微量元素对ZL107力学性能的影响

应用正交试验法来设计ZL107中Zn、Ti、Cd、Sb等元素的含量并制作试样,根据铝合金试样力学性能的测试结果,分析确定较佳的合金成分配比方案.得到的力学性能最好的一组试样的抗拉强度为356.1 MPa,伸长率为3.02%,分别比经T5处理的ZL107铸锭提高了46%和52%.     

Oxidative activities of heterologously expressed CYP107B1 and CYP105D1 in whole-cell biotransformation using Streptomyces lividans TK24

Cytochrome P450 enzymes are a major class of biocatalysts related to the oxidative metabolism of many drugs, assisted by electron transfer partners. The functional expression of the P450 gene in a heterologous host will lead to efficient biotransformation and biodegradation, which are useful in pharmaceutical improvement or environmental cleanup. The soluble cytochrome P450 monooxygenase systems CYP105D1 and CYP107B1 involved in the biotransformation of some xenobiotics, such as secondary metabolites or environmental pollutants, were expressed in Streptomyces lividans TK24 with the Streptomyces expression vector pIJ6021. In whole-cell biotransformation assay using these recombinant strains, the oxidative dealkylation of 7-ethoxycoumarin was detected without any foreign redox partners in the case of CYP107B1, while the activity of CYP105D1 was not monitored until this gene was coexpressed with the ferredoxin gene located downstream of the CYP105D1 gene, and the ferredoxin reductase gene SCF 15.02 from Streptomyces coelicolor A3(II). This result suggests that CYP107B1 is capable of utilizing an endogenous electron transfer partner from the host but not CYP105D1, and that CYP105D1 is complemented by some redox partner imported from closely related strains.     

基于STM32F107的高速以太网接口设计与应用

采用32位微处理器STM32F107和网络接口芯片DP83848实现以太网接口的设计方法,硬件少、易于实现、使用方便,适合现在的网络传输系统.通过对系统的硬件结构及接口电路的介绍,阐明了系统的硬件实现;通过对驱动程序及测试方法的详细分析,明确系统的通信流程.通过测试,该设计能够进行信息的高速、远程传输,完成以太网接入功...     

硅橡胶分子量对硅泡沫性能影响的研究

选用4种不同分子量的液体硅橡胶(107硅橡胶)作为生胶制备出了室温下固化的硅橡胶泡沫材料.探讨了生胶胶料黏度对固化速度的影响,以及分子量大小对硅泡沫的泡孔形貌、物理力学性能、热稳定性的影响.随着基础胶料黏度的增大,凝胶时间及其表干时间缩短,即固化速度加快;随着生胶分子量的增大,硅泡沫的泡孔变小,拉伸强度、压缩模量逐渐增...     

基于WRC297公报方法对接管外载荷作用下局部应力的计算和分析

WRC 297公报方法是压力容器设计中关于接管外载荷作用下局部应力计算常用的一种方法。分析了WRC 297公报在使用过程中的局限性,并通过具体的计算案例,分别对不同结构模式的接管在外载荷作用下的局部应力进行计算、分析和探讨。     

Chemical profile, functional and antioxidant properties of tomato peel fiber

Tomato processing residue is defined as a secondary raw material that can increase its value, being considered a potential source of dietary fiber and bioactive compounds. Commercial tomato peel fiber has been analyzed to ascertain the proximate and nutritional composition (moisture, fat, protein, dietary fiber, ash, and minerals), the fractions (insoluble, IDF, and soluble, and SDF) and sugar composition of dietary fiber, functional properties (water retention capacity, WRC, swelling capacity, SWC, fat absorption capacity, FAC, glucose diffusion retardation index, GDRI, and osmotic pressure), total antioxidant activity (AA), and the content of antioxidant bioactive compounds (phenolic compounds and lycopene). To extract phenolic compounds and dietary fiber, three methods were assayed in this study: enzyme hydrolysis, maceration, and ultrasonic assistance. The content of TDF was 84.16%, and the major fraction was the IDF (71.82%), formed mainly by hemicelluloses. Tomato peel fiber retained 6.76 g of water/g as WRC, and it was significantly correlated with the IDF content. In addition, the content of IDF determined the low FAC and SWC and the GDRI at 60 min (39.22%). The main phenolic compound was rutin, followed by naringenin, rutin derivatives, and chlorogenic acid derivatives. These were better extracted using ultrasonic assistance, whereas lycopene showed mean values between 3 and 4 mg/100 g. The AA of tomato peel fiber was low, since the phenolic compounds are mainly bound to the cell wall of plant, showing a low capacity for scavenging radicals. Due to its chemical profile and functional properties, tomato peel fiber can be used as a food supplement, improving the different physical, chemical, and nutritional properties of foods. However the color and flavor of this product must be considered in its applications to avoid a negative effect on the sensory characteristic of the foods to which it is added.     

IEEE1588协议在合并单元中的应用与实现

数字化变电站尤其是过程层设备对同步精度要求越来越高,文中提出应用对时精度达到亚微秒级的IEEE1588协议,实现合并单元的同步功能向12路电子式电压电流互感器发送同步采样命令,为实现IEC61850T5等级的对时精度提供了很好的技术支持。简要阐述了IEEE1588时钟同步系统的工作原理和时间戳标记的具体设计方法,给出了运用ARM系列STM32F107在过程层合并单元实现IEEE1588协议的过程,并对该方案进行了性能测试,验证了运用STM32F107能够实现IEEE1588网络协议的高精度对时,满足变电站过程层对时钟同步精度的需求。     

基于CS5484的电力参数测量装置设计

分析了电能测量芯片CS5484的电路结构和工作原理,并设计开发了一种基于CS5484的电力参数测量装置,重点分析了电压通道和电流通道的电路组成。系统采用集成以太网控制器的微处理器STM32F107为控制芯片,可以满足复杂的控制输出和联网测量的需求。采用标准交流信号源对装置进行了测试,结果表明该装置对电压测量误差均在0.2%以下,无功功率的测量误差均在0.4%以下,可以较好满足电力参数的测量要求。     

STM32微控制器的可靠串口通信技术研究

在工业控制应用中,串口是微控制器系统必不可少的接口之一,但是串口在应用过程中容易出现误码现象,需要对接收的数据进行校验才能保证通信的可靠性。本文提出一种基于STM32F107的可靠串口通信设计方案,STM32F107提供5个独立的异步串行接口,并且内置了CRC计算单元,实践表明具有较好的性能。