Force constant calculations for octahedral complexes of the type M(CO)5L, based on the CO-factored force field

Using the maximum value of the sum of the interaction constants, the CO-factored force field of octahedral M(CO)₅L molecules was solved to give the relations which allow direct calculation of force constants from C---O stretching frequencies of the all-¹²C¹⁶O molecule. The force constants calculated by these relations were used to predict C---O stretching frequencies of isotopically enriched species of some complexes of the type M(CO)₅L. The results obtained showed that there exists a very good agreement between observed and calculated frequencies. This led us to conclude that the solution presented for the force field of M(CO)₅L molecules is a valid solution.     

固体CD光谱研究及其应用于手性席夫碱M(II)配合物

结合课题组近期的相关研究,对固体CD光谱在手性配合物研究中的应用,特别是手性样品固体CD光谱的测试方法进行了概述,通过对四对手性席夫碱M(II)(M=Ni、Cu)配合物的固体和溶液CD光谱进行比较研究,发现配合物的手性构型在固液相中保持一致,但其固液CD光谱之间存在不同程度的差异,可能是由于相应配合物在固体和溶液相中的四面体扭曲或构象的微妙不同所致.     

固体CD光谱研究及其应用于手性席夫碱M(II)配合物

结合课题组近期的相关研究, 对固体CD光谱在手性配合物研究中的应用, 特别是手性样品固体CD光谱的测试方法进行了概述, 通过对四对手性席夫碱M(II) (M = Ni、Cu)配合物的固体和溶液CD光谱进行比较研究, 发现配合物的手性构型在固液相中保持一致, 但其固液CD光谱之间存在不同程度的差异, 可能是由于相应配合物在固体和溶液相中的四面体扭曲或构象的微妙不同所致.     

EFFECT OF MELITTIN ON PHOTOCYCLE AND PHOTOPOTENTIAL OF PURPLE MEMBRANE: SITES OF INTERACTION BETWEEN BACTERIORHODOPSIN AND MELITTIN

Abstract— Purple membrane (PM) suspension and artificial bilayer lipid membranes (BLM) containing PM sheets were treated with melittin. Both the decaying of the photocycle intermediate M412 and proton translocation were inhibited by melittin: The yields and rate of the slow-decaying component of M412 (M412s) together with the proton release and its uptake rate were significantly decreased, but the rate of the fast-decaying component of M412 (M4120 had only slight changes. Relatively high concentrations of melittin could cause aggregation in PM suspensions. Addition of melittin to a BLM solution increased the continuous photopotential signal but decreased the transient signal. We suggest that there might exist strong interactions between melittin and bacteriorhodopsin in addition to the melittin–lipid action. On the other hand, the results also indicate that proton translocation was more likely to be coupled with M412s and both were more sensitive to the changes caused by the melittin–PM interaction than was M412f.     

CsF-RbF二元系相图

采用支持向量机(SVM)-原子参数模式识别法, 对75个一价金属同阴离子卤化物二元体系固溶体形成规律进行了研究, 根据研究结果, 预测CsF-RbF体系应形成固溶体. 用差热分析法重新测定了该体系的相图, 结果表明, 该体系为液固相连续互溶, 没有最低点和最高点的固溶体体系, 与文献中的热力学计算结果一致.     

The rheological properties of concentrated cetyltrimethylammonium bromide-salicylic acid solutions in water

Data on the rheological properties of the hexadecyl-trimethylammonium salicylate system (CTAB-SA) in water are reported. Three concentrations were used (0.1, 0.01, and 0.001 M). For the highest concentration, the effect of temperature on the rheology was studied in detail.The rheology of the 0.1 M CTAB-SA solution indicates a very uniform micellar size. By contrast with concentrated polymethyl methycrylate dispersions studied by the author, there was a strong divergence between the viscosity-shear rate and viscosity-frequency data, although the plateau low shear rate and frequency values agreed over a wide range of temperature. This effect could be explained by a shear rate dependent diffusion constant. The large temperature variation of the plateau viscosity and elasticity modulus values could be explained by a combination of micellar number concentration and flexibility changes as the temperature varies.At lower concentrations, the rheological data shows evidence of polydispersity in micellar size. Strong shear thickening and extensional viscosity effects are also evident, probably due to micellar overlap and cluster formation in strong shear fields and the alignment of the very long micelles in elongational flow. The shear thickening effects take some 200 s to relax (0.01 M solution). Recovery of the elasticity after shearing the 0.1 M solution is rapid (a few hundred milliseconds).     

