环取代基对金属化聚苯胺衍生物膜修饰电极性能的影响

通过比较聚2，5－二甲氧基苯胺（PDMAn）、聚邻甲基苯胺（POT）和聚间氯苯胺（PmClAn）膜修饰电极的氧化还原电位、沉积在这3种聚合物上的铂微粒的表面形态与晶面取向以及异丙醇在分散Pt微粒的聚苯胺膜修饰电极上的氧化行为，从电子效应和立体效应探讨了聚合物电化学性质与环取代基的关系以及不同聚合基质对Pt沉积机理和有催化性能的影响,结果表明，在硫酸溶液中PDMAn膜修饰电极的氧化还原电位最负、POT次之、PmClAn最正，Pt在PDMAn和POT膜上的电沉积机理与在PmClAn膜上的不同，聚合物膜上沉积的Pt微粒呈现（200)晶面择优取向，其中POT膜上择优取向度最大，PDMAn次之，Pm-ClAn最小，异丙醇在金属化聚合物膜电极上的氧化电位取决于聚苯胺的本质，在POT膜修饰电极上异丙醇的电氧化主要发生在POT的活性电位区，而在PDMAn与PmClAn膜上的电氧化则主要发生在Pt上的氧化电位区，说明聚合物膜不仅作为Pt微粒的分散介质，而且本身有产生催化作用。     

Influence of Mg^2＋ on Initial Stages of CaCO3 Scale Formed on Metal Surface

Magnesium ions, which exist in formation water and injection water under downhole conditions in the oil and gas production industry, are a key determinant in the CaCO3 scale formation. Many studies have focused their attention on the effect of magnesium on the kinetics, the morphology and the content of Mg in the Ca-CO3 scale. Little attention has been paid to the effect of Mg^2 on the initial stages of CaCO3 formation on a metal surface. In this study, an electrochemical technique was used to study the influence of Mg^2 on the ini-tial stages of CaCO3 scale formed on a metal surface. With this electrochemical technique, the reduction of the dissolved oxygen in an analysis solution is considered on the surface of a rotating disk electrode (RDE) un-der potentiostatic control. The rate of oxygen reduction on the surface of the RDE enables the extent of sur-face coverage of scale to be assessed. With this electrochemical technique, a new insight into the effect of Mg^2 on CaCO3 scale formed on a metal surface is given.     

Review on subsurface colloids and colloid-associated contaminant transport in saturated porous media

In this review article, the authors present up-to-date developments on experimental, modeling and field studies on the role of subsurface colloidal fines on contaminant transport in saturated porous media. It is a complex phenomenon in porous media involving several basic processes such as colloidal fines release, dispersion stabilization, migration and fines entrapment/plugging at the pore constrictions and adsorption at solid/liquid interface. The effects of these basic processes on the contaminant transport have been compiled. Here the authors first present the compilation on in situ colloidal fines sources, release, stabilization of colloidal dispersion and migration which are a function of physical and chemical conditions of subsurface environment and finally their role in inorganic and organic contaminants transport in porous media. The important aspects of this article are as follows: (i) it gives not only complete compilation on colloidal fines-facilitated contaminant transport but also reviews the new role of colloidal fines in contaminant retardation due to plugging of pore constrictions. This plugging phenomenon also depends on various factors such as concentration of colloidal fines, superficial velocity and bead-to-particle size ratio. This plugging-based contaminant transport can be used to develop containment technique in soil and groundwater remediation. (ii) It also presents the importance of critical salt concentration (CSC), critical ionic strength for mixed salt, critical shear stressor critical particle concentration (CPC) on in situ colloidal fines release and migration and consequently their role on contaminant transport in porous media. (iii) It also reviews another class of colloidal fines called biocolloids and their transport in porous media. Finally, the authors highlight the future research based on their critical review on colloid-associated contaminant transport in saturated porous media.     

