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     

Bi_4Ge_3O_(12):TR(TR=Pr,Eu,Ce)晶体的吸收和发光光谱

测量了Bi_4Ge_3O_(12)(BGO):Pr、Eu和Ce的吸收、激发和发光光谱。掺杂BGO吸收和激发带相应于pr~(3+)、Eu~(3+)和Ce~(3+)离子特征跃迁。Xe灯中不同波长激发所得到掺杂BGO的发光光谱可通过Bi~(3+)心和掺杂材料之间能量传输过程加以解释。Bi~(3+)心400—600mm发射强度因受到Ce杂质影响变弱,这现象在高Ce浓度晶体里更为显著。     

TR镦锻曲轴的生产

本文简述了TR镦锻装置及其工艺流程、设计程序。主要介绍了TR镦锻曲轴生产中所产生的问题、原因,以及解决办法,有助于我们全面了解TR曲轴生产情况。     

基于Android平台与SMS的智能家居能量管理系统

基于Android平台与SMS技术,设计并实现了智能家居能量管理系统设计方案。在文中描述了该系统的总体设计框图、终端软件设计、智能电表设计、智能插座设计。对该系统进行了验证,实验结果表明,该方案能够快捷地实现对家居设备等能量消耗单元的控制,成本很低,适合入门者使用。     

一种基于工作流图的时间资源分配策略

研究了工作流中时间分配问题。在具体活动基础上增加标记活动，以记录所在路由分支的资源使用情况； 将时间看作一种不可更新资源，并将时间资源分为私有资源、公有资源和双重资源三类； 提出了一种路由结构的时间资源分析方法和分配算法，根据不同路由分支的特点及初始分配资源在实际执行过程中的使用情况，通过裂变与聚合进行时间资源再分配，保证整个工作流的顺利完成。通过实例说明工作流图中时间资源分配过程。     

基于时间反演的天线阵列激励分布确定方法研究

时间反演(TR)是一种新型的电磁波传播与控制方法,具有电磁环境自适应性。采用时间反演方法, 可使结构复杂的天线阵列方向图综合设计简单化。该文初步探索了将时间反演方法应用于微带天线阵列激励设计的可行性,并进行了数值模拟和实验验证。结果表明：对于不同的主波束指向,时间反演法均能准确地确定其对应的激励分布。相对于传统的激励分布确定方法,时间反演法无需互耦补偿计算,准确便捷,且不受阵列和阵元结构形式的限制,在结构复杂阵列的激励分布计算上优势明显。     

多波形超宽带传输参考脉冲无线电系统性能分析

文章中,我们分析了基于多波形的超宽带传输参考脉冲无线电系统的性能。在不考虑帧间干扰和多径干扰的情况下,我们得出了误符号率的闭式解。接着我们又讨论了多波形传输参考系统的抗帧间干扰能力。通过对比仿真结果,我们发现在有帧间干扰的环境中,多波形传输参考系统能够达到比单波形系统更好的误码率性能。     

IDMA下行链路的传输及简化接收方法

针对IDMA下行链路中用户端接收设备复杂度比较高的问题,提出了一种基于时分双工(TDD)模式和时间反转(TR)技术的IDMA下行传输及简化接收方法.该方法通过时分双工获得信道冲激响应,基站发射端利用信道冲激响应的时间反转预处理发射信号.在时间反转及多输入单输出(MISO)技术作用下,利用不同用户信道冲激响应之间的弱相关性以及时间反转处理的空间和时间压缩特性,削弱多用户干扰、共道干扰和符号间干扰.从而使用户接收端只需一个简单的单径接收机即可完成信号的检测,避免了复杂的码片级迭代多用户检测,同时将信道估计器也从用户端转移到基站端,进而使用户端接收设备复杂度大大简化.     

The TR-UWB receiver based on spatial diversity

This paper presents a new Transmitted Reference (TR) Ultra-WideBand (UWB) receiver based on Spatial Diversity (SD), which employs Multi-Antenna Technology (MAT) to improve the performance of TR-UWB receiver. According to the amplitude of correlator output of every antenna branch, this paper analyzed the performances of the proposed TR-UWB receiver employing three different kinds of combina-tion strategies, i.e., Maximum Ratio Combination (MRC), Equal Gain Combination (EGC), and Selective Combination (SC), which are different from conventional ones, and theoretically proved that the performance of EGC is better than MRC. Simulation results verify that when EGC is adopted and BER=10–3, increasing three antennas provides Signal to Noise Ratio (SNR) gain of about 3 dB in CM4 channel and SNR gain of about 2 dB in CM2 channel.     

Influence of polyimide precursor synthesis route and ortho-position functional group on thermally rearranged (TR) polymer properties: Conversion and free volume

Thermal rearrangement of polyimides with ortho-position groups to polybenzoxazoles and related structures has been of recent interest for producing gas separation membranes. This study explores the influence of synthesis route and ortho-position functional group on the thermal rearrangement process and the fractional free volume of thermally rearranged (TR) polymers produced from polyimides derived from 3,3′-dihydroxy-4,4′-diamino-biphenyl and 2,2′-bis-(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (HAB–6FDA). Acetate, propanoate, and pivalate ortho-position functional groups were considered. Thermogravimetric analysis (TGA) was used to study thermal rearrangement at temperatures between 350 and 450 °C, and evolved gases from TGA were analyzed via mass spectrometry to characterize the byproducts of thermal rearrangement and thermal degradation. CO₂ was the major byproduct of thermal rearrangement for all samples, and its evolution began well before the onset of thermal degradation. When non-hydroxyl ortho-position groups were present in the polymers, several byproducts other than CO₂ were also observed due to the loss of these ortho-position groups before thermal rearrangement. Free volume generally increased with increasing extent of thermal rearrangement, but precise values of free volume could not be accurately determined for polymers with propanoate and pivalate ortho-position functional groups due to uncertainties in the chemical structure of partially converted materials. For polymers with acetate and hydroxyl ortho-position groups, free volume could be determined within the uncertainty of density measurements. Thermal rearrangement behavior and free volume results for acetate containing polymers synthesized via different routes were very similar. Based on these results, the chemical structure of the ortho-position functional group has a larger impact on TR polymer properties than the polyimide precursor synthesis route.