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111.
Numbers of Lucilia cuprina (Australian sheep blowfly), Chrysomya spp., and Calliphora spp. blowflies caught on sticky traps baited with various synthetic attractants or a standard liver/sodium sulfide attractant in western Queensland were recorded. Numbers of each genus collected were influenced by the composition of the chemical attractants. Attractant mixtures based on 2-mercaptoethanol, indole, butanoic/pentanoic acid, and a sodium sulfide solution gave 5- to 20-fold higher L. cuprina catches than the liver standard. These blends attracted similar numbers of Chrysomya spp. (0.85-2.7x) and fewer Calliphora spp. (0.02-0.2x) compared to the liver standard. These synthetic attractants were more effective and selective for L. cuprina than the standard liver/sodium sulfide attractant, and they can be packaged in controlled-release dispensers to generate constant, prolonged release of the attractant. 相似文献
112.
A homology model of penicillin acylase from Alcaligenes faecalis and in silico evaluation of its selectivity 总被引:1,自引:0,他引:1
Braiuca P Ebert C Fischer L Gardossi L Linda P 《Chembiochem : a European journal of chemical biology》2003,4(7):615-622
A three-dimensional model of the relatively unknown penicillin acylase from Alcaligenes faecalis (PA-AF) was built up by means of homology modeling based on three different crystal structures of penicillin acylase from various sources. An in silico selectivity study was performed to compare this homology model to the structure of the Escherichia coli enzyme (PA-EC) in order to find any selectivity differences between the two enzymes. The program GRID was applied in combination with the principal component analysis technique to identify the regions of the active sites where the PAs potentially engage different interactions with ligands. These differences were further analyzed and confirmed by molecular docking simulations. The PA-AF homology model provided the structural basis for the explanation of the different enantioselectivities of the enzymes previously demonstrated experimentally and reported in the literature. Different substrate selectivities were also predicted for PA-AF compared to PA-EC. Since no crystallographic data are available for PA-AF to date, the three-dimensional homology model represents a useful and efficient tool for fully exploiting this attractive and efficient biocatalyst, particularly in enantioselective acylations of amines. 相似文献
113.
The ability of semiconductor gas sensors to differentiate between gases is essential but difficult to obtain. In this study, Zn2SnO4 was made to be CO selective and the possible mechanism for the selectivity was studied.The electrical and the gas-sensing properties of uncoated and CuO-coated Zn2SnO4 were investigated. In order to obtain an ohmic contact to Zn2SnO4, a ZnO layer was stacked on top of Zn2SnO4 and co-fired. CuO was coated by immersing the sintered sample in Cu-containing solution. Both uncoated and CuO-coated samples showed the higher sensitivity to 200 ppm CO gas than to 200 ppm H2 gas. However, the CuO-coated Zn2SnO4 showed much enhanced sensitivity and thus good selectivity for CO gas (S
CO/S
H
2 6) compared to the uncoated sample. The excellent selectivity of Zn2SnO4-based materials for CO gas was explained by the difference in the mechanisms of CO and H2 oxidation. 相似文献
114.
Electrodes modified by electrodeposition of CoTAA complexes as selective oxygen cathodes in a direct methanol fuel cell 总被引:3,自引:0,他引:3
P. Convert C. Coutanceau P. Crouïgneau F. Gloaguen C. Lamy 《Journal of Applied Electrochemistry》2001,31(9):945-952
The oxygen reduction reaction (ORR) at cobalt tetraazaanulene (CoTAA) modified electrodes was investigated. As a first approach, modified electrodes were prepared by electrodeposition of CoTAA on glassy carbon (GC). The modification of the GC surface was monitored by u.v.–vis. differential reflectance spectroscopy (UVDRS). The recorded spectra (i.e., absorbance as a function of wavelength and time) showed that the electrodeposition of CoTAA at 0.8 V vs Ag|AgCl, that is, at a potential where the TAA ligand is oxidized to TAA+, seems to produce a thin polymer film. Starting from these preliminary results, porous rotating disc electrodes (RDEs) were prepared by electrodeposition of CoTAA (0.8 V vs Ag|AgCl, 1 min) on graphite powder embedded in a recast Nafion® film. The use of a porous RDE allowed comparison of the activity and selectivity of Pt nanoparticles and CoTAA for the ORR under experimental conditions close to those of a fuel cell cathode, that is, at the catalyst|Nafion® interface. The activity towards the ORR of a porous electrode modified by electrodeposition of CoTAA is not affected when methanol is present in the electrolyte phase, whereas a noticeable decrease in the activity of Pt-based oxygen cathodes was observed under the same conditions. Half-cell life tests showed that CoTAA-modified electrodes and Pt-based electrodes have a comparable stability over a period of 90 min. 相似文献
115.
116.
以聚乙烯醇为基材,加入β环糊精作为手性选择剂,加入聚丙烯酸促进离子传递,制得具有手性选择性的阳离子交换膜.通过电渗析过程分离DL-苯甘氨酸.改变原料中D-苯甘氨酸与L-苯甘氨酸的比例,一级电渗析实验结果表明均为D-苯甘氨酸优先通过手性阳膜,分离系数1.05,且基本不随原料组成变化.二级电渗析可以把过程的分离系数提高到1.10左右. 相似文献
117.
纳滤膜对单价和多价离子具有选择分离性能。实验研究了纳滤膜的截留性能随测试溶液的浓度、温度、pH值和操作压力等纳滤操作条件的变化规律。考察了纳滤膜对重金属离子的截留情况,实验表明纳滤膜能够截留大部分重金属离子。 相似文献
118.
119.
铜离子印迹聚合物的制备及吸附性能 总被引:1,自引:0,他引:1
研究了铜金属离子印迹聚合物的制备方法,考察了该印迹聚合物的吸附性能.以铜离子为模板,以4-乙烯基吡啶为功能单体,偶氮二异丁腈为引发剂,乙二醇二甲基丙烯酸酯为交联剂进行聚合,聚合产物用盐酸进行洗脱,得到铜离子印迹聚合物.利用红外光谱仪、差示扫描量热仪等,对铜金属离子印迹聚合物的结构进行表征.采用静态和动态法分析研究铜金属离子印迹聚合物的吸附性能和选择性.结果表明,与非印迹聚合物吸附剂相比,铜离子印迹聚合物对铜离子具有较好的选择性识别能力,吸附选择性系数较高,可望在分离富集领域获得实际应用. 相似文献
120.
主变差动保护范围包括低压侧母线且母线上接小容量隔离变,隔离变高压侧CT不接入主变差动保护,这种接线构成了不完全差动保护,其定值整定方法与完全差动保护不同,且存在选择性的校核问题。本文提出了定值整定的方法和选择性校核的方法;当选择性不能满足要求时,从速动性、灵敏性、选择性角度提出了四种实用的改进方案,并对各种方案的优缺点进行了比较。 相似文献