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Oriented covalent immobilization of esterase BioH on hydrophilic-modified Fe3O4 nanoparticles. | Investigation of deactivation thermodynamics of lipase immobilized on polymeric carrier | Genomic evidence for the absence of a functional cholesteryl ester transfer protein gene in mice and rats. | eng_Latn | 17,500 |
Self-assembly and chemical modifications of bisphenol a on Cu(111): interplay between ordering and thermally activated stepwise deprotonation. | Chemical Transformations Drive Complex Self-Assembly of Uracil on Close-Packed Coinage Metal Surfaces | Adipose Lipolysis Unchanged by Preexercise Carbohydrate Regardless of Glycemic Index | eng_Latn | 17,501 |
Self-assembled monolayers of metalloporphyrin phosphonates on electrochemically modified HOPG | In Situ Investigations on the Facile Synthesis and Catalytic Performance of CeO 2 -Pt/Al 2 O 3 Catalyst | Membranous Hydrops in the Inner Ear of the Guinea Pig after Obliteration of the Endolymphatic Sac | eng_Latn | 17,502 |
Direct radiative recombination in the Se-terminated nanoscale Si porous structure | Silicon nanowires with mesopores: Fabrication and optical properties | Evidence against a role for platelet-derived molecules in liver regeneration after partial hepatectomy in humans | eng_Latn | 17,503 |
Janus Gold Nanoplatform for Synergetic Chemoradiotherapy and Computed Tomography Imaging of Hepatocellular Carcinoma | Emerging and Innovative Theranostic Approaches for Mesoporous Silica Nanoparticles in Hepatocellular Carcinoma: Current Status and Advances | Porin channels in intact cells of Escherichia coli are not affected by Donnan potentials across the outer membrane. | eng_Latn | 17,504 |
Binary Colloidal Crystal Films Grown by Vertical Evaporation of Silica Nanoparticle Suspensions | Crystallization kinetics of colloidal binary mixtures with depletion attraction. | Regulation of Crystalline Silica: Where Next? | eng_Latn | 17,505 |
Silver nanoparticles (Ag-NPs) have potential applications in life science, food chemistry, biomedicine, photocatalysis and cosmetics fields due to its unique optical, electrical and catalytic properties besides the strong antibacterial property. Apple pomace, a by-product of apple juice production, is ample and easily available. In the present study, this green raw material was used to biosynthesize Ag-NPs for the first time. The obtained silver nanoparticles were investigated by UV-vis, TEM, XRD, and FTIR, respectively. The results showed that the concentration of AgNO 3 and the volume ratio of AgNO 3 solution to apple pomace extract were the important factors affecting the synthesis of silver nanoparticles. When the concentration of AgNO 3 was 10 mmol/L, the volume ratio of AgNO 3 solution to the apple pomace extract of 4:1(ν/ν), Ag-NPs were quickly formed. They were stable with high degree of crystallinity. The particle sizes ranged between 10-20nm and the conversation of silver ions was up to 99%. The bacteriostatic circle tests revealed that the biosynthesized Ag-NPs had a strong antibacterial activity against gram positive bacteria and gram negative bacteria. FTIR analysis demonstrated that some bio-molecules with groups of -NH 2 , -COOH and -OH were distributed on the surface of the newly synthesized Ag-NPs. During the synthesis of silver nanoparticles, there were not any poisonous reducers and stabilizers introduced. | Foodborne diseases are one of the factors that endanger the health of consumers, especially in people at risk of exclusion and in developing countries. The continuing search for effective antimicrobials to be used in the food industry has resulted in the emergence of nanotechnology in this area. Silver nanoparticles (Ag-NPs) are the nanomaterial with the best antimicrobial activity and therefore, with great potential of application in food processing and packing. However, possible health effects must be properly addressed to ensure food safety. This review presents a detailed description on the main applications of Ag-NPs as antimicrobial agents for food control, as well as the current legislation concerning these materials. Current knowledge about the impact of the dietary exposure to Ag-NPs in human health with special emphasis on the changes that nanoparticles undergo after passing through the gastrointestinal tract and how they alter the oral and gut microbiota, is also summarized. It is concluded that given their potential and wide properties against foodborne pathogens, research in Ag-NPs is of great interest but is not exempt from difficulties that must be resolved in order to certify the safety of their use. | UNLABELLED ::: The development of a reliable green chemistry process for the biogenic synthesis of nanomaterials is an important aspect of current nanotechnology research. Silver nanoparticles (AgNPs) have been known for their inhibitory and bactericidal effect. Resistance to antimicrobial agents by pathogenic bacteria has emerged in recent years and is a major challenge for the health care industry. In the present investigation the use of the fungus Trichoderma viride for the extracellular biosynthesis of AgNPs from silver nitrate solution is reported. It was observed that the aqueous silver (Ag(+)) ions, when exposed to a filtrate of T. viride, were reduced in solution, thereby leading to formation of extremely stable AgNPs. These AgNPs were characterized by means of several techniques. The nanoparticles show maximum absorbance at 420 nm on ultraviolet-visible spectra. The presence of proteins was identified by Fourier transform-infrared spectroscopy. The reduction of Ag(+) ions to elemental silver was characterized by x-ray photoelectron spectrophotometry. Electrokinetic measurements (zeta potential) of AgNPs as a function of pH in 1 x 10(-3) mol dm(-3) aqueous solution were evaluated. The transmission electron micrograph revealed the formation of polydispersed nanoparticles of 5-40 nm, and the presence of elemental silver was confirmed by energy-dispersed spectroscopy analysis. The nanoparticles were also evaluated for their increased antimicrobial activities with various antibiotics against gram-positive and gram-negative bacteria. The antibacterial activities of ampicillin, kanamycin, erythromycin, and chloramphenicol were increased in the presence of AgNPs against test strains. The highest enhancing effect was observed for ampicillin against test strains. The result showed that the combination of antibiotics with AgNPs have better antimicrobial effects. A mechanism was also proposed to explain this phenomenon. ::: ::: ::: FROM THE CLINICAL EDITOR ::: Silver nanoparticles (Ag NP-s) represent an important nanomedicine-based advance in the fight against polyresistent bacteria. In this study, the fungus Trichoderma viride was utilized for extracellular biosynthesis of extremely stable Ag Nps. The antibacterial activities of kanamycin, erythromycin, chloramphenicol and especially of ampicillin were increased in the presence of Ag NPs against test strains. | eng_Latn | 17,506 |
An integrated immobilization to encapsulate the Pd/C-coated magnetic nanoparticles within the chiral Ru/diamine-functionalized silica shell for the construction of a bifunctional magnetic catalyst is developed. This catalyst realizes a synergistic Suzuki cross-coupling/asymmetric transfer hydrogenation and a successive reduction/asymmetric transfer hydrogenation for the preparation of chiral aromatic alcohols. | Achieving drug target accumulation in antitumor tissue, simultaneous diagnostic imaging, and optimal release behavior with treatment needs a best chemotherapy procedure involving receptive switch of drug delivery. Constructed on mesoporous silica nanoparticles, which are crossed with multiscale charming nanoparticles for magnetic resonance imaging (MRI)-aided and alternate magnetic field (AMF) response chemotherapy for breast cancer, we report in this work the assembly of a new theranostics drug conveyance process. Hydrothermal processes (gadolinium(III) oxide nanoparticles [Gd-NPs]) and heat decomposition process (radical size uFe-NPs) were used to prepare superparamagnetic Gd-NPs with multiscale sizes. Gadolinium(III) oxide nanoparticles act as an AMF-responsive heat mediator, while ultra-Fe nanoparticles (uFe-NPs) act as an MRI T2 contrast mediator. Nanoparticles of the mesoporous silica with radially oriented mesochannels were further grown in situ on the surfaces of the Gd-NPs, and the uFe-NPs anticancer drug doxorubicin can be easily incorporated in the mesochannels. To provide better targeting capabilities for the as-synthesized biotin-loaded nanohybrids, the particle surfaces are updated with biotin (Bt). This optimized drug conveyance method based on nanocomposites of SiO2 demonstrated great efficiency of medication charging and receptive properties of AMF stimulus release. However, tests of MRI in vitro showed an outstanding contrast effect in MRI with a high stimulation quality (299 mM−1 s−1). In contrast, the study of in vitro cytotoxicity assessment revealed that an MRI-directed stimulus-mediated theranostics tool can be used as a drug conveyance device to efficiently treat breast cancer. | 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 | 17,507 |
Immobilized Cu 2þ ions affinity cellophane- poly(glycidyl methacrylate) (PGMA)-grafted membranes have been prepared through three steps. The first step was introducing of epoxy groups to its chemical structure through grafting process with PGMA. Factors affecting the grafting process have been studied and grafting per- centage (GP) up to 233% has been obtained. The second step was converting the introduced epoxy groups to sul- fonic ones. It was found that maximum amount of sul- fonic groups (2.7 mmol/g) was obtained with minimum GP (46.08%). The third and last step was the immobiliza- tion of Cu 2þ ions into sulfonated grafted membranes obtained from the previous step. Maximum amount of immobilized Cu 2þ ions was found to be 60.9 ppm per gram of polymer. The verification of the grafting and sul- fonation steps has been performed through characteriza- tion of the obtained membranes using FTIR, TGA, and EDAX analysis. Finally, Cu 2þ -immobilized membranes have been evaluated in separation of b-galactosidase (b- Gal) enzyme from its mixture with bovine serum albumin (BSA) in different pH medium. Maximum protein adsorp- tion, for both proteins, has been obtained at pH range 4- 4.5; as 90 and 45% for b-Gal and BSA, respectively. The results showed high affinity toward b-Gal separation although BSA concentration (0.5%) is 20-folds of b-Gal (0.025%). V C 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 2647-2656, 2009 | In this article, we developed novel immobilized Cu2+-hydroxamic acid functionalized poly (methyl methacrylate) grafted cellophane membranes for affinity separation of His-Tag chitinase. First, we grafted the cellophane membranes with poly (methyl methacrylate) (PMMA) and then treated with hydroxylamine hydrochloride to induce hydroxamic acid ions exchange groups, and so we immobilized the copper ions on the hydroxamic acid functionalized PMMA grafted membranes. Fourier transforms infrared analysis and thermal gravimetric analysis provided pieces of evidence of the grafting and the functionalization processes. The membranes show a high affinity toward separating the chitinase enzyme from BSA mixtures. The Cu2+-hydroxamic acid functionalized poly (methyl methacrylate) grafted cellophane membranes show no leakage of Cu2+ ions in the eluting solution during the protein elution process while eluted 88% of the adsorbed chitinase and 80% of the adsorbed BSA. | 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 | 17,508 |
The merger of materials synthesis, organic synthesis, and supramolecular chemistry has lead to a plethora of hybrid organic–inorganic materials with control over the molecular organization, nanoscale periodicity, and macroscopic morphology. Self-assembly of polymeric precursors can be directed by micelle templates, or through microphase separation of block copolymers. This has provided a pathway to new materials whose hierarchical structure determines material properties and function. Periodic mesoporous organosilicas (PMOs), which are composed of bridge-bonded silsesquioxanes organized into a mesoporous architecture, have emerged as promising materials for nanotechnology applications. This article provides an overview of PMOs and describes the challenges, problems and our predictions for the future of these intriguing solid-state materials. | The objective of this work was to synthesize functionalized mesoporous silsesquioxanes with high concentrations of amine groups. During typical sol–gel syntheses, these materials are obtained by co-condensation of organic precursors with suitable linkers, such as tetraethoxysilane, necessary to prevent the mesoporous structure from collapsing. Thus, concentrations of amine groups in organosilicas usually do not exceed 2.7–3.4 mmol g−1. The use of bridged bis-trimethoxysilanes, however, allowed formation of mesoporous materials with no linker. Polycondensation of bis-trimethoxysilanes containing amine groups was conducted in acidic, neutral and basic media, resulting in high yields of solid bridged silsesquioxanes. Gelation occurred quickly if no acid or base was added to the reaction mixture. The hybrid organic/inorganic nature of obtained materials was confirmed by FT-IR and MAS CP NMR spectroscopy. Elemental analysis showed that amino group concentration in the products was 3.3–4.1 mmol g−1. Measurement of particle size distribution confirmed that choice of reaction media significantly affects particle sizes and agglomeration degrees, with the largest agglomerates (up to 50 μm) formed in basic media. A morphology study, using small-angle X-Ray scattering, displayed two-level fractal structures composed of aggregated 6.5–10.5 nm particles. Reactions in the presence of a surfactant resulted in formation of mesoporous structures. Furthermore, the obtained bridged silsesquioxanes were thermally stable down to 260 °C, but could reversibly absorb water and CO2 at temperatures below 120 °C. Thus, condensation of the bridged precursor without a linker resulted in formation of a highly functionalized mesoporous material. | 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 | 17,509 |
Delivering therapeutics to mucosal tissues such as the nasal and gastrointestinal tracts is highly desirable due to ease of access and dense vasculature. However, the mucus layer effectively captures and removes most therapeutic macromolecules and devices. In previous work, we have shown that nanoengineered microparticles (NEMPs) adhere through the mucus layer, exhibiting up to 1000 times the pull-off force of an unmodified microsphere, and showing greater adhesion than some chemical targeting means. In this paper, we demonstrate that nanotopography improves device adhesion in vivo , increasing retention time up to ten-fold over unmodified devices. Moreover, we observe considerable adhesion in several cell lines using an in vitro shear flow model, indicating that this approach is promising for numerous tissues. We then demonstrate that nanowire-mediated adhesion is highly robust to variation in nanowire surface charge and cellular structure and function, and we characterize particle loading and elution. We present a form of cytoadhesion that utilizes the physical interaction of nanoengineered surfaces with subcellular structures to produce a robust and versatile cytoadhesive for drug delivery. These nanoscale adhesive mechanisms are also relevant to fields such as tissue engineering and wound healing because they likely affect stem cell differentiation, cell remodeling, migration, etc. | Understanding of the complicated interactions between biomaterials and cells can accelerate biomedical developments. Recently, many in vitro studies have emphasized the biological features of nanowires (NWs) on the cell’s early response. A type of unique clustered anatase/rutile NWs (ARNWs) was generated using a simple hydrothermal reaction on titanium in the present study. The aim of this study is to determine whether the ARNWs is beneficial for the enhancement of biological capacity. Clustered ARNWs with a diameter of 200 nm were grown on titanium disks via a three-step synthesis process. Three different types of NWs were generated during the production process, displaying different biological characteristics but similar surface topography and wettability. All of the NW surfaces remarkably accelerated the adsorption of albumin protein; however, compared to the ARNWs, a relatively low level of cell attachment and proliferation occurred on the surfaces of sodium titanate NWs (STiNWs) and H2Ti2O5 nanowires (HTiNWs). The data indicated that the surface titanium oxide crystal structure plays an important role in the cell’s early response. To some extent, the generation of anatase and rutile of the ARNWs compensated for the cell-repelling properties. The crystal structure and potential larger loading capacity of the ARNWs face challenges for enhanced cellular adaptation which could improve its clinical potential. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 17,510 |
Nanomedicines, since the approval of the first one in the 1950s, have been accompanied by expectations of higher efficiency and efficacy, compared to less complex drugs. The fulfilment of those expectations has been slower than anticipated, due to the high complexity of nanomedicine drugs combined with a lack of scientific understanding of nanomedicine interactions with biological systems. The unique properties of their size and their surface composition create difficulties in their physicochemical characterization, and as a consequence, difficulty in assessing the similarity of follow-on products (nanosimilars) to originator nanomedicines. During the 2018 European Federation for Pharmaceutical Sciences (EUFEPS) annual meeting “Crossing the barrier for future medicines” in Athens, there were several sessions on nanomedicines organised by the EUFEPS Nanomedicine Network. This review focuses on the session “Nanomedicines and nanosimilars: how to assess similar?”, discussing the nature of nanomedicines, the regulatory aspects of the topic and the impact of practical use and handling of such medicinal products. Emphasis is put on the consequences their nanosize-related properties have on the establishment of their critical quality attributes and how this affects the demonstration of bioequivalence of nanosimilars to their originator products. The lack of an appropriate and harmonized regulatory evaluation procedure and the absence of corresponding education are also discussed, especially the uncertainty surrounding the practical use of nanosimilars, including the higher healthcare cost due to less than satisfactory number of safe and efficacious nanosimilars in the market. | In this review we provide an up to date snapshot of nanomedicines either currently approved by the US FDA, or in the FDA clinical trials process. We define nanomedicines as therapeutic or imaging agents which comprise a nanoparticle in order to control the biodistribution, enhance the efficacy, or otherwise reduce toxicity of a drug or biologic. We identified 51 FDA-approved nanomedicines that met this definition and 77 products in clinical trials, with ~40% of trials listed in clinicaltrials.gov started in 2014 or 2015. While FDA approved materials are heavily weighted to polymeric, liposomal, and nanocrystal formulations, there is a trend towards the development of more complex materials comprising micelles, protein-based NPs, and also the emergence of a variety of inorganic and metallic particles in clinical trials. We then provide an overview of the different material categories represented in our search, highlighting nanomedicines that have either been recently approved, or are already in clinical trials. We conclude with some comments on future perspectives for nanomedicines, which we expect to include more actively-targeted materials, multi-functional materials (“theranostics”) and more complicated materials that blur the boundaries of traditional material categories. A key challenge for researchers, industry, and regulators is how to classify new materials and what additional testing (e.g. safety and toxicity) is required before products become available. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 17,511 |
Alcoholic extract of tulsi leaves was used as a reducing and stabilizing agent for the synthesis of silver nanoparticles (AgNPs). The use of plant extract for the synthesis of nanoparticles is cost-effective, single step, and an ecofriendly process. The biosynthesized AgNPs were characterized using UV-Vis, transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) analysis. The AgNPs formed show surface plasmon resonance at 430 nm. They have a smooth surface with an average diameter of 2–7 nm. Their crystalline nature was confirmed by the XRD. The antifungal activity of the AgNPs was evaluated for opportunistic human fungal pathogens Candida albicans, Candida glabrata, and Candida tropicalis. The antifungal effect was determined by minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), and disk diffusion assay. Further, to assess the pathogenicity, proteinase and phospholipase assays were performed. TEM analysis of treated Candida cells reveals that the AgNPs may be exerting antifungal activity by disrupting the cell membrane structure and integrity. Cytotoxicity of AgNPs was checked by performing hemolytic assay against human erythrocytes. At MIC values, AgNPs caused only 5.6 % lysis in RBCs which was very low in comparison to conventional antifungal agents. Hence, biosynthesized AgNPs using plant extracts have immense antifungal potential and can be used in the management of fungal infections. Further studies have to be done to understand their mode of action. | Silver nanomaterials have been integrated into industrial, biomedical and agricultural application, including biosensor, anti-microbial, anti-tumor, drug delivery, waste treatment, coated fabrics and nano fertilizer. Nanoparticle possesses unusual character due to their large surface area to volume ratio and an extraordinary catalytic activity, electronic properties, optical properties and anti-microbial activity while they are constructed in atomic level. The unique and major task in the synthesis of nanoparticle is choosing of an advanced and ecofriendly method. Nevertheless, physical and chemical methods of synthesis of nanoparticles are too expensive and environmentally unsound. In this study, the green synthesis of nanoparticle’s production methods was evaluated on the basis of variable literatures. Currently, there is a better possibility of using green synthesis of silver nanoparticles, especially a plant, bacterial and fungal production of nanoparticles which is emerging as a novel ecofriendly technique. The growth rate of bacterial culture, the extract of plant secondary metabolite and mycelial surface area of fungus are the main comprehensible mechanism in green synthesis of silver nanoparticles. The silver nanoparticles, which are produced through green biosynthesis is safe and hold a better possibility to be administered for medical and agricultural usages. Over all we found that the fungal green biosynthesis of silver nanoparticles is considered more preferable and is excellently chosen in it in industrial level production. | 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 | 17,512 |
