沉积物与悬浮物中磷分级分离形态差异的初步研究

以滇池2个典型的严重富营养化湖湾———马村湾和海东湾为研究区域,研究分析了2个湖湾沉积物及水体悬浮物中4种磷的赋存形态:松散吸附态磷(NH4Cl-P)、氧化还原敏感态磷(BD-P)、金属结合态磷(NaOH-P)和钙结合态磷(HCl-P)以及有机质含量及总磷(TP)含量.结果表明:沉积物随着风浪搅动悬浮进入水体后,4种形态的磷含量及其所占总磷的比例均发生了较大变化,NH4Cl-P的含量升高,是由于快速的吸附作用所致;NaOH-P在4种磷形态中的比例下降,含量上升,表明沉积物再悬浮进入水体后磷的活化特性加大,

转入生长激素基因红鲤F_2代阳性鱼的摄食及代谢研究

<正>生长激素(GH)是由中腺垂体分泌的多功能激素,对动物生长的促进效应已无可置疑.将冠以小鼠重金属螯合蛋白(MT-1)基因启动顺序的人生长激素(hGH)基因重组质粒pMThGH显微注射到红鲫(Carassius auratus auratus)和泥鳅(Misgurnus anguillicaudatus)的受精卵内,获得了第一批转基因鱼,并进一步证实了转移基因的整合、表达、传代及转GH基因鱼的快速生长效应.由于鱼类自然群体中也存在个别的快速生长个体,对转GH基因鱼快速生

Independent Transport and Sorting of Functionally Distinct Protein Families in Tetrahymena thermophila Dense Core Secretory Granules

Dense core granules (DCGs) in Tetrahymena thermophila contain two protein classes. Proteins in the first class, called granule lattice (Grl), coassemble to form a crystalline lattice within the granule lumen. Lattice expansion acts as a propulsive mechanism during DCG release, and Grl proteins are essential for efficient exocytosis. The second protein class, defined by a C-terminal beta/gamma-crystallin domain, is poorly understood. Here, we have analyzed the function and sorting of Grt1p (granule tip), which was previously identified as an abundant protein in this family. Cells lacking all copies of GRT1, together with the closely related GRT2, accumulate wild-type levels of docked DCGs. Unlike cells disrupted in any of the major GRL genes, Delta GRT1 Delta GRT2 cells show no defect in secretion, indicating that neither exocytic fusion nor core expansion depends on GRT1. These results suggest that Grl protein sorting to DCGs is independent of Grt proteins. Consistent with this, the granule core lattice in Delta GRT1 Delta GRT2 cells appears identical to that in wild-type cells by electron microscopy, and the only biochemical component visibly absent is Grt1p itself. Moreover, gel filtration showed that Grl and Grt proteins in cell homogenates exist in nonoverlapping complexes, and affinity-isolated Grt1p complexes do not contain Grl proteins. These data demonstrate that two major classes of proteins in Tetrahymena DCGs are likely to be independently transported during DCG biosynthesis and play distinct roles in granule function. The role of Grt1p may primarily be postexocytic; consistent with this idea, DCG contents from Delta GRT1 Delta GRT2 cells appear less adhesive than those from the wild type.

Investigation of high cycle and Very-High-Cycle Fatigue behaviors for a structural steel with smooth and notched specimens

The high cycle and Very-High-Cycle Fatigue (VHCF) properties of a structural steel with smooth and notched specimens were studied by employing a rotary bending machine with frequency of 52.5 Hz. For smooth specimens, VHCF failure did occur at fatigue cycles of 7.1 x 10(8) with the related S-N curve of stepwise tendency. Scanning Electron Microscopy (SEM) was used for the observations of the fracture surfaces It shows that for smooth specimens the crack origination is surface mode in the failure regime of less than 10(7) cycles While at VHCF regime, the material failed from the nonmetallic inclusion lies in the interior of material, leading to the formation of fisheye pattern. The dimensions of crack initiation region were measured and discussed with respect to the number of cycles to failure. The mechanism analysis by means of low temperature fracture technique shows that the nonmetallic inclusion in the interior of specimen tends to debond from surrounding matrix and form a crack. The crack propagates and results to the final failure. The stress intensity factor and fatigue strength were calculated to investigate the crack initiation properties. VHCF study on the notched specimens shows that the obtained S-N curve decreases continuously. SEM analysis reveals that multiple crack origins are dominant on specimen surface and that fatigue crack tends to initiate from the surface of the specimen. Based on the fatigue tests and observations, a model of crack initiation was used to describe the transition of fatigue initiation site from subsurface to surface for smooth and notched specimens. The model reveals the influences of load, grain size, inclusion size and surface notch on the crack initiation transition. (C) 2010 Elsevier Ltd. All rights reserved

同位旋非对称核物质状态方程

为了确定同位旋非对称核物质状态方程,利用同位旋有关的量子分子动力学理论计算和寻找实验上对于中能重离子碰撞中核子-核子碰撞截面或者对称势非常灵敏的物理观测量——探针.结果发现了几种分别对于核子-核子碰撞截面或者对称势非常灵敏的物理观测量.并对这些探针的机理进行了仔细研究,对以上研究结果进行小结和讨论,并为今后继续深入研究工作提出展望.

Ar~+和He~+离子与C_(60)碰撞后富勒希离子的激发机制

C60 在与重离子作用下的激发机制与入射离子能量、质量及电荷态有关。核阻止主要出现在低能重离子与C60 的碰撞中 ;而高能轻离子作用下 ,电子阻止迅速增强 ,成为主要的激发方式。本文中直接观察到由弹性碰撞引起的C+ 峰 ,及其丰度依赖于入射离子的质量。同时我们还发现电子阻止随入射离子能量 (7～ 2 0keV)增大相应增加 ,这与绝热量子分子动力学计算的结果一致。