51 research outputs found

    Study on the Fermentation Strategies and Metabolic Regulation of Arachidonic Acid by M. alpina LU166

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    花生四烯酸(Arachidonicacid,ARA)为ω-6高级多不饱和脂肪酸,具有促进婴幼儿脑部发育、调节神经传导、降低胆固醇等多种重要的生理功能,在膳食营养、医药、化妆品等多领域有广泛应用。传统的ARA主要来源于动物油等,难以满足市场需求,利用微生物发酵法生产ARA具有周期短、不受地域限制等优点,成为当前研究的热点之一,而高山被孢霉被认为是ARA的优良生产菌株。 本文以实验室自主分离并鉴定的一株ARA生产菌株—M.alpinaLU166为研究对象,从油脂代谢和ARA合成途径着手,考察了以下几个因素对发酵的影响。首先发现凹槽摇瓶培养可以稳定地控制菌体形态为刺突状小球,这一形态比絮状和大球状...Arachidonic acid is a kind of ω-6 polyunsaturated fatty acid (PUFA), it has many physiological functions, like improving brain development in infants and young children, regulating nerve conduction, and reducing cholesterol levels, so it is widely applied in dietary nutrition, medicine, and cosmetics fields. Traditional ARA mainly comes from animal oils, which is difficult to meet the market dem...学位:工学硕士院系专业:化学化工学院_化学工程学号:2062013115149

    Personnel medical examination prevalence study and countermeasure analysis in Xiamen

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    目的了解厦门市民参加健康体检行为的现状和影响行为取向的相关因素,为制定相关的策略和政策提供科学依据。方法对厦门市各体检中心参加体检人员进行现场问卷调查,用SPSS 17.0统计软件对调查问卷的结果进行分析并评价。再结合社会学研究方法,根据不同年龄组组织体检人员做小组访谈,整合定量与定性资料得出结论和对策。结果 62.3%的被调查者知道定期体检的好处,78.8%的人认为体检是有必要,52.7%的人每年进行至少1次健康体检,体检由单位和医保付费的占到了81.8%,91%的人对体检有意见。结论厦门市参加体检人员对健康体检认知情况尚可,比较依赖公费体检,多数对体检机构服务不满意。对此,我们应该采取相应对策促进全民健康体检目标的实现

    CdS量子点表面巯基酸分子排列方式的宽带和频光谱研究

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    巯基酸是一种常用的量子点表面配体,对量子点的光电属性和催化活性具有重要影响。用宽带和频光谱(BB-SFG)研究巯基酸分子(HS-(CH2)n-COOH,n = 2,5,10)在金膜和硫化镉(CdS)量子点表面的排列方式。结果表明:在金表面上3种自组装巯基酸单分子膜,都可以检测到与巯基和羧基相连的两个亚甲基的C-H振动和频谱峰。而在CdS量子点表面,短链的HS-(CH2)2-COOH和HS-(CH2)5-COOH处于较无序的混乱包覆状态,检测不到C-H振动和频谱峰;但长链的HS-(CH2)10-COOH在CdS量子点表面是较有序的类似反胶束状的排列,可以检测到与羧基相连的亚甲基的C-H振动谱峰。国家重点研发计划项目(2017YFA0206500,2016YFA0200702)国家自然科学基金(21327901)

    无卤含硅阻燃环氧树脂制备与性能研究

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    合成了一种新型的含硅环氧单体-二缩水甘油基二甲基硅烷(DGDMS),将其以一定比例加入到普通商用环氧树脂(DER332)中,使用固化剂4,4'-二氨基二苯砜(DDS)共固化制得无卤含硅阻燃环氧树脂,研究探讨该阻燃环氧树脂的性能。结果表明:随着DGDMS含量的增加,空气和氮气中成炭率(700℃)相应得到提高,同时,氧指数由25.5上升至38.0,证明了在环氧树脂分子链中引入DGDMS可大大提高其阻燃性能