Surface-enhanced Raman scattering of a series of n-hydroxybenzoic acids (n = P, M and O) on the silver nano-particles

Surface-enhanced Raman scattering (SERS) spectra of a series of n-hydroxybenzoic acids (n-HBA, n = P, M and O) adsorbed on the silver nano-particles were studied, respectively, in the silver colloidal solution and on the dried silver-coated filter paper. On the same substrate, the different molecules' SERS spectra were different, while on the different substrates the same molecules' SERS spectra were also different. Significant changes were found in the SERS spectra of PHBA molecules adsorbed on the two substrates, and the changes found in MHBA's spectra on two substrates were next to PHBA's, while almost no changes were found in the spectra of OHBA molecules. Moreover, it was found, on the filter paper, that the SERS spectra of the same molecules would change with the coverage density of the silver nano-particles. The analyses showed that the origins of these changes were the different adsorption behavior of molecules adsorbed on the silver nano-particles. Because in these three molecules the relative positions of the carboxyls and hydroxyls on the benzenes are different, the adsorption behaviors of these three molecules adsorbed on the silver surfaces are also different. The experimental results suggest that the surface characteristic of the substrate and the surface configuration of the adsorbate could exert a great influence on the adsorption behavior of the adsorbates on the substrates.     

A laser Raman spectroscopy study of molybdenum oxide supported on alumina and titania

Molybdenum oxide supported on alumina and titania prepared by three different methods (impregnation, calcination and hydrothermal treatment of mechanical mixtures), have been studied by laser Raman spectroscopy. Different oxomolybdenum species have been detected depending on the method of preparation and on the calcination conditions. Heptamolybdate and polymolybdate species were found in the impregnated and in the uncalcined, hydrothermally treated samples supported on alumina and titania, respectively, whereas polymolybdate species were formed on the surface of alumina when the mechanical mixtures and the hydrothermally treated samples were calcined in the presence of water vapour. However, two kinds of species, polymolybdate and mono-oxomolybdenum, were found in the case of the mechanical mixtures and the hydrothermally treated samples calcined in the presence of water vapour when supported on titania.     

我国稀土生物无机化学研究进展

我国稀土生物无机化学研究的特点是紧密结合稀土在农用及药物中应用所提出急需回答的问题, 经过长期的工作, 已在稀土的跨细胞膜运转, 稀土进入动物体内后的物种分布, 稀土与细胞膜的作用, 稀土对血红蛋白结构与载氧功能的作用, 稀土对骨细胞及骨结构的影响以及稀土在大鼠肝脏中的积累等方面取得了满意的结果. 从而可以为今后开展稀土元素在农用及药用中危险性评价的基础数据, 同时亦将促进稀土细胞化学的发展.     

The formation and production of nano and micro particles on clays under environmental-like conditions

Summary Metal ions are adsorbed in the interlayer space and on the edges of clay minerals, leading to the uniform distribution of metal ions on atomic scale. However, additional processes can be resulted in the formation of nano and micro particles in the interlayer space as well as on the outer surfaces. The formation of nano and micro particles on clay minerals under environmental conditions are discussed here in metal ions (manganese, lead, zinc, and silver ions)/bentonite systems. Two-dimensional nano layer is formed in the interlayer space by the oxidation of manganese ions under atmospheric conditions. Three-dimensional particles are formed on the surfaces initiating by the metal ion adsorption on the deprotonated edge sites. The formation of micro particles on the surface can also be followed by the redox reaction of metal ions.     

Polypeptide friction and adhesion on hydrophobic and hydrophilic surfaces: a molecular dynamics case study

Using all-atomistic MD simulations including explicit water, the mobility and adhesion of a mildly hydrophobic single polypeptide chain adsorbed on hydrophobic and hydrophilic diamond surfaces is investigated by application of lateral and vertical pulling forces. Forced motion on the hydrophilic surface exhibits stick-slip due to breaking and reformation of hydrogen bonds; in contrast, on the hydrophobic surface, the motion is smooth. By carefully tuning the driving force magnitude, the linear-response regime is reached on a hydrophobic surface and equilibrium values for mobility and adhesive strength are obtained. On the hydrophilic surface, on the other hand, slow hydrogen-bond kinetics prevents equilibration and only upper bounds for adhesion force and mobility can be estimated. Whereas the desorption force is rather comparable on the two surfaces and differs at most by a factor of 2, the mobility on the hydrophilic surface is at least 30-fold reduced compared to the hydrophobic one. A simple model based on a single particle diffusing in a corrugated potential landscape suggests that cooperativity is rather limited and that the small mobility on a hydrophilic surface can be rationalized in terms of incoherently moving monomers. The experimentally well-known peptide mobility in bulk water is quantitatively reproduced in our simulations, which serves as a sensitive test on our methodology employed.     

