核磁共振技术测试不同性别大鼠尿液代谢物的研究

采用核磁共振波谱技术测试不同性别大鼠尿液代谢物,分析性别因素对大鼠尿液代谢成分的影响.大鼠尿液核磁共振氢谱（1HNMR谱）结果采用主成分分析（principal component analysis,PCA）和正交偏最小二乘判别分析（orthogonal to partial least squares discriminant analysis,OPLS-DA）方法分析,得到不同性别大鼠尿液中的差异性代谢物.PCA分析结果显示2组尿液代谢成分有明显的差异,进一步进行OPLS-DA分析可以判别出2组尿液中具有差异性的代谢物.结果显示,雌性大鼠尿液中的丙氨酸、缬氨酸、鸟氨酸等氨基酸类以及乙酸、硫胺、氨基马尿酸、苯乙胺、氧氨嘧啶等代谢物含量高于雄性大鼠,差异有统计学意义（p〈0.05）.雄性大鼠尿液中的甲胺、二甲胺、三甲胺、肌酸酐、尿囊素、延胡索酸、甲酸等代谢物则明显高于雌性大鼠,差异有统计学意义（p〈0.05）.性别因素对大鼠尿液中的代谢成分有一定的影响.     

柳兰花蜜腺的发育解剖学研究

柳兰花蜜腺杯状,贴生于凹形的花托内壁上,属花托蜜腺,它由分泌表皮,产蜜组织及亚腺组织构成,分泌表皮由一层细胞组成,具变态气孔,角质层薄。产蜜组织由１５￣２０层细胞组成,无维管束,但在其外侧的亚腺组织中有维管束,柳兰花蜜腺发育早期无特定的原始细胞,是由花托内周表面细胞特化而成的,在蜜腺发育过程中,蜜腺细胞内的液泡,淀粉粒有明显的动态变化,其变化与蜜汁的形成,分泌密切相关。     

油田石油管道油垢厚度测量的实验测量与模拟对比

用实际管道和油垢进行油垢的小角度散射测厚实验,并用MCNP程序在与实际实验相同的几何条件下进行模拟运算来观察在不同的小角度散射情况下,观察散射计数与油垢厚度之间的关系.结果表明:实验与模拟结果符合的良好,特别是在45°入射情况下,实验和模拟的结果中的R2基本上大于0.99,表明45°入射角对于垢厚和散射光子数之间的线性关系是个较好的选择.小角度法测垢是可行的.     

Limited Fraction of Crystallized Side Chains in Bottlebrush Poly(n-alkyl methacrylate)s

Crystallinity of bottlebrush polymers due to side chain crystallization has been considered to be related to the length of the side chains only under the assumption of complete participation of crystallization by all side chains.Recent experimental results revealed that in poly(n-alkyl methacrylate)s a fraction of side chains could not crystallize due to constraints imposed by the trapped main chain entanglements and required expansion of main chain-main chain distance.This result renders the or...     

Progress and Understanding on Catalysts with Well-defined Interface for Boosting CO2 Conversion

Catalytic conversion of CO₂ into valuable chemicals like CH₃OH is the most promising way to alleviate CO₂ emission for solving the serious climate change issue. Multi-component catalysts with well-defined interface show outstanding performance in CO₂ conversion due to the synergistic effects and multifunctional properties caused by the well-defined interface. A discharge technique, named as cold plasma, has been recognized as an excellent strategy for ...     

一种新的双正交小波的构造方法研究

在二进提升方案相关理论的基础上,结合双正交性、消失矩性和对称性条件,提出一种构造提升双正交小波的新方法.此方法从二进小波出发,考虑小波所具有的特性,通过选取适当的提升参数,具体构造了具有紧支撑、对称性、高阶消失矩和速降性的提升双正交小波.     

DISPERSION AND TENSILE BEHAVIOR OF POLYPROPYLENE/MONTMORILLONITE NANOCOMPOSITES PRODUCED VIA MELT INTERCALATION

Most of the anicles on polymer nanocomposites focus on the importance of chemistry used to modify the surfaceof the clay, usually montmorillonite (MMT), and characterization of the nano-scale structure obtained. The role andimportance of processing were also discussed recently. However, few papers concerning the correlation between morphologyof MMT and mechanical properties were published. In order to understand the tensile behavior of PP/Montmorillonite(MMT) nanocomposites better, and to further improve the reinforcement efficiency, we first prepared the PP nanocompositesvia direct melt intercalation using conventional twin-screw extrusion. The dispersion and tensile property of the compositeswere then investigated by SEM, XRD, TEM and a video-controlled tensile set-up. The macroscopic and microscopicdispersion of MMT in PP matrix was verified by XRD and TEM, combined with SEM. The tensile properties were obtainedby video-controlled tensile set-up, which gives true stress-strain curve. It was found that a partly intercalated and partlyexfoliated structure (also called incomplete exfoliation) existed in the system. Though the tensile strength of PPnanocomposites is not much improved in engineering stress-strain curves, more than 20% increase of true stress was found ina true stress-strain experiment at high true strain, which indicates that only oriented silicate layers can have a big effect ontensile properties. Not only orientation of silicate platelets but also the degree of exfoliation is a key factor to determine thereinforcement efficiency. The reinforcement efficiency of MMT has been discussed based on the "continuum" Halpin-Tsaiequations. A good agreement was found between experimental data and theoretical prediction by changing N value (number of platelets per stack) which corresponding to different state of the dispersion of MMT in PP matrix.     

超临界水转化低成熟富有机质页岩生烃特性实验研究

本文采用非等温加热反应器模拟了低成熟富有机质页岩在400℃、25 MPa超临界水中2～12 h范围内的生烃过程。结果表明转化后的产物在油气水中均有分布。在2～12 h范围内,有机碳动用程度随时间的增加逐渐升高,在12 h时可达30%以上。产油率随时间的增加先增后减,在4 h时达到最大值22.11 kg(油)·t^-1(页岩)。产气率随时间的增加逐渐升高,在12 h时达到最大值32.88 m³(气)·t^-1(页岩)。产油中的饱和烃和芳香烃总含量始终大于80%,随着反应时间的延长,产气中甲烷、乙烷和氢气的选择性增强,水溶性有机物含量先增后减,在反应时长8 h时水TOC达到峰值259.98 mg·L^-1。超临界水还能够有效脱除低成熟富有机质页岩中的黄铁矿,并促进页岩内部的介孔和大孔发育。     

彝语广播翻译之我见

彝语广播翻译工作是进行再一次创作的一项工作,在翻译的过程中不仅需要编辑稿件,还要阅读思考、增删加减、润饰完善.本人从事20多年的彝语广播翻译,认为广播稿翻译应追求最佳听觉效应,尽量做到口语化和通俗化,使播者顺口,听着顺耳.     

Fragmentation of protonated ions of peptides containing cysteine,cysteine sulfinic acid,and cysteine sulfonic acid

The oxidation of the sulfhydryl group in cysteine to sulfenic acid, sulfinic acid, and sulfonic acid in proteins is important in a number of enzymatic processes. In this study we examined the fragmentation of four peptides containing cysteine, cysteine sulfinic acid (Cys-SO(2)H), and cysteine sulfonic acid (Cys-SO(3)H) in an ion-trap mass spectrometer. Our results show that the presence of a Cys-SO(2)H in a peptide leads to preferential cleavage of the amide bond at the C-terminal side of the oxidized cysteine residue. The results are important for the determination of the site of the cysteine oxidation and might be useful for the sequencing of cysteine-containing peptides.