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In this paper, a new spectrophotometric method is reported for the determination of nanomolar levels of Eriochrome black T in environmental samples. The method is based on the catalytic effect of silver nanoparticles on the oxidation of Eriochrome black T by hexacyanoferrate (III) in acetate–acetic acid medium and at 25 °C. The absorbance is measured at 512 nm with the fixed-time method. It relies on the linear relationship between the absorbance difference (∆A) and Eriochrome black T amounts in the range of 40–1,250 nM. Under optimum conditions, the sensitivity of the proposed method, i.e., the detection limit corresponding to 80 s, is about 25 nM. The method is featured with good accuracy and reproducibility for Eriochrome black T determination in river water samples without any pre-concentration and separation step. | Surfactant-stabilized silver hydrosol, organosol, reverse micelle-stabilized sol, and their dry products have been prepared and characterized. The dry products can be handled as chemical compounds. Solubility and spectral study of dry products show similar microenvironments for the organo- and reverse-micellized sol. For the conversion of hydrosol into organosol, the surfactant acts as phase transfer catalyst. The study shows that a solvent–surfactant system for which the surfactant can form a reverse micelle is effective for phase transfer of particles from aqueous to organic phase. | Field correctors for a one-meter, f/15 cassegrainian telescope were designed as part of a NASA-funded study of an astronomical observatory on board of the space shuttle. By means of a Gasgoigne corrector and a biconcave field flattener, astigmatism and field curvature are corrected in a 0.6° field. Applicable wavelength ranges are limited by chromatic aberrations. The upper wavelength is selected to match a photocathode response limit. The lower wavelength limit is defined by a filter. Examples of usable wavelength ranges are: 210 nm - 1100 nm (multialkali photocathode, fused-silica corrector elements), 177 nm -320 nm (cesium telluride photocathode, calcium fluoride correctors); and possibly 134 nm -133 nm (cesium iodide photocathode, lithium fluoride correctors). Residual rms lateral color is smaller than 0.02 arc sec, and axial color is smaller than 0.25 arc sec (blur diameter at the ends of the wavelength range). The correctors introduce a small amount of coma. This is compensated by adjustment of the conic constants of the telescope mirrors. | eng_Latn | 8,900 |
The introduction of isolated genes or recombinant DNA into cultured cells is a key procedure in cell and molecular biological research. At present there are many methods for gene transfer. All of these methods have certain shortcomings. Most of them are strongly cell-type dependent (i.e., they can work only on certain cells), and the transfer efficiency is frequently unsatis- factorily low. Furthermore, these methods often produce un- desirable biological or chemical side-effects. Recently, a new physical method has been developed ( 1). The cell membrane can be temporarily permeabilized by exposing the cell to a pulse of high intensity electric field (2). This process is attributed to the creation of resealable pores in the cell mem- brane and is thus called “electroporation.” The electroporation method offers more advantages than most other methods. First, it is simple to use and is time efficient. It can also be used to inject a single cell or millions of cells. Second, because it is a physical method, electroporation is less dependent on cell type. Third, it has fewer harmful biological and chemical side effects. In the last several years, the electroporation method has been successfully used to introduce cloned genes into a wide variety of cells, including mammalian cell lines, isolated cells, plant cells, bacteria, and yeast (3, 4). In addition to gene transfer, electroporation has the potential for use as a micro-injection method to introduce molecules other than DNA, such as second messengers, kinases, and kinase in- hibitors, drugs, and antibodies into a large number of cells. We are currently working to improve this technology. Our approach is to experiment with different wave forms and pulse protocols and to test their effects on cell survival rate and transfection efficiency. Our earlier results had suggested that, by | In order to identify neuronal networks, it is generally required to fix tissue followed by some specific staining procedure. A new procedure is described in this manuscript that labels brain slices that are routinely used for electrophysiological analyses. Fluorescently-labeled lipids can be incorporated into brain slices via passive exchange from exogenously applied vesicles. The labeled lipid is distributed throughout distinct cellular structures of the hippocampus and cerebellum. High resolution images of cells can be obtained and as the labeling process does not affect the electrical properties of the labeled cells, further electrophysiological analyses can be made of identifiable cells. The distribution of the lipid depends on the labeled phospholipid species. One of the lipids analyzed has been previously used for in vitro phospholipase analyses. Addition of phospholipase activating agents resulted in identification with high spatial and temporal resolution of activation of this enzyme in specific cell types. The cells affected correlated with previously identified regions of relevant pharmacological activity. This procedure shows considerable promise for monitoring biochemical changes due to physiological, toxicological, or pathological changes in intact neuronal networks.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 8,901 |
Antibody detection and accurate diagnosis of tropical diseases is essential to help prevent the spread of disease. However, most detection methods lack cost-effectiveness and field-portability, which are essential features for achieving diagnosis in a timely manner in developing countries. To address this problem, transparent 3D printed sample chambers with a total volume of 700 microliters and an oblate spheroid shape were fabricated to measure green light scattering of gold nanoparticles using an optical caustic focus to detect antibodies. Scattering signals from 90 degree scattering of 20, 40, 50, 60, 80, 100, and 200 nm gold nanoparticles using a green laser and standard quartz cuvette were compared to the scattering signals from a green LED light source with an oblate spheroid sample chamber and to Mie theory by fitting the data to a logistic curve. The change in signal from 60 nm to 120 nm decreased in the order of Mie Theory > Optical Caustic scattering > standard laser 90 degree scattering. These results suggested that conjugating 60 nm gold nanoparticles with Dengue Protein E and using an optical caustic system to detect plasmonic light scattering would result in a sensitive test for detecting human antibodies against Dengue Protein E in serum. To explore this possibility, we studied the light scattering response of protein E conjugated gold nanoparticles exposed to different concentrations of anti-protein E antibody, and posteriorly via a feasibility study consisting of 10 human serum samples using a modified dot blot protocol and a handheld optical caustic-based sensor device. The overall agreement between the benchtop light scattering and dot blot results and the handheld optical caustic sensor suggest that the new sensor concept shows promise to detect gold nanoparticle aggregation caused by the presence of the antibody using a homogeneous assay. Further testing and protocol optimization is needed in order to draw conclusions on the positive predictive and negative predictive values for this new testing system. | Sylvatic dengue viruses are both evolutionarily and ecologically distinguishable from the human dengue virus (DENV). Sporadic episodes of sylvatic human infections in West Africa and Southeast Asia suggest that sylvatic DENV regularly come into contact with human beings. Following a study on the sylvatic transmission cycle in Malaysia in 2007, researchers announced that a new DENV serotype, DENV-5, had been discovered. Scientists are still sceptical about these new findings, and indicate that more data is necessary to determine whether this 'new' virus really is a different serotype or whether it is a variant of one of the four DENV serotypes already known. The good news is that this new variant has not yet established itself in the human transmission cycle. However, if it really is a new serotype this will have implications for the long-term control of dengue using vaccines currently under development. | We report nearly complete preservation of “spin memory” between optical absorption and photoluminescence under excitation >0.2 eV above the band gap in nanometer GaSe slabs. | eng_Latn | 8,902 |
The silkworm moth escapes from the pupal-protection case by utilizing cocoon-digesting enzymes. The rectal sac was examined in relation to the behaviour of the animal. Pupae and pharate adults were obtained from commercial races and were reared in the laboratory. The ball-shaped rectal sac, easily distinguishable within the abdomen of the silkworm, was found to contain two phased creamy fluid. The occurance and the shape of the organ and the usage of its fluid suggest its role in perforation of the cocoon. | The rectal sac (Rs) is formed by enlargement of the rectal portion of the hindgut in Bombyx mori. The Rs consists of epithelium, connective tissue, and many rectal pads (Rps). Rps have a cortex and medulla. In the medulla 2- 5 pyramidal epithelial cells synthesize proteinic secretory material (Ps), and then this substance localizes within epithelial cells and connective tissue. It was thought that lipoid secretory material (Ls) was synthesized by epithelial cells in the midgut and was delivered to the Rs; however, Ls was localized in the epithelium of the Rs and in the periphery of Rps. Both secretions were released into the lumen of the Rs. Thus, the synthesis and accumulation of the secretory material increased as the pupa developed, and the Rs gradually grew. In some insects Rps are covered with a peritrophic matrix, which extends backward from the midgut and epithelium. As the larvae grew, depending on development, it was observed that the Rps decreased in number, but that degradation of the Rps gradually increased. This degradation was also observed as the epithelium that covers the Rs thickened and became corrupted. It was thought that the Rs could be responsible for enabling escape from the pupal case at the end of pupal development. | Advanced air quality control requires real-time monitoring of particulate matter size and concentration, which can only be done using optical instruments. However, such techniques need regular calibration with reference samples. In this study, we suggest that puffball fungus (Lycoperdon pyriforme) spores can be utilized as a reference standard having a monodisperse size distribution. We compare the Lycoperdon pyriforme spores with the other commonly used reference samples, such as Al2O3 powder and polystyrene latex (PSL) microspheres. Here we demonstrate that the puffball spores do not coagulate and, thus, maintain the same particle size in the aerosol state for at least 15 minutes, which is enough for instrument calibration. Moreover, the puffball mushrooms can be stored for several years and no agglomeration of the spores occurs. They are also much cheaper than other calibration samples and no additional devices are needed for aerosol generation since the fungal fruiting body acts as an atomizer itself. The aforementioned features make the fungal spores a highly promising substance for calibration and validation of particle size analyzers, which outperforms the existing, artificially produced particles for aerosol sampling. Furthermore, the L. pyriforme spores are convenient for basic research and development of new optical measurement techniques, taking into account their uniform particle size and absent coagulation in the aerosol. | eng_Latn | 8,903 |
This work aims at the development of a fast scanning method for organic pollutants with low-cost small Raman spectrometers. A gold nanoparticles-embedded alginate gel is prepared and applied as the substrate for surface enhanced Raman spectrometric detection of polycyclic aromatic hydrocarbons (PAHs). The target molecules are captured by the three-dimensional network of the alginate gel, and brought close to the hot spots generated by gold nanoparticles embedded in the gel. Significant Raman enhancement effects are observed in the analysis of four typical PAH compounds including pyrene, anthracene, fluorene and benzo(a)pyrene. Quantitative analysis of BaP shows a limit of detection of 0.365 nM using a low-cost small Raman spectrometer, which is comparable to published values. The practicability of the method is tested by analyzing PAHs in different water samples, offering a fast scanning method for PAHs. | The multi-parameter measurement has significant meaning for biosensor to enhance their practical sensing performance. For the biological detection, simultaneous measurement of biological molecule and flow rate could improve the accuracy and sensitivity of sensors significantly. In this paper, an integrated biological analysis and flow rate sensing based on Co2+ doped tilted fiber Bragg gratings has been proposed and experimentally demonstrated for real-time the detection of the Benzo[a]pyrene molecules. A tilted fiber Bragg grating with a tilted angle of 8° was inscribed into a Co2+ doped fiber. The flow rate and Benzo[a]pyrene molecules can be measured simultaneously by interrogating the resonance wavelength of core mode and wavelength interval between the core mode and cladding mode according to the heat exchange and evanescent field of the cladding mode, respectively. Experimental results show that the real-time measurement sensitivities of 12 pm/pM and −0.13 nm/( $\mu \text{L}$ /s) for the Benzo[a]pyrene detection and flow rate were achieved, respectively. Thus the technique appears to have potential applications in chemistry, medicine, and biology. | HIV-positive patients receiving combination therapy (highly active anti-retroviral treatment, HAART) suffer significantly fewer oral infections with the opportunistic fungal pathogen Candida albicans than non-HAART-treated patients. One component of HAART is an inhibitor of the HIV proteinase, the enzyme required for correct processing of retroviral precursor proteins. It would appear that HIV proteinase inhibitors also have a direct effect on one of the key virulence factors of C. albicans , the secreted aspartic proteinases (Saps). This suggests that the reduction in C. albicans infections in HIV-positive patients might not be solely the result of improved immunological status but could also be caused by the HAART treatment directly inhibiting Candida proteinases. | eng_Latn | 8,904 |
Genetically coded fluorescent protein (FP)-based biosensors are powerful tools for the non-invasive tracking of molecular events in living cells. Although a variety of FP biosensors are available, the simultaneous imaging of multiple biosensors (multi-parameter imaging) in single living cells remains a challenge and is far from routinely used to elucidate the intricate networks of molecular events. In this study, we established a novel combination of FP biosensors for dual-parameter ratiometric imaging, consisting of a new fluorescence resonance energy transfer (FRET) pair mVenus (yellow FP)/mKOκ (orange FP)-based (abbreviated as YO) biosensor and a single FP-based biosensor Grx1-roGFP2. Under our imaging condition, 1.4±0.05% of Grx1-roGFP2 signal contributes to the mVenus channel and 5.2±0.12% of the mVenus signal contributes to the Grx1-roGFP2 channel. We demonstrate that such low degree of cross-talk causes negligible distortion of the ratiometric signal of the YO-based FRET biosensor and Grx1-roGFP2. By using this dual-parameter ratiometric imaging approach, we achieved simultaneous imaging of Src/Ca(2+) signaling and glutathione (GSH) redox potential in a single cell, which was previously unattainable. Furthermore, we provided direct evidence that epidermal growth factor (EGF)-induced Src signaling was negatively regulated by H(2)O(2) via its effect on GSH-based redox system, demonstrating the power of this dual-parameter imaging approach for elucidating new connections between different molecular events that occur in a single cell. More importantly, the dual-parameter imaging approach described in this study is highly extendable. | The surface of CdTe quantum dots (Q-dots) was modified with thioglycolic acid (TGA) and these Q-dots were then covalently conjugated to amino-functionalized silica-coated carbon dots (C-dot@SiO2) via carbodiimide chemistry. The Q-dots form kind of “satellites” on the surface of the C-dot@SiO2 nanoparticles. The nanoparticle conjugates display dual emission (with peaks at 441 nm and 605 nm) under UV excitation and were further characterized by transmission electron microscopy, UV–vis absorption and FTIR spectroscopy. The C-dot@SiO2@Q-dots hybrid spheres are shown to represent a ratiometric fluorescent probe for Cu2+ in that the emission of the Q-dots is quenched by Cu2+, while the emission of the C-dots (which are coated with SiO2) is not quenched. The ratio of the fluorescence intensities at 441 and 655 nm is related to the concentration of Cu2+ in the range from 0.1 to 1.0 μM, with a 0.096 μM lower detection limit. The ratiometric probe was successfully applied to the determination of Cu2+ in (spiked) vegetable and fruit samples by the standard addition method, and recoveries ranged from 96.7 to 100.8 %. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 8,905 |
Copper (II) phthalocyanine derivatives with four alkyl chains were synthesized. Langmuir-Blodgett (LB) films of the following two compounds were deposited: Cu(II)[tetrakis(3,3-dimethyl-butoxycarbonyl)] phthalocyanine and Cu(II)[tetrakis(n-butoxycarbonyl)] phthalocyanine. Moreover, LB films from a 1:1 mixture of the two compounds were prepared. All isotherms and optical data were consistent with the molecules being stacked nearly edge-on to the substrate, with the molecular faces having a preferred orientation perpendicular to the dipping direction. The dynamic response characteristics of the electrical conductance of the LB films to different NO2 concentrations in dry air are described. A relationship has been observed between the anisotropic molecular orientation and the electrical conductivity parallel to the substrate. | A novel highly sensitive optical NO 2 -selective sensor was developed using phthalocyaninato-iron(II) as a selective complexing agent. In order to solubilize the iron II+ phthalocyanine and to obtain the monomer species, a N-donor ligand was used as a solvent. The membrane solution was deposited onto a novel aluminum oxide/hydroxide nanoporous material by a spin-coating technique. The chemical reaction principle and the preparation of this new sensor are presented in detail. The effect of the type and concentration of the N-donor ligand, and the influence of the iron phthalocyanine concentration were investigated as well as the effect of the composition and the morphological characteristics of the nanostructured material. In addition, the influence of some relevant external parameters such as flow-rate and interfering compounds were investigated. The results show that the sensor responds to NO 2 concentrations in the gas phase between 5 × 10 −3 ppm and >0.5 ppm with a linear concentration range between 2 × 10 −2 and 0.4 ppm, the detection limit being at 20 ppb. The dynamic range it is not influenced by the flow-rate, by humidity, NO, CO, CO 2 and SO 2 , and the NO 2 -selective optical sensor shows good stability to ambient in view of a long lifetime as a gas and fire alarm detector. Generally 1 ppm NO 2 gas corresponds to 2.0 mg m −3 and 44.5 × 10 −6 mol m −3 . | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 8,906 |
In this study, in situ surface-enhanced Raman scattering (SERS) spectroelectrochemistry and angle-resolved X-ray photoelectron spectroscopy (AR-XPS) are used to investigate the redox reaction and adsorption behavior of anthraquinone-2-carboxylic acid (AQ-2-COOH) on an Ag electrode at different pH values. The obtained results indicate that AQ-2-COOH is adsorbed tilted on the Ag electrode through O-atom of ring carbonyl in a potential range from −0.3 to −0.5 V vs. SCE, but the orientation turns to more tilted orientation with both O-atom of the ring carbonyl and carboxylate group in positive potential region for pH 6.0 and 7.4. However, at pH 10.0, the orientation adopts tilted conformation constantly on the Ag electrode with both O-atom of the anthraquinone ring and carboxylate group in the potential range from −0.3 to −0.5 V vs. SCE or at positive potentials. Moreover, the adsorption behavior of AQ-2-COOH has been further confirmed by AR-XPS on the Ag surface. Proposed reasons for the observed changes in orientation are presented. | A method is described for surface-enhanced Raman scattering (SERS) discrimination of formaldehyde (FA) and acetaldehyde (AA) in aqueous sample solutions. It is based on the use of a paper strip containing 4-aminothiophenol (Atp)-modified reduced graphene oxide (rGO)/[Ag(NH3)2]+ (rGO/[Ag(NH3)2]+/Atp). The addition of FA or AA induces the conversion of [Ag(NH3)2]+ complex to silver nanoparticles (AgNPs) because of aldehyde-induced silver reduction reaction. The AgNPs possess strong SERS activity. The average interparticle gaps between the AgNPs can be fine-tuned by controlling the experimental conditions, this leading to the formation of optimized SERS hot spots. It is also found that the changes in the spectral shapes and the relative intensity ratio of the bands at 1143 and 1072 cm−1 result from the difference in the pH value of the surrounding solution. This effect enables the selective discrimination of FA and AA. The paper strip can be used as a SERS dipstick and swab for on-site determination of FA or AA in wine and human urine via the differences in the intensity of the SERS peaks. The assay works over a wide range of concentrations (0.45 ng·L−1 to 480 μg·L−1) for FA and AA, and the respective detection limits are 0.15 and 1.3 ng·L−1. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 8,907 |
Blood-compatible surfaces prepared through deposition onto steel substrates of colloidal particles composed of heparin or dextran sulfate reacted with hexadecylammonium chloride, and chemically related surfaces, have been analyzed by means of ESCA in order to explore the detailed surface chemistry prior to and after exposure to an albumin solution. In particular it has been shown that the stabilization of the ionic heparin and dextran sulfate hexadecylammonium chloride complexes resulting from reaction with glutaraldehyde is associated with a partial chemical transformation of the hexadecylammonium ion to the corresponding Schiff's base compound. Furthermore, the ESCA S2p peaks due to disulfide bonds and sulfate groups provide evidence for distinctly different albumin adsorption characteristics on the heparin-glutar and dextran sulfate-glutar surfaces. Both of these surfaces exhibit minimal platelet adhesion. However, it is only the heparin-glutar surface that promotes the inhibition of thrombin activity at blood contact. | In this article, we report on the formation and mode-of-operation of an affinity biosensor, where alternate layers of biotin/streptavidin/biotinylated-CRP-antigen/anti-CRP antibody are grown on printed gold electrodes on disposable paper-substrates. We have successfully demonstrated and detected the formation of consecutive layers of supra-molecular protein assembly using an electrical (impedimetric) technique. The formation process is also supplemented and verified using conventional surface plasmon resonance (SPR) measurements and surface sensitive characterization techniques, such as X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The article provides a possible biosensor development scheme, where-(1) fabrication of paper substrate (2) synthesis of gold nanoparticle inks (3) inkjet printing of gold electrodes on paper (4) formation of the biorecognition layers on the gold electrodes and (5) electrical (impedimetric) analysis of growth-all are coupled together to form a test-structure for a recyclable and inexpensive point-of-care diagnostic platform. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 8,908 |
Unilamellar phospholipid vesicles prepared using the polymerizable lipid bis-sorbylphosphatidylcholine (bis-SorbPC) yield three-dimensional nanoarchitectures that are highly permeable to small molecules. The resulting porous phospholipid nanoshells (PPNs) are potentially useful for a range of biomedical applications including nanosensors and nanodelivery vehicles for cellular assays and manipulations. The uniformity and size distribution of the pores, key properties for sensor design and utilization, have not previously been reported. Fluorophore-assisted carbohydrate electrophoresis (FACE) was utilized to assess the nominal molecular weight cutoff limit (NMCL) of the PPN via analysis of retained dextran with single monomer resolution. The NMCL of PPNs prepared from pure bis-SorbPC was equivalent to a 1800 Da linear dextran, corresponding to a maximum pore diameter of 2.6 nm. Further investigation of PPNs prepared using binary mixtures of bis-SorbPC and dioleoylphosphatidylcholine (DOPC) revealed a simila... | A porous phospholipid nanoshell (PPN) sensor functionalized with a specific aptamer sensor agent was prepared for rapid detection of Hg(2+) in human urine with minimal sample preparation. Aptamer sensors provide an important class of optical transducers that can be readily and reproducibly synthesized. A key limitation of aptamer sensors, and many other optical sensors, is the potential of biofouling or biodegradation when used in complex biological matrices such as serum or urine, particularly when high levels of nucleases are present. We prepared Hg(2+)-responsive, PPN-encapsulated aptamer sensors that overcome these limitations. PPNs provide a protective barrier to encapsulate the aptamer sensor in an aqueous environment free of diffusional restrictions encountered with many polymer nanomaterials. The unique porous properties of the PPN membrane enable ready and rapid transfer of small molecular weight ions and molecules into the sensor interior while minimizing the macromolecular interactions between the transducer and degradants or interferents in the exterior milieu. Using Hg(2+)-responsive, PPN-encapsulated aptamer sensors, we were able to detect sub-100 ppb (chronic threshold limit from urine test) Hg(2+) in human urine with no sample preparation, whereas free aptamer sensors yielded inaccurate results due to interferences from the matrix. The PPN architecture provides a new platform for construction of aptamer-functionalized sensors that target low molecular weight species in complex matrices, beyond the Hg(2+) demonstrated here. | Background ::: Serum calcium (Ca) and inorganic phosphate (Pi) concentrations and calcium-phosphate product (CPP) levels are positively associated with worse outcomes in patients with chronic kidney disease, but there are few data for Pi or Ca and none for CPP in patients with chronic heart failure (CHF). | eng_Latn | 8,909 |
