Chirality and Crop Protection

The modern agrochemical industry is searching, more intensively than ever, for new substances to combat pests (weeds, deleterious insects, plant pathogens, etc.). In the complex and costly selection and optimization process, state-of-the-art scientific methods are always needed. The aims of the interdisciplinary optimization are mainly the reduction of the rate of application of the new substance, an increase in the selectivity against the target organism, and the optimal ecological profile. If a promising crop protection compound is a racemate or a diastereoisomeric mixture, the chemist has a unique opportunity to contribute to this optimization process through the synthesis of enantiomerically pure isomers for testing purposes. If the single isomer proves to be biologically superior to the racemate, the development of an economical and ecologically sound process for the production of the single isomer presents an even greater challenge. The average price of a crop protection compound is much lower than that for a pharmaceutical product, and this fact imposes a severe limitation upon the flexibility of the chemist who is concerned with the synthesis and production of a stereochemically pure agrochemical. This forces the crop protection chemist to make full use of both his scientific and creative capabilities. Fortunately, parallel to the development of the above optimization aims of a modern and ecologically sound crop protection research, there has been a continuous and worldwide advance in the area of asymmetric synthesis. Due to the interplay of these two parallel efforts there has been a great accumulation of chemical, biological, and agronomical knowledge in recent years, which should have implications beyond merely the synthesis of enantiomerically pure agrochemicals.     

Organotin compounds in agriculture since 1980. Part I. Fungicidal,bactericidal and herbicidal properties

The object of this review paper is to provide a guide to agrochemical research involving organotin compounds which has been performed since 1980. The information is presented in tabular form and Part I is divided into main sections as indicated by the title. Each section is then subdivided to cover the various commercial organotin compounds. A final subsection lists investigations involving novel compounds. A table of the contents has been provided to enable ease of reference.     

Synthesis, Crystal Structure and Biological Activity of Novel Dichloroacetyl Oxazolidine Herbicide Safeners

A series of novel N-dichloroacetyl oxazolidine herbicide safeners was synthesized and characterized by IR, 1H NMR, 13C NMR, elemental analysis and X-ray diffraction. The preliminary biological test shows that the compounds could protect maize against injury caused by chlorsulfuron to a certain extent.     

有机磷农药生物电化学传感器的研究进展

为了监测有机磷农药给人类及整个生态环境所造成了的危害和影响，本文综述了最近几十年来电化学生物传感器技术在有机磷农药（OPs)检测领域的研究进展。     

化学农药的现代化发展历程

介绍了现代化学农药从天然农药经人工合成有机农药向着“超高效、无毒、无污染”的绿色化学农药方向发展所历经的3个主要发展阶段,探讨了这3个主要发展阶段中代表性农药的性质及其特点。     

农药的危害与微生物农药的开发

农药与人类的健康和农业生态平衡的被破坏有密切关系，人们往往把“农药”视为“毒药”。本文介绍常用农药对人类的健康和环境造成的危害；大力开发和使用微生物农药，逐步消除农药产生的公害问题，并纠正人们对农药的片面认识。     

The Concept of P--H Protection Extended to Phosphine Oxides: Preparation of Functional,Unsymmetrical Secondary and Tertiary Phosphine Oxides

Phosphine oxide analogues of Triazole fungicides and protected Threonine have been prepared. The enzymatic hydrolysis of phosphine oxide di-acetates has been investigated.     