Powders consisting of Si-based nanostructures were synthesized by the extraction of Ca atoms from CaSi2 powders using an inositol hexakisphosphate (IP6) aqueous solution. The raw CaSi2 powders were simply immersed in a diluted IP6 solution, then dried. It is noted that the Si-based nanostructures were easily exfoliated from the powders to expose the surfaces corresponding to the Si {111} planes of the nanostructures. In addition, the Si-based nanostructures were also synthesized by metal atom extraction from SrSi2, BaSi2 and Mg2Si using the IP6 aqueous solution. It was found that the nanostructures mainly including the amorphous Si-oxide phase were obtained for the IP6-treated SrSi2, BaSi2 and Mg2Si powders. Moreover, the amorphous Si oxide-based nanostructures were synthesized from CaSi2 using citric acid, malic acid, FeCl3 and FeCl2 aqueous solutions. It was demonstrated that the morphological and structural properties of the synthesized Si-based nanostructures depend on the silicide templates and the solutions. | We have investigated the fundamental mechanism underlying the hydrogen-induced exfoliation of silicon, using a combination of spectroscopic and microscopic techniques. We have studied the evolution of the internal defect structure as a function of implanted hydrogen concentration and annealing temperature and found that the mechanism consists of a number of essential components in which hydrogen plays a key role. Specifically, we show that the chemical action of hydrogen leads to the formation of (100) and (111) internal surfaces above 400 °C via agglomeration of the initial defect structure. In addition, molecular hydrogen is evolved between 200 and 400 °C and subsequently traps in the microvoids bounded by the internal surfaces, resulting in the build-up of internal pressure. This, in turn, leads to the observed “blistering” of unconstrained silicon samples, or complete layer transfer for silicon wafers joined to a supporting (handle) wafer which acts as a mechanical “stiffener.” | 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 | 17,513 |
Recent developments in bio-fuel cell technology are reviewed. A general introduction to bio-fuel cells, including their operating principles and applications, is provided. New materials and methods for the immobilisation of enzymes and mediators on electrodes, including the use of nanostructured electrodes are considered. Fuel, mediator and enzyme materials (anode and cathode), as well as cell configurations are discussed. A detailed summary of recently developed enzymatic fuel cell systems, including performance measurements, is conveniently provided in tabular form. The current scientific and engineering challenges involved in developing practical bio-fuel cell systems are described, with particular emphasis on a fundamental understanding of the reaction environment, the performance and stability requirements, modularity and scalability. In a companion review (Part II), new developments in microbial fuel cell technologies are reviewed in the context of fuel sources, electron transfer mechanisms, anode materials and enhanced O(2) reduction. | The field of nanobiocatalysis has experienced a rapid growth due to recent advances in nanotechnology. However, biocatalytic processes are often limited by the lack of stability of the enzymes and their short lifetime. Therefore, immobilization is key to the successful implementation of industrial processes based on enzymes. Immobilization of enzymes on functionalized nanostructured materials could give higher stability to nanobiocatalysts while maintaining free enzyme activity and easy recyclability under various conditions. This review will discuss recent developments in nanobiocatalysis to improve the stability of the enzyme using various nanostructured materials such as mesoporous materials, nanofibers, nanoparticles, nanotubes, and individual nanoparticles enzymes. Also, this review summarizes the recent evolution of nanostructured biocatalysts with an emphasis on those formed with polymers. Based on the synthetic procedures used, established methods fall into two important categories: “grafting onto” and “grafting from”. The fundamentals of each method in enhancing enzyme stability and the use of these new nanobiocatalysts as tools for different applications in different areas are discussed. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 17,514 |
PURPOSE ::: This study was carried out to formulate poly(lactide-co-glycolide) (PLGA) nanoparticles using a quaternary ammonium salt didodecyl dimethylammonium bromide (DMAB) and checking their utility to deliver paclitaxel by oral route. ::: ::: ::: METHODS ::: Particles were prepared by emulsion solvent diffusion evaporation method. DMAB and particles stabilized with it were evaluated by MTT and LDH cytotoxicity assays. Paclitaxel was encapsulated in these nanoparticles and evaluated in a chemical carcinogenesis model in Sprague Dawley rats. ::: ::: ::: RESULTS ::: MTT and LDH assays showed the surfactant to be safe to in vitro cell cultures at concentrations <33 microM. PLGA nanoparticles prepared using this stabilizer were also found to be non-toxic to cell lines for the duration of the study. When administered orally to rats bearing chemically induced breast cancer, nanoparticles were equally effective/better than intravenous paclitaxel in cremophor EL at 50% lower dose. ::: ::: ::: CONCLUSIONS ::: This study proves the safety and utility of DMAB in stabilizing preformed polymers like PLGA resulting in nanoparticles. This preliminary data provides a proof of concept of enabling oral chemotherapy by efficacy enhancement for paclitaxel. | The stabilizer, which is used during the preparation of Poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs), is of great importance for particle properties. It could be shown that the stabilizer affects the PLGA NPs stability in time and in dependence of temperature, which are important parameters for their practical use. Complex nanoparticles were prepared, for which we have used tetrandrine, azithromycin, and tobramycin that were incorporated into nanoparticles of different origin—PLGA nanoparticles and DPPC/DPPA liposomes. The sizes and surface potentials of complex nanoparticles have been determined. The diameters of the obtained nanoparticles were 150–200 nm, and they had surface potentials with different charge and value (for PLGA with PL 10RS and PLGA with PL 35 are − 32.8 and − 22.5 mV, respectively, and for PLGA with DMAB + 15.0 mV). From calorimetric and spectrophotometric studies, the structural stability of complex nanoparticles with drug has been determined. The dependence on temperature and time could be shown. Structural changes of the particles in the temperature interval of 25–40 °C could be observed. It turned out that these transformations for the complex liposomes prepared with DPPC are completely reversible, and for other nanoparticles, these changes are irreversible, which means, that after phase transition, the nanoparticles internal structure restores in a different ways. Furthermore, a method, which allowed to observe the release of drugs from nanoparticles (as for PLGA, also for liposomal nanoparticles) initiated by temperature, was used. The work makes use of a new and fast technology that can be used to produce complex, drug containing liposomes in a one-step procedure. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 17,515 |
Biological membranes are ideal for separations as they provide high permeability while maintaining high solute selectivity due to the presence of specialized membrane protein (MP) channels. However, successful integration of MPs into manufactured membranes has remained a significant challenge. Here, we demonstrate a two-hour organic solvent method to develop 2D crystals and nanosheets of highly packed pore-forming MPs in block copolymers (BCPs). We then integrate these hybrid materials into scalable MP-BCP biomimetic membranes. These MP-BCP nanosheet membranes maintain the molecular selectivity of the three types of β-barrel MP channels used, with pore sizes of 0.8 nm, 1.3 nm, and 1.5 nm. These biomimetic membranes demonstrate water permeability that is 20–1,000 times greater than that of commercial membranes and 1.5–45 times greater than that of the latest research membranes with comparable molecular exclusion ratings. This approach could provide high performance alternatives in the challenging sub-nanometre to few-nanometre size range. Protein channels are highly selective, but application in membranes is limited due to low protein content. Here, protein channels are embedded into block copolymers to form nanosheets using rapid solvent casting, with better water permeability and similar molecular exclusions relative to other membrane systems. | Exponential interest in the field of covalent organic frameworks (COFs) stems from the direct correlation between their modular design principle and various interesting properties. However, existing synthetic approaches to realize this goal mainly result in insoluble and unprocessable powders, which severely restrict their widespread applicability. Therefore, developing a methodology for easy fabrication of these materials remains an alluring goal and a much desired objective. Herein, we have demonstrated a bottom-up interfacial crystallization strategy to fabricate these microcrystalline powders as large-scale thin films under ambient conditions. This unique design principle exploits liquid–liquid interface as a platform, allowing simultaneous control over crystallization and morphology of the framework structure. The thin films are grown without any support in free-standing form and can be transferred onto any desirable substrate. The porous (with Tp-Bpy showing highest SBET of 1 151 m2 g–1) and crystal... | 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 | 17,516 |
We studied the self-assembly of inorganic nanocrystals (NCs) confined inside nanoliter droplets (plugs) into long-range ordered superlattices. We showed that a capillary microfluidic platform can be used for the optimization of growth conditions for NC superlattices and can provide insights into the kinetics of the NC assembly process. The utility of our approach was demonstrated by growing large (up to 200 μm) three-dimensional (3D) superlattices of various NCs, including Au, PbS, CdSe, and CoFe(2)O(4). We also showed that it is possible to grow 3D binary nanoparticle superlattices in the microfluidic plugs. | Poly(dimethylsiloxane) (PDMS), a transparent elastomeric polymer, has been widely used in the microfluidic field. However, applications of microfluidic device fabricated in PDMS have been limited to a bioanalysis based on water rather than nonpolar solvents because PDMS swells by absorbing the solvents. In case of inorganic nanocrystals growth into a superlattice structure, a PDMS microfluidic device can be used as long as a solvent-resistant capillary is inserted and assembled with the PDMS device for the growth of nanocrystals localized in nanoliter droplets. To solve the PDMS swelling problem and additional assembly process, we propose that a parylene film coated inside PDMS channel can serve as an effective barrier to the chemical solvents and prevent swelling. We found that a parylene coated PDMS microfluidic channel has a potential for the droplet based nanocrystals growth. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 17,517 |
Stability of Water-in-oil Emulsion and its Liquid Membrane | Separation of Eu(III) with supported dispersion liquid membrane system containing D2EHPA as carrier and HNO3 solution as stripping solution | Correction: Applying thermo-destabilization of microemulsions as a new method for co-catalyst loading on mesoporous polymeric carbon nitride – towards large scale applications | eng_Latn | 17,518 |
Lipid and Lipoprotein Contents of Human Follicular Fluid | The Bile Acid Synthesis Pathway Is Present and Functional in the Human Ovary | Liposomal flucytosine capped with gold nanoparticle formulations for improved ocular delivery | eng_Latn | 17,519 |
Liposomes targeted by fusion phage proteins. | Optimizing Druggability through Liposomal Formulations: New Approaches to an Old Concept | High-affinity glucose uptake in Saccharomyces cerevisiae is not dependent on the presence of glucose-phosphorylating enzymes | eng_Latn | 17,520 |
Effect of hydration on the structure of solid-supported Niosomal membranes investigated by in situ energy dispersive X-ray diffraction | Ciprofloxacin nano-niosomes for targeting intracellular infections: an in vitro evaluation | Nitrogen deposition does not alleviate the adverse effects of shade on Camellia japonica (Naidong) seedlings | eng_Latn | 17,521 |
Cell-seeded 3D scaffolds as in vitro models for electroporation. | The Potential Use of Electrochemotherapy in the Treatment of Uveal Melanoma: In Vitro Results in 3D Tumor Cultures and In Vivo Results in a Chick Embryo Model | Oral insulin does not alter gut microbiota composition of NOD mice | eng_Latn | 17,522 |
Catalyst design for biorefining | Optimal bimodal pore networks for heterogeneous catalysis | Evidence against a role for platelet-derived molecules in liver regeneration after partial hepatectomy in humans | eng_Latn | 17,523 |
Phase transitions in elpasolites (ordered perovskites) | Structural, thermal and optical properties of elpasolite-like (NH4)2KZrF7 | High-affinity glucose uptake in Saccharomyces cerevisiae is not dependent on the presence of glucose-phosphorylating enzymes | eng_Latn | 17,524 |
Analysis of adsorption and binding behaviors of silver nanoparticles onto a pyridyl-terminated surface using XPS and AFM. | Impact of Charge Variation on the Encapsulation of Nanoparticles by Virus Coat Proteins | High-affinity glucose uptake in Saccharomyces cerevisiae is not dependent on the presence of glucose-phosphorylating enzymes | eng_Latn | 17,525 |
Rapid synthesis of multi-chip systems | A global criticality/local phase driven algorithm for the constrained hardware/software partitioning problem | Stimulation of jejunal synthesis of apolipoprotein A-IV by ileal lipid infusion is blocked by vagotomy. | eng_Latn | 17,526 |
Patterns of Innovation and Retention in Templatic Polysynthesis | Rethinking agreement: Cognition-to-form mapping | Synthesis of Microcapsule by Staphylococcus aureus Is Not Responsive to Environmental Phosphate Concentrations | eng_Latn | 17,527 |
Templated synthesis of atomically-thin Ag nanocrystal catalysts in the interstitial space of a layered silicate. | Recent advances in the application of silica nanostructures for highly improved water treatment: a review | Completely Stale Transmitter Channel State Information is Still Very Useful | eng_Latn | 17,528 |
Gold nanoparticle SERS substrates sustainable at extremely high temperatures | Simple size-controlled synthesis of Au nanoparticles and their size-dependent catalytic activity | Inability of the Submaximal Treadmill Stress Test to Predict the Location of Coronary Disease | eng_Latn | 17,529 |
S 1 Supporting Information to : Single-Molecule Electrocatalysis by Single-Walled Carbon Nanotubes | Precise nanometer localization analysis for individual fluorescent probes | 25 Years of Small Molecular Weight Kinase Inhibitors: Potentials and Limitations | eng_Latn | 17,530 |
Associative Polymer Facilitated Electrospinning of Nanofibers | Electrospinning of commercial guar-gum: Effects of purification and filtration. | High-affinity glucose uptake in Saccharomyces cerevisiae is not dependent on the presence of glucose-phosphorylating enzymes | eng_Latn | 17,531 |
Pressure-driven one-step solid phase-based on-chip sample preparation on a microfabricated plastic device and integration with flow-through polymerase chain reaction (PCR). | A review on microscale polymerase chain reaction based methods in molecular diagnosis, and future prospects for the fabrication of fully integrated portable biomedical devices | No evidence for Z-chromosome rearrangements between the pied flycatcher and the collared flycatcher as judged by gene-based comparative genetic maps. | eng_Latn | 17,532 |
The next generation of mammalian cell factories for biopharmaceutical production will be genetically engineered to possess both generic and product-specific manufacturing capabilities that may not exist naturally. Introduction of entirely new combinations of synthetic functions (e.g. novel metabolic or stress-response pathways), and retro-engineering of existing functional cell modules will drive disruptive change in cellular manufacturing performance. However, before we can apply the core concepts underpinning synthetic biology (design, build, test) to CHO cell engineering we must first develop practical and robust enabling technologies. Fundamentally, we will require the ability to precisely control the relative stoichiometry of numerous functional components we simultaneously introduce into the host cell factory. In this review we discuss how this can be achieved by design of engineered promoters that enable concerted control of recombinant gene transcription. We describe the specific mechanisms of transcriptional regulation that affect promoter function during bioproduction processes, and detail the highly-specific promoter design criteria that are required in the context of CHO cell engineering. The relative applicability of diverse promoter development strategies are discussed, including re-engineering of natural sequences, design of synthetic transcription factor-based systems, and construction of synthetic promoters. This review highlights the potential of promoter engineering to achieve precision transcriptional control for CHO cell synthetic biology. | Biotin is an essential micronutrient that acts as a co-factor for biotin-dependent metabolic enzymes. In bacteria, the supply of biotin can be achieved by de novo synthesis or import from exogenous sources. Certain bacteria are able to obtain biotin through both mechanisms while others can only fulfill their biotin requirement through de novo synthesis. Inability to fulfill their cellular demand for biotin can have detrimental consequences on cell viability and virulence. Therefore understanding the transcriptional mechanisms that regulate biotin biosynthesis and transport will extend our knowledge about bacterial survival and metabolic adaptation during pathogenesis when the supply of biotin is limited. The most extensively characterized protein that regulates biotin synthesis and uptake is BirA. In certain bacteria, such as Escherichia coli and Staphylococcus aureus, BirA is a bi-functional protein that serves as a transcriptional repressor to regulate biotin biosynthesis genes, as well as acting as a ligase to catalyze the biotinylation of biotin-dependent enzymes. Recent studies have identified two other proteins that also regulate biotin synthesis and transport, namely BioQ and BioR. This review summarizes the different transcriptional repressors and their mechanism of action. Moreover, the ability to regulate the expression of target genes through the activity of a vitamin, such as biotin, may have biotechnological applications in synthetic biology. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 17,533 |
Amine monofunctional gold nanoparticles (1-AuNPs) were synthesized by employing a solid-supported technique and pH-switchable pseudorotaxane formation. Purification was repeatedly facilitated using crown ether peripherally coated superparamagnetic iron oxide microspheres to yield the monofunctional gold nanoparticles in excellent yield. The product and its related intermediate superstructures were characterized by IR and X-ray photoelectron spectroscopies. Novel supramolecular dimers and trimers were prepared by titrating the 1-AuNPs with bisDB24C8 and trisDB24C8 at different ratios. UV/visible absorption spectroscopic analyses of the supramolecular dimer and trimer solutions, which were formed by mixing their separate components in different ratios, indicated the gradual appearance of two distinct plasmonic resonance bands at 620 and approximately 700 nm. Furthermore, TEM images of the dimers revealed a significant amount of dimer pairs on the surface, while the TEM images of the trimers demonstrated the presence of both dimers and trimers. The trimers appeared as triangular or near-linear shapes. | Hybrid nanoparticles of gold and silver can not only retain the beneficial features of both nanomaterials, but also possess unique advantages (synergism) over the other two types. Novel pseudospherical and anisotropic nanoparticles, bimetallic triangular nanoparticles, and core@shell nanoparticles were prepared by the different procedures for various applications and understanding both the particle evolution (nucleation) and nanoparticle anisotropy. Hybrid nanoparticles of gold and silver are considered to be low in toxicity, and exhibit facile surface functionalization chemistry. Furthermore, their absorption peaks are located in visible and near-infrared region. These nanoparticles provide significant plasmon tunability, chemical and surface modification properties, and significant advances in the growth into anisotropic nanostructures. The photoinduced synthesis can be used to prepare various (sub) nanoparticles and OD and 1D nanoparticles. Ostwald and digestive ripening provided narrower particle size distribution. | 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 | 17,534 |
The synthesis and characterization of polymer-stabilized silver nanoparticles (Ag NPs) for water-based silver inks are studied. In order to synthesize Ag NPs with spherical shape, the conventional polyol processes require an excess of poly(vinyl pyrrolidone) (PVP) (10 ~ 1000 times than AgNO3) and therefore result in low productivity per reactor volume. In this study, poly(acrylic acid) (PAA) with carboxylic acid group was used instead of PVP. Even at less molar ratio of PAA to AgNO3 (< 2), the spherical Ag NPs with average size of 30 nm were successfully synthesized at 100 gram-scale with high reaction yield of 90%. Furthermore, the Ag NPs were dispersed into alcohol-based solvent and then patterned into metallic lines through inkjet printing technology. | Silver (Ag) and copper (Cu) nanoparticles have shown great potential in variety applications due to their excellent electrical and thermal properties resulting high demand in the market. Decreasing in size to nanometer scale has shown distinct improvement in these inherent properties due to larger surface-to-volume ratio. Ag and Cu nanoparticles are also shown higher surface reactivity, and therefore being used to improve interfacial and catalytic process. Their melting points have also dramatically decreased compared with bulk and thus can be processed at relatively low temperature. Besides, regularly alloying Ag into Cu to create Ag–Cu alloy nanoparticles could be used to improve fast oxidizing property of Cu nanoparticles. There are varieties methods have been reported on the synthesis of Ag, Cu, and Ag–Cu alloy nanoparticles. This review aims to cover chemical reduction means for synthesis of those nanoparticles. Advances of this technique utilizing different reagents namely metal salt precursors, reducing agents, and stabilizers, as well as their effects on respective nanoparticles have been systematically reviewed. Other parameters such as pH and temperature that have been considered as an important factor influencing the quality of those nanoparticles have also been reviewed thoroughly. | Synthesis of metallic nanoparticles by chemical and physical method makes the process often cumbersome due the usage of toxic and expensive chemicals. The present study reports the biosynthesis of silver nanoparticles using marine invertebrate (polychaete) extract at room temperature. The ultraviolet-visible (UV-Vis) spectroscopy revealed the formation of silver nanoparticles (AgNPs) by exhibiting the typical surface plasmon absorption maximum at 418–420 nm. Structure and composition of AgNPs were analyzed by atomic force microscopy (AFM). Average particle size of AgNPs ranged from 40 to 90 nm, confirmed by scanning electron microscopy (SEM) analysis. The energy-dispersive X-ray spectroscopy (EDX) of the nanoparticles dispersion confirmed the presence of elemental silver signal, whereas X-ray diffraction (XRD) substantiated the crystalline nature of synthesized nanoparticle. Fourier transform infrared spectroscopy (FTIR) spectral analysis showed the presence of amides phenols, ethers, and fatty acids as major biomolecules responsible for the reduction of silver ions. The possible mechanism responsible for the synthesis of AgNPs by these biomolecules was also illustrated by chemical reactions. The synthesized AgNPs showed comparatively good antibacterial activity against the tested human pathogens. This study advocates that not only plants and microbes but also marine invertebrates do have potential for synthesizing nanoparticles by a cost-effective and eco-friendly approach. | eng_Latn | 17,535 |