This paper presents a new method to measure the constituents of the milk, which uses the scattered light to transmitted ::: light rate of the laser(called s-t rate for short) to detect the protein and fat content of the milk. The basic theory is ::: discussed in the test in detail and the feasibility of the plan is analyzed. A relation curve between the fat and protein of ::: milk and the ratio is built by multiple linear regression method. The uncertainty of the result is mentioned in the paper. | It is possible to relate the response of a sphere to an applied uniform static electric field with the scattering from a small spherical particle due to plane wave incidence. The limits up to which these relations between the polarizability and the extinction, scattering, and radar cross sections of a sphere are valid in the dynamic range are presented here. From the observations it can be concluded that radar cross section is a very good measure in predicting the polarizability. A related aspect studied here is the evaluation of the effective permittivity of a sparse mixture of spherical inclusions using a generalized Maxwell Garnett mixing rule. This is compared with extinction of a plane wave by a slab of n spherical inclusions sparsely located. The extinction by such a slab is calculated using the quasistatic approximation to Mie theory, and also using the full Mie theory, as the size of the inclusions is increased. The studies have been carried out for both lossless and lossy inclusions. The generalized mixing rule was found to be quite accurate in predicting the value of effective permittivity up to size parameters of 0.5 at least for small er of the inclusion. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 8,910 |
Klebsormidium flaccidum algal cells exhibiting the ability to form gold nanoparticles intra-cellularly in suspension were encapsulated within silica gels. Optical and electronic microscopy indicate that entrapped cells maintain their ability to reduce gold salts. A difference in the kinetics of gold colloid formation within silica in the absence or presence of cells could be followed by UV-visible absorption spectroscopy, confirming the bio-mediated nature of the reduction process. Study of the photosynthetic activity of the algae showed that the encapsulation process protects the cells from lethal effects arising from gold toxicity. Moreover, the first in situ imaging of entrapped cells using Raman spectroscopy allowed the investigation of the influence of the gold colloids on the photosynthetic system of the algae, in particular through modification of chlorophyll fluorescence and carotenoid signals. Such a coupling of sol–gel encapsulation and Raman imaging should allow the future development of novel photosynthesis-based cellular biosensors. | We present a comprehensive review of the applications of biosynthesized metallic nanoparticles (NPs). The biosynthesis of metallic NPs is the subject of a number of recent reviews, which focus on the various ‘‘bottom-up’’ biofabrication methods and characterization of the final products. Numerous applications exploit the advantages of biosynthesis over chemical or physical NP syntheses, including lower capital and operating expenses, reduced environmental impacts, and superior biocompatibility and stability of the NP products. The key applications reviewed here include biomedical applications, especially antimicrobial applications, but also imaging applications, catalytic applications such as reduction of environmental contaminants, and electrochemical applications including sensing. The discussion of each application is augmented with a critical review of the potential for continued development. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 8,911 |
A versatile approach based on nanosphere lithography is proposed to generate surface-imprinted polymers for selective protein recognition. A layer of 750 nm diameter latex bead-protein conjugate is deposited onto the surface of gold-coated quartz crystals followed by the electrosynthesis of a poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) film with thicknesses on the order of the bead radius. The removal of the polymer bead-protein conjugates, facilitated by using a cleavable protein-nanosphere linkage is shown to result in 2D arrays of periodic complementary size cavities. Here it is demonstrated by nanogravimetric measurements that the imprinting proceeds further at molecular level and the protein (avidin) coating of the beads generates selective recognition sites for avidin on the surface of the PEDOT/PSS film. The binding capacity of such surface-imprinted polymer films is ca. 6.5 times higher than that of films imprinted with unmodified beads. They also exhibit excellent selectivity against analogues of avidin, i.e., extravidin, streptavidin, and neutravidin, the latter being in fact undetectable. This methodology, if coupled with properly oriented conjugation of the macromolecular template to the nanoparticles, offers the possibility of site-directed imprinting. | Molecularly imprinted polymers (MIPs) have the potential to complement antibodies in bioanalysis, are more stable under harsh conditions, and are potentially cheaper to produce. However, the affinity and especially the selectivity of MIPs are in general lower than those of their biological pendants. Enzymes are useful tools for the preparation of MIPs for both low and high-molecular weight targets: As a green alternative to the well-established methods of chemical polymerization, enzyme-initiated polymerization has been introduced and the removal of protein templates by proteases has been successfully applied. Furthermore, MIPs have been coupled with enzymes in order to enhance the analytical performance of biomimetic sensors: Enzymes have been used in MIP-sensors as “tracers” for the generation and amplification of the measuring signal. In addition, enzymatic pretreatment of an analyte can extend the analyte spectrum and eliminate interferences. | Solar cells, as promising devices for converting light into electricity, have a dramatically reduced performance on rainy days. Here, an energy harvesting structure that integrates a solar cell and a triboelectric nanogenerator (TENG) device is built to realize power generation from both sunlight and raindrops. A heterojunction silicon (Si) solar cell is integrated with a TENG by a mutual electrode of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film. Regarding the solar cell, imprinted PEDOT:PSS is used to reduce light reflection, which leads to an enhanced short-circuit current density. A single-electrode-mode water-drop TENG on the solar cell is built by combining imprinted polydimethylsiloxane (PDMS) as a triboelectric material combined with a PEDOT:PSS layer as an electrode. The increasing contact area between the imprinted PDMS and water drops greatly improves the output of the TENG with a peak short-circuit current of ∼33.0 nA and a peak open-circuit voltage of ∼2.14 V, res... | eng_Latn | 8,912 |
The increasing use of nanoparticles (NP) in commercial products requires elaborated techniques to detect NP in the tissue of exposed organisms. However, due to the low amount of material, the detection and exact localization of NP within tissue sections is demanding. In this respect, Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and Ion Beam Microscopy (IBM) are promising techniques, because they both offer sub-micron lateral resolutions along with high sensitivities. Here, we compare the performance of the non-material-consumptive IBM and material-consumptive ToF-SIMS for the detection of ZrO2 NP (primary size 9–10 nm) in rat lung tissue. Unfixed or methanol-fixed air-dried cryo-sections were subjected to IBM using proton beam scanning or to three-dimensional ToF-SIMS (3D ToF-SIMS) using either oxygen or argon gas cluster ion beams for complete sample sputtering. Some sample sites were analyzed first by IBM and subsequently by 3D ToF-SIMS, to compare results from exactly the same site. Both techniques revealed that ZrO2 NP particles occurred mostly agglomerated in phagocytic cells with only small quantities being associated to the lung epithelium, with Zr, S, and P colocalized within the same biological structures. However, while IBM provided quantitative information on element distribution, 3D ToF-SIMS delivered a higher lateral resolution and a lower limit of detection under these conditions. We, therefore, conclude that 3D ToF-SIMS, although not yet a quantitative technique, is a highly valuable tool for the detection of NP in biological tissue. | Secondary Ion Mass Spectrometry (SIMS) enables surface chemical analysis of nano-scaled objects and chemical imaging of nano-scaled details of natural or artificial objects. This review presents the state of the art in nanoscale SIMS analysis. At first a short introduction into recent instrumentation for high resolution SIMS imaging and the limiting factors of lateral resolution is given. The next section covers the chemical analysis of nanoparticles. Recent applications of nanoscale imaging SIMS in geology, cosmochemistry, materials research, cellular biology, ecology and medical research are summarized and illustrated by examples. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 8,913 |
The infrared absorption spectra and corresponding dispersion spectra of the following liquids have been measured over the range 4200 to 250 cm−1: cyclo-C5H10, CH3•NO2, CH3•CN, CH2Br2, CH2Cl2, CBrCl3, CCl4, C6H6, C6H5•CH3, C6H5Cl, C6H5Br, C6H5I, and C6F6. The spectra were measured in the absence of solvent and the results are reported as the real and imaginary components of the complex refractive index (n, k). The experimental technique combines transmission measurements through thin films and attenuated total reflection measurements by a method which has been described previously. The complete spectral and dispersion curves are displayed graphically; the absorption maxima are tabulated as absorption indices (kmax) and as molar absorption coefficients (emax). The dispersion extrema (nmin, nmax) are also listed and the experimental uncertainties in these quantities are evaluated. Provision is made to supply the complete optical constant data on magnetic tape at encoded intervals of 0.5 cm−1. | The complex optical refractive index contains the optical constants, n(ῦ)and k(ῦ), which correspond to the dispersion and absorption of light within a medium, respectively. By obtaining the optical constants one can in principle model most optical phenomena in media and at interfaces including reflection, refraction and dispersion. We have developed improved protocols based on the use of multiple path lengths to determine the optical constants for dozens of liquids, including organic and organophosphorous compounds. Detailed description of the protocols to determine the infrared indices will be presented, along with preliminary results using the constants with their applications to optical modeling. | We characterize stability under composition, inversion, and solution of ordinary differential equations for ultradifferentiable classes, and prove that all these stability properties are equivalent. | eng_Latn | 8,914 |
Direct current magnetron sputtering (dcMS) is a widely used technique for deposition of a large number of compound and metallic coatings with specified mechanical, electrical and optical properties ... | Carrying out molecular Dynamics simulations is a relevant way for understanding growth phenomena at the atomic scale. Initial conditions are defined for reproducing deposition conditions of plasma sputtering experiments. Two case studies are developed for highlighting the implementation of molecular dynamics simulations in the context of plasma sputtering deposition: ZrxCu1-x metallic glass and AlCoCrCuFeNi high entropy alloy thin films deposited onto silicon. Effects of depositing atom kinetic energies and atomic composition are studied in order to predict evolution of morphologies and atomic structure of MD grown thin films. Experimental and simulated X-ray diffraction patterns are compared. | Differential ion mobility spectrometry (DMS) spatially separates ions in the gas phase using the mobility differences of the ions under applied low and high electric fields. The use of DMS as an ion filter (or ion selector) prior to mass spectrometry analysis has been compromised by the limited ion transmission efficiency. This paper reports enhancement of the DMS-MS sensitivity and signal stability using a modified CaptiveSpray™ source. In terms of the ion sampling and transmission efficiency, the modified CaptiveSpray source swept ~ 89% of the ions generated by the tapered capillary through the DMS device (compared to ~ 10% with a conventional microspray source). The signal fluctuation improved from 11.7% (relative standard deviation, RSD) with microspray DMS-MS to 3.6% using CaptiveSpray-DMS-MS. Coupling of LC to DMS-MS via the modified CaptiveSpray source was simple and robust. Using DMS as a noise-filtering device, LC-DMS-MS performed better than conventional LC-MS for analyzing a BSA digest standard. Although LC-DMS-MS had a lower sequence coverage (55%), a higher Mascot score (283) was obtained compared to those of LC-MS (sequence coverage 65%; Mascot score 192) under the same elution conditions. The improvement in the confidence of the search result was attributed to the preferential elimination of noise ions. Graphical ᅟ. | eng_Latn | 8,915 |
The equilibrium potentiometric (EMF) response of a previously reported polymer membrane-based heparin sensitive electrode toward heparin and other macromolecular polyanions is examined in detail. The precise structure of the lipophilic tetraalkylammonium anion-exchange sites doped within the plasticized poly(vinyl chloride) membrane phase of the sensor is found to play a critical role in the extraction of the polyanions into such membranes. The influence of polyion charge density and molecular weight (chain length) for a series of structurally similar polyanions (sulfonated/carboxylated polysaccharides) on the membrane's EMF response is also studied. It is found that the membrane potential becomes more negative (for given mass/volume concentration of polyion) with an increase of polyion molecular weight up to 3800 for heparin-like structures. In addition, a greater overall equilibrium response is observed as the charge density of the polyanion increases. The observed role of polyanion structure on the membrane's equilibrium EMF response can be explained by a favorable ion-pair formation between the lipophilic anion-exchanger sites in the membrane and the extracted polyanions. The free energy change for such ion-pair formation can be estimated by comparing the membrane's equilibrium EMF response toward a given polyion to that of a second polymeric membrane doped with anion-exchange sites that do not form strong ion pairs with polyanionic macromolecules. The influence of the sample background electrolyte concentration on the extraction behavior of different polyions is also examined. | A flow injection system incorporated with a polycation-sensitive polymeric membrane electrode in the flow cell is proposed for potentiometric determination of heparin. An external current in nano-ampere scale is continuously applied across the polymeric membrane for controlled release of protamine from the inner filling solution to the sample solution, which makes the electrode membrane regenerate quickly after each measurement. The protamine released at membrane-sample interface is consumed by heparin injected into the flow cell via their strong electrostatic interaction, thus decreasing the measured potential, by which heparin can be detected. Under optimized conditions, a linear relationship between the potential peak height and the concentration of heparin in the sample solution can be obtained in the range of 0.1-2.0 U mL(-1), and the detection limit is 0.06 U mL(-1). The proposed potentiometric sensing system has been successfully applied to the determination of heparin in undiluted sheep whole blood. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 8,916 |
Cavity ring-down spectroscopy (CRD-S) is widely adapted for studying light extinction by aerosol in laboratory and field studies. The complex refractive index (RI) of an aerosol can be retrieved by finding the theoretical Mie theory curve that best fits the measured extinction efficiency for as many aerosol diameters as possible. In this study, we introduce a new retrieval approach for the complex RI of aerosols using extinction measurements at only two carefully selected size parameters. We show that for three model substances measured (ammonium sulfate, Suwannee river fulvic acid, and nigrosin) and for 22 other reanalyzed datasets, the “2-points” measurement approach enables the retrieval of complex refractive indices with comparable uncertainty to the traditional measurement and retrieval procedure. The advantages and disadvantages of the new approach are discussed. Copyright 2012 American Association for Aerosol Research | Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross sections and complex refractive indices. We describe a new laboratory instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360–390 and 385–420 nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We determined aerosol extinction cross sections and directly observed Mie scattering resonances for aerosols that are purely scattering (polystyrene latex spheres and ammonium sulfate), slightly absorbing (Suwannee River fulvic acid), and strongly absorbing (nigrosin dye). We describe an approach for retrieving refractive indices as a function of wavelength from the measured extinction cross sections over the 360–420 nm wavelength region. The retrieved refractive indices for PSL and ammonium sulfate agree within uncertainty with the literature values for this spectral region. The refractive index determined for nigrosin is 1.78 (± 0.03) + 0.19 (± 0.08)i at 360 nm and 1.63 (± 0.03) + 0.21 (± 0.05)i at 420 nm. The refractive index determined for Suwannee River fulvic acid is 1.71 (± 0.02) + 0.07 (± 0.06)i at 360 nm and 1.66 (± 0.02) + 0.06 (± 0.04)i at 420 nm. These laboratory results support the potential for a field instrument capable of determining ambient aerosol optical extinction, average aerosol extinction cross section, and complex refractive index as a function of wavelength. | Distillation at an infinite reflux ratio in combination with an infinite number of trays has been investigated. | eng_Latn | 8,917 |
Highly Photosensitive J‐Aggregated Single‐Crystalline Organic Transistors | Flexible Field-Effect Transistor-Type Sensors Based on Conjugated Molecules | Combining activated carbon adsorption with heterogeneous photocatalytic oxidation: Lack of synergy for biologically treated greywater and tetraethylene glycol dimethyl ether | eng_Latn | 8,918 |
Equipotential Shells for Efficient Inductance Extraction | Efficient Inductance Extraction using Circuit-Aware Techniques | Lipoprotein Electrophoresis Should Be Discontinued as a Routine Procedure | eng_Latn | 8,919 |
Influence of Plasmonic Au Nanoparticles on the Photoactivity of Fe2O3Electrodes for Water Splitting | Sandwich Fe2O3/Au/Fe2O3 photoanodes for enhanced photoelectrochemical water splitting | High-affinity glucose uptake in Saccharomyces cerevisiae is not dependent on the presence of glucose-phosphorylating enzymes | eng_Latn | 8,920 |
Precise method for continuous measurement of fluorescent microspheres during flow | Author ' s personal copy Colloid transport with wetting fronts : Interactive effects of solution surface tension and ionic strength | Neophobia does not account for motoric self-regulation performance as measured during the detour-reaching cylinder task | eng_Latn | 8,921 |
Strong coupling between localized surface plasmons and point-like emitters within the classical scheme of the discrete dipole approximation | Strong exciton-photon coupling in an organic semiconductor microcavity | Evidence against a role for platelet-derived molecules in liver regeneration after partial hepatectomy in humans | eng_Latn | 8,922 |
Photoinitiated polymerization: Effect of the initiator absorbance | Polymerization kinetics in photopolymer films | High-affinity glucose uptake in Saccharomyces cerevisiae is not dependent on the presence of glucose-phosphorylating enzymes | eng_Latn | 8,923 |
Principle and applications of a new MOEMS spectrometer | First Spectroscopic Study in the Near-Infrared (NIR) of Self-Forming Nano Vesicles | Microtubule capture by CENP-E silences BubR1-dependent mitotic checkpoint signaling | eng_Latn | 8,924 |
Crosslinkable organic glasses with quadratic nonlinear optical activity | Nonlinear Optical Performance of Poled Liquid Crystalline Azo-dyes Confined in SiO 2 Sonogel Films | QSAR model for predicting the toxicity of organic compounds to fathead minnow | eng_Latn | 8,925 |
Mechanism of plasmid-mediated bacteriophage resistance in lactococci | Bacteriophage defence systems in lactic acid bacteria | Novel high-throughput and maskless photolithography to fabricate plasmonic molecules | eng_Latn | 8,926 |
High-Efficiency White Organic Light-Emitting Diodes Based on Phosphorescent Iridium Complex and 4,4'-Bis[N-1-napthyl-N-phenyl-amino]biphenyl Emitters | Study on charge carrier recombination zone with ultrathin rubrene layer as probe | Performance of white organic light-emitting diode for portable optical biosensor | eng_Latn | 8,927 |
Infrared speckle imaging - Improvement of the method; results on Miras and protostars | Application Of Image Sharpness Criteria In Infrared Speckle Interferometry | Transcriptional activation of HIF-1 by a ROS-ERK axis underlies the resistance to photodynamic therapy | eng_Latn | 8,928 |
A piezoelectric immunobiosensor for atrazine in drinking water | 11 Quartz Crystal Microbalance in Clinical Application | Theory and design of piezoelectric resonators immune to acceleration: present state of the art | eng_Latn | 8,929 |
Uncertainty budgets for liquid waveguide CDOM absorption measurements. | Remote sensing of zooplankton swarms | Absence of CCR8 does not impair the response to ovalbumin-induced allergic airway disease. | eng_Latn | 8,930 |
Atomic Force Microscope Imaging Contrast Based on Molecular Recognition | Probing molecular recognition sites on biosurfaces using AFM. | Retinotopic Mapping Requires Focal Adhesion Kinase-Mediated Regulation of Growth Cone Adhesion | eng_Latn | 8,931 |
Theory of the photothermal radiometry with solids | Contact and non-contact photothermal calorimetry for investigation of condensed matter | Normal Pregnancy and Lactation in a Cat after Treatment of Mammary Gland Tumor When Using Photothermal Therapy with Gold Nanorods: A Case Report | eng_Latn | 8,932 |
Multifunctional au nanoparticle dendrimer-based surface plasmon resonance biosensor and its application for improved insulin detection. | PAMAM dendrimer/gold nanoparticle nanocomposites for a reflection LSPR optical fiber sensor | Porin channels in intact cells of Escherichia coli are not affected by Donnan potentials across the outer membrane. | eng_Latn | 8,933 |
Theoretical study of the sensor design strategy for colorimetric sensor array based on density functional theory | A Novel Nanoscaled Chemo Dye–Based Sensor for the Identification of Volatile Organic Compounds During the Mildewing Process of Stored Wheat | No Detectable Broad-Scale Effect of Livestock Grazing on Soil Blue-Carbon Stock in Salt Marshes | eng_Latn | 8,934 |
Photoelectron characteristic of silver chloride microcrystals adsorbing dye excited by laser | Electro‐spin resonance study of positive holes in J‐aggregates of a cyanine dye on AgBr microcrystals: Effect of aggregate size | High-affinity glucose uptake in Saccharomyces cerevisiae is not dependent on the presence of glucose-phosphorylating enzymes | eng_Latn | 8,935 |
Migration induced reorientation and anisotropic grating formation in photoreactive polymer liquid crystals | Facile one-step photopatterning of polystyrene films | High-affinity glucose uptake in Saccharomyces cerevisiae is not dependent on the presence of glucose-phosphorylating enzymes | eng_Latn | 8,936 |
Development of Multi-Membrane Near-Infrared Diode Mass Spectrometer for Field Analysis of Aromatic Hydrocarbons | Continuous monitoring of the activation and activity of [NiFe]-hydrogenases by membrane-inlet mass spectrometry | Dynamical glass in weakly non-integrable many-body systems | eng_Latn | 8,937 |
Interferometric Detection of Single Gold Nanoparticles Calibrated against TEM Size Distributions | Nanomaterials chemistry : recent developments and new directions | Unattended interferometric sensors | eng_Latn | 8,938 |
Emulsion droplet sizing using low-field NMR with chemical shift resolution and the block gradient pulse method | Diffusion‐ordered spectroscopy on a benchtop spectrometer for drug analysis | Completely Stale Transmitter Channel State Information is Still Very Useful | eng_Latn | 8,939 |
Selective plane illumination microscopy techniques in developmental biology. | Getting the whole picture: High content screening using three-dimensional cellular model systems and whole animal assays | Lipoprotein Electrophoresis Should Be Discontinued as a Routine Procedure | eng_Latn | 8,940 |
A Molecularly Imprinted Nicotine-Selective Polymer | Preparation and evaluation of molecularly imprinted polymer liquid chromatography column for the separation of ephedrine enantiomers | Molecularly Imprinted Sensors — New Sensing Technologies | eng_Latn | 8,941 |
