Abnormally high fractal dimension of silica surfaces measured by adsorption of aliphatic alcohols

Factors leading to abnormally high fractal dimension D of silica surfaces measured by adsorption of aliphatic alcohols have been analyzed. , D .     

光伏太阳能电池生产过程中的污染问题

日益壮大的光伏产业正在为人类发展作出积极的贡献.采用光伏发电来代替传统的发电技术,将会减少89%的空气污染.然而,在这个倡导绿色环境的时代,光伏器件生产引起的环境、健康和安全（EHS）问题也日益引起社会各界的广泛关注.认清光伏产品在生产过程中污染的真相对维持光伏产业的可持续发展有着相当重要的意义.本文综述了常见太阳能电池的EHS问题,并提出了可以减少污染的有效途径;采用生命周期评估（LCA）方法进一步比较了各种太阳能电池生产过程中污染物的排放量数据.     

Synthesis, crystal structure, spectroscopic and electrochemical properties, and H2-evolving activity of a new [PtCl(terpyridine)]+ derivative with viologen-like redox properties

A new Pt(II)-based metalloviologen analog, [PtCl(Mepytpy)](2+) (abbreviated as PV(2+); Mepytpy(+) = 4'-(4-methyl-pyridinio)-2,2':6',2'-terpyridine), was synthesized and its spectroscopic and electrochemical properties were investigated. The structures of Mepytpy(+) and PV(2+) were solved by single-crystal X-ray diffraction analysis. Electrochemical studies in DMF (N,N-dimethylformamide) revealed that both the first and second reduction potentials of PV(2+) (E = -0.87 V vs. Fc/Fc(+) for PV(2+)/PV(+)˙; E = -1.31 V vs. Fc/Fc(+) for PV(+)˙/PV(0)) are nearly consistent with those of methylviologen (N,N'-dimetyl-4,4'-bipyridinium, MV(2+)) (E = -0.90 V vs. Fc/Fc(+) for MV(2+)/MV(+)˙; E = -1.28 V vs. Fc/Fc(+) for MV(+)˙/MV(0)), where the first reduction of PV(2+) is assigned as the reduction at the Mepytpy(+) ligand bound to the Pt(ii) ion. Upon the addition of a reducing agent Na(2)S(2)O(4) into an aqueous acetate buffer solution (pH = 5.0) of PV(2+), the generation of one-electron-reduced radical species (PV(+)˙) was spectrophotometrically observed and was assigned based on the time-dependent density functional theory (TD-DFT) calculations. The H(2)-evolving activity of PV(2+) was evaluated in the presence of a sacrificial electron donor (EDTA) in an aqueous acetate buffer solution (pH = 5.0). It was found that the stability of the metalloviologen PV(2+) during the photolysis is much higher than that of the parent compound [PtCl(tpy)](+).     

The effect of PVAc on the efficiency of thermal reactions in PS/PVAc blends in relation to the atmosphere

The thermal stability of polystyrene (PS) blends with polyvinyl acetate (PV Ac) has been investigated. It was found that PV Ac acts as a sensitizer of the thermal degradation of these blends when the process takes place in a nitrogen atmosphere. In air PV Ac acts as a stabilizer, and the temperature of the decomposition of these blends is higher than that of pure PS. This stabilization is caused by PV Ac favoring an oxidation reaction without breaking the polymer chains.     

渗透汽化分离芳烃/烷烃混合体系的研究进展*

本文对近年来应用于分离芳香烃/ 烷烃混合体系的渗透汽化(简称PV ) 膜材料, 特别是高分子材料进行了较为系统的综述, 并简要概述了渗透汽化膜分离特点、机制以及影响渗透汽化分离过程的主要因素。     