A Facile,Sensitive and Rapid Sensing Platform Based on CoZnO for Detection of Fipronil; an Environmental Toxin

A sensitive detection of extremely toxic phenylpyrazole insecticide, ‘Fipronil’ is presented. Currently, the advancement of approaches for the detection of insecticides at low concentrations with less time is important for environmental safety assurance. Considering this fact, an effort has been made to develop an electrospun CoZnO nanofiber (NF) based label‐free electrochemical system for the detection of fipronil. The CoZnO NF were characterized using different techniques including field emission scanning electron microscopy (FE‐SEM), Energy Dispersive X‐Ray Analysis (EDX), X‐ray diffraction (XRD), Fourier‐transform infrared spectroscopy (FTIR), and Raman Spectroscopy. Based on the experimental results, the proposed platform displayed a linear response for fipronil in the attogram/mL range despite the multiple interfering agents. The sensitivity of the device was found to be 3.99 KΩ (g/ml)^?1 cm^?2. Limit of detection (LOD) and limit of quantification (LOQ) were calculated and found to be 112 ag mL^?1 and 340 ag mL^?1 respectively. Further, this proposed sensor will be implemented in the fields for the rapid and proficient detection of the real samples.     

The Photocatalytic Degradation of Imazapyr

Summary. The degradation of imazapyr, an imidazolinone herbicide, in aqueous solution has been investigated with TiO₂ slurry as photocatalyst at 30°C under UV radiation. The depletion of imazapyr concentration in an aqueous suspension followed 1^st order kinetic behavior. The influence of pH and the charge densities of imazapyr geometries were calculated at the semi-empirical AM1 level, and the effect of temperature was investigated. The addition of electron acceptors such as potassium persulfate and hydrogen peroxide showed that the rate constant doubled at least. At higher persulfate concentrations the herbicide degradation was more efficient in direct photolysis than TiO₂-photocatalysis. The degradation rate constant increased by 38% upon variation of the temperature between 20.0 and 50.0°C and displayed non-Arrhenius behavior.     

3-Phenylpropylamines,A New Class of Systemic Fungicides

The biological activity of 3-phenylpropylamines is not exclusively determined by their structure. It could be demonstrated that the fungicidal activity of partially hydrogenated compounds of this class of substances is also substantially influenced by the conformation. An optimization of the conformational criteria—illustrated by many examples, yet constituting only a small number of those actually examined—afforded compounds with excellent properties, e.g. N-[3-(4-tert-butyl-1-cyclohexenyl)-2-methylpropyl]-cis-2, 6-dimethylmorpholine.     

小分子荧光探针在绿色农药开发中的应用

小分子荧光探针以其灵敏度高、特异性强、稳定性好、操作便捷和成本低等特点在生命科学、医药化学和环境科学等领域得到了广泛的应用.在农药化学领域,小分子荧光探针常被用作农药残留及重金属污染的检测手段.近年来随着全球开发绿色农药战略需求的不断增强,作为靶向型药物设计和高通量筛选的重要分子工具,荧光探针在绿色农药新产品研发领域的...     

Analytical prospect of compact disk technology in immunosensing

A sensitive and versatile methodology involving recordable compact disks as molecular screening surfaces and a standard optical CD/DVD drive as detector, is reported. Quantitative immunoanalysis, in microarray format, of a cancer marker (alpha-fetoprotein, AFP) and a selective herbicide (atrazine) on four types of audio-video disc was conducted. Enzyme or gold nanoparticle-labeled antibodies were used as tracers, forming a precipitate on the sensing disk surface. The principle of disk reading is based on capture of analog signals with the disk drive that were proportional to the darkness of the immunoreaction product. Detection limits for AFP (8.0 μg L⁻¹) and for atrazine (0.04 μg L⁻¹) were under the threshold needed to detect nonseminomatous testicular cancer, and below the maximum E.U. residue limit for drinking water, respectively. The described methodology improves the previous developments using CDs and highlights the enormous potential of immunoassay methods using standard audio–video disk surfaces in combination with the CD/DVD drive for clinical analysis, drug discovery, or high-throughput multiresidue screening applications. Figure  Eye-catching image The analytical potential of commercial audio–video discs as molecular screening surfaces in combination with use of a standard CD/DVD drive as detector for quantitative immunoanalysis of a cancer marker and agrochemical residues is demonstrated.     

