The Simulation of Temperature and Velocity Field in the Heat Exchanger of Light-Gathering Battery Components

根据换热器结构特点及换热特性,对换热器内的换热情况进行理论分析,建立了以水为工质的流动和传热的几何模型,并用有限元分析软件AnSyS模拟出换热器在换热过程中水的温度场和速度场的变化情况,分析了换热器内这两种场的相互作用,对换热器的最优化设计提供了理论依据。According to structural features and heat-transfer characteristics of heat exchangers,the situation of heat-transfer in heat exchanger is theoretically analyzed in this paper and this article establishes geometric models of the flow and heat-transfer taking water as the working fluid.Finite element analysis software ANSYS is used to simulate the changes of the temperature field and velocity filed of the water during the heat-transfer process of heat exchangers.The interaction on this two fields in the heat exchanger presents a theoretical reference on the optimization design of the heat exchanger

螺内酯联合贝前列腺素钠对2型糖尿病肾病患者肾功能的影响

目的探讨贝前列素钠联合螺内酯治疗2型糖尿病肾病的临床研究。方法选取2型糖尿病肾病患者94例,按照随机数字表法随机分为观察组47例与对照组47例。对照组采取单用贝前列素钠治疗,观察组在对照组基础上结合螺内酯联治疗。比较两组治疗前后尿素氮、血肌酐、24 h尿微量清蛋白(m ALB)和肾小球滤过率(GFR)变化。结果观察组总有效率(93.62%)高于对照组(72.34%)(P <0.05)。两组治疗后尿素氮和血肌酐水平均降低(P <0.05);观察组治疗后尿素氮和血肌酐水平低于对照组(P <0.05)。两组治疗后mALB降低而GFR上升(P <0.05);观察组治疗后m ALB低于对照组而GFR高于对照组(P <0.05)。结论贝前列素钠联合螺内酯治疗2型糖尿病肾病患者疗效显著,能改善患者肾功能

Potential direct interspecies electron transfer (DIET) from Clostridium spp. to Methanosarcina barkeri in amethanogenic isolation

【目的】革兰氏阴性菌Geobacter metallireducens可以与乙酸型产甲烷菌Methanosaeta harundinacea或Methanosarcina barkeri通过种间直接电子传递(DIET)还原CO2产甲烷。本实验室前期的研究发现Methanosarcina mazei和Geobacteraceae在铁还原富集培养中形成团聚体,可能存在直接电子传递。然而,革兰氏阳性菌(如Clostridium spp.)与产甲烷菌是否存在种间直接电子传递尚不明确。【方法】采用Hungate厌氧滚管法,以乙醇为唯一电子供体从铁还原富集培养体系中获得产甲烷分离物(S6)。通过T-RFL..

Potential direct interspecies electron transfer (DIET) from Clostridium spp. to Methanosarcina barkeri in methanogenic isolates

[Objective] Geobacter metallireducens, a Gram-negative bacterium, can directly transfer electron to acetoclastic methanogens such as Methanosaeta harundinacea and Methanosarcina barkeri for reducing carbon dioxide to methane. Our previous results showed that Methanosarcina mazei and Geobacteraceae formed aggregates in an iron(III)-reducing enrichment culture indicating direct interspecies electron transfer. However, the capability of direct electron transfer with methanogens for Gram-positive iron(III)-reducing bacteria such as Clostridium spp. is still unknown. [Methods] In this further study, methanogenic isolates(S6)were achieved from the iron(III)-reducing enrichment by roll-tube(Hungate)method with ethanol as the sole electron donor. We used terminal restriction fragment length polymorphism(T-RFLP)and clone library analysis to investigate the community of S6 and used electrochemical method such as cyclic voltammetry(CV)to confirm the electroactivity of isolates. [Results] Clone library analysis of 16S rRNA gene showed that Clostridium spp.(close to C. tunisiense)and Methanosarcina barkeri were predominant in the bacterial and archaeal community, respectively. Interestingly, addition of G. metallireducens into S6 did not increase the ability of both iron(III)reduction and methanogenesis, indicating that Clostridium spp. may play a similar role in direct interspecies electron transfer from G. metallireducens to M. barkeri. Furthermore, current generation of the S6 suspension dramatically decreased when contact between the organisms and the electrodes was prevented by dialysis bag, and CV showed no obvious redox peaks. [Conclusion] These results suggested that there was direct electron transfer in the methanogenic isolates. This work demonstrated that the dominant Gram-positive Clostridium spp. can potentially directly transfer electron to M. barkeri in methanogenic isolates