[1.1](3,3')-azobenzenophane: novel crystal structure and cis-trans isomerization of distorted azobenzene. | Triptycene-Derived Photoresponsive Fluorescent Azo-Polymer as Chemosensor for Picric Acid Detection | Checking for completeness of 24-h urine collection using para-amino benzoic acid not necessary in the Observing Protein and Energy Nutrition study | eng_Latn | 8,942 |
We have used the electrostatic self-assembly process to grow nanostructured thin films, molecular layer-by-molecular layer, on the ends of silica optical fibers. Such thin films effectively form optical cavities that allow the measurement of temperature by low reflectivity optical Fizeau interferometry. | Multilayer films of organic compounds on solid surfaces have been studied for more than 60 years because they allow fabrication of multicomposite molecular assemblies of tailored architecture. However, both the Langmuir-Blodgett technique and chemisorption from solution can be used only with certain classes of molecules. An alternative approach—fabrication of multilayers by consecutive adsorption of polyanions and polycations—is far more general and has been extended to other materials such as proteins or colloids. Because polymers are typically flexible molecules, the resulting superlattice architectures are somewhat fuzzy structures, but the absence of crystallinity in these films is expected to be beneficial for many potential applications. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 8,943 |
We report a novel method to form a circular pattern of monodisperse microdroplets using an electrohydrodynamic repulsion (EDR) mechanism. EDR is a phenomenon of electrostatical bounced microdroplets from an accumulated droplet on a bottom substrate. In addition to a regular EDR system, by placing a ring electrode between the capillary and ground substrate, two separate regions were created. A parameter study of two regions was carried out for droplet formation and falling velocity to control the radius of the generated droplets and the circular patterns independently. Based on energy conservation theory, our experimental results showed that the free-falling region exerted crucial influences on the sizes of the circular patterns. | Isolated droplets can be used as micro-reactors, yet it is challenging to operate them functionally in solution and observe chemical exchanges between droplets. Here, Tian et al. use an acoustic trap to assemble water-based micro-droplets into periodic arrays, spontaneously separated from solution media. | Background ::: No residual disease (NRD) can be found in the specimen after endoscopic resection (ER) of biopsy-proven gastric neoplasm. This study aimed to evaluate the endoscopic and pathologic characteristics of patients with NRD and identify the cause and long-term prognosis. | eng_Latn | 8,944 |
Local electromagnetic enhancement excited from collective oscillations of free electrons on a highly roughened mental surface can induce greatly enhanced Raman scattering. Herein gold mesoparticles with various morphologies and highly roughened surfaces, including sea urchin-like, flower-like, star-like, meatball-like, and dendritic nanostructures are prepared using pentanol/water interface as a growth “bed”. The morphologies of the prepared gold mesoparticles are well controlled by varying the concentrations of additives such as gold ions, ascorbic acid (AA) and cetyltrimethylammonium bromide (CTAB). Due to the unique structures such as rough surface, high internal porosity as well as complex morphology, these as-prepared mesocrystals exhibit a remarkable performance in surface-enhanced Raman scattering (SERS) compared with polyhedral mesoparticles. | With the development of nanotechnology, the preparation method of surface-enhanced Raman scattering (SERS) substrate has made significant progress, which promotes the application of SERS in food safety, environmental protection, and medical testing. We reported on the fabrication of silver-coated magnetic Fe3O4@phenolic resin (Fe3O4@RF) core–shell particles by a facile solvothermal method, followed by deposition of high-density Ag nanoparticles onto the phenolic resin surfaces through an in-situ reduction process. Analysis of Raman spectroscopy was performed by laser Raman spectrometer. The as-synthesized Ag-coated Fe3O4@RF particles as sensitive SERS substrates showed outstanding SERS performances toward probe molecules of 4-aminothiophenolas with a detection limit of 1 × 10–9 mol L–1. Moreover, the enhancement factor of the substrate was calculated to be about 2.86 × 105. Importantly, profiting from the excellent magnetism, the signal attenuated slightly only after three cycles measurements of SERS based on such composite substrates, indicating that Fe3O4@RF@Ag magnetic composite microspheres possessed the outstanding repeatability. On the basis of these results, it is believed that such Fe3O4@RF@Ag substrates are promising for the reusable detection of toxic molecules in practical applications. | Oral cancer has a poor prognosis of only 50% even in the light of current technological advances. This poor prognosis may be attributed to the still unmet clinical need to diagnose oral pre-cancer and dysplasia. Raman spectroscopy, which can detect subtle biochemical changes, has been explored for the diagnosis of cancer. This study aims to address the clinical need by exploiting the high amplification factor of Surface Enhanced Raman Spectroscopy (SERS) to analyse the saliva samples of 10 healthy controls and 10 patients with oral dysplasia. Furthermore, this technique was compared to conventional Raman spectroscopy. The saliva samples were centrifuged at 14000g for 15 minutes and the supernatant was applied directly on the SERS substrate and dried. Simultaneously, the saliva samples were prepared in the same way on slides for conventional Raman analysis. A peak at 2108 cm-1, attributed to salivary thiocyanate was present in all samples from dysplasia subjects but absent in samples from healthy non-smoking subjects. Partial least squares – discriminant analysis models for classification of oral pre-cancer were developed for both Raman spectroscopy and SERS to discriminate between healthy, mild and moderate dysplasia cohorts. | eng_Latn | 8,945 |
Stimuli-responsive photonic crystals (PCs) represent an intriguing class of smart materials very promising for sensing applications. Here, selective ionic strength responsive polymeric PCs are reported. They are easily fabricated by partial sulfonation of polystyrene opals, without using toxic or expensive monomers and etching steps. The color of the resulting hydrogel-like ordered structures can be continuously shifted over the entire visible range (405–760 nm) by changing the content of ions over an extremely wide range of concentration (from about 70 μM to 4 M). The optical response is completely independent from pH and temperature, and the initial color can be fully recovered by washing the sulfonated opals with pure water. These new smart photonic materials could find important applications as ionic strength sensors for environmental monitoring as well as for healthcare screening. | Polymer gels are remarkable materials with physical structures that can adapt signifi cantly and quite rapidly with changes in the local environment, such as temperature, light intensity, electrochemistry, and mechanical force. An interesting phenomenon observed in certain polymer gel systems is mechanochromism ‐ a change in color due to a mechanical deformation. Mechanochromic photonic gels are periodically structured gels engineered with a photonic stopband that can be tuned by mechanical forces to refl ect specifi c colors. These materials have potential as mechanochromic sensors because both the mechanical and optical properties are highly tailorable via incorporation of diluents, solvents, nanoparticles, or polymers, or the application of stimuli such as temperature, pH, or electric or strain fi elds. Recent advances in photonic gels that display strain-dependent optical properties are discussed. In particular, this discussion focuses primarily on polymer-based photonic gels that are directly or indirectly fabricated via self-assembly, as these materials are promising soft material platforms for scalable mechanochromic sensors. | A study has been made of the presence and reactivity of the most commonly used surfactants, both anionic (linear alkylbenzene sulfonates, LAS, and alkyl ethoxysulfates, AES) and non-ionic (alcohol polyethoxylates, AEOs, and nonylphenol polyethoxylates, NPEOs), in water and surface sediments from the middle stretch of the Guadalete River in SW Spain (12 stations). Average values were between 0.1 and 3.7 mg kg(-1) in sediment, and between 0.2 and 37 μg L(-1) in water. The sorption of surfactants was dominated by hydrophobic mechanisms, so those homologues having longer alkyl chains (e.g. C(18)AEO) showed higher relative percentages and concentrations in sediments compared with water. Local and sharply higher concentrations of these compounds were observed at three sampling stations (7, 9 and 12), indicating the occurrence of wastewater discharges into the river. By analysing the distributions of different surfactant homologues and their metabolites we were able to distinguish between sewage contamination from sources discharging treated and untreated wastewaters. Upstream (stations 1-2), LAS concentrations were below 30 μg L(-1) and the composition of their degradation intermediates (sulfophenyl carboxylic acids, SPCs) (160 μg L(-1)) was dominated by short-chain homologues (C(6)-C(9)SPCs), indicating that the degradation of this surfactant is at an advanced stage. The highest concentration (487 μg L(-1)) of SPCs was detected near the effluent outlet of a sewage treatment plant (STP) (station 12). Sampling stations (7 and 9) affected by untreated wastewater discharges were the only ones showing the presence of the most reactive and biodegradable SPC isomers and homologues (e.g. C(11)SPC). Here, LAS reached the highest concentration values measured (>2 mg L(-1)), and showed a homologue distribution closer to that of commercial mixtures than LAS found at the other stations. | eng_Latn | 8,946 |
Experimental bioinformatics data obtained from an E. coli cell-based eukaryotic protein purification experiment were analyzed in order to identify any bottleneck as well as the factors affecting the target purification. All targets were expressed as His-tagged maltose-binding protein (MBP) fusion constructs and were initially purified by immobilized metal affinity chromatography (IMAC). The targets were subsequently separated from the His-tagged MBP through TEV protease cleavage followed by a second IMAC isolation. Of the 743 total purification trials, 342 yielded more than 3 mg of target proteins for structural studies. The major reason for failure of target purification was poor TEV proteolysis. The overall success rate for target purification decreased linearly as cysteine content or isoelectric point (pI) of the target increased. This pattern of pI versus overall success rate strongly suggests that pI should be incorporated into target scoring criteria with a threshold value. [BMB reports 2010; 43(5): 319-324] | We describe and validate a new membrane protein topology prediction method, TMHMM, based on a hidden Markov model. We present a detailed analysis of TMHMM’s performance, and show that it correctly predicts 97–98 % of the transmembrane helices. Additionally, TMHMM can discriminate between soluble and membrane proteins with both specificity and sensitivity better than 99 %, although the accuracy drops when signal peptides are present. This high degree of accuracy allowed us to predict reliably integral membrane proteins in a large collection of genomes. Based on these predictions, we estimate that 20–30 % of all genes in most genomes encode membrane proteins, which is in agreement with previous estimates. We further discovered that proteins with Nin-Cin topologies are strongly preferred in all examined organisms, except Caenorhabditis elegans, where the large number of 7TM receptors increases the counts for Nout-Cin topologies. We discuss the possible relevance of this finding for our understanding of membrane protein assembly mechanisms. A TMHMM prediction service is available at http://www.cbs.dtu.dk/services/TMHMM/. | Solar cells, as promising devices for converting light into electricity, have a dramatically reduced performance on rainy days. Here, an energy harvesting structure that integrates a solar cell and a triboelectric nanogenerator (TENG) device is built to realize power generation from both sunlight and raindrops. A heterojunction silicon (Si) solar cell is integrated with a TENG by a mutual electrode of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film. Regarding the solar cell, imprinted PEDOT:PSS is used to reduce light reflection, which leads to an enhanced short-circuit current density. A single-electrode-mode water-drop TENG on the solar cell is built by combining imprinted polydimethylsiloxane (PDMS) as a triboelectric material combined with a PEDOT:PSS layer as an electrode. The increasing contact area between the imprinted PDMS and water drops greatly improves the output of the TENG with a peak short-circuit current of ∼33.0 nA and a peak open-circuit voltage of ∼2.14 V, res... | eng_Latn | 8,947 |
This study describes a bottom-up assembly route for monodisperse carbon dots (CDs) into different sizes of CD aggregates through the control of the concentration of fatty acids. The highly monodisperse CDs were prepared via solvent–thermal treatment of edible soybean oil, which generated glycerol-based polymer as a carbon source and fatty acid as a surface capping in the synthetic process. The as-synthesized CDs exhibited small particle size variation (2.7 ± 0.2 nm) and narrow emission bands (full width at half-maximum <20 nm). The monodisperse CDs can self-assemble into blue-, green-, yellow-, and red-emitting CD aggregates by tuning the concentration of fatty acids. Compared to commercially available organic dyes and semiconductor quantum dots, the CD aggregates provided a 10–7000-fold improvement in brightness. Additionally, their emission wavelength was tunable across the entire visible spectrum by tuning the excitation wavelength. Because of their high brightness, fluorescence imaging of a single car... | Usually, carbon dots (CDs) display a relatively weak fluorescence quantum yield (QY). In order to obtain brighter CDs, phosphorus and chlorine co-doped CDs (P,Cl-CDs) were prepared via hydrothermal treatment of maltose in the presence of phosphoric and hydrochloric acids. The new CDs are highly monodispersed in water solution, have high fractions of P (14.4 atomic%) and Cl (8.9 atomic%), and exhibited yellow fluorescence with a QY of 15%. This is higher than that of monoatomic doped CDs (8.7 and 9.3% for P-CDs and Cl-CDs, respectively). The P,Cl-CDs are highly photostable, and fluorescence is strongly (statically) quenched by Fe(III). Fluorescence decreases with increasing concentration of Fe(III) in the range from 0.1–8.0 μmol⋅L-1, with a 60 nmol⋅L-1 detection limit. The doped CDs are shown to be a viable nanoprobe for the fluorometric determination of Fe(III) in spiked serum and water samples. | It is proved, by using topological properties, that when a group automorphism of a locally compact totally disconnected group is ergodic under the Haar measure, the group is compact. The result is an answer for Halmos's question that has remained open for the totally disconnected case. | eng_Latn | 8,948 |
A temporal difference method for processing dynamic speckle images is proposed. In the method two speckle images of an object, separated by a time interval, are subtracted one from the other to detect whether the speckle structure has changed or not. The rationale of the method is discussed. A variant of the method that allows measuring the area of an activity zone surrounded by a static region is tested in digital simulations. As a demonstrative experiment, that variant is employed to characterize the drying of a damp patch in filter paper. | Electrophoretic mobility and ζ-potential are important physical parameters for the characterization of micro- and nanosystems. ::: In this communication we describe a new method for determining the ζ-potential through the assembly of two ::: well known techniques: free electrophoresis and Dynamic Speckle. When coherent light passes through a fluid having ::: scattering centres, the far field interference originates a speckled image. If the scattering centres are contained within the ::: cylindrical electrophoresis cell of a ZetaMeter and are forced to move in an orderly way under the action of an external ::: electric field, the time variation of the light intensity in the far field speckle images follows a temporal autocorrelation ::: function g(τ). The corresponding correlation time can then be obtained and related with the velocity, from which the ::: electrophoretic mobility and the ζ-potential of the scattering centres can be determined. We have applied this method to ::: microparticles, like natural air-floated silica and two classes of bioceramics, hydroxyapatite and biphasic calcium ::: phosphate. For comparison, we analysed the same samples in parallel using a commercial Zetasizer Nano from Malvern ::: Instruments. The values of ζ-potential determined using the two techniques were the same within ~3% error. These ::: results validate our new method as a useful and efficient alternative for ζ-potential determination of particles, at least ::: within the micrometer scale. | ABSTRACTUNC-45A is an ubiquitously expressed protein highly conserved throughout evolution. Most of what we currently know about UNC-45A pertains to its role as a regulator of the actomyosin system... | eng_Latn | 8,949 |
We use extended Mie theory to investigate optical forces induced by and acting on small silver nanoparticle aggregates excited at surface plasmon resonance. It is shown that single molecules can be trapped at junctions between closely spaced nanoparticles, which are simultaneously pulled together by optical forces. These effects could significantly influence surface-enhanced Raman scattering and related spectroscopies under normal experimental conditions and contribute to single-molecule sensitivity. | Strategies for in-liquid molecular detection via Surface Enhanced Raman Scattering (SERS) are currently based on chemically-driven aggregation or optical trapping of metal nanoparticles in presence of the target molecules. Such strategies allow the formation of SERS-active clusters that efficiently embed the molecule at the “hot spots” of the nanoparticles and enhance its Raman scattering by orders of magnitude. Here we report on a novel scheme that exploits the radiation pressure to locally push gold nanorods and induce their aggregation in buffered solutions of biomolecules, achieving biomolecular SERS detection at almost neutral pH. The sensor is applied to detect non-resonant amino acids and proteins, namely Phenylalanine (Phe), Bovine Serum Albumin (BSA) and Lysozyme (Lys), reaching detection limits in the μg/mL range. Being a chemical free and contactless technique, our methodology is easy to implement, fast to operate, needs small sample volumes and has potential for integration in microfluidic circuits for biomarkers detection. | Red wine polyphenolic compounds have been demonstrated to possess antioxidant properties, and several studies have suggested that they might constitute a relevant dietary factor in the protection from coronary heart disease. The aim of the present study is to examine whether red wine extracts (RWE) can ameliorate oxysterol-induced endothelial response, and whether inhibition of adhesion molecule expression is involved in monocyte adhesion to endothelial cells. Surface expression and mRNA levels of adhesion molecules (intercellular adhesion molecule 1 and vascular cell adhesion molecule 1) were determined by ELISA and RT-PCR performed on human aortic endothelial cells (HAEC) monolayers stimulated with 7beta-hydroxycholesterol or 25-hydroxycholesterol. Incubation of HAEC with oxysterols (10 microM) increased expression of adhesion molecules in a time-dependent manner. Pretreatment of HAEC with RWE at final concentrations of 1, 10, and 100 ng/ml significantly inhibited the increase of surface protein expression and mRNA levels. Adherence of monocytes to oxysterol-stimulated HAEC was increased compared to that of unstimulated cells. Treatment of HAEC with RWE significantly inhibited adherence of monocytes. These results suggest that RWE works as an anti-atherogenic agent through the inhibition of endothelial-dependent adhesive interactions with monocytes induced by oxysterols. | eng_Latn | 8,950 |
A plasmonic switch is demonstrated with rotaxane-derivatized Au nanodisks. The molecule-nanodisk complexes exhibit redox-controlled reversible plasmon-based switching, suggesting that nanoscale movement with surface-bound molecular machines can be used as the active components of plasmonic devices. | Experiments using an opaque screen with tiny holes in it were a mainstay of early work on the physics of light. 'Tiny holes' later fell out of favour, but in recent years the use of subwavelength holes in metal films has become important in optics research. These films have unique optical properties due to the involvement of electronic surface waves, which can concentrate light in the hole and lead to high transmission. As their properties can be tailored at will by nanofabrication, tiny holes are finding applications in fields such as optoelectronics, chemical sensing and biophysics. The presence of tiny holes in an opaque metal film, with sizes smaller than the wavelength of incident light, leads to a wide variety of unexpected optical properties such as strongly enhanced transmission of light through the holes and wavelength filtering. These intriguing effects are now known to be due to the interaction of the light with electronic resonances in the surface of the metal film, and they can be controlled by adjusting the size and geometry of the holes. This knowledge is opening up exciting new opportunities in applications ranging from subwavelength optics and optoelectronics to chemical sensing and biophysics. | Oxidative stress (OS) is thought to play an important role in the pharmacological and toxic effects of various drugs of abuse. Herein we review the literature on the mechanisms responsible for the cardiovascular and hepatic toxicity of cocaine with special focus on OS-related mechanisms. We also review the preclinical and clinical literature concerning the putative therapeutic effects of OS modulators (such as N-acetylcysteine, superoxide dismutase mimetics, nitroxides and nitrones, NADPH oxidase inhibitors, xanthine oxidase inhibitors, and mitochondriotropic antioxidants) for the treatment of cocaine toxicity. We conclude that available OS modulators do not appear to have clinical efficacy. | eng_Latn | 8,951 |
Permittivities of honeydew melons and watermelons, grown to provide a range of maturities, were measured with an open-ended coaxial-line probe and impedance analyzer at frequencies from 10 MHz to 1.8 GHz. Measurements on fresh apples were also made over a ten-week storage period. Data were taken on the external surfaces of the fruit and on tissue samples from the edible internal tissue. Soluble solids content (SSC), indicative of sweetness, was used for melons as the quality factor for correlation with permittivity. Dielectric constant and loss factor correlations with SSC were low, but a high correlation was obtained between the SSC and permittivity from a complex-plane plot of dielectric constant and loss factor, each divided by SSC. However, quality prediction from this relationship was not very high. Dielectric properties of apples were relatively constant during the ten-week storage period even though firmness of apple tissues decreased significantly over that period. | Honeydew melons were grown and harvested with a range of maturities for measurement of tissue permittivities (dielectric constant and loss factor) to study possible correlations between the dielectric properties and soluble solids (sweetness) for nondestructive sensing of maturity. Permittivities of tissue samples from 38 melons were measured at 25°C over the frequency range from 10 MHz to 1.8 GHz along with refractometer determinations of soluble solids content (SSC), tissue density, and moisture content. A high correlation (r = 0.96) was found between SSC and the permittivity as expressed in a complex-plane plot of the two components of the relative complex permittivity, each divided by SSC. Through this mathematical relationship, SSC can be calculated from measured permittivity values independent of tissue density and moisture content. Moderate correlations were noted between dielectric constant and SSC at 10 MHz and between the loss factor and SSC at 1.8 GHz. Correlations between the dielectric properties and both moisture content and tissue density were very low. The correlation between tissue density and SSC was also very low. A high correlation was noted between SSC and moisture content, with SSC decreasing as moisture content increased. Problems in using the high correlation between permittivity and SSC for practical, nondestructive sensing of honeydew melon maturity as determined by SSC are also considered. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 8,952 |
The emission properties of most fluorescent emitters, such as dye molecules or solid-state color centers, can be well described by the model of an oscillating electric dipole. However, the orientations of their excitation and emission dipoles are, in most cases, not parallel. Although single molecule excitation and emission dipole orientation measurements have been performed in the past, no experimental method has so far looked at the three-dimensional excitation and emission dipole geometry of individual emitters simultaneously. We present the first experimental study, using defocused imaging in conjunction with radially polarized excitation scanning, to measure both the excitation as well as emission dipole orientations of single molecules, which allows us to sample the distribution of their mutual orientation. We find an unexpectedly broad distribution of the angle between both dipoles which we attribute to the interaction between the observed molecules and the substrate they are immobilized on. | Various methods exist for measuring molecular orientation, thereby providing insight into biochemical activities at nanoscale. Since fluorescence intensity and not electric field is detected, these methods are limited to measuring even-order moments of molecular orientation. However, any measurement noise, for example photon shot noise, will result in nonzero measurements of any of these even-order moments, thereby causing rotationally-free molecules to appear to be partially constrained. Here, we build a model to quantify measurement errors in rotational mobility. Our theoretical framework enables scientists to choose the optimal single-molecule orientation measurement technique for any desired measurement accuracy and photon budget. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 8,953 |
