聚氧乙烯醚和聚羧酸盐复配体系在430 g·L-1戊唑醇水悬浮剂中的应用

研究了聚羧酸盐分散剂SD-840和聚氧乙烯醚分散剂601P的复配体系对430 g·L~(-1)戊唑醇水悬浮剂(SC)悬浮稳定性的影响.通过测定不同戊唑醇SC热贮前后各样品的粒径大小、Zeta电势、黏度、悬浮率的变化,发现与单独使用SD-840,601P相比,两者的复配体系制备的430 g·L~(-1)戊唑醇SC稳定性能好,尤其在SD-840和601P质量比为m(SD-840):m(601P)=0.75体系中,水悬浮剂稳定性能最佳,热贮前后的粒径和悬浮率变化最小,热贮前后粒径分布D90分别为2.35μm和2.50μm,悬浮率热贮前后分别为99.47%和96.58%.     

皖北地区楚汉文化传承与地域化建筑特色设计研究

文化是一个国家和民族的灵魂,继承和弘扬优秀传统文化,挖掘和丰富建筑的文化内涵是体现城市地域化特色的重要部分。楚汉文化是中国传统文化艺术的重要源头之一,在历史发展中不断地被继承和转化。本文结合安徽北部作为楚汉文化之一的历史背景,通过研究楚汉文化特色,试图提炼楚汉文化中最具特色的部分经过抽象和提高,将楚汉艺术与现代化建筑设计相融合,以启发当前建筑设计中体现楚汉风格地域特色形式美的建设需求。     

Large-scale vortex lattice emerging from collectively moving microtubules

Spontaneous collective motion, as in some flocks of bird and schools of fish, is an example of an emergent phenomenon. Such phenomena are at present of great interest and physicists have put forward a number of theoretical results that so far lack experimental verification. In animal behaviour studies, large-scale data collection is now technologically possible, but data are still scarce and arise from observations rather than controlled experiments. Multicellular biological systems, such as bacterial colonies or tissues, allow more control, but may have many hidden variables and interactions, hindering proper tests of theoretical ideas. However, in systems on the subcellular scale such tests may be possible, particularly in in vitro experiments with only few purified components. Motility assays, in which protein filaments are driven by molecular motors grafted to a substrate in the presence of ATP, can show collective motion for high densities of motors and attached filaments. This was demonstrated recently for the actomyosin system, but a complete understanding of the mechanisms at work is still lacking. Here we report experiments in which microtubules are propelled by surface-bound dyneins. In this system it is possible to study the local interaction: we find that colliding microtubules align with each other with high probability. At high densities, this alignment results in self-organization of the microtubules, which are on average 15?μm long, into vortices with diameters of around 400?μm. Inside the vortices, the microtubules circulate both clockwise and anticlockwise. On longer timescales, the vortices form a lattice structure. The emergence of these structures, as verified by a mathematical model, is the result of the smooth, reptation-like motion of single microtubules in combination with local interactions (the nematic alignment due to collisions)--there is no need for long-range interactions. Apart from its potential relevance to cortical arrays in plant cells and other biological situations, our study provides evidence for the existence of previously unsuspected universality classes of collective motion phenomena.     

正交晶系DyF_3，HCF_3和YbF_3的电学性质

正交晶系ＤｙＦ＿３，ＨｏＦ＿３和ＹｂＦ＿３的电学性质吴明　，罗裕基，任玉芳，苏锵（中山大学化学系，广州５１０２７５）（中国科学院长春应用化学研究所）关键词α—ＹＦ３结构的氟化物，电导性能分类号（）４７２．４，《）６１４．３３氟调澜矿型结构的典型化合物...     

