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Reaction of ubiquinone in the high-affinity quinone-binding site (QH) in bo-type ubiquinol oxidase from Escherichia coli was revealed by EPR and optical studies. In the QH site, ubiquinol was shown to be oxidized to ubisemiquinone and to ubiquinone, while no semiquinone signal was detected in the oxidase isolated from mutant cells that cannot synthesize ubiquinone. The QH site highly stabilized ubisemiquinone radical with a stability constant of 1–4 at pH 8.5 and the stability became lower at the lower pH. Midpoint potential of QH2/Q couple was −2 mV at pH 8.5 and showed −60 mV/pH dependence indicative of 2H+/2e− reaction. The Em was more negative than that of low-spin heme b above pH 7.0. We conclude that the QH mediates intramolecular electron transfer from ubiquinol in the low-affinity quinol oxidation site (QL) to low-spin heme b. Unique roles of the quinone-binding sites in the bacterial ubiquinol oxidase are discussed.
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Under anaerobic conditions and in the presence of nitrate, the facultative anaerobe Escherichia coli synthesises an electron-transport chain comprising a primary dehydrogenase and the terminal membrane-bound nitrate reductase A (NarGHI). This review focuses on recent advances obtained on the structure and function of the three protein subunits of membrane-bound nitrate reductases. We discuss a global architecture for the Mo-bisMGD-containing subunit (NarG) and a coordination model for the four [Fe-S] centres of the electron-transfer subunit (NarH) and for the two b-type haems of the anchor subunit NarI.
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We characterize stability under composition, inversion, and solution of ordinary differential equations for ultradifferentiable classes, and prove that all these stability properties are equivalent.
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eng_Latn
| 31,200 |
A copper-catalyzed aerobic oxidation of benzylpyridine N-oxides is reported. The N-oxide moiety acts as a built-in activator for the benzylic methylene oxidation, without requirement of additives. Reaction conditions were identified which suppress undesired benzoylpyridine formation via N-deoxygenation involving intermolecular oxygen transfer. The versatility of the N-oxide group of the benzoylpyridine N-oxide reaction products for post-functionalization of the pyridine ring is demonstrated through efficient C-C, C-N, C-O and C-Cl bond forming procedures, with both nucleophiles and electrophiles. Finally, the applicability of the new synthetic methodology is demonstrated in an alternative route towards the anti-histaminic drug Acrivastine via three consecutive N-oxide activated C-H functionalization processes, starting from picoline N-oxide.
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An efficient direct C(sp3)⁻H oxidation of diarylmethanes has been demonstrated by this study. This method employs environment-friendly O₂ as an oxidant and is promoted by commercially available MN(SiMe₃)₂ [M = K, Na or Li], which provides a facile method for the synthesis of various diaryl ketones in excellent yields. This protocol is metal-free, mild and compatible with a number of functional groups on substrates.
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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.).
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eng_Latn
| 31,201 |
The copper-free click reaction was explored as a surface functionalization methodology for ZnO nanorod films grown by metal organic chemical vapor deposition (MOCVD). 11-Azidodecanoic acid was bound to ZnO nanorod films through the carboxylic acid moiety, leaving the azide group available for Cu-free click reaction with alkynes. The azide-functionalized layer was reacted with 1-ethynylpyrene, a fluorescent probe, and with alkynated biotin, a small biomolecule. The immobilization of pyrene on the surface was probed by fluorescence spectroscopy, and the immobilization of biotin was confirmed by binding with streptavidin–fluorescein isothiocyanate (streptavidin–FITC). The functionalized ZnO films were characterized by Fourier transform infrared attenuated total reflectance (FTIR–ATR), steady-state fluorescence emission, fluorescence microscopy, and field emission scanning electron microscopy (FESEM).
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Metal organic chemical vapor deposition grown films consisting of MgxZn1-xO (4% < x < 5%) nanorod arrays (MgZnOnano) were functionalized with 11-azidoundecanoic acid (1). The MgZnOnano was used instead of pure ZnO to take advantage of the etching resistance of the MgZnOnano during the binding and subsequent sensing device fabrication processes of sensor devices, while the low Mg composition level ensures that selected ZnO properties useful for sensors development, such as piezoelectricity, are retained. Compound 1 was bound to the MgZnOnano surface through the carboxylic acid group, leaving the azido group available for click chemistry and as a convenient infrared spectroscopy (IR) probe. The progress of the functionalization with 1 was characterized by FTIR microscopic imaging as a function of binding time, solvents employed, and MgZnOnano morphology. Binding of 1 was most stable in solutions of 3-methoxypropionitrile (MPN), a non-protic polar solvent. This occurred first in μm-scale islands, then expanded to form a rather uniform layer after 22 h. Binding in alcohols resulted in less homogenous coverage, but the 1/MgZnOnano films prepared from MPN were stable upon treatment with alcohols at room temperature. The binding behavior was significantly dependent on the surface morphology of MgZnOnano. Graphical abstract The functionalization of MgZnO nanorod films with a click-ready linker and its dependence on bidning conditions and morphology has been studied by FTIR microscopic imaging using the azido group as the IR tag.
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Radiation hazards in outer space present an enormous challenge for the biological safety of astronauts. A deleterious effect of radiation is the production of reactive oxygen species, which result in damage to biomolecules (e.g., lipid, protein, amino acids, and DNA). Understanding free radical biology is necessary for designing an optimal nutritional countermeasure against space radiation-induced cytotoxicity. Free radicals (e.g., superoxide, nitric oxide, and hydroxyl radicals) and other reactive species (e.g., hydrogen peroxide, peroxynitrite, and hypochlorous acid) are produced in the body, primarily as a result of aerobic metabolism. Antioxidants (e.g., glutathione, arginine, citrulline, taurine, creatine, selenium, zinc, vitamin E, vitamin C, vitamin A, and tea polyphenols) and antioxidant enzymes (e.g., superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidases) exert synergistic actions in scavenging free radicals. There has been growing evidence over the past three decades showing that malnutrition (e.g., dietary deficiencies of protein, selenium, and zinc) or excess of certain nutrients (e.g., iron and vitamin C) gives rise to the oxidation of biomolecules and cell injury. A large body of the literature supports the notion that dietary antioxidants are useful radioprotectors and play an important role in preventing many human diseases (e.g., cancer, atherosclerosis, stroke, rheumatoid arthritis, neurodegeneration, and diabetes). The knowledge of enzymatic and non-enzymatic oxidative defense mechanisms will serve as a guiding principle for establishing the most effective nutrition support to ensure the biological safety of manned space missions.
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eng_Latn
| 31,202 |
Palladium-catalyzed polycondensation between N,N'-dichloro-p-benzoquinone diimines and diorganometallic aromatic compounds provides a new route for the synthesis of polyanilines. A polymer composed of dimethyl-p-benzoquinone diimine and thiophene units has an electrical conductivity of about 1 Scm-1 at room temperature, and the temperature dependence of the electrical conductivity follows a variable-range-hopping-type equation.
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Poly(1,4-benzoquinonediimine-N,N-diyl-1,4-phenylene) having similar structure to pernigraniline was synthesized by chemical oxidative polymerization of p-phenylenediamine and its salt using potassium peroxydisulfate as an oxidant in molar ratio 1:0.8, in acetic acid, at 278 K. Acetylation of amino end groups of polymers were carried out aiming to prevent self-condensation of amino groups with 1,4-benzoquinone diimine groups by 1,4-addition. Attempting to carry out the reduction of obtained polymer with hydrazine hydrate, it was shown that 1,4-addition of hydrazine to quinonediimine groups occurs instead of expected reduction reaction. When doping obtained polymers with iodine, the electrical conductivity increases up to 10−4 S/cm.
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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.).
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eng_Latn
| 31,203 |
A gas chromatographic analysis for vinyl acetate is presented. Vinyl acetate was sampled by adsorbing on activated carbon. It was desorbed with carbon disulfide with a mean efficiency of 83.0%. The analytical column was packed with 10% free fatty acid phase on acid-washed Chromosorb-P. Gas chromatographic identification was also conducted on another column packed with 0.4% Carbowax-1500 on Carbopack A. Analysis was performed on a chromatograph equipped with a flame ionization detector. The precision (coefficient of variation) for the analytical procedure using a free fatty acid phase column was 4.0%. Based on a 10 litre air sample, the calculated limit of detection by this procedure was 0.1 parts per million.
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A gas Chromatographic procedure for the determination of 2-ethoxyethanol (C2H5OCH2CH2OH) was developed by using the general principles of analysis of solvent vapors. 2-Ethoxyethanol was sampled by adsorbing on activated carbon. It was desorbed with carbon disulfide plus 2-propanol (0.5%). The analytical column was packed with 10% free fatty acid phase on Chromosorb-P AW. The analysis was conducted at 130° C isothermal using a flame ionization detector. Addition of 2-propanol (0.5%) to carbon disulfide improved (P≤0.01) desorption of 2-ethoxyethanol adsorbed on activated carbon. The mean desorption efficiency of carbon disulfide plus 2-propanol (0.5%) was 87.9±2.86% (n=15). Based on a 101 air sample and detector sensitivity of 2×10−10AFS, the calculated limit of detection of 2-ethoxyethanol was 0.1 ppm. The precision (coefficient of variation) for this analytical procedure was 3.34% (n=12). In conclusion, 2-ethoxyethanol adsorbed on activated carbon can be desorbed with carbon disulfide plus 2-propanol (0.5%). Subsequently the desorbed 2-ethoxyethanol can be analyzed by gas chromatographic identification on 10% FFAP using a flame ionization detector.
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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.
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eng_Latn
| 31,204 |
Pyrite ( E g =0.95 eV) is being developed as a solar energy material due to its environmental compatibility and its very high light absorption coefficient. A compilationof material, electronic and interfacial chemical properties is presented, which is considered relevant for quantum energy conversion. In spite of intricate problems existing within material chemistry, high quantum efficiencies for photocurrent generation (>90%) and high photovoltages (≈500 mV) have been observed with single crystal electrodes and thin layers respectively. The most interesting aspect of this study is the use of pyrite as an ultrathin (10–20 nm) layer sandwiched between large gap p-type and n-type materials in a p-i-n like structure. Such a system, in which the pyrite layer only acts as photon absorber and mediates injection of excited electrons can be defined as sensitization solar cell. The peculiar electron transfer properties of pyrite interfaces, facilitating interfacial coordination chemical pathways, may turn out to be very helpful. Significant research challenges are discussed in the hope of attracting interest in the development of solar cells from this abundant material.
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Thin films of pyrite (FeS2) were fabricated using synthesized nano-particles and their structural, electrical and optical properties were characterized. Initially, pyrite-nano-particles were synthesized by an aqueous hydrothermal reaction. The X-ray diffraction confirmed that synthesized pyrite had a phase pure cubic pyrite structure with the average grain size around 30.0 nm. The pyrite films were fabricated by vacuum thermal evaporation of pyrite nanoparticles followed by a thermal sulfurization process. The as-deposited films have an amorphous structure and the sulfurized films have a cubic pyrite structure. The optical properties exhibited the bandgap closer to previously reported bandgap of pyrite. The photoconductivity of pyrite films was measured under AM1.5G sunlight and infrared (850 nm) light illumination. The photoconductivity data showed that the sulfurized pyrite films were more photoconductive than the as-deposited films.
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OBJECTIVE ::: To evaluate the association between inhalation exposure to jet propulsion fuel 8 (JP-8) and urinary metabolites among US Air Force (USAF) personnel, and investigate the role of glutathione S-transferase polymorphisms. ::: ::: ::: METHODS ::: Personal air samples were collected from 37 full-time USAF personnel during 4 consecutive workdays and analyzed for JP-8 constituents and total hydrocarbons. Pre- and postshift urine samples were collected each day and analyzed for polycyclic aromatic hydrocarbon urinary metabolites. ::: ::: ::: RESULTS ::: Work shift exposure to total hydrocarbons was significantly associated with postshift urinary 1-naphthol (β = 0.17; P = <0.0001), 2-naphthol (β = 0.09; P = 0.005), and 2-hydroxyfluorene concentrations (β = 0.08; P = 0.006), and a significant gene-environment interaction was observed with glutathione S-transferase mu-1. ::: ::: ::: CONCLUSIONS ::: USAF personnel experience inhalation exposure to JP-8, which is associated with absorption of JP-8 constituents while performing typical job-related tasks, and in our data the glutathione S-transferase mu-1 polymorphism was associated with differential metabolism of naphthalene.
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eng_Latn
| 31,205 |
In this study, the degradation of dimethyl phthalate (DMP), taken as model compound for phthalate esters, by the photo-assisted peroxymonosulfate (PMS) process was investigated. The high oxidation potential of hydroxyl and sulfate radicals generated by the activation of PMS under UV-C light irradiation was used to completely oxidize aqueous DMP solutions. Experiments were conducted at varying initial pH values (3.0, 6.0, and 9.0) and PMS concentrations (0-60 mM) to evaluate the effect of different reaction conditions on DMP treatment performance with the PMS/UV-C process. It was observed that lowering the initial reaction pH slightly improved the degradation rate of DMP. On the contrary, TOC abatements were slightly enhanced with increasing initial reaction pH. An adequate (optimum) PMS concentration of 40 mM resulted in the fastest and highest DMP degradation rates and efficiencies, respectively. At an initial concentration of 100 mg L(-1), more than 95% DMP removal was obtained after only 20 min under PMS/UV-C treatment conditions. For the proposed adequate PMS concentration (40 mM) the lowest electrical energy per order (EE/O) value was calculated as 2.9 kW h m(-3) order(-1).
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Rate constants have been compiled for reactions of various inorganic radicals produced by radiolysis or photolysis, as well as by other chemical means in aqueous solutions. Data are included for the reactions of ⋅CO2 −, ⋅CO3⋅−, O3, ⋅N3, ⋅NH2, ⋅NO2, NO3⋅, ⋅PO32−, PO4⋅2−, SO2⋅ −, ⋅SO3 −, SO4⋅−, ⋅SO5⋅−, ⋅SeO3⋅ −, ⋅(SCN)2⋅ −, ⋅CL2⋅−, ⋅Br2⋅ −, ⋅I2⋅ −, ⋅ClO2⋅, ⋅BrO2⋅, and miscellaneous related radicals, with inorganic and organic compounds.
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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...
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eng_Latn
| 31,206 |
Based on kinetic evidence, it has been shown for the first time that the mode of binding of aromatic donor molecules is similar in horseradish peroxidase and lactoperoxidase; also that the nature of the heme plays an important role in the reaction with hydrogen peroxide, and has no effect on the reaction of the intermediate compound II with aromatic substrates.
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On the basis of optical difference spectra, lactoperoxidase (LPO) was shown to form a 1:1 complex with aromatic donor molecules: resorcinol, hydroquinone, phenol, p-cresol, guaiacol, aniline, and benzohydroxamic acid. As compared with horseradish peroxidase (HRP), the values of the dissociation constant, Kd, of LPO-donor complexes were found to be 4-720-fold larger and were not greatly changed in the presence of KCN and by changes in pH in the range 4-9. The apparent enthalpy and entropy of the binding reactions were found to be -13 kJ mol-1 and -29 J mol-1 K-1, respectively, somewhat smaller (in absolute value) than the corresponding values of HRP. The difference spectra of LPO-donor complexes resembled each other, in contrast to the case of HRP, and the bindings of the donors to LPO occurred in a competitive fashion between the donors. Incubation of LPO with phenylhydrazine and hydrogen peroxide markedly depressed donor binding, the intensity of the Soret band, and the catalytic activity, probably as the result of formation of meso-phenyl derivatives of the heme. These findings suggest that the binding of aromatic donors to LPO occurs at a specific site, probably near the heme edge, where the electron transfer in the peroxidase reaction may take place.
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On the basis of optical difference spectra, lactoperoxidase (LPO) was shown to form a 1:1 complex with aromatic donor molecules: resorcinol, hydroquinone, phenol, p-cresol, guaiacol, aniline, and benzohydroxamic acid. As compared with horseradish peroxidase (HRP), the values of the dissociation constant, Kd, of LPO-donor complexes were found to be 4-720-fold larger and were not greatly changed in the presence of KCN and by changes in pH in the range 4-9. The apparent enthalpy and entropy of the binding reactions were found to be -13 kJ mol-1 and -29 J mol-1 K-1, respectively, somewhat smaller (in absolute value) than the corresponding values of HRP. The difference spectra of LPO-donor complexes resembled each other, in contrast to the case of HRP, and the bindings of the donors to LPO occurred in a competitive fashion between the donors. Incubation of LPO with phenylhydrazine and hydrogen peroxide markedly depressed donor binding, the intensity of the Soret band, and the catalytic activity, probably as the result of formation of meso-phenyl derivatives of the heme. These findings suggest that the binding of aromatic donors to LPO occurs at a specific site, probably near the heme edge, where the electron transfer in the peroxidase reaction may take place.
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eng_Latn
| 31,207 |
Precise electrical contact between single-molecule and electrodes is a first step to study single-molecule electronics and its application such as (bio)sensors and nanodevices. To realize a reliable electrical contact, we can use DNA as a template in the field of nanoelectronics because of its micrometer-scaled length with the thickness of nanometer-scale. In this paper, we studied the reactivity of the amide-coupling reaction to tether oligodeoxynucleotides (ODNs) to organic molecules and the elongation of the ODNs by the polymerase chain reaction (PCR) to synthesize 1.5 kbp dsDNA-organic molecule-1.5 kbp dsDNA (DOD) triblock architecture. The successful amide-coupling reactions were confirmed by electrospray ionization mass spectrometry (ESI-MS), and the triblock architectures were characterized by 1% agarose gel electrophoresis and atomic force microscope (AFM). Our result shows that this strategy is simple and makes it easy to construct DNA−organic molecule−DNA triblock architectures and potentially p...
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Chemical reactions in solution almost always take place via a series of minute intermediates that are often in rapid equilibrium with each other, and hence hardly characterizable at the level of atomistic molecular structures. We found that single-molecule atomic-resolution real-time electron microscopic (SMART-EM) video imaging provides a unique methodology for capturing and analyzing the minute reaction intermediates, as illustrated here for single prenucleation clusters (PNCs) in the reaction mixture of metal–organic frameworks (MOFs). Specifically, we found two different types of PNCs are involved in the formation of MOF-2 and MOF-5 from a mixture of zinc nitrate and benzene dicarboxylates at 95 °C and 120 °C, respectively. SMART-EM identified a small amount of 1-nm-sized cube and cube-like PNCs in the MOF-5 synthesis, but not in the MOF-2 synthesis. In the latter, we instead found only linear and square PNCs, suggesting that the MOF-2/-5 bifurcation takes place at the PNC stage. Numerous techniques have been used to study the crystallization process of metal-organic frameworks, but little is known about their prenucleation clusters. Here the authors use single-molecule atomic-resolution real-time electron microscopic video imaging to identify prenucleation clusters in the synthesis of MOF-2 and MOF-5.
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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).
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eng_Latn
| 31,208 |
This article reviews use of the pulse radiolysis technique in studies of intramolecular electron transfer processes in single- and multi-copper blue proteins. Kinetic parameters are analyzed in order to correlate rates and activation parameters with the available structural information. Reaction mechanisms are presented as well as current theoretical treatments based on the semi-classical Marcus theory.
