Progress in Laser Ignition Based on Passively Q-Switched Solid-State Lasers

稀薄燃烧是一种先进的燃烧方法,采用稀薄燃烧技术可以使发动机在减少废气排放的同时提高热效率。稀薄燃烧催发了激光点火技术的应用。最近几十年,脉冲宽度短、峰值功率高的被动调Q固体激光器得到了飞速的发展,特别是采用掺钕离子(nd3+)和镱离子(yb3+)的激光材料作为激光增益介质,用Cr4+∶yAg作为被动调Q开关的微片固体激光器在激光点火研究方面取得了长足的进展。系统地介绍了激光点火的机理和应用于激光点火的基于nd∶yAg/Cr4+∶yAg与yb∶yAg/Cr4+∶yAg的被动调Q固体激光器的最新研究进展,以及两类被动调Q激光器在激光点火应用中的优缺点,并指出了yb∶yAg/Cr4+∶yAg被动调Q微片激光器在激光点火应用中的优势、需解决的问题及发展方向。Laser ignition technology emerges as an advanced combustion method for engine.It can make the engine reduce waste gas emission and improve the thermal effect.Lean burning improves thermal efficiency and reduces exhaust emissions by laser ignition.In recent decades, short pulse, high peak power passively Q-switched solid-state lasers are developed rapidly for their potential applications in laser ignition.Especially the passively Q-switched lasers using neodymium ion(Nd3+) or ytterbium ion(Yb3+) doped materials as the laser gain media and Cr4+∶YAG as the saturable absorber, make much progress in potential laser ignition applications.We overviewe the mechanism of laser ignition and progresses in passively Q-switched solid-state lasers based on Nd∶YAG/Cr4+∶YAG and Yb∶YAG/Cr4+∶YAG.And the advantages and disadvantages of these two types passively Q-switched lasers used in laser ignition are discussed systematically.The advantages of Yb∶YAG/Cr4+∶YAG passively Q-switched microchip lasers used in laser ignition are addressed for future application in engine ignition.And the key issues for developing high peak power Yb∶YAG/Cr4+∶YAG passively Q-switched microchip lasers are also addressed.国家自然科学基金(61275143); 教育部新世纪优秀人才支持计划(NCET-09-0669

新型纳米结构电极体系的界面结构和性能

1 背景 具有重要应用功能的新体系和新研究方法,是当代电化学与其他学科实现交叉及电化学本身发展的二个主要研究方向。“九五”国家自然科学基金重点项目“新型纳米结构电极体系的界面结构和性能”,正是遵循电化学的主要方向,以新型材料或结构、尤其是纳米结构制备电极(包括表面增强光学电极、过渡金属薄膜和表面合金电极、纳米结构半导体膜电极、电活性表面团簇电极);利用电化学现

细分贸易对中国行业技术进步的影响

基于中国1995—2009年的数据,建立动态面板模型探索不同贸易类型对行业技术进步的影响差异。研究发现:贸易的开展对中国技术进步的影响并非完全一致,不仅存在贸易种类间的差异,同时也存在行业间的差异。其中,对于制造业的技术进步来说,中间品出口、用于出口的中间品进口和用于国内生产的中间品进口这三类贸易存在促进效应,用于出口的中间品进口贸易的正向效应最高,最终消费品出口和进口贸易存在阻碍效应;对于服务业来说,最终消费品出口、进口和用于出口的中间品进口这三类贸易存在促进效应,用于出口的中间品进口贸易的正向效应最高,中间品出口和用于国内生产的中间品进口贸易存在阻碍效应。国家社会科学基金项目(16BJL067

The basic research progress of catalytic chemistry in China in 2008 based on the published papers

