甜菜对豆磺隆的敏感性与豆磺隆吸收传导关系的研究

采用框栽和水培的研究方法,研究甜菜对豆磺隆的耐性差异与豆磺隆吸收及传导的关系。结果表明:甜菜对豆磺隆耐性与豆磺隆的吸收无关;豆磺隆茎叶处理后48h,耐豆磺隆甜菜与敏感甜菜根中豆磺隆含量存在极显著差异。耐性甜菜叶片中豆磺隆短时间的迅速降解,传导至根部少、受豆磺隆毒害时间短是耐性形成的原因之一。

园林树木种类及树冠大小对自流式注干药剂吸收及传导的影响

为探明园林树木种类、树冠大小及药剂种类对自流式注干药剂吸收及传导的影响,将甲氨基阿维菌素苯甲酸盐（简称甲维盐）分别与丁硫克百威、吡虫啉及阿维菌素组合,配制成2.8%甲维盐＋0.3%丁硫克百威（简称3.1%EB）、6%甲维盐＋4%吡虫啉（10%EB）与2%甲维盐＋0.5%阿维菌素（2.5%EB）3种乳油（EC）注干液剂,通过自流式树干注药方式,将3.1%EB和10%EB分别导入香抛树、柳树与栾树体内,研究了不同树种及不同药剂下药液吸收与传导的差异;采用2.5%EB,研究了香抛树树冠直径对药液吸收及传导的影响,同时通过HPLC-UVD检测方法,考察了药剂的残效期。结果表明：树木种类会显著影响注干药剂的吸收,且吸收速率依次为柳树〉香抛树〉栾树,开始注药5 d后,柳树上的药剂已被全部吸收,而栾树上3.1%EB和10%EB的剩余量分别为66.6%和48.6%;开始注药5 d后,10%EB在香抛树上的吸收率显著高于3.1%EB,两者剩余量分别为12.6%和29.3%,而其他处理则显示药剂种类对其吸收率影响不大;香抛树树冠直径大小对2.5%EB的吸收具有显著影响,冠径越大越利于药剂的吸收;开始注药起第113天,在香抛树枝叶中仍能检测到阿维菌素和甲维盐残留。研究表明,柳树对3.1%EB和10%EB的吸收性能均最佳,且供试药剂种类对其吸收性能影响不大;香抛树冠径大小与其对2.5%EB的吸收呈正相关性,且药剂残效期高达90～120 d。

中空介孔二氧化硅纳米粒子负载的鱼藤酮纳米颗粒在黄瓜植株中的吸收和传导特性

【目的】以纳米载体作为农药载体,提高农药利用率。【方法】采用自模板合成法,在合成实心介孔二氧化硅纳米粒子(Mesoporous silica nanoparticles,MSNs)的基础上,以水为刻蚀剂制备中空介孔二氧化硅纳米粒子(Hollow mesoporous silica nanoparticles,HMSNs)。通过溶剂挥发法将植物源农药鱼藤酮(Rot)负载到HMSNs的孔道中,制备得到Rot@HMSNs。测定Rot@HMSNs的缓释性能和杀虫活性。HPLC检测Rot@HMSNs中鱼藤酮在黄瓜植株中的系统分布。【结果】所制备的HMSNs粒径约250 nm,比表面积达999.4 m^(2)/g。Rot@HMSNs粒径均一,载药率达46.7%,具有良好的释放特性,释放模型符合Ritger-Peppas释放模型。HMSNs显著提高了鱼藤酮在黄瓜植株中的吸收和传导能力。【结论】通过纳米载体HMSNs可以提高鱼藤酮的利用率,此研究对于减少农药使用量、降低环境污染具有重要意义。

五种杀菌剂在水稻上的吸收与传导性能研究

茎叶喷雾是当前化学农药最常用的施药方式,但是存在着农药蒸发飘移、弹跳碎裂、因过度铺展而脱靶流失等缺陷,导致农药利用率低。通过研究农药在植物体内的吸收及传导性能,选择合适的农药研发根部施药的剂型与技术,能够降低环境因素对农药有效成分的不利影响,并通过农药的缓慢释放与剂量调控维持更长时间的药效,从而有效提高农药利用率。本研究以室内营养土和营养液两种模式培育的水稻为模式作物,研究了三环唑、噻呋酰胺、己唑醇、氟环唑和嘧菌酯5种不同类型的杀菌剂在水稻苗期植株中的吸收与传导行为。结果表明,这5种杀菌剂均可以被水稻幼苗根系吸收并向上传导,但效率存在差异。在营养土和营养液培养条件下,水稻幼苗根部的三环唑含量在4 h~2 d内明显高于茎叶部,施药5 d后三环唑在水稻中的转运因子值均大于1,说明三环唑具有良好的向上传输性能,而其他农药向上传输的能力较差。相比其他4种农药,三环唑更适合加工成根部施用的剂型,更易于通过水稻根部吸收后向上传输与分布,以有效防控茎叶部病害。该结果可为根部施用的药剂研发提供思路,为农药根部施药技术的发展提供指导。

