26 resultados para D. N. P. S. F.-Correspondència
em Chinese Academy of Sciences Institutional Repositories Grid Portal
Resumo:
We introduce a conceptual model for the in-plane physics of an earthquake fault. The model employs cellular automaton techniques to simulate tectonic loading, earthquake rupture, and strain redistribution. The impact of a hypothetical crustal elastodynamic Green's function is approximated by a long-range strain redistribution law with a r(-p) dependance. We investigate the influence of the effective elastodynamic interaction range upon the dynamical behaviour of the model by conducting experiments with different values of the exponent (p). The results indicate that this model has two distinct, stable modes of behaviour. The first mode produces a characteristic earthquake distribution with moderate to large events preceeded by an interval of time in which the rate of energy release accelerates. A correlation function analysis reveals that accelerating sequences are associated with a systematic, global evolution of strain energy correlations within the system. The second stable mode produces Gutenberg-Richter statistics, with near-linear energy release and no significant global correlation evolution. A model with effectively short-range interactions preferentially displays Gutenberg-Richter behaviour. However, models with long-range interactions appear to switch between the characteristic and GR modes. As the range of elastodynamic interactions is increased, characteristic behaviour begins to dominate GR behaviour. These models demonstrate that evolution of strain energy correlations may occur within systems with a fixed elastodynamic interaction range. Supposing that similar mode-switching dynamical behaviour occurs within earthquake faults then intermediate-term forecasting of large earthquakes may be feasible for some earthquakes but not for others, in alignment with certain empirical seismological observations. Further numerical investigation of dynamical models of this type may lead to advances in earthquake forecasting research and theoretical seismology.
Resumo:
本文对CSM-GRP间剪切断裂用实验与分析方法进行了研究。用英国标准BS4994规定的双槽试件拉剪法测量了层间剪切强度(ILSS)。用有限元法计算了应力分布、损伤扩展和复合型应力强度因子。并讨论了BS4994规定的这一试验方法的可靠性。
Resumo:
研究了L-α-磷脂酰乙醇胺分子(PE)与去污剂分子摩尔数之比Rm(P)/m(D)对磷脂分子在固体硅片表面自组装成膜的影响。通过椭偏技术测定磷脂膜层厚度,结合磷脂膜层表面疏水角的变化、磷脂分子头部亲水、尾部疏水的性质及与蛋白质分子的作用条件,得到:随着Rm(P)/m(D)在PE溶液中的增大,PE膜层在硅基片上的存在形式由单层向双层逐渐过渡。当对硝基苯酯基-聚乙二醇-(1,2-双油酰基-3-甘油磷脂乙醇胺)分子(pNP-PEG-DOPE)与已固定的PE分子反应时,分子间形成双层膜的机制也从pNP-PEG-DOPE与单层PE分子膜层的直接吸附逐渐过渡到取代上层PE分子并与下层PE分子吸附形成双层膜。
Resumo:
利用高重频YAG激光作用在固体表面所产生的等离子体使工件和电极之间在大气环境中并且电压远低于击穿闭值的条件下产生可控定向放电。实验结果显示,放电坑基本上呈火山坑形,既有单坑结构,也有多坑结构,其形貌受到放电波形、电源极性、放电介质等因素的影响。放电坑表面形貌的规律是:①除了涂油时的阳极放电坑是单坑结构以外,其他条件下的放电坑都是复合多坑结构;②单坑结构呈火山坑形,坑底为圆弧形,熔凝物堆积在坑的边缘,而多坑结构则是一个大的放电坑中有多个凸起的尖峰,这种结构有利于毛化加工。研究表明,对于碳钢、铸铁、黄铜三种材料,放电坑直径d电源参数的关系可以表示成:dIαp对于三角波),或dΥβ(对于矩形波)。α的范围在0.40~0.71,β的范围在0.23~0.47。在工件表面涂油,有利于提高放电的能量密度,使放电坑变深。介质的密度和粘性系数可作为控制放电通道扩展的有效因素。放电能量一定时,有固态相变材料的相变区深度的变化遵从以下规律:①放电波形和电源极性一定时,涂油时的深度>大气时的深度;②极性和介质一定时,矩形波时的深度≥三角波时的深度;③介质和波形一定时,阳极时的深度≥阴极时的深度。与一般的研究电极损耗即放电前后电极的质量差所不同的是,认为在激光诱导放电毛化技术中,对工件电极应该研究放电的侵蚀作用,即实验上可观测到的能量作用的范围所对应的体积V,它不仅包括脱落下来的那部分物质,也包括发生了组织变化的那部分物质。对于有固态相变的材料,V通常就是相变区边界所对应的球冠体积;对于无固态相变的材料,V通常是放电坑的体积。通过量纲分析,揭示出V是一个多元函数。当电极材料和放电介质一定时,对于电流峰值一定的矩形波放电,v主要取决于脉冲宽度γ,其函数关系为:V=K1·Υ1.41~1.45;对于脉冲宽度一定的三角波放电,V主要取决于电流峰值IPV=K2·I1.30~2.15PK1、K2为与材料和放电介质有关的常量。在比较分析了脉冲激光束与激光诱导放电在功率密度、作用时间和坑的深度等方面对材料的影响之后,认为:高重频激光束适合于对材料表面进行薄层熔凝和毛化,低重频长脉冲激光束适合于对材料进行表面改性处理,而激光诱导放电具有对材料表面进行造型强化和组织强化的双重作用。设计了一种转动式圆盘电极,延长了工具电极的连续工作时间。
