固体聚合物电解质在肉桂醇电解氧化中的应用(II)——后续化学反应在电催化反应中的地位及其影响因素

对影响肉桂醇电极氧化的各种因素作了进一步的讨论. 实验结果表明固体聚合物电解质内水的含量、pH 以及浸入离子交换膜中的二价锰离子的浓度均对该电极反应的电位以及后续化学反应的速度有很大的影响, 在较高的温度下反应时, 有利手提高生成肉桂醛的电流效率.     

固体聚合物电解质在肉桂醇电解氧化中的应用(Ⅱ)——后续化学反应在电催化反应中的地位及其影响因素

对影响肉桂醇电极氧化的各种因素作了进一步的讨论.实验结果表明固体聚合物电解质内水的含量、pH 以及浸入离子交换膜中的二价锰离子的浓度均对该电极反应的电位以及后续化学反应的速度有很大的影响,在较高的温度下反应时,有利手提高生成肉桂醛的电流效率.     

Impregnated fly ash sorbent for cesium-137 removal from water samples

Journal of Radioanalytical and Nuclear Chemistry - Cesium-137 is an important indicator of radioactive pollution in the aquatic environment. The aim of this study was to increase the sorption...     

Conversion Natural Gas to Ci Hydrocarbons via Cold Plasma Reaction

Natural gas is not only an increasing important role in energy and chemicals supplies in 21st century but also the second most important of the greenhouse gases^[1]. For the past 200 years atmospheric methane concentrations have increased from 0.8 to 1.65ppm. This change in methane concentration had been led to an estimated increase in radiative forcing of climate of 0.47 W/m² compared to the increase of 1.56 W/m² due to the change in carbon dioxide concentration over a comparable time period^[2]. With large increases in natural gas reserves proven worldwide, it can be expected that natural gas will play an increasing important role in humanity future. Cold plasma chemical processing is a promising route for synthesis of chemicals that have high activation energies, because electric field can be excite reactant to the plasma and many kinds of reactive particles, electrons, free radicals, ions metastable species and photons are produced in a plasma chemical processing system.     

Effect of ozone oxidation on single-walled carbon nanotubes

Exposing single-walled carbon nanotubes to room-temperature UV-generated ozone leads to an irreversible increase in their electrical resistance. We demonstrate that the increased resistance is due to ozone oxidation on the sidewalls of the nanotubes rather than at the end caps. Raman and X-ray photoelectron spectroscopies show an increase in the defect density due to the oxidation of the nanotubes. Using ultraviolet photoelectron spectroscopy, we show that these defects represent the removal of pi-conjugated electron states near the Fermi level, leading to the observed increase in electrical resistance. Oxidation of carbon nanotubes is an important first step in many chemical functionalization processes. Because the oxidation rate can be controlled with short exposures, UV-generated ozone offers the potential for use as a low-thermal-budget processing tool.     

Formation of rodlike structures of water between oppositely charged ions in decane and polyethylene

The Gibbs ensemble Monte Carlo method has been combined with the connectivity altering osmotic Gibbs ensemble to study water solubility and clustering in decane and polyethylene. We show that the presence of oppositely charged ion pairs that have fixed positions in the hydrocarbon matrices leads to an order of magnitude increase in the water solubility. This is important to a wide range of technical applications, since the uptake of the water leads to an increase in volume--or expansion--of the hydrocarbon phase which, in the case of polyethylene, may change the polymer properties and lead to water treeing. The increase in solubility is largest when the ions are sufficiently close so that rod-shaped clusters of water molecules form between the ions.     

