Physicochemical Studies on Biological Macro- and Microemulsions VI : Mixing Behaviors of Eucalyptus Oil,Water and Polyoxyethylene Sorbitan Monolaurate (Tween 20) Assisted by n-Butanol or Cinnamic Alcohol

The phase behavior of Eucalyptus oil/ Tween 20/ Butanol/ Water and Eucalyptus oil/ Tween 20/ Cinnamic Alcohol/ Water systems have ben studied in detail. Both triangular and tetrahedral representations have been considered to understand the topological nature of the multicomponent mixtures. Shear viscosities of typical multiphasic compositions have been measured at different rates and temperatures. The samples have undergone shear thinning. The effect of temperature on the volumes of multiphasic compositions have been also investigated both increase and decrease of the extents of different phases have been witnessed. The enthalpy of dissolution of both water and oil in presence of amphiphile solutions in oil and water respectively have been determined calorimetrically. Considering the phase separation point to be the point of maximum solubility of microdroplets, the free energies and hence entropies ofsolution have been estimated. The above phy.sicochemical features have been also examined in presence of additives, viz, NaGI and urea.     

ClO与ClO自由基反应机理及电子密度拓扑分析

利用密度泛函理论对ClO与ClO自由基反应机理进行了深入理论探讨,在B3LYP/6-311＋＋G（3df）水平上对该反应体系的反应物、中间体、过渡态及产物进行了几何构型优化,对反应通道进行了IRC(内禀反应坐标）路径解析,计算了沿各反应通道的能垒和离解能,并进行了零点能校正.从量子拓扑学的角度,对反应通道IRC途径上一些重要点进行了电子密度拓扑分析,讨论了反应过程中化学键的断裂、生成以及键的变化规律,找到了反应途径的能量过渡态和结构过渡态.     

3-芳氧基-6-取代哒嗪的合成及其除草活性

合成了系列3-芳氧基-6-取代哒嗪类化合物.化合物结构经¹HNMR、元素分析、IR和MS确证.生物活性测试结果表明,该类化合物具有很好的除草活性,讨论了其结构与除草活性的关系.     

Recent developments in radioanaytical technologies for environmental investigations

Radiometric techniques, specifically underground gamma-ray spectrometry, have been recently widely applied in the analysis of short and medium-lived radionuclides in the environment. Long-lived radionuclides have been mostly analysed by Accelerator Mass Spectrometry and Inductively Coupled Plasma Mass Spectrometry. These developments have considerably improved the detection limits for analysis of radionuclides in the terrestrial and marine environments. They have also decreased required sample volumes so applications, which have not been possible before either because of sample size or required sensitivity, have become feasible. The recent developments are illustrated by applications of radiometric and mass spectrometry techniques in isotope hydrology and oceanography.     

Mass spectra of some oxadiazole derivatives

The mass spectra of some substituted oxadiazoles have been determined and analysed with the aid of high resolution mass spectrometry. Some characteristic and major differences between their spectra have been noted, and possible rationalizations have been advanced. The main fragmentation patterns of the 1,3,4-oxadiazole derivatives have been interpreted in terms of diazirine intermediates. Specific skeletal rearrangement processes have been observed in the spectra of the 1,3,4- and 1,2,4-oxadiazoles, and possible mechanisms are proposed.     

Pt/HM、Pd/HM催化剂上CO氧化反应活性和动力学研究

研究了Pt/HM、Pd/HM催化剂上CO氧化反应的活性,求出了各种催化剂的CO氧化反应动力学方程。考察了不同气氛下CO氧化活性的演变规律和V⁴⁺、Co²⁺离子对Pt、Pd的助催化作用,并用催化剂集团结构适应模型对以上结果作出了解释。     

飞行时间二次离子质谱(TOF-SIMS)结合化学衍生法分析杂环新化合物的结构

飞行时间二次离子质谱(TOF-SIMS)分析了难挥发的杂环新化合物咪唑啉硫氰酸盐及其三种衍生物, 确认出很强的氢离化及银离化准分子离子峰, 通过对各种衍生物谱图的对照分析, 确认出较强的含有结构特征的碎片离子峰, 并对该化合物在离子轰击下的裂解规律作了分析, 支持了对该新化合物结构的鉴定。     

Improved microbiological hydroxylation of sesquiterpenoids: semisynthesis,structural determination and biotransformation studies of cyclic sulfite eudesmane derivatives

Two new cyclic sulfite eudesmane derivatives have been investigated. Their (R) and (S) sulfur configuration and the structural arrangement of their "A" rings have been assigned by means of their 13C and 1H NMR chemical shifts and have been confirmed by single-crystal X-ray analyses. Microbial-transformation of these epimer cyclic sulfites and their dihydroxyeudesmane precursor have been studied using the hydroxylating fungus Rhizopus nigricans. Increased biocatalysis rates and considerable differences in the biotransformation of both cyclic sulfite eudesmanes have been found. Promising 8alpha,11-dihydroxy derivatives have been isolated from the (S)-diastereomer bioconversion.     