Resumo:
(100 - x)TeO2 - xNb(2)O(5) (x=5-20) mobic tellurite glasses doped with 0.5 mol.% Er2O3 were synthesized, and their thermal, mechanical, and spectroscopic properties were measured and compared to the properties of the typical 75TeO(2)-20ZnO-5Na(2)O (TZN) tellurite glass. The refractive index (n(d)), density (p), and glass transition temperature (T-g) of bulk glasses increase with the Nb2O5 content. The Vickers microhardness (H-v) of bulk glass in niobic tellurite glasses also increases with the Nb2O5 content. The values (2.5-3.2 GPa) of H, in the niobic tellurite glasses are 47-88% larger than that (1.7 GPa) in TZN glass. The effect of Nb2O5 content on absorption spectra, the Judd-Ofelt parameters Omega(t) (t = 2, 4, 6), fluorescence spectra and the lifetimes of Er3+ :I-13/2 level were also investigated, and the stimulated emission crosssection was calculated from McCumber theory. With increasing Nb2O5 content in the glass composition, the Omega(t) (t = 2, 4, 6) parameters, fluorescence full width at half maximum (FWHM) Of I-13/2 of Er3+ increase, while the I-4(13/2) lifetimes of Er3+ decreases. Compared with TZN glass, the gain bandwidth properties of Er3+-doped TeO2-Nb2O5 glass is much larger than in tellurite glass based TeO2-ZnO-Na2O system, bismush-based glass, germanate, and silicate glasses, which indicates that TeO2-Nb2O5 glasses are better choice as a practical available host material for broadband Er3+-doped amplifier. (c) 2005 Elsevier B.V. All rights reserved.
Resumo:
基于PFU微型生物群落参数调查数据,对湖北省汉江两条污染带11个站点和湖南常德市水系15个站点所属水质组别进行了综合分析研究.所得典型鉴别函数能够对水质组别作出有效的鉴别,分类函数对站点的水质组别分类正确率达到96%;群落参数对化学综合污染指数(P)的响应不呈简单的线性关系,群落参数的变化存在一定模式.提出了“转折区”(turninginterval)概念.水质由洁净到严重污染的变化过程中,在转折区内,微型生物群落的5个参数与P相关性将发生根本性改变:DSeq与P正相关转变为负相关,T90%由负相关
Resumo:
The seasonal population dynamics and maturation cycle of the nematode Camallanus cotti in the posterior intestine of Chinese hooksnout carp Opsariichthys bidens have been studied in the Danjiangkou Reservoir of the Hubei Province in central China from September 2004 to November, 2005. The overall prevalence, mean abundance and intensity of C cotti among fish sampled (n = 700 fish) were 47%, 2.29 +/- 12.38 ( +/- S.D.) and 1-307 (average 4.89 +/- 17.74), respectively. The overall sexual ratio of female to male nematodes (excluding L3 and L4 juveniles) was 1.17:1. Statistical results showed weakly positive correlations betweerl fish length and the number of nematodes per host. The dynamics of infection of the nematode exhibited significant seasonal pattern in changes in mean abundance. A similar pattern was found for changes in nematode prevalence, although this was not statistically significant. Higher levels of infection were observed among fish sampled in summer months and the lower in the winter. Neither the prevalence nor the abundance of the parasite was significantly different between male and female hosts. The pattern of frequency distribution of the parasite in the host was found to be over-dispersed throughout the sampling period. In addition, studies on the development and maturation of the parasite in O. bidens revealed that development (maturation), recruitment of the next generation, and reproduction may be continuous year-round, although reproduction may peak during the winter. (c) 2007 Elsevier B.V. All rights reserved.
