罗丹明B—I3^—离子缔合物共振散射测定环境水样中的铬（Ⅵ）和铬（Ⅲ）

研究在磷酸介质中,罗丹明B与I3^-的离子缔合物的共振散射光谱。确定了散射光强度与溶液中Cr(VI)浓度的关系。提出了共振散射测定Cr(VI)的新方法,方法的检出限为2．2ug/L,线性范围为10．0－500ug/L,结合离子交换分离法,用于环境水样中铬的形态分析,结果满意。     

VISCOELASTIC BEHAVIOR OF THE NON-HOOKE DEFORMATION BEFORE YIELDING IN UNIAXIAL DRAWING OF AMORPHOUS POLY(ETHYLENE TEREPHTHALATE)*

Viscoelastic behavior of the non-Hooke deformation of amorphous PET film before yield was investigated in thetemperature region 74--80.5℃ around the glass transition temperature. The film specimen was drawn to yield point followedby unloading to zero stress, then the residual deformation was held constant, while the subsequent evolution of the stress wasrecorded. An induction period was found in the course of stress evolution fol1owed by a stress step-increase. The inductionperiod decreases with increasing drawing temperature with an activation energy of 1.10 MJ/mol·K, which is attributed tothe time needed for the relaxation of rubbery deformation through cooperative internal rotations. At temperatures lower than74℃, there is no stress increase or the induction period becomes too long to be observed. Thus the nature of anelasticity inthe non-Hooke region before yielding is attributed to stress induced rubbery deformation. The experimental results areinterpreted in terms of Perez' rheological model of a series connected Hooke spring and a Voigt element consisting of aparallel connected elastic spring and a dashpot.     

光合反应中心原初电子转移机理的理论研究

用量子化学密度泛函B3LYP方法在3-21G水平上计算细菌光合反应中心原初电子给体P960和绿色植物PSⅡ光合反应中心原初电子给体P680的电子结构,然后研究轴向配位的组氨酸残基和周围蛋白质环境的影响,最后探讨其原初电子转移机理。计算结果表明：(1)细菌光合作用反应中心原初电子给体P960-h的HOMO主要是由与M分支相连的组成单元上原子的原子轨道组成,而它的LUMO则两个组成单元上原子的原子轨道都有贡献;PSⅡ反应中心中原初电子给体P680的HOMO和LUMO均主要由与D1蛋白相连的组成单元上原子的原子轨道组成。这些计算结果能够从反应中心最核心的部分-原初电子给体的电子结构方面解释Rps.uiridis反应中心和PSⅡ反应中心原初电子转移只沿一个分支进行的的途径选择性。(2)虽然与细菌反应中心原初电子给体超分子P960的两个细菌叶绿素分子形成轴向配位的组氨酸残基His并未参与超分子P960-h的HOMO和LUMO的组成,但是由于其轴向配位,使得P960-h的ELUMO显著地升高到高于辅助细菌叶绿素和去镁细菌叶绿素的相应值,使得原初电子转移反应能够顺利进行。否则原初电子转移反应很难进行。PSⅡ反应中心的情况,与细菌反应中心十分相似。(3)细菌反应中心辅助细菌叶绿素(ABChlb)中的Mg离子与最近的组氨酸残基His中的N原子的距离和原初电子给体P960中的相应的Mg-N的距离相似,因此同样应该考虑此轴向配位的组氨酸残基,此时原初电子转移反应是沿L分支从P960-h经ABChlb到去镁细菌叶绿素(BPheob)的两步电子转移过程。而PSⅡ反应中心的辅助叶绿素不存在His的轴向配位,这应是与细菌反应中心的重要区别之一,此时原初电子转移应是沿Dl分支从P680-h到Pheoa的一步电子转移过程,但同时也不能完全排除从P680-h到AChla到Pheoa的二步电子转移过程。     

Oryzias latipes鱼体对不同形态镧的积累特征

在试验室条件下研究了Oryzias latipes鱼体对不同形态轻稀土La的积累特征及它对游离La吸收的动力学过程,并初步探讨了鱼对La的吸收机制。结果表明,试验鱼对La的积累量随水相游离La浓度增高、暴露时间增长而增加;水相富里酸的存在明显降低了La对鱼对生物有效性。此外,试验鱼也可以通过摄食获取水相中的La。     

钌联吡啶单配体双取代基效应

对钌联吡啶配合物及其单配体的4,4′ 双取代衍生物, 用量子化学密度泛函(DFT)方法在B3LYP/LanL2DZ水平上进行计算.探讨一些强的推电子基团(如－OCH3)和强的拉电子基团(如－NO2)的取代基效应对配合物的电子结构与相关性质,如配位键长、光谱性质等的影响规律,为该类配合物的合成,光、电、催化和生化作用机理分析提供理论参考.     