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Laccases are part of the family of multicopper oxidases (MCOs), which couple the oxidation of substrates to the four electron reduction of O2 to H2O. MCOs contain a minimum of four Cu's divided into Type 1 (T1), Type 2 (T2), and binuclear Type 3 (T3) Cu sites that are distinguished based on unique spectroscopic features. Substrate oxidation occurs near the T1, and electrons are transferred approximately 13 Å through the protein via the Cys-His pathway to the T2/T3 trinuclear copper cluster (TNC), where dioxygen reduction occurs. This review outlines the electron transfer (ET) process in laccases, and the mechanism of O2 reduction as elucidated through spectroscopic, kinetic, and computational data. Marcus theory is used to describe the relevant factors which impact ET rates including the driving force, reorganization energy, and electronic coupling matrix element. Then, the mechanism of O2 reaction is detailed with particular focus on the intermediates formed during the two 2e(-) reduction steps. The first 2e(-) step forms the peroxide intermediate, followed by the second 2e(-) step to form the native intermediate, which has been shown to be the catalytically relevant fully oxidized form of the enzyme.
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Berzelius failed to make use of Faraday's electrochemical laws in his laborious determination of equivalent weights.
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eng_Latn
| 31,209 |
Ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one), a lipid-soluble organoselenium compound, exhibits nu- merous biological activities both in vitro and in vivo systems. This compound is undergoing clinical trials for a number of disease states such as stroke and hearing loss. It is known that ebselen exhibits glutathione peroxidase activity (GPx) and is a remarkable scavenger of reactive oxygen species (ROS) such as peroxynitrite (PN). The rate of the reaction between ebselen and PN has been shown to be about three orders of magnitude higher than that of naturally occurring small mole- cules, such as cysteine, methionine and ascorbate. It is also known that ebselen and related compounds effectively protect against lipid peroxidation induced by transition metal ions. However, the mechanism by which ebselen exerts its antioxi- dant activity and the importance of the cyclic selenazole moiety are still not well-understood. In this article, the complex chemical mechanisms involved in the antioxidant activity of ebselen and related compounds are discussed.
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We previously reported that water-soluble cyclic selenides can mimic the antioxidative function of glutathione peroxidase (GPx) in water through a simple catalytic cycle, in which the selenide (>Se) is oxidized by H2O2 to the selenoxide (>Se=O) and the selenoxide is reduced by a thiol back to the selenide. In methanol, however, the GPx-like activity could not be explained by this simple scenario. To look into the reasons for the unusual behaviors in methanol, monoamino-substituted cyclic selenides with a variable ring size were synthesized, and the intermediates of the catalytic cycle were characterized by means of 77Se-NMR and LC–MS spectroscopies. In water, it was confirmed that the selenide and the selenoxide mainly contribute to the antioxidative function, though a slight contribution from the dihydroxy selenane (>Se(OH)2) was also suggested. In methanol, on the other hand, other active species, such as hydroxyselenonium (>Se+–OH) and hydroxy perhydroxy selenane (>Se(OH)(OOH)), could be generated to build another catalytic cycle. This over-oxidation would be more feasible for amino-substituted cyclic selenides, probably because the ammonium (NH3+) group would transfer a proton to the selenoxide moiety to produce a hydroxyselenonium species in the absence of an additional proton source. Thus, a shift of the major catalytic cycle in methanol would make the GPx-like antioxidative function of selenides perplexing.
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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.
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eng_Latn
| 31,210 |
After occupational exposure to napthylene-1,5 diisocyanate (NDI) for 2 years, a 33-year-old female worker developed work-related asthma attacks. Occupational-type exposure tests with NDI resulted in a late asthmatic response, whereas a corresponding challenge test with 4,4'-methylenediphenyl diisocyanate was negative. We conclude that NDI exposure in the range of its occupational exposure limit caused occupational asthma in this subject.
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Background ::: Isocyanates are some of the leading occupational causes of respiratory disorders, predominantly asthma. Adequate exposure monitoring may recognize risk factors and help to prevent the onset or aggravation of these aliments. Though, the biomonitoring appears to be most suitable for exposure assessment, the sampling time is critical, however. In order to settle the optimal time point for the sample collection in a practical biomonitoring approach, we aimed to measure the elimination of isocyanate urine metabolites.
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A photochemically inactive diarylethene derivative with a naphthol group bridging through the imidazole unit (DIN) was synthesized to characterize a multifunctional switch. Upon stimulation by radiation (UV and visible light), the target diarylethene derivative DIN was not photochemically inactive but photo-active, it could be photo-converted into a keto compound. Moreover, the photochromic reaction of DIN was observed when it was stimulated by the addition of acid or methylation. Fluorescence quenching and the bathochromic effect occurred when DIN was stimulated by the addition of copper ions and a base, respectively. Its optical properties could be regulated by various chemical stimuli. Thus, it can potentially be utilized as a multiresponsive molecular switch.
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eng_Latn
| 31,211 |
The dipyrromethane + aldehyde condensation is a common method for the synthesis of trans-A2B2-porphyrins, but is often plagued by scrambling processes that lead to a mixture of porphyrins. The problem of scrambling is more pronounced with unhindered dipyrromethanes (e.g., 5-phenyldipyrromethane) than with hindered dipyrromethanes (e.g., 5-mesityldipyrromethane). We have characterized the oligomer composition (by LD-MS), yield of porphyrin (by UV–Vis), yield of N-confused porphyrin (by HPLC), and level of unreacted aldehyde (by TLC) in dipyrromethane + aldehyde condensations leading to trans-A2B2-porphyrins. Reaction conditions known to suppress scrambling in reactions involving 5-phenyldipyrromethane (PDPM) were compared to conditions known to provide extensive scrambling. The low-scrambling conditions were found to suppress scrambling by inhibiting reaction of oligomer fragments generated by acid-induced cleavage of the dipyrromethane, rather than by inhibiting acidolysis itself. However, such reaction conditions were also found to inhibit the condensation, leading to low yields (<10%) of porphyrin. The condensation of PDPM + aldehyde was also compared to reactions involving 5-mesityldipyrromethane (MDPM) to understand why trans-A2B2-porphyrins can be prepared in good yield devoid of scrambling from reactions using MDPM. The absence of scrambling in MDPM + aldehyde condensations was due to the resistance of MDPM to acidolysis. Taken together, these studies provide insight into the origin of scrambling with different types of substrates under different reaction conditions in the dipyrromethane + aldehyde route to trans-A2B2-porphyrins.
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Cancer and bacterial diseases have been the most incidental diseases to date. According to the World Health Report 2018, at least every family is affected by cancer around the world. In 2012, 14.1 million people were affected by cancer, and that figure is bound to increase to 21.6 million in 2030. Medicine therefore sorts out ways of treatment using conventional methods which have been proven to have many side effects. Researchers developed photothermal and photodynamic methods to treat both cancer and bacterial diseases. These methods pose fewer effects on the biological systems but still no perfect method has been synthesized. The review serves to explore porphyrin and gold nanorods to be used in the treatment of cancer and bacterial diseases: porphyrins as photosensitizers and gold nanorods as delivery agents. In addition, the review delves into ways of incorporating photothermal and photodynamic therapy aimed at producing a less toxic, more efficacious, and specific compound for the treatment.
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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...
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eng_Latn
| 31,212 |
Reactive oxygen species and platelets are thought to be involved in the pathogenesis of cardiovascular disease. Epidemiological data have indicated that high consumption of fruits and vegetables is associated with a lower incidence of vascular events. Polyphenols were proposed to provide such a protection. In the present study performed in rats, we investigated the influence of (+)-catechin (Cat), a polyphenol identified in tea, cocoa, and red wine, on an acute iron load-induced model of platelet hyperactivity. We found that platelet function was significantly enhanced in iron-loaded rats. These changes were associated with impairment of the antioxidative defense including ex vivo free radical-induced hemolysis. Pretreatment with Cat (10 mg/kg, ip, 4 d) normalized biomarkers of antioxidative status and platelet hyperactivity. The benefits of Cat treatment were only observed in iron-loaded animals and not in control animals. In light of the known antioxidant properties of Cat (or its metabolites), we suggest that oxidative injury-induced modification of platelet calcium homeostasis may have explained the iron load-induced platelet hyperactivity. The protective effect of Cat appears to work probably through normalization of the antioxidative status.
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High plasma concentrations of nonesterified fatty acids (NEFAs), transported bound to serum albumin, are associated with type 2 diabetes (T2D). The effects of albumin on platelet function were investigated in vitro. Modifications of albumin, such as those due to glycoxidation, were found in patients with T2D, and the consequences of these modifications on biological mechanisms related to NEFA handling were investigated. Mass spectrometry profiles of albumin from patients with T2D differed from those from healthy control subjects. Diabetic albumin showed impaired NEFA binding capacity, and both structural and functional alterations could be reproduced in vitro by incubating native albumin with glucose and methylglyoxal. Platelets incubated with albumin isolated from patients with T2D aggregated approximately twice as much as platelets incubated with albumin isolated from healthy control subjects. Accordingly, platelets incubated with modified albumin produced significantly higher amounts of arachidonate metabolites than did platelets incubated with control albumin. We concluded that higher amounts of free arachidonate are made available for the generation of active metabolites in platelets when the NEFA binding capacity of albumin is blunted by glycoxidation. This newly described mechanism, in addition to hypoalbuminemia, may contribute to platelet hyperactivity and increased thrombosis, known to occur in patients with T2D.
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The surface-assisted intramolecular ligand reaction of a porphyrin molecule adsorbed on Au(111) is studied by scanning tunneling microscopy and spectroscopy. The temperature-induced stepwise transformation of iron octaethylporphyrin proceeds via a concentric electrocyclic ring closure, with the final product iron tetrabenzoporphyrin being identified by its characteristic Kondo resonance. Along with the transformation of the organic ligand, changes in the magnetic fingerprint are observed, indicating an increasing coupling of the iron spin with the substrate electrons.
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eng_Latn
| 31,213 |
Ammineruthenium(III) complexes have been found to act as electron acceptors for the transplasmalemma electron transport system of animal cells. The active complexes hexaammineruthenium(III), pyridine pentammineruthenium(III), and chloropentaammineruthenium(III) range in redox potential (E'0) from 305 to -42 mV. These compounds also act as electron acceptors for the NADH dehydrogenase of isolated plasma membranes. Stimulation of HeLa cell growth, in the absence of calf serum, by these compounds provides evidence that growth stimulation by the transplasma membrane electron transport system is not entirely based on reduction and uptake of iron.
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The goal of this study is to establish the effect of [(H2O)(NH3)5Ru(II)]2+ reaction of nuclei on their RNA transcription levels. This question is important because ammineruthenium compounds share chemical and biological properties with the chemotherapeutic agent cis-dichlorodiammineplatinum(II) or cisplatin. First we demonstrate that mouse liver nuclei are active in RNA transcription in vitro and characterize the optimum conditions for in vitro transcription. Synthetic rates in the presence of inhibitors actinomycin D and α-Amanitin and measurements of oligo(dT)-cellulose RNA binding levels suggest that all three RNA Polymerases are active in synthesis at about the following percentages-RNA Polymerase I(30%), II(50%) and III(20%). Mouse liver nuclei reacted with [(H2O)(NH3)5Ru(II)]2+ and then oxidized had (NH3)5 Ru(III)3+-DNA adduct levels inversely related to total RNA synthetic rates. Oligo(dT) cellulose RNA binding levels did not vary with DNA adduct density. These data suggest that direct DNA lesions rather than [(NH3)5Ru(III)]3+ effects on other aspects of the transcription system are responsible for the diminished RNA synthesis levels. Ammineruthenium complexes remain desirable candidates for chemotherapeutic agents that may be safely administered in the unreactive ruthenium(III) state and be activated toward DNA binding by reduction in the hypoxic environment of many tumour cells.
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Alkyl xanthines underwent ::: selective homolytic aromatic substitution at C-8 position with alkyl groups of ::: pentaamminecobalt(III) complex. In this process of synthesis, we used monoalkyl ::: hydrazines as the radical source in aqueous ammonia solution. Evidence supporting ::: coordination of the alkyl hydrazine to pentaamminecobalt(III) complex by ::: radical trapping was in good agreement with literature. The products were ::: characterized using GC-MS and 1H, 14N and 59Co ::: NMR spectroscopy.
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eng_Latn
| 31,214 |
Two linear polyads were designed using zinc(II)porphyrin, [ZnP], and N-methyl-2-phenyl-3,4-fullero-pyrrolidine (C60) where C60 is dangling either at the terminal position of [ZnP]–C6H4––C6H4–[ZnP]–C60 (1) or at the central position of [ZnP]–C6H4––C6H4–[ZnP(C60)]–C6H4––C6H4–[ZnP] (2) in order to test whether the fact of having one or two side electron donors influences the rate of electron transfer, ket. These polyads were studied using cyclic voltammograms, DFT computations, steady state and time-resolved fluorescence spectroscopy, and femtosecond transient absorption spectroscopy (fs-TAS). Photo-induced electron transfer confirmed by the detection of the charge separated state [ZnP˙+]/C60˙− from fs-TAS occurs with rates (ket) of 3–4 × 1010 s−1 whereas the charge recombinations (CRs) are found to produce the [ZnP] ground state via two pathways (central [ZnP˙+]/C60˙− (ps) and terminal central [ZnP˙+]/C60˙− (ns) producing [1ZnP] (ground state) and [3ZnP*]). The formation of the T1 species is more predominant for 2.
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A simple and straightforward synthesis of diporphyrins and pentaporphyrins is reported here. The supramolecular interactions of the new porphyrin derivatives with C60 and PyC60 (a pyridyl [60]fulleropyrrolidine) were evaluated by absorption and fluorescence titrations in toluene. While no measurable modifications of the absorption and fluorescence spectra were observed upon addition of C60 to the porphyrin derivatives, the addition of PyC60 to the corresponding mono-Zn(II) porphyrins resulted in the formation of Zn(porphyrin)-PyC60 coordination complexes and the binding constants were calculated. Results show that the four free-base porphyrin units in pentaporphyrin 6 have a significant contribution in the stabilization of the 6-PyC60 complex. The crystal and molecular features of the pentaporphyrin Zn5 were unveiled using single-crystal X-ray diffraction studies.
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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.
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eng_Latn
| 31,215 |
The origin of life is one of the fundamental questions in science. Eschenmoser proposed the “glyoxylate scenario”, in which plausible abiotic synthesis pathways were suggested to be compatible with the constraints of prebiotic chemistry. In this proposal, the stem compound is HCN. In this work, we explore the “glyoxylate scenario” through several syntheses of HCN polymers, paying particular attention to the role of the aqueous aerosols, together with statistical methods, as a step to elucidate the synthetic problem of the origin of life. The soluble and insoluble HCN polymers synthetized were analyzed by GC-MS. We identified, for the first time, glyoxylic acid in these polymers, together with some constituents of the reductive tricarboxylic acid cycle, amino acids and several N-heterocycles. The findings presented herein, as the first global approach to the “glyoxylate scenario”, give full effect to this hypothesis and prove that aqueous aerosols could play an important role in this plausible scene of the origin of life.
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Life builds its molecules from carbon dioxide (CO2) and breaks them back down again through the intermediacy of just five metabolites, which are the universal hubs of biochemistry1. However, it is unclear how core biological metabolism began and why it uses the intermediates, reactions and pathways that it does. Here we describe a purely chemical reaction network promoted by ferrous iron, in which aqueous pyruvate and glyoxylate—two products of abiotic CO2 reduction2–4—build up 9 of the 11 intermediates of the biological Krebs (or tricarboxylic acid) cycle, including all 5 universal metabolic precursors. The intermediates simultaneously break down to CO2 in a life-like regime that resembles biological anabolism and catabolism5. Adding hydroxylamine6–8 and metallic iron into the system produces four biological amino acids in a manner that parallels biosynthesis. The observed network overlaps substantially with the Krebs and glyoxylate cycles9,10, and may represent a prebiotic precursor to these core metabolic pathways. A chemical reaction network that overlaps with the biological Krebs and glyoxylate cycles arises from pyruvate and glyoxylate in the presence of iron, suggesting how early metabolic pathways might have arisen from CO2.
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Immune mice which exhibited a delayed-type hypersensitivity reaction to bovine serum albumin after bovine serum albumin immunization and stimulation and normal mice that had been transferred with a lymphokine-rich fraction from the supernatant of concanavalin A-stimulated spleen cell cultures demonstrated resistance to Salmonella infection.
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eng_Latn
| 31,216 |
A diarylethene fused trimer, 1-(5-(2-(3,5-dimethyl-2-thienyl)hexafluorocyclopententen-1-yl)-2,4-dimethyl-3-thienyl)-2-(5-(2-(2,4-dimethyl-5-phenyl-3-thienyl)hexafluorocyclopentene-1-yl)-2,4-dimethyl-3-thienyl)hexafluorocyclopentene, was synthesized. The diarylethene derivative showed full-color photochromic performance by choosing appropriate wavelength of light.
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A new unsymmetrical photochromic diarylethene compound, ::: [1-(2-methyl-5-phenyl-3-thienyl),2-(2-methyl-5-(2-pyridyl)-3-thienyl)]perfluorocyclopentene (1a), was synthesized and its photochemical properties, such as ::: photochromism and kinetics in solution as well as in PMMA amorphous film, electrochemical properties and optical ::: strorage properties were investigated in detail. The results showed that the cyclization/cycloreversion process of the ::: compound was determined to be the zeroth/first order reaction, the electrochemical properties suggests that the ::: diarylethene derivative can be used as an electrochemical switch and electrochemistry data storage, and the optical ::: propertis can be potential use for data storage.
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A new unsymmetrical photochromic diarylethene compound, ::: [1-(2-methyl-5-phenyl-3-thienyl),2-(2-methyl-5-(2-pyridyl)-3-thienyl)]perfluorocyclopentene (1a), was synthesized and its photochemical properties, such as ::: photochromism and kinetics in solution as well as in PMMA amorphous film, electrochemical properties and optical ::: strorage properties were investigated in detail. The results showed that the cyclization/cycloreversion process of the ::: compound was determined to be the zeroth/first order reaction, the electrochemical properties suggests that the ::: diarylethene derivative can be used as an electrochemical switch and electrochemistry data storage, and the optical ::: propertis can be potential use for data storage.
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eng_Latn
| 31,217 |
The temperature dependence of the morphology of single wall carbon nanotubes (SWNTs) has been studied by Raman spectroscopy at different temperatures by changing the incident laser power. It is shown that a high power laser irradiation treatment of as-grown samples anneals the SWNTs, improving their structural order and perhaps also removing adsorbed gases. As a result, a significant increase in the Raman cross-section of the nanotubes upon laser irradiation can be observed, for both metallic or semiconducting tubes. The investigation of the power level dependence of the Raman spectra also reveals that smaller diameter nanotubes are burned off first, increasing the mean diameter of the nanotubes in the sample.