同多酸和杂多酸修饰微电极的电化学研究 Ⅶ.磷钒钼杂多酸薄膜修饰微电极和杂多酸/聚苯胺薄膜修饰微电极的制备和电化学性质

本文详细描述了磷钒钼杂多酸（PV2Mo10）极薄膜修饰碳纤维（CF）微电极和PV2Mo10／聚苯胶（PAn）薄膜修饰微电极的制备及其电化学性质。     

齐聚苯撑乙烯-二氧化硅复合膜的制备及其光电性质研究

聚苯撑乙烯（PPV）及其复合物由于光致发光效率高及电荷传输性能好,故在光电器件方面的应用已受到广泛重视,但聚合物材料有自身的局限性,主要是：（1）在矣合时残留杂质影响器件的稳定性;（2）聚合物结构复杂多变使其发光机理与微观结构模糊不清。因此具有化学结构,化学纯度高的剂聚苯撑乙烯（oligo-PV)及其复合物的合成和理论研究吸引了许多研究者。     

Isolation and characterization of phenyl viologen as a radical cation and neutral molecule

The chemical synthesis, isolation, and characterization of phenyl viologen (PV) as a dication, radical cation, and neutral species are described. Single-crystal X-ray diffraction of PV(2+)2Cl(-.)2H2O and PV(.+)PF(6)(-).pyridine reveals the expected differences in bond lengths and also a structural change from two coplanar central rings in PV(.+) to a twist of 36 degrees between the two central rings in PV(2+). The phenyl viologen radical cation exhibits behavior characteristic of many radical cations, including weak pi-dimerization in the solid state and reversible pi-dimerization in solution. Electrical conductivity measurements of neutral phenyl viologen, the first such measurements of a neutral viologen, reveal that it is a significantly better conductor than the radical cation. Differences in geometric relaxation during charge transfer offer a possible explanation for the higher conductivity of the neutral viologen.     

Clinical application of extracellular fluid measurement using 35S-sodium sulfate (author's transl)

ECF (extracellular fluid volume) was measured by 35S-sodium sulfate and the same time value of PV (plasma volume) was determined by 131I-RISA in each subject. In normal ECF was an average of 181 ml/kg, 6.21 l/m2 and PV was 49.1 ml/kg, 1.69 l/m2. Both values of ECF and PV in essential hypertension were almost the same as those in normal. In congestive heart failure ECF was 232 ml/kg, 7.51 l/m2 and PV was 55.8 ml/kg, 1.80 l/m2. In the patients with ascites or edema, ECF was 256 ml/kg, 8.69 l/m2 and PV was 53.0 ml/kg, 1.79 l/m2. The results of the measurement by the two compounds also corresponded to the conditions of the patients who showed electrolytes disorders (ACTH deficiency, SIADH) and was improved by treatment.     

Efficient charge transport along phenylene-vinylene molecular wires

We have studied the motion of charge carriers along isolated phenylene-vinylene (PV) chains using a combination of experimental and theoretical methods. The conductive properties of positive charges along PV chains in dilute solution were studied by using the pulse-radiolysis time-resolved microwave conductivity (TRMC) technique. This technique enables the measurement of high-frequency (tens of GHz) charge carrier mobilities along isolated PV chains without the use of electrodes. The charge carrier mobility along PV chains with finite and infinite length was studied theoretically by charge transport simulations with parameters from density functional theory (DFT) calculations. The high-frequency charge carrier mobility is found to depend strongly on the conjugation length of the PV chains and is found to increase both with increasing length of the PV chain and with increasing conjugation fraction. The experimental results are in good agreement with the calculated results. On the basis of this combined experimental and theoretical study an intrachain charge carrier mobility of a few tens of cm2/Vs is expected for an infinitely long PV chain without conjugation breaks.     

主链含三苯胺单元的聚苯乙炔的合成及其电致发光性能

采用4-甲基三苯胺的二醛基化合物分别与对、间、邻-二甲基苯的膦盐反应,制备了三种含三苯胺单元的聚苯乙炔类共聚物TPA-PPV、TPA-PmPV和TPA-PoPV。结果表明：TPA-PPV和TPA-PmPV具有良好的热稳定性和光电化学性能,该类共聚物不但具有良好的空穴传输性能,而且作为发光材料应用于发光器件时可以调制发光颜色。     

