轻质双相高熵合金Al20Li20Mg10Sc20Ti30热力学性质的第一性原理研究

采用特殊准随机结构(Special Quasi-random Structure, SQS)处理高熵合金固溶体的化学无序性,并基于密度泛函理论研究了具有面心立方(Face-centered Cubic, FCC)和密排六方(Hexagonal Close-packed, HCP)结构的Al20Li20Mg10Sc20Ti30高熵合金的结构稳定性和热力学性质。理论得到的两个相的晶格常数与实验测量值符合较好。两相中,由于HCP相具有较FCC相略大的体模量,因而其具有较好的抗压缩性能。由于计算得到的两个相在0 K时的形成焓都为小的正值,因而两个相都为热力学亚稳结构。采用Debye-Grüneisen模型研究了不同温度下两个相的热力学性质,结果表明两个相的体模量随温度的上升表现出缓慢的下降趋势,且HCP相的体模量大于FCC相,而FCC相具有更大的体积热膨胀系数。研究了两个相的熵(包括振动部分的贡献和电子部分的贡献)随温度的变化,结果表明在研究的温度范围内,HCP相比FCC相具有更大的熵,且两个相的熵的主要来源都为振动部分的贡献。     

Die Novellen zur Bauordnung für Wien im Jahr 2006

Die Bauordnung für Wien (WBO) wurde im Jahr 2006 durch zwei Novellen ge?ndert. Die 1. Novelle (wr LGBl 10/2006) dient im Wesentlichen der Umsetzung der EU-RL 2001/42/EG über die Prüfung der Umweltauswirkungen bestimmter Pl?ne und Programme und 2003/105/EG zur ?nderung der EU-RL 96/82/EG zur Beherrschung der Gefahren bei schweren Unf?llen mit gef?hrlichen Stoffen sowie der Neudefinition des Hochhausbegriffes. Durch die 2. Novelle (wr LGBl 61/2006) erfolgt eine Neufassung der Bestimmungen über die so genannte "Bekanntgabe der Bebauungsbestimmungen". Im Folgenden werden die Schwerpunkte der beiden Novellen dargestellt.     

Residues of veterinary antibiotics in manures from feedlot livestock in eight provinces of China

The residue levels of selected fluoroquinolones, sulfonamides and tetracyclines in 143 animal dung samples collected in 2007 from large-scale livestock and poultry feedlots in 8 provinces were determined by using ultrasonic extraction and liquid chromatography. Recoveries from spiked pig dung samples (spike level = 1 mg/kg) ranged from 73.9 to 102.0% for fluoroquinolones, from 81.6 to 92.3% for sulfonamides, and from 57.2 to 72.6% for tetracyclines. Relative standard deviations of the recoveries were less than 10% within the same day. Method quantification limits were measured from 0.031 to 0.150 mg/kg for fluoroquinolones, from 0.023 to 0.082 mg/kg for sulfonamides, and 0.091 to 0.182 mg/kg for tetracyclines in spiked pig manure samples. Analysis of 61 pig, 54 chicken and 28 cow dung samples collected in China revealed that in pig and cow dung, up to 33.98 and 29.59 mg/kg ciprofloxacin, 33.26 and 46.70 mg/kg enrofloxacin, 59.06 and 59.59 mg/kg oxytetracycline, and 21.06 and 27.59 mg/kg chlortetracycline could be detected, respectively. A maximum concentration of 99.43 mg/kg fleroxacin, 225.45 mg/kg norfloxacin, 45.59 mg/kg ciprofloxacin and 1420.76 mg/kg enrofloxacin could be detected in chicken dung. No appreciable sulfonamide antibiotic concentrations (less than 10 mg/kg) were found in any animal dung, and only sulfadimidine was observed, at a maximum concentration of 6.04 mg/kg, in chicken dung. Both enrofloxacin and chlortetracycline were detected with a very high occurrence in three animal manure samples. The residue levels for most antibiotics showed significant statistical differences among the sampling districts and the animal species.     