中国农药应用工艺学20年的理论研究与技术概述

农药应用工艺学是研究提高农药利用率和施药效率,减轻或消除农药对环境的污染和对人、畜及有益生物危害风险的一门综合性学科。近20年来,中国在农药的吸收传导、控制释放、剂型研发、省力化施药、雾滴运动、高效装备及智能精准施药等方面取得了长足的进步:建立了药剂吸收量与种子包衣剂量之间的关系模型;阐明了农药控制释放的动力学规律,揭示了缓释农药提高作物安全性的生物学机制;研发了超低容量制剂、烟雾剂、粉尘剂、展膜油剂、缓释颗粒剂等省力化农药剂型和与之匹配的省力化施药技术;探明了农药雾滴在作物冠层的沉积流失规律,建立了农药利用率模型;建立了农药施用定量分析计算理论,提出了农药雾滴"杀伤半径"概念,推动了农药低容量喷雾技术发展;建立了植保无人飞机低容量喷雾技术体系,开启了人工智能(AI)施药技术的研究和应用,初步建立人工智能精准喷雾技术。中国农药应用已逐步实现从简单、粗放向科学、安全、智能精准的转变,为农药减施增效提供理论依据和技术支撑。

桶混助剂对25%吡唑醚菌酯悬浮剂防治黄瓜靶斑病的调控作用

为了明确桶混助剂对吡唑醚菌酯防治黄瓜靶斑病的调控作用,本研究结合助剂的结构特点,探究了SP-4806、SY-A、SY-B、SY-C等4种桶混助剂对25%吡唑醚菌酯悬浮剂对靶沉积界面性能、黄瓜体内吸收传导性能以及对黄瓜靶斑病防效的影响。试验结果表明,4种助剂均能降低表面张力、接触角,增强润湿渗透性能,促进25%吡唑醚菌酯悬浮剂在黄瓜体内向上传导作用,且助剂SP-4806对25%吡唑醚菌酯悬浮剂在黄瓜体内向下传导具有显著促进作用。4种桶混助剂均不同程度促进25%吡唑醚菌酯悬浮剂对黄瓜靶斑病的防效,其中添加助剂SP-4806处理的防效较25%吡唑醚菌酯悬浮剂显著提高,药后9 d防效分别为76.76%。本研究结果可为桶混助剂对25%吡唑醚菌酯悬浮剂应用于防治黄瓜靶斑病提供参考。

农药内吸性的研究现状与改善策略

合理利用和改善农药在植物中的内吸传导特性,可大幅提高农药在靶标部位的积累并减少农药对环境的污染。通过对农药内吸性的研究,已逐步揭示了植物吸收和传导农药的基本原理,对内吸性农药的研发具有重要意义。随着农药改造和纳米载体的出现及发展,利用不同方法或手段来改善农药内吸性的研究报道也逐渐增加。本综述主要从农药在植物中的内吸性研究进展、研究方法以及改善农药内吸性的策略3个方面进行了阐述,可为内吸性农药及其剂型的开发提供参考。

耐压低频吸声方面的橡胶材料与结构

声能的损耗,主要是由三种方式来完成的:其中在18世纪由司托克斯和克希何夫提出并建立的粘滞吸收和热传导吸收,被称为古典吸收.在此基础上,19世纪对提出了一种新的吸收理论-分子驰豫吸收.也被称做超吸收.这三种声吸收的理论基本上涵盖了声损耗的现象.

Interaction of Counter Propagating Electromagnetic Waves with the Absorbing Plate in the Waveguide

The interaction of two coherent counter propagating TE （transverse-electric） and TM （transverse-magnetic） electromagnetic waves with different initial phases in the absorbing plate placed in the regular ideal waveguide is considered. The losses of energy of TE and TM waves in the absorbing plate are calculated. Some features of tunnel interference in the absorbing plate in the waveguide are revealed. It is shown that the losses of energy strongly depend on the various parameters describing the interaction of the counter propagating waves. Definitely choosing the parameters we can control the electromagnetic processes in this case.

啶酰菌胺在黄瓜植株上的吸收与消解

[目的]建立气相色谱(GC)检测黄瓜样品中啶酰菌胺残留的方法。研究啶酰菌胺在黄瓜植株上的吸收、运转及其消解规律。[方法]采用QuEChERS前处理方法提取黄瓜和黄瓜叶片中残留的啶酰菌胺,并用电子捕获检测器(ECD)检测。[结果]施药处理部位上下部分黄瓜中,啶酰菌胺残留量最高值分别出现在处理后4 h和1 d;啶酰菌胺处理后8 h,上部叶片啶酰菌胺残留量达最高值0.42 mg/kg,仅为下部叶片的4%;施药后2 d,下部叶片中啶酰菌胺残留量最高达9.20 mg/kg。但叶片和黄瓜中残留的啶酰菌胺均可快速降解,施药处理7 d后,啶酰菌胺残留量均低于5 mg/kg(MRL)。[结论]啶酰菌胺在黄瓜中的半衰期为1.3 d,在黄瓜叶片中的半衰期为3.5 d。啶酰菌胺在黄瓜植株上有双向传导性,但上下传导的差异较大。