Studies on the Ion Conductive Performance of Composite Polymer Electrolyte Containing Nano-scale SiO_2

于含锂盐的梳状聚醚聚合物电解质添加纳米S iO2制备复合聚合物电解质.并分别使用DSC和XRD研究S iO2对聚合物链段运动能力的影响.电导率测试表明,在相同的锂盐浓度下,加入5%的纳米S iO2后,聚合物电解质具有最高的离子电导率,30℃时为7.8&times;10-5S/cm,80℃时达到4.5&times;10-4S/cm.与未添加S iO2的聚合物电解质相比,电导率提高了30%~60%.TGA测定给出该聚合物的热分解温度为300℃左右,显示出良好的安全性能.Nano-silicon oxide was doped into a novel comblike polyether,poly(3-(methoxy(triethylenoxy))methyl-3'-methyloxetane) to prepare a series of composite polymer electrolyte.The ion conductivity measurement revealed that the composite polymer electrolyte added with 5% weight fraction of SiO2 has the highest ion conductivity of 7.8&times;10-5 S/cm at 30℃ and 4.5&times;10-4 S/cm at 80℃,which is increased 30%~60% as compared to the polymer electrolyte without adding any SiO2.DSC results implied that the nano-silicon oxide inserts into the macromolecule chains to increase the free volume and decrease the glass transition temperature to enhance the ion conductivity.In addition,it seems that the crystallization occurred due to the hydrogen bonds between hydroxyl group on the surface of silicon oxide and oxygen atoms on the polymer chains.And XRD spectrum demonstrated the existence of micro-crystals.The heat decomposition temperature was detected by TGA,indicating the good heat stability of this composite polymer electrolyte.作者联系地址：北京理工大学材料科学与工程学院,北京理工大学材料科学与工程学院,北京理工大学材料科学与工程学院,北京理工大学材料科学与工程学院,北京理工大学化工与环境学院,北京理工大学化工与环境学院 国家高技术绿色材料发展中心,北京100081,国家高技术绿色材料发展中心,北京100081Author's Address: 1.School of Materials Science &amp; Engineering,Beijing Institute of Technology,Beijing 100081,China,2.School of Chemical Engineering &amp; Environment, Beijing Institute of Technology,Beijing 100081,China,3.Laboratory of National Development Center of Hi-Tech Green Materials,Beijing 100081,Chin

了不起的体育运动

奥运圣火已经点燃,全世界的优秀运动员正展开激然的角逐。在银屏前跟着欢呼呐喊的同时,也请你和我们一起探讨关于运动的话题。我们为什么要让孩子运动?运动可以给孩子带来什么?冠军教练如何看待冠军的培养?运动给优秀运动员们带来的人生改变是什么?儿童的体能训练都有哪些误区?幼儿园的冰雪运动课是如何开展的?</p

基于多重时空数据的新疆绿洲研究/Study of Xinjiang oasis with multitude of temporal and spatial data[J]

绿洲是在特定的气候、地貌、水文、土壤、植被、动物等因素相互作用以及人类活动共同影响下而形成的自然综合体.即是在干旱区或荒漠背景下,由自然及人类共同作用,有利于人类及其他生物生存,且生产力明显高于周边的地域.利用近期新疆地区地形、降水、植被、草地、土壤等空间数据,以及2010年度新疆地区土地利用数据,应用GIS软件进行综合空间分析,获取了新疆地区干旱荒漠及绿洲区域的界线.2010年度新疆绿洲面积约占全疆总面积的9.54％,包括了天然绿洲与人工绿洲,两部分面积几乎各占一半.新疆地区绿洲的土地利用类型包括了各类林地、中高覆盖度草地、除冰川和永久积雪地的各类水域,沼泽地、城镇工矿居民点建设用地,以及各类灌溉耕地