    Electric-field-induced selective catalysis of single-molecule reaction

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    随着单分子电学检测技术的迅速发展,分子电子学的研究不再局限于分子电子学器件的构筑及其电学性质的测量,而且扩展到单分子尺度化学反应过程的探索。然而目前相关的研究仍然局限于理论计算方面,在单分子尺度上实时监测和调控化学反应的活性和选择性是化学领域的长期目标和挑战。针对这一挑战,洪文晶教授课题组与程俊教授课题组合作,自主研发了精密科学仪器,将单个有机分子定向连接在两个末端尺寸为原子级的电极之间,解决了化学反应中分子取向控制的问题.理论计算结果证实了定向电场可以有效地稳定化学反应的过渡态,从而降低反应能垒。该研究工作在化学化工学院洪文晶教授、程俊教授、能源材料化学协同创新中心(iChEM)刘俊扬副研究员的共同指导下完成,由硕士研究生黄晓艳、iChEM博士研究生唐淳、博士研究生李洁琼以及兰州大学的陈力川博士作为共同第一作者,化学化工学院师佳副教授、陈招斌高级工程师、夏海平教授和田中群教授,萨本栋微纳研究院杨扬副教授、环境与生态学院白敏冬教授以及兰州大学张浩力教授参与了研究工作的讨论并给予指导,博士后乐家波、博士研究生郑珏婷、张佩(已毕业)、李瑞豪、李晓慧也参与了研究工作。Oriented external electric fields (OEEFs) offer a unique chance to tune catalytic selectivity by orienting the alignment of the electric field along the axis of the activated bond for a specific chemical reaction; however, they remain a key experimental challenge. Here, we experimentally and theoretically investigated the OEEF-induced selective catalysis in a two-step cascade reaction of the Diels-Alder addition followed by an aromatization process. Characterized by the mechanically controllable break junction (MCBJ) technique in the nanogap and confirmed by nuclear magnetic resonance (NMR) in bottles, OEEFs are found to selectively catalyze the aromatization reaction by one order of magnitude owing to the alignment of the electric field on the reaction axis. Meanwhile, the Diels-Alder reaction remained unchanged since its reaction axis is orthogonal to the electric fields. This orientation-selective catalytic effect of OEEFs reveals that chemical reactions can be selectively manipulated through the elegant alignment between the electric fields and the reaction axis.This work was supported by the National Key R&D Program of China (2017YFA0204902), the National Natural Science Foundation of China (21722305, 21703188, 21673195, 21621091, 51733004, 51525303, and 91745103), the China Postdoctoral Science Foundation (2017M622060), and the Young Thousand Talents Project of China. 该工作得到国家自然科学基金委(21722305、21703188、21673195、51733004、51525303、91745103),国家重点研发计划课题(2017YFA0204902),中国博士后面上基金(2017M622060)的资助,以及固体表面物理化学国家重点实验室、醇醚酯化工清洁生产国家工程实验室、能源材料化学协同创新中心的支持

    Transition from tunneling leakage current to molecular tunneling in single-molecule junctions

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    数十年来,半导体工业一直遵循基于“摩尔定律”所设定的发展蓝图,逐步提升集成电路芯片上晶体管的集成度和运行速度,减小器件尺寸。为探索这一尺寸极限,课题组基于机械可控裂结技术自主开发了具有飞安级电学测量和亚纳米级位移控制灵敏度的科学仪器,在国际上首次获取了一系列具有不同重复单元的寡聚苯乙炔类分子电导随电极间距的演变关系,并发现随着电极间距的缩小,器件电输运由通过分子器件电流占主导逐步转变到由隧穿漏电流占主导。对于本研究中具有最小尺寸的寡聚苯乙炔分子器件,其由于隧穿漏电流所制约的尺寸极限可小至0.66 nm,预示了有机分子器件在未来电子器件小型化方面具有重要的应用潜力。 这一研究工作是在化学化工学院洪文晶教授、萨本栋微纳研究院杨扬助理教授以及英国Durham University的MartinR. Bryce教授共同指导下完成的。能源材料化学协同创新中心iChEM Fellow刘俊扬博士为论文第一作者,博士研究生郑珏婷、李瑞豪和硕士研究生黄晓艳、唐永翔、皮九婵、本科生王飞等参与了研究工作。田中群教授、毛秉伟教授和师佳副教授为论文工作提供了重要指导。【Abstract】The tunneling leakage current will be a major quantum obstacle during miniaturization in the semiconductor industry down to the scale of several nanometers. At this scale, to promote charge transport and overcome the tunneling leakage current between the source and drain terminals, molecular electronic junctions offer opportunities by inserting molecules between these two electrodes. Employing a series of oligo(aryleneethynylene) (OAE) molecules, here we investigate the transition from tunneling leakage current to molecular tunneling in the single-molecule devices using mechanically controllable break junction (MCBJ) technique, and the transition distances of the OAE molecular junctions were determined and even down to 0.66 nm for OAE2 molecular junction, which demonstrates that the intrinsic charge transport properties of a single-molecule device can be outstripped from the tunneling leakage current. Consequently, molecular electronic devices show the potential to push the ultimate limit of miniaturization to the scale of several angstroms.This work was supported by the National Key R&D Program of China (2017YFA0204902). This work was also generously supported by the Young Thousand Talent Project of China, the EC FP7 ITN “MOLESCO” project number 606728, the National Natural Science Foundation of China (nos. 21703188, 21673195, 21503179), and the China Postdoctoral Science Foundation (2017M622060). 该工作获得科技部国家重点研发计划课题(2017YFA0204902),国家自然科学基金委(21673195、21703188、21503179)以及中国博士后科学基金(2017M622060)等项目的资助,也得到了固体表面物理化学国家重点实验室、能源材料化学协同创新中心的支持