丁二酸氧钒和己二酸氧钒的热分解反应及V_4C_3催化活性研究

研究了丁二酸氧钒和己二酸氧钒在Ar气氛下的热分解反应。求出了二酸氧钒的热分解反应表观动力学参数n-1.82,E=367.1kJ/mol,logZ=24.25;已二酸氧钒的n=1.06,E=242.9kJ/mol,logZ=15.61。在微型催化床上研究,证明热分解产物V_4C_3对N_2O和NO的热分解具有明显的催化活性。     

关于一类图的优美性

将齿轮图的每个齿的顶端点与ｍ个孤立点相连后所得的图称为ｎ顶边星图，文［３］猜想，所有的ｎ顶边星图都是优美图，本文证明了这一猜想是正确的．     

基于ＡＱＷＡ 的带支腿浮式结构的水动力特性分析

在利用有限元软件计算带支腿浮式结构水动力响应时,为了分析网格尺寸对结构水动力特性计算结果的影响,根据势流理论及波浪的辐射/衍射理论,对某带支腿浮式结构的桩腿收起时的水动力响应进行了分析,并运用数值计算软件AQWA对其进行仿真计算,得到采用不同网格尺寸计算时,浮式结构各自由度附加质量、附加阻尼、不同入射角的波浪作用下的波浪激励力及幅值响应算子随波浪频率的变化曲线。数值计算结果表明,网格尺寸对结构附加质量、附加阻尼有一定的影响,对波浪激励力的影响较小,对结构的幅值响应算子影响不大。     

Cryptomare magmatism 4.35 Gyr ago recorded in lunar meteorite Kalahari 009

The origin and evolution of the Moon remain controversial, with one of the most important questions for lunar evolution being the timing and duration of basaltic (mare) magmatism. Here we report the result of ion microprobe U-Pb dating of phosphates in a lunar meteorite, Kalahari 009, which is classified as a very-low-Ti mare-basalt breccia. In situ analyses of five phosphate grains, associated with basaltic clasts, give an age of 4.35 +/- 0.15 billion years. These ancient phosphate ages are thought to represent the crystallization ages of parental basalt magma, making Kalahari 009 one of the oldest known mare basalts. We suggest that mare basalt volcanism on the Moon started as early as 4.35 Gyr ago, relatively soon after its formation and differentiation, and preceding the bulk of lunar volcanism which ensued after the late heavy bombardment around 3.8-3.9 Gyr (refs 7 and 8). Considering the extremely low abundances of incompatible elements such as thorium and the rare earth elements in Kalahari 009 (ref. 9) and recent remote-sensing observations illustrating that the cryptomaria tend to be of very-low-Ti basalt type, we conclude that Kalahari 009 is our first sample of a very-low-Ti cryptomare from the Moon.     

Histone demethylase JHDM2A is critical for Tnp1 and Prm1 transcription and spermatogenesis

Recent studies indicate that, similar to other covalent modifications, histone lysine methylation is subject to enzyme-catalysed reversion. So far, LSD1 (also known as AOF2) and the jumonji C (JmjC)-domain-containing proteins have been shown to possess histone demethylase activity. LSD1 catalyses removal of H3K4me2/H3K4me1 through a flavin-adenine-dinucleotide-dependent oxidation reaction. In contrast, JmjC-domain-containing proteins remove methyl groups from histones through a hydroxylation reaction that requires alpha-ketoglutarate and Fe(II) as cofactors. Although an increasing number of histone demethylases have been identified and biochemically characterized, their biological functions, particularly in the context of an animal model, are poorly characterized. Here we use a loss-of-function approach to demonstrate that the mouse H3K9me2/1-specific demethylase JHDM2A (JmjC-domain-containing histone demethylase 2A, also known as JMJD1A) is essential for spermatogenesis. We show that Jhdm2a-deficient mice exhibit post-meiotic chromatin condensation defects, and that JHDM2A directly binds to and controls the expression of transition nuclear protein 1 (Tnp1) and protamine 1 (Prm1) genes, the products of which are required for packaging and condensation of sperm chromatin. Thus, our work uncovers a role for JHDM2A in spermatogenesis and reveals transition nuclear protein and protamine genes as direct targets of JHDM2A.