用界面几何约束的多起点蒙特卡罗方法对蛋白质/ 短肽识别体系的对接计算

提出了一个界面几何约束的多起点蒙特卡罗构象搜索方法,并把这个方法用于三个丝氨酸蛋白酶/短肽抑制剂体系的刚性、部分柔性和全部柔性对接计算中。我们的方法成功地预测出了接近晶体结构的配体构象。与没有几何约束相比,我们的几何约束蒙特卡罗方法显示出了更好的收敛性质。     

共线量子散射方法研究D+CID体系

用共线量子散射方法计算D+CID体系的反应几率和传能几率。发现存在很强的振荡现象。体系的碰撞中间态的寿命的计算结果为fs-ps数量级。当某一反应通道打开时,在能量阈值附近通常都伴随着一些长寿命的碰撞中间态。这一点该体系中表现很比较明显。     

Indirect Determination of Ascorbic Acid with Ammonium Sulfate and Ethanol by Extraction and Flotation of Copper

A new method of indirect determination of ascorbic acid with ammonium sulfate and ethanol by extraction and flotation of copper in the presence of thiocyanate has been studied in this paper. The study shows that a small amount of Cu(II) is reduced to Cu(I) by ascorbic acid, then Cu(I) precipitates with SCN^?. In the course of phase separation of ethanol from water, the precipitated CuSCN is extracted and stays in the interface of ethanol and water. A good linear relationship is observed between the extraction yield of Cu(II) and the amount of ascorbic acid. The detection limit for ascorbic acid is 1 10^?5 M. Every parameter has been optimized and the reaction mechanism has been studied. The method is simple, rapid (5 min) and suffers from few interferences of common anions and cations. It has been successfully applied for the determination of ascorbic acid in pharmaceuticals and fruits.     

Rules on pair electron correlation in MOH (M=H,Li, Na)

In this article, the transferable property of pair correlation energies of OH components is discussed for a series of OH containing compounds MOH (M=H, Li, Na). In this series of compounds, from OH free radicals through HOH, LiOH, NaOH to OH^?, both the intra‐ and interpair correlation energies and intra‐ and intershell correlation energies of the inner orbital electrons change little. The 1s$_{\mathrm{O}}^{2}$ is very much alike in all the above OH containing systems and such a pair correlation is transferable. But the interpair correlation and intrashell correlation energies of the valence electrons are large and change a lot in all systems. In MOH molecules, the OH correlation energy contribution increases with the increase of the ionic bond strength of the compound and this contribution is always between the correlation energy values of OH free radicals and OH^? atomic groups. For strong ionic compounds, we present a very simple method to estimate the correlation energy by adding the correlation energies of its component ions within the chemical accuracy (2 kcal/mol). © 2001 John Wiley & Sons, Inc. Int J Quant Chem 83: 311–317, 2001     

Electronegativity Scaled as a Average Attracting Energy of Valence‐Shell Electrons in a Ground‐State Free Atom

The total capability of an atom attracting valence electrons can be measured by the sum of ionization energies of valence electron in a ground‐state free atom plus its electron affinity called Total Attracting Energy, TAE = Σn_iE_i + EA, where, E_i is the ionization energy of the ith valence‐shell electron in a ground‐state free atom, n_i is the number of valence‐shell electron bearing energy E_i, and EA is the electron affinity. And the electronegativity χ_CL is proportional to the average of TAE, AAE = TAE_av, divided by Σn_i, the number of atomic valence‐shell electrons. χ_CL = 0.1813 TAE_av = 0.1813 AAE = 0.1813 TAE/Σn_i, = 0.1813 (Σn_iE_I + EA)/Σn_i. Further, the atomic valence orbital electronegativity can be also obtained from the TAE value of an atom. Some discussions were made on several special aspects such as scale of rare gases, comparisons with Pauling's and Allen's scales, etc.