2,3-环氧羧酸-对-溴苯甲酰甲基酯的合成及其抗菌活性

环氧化合物,尤其是2,3-环氧羧酸类化合物既是一类重要的有机合成中间体,又是一类很有前途的生物活性物质,并广泛存在于自然界中,与生物体内的生理生化过程紧密相连。文献报导环氧化合物具有杀虫、杀螨、杀菌和生长调节的活性。Hendlin等从链霉菌的发酵液中分离到一种抗菌素(膦霉素),证明其为广谱的杀菌剂,其结构为2,3-环氧丙膦     

对映选择催化环丙烷化反应中活性铜催化剂组成的测定

对映选择催化环丙烷化反应中活性铜催化剂组成的测定臧二乐，李萍，胡秉方（北京农业大学应用化学系，北京１０００９４）关键词铜络合物，催化机理，环丙烷化手性铜（Ⅱ）络合物已广泛应用于催化环丙烷化反应［１，２］．关于反应中催化活性体的组成，结构及诱导机理却不...     

A Calcium-Ion-Stabilized Lipase from <Emphasis Type="Italic">Pseudomonas stutzeri</Emphasis> ZS04 and its Application in Resolution of Chiral Aryl Alcohols

An extracellular organic solvent-tolerant lipase-producing bacterium was isolated from oil-contaminated soil samples and was identified taxonomically as Pseudomonas stutzeri, from which the lipase was purified and exhibited maximal activity at temperature of 50 °C and pH of 9.0. Meanwhile, the lipase was stable below or at 30 °C and over an alkaline pH range (7.5–11.0). Ca²⁺ could significantly improve the lipase thermal stability which prompts a promising application in biocatalysis through convenient medium engineering. The lipase demonstrated striking features such as distinct stability to the most tested hydrophilic and hydrophobic solvents (25 %, v/v), and DMSO could activate the lipase dramatically. In the enzyme-catalyzed resolution, lipase ZS04 manifested excellent enantioselective esterification toward the (R)-1-(4-methoxyphenyl)-ethanol (MOPE), a crucial chiral intermediate in pharmaceuticals as well as in other analogs with strict substrate specificity and theoretical highest conversion yield. This strong advantage over other related schemes made lipase ZS04 a promising biocatalyst in organic synthesis and pharmaceutical applications.     

Adaptation of glycolysis and growth to acetate in Sporolactobacillus sp. Y2-8

Exogenous addition of a low concentration of acetate (2 g/L sodium acetate) effectively decreased acetic acid excretion and lowered the ATP content in Sporolactobacillus sp. Y2-8 without any growth defect although the acetate could not be utilized at an initial glucose concentration of 150 g/L. This induced an enhanced glycolytic flux with increased specific activities of hexokinase and phosphofructokinase, probably to compensate for the lowered efficiency of ATP production. However, with increasing concentrations (5 g/L sodium acetate), acetate was utilized first before being produced again, causing a growth lag at the transition. Glucose consumption was also reduced at high acetate concentrations, resulting in decreased D-lactic acid production. These results demonstrate that acetate plays a significant role in regulating glycolysis and growth of Sporolactobacillus.     

H~∞鲁棒滤波在惯导初始对准中的应用

本文给出了惯导系统初始对准的非线性模型 ,针对一般非线性滤波线性化所引起的模型误差 ,提出了 H∞ 鲁棒滤波方法 ,并与卡尔曼滤波器、二次滤波等方法进行了比较。仿真结果表明 ,该方法比二次滤波等方法计算量大大减小 ,精度要高 ;对于非线性模型 ,在存在模型误差或噪声不确定情况时 ,其滤波性能远优于扩展卡尔曼滤波及其它非线性滤波算法     

具有扩散的Brusselator系统的Hopf分支

在齐次Neumann边界条件下,研究了Brusselator系统的Hopf分支问题.证明了当参数满足一定条件时,Brusselator常微分系统的平衡解和周期解是渐近稳定的,而相应的偏微分系统的空间齐次平衡解是不稳定的;如果适当选取参数,那么Brusselator偏微分系统出现Hopf分支.同时,利用中心流形定理证明了Hopf分支解的稳定性.最后给出一些数值模拟的例子以验证和补充理论分析结果.     