Resumo:
Mature female and male zebrafish were separated and exposed to nonylphenol (NP) at 0.1, 1, 10, 50, 100 and 500 mu g/L, respectively, for 3 weeks. Gonadosomatic index (GSI) in both sexes and vitellogenin (VTG) induction in males was measured as the bioindicators for the impairment to the parents. The results indicated that 50 mu g/L of NP was the non-observed effect concentration (NOEC) for GSI and VTG induction. Afterwards, the 50 mu g/L NP exposed females and males, and the control females and males were cross-wise pair-bred in the control water for one week to examine the reproductive effects. The embryonic cathepsin D (CAT D) activity, eggshell thickness, fecundity, hatching rate and malformation (vertebral column flexure) rate of offspring were determined in the four pair-bred groups. While endpoints remained unchanged in the groups with exposed males, prenatal exposure of females to 50 mu g/L of NP resulted in the impairment of reproduction in groups with exposed females including inhibition of CAT D activity (P < 0.05), decrease of eggshell thickness (by 23.6%) and elevation of malformation rate (P < 0.001). These results suggested NP could induce reproductive damage to zebrafish at NOEC for parents. The results also imply that alterations of CAT D activity and eggshell thickness may be more sensitive biomarkers to indicate the reproductive effects caused by endocrine disrupting chemicals. (c) 2005 Elsevier Inc. All rights is reserved.
Resumo:
本论文的研究方向是通过密度泛函理论研究各种材料的物理化学性质。近年来相关理论和数值算法的飞速发展,使得基于密度泛函理论的第一性原理方法成为凝聚态物理、量子化学和材料科学中的常规计算研究手段。本论文对无机材料进行第一性原理研究,研究涉及材料物性包括几何构型、电子结构、磁性能、和力学性质等等。 第一章简要地介绍了密度泛函理论的基本框架和近年来的理论发展。密度泛函理论的发展以及寻找合适的交换相关能量泛函为主线。从最初的局域密度近似(LDA)、广义梯度近似(GGA)到现在的非局域泛函、自相互作用修正,多种泛函形式的出现使得密度泛函理论可以提供越来越精确的计算结果。除了改进交换相关泛函,近年来密度泛函理论向动力学平均场和含时理论等方面扩展也很活跃。这些扩展式的密度泛函理论的应用领域不断扩大。在本章的最后,我们介绍一些密度泛函理论的应用程序。 第二章我们通过第一性原理从头算系统的研究了5d渡金属二硼化物TMB2 (TM = Hf, Ta, W, Re, Os and Ir, Pt)在假想的Pmmn间群中的结合能、生成焓、力学常数和电子能带结构。我们的计算结果表明在力学常数和价电子浓度之间存在一种关系:即当价电子浓度在6.8到7.2之间时,体模量和剪切模量达到最大值。再者,这种力学常数与价电子浓度之间的关系可以通过电子能带结构分析,如费米面附近价电子的占据情况,决定了体系的结合能和力学性能。最大的体模量和剪切模量的获得归因于TM d-B p键态的几乎完全占据和反键态的未占据。依据上述这种关系,我们预测了在正交结构OsB2合金化W和Re将比合金化Ir元素更容易和更硬。事实上,我们的进一步计算证实了我们的期望。 通过第一性原理计算研究了ReB2和WB2的结构、弹性力学,和电子性质。