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Floating catalyst chemical vapor deposition uniquely generates aligned carbon nanotube (CNT) textiles with individual CNT lengths magnitudes longer than competing processes, though hindered by impurities and intrinsic/extrinsic defects. We present a photonic-based post-process, particularly suited for these textiles, that selectively removes defective CNTs and other carbons not forming a threshold thermal pathway. In this method, a large diameter laser beam rasters across the surface of a partly aligned CNT textile in air, suspended from its ends. This results in brilliant, localized oxidation, where remaining material is an optically transparent film comprised of few-walled CNTs with profound and unique improvement in microstructure alignment and crystallinity. Raman spectroscopy shows substantial D peak suppression while preserving radial breathing modes. This increases the undoped, specific electrical conductivity at least an order of magnitude to beyond that of single-crystal graphite. Cryogenic conductivity measurements indicate intrinsic transport enhancement, opposed to simply removing nonconductive carbons/residual catalyst.
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A unique approach using the large photoacoustic effect of single-walled carbon nanotubes (SWNTs) for targeting and selective destruction of cancer cells is demonstrated. SWNTs exhibit a large photoacoustic effect in suspension under the irradiation of a 1064-nm Q-switched millisecond pulsed laser and trigger a firecracker-like explosion at the nanoscale. By using such an explosion, a photoacoustic agent is developed by functionalizing the SWNTs with folate acid (FA) that can selectively bind to cancer cells overexpressing folate receptor on the surface of the cell membrane and kill them through SWNT explosion inside the cells under the excitation of millisecond pulsed laser. The uptake pathway of folate-conjugated SWNTs into cancer cells is investigated via fluorescence imaging and it is found that the FA-SWNTs can enter into cancer cells selectively with a high targeting capability of 17-28. Under the treatment of 1064-nm millisecond pulsed laser, 85% of cancer cells with SWNT uptake die within 20 s, while 90% of the normal cells remain alive due to the lack of SWNTs inside cells. Temperature changes during laser treatment are monitored and no temperature increases of more than +/- 3 degrees C are observed. With this approach, the laser power used for cancer killing is reduced 150-1500 times and the therapy efficiency is improved. The death mechanism of cancer cells caused by the photoacoustic explosion of SWNTs is also studied and discussed in detail. These discoveries provide a new way to use the photoacoustic properties of SWNTs for therapeutic applications.
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eng_Latn
| 31,218 |
In vitro incubation of peritoneal macrophages from normal, peptone-stimulated mice with levamisole (1-100 microM) for 1 and 22 h had no effect on either phagocytosis of particulate material (sheep erythrocytes, zymosan) or cellular levels and release of lysosomal enzymes (beta-D-glucuronidase, cathepsin D). By contrast, levamisole 1 and 5 mM dramatically increased enzyme release while inhibiting phagocytosis. In some experiments, however, these high concentrations of levamisole caused an elevated cell mortality. When incubation was extended to 72 h, a decrease of both phagocytosis and enzyme release was observed. The catabolism of endocytosed antigens (sheep erythrocytes, human gammaglobulin) was not at all or only slightly modified depending upon the antigen. The cellular level of cyclic AMP remained unchanged in all experiments. In vivo exposure of macrophages to levamisole (2.5 and 10 mg/kg/day i.p. for 3 days) produced a dose-dependent increase in processing of endocytosed antigens as shown by an enhanced transfer of initially endocytosed material to the macrophage plasma membrane. The other parameters were not modified. The immunogenicity of erythrocytes, when endocytosed by levamisole-treated macrophages and transferred into unsensitized recipients, was increased in some in vivo experiments.
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The activity of β-d-glucuronidase (BDG) was lowered and the activity of myeloperoxidase (MPO) was elevated in polymorphonuclear leukocytes (PMNs) of SLE patients compared with normal subjects. After levamisole treatment, the activities of BDG, MPO, and lysozyme rose in PMNs of SLE patients. A higher activity of lysozyme was also observed in peritoneal PMNs of rabbits after levamisole administration. During incubation of human phagocytizing and non-phagocytizing PMNs, no effects of levamisole at concentrations of 10−3 to 10−5M were observed on the release of lysosomal enzymes. These concentrations of levamisole also did not influence INT reductase activity and production of superoxide by normal human PMNs in the presence of zymosan particles. These findings suggest that levamisole might have an effect on the actual level of lysosomal enzymes in PMNs rather than on their release.
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Ammonia synthesis consumes large amounts of energy in traditional industry and causes considerable air pollution to the atmosphere. Therefore, developing green strategies and novel catalysis for NH3 synthesis under ambient conditions using renewable energy is strongly desired. In this work, Er-doped lanthanum cobaltite/attapulgite composites (LaCoO3:Er3+/ATP) were prepared by a sol–gel method. The influence of the Er doping ratio and LaCoO3:Er3+ loading amount on the generation rate of ammonia under visible-light irradiation were investigated. The results show that Er3+-doped LaCoO3 can convert visible light into ultraviolet light and reach the highest conversion rate when the doping amount of the Er element is 6 mol%, which enhances the utilization of solar energy. ATP contributes to the adsorption of N2 and the Co dopant weakens the N≡N bond favoring the activation of N2. Moreover, a direct Z-scheme heterostructure is constructed between LaCoO3:Er3+ and ATP when the loading amount is 10 wt%, which facilitates the separation of charge carriers and preserves the high redox potentials, leading to the enhanced photocatalytic nitrogen fixation performance.
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eng_Latn
| 31,219 |
The synthesis of silicon compounds is usually performed by vulcanization at high temperatures in the presence of a platinum catalyst. The activation can also be achieved by UV light irradiation. When a suitable sensitizer is added to the formulation, the reaction can be triggered by lower wavelengths (in the visible spectra). In this way, both energy saving and greater safety are carried out. In the present paper, the reactivity of the trimethyl(methylcyclopentadienyl)-platinum(IV) catalyst (Me-Cp)Pt(Me)3 was investigated under visible light activation (380–515 nm) in the presence of different amount of 2-chlorothioxanthen-9-one (CTX) sensitizer. A proceeding of the curing after the irradiation was also observed leading to the formation of thick samples after short period of irradiation. The properties of the cured material were compared to those obtained by UV light activation.
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Hydrosilylation reactions, the (commonly) anti-Markovnikov additions of silanes to unsaturated bonds present in compounds such as alkenes and alkynes, offer numerous unique and advantageous properties for the preparation of polymeric materials, such as high yields and stereoselectivity. These reactions require to be catalyzed, for which platinum compounds were used in the initial stages. Celebrating the 50th anniversary of hydrosilylations in polymer science and, concomitantly, five decades of continuously growing research, hydrosilylation reactions have advanced to a level that renders them predestined for transfer into commercial products on the large scale. Facing this potential transfer, this review addresses and discusses selected current trends of the scientific research in the area, namely low-cost transition metal catalysts (focusing on iron, cobalt, and nickel complexes), metal-free catalysts, non-thermally triggered hydrosilylation reactions (highlighting stimuli such as (UV-)light), and (potential) industrial applications (highlighting the catalysts used and products manufactured). This review focuses on the hydrosilylation reactions involving alkene reactants.
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We report on a standoff spectroscopic technique for detecting chemical residues on surfaces. An infrared (IR) camera was used in combination with a wavelength tunable mid-IR quantum cascade laser to acquire multispectral image arrays of a surface with explosive residue. IR spectral signatures of residue of cyclotrimethylenetrinitramine (commonly known as RDX) were extracted in the wavelength range 7.9 to 9.7 $\mu \text{m}$ from the multispectral IR images. Detection of RDX was achieved for a lower surface concentration of $5~\mu \text{g}$ cm−2 and a higher surface concentration of $20~\mu \text{g}$ cm−2 at distances of 0.15 m and 1.5 m, respectively. We performed no background subtraction and the resulting IR spectra of RDX were compared with reference Fourier Transform IR Spectroscopy data that were acquired by placing 20 $\mu \text{g}$ of RDX on a ZnS window. We found that the detection of RDX can be made with negligible interfering contribution of reflected IR photons from the substrate surface.
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eng_Latn
| 31,220 |
The dicobalt form of the metallohydrolase methionine aminopeptidase from Escherichia coli (CoCo EcMetAP) has an active site with one 5-coordinate Co (II) and a more weakly bound 6-coordinate Co (II). These metal ions are bridged by two carboxylate amino acid side chains and water or hydroxide, potentially enabling magnetic exchange coupling between the metals. We used variable-temperature, variable-field magnetic circular dichroism to determine whether such coupling occurs. CoCo EcMetAP's MCD spectrum shows distinct d-d transitions at 495 and 567 nm caused by 6- and 5-coordinate Co (II), respectively. The magnetization curves for 5- and 6-coordinate Co (II) are very different, indicating that their electronic ground states vary considerably, ruling out any coupling. When the fungal metabolite fumagillin binds to the CoCoEcMetAP, the qualitative MCD spectrum is unchanged; however, VTVH MCD data show that 5- and 6-coordinate Co (II) ions have similarly shaped magnetization curves, indicating that the Co (II) ions now share the same electronic ground state. Fitting the VTVH MCD data to a model in which dimer wave functions are calculated using a spin Hamiltonian with zero-field splitting showed the Co (II) ions to be weakly ferromagnetically coupled, with J = 2.9 cm (-1). Ferromagnetic coupling is unusual for dinuclear Co (II); therefore, to support the CoCoEcMetAP/fumagillin complex results, we also analyzed VTVH MCD data from a matched pair of dinuclear cobalt complexes, 1 and 2. Complex 1 shares the carboxylate and hydroxide-bridged dicobalt(II) structural motif with the active site of CoCo EcMetAP. Complex 2 contains a nearly isostructural Co (II) ion, but the Co (III) is diamagnetic, so any magnetic coupling is switched off, while the spectral features of the Co (II) ion remain. Magnetization data for 1, fitted to the dimer model, showed that the Co (II) ions were weakly ferromagnetically coupled, with J = 1.7 cm (-1). Magnetization data for Co (II) ions in 2, however, reflect loss of magnetic exchange coupling.
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Metal ion-dependent, organophosphate-degrading enzymes have acquired increasing attention due to their ability to degrade and thus detoxify commonly used pesticides and nerve agents such as sarin. The best characterized of these enzymes are from Pseudomonas diminuta (OPH) and Agrobacterium radiobacter (OpdA). Despite high sequence homology (>90 % identity) and conserved metal ion coordination these enzymes display considerable variations in substrate specificity, metal ion affinity/preference and reaction mechanism. In this study, we highlight the significance of the presence (OpdA) or absence (OPH) of an extended hydrogen bond network in the active site of these enzymes for the modulation of their catalytic properties. In particular, the second coordination sphere residue in position 254 (Arg in OpdA, His in OPH) is identified as a crucial factor in modulating the substrate preference and binding of these enzymes. Inhibition studies with fluoride also support a mechanism for OpdA whereby the identity of the hydrolysis-initiating nucleophile changes as the pH is altered. The same is not observed for OPH.
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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...
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eng_Latn
| 31,221 |
Many studies have elucidated structures and thermodynamics of complexes formed by different ligands with DNA. However, in most cases structural and free energy binding studies were not correlated with each other because of the problem of identifying which experimental free energy of binding corresponds to which experimental DNA–ligand structure. In the present work, Poisson–Boltzmann and solvent-accessible surface area methods were used to predict unknown modes of interaction between DNA and three different ligands: mitoxantrone and two pyrimidoacridine derivatives. In parallel, experimental measurements of binding free energy for the studied complexes were performed to compare experimental and calculated values. Our studies showed that the calculated values of free energy are only close to experimental data for some models of interaction between ligands and DNA. Based on this correlation, the most likely models of DNA–ligand complexes were postulated: (i) mitoxantrone and one derivative of pyrimidoacridine, both with two charged side chains, intercalate from the minor groove of DNA and bind with both chains in this groove; (ii) pyrimidoacridine, with only one side chain, very likely does not intercalate into DNA at all. Additionally, the non-electrostatic and electrostatic parts of the calculated binding free energy for the DNA–ligands studied are discussed.
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Pyrimidoacridinetriones (PATs) are a new group of highly active antitumor compounds. It seems reasonable to assume that, like for some other acridine derivatives, intercalation into DNA is a necessary, however not a sufficient condition for antitumor activity of these compounds. Rational design of new compounds of this chemotype requires knowledge about the structure of the intercalation complex, as well as about interactions responsible for its stability. Computer simulation techniques such as molecular dynamics (MD) may provide valuable information about these problems. The results of MD simulations performed for three rationally selected PATs are presented in this paper. The compounds differ in the number and position of side chains. Each of the compounds was simulated in two systems: i) in water, and ii) in the intercalation complex with the dodecamer duplex d(GCGCGCGCGCGC)2. The orientation of the side chain in relation to the ring system is determined by the position of its attachment. Orientation of the ring system inside the intercalation cavity depends on the number and position of side chain(s). The conformations of the side chain(s) of all PATs studied in the intercalation complex were found to be very similar to those observed in water.
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The identification of N6-methyldeoxyadenosine in the DNA of Xenopus laevis, mice and humans extends the presence of this mark to vertebrates, thus fostering the potential importance of this mark as a carrier of epigenetic information.
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eng_Latn
| 31,222 |
The synthesis, X-ray crystal structure, vibrational and optical spectroscopy for the eight-coordinate thiocyanate compounds, [Et4 N]4 [Pu(IV) (NCS)8 ], [Et4 N]4 [Th(IV) (NCS)8 ], and [Et4 N]4 [Ce(III) (NCS)7 (H2 O)] are reported. Thiocyanate was found to rapidly reduce plutonium to Pu(III) in acidic solutions (pH<1) in the presence of NCS(-) . The optical spectrum of [Et4 N][SCN] containing Pu(III) solution was indistinguishable from that of aquated Pu(III) suggesting that inner-sphere complexation with [Et4 N][SCN] does not occur in water. However, upon concentration, the homoleptic thiocyanate complex [Et4 N]4 [Pu(IV) (NCS)8 ] was crystallized when a large excess of [Et4 N][NCS] was present. This compound, along with its U(IV) analogue, maintains inner-sphere thiocyanate coordination in acetonitrile based on the observation of intense ligand-to-metal charge-transfer bands. Spectroscopic and crystallographic data do not support the interaction of the metal orbitals with the ligand π system, but support an enhanced An(IV) -NCS interaction, as the Lewis acidity of the metal ion increases from Th to Pu.
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The first example of a uranyl selenocyanate compound is reported. The compound [Et4N]3[UO2(NCSe)5] has been synthesized and fully characterized by vibrational and multinuclear (1H, 13C{1H} and 77Se{1H}) NMR spectroscopy. The photophysical properties have also been recorded and trends in a series of uranyl pseudohalides discussed. Spectroscopic evidence shows that the U–NCSe bonding is principally ionic. An electrochemical study revealed that the reduced uranyl(V) species is unstable to disproportionation and a ligand based oxidation is also observed. The structure of [Et4N]4[UO2(NCSe)5][NCSe] is also presented and Se···H–C hydrogen bonding and Se···Se chalcogen–chalcogen interactions are seen.
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not available DOI: http://dx.doi.org/10.3329/pulse.v5i2.20263 Pulse Vol.5 July 2011 p.31-40
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eng_Latn
| 31,223 |
Recently, pyrazole derivatives as high affinity and selective A2A adenosine receptor antagonists have been reported. But, so far, there are no reports about the inhibitory effects of multi-substituted pyrazole derivatives on apoptosis of vascular endothelial cells (VECs). In this study, we synthesized six pyrazole derivatives and characterized the structures of the compounds by IR, 1 H NMR, mass spectroscopy, and element analysis. The biology assay showed that a novel pyrazole derivative, ethyl 3-( o -chlorophenyl)-5-methyl-1-phenyl-1 H -pyrazole-4-carboxylate (MPD) at low concentration (25 μM) increased VECs viability and inhibited VECs apoptosis induced by deprivation of serum and FGF-2. During this process, the levels of integrin β4, reactive oxygen species (ROS), and p53 were depressed obviously. The data suggested that MPD was a potential inhibitor of apoptosis associated with the signal pathway mediated by integrin β4, ROS, and p53 in VECs.
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A series of novel 5-aryl-3-ferrocenyl-1-pyridazinyl pyrazoline derivatives was synthesized by the reaction of ferrocenyl chalcone and 3-chloro-6-hydrazinylpyridazine in 10-65% yields. The compounds were characterized using IR, (1)H NMR, HRMS spectroscopic techniques and representative compounds 3c and 4c were assigned based on the X-ray crystallographic structure. The absorption and fluorescence characteristics of the compounds were investigated in chloroform, tetrahydrofuran and acetonitrile, respectively. The results showed that the absorption maxima of the compounds varied from 323 to 327 nm depending on the groups bonded to benzene and pyridazine ring. The maximum emission spectra of compounds in CHCl(3) were dependent on groups in pyridazine ring in which a strong donating-electron group such as propoxyl group on pyridazine ring in N-1 position of pyrazoline made the emission wavelength of 4a-4e small red shifte than that of compounds 3a-3e with chlorine group. The intensity of absorption and fluorescence was also correlated with substituent on aryl ring in C-5 position of pyrazoline. In addition, the absorption spectra of these compounds changed very little, but the fluorescence spectra had much change with increasing solvent polarity.
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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.).
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eng_Latn
| 31,224 |
Paramagnetic iron(III) and diamagnetic gallium(III) porphyrin complexes with axial allyl and vinyl ligands have been prepared by the addition of an organo-Grignard reagent to (porphyrin)MIIICl in toluene-d8 solution for in situ observation by 1H NMR spectroscopy. The products are considerably less stable to chromatography and to warming to room temperature than are their alkyl counterparts. The spectral data indicate that the allyl and vinyl groups are coordinated in an η1-fashion for the iron complexes at low temperatures (−80 to −40°C) and for the gallium complexes. Purple blocks of {(tetra(p-anisyl)porphyrin)Ga(vinyl)}·2.5benzene crystallize in the space g P 2 1 n with a = 11.654(3), b = 18.960(6), c = 23.916(6) A , β = 97.69° at 130 K with Z = 4 . Refinement of 9202 reflections, 668 parameters and 18 restraints yielded wR2 = 0.2041 and a conventional R1 = 0.071 for 6434 reflections with l>2σI. The structure shows that the gallium center is five-coordinate with a single, η1-vinyl group as the axial ligand. Remarkably, in view of the tendency of related dioxygen ligands in porphyrin complexes to show four-fold disorder, the vinyl group is fully ordered. Dioxygen reacts with {(tetra(p-tolyl)porphyrin)FeIII(allyl)} at −80°C to produce {(tetra(p-tolyl)porphyrin)FeIII(OH)} and acrolein, OCHCHCH2, the expected products of insertion of dioxygen into an FeC σ-bond.
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In this paper we review recent advances in computational chemistry and specifically focus on the chemical description of heme proteins and synthetic porphyrins that act as both mimics of natural processes and technological uses. These are challenging biochemical systems involved in electron transfer as well as biocatalysis processes. In recent years computational tools have improved considerably and now can reproduce experimental spectroscopic and reactivity studies within a reasonable error margin (several kcal·mol−1). This paper gives recent examples from our groups, where we investigated heme and synthetic metal-porphyrin systems. The four case studies highlight how computational modelling can correctly reproduce experimental product distributions, predicted reactivity trends and guide interpretation of electronic structures of complex systems. The case studies focus on the calculations of a variety of spectroscopic features of porphyrins and show how computational modelling gives important insight that explains the experimental spectra and can lead to the design of porphyrins with tuned properties.
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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.