咪唑啉酰胺在电偶电极表面的吸附行为

采用原子力显微镜技术研究了有机阳离子缓蚀剂(咪唑啉酰胺)在电偶电极表面的吸附行为, 并探讨了其腐蚀抑制机理. 结果表明, 金属表面的过剩电荷较大地影响缓蚀剂分子的吸附行为. 在1%的NaCl溶液中, 碳钢电极表面带有过剩的负电荷；不锈钢电极表面带有过剩的正电荷；碳钢电极和不锈钢电极耦合后, 其表面分别带有过剩的正电荷和负电荷. 在耦合前阳离子缓蚀剂分子仅吸附在碳钢表面, 耦合后缓蚀剂分子在偶对的阴极(不锈钢)和阳极(碳钢)表面均有吸附, 但缓蚀剂分子在碳钢表面的吸附强度和覆盖度较之耦合前降低, 缓蚀剂的腐蚀抑制能力减弱.     

Nano-emulsions: New applications and optimization of their preparation

Nano-emulsions, as non-equilibrium systems, present characteristics and properties which depend not only on composition but also on the preparation method. Although interest in nano-emulsions was developed since about 20 years ago, mainly for nanoparticle preparation, it is in the last years that direct applications of nano-emulsions in consumer products are being developed, mainly in pharmacy and cosmetics. These recent applications have made that studies on optimization methods for nano-emulsion preparation be a requirement. This review is focused on the most recent literature on developments of nano-emulsions as final application products and on the optimization of their preparation.     

Negative pions in chemistry

Measuring the probability of pion capture by hydrogen provides information on the properties of the chemical bond of hydrogen in molecules, in particular, on the electron density near the protons. This is shown in studies of the temperature dependence of pion capture in hydrogen-bonded liquids, of the influence of electronegative groups on the hydrogen atom in simple organic molecules, and of the effect of coordination on water molecules in aquacomplexes and aqueous solutions.     

Absorption profiles of flames used in atomic-absorption spectroscopy

A study has been made of the distributions of metallic atoms in their ground electronic state when an aqueous or an organic solvent containing the metal present in the solution in various combined forms is sprayed into various flames used in atomic-absorption spectroscopy. It has been found that with almost all elements studied, rich flames give greater peak absorbances than lean flames, and the flame stoichiometry determines the number of free atoms in a flame. It has also been observed that the spatial distribution of free atoms in a flame depends not only on the flame stoichiometry but also on the species which the desired metal forms in the solution and the flame, on the other anions, complexing agents, and cations present in the solution, on chemical and physical properties of the solvent, on the type of atomizer-burner and on the flame temperature.     

In Vitro Studies on Therapeutic Effects of Cannabidiol in Neural Cells: Neurons,Glia, and Neural Stem Cells

(‒)-Cannabidiol (CBD) is one of the major phytocannabinoids extracted from the Cannabis genus. Its non-psychoactiveness and therapeutic potential, partly along with some anecdotal—if not scientific or clinical—evidence on the prevention and treatment of neurological diseases, have led researchers to investigate the biochemical actions of CBD on neural cells. This review summarizes the previously reported mechanistic studies of the CBD actions on primary neural cells at the in vitro cell-culture level. The neural cells are classified into neurons, microglia, astrocytes, oligodendrocytes, and neural stem cells, and the CBD effects on each cell type are described. After brief introduction on CBD and in vitro studies of CBD actions on neural cells, the neuroprotective capability of CBD on primary neurons with the suggested operating actions is discussed, followed by the reported CBD actions on glia and the CBD-induced regeneration from neural stem cells. A summary section gives a general overview of the biochemical actions of CBD on neural cells, with a future perspective. This review will provide a basic and fundamental, but crucial, insight on the mechanistic understanding of CBD actions on neural cells in the brain, at the molecular level, and the therapeutic potential of CBD in the prevention and treatment of neurological diseases, although to date, there seem to have been relatively limited research activities and reports on the cell culture-level, in vitro studies of CBD effects on primary neural cells.     