计算结果表明:ReB2的平衡态结构参数和报导的实验结构一致。在常温常压下,WB2在P63/mmc空间群比在P6/mmm更稳定。依据我们计算的多晶聚集体的体模量、剪切模量,ReB2和WB2可以被看作是具有前景的低压缩率和硬材料。再者,化合物的力学各项异性通过计算得到的弹性力学常数来详细的分析讨论。态密度和电子密度分析揭示过渡金属和硼原子之间的共价键是材料具有高的体模量、剪切模量和小的Poisson率的原因。 第四章,采用WIEN2k程序包中的缀加平面波+局域轨道方法的第一性原理计算,研究了层状钙钛矿化合物Cs2AgF4的结构、电子结构和磁性等性质。我们的计算结果表明Cs2AgF4的基态为正交相,能量比四方相低。我们同时发现Cs2AgF4应该表现出一种强的二维铁磁性,铁磁层之间为弱的反铁磁性耦合,这一结果与实验观察相一致。更主要的是,通过分析态密度图和自旋电子密度等密度面的分析,可以清楚地看出体系中存在 和 轨道的反铁电弹性有序现象。 第五章中,采用WIEN2k程序包中的缀加平面波+局域轨道方法的第一性原理计算,研究了YBaFe2O5的晶体结构、电子和磁性等方面的物理性能,特别是有关电荷和轨道有序的情况。尽管总的3d荷不均衡程度很小,以Fe2+ 和Fe3+阳离子t2g轨道占据数的差别所定义的轨道有序序参量相当大(0.73),无可非议的显示YBaFe2O5中存在电荷和轨道有序。O 2pFe eg轨道之间的强的杂化作用使得Fe2+ 和Fe3+阳离子之间总电荷差别几乎完全消失。此外,我们讨论了轨道有序和电荷有序以及磁有序之间的关系。dxz轨道有序决定了G型反铁磁性自旋有序的稳定性和电荷有序模式。
Resumo:
本实验室果蝇研究工作,主要集中在黑腹果蝇的新基因起源的研究。新基因起源的分子机制主要包括:外显子重排、基因复制、基因逆转座、移动元件介导、基因水平转移、基因从头起源、基因的断裂融合。为了阐述这些新基因的产生和它们所带来的物种适应性,我们对这些新近起源的基因进行了功能研究。但是,仅仅限于新基因所在物种的功能研究并不能完全解释新基因产生的进化原因,我们需要了解它是否能够给没有该基因的果蝇物种带来一定的适应性。例如一些生殖相关新基因,如果我们将它们转入没有该基因的果蝇,那是否能够给该果蝇带来生殖能力的提高?无论结果如何,这都为我们研究新基因的起源提供一个重要线索。由此,黑腹果蝇以外的其它果蝇物种中实现转基因成为该研究的重要技术环节。但是,实验室目前的转基因系统仅限于P座子介导的黑腹果蝇转基因系统,因而我们需要建立一种新的转基因平台。而转座子Minos破物种范围的转基因特性,以及它的转座特点为我们提供了选择。转座子Minos从果蝇D. hydei中克隆出来长约1.8kb的Ⅱ型转座子,Tc1家族转座元件成员。Minos转座机制与大部分转座子一样,在宿主基因组里面实行着剪切和粘贴的运作机制。Minos转座时,偏向插入TA位点并且主要集中于内含子区域,这样可以减少对插入位置基因的影响。此外,Minos黑腹果蝇中的转座效率约30%,并且拥有一套成熟的选择标记。因此,Minos为我们解决非黑腹果蝇转基因技术难题的首选。 在本文的工作中,我们采用由希腊Savakis授(希腊分子生物学与生物技术研究所)提供的Minos基因系统,完成果蝇的转基因实验。在这套转基因系统中,非自主的转座子Minos转座酶基因被克隆到了不同载体当中。其中Minos座子序列中插入了由3xP3眼睛特异表达的启动子介导表达的eGFP告基因,而转座酶基因则由热激蛋白hsp70启动子调控表达。实验过程中,我们在果蝇D. melanogaster 和D. yakuba的胚胎中分别同时显微注射入含有转座子和转座酶本实验室果蝇研究工作,主要集中在黑腹果蝇的新基因起源的研究。新基因起源的分子机制主要包括:外显子重排、基因复制、基因逆转座、移动元件介导、基因水平转移、基因从头起源、基因的断裂融合。为了阐述这些新基因的产生和它们所带来的物种适应性,我们对这些新近起源的基因进行了功能研究。但是,仅仅限于新基因所在物种的功能研究并不能完全解释新基因产生的进化原因,我们需要了解它是否能够给没有该基因的果蝇物种带来一定的适应性。例如一些生殖相关新基因,如果我们将它们转入没有该基因的果蝇,那是否能够给该果蝇带来生殖能力的提高?无论结果如何,这都为我们研究新基因的起源提供一个重要线索。由此,黑腹果蝇以外的其它果蝇物种中实现转基因成为该研究的重要技术环节。但是,实验室目前的转基因系统仅限于P座子介导的黑腹果蝇转基因系统,因而我们需要建立一种新的转基因平台。而转座子Minos破物种范围的转基因特性,以及它的转座特点为我们提供了选择。转座子Minos从果蝇D. hydei中克隆出来长约1.8kb的Ⅱ型转座子,Tc1家族转座元件成员。Minos转座机制与大部分转座子一样,在宿主基因组里面实行着剪切和粘贴的运作机制。Minos转座时,偏向插入TA位点并且主要集中于内含子区域,这样可以减少对插入位置基因的影响。此外,Minos黑腹果蝇中的转座效率约30%,并且拥有一套成熟的选择标记。因此,Minos为我们解决非黑腹果蝇转基因技术难题的首选。 在本文的工作中,我们采用由希腊Savakis授(希腊分子生物学与生物技术研究所)提供的Minos基因系统,完成果蝇的转基因实验。