Transport of99mTc across TBP-kerosene oil supported liquid membranes

Transport of^99mTc across tri-n-butylphosphate (TBP) kerosene oil supported liquid membranes (SLM) has been studied under various conditions. Presence of dichromate ions helps avoid activity scavenging effects. Concentration increase of TBP, the complexing carrier used in the present study has a positive effect on flux (J) and permeability (P) of these ions, as up to 2.87M there is an increase in J and P values. HCl concentration in the feed solution increases J and P with their maximum values at 2.5–3.0M HCl in the feed. Above this concentration there is a decrease in flux and permeability of^99mTc(VII) ions. The given ions are stripped with LiCl or NaCl solutions but more with NaOH. The optimum conditions of transport of the given ions are 2.5M HCl concentration in the feed, 2.87M TBP concentration in the membrane and 1M NaOH concentration in the strip solution. Equations have been developed to indicate the relation between flux, J, viscosity, of TBP in organic membrane phase, temperature, T, [H⁺], in the aqueous feed solutions and Tc ion concentration in the feed solution. Based on P, the values determined from liquid membrane experiments, the quantitative flux values of Tc(VII) ions were also determined as a function of TBP concentration in the membranes, and HCl and Tc concentration in the feed solution using the given equations. This experimental technique provides quantitative results from trace level activity transfer experiments.     

Solid formation in simulated high level liquid waste of relatively low nitric acid concentration

Solid formation in a simulated high level liquid waste (HLLW) was experimentally examined at 2M and 0.5M nitric acid concentrations. The precipitation studies were conducted by refluxing the simulated HLLW around 100°C. Zr, Mo, Te and Ru were major precipitation elements in both 2M and 0.5M HNO₃ solutions. The amount of precipitate in 2M HNO₃ solution decreased with decreasing Zr concentration and no precipitation was found in the solution without Zr. Only about 10% of Zr, Mo and Te were precipitated, if the Mo/Zr ratio in the 0.5M HNO₃ solution was kept below 0.5. Complete removal of Zr and Mo was the most effective way to prevent solid formation in the solution with 2M and 0.5M HNO₃ concentrations.     

短链聚苯乙烯稀溶液粘度及渗透压行为

本文用动态膜渗透压及粘度法测定了短链聚苯乙烯的分子量Mn, 第二virial系数A2及特性粘数[η], 得到聚苯乙烯(2.5×10^3, 均方末端距以及扩张因子αs均与报道值一致。本工作表明, 分子量大约在400-1.5×10^4之间, 为聚苯乙烯从小分子到高分子的过渡区, 此时短链聚苯乙烯以蠕虫形链存在于溶液中。     

Migration behaviour and separation of tramadol metabolites and diastereomeric separation of tramadol glucuronides by capillary electrophoresis

Capillary electrophoresis with UV detection was used to separate tramadol (TR), a centrally acting analgesic, and its five phase I (M1, M2, M3, M4, M5) and three phase II metabolites (glucuronides of M1, M4 and M5). Several factors were evaluated in optimisation of the separation: pH and composition of the background electrolyte and the influence of a micellar modifier, sodium dodecyl sulfate. Baseline separation of TR and all the analytes was obtained with use of 65 mM tetraborate electrolyte solution at pH 10.65. The lowest concentrations of the analytes that could be detected were below 1 microM for the O-methylated, below 2 microM for the phenolic and ca. 7 microM for the glucuronide metabolites. The suitability of the method for screening of real samples was tested with an authentic urine sample collected after a single oral dose (50 mg) of TR. After purification and five-fold concentration of the sample (solid-phase extraction with Oasis MCX cartridges), the parent drug TR and its metabolites M1, M1G, M5 and M5G were easily detected, in comparison with standards, in an interference-free area of the electropherogram. Diastereomeric separation of TR glucuronides in in vitro samples was achieved with 10 mM ammonium acetate-100 mM formic acid electrolyte solution at pH 2.75 and with basic micellar 25 mM tetraborate-70 mM SDS electrolyte solution at pH 10.45. Both separations showed that glucuronidation in vitro produces glucuronide diastereomers in different amounts. The authentic TR urine sample was also analysed by micellar method, but unambiguous identification of the glucuronide diastereomers was not achieved owing to many interferences.     