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eng_Latn
| 31,225 |
We consider a spatial modulation (SM)-based physical-layer network coding (PNC) technique with convolutional codes (CC) for a two-way relay network (TWRN) consisting of two source nodes and a single relay node. We assume all communicating nodes are equipped with multiple antennas. Two source nodes simultaneously transmit packets by utilizing the SM with CC to the relay node. The relay node detects signal by utilizing a maximum-likelihood detection technique based on a direct decoding or a separate decoding algorithm. Through extensive simulations, it has been shown that the SM-based PNC technique outperforms the conventional PNC technique. Note that the direct decoding has low complexity, while achieving a similar performance to the separate decoding in terms of bit error rate (BER).
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In this letter, we consider a two-way relay channel where two source nodes exchange their packets via a half-duplex relay node, which adopts physical-layer network coding (PNC) for exchanging packets in two time slots. Convolutional codes (CCs) are assumed to be applied as a channel code for each packet. The relay node directly decodes the XORed version of packets of two source nodes in the multiple access (MA) phase. We first mathematically analyze a bit error rate (BER) of the MA phase in the PNC with CCs in Rayleigh fading channels. Then, we propose a power allocation (PA) strategy for minimizing the derived BER expression at the relay node. It is shown that the proposed transmit power solution satisfies the following relationship: ${P_{1}^{\ast}\over P_{2}^{\ast}}=\sqrt{\Omega_{2}\over\Omega_{1}} $ , where $P_{i}^{\ast}$ and $\Omega_{i}$ denote the optimal power of the $i$ th source node and the variance of the channel gains between the $i$ th source node and the relay node. The proposed PA strategy significantly outperforms conventional PA schemes in terms of the BER.
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Chemical reactions in solution almost always take place via a series of minute intermediates that are often in rapid equilibrium with each other, and hence hardly characterizable at the level of atomistic molecular structures. We found that single-molecule atomic-resolution real-time electron microscopic (SMART-EM) video imaging provides a unique methodology for capturing and analyzing the minute reaction intermediates, as illustrated here for single prenucleation clusters (PNCs) in the reaction mixture of metal–organic frameworks (MOFs). Specifically, we found two different types of PNCs are involved in the formation of MOF-2 and MOF-5 from a mixture of zinc nitrate and benzene dicarboxylates at 95 °C and 120 °C, respectively. SMART-EM identified a small amount of 1-nm-sized cube and cube-like PNCs in the MOF-5 synthesis, but not in the MOF-2 synthesis. In the latter, we instead found only linear and square PNCs, suggesting that the MOF-2/-5 bifurcation takes place at the PNC stage. Numerous techniques have been used to study the crystallization process of metal-organic frameworks, but little is known about their prenucleation clusters. Here the authors use single-molecule atomic-resolution real-time electron microscopic video imaging to identify prenucleation clusters in the synthesis of MOF-2 and MOF-5.
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eng_Latn
| 31,226 |
The ESR spectra of tetrathiafulvalene (TTF) derivatives substituted with imino pyrolidine- and piperidine-1-oxyls and their cation radicals were investigated. For the neutral TTF’s the unpaired electron is localized at the nitroxide group. While, an intramolecular spin-spin exchange albeit weak occurs between the TTF cation radical and the nitroxide radical in the one-electron oxidized TTF’s, and the ground spin state of the biradical is a singlet.
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The electronic configuration of the molecule is the foundation of its structure and reactivity. The spin state is one of the key characteristics arising from the ordering of electrons within the molecule’s set of orbitals. Organic molecules that have open-shell ground states and interesting physicochemical properties, particularly those influencing their spin alignment, are of immense interest within the up-and-coming field of molecular electronics. In this advanced review, we scrutinize various qualitative rules of orbital occupation and spin alignment, viz.,the aufbau principle, Hund’s multiplicity rule, and dynamic spin polarization concept, through the prism of quantum mechanics. While such rules hold inselected simple cases, in general the spin state of a system depends on a combination of electronic factors that include Coulomb and Pauli repulsion, nuclear attraction, kinetic energy, orbital relaxation, and static correlation. A number of fascinating chemical systems with spin states that fluctuate between triplet andopen-shell singlet, and are responsive to irradiation, pH, and other external stimuli, are highlighted. In addition, we outline a range of organic molecules with intriguing non-aufbau orbital configurations. In such quasi-closed-shell systems,the singly occupied molecular orbital (SOMO) is energetically lower than one or more doubly occupied orbitals. As a result, the SOMO is not affected by electron attachment to or removal from the molecule, and the products of such redox pro-cesses are polyradicals. These peculiar species possess attractive conductive andmagnetic properties, and a number of them that have already been developed into molecular electronics applications are highlighted in this review.
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A 75-year-old female complained of severe chest pain and was emergently admitted to our hospital because of anterior acute myocardial infarction. Emergent coronary angiography was performed and revealed occlusion in segment 7, so a stent was implanted. Lidocaine, carvedilol, amiodarone, magnesium, and nifekalant were administered successively because non-sustained ventricular tachycardia (NSVT) frequently appeared like an electrical storm. After nifekalant administration, QTc was significantly prolonged and torsades de pointes was induced. Overdrive pacing was performed and finally the NSVT was completely controlled. If fatal arrhythmias such as NSVT show resistance to medication, overdrive pacing should be considered to stabilize the arrhythmia associated with acute coronary syndrome.
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eng_Latn
| 31,227 |
Isomeric Dithienophosphepines: The Impact of Ring Fusion on Electronic and Structural Properties
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We present the synthesis and extensive experimental (X-ray crystallography, UV-Vis spectroscopy, cyclic voltammetry) and theoretical (DFT calculations) characterization of two isomeric dithieno[b,f]phosphepines (DTPs). The relative orientation of the phosphepine and the thiophene moieties has a decisive impact on the electronic and structural properties of these compounds. Moreover, the thiophene units allow for a facile subsequent functionalization via direct Pd-catalyzed C-H coupling, which renders DTPs highly promising building blocks for organophosphorus functional materials.
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We have used IR spectroscopy to study the reaction between L-cysteine and dimethyl sulfoxide in aqueous medium. We have found that reaction occurs with formation of an insoluble product, which we have identified. We show that oxidation of L-cysteine by dimethyl sulfoxide can occur at an appreciable rate under mild conditions, with formation of L-cystine, dimethyl sulfide, and water.
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eng_Latn
| 31,228 |
Synthesis of polysubstituted pyridines from oxime acetates using NH4I as dual-function promoter
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Pyridine formation with oxime acetates as the building blocks under metal-free conditions is described. Ammonium iodide has proved to be a highly efficient promoter for oxime N–O bond reduction and subsequent condensation reactions, whereby it played a dual-function role in the transformation. While the three-component reaction of oxime acetates, benzaldehydes, and 1,3-dicarbonyls proceeded well with the assistance of a stoichiometric amount of ammonium iodide, the condensation of oximes and acroleins was enabled by using a catalytic initiator to afford substituted pyridines. By this protocol, substituted pyridine products were generated in moderate to excellent yields with tolerance towards a broad range of functional groups.
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Preparation of a series of dissociatively stable Pt(tripod)PR/sub 3/ complexes where tripod = CH/sub 3/C(CH/sub 2/PPh/sub 2/)/sub 3/ and PR/sub 3/ = PMe/sub 2/Ph, PMePh/sub 2/, PPh/sub 3/, P(4FC/sub 6/H/sub 4/)/sub 3/, P(3,5(CF/sub 3/)/sub 2/C/sub 6/H/sub 3/)/sub 3/, P(CH/sub 2/CH/sub 2/CN)/sub 3/, P(OMe)Ph/sub 2/, P(OMe)/sub 2/Ph, P(OMe)/sub 3/, P(POh)/sub 3/, and P(OCH/sub 2/CF/sub 3/)/sub 3/ are reported. /sup 195/Pt(/sup 1/H) and /sup 31/P(/sup 1/H) NMR data are also included. These data have expanded the data base available for the platinum (0) complexes and facilitated the drawing of empirical relationships from the platinum chemical shifts and platinum-phosphorus coupling constants. 29 refs., 1 fig., 1 tab.
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eng_Latn
| 31,229 |
The effect of desipramine upon central adrenergic function in depressed patients
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Eleven drug free patients meeting Research Diagnostic Criteria for Major Depressive Disorder have been treated with desipramine and given a clonidine infusion after 0, 1 and 3 weeks of treatment. The sedative and hypotensive effects of clonidine were significantly inhibited after three weeks of treatment with desipramine: a similar interaction was seen after one week of treatment although this just failed to reach statistical significance. The growth hormone (GH) response to clonidine was initially impaired, but increased significantly after one week of treatment. A significant reduction in the GH response occurred during the second and third weeks of treatment with desipramine. This last finding is interpreted as evidence of adaptive change of alpha 2 adrenoceptors: the other changes can be explained by the known ability of desipramine to block the re-uptake of noradrenaline.
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To gain insight into the chemical nature of drug-induced photoallergy, model studies have been carried out on the photochemical modification of proteins by tiaprofenic acid. Irradiation of decarboxylated tiaprofenic acid (DTPA) in the presence of p-cresol leads to C–C- and C–O-connected p-cresol “dimers”, together with DTPA hydrodimers. The p-cresol–DTPA cross-coupling product was not detected in this reaction. However, a product of this type is formed using a more hindered phenol, such as 2,6-di-tert-butylphenol. Similar results are obtained when tiaprofenic acid (TPA) or its methyl ester are used as photosensitizers. The observed formation of “dimers” can be related to protein photo-crosslinking, through the coupling of two tyrosine units. On the other hand, phenol–(D)TPA cross-coupling may be relevant to the understanding of drug–protein photobinding.
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eng_Latn
| 31,230 |
Analysis of fatty acid anhydrides and polyanhydrides
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Abstract Acid anhydrides are considered as important reagents in organic and peptide synthesis and in recent years for the formation of prodrugs and biomaterials for controlled release of drugs. This article highlights the analysis of mixed anhydrides and polyanhydrides synthesized by various methods. Analytical methods including HPLC, GLC, 1 H NMR and IR spectroscopy are described for the determination of anhydride hydrolysis and amidation.
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A method was developed to reduce aromatic nitro compounds to the corresponding anilines using sulfur and base. The method tolerates a range of functional groups on the benzene ring, avoids the use of hydrogen and transition metals and provides the anilines in moderate to high yields.
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eng_Latn
| 31,231 |
Localisation by immunofluorescence of thyrotropin-releasing hormone in the cutaneous glands of the frog, Rana ridibunda.
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Abstract Using the technique of indirect immunofluorescence, thyrotropin-releasing hormone (TRH) has been localised in certain cells of the cutaneous glands of the frog, Rana ridibunda . No specific fluorescence was found in other cells in the dermis, nor were any positive cells found in the epidermis. Previous studies have shown by radioimmunoassay that large amounts of TRH are present in frog skin, particularly in the dorsal region. Since dorsal frog skin contains many more glands than its ventral counterpart, this non-homogeneous distribution of TRH can be explained by its presence in a population of cells found in one type of cutaneous gland.
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Ribosomal 5S RNA presents a particular challenge to structural investigations since this polynucleotide is too large for complete NMR characterization but lacks significant tertiary structure to modulate, for example, diagnostic alkylation of guanine N7 by dimethyl sulfate. Nickel- and cobalt-dependent reagents that are sensitive to the N7 and aromatic face of guanine have now been applied to 5S rRNA (Xenopus lavis) and provide structural information that was not previously available from traditional chemical or enzymatic probes. Although G75 had repeatedly demonstrated an average reactivity with dimethyl sulfate and minimal reactivity with RNase T1, this residue was the major target of both metal-dependent reagents. Such reactivity provides crucial support for a structural model of loop E identified by prior physical, but not chemical, methods. Similarly, the tetraloop structure of loop D was more accurately reflected by the reactivity of G87 and G89 in the presence of the nickel reagent rather than in t...
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eng_Latn
| 31,232 |
Polymer-based parallel tandem solar cells with a transparent ferroelectric interconnecting layer
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We present a parallel polymer tandem solar cell that contains a transparent ferroelectric interconnecting layer based on polyvinylidene fluoride (PVDF) between two subcells. The interconnecting layer suppresses charge recombination, which leads to a large increase in short-circuit current and, thereby, effective parallel connection of the two subcells. The tandem cells maintained open-circuit voltages in the region between those of the subcells. An additional increase in the short-circuit current of the tandem cells was attained by introducing another ferroelectric layer to suppress charge recombination at the interface between the front subcell and a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) layer. As a result, a power conversion efficiency of 5.61% was obtained with the tandem structure PVDF/PCDTBT:PC71BM/PVDF/PTB7:PC71BM (PCDTBT is poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)], PC71BM is [6,6]-phenyl-C71-butyric acid methyl ester, and PT...
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To gain insight into the chemical nature of drug-induced photoallergy, model studies have been carried out on the photochemical modification of proteins by tiaprofenic acid. Irradiation of decarboxylated tiaprofenic acid (DTPA) in the presence of p-cresol leads to C–C- and C–O-connected p-cresol “dimers”, together with DTPA hydrodimers. The p-cresol–DTPA cross-coupling product was not detected in this reaction. However, a product of this type is formed using a more hindered phenol, such as 2,6-di-tert-butylphenol. Similar results are obtained when tiaprofenic acid (TPA) or its methyl ester are used as photosensitizers. The observed formation of “dimers” can be related to protein photo-crosslinking, through the coupling of two tyrosine units. On the other hand, phenol–(D)TPA cross-coupling may be relevant to the understanding of drug–protein photobinding.
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eng_Latn
| 31,233 |
Electrochemically generated tungsten-based active species as catalysts for metathesis-related reactions: 1. Acyclic diene metathesis polymerization of 1,9-decadiene
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The application of the WCl6–e−–Al–CH2Cl2 system to acyclic diene metathesis polymerization of 1,9-decadiene is reported. The polyoctenamer formed is of a weight-average molecular weight of 9000 with a polydispersity of 1.92. IR and NMR spectral analyses indicate the retention of the double bonds in the polymer structure with high trans content as expected from a step condensation reaction. This relatively stable catalytic system, however, also activates the competing vinyl addition reactions while being inactive in ring-closure metathesis reactions. Copyright © 2002 John Wiley & Sons, Ltd.
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The inhibition of methyltransferases is currently of high interest, particularly in the areas of microbial infection and cell proliferation, as there have been serious attempts to develop novel anti-microbial agents. In the present investigation, a series of 11 S-adenosyl-$L$-homocysteine analogues have been synthesized and effect of these analogues on DNA methylation catalyzed by DNA methyltransferases was studied. It was found that, while $5^{\prime}$-S-(propionic acid)$5^{\prime}$-deoxy-9-($1^{\prime}$-\beta-$D$-ribofuranosyl)1,3-dideazaadenine was an activator of EcoP15I and HhaI DNA methyltransferases, $5^{\prime}$-S-(propionic acid)$5^{\prime}$-deoxy-9-($1^{\prime}$-\beta-dribofuranosyl)adenine inhibited the methyltransferases in a non-competitive manner. An understanding of the binding of analogues to DNA methyltransferases will greatly assist the design of novel anti-microbial compounds.
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eng_Latn
| 31,234 |
Synthesis of nanosized rubidium ferrite by thermolysis of ferricarboxylate precursors and combustion method
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Abstract Nanosized pure rubidium ferrites have been successfully prepared by thermal decomposition of rubidium hexa(carboxylato)ferrate(III) precursors, Rb 3 [Fe(L) 6 ]· x H 2 O (L = formate, acetate, propionate, butyrate), in flowing air atmosphere from ambient temperature to 1000 °C. Various physico-chemical techniques i.e. simultaneous TG–DTG–DTA, XRD, Transmission Electron Microscope (TEM), IR and Mossbauer spectroscopy etc. have been employed to characterize the intermediates and end products. After dehydration, the anhydrous precursors undergo exothermic decomposition to yield various intermediates i.e. rubidium carbonate/acetate/propionate/butyrate and α-Fe 2 O 3 . A subsequent decomposition of these intermediates, followed by solid state reaction, lead to the formation of nanosized rubidium ferrite (RbFeO 2 ). The same nano-ferrite has also been prepared by the combustion method at a comparatively lower temperature and in less time than that of the conventional ceramic method (>1200 °C).
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A fluorometric enzyme assay was developed to evaluate the ability of a variety of compounds to bind to and/or inhibit pyroglutamyl aminopeptidase I. Among these compounds were a series of chloromethyl ketone analogues of thyrotropin releasing hormone (TRH) which had previously been shown to possess TRH-like activity in the central nervous system and have now been found to be good inhibitors of pyroglutamyl aminopeptidase. Thus, it is suggested that the observed TRH-like CNS activity could derive indirectly from inhibition of endogenous TRH degradation by pyroglutamyl aminopeptidase I.
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eng_Latn
| 31,235 |
Heterogeneous zirconia-supported ruthenium catalyst for highly selective hydrogenation of 5-hydroxymethyl-2-furaldehyde to 2,5-bis(hydroxymethyl)furans in various n-alcohol solvents
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5-Hydroxymethyl-2-furaldehyde (HMF) was hydrogenated to 2,5-bis(hydroxymethyl)furan (BHMF) (>99% yield) in various n-alcohol solvents using a Ru(OH)x/ZrO2 catalyst. The TON and TOF for the hydrogenation were calculated to be 912 and 304 h−1, respectively.
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Abstract Exposure of the dorsal skin of hairless mice to the light of a germicidal lamp under standardized conditions produces reproducible, time-dependent increases of putrescine and spermidine concentrations, and a decrease of spermine levels, concomitant with the increase of the rate of DNa synthesis. Systemic or topical treatment of the animals with α-difluoromethylornithine, an enzyme-activated irreversible inhibitor of ornithine decarboxylase, completely prevents the uv light-induced rapid formation of putrescine, and diminishes the enhancement of polyamine turnover rates. A significant effect of the drug on the rate of DNA synthesis could not be shown. The model is suitable for the study of interrelations between polyamine metabolism and cell proliferation and for the screening of compounds designed as inhibitors of polyamine biosynthesis.
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eng_Latn
| 31,236 |
A Study of the Kinetic and Mechanism of Electrochemical Reduction for Para Nitro Phenol, 2,4- Di Nitro Phenol , 2,4,6-Tri Nitro Phenol in HCL(0.5m) Medium
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In this study, the voltammetric behavior of 4-nitrophenol, 2,4-nitrophenol and 2,4,6-tri nitro phenol in acidic medium was investigated by cyclic voltammetry at glassy carbon electrode.The reduction of the para nitro phenol (2.10 -4 M) in the presence of HCL (0.5M) as supporting electrolyte reveals one irreversible peak while the reduction of the 2,4-di nitro phenol shows two irreversible current peaks and the reduction of the 2,4,6- tri nitro phenol gives three irreversible current peaks to produce the derivatives amines as the final products Keywords: Polarography, Cyclic voltammetry, Glassy carbon electrode (GCE), 4-nitro phenol, 2,4-di nitro phenol , 2,4,6 tri nitro phenol
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1. After i.p. administration of [14C]diphenyl ether (5 mg/kg) to rats, radioactivity was detected rapidly in all organs and tissues.2. After intragastric administration of [14C]diphenyl ether (10 mg/kg) to rats, unchanged diphenyl ether in the blood was at max. concn. within 15 h and decreased linearly with time, with a biological half-life of about 1–5 h.3. More than 90% of the intragastrically administered dose was excreted in urine and faeces within three days; >80% dose was in the urine.4. From g.l.c. and mass-spectral data, it was shown that rats metabolized diphenylether to its 2-hydroxy, 4-hydroxy, 4,4′-dihydroxy, 4-methoxy-monohydroxy and 4-methoxy-dihydroxy derivatives.