Importance of temperature effect on the electrophoretic behavior of charge-regulated particles

The Joule heating effect is inevitable in electrophoresis operations. To assess its influence on the performance of electrophoresis, we consider the case of a charge-regulated particle in a solution containing multiple ionic species at temperatures ranging from 298 to 308 K. Using an aqueous SiO(2) dispersion as an example, we show that an increase in the temperature leads to a decrease in both the dielectric constant and the viscosity of the liquid phase, and an increase in both the diffusivity of ions and the particle surface potential. For a particle having a constant surface potential, its electrophoretic mobility is most influenced by the variation in the liquid viscosity as the temperature varies, but for a charged-regulated particle both the liquid viscosity and the surface potential can play an important role. Depending upon the level of pH, the degree of increase in the mobility can be on the order of 40% for a 5 K increase in the temperature. The presence of double-layer polarization, which is significant when the surface potential is sufficiently high, has the effect of inhibiting that increase in the mobility. This implies that the influence of the temperature on the mobility of the particle is most significant when the pH is close to the point of zero charge.     

The Synthetic Strategy toward of ACE-Inhibitors

Angiotensin II is an important octapeptide which is responsible for the increase in blood pressure in three major mechanisms. It acts as a hormone to attack the receptor on the blood vessels, which cause strong vasoconstriction. It is also the major stimulus for release another hormone, aldolsterone, which promote the excretion of potassium ion and retention of sodium and waster. Both of the above effects increase the blood pressure. On the other hand, ACE (Angiotensin Converting Enzyme) catalyzes the hydrolysis of bradykinin that is a potent vasodilator. Therefore, the inhibitor of ACE can act as an efficient anti-hypertensive agent through multiple routes.     

Determination of Atmospheric Methyl Bromide by Gas Chromatography

The bromomethane is an important substance for the destruction of ozone layer. Its source from mankind release is mainly agricultural use as soil fumigant and pesticide. Khalil et al. derived an annual increase of (3±1)% for the globe their content in the atmosphere during 1988-1992 through a detailed analysis of an extended series of sampling of CH₃Br.     

Nonvolatile resistive memory of ferrocene covalently bonded to reduced graphene oxide

Recently, the number of studies concerning organic memory devices has grown rapidly due to increase in the demand for electronic devices. Among the organic memory devices, the development of organic nonvolatile memory materials and devices is becoming an important research topic due to their low power consumption.     

Multipurpose biological reference materials

Summary Reference materials to meet multipurpose needs for analysis of both inorganic and organic constituents in biological investigations are not readily available. A human total diet material is being investigated as a reference material for a wide variety of constituents of interest to human nutrition and health. This material shows a stable assay value for the natural levels of a number of vitamins following freeze-drying or radiation sterilization. This is an important feature in producing materials for long term stability as a Reference Material for natural levels of these constituents. An exception is an increase of 34% in assay value of folic acid upon freeze-drying and an 85% increase upon freezedrying followed by radiation sterilization.

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Vielseitig verwendbare biologische Referenzmaterialien

     

聚氧乙烯醚类表面活性剂表面扩张粘弹性质研究

研究了非离子表面活性剂壬基苯酚聚氧乙烯醚NP-8, NP-10和NP-12水溶液的表面扩张粘弹性质, 考察了氧乙烯数的变化对表面吸附膜特性的影响. 研究结果表明, 三种表面活性剂的扩张弹性随着工作频率的增大而增大, 扩张粘性则在0.1~0.01 Hz范围内通过不明显的极大值; 扩张弹性和粘性随着浓度的增加在同一浓度处通过一个极大值; 氧乙烯数从8增加到12, 表面扩张弹性、粘性和相角的变化不大. 从发生在表面上和表面附近的微观弛豫过程的角度对实验结果进行了讨论.     

Physicochemical Properties of Profiled Heterogeneous Ion-Exchange Membranes

Optimum values of parameters of hot pressing of heterogeneous ion-exchange membranes MK-40 and MA-40 (temperature, pressure, exposure duration) with the aim of creating geometrical profiles on their surfaces are determined. A method of optical visualization of membrane profiles and a diffusion technique of diagnostics of through pores in the membranes are developed and substantiated. Most important physicochemical and physicomechanical characteristics of profiled membranes are investigated. It is shown that the major obstacle in the production of profiled cation-exchange heterogeneous membranes is encapsulation of grains of the ion-exchange resin by an inert polyethylene film, which leads to an increase in the surface resistance of the membranes and to a decrease in the fraction of their active surface areas. The profiling of heterogeneous anion-exchange membranes is accompanied by an increase in their microscopic porosity and diffusion penetrability.     