依据我国催化领域的学者在一些重要国际学术刊物上发表的论文,从能源和化工催化、环境催化、绿色催化、手性催化、有机合成中的多相催化、光催化、催化新材料和催化剂新合成方法、催化活性中心和催化反应机理表征等方面,简要介绍2008年我国催化学科在基础研究方面所取得的一些进展.This review highlights fundamental research progress in catalysis discipline in China in 2008 based on the scientific papers published in some prestigious international journals related to catalysis.The present review mainly includes the following aspects:catalysis for energy and chemical processes,environmental catalysis,green catalysis,chiral catalysis,heterogeneous catalysis for organic synthesis,photocatalysis,novel catalytic materials and catalyst synthetic methods,characterizations of active sites and reaction mechanisms

Investigations of electrochemical performance of copper coated AB 5 type metal hydride electrodes

通过改变处理溶液中铜的含量和PH值等包覆条件，考查了Ab5型贮氢合金酸性包覆铜处理方法和相应金属氢化物电极的放电性能。研究表明该方法具有经济易操作的特点，处理溶液的PH值对铜包覆速度和电极初期放电性能有很大影响。通过循环伏安实验和紫外可见光谱技术研究了包覆铜层的稳定性，实验结果表明电极表面包覆层能通过形成氧化物，以CuO2-2的形式溶解到电解液中，并且溶解在电解液中的铜离子对氧化镍正极的电极性能产生不良影响。The coating conditions of copper on AB 5 type hydrogen storage alloy and the electrochemical performance of copper coated metal hydride electrodes have been investigated through changing the concentration of copper ions and pH value of the treatment solution.The results showed that the copper coating treatment improved the initial electrochemical performance of metal hydride electrodes,and the pH value of treatment solution was important to increase the coating rate of copper and improve the initial discharging behavior of electrodes.Furthermore,the stability of copper coated layer on metal hydride electrode also have been studied with the help of cyclic voltammetry and UV visible spectrophotometer.It was demonstrated that the copper coated layer was oxidized and dissolved into the electrolyte in the form of cupric oxide,and the redox behavior of nickel hydroxide/oxyhydroxide electrode is affected by the copper ions dissolved in the electrolyte.国家“863”计划;国家自然科学基

Emission Mechanism of High Al-content AlGaN Multiple Quantum Wells

紫外LED的发光功率和效率还远不能令人们满意,波长短于300 nm的深紫外LED的发光效率普遍较低。厘清高Al组分Al Ga N多量子阱结构的发光机制将有利于探索改善深紫外LED的发光效率的新途径、新方法。为此,本文通过金属有机气相外延技术外延生长了表面平整、界面清晰可辨且陡峭的高Al组分AlGa N多量子阱结构材料,并对其进行变温光致发光谱测试,结合数值计算,深入探讨了Al Ga N量子阱的发光机制。研究表明,量子阱中具有很强的局域化效应,其发光和局域激子的跳跃息息相关,而发光的猝灭则与局域激子的解局域以及位错引起的非辐射复合有关。The quantum efficiency of deep UV light emitting diodes( LED) drops dramatically with the increasing of Al content. Understanding the emission mechanism of high Al-content Al Ga N multiple quantum wells( MQW) is the one of the most important objects for improving the quantum efficiency of deep UV LED. In this work,high Al-content Al Ga N MQW structure with atomically flat hetero-interfaces was grown and characterized by photoluminescence( PL) measurements at different temperatures. The results indicate that there is a strong exciton-localization effect in the MQW structure and the emission is closely related to the hopping of the excitons. Due to the exciton delocalization and nonradiative recombination at defects,the PL intensity is strongly quenched at high temperatures.“973”国家重点基础研究发展计划(2012CB619300);; “863”国家高技术研究发展计划(2014AA032608);; 国家自然科学基金(U1405253;61227009;11204254;11404271);; 福建省自然科学基金(2015J01028)资助项

