聚乙二醇中1-辛炔的环三聚反应

在绿色反应介质聚乙二醇中,PdCl2／CuCl2催化体系可以顺利地催化1-辛炔发生环三聚反应,区域选择性地生成1,3,5-三己基苯,该反应产率较高,对环境友好,且催化体系可以适当地重复使用．     

The electron beam technique in carbon monoxide: Density and quenching rates

Electron-induced emissions of the First Negative System of CO⁺ were studied in CO and Ar+CO(10%) free jets. The mechanisms of the excitation–emission process were analysed to make use of the electron beam technique in CO as well as in a CO+Ar mixture. It was shown that more than 85% of the (0,0) band emission was excited by primary electrons. Rate constants of collisional quenching of the CO⁺(B) state by CO and Ar were measured at low (<200 K) temperatures. The negative temperature dependence of the quenching rates is in qualitative agreement with the results obtained for other molecular ions.     

Characteristics of alternating current hopping conductivity in DNA sequences

This paper presents a model to describe alternating current (AC) conductivity of DNA sequences, in which DNA is considered as a one-dimensional (1D) disordered system, and electrons transport via hopping between localized states. It finds that AC conductivity in DNA sequences increases as the frequency of the external electric field rises, and it takes the form of σ_ac (ω)～ω ²\ln ²(1/ω). Also AC conductivity of DNA sequences increases with the increase of temperature, this phenomenon presents characteristics of weak temperature-dependence. Meanwhile, the AC conductivity in an off-diagonally correlated case is much larger than that in the uncorrelated case of the Anderson limit in low temperatures, which indicates that the off-diagonal correlations in DNA sequences have a great effect on the AC conductivity, while at high temperature the off-diagonal correlations no longer play a vital role in electric transport. In addition, the proportion of nucleotide pairs p also plays an important role in AC electron transport of DNA sequences. For p < 0.5, the conductivity of DNA sequence decreases with the increase of p, while for p ≥ 0.5, the conductivity increases with the increase of p.     

Synthesis and Bioactivity of a Novel Bismuthoxide Schiff-base Complex Derived from Salen-like Ligand and Bismuth(Ⅲ) Nitrate

In this paper, a novel bismuthoxide Schiff-base complex [Bi₉O₈(vanen)₃(NO₃)₂(CH₃OH)₂(H₂O)·3NO₃·5.5H₂O](abbreviated as Bivanen) was synthesized with Salen-like ligand H₂vanen[H₂vanen=N,N'-ethylene bis(3-methoxysalicylideneimine)] and bismuth(Ⅲ) nitrate. Its structure was characterized by IR spectra, NMR spectra and X-ray diffraction. In particular, the biology activities of the ligand and the complex against Schizosaccharomyces pombe(S. pombe) were studied using biological microcalorimetry. The metabolic thermogenic curves of S. pombe were measured at 32.00℃. Then, some quantitative thermokinetic parameters of growth metabolism of S. pombe including the rate constant(k), inhibition ratio(I) and half inhibition concentration(IC₅₀) were calculated. Experimental results showed that the k values of S. pombe decreased while I values of S. pombe increased with the increase of concentrations of the ligand and the complex. The IC₅₀ of the ligand and the complex were found to be 0.067 and 0.037 mmol/L, respectively.     

Lithium Distribution in Red Blood Cells and Plasma: NMR Studies of Rat Blood

To understand the interaction of lithium (Li⁺) with a coadministered drug in both the blood and the brain, we have treated rats with either Li⁺ alone or Li⁺ and a codrug. In this paper we address the important problem of quantitation of intra and extracellular Li⁺ ion contents in blood by the ⁷Li-NMR technique and the use of a shift reagent (SR). Although Li⁺ can be studied by atomic absorption techniques, these techniques involve tedious separation of intra- and extracellular components prior to chemical analysis. Magnetic resonance studies on rat blood, in the dose range of 0.5 to 10 meq/kg, indicate that the intracellular red blood cell Li⁺ predominates in the lower dose range of 0.5–1.0 meq/kg. As the lithium dose increases, a significantly larger amount of Li⁺ accumulates in the extracellular volume. Our studies on a number of animals at various doses of LiCl indicate that ⁷Li-NMR of blood samples provide a reliable, noninvasive quantification of red blood cell and plasma Li⁺ concentrations. The NMR method was further used to study the effect of coadministered drugs such as thioridazine on the intra- and extracellular Li⁺ concentration of RBCs.     

火焰原子吸收光谱法测定黄芪、甘草、广藿香中的铜

用硝酸-高氯酸混合酸(4 1)消解黄芪、甘草、广藿香,在波长324.7nm处,用火焰原子吸收光谱法测定黄芪、甘草、广藿香中铜的含量.线性回归方程为A=0.1861C 0.0007,相关系数r=0.9998,线性范围为0-7μg/mL,检出限为0.0032μg/mL,测定结果的相对标准偏差为0.061%,加标回收率为98.7%-103.0%.     

Computer-aided acquisition and processing of data for caloric measurements with isoperibol calorimeters

The undisturbed temperature equilibration of the vessel in an isoperibol calorimeter must follow an exponential time function. Any caloric effect within this vessel must cause a deviation of this function. A mathematical relation has been derived for linking the extent of this caloric effect and the integral of the temperature-time function.This algorithm has been utilized for a computer program capable for an automatic acquisition of the data of an appropriate digital temperature meter and for the automatic calculation of the calorimetric results.In two different calorimetric units these arrangements have been applied for the following determinations: -specific heat capacities of liquid samples -heats of chemical reactions -reaction rates -heats of vaporization of liquid samples.     

A Piezoelectric Screw Dislocation Interacting with an Elliptical Piezoelectric Inhomogeneity Containing a Confocal Elliptical Rigid Core

The electro-elastic interaction between a piezoelectric screw dislocation and an elliptical piezoelectric inhomogeneity, which contains an electrically conductive confocal elliptical rigid core under remote anti-plane shear stresses and in-plane electrical load is dealt with. The analytical solutions to the elastic field and the electric field, the interfacial stress fields of inhomogeneity and matrix under longitudinal shear and the image force acting on the dislocation are derived by means of complex method. The effect of material properties and geometric configurations of the rigid core on interfacial stresses generated by a remote uniform load, rigid core and material electroelastic properties on the image force is discussed.     

Fast Laplace transform methods for the PDE system of Parisian and Parasian option pricing

Science China Mathematics - This paper develops a fast Laplace transform method for solving the complex PDE system arising from Parisian and Parasian option pricing. The value functions of the...     

Buchwald-Hartwig Amination of Coordinating Heterocycles Enabled by Large-but-Flexible Pd-BIAN-NHC Catalysts**

A new class of large-but-flexible Pd-BIAN-NHC catalysts (BIAN=acenaphthoimidazolylidene, NHC=N-heterocyclic carbene) has been rationally designed to enable the challenging Buchwald-Hartwig amination of coordinating heterocycles. This robust class of BIAN-NHC catalysts permits cross-coupling under practical aerobic conditions of a variety of heterocycles with aryl, alkyl, and heteroarylamines, including historically challenging oxazoles and thiazoles as well as electron-deficient heterocycles containing multiple heteroatoms with BIAN-INon (N,N′-bis(2,6-di(4-heptyl)phenyl)-7H-acenaphtho[1,2-d]imidazol-8-ylidene) as the most effective ligand. Studies on the ligand structure and electronic properties of the carbene center are reported. The study should facilitate the discovery of even more active catalyst systems based on the unique BIAN-NHC scaffold.