Nanoporous Pt−Co alloy nanowires were synthesized by electrodeposition of Co-rich Pt1Co99 alloy into anodic aluminum oxide (AAO) membranes, followed by a dealloying treatment in a mild acidic medium. These nanowires consist of porous skeletons with tiny pores of 1−5 nm and crystalline ligaments of 2−8 nm. Morphological and compositional evolutions of the porous Pt−Co nanowires upon dealloying were investigated, and their formation mechanism is discussed. The nanoporous Pt−Co alloy nanowires are found to exhibit distinctly enhanced electrocatalytic activities toward methanol oxidation as compared to the current state-of-the-art Pt/C and PtCo/C catalysts, thus showing substantial promise as efficient anode electrocatalysts in direct methanol fuel cells. | We have established a facile and generalizable electrochemical synthesis of metallic mesoporous nanorods in the nanochannels of commercial polycarbonate membranes using microemulsions containing ionic liquids. Herein, we report the preparation of magnetic CoPt nanorods with various meso or nanopores distributions, depending on the microemulsion type (ionic liquid –in-water (IL/W), bicontinuous (β) or water-in-ionic liquid (W/IL)). The synthesized porous nanorods show a much enhanced electrocatalytic activity for methanol oxidation in comparison with compact Pt nanorods (up to 12 times) or Pt/C electrocatalyst (Pt nanoparticles or commercial black platinum). Therefore, the synthesized CoPt mesoporous nanorods could be excellent catalysts in direct methanol fuel cells (DMFC's), as they have high surface areas, large pore volumes and high corrosion stability, and they exhibit promising catalytic properties. | In this study we investigate for the first time the biomedical potential of using a membrane made from anodic aluminium oxide (AAO) for culturing the Madin-Darby Canine Kidney (MDCK) epithelial cell line. Nano-porous aluminium oxide membranes exhibit interesting properties such as high porosity, which allows the exchange of molecules and nutrients across the membrane and can be made with highly specific pore sizes that can be preselected by adjusting the controlling parameters of a temperature controlled two-step anodization process. The cellular response and interactions of the MDCK cell line with the synthesised nano-porous AAO membrane, a commercially available membrane and a glass control were assessed by investigating cell adhesion, morphology and proliferation. | eng_Latn | 17,536 |
Plasmon resonances in graphene ribbon arrays are investigated numerically by means of the Finite Element Method. Numerical analysis shows that a series of multipolar resonances take place when graphene ribbon arrays are illuminated by a TM polarized electromagnetic wave. Moreover, these resonances are angle-independent, and can be tuned greatly by the width and the doping level of the graphene ribbons. Specifically, we demonstrate that for graphene arrays with several sets of graphene ribbons, which have different widths or doping levels, each of these multipolar resonances will be split into several ones. In addition, as plasmon resonances can confine electromagnetic field at the ribbon edges, graphene ribbons with different widths or doping levels offer intriguing application for electrically tunable spectral imaging. | ABSTRACTIntroduction Physiological processes at the molecular level take place at precise spatiotemporal scales, which vary from tissue to tissue and from one patient to another, implying the need for carriers that enable tunable release of therapeutics.Areas covered Classification of all drug release to intrinsic and extrinsic is proposed, followed by the etymological clarification of the term ‘tunable’ and its distinction from the term ‘tailorable’. Tunability is defined as analogous to tuning a guitar string or a radio receiver to the right frequency using a single knob. It implies changing a structural parameter along a continuous quantitative scale and correlating it numerically with the release kinetics. Examples of tunable, tailorable and environmentally responsive carriers are given, along with the parameters used to achieve these levels of control.Expert opinion Interdependence of multiple variables defining the carrier microstructure obstructs the attempts to elucidate parameters that allow for ... | Background ::: Monoacetylated xylosyl residues of the main hardwood hemicellulose acetylglucuronoxylan undergo acetyl group migration between positions 2 and 3, and predominantly to position 4 of the non-reducing end xylopyranosyl (NRE-Xylp) residues which are amplified by saccharifying enzymes. On monoacetylated non-reducing end xylopyranosyl (NRE-Xylp) residues of xylooligosaccharides the acetyl group migrates predominantly to position 4 and hinders their hydrolysis by β-xylosidase. | eng_Latn | 17,537 |
Two types of bead-form macroporous carriers based on glycidyl methacrylate with ethylene dimethacrylate copolymers were used for the immobilization of penicillin amidase either directly or after chemical modificaton. Direct binding through oxirane groups, which is equally efficient at pH 4.2 and 7, is relatively slow and brings about an activity loss at low enzyme concentrations. The most efficient immobilization was achieved on glutaraldehyde-activated amino carier, irrespective of whether the amino groups were formed by ammonia or 1,6-diaminohexane treatment of the original oxirane carrier. Hydrazine treatment gave lower immobilization yields. The same is true of the azide method independent of the length of the spacer. Most enzyme activity was preserved by coupling the carbodiimide-activated enzyme to the carrier with alkyl or arylamino groups at the end of a longer substituent. Immobilization on diazo-modified carrier gave average results. Rapid immobilization by a lysine-modified phosgene-treated carrier resulted in an activity loss. It is suggested that multipoint and very tight attachment of the enzyme molecule to the matrix decreased the activity. The immobilized activity is quite stable in solution and very stable upon lyophilization with sucrose. | In 8 heart transplant recipients in follow-up checks we have evaluated the binding of transplantation antigen loaded methacrylate-carrier to peripheral mononuclear cells (rosette technique). All patients were treated with a triple-drug regimen for immunosuppression, consisting of steroids, azathioprine and cyclosporine A. The increase of the number of these antigen binding cells over a limit value of 30 RFC/103 MNC is a reliable sign of a beginning immune reaction against the graft. The evidence is given by comparing the results with these of situation in endomyocardial biopsies (EMB). The test is predictive 3 to 6 days before infiltrating cells are visible in biopsies and donor independent (use of antigen mixture from cadaver spleens). | Laccase is an enzyme that is used for fabricating cathodes of biofuel cells. Many studies have been aimed at searching the ways for enhancing specific electrochemical characteristics of cathode with the laccase- based catalyst. The electroreduction of oxygen on the electrode with immobilized laccase proceeds under the conditions of direct electron transfer between the electrode and active enzyme center. In this work, the effect of oxygen partial pressure on the electrocatalytic activity of laccase is studied. It is shown that, at the concentrations of oxygen dissolved in the electrolyte higher than 0.28 mM, the process is controlled by the kinetics of the formation of laccase–oxygen complex, whereas at lower concentrations and a polarization higher than 0.3 V, the process is limited by the oxygen diffusion. A wide range of carbon materials are studied as the carriers for laccase immobilization: carbon black and nanotubes with various BET specific surface areas. The conditions, which provide the highest surface coverage of carbon material with enzyme in the course of spontaneous adsorptive immobilization and the highest specific characteristics when using a “floating” electrode simulating a gas-diffusion electrode, are determined: 0.2 M phosphate-acetate buffer solution; oxygen atmosphere; the carrier material (nanotubes with a BET surface area of 210 m2/g and a mesopore volume of 3.8 cm3/g); and the composition of active mass on the electrode (50 wt % of carbon material + 50 wt % of hydrophobized carbon black). | eng_Latn | 17,538 |
Lipid-based delivery systems (LBDSs) are widely applied in pharmaceuticals and health care because of the increased bioavailability of lipophilic components when they are coadministered with high-fat meals. However, how to accurately control their in vivo release and stability is still challenging. Here, after introducing the simple esterification and coprecipitation, we created the dual-functional composite ODS-β-CD-VE by the coassembly of β-cyclodextrin (β-CD), octadecenyl succinic anhydride (ODSA), and vitamin E (VE). The resulting dual-functional particle presented a uniform sheetlike shape and nanometer size. In addition, its chemical structure was clarified in detail via nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Benefiting from the antioxygenation of VE, lipid oxidation in the ODS-β-CD-VE-stabilized Pickering emulsion was effectively inhibited. Meanwhile, pH-induced protonation/deprotonation of carboxyl groups guaranteed that the e... | Vitamin E (VE) and β-cyclodextrin (β-CD) can form an inclusion complex; however, the inclusion rate is low because of the weak interaction between VE and β-CD. The results of a molecular docking study showed that the oxygen atom in the five-membered ring of octenyl succinic anhydride (OSA) formed a strong hydrogen bond interaction (1.89 A) with the hydrogen atom in the hydroxyl group of C-6. Therefore, β-CD was modified using OSA to produce octenyl succinic-β-cyclodextrin (OCD). The inclusion complexes were then prepared using OCD with VE. The properties of the inclusion complex were investigated by Fourier-transform infrared spectroscopy (FT-IR), 13C CP/MAS NMR, scanning electron microscopy (SEM), and atomic force microscopy (AFM). The results demonstrated that VE had been embedded into the cavity of OCD. Furthermore, the emulsifying properties (particle size distribution, ζ-potential, and creaming index) of the OCD/VE inclusion-complex-stabilized emulsion were compared with that stabilized by β-CD, OCD, and an OCD/VE physical mixture. The results showed that the introduction of the OS group and VE could improve the physical stability of the emulsion. In addition, the OCD/VE inclusion complex showed the strongest ability to protect the oil in the emulsion from oxidation. OCD/VE inclusion complex was able to improve the physical and oxidative stability of the emulsion, which is of great significance to the food industry. | 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 | 17,539 |
Uniform, spherical CuCl particles were obtained by mixing aqueous solutions of CuCl2 and ascorbic acid in the presence of polyvinylpyrrolidone (PVP) as dispersing agent. The size and the uniformity of the resulting particles depended on the volume ratio of the reactant solutions, their concentrations, the distribution of the stabilizers, and the mixing method. The single jet precipitation yielded large spheres of broad size distributions, while the particles obtained by the double jet technique were rather uniform in size. The final colloidal CuCl particles were formed by the aggregation of nanocrystals, initially generated in the system. Depending on the pH of the reaction mixture, these particles slowly change to large CuCl crystals on aging in the mother liquor. | Metamaterials with tunable properties are of great importance due to potential applications in super-resolution lensing ::: and sensors. In this paper we study the feasibility of the fabrication of a metamaterial using binary nanoparticle-dispersed ::: liquid crystal cell (NDLCC). Depending on the angle between the director axis of the LCC and the incident ::: beam, types, radii, and volume filling fractions of the nanoparticles, a negative index of refraction cell is obtained in a ::: certain range of frequencies. The effective index of refraction is calculated using the effective medium theory. The ::: scattering, extinction, and absorption of such a NDLCC cell is also found. Finally, the influence of the various ::: parameters to obtain such a negative index metamaterial has been investigated. | Because of antibiotic resistance threats, there has been a resurgence of interest in Ag or Cu nanoparticles (NPs) with soft functional components as composite particulates or coatings for broad-spectrum and strong antibacterials despite the biotoxicity of the NPs. Although the composite architectures conferred stimuli-responsive and safer antibacterial functions to the particulates or coatings, the renewal of antibacterial activity for long-term care remains a challenge, and the preparation and storage of the composites require complex and costly chemistries and procedures. Consequently, developing a digitizable platform for the plug-in manufacture of ultrasmall (atomically countable) Ag or Cu particles may represent an important advancement because an on-demand post-processing method for conferring functional overlayers onto NPs was recently introduced. In this study, a tandem electrostatic system consisting of a carbon brush ionizer and a spark ablation device was developed, in which gaseous ions (1 × 107 ions cm−3) were injected into the spark ablation passage between Ag or Cu rods to ensure the steady and uniform manufacture of ultrasmall Ag or Cu particles (~3 nm). The resulting Ag or Cu particles exhibited stronger and more stable antibacterial activities against bacteria (including multidrug-resistant strains) than Ag or Cu NPs (>10 nm). | eng_Latn | 17,540 |
Isofagomine 1 (Scheme 1), a prominent member of the aza sugar family, was proposed and first synthesized by Lundt, Bols, and co-workers in 1994.[1] Subsequently, the molecule attracted considerable synthetic attention[2] owing to its strong inhibition of a range of enzymes that hydrolyze, in particular, the β-glycosidic linkage. One of the most expeditious syntheses of 1 starts from benzyl α-l-xylopyranoside and introduces the required nitrogen and extra carbon atom in the form of the nitrile 2.[2] This synthesis very closely follows our route to isofagomine, starting with benzyl β-l-xylopyranoside;[3] we have recently reported some | The ability to modify peptide- and protein-based biomaterials selectively under mild conditions and in aqueous buffers is essential to the development of certain areas of bionanotechnology, tissue engineering and synthetic biology. Here we show that Self-Assembling peptide Fibers (SAFs) can incorporate multiple modified peptides non-covalently, stoichiometrically and without disrupting their structure or stability. The modified peptides contain groups suitable for post-assembly click reactions in water, namely azides and alkenes. Labeling of these groups is achieved using the orthogonal Cu(I)-catalyzed azide-alkyne and photoinitiated thiol-ene reactions, respectively. Functionalization is demonstrated through the conjugation of biotin followed by streptavidin-nanogold particles, or rhodamine, and visualized by electron and light microscopy, respectively. This has been shown for fibers harboring either or both of the modified peptides. Furthermore, the amounts of each modified peptide in the fibers can be varied with concomitant changes in decoration. This approach allows the design and assembly of fibers with multiple functional components, paving the way for the development of multi-component functionalized systems. | 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 | 17,541 |
The syntheses of silicas with highly ordered cubic Ia3d structure templated by Pluronic P123 (EO20PO70EO20) block copolymer surfactant and sodium dodecyl sulfate (SDS) additive in the presence of swelling agents are demonstrated. It was found that the cubic Ia3d silica forms at 25 °C when a moderate amount of a swelling agent, such as 1,3,5-triisopropylbenzene (TIPB), 1,4-diisopropylbenzene (DIPB), or 1,3,5-triethylbenzene (TEB), is added. However, 1,3,5-trimethylbenzene was not found suitable, suggesting that the success of the synthesis requires a careful selection of a swelling agent. An increase in the relative amount of the swelling agent in a limited range tends to cause an increase in the unit-cell size, while a further unit cell parameter increase can be accomplished with TIPB through a concomitant decrease in the synthesis temperature and increase in the relative amount of the swelling agent. Many of the cubic Ia3d products, including those with the largest attained unit-cell sizes, were highly o... | Recent advancements in drug delivery technologies utilizing a variety of carriers have resulted in a path-breaking revolution in the approach towards diagnosis and therapy alike in the current times. Need for materials with high thermal, chemical and mechanical properties have led to the development of mesoporous silica nanoparticles (MSNs). These ordered porous materials have garnered immense attention as drug carriers owing to their distinctive features over the others. They can be synthesized using a relatively simple process, thus making it cost effective. Moreover, by controlling the parameters during the synthesis; the morphology, pore size and volume and particle size can be transformed accordingly. Over the last few years, a rapid increase in research on MSNs as drug carriers for the treatment of various diseases has been observed indicating its potential benefits in drug delivery. Their widespread application for the loading of small molecules as well as macromolecules such as proteins, siRNA and so forth, has made it a versatile carrier. In the recent times, researchers have sorted to several modifications in the framework of MSNs to explore its potential in drug resistant chemotherapy, antimicrobial therapy. In this review, we have discussed the synthesis of these multitalented nanoparticles and the factors influencing the size and morphology of this wonder carrier. The second part of this review emphasizes on the applications and the advances made in the MSNs to broaden the spectrum of its use especially in the field of biomedicine. We have also touched upon the lacunae in the thorough understanding of its interaction with a biological system which poses a major hurdle in the passage of this carrier to the clinical level. In the final part of this review, we have discussed some of the major patents filed in the field of MSNs for therapeutic purpose. | 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 | 17,542 |
Nanocatalysts that possess large amounts of atoms on sharp corners and edges and high indexed sites are known to be more catalytically active. We report here on a novel yet simple method to synthesize in large yields a very active platinum nanocatalyst; the multiarmed nanostar single crystal. We utilize a seed mediated method using tetrahedral nanoparticles that are also synthesized by a new and simple technique. High-resolution TEM shows that the nanostar has many arms, varying from a few to over 30, whereby even the largest ones are found to have single-crystal structures. This strongly suggests that they are formed by a growth mechanism of the seed crystals and not by the aggregation of seed crystals, which should produce twinning planes. Due to the reduction reaction of ferrricyanide by thiosulfate, the nanostars are found to have an activation energy, which is nearly 60% of that of the tetrahedral seeds themselves, both having the same PVP capping agent. This is undoubtedly due to the multiarms with edges, corners, and the presence of high indexed facets in the nanostar catalyst. | A continuing goal in catalysis is to unite the advantages of homogeneous and heterogeneous catalytic processes. To this end, nanoparticles represent a new frontier in heterogeneous catalysis, where this unification can also be supplemented by the ability to obtain new or divergent reactivity and selectivity. We report a novel method for applying heterogeneous catalysts to known homogeneous catalytic reactions through the design and synthesis of electrophilic platinum nanoparticles. These nanoparticles are selectively oxidized by the hypervalent iodine species PhICl(2), and catalyse a range of π-bond activation reactions previously only catalysed through homogeneous processes. Multiple experimental methods are used to unambiguously verify the heterogeneity of the catalytic process. The discovery of treatments for nanoparticles that induce the desired homogeneous catalytic activity should lead to the further development of reactions previously inaccessible in heterogeneous catalysis. Furthermore, a size and capping agent study revealed that Pt PAMAM dendrimer-capped nanoparticles demonstrate superior activity and recyclability compared with larger, polymer-capped analogues. | 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 | 17,543 |
