Enantioselective Hydrogenation of Acetophenone over Cinchonidine-Stabilized and Supported Rhodium Clusters

Because of the importance of the chirality in chemicals in everyday, the synthesis of enantiomerically pure chiral compounds has become an important academic and commercial advantage. In asymmetric synthesis field, enantioselective catalysis has been the most challenging subject over the past decades. Among the numerous enantioselective heterogeneous catalysts, the rhodium is always an unsuccessful example under favorable reaction conditions with only 20%-30% enantiomeric excess (e.e.)^[1].And almost all of papers about heterogeneous enantioselective catalysis have reported that rhodium is not suitable for heterogeneous enantioselective hydrogenation^[1-3].     

基体改进效应应用于石墨炉原子吸收测定汞

微克量贵金属可以改进基体,以防止汞在干燥和灰化过程中的严重损失.钯存在时,最高允许灰化温度为500℃,比应用硫化铵所能达到的灰化温度高200℃,并且干扰少,又不需要任何分离步骤,可用以测定废水中的痕量(0.2毫微克)汞.     

Monte Carlo data of dilute solutions of large spheres in binary hard sphere mixtures

Monte Carlo (MC) simulation data for additive binary hard sphere mixtures are reported for dilute concentrations of the large sphere. Using a single occupancy linked cell method, binary hard sphere solutions with a size ratio of 5 are simulated at high reduced density and low concentration of the large sphere. Data for the solute-solvent pair distribution function show that at the lowest concentrations of the large sphere simulated, the Boublik-Mansoori-Carnahan-Starling-Leland (BMCSL) equation underestimates the contact value; whereas the recently proposed Henderson-Chan (HC) equation gives a good prediction. For the solute-solute contact value at the colloidal limit, the MC data lie between the two predictions. The BMCSL equation underestimates, while the HC equation overestimates, the correct solute-solute contact value.     

Diffusivity and conductivity of a primitive model electrolyte in a nanopore

Equilibrium and non-equilibrium molecular dynamics simulations are applied to obtain the diffusion coefficient and electric conductivity of ions in dilute electrolytes confined in neutral cylindrical pores. The electrolyte is described with the restricted primitive model and the wall of the pore is modelled as a soft wall. The equilibrium molecular dynamics simulations show that the axial diffusion coefficient of ions decreases with increasing confinement. For a fixed pore radius the diffusion coefficient decreases with increasing number density of the ions. The current response of the system to an applied electric field is maintained at constant temperature by Gaussian isokinetic equations of motion, and at constant concentration by periodic boundary conditions with recycling of ions in the axial direction. The electric conductivity is calculated from the current density and the electric field applied for different pore sizes. In contrast to the trend in diffusivity, conductivity increases slightly in smaller pores. For a very small pore, however, conductivity is lower than the bulk, because oppositely charged ions moving in opposite directions under the electric field cannot avoid collisions with each other in a narrow channel.     

高效液相色谱法测定2种中药片剂中紫丁香苷的含量

建立了测定2种中药制剂灭澳灵片和活络消痛片中紫丁香苷含量的高效液相色谱方法.采用KromasilC18反相色谱柱(5μm,250 mm×4.6 mm),以乙腈-1%冰醋酸溶液(体积比10∶90)为流动相,流速1.0 mL/min,检测波长265 nm,在15 min内完成分离检测.紫丁香苷在0.16~100μg/mL范围内呈良好的线性关系(r=0.9999),最低检出限0.1μg/mL(S/N=3).灭澳灵片的加样回收率为92.2%~97.6%,活络消痛片的加样回收率为94.0%~102.6%.     

New Chiral Ligand N-Toluenesulfonyl-2,2′-dimethoxy-6,6′-diaminobiphenyl for Catalytic Asymmetric Transfer Hydrogenation of Ketones

Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｏｐｔｉｃａｌｌｙａｃｔｉｖｅｓｅｃｏｎｄａｒｙａｌｃｏｈｏｌｓａｒｅｕｓｅｆｕｌｂｕｉｌｄ ｉｎｇｂｌｏｃｋｓｆｏｒｐｈａｒｍａｃｅｕｔｉｃａｌｓ ,ａｇｒｏｃｈｅｍｉｃａｌｓａｓｗｅｌｌａｓｏｔｈｅｒｍａｔｅｒｉａｌｓ .1Ａｖａｒｉｅｔｙｏｆａｓｙｍｍｅｔｒｉｃｃａｔａｌｙｔｉｃｒｅａｃ ｔｉｏｎｓｈａｖｅｂｅｅｎｄｅｖｅｌｏｐｅｄｆｏｒｐｒｅｐａｒｉｎｇｓｕｃｈｉｍｐｏｒｔａｎｔｓｅｃｏｎｄａｒｙａｌｃｏｈｏｌｓ .2 Ｉｎａｄｄｉｔｉｏｎｔｏｓｔｒａｉｇｈｔｆｏｒｗａ…     

1,3—二烯基—1,1,3,3—四甲基二硅氧烷／苯乙烯共聚物的合成及其热性能

１，３二烯基１，１，３，３四甲基二硅氧烷／苯乙烯共聚物的合成及其热性能王文俊（浙江大学高分子科学与工程研究所杭州３１００２７）ＳＨＩＮＦｒａｎｋｌｉｎＧ．１，２，ＣＨＡＮＴ．Ｃ．１，３（香港理工大学１材料研究中心２应用物理学系３应用生物及...     

1,3-二烯基-1,1,3,3-四甲基二硅氧烷/苯乙烯共聚物的合成及其热性能

有机硅聚合物具有柔软、耐热、耐水、抗生物污染等优点,若在聚合物中引入其它官能团,可进一步改善其性能,扩大应用领域,如:气体分离膜[1,2]、耐紫外线及X-射线材料[3]、半导体材料[4]、药物载体[5]、液晶材料[6]、阻燃材料[7]等.特别是含硅烷基苯乙烯衍生物系列的聚合物,其膜适用于氧等气体的分离,近来出现许多研究报道[1,2,8,9].     

Toeplitz Preconditioners for Toeplitz Systems with Nonnegative Generating Functions

The preconditioned conjugate gradient method is employed tosolve Toeplitz systems T_nx = b where the generating functionsof the n-by-n Toeplitz matrices T_n are continuous nonnegativeperiodic functions defined in [–,]. The preconditionedC_n are band Toeplitz matrices with band-widths independent ofn. We prove that the spectra of C_n^-1T_n are uniformly boundedby constants independent of n. In particular, we show that thesolutions of T_nx = b can be obtained in O(nlogn) operations.     

Synthesis of Pyrrole-Imidazole Polyamide

Small molecules that target specific predetermined DNA sequences have the potential tocontrol gene expression'. Realization of the high affinity binding and specific recognitionof DNA sequences by organic molecules is one of the focuses of biological chemistry.The natural products netropsin and distamycin are N-methylpyrrole containing di- andtripeptides, with binding specificity at sites of successive A.T or T.A base pairs of DNAin the minor groove'. Recently, N-methylimidazole is intro…