    基于ReaxFF MD的正十二烷氧化的反应机理分析

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    正十二烷是吸热型碳氢燃料的重要组分,常被作为燃料直链烷烃的模型化合物,本文用ReaxFF MD方法模拟了正十二烷的氧化过程。利用国际上首个ReaxFF MD模拟结果的化学反应分析工具VARxMD可直接观察其燃烧过程的详细化学反应,快速得到正十二烷氧化的可能反应路径

    Application of flat UF in separation and purification of natural taurine

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    介绍了天然牛磺酸提取工艺中存在的问题及膜分离技术,研究了4种不同规格超滤膜在章鱼下脚料中提取天然牛磺酸中的应用,从膜通量、蛋白去除率、牛磺酸收率、膜污染和膜清洗等各方面考察了不同材质、不同切割分子量的平板超滤膜分离性能.得出了1#平板超滤膜(MWCO 30 000g/MOl,CA)为从章鱼下脚料中分离牛磺酸的较佳分离膜.This article elaborates on the problems which exist in the separation and concentration of nature taurine with membrane separation technology.It analyzes how four different types of ultrafiltration membrane are applied to extract nature taurine from octopus scraps.The separation performance of flat ultrafiltration membranes which have different materials and MWCO is studied in terms of the membrane flux,the removal rate of protein,the yield of taurine,the repeated utilization of the membrane.The article finds out that 1#flat UF membrane(MWCO 30 000g/mol,CA)is the preferred membrane

    Main Crops Carbon Footprint in Pingluo County of

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    农田碳足迹可以全面地反映农作物生产过程中各种因素引起的碳排放效应,是指导农业生产节能减排的重要指标。为探明农作物生产的碳足迹,基于宁夏回族自治区平罗县农田生产的实地调查数据,利用碳足迹的基本理论和方法,测算了该县农作物碳足迹。结果表明,水稻、玉米和小麦的碳足迹分别为1 487.56±164.59,913.03±142.99和809.75±144.99kg Ce/(hm2.a);碳成本分别为0.17±0.05,0.08±0.02g和0.12±0.03kg Ce/kg;化肥的施用量是影响碳足迹的主要因素,而水稻生产过程中灌溉水及育秧过程也是其碳足迹较高的主要原因。为了提高农田固碳减排增汇效益,应压缩水稻种植面积,扩大玉米和小麦种植,同时,建立节肥低碳高效的种植模式是实现平罗县农田节能减排的有效途径。 The carbon emission caused by various factors during the crop production process can be roundlyevaluated using carbon footprint of farmland,which is an important indicator that can provide a guidance forenergy saving and emission reduction in agricultural industry.In order to find out the carbon footprint ofcrop production,the carbon footprint of Pingluo County in Ningxia Hui Autonomous Region is calculatedbased on the investigated data of farmland production in the county by using basic theories and research approaches of carbon footprint.Results show that the carbon footprints of rice,corn and wheat are 1 487.56±164.59,913.03±142.99and 809.75±144.99kg Ce/(hm2·a)and the carbon costs,0.17±0.05,0.08±0.02and 0.12±0.03kg Ce/kg,respectively.The application rate of chemical fertilizer is a main influencefactor for the carbon footprint.Additionally,irrigation water and seedling production are the key causes ofhigh-carbon footprint during rice production.To improve the benefits of fixing carbon,reducing emissionsand adding carbon sinks of farmland,rice planting area should be reduced and corn and wheat planting areasshould be expanded.Meanwhile,the construction of fertilizer-saving,low-carbon and efficient agriculturalcropping patterns is an effective way to realize energy saving and emission reduction of the farmlands inPingluo County
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