The present study examined the effects of cognitive skills (processing speed, visual memory and auditory memory) and body mass index (BMI) on cardiovascular responses to stress. It was hypothesized that obese participants who score lower on measures of cognitive skills would have greater cardiovascular responses to the stressor than normal weight participants higher scores on the cognitive skills. The participants for the study were 97 African American college students between the ages of 18-27. BMI ranged from 15.60-47.10 kg/m2 and the mean BMI was 26.47 kg/m2. Cognitive skills were taken from a battery that is being developed as the Gibson Cognitive Skills Test. The cognitive skills used in the present study were processing speed, visual memory and auditory memory. Cardiovascular measures were taken as the participants viewed a racially noxious scene on videotape. The scene depicted the horrendous conditions that Africans experienced, as they were transported to America for slavery. Findings from the study revealed that individuals with lower cognitive skill levels and higher BMIs had higher blood pressures and blood output than their counterparts. This project expands our knowledge of cardiovascular responses to stress, by examining the influence of cognition in the process. A continuation of this research would assist with providing a deeper understanding of the impact of cognition on obesity and cardiovascular disease. | Nanotechnology is a new technology of the century and it is showing tremendous results in many fields like medical, pharmaceutical, agriculture etc. Applications of Nanotechnology in the food division are completely different in their usage in pharmaceutical industry. Numerous researchers have discovered well the capability of nanoscience to lead all the food firms better in the 21st century. Despite the fact that effective uses of nanotechnology to food are still constrained, some essential ideas in light of nanoscale have been built up well. In food technology field, two noteworthy applications identified with nanotechnology. In the previous field, better food safety estimation and quality can be accomplished by utilizing nanotechnology. Progresses in advances, for example, DNA microarrays, microelectromechanical frameworks, and microfluidics, will empower the acknowledgment of the capability of nanotechnology for food preparation and storage applications. In the last mentioned, food preparing can be to a great extent enhanced in the parts of keen delivery of supplements, bioseparation of proteins, quick testing of organic and substance contaminants, nanoencapsulation of nutraceuticals, solubilization, delivery, and colour in food network; these being a portion of the known topics of nanotechnology for food and agriculture. In the meantime, sustenance nanotechnology as another innovation is in a need of reviews of the potential side effects and in addition numerous positive outcomes. In this survey, we proposed to cover a portion of the advancements in nanotechnology and their applications to food, nutrition and pharmaceutical systems. It introduces a portion of the nanoscale-sized structure that is particularly pertinent to the sustenance business, the distinctive nourishment producing strategies that could profit by nanotechnology, and nanotechnology's applications to the formulation and food storage, together with identifying the difficulties. | Demography research rarely examines the black box within which the cognitive diversity of the top management team is assumed to affect firm performance. Using data from 35 simulated firms run by a total of 159 managers attending executive education programs, the current research tested several hypotheses concerned with (a) the relationship between demographic and cognitive team diversity and (b) the reciprocal effects of diversity and firm performance. Results showed that members of high-performing teams tended to preserve multiple interpretations early in the team's life cycle, but that they moved toward greater clarity near the end of the life cycle. These high-performing teams, therefore, exhibited both early interpretative ambiguity and late heedful interrelating. Cognitive diversity in teams affected and was affected by changes in firm performance. Surprisingly, there was no evidence of any effect of demographic diversity on measures of cognitive diversity. | eng_Latn | 17,544 |
The key feature of enzymic catalysis is recognition of the transition state. Synthesis of designed systems rarely leads to successful catalysts as the rules for conformation and intermolecular interactions are to imperfectly understood. This review describes several current ‘selection’ approaches to the generation of systems that can recognise transitionstate analogues. Examples covered include catalytic antibodies, ribozymes, imprinted polymers. Combinatorial chemistry, and thermodynamic templating. All have the potential to yeild effective catalysts without prior design of every detail. | The increasing demand for enzymes as highly selective, mild, and environmentally benign catalysts is often limited by the lack of an enzyme with the desired catalytic activity or substrate selectivity and by their instability in biotechnological processes. The previous answers to these problems comprised genetically engineered enzymes and several classes of enzyme mimics. Here we describe the potential of chemical enzyme engineering: native enzymes can be modified by merely chemical means and basic equipment yielding so-called semisynthetic enzymes. Thus, the high substrate selectivity of the enzymatic peptide framework is combined with the catalytic versatility of a synthetic active site. We illustrate the potential of chemically engineered enzymes with the conception of the semisynthetic peroxidase seleno-subtilisin. First, the serine endoprotease subtilisin was crystallized and cross-linked with glutaraldehyde to give cross-linked enzyme crystals which were found to be insoluble in water or organic solvents and highly stable. Second, serine 221 in the active site (Enz-OH) was chemically converted into an oxidized derivative of selenocystein (Enz-SeO2H). As a consequence, the former proteolytic enzyme gained peroxidase activity and catalyzed the selective reduction of hydroperoxides. Due to the identical binding sites of the semisynthetic peroxidase and the protease, the substrate selectivity of seleno-subtilisin was predictable in view of the well-known selectivity of subtilisin. | Miniaturized electrochemical in vivo biosensors allow the measurement of fast extracellular dynamics of neurotransmitter and energy metabolism directly in the tissue. Enzyme-based amperometric biosensing is characterized by high specificity and precision as well as high spatial and temporal resolution. Aside from glucose monitoring, many systems have been introduced mainly for application in the central nervous system in animal models. We compare the microsensor principle with other methods applied in biomedical research to show advantages and drawbacks. Electrochemical sensor systems are easily miniaturized and fabricated by microtechnology processes. We review different microfabrication approaches for in vivo sensor platforms, ranging from simple modified wires and fibres to fully microfabricated systems on silicon, ceramic or polymer substrates. The various immobilization methods for the enzyme such as chemical cross-linking and entrapment in polymer membranes are discussed. The resulting sensor performance is compared in detail. We also examine different concepts to reject interfering substances by additional membranes, aspects of instrumentation and biocompatibility. Practical considerations are elaborated, and conclusions for future developments are presented. Graphical ᅟ. | eng_Latn | 17,545 |
Polyphosphates are important but neglected polyelectrolytes that play a major role in biology and in surface science for the stabilization of colloids against flocculation and for the preservation of food. They are also known as “Calgon” ® and intensively used as additives in washing powders. This review aims to review recent developments in which linear polyphosphates are used for the design of new functional coatings using sol–gel processes and layer-by-layer deposition methods. All these methods rely on the high charge density of polyphosphates as inorganic polyelectrolytes, therefore the structure and properties of these molecules are also reviewed. New perspectives will also been given for the design of stimuli responsive coatings at the tiny frontier between biology and materials science. | Cells acquire free metals through plasma membrane transporters. But, in natural settings, sequestering agents often render metals inaccessible to transporters, limiting metal bioavailability. Here we identify a pathway for metal acquisition, allowing cells to cope with this situation. Under limited bioavailability of Mg2+, yeast cells upregulate fluid-phase endocytosis and transfer solutes from the environment into their vacuole, an acidocalcisome-like compartment loaded with highly concentrated polyphosphate. We propose that this anionic inorganic polymer, which is an avid chelator of Mg2+, serves as an immobilized cation filter that accumulates Mg2+ inside these organelles. It thus allows the vacuolar exporter Mnr2 to efficiently transfer Mg2+ into the cytosol. Leishmania parasites also employ acidocalcisomal polyphosphate to multiply in their Mg2+-limited habitat, the phagolysosomes of inflammatory macrophages. This suggests that the pathway for metal uptake via endocytosis, acidocalcisomal polyphosphates and export into the cytosol, which we term EAPEC, is conserved.Metal bioavailability is frequently limited by sequestering agents which makes them inaccessible to cells. Here the authors show that cells can increase Mg2+ uptake via fluid phase endocytosis and accumulate this metal in their vacuole loaded with polyphosphate, and later can be exported to the cytosol. | 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 | 17,546 |
Comparative studies of the morphological characteristics of selenium- and platinum-containing nanostructures were performed by molecular optics methods. The nanostructures were based on an ionogenic polymeric stabilizer, poly-N,N,N,N-trimethylmethacryloyloxyethylammonium methyl sulfate, and a non-ionogenic polymeric stabilizer, oxyethylcellulose. Studies were performed in aqueous solutions at a fixed ratio between components. The adsorption of a considerable number of polymer macromolecules on nanoparticles with the formation of superhigh-molecular-weight nanostructures with shapes close to spherical was observed for all the nanosystems studied. The thermodynamic state of nanosystems was characterized. Certain morphological characteristics of nanostructures were substantially influenced by the nature of both nanoparticles and polymer matrix. | In this study, a simple technique for preparation of colloid solution of metal nanoparticles in polyethylene glycol (PEG)/H2O is described. By this technique, stable colloidal metal solutions can be prepared ready for use without application of chemical reactions, stabilizers, or reducing agents. The nanoparticles are created by direct sputtering of metal into PEG. The influence of sputter conditions and the concentration of PEG/H2O on the properties of nanoparticles was studied. The nanoparticles were characterized by transmission electron microscopy, atomic absorption spectrometry, dynamic light scattering, and UV–Vis spectroscopy. UV–Vis spectra of gold nanoparticle solution exhibit localized surface plasmon resonance characteristic peaks located in the region 513–560 nm (PEG/H2O—1/1), 509–535 nm (PEG/H2O—1/9), and for silver nanoparticles in the region from 401 to 421 nm. Silver nanoparticles have a broader size distribution compared with gold ones. An appropriate choice of concentration, mixing, and deposition conditions allows preparing the stable solution of gold or silver nanoparticles. | 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 | 17,547 |
This paper reviews our recent work on DNA-based nanofabrication. DNA nanostructures were used as a template to initiate direct pattern transfers to a diverse range of substrates, including oxides, polymers, and self-assembled monolayers. Complex patterns were obtained in many cases with a lateral resolution down to sub-10 nm demonstrated in some cases. These results highlight the potential of DNA nanotechnology in low cost, high resolution patterning. | We demonstrate a new approach to pattern transfer for bottom-up nanofabrication. We show that DNA promotes/inhibits the etching of SiO(2) at the single-molecule level, resulting in negative/positive tone pattern transfers from DNA to the SiO(2) substrate. | Background ::: The solution of 3D models in degenerated geometries in which some characteristic dimensions are much lower than the other ones -e.g. beams, plates, shells,...- is a tricky issue when using standard mesh-based discretization techniques. | eng_Latn | 17,548 |
BACKGROUND ::: Stem cells can differentiate into multiple cell types, and therefore can be used for cellular therapies, including tissue repair. However, the participation of stem cells in tissue repair and neovascularization is not well understood. Therefore, implementing a noninvasive, long-term imaging technique to track stem cells in vivo is needed to obtain a better understanding of the wound healing response. Generally, we are interested in developing an imaging approach to track mesenchymal stem cells (MSCs) in vivo after delivery via a polyethylene glycol modified fibrin matrix (PEGylated fibrin matrix) using MSCs loaded with gold nanoparticles as nanotracers. The objective of the current study was to assess the effects of loading MSCs with gold nanoparticles on cellular function. ::: ::: ::: METHODS ::: In this study, we utilized various gold nanoparticle formulations by varying size and surface coatings and assessed the efficiency of cell labeling using darkfield microscopy. We hypothesized that loading cells with gold nanotracers would not significantly alter cell function due to the inert and biocompatible characteristics of gold. The effect of nanoparticle loading on cell viability and cytotoxicity was analyzed using a LIVE/DEAD stain and an MTT assay. The ability of MSCs to differentiate into adipocytes and osteocytes after nanoparticle loading was also examined. In addition, nanoparticle loading and retention over time was assessed using inductively coupled plasma mass spectrometry (ICP-MS). ::: ::: ::: CONCLUSION ::: Our results demonstrate that loading MSCs with gold nanotracers does not alter cell function and, based on the ICP-MS results, long-term imaging and tracking of MSCs is feasible. These findings strengthen the possibility of imaging MSCs in vivo, such as with optical or photoacoustic imaging, to understand better the participation and role of MSCs in neovascularization. | Tissue engineering has evolved with multifaceted research being conducted using advanced technologies, and it is progressing toward clinical applications. As tissue engineering technology significantly advances, it proceeds toward increasing sophistication, including nanoscale strategies for material construction and synergetic methods for combining with cells, growth factors, or other macromolecules. Therefore, to assess advanced tissue-engineered constructs, tissue engineers need versatile imaging methods capable of monitoring not only morphological but also functional and molecular information. However, there is no single imaging modality that is suitable for all tissue-engineered constructs. Each imaging method has its own range of applications and provides information based on the specific properties of the imaging technique. Therefore, according to the requirements of the tissue engineering studies, the most appropriate tool should be selected among a variety of imaging modalities. The goal of this ... | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 17,549 |
The functionalization of silk through nanotechnology is becoming an important research field to prevent fiber damage from microbial attack and improve hygienic aspects. The eco-friendly fabrication of silver nanoparticles (AgNPs)-modified silk using natural extracts has recently gained considerable interests. This study presented a facile method of incorporating AgNPs onto silk using baicalin (a bioactive constituent of Scutellaria baicalensis Georgi) as a natural reductant and a stabilizing agent. The influences of synthesis factors on the yield and particle size of AgNPs were investigated. The color characteristics and functionalities of the AgNPs treated silk were evaluated. The results showed that the yield and particle size of AgNPs were influenced by synthesis conditions. AgNPs were inclined to form in basic condition. The particle size of AgNPs decreased with increasing baicalin and decreasing AgNO 3 concentrations. The TEM image showed that AgNPs were predominantly spherical in shape and uniform in size. The functional evaluations revealed that the AgNPs treated silk possessed excellent antibacterial activities against Escherichia coli and Staphylococcus aureus , and certain antioxidant activity. The vitality of this research lies in the sustainable and eco-friendly synthesis of AgNPs using baicalin, which can be successfully applied in the preparation of hygiene-related and medical silk materials. | In this investigation, Ag@AgCl nanoparticles were synthesized by a green and inexpensive method using Elaeagnus angustifolia leaves, as a reducing and stabilizing agent without using any toxic solvent, external halide source, harsh chemicals, or capping agents. In this protocol, the nanophotocatalyst was synthesized via immobilization of Ag@AgCl NPs on the surface of biowaste Elaeagnus angustifolia seed (EAS) as a green support, which prevents the agglomeration Ag@AgCl NPs and improves the catalytic activity. The biosynthesized nanophotocatalyst were characterized by UV-Vis spectroscopy, Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE SEM), energy dispersive X-ray spectroscopy (EDS), and transform electron microscopy (TEM) and inductively couple plasma mass spectrometry (ICP). In order to investigate the photocatalytic activity of the biosynthesized nanophotocatalyst, it was used in the degradation of methylene blue (MB) under sunlight. The results showed that nanophotocatalyst had an excellent photo activity without any agglomeration. In addition, the nanophotocatalyst can be easily be recycled and reused several times without losing its activity. Graphical abstract. | 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 | 17,550 |
A novel and efficient method for molecular engineering of the pore size and porosity of microporous sol–gel silica membranes is demonstrated in this communication. By adding a suitable organic template (e.g. tetraethyl- or tetrapropylammonium bromide) in polymeric silica sols, otherwise known to result in microporous membranes with pores in the range 3–4 A, we can ‘shift’ the pore size to 5–6 A, as judged by single-component gas and vapor permeation results with probe molecules of increasing kinetic diameter (dk). The templated membranes exhibit permeances as high as 10 −7 to 10 −6 mol m −2 s −1 Pa −1 for molecules with dk < 4.0 A (e.g. CO2 ,N 2 ,C H 4), coupled with single-component selectivities of 100–1800 for N2/SF6, 20–40 for n-butane/iso-butane, and 10–20 for para-xylene/ortho-xylene. The transport properties of the templated membranes are distinctly different from those of the respective silica membranes prepared without templating, and resemble somewhat the transport properties of polycrystalline zeolite MFI membranes prepared by the lengthy, batch hydrothermal synthesis approach, using tetrapropylammonium bromide as a structure directing agent. © 2003 Elsevier Science B.V. All rights reserved. | We present a new processing scheme for the deposition of microporous, sol–gel derived silica membranes on inexpensive, commercially available anodic alumina (Anodisk TM ) supports. In a first step, a surfactant-templated mesoporous silica sublayer (pore size 2–6 nm) is deposited on the Anodisk support by dip-coating, in order to provide a smooth transition from the pore size of the support (20 or 100 nm) to that of the membrane (3–4 u | 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 | 17,551 |
The Fe3O4 magnetic nanoparticles were prepared by precipitating ferrous ion (Fe2+) and ferric ion (Fe3+) in alkaline solution. The Fe3O4 magnetic nanoparticles were modified by tannic acid. After functionalization process, two methods were used to immobilize Lipase on Fe3O4 magnetic nanoparticles. In the first method, novel tannic acid magnetic cross-linked enzyme aggregates of lipase (TA-MNPs-CLEAs) were synthesized by cross-linking of lipase aggregates and starch as co-feeder with Fe3O4 magnetic nanoparticles improved by tannic acid (TA-MNPs). In the second method, the lipase was successfully immobilized on the surface of TA-MNPs. The properties of Fe3O4 and its modified forms were examined by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM) and zeta potential measurements. Novel TA-MNPs-lipase and TA-MNPs-CLEAs-starch-lipase were enhanced and provided an effective method to improve the activity and stability of lipase for biodiesel production. Using 1% TA-MNPs-lipase and TA-MNPs-CLEAs-starch (w/w of oil) conversions around 67.87, and 85.88%, respectively, were obtained at 40 °C after 2 h of reaction. Furthermore, the immobilized enzyme was easily recovered from the reaction mixture and reused. The obtained results suggest that TA-MNPs-lipase and TA-MNPs-CLEAs-starch-lipase can become a powerful biocatalyst for biodiesel production. | Oxide material of a new type, ZrO2·SiO2 (raw and carbonyl-grafted), was used as support in the immobilization of aminoacylase from Aspergillus melleus. The ZrO2·SiO2 was synthesized via sol–gel method. The obtained material was additionally modified with glutaraldehyde. Various physicochemical analyses were used to confirm the effectiveness of the modification and immobilization processes, including Fourier transform infrared spectroscopy, laser Doppler velocimetry and low-temperature N2 sorption. The immobilization process was performed within 3 h using different concentrations of enzyme solution (1, 3, 5 and 7 mg/mL), and the Bradford method was used to determine the quantity of immobilized enzyme. The resulting biocatalytic systems were then used as catalysts in the hydrolysis of different N-acetyl-dl-amino acids (leading to l-methionine, l-cysteine, l-serine and l-tryptophan). Based on this reaction the apparent and relative catalytic activities were determined. The highest activity of the immobilized enzyme was attained in the synthesis of l-methionine (the apparent activities of aminoacylase immobilized on raw and carbonyl-grafted ZrO2·SiO2 were 4112 and 4947 U/g, respectively). Furthermore, the effect of pH and temperature on catalytic activity, as well as the storage stability and reusability of the prepared biocatalytic systems were determined. Aminoacylase immobilized on carbonyl-grafted ZrO2·SiO2 retains 85% of its initial activity after 30 days of storage and 70% after five reaction cycles. | Context: We reported that D-4F, an apolipoprotein A-I (Apo A-I) mimetic polypeptide with 18 d-amino acids, suppressed IL-4 induced macrophage alternative activation and TGF-β1 expression in... | eng_Latn | 17,552 |
