Optimization on the Work Output,Efficiency and Other Performance Parameters of an Irreversible Diesel Heat Engine

建立不可逆狄塞尔热机循环新模型,探索不可逆绝热过程对热机循环性能的影响,应用有限时间热力学方法,导出了输出功和效率与压力比、高低温比间的解析表式,揭示了这些重要热力学参量间的变化特性.研究结果表明,随着绝热不可逆程度的增大,输出功及效率均明显减小;输出功和效率随压力比的变化在一定范围内存在极大值,而输出功随高低温比的增大而单调增大.通过数值计算,还讨论了包括热机压力比、输出功和效率等优化工作区域及其界限.所得结论可为一类内燃机的最佳运行条件和优化设计提供理论参考.A new cyclic model of irreversible Diesel heat engine is proposed.The influence of irreversible adiabatic processes on the cyclic performance of the engine is explored.By using the method of finite time thermodynamics,the relations among the work output,efficiency and the pressure ratio,high-low temperature ratio are derived and the characteristics of these important thermodynamic parameters are revealed.It is shown that as the adiabatic irreversibility increases,the work output and efficiency significantly decrease and the work output and efficiency have their extremal values for the pressure ratio in some region,but the work output is monotonic increasing function of the high-low temperature ratio.By means of numerical calculation,the optimal operating ranges and bounds of the pressure ratio,work output,efficiency for the engine are further analyzed and discussed.The conclusions obtained here may provide some theoretical guidance for the optimal operating condition and the optimal design of a class of internal combustion engines.华南理工大学科研基金资

High-Throughput Assessment of Mitochondrial Fluorescence Labeling at Single-Particle Level

线粒体是真核细胞能量代谢和信号转导的调控中枢,虽然各种灵敏、特异的线粒体荧光标记技术已经被广泛应用于线粒体研究,但仍缺乏单线粒体水平的荧光染色性能评估方法。基于超高灵敏流式检测技术(High sensitivity flow cytometry,HSFCM)能对单个线粒体进行高灵敏、高通量、多参数定量分析的独特优势,本研究发展了一种单线粒体水平的荧光标记高通量评估方法。将携带靶向线粒体绿色荧光蛋白基因的p Ac GFP1-Mito质粒转染至人宫颈癌He La细胞中,用G418筛选出稳定转染细胞,分别从瞬时转染和稳定转染的细胞中提取线粒体。此外,从未转染质粒的正常He La细胞中提取线粒体,分别进行Mito Tracker Green标记以及SYTO 62线粒体DNA染色,应用实验室自行研制的超高灵敏流式检测装置在单线粒体水平对这4种线粒体标记方法的荧光亮度、标记效率和稳定性进行评估。实验结果表明,稳定转染细胞中单个线粒体的绿色荧光蛋白(GFP)荧光亮度为瞬时转染的17.7倍,比Mito Tracker Green标记的线粒体亮度高约两个数量级,且标记稳定性好。本研究为线粒体标记方法的选择提供了一种先进的分析方法。Mitochondria play a central role in the regulation of energy metabolism and signal transduction in eukaryotic cells. Although many fluorescent labeling strategies have been developed for mitochondrial studies,the methods that enable labeling efficiency assessment at the single-mitochondrion level are still lacking. By employing the unique advantages of high sensitivity flow cytometry( HSFCM) in the sensitive,rapid,and quantitative multiparameter analysis of individual mitochondria,here we examined the performance of several different mitochondrial labeling strategies from the perspectives of brightness,labeling ratio,and stability.Mitochondria isolated from He La cells transfected with p Ac GFP1-Mito plasmid upon transient or stable transfections,and mitochondria directly labeled with Mito Tracker Green or SYTO 62 were analyzed by a laboratory-built three-channel HSFCM. Upon the quantitative measurement of fluorescence brightness,it was found that the fluorescence intensity of green fluorescent protein( GFP) in mitochondria isolated from cells with stable transfection was about 17. 7-fold higher than the transient transfection ones,and was approximately two orders of magnitude brighter than mitochondria labeled with Mito Tracker Green. On the other hand,the fluorescence signal of SYTO 62 labeling decreased upon washing,indicating its rapid dissociation rate. The strong fluorescence intensity and good labeling stability make stable transfection an efficient method to label mitochondria. The experimental results demonstrates that HSFCM provides a powerful analytical tool to assess the performance of mitochondrial fluorescence labeling via high throughput single mitochondria analysis.国家自然科学基金项目(Nos.91313302,90913015,21225523)资助~