Hopf bifurcation and steady-state bifurcation for an autocatalysis reaction–diffusion model

This paper is concerned with an autocatalysis model subject to no-flux boundary conditions. The existence of Hopf bifurcation are firstly obtained. Then by the center manifold theory and the normal form method, the direction of Hopf bifurcation and the stability of spatially homogeneous and inhomogeneous periodic solutions are established. On the other hand, the steady-state bifurcations from simple and double eigenvalues are intensively studied. The techniques of space decomposition and implicit function theorem are adopted to deal with the case of double eigenvalues. Finally, some numerical simulations are shown to verify the analytical results.     

用于乳糖含量测定的新型氨基键合硅胶色谱固定相的制备及评价

基于合成的氨基键合硅胶色谱固定相,按照2015版《中华人民共和国药典》乳糖项下含量测试方法,建立了高效液相色谱-示差折光检测（HPLC-RI）分离乳糖与蔗糖的分析方法。考察了3种不同类型的氨基色谱固定相制备的色谱柱（300 mm×4.6 mm,5 μm）对乳糖和蔗糖的保留时间、分离度和峰面积稳定性等色谱行为的影响。以乙腈-水（70 ∶ 30,v/v）为流动相进行等度洗脱,流速为1.0 mL/min,进样量为10 μL。结果表明：使用异丙基侧链保护的氨基色谱柱时,乳糖和蔗糖的分离度为3.03,实现了二者的良好分离,且各目标物峰形良好;乳糖峰面积的RSD仅为1.14%,小于药典规定的2.0%。该法满足2015版《中华人民共和国药典》方法中乳糖含量测定的要求,适合作为乳糖含量测定的质控色谱柱。     

一些2-氨基-1,3,4-噻二唑类化合物的合成及其对水稻白叶枯病菌活性的研究

为了筛选防治水稻白叶枯病的新药剂,合成了16个2-氨基-5-烷基-1,3,4-噻二唑(Ⅰ)(其中7个是新化合物),11个O,O-二苯基-N-(5-烷基-1,3,4-噻二唑-2-基)磷酰胺(Ⅱ)及4个O,O-二烷基-S-(N-1,3,4-噻二唑)胺基甲基二硫代磷酸酯(Ⅲ)。对水稻白叶枯病原菌和桃冠瘿病原菌进行了离体药效试验,结果表明Ⅰ、Ⅱ类化合物均有活性,且活性的大小与5-位正烷基的碳原子数有关。     

Elevated-temperature ultrahigh-pressure liquid chromatography using very small polybutadiene-coated nonporous zirconia particles

Capillary columns packed with small diameter particles typically lead to low permeability and long separation times in high-performance liquid chromatography. Ultrahigh pressures (>10,000 p.s.i.; 1 p.s.i. is identical with 6,894.76 Pa) can be used to overcome the limitations that small particles impose. Ultrahigh-pressure liquid chromatography (UHPLC) has demonstrated great potential for high-speed and high-efficiency separations. Decreasing the viscosity of the mobile phase by elevating the temperature could additionally reduce the pressure drop and facilitate the use of longer columns or smaller particles to achieve even higher total plate numbers. For this reason, we investigated the use of elevated temperatures in UHPLC. Water-resistant, flexible heater tape covered with insulation was used to provide the desired heat to the column. Polybutadiene-coated 1 microm nonporous zirconia particles were used because of their chemical stability at elevated temperature. A column efficiency as high as 420,000 plates m(-1) was obtained. The effects of temperature and pressure on the separation of parabens were investigated. Separation of five herbicides was completed in 60 s using 26,000 p.s.i. and 90 degrees C.