Yeast mutants with increased bacterial transposon Tn5 excision

Five complementing recessive mutations that exhibit increased bacterial transposon Tn5 precise excision in yeast Saccharomyces cerevisiae were obtained by ethylmethanesulfonate treatment. One of these mutations (tex1) was submitted to extensive genetic analysis. tex1 is a recessive temperature-sensitive mutation resulting in a 20-100-fold increase in Tn5 excision. It also has increased frequencies of ochre mutation reversion, of forward mutation to canavanine resistance, and loss of chromosome III or its right arm. The possible mechanism of tex1 effects is discussed.     

锆(Ⅳ)-3,5-diBr-PADAP-安替比林三元配合物的分光光度研究与应用

本文提出在安替比林存在下,以3,5-diBr-PADAP为显色剂,分光光度测定微量锆的新方法。在pH1～2的HCl介质中,锆(W)与试剂和安替比林形成配合比为1:1:1的红色三元配合物,最大吸收值在615nm波长处,摩尔吸光系数ε=1.35×10~5。锆(Ⅳ)量在0～25μg/25ml范围内,遵守比尔定律。方法简单、快速、准确。若采用钽试剂—苯萃取法分离共存离子,可适用于钽铌矿和合金中痕量锆的测定。     

4-氨基-3-肼基-5-巯基-1,2,4-三唑的合成及其对醛的检验

以硫脲和水合肼合成了可用于检验醛的试剂——4-氨基-3-肼基-5-巯基-1，2，4-三唑(别名：紫醛)，其结构通过红外光谱、核磁进行了确定。试验表明，紫醛对醛的检验敏感、专一、快速、操作简单。     

Application of artificial neural networks to the analysis of two‐dimensional fluorescence spectra in recombinant E coli fermentation processes

A two‐dimensional (2D) spectrofluorometer was used to monitor various fermentation processes with recombinant E coli for the production of 5‐aminolevulinic acid (ALA). The whole fluorescence spectral data obtained during a process were analyzed using artificial neural networks, ie self‐organizing map (SOM) and feedforward backpropagation neural network (BPNN). The SOM‐based classification of the whole spectral data has made it possible to qualitatively associate some process parameters with the normalized weights and variances, and to select some useful combinations of excitation and emission wavelengths. Based on the classified fluorescence spectra a supervised BPNN algorithm was used to predict some of the process parameters. It was also shown that the BPNN models could elucidate some sections of the process's performance, eg forecasting the process's performance. Copyright © 2005 Society of Chemical Industry     

Kinetics study of Ti[O(CH2)4OCHCH2]4 initiated ring‐opening polymerization of ε‐caprolactone by differential scanning calorimetry

Chemical shrinkage was used for the in situ measurement of the progressing chemical stabilization reactions and the influence of ozone during the stabilization of polyacrylonitrile. A method for evaluating the activation energy through the sensitivity temperature is presented. The calculated results show that the activation energies were 161.57 kJ/mol in air and 181.23 kJ/mol in ozone-enriched air. Therefore, the chemical reactions were postponed during stabilization in ozone-enriched air. Ozone seemed to act in three ways: first, ozone promoted the formation of the serious skin–core structure. Second, ozone accelerated the chemical reactions and shortened the stabilization time at lower heating rates. Third, ozone postponed the chemical reactions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

OPC技术在过程控制中的应用

在简要介绍OPC技术原理的基础上,对OPC技术在罗克韦尔PLC5系列PLC及其相关软件与VB程序通信中的应用进行了研究,并通过实例说明了OPC服务器的配置方式及OPC客户端程序的实现方法。     

新试剂SPAQ与铜的显色反应研究及应用

本文研究了新试剂5-(4-磺酸钠苯偶氮)-8-氨基喹啉(SPAQ)与铜的显色反应及其最佳条件.在CTMAB存在下,于pH9.5的硼砂介质中,SPAQ与铜形成2:1的紫红色配合物,其最大吸收峰位于584.6nm,摩尔吸光系数为7.8×10~4.铜量在0～20μg/25ml范围内符合比尔定律.方法灵敏、快速,不需萃取分离,可用于粗铅、粗锌及锌合金中的微量铜的测定,结果满意.     

激光诱导H_2S催化裂解制备H_2的研究

在室温常压静态条件下研究了以Ｖ２Ｏ５／ＴｉＯ２为催化剂，紫外脉冲激光诱导Ｈ２Ｓ催化分解为Ｈ２和Ｓ的反应及其机理。考察了产氢量与激光不同照射条件之间的关系。     

Structural modelling of coprecipitated VTiO catalysts

A statistical study of the particle shape and size of pure V₂O₅ and TiO₂, and samples of coprecipitated V₂O₅---TiO₂ catalysts with different V/Ti ratios, has been performed. They were also characterized by XRD, EDAX, SEM and XPS. The results showed that pure vanadium pentoxide is compose by large square or needle-shaped particles, while pure titanium dioxide has small and rounded ones. VTiO samples presented an area and shape, depending on the V/Ti ratio.

These results and the spectroscopical characterization conducted to a particle model of the catalysts. Those VOTi samples with high V/Ti ratio would have large V₂O₅ crystals acting as support of a V/TiO₂ solid solution. In contrast, those samples with a low V/Ti ratio, would have the solid solution supporting vanadium pentoxide crystals.     

ZSM-5型沸石催化剂的结焦与失活

本文对ZSM-5型沸石催化剂结焦与失活的关系进行了系统的评述.探讨了ZSM-5沸石的酸度和微孔结构对结焦过程的影响.