The effect of surfactant tail structure on the stability of a water/supercritical CO2 microemulsion (W/scCO2 muE) was examined for various fluorinated double-tail anionic surfactants of different fluorocarbon chain lengths, F(CF2)n (n = 4, 6, 8, and 10), and oxyethylene spacer lengths, (CH2CH2O)(m/2) (m = 2 and 4). The phase behavior of the water/surfactant/CO2 systems was studied over a wide range of CO2 densities from 0.70 to 0.85 g/cm(3) (temperatures from 35 to 75 degrees C and pressures up to 500 bar) and corrected water-to-surfactant molar ratios (W0c). All of the surfactants yielded a W/scCO2 muE phase, that is, a transparent homogeneous phase with a water content larger than that permitted by the solubility of water in pure CO2. With increasing W0c, a phase transition occurred from the muE phase to a macroemulsion or a lamella-like liquid crystal phase. The maximum W0c value was obtained at a tail length of 12-14 A, indicating the presence of an optimum surfactant tail length for W/scCO2 muE formation. | The article addresses the role of surfactant headgroup structure on hybrid surfactant performance for water-in-CO 2 (w/c) microemulsion stabilization. The synthetic procedure, aqueous properties, and phase behaviour of a new hybrid sulfoglutarate surfactant are described. The sulfoglutarate version has an extra methylene group incorporated into the hydrophilic headgroup. The related hydrocarbon (AOT14 and AOT14GLU) and fluorocarbon (di-CF2 and di-CF2GLU) surfactants were used to form w/c microemulsions. For these two groups, the aqueous properties and w/c phase stability of both sulfoglutarates and sulfosuccinates were found to be similar. The newly synthesized hybrid CF2/AOT14GLU (sodium (4 H, 4 H, 5 H, 5 H, 5 H -pentafluoropentyl-2,2-dimethyl-1-propyl)-2-sulfoglutarate) proved to be more efficient than the normal sulfosuccinate, hybrid CF2/AOT14 in terms of the aqueous behaviour and w/c phase stability. Hybrid CF2/AOT14GLU more effectively decreased the air-water surface tension by ∼2 mN m −1 and lowering the cloud pressures on CO 2 by ∼150 bar. | Exposure of lung tissues to cigarette smoke is a major cause of human disease and death worldwide. Unfortunately, adequate model systems that can reliably recapitulate disease biogenesis in vitro, including exposure of the human lung airway to fresh whole cigarette smoke (WCS) under physiological breathing airflow, are lacking. This protocol extension builds upon, and can be used with, our earlier protocol for microfabrication of human organs-on-chips. Here, we describe the engineering, assembly and operation of a microfluidically coupled, multi-compartment platform that bidirectionally ‘breathes’ WCS through microchannels of a human lung small airway microfluidic culture device, mimicking how lung cells may experience smoke in vivo. Several WCS-exposure systems have been developed, but they introduce smoke directly from above the cell cultures, rather than tangentially as naturally occurs in the lung due to lateral airflow. We detail the development of an organ chip–compatible microrespirator and a smoke machine to simulate breathing behavior and smoking topography parameters such as puff time, inter-puff interval and puffs per cigarette. Detailed design files, assembly instructions and control software are provided. This novel platform can be fabricated and assembled in days and can be used repeatedly. Moderate to advanced engineering and programming skills are required to successfully implement this protocol. When coupled with the small airway chip, this protocol can enable prediction of patient-specific biological responses in a matched-comparative manner. We also demonstrate how to adapt the protocol to expose living ciliated airway epithelial cells to smoke generated by electronic cigarettes (e-cigarettes) on-chip. This protocol describes a biomimetic smoking robot that can be used in combination with microfluidic organ chips to simulate disease biogenesis in vitro. | eng_Latn | 17,553 |
Nanotechnology is a relatively new branch of science that involves harnessing the unique properties of particles that are nanometers in scale (nanoparticles). Nanoparticles can be engineered in a precise fashion where their size, composition and surface chemistry can be carefully controlled. This enables unprecedented freedom to modify some of the fundamental properties of their cargo, such as solubility, diffusivity, biodistribution, release characteristics and immunogenicity. Since their inception, nanoparticles have been utilized in many areas of science and medicine, including drug delivery, imaging, and cell biology1-4. However, it has not been fully utilized outside of "nanotechnology laboratories" due to perceived technical barrier. In this article, we describe a simple method to synthesize a polymer based nanoparticle platform that has a wide range of potential applications. ::: ::: The first step is to synthesize a diblock co-polymer that has both a hydrophobic domain and hydrophilic domain. Using PLGA and PEG as model polymers, we described a conjugation reaction using EDC/NHS chemistry5 (Fig 1). We also discuss the polymer purification process. The synthesized diblock co-polymer can self-assemble into nanoparticles in the nanoprecipitation process through hydrophobic-hydrophilic interactions. ::: ::: The described polymer nanoparticle is very versatile. The hydrophobic core of the nanoparticle can be utilized to carry poorly soluble drugs for drug delivery experiments6. Furthermore, the nanoparticles can overcome the problem of toxic solvents for poorly soluble molecular biology reagents, such as wortmannin, which requires a solvent like DMSO. However, DMSO can be toxic to cells and interfere with the experiment. These poorly soluble drugs and reagents can be effectively delivered using polymer nanoparticles with minimal toxicity. Polymer nanoparticles can also be loaded with fluorescent dye and utilized for intracellular trafficking studies. Lastly, these polymer nanoparticles can be conjugated to targeting ligands through surface PEG. Such targeted nanoparticles can be utilized to label specific epitopes on or in cells7-10. | The efficient and reproducible production of nanoparticles using bulk nanoprecipitation methods is still challenging because of low batch to batch reproducibility. Here, we optimize a bulk nanoprecipitation method using design of experiments and translate to a microfluidic device to formulate surface-modified poly-lactic-co-glycolic (PLGA) nanoparticles. Cell-penetrating peptides (CPPs) with a short, long linear or branched architecture were used for the surface modification of PLGA nanoparticles. The microfluidics method was more time efficient than the bulk nanoprecipitation method and allowed the formulation of uniform PLGA nanoparticles with a size of 150 nm, a polydispersity index below 0.150 and with better reproducibility in comparison to the bulk nanoprecipitation method. After surface modification the size of CPP-tagged PLGA nanoparticles increased to 160-180 nm and the surface charge of the CPP-tagged PLGA nanoparticles varied between -24 mV and +3 mV, depending on the architecture and concentration of the conjugated CPP. Covalent attachment of CPPs to the PLGA polymer was confirmed with FTIR by identifying the formation of an amide bond. The conjugation efficiency of CPPs to the polymeric PLGA nanoparticles was between 32 and 80%. The development and design of reproducible nanoformulations with tuneable surface properties is crucial to understand interactions at the nano-bio interface. | 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 | 17,554 |
A new adenine-functionalized polythiophene (PAT) has been developed which allows the incorporation of multiple self-complementary hydrogen-bonded groups into micelles. After the encapsulation of fullerene derivatives (PCBM) into PAT, their excellent electrochemical storage capacities make the PAT/PCBM micelle a promising candidate for an electron storage/transport layer in the fabrication of high-performance electrochemical devices. | In this paper we report the first observation, through X-ray diffraction, of noncovalent uracil–uracil (U–U) dimeric π-stacking interactions in carbon nanotube (CNT)–based supramolecular assemblies. The directionally oriented morphology determined using atomic force microscopy revealed highly organized behavior through π-stacking of U moieties in a U-functionalized CNT derivative (CNT–U). We developed a dispersion system to investigate the bio-inspired interactions between an adenine (A)-terminated poly(3-adeninehexyl thiophene) (PAT) and CNT–U. These hybrid CNT–U/PAT materials interacted through π-stacking and multiple hydrogen bonding between the U moieties of CNT–U and the A moieties of PAT. Most importantly, the U···A multiple hydrogen bonding interactions between CNT–U and PAT enhanced the dispersion of CNT–U in a high-polarity solvent (DMSO). The morphology of these hybrids, determined using transmission electron microscopy, featured grape-like PAT bundles wrapped around the CNT–U surface; this tight connection was responsible for the enhanced dispersion of CNT–U in DMSO. | Context: We reported that D-4F, an apolipoprotein A-I (Apo A-I) mimetic polypeptide with 18 d-amino acids, suppressed IL-4 induced macrophage alternative activation and TGF-β1 expression in... | eng_Latn | 17,555 |
Molecular communication is engineered biological communication (e.g., cell-to-cell signaling) that allows nanomachines (e.g., engineered organisms, artificial devices) to communicate through the use of chemical signals or molecules. In this paper, we describe a cell-based molecular communication network, a class of molecular communication systems in which nanomachines communicate using a cell-cell communication network. | Molecular communication is engineered biological communication (e.g., cell-to-cell signaling) that allows nanomachines (e.g., engineered organisms, artificial devices) to communicate through chemical signals in an aqueous environment. This paper describes the design of a molecular communication system based on intercellular calcium signaling networks. This paper also describes possible functionalities (e.g., signal switching and aggregation) that may be achieved in such networks. | Molecular communication is engineered biological communication (e.g., cell-to-cell signaling) that allows nanomachines (e.g., engineered organisms, artificial devices) to communicate through chemical signals in an aqueous environment. This paper describes the design of a molecular communication system based on intercellular calcium signaling networks. This paper also describes possible functionalities (e.g., signal switching and aggregation) that may be achieved in such networks. | eng_Latn | 17,556 |
We have developed a self-assembly method for patterning thin CoSi 2 layers on Si(100) during their formation in a solid state reaction. This technique is based on anisotropic diffusion in a local stress field during rapid thermal processing. The stress is induced by a layer structure consisting of 30 nm SiO 2 and 300 nm Si 3 N 4 which is patterned with conventional optical lithography. We have investigated two different silicide formation processes. Firstly, we deposited Co on Si in a UHV MBE chamber. Rapid thermal annealing leads to the formation of polycrystalline CoSi 2 . Secondly, we used a titanium oxide mediated epitaxy process. For both processes we observed nanostructures with dimensions of about 100 nm showing wave-like separation edges in the first case and good uniformity in the second case. | A series of investigation were performed on Mn films which were deposited on GaAs substrates by thermal evaporation. The Mn films exhibit a highly ordered ripple-shaped structure with good periodicity, creating an exclusive patterning tool to construct two dimensional arrays of confined microstructures. The influence of the thickness of the Mn film in producing the ripple structure was clearly observed. In addition, the annealing time was considered as the major parameter to control the ordering of the ripple structure. A model for the creation of stress-driven microstructure is also proposed which indicates that Mn thin films grow on GaAs substrates in three stages: in the primary stage, the growth occurs via two-dimensional nucleation process; as the thickness increases, the stress is released by the film via creation of additional surface roughness which produce ripples; and finally an island-like growth occurs because of the non-uniform distribution of stress along the surface of the film. | Antigen-specific immunotherapy is the only curative approach for the treatment of allergic diseases such as Japanese cedar pollinosis. Immunotherapy using a T cell epitope vaccine in combination with the adjuvant R848 is of particular interest as a safe and effective approach to treat allergic diseases. Herein, we propose a simple and easy to handle vaccine administration method using the original solid-in-oil (S/O) nanodispersion system that permeates through the skin. The S/O nanodispersion system is composed of nanoparticles of hydrophilic molecules surrounded with hydrophobic surfactants that are dispersed in an oil vehicle. The system has potential to carry and deliver both hydrophilic and hydrophobic bioactives. Hydrophilic T cell epitope peptide was efficiently delivered through mouse skin using the S/O nanodispersion system and lowered antigen-specific IgE levels in pollinosis model mice. Addition of the hydrophobic adjuvant R848 significantly lowered the antibody secretion and shifted the Th1/Th2-balance toward Th1-type immunity in the model mice, showing the potential to alleviate Japanese cedar pollinosis. This article is protected by copyright. All rights reserved. | eng_Latn | 17,557 |
The synthesis of gold nanoparticles (AuNPs), especially by green methods, has attracted great attention due to their unique size-dependent optical properties, biocompatibility and diverse applications in various fields. The formation of stable AuNPs with control of size and shape often requires the use of a surfactant or some surface stabilizing ligands. Unfortunately, these stabilizing agents may hinder the catalytic activity and adversely affect the biocompatibility of the surfactant/AuNPs assembly. In this article, we report a one-pot, green synthesis of ligand-free AuNPs employing the eco-friendly glycerol both as reducing agent and stabilizing agent, thereby, greatly simplifying the synthesis process. The effect of glycerol:water (G:W) ratio, pH, temperature, dilution, ionic strength and aging on the stability and particle size distribution was studied. Stable AuNPs with reasonably good size distribution (8 ± 2 nm) were obtained which, at room temperature, showed no significant agglomeration or size change up to 04 days and only slight changes were seen after 08 days. The stability and size distribution of the particles was found to be dependent on the G:W ratio, temperature and pH of the reaction media. Owing to their clean surface, the synthesized ligand-free AuNPs exhibit advantage of lower energy requirement for glycerol electro-oxidation when compared to bulk Au and AuNPs-PVP materials. Such surfactant-free biocompatible AuNPs prepared using the eco-friendly glycerol may find useful applications in catalysis and biomedical applications. | This paper describes a method of coating metallic gold (Au) nanoparticles with chitosan (CS) shells in an aqueous solution. A colloidal solution of Au nanoparticles with a particle size of 16.5 ± 1.7 nm was prepared by reducing the Au ions (III) with sodium citrate in water at 80 °C. CS coating was achieved in an aqueous solution containing the Au nanoparticles by using CS as a shell source and sodium hydroxide as a pH adjuster at 25 °C. Ultraviolet-visible extinction spectroscopy and transmittance electron microscopy observation revealed that the Au nanoparticles were coated with CS shells. Additionally, the CS shell thickness could be varied in a range up to 2.2 nm by changing the CS concentration during the CS-coating process. | We consider the election model in which voters choose a subset from the set of candidates. Both voters and candidates are assumed to possess preferences with separable strict orderings. We investigate a rule satisfying candidate stability, which is the requirement to deter any candidate from strategic withdrawal. We show that a rule satisfies candidate stability if and only if it satisfies independence of the selection for each candidate. | eng_Latn | 17,558 |
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA. All rights reserved. Interest in continuous processing in the biotech industry has increased recently with the latest advances in perfusion cell culture technologies and the emergence of semicontinuous chromatography. Continuous manufacturing technologies have long been perceived to be more complex to implement and validate in the biotech sector. However, more recent continuous systems aim to overcome these obstacles with the promise of higher productivities and lower failure rates. This presentation will evaluate the potential of integrated batch and continuous processes via a series of case studies based on the commercial manufacture of monoclonal antibodies (mAb). The operational, economic, and environmental feasibility of these technologies is evaluated using a prototype dynamic decision-support tool built at University College London encompassing process economics, discrete-event simulation, and uncertainty analysis so as to enable a holistic assessment. The first case study compares fed-batch culture to two perfusion technologies: spin-filter perfusion and an emerging perfusion technology utilizing alternating tangential flow perfusion reactors. The second case study presents an integrated experimental and modeling approach to evaluate the potential of semicontinuous chromatography for the capture of mAbs in both clinical and commercial manufacture. The final case study provides a wide-ranging overview of the performance of continuous processing relative to the current batch platform for the mAb sector. | The current processing paradigm of large manufacturing facilities dedicated to single product production is no longer an effective approach for best manufacturing practices. Increasing competition for new indications and the launch of biosimilars for the monoclonal antibody market have put pressure on manufacturers to produce at lower cost. Single-use technologies and continuous upstream processes have proven to be cost-efficient options to increase biomass production but as of today the adoption has been only minimal for the purification operations, partly due to concerns related to cost and scale-up. This review summarizes how a single-use holistic process and facility strategy can overcome scale limitations and enable cost-efficient manufacturing to support the growing demand for affordable biologics. Technologies enabling high productivity, right-sized, small footprint, continuous, and automated upstream and downstream operations are evaluated in order to propose a concept for the flexible facility of the future. | Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights. | eng_Latn | 17,559 |
Three different β-lactamase substrate profiles were identified in 95 isolates of coagulase-negative staphylococci (CNS), of 57 different phenotypes, from 16 orthopaedic inpatients and staff members in one ward, by applying a bacterial whole-cell assay based on the hydrolysis of cefazolin, cephaloridine and nitrocefin. The typability of the assay was 93%, and 91% of the CNS isolates could be classified. To assess the discrimination between the β-lactamase profiles obtained in the whole-cell assay, β-lactamase extracts from 19 of the CNS isolates were used for estimation of their relative β-lactamase substrate affinity index (RSAI). The RSAI assay was able to type previously unclassifiable or nontypable isolates. Two of the profiles obtained with the whole-cell assay were similar to those of the Staphylococcus aureus controls producing A or D and B or C β-lactamases respectively. The distribution of β-lactamase substrate profiles among the CNS isolates indicated an efficient spread of these drug resistance genes. | beta-Lactamases are the commonest single cause of bacterial resistance to beta-lactam antibiotics. Numerous chromosomal and plasmid-mediated types are known and may be classified by their sequences or phenotypic properties. The ability of a beta-lactamase to cause resistance varies with its activity, quantity, and cellular location and, for gram-negative organisms, the permeability of the producer strain. beta-Lactamases sometimes cause obvious resistance to substrate drugs in routine tests; often, however, these enzymes reduce susceptibility without causing resistance at current, pharmacologically chosen breakpoints. This review considers the ability of the prevalent beta-lactamases to cause resistance to widely used beta-lactams, whether resistance is accurately reflected in routine tests, and the extent to which the antibiogram for an organism can be used to predict the type of beta-lactamase that it produces. | Laccase is an enzyme that is used for fabricating cathodes of biofuel cells. Many studies have been aimed at searching the ways for enhancing specific electrochemical characteristics of cathode with the laccase- based catalyst. The electroreduction of oxygen on the electrode with immobilized laccase proceeds under the conditions of direct electron transfer between the electrode and active enzyme center. In this work, the effect of oxygen partial pressure on the electrocatalytic activity of laccase is studied. It is shown that, at the concentrations of oxygen dissolved in the electrolyte higher than 0.28 mM, the process is controlled by the kinetics of the formation of laccase–oxygen complex, whereas at lower concentrations and a polarization higher than 0.3 V, the process is limited by the oxygen diffusion. A wide range of carbon materials are studied as the carriers for laccase immobilization: carbon black and nanotubes with various BET specific surface areas. The conditions, which provide the highest surface coverage of carbon material with enzyme in the course of spontaneous adsorptive immobilization and the highest specific characteristics when using a “floating” electrode simulating a gas-diffusion electrode, are determined: 0.2 M phosphate-acetate buffer solution; oxygen atmosphere; the carrier material (nanotubes with a BET surface area of 210 m2/g and a mesopore volume of 3.8 cm3/g); and the composition of active mass on the electrode (50 wt % of carbon material + 50 wt % of hydrophobized carbon black). | eng_Latn | 17,560 |
The discrimination of nucleic acid sequences and the detection of sequence-specific nucleic acid binding events by protein nanopores can be parallelized by optically encoding the ionic flux through the pores. | The connector channel of bacteriophage phi29 DNA packaging motor has been inserted into the lipid bilayer membrane and has shown potential for the sensing of DNA, RNA, chemicals, peptides, and antibodies. Properties such as high solubility and large channel size have made phi29 channel an advantageous system for those applications; however, previously studied lipid membranes have short lifetimes, and they are frangible and unstable under voltages higher than 200 mV. Thus, the application of this lipid membrane platform for clinical applications is challenging. Here we report the insertion of the connector into the stable polymer membrane in MinION flow cell that contains 2048 wells for high-throughput sensing by the liposome-polymer fusion process. The successful insertion of phi29 connector was confirmed by a unique gating phenomenon. Peptide translocation through the inserted phi29 connector was also observed, revealing the potential of applying phi29 connector for high-throughput peptide sensing. | We describe the methods used in our laboratory for the analysis of single nucleic acid molecules with protein nanopores. The technical section is preceded by a review of the variety of experiments that can be done with protein nanopores. The end goal of much of this work is single-molecule DNA sequencing, although sequencing is not discussed explicitly here. The technical section covers the equipment required for nucleic acid analysis, the preparation and storage of the necessary materials, and aspects of signal processing and data analysis. | eng_Latn | 17,561 |
