从7-ADCA生产过程中环境友好的回收苯乙酸

采用新工艺回收7-氨基-3-脱乙酰氧基头孢烷酸(7-ADCA)生产中产生的苯乙酸,并对苯乙酸回收过程中产生的废硫酸进行处理。采用硫酸(9 8%)洗涤二氯甲烷,硫酸与二氯甲烷适宜的体积比为1∶50,洗涤好的二氯甲烷中含苯乙酸4%。蒸馏出二氯甲烷,趁热向熔融苯乙酸中加入母液,降温析出苯乙酸。晾干的苯乙酸为白色鳞片状,含量大于99%,苯乙酸母液补充部分清水套用到下一批析出苯乙酸。废浓硫酸用芬顿试剂氧化,控制80℃氧化4h,双氧水和七水硫酸亚铁重量比为6∶1,废浓硫酸COD下降85%以上。氧化结束后向废硫酸中加入铁粉和双氧水,制得聚合硫酸铁。     

Evolution on neutral networks accelerates the ticking rate of the molecular clock

Large sets of genotypes give rise to the same phenotype, because phenotypic expression is highly redundant. Accordingly, a population can accept mutations without altering its phenotype, as long as the genotype mutates into another one on the same set. By linking every pair of genotypes that are mutually accessible through mutation, genotypes organize themselves into neutral networks (NNs). These networks are known to be heterogeneous and assortative, and these properties affect the evolutionary dynamics of the population. By studying the dynamics of populations on NNs with arbitrary topology, we analyse the effect of assortativity, of NN (phenotype) fitness and of network size. We find that the probability that the population leaves the network is smaller the longer the time spent on it. This progressive ‘phenotypic entrapment’ entails a systematic increase in the overdispersion of the process with time and an acceleration in the fixation rate of neutral mutations. We also quantify the variation of these effects with the size of the phenotype and with its fitness relative to that of neighbouring alternatives.     

Microbial Fuel Cell Application for Azoic Dye Decolorization with Simultaneous Bioenergy Production Using Stenotrophomonas sp.

A single‐chamber air‐cathode microbial fuel cell (MFC) was successfully applied for decolorization of the diazoic dye Reactive Black 5 (RB5) with simultaneous production of electricity. An innovative low‐cost medium, the marine water‐glucose‐yeast extract medium (MWGY), was developed which appears as a textile marine effluent in terms of salinity. The anode compartment containing a single bacterial strain of Stenotrophomonas sp. showed almost complete dye decolorization with different RB5 concentrations after seven days of treatment. For the four dye concentrations used, a correlation between dye removal and production of electrical energy was found. The comparison of the decolorization process in the MFC with that in a batch reactor as control experiment highlights the efficiency of the single‐chamber air‐cathode MFC technology which improved the dye removal by the same bacterial strain.     

Controllability Analysis of Process Alternatives for Biobutanol Purification

Biobutanol has characteristics similar to petroleum fuel and is considered as a superior biofuel compared to ethanol. The development of technologies for biobutanol production by fermentation has resulted in higher final biobutanol concentrations together with less energy‐intensive separation and purification techniques. These new technological developments have the potential to provide a production process for biobutanol that is economically viable in comparison to the petrochemical pathway for its production. The control properties of four different possible process designs for biobutanol purification are analyzed. The results, using the singular value decomposition technique, indicated that the scheme where only biobutanol flow is purified, and both ethanol and acetone leaving the purification process mixed with water and biobutanol traces, showed the best control properties.     

铁路反恐视频监控系统方案探究

本文通过分析反恐视频监控的需求，研究了普通红外线摄像机和激光摄像机的性能、铁路通信传输网通道容量和视频占用的资源量，推荐反恐视频监控方案采用数字激光摄像机。     

一种矿用二氧化氮传感器的检测方法

矿用二氧化氮传感器是煤矿常用的气体检测仪表，针对煤矿需求开发的矿用二氧化氮传感器，需要满足煤矿矿用产品要求。文章提出一种矿用二氧化氮传感器检测方法，说明矿用二氧化氮传感器需要满足的技术参数，供实验室检测人员借鉴，也为设计制造矿用二氧化氮传感器提供了参考。