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eng_Latn
| 31,237 |
[8-(Diphenylphosphanyl)naphthyl-κ2 C 1,P](phenylethynyl)tris(trimethylphosphane-κP)iron(II)
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The title compound, [Fe(C(8)H(5))(C(22)H(16)P)(C(3)H(9)P)(3)], was synthesized by the addition of phenyl-ethine to a solution of the parent methyl iron complex Fe(CH(3)){P(C(6)H(5))(2)(C(10)H(6))}(PMe(3))(3) at 213 K, accompanied by evolution of methane. The coordination around the iron center can be described as slightly distorted octa-hedral [Fe-P 2.2485 (12)-2.2902 (12) Å; Fe-C 1.918 (5), 2.015 (4) Å], with a meridional arrangement of the trimethyl-phosphine ligands and the introduced terminal alkinyl-ligand trans to the P(Ph)(2)-anchoring group.
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As a method for removing hydrogen sulfide feed synthesis, iron penta-carbonyl, and nickel tetra carbonyl from a gas stream, the removal method comprising: (A) water, by contacting the absorbing liquid comprising a physical solvent and an amine with the feed synthesis gas stream to remove hydrogen sulfide and iron penta-carbonyl, hydrogen sulfide and iron penta carbonyl step carbonyl is of obtaining a synthesis gas stream depleted, (B) the hydrogen sulfide and iron penta carbonyl this to a synthesis gas stream depleted in contact with a solid adsorbent comprising activated carbon to adsorb the nickel tetra carbonyl, nickel tetra carbonyl this thick solid adsorbent and the purified synthesis gas stream, a and a step of obtaining. Syngas stream, hydrogen sulfide, iron penta-carbonyl, nickel tetra carbonyl
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eng_Latn
| 31,238 |
Preparation and characterization of some addition complexes of cobalt(II) dithioacetylacetonate with Nitrogen donors
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A series of 1:1 addition complexes of Cobalt(II)dithioacetylacetonates with nitrogen donors such as morpholine, piperidine, piperazine, carbazole, dimethylamine, diethylamine and isopropylamine have been synthesized by treating the appropriate metal(II)dithioacetylacetonate with nitrogen donors in organic solvent . These addition complexes have been characterized by analytical data, electrical conductance, magnetic susceptibility measurements and electronic and infrared spectral studies. The biological activities of the complexes have also been carried out and they have been found to be antifungal in nature. NMR studies of some complexes has also been carried out.
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This work deals with the analysis of the performance and emissions of ethanol HCCI/PSCCI engines by means of a Dynamic Adaptive Chemistry (DAC) technique. The implementation of such a technique provides a reduction of the computational cost of the simulations without compromising the reliability of the results. Very accurate results, in terms of pressure and heat release rate profiles and CO, CO2 and UHC emissions, are obtained with ethanol as the only species for the DRGEP graph search both with the charge uniformly distributed in the combustion chamber and by directly injecting liquid fuel in the same chamber. The global speed up of DAC simulations is twice with respect to a full mechanism which consists of 57 species and 288 reactions and a further increase is expected when DAC is compared to very detailed kinetics.Copyright © 2012 by ASME
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eng_Latn
| 31,239 |
Present status and future trends of specialty polymers for automotive hose in Japan
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Abstract In Japan, official specifications covering automotive devices do not specify the polymer(s) to be used. Accordingly, we have reviewed the market trend of polymer usage for various hoses in these devices, and through a review of published papers, indicated polymer usage reported or suggested in them. As the development of automotive parts requiring higher endurance and reliability has been greatly emphasized in Japan, we, a specialty polymer supplier, have expended our best efforts to comply with such requirements.
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Abstract Literature sources on metal-organic materials encapsulating versatile porphyrinoids and heme enzymes have been discussed in this review. General fundamentals and structural and chemical requisites of these architectures are discussed in introduction followed by historical perspectives of the initial composites. We have categorized the structural aspects of this class of compounds according to the host and guest skeletons as well as encapsulating strategies in a sequential manner. Heme mimetic, as well as some novel applications of the materials including oxidation, electron transfer, carbene transfer and bio-molecule sensing, are then discussed and compared with each other and their homogeneous analogues based on mechanistic similarities, wherever possible.
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eng_Latn
| 31,240 |
An Empirical Analysis of the Relationship among Top Management Team Heterogeneity, Collective Innovation Capacity and Corporate Performance
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Through interviews with TMT members and data from 102 valid questionnaires, the result of empirical analysis shows that: top management team heterogeneity in age and organizational tenure is positive to collective innovation capacity and corporate performance; collective innovation capacity is positive to corporate performance; collective innovation capacity mediates partially the relationship between TMT age heterogeneity and corporate performance, and mediates entirely the relationship between TMT tenure heterogeneity and corporate performance.
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Abstract Literature sources on metal-organic materials encapsulating versatile porphyrinoids and heme enzymes have been discussed in this review. General fundamentals and structural and chemical requisites of these architectures are discussed in introduction followed by historical perspectives of the initial composites. We have categorized the structural aspects of this class of compounds according to the host and guest skeletons as well as encapsulating strategies in a sequential manner. Heme mimetic, as well as some novel applications of the materials including oxidation, electron transfer, carbene transfer and bio-molecule sensing, are then discussed and compared with each other and their homogeneous analogues based on mechanistic similarities, wherever possible.
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eng_Latn
| 31,241 |
Copolymerization of propylene oxide and carbon disulfide with diethylzinc–electron‐donor catalyst
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Copolymerization of propylene oxide with carbon disulfide was studied by using a catalyst consisting of diethylzinc (ZnEt2) and various electron donors. Tertiary amines, tertiary phosphines, and hexamethylphosphoric triamide were the effective donors for the copolymerization, but ZnEt2–water, alcohol, and primary or secondary amines having high activities for the homopolymerization of propylene oxide were not effective for the copolymerization of propylene oxide and carbon disulfide. The copolymers obtained were of low molecular weight and had a monomer unit ratio (CS2/PO) of 0.5–0.7. In addition, a considerable amount of 1,3-oxathioran-4-methyl-2-thion was isolated as a by-product.
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Abstract Exposure of the dorsal skin of hairless mice to the light of a germicidal lamp under standardized conditions produces reproducible, time-dependent increases of putrescine and spermidine concentrations, and a decrease of spermine levels, concomitant with the increase of the rate of DNa synthesis. Systemic or topical treatment of the animals with α-difluoromethylornithine, an enzyme-activated irreversible inhibitor of ornithine decarboxylase, completely prevents the uv light-induced rapid formation of putrescine, and diminishes the enhancement of polyamine turnover rates. A significant effect of the drug on the rate of DNA synthesis could not be shown. The model is suitable for the study of interrelations between polyamine metabolism and cell proliferation and for the screening of compounds designed as inhibitors of polyamine biosynthesis.
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eng_Latn
| 31,242 |
Design and Synthesis of Certain Mesoionic Sydnonyl Styrylketones as Potential Nonsteroidal Antiinflammatory Agents.
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Compounds containing both the structural features of mesoionic sydnones and styrylketone (III) (9 examples) are designed and synthesized as potential analgesic and antiinflammatory agents using a Claisen—Schmidt reaction.
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We have used IR spectroscopy to study the reaction between L-cysteine and dimethyl sulfoxide in aqueous medium. We have found that reaction occurs with formation of an insoluble product, which we have identified. We show that oxidation of L-cysteine by dimethyl sulfoxide can occur at an appreciable rate under mild conditions, with formation of L-cystine, dimethyl sulfide, and water.
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eng_Latn
| 31,243 |
Stereochemical studies of the synthesis of α-amino-nitriles related to lincosamine
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Abstract The syntheses of 6-amino-6-deoxyheptopyranurononitriles related to lincosamine by cyano-amination of 1,2:3,4-di- O -isopropylidene-α- d - galacto -hexodialdo-1,5-pyranose ( 2 ) is reported. The procedure described allowed direct cyano-amination in good yield under mild conditions. The high diastereofacial selectivity of the reaction is discussed. Indirect cyano-amination by activation of the corresponding cyanohydrins followed by displacement with an amine was also studied. Epimerization occurred at C-6 and the resulting aminonitriles were formed under thermodynamic control. From these chain extensions, precursors of lincosamine and analogues were obtained.
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Abstract The set-up and operating principle of an analyzer, which can be used without any filter for the continuous measurement of ammonia (NH 3 ) and isocyanic acid (HNCO) in soot containing exhaust gases is described. Ammonia and isocyanic acid are dissolved in a buffer solution, in which ammonia is measured directly with an ammonia-sensitive electrode. The sum of ammonia and isocyanic acid is measured with the same method after hydrolysis of HNCO to NH 3 and CO 2 . Ammonia and isocyanic acid concentrations of up to ∼500 ppm can be measured with a mean relative error of 3.6% at a standard deviation of 4.0%. The investigation of the urea thermohydrolysis, which is an important step in the selective catalytic reduction (SCR) of nitrogen oxides in Diesel exhaust gases, revealed the emission of toxic isocyanic acid besides ammonia from the SCR catalyst.
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eng_Latn
| 31,244 |
Assignments of the temporary anion states of the chloromethanes
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Calculations employing the stabilization method are used to predict the energies or the C-Cl(σ * ) anion states or the chloromethanes. These calculations provide support for the assignments or the features observed in the electron transmission spectra or the chloromethanes. The stabilization method is round to be much more successful than conventional molecular orbital calculations at predicting relative vertical electron attachment energies
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1. ::: ::: The photoelectronic spectra of the molecules of some cyclopropyl-substituted butadienes were obtained and interpreted. ::: ::: ::: ::: ::: 2. ::: ::: The processes of the formation of negative ions in dissociative capture of electrons by the molecules of these compounds were studied. The effect of the cyclopropyl groups is primarily manifested by destabilization of the molecular negative ion with respect to self-splitting of the electron.
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eng_Latn
| 31,245 |
Identification of degradation products of diclofenac by electrospray ion trap mass spectrometry.
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The degradation products of diclofenac in aqueous dosage form in accelerated storage conditions were characterized by electrospray ionization-ion trap mass spectrometry (ESI-MS). Liquid chromatography (LC)-MS analyses revealed the presence of three degradation products. ESI-MS(n) spectra were used to study diclofenac fragmentation in detail and to characterize the structures of degradation products. A previously described degradation product, formed by a cyclization reaction of diclofenac producing the indolinone derivative, was found. As any hydroxylated product was found, no oxidation seems to occur in the dosage form used. On the contrary, two degradates have been detected and identified, leading to a primary alcohol structure or an aldehyde function in place of the acetate group of diclofenac.
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This study reports on the gelation behaviour of a well-known family of dipicolinic acid derivatives that lack any long aliphatic chain as substituent. The mechanism of gelation is likely to arise from the base-assisted deprotonation of the carboxylic functionality which leads to the formation of the
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eng_Latn
| 31,246 |
Mechanisms and Active Sites for C–O Bond Rupture within 2-Methyltetrahydrofuran over Ni, Ni12P5, and Ni2P Catalysts
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Nickel phosphide catalysts (Ni12P5 and Ni2P) preferentially cleave sterically hindered 3C–O bonds over unhindered 2C–O bonds, and Ni2P is up to 50 times more selective toward 3C–O bond cleavage than Ni. Here, we combine kinetic measurements, in situ infrared spectroscopy, and density functional theory (DFT) calculations to describe the mechanism for C–O bond rupture over Ni, Ni12P5, and Ni2P catalysts. Steady-state rate measurements and DFT calculations of C–O bond rupture within 2-methyltetrahydrofuran (MTHF) show that quasi-equilibrated MTHF adsorption and dehydrogenation steps precede kinetically relevant C–O bond rupture at these conditions (1–50 kPa MTHF; 0.1–6 MPa H2; 543 K). Rates for 3C–O and 2C–O bond rupture are inhibited by H2, and the ratio of these rates increases with [H2]1/2, suggesting that the composition of the reactive intermediates for 3C–O and 2C–O rupture differs by one H atom. Site-blocking CO*, NH3*, and H* inhibit rates without altering the ratio of 3C–O to 2C–O bond rupture, indi...
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Abstract The geometry of thianthrene and its cation radicals (the ground state and first excited state) has been studied. Ab initio calculations on thianthrene indicate a folded structure. Ab initio and energy weighted maximum overlap on the thianthrene cation radical and its first excited state reveal a structure very similar to the closed shell system. The results obtained are discussed in relation to the chemical properties of thianthrene.
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eng_Latn
| 31,247 |
Decreased benzodiazepine receptor density in rat cerebellum following neurotoxic doses of phenytoin.
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The effect of acute and chronic administration of phenytoin on [3H]flunitrazepam binding was examined in the rat cerebellum. There was no significant effect of phenytoin on [3H]flunitrazepam binding in the rat cerebellum 1 and 6 h after a single i.p. injection of 200 mg/kg of phenytoin. However, after 14 days and 28 days of chronic phenytoin administration, significant decreases in [3H]flunitrazepam receptor density were observed, with no changes in apparent affinity constants in the rat cerebellum. This effect of phenytoin was dose-dependent, as lower doses of phenytoin (100 mg/kg/day) for 14 or 28 days produced no alterations in [3H]flunitrazepam binding the the rat cerebellum. Light-microscopic examination of the rat cerebellum treated with 200 mg/kg/day of phenytoin for 14 days showed degeneration of the Purkinje cells, with edematous Bergmann astrocytes. These data provide evidence for the neuronal localization of benzodiazepine receptors on cerebellar Purkinje cells.
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Studies on the relative reactivities of esters of oncogenic and nononcogenic members of the purine N-oxide series indicate that, despite similarities in rates of reaction with the solvent, electrophilic cations from oncogenic derivatives are 10- to 100-fold more reactive toward added nucleophiles in vitro than are cations from nononcogenic compounds. The studies provide strong confirmation of an earlier proposal that nitrenium ion contributors of delocalized aromatic cations from 3-acyloxypurines, rather than radical intermediates, are the agents responsible for the oxidizing reactivity of these esters. They demonstrate further that delocalized aromatic nitrenium ions are highly susceptible to reduction by common nucleophiles that are not usually associated with oxidation-reduction reactions. Examples of such behavior with "soft" bases and other oncogenic arylamines indicate the generality of this little recognized property of aromatic nitrenium ions.
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eng_Latn
| 31,248 |
Changes Characteristics of LDH,CK-MB,CK and cTnI Content in Neonatal Hypoxic-ischemic Encephalopathy
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Objective:To study the changes characteristics of LDH,CK-MB,CK and cTnI content in neonatal hypoxic-ischemic encephalopathy. Methods:The content of LDH,CK-MB,CK and cTnI in the serum of 37 cases of neonatal hypoxic-ischemic encephalopathy admitted to our hospital in acute and convalescent was measured,the measurement results were compared with healthy newborns born in the hospital for the same period.Results:The levels of LDH,CK-MB,CK and cTnI of the control group when was born 3d were significantly lower than the content of the acute phase of the observation group(P 0.01); there was no significant difference of the content of LDH,CK-MB,CK and cTnI content of the control group was born after 10d with the observation group convalescent(P 0.05).Conclusion:Different periods of neonatal hypoxic-ischemic encephalopathy LDH,CK-MB,CK and cTnI levels change significantly,the detection of the above indicators can provide scientific guidance for clinical treatment,staging,indexing.
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Abstract A new kinetic approach is presented to study the mechanism of the catalytic reaction of the hydrogenation of carbon monoxide on Fe–Co–Mn catalyst prepared by wet impregnation method over MgO support. The experimental data obtained by a fixed bed reactor are used for calculating the apparent activity energy of the LHHW kinetic models developed for the consumption of carbon monoxide, and formation of methane, alkenes and alkanes. Then, using the calculated activation energies and the available UBI–QEP relationships for the ternary catalyst and obtaining the relationships between the apparent activity energy of the LHHW kinetic model and the activity energy of surface elementary reactions involved in the kinetic equation extraction and by developing an appropriate software coupled with a genetic optimization algorithm, the surface binding energy of carbon, oxygen and hydrogen on the ternary catalyst are calculated.
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eng_Latn
| 31,249 |
Substrates for Rapid Delivery of Electrons and Holes to Buried Active Sites in Proteins
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New reduced and oxidized states of cytochrome P450cam have been generated by electron transfer to and from the heme group of the buried active site. This is achieved with the photosensitizer [Ru(bpy)3]2+ (bpy=2,2′-bipyridine), which is linked through a hydrocarbon chain to a species with high affinity for the heme cavity (see picture). The direction of photoinduced charge transfer is controlled with a suitable quencher; the new oxidation states are formed in about 0.1 ms and persist for approximately 100 ms.
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Features of the interaction with DNA of photoactivable aryl azides having various substituents in the aromatic ring have been studied. The nature of the interaction with DNA and the degree of its modification depend substantially on the nature of these substituents. The results obtained can be used for obtaining DNA probes bearing various marker groups.
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eng_Latn
| 31,250 |
Trifluoromethylations of Alkenes Using PhICF3Cl as Bifunctional Reagent
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We described a trifluoromethylation of alkenes using PhICF3Cl as bifunctional reagent. Chlorotrifluoromethylated products were obtained when nonconjugated alkenes were treated with PhICF3Cl in 1,4-dioxane at 60 °C, while vinyl C–H trifluoromethylated products were obtained by further elimination of hydrochloride in the case of those conjugated alkene substrates in DMF. Broad substrate scope, especially including complex alkenes bearing biological active motifs, suggests that this mild reaction is feasible for late-stage modification in drug discovery.
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Abstract By varying the conditions of reacting methylhistamine, histamine, histidine, 3-methylhistidine, 1-methylhistidine, methylimidazoleacetic acid, and imidazoleacetic acid with NBS and OPD, fluorophors are obtained which could be exploited for the measurement of these substances in biological material.
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eng_Latn
| 31,251 |
Nucleogenic silylium cations and their analogs
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Abstract Radiochemical studies of nucleogenic trivalent cations of the 14th group elements (silicon and germanium) generated by the β-decay of tritium atoms incorporated into organometallic molecules are reviewed. The radiochromatographic analysis of the neutral labeled products of reactions of these cations with various nucleophiles combined with quantum chemical data allowed us to obtain new information about the reactivity and rearrangements of silylium and germylium cations.
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As part of a research programme targeting novel indole-like molecules as potential cannabinoid agonists [1-4] we synthesised N-(2-ethylmorpholino)-3-bis-ketothiene.[...]
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eng_Latn
| 31,252 |
Asymmetric 1,4-additions to μ-menthyloxybutenolides. (part III)1 enantioselective synthesis of (−) eudesmin.
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Abstract Based on an enantioselective Michael Addition of the aryldithiane of 3,4-dimethoxybenzaldehyde, to (5S)-methyloxy-s[5H]-furanone optically pure (−) Eudesmin was systhesized in 16% overall yield.
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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.