光伏组件封装材料进展

封装材料是影响目前太阳能等光伏组件使用性能的重要因素。结合最新研究进展,本文从化学观点出发,综述和评论了实用的乙烯-乙烯醋酸酯共聚物(EVA)、聚乙烯醇缩丁醛(PVB)和聚二甲基硅氧烷(PDMS)材料在使用过程出现的问题以及改性研究方法,强调了PDMS材料在太阳能光伏组件封装中的重要性。     

Nanoparticle-polymer photovoltaic cells

The need to develop and deploy large-scale, cost-effective, renewable energy is becoming increasingly important. In recent years photovoltaic (PV) cells based on nanoparticles blended with semiconducting polymers have achieved good power conversion efficiencies (PCE). All the nanoparticle types used in these PV cells can be considered as colloids. These include spherical, rod-like or branched organic or inorganic nanoparticles. Nanoparticle-polymer PV cells have the long-term potential to provide low cost, high-efficiency renewable energy. The maximum PCE achieved to date is about 5.5%. This value should rise as recently reported theoretical predictions suggest 10% is achievable. However, there are a number of challenges that remain to be overcome. In this review two general types of nanoparticle-polymer PV cells are considered and compared in detail. The organic nanoparticle-polymer PV cells contain fullerene derivatives (e.g., phenyl C61-butyric acid methyl ester, PCBM) or single-walled nanotubes as the nanoparticle phase. The second type is hybrid inorganic nanoparticle-polymer PV cells. These contain semiconducting nanoparticles that include CdSe, ZnO or PbS. The structure-property relationships that apply to both the polymer and nanoparticle phases are considered. The principles underlying nanoparticle-polymer PV cell operation are also discussed. An outcome of consideration of the literature in both areas are two sets of assembly conditions that are suggested for constructing PCBM-P3HT (P3HT is poly(3-hexylthiophene)) or CdSe-P3HT PV cells with reasonable power conversion efficiency. The maximum PCE reported for organic nanoparticle PV cells is about twice that for inorganic nanoparticle-polymer PV cells. This appears to be related to morphological differences between the respective photoactive layers. The morphological differences are attributed to differences in the colloidal stability of the nanoparticle/polymer/solvent mixtures used to prepare the photoactive layers. The principles controlling the colloid stability of the nanoparticle/polymer/solvent mixtures are discussed.     

Isolation of Lectins from the Kidney Bean,Phaseolus valgaris L

From the seeds of red kidney bean (Phaseolus valgaris L.), two protein constituents named PV3 and PV5 have been isolated and purified by extraction with PB buffer, S-Sepharose Fast Flow column chromatography (Fig.l).     

Methodological aspects in the calculation of parity-violating effects in nuclear magnetic resonance parameters

We examine the quantum chemical calculation of parity-violating (PV) electroweak contributions to the spectral parameters of nuclear magnetic resonance (NMR) from a methodological point of view. Nuclear magnetic shielding and indirect spin-spin coupling constants are considered and evaluated for three chiral molecules, H2O2, H2S2, and H2Se2. The effects of the choice of a one-particle basis set and the treatment of electron correlation, as well as the effects of special relativity, are studied. All of them are found to be relevant. The basis-set dependence is very pronounced, especially at the electron correlated ab initio levels of theory. Coupled-cluster and density-functional theory (DFT) results for PV contributions differ significantly from the Hartree-Fock data. DFT overestimates the PV effects, particularly with nonhybrid exchange-correlation functionals. Beginning from third-row elements, special relativity is of importance for the PV NMR properties, shown here by comparing perturbational one-component and various four-component calculations. In contrast to what is found for nuclear magnetic shielding, the choice of the model for nuclear charge distribution--point charge or extended (Gaussian)--has a significant impact on the PV contribution to the spin-spin coupling constants.     