Surface modification and functionalization of nanomaterials have been adopted widely in devising smart drug delivery systems. This work examines the fabrication of multi-stimuli responsive surfaces on mesoporous silica nanoparticles (MSN) for environmentally sensitive site specific drug delivery with reduced risk of premature drug leakage. Chitosan cross-linked via disulfide bonds was applied to form a thin film on drug-loaded MSN, realizing a capsulation and stimuli-sensitive regulating gate membrane; that was further conjugated with folate for site specific targeting toward cancer cells. The chitosan thin film was very stable under neutral conditions and could effectively prevent drug leakage, but was sensitive to both pH and GSH stimulations to reach rapid drug release. Thus, drug release could be triggered by changes in such factors that are common to cancer cells. However, complete and accelerated release could only be realized when triggered simultaneously by both acidic pH and GSH. Moreover, tests with HepG-2 cells confirmed that folate-receptor mediated endocytosis successfully enhanced the cellular uptake of the nanoparticle and antitumor activity toward cancer cells. It is expected that this surface chemical modification strategy promises a powerful approach constructing smart drug delivery systems for efficient and safe chemotherapy. | Hepatocellular carcinoma (HCC) is one of the most prevalent and lethal solid cancers globally. To improve diagnosis sensitivities and treatment efficacies, the development of new theranostic nanoplatforms for efficient HCC management is urgently needed. In the past decade, mesoporous silica nanoparticles (MSNs) with tailored structure, large surface area, high agents loading volume, abundant chemistry functionality, acceptable biocompatibility have received more and more attention in HCC theranostic. This review outlines the recent advances in MSNs-based systems for HCC therapy and diagnosis. The multifunctional hybrid nanostructures that have both of therapy and diagnosis abilities are highlighted. And the precision delivery strategies of MSNs in HCC are also discussed. Final, we conclude with our personal perspectives on the future development and challenges of MSNs. | 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 | 17,562 |
Use of cationic polymers as nonviral gene vectors has several limitations such as low transfection efficiency, high toxicity, and inactivation by serum. In this study, varying amounts of low molecular weight branched polyethylenimine 1.8 kDa (bPEI 1.8) were introduced on to a neutral polymer, poly(vinyl alcohol) (PVA), to bring in cationic charge on the resulting PVA-PEI (PP) nanocomposites. We rationalized that by introducing bPEI 1.8, buffering and condensation properties of the proposed nanocomposites would result in improved gene transfer capability. A series of PVA-PEI (PP) nanocomposites was synthesized using well-established epoxide chemistry and characterized by IR and NMR. Particle size of the PP/DNA complexes ranged between 120 to 135 nm, as determined by dynamic light scattering (DLS), and DNA retardation assay revealed efficient binding capability of PP nanocomposites to negatively charged nucleic acids. In vitro transfection of PP/DNA complexes in HEK293, HeLa, and CHO cells revealed that the... | Development of efficient and safe nucleic acid carriers is one of the most challenging requirements to improve the success of gene therapy. Here, we synthesized a linker, 3-(hexadecyloxy)-1-chloropropan-2-ol, and grafted it onto linear polyethylenimine in varying amounts to obtain a series of HD-lPEI polymers that were able to form self-assembled nanoparticles (SN). 1H-NMR spectrometry was used to determine the extent of grafting of the linker, HD, on to the lPEI backbone. We further complexed the SN of HD-lPEI with plasmid DNA (pDNA) and the resultant nanoplexes were characterized by their size and zeta potential and further evaluated for their transfection ability and cytotoxicity in MCF-7 cells. In the series, the SN of HD-lPEI-3 (ca. 15% substitution) showed the highest transfection efficiency (~ 91%) with non-significant cytotoxicity in comparison to the commercial transfection reagents. The in vitro gene knockdown study displayed ~ 80% suppression of GFP gene expression by SN of HD-lPEI-3/pDNA/siRNA complex, whereas Lipofectamine™/pDNA/siRNA complex could suppress the expression by only ~ 48%. The enhanced expression of luciferase gene using SN of HD-lPEI-3 in different vital organs of Balb/c mice also demonstrated the potential of the projected formulation for gene delivery. The encouraging results of SN of HD-lPEI-3 polymer for delivery of nucleic acids in vitro and in vivo paved the way to evaluate the potential of the same for neuronal siRNA delivery. The safe and efficient stereotaxic delivery of FITC-labeled siRNA against α-synuclein gene also confirms the potential applicability of HD-lEPI-3 SN as a vector for neuronal delivery. | The article describes a simple and rapid method for colorimetric detection of bacteria. It is based on competitive binding of positively charged polyethyleneimine-coated gold nanoparticles (PEI-AuNPs) to negatively charged enzymes and bacteria. The PEI-AuNPs are electrostatically attracted by both the bacterial surface and the enzyme β-galactosidase (β-Gal). Binding to the latter results in the inhibition of enzyme activity. However, in the presence of a large number of bacteria, the PEI-AuNPs preferentially bind to bacteria. Hence, the enzyme will not be inhibited and its activity can be colorimetrically determined via hydrolysis of the chromogenic substrate chlorophenol red β-D-galactopyranoside (CPRG). The detection limit of this assay is as low as 10 cfu·mL−1, and the linear range extends from 106 to 108 cfu·mL−1. The assay is applicable to both Gram-negative (such as enterotoxigenic Escherichia coli; ETEC) and Gram-positive (Staphylococcus aureus; S. aureus) bacteria. Results are obtained within 10 min using an optical reader, and within 2–3 h by bare-eye detection. The method was applied to the identification of ETEC contamination at a level of 10 cfu·mL−1 in spiked drinking water. Given its low detection limit and rapidity (sample preconcentration is not required), this method holds great promise for on-site detection of total bacterial contamination. | eng_Latn | 17,563 |
Starting with Co-salt-loaded inverse micelles, which form if the diblock copolymer polystyrene-block-poly(2-vinylpyridine) is dissolved in a selective solvent like toluene and CoCl2 is added to the solution, monomicellar arrays of such micelles exhibiting a significant hexagonal order can be prepared on top of various substrates with tailored intermicellar distances and structure heights. In order to remove the polymer matrix and to finally obtain arrays of pure Co nanoparticles, the micelles are first exposed to an oxygen plasma, followed by a treatment in a hydrogen plasma. Applying in-situ X-ray photoelectron spectroscopy, it is demonstrated that: 1) The oxygen plasma completely removes the polymer, though conserving the original order of the micellar array. Furthermore, the resulting nanoparticles are entirely oxidized with a chemical shift of the Co 2p3/2 line pointing to the formation of Co3O4. 2) By the subsequent hydrogen plasma treatment the nanoparticles are fully reduced to metallic Co. 3) By exposing the pure Co nanoparticles for 100 s to various oxygen partial pressures p, a stepwise oxidation is observed with a still metallic Co core surrounded by an oxide shell. The data allow the extraction of the thickness of the oxide shell as a function of the total exposure to oxygen (p × time), thus giving the opportunity to control the ferromagnetic–antiferromagnetic composition of an exchange-biased magnetic system. | Patterning metallic nanoparticles on substrate surfaces is important in a number of applications. However, it remains challenging to fabricate such patterned nanoparticles with easily controlled structural parameters, including particle sizes and densities, from simple methods. We report on a new route to directly pattern pre-formed gold nanoparticles with different diameters on block copolymer micellar monolayers coated on silicon substrates. Due to the synergetic effect of complexation and electrostatic interactions between the micellar cores and the gold particles, incubating the copolymer-coated silicon in a gold nanoparticles suspension leads to a monolayer of gold particles attached on the coated silicon. The intermediate micellar film was then removed using oxygen plasma treatment, allowing the direct contact of the gold particles with the Si substrate. We further demonstrate that the gold nanoparticles can serve as catalysts for the localized etching of the silicon substrate, resulting in nanoporous Si with a top layer of straight pores. | was associated with an expansion of the lysosomal compartment and an increase in a subpopulation of lysosomes with increased size and density. Moreover, the decreased mitochondrial Cbl that was associated with lysosomal Cbl trapping was correlated with decreased incorporation of [ 14 C] propionate into cellular proteins/macromolecules, indicating an inhibition of Cbl-dependent Mm-CoA (methylmalonyl-coenzyme A) mutase activity. These results add support to the idea that lysosomal dysfunction may significantly impact upon Cbl transport and utilization. | eng_Latn | 17,564 |
The ability to use proteins in nonnatural environments greatly expands their potential applications in biotechnology. Because nature has not paid much attention to optimizing proteins for in vitro applications under conditions that differ substantially from their natural surroundings, there is generally room for improvement through alterations in the amino acid sequence. The most effective approach to this protein engineering task depends on the level to which the molecular basis for the desired property is understood. Consistently successful "rational" design using site-directed mutagenesis requires a high level of understanding of structure and mechanisms or, alternatively, a particularly simple strategy for obtaining the desired feature. An example of a generally applicable and easy-to-implement protein stabilization strategy is metal ion chelation by specific surface dihistidine sites, which can affect thermal stability as well as the protein's ability to withstand denaturants such as guanidinium chloride. Random mutagenesis, on the other hand, can be effective even when structure or mechanisms are poorly understood, provided one can conveniently screen or select for the property of interest. This approach is illustrated by the sequential accumulation of random mutations that greatly enhance the catalytic activity of a serine protease, subtilisin E, in polar organic solvents. The random mutagenesis approach, which mimics the natural evolutionary refinement process, can be used to "coax" enzymes into tolerating nonnatural environments. | The stabilization of proteins is discussed from the theoretical and practical points of view. Methods are described for kinetic stabilization and protection from deterioration, as well as the thermodynamic stabilization of proteins. | We report enhancement of the mechanical stability of graphene through a one-step method to disperse gold nanoparticles on the pristine graphene without any added agent. | eng_Latn | 17,565 |
Photopheresis, initially established as an effective treatment of cutaneous T-cell lymphoma, has in recent years also been used to treat chronic graft vs. host disease, heart transplant rejection, and several other conditions requiring immunosuppression. Despite reported beneficial results of this procedure in treatment of various conditions, randomized controlled clinical trials are lacking for the majority of suggested indications. Furthermore, the mechanisms of action of this procedure are still unclear. Deeper understanding of the molecular basis of photopheresis-based immunomodulation will allow better selection of patients to be treated and will facilitate development of novel, minimally toxic immunomodulatory treatments. Am. J. Hematol., 2008. © 2008 Wiley-Liss, Inc. | Background ::: CD93 is a cell surface glycoprotein that is required for efficient engulfment of apoptotic cells via an unknown mechanism. Recently, it was demonstrated that CD93 is proteolytically cleaved from the surface of activated human monocytes and neutrophils in response to inflammatory signals in vitro and that a soluble form of CD93 (sCD93) exists in human plasma. | Nanoscale science and technology is today mainly focused on the fabrication of nanodevices. Our approach makes use of lithography processes to build the desired nanostructures directly. The fabrication process involves an electron-beam lithography technique to define metallic microstructures onto which nanometre scale patterning is performed using an atomic force microscope (AFM) as a mechanical modification tool. Both direct material removal and AFM-assisted mask patterning are applied in order to achieve the smallest possible separation between electrode pairs. The sample preparation involves a polymer deposition process that results in conformal growth and in surface roughness comparable to that of the substrate. The results of the application of this technique show that the process is reproducible and exhibits a good operation control during the lithographic steps, both ensured by the imaging facilities of the AFM. The nanolithography technique has been used to fabricate nanogap electrodes to be used for molecular devices. The study reported here can be considered as a reliable starting point for the development of more complex nanodevices, such as single-electron transistors. | eng_Latn | 17,566 |
We report on a versatile strategy to fabricate shape-controlled polymeric nano-objects with an internal compartmentalized structure by replication from pore-diameter-modulated and interconnected nanoporous anodized aluminum oxide (AAO). The AAO with modulated pore diameters is synthesized in a refined temperature-modulated hard anodization (TMHA) approach, by alternating the flow rate of an air stream cooling the electrolyte. Through pore-widening of the templates with modulated pore diameters, a stable interconnected 3D network with transversal ellipsoidal holes is fabricated as a second template structure. From these unprecedented template structures exhibiting modulated pores and an intricate 3D network structure, shape-controlled polymeric nano-objects are replicated using the melt wetting method with polystyrene homopolymer (PS) and cylinder-forming block copolymer polystyrene-block-polydimethylsiloxane (PS298-b-PDMS195). The replicated nanostructures are separated into individual anisotropically sha... | Combining 1D metal nanotubes and nanowires into cross-linked 2D and 3D architectures represents an attractive design strategy for creating tailored unsupported catalysts. Such materials complement the functionality and high surface area of the nanoscale building blocks with the stability, continuous conduction pathways, efficient mass transfer, and convenient handling of a free-standing, interconnected, open-porous superstructure. This review summarizes synthetic approaches toward metal nano-networks of varying dimensionality, including the assembly of colloidal 1D nanostructures, the buildup of nanofibrous networks by electrospinning, and direct, template-assisted deposition methods. It is outlined how the nanostructure, porosity, network architecture, and composition of such materials can be tuned by the fabrication conditions and additional processing steps. Finally, it is shown how these synthetic tools can be employed for designing and optimizing self-supported metal nano-networks for application in electrocatalysis and related fields. | The oxidative polymorphism of debrisoquine (DBQ) has been determined in 89 patients with colo-rectal cancer and in 556 normal control subjects. Four patients and 34 controls, with a metabolic ratio >12.6, were classified as poor metabolisers of DBQ (n.s.). | eng_Latn | 17,567 |
Background : Two complementary approaches to studying the cellular function of proteins involve alteration of function either by mutating protein-encoding genes or by binding a small molecule to the protein. A mutagen can generate millions of genetic mutations; correspondingly, split-pool synthesis can generate millions of unique ligands attached to individual beads. Genetic screening of mutations is relatively straightforward but, in contrast, split-pool synthesis presents a challenge to current methods of screening for compounds that alter protein function. The methods used to screen natural products are not feasible for large libraries composed of covalently immobilized compounds on synthesis beads. The sheer number of compounds synthesized by split-pool synthesis, and the small quantity of individual compound attached to each bead require assay miniaturization for efficient screening. Results : We present a miniaturized cell-based technique for the screening of ligands prepared by split-pool synthesis. Spatially defined droplets with uniform volumes of approximately 50–150 nanoliters (depending on well dimensions) are arrayed on plastic devices prepared using a combination of photolithography and polymer molding. Using this microtechnology, approximately 6,500 assays using either yeast cells or mammalian tissue culture can be performed within the dimensions of a standard 10 cm petri dish. We demonstrate that the biological effect of a small molecule prepared by split-pool synthesis can be detected in this format following its photorelease from a bead. Conclusions : The miniaturized format described here allows uniformly sized nanodroplets to be arrayed on plastic devices. The design is amenable to a large number of biological assays and the spatially arrayed format ensures uniform and controlled ligand concentrations and should facilitate automation of assays. The screening method presented here provides an efficient means of rapidly screening large numbers of ligands made by split-pool synthesis in both yeast and mammalian cells. | Biological systems are highly complex. To analyze the intricate workings of biological systems in an affordable and timely manner, a number of technologies have been developed to analyze biological systems in a highly parallel manner. Of these tools, micro- and nanoscale technologies have emerged as an effective tool because they can be used to automate, miniaturize, and multiplex biochemical assays to study biological functions at the cellular and genomic level at reduced experimentation costs. Herein, we provide a broad overview of several micro- and nanoscale technologies, as well as discuss their current and future applications. Our review primarily focuses on the microarray technologies and their applications to platforms such as DNA, cell, and protein arrays. We also provide a brief description of micro- and nanopatterning of substrates and scaffolds, and their effect on stem cell differentiation and cellular co-cultures. Additionally, augmentation of the microarray technology via integration with microfluidic technologies; and the application of microarrays as biochemical detection platforms are also discussed. Wherever appropriate, current limitations, suitable alternatives, and directions for future research have also been presented. | 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 | 17,568 |
A non-metallic conveyor component is provided. The conveyor component includes an inner race and an outer race. The inner race includes an outer bearing surface. The outer race includes and inner bearing surface. One of the outer and inner bearing surfaces includes a helical groove. The inner and outer races are made from a polymeric matrix material having an alloying additive. | It is urgent to filter invalid or even hostile information in web information systems. A configurable rule engine is designed to solve the problem of simpleness and low self-adaptive ability of rule matching method in traditional information filtering algorithm. In the engine, functions are dynamically called by using reflect mechanism to achieve computing of atom rules, logic rules are described in XML file and transferred to AND/OR tree, AND/OR tree is transferred to 0-1 Matrix, efficient reasoning of logic rules is achieved by combining with AND/OR switching principle, and atom rules base and logic rule base are also configured. Finally, the conceptual model and design model for the rule engine are given, the rule engine is running by classifying and definition of lifecycle. | Cancer theranostics is one of the most important approaches for detecting and treating patients at an early stage. To develop such a technique, accurate detection, specific targeting, and controlled delivery are the key components. Various kinds of nanoparticles have been proposed and demonstrated as potential nanovehicles for cancer theranostics. Among them, polymer-like dendrimers and copolymer-based core-shell nanoparticles could potentially be the best possible choices. At present, magnetic resonance imaging (MRI) is widely used for clinical purposes and is generally considered the most convenient and noninvasive imaging modality. Superparamagnetic iron oxide (SPIO) and gadolinium (Gd)-based dendrimers are the major nanostructures that are currently being investigated as nanovehicles for cancer theranostics using MRI. These structures are capable of specific targeting of tumors as well as controlled drug or gene delivery to tumor sites using pH, temperature, or alternating magnetic field (AMF)-controlled mechanisms. Recently, Gd-based pseudo-porous polymer-dendrimer supramolecular nanoparticles have shown 4-fold higher T1 relaxivity along with highly efficient AMF-guided drug release properties. Core-shell copolymer-based nanovehicles are an equally attractive alternative for designing contrast agents and for delivering anti-cancer drugs. Various copolymer materials could be used as core and shell components to provide biostability, modifiable surface properties, and even adjustable imaging contrast enhancement. Recent advances and challenges in MRI cancer theranostics using dendrimer- and copolymer-based nanovehicles have been summarized in this review article, along with new unpublished research results from our laboratories. | eng_Latn | 17,569 |
Ruthenium olefin metathesis catalysts bearing a polar quaternary ammonium group in N-heterocyclic ligand were immobilized on silica and siliceous mesoporous molecular sieves with different pore sizes (SBA-15 and MCM-41). The activity of the heterogeneous catalysts was found to increase with an increase in pore size of the support used, with the best results observed for SBA-15-supported catalyst. The influence of reaction conditions (temperature, solvent, catalyst, and substrate concentration) on the efficiency of new heterogeneous catalysts was established. A significant influence of the counterion present in the ruthenium complex on the activity of immobilized catalysts was also found: those derived from chloride containing ion exhibited the highest activity. High activity in ring-closing metathesis of substrates as citronellene, 1,7-octadiene, and diallyl compounds as well as in cross-metathesis of unsaturated aliphatic compounds with methyl acrylate was observed under optimized conditions. In some cas... | As structure-directing agents, the molecular structure of surfactants is critical for determining the properties of prepared mesoporous materials. Using dehydroabietic acid as a starting material, a series of rosin-based Gemini surfactants (abbreviated as R-n-R, n = 3, 6, 8 and 10, indicating the carbon atom number contained in the spacer) were synthesized and applied as templates in the preparation of ordered mesoporous silica. The structures and morphologies of the samples were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope and N2 adsorption–desorption. The R-n-R surfactants feature rigid tricyclic hydrophobic groups with large volumes, which are beneficial for the formation of a three-dimensional cubic phase. Furthermore, the spacer length was found to have a tremendous effect on the structure of the prepared mesoporous silica materials. The head group of R-3-R, which has a short spacer, is excessively charged, leading to silica nanoparticles with an irregular morphology and a rather low BET surface area. With longer spacer lengths, R-6-R, R-8-R and R-10-R are conducive to generating silica nanoparticles with a novel dumbbell-like morphology and with higher BET surface areas of 1171, 1096 and 1186 m2 g−1, respectively. The results demonstrate the particularities of the Gemini surfactant structure in the preparation of mesoporous silica nanoparticles with novel morphologies, and the details of the molecular interactions that occur in the condensation of silicate anions are also revealed. | 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 | 17,570 |