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eng_Latn
| 31,253 |
Sulphydryl groups in photosynthetic energy conservation III. Inhibition of photophosphorylation in spinach chloroplasts by CdCl2
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Abstract Low concentrations of CdCl2 inhibited cyclic and non-cyclic photophosphorylation in spinach chloroplasts and depressed coupled electron transport to the basal level. The basal electron transport and the electron flow stimulated by several uncouplers, except arsenate, were not affected. The inhibitory effects of cadmium were reversed by dithiols like dithioerythritol or 2,3-dimercaptopropanol. The light-induced pH rise of chloroplast suspensions and the trypsin-activated Ca-ATPase were not affected by cadmium at the concentrations that inhibited ATP synthesis but the latter was affected by higher concentrations.
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The investigations of recent progress in the fields of design and synthesis of supramolecular coordination compounds,as well as their applications,are reviewed in the text.As new potential functional materials, supramolecular coordination compounds containing thiosemicarbazide have been synthesized via molecular design and spontaneous assembly,and their composition-structure-nonlinearity relationships are discussed in this thesis.All the achievements for our research work have been carried out in order to design and synthesize new functional complex with novel structure effectively.
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eng_Latn
| 31,254 |
Oxidative Phosphorylation and Sensitivity to Uncouplers of House Fly Mitochondria: Influence of Isolation Medium
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An isolation and suspension medium for house fly, Musca domestica L., muscle mitochondria consisting of sucrose, EDTA, citrate, α -ketoglutarate, and succinate results in high efficiency for oxidative phosphorelation, adequate respiratory control, and maximal sensitivity to uncouplers. This system permits further studies with the oxygen electrode on the mode of action of uncouplers as insecticide chemicals
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The alignment between the energy levels of the constituents of an organic solar cell plays a central role in determining the open-circuit voltage. However, tuning the energy levels of electrodes and/or active components via molecular modifiers placed at interfaces is not straightforward. The morphology of organic materials is commonly controlled by the substrate onto which they are deposited, and differences in morphology often lead to differences in energetics. Such a change in morphology may reduce the effect of surface modifications, as the modified surface is part of an interface with the organic material. Here we show, in an experimental model system, that by using binary molecular monolayers, in which dipolar molecules are buried in a protective nonpolar matrix, we can transform changes in the electrode surface dipole into interface dipole changes without significantly affecting the growth of pentacene onto the molecular layer, thus enabling the use of the full range of dipolar-induced open-circuit-...
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eng_Latn
| 31,255 |
Hemistepsins with cytotoxic activity from Hemisteptia lyrata.
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Two sesquiterpene lactones were isolated from Hemisteptia lyrata Bunge (Compositae). Their structures were elucidated by spectroscopic methods as recently known hemistepsin and the new 6-O-(2-methylpropenoyl)-3-hydroxy-4(15), 10(14), 11(13)-guaiatrien-12,8-olide. The two hemistepsin derivatives were examined for their in vitro cytotoxic activity against human cell lines such as UACC 62, HCT 15, UO-31, PC-3 and A549. Growth inhibitory property was determined by in vitro treatment of the respective cell lines using the sulforhodamine B assay (SRB). Both compounds exhibited significant cytotoxic activity (IC50 < 4.3 micrograms/ml) on all five human cell lines tested.
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Despite the young age of the research field, substantial progress has been made in the study of metal halide perovskite nanocrystals (HPNCs). Just as their thin-film counterparts are used for light absorption in solar cells, they are on the way to revolutionizing research on novel chromophores for light emission applications. Exciting physics arising from their peculiar structural, electronic, and excitonic properties are being discovered with breathtaking speed. Many things we have learned from the study of conventional semiconductor quantum dots (CSQDs) of II–VI (e.g., CdSe), IV–VI (e.g., PbS), and III–V (e.g., InP) compounds have to be thought over, as HPNCs behave differently. This Feature Article compares both families of nanocrystals and then focuses on approaches for substituting toxic heavy metals without sacrificing the unique optical properties as well as on surface coating strategies for enhancing the long-term stability.
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eng_Latn
| 31,256 |
4-Vinylbenzyl analogs of adenine and uracil: reactive monomers for nucleobase polymeric resins.
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The crystal structures of 9-(4-vinylbenzyl)adenine, C(14)H(13)N(5), and 1-(4-vinylbenzyl)uracil, C(13)H(12)N(2)O(2), are composed of zigzag ribbon-like structures that are stabilized by conventional (N[bond]H...N-type) hydrogen bonds for the former and conventional (N[bond]H...O-type) and non-conventional (C[bond]H...O-type) hydrogen bonds for the latter; the hydrogen-bonding patterns are represented by graph-sets R(2)(2)(9) and R(2)(2)(8), respectively. The adenine and uracil moieties in these alkylated derivatives are planar and are inclined at angles of 84.44 (4) and 79.07 (7) degrees, respectively, with respect to the phenyl rings.
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Adjuvant having an adjuvant capacity superior to those of conventional adjuvants and capable of effecting protective reactions over strains. This adjuvant has been developed on the basis of the finding that a double stranded RNA (for example, Poly(I:C)) when used in combination with a subunit antigen unexpectedly has the above capability. Thus, there is provided a vaccine for mucosal administration, comprising a double stranded RNA (A) and, as a pathogen, a subunit antigen or inactivated antigen (B).
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eng_Latn
| 31,257 |
Large-Scale, Protection-Free Synthesis of Se-Adenosyl-l-selenomethionine Analogues and Their Application as Cofactor Surrogates of Methyltransferases
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S-Adenosyl-l-methionine (SAM) analogues have previously demonstrated their utility as chemical reporters of methyltransferases. Here we describe the facile, large-scale synthesis of Se-alkyl Se-adenosyl-l-selenomethionine (SeAM) analogues and their precursor, Se-adenosyl-l-selenohomocysteine (SeAH). Comparison of SeAM analogues with their equivalent SAM analogues suggests that sulfonium-to-selenonium substitution can enhance their compatibility with certain protein methyltransferases, favoring otherwise less reactive SAM analogues. Ready access to SeAH therefore enables further application of SeAM analogues as chemical reporters of diverse methyltransferases.
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The lake sediments have registered the information of palaeoclimate and palaeoenvironment in the lake itself and the regional scale. This also leads to a complexity in study of the palaeolimnology by all kinds of proxies. How to purify these proxies to indicate the palaeoclimate has become a problem to be solved. Most of the proxies can qualitively identify the percentage of allochthonous and autochthonous organic components, e.g. δ13corg CD/TC. The model introduced in this note has provided a method of quantitatively calculating the amount of allochthonous organic carbon. As for determination of regulating parameters, i.e. A1 and As, further work is still in need.
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eng_Latn
| 31,258 |
Expression of E-Cadherin, α-Catenin, β-Catenin and Plakoglobin in Esophageal Carcinomas and Its Prognostic Significance
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It has been suggested that inactivation of the cadherin-mediated cell-cell adhesion system plays a role in the initial steps of cancer invasion and metastasis. Expression of E-cadherin and its intracy
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Abstract Detailed DFT calculations of C2H2 hydrogenation on Pd6, Pd6+ and Pd6B clusters were performed to explore the effect of interstitial B on the mechanisms of C2H2 hydrogenation catalyzed by Pd6. The results show that the Pd6B cluster has the lowest diffusion barriers of H atoms and dissociated barriers of H2; the interstitial B atom can simultaneously improve both the activity and selectivity of C2H2 hydrogenation to C2H4 on Pd6 cluster by altering the major product and the optimal pathway. Moreover, the higher charge is conducive to enhancing the adsorption of C2H2 and C2H4, rather than the selectivity of C2H4 formation. Our work provides some insight into the activity selectivity charge relationship of Pd-based catalysts in C2H2 selective hydrogenation.
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eng_Latn
| 31,259 |
A new class of binuclear rhenium(II) halide species containing a strong metal–metal bond: the chemistry and structure of complexes of the type Re2X4(Pr3)4
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A new class of tertiary phosphine complexes of the type Re2Cl4(PR3)4 have been isolated from the reation of Re3Cl9 or the Re2Cl82– anion with the appropriate phosphine, and a single crystal X-ray structure analysis has shown Re2Cl4(PEt3)4 to posses a strong (evidently quadruple) rhenium–rhenium bond and eclipsed rotational configuration.
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Abstract Nitroxide free radicals are destroyed by ultraviolet irradiation in the presence of phenothiazine derivatives. This property has been used in order to determine the type of interaction of these drugs with spin-labelled lecithin multibilayers. Kinetic measurements of the spin label signal decay under irradiation have shown that chlorpromazine and perphenazine are preferentially located in the polar part of the bilayer, whereas promethazine and oxidized derivatives of chlorpromazine are found principally in the hydrophobic part.
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eng_Latn
| 31,260 |
C(sp2)–H Trifluoromethylation of enamides using TMSCF3: access to trifluoromethylated isoindolinones, isoquinolinones, 2-pyridinones and other heterocycles
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A method for the direct C(sp2)–H trifluoromethylation of enamides, including biologically relevant isoindolinones, isoquinolinones and 2-pyridinones using TMSCF3 under oxidative conditions is presented. The protocol is convenient, operationally simple and exhibits high tolerance across a multitude of relevant handles and functional groups.
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A fluorometric enzyme assay was developed to evaluate the ability of a variety of compounds to bind to and/or inhibit pyroglutamyl aminopeptidase I. Among these compounds were a series of chloromethyl ketone analogues of thyrotropin releasing hormone (TRH) which had previously been shown to possess TRH-like activity in the central nervous system and have now been found to be good inhibitors of pyroglutamyl aminopeptidase. Thus, it is suggested that the observed TRH-like CNS activity could derive indirectly from inhibition of endogenous TRH degradation by pyroglutamyl aminopeptidase I.
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eng_Latn
| 31,261 |
Theoretical studies on the acid hydrolysis of methyl carbamate
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The mechanism of the A2 acid hydrolysis of methyl carbamate was investigated using MNDO method. The reaction was found to proceed in two steps: (1) the rate-determining nucleophilic attack of water on the carbonyl carbon of the N-protonated tautomer involving the tetrahedral TS; and (2) the fast subsequent proton abstraction by the leaving group, NH3, to form products. The mechanism is similar to that involved in the A2 hydrolysis of acetamide. Effects of substituents, R1, R2, and R3 in R1OCONR2R3, on rates can be predicted by the changes in electron densities on alkoxy oxygen and N, in complete agreement with the experimental results. We concluded that there is no need for invoking two different mechanisms for amides and carbamates since a common mechanism can easily accommodate all the experimental results.
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Chemosensory devices with self organized structures and artificial receptors are developed for a wide field of applications. Supramolecular hosts, highly ordered liquid crystal phases and even Langmuir Blodgett films are promising recognition elements. Cage compounds such as tert- butyl-calix[n]arene show high preorganization due to their rigid walls and form highly symmetrical cavities suitable for host guest inclusion of analytes. Disturbance of the highly ordered cholesteric and nematic phases influences the optical and dielectric properties of these materials.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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eng_Latn
| 31,262 |
Metastatic thyroid carcinoma arising from congenital goiter due to mutation in the thyroperoxidase gene.
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A very large cervical tumor that extended to the upper mediastinum was seen in a newborn after an uneventful pregnancy. The computed axial tomography scan confirmed the presence of a solid mass with precise limits and scattered foci of calcifications situated in the anterolateral region of the neck. The infant underwent thyroidectomy on the seventh day after birth. Pathological examination revealed a follicular carcinoma of the thyroid and probable dyshormonogenetic hyperplastic goiter. At 5 months of age, whole body scans indicated the presence of lung and bone metastases, which were treated with therapeutic doses of radioiodine. Genomic DNA was obtained from the newborn, her parents, her paternal aunt, and her paternal grandparents. Denaturing gradient gel electrophoresis analysis of PCR fragments corresponding to exon 14 of the thyroid peroxidase (TPO) gene indicated the presence of a mutant TPO allele present in the propositus, her father, and her paternal grandmother. Sequencing of the TPO gene demon...
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Here, we present the fabrication of a reduced graphene oxide-supported PdCa (PdCa/rGO) alloyed catalyst via a NaBH4 reduction method for direct alcohol fuel cells in basic medium and direct formic acid fuel cells in acidic medium. Powder X-ray diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller, inductively coupled plasma mass spectrometry, and Raman spectroscopy are used to characterize the PdCa/rGO catalyst. We proved that the calcium oxide significantly enhances the electrocatalytic methanol, ethanol, and formic acid oxidation over the Pd/rGO surface. The obtained mass activities for PdCa/rGO are 4838.06, 4674.70, and 3906.49 mA mg–1 for formic acid, methanol, and ethanol, respectively. Long-term stability, high activity, and high level of tolerance to CO poisoning of the PdCa/rGO electrocatalyst are attributed to the presence of calci...
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eng_Latn
| 31,263 |
Antimicrobial activity of Candida hordei De Miranda and Diem
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A new species of yeast,Candida hordeiDe Miranda andDiem, is able to produce an antibiotic which kills and lyses diverse microorganisms.
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Abstract The dirhodium tetraprolinate, Rh 2 ( S -DOSP) 4 is an efficient catalyst in an enantioselective C–H activation protocol. Rh 2 ( S -DOSP) 4 catalyzed decomposition of aryldiazoacetates or vinyldiazoacetates results in the formation of transient rhodium carbenoid intermediates. These intermediates are capable of selectively inserting into the C–H bond of acetals. The resulting products are protected β-keto esters, and so the C–H activation protocol can be considered as strategically equivalent to the Claisen condensation.
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kor_Hang
| 31,264 |
Synthesis, Physico-Chemical and Antimicrobial Studies of Ionic Liquid
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1 H and 13 C NMR and ESI-MS spectrometry. Thermal studies were also carried out to get thermal stability of the ionic compound. X-ray crystallographic study was carried out to ascertain the structure of ammonium cation which is bonded to three anion via O-H…Cl intermolecular hydrogen bonds. Synthesized compound was also investigated for in vitro antimicrobial study against number microbes and results showed excellent results.
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Abstract The pyrohydrolytic determination of fluoride using moist air is described for the fluoride content of plutonium fluorides on the milligram scale.
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eng_Latn
| 31,265 |
Synthesis of the 4,10-Dihydro-3H-pyridazino[1,6-b]isoquinolin-10-one System by a Furan Recyclization Reaction
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The novel 4,10-dihydro-3 H-pyridazino[1,6- B]isoquinolin-10-one heterocyclic system was synthesized by acid-catalyzed recyclization of 2-(difurylmethyl)benzohydrazides as well as by recyclization of (2-carboxyaryl)difurylmethanes to isocoumarins followed by the reaction with hydrazine hydrate.
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Coloring reaction of sake caused by exposure to sun-light was investigated. There is one of the coloring reactions in which deferri-ferrichrysin participate. The reaction was named Reaction I.Deferri-ferrichrysin, tyrosine, Mn2+ and unknown nitrogenous compound named conveniently compound X were essential for Reaction I and citric acid was stimulative.Compound X was purified by using Amberlite IR 120 (H type) column, active carbon column, silicic acid column and alumina column, and crystallized from methanol-water (1 : 1).The crystals decomposed at 288~290°C. The ultraviolet and infrared spectra of the compound X were essentially identical with those of authentic kynurenic acid.From these results the compound X was identified as kynurenic acid.Since kynurenic acid alone did not cause the color development and riboflavin could be substituted for kynurenic acid in Reaction I, kynurenic acid may act as photosensitizer in Reaction I.
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eng_Latn
| 31,266 |
Inhibition of ICAM-1 expression on endothelial cells in hypoxia/reoxygenation by antisense oligodeoxynucleotides
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AIM: To investigate the effect of antisense oligodeoxynucleotides (AS-ODN) on the intercellsular adhesion molecule-1(ICAM-1) expression on endothelial cells in hypoxia/reoxygenation(H/R). METHODS: With cultured glomerular vascular endothelial cell in H/R,the positive percentage of ICAM-1 expression was measured by flow cytometry before and after giving AS-ODN. RESULTS: The ICAM-1 expression did not increase on glomerular vascular endothelial cell in 10 hours hypoxia compared to control group,it increased in 6 hours reoxygenation, and decreased by 40.6% after giving AS-OND. CONCLUSION: AS-ODN may decrease the expression of ICAM-1 on endothelial cells in H/R.
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This work deals with the analysis of the performance and emissions of ethanol HCCI/PSCCI engines by means of a Dynamic Adaptive Chemistry (DAC) technique. The implementation of such a technique provides a reduction of the computational cost of the simulations without compromising the reliability of the results. Very accurate results, in terms of pressure and heat release rate profiles and CO, CO2 and UHC emissions, are obtained with ethanol as the only species for the DRGEP graph search both with the charge uniformly distributed in the combustion chamber and by directly injecting liquid fuel in the same chamber. The global speed up of DAC simulations is twice with respect to a full mechanism which consists of 57 species and 288 reactions and a further increase is expected when DAC is compared to very detailed kinetics.Copyright © 2012 by ASME
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eng_Latn
| 31,267 |
The use of 6-benzylaminopurine for rapid multiplication of Tillandsias
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Some species of the genus Tillandsia (Bromelioceae) are highly endangered in their natural habitats. This report introduces a method for induced lateral shoot development in atmospheric Tillandsias using the cytokinin BAP. Spraying or dipping the plants with BAP-solutions induced many lateral shoots. Even difficult-to-propagate species like T. cacticola L.B.SM developed up to 30 times more usable shoots than the control. Applying low concentrations (1 and 5 mg.L -1 ) over a longer period of time (10 weeks, 3 times a week) produced results similar to those using higher concentrations (50 mg.L -1 ) for shorter periods (2 weeks, 3 times a week). Chemical name used: 6-benzylaminopurine (BAP).
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In this letter, we report the singlet ground state structure of the full carotenoid peridinin by means of variational Monte Carlo (VMC) calculations. The VMC relaxed geometry has an average bond length alternation of 0.1165(10) Å, larger than the values obtained by DFT (PBE, B3LYP, and CAM-B3LYP) and shorter than that calculated at the Hartree-Fock (HF) level. TDDFT and EOM-CCSD calculations on a reduced peridinin model confirm the HOMO-LUMO major contribution of the Bu(+)-like (S2) bright excited state. Many Body Green's Function Theory (MBGFT) calculations of the vertical excitation energy of the Bu(+)-like state for the VMC structure (VMC/MBGFT) provide an excitation energy of 2.62 eV, in agreement with experimental results in n-hexane (2.72 eV). The dependence of the excitation energy on the bond length alternation in the MBGFT and TDDFT calculations with different functionals is discussed.
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eng_Latn
| 31,268 |
[2 + 2] Cycloaddition of Fullerenes with Electron-Rich Alkenes and Alkynes
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Photochemical [2 + 2] cycloaddition of C60 with N,N-diethyl-4-methyl-3-penten-1-yn-1-amine (1) afforded the stable C60-fused cyclobutenamine 2 which underwent self-sensitized photooxidation to dihydrofullerenone amide 4 in high yield. Fullerenes C60 and C70 react thermally with tetraalkoxyethylenes to give dihydrofullerene cyclobutanediketals, which undergo a clean cycloreversion to fullerenes on irradiation with visible or UV light. Attempted hydrolysis of the ketals was unsuccessful, but treatment of 1,2-(6161,62,62-tetraethoxycyclobutano)dihydro[60]fullerene (8) with TMSI gave ring-contracted product 11 (by cleavage of the C−C bond to the fullerene fragment) along with reduction product 12.