在这套转基因系统中,非自主的转座子Minos转座酶基因被克隆到了不同载体当中。其中Minos座子序列中插入了由3xP3眼睛特异表达的启动子介导表达的eGFP告基因,而转座酶基因则由热激蛋白hsp70启动子调控表达。实验过程中,我们在果蝇D. melanogaster 和D. yakuba的胚胎中分别同时显微注射入含有转座子和转座酶所在的质粒。转座酶在37度条件诱导下进行表达,协助Minos成转座过程。在转基因果蝇的阳性筛选中,我们利用眼睛特异表达的绿色荧光蛋作为选择标记。并且,我们通过PCR实验进一步验证了转基因果蝇的真实性。本研究中,我们对转基因实验条件进行了初步优化。我们通过对黑腹果蝇白眼突变品系W1118和D. yakuba注射后胚胎进行保湿,对D. yakuba注射胚胎进行非退壳处理。在改进条件下W1118和D. yakuba的存活率分别为10%和3%左右。通过筛选转基因阳性果蝇,我们得出MinosW1118和D. yakuba中的转座效率分别在32%和20%左右。我们的实验结果再一次证实了Minos果蝇D. melanogaster中可行性。同时,该工作也初步完成了在果蝇D. yakuba 中的第一次Minos导的转基因实验,为新基因的跨物种功能研究奠定了实验基础。在未来的工作计划中,我们将采用Minos基因系统,把实验室目前研究的黑腹果蝇新基因导入其它物种果蝇进行功能研究。 水稻是一种重要的世界粮食作物,世界上过半的人口以水稻为主食。水稻相对别的粮食作物来讲具有较小的基因组,并且拥有较好的基因组注释,是一种理想的单子叶模式生物。植物转基因技术的发展推动着水稻功能基因组学的研究,目前水稻的转基因技术主要依赖于土壤细菌农杆菌(Agrobacterium tumefaciens)T-DNA介导的外源基因染色体插入。在自然状态下,农杆菌的T-DNA位于Ti致瘤质粒当中。它包括了一些转座元件和一些帮助T-DNA转座的毒性蛋白基因和调节基因。由于Ti质粒上的T-DNA太长,并且没有太多的酶切位点,因此自然状态的T-DNA不适合进行转基因实验。为了方便T-DNA的实际应用,研究人员创立了双载体转基因系统。T-DNA转座区被分离到出Ti载体,并且装载到另外一个适合实验操作的质粒当中,而毒性蛋白表达基因等则保留在Ti质粒上。因此,在进行T-DNA介导的转基因实验时,需要同时存在T-DNA载体和Ti质粒。 本文以“水稻注释计划数据库RAP-DB”的表达数据为参考,选择了60个高表达基因的启动子区域进行克隆。通过对T-DNA载体pCAMBIA1301 进行改造,去掉其原来的35S动子,将预测的基因启动子克隆到该载体中并与报告基 摘要 因GUS 基因融合。通过分子克隆实验,我们得到了45个高表达基因的启动子载体。最终,为了测试这45个启动子的启动效率,我们会将它们转化到水稻愈伤组织中通过启动子融合的GUS于表达情况来判断我们启动子的启动效率。
Resumo:
HIRFL was upgraded from beginning 2000. Besides of researches on nuclear physics, atomic physics, irradiative material and biology, the cancer therapy by heavy ion and hadron physics are being developing. The injector system of SFC+SSC can provide all ions from proton to uranium with higher intensity. The Cooling Storage Ring (CSR) has accelerated beams successful. The ions C-12(6+), Ar-36(18+), Xe-129(27+) have been accelerated up 1000MeV/u, 235MeV/u with about 10(9)similar to 10(8) ions per spill respectively. The beam momentum dispersion was measured from 4x10(-3) to 2x10(-4) after cooling by the electron cooler or similar to 4x10(-4) after accelerated to 1000MeV/u without cooling. In order to improve the nuclear structure and heavy isotope research in SFC+SSC energy domain, A Wien filter was added in front of RIBLL and gas was filled in first section of RIBLL; a new spectrometry SHANS has being installed. Presently, there are two starting version experimental setups at CSR.