Structural and functional characterisation of a biohybrid material based on acetylcholinesterase and layered double hydroxides

This work describes the use of layered double hydroxides (LDHs) for the immobilisation of acetylcholinesterase (AChE) on insulator/semiconductor solid supports. Different LDHs have been synthesised by a co-precipitation method. Afterwards, biohybrid materials based on AChE-LDH mixtures have been produced using wild and recombinant enzymes. Spectroscopic techniques have confirmed the LDH phase identity and the links created between the LDH and AChE. Spectrophotometric assays have demonstrated that most of the biohybrid materials are functional and stable. Several configurations have been used for AChE immobilisation. The highest catalytic responses have been observed when using wild enzyme and immobilising AChE-LDH mixtures on LDHs previously deposited on the solid supports. LDHs have been demonstrated to be suitable host matrices for AChE immobilisation on electrodes for the subsequent development of electrochemical biosensors.     

Differences in Trace Element Concentrations between the Right and Left Hemispheres of Human Brain Using INAA

Very few publications have quoted differences between the same regions in both the right and left hemispheres of the human brain. It may be possible that that the two hemispheres have different trace elemental concentrations, since it is known that they both have different functions. In this study, three brain regions from both the right and left hemispheres of the cortex have been sampled from five elderly individuals (three 'normal' and two Alzheimer's disease) and their elemental concentrations have been determined by instrumental neutron activation analysis (INAA).     

Conformation-activity relationships in polyketide natural products. Towards the biologically active conformation of epothilone

The conformation-activity relationships for the biologically active polyketide, epothilone, have been determined. Computer-based molecular modeling and high field NMR techniques have provided the solution preferences for epothilones and. For the C1-C8 polypropionate region, two conformational families, conformers 1 and 2, have been identified as having significant populations in polar and non-polar solvents. In the C11-C15 region, additional flexibility was observed and two local conformations have been identified as important, conformers 3 and 4. Epothilone analogues with altered conformational profiles have been designed and synthesized. Conformational analysis and the results of biological assays have been correlated to provide increased understanding of the biologically active conformation for the epothilone class of natural product. Conformation-activity relationships have been shown to be an important complement to structure-activity data.     

Theoretical Study of the AICI Disproportionation Reaction Mechanism on the Al(100) Surface

The surface disproportionation reaction mechanism of aluminum subchloride on the aluminum (100) surfaces has been investigated by the plane-wave density functional theory (DFT).Three kinds of possible reaction mechanism of AlCl disproportionation reaction on the aluminum (100)surfaces have been taken into account. The structures of reactants and products have been optimized, transition states have been confirmed and activation energies have been calculated. The adsorption energy of reactants and desorption energy of products have been determined. All of these have been employed to confirm the reaction mechanism and the rate determining step of AlCl disproportionation reaction on the aluminum (100) surfaces.     

Spectroscopic studies of triethoxysilane sol-gel and coating process

Silica sol-gels have been prepared under different conditions using triethoxysilane (TES) as precursor. The prepared sol-gels have been used to coat aluminum for corrosion protection. Vibrational assignments have been made for most vibration bands of TES, TES sol-gel, TES sol-gel-coated aluminum and xerogel. It has been noticed that air moisture may have helped the hydrolysis of the thin coating films. Xerogels have been obtained from the sol-gel under different temperature conditions and the resulting samples have been characterized by using infrared and Raman spectroscopic methods. IR data indicate that the sol-gel process is incomplete under the ambient conditions although an aqueous condition can have slightly improved the process. Two nonequivalent silicon atoms have been identified from the collected (29)Si NMR spectra for the sol-gel, supporting the result derived from the IR data. The frequency of SiH bending vibration has been found to be more sensitive to the skeletal structure than that of the SiH stretching vibration. A higher temperature condition could favor the progression of hydrolysis and condensation. A temperature higher than 300 degrees C would cause sample decomposition without seriously damaging the silica network. From infrared intensity measurements and thermo-gravimetric analyses, the fractions of incomplete hydrolysis and condensation species have been estimated to be 4% and 3%, respectively. Electrochemical data have shown that the sol-gel coating significantly improves the corrosion protection properties of aluminum.     