Activated carbongraphene composites with high-rate performance as electrode materials for electrochemical capacitors

Activated carbongraphene composites with high-rate performance as electrode materials for electrochemical capacitor

Catalytic site of nitrogenases and its chemical simulations

固氮酶是固氮微生物在常温常压下固氮成氨的催化剂,其催化机理和化学模拟一直是国际上长期致力研究的对象.钼铁蛋白高分辨1.0单晶X射线衍射分析表明,固氮酶催化活性中心铁钼辅基的结构为MO fE7S9C(r-HOMOCIT),其中,MO原子和3个u2-硫配体、1个组氨酸和1个高柠檬酸配位,形成八面体构型.高柠檬酸以α-烷氧基氧和α-羧基氧与钼螯合形成双齿配位,氨基酸残基上的组氨酸咪唑氮和半胱氨酸巯基与钼和铁单齿配位.在固氮酶铁钼辅基的生物合成过程中,高柠檬酸和咪唑侧基是在最后的合成步骤插入铁硫碳簇前驱体中,其中高柠檬酸和咪唑侧基有可能对质子传递以及稳定MO fE7S9C簇起到重要作用.本文从固氮酶铁钼辅基结构出发,结合最近本课题组从化学模拟出发,将固氮酶催化活性中心铁钼辅基结构修订为加氢新结构MO fE7S9C(r-HHOMOCIT)的研究,着重介绍了近年来国内外固氮酶活性中心、生物合成和催化作用机理的研究进展,并展望了固氮酶的研究前景.Nitrogenase catalyzes the reduction of dinitrogen to ammonia in the process of biological nitrogen fixation.In the past few decades, its catalytic mechanism and chemical simulation have been widely studied.The high resolution X-ray structural analysis of the Mo Fe protein in nitrogenase reveals the iron molybdenum cofactor(Fe Mo-co) as a cage structure, Mo Fe7S9C(R-homocit).The molybdenum atom is coordinated by three sulfur atoms, a nitrogen atom from histidine residue and two oxygen atoms from R-homocitrate.Recently, the model has been modified as a protonated structure of Mo Fe7S9C(R-Hhomocit).Homocitrate and imidazole sidechain may play important roles in delivering proton and stabilizing the Mo Fe7S9C cluster in the process of N2 reduction.However the mechanism of N2 reduction remains unclear.In this review, the chemistry of molybdenum with homocitrate and imidazole is discussed, including the iron molybdenum sulfur complexes, which will be helpful to understand the coordination environment of molybdenum atom in iron molybdenum cofactor.国家重点基础研究发展计划(2010CB126504); 国家自然科学基金(21073150)资

用于生命之树重建的数据集

由中国科学院计算机网络信息中心、中国科学院植物研究所、深圳市中国科学院仙湖植物园"三方两地"共同合作研究建设的"达尔文树"——分子数据分析应用环境(DarwinTree——Molecular Data Analysis and Application Environment),从中国陆地植物发育系统框架的研究出发,逐步推动解决生命之树构建过程中存在的技术难题,探索利用基因和基因组信息构建生命之树的策略和方法,研究和开发DNA序列信息自动采集和生命之树自动生成技术(Automatic Reconstruction of The Tree of Life),建立生命之树信息平台及其利用体系,为最终在我国建立具有国际影响的,能很好地兼容物种分类、地理分布、形态性状、化石信息以及DNA信息的物种库(Species Bank)创造条件。DarwinTree旨在为科研人员提供数据和分析并举的工作平台,该平台将承担数据汇集和面向实际科研工作应用的双重作用。本文发布的数据集包括:(1)DarwinTree基础数据集:来自国际公共序列数据的标记处理得到的分子标记数据及其与任意阶元物种分类名称对应的统计数据集;(2)DarwinTree自测序数据集:面向中国陆地植物研究的补充测序序列数据;(3)DarwinTree中国维管植物进化数据集:已构建的中国维管植物属系统发育树的数据(Generic tree of Chinese vascular plants)