Adsorption removal of methyl violet from aqueous solution by chromium phosphovanadate

An effective adsorbent for methyl violet (MV), chromium phosphovanadate (named as Cr‐PV) nanomaterials, was prepared by a simple coprecipitation strategy. The microstructure and morphology of as‐synthesized Cr‐PV were characterized by SEM, X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR), respectively, which was confirmed as nanosheet shapes. The adsorption behavior for MV from aqueous solutions was systematically investigated. The kinetic and equilibrium results indicate that the adsorption process follows pseudo‐second‐order kinetic model and Langmuir isotherm, respectively. Compared with PV and commercially available activated carbon, Cr‐PV has preferable adsorption property to MV. The maximum adsorption capacity can reach 123.81 mg g^?1 at room temperature. The thermodynamic parameters such as Gibbs free energy (ΔG^ο), enthalpy (ΔH^ο), and entropy change (ΔS^ο) show that the adsorption of MV is an endothermic and spontaneous process. Moreover, the adsorptive behavior between Cr‐PV and MV is monolayer adsorption and electrostatic interaction mechanism. Cr‐PV, as a promising adsorbent with high adsorption capacity and fast adsorption rate, shows great potential for the removal of MV from wastewater.     

Pyrocatecholsulphonphthalein complexan as an analytical reagent

Pyrocatecholsulphonphthalein complexan (PSC) has been synthesized from Pyrocatechol Violet (PV), iminodiacetic acid and formaldehyde by Mannich condensation. Its acid dissociation equilibria have been studied potentiometrically. Some characteristic properties of Xylenol Orange (XO) and PV are found in PSC, which is slightly superior to XO and PV in sensitivity as a chromogenic reagent for bismuth. The spectrophotometric characteristics of some metal ion-PSC complexes are reported.     

Generation of a selective layer on polyacrylonitrile membrane supports for separation of aromatic/non‐aromatic hydrocarbon mixtures by pervaporation

An application of the “pore filling” concept yielded high‐performance composite membranes for the selective pervaporation (PV) separation of aromatic/non‐aromatic hydrocarbon mixtures. Asymmetric polyacrylonitrile (PAN) membranes (average pore size of about 12 nm) were used as support for polymeric PV separation phases which were prepared in situ by heterogeneous photo‐initiated graft copolymerization. The impact of chain length of methyl polyoxyethylene (meth)acrylates and preparation parameters (UV irradiation time and degree of grafting) were analysed using PV with toluene/heptane (20/80 wt‐ratio; 80°C) as model feed. High selectivity and high permeate fluxes were achieved. Major reasons for the excellent performance were the small effective PV barrier thickness (< 5μm) and the covalent anchoring of the coated polymer.     

渗透汽化芳烃/烷烃分离膜材料

芳烃/烷烃混合物的分离在石油化工及环保领域都具有重大意义.与传统的萃取精馏等技术相比,渗透汽化膜技术以其清洁、节能和高效的优点,应用于芳烃/烷烃混合物的分离并受到重视.本文综述了渗透汽化芳烃/烷烃分离膜的研究进展,概述了渗透汽化技术的基本原理和应用,重点介绍了用于渗透汽化芳烃/烷烃分离的聚酰亚胺、聚氨酯等高分子膜材料的结构特点和分离性能.总结了膜材料的接枝、共聚和共混,添加传质促进剂的改性方法.分析了渗透汽化芳烃,烷烃分离膜材料的研究思路,在此基础上对渗透汽化芳烃/烷烃分离膜材料的研究方向和发展前景进行了展望.     

DFT study of electronic and magnetic structure of perovskite and post-perovskite CaRhO3

Within density functional theory the equations of state for perovskite (PV) and post-perovskite (PPV) forms of CaRhO₃ are obtained with equilibrium values of volume in agreement with experiment. Energy magnitudes point to a stabilization of PPV versus PV. This is interpreted by analyses of the charge density and the chemical bonding plots, showing that the Rh–O interactions within two oxygen sublattices are selectively differentiated and reinforced for one of the two oxygen sublattices within PPV variety with respect to PV one. Investigation of the magnetic properties shows no magnetic order and a metallic character for PV while ferromagnetism occurs in PPV with a tendency to insulating behavior. This long range order is favored by direct t_2g–t_2g interactions through edge sharing octahedra in PPV CaRhO₃, stronger than indirect t_2g–p_π–t_2g ones in PV variety.