A planar conjugated copolymer named HXS-1 was applied in thin film phototransistors. Similar to organic field-effect transistors using V(G) to control the source-drain current, in phototransistors, the light is used to substitute V(G) as an independent variable to control the output of the transistors to realize light detection and signal magnification in a single organic device. All devices exhibited high performance with an on/off ratio up to 4.6 × 10(4) (the highest on/off ratio of organic or polymer phototransistors), which could be assigned to i) the wide absorption features of HXS-1 in the whole UV-vis range, ii) the ideal HOMO energy level of HXS-1 (5.21 eV) to align with Au electrodes (5.2 eV) and iii) the high mobility of the polymer thin films (∼0.06 cm(2) /Vs). Moreover, the devices, both under continuous operation conditions and long term measurement conditions, exhibited excellent stability, indicating potential applications of the devices in polymer-based optoelectronics. | Organic phototransistors based on high-quality 2,8-dichloro-5,11-dihexyl-indolo[3,2- b ]carbazo (CHICZ) single crystals show the highest photoresponsivity of 3×103 A W−1, photosensitivity of 2×104 and the detectivity can achieve 8.4×1014 Jones. We also discovered good linear dependence of log(photosensitivity) versus the wavelength when the devices were illuminated with a series of same-intensity but different-wavelength lights. The organic phototransistors based on CHICZ single crystal have potential applications in wavelength-detection. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 8,954 |
This study demonstrates a biological route to programming well-defined protein-inorganic interfaces with an arrayed geometry via modular peptide tag technology. To illustrate this concept, we designed a model multifunctional fusion protein, which simultaneously displays a maltose-binding protein (MBP), a green fluorescence protein (GFPuv) and an inorganic-binding peptide (AgBP2C). The fused combinatorially selected AgBP2C tag controls and site-directs the multifunctional fusion protein to immobilize on silver nanoparticle arrays that are fabricated on specific domain surfaces of ferroelectric LiNbO3 via photochemical deposition and in situ synthesis. Our combined peptide-assisted biological and ferroelectric lithography approach offers modular design and versatility in tailoring surface reactivity for fabrication of nanoscale devices in environmentally benign conditions. | The photochemical deposition of silver on (001)-oriented 0.25Pb(In 1/2 Nb 1/2 )O 3 -0.44Pb(Mg 1/3 Nb 2/3 )O 3 -0.31PbTiO 3 (PIN-PMN-PT) ferroelectric single crystals is investigated via piezoresponse force microscopy (PFM) and Kelvin probe force microscopy (KPFM). Selective photochemical deposition within c+ domains is attained by manipulating the photoreaction time. Enhanced photochemical reduction at c−/c+ domain boundaries is achieved by controlling the domain poling voltage and the scanning direction of the tip during domain switching. These phenomena are explained by polarisation band bending at domain boundaries and tip induced charge injection during domain switching. This work provides insight into obtaining an arbitrary spatial distribution of photodeposited metal on ferroelectric materials. | Blunt trauma abdomen rarely leads to gastrointestinal injury in children and isolated gastric rupture is even rarer presentation. We are reporting a case of isolated gastric rupture after fall from height in a three year old male child. | eng_Latn | 8,955 |
With the aid of indocyanine green (ICG), lymphatic architecture and function in both mice and humans has been successfully imaged non-invasively using near-infrared (NIR) fluorescence imaging devices. Maximal measurement sensitivity of NIR fluorescence imaging devices is needed for "first-in-humans" molecularly targeting NIR fluorescence agents that are brighter than non-specific ICG. In this study, we developed a solid phantom and measurement approach for the quantification of excitation light leakage and measurement sensitivity of NIR fluorescence imaging devices. The constructed solid phantom, consisting of quantum dots impregnated onto specularly reflective surface, shows long-term stability and can be used as a traceable fluorescence standard. With the constructed solid phantom, the intensified CCD (ICCD)-based device demonstrated more than 300% higher measurement sensitivity compared to the Electron Multiplying CCD (EMCCD) based device when integration time was maintained less than 1.0 s. | The success of optical surgical navigation depends upon being able to intraoperatively employ a contrast agent and an imaging device to successfully guide surgery. Development of devices and contrast agents typically occur separately even though it is their combined performance that ultimately determines success and clinical adoption. Herein, we review critical issues and summarize our strategies and approaches for validating molecularly-targeted, near-infrared fluorescent contrast agents and the devices sufficiently sensitive enough for their detection in order to guide lymph node dissection. | The pre-launch characterization and calibration of remote sensing instruments should be planned and carried out in conjunction with their design and development to meet the mission requirements. The onboard calibrators such as blackbodies and the sensors such as spectral radiometers should be characterized and calibrated using SI traceable standards. In the case of earth remote sensing, this allows inter-comparison and intercalibration of different sensors in space to create global time series of climate records of high accuracy where some inevitable data gaps can be easily bridged. The recommended best practice guidelines for this pre-launch effort is presented based on experience gained at National Institute of Standards and Technology (NIST), National Aeronautics and Space Administration (NASA) and National Oceanic and Atmospheric Administration (NOAA) programs over the past two decades. The currently available radiometric standards and calibration facilities at NIST serving the remote sensing community are described. Examples of best practice calibrations and intercomparisons to build SI (international System of Units) traceable uncertainty budget in the instrumentation used for preflight satellite sensor calibration and validation are presented. | eng_Latn | 8,956 |
In this letter, a microstrip line (MLIN)-based glucose sensor with significant improvement in sensitivity over sensors of the same category is proposed for noninvasive glucose monitoring. It has a T-shaped patterned signal line using the main field of an MLIN for sensing. Glucose under monitoring serves as the substrate of the MLIN. The pattern in the MLIN is designed for enhancing the field interaction in the substrate for improving the sensitivity of the sensor. It achieves much higher sensitivity than that of the state-of-the-art MLIN-based sensors for the same concentrations and comparable sensitivity to resonance-based microstrip sensors with improved robustness. The improvement in sensitivity is validated based on experiments using 0.9% sodium chloride with different glucose concentrations. The robustness is analyzed. The proposed structure is promising for noninvasive continuous glucose monitoring. | In this paper, a novel non-invasive sensor for the measurement of the glucose concentrations in blood is presented. By using a microstrip band pass filter, a wireless sensor is achieved. In the introduced design, the thumb is placed on the structure of the filter as a superstrate. The response of the filter is dependent on the permittivity of the superstrate. A compact size, linearity and cost effectiveness are the most important advantages of the proposed sensor. The linear behaviour of the filter in terms of the frequency is investigated and for a linear behaviour, a certain frequency for operation is selected. The introduced sensor can be used by diabetics for continuous self-monitoring of the glucose level. The structure of the proposed sensor is designed on the low-cost substrate, FR4, by compact dimensions of 50 mm × 40 mm × 1.6 mm. A prototype of the proposed filter was fabricated and the performance of the filter was investigated, experimentally. | Experiments using a plexiglass Y -maze fluviarium showed that nymphs of Parameletus chelifer and Parameletus minor each used different environmental cues to orient. P. chelifer nymphs reacted to pH while nymphs of P. minor were very sensitive to concentration of dissolved organic matter. The capacity to detect these water quality differences was lost as soon as the nymphs reached seasonally submerged areas suitable for growth at the margin of the river. When nymphs of both species had reached their growing areas, water temperature became the crucial cue for orientation. | eng_Latn | 8,957 |
Molecular photonics, information processing based on strong interactions of photons and molecules, has attracted much attention, since it can fully utilize many superior properties of both photons and molecules. We have developed polymeric materials showing ultrafast absorption changes in the visible to near-infrared regions including the telecommunication wavelength by photoinduced electron transfer and reverse reactions between substituted pyridinium and its counter anion. By selecting the counter anion we succeeded in making steady and ultrafast absorption changes. Time-resolved absorption and fluorescence spectroscopy upon femtosecond laser excitation revealed reaction mechanism and ultrafast dynamics. In order to fully utilize such photoresponses in molecular photonics, we proposed guided wave mode (GWM) device composed of a prism, a low refractive index polymer film, and a photoresponsive polymer film. The reflectance in this GWM is controlled by many factors such as thickness values and complex refractive indices of two polymer layers as well as an incident angle and wavelength. We successfully achieved sensitive, all optical, and very fast control of reflectance by means of photoinduced complex refractive index changes upon femtosecond laser excitation. | The sol-gel method has been employed in the fabrication of easily processable mesostructured films consisting of a nonionic surfactant and silica as the inorganic component. The ability of the occluded Pluronic P123 mesostructures to solubilize guest molecules made these films ideal host matrices for organic dyes and molecular assemblies, possessing substantial nonlinear susceptibilities. These films were explored for use as the photonic layer in all-optical time-to-space converters and proved successful at increasing the optical response of the intercalated dyes to a point that would make these composite films applicable for use as the photonic layer. Recording of a dynamical grating in a single-pulse regime has been obtained. Since the dynamical grating exhibits the fast relaxation time (up to 10 ns), the nonlinear mechanism represents an electronic excitation of the photosensitive molecules. As far as the dye molecules are distributed in nanoporous silica, a model of ‘gas of molecular dye’ may be rightly used in order to consider nonlinear optical properties in the nanostructured hybrid films. We suppose that further improvement of the nonlinear optical nanomaterials may follow on the way to embed additional inclusions, which will not promote the heat accumulation in the host matrix and will lead to effective dissipation of the heat energy. PACS: 78.20.-e; 42.70 -а; 42.79 | Background ::: Beta-2 Microglobulin (β2M) is a prototypical “middle molecule” uremic toxin that has been associated with a higher risk of death in hemodialysis patients. A quantitative description of the relative importance of factors determining β2M concentrations among patients with impaired kidney function is currently lacking. | eng_Latn | 8,958 |
Visible and near-infrared radiation is now widely employed in health science and technology. Pre-clinical trials are still essential to allow appropriate translation of optical methods into clinical practice. Our results stress the importance of considering the mouse strain and gender when planning pre-clinical experiments that depend on light–skin interactions. Here, we evaluated the optical properties of depilated albino and pigmented mouse skin using reproducible methods to determine parameters that have wide applicability in biomedical optics. Light penetration depth (δ), absorption (μ a ), reduced scattering (μ′ s ) and reduced attenuation (μ′ t ) coefficients were calculated using the Kubelka–Munk model of photon transport and spectrophotometric measurements. Within a broad wavelength coverage (400–1400 nm), the main optical tissue interactions of visible and near infrared radiation could be inferred. Histological analysis was performed to correlate the findings with tissue composition and structure. Disperse melanin granules present in depilated pigmented mouse skin were shown to be irrelevant for light absorption. Gender mostly affected optical properties in the visible range due to variations in blood and abundance of dense connective tissue. On the other hand, mouse strains could produce more variations in the hydration level of skin, leading to changes in absorption in the infrared spectral region. A spectral region of minimal light attenuation, commonly referred as the “optical window”, was observed between 600 and 1350 nm. | Infectious pneumonia is a major cause of morbidity/mortality, mainly due to the increasing rate of microorganisms resistant to antibiotics. Photodynamic Inactivation (PDI) is emerging as a promising treatment option, which effects are based on oxidative stress, targeting several biomolecules and probably preventing potential resistant strains. In previous studies, the in vitro inactivation of Streptococcus pneumoniae using indocyanine green (ICG) and infrared (IR) light source (780 nm) was successful, and achieving satisfactory reduction of colony-forming units (CFU/mL). In the present study, a proof-of-principle protocol was designed to treat lung infections by PDI using extracorporeal irradiation with a 780 nm laser device and nebulized ICG as photosensitizer. Balb/c mice were infected with S. pneumoniae and PDI was performed two days after infection using 800 μM of nebulized ICG and extracorporeal irradiation. Our results indicate that IR-extracorporeal PDI using nebulized ICG may be considered a potential pneumonia treatment, and pulmonary decontamination with PDI may be used as a single therapy or as an adjuvant for antibiotics. | By using a superluminescent diode as the light source and a depolariser inside the fibre coil, a constant scale factor is achieved without using polarisation control elements. For long-term behaviour an RMS-bias drift of 10 degrees/h is obtained. | eng_Latn | 8,959 |
Two cDNAs encoding firefly luciferase (FLuc) and Renilla luciferase (RLuc) were used as labels for the development of a microtiter well-based expression hybridization assay that allows simultaneous determination of two target DNA sequences. The target DNAs were denatured and hybridized with specific capture and detection probes. One detection probe was biotinylated while the other was tailed with poly(dT). The hybrids were reacted with a streptavidin-FLuc DNA complex and a poly(dA)-tailed RLuc DNA, respectively. Subsequently, the cDNA labels were expressed in vitro simultaneously and independently in the same transcription/translation reaction mixture. The activities of generated firefly and Renilla luciferases were co-determined in the same sample based on the differential requirements of their characteristic bioluminescent reactions for magnesium ions. | Chemi(bio)luminometric assays have contributed greatly to various areas of nucleic acid analysis due to their simplicity and detectability. In this work, we present the development of chemiluminometric genotyping methods in which (a) detection is performed by using either a conventional digital camera (at ambient temperature) or a smartphone and (b) a lateral flow assay configuration is employed for even higher simplicity and suitability for point of care or field testing. The genotyping of the C677T single nucleotide polymorphism (SNP) of methylenetetrahydropholate reductase (MTHFR) gene is chosen as a model. The interrogated DNA sequence is amplified by polymerase chain reaction (PCR) followed by a primer extension reaction. The reaction products are captured through hybridization on the sensing areas (spots) of the strip. Streptavidin-horseradish peroxidase conjugate is used as a reporter along with a chemiluminogenic substrate. Detection of the emerging chemiluminescence from the sensing areas of the strip is achieved by digital camera or smartphone. For this purpose, we constructed a 3D-printed smartphone attachment that houses inexpensive lenses and converts the smartphone into a portable chemiluminescence imager. The device enables spatial discrimination of the two alleles of a SNP in a single shot by imaging of the strip, thus avoiding the need of dual labeling. The method was applied successfully to genotyping of real clinical samples. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 8,960 |
Microfluidic cytometers based on coulter principle have recently shown a great potential for point of care biosensors for medical diagnostics. In this study, the design of coulter based microfluidic cytometer is investigated by using electrical circuit simulations. We explore the effects of physical dimensions of the microelectrodes, the measurement volume, size/morphology of the targeted cells, electrical properties of the reagents in the measurement volume, and, the impedance of external readout circuit, on the sensitivity of the sensor. We show that the effect of microelectrode's surface area and the dielectric properties of the suspension medium should be carefully considered when characterizing the output response of the sensor. In particular, the area of microelectrodes can have significant effect on cells electrical opacity( the ratio of the cell impedance at high to low frequency) which is commonly used to distinguish between sub-population of the target cells( e.g. lymphocytes vs monocytes when counting white blood cells).Moreover, we highlight that the opacity response vs frequency can significantly vary depending upon whether the absolute cell impedance or the differential output impedance is used in the calculation. These insights can provide valuable guidelines for the design and characterization of coulter based microfluidic sensors. | Over the last century a number of techniques have been developed which allow the measurement of the dielectric properties of biological particles in fluid suspension. The majority of these techniques are limited by the fact that they only provide an average value for the dielectric properties of a collection of particles. More recently, with the advent of microfabrication techniques and the Lab-on-a-chip, it has been possible to perform dielectric spectroscopic experiments on single biological particles suspended in physiological media. In this paper we review current methods for single cell dielectric spectroscopy. We also discuss alternative single cell dielectric measurement techniques, specifically the ac electrokinetic methods of dielectrophoresis and electrorotation. Single cell electrical impedance spectroscopy is also discussed with relevance to a microfabricated flow cytometer. We compare impedance spectroscopy data obtained from measurements made using a microfabricated flow cytometer with simulation data obtained using an equivalent circuit model for the device. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 8,961 |
Silver nanomaterials (AgNMs) of different shapes and sizes are potentially toxic to aquatic organisms. However, studies on the toxicity of AgNMs and on their shape-dependent effects on algae are scarce. The present study evaluated the effects of three AgNMs (silver nanospheres, AgNPs; silver nanowires, AgNWs; silver nanoplates, AgPLs) with different shapes coated with polyvinylpyrrolidone on the growth and photosynthetic performance of an alga, Chlorococcum infusionum . We used growth measurements and determined the photosynthetic parameters based on chlorophyll fluorescence transients in the algal cells exposed to different concentrations of the three AgNMs. The effective concentrations at 50% (EC 50 ) of AgNPs, AgNWs, and AgPLs were calculated to be 0.1, 0.045, and 0.021 mg/L, respectively. The results showed that the toxicity of AgNMs in C. infusionum was in the order, AgPLs (40 nm diameter) > AgNWs (21,000 nm length × 42 nm diameter) > AgNPs (57 nm diameter), based on the decrease in growth and three photosynthetic activities. We propose that the toxic potential of AgNMs is primarily dependent on their diameter and secondarily on their shape. Overall, this study provides, for the first time, a comparison of the growth and photosynthetic activities of C. infusionum exposed to AgNMs of three different shapes. | In the present in vivo study, we provide a comparison of toxicological consequences induced by four different types of spherical nanoparticles (NPs)—silver nanoparticles (AgNPs, 40 ± 6 nm), nickel (NiNPs, 43 ± 6 nm), cobalt oxide (Co3O4NPs, 60 ± 6 nm), and chromium oxide (Cr3O4NPs, 50 ± 5 nm)—on freshwater fish Labeo rohita. Fish were exposed to NPs (25 mg/L) for 21 days. We observed a NPs type-dependent toxicity in fish. An altered behavior showing signs of stress and a substantial reduction in total leukocyte count was noticed in all NP-treated groups. A low total erythrocyte count in all NP-treated fish except for Co3O4NPs was discerned while a low survival rate in the case of Cr3O4NP-treated fish was observed. A significant decrease in growth and hemoglobin were noticed in NiNP- and Cr3O4NP-treated fish. A considerable total protein elevation was detected in NiNP-, Co3O4NP-, and Cr3O4NP-treated groups. An upgrading in albumin level was witnessed in Co3O4NP- and Cr3O4NP-treated groups while a high level of globulin was noted in NiNP- and Co3O4NP-exposed groups. In all NP-treated groups, a depleted activity of antioxidative enzymes and pathological lesions in liver and kidney were noticed. | Fibrous particles interact with cells and organisms in complex ways that can lead to cellular dysfunction, cell death, inflammation, and disease. The development of conductive transparent networks (CTNs) composed of metallic silver nanowires (AgNWs) for flexible touchscreen displays raises new possibilities for the intimate contact between novel fibers and human skin. Here, we report that a material property, nanowire-bending stiffness that is a function of diameter, controls the cytotoxicity of AgNWs to nonimmune cells from humans, mice, and fish without deterioration of critical CTN performance parameters: electrical conductivity and optical transparency. Both 30- and 90-nm-diameter AgNWs are readily internalized by cells, but thinner NWs are mechanically crumpled by the forces imposed during or after endocytosis, while thicker nanowires puncture the enclosing membrane and release silver ions and lysosomal contents to the cytoplasm, thereby initiating oxidative stress. This finding extends the fiber pathology paradigm and will enable the manufacture of safer products incorporating AgNWs. | eng_Latn | 8,962 |
A new version of the photodiode array Fourier transform spectrometer for visible spectroscopy is described. In this version, a birefringent interferometer with a Wollaston prism produces a spatial interferogram the of the radiation, which is detected by a linear photodiode array. In addition to the merit of having no mechanical moving parts, this spectrometer has the beneficial advantage of the simple and rugged optical setup and alignment due to its common-path and in-line interferometer formation. These advantages lend this spectrometer to field-use applications. Emission spectra of a low-pressure mercury lamp and a light-emitting diode and an absorption spectrum of a didymium glass filter measured by the developed spectrometer are presented. | A prototype long wave infrared Fourier transform spectral imaging system using a wedged Fabry-Perot interferometer ::: and a microbolometer array was designed and built. The instrument can be used at both short (cm) and long standoff ::: ranges (infinity focus). Signal to noise ratios are in the several hundred range for 30 C targets. The sensor is compact, ::: fitting in a volume about 12 x12 x 4 inches. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 8,963 |
