纳米Fe3O4含量对微生物燃料电池性能的影响

以不锈钢网为集流体,采用辊压工艺制备了Fe3O4质量分数分别为0%、2.5%、5.0%和7.5%的不锈钢网、活性炭粉和Fe3O4构成的复合阳极AcM、AcFeM1、AcFeM2和AcFeM3,研究了Fe3O4含量对单室无膜空气阴极微生物燃料电池(MFC)产电性能的影响,并通过塔菲尔曲线和阳极充电-放电测试研究了不同Fe3O4含量的阳极的电化学行为。结果表明,阳极Fe3O4质量分数由0%增加至2.5%、5.0%时,MFCs的最大输出功率和净电容电荷由AcM阳极的664 mW/m2和293.9 C分别上升至AcFeM1、AcFeM2电极的731 mW/m2和300.4 C、809 mW/m2和388.5 C,当Fe3O4含量继续增加至7.5%时,MFCs的产电效率和净电容电荷均减小,Fe3O4质量分数在5.0%时,MFCs性能最佳;电化学测试进一步说明Fe3O4质量分数在5.0%时,MFCs阳极的动力学活性最好。     

Thermal denaturation of ribonuclease T1 a DSC study

The thermal denaturation of microbial Ribonuclease T1 (RNAase T1) as a function ofpH, was studied by means of DSC microcalorimetry. The midpoint denaturation temperatures, enthalpy changes and heat capacity changes of Ribonuclease T1 were compared with those obtained for pancreatic Ribonuclease A (RNAase A). It was found that the microbial T1 protein undergoes a more complex conformational transition than the simple two-state transition shown by Ribonuclease A. The hypothesis of the presence of a molten globule form is discussed. The conformational stability of RNAase T1 is lower than that of RNAase A at highpH values. Indeed, the maximum stability of RNAase T1 occurs atpH 5, whereas that of RNAase A occurs atpH 8. AtpH=3.7 an irreversible aggregation phenomenon was indicated by the existence of a reproducible exothermic peak. The conformational transition of RNAase T1 is reversible in the range ofpH 4.5–7.0, whereas it becomes irreversible atpH8.0 as for RNAase A.This work was financed by the National Research Council (C.N.R.-Rome) and by Ministry of University and Scientific and Technological Research.     

New Synthetic Approaches to Substituted Pyridine-2-(1H)-ones Clubbed with Substituted Aryl Diazo Substituents

6-Triazolylpyridone derivatives were synthesized by coupling 4-(4-methoxyphenyl)-6-(1H-1,2,4-triazol-1-yl)-1-(3-chlorophenyl)pyridin-2(1H)-one with substituted benzenediazonium chlorides in the form of two isomers, which were separated by column chromatography and characterized by ¹H and ¹³C NMR. Following the green approach, solvents were avoided as much as possible. The reaction monitoring was carried out by gas chromatography as well as thin-layer chromatography. The scope and limitation of the method are discussed. The structures of all the compounds have been assigned unambiguously on the basis of elemental analysis, infrared, and NMR spectral data and have been evaluated for antimicrobial and antitubercular activities.     

焦测序技术及其在遗传分析中的应用

焦测序技术是一种新的实时DNA测序技术。它在DNA聚合酶、三磷酸腺苷硫酸化酶、荧光素酶和三磷酸腺苷双磷酸酶4种酶的协同作用下,使引物延伸聚合脱氧核糖核酸(dNTP)释放焦磷酸盐(PP i)、PP i转换三磷酸腺苷(ATP)、ATP产生荧光信号与dNTP和ATP的降解等化学反应偶联起来,检测结果准确可靠。本文综述了焦测序技术的基本原理、操作步骤和它在单核苷酸多态性(SNP)研究、微生物的分型鉴定和基因甲基化检测等遗传分析中的应用,并对焦测序技术的发展作了展望。     

Zn2+对土壤微生物碳、呼吸强度的影响

Zn是典型的人类活动源元素之一，工业化进程加剧了Zn对农田生态系统污染的威胁犤１犦。最初，重金属是否污染判断标准采用X＋２S（X为该元素背景值，S为标准偏差）犤２犦，国际通用土壤质量标准界定之后，将生物量下降６０％作为重金属元素的临界浓度犤３犦。一些研究表明，Cu、Pb、Cd、Hg等进入土壤之后，微生物群落多样性发生改变犤４犦，导致微生物生物量和呼吸速率降低或显著增加犤５犦，酶的活性受严重损害犤６犦，微生物生态参数Cmic／Corg降低，代谢熵qCO２则明显升高犤７犦。对Zn２＋的研究侧重于生物毒理作用犤８犦，Zn２＋…     

Novel aromatics bearing 4-O-methylglucose unit isolated from the oriental crude drug Bombyx Batryticatus

Oriental crude drug, Bombyx Batryticatus, is dried silkworm larva, Bombyx mori L., which are dead and stiffened due to a Beauveria bassiana infection. In traditional Japanese, Korean, and Chinese medicine, it is employed as analgesic and anticonvulsant. We investigated the constituents of Bombyx Batryticatus and isolated four novel aromatics bearing 4-O-methylglucose moiety, BB-1, 2, 3, and 4 (1-4). It is speculated that these compounds are produced by an interaction between plants, insects, and microorganisms.     

基于广义回归神经网络的微生物降解效应对助燃剂检测的影响

为探究火场土壤载体中微生物降解效应对助燃剂鉴定的影响，在普通土和培养土两种土样上注射助燃剂，以密封存放时间为变量，通过静态顶空的样品预处理方式对样品内的助燃剂残留物进行气相色谱-质谱法（GC-MS）鉴定。研究发现，微生物降解效应会改变样品内助燃剂组分，不同土样内降解结果有所不同，普通土样的降解效应较培养土样明显，C9~C12直链烷烃和单取代芳香烃更易被降解，多取代芳烃的降解难度随取代基含量的增多而增加。按土样种类采用主成分分析（PCA）的方式进行数据降维后，采用广义回归神经网络（GRNN）对不同土样结果区分，准确率达100%。     

Multivariate curve resolution of mixed bacterial DNA sequence spectra: identification and quantification of bacteria in undefined mixture samples

A comprehensive understanding of factors that influence microbial competition and cooperation, their diversity and processes will be greatly beneficial in many research areas. Current tools for microflora determinations are far from suitable for high‐throughput monitoring of development in complex microbial communities. Here, we describe the application of a calibration free method, multivariate curve resolution with alternating least squares (MCR‐ALS), for identification and quantification of different microbes in mixture samples. The idea is to utilize MCR‐ALS to enable close monitoring of ecology in a variety of microbial communities. The data from two designed experiments consisting of DNA sequence spectra measured on mixtures were analysed with MCR‐ALS using no prior information on the data except for appropriate constraints, such as non‐negativity and closure. The results were compared both to the known true concentrations as well as to the results obtained from the well‐established multivariate calibration method partial least squares (PLS) regression. MCR‐ALS performed as well as PLS regression, successfully extracting all pure bacterial spectra and quantitative information on these, with 97.81% and 97.91% explained variance for the first and the second data set, respectively. Copyright © 2008 John Wiley & Sons, Ltd.