Influence of morphology on electric conductance in poly(ethylene naphthalene-2,6-dicarboxylate)

Polymers find an important field of application in the electrical industry because of their utilization as insulators and dielectrics. The challenge over the last several years has been to make electrical compounds smaller in size. In that way the material morphology is of strategic importance in the performance of new components in relation to their geometry. Therefore, it is important to know the influence of different types of stress on electric properties of the materials. We have studied the influence of the crystallinity on electric conductance of poly(ethylenenaphthalene-2,6-dicarboxylate) (PEN), which is increasingly replacing some dielectrics (polypropylene and PET) in certain electric applications. Starting from an amorphous PEN, samples with various crystallinities were obtained and analyzed using DSC in order to determine their thermal characteristics. Moreover, measurements of charge and discharge currents were carried out on PEN samples to characterize their electric properties. The steady state current observed after 120 min, in response to the electric field, shows an increase in the insulator resistivity with the crystallinity. The increase in the crystallinity favors a decrease in the free volume, so the movement of charges is restricted especially by the species of large sizes.     

Picosecond kinetics of tetracene dianions

Autoionization is a possible mechanism for the picosecond kinetics of tetracene dianion di-potassium salt (TeT^2?, 2K⁺) in DME and MeTHF. We have observed an intermediate absorption by what we believe to be an important extension of the experimental methods of picosecond spectroscopy. This double beam method provides an improvement over an order of magnitude increase in sensitivity and reliability over our previous electronically displayed techniques.     

Crystal polymorphism and spectroscopical properties of sulfonamides in solid state by means of First Principles calculations

Journal of Computer-Aided Molecular Design - Sulfonamides are an important class of therapeutic agents. The increase in the number of new sulfonamide derivatives makes it necessary to study more...     

New High-Temperature Polymers. II: Ordered Aromatic Copolyamides Containing Fused and Multiple Ring Systems

Thermostable polymers and, more particularly, thermostable fibers and films are becoming more and more important as the demands of space-age technology increase. In the preparation of thermostable fibers having good tensile strengths and practical utility the processibility of the polymer is of great importance. Aromatic polyamides meet the two most important requirements: a high degree of thermal stability and an ease of preparation as viscous solutions that can be spun into fibers or cast into films.     

LIPID PEROXIDATION AND OTHER MEMBRANE DAMAGE PRODUCED IN Escherichia coli K1060 BY NEAR-UV RADIATION AND DEUTERIUM OXIDE

Abstract— With accumulating evidence that the membrane is an important site for near-UV inactivating events, we have investigated the effects of near-UV radiation on the unsaturated fatty acid auxotroph E. coli K1060 following incorporation into the membrane phospholipids of fatty acids with varying degrees of unsaturation. Sensitivity, lipid peroxidation and membrane damage, as determined by ⁸⁶Rb⁺ leakage, have been found to increase with increasing unsaturation in log-phase cells. Similar experiments carried out in D₂O also show an increase in sensitivity, lipid peroxidation and membrane damage, indicating that singlet oxygen may be responsible for such near-UV-radiation-induced damage     

THE FTIR STUDIES OF PHOTO-OXIDATIVE DEGRADATION OF POLYPROPYLENE

The photo-oxidative degradation process of polypropylene film containing iron ions was investigated via FTIR and absorbance substraction technique. It is shown that the iron ions play an important role in the decomposition of hydroperoxide and the increase of the degradation rate of polypropylene film. The amorphous region of PP film undergoes degradation prior to the crystalline one.