Intracellular delivery of exogenous proteins is a field of bioscience that has grown rapidly in recent years, driven by the potential clinical applications. We developed a protein nanocarrier composed of amphiphilic polysaccharide nanogels formed by self-assembly of ethylenediamine- and cholesteryl group-bearing pullulan (CHP-NH2). The nanogel strongly interacts with cells allowing proteins to be internalized more effectively than with other carriers, such as cationic liposomes and a protein transduction domain-based amphiphilic peptide carrier. An interesting property of nanogels is that they can form a stable complex with proteins that are suitably sized suitable for intracellular uptake (~50 nm). Nanogels also act as artificial chaperones by preventing the aggregation of denatured protein and aid correct protein refolding. We also developed a cell-specific peptide (Arg-Gly-Asp; RGD)-modified nanogel (CHP-RGD) with greater potential for cell-specific, receptor-mediated delivery. This nanogel was effectively internalized into cells via integrin-mediated endocytosis, specifically clathrin-mediated endocytosis and macropinocytosis. Cell-specific peptide-modified polysaccharide nanogels are expected to have broad applications in drug delivery. In this chapter, we describe the results of recent studies and discuss future challenges for protein delivery using polysaccharide nanogels. | Polymer nano-sized hydrogels (nanogels) as drug delivery carriers have been investigated over the last few decades. Pullulan, a nontoxic and nonimmunogenic hydrophilic polysaccharide derived from fermentation of black yeast like Aureobasidium pullulans with great biocompatibility and biodegradability, is one of the most attractive carriers for drug delivery systems. In this review, we describe the preparation, characterization, and ‘switch-on/off’ mechanism of typical pullulan self-assembled nanogels (self-nanogels), and then introduce the development of hybrid hydrogels that are numerous resources applied for regenerative medicine. A major section is used for biomedical applications of different nanogel systems based on modified pullulan, which exert smart stimuli-responses at ambient conditions such as charge, pH, temperature, light, and redox. Pullulan self-nanogels have found increasingly extensive application in protein delivery, tissue engineering, vaccine development, cancer therapy, and bi... | 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 | 17,571 |
Mesoporous silica nanoparticles (MSN) and hollow mesoporous silica nanoparticles (HMSN) of the size of ∼200 nm have been synthesized from iron silicate via selective etching of iron oxide and were used to deliver a prominent anticancer drug doxorubicin under external stimuli. The facile synthesis of MSN and HMSN involves synthesis of iron silicate coated by iron oxide and silica in a layer by layer (LbL) fashion followed by selective etching of iron oxide under mild conation. Among all the particles, HMSN has less surface area (100 m 2 /g) and larger pore size (4.62 nm). We demonstrated that both MSN and HMSN release the drug over a period of 4 h under external stimuli (acidic pH). The release profile reveals that HMSN release comparatively less amount of drug as compared to MSN. This could be attributed to the larger pore volume (0.52 cc/g) of MSN as compared to HMSN (0.20 cc/g). The particles neither show any cytotoxicity towards the HeLa cells up to 350 μg/ml nor any morphological change to the nucleus of the cells. The cytotoxicity value was much higher compared to the literature reports on MSN. This implies a better biocompatibility of the particles prepared through this methodology. | Functionality in nanoengineered materials has been usually explored on structural and chemical compositional aspects of matter that exist in such solid materials. It is well known that the absence ... | Different approaches have been considered for the development of smart anticorrosive coatings by the incorporation of nanocontainers loaded with corrosion inhibitors into the protective layer. Nanocontainers are designed to allow a controlled release of the inhibitor in response to an external stimulus, thus, achieving more efficient and more economical use of the active component. In this case, a pH change is a very interesting stimulus to trigger the release because corrosion processes cause local pH changes. To this end, a special focus has been placed on the use of mesoporous silica nanoparticles (MSN) as nanocontainers due to their interesting characteristics, such as larger surface area, versatile functionalisation, stability, etc. However, the use of hollow mesoporous silica nanoparticles (HMSN), with a large central hole combined with an external mesoporous silica shell, offers an additional advantage due to the higher loading capacity. In the present work, HMSN have been efficiently synthesised, loaded with sodium phosphomolybdate, as a non-toxic alternative to the use of chromates, and encapsulated by a layer of an oppositely charged polyelectrolyte, poly(diallyldimethylammonium chloride) (PDDA). The morphology and textural properties of the produced nanocapsules have been studied by different techniques (SEM/EDS, TEM/EDS, Brunauer–Emmett–Teller (BET) analysis method, ζ-potential). Finally, the releasing capacity and corrosion protection at different pH values have been studied, confirming the smart behaviour of the encapsulated loaded HMSN. | eng_Latn | 17,572 |
Quantitative Structure-Affinity Relationships of Dopamine D2 Receptor Antagonists: A Comparison between Orthopramides and 6-Methoxysalicylamides | A large series of orthopramides (= 2-methoxybenzamides), 6-methoxysalicylamides, and 2,6-dimethoxybenzamides were examined for their affinity to the dopamine D2 receptor. The binding data were correlated with physicochemical parameters and C-13-NMR chemical shifts using the cross-validated partial least-squares method and multiple linear regression analysis. The results quantitate the influence of electronic factors and lipophilicity to D2 receptor binding. They also show that the N-[(1-ethylpyrrolidin-2-yl)methyl] and N-(1-benzylpiperidin-4-yl) side-chains affect the mode of binding of these compounds | A simple, inexpensive approach is proposed for enhancing the durability of automotive proton exchange membrane fuel cells by selective promotion of the hydrogen oxidation reaction (HOR) and suppression of the oxygen reduction reaction (ORR) at the anode in startup/shutdown events. Dodecanethiol forms a self-assembled monolayer (SAM) on the surface of Pt particles, thus decreasing the number of Pt ensemble sites. Interestingly, by controlling the dodecanethiol concentration during SAM formation, the number of ensemble sites can be precisely optimized such that it is sufficient for the HOR but insufficient for the ORR. Thus, a Pt surface with an SAM of dodecanethiol clearly effects HOR-selective electrocatalysis. Clear HOR selectivity is demonstrated in unit cell tests with the actual membrane electrode assembly, as well as in an electrochemical three-electrode setup with a thin-film rotating disk electrode configuration. | eng_Latn | 17,573 |
[Various properties of urease encapsulated into liposomes]. | The enzymic activity of plant urease encapsulated into liposomes from egg lecithin was studied. Liposomes contained 3-5% of the initial enzymic preparation. Incorporation of urease into liposomes increases the permeability of the lecithin membrane for urea. The liposome membrane provides protection of the incorporated material from the inhibitory action of heavy metal ions. Kinetics of the reactions catalyzed by the free enzyme and encapsulated one is different. Km for the encapsulated enzyme is 1 X 10(-3) M and for free urease--4 X 10(-4) M, that is related to limited substrate mass transfer rate and as a result of it due to inhomogeneity of the catalysis proceeding in liposomes. | Drug delivery device implantable in the drug contained in the housing and drug reservoir lumen having a drug reservoir lumen, which is closed surrounded by the first wall structure and a hydrophilic second wall structure wherein, here, the first wall structure is impervious to the drug, and the second wall structure is permeable to the drug. Method of providing drug in controlled release to the patient may place the drug delivery device to the patient, to release the drug from the drug reservoir lumen via diffusion through the second wall structure including. .FIELD 8A | eng_Latn | 17,574 |
The Preliminary Study of Machinability during Milling of Titanium Alloy (Ti-6Al-4V) | Titanium and its alloys have found wide application in the aerospace, biomedical and automotive industries owing to their good strength-to weight ratio and high corrosion resistance. However, these alloys have very poor machinability, which is attributed to their inherent high strength maintained at elevated temperature and low thermal conductivity leading to high cutting temperatures. This paper presents the findings of an experimental investigation into the effects of cutting speed, feed rate and depth of cut when milling titanium alloy Ti-6Al-4V. The cutting forces were the response variables investigated. This experimental investigation is translated into a mathematical model of cutting forces designed on the basis of the results obtained from this research. | Single-cell encapsulation promises the cytoprotection of the encased cells against lethal stressors, reminiscent of the sporulation process in nature. However, the development of a cytocompatible method for chemically mimicking the germination process (i.e., shell degradation on-demand) has been elusive, despite the shell degradation being pivotal for the practical use of functional cells as well as for single cell-based biology. We report that an artificial shell, composed of tannic acid (TA) and FeIII, on individual Saccharomyces cerevisiae controllably degrades on-demand, while protecting the yeast from multiple external aggressors, including UV-C irradiation, lytic enzymes, and silver nanoparticles. Cell division is suppressed by the TA–FeIII shell, but restored fully upon shell degradation. The formation of a TA–FeIII shell would provide a versatile tool for achieving the chemical version of “sporulation and germination”. | eng_Latn | 17,575 |
EXPERIMENTAL STUDIES ON SINTERING WITH HIGH-FERRUM AND LOW-SILICON VANADIUM TITANIUM MAGNETITE | The variational trend of agglomerate intensity after enhancing ferrum and reducing silicon in vanadium titanium magnetite and the measures of improving intensity at the condition of high-ferrum and low-silicon have been studied. | Single-cell encapsulation promises the cytoprotection of the encased cells against lethal stressors, reminiscent of the sporulation process in nature. However, the development of a cytocompatible method for chemically mimicking the germination process (i.e., shell degradation on-demand) has been elusive, despite the shell degradation being pivotal for the practical use of functional cells as well as for single cell-based biology. We report that an artificial shell, composed of tannic acid (TA) and FeIII, on individual Saccharomyces cerevisiae controllably degrades on-demand, while protecting the yeast from multiple external aggressors, including UV-C irradiation, lytic enzymes, and silver nanoparticles. Cell division is suppressed by the TA–FeIII shell, but restored fully upon shell degradation. The formation of a TA–FeIII shell would provide a versatile tool for achieving the chemical version of “sporulation and germination”. | yue_Hant | 17,576 |
Isoelectric focusing--a new approach to the study of immune complexes. | Isoelectric focusing was used to examine antigen-antibody complexes. BSA : anti-BSA complexes were dissociated and antigen was separated from antibody based upon differences in pI value by isoelectric focusing (pH gradient 3--10). The recovered proteins were homogeneous as determined by immunodiffusion and polyacrylamide gel electrophoresis analyses. The technique was capable of resolving 6.4 microgram of BSA : anti-BSA complexes. More than 90% of the complexes applied to isoelectric focusing gels were dissociated and entered the gels. It was further demonstrated, by the use of complexes containing enzymes (acid phosphatase or alkaline phosphatase), that the dissociated enzymes retained their native pI as well as enzymatic activities. The isoelectric focusing technique, therefore, represents a new and effective approach to the dissociation of antigen-antibody complexes. | Abstract This paper describes an interface method to utilize the hybrid system with fuel cell and battery. The hybrid system has unique advantage to manage energy state between high energy system (fuel cell) and high power system (battery) according to various type ofload. First, the hybrid system is completely modelled and simulated by using Simplorer. The models are sufficiently correct by considering many parameters. Interface method is realized by constructing a DC-DC converter, and experimented under various load conditions. | eng_Latn | 17,577 |
Thermal Shock Induces Host Proteostasis Disruption and Endoplasmic Reticulum Stress in the Model Symbiotic Cnidarian Aiptasia | Coral bleaching has devastating effects on coral survival and reef ecosystem function, but many of the fundamental cellular effects of thermal stress on cnidarian physiology are unclear. We used label-free liquid chromatography–tandem mass spectrometry to compare the effects of rapidly (33.5 °C, 24 h) and gradually (30 and 33.5 °C, 12 days) elevated temperatures on the proteome of the model symbiotic anemone Aiptasia. We identified 2133 proteins in Aiptasia, 136 of which were differentially abundant between treatments. Thermal shock, but not acclimation, resulted in significant abundance changes in 104 proteins, including those involved in protein folding and synthesis, redox homeostasis, and central metabolism. Nineteen abundant structural proteins showed particularly reduced abundance, demonstrating proteostasis disruption and potential protein synthesis inhibition. Heat shock induced antioxidant mechanisms and proteins involved in stabilizing nascent proteins, preventing protein aggregation and degradi... | We report a unique approach in which living cells direct their integration into 3D solid-state nanostructures. Yeast cells deposited on a weakly condensed lipid/silica thin film mesophase actively reconstruct the surface to create a fully 3D bio/nano interface, composed of localized lipid bilayers enveloped by a lipid/silica mesophase, through a self-catalyzed silica condensation process. Remarkably, this integration process selects exclusively for living cells over the corresponding apoptotic cells (those undergoing programmed cell death), via the development of a pH gradient, which catalyzes silica deposition and the formation of a coherent interface between the cell and surrounding silica matrix. Added long-chain lipids or auxiliary nanocomponents are localized within the pH gradient, allowing the development of complex active and accessible bio/nano interfaces not achievable by other synthetic methods. Overall, this approach provides the first demonstration of active cell-directed integration into a n... | eng_Latn | 17,578 |
Light-driven synthesis of hollow platinum nanospheres | Hollow platinum nanospheres that are porous and have uniform shell thickness are prepared by templating platinum growth on polystyrene beads with an adsorbed porphyrin photocatalyst irradiated by visible light. | Abstract Using a simple chemical process, phosphorylcholine has been deposited covalentiy on the surface of a variety of hydroxylated polymers as a stable, monomolecular coating. Our goal was to obtain new biomaterials which, due to the chemical similarity of the modified interfaces to the phospholipid head groups present on the extracellular surfaces of blood cell membranes, should exhibit enhanced haemo- and biocompatibility. Our previous analyses by chemical and spectrophotometric methods indicated that sufficient quantities of phosphorylcholine were deposited on glass and silica surfaces to result in appreciable modification of their interfacial properties. In the present study, we have examined a series of modified hydroxylated substrates by ESCA and demonstrate specific chemical modifications on the molecular surfaces of polymeric substrates. | eng_Latn | 17,579 |
Thiols make for better catalysts: Au nanoparticles supported on functional SBA-15 for catalysis of Ullmann-type homocouplings. | A strategy for arraying small gold nanoparticles on a mesoporous support modified with single-component or mixed self-assembled monolayers is described. The use of mixed surface modifiers allows easy access to a range of surface chemistries and modalities of interaction between nanoparticles and supports. A combination of thiol groups and linear semifluorinated chains effectively stabilized the nanoparticles against aggregation, while preserving their catalytic activity. The thiol-fluorous-supported catalyst was found active in Ullmann-type homocoupling of aryl halides and showed exceptional selectivity in this reaction. | Abstract A short-to-intermediate range order of liquid Al–Cu binary alloys has been studied by X-ray diffraction and the reverse Monte Carlo modeling. The comprehensive analysis of three-dimensional models of the liquid Al–TM (TM = Co, Ni, Cu) binary alloys has been performed by means of Voronoi–Delaunay method. The existence of a prepeak in the S(Q) function of the liquid alloys reached with Al is caused by a specific arrangement of 3d-transition metal atoms in dense packed polytetrahedral clusters. It has been found that the icosahedral short-range order in dense polytetrahedral clusters and chemical short-range order lead to the formation of the medium range order in the investigated melts. | eng_Latn | 17,580 |
Selective hydrogenation of biomass derived substrates using ionic liquid-stabilized ruthenium nanoparticles | Ionic liquid-stabilized ruthenium nanoparticles with an average size between 2–3 nm are very active catalysts for the hydrogenation of biomass derived substrates. Their catalytic performance complements that of classic homogeneous and heterogeneous ruthenium catalysts. | The present invention relates to a novel protein kinase for improved bicyclic heteroaryl derivatives inhibitory activity, pharmaceutically acceptable salts, hydrates and solvates thereof, for the prevention or treatment of abnormal cell growth disease comprising the bicyclic heteroaryl derivatives, their pharmaceutically acceptable salt thereof, a hydrate thereof or a solvate thereof as an active ingredient of a pharmaceutical composition. | eng_Latn | 17,581 |
Collagenolytic cathepsin B and L activity in experimental fibrotic liver and human liver. | To clarify the role of individual collagenolytic cathepsin in hepatic collagen degradation, cathepsin B and L activities were determined in normal and CCl 4 -induced fibrotic liver, together wiht non-collagenolytic cathepsin H. Cathepsin B and L activities increased 1.9- and 2.0-fold, respectively, in the fibrotic liver as compared with the normal liver, and were significantly correlated with hepatic hydroxyproline levels | We report a unique approach in which living cells direct their integration into 3D solid-state nanostructures. Yeast cells deposited on a weakly condensed lipid/silica thin film mesophase actively reconstruct the surface to create a fully 3D bio/nano interface, composed of localized lipid bilayers enveloped by a lipid/silica mesophase, through a self-catalyzed silica condensation process. Remarkably, this integration process selects exclusively for living cells over the corresponding apoptotic cells (those undergoing programmed cell death), via the development of a pH gradient, which catalyzes silica deposition and the formation of a coherent interface between the cell and surrounding silica matrix. Added long-chain lipids or auxiliary nanocomponents are localized within the pH gradient, allowing the development of complex active and accessible bio/nano interfaces not achievable by other synthetic methods. Overall, this approach provides the first demonstration of active cell-directed integration into a n... | eng_Latn | 17,582 |
Analysis of the acid hydrolysis products of monofunctional chemically bonded stationary phases for high-performance liquid chromatography using capillary gas chromatography | Abstract Capillary gas chromatography of the acid hydrolysis products of monochlorosilane packing materials for high-performance liquid chromatography was used to determine the chemical composition of the bonded phases. Packing materials were acid hydrolysed, either with or without an excess of an added silica gel bonded with a different alkyl silane. The dimer products formed were extracted into hexane, and analysed by capillary gas chromatography. Determination of the identity and surface concentrations of both the primary and capping ligands was possible. This method is also valuable for the determination of more complex blended stationary phases consisting of multiple bonded ligand groups. It is suitable for quality control of both the final stationary phases and the silane reagents used in bonding. | Lipases are ubiquitous biocatalysts that catalyze various reactions in organic solvents or in solvent-free systems and are increasingly applied in various industrial fields. In view of the excellent catalytic activities and the huge application potential, more than 20 microbial lipases have been realized in large-scale commercial production. The potential for commercial exploitation of a microbial lipase is determined by its yield, activity, stability and other characteristics. This review will survey the various technical methods that have been developed to enhance yield, activity and stability of microbial lipases from four aspects, including improvements in lipase-producing strains, modification of lipase genes, fermentation engineering of lipases and downstream processing technology of lipase products. | eng_Latn | 17,583 |