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In this paper we address the celebrated Albert problem for exceptional Jordan algebras (i.e. Albert algebras): Does every Albert division algebra contain a cubic cyclic subfield? We prove that for any Albert division algebra $A$ over a field $k$ of arbitrary characteristic, there is a suitable isotope that contains a cubic cyclic subfield. It follows from this that for any Albert division algebra $A$ over a field $k$, the structure group $\text{\bf Str}(A)$ always contains a subgroup of type $^3D_4$ defined over $k$.
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eng_Latn
| 31,269 |
Intermolecular vibrations of charge transfer complexes
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The intermolecular vibration band has been identified in the far infra-red spectra of the pyridine IBr and pyridine ICI charge transfer complexes. All the reported observations on these and similar complexes can be accounted by a simple 3-centre molecular orbital treatment.
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EUROPEAN SCIENCEVIENNA-- Founded in 1985, the Institute of Molecular Pathology (IMP) has put Vienna on the biomedical research map, exemplifying the promise of Austria's scientific rehabilitation. IMP's 13 research groups--which boast 120 scientific staff members from 25 nations--have done groundbreaking work in such areas as chromatid separation in yeast and cell adhesion in cancer. And more expansion is in the works.
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eng_Latn
| 31,270 |
The Kinetic Studies of Al_2O_3 Absorption CHOH
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In this study, the adsorption capacity of different properties of alumina to formaldehyde gas was researched by static adsorption. Compared to pressure conditions, the adsorption capacity was two times in vacuum conditions. At the same conditions, compared to the activated carbon, the adsorption capacity of alumina to formaldehyde gas was poorer. The results showed that alumina and activated carbon can be used as a better adsorbent to remove indoor formaldehyde gas, and the adsorption effect of aluminum hydroxide to formaldehyde gas was poorer.
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The active-site CXXC motif of thiol:disulfide oxidoreductases is essential for their catalysis of redox reactions. Changing the XX residues can perturb the reduction potential of the active-site disulfide bond of the Escherichia coli enzymes thioredoxin (Trx; CGPC) and DsbA (CPHC). The reduction potential is correlated with the acidity of the N-terminal cysteine residue of the CXXC motif. As the pKa is lowered, the disulfide bond becomes more easy to reduce. A change in pKa can account fully for a change in reduction potential in well-characterized CXXC motifs of DsbA but not of Trx. Formal analysis of the Nernst equation reveals that reduction potential contains both pH-dependent and pH-independent components. Indeed, the difference between the reduction potentials of wild-type Trx and wild-type DsbA cannot be explained solely by differences in thiol pKa values. Structural data for thiol:disulfide oxidoreductases reveal no single factor that determines the pH-independent component of the reduction potent...
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eng_Latn
| 31,271 |
Electrochemically active polymeric hollow fibers based on poly(ether-b-amide)/carbon nanotubes
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Abstract A simple and effective method to incorporate catalytic activity to a hollow fiber membrane is reported. Polyetherimide hollow fiber membranes were coated with a solution containing carboxyl-functionalized multi-walled carbon nanotubes and poly(ether- b -amide). Electron microscopy images confirmed the presence of a layer of percolating carbon nanotubes on the surface of the membranes. Cyclic voltammetry and linear swept voltammetry experiments showed that these membranes are able to drive the reactions of hydrogen evolution, and oxygen reduction, making them a cheaper, and greener substitute for platinum based cathodes in microbial bioelectrochemical systems. Water flux and molecular weight cut off experiments indicated that the electrochemically active coating layer does not affect the ultrafiltration performance of the membrane.
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Many marine bioactive compounds have medicinal and nutritional values. These bioactive compounds have been prepared using solvent-based extraction from marine bio-resources or chemical synthesis, which are costly, inefficient with low yields, and environmentally unfriendly. Recent advances in metabolic engineering allowed to some extent more efficient production of these compounds, showing promises to meet the increasing demand of marine natural bioactive compounds. In this paper, we review the strategies and statuses of metabolic engineering applied to microbial production of marine natural bioactive compounds including terpenoids and their derivatives, omega-3 polyunsaturated fatty acids, and marine natural drugs, and provide perspectives.
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eng_Latn
| 31,272 |
THE INTERACTION OF ALKALINE SOLUTIONS OF POTASSIUM BOROHYDRIDE WITH LANI4.5M0.5 (M = NI, MN, CR, CO, FE, CU, AL) INTERMETALLIC COMPOUNDS
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The behavior of LaNi4.5M0.5 (M = Ni, Mn, Cc Co, Fe, Cu, Al) interinctallic compounds (IMC) in alkaline solutions of KBH4 (0.1; 1.0; 4.0 mol L−1 KOH) Was investigated in the temperature range 298–318 K. The catalytic hydrolysis of KBH4 is zero order with respect to KBH4 and not order with respect to IMC. Activation energies of the catalytic hydrolysis of KBH4 in the presence of' IMC are in the range of 60–65 U mol−1. The rate of hydrolysis of KBH4 increases with the concentration of the KOH solution. The hydrogenation of LaNi4.5M0.5 in alkaline solutions of KBH4 yields β-hybride phases for M = Min, Cr, Co, Cu, Al and α-hybride phases for M = Ni, Fe.
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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.
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yue_Hant
| 31,273 |
Titanocene-Catalyzed Alkylation of Aryl-Substituted Alkenes with Alkyl Halides
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Aryl-substituted alkenes (ArHC=CH2) react with alkyl halides (R–X, X = Br or Cl) in the presence of a catalytic amount of [Cp2TiCl2] and nBuMgCl in Et2O to give alkylated alkenes (ArHC=CHR). This reaction proceeds regio- and stereoselectively under mild conditions to afford E-olefins. Primary and secondary alkyl bromides and secondary alkyl chlorides can be used as suitable alkylating reagents. The reactions of aliphatic alkenes, such as 1-octene and internal alkenes, were sluggish. When t-alkyl halides are employed, alkylative dimerization of alkenes proceeds exclusively to give symmetrical vic-diarylalkanes. These reactions involve addition of alkyl radicals to arylalkenes to form benzyl radicals as a carbon–carbon bond-forming step. Dimerization of thus formed benzyl radicals affords symmetrical alkanes and β-hydrogen elimination from benzyltitanocene intermediates gives alkylated alkenes. A possibility that titanocene activates alkenes as radical accepters was also proposed.
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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.
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eng_Latn
| 31,274 |
Effect of Visible Light on the Dimerization of Cobalt (II) Tetrasulfonated Phthalocyanine in Water
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Abstract Beelen and coworkers in the Netherlands recently reported that visible light enhanced the rate of selective oxidation of mercaptoethanol by dioxygen, catalyzed by cobalt (II) tetrasulfonated phthalocyanine (CoTSPC). The Dutch workers speculated that visible light promoted disaggregation of CoTSPC, producing more of the catalytically active monomer. If Beelen and associates are correct, then it is possible that the values for the dimerization constants of CoTSPC are in error. since the values were measured spectrophotometrically in the region of the spectrum where Beelen contends visible light promtes disaggregation. To test whether the dimerization constants are altered by the spectrophotometer, the absorbance of a CoTSPC solution was measured with a diode array UV-VIS spectrophotometer. By comparing the spectrum of CoTSPC in the UV region with the tungsten lamp active and then inactive, one can see whether the visible light affects aggregation. It turned out that no change was observed in the sp...
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We report on the dot-size dependence of the dephasing time T/sub 2/ value in CuCl spherical QDs, which contrasts with the existing data observed by other methods, and the respective temperature dependencies of the T/sub 2/ value in the different dot-sizes.
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eng_Latn
| 31,275 |
Photoelectronic spectroscopy and mass spectroscopy of the negative ions in molecules of cyclopropyl-substituted butadienes
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1. ::: ::: The photoelectronic spectra of the molecules of some cyclopropyl-substituted butadienes were obtained and interpreted. ::: ::: ::: ::: ::: 2. ::: ::: The processes of the formation of negative ions in dissociative capture of electrons by the molecules of these compounds were studied. The effect of the cyclopropyl groups is primarily manifested by destabilization of the molecular negative ion with respect to self-splitting of the electron.
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SummaryThe metabolism of betahistine, demethylbetahistine and 2-(2-hydroxy-ethyl) pyridine in the rabbit leads to the urinary excretion of acidic metabolities, including 2-pyridylacetate, which is excreted in part as N-2-pyridylacetylglycine. Other unidentified Koenig-positive compounds were in the acidic fraction.
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eng_Latn
| 31,276 |
A rapid and quantitative exchange of the boron hydrogens in trimethylamine borane with D2O
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New procedures are given that should greatly facilitate the synthesis of compounds labeled with deuterium or tritium with known stereochemistry to aid in the elucidation of reaction mechanisms. The homogeneous reaction of uces hydrolyze slowly to produce pure deuterium gas. Also the hydrolysis of trimethylamine borane-da in HCl produces only hydrogen gas. Large amounts of trimethylamine-d3 are obtained readily using this procedure.
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A fluorometric enzyme assay was developed to evaluate the ability of a variety of compounds to bind to and/or inhibit pyroglutamyl aminopeptidase I. Among these compounds were a series of chloromethyl ketone analogues of thyrotropin releasing hormone (TRH) which had previously been shown to possess TRH-like activity in the central nervous system and have now been found to be good inhibitors of pyroglutamyl aminopeptidase. Thus, it is suggested that the observed TRH-like CNS activity could derive indirectly from inhibition of endogenous TRH degradation by pyroglutamyl aminopeptidase I.
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eng_Latn
| 31,277 |
Enzyme histochemical alterations in human skeletal muscles after tenotomy and after spontaneous rupture of the tendon.
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The authors studied the histochemical alterations of human skeletal muscles after tenotomy and after spontaneous rupture of the tendon. Both succinate dehydrogenase (in type I fibers), and myofibrillar ATP-ase (in type 2 fibers) activity was decreased in all injured muscles. In the intact antagonists and contralateral muscles alterations were not found. The creatine phosphokinase and aldolase activity were decreased also in injured muscles. The lactate dehydrogenase activity was various both in affected and in unaffected muscles. Two weeks or more after the injury of the tendon in injured muscles the number of type 1 fibers were decreased and therefore a mathematically significant type 2 fibre predominance occurred. Atrophy involve both type 1 and type 2 fibers, but type 1 fibre atrophy was more pronunced as type 2 fibre atrophy.
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1. ::: ::: The kinetics of the phototransformation of sterically hindered phenol inorganic solvents was investigated. The singlet state is the photochemically active state. The phenol is consumed according to a first-order law. The quantum yields of the phototransformation for the investigated phenol in various solvents amount to ∼ 10−2−10−3. ::: ::: ::: ::: ::: 2. ::: ::: It was found that the phototransformation of phenol is accelerated in alcohols, and this was explained by chemical reaction of the singlet excited molecules of the phenol with oxygen. ::: ::: ::: ::: ::: 3. ::: ::: In a frozen (77°K) solution the phototransformation of sterically hindered phenol occurs by a two-quantum mechanism.
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eng_Latn
| 31,278 |
Ion‐impact‐produced secondary electron emission and its effect on space instrumentation
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Secondary electron emission produced by ion impact is shown by laboratory experiments to be the cause of an unexpected electron current observed in the OV1-18 satellite electron energy analyzer experiment. Secondary electron yield from most ionospheric ion species incident on conducting surfaces used in space instrumentation has been measured in laboratory experiments. The yields vary several orders of magnitude as the energy of ion impact varies from 10 to 300 ev. This large change in yield and the rather large values of the yield at the higher ion impact energies are evidently a consequence of the ‘gas-covered’ nature of the surfaces. A method for elimination of the unwanted current in electron energy analyzers is presented and shown to be effective.
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Abstract A synthesis and stereochemistry confirmation of a constituent recently isolated from the whole plant Isodon excisus is reported. An enantioselective catalytic boron-mediated reduction of an α-bromoketone was utilized in the key synthetic transformation. The methodology described herein was also used for the synthesis of the natural product's enantiomer and several derivatives. In addition, the compounds were evaluated for inhibitory activity in a caspase induction assay. The natural product was found to be devoid of activity, but several derivatives had moderate inhibitory activity (EC 50
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eng_Latn
| 31,279 |
Binuclear manganese complexes as catalysts in the selective and efficient oxidation of sulfides to sulfones
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The binuclear MnIVMnIV manganese complex 1 catalyzes the periodic acid oxidation of sulfides to sulfones under mild conditions. The reaction was found to be highly selective giving almost quantitative yields of the sulfones even in the presence other easily oxidized groups. Only amines were found to hinder the reaction.
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Effect on Na+ current of BmKAS-1, a novel polypeptide purified from the venom of Chinese scorpion Buthus martensi Karsch (BmK), has been investigated in differentiated NG108-15 cells by using patch-clamp whole-cell recording. Neutralizing effect of four monoclonal antibodies of BmKAS-1 (mAb #2, #3, #4, and #5) has also been observed. The results showed that Na+ current was irreversibly inhibited by BmKAS-1 and the inhibitory effect was abolished by mAb #2 and #5, but not by mAb #3 and #4.
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eng_Latn
| 31,280 |
Synthesis of Dinaphtho-dioxaphosphepin-4-oxides, Epoxides and Bisphosphonates
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A few new seven-membered phosphorus heterocyclic compounds and bis-phosphonates (5a–5g, 5f′, 5g′, 9 and 10) were prepared by the reaction of 4-bromo dioxaphosphepin (2) with various Grignard reagents followed by their oxidation with H2O2. All the compounds were thoroughly characterized by elemental analysis, IR, 1H, 13C, 31P NMR and mass spectral data. Their antimicrobial activity was evaluated and some of them possess significant activity.
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Abstract The reaction of trans -Mo(N 2 ) 2 (Dppe) 2 (Dppe = Ph 2 PCH 2 CH 2 PPh 2 ) with carbon monoxide gives, initially, the previously unknown trans -Mo(CO) 2 (Dppe) 2 , which isomerises in solution to the well-known cis isomer. The reaction was followed by IR spectroscopy under carbon monoxide pressure.
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eng_Latn
| 31,281 |
Structure-Activated Copper Photosensitisers for Photocatalytic Water Reduction
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A series of phenanthroline-based ligands have been synthesised and their influence as bidentate nitrogen ligands in heteroleptic [Cu(P^P)(N^N)]+ photosensitisers in light-driven water reduction has been studied. In this noble-metal-free Cu–Fe-based photocatalytic water reduction system, the structural effects of the nitrogen ligands have been explored, including the steric and electronic effects of substituents at the 2,9- and 4,7-positions of phenanthroline. Ligands were prepared that led to increased hydrogen generation, with turnover numbers (TONCu) of up to 1388 being observed. All the new complexes were electrochemically and photophysically characterised. We demonstrate for the first time that the presence of fluorine in nitrogen ligands increases the efficacy of copper complexes in photocatalytic hydrogen production.
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The paper reviews the development of catalytic spectrophotometric determination of nitrite, including the indicator reaction, detection limit, linear range and applications of the methods. It also puts forward the developing orientation for a high sensibility analytical method.94 references are cited.
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eng_Latn
| 31,282 |
Expression of Recombinant Chinese Bovine Enterokinase Catalytic Subunit in P. pastoris and Its Purification and Characterization
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Enterokinase is a tool protease widely utilized in the cleavage of recombinant fusion proteins.cDNA encoding the catalytic subunit of Chinese bovine enterokinase (EKL) was amplified by PCR and then fused to the 3′end ofprepro secretion signal peptide gene of α-mating factor from Saccharornyces cerevisiae to get the α-MF signal-EKL-His6 encoding gene by PCR. Then the whole coding sequence was cloned into the integrative plasmid pAO815 under the control of a methanol-inducible promoter and transformed GS 115 methylotrophic strain of Pichiapastoris. Secreted expression of recombinant EKL-His6 was attained by methanol induction and its molecular weight is 43 kD. Because of the existence of His6-tag, EKL-His6 was easily purified from P pastoris fermentation supernatant by using Ni2. affinity chromatography and the yield is 5.4 mg per liter of fermentation culture. This purified EKL-His6 demonstrates excellent cleavage activity towards fusion protein containing EK cleavage site.
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In this letter, we report the singlet ground state structure of the full carotenoid peridinin by means of variational Monte Carlo (VMC) calculations. The VMC relaxed geometry has an average bond length alternation of 0.1165(10) Å, larger than the values obtained by DFT (PBE, B3LYP, and CAM-B3LYP) and shorter than that calculated at the Hartree-Fock (HF) level. TDDFT and EOM-CCSD calculations on a reduced peridinin model confirm the HOMO-LUMO major contribution of the Bu(+)-like (S2) bright excited state. Many Body Green's Function Theory (MBGFT) calculations of the vertical excitation energy of the Bu(+)-like state for the VMC structure (VMC/MBGFT) provide an excitation energy of 2.62 eV, in agreement with experimental results in n-hexane (2.72 eV). The dependence of the excitation energy on the bond length alternation in the MBGFT and TDDFT calculations with different functionals is discussed.
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eng_Latn
| 31,283 |
[Effects of diazoxide on the mitochondrial membrane potential and ROS generation in rat uterus cells].
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In the present study we demonstrate partial depolarization of the mitochondrial inner membrane from the rat uterus cells upon activation of mitochondrial ATP-sensitive K(+)-channel (mitoK(ATP)) with diazoxide. The estimated affinity constant of diazoxide to mitoK(ATP) from rat uterus cells is (5.01 +/- 1.47) 10(-6) M. We also observed an enhanced generation of reactive oxygen species after addition of diazoxide. Both effects were effectively eliminated by glybenclamide, blocker of the ATP-sensitive K+ channel. Our results indicate that activation of mitoK(ATP) in rat uterus cells leads to a partial depolarization of mitochondrial membrane and an increase in ROS concentration.
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Abstract In order to study the size distribution of a radioactivity due to radon daughters in the environmental atmosphere, an experimental procedure using filters, ion tubes, diffusion batteries and cascade impactors (CASELLA MK2 and ANDERSEN) is presented. A comparison between the experimental results and a theoretical curve, deduced of the attachment theory of the small radioactive ions on atmospheric particles, is carried out.
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eng_Latn
| 31,284 |
Excessive iron storage in a patient with Wilson's disease
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We report on an otherwise healthy female, mother of two children, with severe decompensated liver cirrhosis due to an iron overload and Wilson's disease. The patient was considered heterozygote for hemochromatosis on the basis of the autosomal recessive inheritance for hemochromatosis, the frequency of the hemochromatosis gene, and the laboratory parameters defining her iron overload. The case is interesting because of the coincidence of Wilson's disease and excessive iron storage.
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Abstract Supporting Wilkinson's complex on γ-Al 2 O 3 rendered a high active catalyst for cyclohexene to cyclohexane hydrogenation. The activity was higher than that of the same complex unsupported, in the presence or absence of a S-containing poison (tetrahydrothiophene). XPS results suggested that, after poisoning, there was an insertion of a sulfur atom into the rhodium coordination sphere. Comparison of Wilkinson's complex with other palladium and nickel complexes was also made. The Wilkinson's complex proved to be more active and sulfur resistant than the Pd and Ni complexes in both homogeneous and heterogeneous conditions. For the Pd and Ni complexes there was a change in the coordination sphere after poisoning, as shown by the XPS results.