A rapid method has been developed for detecting food colorants based on surface-enhanced Raman spectroscopy (SERS). The technique was demonstrated to have the ability to identify a wide variety of artificial and natural food coloring agents currently approved or banned in the United States. A simple silver nanoparticle substrate was used to enhance the signal, requiring less than 10 min of sample preparation prior to analysis. All of the colorants had distinct SERS signals and could be easily differentiated based on their spectral features and using principal component analysis. Further tests confirmed that SERS is capable of quantifying adulteration with chemically and visually similar colorants, and can detect signals from some artificial colorants down to at least 1 ppm concentrations. Additionally, both artificial and natural colorants could be identified in commercially available food products using the technique. This study establishes a database of 16 commonly used artificial and natural food colorants. The simplicity of the SERS method and its strong effectiveness for detecting colorants indicate that it has great potential to be used for practical applications in this area. | Palm oil is one of the most useful vegetable available. Sudan IV dye is used as hue enhancer in palm oil despite the ban as food colorant due to its carcinogenicity and mutagenicity by the International Agency for Research on Cancer (IARC). Surface enhanced Raman spectroscopy (SERS) coupled with chemometric methods was applied to detect the presence of Sudan IV in some edible palm oil samples. We studied the samples within the 1200–1800 cm− 1 Raman frequency range. In predicting adulteration, we used 1388 cm− 1 Raman peak that is associated with Sudan IV as our marker. We were able to confirm adulteration in four of the five palm oil samples provided by the Food and Drug Authority of Ghana. With these methods, we confirmed the results from Food and Drug Authorities of Ghana by proving that there were indeed Sudan IV adulteration in some palm oil samples. | Surface enhanced Raman scattering (SERS) sensors have been fabricated by rapid thermal chemical vapor deposition of high-density nanoscale discrete graphene islands on copper foils followed by electroless chemical plating of discrete, closely spaced, and irregularly shaped silver nanoparticles on the copper surface where it is not covered by graphene islands. By fine tuning of the size and distribution of graphene islands and adjusting the deposition time for silver nanoparticles, nanoscale gaps between silver particles are fabricated. SERS sensors exhibiting Raman scattering signal enhancement factors as high as 1014 in reference to a bare copper have been demonstrated. Raman scattering signal has been measured from as low as 10−16 M of R6G molecules in water. This article reports effects and optimization process of size and distribution of graphene islands on desirable morphology of chemically plated silver nanoparticles. The density of nanoscale gaps of a few nanometers in distance between neighboring silver nanoparticles is optimized, resulting in the demonstration of SERS sensors with very low detection limits for R6G molecules. | eng_Latn | 8,964 |
The ketolide HMR 3647 (previously RU 66647) was evaluated against 2,563 recent clinical isolates of gram-positive pathogens and 200 Haemophilus influenzae isolates. HMR 3647 was active against macrolide-resistant streptococci, including pneumococci, but was not active against macrolide- or lincosamide-resistant staphylococci. Against H. influenzae, the potency of HMR 3647 was similar to that of azithromycin. | The potential efficacy of an antibacterial depends not only on its spectrum of activity but also on its concen- tration at the site of infection. The tissue kinetics of telithromycin—the first ketolide antibacterial—are reviewed here. Telithromycin accumulates rapidly in white blood cells, inflammatory fluid, and cells and tissues of the upper and lower respiratory tract, with mean concentrations above the MICs of key respiratory pathogens. Tissue kinetics of telithromycin support facilitated delivery to the site of infection, good efficacy against intracellular respiratory pathogens and respiratory pathogens at extracellular sites in the airways, and effectiveness in the treatment of upper and lower respiratory tract infections (RTIs). The tissue kinetics profile of telithromycin, together with its microbiological profile, makes it a promising new antibacterial for the treatment of community-acquired RTIs. | Molybdenum telluride (MoTe2) has attracted renewed interest owing to their versatile applications, such as transistors, logic circuits, photovoltaic cells, photodetectors, sensors, and lasers. We demonstrate an all-optically tunable microfiber knot resonator (MKR) overlaid with MoTe2 nanosheets. The optical transmitted power (OTP), resonance wavelength, and extinction ratio of the MoTe2 coated MKR can be tuned using external incidence pump lasers (405, 450, and 660 nm). MKR with MoTe2 nanosheets has strong absorption in the visible regime and enhanced light–matter interaction, resulting in enhanced tuning efficiency. Assisted by thermo-optic effect and photon generated carriers, the intensity and the wavelength of the MKR can be simultaneously tuned. The tuning efficiencies of the OTP, resonance wavelength, and extinction ratio of the MKR are up to 0.5 dB/mW, 7.52 pm/mW, and 0.16 dB/mW, respectively. The response time is measured to be ∼3 ms. Theoretical simulations are performed for the MKR with and without MoTe2, which agree well with the experimental results. The advantages of this device are all-optical tuning, easy fabrication, all-fiber content, high tuning efficiency, and fast response. This all-optical tunable MKR can find applications in all-optical circuitry, all-optical modulator, multi-dimensionally tunable optical devices, etc. | eng_Latn | 8,965 |
For the detection of methane (CH4) gas concentration in some mining complexes, the paper studies and discusses two kinds of easily-realized CH4 gas opticfiber sensor, that is infrared absorption CH4 gas optic fiber sensor and thin film transmission CH4 gas optic fiber sensor. The optic structure of the sensor is discussed, and the paper compares the difference between the single optic structure system and the double one. It puts forward a multipoint long-distance detection system constructed by the micro- computer small system and the upper computer, and discusses the hardware and software system.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. | An all-optical remote sensing system utilizing long-distance low-loss optical fiber links in conjunction with high-radiant InGaAsP light emitting diodes and dielectric interference filters was developed for the real-time absorption measurement of molecular concentration in the near-infrared region. The highly sensitive technique was achieved employing the power-balanced two-wavelength differential absorption method in the system, which enables direct detection of differential absorption signals for the specific molecule being monitored. Based on the laboratory study of the 2ν3 overtone band of CH4 molecules at 1.66 μm, the system was used for remote detection of low-level CH4 gas using a 2-km long low-loss silica optical fiber link incorporating an InGaAsP light emitting diode. Thus we demonstrated that this method is capable of a high detection sensitivity as low as ~400 ppm, i.e., ~0.8% of the lower explosion limit of CH4 density in air. Further extensive applications of the system as well as potential improvement of its sensitivity are also discussed. | An all-optical remote sensing system utilizing long-distance low-loss optical fiber links in conjunction with high-radiant InGaAsP light emitting diodes and dielectric interference filters was developed for the real-time absorption measurement of molecular concentration in the near-infrared region. The highly sensitive technique was achieved employing the power-balanced two-wavelength differential absorption method in the system, which enables direct detection of differential absorption signals for the specific molecule being monitored. Based on the laboratory study of the 2ν3 overtone band of CH4 molecules at 1.66 μm, the system was used for remote detection of low-level CH4 gas using a 2-km long low-loss silica optical fiber link incorporating an InGaAsP light emitting diode. Thus we demonstrated that this method is capable of a high detection sensitivity as low as ~400 ppm, i.e., ~0.8% of the lower explosion limit of CH4 density in air. Further extensive applications of the system as well as potential improvement of its sensitivity are also discussed. | eng_Latn | 8,966 |
Picosecond laser sources operating over an order of magnitude in repetition rates and pulse energies at selected emission wavelengths from the UV to IR range are presented for time-correlated single-photon counting in demanding imaging applications. | More than 20 years ago, single photon counting based techniques evolved as one recognized standard in fluorescence detection. In combination with confocal microscopy FLIM (Fluorescence Lifetime Imaging Microscopy) and FCS (Fluorescence Correlation Spectroscopy) became established techniques for investigations down to the single molecule level. Up to date, these experiments typically are carried out in the visible up to the near infrared spectral range.Based on recent advances in fiber amplified laser technology [1] and ultrasensitive detection, we present a novel approach to extend time-correlated single photon counting (TCSPC) into the deep UV using 266 nm excitation. Hereby, direct access is granted to the native fluorescence of biomolecules originating from appropriate chromophoric groups such as the amino acids tryptophan and tyrosine within proteins. As first results, we will present label-free FLIM of cells where the aromatic amino acids within the proteins become visible. As a benchmark, also FCS with organic fluorophores in the deep UV will be shown.Another application of time-resolved fluorescence microscopy in the deep UV includes microfluidics and thus enables label-free detection and identification of various aromatic analytes in chip electrophoresis [2, 3]. Fluorescence decay curves are gathered on-the-fly and average lifetimes can be determined for different substances in the electropherogram with the aim to identify aromatic compounds in mixtures. Based on the time-correlated single photon counting the background fluorescence can be discriminated resulting in improved signal-to-noise-ratios. In addition, microchip electrophoretic separations with fluorescence lifetime detection can be performed with protein mixtures emphasizing the potential for biopolymer analysis.References:[1] Schoenau et.al., Biomedical Optics (BIOMED), Miami, Florida, 2012[2] Beyreiss et al., Electrophoresis 2011, 32, 3108-3114[3] S. Ohla et al., Chem. Eur. J. 2012, 18, 1240 - 1246 | Below T CO = 157 K the quasi-one-dimensional charge-transfer salt (TMTTF) 2 SbF 6 undergoes a pronounced phase transition to a charge-ordered ground state. We have explored the non-linear and photoconductive behavior as a function of applied voltage, laser pulse energy and temperature. Besides a decay of the photoconductive signal in a double exponential fashion in the millisecond range, we discover current oscillations in the kHz range induced by the application of short laser pulses. While the resonance frequencies do not depend on voltage or laser intensity and vary only slightly with temperature, the amplitude changes linearly with the laser intensity and voltage. We suggest that photo-induced fluctuations of the charge-ordered state alter the current flow of the single particles and hence, the photocurrent. The findings are discussed and compared to comparable phenomena in other low-dimensional electron systems. | eng_Latn | 8,967 |
In recent years, there has been rapid progress in understanding the properties and mechanism of generation of the light-evoked electrical signals of vertebrate rods and cones. The graded hyperpolarization that carries information over the length of the cell is generated by closure of cation-selective aqueous pores in the surface membrane of the outer segment. These pores are controlled cooperatively by cyclic GMP, which acts continuously in darkness to keep the pores open. Photoisomerization of rhodopsin or cone pigment produces the rapid amplified activation of phosphodiesterase, which lowers the concentration of cGMP, thereby lowering the conductance of the surface membrane. Calcium ions, once thought to relay excitation to the light-sensitive channels, do not play this role. Instead, they appear to participate in a feedback control mechanism that regulates the nucleotide cascade. Although some general features of the transduction mechanism are now understood, a number of important questions remain. How is the nucleotide cascade shut off? Where does Ca act? What is the structure of the light-sensitive channel? How are stereotyped single photon responses produced? Primate photoreceptors are no longer off limits to single cell electrophysiology. Analysis of the response properties and dark noise of primate rods gives a physiological basis for several fundamental features of human rod vision: single photon detection, poor temporal resolution, the "dark light," rod saturation, scotopic spectral sensitivity, and, perhaps, after-image signals. Primate cones show less sensitive but faster responses shaped by a resonance which may figure in the flicker sensitivity of human cone vision. The spectral sensitivity of the three types of primate cones has been determined over the entire visible region. These sensitivities satisfactorily predict human color matching. The spectral sensitivity curves indicate that the pigment in a given cone is very pure, and that individual cones of a given type normally contain pigments with very similar or identical spectral properties. | Seeing begins in the photoreceptors, where light is absorbed and signaled to the nervous system. Throughout the animal kingdom, photoreceptors are diverse in design and purpose. Nonetheless, phototransduction-the mechanism by which absorbed photons are converted into an electrical response-is highly conserved and based almost exclusively on a single class of photoproteins, the opsins. In this Review, we survey the G protein-coupled signaling cascades downstream from opsins in photoreceptors across vertebrate and invertebrate species, noting their similarities as well as differences. | An experimental analysis of the role of surface roughness parameters on micropitting and the succeeding rolling contact fatigue (RCF) of silicon nitride against AISI 52100 steel under lubricated conditions was performed. In accelerated fatigue tests using a four-ball tester, the arithmetic mean, root mean square, and peak-to-valley roughnesses of silicon nitride surfaces varied, while the roughness of the steel surface was unchanged. The correlation between the fatigue life and roughness parameters for silicon nitride was obtained. The peak-to-valley roughness was the roughness parameter that dominantly affected the RCF life of silicon nitride. The micropitting of surfaces leading to fatigue intensified as the roughness was increased. Extensive micropitting was observed on the rolling track beyond the trailing edge of the spall region in the circumferential direction. | eng_Latn | 8,968 |
Biosensor-based fragment screening is a valuable tool in the drug discovery process. This method is advantageous over many biochemical methods because primary hits can be distinguished from non-specific or non-ideal interactions by examining binding profiles and responses, resulting in reduced false-positive rates. Biolayer interferometry (BLI), a technique that measures changes in an interference pattern generated from visible light reflected from an optical layer and a biolayer containing proteins of interest, is a relatively new method for monitoring small molecule interactions. The BLI format is based on a disposable sensor that is immersed in 96-well or 384-well plates. BLI has been validated for small molecule detection and fragment screening with model systems and well-characterized targets where affinity constants and binding profiles are generally similar to those obtained with surface plasmon resonsance (SPR). Screens with challenging targets involved in protein–protein interactions including BCL-2, JNK1, and eIF4E were performed with a fragment library of 6,500 compounds, and hit rates were compared for these targets. For eIF4E, a protein containing a PPI site and a nucleotide binding site, results from a BLI fragment screen were compared to results obtained in biochemical HTS screens. Overlapping hits were observed for the PPI site, and hits unique to the BLI screen were identified. Hit assessments with SPR and BLI are described. | This review is focused on methods for detecting small molecules and, in particular, the characterisation of their interaction with natural proteins (e.g. receptors, ion channels). Because there are intrinsic advantages to using label-free methods over labelled methods (e.g. fluorescence, radioactivity), this review only covers label-free techniques. We briefly discuss available techniques and their advantages and disadvantages, especially as related to investigating the interaction between small molecules and proteins. The reviewed techniques include well-known and widely used standard analytical methods (e.g. HPLC-MS, NMR, calorimetry, and X-ray diffraction), newer and more specialised analytical methods (e.g. biosensors), biological systems (e.g. cell lines and animal models), and in-silico approaches. | Blunt trauma abdomen rarely leads to gastrointestinal injury in children and isolated gastric rupture is even rarer presentation. We are reporting a case of isolated gastric rupture after fall from height in a three year old male child. | eng_Latn | 8,969 |
We report a combined three-dimensional structural and fluid structure interaction finite element study of an orthogonal surface acoustic wave (SAW) device based on langasite (LGS). Our simulation results indicate that simultaneous sensing and nonspecifically bound protein removal can be achieved through the use of multidirectional transducers on a single piezoelectric device. We find that the (0, 22, 90) Euler direction on the LGS-based device is suitable for biosensing via propagation of pure shear-horizontal waves, whereas the (0, 22, 0) direction allows for acoustic streaming induced biofouling removal through the propagation of mixed mode waves with prominent surface normal component. This study reveals the possibility of integrating sensing and biofouling removal functions on a single SAW device, thereby enhancing sensor performance. | Non-specific adsorption (NSA) is a persistent problem that negatively affects biosensors, decreasing sensitivity, specificity, and reproducibility. Passive and active removal methods exist to remedy this issue, by coating the surface or generating surface forces to shear away weakly adhered biomolecules, respectively. However, many surface coatings are not compatible or effective for sensing, and thus active removal methods have been developed to combat this phenomenon. This review aims to provide an overview of methods of NSA reduction in biosensing, focusing on the shift from passive methods to active methods in the past decade. Attention is focused on protein NSA, due to their common use in biosensing for biomarker diagnostics. To our knowledge, this is the first review to comprehensively discuss active NSA removal methods. Lastly, the challenges and future perspectives of NSA reduction in biosensing are discussed. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 8,970 |
In this paper, we report a fast and facile method for fabricating colloidal photonic crystals inside microchannels of ::: radially symmetric microfluidic chips. As the suspension of monodisperse silica or polystyrene latex spheres was driven ::: to flow through the channels under the centrifugal force, the colloidal spheres were quickly assembled into face centered ::: cubic arrangement which had photonic stop bands. The optical reflectance spectrum was modulated by the refractiveindex ::: mismatch between the colloidal particles and the solvent filled in the interstices between the particles. Therefore, ::: the present microfluidic chips with built-in colloidal photonic crystals can be used as in-situ optofluidic microsensors for ::: high throughput screening, light filters and biosensors in integrated adaptive optical devices. | Microfluidic approaches for controlled generation of colloidal clusters, for example, via encapsulation of colloidal particles in droplets, have been used for the synthesis of functional materials including drug delivery carriers. Most of the studies, however, use a low concentration of an original colloidal suspension ( 60 wt %) particle concentrations. Three types of microfluidic devices, PDMS flow-focusing, PDMS T-junction, and microcapillary devices, are investigated for direct encapsulation of a high concentration of polystyrene (PS) nanoparticles in droplets. In particular, it is shown that PDMS devices fabricated by soft lithography can generate droplets from a 25 wt % PS suspension, whereas microcapillary devices made from glass capillary tubes are able to produce droplets from a 67 wt % PS nanoparticle suspension. When the PS concentration is between 0.6 and 25 wt %, the size o... | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 8,971 |
The microbial diversity and community structure in twenty-one groundwater samples from high arsenic shallow aquifers of Hetao Basin, Inner Mongolia, China was investigated with an integrated approach including polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene phylogenetic analyses. A total of 25 bacterial and 32 archaeal DGGE bands were exercised for sequencing. Phylogenetic analyses showed that the bacterial DGGE bands were dominated by Proteobacteria, and the archaeal bands were dominated by Thaumarchaeota and Euryarchaeota. Based on arsenic concentrations, three samples (corresponding to low, medium, and high level of arsenic, respectively) were selected for construction of 16S rRNA gene clone libraries. A total of 912 (468 and 444 for bacteria and archaea, respectively) 16S rRNA gene clone sequences were obtained and subjected to phylogenetic analyses. The results showed that bacterial communities of these samples were dominated by Acinetobacter, Pseudomo... | A survey was carried out on the microbial community of 20 groundwater samples (4 low and 16 high arsenic groundwater) and 19 sediments from three boreholes (two high arsenic and one low arsenic boreholes) in a high arsenic groundwater system located in Hetao Basin, Inner Mongolia, using the 454 pyrosequencing approach. A total of 233,704 sequence reads were obtained and classified into 12-267 operational taxonomic units (OTUs). Groundwater and sediment samples were divided into low and high arsenic groups based on measured geochemical parameters and microbial communities, by hierarchical clustering and principal coordinates analysis. Richness and diversity of the microbial communities in high arsenic sediments are higher than those in high arsenic groundwater. Microbial community structure was significantly different either between low and high arsenic samples or between groundwater and sediments. Acinetobacter, Pseudomonas, Psychrobacter and Alishewanella were the top four genera in high arsenic groundwater, while Thiobacillus, Pseudomonas, Hydrogenophaga, Enterobacteriaceae, Sulfuricurvum and Arthrobacter dominated high arsenic sediments. Archaeal sequences in high arsenic groundwater were mostly related to methanogens. Biota-environment matching and co-inertia analyses showed that arsenic, total organic carbon, SO4(2-), SO4(2-)/total sulfur ratio, and Fe(2+) were important environmental factors shaping the observed microbial communities. The results of this study expand our current understanding of microbial ecology in high arsenic groundwater aquifers and emphasize the potential importance of microbes in arsenic transformation in the Hetao Basin, Inner Mongolia. | In this paper, we present a new design for an electro-optic modulator ⎯ operating at the telecomm wavelength of 1550 nm and having a very high extinction ratio ⎯ based on photonic crystal (PhC) slab waveguide and phase change material Germanium Selenide (GeSe) embedded in core silicon layer. The device is based on the shifting of the photonic bandgap of the PhC slab waveguide when the refractive index of the GeSe layer changes on application of electric field. Since GeSe changes from its phase crystalline to amorphous on application of an electric field, its refractive index also changes when this phase transition occurs. As a result of a large refractive index contrast between the two phases, the change in the effective refractive index in the PhC slab waveguide is also very high. With two self-sustainable states, the hybrid modulator shows broadband switching capability and an On/Off extinction ratio > 37 dB around a wavelength of 1550 nm. | eng_Latn | 8,972 |
The on-chip measurement of absorbing species has proven to be challenging, particularly with respect to the sample pathlengths available in a miniaturised system. This paper demonstrates how the principles of total internal reflection can be utilised to form a liquid-core waveguide along a single microfluidic channel, increasing the sampling pathlength to 5 mm while maintaining a detection volume of ≤1 µL. This was achieved using the Teflon fluoropolymers PTFE, FEP and AF as cladding for the liquid-core waveguide. In conjunction with a 3D chip architecture, the use of the liquid-core waveguide enables more efficient use of the probing light beam along with easy and effective coupling of the source, microfluidic chip and the detection system. The confirmation that waveguiding was occurring was successfully demonstrated and the subsequent spectrophotometric analysis of crystal violet provided a linear calibration with reproducibility (<2.4% RSD) and limits of detection (<1.3 µM), comparable to absorbance measurements made with a standard UV-Vis spectrophotometer. | Nanoporous Solid-Liquid core waveguides were prepared by UV induced surface modification of hydrophobic nanoporous polymers. With this method, the index contrast (δn = 0.20) is a result of selective water infiltration. The waveguide core is defined by UV light, rendering the exposed part of a nanoporous polymer block hydrophilic. A propagation loss of 0.62 dB/mm and a bend loss of 0.81 dB/90° for bend radius as low as 1.75 mm was obtained in these multimode waveguides. | Microalgae have a demonstrated potential as producers of high-quality renewable biofuel feedstocks as well as other high-value chemicals. However, significant improvements from microalgal biology and strain development to downstream processing are required to achieve economically viable microalgae-derived biofuels and bioproducts. Mainstream techniques used in microalgal research are based on conventional cell culture and cell handling systems, which are bulky, labor-intensive, time-consuming, and also limited in throughput. Microfluidic lab-on-a-chip systems can offer cost- and time-efficient alternatives to advance microalgal biofuel and bioproduction research by providing high precision and high efficiency cell/reagent handling capabilities, enabling high-throughput assays in a fully automated fashion. Here, we review recent advances in the development and application of microfluidic lab-on-a-chip systems for microalgal biotechnology, especially microalgae-based biofuels, including microsystems for single-cell resolution high-throughput cell identification and separation, highly efficient cell transformation, high-throughput parallel cell cultivation, cell harvesting, and cell analysis applications. Other microfluidic applications such as microalgae-based fuel cells and microalgae-based biosensing platforms are also reviewed towards the end. We conclude by suggesting possible future directions on how microfluidic lab-on-a-chip systems can be utilized to overcome current challenges and improve the current status in microalgal biotechnology. | eng_Latn | 8,973 |