Advances in chemical synthesis and application of metal-metalloid amorphous alloy nanoparticulate catalysts | This paper reviews the advances in the chemical synthesis and application of metal-metalloid amorphous alloy nanoparticles consisting of transition metal (M) and metalloid elements (B, P). After a brief introduction on the history of amorphous alloy catalysts, the paper focuses on the properties and characterization of amorphous alloy catalysts, and recent developments in the solution-phase synthesis of amorphous alloy nanoparticles. This paper further outlines the applications of amorphous alloys, with special emphasis on the problems and strategies for the application of amorphous alloy nanoparticles in catalytic reactions. | The invention relates to low-dose tablets obtained by directly compressing microgranules essentially constituted of a neutral support covered by a polymeric layer containing at least one pharmaceutically acceptable polymer and permitting the modified release of active substances in an aqueous medium, to which an active layer containing at least one active substance is applied. The inventive tablets advantageously exhibit a matrix effect similar to that obtained with conventional matrix tablets that depends on the nature of the polymer(s) used for the constitution of the polymeric layer. This matrix effect makes it possible to modify the release profile of the transported active substance based on the type of the polymer used. These tablets are particularly suited for realizing low-dose tablets. The invention also relates to a method for producing these tablets and to the use thereof, particularly for administering active substances in low to very low doses. | eng_Latn | 17,584 |
ChemInform Abstract: Synthesis and in vivo Evaluation of Carbonyl-amide Linkage Based New Benzimidazole Derivatives. | The title compounds (IV) are obtained via Passerini reaction from acetic acid (I), aromatic aldehydes (II), and isocyanide (III). | We report a unique approach in which living cells direct their integration into 3D solid-state nanostructures. Yeast cells deposited on a weakly condensed lipid/silica thin film mesophase actively reconstruct the surface to create a fully 3D bio/nano interface, composed of localized lipid bilayers enveloped by a lipid/silica mesophase, through a self-catalyzed silica condensation process. Remarkably, this integration process selects exclusively for living cells over the corresponding apoptotic cells (those undergoing programmed cell death), via the development of a pH gradient, which catalyzes silica deposition and the formation of a coherent interface between the cell and surrounding silica matrix. Added long-chain lipids or auxiliary nanocomponents are localized within the pH gradient, allowing the development of complex active and accessible bio/nano interfaces not achievable by other synthetic methods. Overall, this approach provides the first demonstration of active cell-directed integration into a n... | eng_Latn | 17,585 |
Structure of liquid tin under high pressure by ab initio molecular-dynamics simulation | Pressure-induced structural change of liquid tin was studied by constant-pressure ab initio molecular-dynamics simulations from 0 to 4 GPa. We have found that with increasing pressure the liquid tin is not compressed uniformly but very gradually changes from complex anisotropic structures to more simple isotropic close-packed structure. | We report a unique approach in which living cells direct their integration into 3D solid-state nanostructures. Yeast cells deposited on a weakly condensed lipid/silica thin film mesophase actively reconstruct the surface to create a fully 3D bio/nano interface, composed of localized lipid bilayers enveloped by a lipid/silica mesophase, through a self-catalyzed silica condensation process. Remarkably, this integration process selects exclusively for living cells over the corresponding apoptotic cells (those undergoing programmed cell death), via the development of a pH gradient, which catalyzes silica deposition and the formation of a coherent interface between the cell and surrounding silica matrix. Added long-chain lipids or auxiliary nanocomponents are localized within the pH gradient, allowing the development of complex active and accessible bio/nano interfaces not achievable by other synthetic methods. Overall, this approach provides the first demonstration of active cell-directed integration into a n... | eng_Latn | 17,586 |
Liquid-phase theoretical antioxidant activity trend of some cinnamic acid antioxidants | The trend in antioxidant activity of four cinnamic acid antioxidants, derived on the basis of their liquid-phase phenolic O H bond dissociation enthalpies, is determined theoretically, with the aid of the polarizable continuum model at the density functional theory level. Three solvents, differing in their hydrogen-bonding ability and polarity—n-heptane, acetonitrile, and ethanol—were used to model different environmental situations. The trends in solution-phase antioxidant activity appeared different in each solvent; still, the theoretical antioxidant activity trend derived in n-heptane was in excellent agreement with the experimental one in the lipid systems and the gas-phase system. Different ortho substituents show notably different solvent effects. These results could lead to the determination of reliable antioxidant activity trends in real-solution environments of interest in food or biological science frameworks. | We report a unique approach in which living cells direct their integration into 3D solid-state nanostructures. Yeast cells deposited on a weakly condensed lipid/silica thin film mesophase actively reconstruct the surface to create a fully 3D bio/nano interface, composed of localized lipid bilayers enveloped by a lipid/silica mesophase, through a self-catalyzed silica condensation process. Remarkably, this integration process selects exclusively for living cells over the corresponding apoptotic cells (those undergoing programmed cell death), via the development of a pH gradient, which catalyzes silica deposition and the formation of a coherent interface between the cell and surrounding silica matrix. Added long-chain lipids or auxiliary nanocomponents are localized within the pH gradient, allowing the development of complex active and accessible bio/nano interfaces not achievable by other synthetic methods. Overall, this approach provides the first demonstration of active cell-directed integration into a n... | eng_Latn | 17,587 |
Yeast gets a solar-powered boost | The simple brewer’s yeast Saccharomyces cerevisiae is one of the most well-characterized microorganisms on the planet. It is used to ferment alcohol, as well as synthesize drugs and feedstock chemicals. Now, researchers have created yeast that can perform another trick: harnessing sunlight. Neel Joshi’s group at Harvard University added semiconductor nanoparticles to the surface of genetically engineered yeast to generate an inorganic, biological, hybrid organism. The yeast grabs electrons, which are produced when light shines on the particles, to drive production of shikimic acid—used to make oseltamivir, sold under the brand name Tamiflu. Joshi tells C&EN that the project was conceived of by two postdocs, Junling Guo and Miguel Suastegui, who have backgrounds in materials science and metabolic engineering, respectively. “They came up with this idea,” Joshi explains, “which initially I didn’t think was going to work.” But he was proved wrong. “It worked beautifully.” The researchers fixed indium phosphide | Accelerator builder Richard York's XFEL vision was already in hand when President Obama called for a US cancer "moonshot." | eng_Latn | 17,588 |
[Production of spheroplasts from Pseudomonas aeruginosa]. | The spheroplasts were prepared from the gram-negative bacterium Pseudomonas aeruginosa IBFM-13 upon incubation with lysozyme, but without EDTA. The following conditions were found to be optimal: 20 percent sucrose; lysozyme, 54 mcg/mg protein of the cells; pH 7.6. The spheroplasts, as well as the cells, have a high rate of malate oxidation, but do not oxidize NADH2, the latter fact suggesting that the cytoplasmic membrane remains intact. | Hollow platinum nanospheres that are porous and have uniform shell thickness are prepared by templating platinum growth on polystyrene beads with an adsorbed porphyrin photocatalyst irradiated by visible light. | eng_Latn | 17,589 |
Design, synthesis, and antiviral activity of novel phosphoramidates | Novel phosphoramidates 8a-b possessing structural features similar to nucleoside phosphonates HPMPA, PMEA, PMEG, and oxathiolane nucleoside BCH189 were synthesized by chemical methods. The designed molecules exhibited significant antiviral activities. We hypothesized that, as a masked membranesoluble form of the potential bioactive compounds 7a-b, phosphoramidates 8a-b may act as a proteinase substrate. Then, the potential drug 7a-b will be liberated inside the infected cells. The triphosphate anabolites of each could act as competitive substrates for the HIV reverse transcriptase and terminate DNA synthesis after being incorporated into the growing DNA strand. Phosphoramidates 8a-b were synthesized as racemates to allow access to both enantiomers. | Hollow platinum nanospheres that are porous and have uniform shell thickness are prepared by templating platinum growth on polystyrene beads with an adsorbed porphyrin photocatalyst irradiated by visible light. | eng_Latn | 17,590 |
First principle study on in-vitro antismicrobial properties of nano 52S4.6 bioactive glass | Abstract The present study was aimed at determining kinetics of inhibition of bacterial growth by 52S4.6 Nano bioactive glass (Nbg) particles prepared via acid hydrolysis mediated sol-gel method using tetraethyl orthosilicate (TEOS), triethyl phosphate (TEP), calcium nitrate tetrahydrate (Ca(NO3)2·4H2O), sodium nitrate (NaNO3) as precursors. Synthesized Nbg powders exhibited a very narrow size distribution of about 1–2 nm primarily because of high zeta potential of about 39 mv with predominating amorphous phase as obtained from XRD data and SAED pattern. Minimum inhibitory concentration of Nbg was determined to be 15 mg/ml for Escherichia coli (E. Coli) and 15–20 mg/ml for Staphylococcus aureus (S. Aureus) respectively, after 72 h of incubation. The inhibition was primarily because of ions released that increased osmolarity, osmotic pressure and the pH of the culture media from 7.2 to 10.1 over the period of 168 h of incubation. | Disclosed is a precursor composition comprising: a compound selected from a compound represented by the formula: Si(OR 1 ) 4 and a compound represented by the formula R a (Si)(OR 2 ) 4-a (in the formulas R 1 represents a monovalent organic group; R represents a hydrogen atom, a fluorine atom or a monovalent organic group; R 2 represents a monovalent organic group; and a is an integer ranging from 1 to 3, provided that R, R 1 and R 2 may be the same or different from one another) a thermally degradable organic compound; an element having a catalyst activity; urea; and the like. A porous thin film produced from the precursor composition is irradiated with ultraviolet ray, and then subjected to gas-phase reaction with a hydrophobic compound. A porous thin film thus prepared can be used for the manufacture of a semiconductor device. | eng_Latn | 17,591 |
Synthesis and characterization of spinel metal aluminate by a simple microwave assisted green synthesis | Abstract In the current research report we present a simple, eco-friendly, cost and time saving biosynthesis of ZnAl 2 O 4 spinel nano and micro particles using Pomegranate peel extract, that act as the reducing as well as stabilizing agent. Thus synthesized products are then consistently characterized under powder X-ray diffraction (PXRD), scanning electron microscopy (SEM). The powder XRD analysis has confirmed their chemical composition. Optical properties including diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and fourier transform infrared spectroscopy (FTIR) are also investigated. The ZnAl 2 O 4 nanoparticles formation is been confirmed by PXRD, FT-IR and SEM. From XRD the calculated crystalline size of the ZnAl2O4 nanoparticles is in the range of 11.2 nm. | Single-cell encapsulation promises the cytoprotection of the encased cells against lethal stressors, reminiscent of the sporulation process in nature. However, the development of a cytocompatible method for chemically mimicking the germination process (i.e., shell degradation on-demand) has been elusive, despite the shell degradation being pivotal for the practical use of functional cells as well as for single cell-based biology. We report that an artificial shell, composed of tannic acid (TA) and FeIII, on individual Saccharomyces cerevisiae controllably degrades on-demand, while protecting the yeast from multiple external aggressors, including UV-C irradiation, lytic enzymes, and silver nanoparticles. Cell division is suppressed by the TA–FeIII shell, but restored fully upon shell degradation. The formation of a TA–FeIII shell would provide a versatile tool for achieving the chemical version of “sporulation and germination”. | eng_Latn | 17,592 |
Size-controlled synthesis of Pd nanomaterials via proton beam irradiation. | We present a facile one-pot synthetic route for the production of palladium nanoparticles via a simple proton beam irradiation process at room temperature. The synthesis of size-controlled palladium nanostructures was realized just by changing the mean current of the proton beam and by controlling the molar concentration ratios of surfactants to Pd precursors in an aqueous phase-based solution without the addition of any harsh reductants. As the beam current was increased under the same Pd ion concentration conditions, the average diameter of the prepared Pd nanoparticles tended to be decreased. We also found that the size of the synthesized Pd nanocrystals was decreased as the molar ratio of surfactants to palladium ion was increased. | Introduction A successful fi rst structure refi nement of lysozyme [1] already proved the value of standard XRPD laboratory instruments for protein structure research. In this contribution we will present new measurements and crystallographic analysis results of insulin and insulin derivatives performed on data from a PANalytical X’Pert PRO diffractometer used in different confi gurations. We additionally demonstrate that even fast measurements on a 96 well plate as used for polymorph screening purposes, result in high quality data, which is suitable for automatic crystallographic analysis like indexing [2] and LeBail [3] fi tting. | eng_Latn | 17,593 |
Modeling and simulation of hydrodemetallation and hydrodesulfurization processes with transient catalytic efficiency | A model is presented for the description of the concentration behavior of organometallic and sulfurated compounds in hydrodemetallation and hydrodesulfurization catalytic processes, where catalyst effectiveness decreases with time. Due to the complexity of the mixture, an approach based on pseudocomponents was adopted. The system is modeled as an isothermal tubular reactor with axial dispersion, where the gas phase (hydrogen in excess) flows upward concurrently with the liquid phase (heavy oil) while the solid phase (catalyst) stays inside the reactor in an expanded (confined) bed regime. The catalyst particles are very small and are assumed to be uniformly distributed in the reactor. The heavy oil fractions contain organometallics and sulfurated compounds, from which the metals and sulfur are to be removed, the metals as deposits in the catalyst pores and the sulfur as gas products. Simulations were carried out where the concentration profile inside the reactor was calculated for several residence times. | The invention relates to a method for manufacturing series silver nano-sheets in a batch. The method includes dividing polyhydric alcohol, dimethyl formamide, high-polymer surfactant, metal salt adjuvant containing halogen and metal silver salt into three batches to be treated by the aid of the metal salt adjuvant containing the halogen; then uniformly mixing the materials; and obtaining the series silver nano-sheets by means of heating reaction. The silver nano-sheets are uniform in shape, high in purity, fine in monodispersity and low in cost, a reaction device is simple, large-scale preparation of the silver nano-sheets can be realized, and the method has an industrial prospect. | eng_Latn | 17,594 |
Terminal assembly for bipolar electrochemical cell or battery | The present invention provides a battery stack comprising a terminal assembly and a terminal assembly, the terminal assembly comprising: an end wall in electrical communication with the terminal when in contact with the terminal of the electrochemical cell; Side walls; And a rim that is separated from the distal wall by the sidewall; And a terminal end plate having first and second surfaces coplanar with the end wall and connected to the rim at the first surface, the connection being such that when the end wall is in contact with the terminal Wherein the end plate includes a first surface area surrounded by the rim and a second surface area outside the outer periphery of the rim, And the first and second surface regions are substantially the same. | The interaction of the negatively-charged phosphatidylserine (PS) and γ-Aminobutyric acid (GABA) is examined in black lipid membranes (BLM) and inverse micelles. | eng_Latn | 17,595 |
Biosynthetic Polymers as Functional Materials | The synthesis of functional polymers encoded with biomolecules has been an extensive area of research for decades. As such, a diverse toolbox of polymerization techniques and bioconjugation methods has been developed. The greatest impact of this work has been in biomedicine and biotechnology, where fully synthetic and naturally derived biomolecules are used cooperatively. Despite significant improvements in biocompatible and functionally diverse polymers, our success in the field is constrained by recognized limitations in polymer architecture control, structural dynamics, and biostabilization. This Perspective discusses the current status of functional biosynthetic polymers and highlights innovative strategies reported within the past five years that have made great strides in overcoming the aforementioned barriers. | The details are presented of SynBioSS, a computational design tool for synthetic biology. In SynBioSS, the user simply inputs the molecular components of a synthetic biological system and the software outputs a reaction network that models the biomolecular interactions of this system. This software assists practitioners with little or no modeling experience in quantitatively describing synthetic biological systems. ::: ::: ::: Keywords: ::: ::: computational synthetic biology; ::: synthetic biology tools; ::: automatic design of synthetic systems; ::: modeling synthetic constructs; ::: modeling genetic circuits | eng_Latn | 17,596 |
Teratogenic effects of parthenogenetic cells from LTXBO mice, a strain which develops ovarian teratomas at high frequency | LTXBO mice develop ovarian teratomas at high frequency. The phenotype of tumour tissues is unusual in that most contain trophoblast elements. Since the tumours are derived from parthenogenetically activated oocytes, they would not be expected to produce trophoblast. The developmental potential of parthenogenetic cells from these mice was tested in aggregation chimeras. No contribution to trophoblast tissues was observed. However, a high incidence of morphological abnormalities was seen, suggesting that the parthenogenetic cells exerted a teratogenic effect. | Here, we demonstrate a new approach to obtain core/shell bismuth telluride/bismuth sulfide nanorods with shell branching by using a biomolecular surfactant, L-glutathionic acid (LGTA). We show that crystallographic twinning of Bi2S3 driven by Bi-LGTA ligand desorption is the primary mechanism of shell branching, which can be controlled by adjusting the LGTA concentration, reaction temperature, and time. Such branched nanostructures and their formation mechanism are different from the nanotetrapod heterostructures of CdSe and CdTe [13‐15] obtained by exploiting lattice mismatch between allotropic polytypes. | eng_Latn | 17,597 |
Synthesis of a series of soluble main-chain chiral nonracemic poly(alkyl-aryl ketone) | A series of main-chain chiral polyketones have been synthesized through condensation polymerization of a dihalide and a diketone with optically pure binaphthyl moiety as linkage in the polymer backbone. The solubility of the polymers can be easily enhanced by substituents at the alpha position next to the carbonyl groups. Reducing the steric hin- drance of the substituents in the monomers increases the reactivity of the polymerization. The chiral polymers exhibit large optical rotations. Circular Dichroism (CD) spectra of the polymers are similar to those of the corresponding monomers. The novel synthetic strategy may have great impact on future development of palladium catalyzed condensation polymeriza- tions. The highly soluble chiral polymers synthesized allow for preparation of materials in the form of thin films and have potentials applications in various areas such as chiral separation and recognition. | A simple, inexpensive approach is proposed for enhancing the durability of automotive proton exchange membrane fuel cells by selective promotion of the hydrogen oxidation reaction (HOR) and suppression of the oxygen reduction reaction (ORR) at the anode in startup/shutdown events. Dodecanethiol forms a self-assembled monolayer (SAM) on the surface of Pt particles, thus decreasing the number of Pt ensemble sites. Interestingly, by controlling the dodecanethiol concentration during SAM formation, the number of ensemble sites can be precisely optimized such that it is sufficient for the HOR but insufficient for the ORR. Thus, a Pt surface with an SAM of dodecanethiol clearly effects HOR-selective electrocatalysis. Clear HOR selectivity is demonstrated in unit cell tests with the actual membrane electrode assembly, as well as in an electrochemical three-electrode setup with a thin-film rotating disk electrode configuration. | eng_Latn | 17,598 |
A kinetic modeling study of NO oxidation over a commercial Cu-CHA SCR catalyst for diesel exhaust aftertreatment | Abstract Based on a redox kinetic mechanism, we derive a rate expression for NO oxidation over Cu-zeolite catalysts, and fit it to a set of NO oxidation experiments carried out over a commercial Cu-zeolite SCR catalyst with chabazite structure. The so developed model is able to predict the complex behavior of the NO oxidation reaction in good agreement with data covering the effects of NO, O 2 , NO 2 and H 2 O feed contents, GHSV and reaction temperature (150–350 °C). We show also that the dependency of the negative kinetic order of NO 2 on the operating temperature is consistent with the proposed mechanism. Since NO oxidation in an NH 3 -SCR converter may affect the overall deNO X activity, the herein presented model is also relevant to characterize and describe the behavior of state-of-the-art SCR catalysts. | The present invention provides an antibody-drug conjugates (ADC) of the cation exchange chromatography purification process, the choice of the cation exchange chromatography in conjunction with - elute mode or purified overload mode, the drug may be conjugated ADC ratio (DAR ) controlling the process in the target range, acts simultaneously remove multimers. This is a new purification process of preparing ADC, reduces production costs and risks, while achieving the ADC molar coupling small molecule drug / antibody ratio (DAR) and the control multimers useful in developing controlled stronger, lower cost and risk of ADC production process, in order to obtain higher quality products, to ensure drug safety and therapeutic effect. | eng_Latn | 17,599 |
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