自探针荧光法研究十二烷基苯磺酸钠与TritonX-100相互作用

采用荧光光谱法研究了十二烷基苯磺酸钠（SDBS）与非离子表面活性剂TritonX-100混合体系在水溶液中聚集体的性质。 发现在浓度与荧光强度的关系曲线上存在2个转折点,分别对应于混合体系的临界胶团浓度和胶团形状发生转变的浓度。 通过混合胶团相互作用关系,计算了SDBS与TritonX-100的相互作用参数βM,说明SDBS以其自身所带生色基团苯磺酸与TritonX-100发生了协调效应且存在着较强的相互作用。     

Analysis of osmotic pressure data for aqueous protein solutions via a multicomponent model

Integral equation theories and Monte Carlo simulations were used to study the Donnan equilibrium, which is established by an equilibrium distribution of a simple electrolyte between an aqueous protein-electrolyte mixture and an aqueous solution of the same simple electrolyte, when these two phases are separated by a semipermeable membrane. In order to describe the unusually low osmotic pressure found in many experiments we assumed that protein molecules can form dimers. The model solution contains proteins in a monomeric form, represented as charged hard spheres, or in a dimerized form, modeled as fused charged hard spheres. The counterions and coions were also modeled as charged hard spheres but of a much smaller size. The associative mean spherical and hypernetted-chain approximations were applied to this model. In addition, Monte Carlo computer simulations were performed for the same model system mimicking a lysozyme solution in the presence of 0.1 M sodium chloride. Theory and simulations were found to be in reasonably good agreement for the thermodynamic properties such as chemical potential and osmotic pressure under these conditions. Using the theoretical approaches mentioned above, we analyzed the experimental data for the osmotic pressure of bovine serum albumin in 0.15 M sodium chloride, human serum albumin solution (HSA) in 0.1 M phosphate buffer, and lysozyme in sulphate and phosphate buffers. The theoretically determined osmotic coefficients were fitted to the existing experimental data in order to obtain the fraction of dimers in solution. Our analysis indicated that there was relatively small self-association of protein molecules for bovine serum albumin solutions at pH=5.4 and 7.3, with the fraction of dimers smaller than 10%, while at pH=4.5 the dimer fraction was equal to 50%. In the case of HSA solutions, strong negative deviations from the ideal value were found and at pH=8.0 a reasonably good agreement between the theory and experiment is obtained by assuming full dimerization. For HSA solution at pH=5.4, the best fit to the experimental results was obtained for a fraction of dimers equal to 80%.     

The influence of complexing agents on the effectiveness of electrochemical masking with anionic surfactants in anodic stripping voltammetry

The influence of sodium dodecyl sulphate, sodium dodecyl sulphonate and sodium stearinate on the anodic stripping peaks of Tl(I), Pb(II), Cd(II), Cu(II) and In(III) was investigated. The supporting electrolytes were 0.5M sodium sulphate solution, 0.2M citrate solution (pH 3.7, 4.6 and 7.3), 0.5M tartrate solution (pH 4.4) and 0.1M solution of EDTA (pH 4.4). The composition of complex compounds forming in a solution under experimental conditions was defined. The conditions of ion reduction of metals on hanging mercury electrode during the electrolytical deposition were investigated. The investigation included an analysis of voltammetric curves of the metal ions. The obtained results suggest that "electrochemical masking" is much stronger in electrolytes containing a complexing agent than in the sodium sulphate solution. The influence of the complexing agent may not be explained in terms of the interaction between the form of the complex and the charge of the adsorbed surfactant particles; rather the complexing process is connected with indirect inhibition, i.e., by decreasing the rate of charge transfer reaction.     