西沙赵述岛海域珊瑚礁鱼类物种多样性

2017年4月采用水下录像方式对西沙赵述岛潟湖内外珊瑚礁鱼类种类组成、密度和种类相似度以及造礁珊瑚覆盖率进行评估.共鉴定珊瑚礁鱼类58种,隶属于1纲3目18科37属,其中鲈形目占绝对优势,共55种,占总种类数的94.83%.潟湖内外的珊瑚礁鱼类平均密度存在显著差异,且潟湖内(1.712 3±0.273 2尾/m2)高于潟湖外(0.655 1±0.029 3尾/m2).胸斑眶锯雀鲷(Stegastes fasciolatus)、三斑海猪鱼(Halichoeres trimaculatus)、宅泥鱼(Dascyllus aruanus)和栉齿刺尾鱼(Ctenochaetus striatus)为西沙赵述岛的主要鱼类,前3种主要分布在潟湖内,而栉齿刺尾鱼主要分布在潟湖外.潟湖内外珊瑚礁鱼类的种类相似性系数为0.29,属于中等不相似.潟湖内外的造礁珊瑚覆盖率分别为(7.98±9.91)%和(12.35±6.21)%,不存在显著差异.调查区内珊瑚礁鱼类以小型种类为主,珊瑚礁鱼类中食用价值高的石斑鱼科和鹦嘴鱼科的鱼类密度均不高,这可能与日渐退化的珊瑚礁生态功能和日益增加的人类活动相关.海南省重大科研计划项目(ZDKJ2016013);;农业农村部渔业渔政管理局项目(171821301354051007);;国家海洋局项目(220203993022761133

Studies on chemical constituents in ethanolic extract from Acanthus ilicifolius as a pharmaceutic mangrove

目的探讨老鼠簕的化学成分。方法将老鼠簕全株粉碎后,用95%乙醇浸提3次,合并浓缩,浸膏的石油醚部位经反复硅胶柱层析分离,结合波谱学数据鉴定化合物结构。结果从石油醚部位分离得到8个化合物,分别为β-谷甾醇(Ⅰ)、豆甾醇(Ⅱ)、正十六烷酸(Ⅲ)、正二十八烷酸(Ⅳ)、4,22-二烯-3-酮豆甾烷(stig-masta-4,22-dien-3-one)(Ⅴ)、4-烯-3-酮豆甾烷(stigmast-4-en-3-one)(Ⅵ)、5,22-二烯-7-酮-3β-羟基豆甾烷(3β-hydroxystigmasta-5,22-dien-7-one)(Ⅶ)、2-唑啉酮(2-benzoxazolinone)(Ⅷ)。结论其中Ⅴ,Ⅵ,Ⅶ为首次从该植物中分离得到。Objective To study the chemical constituents of Acanthus ilicifolius.Methods The air-dried and powdered plant material was extracted with 95% ethanol.Silica gel and Sephadex LH-20 column chromotography were used in the isolation from the ethanol extracts of the whole plant,the compounds were determined on the basis of various modern spectroscopic analyses and physical constants.Results Eight compounds were isolated from the petroleum ether soluble portion,identified as β-sitosterol(Ⅰ),stigmasterol(Ⅱ),n-hexadecane acid(Ⅲ),n-octacosanic acid(Ⅳ),stigmasta-4,22-dien-3-one(Ⅴ),stigmasta-4-en-3-one(Ⅵ),3β-hydroxystigmasta-5,22-dien-7-one(Ⅶ) and 2-benzoxazolinone(Ⅷ).Conclusion CompoundⅤ,Ⅵ,Ⅶ were obtained from the genus for the first time.国家自然科学基金(30671646);; 福建省科技计划资助项目(2003Y036

福建省实验动物学学科发展研究报告

1实验动物科学概述1.1实验动物科学的概念实验动物科学(lAbOrATOry AnIMAl SCIEnCES)是以实验动物资源研究、质量控制和利用实验动物进行科学实验的一门综合性学科。在《学科分类与代码标准》(gb/T13745-1992)中,与实验动物科学有关的学科分别是“实验动物学“、“医学实验动物学“、“比较病理学“等