The opto-mechanical properties of a photo-responsive nematic polymer network (PRPN) are investigated using molecular dynamics simulation. For the implementation of the trans-to-cis isomerization of azo compounds, a switchable potential formalism for the N = N bond is applied to the crosslinked PRPN unit cell model. During the light switch-on and heating-up simulations at a wide range of temperatures, the scalar orientational order parameter for the mesogenic side group molecules, the effective photo-induced strain of the bulk polymer network, and the opto-mechanical properties are characterized. The correlation between the microstate which belongs to the molecular location and the macroscopically observed photostrain is identified according to the isomerization ratio of the diazene groups. | A liquid crystal network whose chromophores are functionalized by photochromic dye exhibits light-induced mechanical behaviour. As a result, the micro-scaled thermotropic traits of the network and the macroscopic phase behaviour are both influenced as light alternates the shape of the dyes. In this paper, we present an analysis of this photomechanical behaviour based on the proposed multiscale framework, which incorporates the molecular details of microstate evolution into a continuum-based understanding. The effects of trans-to-cis photoisomerization driven by actinic light irradiation are first examined using molecular dynamics simulations, and are compared against the predictions of the classical dilution model; this reveals certain characteristics of mesogenic interaction upon isomerization, followed by changes in the polymeric structure. We then upscale the thermotropic phase-related information with the aid of a nonlinear finite element analysis; macroscopic deflection with respect to the wide ranges of temperature and actinic light intensity are thereby examined, which reveals that the classical model underestimates the true deformation. This work therefore provides measures for analysing photomechanics in general by bridging the gap between the micro- and macro-scales. | Background ::: Serum calcium (Ca) and inorganic phosphate (Pi) concentrations and calcium-phosphate product (CPP) levels are positively associated with worse outcomes in patients with chronic kidney disease, but there are few data for Pi or Ca and none for CPP in patients with chronic heart failure (CHF). | eng_Latn | 8,974 |
: A number of recent studies by this group and others have demonstrated the ability of normal Raman and surface-enhanced Raman spectroscopy (SERS) to identify bacteria at the species level. Our efforts have focused on the use of colloidal silver as the SERS active substrate. The addition of silver nanoparticles to the bacteria not only produces an enhanced Raman signal, but it also suppresses the native biofluorescence associated with visible laser excitation. Raman chemical imaging uses every pixel or a binned pixel group of the Raman camera as an independent Raman spectrograph. Thus, spatially resolved Raman spectral information is obtained; much like a visual microscope provides spatially resolved visual information. The advantage of this technique in biological detection resides primarily in analysis of biological samples in complex backgrounds without the need for any sample pre-processing. Using a chemical imaging Raman microscope, we compare normal Raman chemical imaging to SERS chemical imaging of a complex mixture of bacteria. In both cases we are able to differentiate single bacteria in the Raman microscope's field of view, but with a substantial reduction in analysis time for SERS chemical imaging. | A novel method was developed to rapidly concentrate, detect, and differentiate bacteria in skimmed milk using surface enhanced Raman scattering (SERS) mapping on 4-mercaptophenylboronic acid (4-MPBA) functionalized silver (Ag) dendrites. The 4-MPBA functionalized Ag dendritic SERS substrate was used to capture the bacterial cells and enhance the bacterial signal. Salmonella, a significantly important food pathogen, was used as the representative strain to optimize and evaluate the developed method. The capture efficiency for Salmonella enterica subsp enterica BAA1045 (SE1045) was 84.92 ± 3.25% at 106 CFU/mL and as high as 99.65 ± 3.58% at 103 CFU/mL. Four different strains, two gram-negative and two gram-positive, can be clearly distinguished by their SERS spectra using principle component analysis. A mapping technique was utilized to automatically collect 400 spectra over an area of 60 μm × 60 μm to construct a visual image for a sensitive and statistically reliable detection within 30 min. Using this method, we were able to detect as low as 103 CFU/mL bacterial cells in 50 mM NH4HCO3 solution and 102 CFU/mL cells in both 1% casein and skimmed milk. Our results demonstrate the feasibility of using SERS mapping method coupled with 4-MPBA functionalized Ag dendrites for rapid and sensitive bacteria detection in complex liquid samples. Graphical A novel SERS mapping method based on 4-mercaptophenylboronic acid functionalized silver (Ag) dendrites was developed to rapidly concentrate, detect, and differentiate bacteria. | All molecules consist of chemical bonds, and much can be learned from mapping the spatiotemporal dynamics of these bonds. Since its invention a decade ago, stimulated Raman scattering (SRS) microscopy has become a powerful modality for imaging chemical bonds with high sensitivity, resolution, speed and specificity. We introduce the fundamentals of SRS microscopy and review innovations in SRS microscopes and imaging probes. We highlight examples of exciting biological applications, and share our vision for potential future breakthroughs for this technology. | eng_Latn | 8,975 |
We report the microfluidic fabrication of robust and fluid tethered bilayer arrays within a poly(dimethylsiloxane) (PDMS) chip, and demonstrate its addressability and biosensing by incorporating the GM1 receptor into the bilayer framework for detection of cholera toxin. Rapid optimization of the experimental conditions is achieved by using nanoglassified surfaces in combination with surface plasmon resonance. The ultrathin glassy film on gold mimics glass surfaces employed in microfluidics, allowing real-time monitoring of multiple assembly steps and therefore permitting rapid prototyping of microfluidic arrays. The tethered bilayer array utilizes a covalently immobilized biotinylated protein for generation of well-defined capture zones where a streptavidin link is employed for the immobilization of biotinylated vesicles. Fusion of captured vesicles is accomplished using a concentrated PEG solution, and the lateral diffusion of the tethered bilayer membrane is characterized by fluorescence recovery after photobleaching methods. The tethered membrane arrays demonstrate marked stability and high mobility, which provide an ideal host environment for membrane-associated proteins and open new avenues for high-throughput analysis of these proteins. | Infectious diseases are still a major healthcare problem. From food intoxication and contaminated water, to hospital-acquired diseases and pandemics, infectious agents cause disease throughout the world. Despite advancements in pathogens' identification, some of the gold-standard diagnostic methods have limitations, including laborious sample preparation, bulky instrumentation and slow data readout. In addition, new field-deployable diagnostic modalities are urgently needed in first responder and point-of-care applications. Apart from compact, these sensors must be sensitive, specific, robust and fast, in order to facilitate detection of the pathogen even in remote rural areas. Considering these characteristics, researchers have utilized innovative approaches by employing the unique properties of nanomaterials in order to achieve detection of infectious agents, even in complex media like blood. From gold nanoparticles and their plasmonic shifts to iron oxide nanoparticles and changes in magnetic properties, detection of pathogens, toxins, antigens and nucleic acids has been achieved with impressive detection thresholds. Additionally, as bacteria become resistant to antibiotics, nanotechnology has achieved the rapid determination of bacterial drug susceptibility and resistance using novel methods, such as amperometry and magnetic relaxation. Overall, these promising results hint to the adoption of nanotechnology-based diagnostics for the diagnosis of infectious diseases in diverse settings throughout the globe, preventing epidemics and safeguarding human and economic wellness. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 8,976 |
The intermediate photolytic sequence of octopus rhodopsin was studied at different temperatures and different pH values by means of a flash photolysis-rapid scan spectrophotometry near physiological temperature. The first photoproduct in the photolysis of rhodopsin was lumirhodopsin. Transformation of lumirhodopsin leads to mesorhodopsin took place independently of the pH of the solution. Mesorhodopsin was transformed to acid metarhodopsin in acid solution. In alkaline solution, mesorhodopsin was transformed to transient acid metarhodopsin whose absorption spectrum was similar to acid metarhodopsin. Transient acid metarhodopsin was then transformed to alkaline metarhodopsin reaching a tautomeric equilibrium which was determined by the pH of the solution. | A spectrally silent transformation in the photolysis of octopus rhodopsin was detected by the time-resolved transient grating method. Our results showed that at least two photointermediates, which share the same chromophore absorption spectrum, exist after the final absorption changes. Previously, mesorhodopsin was thought to decay to the final photoproduct, acid metarhodopsin with a lifetime of 38 micros at 15 degrees C, but the present results show that there is at least one intermediate species (called transient acid metarhodopsin) with a lifetime of 180 micros at 15 degrees C, before forming acid metarhodopsin. This indicates that the parts of the protein distant from the chromophore are still changing even after the changes in microenvironment around the chromophore are over. From the signal intensity detected by the transient grating method, the volume change of the spectrally silent transformation was found to be DeltaV = 13 ml/mol. The activation energy of the spectrally silent transformation is much lower than those of other transformations of octopus rhodopsin. Since stable acid metarhodopsin has not been shown to activate the G protein, this transient acid metarhodopsin may be responsible for G protein activation. | A spectrally silent transformation in the photolysis of octopus rhodopsin was detected by the time-resolved transient grating method. Our results showed that at least two photointermediates, which share the same chromophore absorption spectrum, exist after the final absorption changes. Previously, mesorhodopsin was thought to decay to the final photoproduct, acid metarhodopsin with a lifetime of 38 micros at 15 degrees C, but the present results show that there is at least one intermediate species (called transient acid metarhodopsin) with a lifetime of 180 micros at 15 degrees C, before forming acid metarhodopsin. This indicates that the parts of the protein distant from the chromophore are still changing even after the changes in microenvironment around the chromophore are over. From the signal intensity detected by the transient grating method, the volume change of the spectrally silent transformation was found to be DeltaV = 13 ml/mol. The activation energy of the spectrally silent transformation is much lower than those of other transformations of octopus rhodopsin. Since stable acid metarhodopsin has not been shown to activate the G protein, this transient acid metarhodopsin may be responsible for G protein activation. | eng_Latn | 8,977 |
Stacked white organic light-emitting devices (WOLEDs) comprising of blue fluorescent and orange phosphorescent emissive units employing tri(8-hydroxyquinoline) aluminum (Alq3):Mg/MoO3 as charge generation layer are fabricated. The working mechanism of Alq3:Mg/MoO3 is also discussed using a simple method. We demonstrate charge-carrier separation takes place only in MoO3 layer. Stacked WOLED with better performance was obtained by adjusting the thickness of MoO3. The stacked WOLED with efficiency of 39.2 cd/A has excellent color stability with the Commission Internationale de l’Eclairage coordinates only changing from (0.407, 0.405) to (0.398, 0.397) when luminance increases from 22 to 10 000 cd/m2. | Organic light-emitting diode (OLED)-based display products have already emerged in the market and their efficiencies and lifetimes are sound at the comparatively low required luminance. To realize OLED for lighting application sooner, higher light quality and better power efficiency at elevated luminance are still demanded. This review reveals the advantages of incorporating a nano-scale carrier modulation layer (CML), also known as a spacer, carrier-regulating layer, or interlayer, among other terms, to tune the chromaticity and color temperature as well as to markedly improve the device efficiency and color rendering index (CRI) for numerous OLED devices. The functions of the CML can be enhanced as multiple layers and blend structures are employed. At proper thickness, the employment of CML enables the device to balance the distribution of carriers in the two emissive zones and achieve high device efficiencies and long operational lifetime while maintaining very high CRI. Moreover, we have also reviewed the effect of using CML on the most significant characteristics of OLEDs, namely: efficiency, luminance, life-time, CRI, SRI, chromaticity, and the color temperature, and see how the thickness tuning and selection of proper CML are crucial to effectively control the OLED device performance. | The hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hempitera: Adelgidae), threatens the health and sustainability of the native eastern North American hemlocks, Tsuga canadensis (L.) Carriere and T. caroliniana Engelman. The lineage of HWA that was introduced to the eastern United States came from Japan sometime prior to 1951, and did not co-evolve with eastern North American forest ecosystems (Havill et al. 2006). As a result, eastern hemlock species cannot adequately resist or tolerate the impacts of adelgid feeding, and the native community of natural enemies in eastern North America is not capable of maintaining HWA populations below damaging levels. This results in widespread death of hemlock trees, which is having serious consequences for biodiversity, ecosystem functions, and ornamental and urban resources. | eng_Latn | 8,978 |
The synthesis and photophysical properties of a tetra-PEG-modified and freely water-soluble quinoline-annulated porphyrin are described. We previously demonstrated the ability of quinoline-annulated porphyrins to act as an in vitro NIR photoacoustic imaging (PAI) contrast agent. The solubility of the quinoline-annulated porphyrin derivative in serum now allowed the assessment of the efficacy of the PEGylated derivative as an in vivo NIR contrast agent for the PAI of an implanted tumor in a mouse model. A multi-fold contrast enhancement when compared to the benchmark dye ICG could be shown, a finding that could be traced to its photophysical properties (short triplet lifetimes, low fluorescence and singlet oxygen sensitization quantum yields). A NIR excitation wavelength of 790 nm could be used, fully taking advantage of the optical window of tissue. Rapid renal clearance of the dye was observed. Its straight-forward synthesis, optical properties with the possibility for further optical fine-tuning, nontoxicity, favorable elimination rates, and contrast enhancement make this a promising PAI contrast agent. The ability to conjugate the PAI chromophore with a fluorescent tag using a facile and general conjugation strategy was also demonstrated. | The development of low-cost and fast photoacoustic microscopy systems enhances the clinical applicability of photoacoustic imaging systems. To this end, we present a laser scanning laser diode-based photoacoustic microscopy system. In this system, a 905 nm, 325 W maximum output peak power pulsed laser diode with 50 ns pulsewidth is utilized as the light source. A combination of aspheric and cylindrical lenses is used for collimation of the laser diode beam. Two galvanometer scanning mirrors steer the beam across a focusing aspheric lens. The lateral resolution of the system was measured to be ∼21 μm using edge spread function estimation. No averaging was performed during data acquisition. The imaging speed is ∼370 A-lines per second. Photoacoustic microscopy images of human hairs, ex vivo mouse ear, and ex vivo porcine ovary are presented to demonstrate the feasibility and potentials of the proposed system. | Background ::: Serum calcium (Ca) and inorganic phosphate (Pi) concentrations and calcium-phosphate product (CPP) levels are positively associated with worse outcomes in patients with chronic kidney disease, but there are few data for Pi or Ca and none for CPP in patients with chronic heart failure (CHF). | eng_Latn | 8,979 |
Surfaces -defined as the interfaces between solids and liquids- have attracted much attention in optics and biology, such as total internal reflection imaging (TIRF) and DNA microarrays. Within the context of optofluidics however, surfaces have received little attention. In this paper, we describe how surfaces can define or enhance optofluidic function. More specifically we discuss chemical interfaces that control the orientation of liquid crystals and the stretching of individual nucleic acids, diffractive and plasmonic nanostructures for lasing and opto-thermal control, as well as microstructures that read pressure and form chemical patterns. | We report recent progress in the development of surface-enhanced Raman scattering (SERS)-based optofluidic platforms for the fast and sensitive detection of chemical and biological analytes. In the current context, a SERS-based optofluidic platform is defined as an integrated analytical device composed of a microfluidic element and a sensitive Raman spectrometer. Optofluidic devices for SERS detection normally involve nanocolloid-based microfluidic systems or metal nanostructure-embedded microfluidic systems. In the current review, recent advances in both approaches are surveyed and assessed. Additionally, integrated real-time sensing systems that combine portable Raman spectrometers with microfluidic devices are also reviewed. Such real-time sensing systems have significant utility in environmental monitoring, forensic science and homeland defense applications. | It is proved that special flows over irrational rotations and under functions whose Fourier coefficients are of order O(1/| n |) are disjoint in the sense of Furstenberg from all mixing flows. This is an essential strengthening of a classical result by Kocergin on the absence of mixing of special flows built over irrational rotations and under bounded variation roof functions. | eng_Latn | 8,980 |
Summary ::: ::: Scanning force microscopy (SFM) holds great promise for biological research. Two major problems that have confronted imaging with the scanning force microscope have been the distortion of the image and overestimation in measurements of lateral size due to the varying geometry and characteristics of the scanning tip. In this study, spherical colloidal gold particles (10, 20 and 40 nm in diameter) were used to determine (1) tip parameters (size, shape and semivertical angle); (2) the distortion of the image caused by the tip; and (3) the overestimation or broadening of lateral dimensions. These gold particles deviate little in size, are rigid and have a size similar to biological macromolecules. Images of the colloidal gold particles by SFM were compared with those obtained by electron microscopy (EM). The height of the gold particles as measured by SFM and EM was comparable and was little affected by the tip geometry. The measurements of the lateral dimensions of colloidal gold, however, showed substantial differences between SFM and EM in that SFM resulted in an overestimate of the lateral dimensions. Moreover, the distortion of images and broadening of lateral dimensions were specific to the SFM tip used. The calibration of the SFM tip with mica provided little clue as to the type of distortion and the amount of lateral broadening observed when the larger gold particles were scanned. The SFM image also depended on the orientation of the tip with respect to the specimen. Our results suggest that quantitative SFM imaging requires calibration to identify and account for both the distortions and the magnitude of lateral broadening caused by the cantilever tip. Calibration with gold particles is fast and nondestructive to the tip. The raw imaging data of the specimen can be corrected for the tip effect and true structural information can be derived. In summary, we present a simple and practical method for the calibration of the SFM tip using gold particles with a size in the range of biomacromolecules that allows: (1) selection of a cantilever tip that produces an image with minimal distortion; (2) quantitative determination of tip parameters; (3) reconstruction of the shape of the tip at different heights from the tip apex; (4) appreciation of the type of distortion that may be introduced by a specific tip and quantification of the overestimation of the lateral dimensions; and (5) calculation of the true structure of the specimen from the image data. The significance is that such calibration will permit quantitative and accurate imaging with SFM. | A new method for the analysis of protein colloidal diameter has been developed using three existing protein concentration quantification techniques, absorption at 280 nm, colloidal gold assay, and DC protein assay. Protein colloids are formed in the process of aggregation and are thought to be intermediates in protein self-assembly and formation of amyloid fiber. Deposition of the protein fibers in tissues leads to numerous human diseases including Alzheimer’s. Lysozyme was incubated at pH 2.0, 55°C, an environment conducive to amyloid fiber formation. The protein colloids present in the supernatant of the samples after centrifugation were studied over a time course of 30 days. The OD 280 assay detects total protein concentration based on absorption of radiation in the near UV. The colloidal gold assay and DC protein assay only measure colloidal sphere surface protein concentration. Due to the surface plasmon resonance, the light absorption spectrum changes when proteins bind to colloidal gold particles. Using the measured protein concentration on the surface of protein colloids along with the total measured protein concentration in the entire protein colloidal spheres, an interior protein concentration for all colloids is obtained. The protein colloidal sphere size can be calculated by using the ratio between the interior protein concentration and total protein concentration. Results indicate that the colloidal gold assay, DC protein assay, and OD 280 assay can be used to quantify the size of the protein colloids. The colloidal gold assay and DC protein assay are both independently effective in analysis of surface protein concentration in protein colloids. The DC protein assay was found to be much quicker in data production as it only requires 15 minutes of incubation time. The DC protein assay was also more reliable than the colloidal gold assay in accuracy and precision of results. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 8,981 |
Electrospun nanofibrous film doped with a fluorescent conjugated polymer P was developed as a sensory device for detection of the explosive 2,4-dinitrotoluene (DNT). Polymer P obtained through a Sonogashira cross-coupling polymerization showed high affinity and excellent fluorescence quenching property toward electro-deficient compound DNT in solution. A versatile and effective electrospinning technique, which effectively reduced aggregation and fluorescence self-quenching of the conjugated polymers in thin film by the traditional spin-casting, was successfully employed to develop explosive-sensing nanofibrous devices. By doping with polystyrene as supporting matrix and subsequent electrospinning, the obtained fluorescent nanofibrous film exhibited remarkable sensitivity to trace DNT vapor due to a large surface area-to-volume ratio and unique porous structure. The sensitivity of the device was further improved by introducing secondary pores into the nanofibers through addition of a surfactant, sodium dod... | Conjugated polymer P, which was synthesized by introducing 9,9-diphenylfluorene and thiophene units into the backbone of poly(fluorenylene ethynylene), showed high sensitivity in detecting nitroaromatics. A double-layer sensor, named P-PS/GEL, was prepared by electrospinning technique using polymer P, polystyrene (PS), and gelatin (GEL). A nanofibrous membrane from the mixture of PS and P as the top layer (P-PS) served as the sensing layer for detecting nitroaromatics (NACs). A gelatin nanofibrous membrane as the bottom layer (GEL) served as porous scaffold for the top layer. Therefore, apart from transferring into the top layer directly from above, the NACs molecules could also approach the top sensing layer through the bottom porous layer. This double-layer conformation greatly improved the permeability of the P-PS layer. As a result, the double-layer sensor exhibited a greater quenching efficiency (Q f) of 75 % than that of the single-layer P-PS (55 %). Importantly, the sensor showed good reversibility of quenching process after being exposed to saturated DNT vapor for 6 cycles. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 8,982 |