新型八甲氧苯氧基取代的对称两层三明治化合物M[Pc(MeOPhO)8]2的合成和谱学表征(英)

在回流的正戊醇中，以RE(acac)₃·nH₂O (acac=乙酰丙酮一价阴离子)为模板，以DBU(1，8-二氮杂双环[5.4.0]十一烯-7)作催化剂，在回流的正戊醇中与4，5-二(4-甲氧苯氧基)邻苯二甲氰反应，我们合成了一系列的15个新型稀土对称二层配合物M[Pc(MeOPhO)₈]₂[M=Y，La，Ce，Pr，Nd，Sm，Eu，Gd，Tb，Dy，Ho，Er，Tm，Yb，Lu；H₂Pc(MeOPhO)₈=2，3，9，10，16，17，23，24-八(4-甲氧苯氧基)酞菁]。整个系列的对称二层配合物主要借助于UV-Vis，IR谱学手段得到充分的表征。所有的研究表明在两个大环之间存在强烈的π-π相互作用，空穴主要位于酞菁大环配体上。     

酸性介质中丙烯基硫脲对铜阳极溶出和阴极沉积过程影响的EQCM研究

采用循环伏安(CV)和电化学石英晶体微天平(EQCM)方法研究了酸性介质中铜阳极溶出和阴极沉积过程以及丙烯基硫脲(AT)对该过程的影响. 结果表明, 铜阳极溶出和阴极沉积过程的M/n分别为32.0和34.2 g/mol, 都是两电子过程, 其间未检测到Cu(Ⅰ)中间产物. AT改变了铜阳极溶出和阴极沉积的历程. 在含AT的溶液中, 铜阳极溶出和阴极沉积过程的M/n分别为61.9和65.4 g/mol, 可指认铜阳极溶出产物为CuAT+, 并提出了AT存在下Cu阳极溶出和阴极沉积过程的反应机理; 从电极表面质量定量变化的角度提供了Cu阳极溶出和阴极沉积过程的新数据.     

Matrix-assisted laser desorption/ionization mass spectrometry with re-engineered 2,5-dihydroxybenzoic acid derivative

Dihydroxybenzoic acid was modified to three analogues (M2, M4 and M6). The analogues exhibited specific properties that resulted in enhancement of analyte signal intensity with or without addition of iodine compared to the underivatized parent. Addition of iodine to M2, an ester of dihydroxybenzoic acid that had a terminal double bond in the alkyl chain, resulted in peak intensities comparable to the parent, indicating that iodine interaction across the double bond resulted in enhancement although the exact mechanism is not fully understood. No enhancement on addition of iodine was observed for M4, which had a long alkyl chain that contained no double bonds. The alkyl chain allowed micelle formation in solution, which in turn allowed more uniform analyte-to-matrix mixing. The final analogue combined the long alkyl chain of M4 with the double bond of M2 and exhibited either similar peak intensities to that of dihydroxybenzoic acid or better. Micelle formation in solution was examined using spectroscopy and in the solid by reflective microscopy. The standard deviation from spot to spot was considerably lower relative to dihydroxybenzoic acid (RSD 3.4%vs. 14.2%). Unlike dihydroxybenzoic acid, the novel matrix M6 was able to yield characteristic peaks for analytes such as ubiquitin.     

The influence of the ethanol-water molar ratio in the precursor solution on morphology and photocatalytic activity of pyrolytic ZnO films