现代中国文学发展中的权力化语言

当代中国批评界对权力/话语关系的阐发实际上完成了“由微转宏”的转换,探讨现代中国文学发展中政治权力与语言的影响是一个重要的话题。政治权力造成了文学话语的暴力性,也形成了某些似是而非的话语逻辑。当然,反抗性话语也始终存在,并构成了现代中国文学的特殊的修辞。五四白话的推行是现代知识分子反抗政治强权话语的最显赫的成果,对这一历史运动冠以“文化霸权”的批评不仅严重脱离事实,而且本身也是对话语/权力概念的最大的误读。     

现代防弹材料发展概观

防弹材料的不断创新发展带来了防弹装备的现代化发展,现代防弹材料历经了3代发展：第1代防弹材料以特种钢、铝合金等硬质金属为主;第2代防弹材料是合成高分子材料,以凯芙拉（Kevlar）为代表的高性能合成纤维为主;第3代防弹材料则以高性能的有机-无机复合材料为主。     

Development and Comparative Study of Different Immunoenzyme Techniques for Pesticides Detection

Abstract

Different ELISA techniques have been developed for the detemination of four widely used pesticides: 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), simazine and atrazine. Dependences between the assay scheme and the limiting detectable concentration of the pesticide were studied. The cases of preferential applying of the scheme with immobilized antibodies or one with immobilized pesticide-protein conjugate have been revealed. The following approaches resulting in lowering of ELISA sensitivity were proposed: preliminary incubation of the tested sample with antibodies, immobilization of antibodies via staphylococcal protein A, usage of monovalent fragments of antibodies instead of native ones and chemical modification of the pesticide molecules in the sample. Optimal combinations of these approaches permitted to lower the detection limit of the assays in about 5–30 times. The achieved sensitivities were 3 ng/mL for 2,4-D, 5 ng/mL for 2,4,5-T, 0.05 ng/mL for simazine, and 0.1 ng/mL for atrazine, being acceptable for purposes of ecological monitoring.     

生化分析用荧光纳米粒子研究进展

荧光纳米粒子在生化分析领域的应用研究近十年来取得了令人瞩目的进展,引起了研究者的广泛关注,如何制备强荧光发光、高生物亲和的荧光纳米粒子是其在生化分析领域应用的前提和基础。本文评述了近年来在生化分析领域应用较多的几种荧光纳米粒子的研究进展与状况。引用文献103篇。     

二甲氧基硫代磷酸酯类农药多残留免疫分析方法研究

以二甲氧基硫代磷酸酯类农药为目标,设计合成了系列半抗原及抗原,制备了4种宽谱特异性抗体。研究结果表明,含不饱和烷烃手臂的半抗原所制备的抗体宽谱特异性优于含酰胺键手臂的半抗原所制备的抗体。采用目标待测物的特征次级结构作为包被半抗原可显著提高ELISA检测灵敏度。经条件优化建立的最佳间接竞争ELISA多残留检测方法可同时检测8种常用高毒农药,其检出限(LOD)在2.6～104μg/kg之间,符合相关限量标准要求。生菜样品药物添加平均回收率为73.9%～121.4%;平均相对标准偏差为10.6%～18.4%。菜心样品药物添加平均回收率为80.4%～121.2%;平均相对标准偏差为13.5%～24.4%。方法精密度均达到气相色谱法的检测水平。     

不同基质中有机氯农药提取技术及发展趋势

该文根据各种基质特点及其中有机氯农药的分布特点,对不同介质中有机氯农药的提取方法进行了归纳.着重介绍了不同基质中有机氯农药提取方法,如均质法、固相萃取法、索氏提取法、基质固相分散法、加速溶剂萃取法、超临界流体提取法、超声波提取法和微波辅助提取法等.通过详细实例,总结了上述提取方法的优缺点,并对有机氯农药提取方法做了展望...     

Recent Development in the Synthesis of Natural Saponins and Their Derivatives

Naturally occurring saponins are attractive candidates or lead compounds for new drug design and development and thus have become important synthetic targets. This short account reviews the recent progress in the chemical synthesis and structure-activity relationship (SAR) studies of naturally occurring saponins and their derivatives.