Secondary metabolites in plant material can be imaged in a simple and robust way by creating an imprint of the plant material on a porous Teflon surface. The Teflon surface serves to extract compounds from the plant material for enhanced desorption electrospray ionization imaging analysis, while maintaining the spatial information of the sample. The method, which remedies for limitations in mass spectrometry imaging of compounds embedded in plant material, was demonstrated on leaves and petals of Hypericum perforatum and leaves of Datura stramonium. | Natural products continue to serve as an important source of novel drugs since the beginning of human history. High-throughput techniques, such as MALDI-MS, can be techniques of choice for the rapid screening of natural products in plant materials. We present here a fast and reproducible matrix-free approach for the direct detection of UV active metabolites in plant materials without any prior sample preparation. The plant material is mechanically ground to a fine powder and then sieved through different mesh sizes. The collected plant material is dispersed using 1 μL solvent on a target plate is directly exposed to Nd:YAG 335 nm laser. The strategy was optimized for the analysis of plant metabolites after study of the different factors affecting the reproducibility and effectiveness of the analysis, including particle sizes effects, types of solvents used to disperse the sample, and the part of the plant analyzed. Moreover, several plant species, known for different classes of metabolites, were screened to establish the generality of the approach. The developed approach was validated by the characterization of withaferin A and nicotine in the leaves of Withania somnifera and Nicotiana tabacum, respectively, through comparison of its MS/MS data with the standard compound. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques were used for the tissue imaging purposes. This approach can be used to directly probe small molecules in plant materials as well as in herbal and pharmaceutical formulations for fingerprinting development. | Solar cells, as promising devices for converting light into electricity, have a dramatically reduced performance on rainy days. Here, an energy harvesting structure that integrates a solar cell and a triboelectric nanogenerator (TENG) device is built to realize power generation from both sunlight and raindrops. A heterojunction silicon (Si) solar cell is integrated with a TENG by a mutual electrode of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film. Regarding the solar cell, imprinted PEDOT:PSS is used to reduce light reflection, which leads to an enhanced short-circuit current density. A single-electrode-mode water-drop TENG on the solar cell is built by combining imprinted polydimethylsiloxane (PDMS) as a triboelectric material combined with a PEDOT:PSS layer as an electrode. The increasing contact area between the imprinted PDMS and water drops greatly improves the output of the TENG with a peak short-circuit current of ∼33.0 nA and a peak open-circuit voltage of ∼2.14 V, res... | eng_Latn | 8,983 |
Light and electrothermal responsive polymer photonic crystals (PCs) modified with 1'-acryloyl chloride-3',3'-dimethyl-6-nitro-spiro(2H-1-benzopyran-2,2'-indoline) (SPMA) are proposed, and their dynamic display patterns are achieved through the combination of the SPMA-modified PCs and a patterned graphite layer. These PCs exhibit fluorescence under UV light irradiation because of the isomerization of the SPMA, which is restricted in the shell of the polymer colloidal spheres. After a voltage is applied to the patterned graphite layer, the fluorescence of PCs in the specific area disappears, and dynamic display patterns are obtained. Under UV light irradiation, the PCs change from the "partial-fluorescence" state to the initial "fluorescence" state, and the patterns disappear. Using this technique, the PC pattern "M L N" on the glass substrate and PC patterns from "0" to "9" on the paper substrate are fabricated. Thus, these dual-responsive PCs have potential applications in information recording, anticounterfeiting, dynamic display, and photoelectric devices. | Colour patterns based on micro-nano structure have attracted enormous research interests due to unique optical switches and smart surface applications in photonic crystal, superhydrophobic surface modification, controlled adhesion, inkjet printing, biological detection, supramolecular self-assembly, anti-counterfeiting, optical device and other fields. In traditional methods, many patterns of micro-nano structure are derived from changes of refractive index or lattice parameters. Generally, the refractive index and lattice parameters of photonic crystals are processed by common solvents, salts or reactive monomers under specific electric, magnetic and stress conditions. This review focuses on the recent developments in the fabrication of micro-nano structures for patterns including styles, materials, methods and characteristics. It summarized the advantages and disadvantages of inkjet printing, angle-independent photonic crystal, self-assembled photonic crystals by magnetic field force, gravity, electric field, inverse opal photonic crystal, electron beam etching, ion beam etching, laser holographic lithography, imprinting technology and surface wrinkle technology, etc. This review will provide a summary on designing micro-nano patterns and details on patterns composed of photonic crystals by surface wrinkles technology and plasmonic micro-nano technology. In addition, colour patterns as switches are fabricated with good stability and reproducibility in anti-counterfeiting application. Finally, there will be a conclusion and an outlook on future perspectives. | Whole retina, rod outer segments, and retinal pigment epithelium of frogs ( Rana pipiens ) fed crickets for more than 1 year had significantly lower levels of docosahexaenoic acid (22:6n-3) than the same tissues of frogs fed crickets for less than 1 month. Decreases in 22:6n-3 levels in these tissues were compensated for by increases in the n-6 polyunsaturated fatty acids (PUFAs), primarily 22:5n-6. There were no changes in the levels of saturated, monoenoic, or dienoic acids. Analysis of diacyl phospholipid molecular species (PLMS) revealed decreases in both the 22:6(n-3)-containing dipolyenoic molecular species in phosphatidylethanolamine and phosphatidylserine, and the monopolyenoic molecular species in phosphatidylcholine. These PLMS were replaced by species containing 22:5n-6 or other n-6 PUFAs. Examination of fatty acid methyl esters of total lipids extracted from crickets revealed that less than 1 mol% fatty acids were of the n-3 family, while more than 30 mol% were of the n-6 family. Thus, frogs raised on an n-3-deficient diet have reduced levels of n-3 PUFA in their retinas, rod outer segments, and retinal pigment epithelium. Although such changes have been reported for mammals, this is the first report of the effects of n-3 deficiency on the lipids of amphibians. | eng_Latn | 8,984 |
Providing sufficient, healthy food for the increasing global population is putting a great deal of pressure on the agrochemical industry to maximize crop yields without sustaining environmental damage. The growth and yield of every plant with sexual reproduction, depends on germination and emergence of sown seeds, which is affected greatly by seed disease. This can be most effectively controlled by treating seeds with pesticides before they are sown. An effective seed coating treatment requires a high surface coverage and adhesion of active ingredients onto the seed surface and the addition of adhesive agents in coating formulations plays a key role in achieving this. Although adhesive agents are known to enhance seed germination, little is understood about how they affect surface distribution of actives and how formulations can be manipulated to rationally engineer seed coating preparations with optimized coverage and efficacy. We show, for the first time, that stimulated Raman scattering microscopy can be used to map the seed surface with microscopic spatial resolution and with chemical specificity to identify formulation components distributed on the seed surface. This represents a major advance in our capability to rationally engineer seed coating formulations with enhanced efficacy. | All molecules consist of chemical bonds, and much can be learned from mapping the spatiotemporal dynamics of these bonds. Since its invention a decade ago, stimulated Raman scattering (SRS) microscopy has become a powerful modality for imaging chemical bonds with high sensitivity, resolution, speed and specificity. We introduce the fundamentals of SRS microscopy and review innovations in SRS microscopes and imaging probes. We highlight examples of exciting biological applications, and share our vision for potential future breakthroughs for this technology. | A linear gating mechanism links kinetically and structurally distinct closed and open states of NMDA receptors. During allosteric inhibition, agonist binding incudes uncoupling of structural changes from gating motions in the first transmembrane region. | eng_Latn | 8,985 |
Prior work on the fiber optic spectrochemical emission sensor called HaloSnif{trademark} has been extended to include an ultra-thin membrane which allows passage of volatile organic chlorinated compounds (VOCl). The membrane has been demonstrated to exclude H{sub 2}O during VOCl monitoring. The system is capable of measuring VOCl in gas-phase samples or aqueous solutions over a wide linear dynamic range. The lower limit of detection for trichloroethylene (TCE), perchloroethylene (PCE), carbon tetrachloride (CCl{sub 4}), and other related compounds in the gas-phase is 1 to 5 ppm{sub v/v}, and in the aqueous-phase is 5 to 10 mg/L. Waste site characterization and remediation activities often require chemical analysis in the vadose zone and in groundwater. These analyses are typically performed in analytical laboratories using widely accepted standardized methods such as gas chromatography, gas chromatography/mass spectrometry. The new developments with HaloSnif provide rapid field screening which can augment the standardized methods. | Western Research Institute conducted a study to define the various parameters that need to be considered in the design and use of a downhole submersible photoionization detector (PID) probe to measure volatile organic compounds (VOCs). Detector response under various conditions, including saturated humidity environments, temperature, and analyte concentration was studied. The relative responses for several VOC analytes were measured. The partitioning of VOCs between water and air was studied as a function of analyte concentration and temperature. The Henry`s law constant governing this partitioning represents an ideal condition at infinite dilution for a particular temperature. The results show that this partitioning is not ideal. Conditions resulting in apparent, practical deviations from Henry`s law include temperature and VOC concentration. Studies with membranes show that membranes that allow passage of VOCs also allow some passage of water vapor. A membrane could play a useful role in protecting the sensor from direct contact with liquid water down hole. A porous poly(tetrafluoroethylene) (PTFE) membrane allows for a rapid passage of VOCs. The rate of diffusion to the sensor with or without a membrane might be a limiting factor for rapid measurements. Various means of mixing may need to be considered. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 8,986 |
The osteocyte is believed to act as the main sensor of mechanical stimulus in bone, controlling signalling for bone growth and resorption in response to changes in the mechanical demands placed on our bones throughout life. However, the precise mechanical stimuli that bone cells experience in vivo are not yet fully understood. The objective of this study is to use computational methods to predict the loading conditions experienced by osteocytes during normal physiological activities. Confocal imaging of the lacunar–canalicular network was used to develop three-dimensional finite element models of osteocytes, including their cell body, and the surrounding pericellular matrix (PCM) and extracellular matrix (ECM). We investigated the role of the PCM and ECM projections for amplifying mechanical stimulation to the cells. At loading levels, representing vigorous physiological activity (3000 µɛ), our results provide direct evidence that (i) confocal image-derived models predict 350–400% greater strain amplification experienced by osteocytes compared with an idealized cell, (ii) the PCM increases the cell volume stimulated more than 3500 µɛ by 4–10% and (iii) ECM projections amplify strain to the cell by approximately 50–420%. These are the first confocal image-derived computational models to predict osteocyte strain in vivo and provide an insight into the mechanobiology of the osteocyte. | Solute transport through the bone lacunar-canalicular system is believed to be essential for osteocyte survival and function but has proved difficult to measure. We report an approach that permits direct measurement of real-time solute movement in intact bones. By using fluorescence recovery after photobleaching, the movement of a vitally injected fluorescent dye (sodium fluorescein) among individual osteocytic lacunae was visualized in situ beneath the periosteal surface of mouse cortical bone at depths up to 50 μm with laser scanning confocal microscopy. Transport was analyzed by using a two-compartment mathematical model of solute diffusion that accounted for the characteristic anatomical features of the lacunar-canalicular system. The diffusion coefficient of fluorescein (376 Da) was determined to be 3.3 ± 0.6 × 10-6 cm2/sec, which is 62% of its diffusion coefficient in water and is similar to diffusion coefficients measured for comparably sized molecules in cartilage. The diffusion of fluorescein in bone is also consistent with the presence of an osteocyte pericellular matrix whose structure resembles that proposed for the endothelial glycocalyx [Squire, J. M., Chew, M., Nneji, G., Neal, C., Barry, J. & Michel, C. (2001) J. Struct. Biol. 136, 239–255]. To our knowledge, this is the first instance where the dynamics of molecular movement has been measured directly in the bone lacunar-canalicular system. This in situ imaging approach should also facilitate the analysis of convection-based transport mechanisms in bones of living animals. | We report nearly complete preservation of “spin memory” between optical absorption and photoluminescence under excitation >0.2 eV above the band gap in nanometer GaSe slabs. | eng_Latn | 8,987 |
We have developed a simple-to-manufacture microfabricated gas preconcentrator for MEMS-based chemical sensing applications. Cavities and microfluidic channels were created using a wet etch process with hydrofluoric acid, portions of which can be performed outside of a cleanroom, instead of the more common deep reactive ion etch process. The integrated heater and resistance temperature detectors (RTDs) were created with a photolithography-free technique enabled by laser etching. With only 28 V DC (0.1 A), a maximum heating rate of 17.6 °C/s was observed. Adsorption and desorption flow parameters were optimized to be 90 SCCM and 25 SCCM, respectively, for a multicomponent gas mixture. Under testing conditions using Tenax TA sorbent, the device was capable of measuring analytes down to 22 ppb with only a 2 min sample loading time using a gas chromatograph with a flame ionization detector. Two separate devices were compared by measuring the same chemical mixture; both devices yielded similar peak areas and wi... | Gas sensor arrays often lack discrimination power to different analytes and robustness to interferants, limiting their success outside of research laboratories. This is primarily due to the widely sensitive (thus weakly-selective) nature of the constituent sensors. Here, the effect of orthogonality on array accuracy and precision by selective sensor design is investigated. Therefore, arrays of (2-5) selective and non-selective sensors are formed by systematically altering array size and composition. Their performance is evaluated with 60 random combinations of ammonia, acetone and ethanol at ppb to low ppm concentrations. Best analyte predictions with high coefficients of determination (R2) of 0.96 for ammonia, 0.99 for acetone and 0.88 for ethanol are obtained with an array featuring high degree of orthogonality. This is achieved by using distinctly selective sensors (Si:MoO3 for ammonia and Si:WO3 for acetone together with Si:SnO2) that improve discrimination power and stability of the regression coefficients. On the other hand, arrays with collinear sensors (Pd:SnO2, Pt:SnO2 and Si:SnO2) hardly improve gas predictions having R2 of 0.01, 0.86 and 0.28 for ammonia, acetone and ethanol, respectively. Sometimes they even exhibited lower coefficient of determination than single sensors as a Si:MoO3 sensor alone predicts ammonia better with a R2 of 0.68. Graphical abstract Conventional arrays (red) with weakly-selective sensors span a significantly smaller volume in the analyte space than arrays containing distinctly-selective sensors (orthogonal array, green). Orthogonal arrays feature better accuracy and precision than conventional arrays in mixtures of ammonia, acetone and ethanol. | The upgrade of the Belle experiment and the KEKB accelerator aims to increase the experimental data set of the experiment by the factor 50. This will be achieved by increasing the luminosity of the accelerator which requires also a significant detector upgrade. A new pixel detector based on the DEPFET1 technology is one of the detector upgrade requirements to handle the increased reaction rate and provide better vertex resolution. One of the features of the DEPFET detector is a long integration time of 20 µs. With the expected detector occupancy of about 2%, the detector will generate about 22 GB/s of data. | eng_Latn | 8,988 |
A complete NMR structure analysis of an eight-residue peptide, covalently bound to a single-bead of a poly(ethylene glycol) based (POEPOP 1500) resin, is described. Well resolved 1D and 2D 1H NMR spectra were obtained using magic angle spinning (MAS) Nanoprobe NMR spectroscopy at 500 MHz. The quantity of peptide on individual beads was determined after each NMR experiment by cleaving the peptide from the resin, and subsequent measurement of the fluorescence from the Abz-containing peptide in solution. It was found that about 1.6 nmol of peptide was the minimum amount needed to obtain a high resolution 1D 1H NMR spectrum in less than 20 minutes. For a complete structure elucidation by 2D 1H NMR a loading of about 6 nmol of peptide on a single-bead was required. It has been demonstrated that, with a sufficient loading on PEG-based resins, a complete structure elucidation of a resin bound octapeptide on a single bead can be achieved. This observation may be useful for screening and analysis of ‘one-bead, one-compound’ libraries. | An efficient approach in combinatorial chemistry is the synthesis of one-bead-one-compound peptide libraries. In contrast to synthesis and functional screening, which is performed in a largely automated manner, structure determination has been frequently laborious and time-consuming. Here we report an approach for de novo sequencing of peptides on single beads by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance (MALDI-FTICR) tandem mass spectrometry, using a resin with a photolinker for solid-phase peptide synthesis. Upon sorting out single beads, an efficient sample preparation on the MALDI target was developed that enables fragmentation upon irradiation of the bead-matrix mixture with the ultraviolet (UV)-MALDI laser, with enhanced yield of sequence-specific fragment ions at increased laser energy. This approach is illustrated by sequence determinations of two peptides from a library with sequences varying in a single amino acid; the feasibility with tandem-MS procedures and fragment ion assignment was ascertained by sustained off-resonance irradiation/collision induced dissociation (SORI/CID) and infrared multiphoton dissociation (IRMPD) fragmentation. | Solar cells, as promising devices for converting light into electricity, have a dramatically reduced performance on rainy days. Here, an energy harvesting structure that integrates a solar cell and a triboelectric nanogenerator (TENG) device is built to realize power generation from both sunlight and raindrops. A heterojunction silicon (Si) solar cell is integrated with a TENG by a mutual electrode of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film. Regarding the solar cell, imprinted PEDOT:PSS is used to reduce light reflection, which leads to an enhanced short-circuit current density. A single-electrode-mode water-drop TENG on the solar cell is built by combining imprinted polydimethylsiloxane (PDMS) as a triboelectric material combined with a PEDOT:PSS layer as an electrode. The increasing contact area between the imprinted PDMS and water drops greatly improves the output of the TENG with a peak short-circuit current of ∼33.0 nA and a peak open-circuit voltage of ∼2.14 V, res... | eng_Latn | 8,989 |
: The rare-earth diphthalocyanines have potential applications in flat-panel multicolor displays for military purposes. Lutetium diphthalocyanine electrochromic films were investigated in oxygen-free chloride solutions from pH 1 to 7 by spectroelectrochemical methods under near equilibrium conditions. Colors are reported in CIE and Munsell notations calculated from absorption spectra. The results include a comprehensive pH-potential-color diagram and a unified scheme for the electrochemical reactions of the display material. Stability zones are defined for the principal colors orange, green, light blue (two types), dark purple-blue, and violet. Yellows, blue-greens, and additional dark blues are shown to result from blending pairs of principal colors in specified proportions. Other color modifications arising from discontinuities in the electrochromic film are treated in terms of a mathematical model. The results and methodology of this study will be useful in further work to optimize the display colors and extend the cycle life. | The increase in the interaction between man and machine has made display devices indispensable for visual communication. The information which is to be communicated from a machine can be often in the form of color images. Electrochromic display device (ECD) is one of the most powerful candidate for this purpose and has various merits such as multicolor, high contrast, optical memory, and no visual dependence on viewing angle. A large number of electrochromic materials are available from almost all branches of synthetic chemistry. In this review, we have tried to describe the fundamentals of such electrochromic materials and their use in EDDs. The most important examples from major classes of electrochromic materials namely transition metal oxides, Prussian blue, phthalocyanines, viologens, fullerenes, dyes and conducting polymers (including gels) are described. Examples of their use in both prototype and commercial electrochromic devices are given. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 8,990 |
Calculations of the normalized absorption, scattering, and total attenuation cross-sections of water spheres are presented for the wavelength range from 4 μ to 24 μ, at intervals of 1 μ for the wavelength interval from 4 μ to 10 μ, and at 2 μ intervals thereon to 24 μ. The calculations have been carried out to values of α (α is the ratio of sphere circumference to wavelength) of 30. For values of the Mie absorption parameter, k, greater than approximately 0·10, values of the normalized absorption cross-section are shown to have a maximum which exceeds unity by an appreciable amount. In all instances, the values of the normalized scattering and total attenuation cross-sections exceed unity over most ranges of α considered, the excess over unity being greater for small values of absorption. Some rough calculations are made comparing Mie absorption coefficients with those for bulk-water absorption at the same wavelength. | Information content analysis is used to select channels for a marine liquid cloud retrieval using the high-spectral-resolution oxygen A-band instrument on NASA's Orbiting Carbon Observatory-2 (OCO-2). Desired retrieval properties are cloud optical depth, cloud-top pressure and cloud pressure thickness, which is the geometric thickness expressed in hectopascals. Based on information content criteria we select a micro-window of 75 of the 853 functioning OCO-2 channels spanning 763.5–764.6 nm and perform a series of synthetic retrievals with perturbed initial conditions. We estimate posterior errors from the sample standard deviations and obtain ±0.75 in optical depth and ±12.9 hPa in both cloud-top pressure and cloud pressure thickness, although removing the 10 % of samples with the highest χ 2 reduces posterior error in cloud-top pressure to ±2.9 hPa and cloud pressure thickness to ±2.5 hPa. The application of this retrieval to real OCO-2 measurements is briefly discussed, along with limitations and the greatest caution is urged regarding the assumption of a single homogeneous cloud layer, which is often, but not always, a reasonable approximation for marine boundary layer clouds. | The development of photodynamic therapy into a modality for treatment of prostate cancer calls for reliable optical dosimetry. We employ, for the first time, interstitial time-resolved spectroscopy to determine in vivo optical properties of human prostate tissue. Nine patients are included in the study, and measurements are conducted prior to primary brachytherapy treatment of prostate cancer. Intrasubject variability is examined by measuring across three tissue volumes within each prostate. The time-resolved instrumentation proves its usefulness by producing good signal levels in all measurements. We are able to present consistent values on reduced scattering coefficients (mu(s)'), absorption coefficients (mu(a)), and effective attenuation (mu(eff)) at the wavelengths 660, 786, and 916 nm. At 660 nm, mu(s)' is found to be 9+/-2 cm(-1), and mu(a) is 0.5+/-0.1 cm(-1). Derived values of mu(eff) are in the range of 3 to 4 cm(-1) at 660 nm, a result in good agreement with previously published steady state data. Total hemoglobin concentration (THC) and oxygen saturation are spectroscopically determined using derived absorption coefficients. Derived THC values are fairly variable (215+/-65 microM), while derived values of oxygen saturation are gathered around 75% (76+/-4%). Intrasubject variations in derived parameters correlate (qualitatively) with the heterogeneity exhibited in acquired ultrasound images. | eng_Latn | 8,991 |
