“HSR CSR PSR”树脂的氧化还原电位

本文介绍了氧化还原树脂的氧化还原电位测定方法,并据此研究和测定了自制的三种氧化还原树脂—HSR、CSR、PSR的氧化还原电位,这些电位的测定结果与其氧化还原性能实验事实相符。还研究了多种氧化剂和还原剂与自制的三种氧化还原树脂的交换性能,讨论了这些树脂的交换容量与氧化还原电位的关系。此外,用红外光谱研究了这类树脂从氧化态到还原态的结构变化。     

光电材料在金属防腐蚀中的应用

金属腐蚀问题一直以来是困扰我们的大问题。近年来,光电材料凭借其寿命长、无毒环保等优势在金属防腐的应用中发挥越来越大的作用。光电材料通过电子-空穴方法替代从前牺牲阳极的防腐蚀方法,电子与空穴的分离是为了电子能够快速达到阴极碳的位置,促成碳钢电位降低,空气中的水蒸气或有机气体是被空穴氧化,伴随碳钢电位降低所耗用的是光电材料周围的水、有机气体等而不是光电材料本身。主要对光电材料在金属防腐蚀中的应用进行了探讨,以供同行借鉴。     

硫酸乙烯酯及其改性分子氧化还原稳定性的密度泛函理论研究

基于密度泛函,分别从HOMO/LUMO和氧化/还原电位两个角度研究硫酸乙烯酯分子(DTD)及其改性分子的氧化/还原稳定性。通过垂直电离势的方法对化合物电位进行计算,模拟数值与实验数值有较好的吻合,电位展现出的氧化/还原稳定性趋势与分子的HOMO/LUMO相符。针对DTD分子结构改性,CO或CC基团的引入对添加剂的氧化稳定性和还原稳定性无益,改性分子的电化学稳定窗口反而变窄。     

电镀废水处理中的氧化还原电位控制

介绍了氧化还原电位控制原理,从理论和实际应用的角度揭示了影响氧化还原电位的因素。针对工程应用中遇到的氧化还原电位控制点确定等问题,提出了参考方法。     

从氧化还原电位的角度看菁染料的光谱增感与结构的相关性

本文用循环伏安法测定了一些菁染料的氧化还原电位,估算了一些未测得的数值,并与收集到的相同条件下的文献值进行了系统的比较。详尽地分析了菁染料的各种结构因素对氧化还原电位,进而对光谱增感作用的影响。从氧化还原电位的角度为选择性能优良的增感染料提供了一个重要的途径。     

关联氧化还原电位的丁二酸发酵过程动力学模型

氧化还原电位的调控对丁二酸发酵过程影响较大,而现有的丁二酸发酵过程动力学模型均未包含此重要参量。本研究首先进行五种氧化还原电位水平下的模型参数寻优,比较了Nelder-Mead算法与自适应遗传算法,采用后者进行参数优化。分析了氧化还原电位与动力学模型参数之间的函数关系,得到关联氧化还原电位的动力学模型。采用另外两种氧化还原电位水平下的实验数据进行模型验证,结果表明该模型具有较好的可靠性。     

有机电致发光空穴传输材料的合成

有机电致发光中空穴传输材料对整个器件的性能有重要作用。系统地综述了空穴传输材料的研究现状,包括Ullmann偶合法、钯催化法、格氏反应、Suzuki偶合等。同时对合成的空穴传输材料的特性进行了简述。     

用氧化还原电位滴定法测定磺酰氯的含量

介绍了用氧化还原的原理电位滴定磺酰氯类物质的方法,并与传统的碱解银量法和碱溶中和法做了对比实验,结果表明,氧化还原电位滴定磺酰氯类物质,操作简便,准确快速,成本较低,是一种适用于工业化生产的分析方法。     

几种二胺类分子空穴传输特性的量子化学分析

以TPD、TTB及NPB等二胺类空穴传输材料分子为研究对象,采用PM3半经验量子化学与DFT方法,计算了这3种分子未充电及充电时的几何构型、分子能量、HOMO与LUMO轨道及其能隙、分子净电荷分布与偶极距;同时,根据计算结果对比和分析了这3种分子的空穴传输能力.研究表明：NPB分子的空穴传输能力最为优越;3种分子的N原子部位均具有高的空穴迁移率.     

钙钛矿太阳能电池中D-A-D型空穴传输材料的研究进展

钙钛矿太阳能电池(PSCs)由于具有快速提升的光电转换效率、制备成本低、可溶液加工等优点而获得了广泛关注.空穴传输材料(HTM)负责空穴抽取和防止电荷复合,可提高PSCs的效率和稳定性,是PSCs中的重要组成部分.线型给体-受体-给体(D-A-D)结构的有机小分子空穴传输材料的结构简单,合成难度低.另外,吸电子单元的引入可以降低最高占据分子轨道(HOMO)能级,提高材料的稳定性,而且线型D-A-D构型有利于增强分子内电荷转移,提高材料的空穴传输能力.综述了2009年以来线型D-A-D类空穴传输材料在PSCs中的应用.详细介绍了各空穴传输材料分子结构对PSCs的光电转换效率和器件稳定性等性能的影响.最后,对未来线型D-A-D型空穴传输材料的发展进行了展望.     