Zinc oxide films were fabricated by a homemade spray pyrolysis system equipped with an optical setup ensuring the in situ control of the film growth. Zinc acetate (0.1 M) diluted in a mixture of ethanol and water was used as the precursor solution. The ethanol-water molar ratio, gamma, in the precursor solution was varied from 0 to 0.92. The deposition temperature and the pH of the precursor solution were kept at 350 degrees C and 4.5, respectively. X-ray diffraction patterns revealed that films were zincitelike with a grain size depending on the ethanol-water molar ratio in the precursor solution. The interference pattern obtained during film deposition was used to monitor the film roughness; it was found that this is related with those results of surfaces and optical analysis obtained by scanning electron microscopy and spectrophotometric measurements, respectively. The morphology of the ZnO films obtained from gamma equal to either 0 or 0.92 are dense with agglomerates uniformly distributed, whereas the films obtained from gamma equal to either 0.03 or 0.06 are very rough with irregular agglomerates. The films obtained from gamma equal to 0.12, 0.18 and 0.31 are rough. Photoelectrocatalytic results indicated that there is a correlation of the partial molar volume of ethanol with respect to water in the spraying solution, with the photocatalytic efficiency of the ZnO films. We found that the maximum photodegradation of methyl orange in the solution occurs using ZnO films obtained with gamma = 0.12.     

Radiolysis of cyanocobalamin (vitamin B12)

Research on the radiolysis of vitamins is of considerable interest since these compounds are important nutritional constituents in foods and in dietetic supplements. In spite of these considerations there are few data and very often difficult to compare for the radiolytic behavior of vitamins. In this work we focused our attention on to the study of the radiolysis of cyanocobalamin (vitamin B₁₂) in solid state and in aqueous solutions. The procedure was followed by HPLC and UV-spectroscopy. The results obtained in aqueous solutions showed a dependence of the decomposition as a linear function of the dose. The G of decomposition for a 1×10⁻⁵ M solution was 3.3. In the solid state the vitamin was very stable towards the irradiation in the conditions used in this study with a G=2.1×10⁻³. A study made with Serratia marcescens as a microbiological contaminant showed that at the sterilization dose there is a destruction of the vitamin in aqueous solution. In the solid state the degree of decomposition was 7%.     

The determination of copper at thin film electrodes by constant current stripping potentiometry

A comparison of the determination of copper by constant current stripping potentiometry (CCSP) at mercury and gold films has been carried out. The preferred solution conditions for the mercury film study were determined to be 0.1M ammonium acetate at pH 4.5 and 0.1M HCl for the gold film study. The influence of chloride on the stripping signal was investigated and it was found that for the mercury film conditions, well-formed stripping signals could be obtained up to a chloride concentration of 0.5 M which permitted the ready determination of copper in seawater. With the gold film, high chloride concentrations affected both the film stability and the glassy carbon surface and repeatable results were difficult to obtain. The optimized CCSP methods were applied to various aqueous samples including tap water, seawater, TCLP (acetic acid) extracts as well as TCLP extracts using groundwater and ocean water. Based on the results obtained for these various matrices, it was concluded that there are several advantages favoring the mercury film. The interference from organic components in the sample matrix on the general applicability of CCSP for the determination of copper at either a mercury or gold film is discussed.     

Effects of Ascorbic Acid on PVS2 Cryopreservation of Dendrobium Bobby Messina’s PLBs Supported with SEM Analysis

Regrowth of the cryopreserved protocorm-like bodies (PLBs) of Dendrobium Bobby Messina was assessed based on the plant vitrification solution 2 (PVS2) optimisation conditions. The optimized protocol obtained based on TTC spectrophotometrical analysis and growth recovery were 3–4 mm of PLBs size precultured in 0.2 M sucrose for 1 day, treated with a mixture of 2 M glycerol and 0.4 M sucrose supplemented with half-strength liquid MS media at 25 °C for 20 min and subsequently dehydrated with PVS2 at 0 °C for 20 min prior to storage in liquid nitrogen. Following rapid warming in a water bath at 40 °C for 90 s, PLBs were treated with unloading solution containing half-strength liquid MS media supplemented with 1.2 M sucrose. Subsequently, the PLBs were cultured on half-strength semi-solid MS media supplemented with 2 % (w/v) sucrose without any growth regulators and resulted in 40 % growth recovery. In addition, ascorbic acid treatment was used to evaluate the regeneration process of cryopreserved PLBs. However, growth recovery rates of non-cryopreserved and cryopreserved PLBs were 30 and 10 % when 0.6 mM ascorbic acid was added. Scanning electron microscopy analysis indicates that there are not much damages observed on both cryopreserved and non-cryopreserved PLBs in comparison to PLBs stock culture.