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eng_Latn
| 31,285 |
Synthesis of Aurones and Their Inhibitory Effects on Nitric Oxide and PGE2 Productions in LPS-Induced RAW 264.7 Cells.
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Aurones (IIIe) and (IIIf), which possess a C-6 hydroxyl group in the A-ring and methoxy substituents in the B-ring, inhibit the NO and PGE2 production more efficiently than sulfuretin and are less cytotoxic.
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A generalized model that describes apparently “non-Nernstian” equilibrium responses of ionophore-based ion-selective electrodes (ISEs) is presented. It is formulated for primary and secondary ions of any charges that enter the membrane phase and independently form complexes with the ionophore, respectively. Equations for the phase boundary potential model were solved numerically to obtain whole response curves as a function of the sample activity of the primary ion, and analytical solutions could be obtained for apparently non-Nernstian response sections in these response curves. Ionophore-based ISEs can give three types of apparently non-Nernstian equilibrium responses, i.e., apparently “super-Nernstian”, “inverted-Nernstian”, and “sub-Nernstian” responses. The values of the response slopes depend on the charge numbers of the primary and secondary ions and on the stoichiometries of their complexes with the ionophore. The theoretical predictions for super-Nernstian responses agree well with the experiment...
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eng_Latn
| 31,286 |
Why Is There a Barrier in the Coupling of Two Radicals in the Water Oxidation Reaction
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Two radicals can form a bond without an energetic barrier. However, the radical coupling mechanism in ruthenium-catalyzed water oxidation has been found to be associated with substantial activation energies. Here we have investigated the coupling reaction of [Ru═O(bda)L2]+ catalysts with different axial L ligands. The interaction between the two oxo radical moieties at the Ru(V) state was found to have a favorable interaction in the transition state in comparison to the prereactive complex. To further understand the existence of the activation energy, the activation energy has been decomposed into distortion energy and interaction energy. No correlation between the experimental rates and the calculated coupling barriers of different axial L was found, showing that more aspects such as solvation, supramolecular properties, and solvent dynamics likely play important roles in the equilibrium between the free RuV═O monomer and the [RuV═O···O═RuV] dimer. On the basis of our findings, we give general guidelines...
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Background/Aims: Oxidative stress is involved in Alzheimer disease pathology, but its impact on cognitive function in community-dwelling older adults remains unkn
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eng_Latn
| 31,287 |
Structure of indoline spiropyrans containing a fused coumarin fragment: Quantum-chemical investigation
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In order to examine the way of fusion of the coumarin fragment to the 2H-pyran part of indoline spiropyrans the relative stability was estimated of the cyclic and merocyanine forms by means of calculations in the framework of DFT in B3LYP/6-31G(d,p) approximation. In agreement with the experimental data the relative stabilization of the spirocyclic isomer correlates with the length of the bond where the fusion occurs.
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Planktonic foraminifer, temperature dependent and temperature independent variations, similar variations observed from three ecologically distinct regions, direction of coiling not related to temperature, Quaternary, Atlantic Ocean, Caribbean Sea
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eng_Latn
| 31,288 |
The invention of new radical chain reactions. Part VIII. Radical chemistry of thiohydroxamic esters; A new method for the generation of carbon radicals from carboxylic acids
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Abstract The aliphatic and alicyclic esters of N-hydroxypyridine-2-thione are readily reduced by tributylstannane in a radical chain reaction to furnish nor-alkanes. 1 In the absence of the stannane a smooth decarboxylatlive rearrangement occurs to give 2-substituted thiopyridines. 1 The radicals present in this reaction provoke with t -butylthiol an efficient radical reaction with formation of nor-alkane and 2-pyridyl- t -butyl disulphide. 1 Similarly these carbon radicals can be captured by halogen atom transfer to give noralkyl chlorides, bromides and iodides. 2 With oxygen in the presence of t-butylthiol the corresponding noralkyl hydroperoxides are formed in another radical chain reaction. 3
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We have carried out molecular dynamics (MD) simulations and free energy calculations on the α-subtype of the human estrogen receptor ligand-binding domain (ERα LBD) complexed with a number of known agonists and putative xenoestrogens. Our dynamical simulations of ligand−receptor complexes underscore the highly structured nature of the complex and offer some interesting insights into the structure−activity relationship (SAR) for these ligands. With traditional thermodynamic integration (TI) calculations, we calculate relative binding free energies for three known agonists, in good agreement with experimental values. The sheer number of possible xenoestrogenic compounds makes an approach using traditional free energy calculations unfeasible. Instead, we have made use of a single-step perturbation methodology that allows the calculation of relative free energies for a large number of related polyaromatic hydrocarbons (PAHs) from a single simulation. Our results show good (maximum deviation 3.3 kJ mol-1) agre...
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eng_Latn
| 31,289 |
A Convenient Synthetic Route to Spiro[indole-3,4'-piperidin]-2-ones
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Starting from 1-[(tert-butoxy)carbonyl]piperidine-4-carboxylic acid and 2-bromoaniline, the spiro[indole-3,4′-piperidin]-2-one system was obtained in three high-yielding steps: anilide formation, N(1)-protection, and intramolecular cyclization under Pd catalysis as the key reaction. The preparation of the corresponding 2-bromoanilide was studied. In extension, the same sequence was developed with 4-methyl- and 4-nitro-2-bromoaniline. In the key step, the NO2 group led to a rather diminished yield. The transformation of the protected spiro[indole-3,4′-piperidin]-2-one to the corresponding unprotected dihydroindoles is discussed.
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Flow Injection (FI) techniques for use with Atomic Absorption Spectrometry (AAS) ::: have attracted considerable research interest for sample introduction and calibration ::: strategies. The interest continues in on-line preconcentration and matrix modification ::: which are carried out by the incorporation of liquid-liquid extraction, ion-exchange, ::: immobilised reagents, gas/vapour generation and continuous precipitation-filtration ::: devices into suitably designed manifolds. Indirect determination of inorganic anions and ::: organic compounds is becoming routine by FI–flame AAS. The direct analysis of solid ::: samples, which is a shortcoming of flame AAS, was recently carried out by on-line ::: electrolytic dissolutions. [Continues.]
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eng_Latn
| 31,290 |
Triptinins A and B, two leukotriene D4 antagonistic 19(4→3)-abeo-abietanes from Tripterygium wilfordii
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Abstract Bioassay-directed separation of an ethanolic extract of the roots of Tripterygium wilfordii furnished two new 19(4→3)- abeo -abietanes, triptinin A and B, along with two known diterpenes, triptoquinone A and 11-hydroxy-14-methoxy-19(4→3)- abeo -abieta-3, 8, 11, 13-tetraen-19-oic acid, as leukotriene D 4 antagonist constituents. The structures of these diterpenes were elucidated by spectroscopic methods.
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Abstract A microscopic form factor for the process 6 Li → α + d is derived by summing a realistic nucleon-nucleon interaction between the nucleons in the alpha and deuteron clusters within a fully antisymmetrized 6 Li wave function and integrating over the internal coordinates of the clusters. The form factor is employed in finite-range DWBA calculations of the ( 6 Li, d) and (d, 6 Li) reactions and in general provides a good description of the shapes of the angular distributions. However, the spectroscopic factors for ( 6 Li, d), (d, 6 Li), and those calculated from the shell model are in poor agreement.
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eng_Latn
| 31,291 |
TGF-β signaling is activated in patients with chronic HBV infection and repressed by SMAD7 overexpression after successful antiviral treatment
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Objectives ::: Although animal studies demonstrated that Smad7 induction ameliorates TGF-β/SMAD-mediated fibrogenesis, its role in human hepatic diseases is rather obscure. Our study explored the activation status of TGF-β/activin pathway in patients with chronic liver diseases, and how it is affected by successful antiviral treatment in chronic HBV hepatitis (CHB).
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Abstract Amino modified SBA-15 (SBA-NH 2 ) was used to immobilize vanadyl (VO 2+ ) and cupric (Cu 2+ ) ions, giving SBA-NH 2 -VO 2+ and SBA-NH 2 -Cu 2+ catalysts, respectively, and the as-prepared catalysts were characterized by XRD, XPS, TEM and Nitrogen adsorption–desorption technologies. The catalytic performance of the SBA-NH 2 -VO 2+ catalysts for the oxidation of HMF can be enhanced by the use of SBA-NH 2 -Cu 2+ as the co-catalyst. Several important reaction parameters were investigated, and it was found that the reaction solvent showed a great effect on the oxidation of HMF. The highest HMF conversion and product selectivity were obtained in aromatic solvents. The highest HMF conversion reached 98.8% at 110 °C in 4-chlorotoluene, affording DFF and 2,5-furandicarboxylic acid (FDCA) with yields of 28.9% and 62.7%, respectively. More importantly, the catalysts could be recycled and showed no significant decrease of their catalytic activities.
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eng_Latn
| 31,292 |
HPLC of Fluorescent Products of Acetaminophen Reaction with Peroxidase
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Abstract HPLC was utilized in this work to follow the progress of the reaction of acetaminophen and hydrogen peroxide in the presence of horseradish peroxidase. Several fluorescent as well as ultraviolet-detectable compounds where detected and separated by HPLC on a reversed-phase column. These reaction products are polymers of acetaminophen. The compounds are stable and fluoresce directly over a wide pH range without the need for further chemical reactions. Surfactants enhance the fluorescence intensity. The fluorescent compounds have several potential practical applications as sensitive tests for: hydrogen peroxide, peroxidase activity and also as an indicator reaction for coupled enzymatic assays such as glucose and uric acid.
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Activity coefficients of hexane, heptane, methyl cyclo-hexane, benzene, toluene, ethyl benzene, o-, m-, p-xylene at infinite dilution in polystyrene-volatile component systems are determined by GLPC method. The relation may be expressed as following equation:with an error less than 5 % to the experimental data.
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eng_Latn
| 31,293 |
Oxoanion influences on the self-assembly of cationic co-ordination complex polymers of the nickel(II)–di-4-pyridylamine family
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Hydrothermal reactions of NiII, di-4-pyridylamine (dpa) and the appropriate oxide yield materials of the NiII–organodiamine–EO42– family. Specifically, reaction of NiCl2·6H2O, dpa, and MoO3 in water at 120 °C yielded [Ni(dpa)2(MoO4)] 1, while the reaction of NiSO4·6H2O and dpa in water at 120 °C gave [Ni(dpa)(SO4)(H2O)]·2H2O 2. The structures reveal the dramatic influence of the anion identity and ligation modes in the {Ni(dpa)n}n2n+ substructure. The structure of 1 is constructed from two motifs, two-dimensional {Ni(dpa)}n2n+ sheets and one-dimensional {NiMoO4}n chains, to produce a three-dimensional covalently linked framework. In contrast, the {Ni(dpa)}n2n+ substructure of 2 is three-dimensional, with co-ordinated SO42– and aqua ligands projecting into channels formed by the {Ni(dpa)}n2n+ framework. The void is reduced through the common characteristic of interpenetration, such that the structure of 2 exhibits two independent three-dimensional frameworks.
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Photocatalytic oxidation has broad application prospects in water pollution control due to its efficient removal of trace refractory organics without secondary pollution.The types and characteristics of emerging organic contaminants were described.The reaction mechanism of photocatalytic oxidation was analyzed.The treatment effect and research progress of various endocrine disrupting compounds and pharmaceuticals and personal care products by photocatalytic oxidation were illustrated in detail.Moreover,the problems and the tendency of future prospective technology development were also discussed.
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eng_Latn
| 31,294 |
Notes on some field experiments mainly with dieldrin formulations.
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Dieldrin is effective as a larvicide in a variety of breeding places against local anophelines. A high spreading anti-malarial oil containing dieldrin has been as effective as a similar preparation with D.D.T., and may be used in similar circumstances. Dieldrin W.P. 25 percent, used at a dosage of 2 oz. per acre, gave adequate control of anophelines in pools of standing water for at least 14 days. In pools which were treated several times, a cumulative effects appeared which gave control for a much longer period. Increased dosage gave increasing control and only where applications reached 1/2 lb. and 1 lb. per acre, were any ill effects noted on other forms of animal life in the treated water bodies. Compared with similar formulations of D.D.T. and B.H.C., dieldrin W.P. 25 percent gave better results than either at the standard recommended rates of application. In large scale field trials, dieldrin W.P. 25 percent gave adequate control for periods of at least 14 days after application. (AU)
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1. ::: ::: On the basis of obtained kinetic and thermodynamic parameters of the reaction of the reversible recombination of the 2-(4′-dimethylaminophenyl)indan-1,3-dionyl radical, it is established that the most dominating influence on the rate of this reaction is nonspecific solvation. ::: ::: ::: ::: ::: 2. ::: ::: Values of rate constants of the recombination of the 2-(4′-diphenylaminophenyl)indan-1,3-dionyl radical has a V-shaped dependence on the parameter ET, Strong solvation of this radical in chloroform converts the recombination reaction from a diffusion-controlled range to a kinetic range.
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eng_Latn
| 31,295 |
The study of VUV emissions of Ar*2 excimers using three-photon absorption laser-induced fluorescence
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The VUV emissions of the second continuum of argon at ~130 nm were investigated for pressures ranging from 100 to 600 Torr after selectively populating the resonant atomic state of the 3p54s configuration of argon by using three-photon absorption laser-induced fluorescence. For brief and selective excitation conditions, a kinetic study was performed by analysing the VUV postluminescence decay of argon. This study clearly shows that only three-body collisions lead to the formation of the excimer Ar2(A1u). The three-body decay rate constant of the metastable state Ar4s[3/2]02 was measured for the first time under selective excitation (k'3 = (19.5 ± 2.1) Torr−2 s−1). The role of the first resonant and metastable states of argon in the formation of excimers responsible for the VUV emissions is discussed. A kinetic scheme showing the main reaction processes is proposed and compared with those already obtained with other rare gases.
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The present paper reports on the effects of UV-A light on the catalase activity of the calf eye vitreous. A total of 26 eyes were irradiated with UV-A light for 3 h and the catalase activity was compared with that of unirradiated eyes. An increase in activity by 33% was shown in the irradiated eyes. The reason for this increase is the induction of radical formation by short-wave light with subsequently intensified catalase formation or release to enable binding of the radicals formed by the cells. The vitreous must therefore be protected from UV-A light.
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eng_Latn
| 31,296 |
Treatment of cutaneous sarcoidosis with chloroquine. Review of the literature.
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Systemic corticosteroids may be either contraindicated or not efficacious in treating the cutaneous manifestations occurring in 20% to 35% of patients with systemic sarcoidosis. Chloroquine phosphate has been reported to be a valuable alternative therapy for cutaneous lesions of sarcoidosis. With a judiciously determined daily dosage and regular 6-month ophthalmologic follow-up examinations, the risk of developing retinopathy can be avoided, because the daily dosage rate rather than total dose accumulation determines the development of chloroquine-induced retinopathy. We reviewed the efficacy and safety of chloroquine and its role in the treatment of cutaneous sarcoidosis.
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A new NADPH-dependent benzil reductase (KRED1-Pglu) was identified from the genome of the non-conventional yeast Pichia glucozyma CBS 5766 and overexpressed in E. coli. The new protein was characterised and reaction parameters were optimised for the enantioselective reduction of benzil to (S)-benzoin. A thorough study of the substrate range of KRED1-Pglu was conducted; in contrast to most other known ketoreductases, KRED1-Pglu prefers space-demanding substrates, which are often converted with high stereoselectivity. A molecular modelling study was carried out for understanding the structural determinants involved in the stereorecognition experimentally observed and unpredictable on the basis of steric properties of the substrates. As a result, a new useful catalyst was identified, enabling the enantioselective preparation of different aromatic alcohols and hydroxyketones.
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eng_Latn
| 31,297 |
4-Chloro-2-aminophenol-5- and -6-sulphonic Acids, their Characterisation and Differentiation
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Owing to the similarity in the properties of pairs of dyes made by coupling diazotised 4-chloro-2-aminophenol-5- and -6-sulphonic acids with the same coupling component, the identity of the former compound was open to suspicion. Consequently, 4-chloro-2-aminophenol-5-sulphonic acid has been prepared by sulphonating 5-chlorobenzoxazolone and then hydrolysing the 5-chloro-benzoxazolone-6-Bulphonic acid. 4-Chloro-2-aminophenol-5- and 6-sulphonic acids have been characterised by conversion into 5-chlorobenzoxazolone-6- and -7-sulphonic acids, from which the S-benzylthiuronium and p-toluidine salts were prepared. These derivatives possess satisfactory melting points and are suitable for the identification of 4-chloro-2-aminophenol-5- and -6-sulphonic acids. The preparation of 2-amino-phenol-5-sulphonic acid from o-aminophenol via benzoxazolono is described, and 2-aminophenol-4- and -5-sulphonic acids also are readily identified by means of their S-benzylthiuronium and p-toluidine salts.
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Electronic and geometric structures at the water-amorphous silica nanoparticle (NP) interface are determined as a function of suspension pH using a combination of X-ray photoelelectron spectroscopy (XPS) from a liquid microjet, solid-state nuclear magnetic resonance (NMR), and density functional theory (DFT). We provide direct spectroscopic evidence of the existence of (de)protonated silanol groups at the liquid–NP interface and give a microscopic description of the interface structure. The (de)protonated silanol groups, ≡Si–OH2+ and ═Si–(OH)(OH2+) in acidic suspension and ≡Si–O– and ═Si–(OH)(O–) in basic, give rise to well-resolved peaks in the Si 2p spectra that allow their identification and subsequent assignment by DFT. The change in surface potential at the silica NP surface as a function of pH can be directly measured by XPS and allows for an estimate of the fraction of silanol groups that become (de)protonated at the pH of the experiments. In agreement with DFT calculations, NMR is unable to direct...
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eng_Latn
| 31,298 |
Taurine in the hippocampal formation of the Senegalese baboon, Papio papio: an immunocytochemical study with an antiserum against conjugated taurine
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An antiserum raised against taurine conjugated to bovine serum albumin by glutaraldehyde produced intense staining of hippocampal pyramidal neurons at the CA1/CA3 transition (including CA2) and of a small proportion of the granule cells. Strongly immunoreactive neurons were also found in a zone overlapping the second reflected blade in the hilus. Most glial cells were unlabeled.
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Abstract Amino modified SBA-15 (SBA-NH 2 ) was used to immobilize vanadyl (VO 2+ ) and cupric (Cu 2+ ) ions, giving SBA-NH 2 -VO 2+ and SBA-NH 2 -Cu 2+ catalysts, respectively, and the as-prepared catalysts were characterized by XRD, XPS, TEM and Nitrogen adsorption–desorption technologies. The catalytic performance of the SBA-NH 2 -VO 2+ catalysts for the oxidation of HMF can be enhanced by the use of SBA-NH 2 -Cu 2+ as the co-catalyst. Several important reaction parameters were investigated, and it was found that the reaction solvent showed a great effect on the oxidation of HMF. The highest HMF conversion and product selectivity were obtained in aromatic solvents. The highest HMF conversion reached 98.8% at 110 °C in 4-chlorotoluene, affording DFF and 2,5-furandicarboxylic acid (FDCA) with yields of 28.9% and 62.7%, respectively. More importantly, the catalysts could be recycled and showed no significant decrease of their catalytic activities.
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eng_Latn
| 31,299 |
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