Statistical thermodynamics of polynuclear linear complexes with mixed valence states by means of the correlated walk

Expressions for the equilibrium electrode potential of linear N-nuclear complexes with homoredox centers were derived by the theory of the correlated walk as a function of the molar fraction of the oxidized moiety, the nearest-neighbor interaction energies and N. When the interaction energy was large in two-, three- and four-nuclear complexes, the expressions predicted two, three and four voltammetric peaks respectively owing to the formation of mixed valence states. The intuitive extension that the N-nuclear complex might exhibit N peaks was invalid. There were three peaks for any odd number of N. In contrast, four peaks appeared for any even number of N more than 4. For a polynuclear complex with N → ∞, the number of the peaks was reduced to two, as if the complex might be a binucleus. The log plot for the fraction vs. potential curve at large values of N deviated from a straight line. The averaged inverse slope was ca. 90 mV at 25°C. From the concentration distribution of a predominant species varying with the potential, the deviation of the log plot was ascribed to the coexistence of various isomers with different interaction energies. The difference in the voltammetric peak potential was approximately linear with the interaction energy for any N. Approximate equations for the potential difference for N= 2, 3 and 4 were obtained, and were applied to the experimental data available for polyferrocenes.     

Open tubular columns with mixed‐mode reversed‐phase and weak anion‐exchange stationary phase for capillary electrochromatography

Columns for open tubular capillary electrochromatography, coated with a mixed‐mode (RP/ion‐exchange) stationary phase, were prepared by using the sol–gel method. The synthetic procedure was optimized by changing the ratios of tetraethoxysilane, octyltriethoxysilane, and 3‐aminopropyltriethoxysilane in the initial sol. SEM studies reveal that a coating with about 400 nm thickness can be obtained. The inner surface properties of these capillaries were probed by measuring the EOF as a function of pH. The surface of this stationary phase contains octyl, amine, and residual silanol moieties; the amine and silanol groups determine the net charge on the inner surface of the capillary and can produce a switchable EOF (anodal/cathodal). The performances of the columns were evaluated by open tubular capillary electrochromatography using a wide range of compounds (polycyclic aromatic hydrocarbons, aromatic acids, and aromatic amines).     

Transport of monooleoylglycerol mediated by bile salt micelles across porous membranes

In order to study how the bile salts and lipids behave in the vicinity of microvillus, the transport properties of a sodium salt of deoxycholic acid (NaDC) and its mixture with monooleoylglycerol (MO) through artificial membranes were investigated in 0.15 M NaCl saline solution at 37°C.The hydrodynamic radius of MO-solubilized micelles was estimated to be approximately 17–20 Å from the transport study. The thermodynamically stable MO-NaDC mixed micelles formed above critical micelle concentration in the higher region of mole fraction of NaDC in the mixture (X _NaDC>ca. 0.6), can behave as a single species in transport process and freely pass through the porous membranes of both pore sizes, 0.01 m and 0.1 m.The permeabilities of MO-NaDC mixed micelles are large compared with those of pure NaDC micelles. MO molecules solubilized may probably enhance the interaction between MO and NaDC molecules by better contacting with the respective hydrophobic groups in a mixed micelle (the flexible structure of MO molecule enables it), and in this situation, the smaller micelles compared with those of pure NaDC must be more favorable.     

混合三烃基锡衍生物的研究(Ⅲ)──二丁基一环己基锡羧酸酯的合成、结构表征及生物活性

以丁基替换环己基,合成了20种二丁基一环己基锡羧酸酯。利用IR、NMR及元素分析表征了化合物的结构,确定了化合物的质谱裂解机制。对化合物进行了生物活性普筛试验。结果表明,这类化合物同时具有高效杀菌和杀螨活性。     

氢氧化铝镁正电溶胶制备及性能研究

氢氧化铝镁正电溶胶制备及性能研究侯万国，张春光，孙德军，梁晓丽，王果庭（山东大学胶体与界面化学研究所，济南，２５０１００）关键词混合金属氢氧化物，溶胶，超细颗粒混合金属氢氧化物的合成、组成及结构等已得到广泛研究［１，２］．我们也曾用插入法合成了混合金...     