Thermodynamic properties and electrochemical behavior of lithium–germanium alloys

Published data on the phase diagram of the lithium–germanium system, on the thermodynamic properties of Li–Ge alloys, on their electrochemical behavior in various media, and on prospects for using them in lithium–ion batteries and in other chemical current sources are analyzed.     

多相催化中的溢流作用

详细介绍和评述了30 余年来有关溢流的研究进展, 包括溢流这一概念的内涵及其对多相催化学科的影响, 常见的溢流现象、溢流效应及利用溢流效应进行催化剂设计的有关问题; 对未来溢流研究的方向提出了建议。     

Substituent effect on the tautomerism of 5-acetyl-2-methoxydihydropyrimidines: experimental NMR and computational DFT studies

Some selected 5-acetyl-2-methoxydihydropyrimidines (DHPMs) are synthesized and the electronic effect of the substituent on the 4-position of the heterocyclic ring on the ratio of the possible tautomeric forms is investigated using dynamic NMR experiments. The results of this study indicate that these compounds coexist in two tautomeric 1,4- and 3,4-forms in the solution and their tautomeric ratios depend on the electronic nature of the additional substituent on the 4-phenyl substituent, the nature of solvent used for NMR study and also on the temperature. B3LYP/6–31 ++G** computational studies in the gas and solution phases elucidate the effect of the additional substituent on the phenyl ring on the structural, electronic and bonding characteristics of the tautomeric forms in these compounds. Furthermore, solvation of these DHPMs determines the relative stabilities of the two tautomers in the solution phase, which cannot be probed by model solvents adopted in SCRF calculations.     

多相聚合物体系相界面研究进展

综述了多相聚合物体系相界面的形成、界面层状态的表征、界面层性质及其对体系性能的影响。重点论述了不同类型增容剂对界面行为的影响，其中对嵌段型增容剂的分子量、浓度等因素对界面行为的影响建立了定量关系；而对接枝型和无规增容剂对界面行为的影响研究较少，有待发展。指出了在界面张力、界面层厚度与多相聚合物体系性能，尤其是力学性能之间建立量化关系是高分子物理领域一个可以期待的发展方向。     

溶胶-凝胶技术在电化学和生物传感器制备中的应用近况

对溶胶-凝胶技术在制备电化学和生物传感器中的应用近况(涉及年份主要在1992-2006年间)作了评述,内容主要集中在应用此技术包埋某些电化学活性物质或生物化学活性分子于其中而制备相关传感器的方法及其原理,在制备传感器过程中的影响因素以及此类传感器的分析应用。此外,对其发展趋势也作了简单的讨论(引用参考文献51篇)。     

Actuation of adaptive liquid microlens droplet in microfluidic devices: A review

A significant growth of research on adaptive liquid lens is achieved over the past decades, and the field is still attracting increasing attentions, focusing on the transition from the current stage to the commercialized stage. The challenges faced are not limited to fabrication, material, small tuning range in focal lengths, additional control systems, limitations in special actuation methods and so on. In addition, the use of external driving parts or systems induce extra problem on bulky appearance, high cost, low reliability etc. Therefore, adaptive liquid lens will be an interesting research focus in both microfluidics and optofluidics science. This review attempts to summarize and focus on the droplet profile deformation under different driving mechanisms in tunable liquid microlens as well as the application in cameras, cell phone and so on. The driving techniques are generally categorized in terms of mechanisms and driving sources.     

Edge excitation red-shift and proton migration in acidic quinine sulphate solution

A red-shift in the emission maximum of an acidic solution of quinine sulphate is observed on exciting in the red edge of the absorption band. The edge excitation red-shift (EERS) which really is the difference in cm^?1 between the emission maxima obtained on red edge excitation (REE) and on shorter wavelength excitation (SWE) depends on viscosity, temperature, deuteration of the solvent and concentration of the solute. The dependence of the EERS on these factors is due largely to a shift in the emission maximum on SWE; the REE emission shifts little. These results are explained on the basis of solvent relaxation and proton migration in the excited state.