Silphinene Sesquiterpenes as Model Insect Antifeedants

Silphinene sesquiterpenes are established chrysomelid antifeedants. In this work, nine silphinene analogs, 11-acetoxy-5-angeloyloxysilphinen-3-one (1), 11-acetoxy-5-tigloyloxysilphinen-3-one (2), 11-acetoxy-5-iso- butyryloxysilphinen-3-one (3), 11-hydroxy-5-angeloyloxysilphinen-3-one (4), 11,5-dihydroxysilphinen-3-one (5), 11,5-diacetoxysilphinen-3-one (6), 5,11-diisobutyryloxysilphinen-3-one (7), silphinen-3,5,11-trione (8), and O-methyl-5-epicantabrenolic acid methyl ester (10), and a presilphiperfolane sesquiterpene (9) were tested against several divergent insect species, including the lepidopteran Spodoptera littoralis, the chrysomelid Leptinotarsa decemlineata, and five aphid species, and their antifeedant effects were compared with those of picrotoxinin, a GABA-antagonist, and thymol, an allosteric modulator for insect GABA receptors. All insects tested responded to at least one silphinene analog and/or GABA antagonist. Compound 3 and thymol were effective antifeedants against all species tested except S. littoralis, with varying potencies according to their feeding ecologies. The toxicity of these compounds was species-dependent and did not correlate with their antifeedant effect.     

二氯苯醚菊酯与甲基对硫磷、毒死蜱和马拉松混用对欧洲玉米螟的增效研究

All 等人(1977)曾分析二氯苯醚菊酯与选择的有机磷和氨基甲酸酯杀虫剂对玉米穗虫(Heliothis zea)及烟芽夜蛾(H.Virescens)幼虫的协同作用。在对这两种虫的实验室和田间试验结果中,发现二氯苯醚菊酯加上甲基对硫磷或灭多虫具有增效作用。在某些情况下,包括二氯苯醚菊酯的二元混合物防治这两种害虫的药量可以降至单用量的10％。他们没有阐明增效作用的机制。     

黄色物质在含铜介质中的解毒作用

可溶性黄色有机物(黄色物质)普遍存在于含有水的环境里,它通过影响含水有机体中矿物质的输送和转化,以及对机体本身物质发生的作用,而影响到生态环境。对这种黄色物质虽然已经作了很多研究,但在化学上和物理上还是不清楚的。一般认为在自然水中游离的黄色微小颗粒,是来自腐败了的有机质,是一种水溶性的抽提物。木质素是植物体的基本组成物,是一类稳定的、黄褐色的腐败中间产物腐植质或腐植酸物质的前体(?)。腐植酸物质分为腐植酸(碱可溶的)和黄腐酸(酸可溶的)两部份。这些化合物在水中不溶解,而且当从土壤或沉积物中抽提出来时又特别容易被分解。黄色腐败产物中的黄色物质,常称它为可溶性腐植质(可溶性腐植酸)从有些数据如元素组成、可见     

低能耗合成氨生产的联合能量回收系统

采用氨生产能量回收系统的现有装置,可以使每吨氨的能耗从8.4×10~6千卡降为7.0×10~6千卡。     

碳纤维与复合材料的回顾(第一部分)

在论文将分为两部分,目的是要回顾碳纤维及其原丝的生产技术、纤维结构及其主要性能(第一部分).并总结目前树脂基或水泥基碳纤维复合材料的现状(第二部分)。     

排气減压设计原理 对消除单基药自动化生产线爆炸事故的应用

试验研究确定了发射药贮药漏斗适合于排出燃烧反应的气体,因而消除在单基药自动化生产线空气干燥过程中的爆炸反应。用450磅品号MISP f/105mm的发射药,在特别设计的,安装有减压排气装置的药斗中,进行大型试验,从漏斗底部点火时,火药的燃烧不会转变为爆炸。实现这种药斗设计方案,在单基药自动化生产线的后工序中,可将估计的7级爆炸事故减小到2级燃烧事故。采用本试验研究中所确定的发射药表面积与药斗排气口面积之比,就可提供基本的安全设计数据,能在单基发射药生产设备中避免由于火焰所引起的爆炸反应。     

侧流塔的最小回流比

蒸馏塔的设计需要估算最小回流比。本文指出如何计算有一股或多股侧流的蒸馏塔最小回流比。     

杀螟硫磷原药和制剂气相色谱测定法的协作研究

世界卫生组织(WHO)于1973年首次把杀螟硫磷(fenitrothion)编入农药规格手册。有效成份的分析采用滴定法,该法基于杀螟硫磷在酸性溶液中被锌还原,然后用亚硝酸钠滴定还原产物胺。方法包括原药及其可湿性粉剂的测定。这一方法并不是专一的而且费时。在WHO杀虫剂化学与规格专家委员会1977年会议上,J.W.Miles和D.L.Mount     

Interactions between immunoglobulin-like and catalytic modules in Clostridium thermocellum cellulosomal cellobiohydrolase CbhA

Cellobiohydrolase CbhA from Clostridium thermocellum cellulosome is a multi-modular protein composed starting from the N-terminus of a carbohydrate-binding module (CBM) of family 4, an immunoglobulin(Ig)-like module, a catalytic module of family 9 glycoside hydrolases (GH9), X1(1) and X1(2) modules, a CBM of family 3 and a dockerin module. Deletion of the Ig-like module from the Ig-GH9 construct results in complete inactivation of the GH9 module. The crystal structure of the Ig-GH9 module pair reveals the existence of an extensive module interface composed of over 40 amino acid residues of both modules and maintained through a large number of hydrophilic and hydrophobic interactions. To investigate the importance of these interactions between the two modules, we compared the secondary and tertiary structures and thermostabilities of the individual Ig-like and GH9 modules and the Ig-GH9 module pair using both circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC). Thr230, Asp262 and Asp264 of the Ig-like module are located in the module interface of the Ig-GH9 module pair and are suggested to be important in 'communication' between the modules. These residues were mutated to alanyl residues. The structure, stability and catalytic properties of the native Ig-GH9 and its D264A and T230A/D262A mutants were compared. The results indicate that despite being able to fold relatively independently, the Ig-like and GH9 modules interact and these interactions affect the final fold and stability of each module. Mutations of one or two amino acid residues lead to destabilization and change of the mechanism of thermal unfolding of the polypeptides. The enzymatic properties of native Ig-GH9, D264A and T230A/D262A mutants are similar. The results indicate that inactivation of the GH9 module occurs as a result of multiple structural disturbances finally affecting the topology of the catalytic center.     

橡胶添加剂苯并呋咱-1-氧化物

普遍称为Ｂｅｎｚｏｆｕｒｏｘａｎ（ＢＦＯ）的苯并呋咱－１－氧化物已证明能降低填充炭黑的硫化胶的滞后损失３０％以上。ＢＦＯ大概能促进弹性体和炭黑之间的键合，导致硫化胶“佩恩效应”降低。ＢＦＯ在母炼胶混炼期间于不同温度下加入。为了最大限度地降低滞后损失，需要高温混炼，而且采用高比表面积的炭黑会更有效。镍盐会改善ＢＦＯ和弹性体／炭黑间的反应。