Biotransformation of l‐menthol by twelve isolates of soil‐borne plant pathogenic fungi (Rhizoctonia solani) and classification of fungi

The microbial transformation of l‐menthol ( 1 ) was investigated by using 12 isolates of soil‐borne plant pathogenic fungi, Rhizoctonia solani (AG‐1‐IA Rs24, Joichi‐2, RRG97‐1; AG‐1‐IB TR22, R147, 110.4; AG‐1‐IC F‐1, F‐4, P‐1; AG‐1‐ID RCP‐1, RCP‐3, and RCP‐7) as a biocatalyst. Rhizoctonia solani F‐1, F‐4 and P‐1 showed 89.7–99.9% yields of converted product from 1 , RCP‐1, RCP‐3, and RCP‐7 26.0–26.9% and the other isolates 0.1–12.0%. In the cases of F‐1, F‐4 and P‐1, substrate 1 was converted to (?)‐(1S,3R,4S,6S)‐6‐hydroxymenthol ( 2 ), (?)‐(1S,3R,4S)‐1‐hydroxymenthol ( 3 ) and (+)‐(1S,3R,4R,6S)‐6,8‐dihydroxymenthol ( 4 ), which was a new compound. Substrate 1 was converted to 2 and/or 3 by RRG97‐1, 110.4, RCP‐1, RCP‐3 and RCP‐7. The structures of the metabolic products were elucidated on the basis of their spectral data. In addition, metabolic pathways of the biotransformation of 1 by Rhizoctonia solani are discussed. Finally, from the main component analysis and the differences in the yields of converted product from 1 , the 12 isolates of Rhizoctonia solani were divided into three groups based on an analysis of the metabolites. Copyright © 2003 Society of Chemical Industry     

GPIB激光自动测径系统及逻辑分析仪的应用

激光测径仪可以对被测的直径进行精确地测量，但被测物所处的环境条件如灰尘、蒸汽等都会影响测量的精确性。本文介绍了一种基于GHB接口的激光测径自动测试系统，用于采集激光测径仪在各种干扰条件下的测量信号，并利用计算机对获得的数据进行处理，从而消除环境对测量结果精确性的影响，另外重点介绍了系统中逻辑分析仪的使用。     

虚拟网立即计费管理系统的实现

随着各运营商之间竞争日趋激烈。为大客户提供方便、快捷．经济的服务是各运营商的首要目标。立即计费（IB）技术的实现．一方面使集团用户能够自主快捷地进行话费核算．电话权限控制．达到内部成本控制目的：另一方面．集团用户能在几乎没有投资成本的情况下实现PBX的功能，同时克服了PBX由于受到中继的约束．通话数量受限的瓶颈。     

有线电视HFC网络技术及其在智能建筑中的应用

文中详细阐述了有线电视HFC网络的传输带宽、系统组成及特点,并对该技术在智能建筑中的应用进行了简要的说明,为智能建筑的设计提供了有益的参考.     

大学英语四、六级网考实施过程中的思考

大学英语四、六级网考在提升考试组织效率、改进考试效度和信度、减少考试作弊等方面有着技术上的优势,是一项很有发展前景的大规模标准化语言水平测试。而考试实施中遇到的高校硬件设施、网考题库建设、考生的畏惧心理等问题制约了网考发展。只有在解决这些问题的基础上,网考才有可能得到更大面积的推广。     

基于数据选择模型的IB算法

针对数据对象自身模式特征明确程度的不同给IB（Information Bottleneck）方法数据分析带来的问题,定义一个“基于明确因素”的数据选择模型,使得IB方法可从数据集中选取模式特征较为明确的数据对象并对其进行模式分析,提出DSIB （Data Selection Information Bottleneck）算法.DSIB算法采用数据压缩过程中所产生的信息损失作为数据对象模式特征是否明确的判定条件,使用“边选择边学习”的顺序“抽取-合并”策略来优化DSIB目标函数.实验结果表明：随着数据选择标准的不断提高,DSIB算法在提高数据分析精度的同时所牺牲的召回率较小;与未做选择的数据分析算法相比,DSIB算法可更好地识别出数据中所固有的内在模式.     

Synthesis and structure-activity relationship of cytotoxic marine cyclodepsipeptide IB-01212 analogues

Several recently discovered marine products have remarkable in vitro and in vivo anticancer profiles against a wide range of tumor cell lines. Some of these compounds are currently in clinical trials. These compounds show complex structures and mechanisms of action of interest. Herein, we describe the preparation of a series of totally synthetic molecules that are structurally related to the natural marine product IB-01212 and evaluated them as antitumor agents. For this, total solid-phase syntheses of the products were performed in parallel by two distinct routes: linear synthesis and convergent synthesis. Structural modifications were introduced in several residue positions to afford 21 IB-01212 analogues for structure-relationship studies. An increase in the number of methyl groups in the macrocycle enhanced cytotoxic activity. Also, the replacement of an ester bond by an amide bond favored antitumor activity against several human cell lines. In addition, the L configuration analogues were more active against all the tumor cell lines than those containing the D configuration. A significant increase in the size and asymmetry of the macrocycle diminished biological activity with respect to that of IB-01212. These results are of great value for the discovery of new and more effective anticancer agents.     

A numerical modeling of the vortex-induced vibration of cascade in turbomachinery using immersed boundary method

Based on the immersed boundary method,a fast simulation for solving unsteady,incompressible,viscous flow associated with the oscillating cascade is established on a quasi-three-dimensional coordinate system.The numerical method is applied to the simulation of the flow passing an oscillating circular cylinder which is forced to move in X direction under prescribed motions in water at rest at low Keulegan-Carpenter numbers.Then vor-tex-induced vibration of a cylinder with two degrees of freedom which oscillat...     

智能建筑IB的系统集成方式

文章介绍了智能建筑的基本要素,论述了智能建筑的系统集成方式,对智能建筑系统内涵构架及可持续发展进行了必要的研讨。     

IB和IIB族金属催化氢胺化反应的研究进展

氢胺化反应是将氮氢键直接加成到碳碳不饱和键上的原子经济性反应，是一种合成胺类化合物的重要路径，在合成含氮化合物方面具有重要意义。本文首先介绍了氢胺化反应的机理，从活化胺类和活化不饱和烃类两个氢胺化反应机理的视角，详细阐述了IB族中的Au、Ag、Cu和IIB族中的Zn 4种金属在氢胺化反应过程中活化底物的方式，并指出了IB和IIB两族金属在氢胺化反应的热催化体系中存在的优缺点，在均相体系中反应温度较低，但操作步骤繁琐，催化剂不能循环利用，而在多相体系中可以实现催化剂的循环利用，但又面临着反应温度高的问题，因此开发温和条件下高效绿色的催化体系显得至关重要。此外，对光催化技术在氢胺化反应中的应用前景进行了展望，而非贵金属利用可见光在温和条件下实现高效催化氢胺化反应是未来的一个重要发展方向。