A review of high thermal conductivity carbon-based materials for microwave absorption materials

The ever-increasing integration of electronic devices has inevit-ably caused electromagnetic interference and heat accumulation problems,and dual-function materials with both a high thermal conductivity and high electromagnetic wave absorption(EWA)are regarded as an effective strategy for solving these problems.Carbon materials are widely used as thermal and EWA fillers due to their excellent conductivity and outstanding thermal conduction properties,and have become a research hotspot in the field of high thermal conductivity,microwave absorbing materials in recent years.The status of current research progress on carbon-based high thermal-conduction microwave absorption materials,including carbon fibers,carbon nanotubes,graphene and amorphous carbon,is re-viewed,and the influence of the structure of the materials on their absorption and thermal conductivity properties,such as core-shell structure,three-dimensional network structure,and heteroatom doping,is also elaborated.Feasible solutions for the cur-rent problems with these materials are proposed,with the aim of providing valuable guidance for the future design of carbon-based high thermal conduction microwave absorbing materials.

Ammonium homeostasis and signaling in plant cells

Nitrogen is an essential macronutrient in plant growth and development. Ammonium is one of the major inorganic nitrogen forms for root uptake. The homeostasis of ammonium in the plant cell is under tight control to prevent ammonium toxicity when in excess. In the ammonium sig- naling pathway, internal and external ammonium can be de- tected by specific sensors, which in turn triggers a series of proper plant ammonium responses including transcription regulation and phosphorylation. Ammonium absorption is mainly mediated by the root-located ammonium transporters, which are key regulators in the nitrogen signaling pathway. Many researchers have attempted to unravel the mechanisms of ammonium uptake by the transporters. Fine-tuned modulation of ammonium homeostasis is necessary to main- tain an appropriate level of ammonium in the cytoplasm, which is a balance of ammonium efflux, assimilation and compartmentation. Recently, there has been important pro- gress in revealing the ammonium sensing and signaling mechanisms. In this review, we focus on the homeostatic regulation and signaling of cytosolic ammonium.

Spectral Absorption Gas Sensor Based on Anti-Resonant Reflecting Optical Waveguide

An air-silica microstructure optical fiber based on the anti-resonant reflecting optical waveguide （ARROW） principle was used to develop a spectral absorption gas sensor. The ARROW fiber has an air core and an air cladding layer. An ARROW fiber with a length of 725mm was used to construct a sensing system to detect acetylene gas. The gas was injected into the fiber from one end of the fiber. The transmission spectra were collected using an optical spectrum analyzer. The results indicate that the system can detect the gas of different concentrations and has the good system linearity. The response time of the system is about 200 s.

Biochar Effect on Water Evaporation and Hydraulic Conductivity in Sandy Soil

Biochar, as a kind of soil amendment, has important effects on soil water retention. In this research, 4 different kinds of biochars were used to investigate their influences on hydraulic properties and water evaporation in a sandy soil from Hebei Province, China. Biochar had strong absorption ability in the sandy soil. The ratio of water content in the biochar to that in the sandy soil was less than the corresponding ratio of porosity. Because of the different hydraulic properties between the sandy soil and the biochar, the saturated hydraulic conductivity of the sandy soil gradually decreased with the increasing biochar addition. The biochar with larger pore volume and average pore diameter had better water retention. More water was retained in the sandy soil when the biochar was added in a single layer, but not when the biochar was uniformly mixed with soil. Particle size of the added biochar had a significant influence on the hydraulic properties of the mixture of sand and biochar. Grinding the biochar into powder destroyed the pore structure, which simultaneously reduced the water absorption ability and hydraulic conductivity of the biochar. For this reason, adding biochar powder to the sandy soil would not decrease the water evaporation loss of the soil itself.

Optical Humidity Sensor Based on Air Guided Photonic Crystal Fiber

We proposed a novel relative humidity （RH） sensor based on the air guided photonic crystal fiber （AGPCF） using the direct absorption spectroscopic method in this paper. The wavelength scanning around the water vapor absorption peak around 1368.59nm was realized by injecting the saw-tooth modulated current to a distributed-feedback laser diode. A reference signal was used as a zero absorption baseline and to help reduce the interference from the distributed-feedback laser source and probed region. The humidity level was determined by the normalized voltage difference between the reference signal and sensor signal at the peak of water vapor absorption. We demonstrated that a length of 5-cm AGPCF with a fixed small air gap between the single mode fiber （SMF） and hollow core fiber as an opening achieved a humidity detection resolution of around 0.2%RH over the range 0 to 90%RH which did not require the use of any hygroscopic coating material.

Slow light propagation without absorption based on intersubband transitions in a semiconductor quantum well

When semiconductor quantum wells(SQWs) interact with lasers,the group velocity of the low-intensity light pulse is studied theoretically.It is shown that by adjusting the parameters,slow light propagation of the probe field can be exhibited in such a system.Meanwhile,the probe absorption-gain spectra can be changed from absorption to zero,i.e.,electromagnetically induced transparency(EIT).It is easy to observe the light propagation experimentally,and it leads to potential applications in many fields of solid-state quantum information,for example,optical switching,detection and quantum computing.