Biological processes are intrinsically dynamic. Although traditional methods provide valuable insights for the understanding of many biological phenomena, the possibility of measuring, quantifying, and localizing proteins within a cell, a tissue, and even an embryo has revolutionized our train of thoughts and has encouraged scientists to develop molecular tools for the assessment of protein or protein complex dynamics within their physiological context. These ongoing efforts rest on the emergence of biophotonic techniques and the continuous improvement of fluorescent probes, allowing precise and reliable measurements of dynamic cellular functions. The march of the “ in vivo biochemistry” has begun, already yielding breathtaking results. | Small GTPases act as molecular switches that regulate various plant responses such as disease resistance, pollen tube growth, root hair development, cell wall patterning and hormone responses. Thus, to monitor their activation status within plant cells is believed to be the key step in understanding their roles. We have established a plant version of a Förster resonance energy transfer (FRET) probe called Ras and interacting protein chimeric unit (Raichu) that can successfully monitor activation of the rice small GTPase OsRac1 during various defence responses in rice cells. Here, we describe the protocol for visualizing spatiotemporal activity of plant Rac/ROP GTPase in living plant cells, transfection of rice protoplasts with Raichu-OsRac1 and acquisition of FRET images. Our protocol should be widely adaptable for monitoring activation for other plant small GTPases and for other FRET sensors in various plant cells. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 8,992 |
Cell penetrating peptides (CPPs) have attracted recent interest as drug delivery tools, although the mechanisms by which CPPs are internalized by cells are not well-defined. Here, we report a new experimental approach for the detection and secondary structure determination of CPPs in live cells using Raman microscopy with heavy isotope labeling of the peptide. As a first demonstration of principle, penetratin, a 16-residue CPP derived from the Antennapedia homeodomain protein of Drosophila, was measured in single, living melanoma cells. Carbon-13 labeling of the Phe residue of penetratin was used to shift the intense aromatic ring-breathing vibrational mode from 1003 to 967 cm−1, thereby enabling the peptide to be traced in cells. Difference spectroscopy and principal components analysis (PCA) were used independently to resolve the Raman spectrum of the peptide from the background cellular Raman signals. On the basis of the position of the amide I vibrational band in the Raman spectra, the secondary struc... | In the fast-developing fields of pharmaceutical research and industry, the implementation of Raman spectroscopy and related technologies has been very well received due to the combination of chemical selectivity and the option for non-invasive analysis of samples. This chapter explores established and potential applications of Raman spectroscopy, confocal Raman microscopy and related techniques from the early stages of drug development research up to the implementation of these techniques in process analytical technology (PAT) concepts for large-scale production in the pharmaceutical industry. Within this chapter, the implementation of Raman spectroscopy in the process of selection and optimisation of active pharmaceutical ingredients (APIs) and investigation of the interaction with excipients is described. Going beyond the scope of early drug development, the reader is introduced to the use of Raman techniques for the characterization of complex drug delivery systems, highlighting the technical requirements and describing the analysis of qualitative and quantitative composition as well as spatial component distribution within these pharmaceutical systems. Further, the reader is introduced to the application of Raman techniques for performance testing of drug delivery systems addressing drug release kinetics and interactions with biological systems ranging from single cells up to complex tissues. In the last part of this chapter, the advantages and recent developments of integrating Raman technologies into PAT processes for solid drug delivery systems and biologically derived pharmaceutics are discussed, demonstrating the impact of the technique on current quality control standards in industrial production and providing good prospects for future developments in the field of quality control at the terminal part of the supply chain and various other fields like individualized medicine. On the way from the active drug molecule (API) in the research laboratory to the marketed medicine in the pharmacy, therapeutic efficacy of the active molecule and safety of the final medicine for the patient are of utmost importance. For each step, strict regulatory requirements apply which demand for suitable analytical techniques to acquire robust data to understand and control design, manufacturing and industrial large-scale production of medicines. In this context, Raman spectroscopy has come to the fore due to the combination of chemical selectivity and the option for non-invasive analysis of samples. Following the technical advancements in Raman equipment and analysis software, Raman spectroscopy and microscopy proofed to be valuable methods with versatile applications in pharmaceutical research and industry, starting from the analysis of single drug molecules as well as complex multi-component formulations up to automatized quality control during industrial production. | Solar cells, as promising devices for converting light into electricity, have a dramatically reduced performance on rainy days. Here, an energy harvesting structure that integrates a solar cell and a triboelectric nanogenerator (TENG) device is built to realize power generation from both sunlight and raindrops. A heterojunction silicon (Si) solar cell is integrated with a TENG by a mutual electrode of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film. Regarding the solar cell, imprinted PEDOT:PSS is used to reduce light reflection, which leads to an enhanced short-circuit current density. A single-electrode-mode water-drop TENG on the solar cell is built by combining imprinted polydimethylsiloxane (PDMS) as a triboelectric material combined with a PEDOT:PSS layer as an electrode. The increasing contact area between the imprinted PDMS and water drops greatly improves the output of the TENG with a peak short-circuit current of ∼33.0 nA and a peak open-circuit voltage of ∼2.14 V, res... | eng_Latn | 8,993 |
An optical sensor for the dengue virus (DENV) E-protein based on cadmium sulfide quantum dots composited with amine functionalized graphene oxide (CdS-NH2GO) thin film was successfully developed. A specific monoclonal antibodies (IgM) were covalently attached to CdS-NH2GO via EDC/NHS coupling to sense targeted E-proteins. The SPR sensor exhibited an excellent detection limit (0.001 nM/1 pM) with sensitivity of 5.49° nM−1 for the detection of DENV E-protein. The binding affinity, as well as the performance of the Au/CdS-NH2GO/EDC-NHS/IgM film, was successfully obtained at 486.54 nM−1 in detecting DENV E-proteins. These results indicated that the Au/CdS-NH2GO/EDC-NHS/IgM film shows high potential sensitive and stronger binding towards DENV E-protein. | In this work, sensitive detection of dengue virus type 2 E-proteins (DENV-2 E-proteins) was performed in the range of 0.08 pM to 0.5 pM. The successful DENV detection at very low concentration is a matter of concern for targeting the early detection after the onset of dengue symptoms. Here, we developed a SPR sensor based on self-assembled monolayer/reduced graphene oxide-polyamidoamine dendrimer (SAM/NH2rGO/PAMAM) thin film to detect DENV-2 E-proteins. Surface characterizations involving X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirms the incorporation of NH2rGO-PAMAM nanoparticles in the prepared sensor films. The specificity, sensitivity, binding affinity, and selectivity of the SPR sensor were then evaluated. Results indicated that the variation of the sensing layer due to different spin speed, time incubation, and concentration provided a better interaction between the analyte and sensing layer. The linear dependence of the SPR sensor showed good linearity (R2 = 0.92) with the lowest detection of 0.08 pM DENV-2 E-proteins. By using the Langmuir model, the equilibrium association constant was obtained at very high value of 6.6844 TM-1 (R2 = 0.99). High selectivity of the SPR sensor towards DENV-2 E-proteins was achieved in the presence of other competitors. | In this work, sensitive detection of dengue virus type 2 E-proteins (DENV-2 E-proteins) was performed in the range of 0.08 pM to 0.5 pM. The successful DENV detection at very low concentration is a matter of concern for targeting the early detection after the onset of dengue symptoms. Here, we developed a SPR sensor based on self-assembled monolayer/reduced graphene oxide-polyamidoamine dendrimer (SAM/NH2rGO/PAMAM) thin film to detect DENV-2 E-proteins. Surface characterizations involving X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirms the incorporation of NH2rGO-PAMAM nanoparticles in the prepared sensor films. The specificity, sensitivity, binding affinity, and selectivity of the SPR sensor were then evaluated. Results indicated that the variation of the sensing layer due to different spin speed, time incubation, and concentration provided a better interaction between the analyte and sensing layer. The linear dependence of the SPR sensor showed good linearity (R2 = 0.92) with the lowest detection of 0.08 pM DENV-2 E-proteins. By using the Langmuir model, the equilibrium association constant was obtained at very high value of 6.6844 TM-1 (R2 = 0.99). High selectivity of the SPR sensor towards DENV-2 E-proteins was achieved in the presence of other competitors. | eng_Latn | 8,994 |
Acetylcholinesterase (ChE) sensor based on Prussian blue (PB) modified electrode was developed and tested for the detection of organophosphorus and carbamic pesticides. The signal of the sensor was generated in PB mediated oxidation of thiocholine recorded at +200 mv in DC mode. ChE from electric eel was immobilized by cross-linking with glutaraldehyde in the presence of bovine serum albumin (BSA) on the surface of screen-printed carbon electrode covered with PB and Nafion. The content of the surface layer (specific enzyme activity, Nafion and BSA amounts) was optimized to establish high and reliable response toward the substrate and ChE inhibitors. The ChE/PB sensor makes it possible to detect Aldicarb, Paraoxon and Parathion-Methyl with limits of detection 30, 10 and 5 ppb, respectively (incubation 10 min). The feasibility of practical application of the ChE/PB sensor developed for the monitoring of degradation of the pesticides in wine fermentation was shown. To diminish matrix interferences, the electrolysis of the grape juice with Al anode and evaporation of ethanol were suggested, however the procedures decrease the sensitivity of pesticide detection and stability of the sample tested. | Publisher Summary The need for electrochemical sensors which are able to monitor important analytes at low concentrations and with little or low interference effect and which could also allow mass production of probes and an in situ application has become more and more urgent during recent years. The modified sensors for H 2 O 2 and thiocholine detection presented in this chapter seem to be an adequate response to this demand. The use of Prussian blue (PB)-modified sensors has in fact been demonstrated to be extremely useful for H 2 O 2 amperometric detection at low applied potentials with a number of possible biosensor applications based on oxidase enzymes. PB-modified sensors have also demonstrated a very high operative stability even at alkaline pH, which makes possible the use of these probes in continuous mode for up to 50 h at pH 7.4 and for 20 h at pH 9.0. Two applications of the PB-modified screen-printed electrodes were reported. The first one is based on the coupling of the modified sensor with glucose oxidase for assembling a glucose biosensor to be applied in a continuous glucose monitoring. Analytical parameters such as stability of the biosensor were found to be satisfactory. The operational stability was found to be suitable for clinical application. In the second application, the use of PB-modified sensors as powerful tools for thiocholine detection has been proposed for pesticide quantification in grape samples during wine fermentation. | The upgrade of the Belle experiment and the KEKB accelerator aims to increase the experimental data set of the experiment by the factor 50. This will be achieved by increasing the luminosity of the accelerator which requires also a significant detector upgrade. A new pixel detector based on the DEPFET1 technology is one of the detector upgrade requirements to handle the increased reaction rate and provide better vertex resolution. One of the features of the DEPFET detector is a long integration time of 20 µs. With the expected detector occupancy of about 2%, the detector will generate about 22 GB/s of data. | eng_Latn | 8,995 |
This paper presents a cost-effective portable photodetection system for capillary electrophoresis absorptiometry. By using a CMOS BDJ (buried double p–n junction) detector, a dual-wavelength method for absorbance measurement is implemented. This system includes associated electronics for low-noise pre-amplification and A/D conversion, followed by digital signal acquisition and processing. Two signal processing approaches are adopted to enhance the signal to noise ratio. One is variable time synchronous detection, which optimizes the sensitivity and measuring rate compared to a conventional synchronous detection technique. The other is a statistical approach based on principal component analysis, which allows optimal estimation of detected signal. This system has been designed and tested in capillary electrophoresis conditions. Its operation has been verified with performances comparable to those of a commercialized spectrophotometric system (HP-3D CE). With potential on-chip integration of associated electronics, it may be operated as an integrable detection module for microchip electrophoresis and other microanalysis systems. | A buried quad junction (BQJ) photodetector has been designed and fabricated with a high-voltage CMOS process. It implements four vertically-stacked p-n junctions with four different spectral responses. This feature allows high spectral discriminating ability, greater than both conventional buried double junction and buried triple junction detectors. In this paper, we propose a SPICE-like model, based on the physical properties of the device structure. The proposed model has been integrated in EDA software. It could be used for rapid and reliable design of system on chip, integrating the BQJ sensor, and its signal processing. The analytical expressions of the four BQJ photocurrents, as well as dark currents, have been developed. The spectral characteristics of the photodetector, computed with the proposed model, have been compared with those from TCAD simulations and experimental measurements. The analytical is close to the measurement with an average error on spectral responses in the range of 3-17 %, depending on the considered junction. | We prove that groups acting geometrically on delta-quasiconvex spaces contain no essential Baumslag-Solitar quotients as subgroups. This implies that they are translation discrete, meaning that the translation numbers of their nontorsion elements are bounded away from zero. | eng_Latn | 8,996 |
The optical properties of MoS2 monolayers are dominated by excitons, but for spectrally broad optical transitions in monolayers exfoliated directly onto SiO2 substrates detailed information on excited exciton states is inaccessible. Encapsulation in hexagonal boron nitride (hBN) allows approaching the homogenous exciton linewidth, but interferences in the van der Waals heterostructures make direct comparison between transitions in optical spectra with different oscillator strength more challenging. Here we reveal in reflectivity and in photoluminescence excitation spectroscopy the presence of excited states of the A exciton in MoS2 monolayers encapsulated in hBN layers of calibrated thickness, allowing us to extrapolate an exciton binding energy of ≈220 meV. We theoretically reproduce the energy separations and oscillator strengths measured in reflectivity by combining the exciton resonances calculated for a screened two-dimensional Coulomb potential with transfer matrix calculations of the reflectivity for the van der Waals structure. Our analysis shows a very different evolution of the exciton oscillator strength with principal quantum number for the screened Coulomb potential as compared to the ideal two-dimensional hydrogen model. | We measure the coherent nonlinear response of excitons in a single layer of molybdenum disulfide embedded in hexagonal boron nitride, forming a h-BN/MoS2/h-BN heterostructure. Using four-wave mixing microscopy and imaging, we correlate the exciton inhomogeneous broadening with the homogeneous one and population lifetime. We find that the exciton dynamics is governed by microscopic disorder on top of the ideal crystal properties. Analyzing the exciton ultrafast density dynamics using amplitude and phase of the response, we investigate the relaxation pathways of the resonantly driven exciton population. The surface protection via encapsulation provides stable monolayer samples with low disorder, avoiding surface contaminations and the resulting exciton broadening and modifications of the dynamics. We identify areas localized to a few microns where the optical response is totally dominated by homogeneous broadening. Across the sample of tens of micrometers, weak inhomogeneous broadening and strain effects ar... | Red wine polyphenolic compounds have been demonstrated to possess antioxidant properties, and several studies have suggested that they might constitute a relevant dietary factor in the protection from coronary heart disease. The aim of the present study is to examine whether red wine extracts (RWE) can ameliorate oxysterol-induced endothelial response, and whether inhibition of adhesion molecule expression is involved in monocyte adhesion to endothelial cells. Surface expression and mRNA levels of adhesion molecules (intercellular adhesion molecule 1 and vascular cell adhesion molecule 1) were determined by ELISA and RT-PCR performed on human aortic endothelial cells (HAEC) monolayers stimulated with 7beta-hydroxycholesterol or 25-hydroxycholesterol. Incubation of HAEC with oxysterols (10 microM) increased expression of adhesion molecules in a time-dependent manner. Pretreatment of HAEC with RWE at final concentrations of 1, 10, and 100 ng/ml significantly inhibited the increase of surface protein expression and mRNA levels. Adherence of monocytes to oxysterol-stimulated HAEC was increased compared to that of unstimulated cells. Treatment of HAEC with RWE significantly inhibited adherence of monocytes. These results suggest that RWE works as an anti-atherogenic agent through the inhibition of endothelial-dependent adhesive interactions with monocytes induced by oxysterols. | eng_Latn | 8,997 |
Application of polysilanes for a deep UV (DUV) bottom anti- reflective coating (BARC), in order to resolve the problem posed by the insufficient anti-reflection with thin conventional organic BARC applied on transparent dielectric film, is described. The newly developed polysilane anti- reflective coating has the real part of refractive index, n equals 2.00, and the imaginary part, k equals 0.23 at 248 nm. The polysilane coating is immiscible with a chemically amplified photoresist, and is not removable during normal wet development of photoresist. Etching rate of the polysilane is 2 times faster than that of DUV resist during BARC etching, and lower than that of DUV resist during dielectric film etching. The polysilane layer is easily removed by ashing using O2 gas process. Using thick polysilane coating, it can realize both the suppression of the interface reflection between the resist and BARC and good critical dimension control on dielectric film. | We have recently reported the formation of scum-free micron images in a bilayer composed of a thin (1500 angstrom) imaging layer of poly(cyclohexylmethylsilane) coated over a thick planarizing layer of a hardbaked diazoquinone-novalac type photoresist using deep UV exposure. Although excellent resolution was achieved (< 0.5 micrometers ) in this process, the exposure doses required (125-150 mJ/cm2) were higher than desirable for commercial DUV imaging tools. We have addressed this problem using two approaches: (i) the synthesis of new polysilanes which are intrinsically more sensitive to photodegradation in the solid state and (ii) the incorporation of additives which enhance the photosensitivity. Regarding the former, a number of aryl substituted polysilane homopolymers which are significantly more photolabile than the standard poly (methylphenylsilane), as assayed by the rate of spectral photobleaching upon exposure to DUV radiation, have been prepared and tested. In addition, a number of small molecule additives which quantitatively quench the polymer fluorescence in the solid state have been identified. Some of the additives which efficiently quench the polymer fluorescence in the solid state also accelerate the rate of photodegradation. The combination of the new polysilane materials with sensitizing additives has allowed submicron DUV imaging at exposure doses as low as 20 mJ/cm2 or less in a bilayer configuration employing O2-RIE for image transfer of the wet-developed images.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. | Arsenic compounds have been used extensively in agriculture in the US for applications ranging from cotton herbicides to animal feed supplements. Roxarsone (3-nitro-4-hydroxyphenylarsonic acid), in particular, is used widely in poultry production to control coccidial intestinal parasites. It is excreted unchanged in the manure and introduced into the environment when litter is applied to farmland as fertilizer. Although the toxicity of roxarsone is less than that of inorganic arsenic, roxarsone can degrade, biotically and abiotically, to produce more toxic inorganic forms of arsenic, such as arsenite and arsenate. Experiments were conducted on aqueous litter leachates to test the stability of roxarsone under different conditions. Laboratory experiments have shown that arsenite can be cleaved photolytically from the roxarsone moiety at pH 4-8 and that the degradation rate increases with increasing pH. Furthermore, the rate of photodegradation increases with nitrate and natural organic matter concentration, reactants that are commonly found in poultry-litter-water leachates. Additional photochemical reactions rapidly oxidize the cleaved arsenite to arsenate. The formation of arsenate is not entirely undesirable, because it is less mobile in soil systems and less toxic than arsenite. A possible mechanism for the degradation of roxarsone in poultry litter leachates is proposed. The results suggest that poultry litter storage and field application practices could affect the degradation of roxarsone and subsequent mobilization of inorganic arsenic species. | eng_Latn | 8,998 |
Spectrometrically or optically encoded microsphere based suspension array technology (SAT) is applicable to the high-throughput, simultaneous detection of multiple analytes within a small, single sample volume. Thanks to the rapid development of nanotechnology, tremendous progress has been made in the multiplexed detecting capability, sensitivity, and photostability of suspension arrays. In this review, we first focus on the current stock of nanoparticle-based barcodes as well as the manufacturing technologies required for their production. We then move on to discuss all existing barcode-based bioanalysis patterns, including the various labels used in suspension arrays, label-free platforms, signal amplification methods, and fluorescence resonance energy transfer (FRET)-based platforms. We then introduce automatic platforms for suspension arrays that use superparamagnetic nanoparticle-based microspheres. Finally, we summarize the current challenges and their proposed solutions, which are centered on improving encoding capacities, alternative probe possibilities, nonspecificity suppression, directional immobilization, and "point of care" platforms. Throughout this review, we aim to provide a comprehensive guide for the design of suspension arrays, with the goal of improving their performance in areas such as multiplexing capacity, throughput, sensitivity, and cost effectiveness. We hope that our summary on the state-of-the-art development of these arrays, our commentary on future challenges, and some proposed avenues for further advances will help drive the development of suspension array technology and its related fields. | An innovative signal amplification strategy assisted by RNase H is described here for the detection of DNA targets in a universal fashion. A tailor-made RNA molecular beacon (RMB) conjugated with a fluorescence resonance energy transfer (FRET) pair (fluorophore and quencher) was designed, characterized, and combined with the employment of RNase H. Its performance is compared to that of other nucleases including Exonuclease III and T7 exonuclease. Fluorometry, performed best at excitation/emission wavelengths of 490/520 nm, gives an amazingly low detection limit of 23 fM for target DNA. The method was verified by the determination of human hemochromatosis (HFE) gene. It is perceived that the method represents a versatile tool for the detection of a wide range of targets. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 8,999 |
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