Charge carrier transport control in activated carbon fibers

We present the results of measurements of electronic transport in an activated carbon fiber performed over a wide temperature range. The fiber had been subjected to the adsorption of various molecules, one type at a time. The presence of guest molecules inside the fiber’s pores causes significant changes in the electronic transport which has been observed to depend on the molecules’ dipole moment. Results show the possibility of controlling the charge carrier transport through the fiber by using specific adsorbents.     

The correlation between protein stability and dipole moment: a critical test

Improving the stability of proteins is a major aim in basic and applied protein science. Querol and coworkers calculated changes in the quasi-electric dipole moment of a protein and used it as a simple criterion to predict stabilizing charge mutations. They employed this method to propose for the bacterial cold shock protein Bc-Csp a number of charge mutations that should have a strong influence on stability. We produced eight variants of Bc-Csp with such mutations and measured their stabilities experimentally. However, we could not find a correlation between the stability and the quasi dipole moment of these variants. Possibly, the quasi dipole moment reflects only a secondary aspect of the changes that are caused by charge mutations in a protein.     

A simple electrostatic criterion for predicting the thermal stability of proteins

The enhancement of protein thermostability is an important issuefor both basic science and biotechnology purposes. We have developeda thermostability criterion for a protein in terms of a quasi-electricdipole moment (contributed by its charged residues) definedfor an electric charge distribution whose total charge is notzero. It was found that minimization of the modulus of thisdipole moment increased its thermal stability, as demonstratedby surveying these values in pairs of mesostable–thermostablehomologous proteins and in mutations described in the literature.The analysis of these observations provides criteria for thermostabilizationof a protein, by computing its dipole profile. This profileis obtained by direct substitution of each amino acid of thesequence by either a positive, negative or neutral amino acid,followed by a recalculation of the dipole moment. As an experimentalexample, these criteria were applied to a ß-glucanaseto enhance its thermal stability.     

DFT Studies of Selected Epoxies with Mesogenic Units–Impact of Molecular Structure on Electro-Optical Response

Theoretical studies of molecular structure and electric charge distribution were carried out for three epoxy compounds with different mesogenic cores. The compounds exhibit a nematic phase and form polymer networks that are potential bases for various composites. Results were compared to analogous materials with non-polar chains. A customized process involving geometry optimization of a series of conformations was employed to greatly increase likelihood of reaching global energy minimum for each molecule. All computations used Density Functional Theory (DFT) electron correlation model with the B3LYP hybrid functional. Molecular structure calculations yielded several parameters, including the magnitude and direction of the dipole moment, polarizability (α), first hyperpolarizability (β), and highest-occupied/lowest-unoccupied molecular orbital (HOMO-LUMO) energies. These parameters can help predict electronic properties of the nematic phase and the polymer network and assess their predisposition for application in electrooptical devices. In particular, the magnitude and direction of the dipole moment determine molecular alignment of liquid crystal phases in electric field, which enables controlling molecular order also in cured networks. Theoretical results were supplemented with observations of the nematics and their behavior in electric field. It was demonstrated for the studied compounds that a change in aliphatic chain polarity helps preserve and reinforce perpendicular alignment of molecules induced by electric field.     

Research progress of high-rate capacity layered double hydroxide supercapacitor materials

Layered double hydroxides （LDHs） are two-dimensional layered materials composed of positively charged metal hydroxide laminates, negatively charged anions between the layers, and water molecules, which can store and release charge through the reversible oxidation-reduction reaction between hydroxide and oxyhydroxide. LDHs have the advantages of high theoretical capacity, adjustable morphology and composition, low cost, and easy large-scale preparation, and have become the supercapacitor electrode materials with increasing attraction in recent years. To date, the rate capacities of LDHs are far from the expectation due to the low activity associated with low intrinsic activity and small active surface area, and the slow charge transport kinetics arising from the poor intrinsic conductivity to hinder electron transfer and the narrow interlayer distance to impede ion diffusion. Various strategies have developed to increase the activity, e.g., by regulating compositions, amorphizating, nanostructuring and constructing hierarchical structures, and to facilitate the charge transport kinetics, e.g., by compositing with carbon, depositing/growing on conductive substrates, expanding interlayer distance, exfoliation-self-assembly. This review starts with the structural characteristics and energy storage mechanism of LDHs, and then summarizes the strategies for improving the rate capacities of LDHs. The up-to-date progress in achieving the high-rate capacity by matching electron transfer with ion diffusion is also included, which suggests a new avenue to explore the advanced LDHs for energy storage.     