混合表面活性剂存在下火焰原子吸收光谱法测定合金钢中的钼

研究了在火焰原子吸收光谱法中三乙醇胺及十二烷基三甲基氯化铵对钼的增感作用。在仪器最佳工作条件及合适的酸存在下,６０ｇ／Ｌ三乙醇胺及１６ｇ／Ｌ十二烷基三甲基氯化铵可使钼的吸光度增感７０．４％,且能消除多种共存元素的干扰。建立了合金风中大于０．０５％钼的测定方法。     

Detection of antisperm antibody in human serum using a piezoelectric immunosensor based on mixed self-assembled monolayers

A novel piezoelectric immunosensor based on mixed self-assembled monolayers (mixed SAMs) formed by short-chain amine- and carboxyl-terminated thiols has been developed to immobilize antigens onto gold electrodes for detecting antisperm antibody (AsAb) in human serum samples. The properties and the enhanced performance of the affinity biosensor interface based on mixed SAMs are investigated. Most importantly, analytical results of several human serum samples using the developed technique are in satisfactory agreement with those given by the enzyme-linked immunosorbent assay (ELISA) method in the concentration ranging from 32.3 to 300.0 mU/ml. It means the procedure proposed in this paper is likely to have a great potential in research and may play an important clinical role in a few years later.     

Electrochemical characteristics of Ce0.8Gd0.2O1.9|La0.6Sr0.4CoO3-δ + Ce0.8Gd0.2O1.9 half-cell

The analysis of the medium temperature half-cell Ce_0.8Gd_0.2O_1.9|70 wt% La_0.6Sr_0.4CoO_3- (LSCO) + 30 wt % Ce_0.8Gd_0.2O_1.9 (CGO) has been made by electrochemical impedance, cyclic voltammetry and chronoamperometry. The shape of complex impedance plots depends on temperature and cathodic polarisation of the electrode. Nyquist (Z, Z-) plots were fitted by equivalent circuit taking into account the electrolyte properties (at very high frequencies), charge transfer process at grain boundaries (at high frequencies), and medium and low frequency O₂ reduction process at the cathode surface and inside the porous cathode material. Two different time constants have been obtained for the cathode process, i.e. for electroreduction of oxygen. It was found that the addition of CGO into the cathode material (LSCO) only somewhat decreases the surface catalytic activity but the noticeably higher low-frequency resistance (i.e. mainly diffusion-like mass transfer resistance R_D) values at lower temperatures have been calculated. It was found that the mainly bulk diffusion-limited process at T773 K deviates toward the kinetically mixed process (diffusion + charge transfer) with increasing temperature.     

Preparation and properties of homogeneous V2O5-SiO2 xerogel composite based on interpenetrating polymer network

In this paper, we report the conducting and electrochemical properties of a homogeneous V₂O₅-SiO₂ xerogel composite obtained from the simultaneous polymerization in both inorganic components (Si-O and V-O based polymers) forming an interpenetrating polymer network, where a mutual “solubility” due to cross-links and entanglements was observed. The presence of V₂O₅ inside the silica matrix has a strong effect on electrical conductivity; measurements showed room temperature conductivity almost 1000 times higher than what is found in the literature. In addition, the electrochemical behavior is quite similar to that found in V₂O₅ xerogel. Moreover, the effects of thermal treatment on the conducting and electrochemical properties were investigated. It was found that both properties were improved with no significant effect on V₂O₅ xerogel layered structure.     

2D metal slabs in new nickel-tin chalcogenides Ni7−δSnQ2 (QSe, Te): average crystal and electronic structures, chemical bonding and physical properties

A systematic search for mixed low-valence, nickel-tin chalcogenides performed by establishing phase relations in the parts of Ni-Sn-Se and Ni-Sn-Te ternary systems resulted in the discovery of two new compounds, Ni_5.62SnSe₂ and Ni_5.78SnTe₂. Single crystals of both compounds were prepared by chemical transport with iodine and crystal structures were determined by single crystal X-ray investigation. The ED patterns for Ni_5.78SnTe₂ showed the presence of satellite reflections, which indicate a modulated structure with q≈0.4a^*. Average crystal structures of both compounds were determined to be of tetragonal symmetry (Sp.gr. I4/mmm, Z=2) with a=3.6890(8) Å, c=18.648(3) Å, R_w=0.0716 and a=3.7680(5) Å, c=19.419(4) Å, R_w=0.0832, correspondingly, and are isostructural to known Ni_5.72SbSe₂ and Ni_5.66SbTe₂. Measurements were carried out for both compounds with respect to thermal, electrical and magnetic properties. Ab initio band structure calculations were also performed to take a first glance into the electronic structure of such type compounds. The anisotropy of their band structure was found. Physical property measurements showed both compounds to be the anisotropic metallic conductors and paramagnetics. Calculated difference charge density maps revealed pairwise covalent and multicenter metallic nature of the d-metal—chalcogen and d-metal—p-metal interactions, respectively.