CRETACEOUS MAGNETOSTRATIGRAPHY IN THE SONGLIAO BASIN, CHINA

This paper is the result of research on the Cretaceous magnetostratigraphy in the Songliao Basin. The palaeomagnetic experiment on 2235 specimens from 24 drills and an outcrop profile in Quantou shows that most specimens have stable remanent magnetization.The features of polarities associated with all the rock formations of the Cretaceous in the Songliao plain have been summarized. The reversed polarity zones have been found in the Yingcheng, Dcnglouku, Yaojia and Nenjiang Formations. These reserved-polarity zones and their geologic ages have been argued. Accordingly. the polarity columns for different drills and a comprehensive column have been compiled, and the classification and correlation of the Cretaceous stratigraphy in the Songliao Basin have been discussed.     

Energetics and metastability of the adenine dication observed in proton-adenine collisions

We present here a study that deals with the correlated fragmentation of a doubly charged adenine molecular target induced by a 100 keV proton beam. We have elucidated part of the dissociation dynamics for several channels and have obtained the corresponding kinetic energy released values. We have extracted activation energies by combining our experimental data with computations using the ab initio GAMESS code. We have observed metastability patterns against fragmentation, for which we have extracted the temporal mechanism (one or two steps). Subsequently, we have obtained lifetimes in the 100-200 ns range. In the simplest case of two-body fragmentation with the emission of mass 28, the determination of transition states and reaction paths has showed that emission of the H-C-N-H fragment is preferred to that of C-N-H(2). From the calculated activation barriers and lifetimes, we have deduced an equivalent temperature of the dication that we have compared with the existing models.     

Phase structure of silanol-modified ethylene-vinyl acetate copolymers

For (ethylene-vinyl acetate copolymer)-tetraethoxysilane and (ethylene-vinyl acetate copolymer)-polydimethylsiloxane systems, the solubility of components has been studied in a wide range of temperatures and compositions. Phase diagrams have been constructed, pair interaction parameters have been calculated, and diffusion coefficients and activation energies of diffusion have been estimated. The temperature and concentration ranges of a change in solubility related to chemical interactions between the components have been revealed, and the structure of the modified copolymers has been studied. On the basis of the kinetic data on the movement of isoconcentration planes in diffusion zones of component mixing, time intervals corresponding to the onset of the chemical reaction between the components have been determined and the apparent activation energies of the process have been computed. Complex-shaped binodal and boundary curves have been interpreted within the framework of the classical Flory-Huggins theory.     

Approximations of the nucleus size spectrum in nucleation kinetics under gradually varied external conditions

Several simple approximations have been presented for describing evolution of a condensing system at the stage of nucleation under dynamic conditions. All of them have been compared with the exact numerical solution, and their errors have been determined. All relative errors have been shown to be rather small.     

C~6~0^2^-单态和三态的结构和光谱性质

用INDO系列方法对C~6~0^2^-单态和三态分别进行了几何构型优化, 得到D~2~h对称性的构型, 表明C~6~0^2^-确实发生了Jahn-Teller畸变, 导致双键变长, 形成15种键, 9种不等同碳原子, 其额外负电荷主要分布在赤道附近, 以此构型为基础,计算了C~6~0^2^-的电子光谱, 与实验值基本一致, 对光谱进行了理论指认, 说明了光谱红移的原因。     

Synthese de substances macromoleculaires renfermant des motifs monomeres derives de colorants—XIX: Synthese d'oligoethers et d'oligoesters colores par structure

Oligo-oxyethylenes and oligo(oxyethylenes-Co-oxypropylenes) with hydroxy end-groups have been modified by nitration and amination of the end-groups; the modification was partial in some cases and complete in others. Amino end-groups have been diazotized and the oligomers with azo end-groups have been coupled with β oxynaphthic acid and N,N′diethylaniline. Oligomers with chromophoric and hydroxy groups in the chain have been used to prepare polyurethane foams. Structurally coloured polyesters have been synthesized similarly and used to prepare polyurethane elastomers. All these oligomers have been characterized by i.r. and visible spectroscopy, NMR, end-group titration, vapour pressure osmometry and thermal differential analysis.     

Na2CrO4-NaF-NaI and K2CrO4-KF-KI three-component systems

Na₂CrO₄-NaF-NaI and K₂CrO₄-KF-KI three-component systems have been studied by differential thermal analysis (DTA). The compositions and melting temperatures have been determined and the enthalpies of melting have been measured for eutectic mixtures. Phase equilibria in the title systems have been described, and phase fields have been demarcated.