高倍率容量层状双金属氢氧化物超级电容材料的研究进展

层状双金属氢氧化物（LDHs）是由带正电荷的金属氢氧化物层板、层间带负电荷的阴离子和水分子组成的二维层状材料,可通过氢氧化物与羟基氧化物之间的可逆氧化还原反应存储与释放电荷,具有理论容量高、形貌与组分可调、成本低、易宏量制备等优点,成为近年来备受关注的超级电容器电极材料。超级电容材料在大电流密度下的比容量与其应用潜力密切相关,研究者们通过材料设计及电极工程,探索了多种提升LDHs倍率容量（即不同电流密度下的容量）的方法与技术,但至今LDHs的实际储能性能仍然远低于预期。简述了LDHs的结构、储能机理与面临的挑战,从增加反应活性、促进电荷传输动力学的角度归纳总结了提升LDHs倍率容量的研究进展,探讨了通过匹配电子传输和离子输运能力进一步提升LDHs倍率容量的新思路。     

Monitoring the Charge Distribution during Proton and Sodium Ion Conduction along Chains of Water Molecules and Protein Residues

Quantum calculations are used to determine the level of delocalization of the charge of a cation as it translates along a chain of water molecules or glycine residues. Charge dispersal is monitored via the molecular electrostatic potential and the dipole moment of the entire system. The positive charge is largely localized on the water molecule on which the proton is situated, but becomes more intense and extended as the proton moves along the chain. The positive charge is more delocalized in protonated polyglycine, where it extends over at least an entire residue. Displacement of the proton along the chain intensifies the charge, and progressively polarizes the entire chain. This pattern of charge intensification is more profound in both the 3₁₀ and α-helical structures. An Na⁺ cation behaves in much the same way as H⁺ in terms of charge migration.     

外壁荷电性质对双壁碳纳米管中水分子运动行为的影响

采用分子动力学模拟方法考察了双壁碳纳米管外壁荷电性质对孔道内水分子运动行为的影响。模拟结果显示：外壁荷电的双壁碳纳米管中水分子链呈现“双偶极”分布,由此将水分子的偶极翻转限制在碳纳米管的中部,避免了整条水分子链的偶极翻转,加速了水分子运动。外壁负载电荷也增强了水分子与碳纳米管之间相互作用,降低了水分子进入碳纳米管的能量壁垒,增强了碳纳米管内水分子内的氢键稳定性,这些均有利于水分子加速进入碳纳米管并在其中连续运动。上述结果从分子水平上揭示了碳管中水分子流动机理,为设计新型水纯化膜材料提供了有益的启示。     

Determination of the step dipole moment and the step line tension on Ag(0 0 1) electrodes

Using impedance spectroscopy, we determined the step dipole moment and the potential dependence of the step line tension of silver electrodes in contact with an electrolyte: (0 0 1) and vicinal surfaces (1 1 n) with n = 5, 7, 11 in 10 mM ClO₄⁻-solutions were investigated. The step dipole moment is determined from the shift of the potential of zero charge (pzc) as a function of the surface step density. The dipole moment per step atom was found to be 3.5 ± 0.5 × 10⁻³ e Å. From the pzc and the potential dependence of the capacitance curves, the potential dependence of the surface tension of the vicinal surfaces is determined. The line tension of the steps is then calculated from the difference between the surface tensions of stepped (1 1 n) and the nominally step-free (0 0 1) surfaces. The results are compared to a previous study on Au(1 1 n) surfaces. For gold, the step line tension decreases roughly linear with potential, whereas a parabolic shape is observed for silver.     

Acetylcholinesterase: Effects of Ionic Strength and Dimerization on the Rate Constants

Brownian dynamics simulations are used to calculate diffusion-controlled rate constants for the binding of a positively-charged ligand to acetylcholinesterase (AChE) at 300 K, pH 7, and several ionic strengths. Models of the enzyme were constructed on the basis of the crystal structure of Torpedo californica AChE, and the ligand was modeled as a 5-Å sphere. Assignment of the charge distribution of the enzyme is based on calculation of the fractional charges of its ionizable groups as a function of pH and ionic strength, by the finite difference Poisson-Boltzmann method. We find that the mean charge of the enzyme increases significantly with increasing ionic strength, with most of the increase occurring between 0 and 200 mM ionic strength. The charge distribution results in a very high dipole moment for the monomeric subunit of the protein: 1500 D relative to the Center of Diffusion. The magnitude and orientation of the dipole moment are relatively insensitive to the ionic strength. At physiological ionic strength, electrostatic steering of the ligand increases the rate constant of the enzyme-ligand encounter by more than one order of magnitude. The increase in protein charge with rising ionic strength weakens the ionic strength dependence of the rate somewhat. The calculations reproduce the experimentally observed decrease of the rate constants with increasing ionic strength. We observe no intrinsic rate difference for dimeric AChE as compared to the monomer: the rate constant of the dimer is twice that of the monomer.