杀虫剂亚致死剂量对棉铃虫靶标酶的影响

高效氯氰菊酯、氯氟氰菊酯、辛硫磷、杀螟硫磷4种杀虫剂亚致死剂量(LC50)预处理棉铃虫Helicoverpaarmigera(Hübner)3龄幼虫一定时间后,4种杀虫药剂对棉铃虫的毒力影响有明显差异。酶动力学研究表明:用4种药剂的亚致死浓度LC50剂量处理棉铃虫3龄幼虫,在药剂处理后的144h内,幼虫GSTs活性发育变化规律与对照有一定的差异。GSTs比活力在对照组GSTs比活力值附近波动,说明昆虫在杀虫药剂刺激一段时间后,其GSTs处于动态的调整之中。在48～120h之间,Na+–K+–ATP酶比活力与对照组相比有回升的趋势,说明昆虫在外界刺激物的作用下,其Na+–K+–ATP酶也处于动态的调整之中。     

Modelling of Electrical Conductivity of a Silver Plasma at Low Temperature

During the working of electrical fuses, inside the fuse element the silver ribbon first begins to melt, to vaporize and then a fuse arc appears between the two separated parts of the element. Second, the electrodes are struck and the burn-back phenomenon takes place. Usually,the silver ribbon is enclosed inside a cavity filled with silica sand. During the vaporization of the fuse element, one can consider that the volume is fixed so that the pressure increase appears to reach pressures higher than atmospheric pressure. Thus, in this paper two pressures, 1 atm and 10 atm, are considered. The electrical field inside the plasma can reach high values since the distance between the cathode surface and the anode surface varies with time. That is to say from zero cm to one cm order. So we consider various electrical fields: 10~2V/m, 10~3V/m, 5×10~3V/m,10~4V/m at atmospheric pressure and 10~5V/m at a pressure of 10 atm. This study is made in heavy species temperature range from 2,400 K to 10,000 K. To study the plasma created inside the electric fuse, we first need to determine some characteristics in order to justify some hypotheses.That is to say: are the classical approximations of the thermal plasmas physics justified? In other words: plasma frequency, the ideality of the plasma, the Debye-Hückel approximation and the drift velocity versus thermal velocity. These characteristics and assumptions are discussed and commented on in this paper. Then, an evaluation of non-thermal equilibrium versus considered electrical fields is given. Finally, considering the high mobility of electrons, we evaluate the electrical conductivities.     

多孔钛材料的动态力学响应研究

通过一级轻气炮加载,对孔洞具有一定规律的多孔钛材料进行了平板撞击实验及数值研究.基于锰铜压阻计测量到的实验波形,获得了冲击波在多孔钛材料中传播的衰减效应以及冲击波波速和波后粒子速度的D-u冲击绝热关系.依照实验情况在非线性动力学有限元软件中建立了数值模型,并根据计算结果得到了冲击波的压力-时间波形以及冲击绝热关系,拟合出了多孔钛材料的多项式形式Griüneisen状态方程.通过对压缩度μ进行泰勒展开,结合冲击波基本关系式及冲击绝热关系,从理论上得到了多项式形式Grüneisen状态方程系数的具体表达式.     

AG9/AB9与牛血清白蛋白相互作用的德拜休克尔极限理论分析及其焓熵补偿

本研究通过多光谱技术深入探讨盐浓度（离子强度）对酸性绿9（acid green 9,AG9）和酸性蓝9（acid blue 9,AB9）与牛血清白蛋白（bovine serum albumin,BSA）之间相互作用的影响。运用德拜休克尔极限理论定 量分析,计算得到真实的吉布斯自由能变化（ΔG0I →0）和BSA的阴离子受体腔内有效电荷（ZB）。配体AG9/AB9 所带电荷ZC的值为负,ZB的值为正,意味着相反电荷之间离子对的形成,即AG9/AB9的负电荷与BSA的净正电荷 结合腔（位点-Ⅰ）相结合,表明BSA的局部电荷主导BSA-AG9/AB9体系的相互作用,而不是它的整体或表面电 荷。随着盐浓度的增加,这两个体系的熵变逐渐由正值变为负值,且焓变逐渐增大,使ΔG0几乎不变而发生焓熵补 偿。最终其热力学参数由ΔH0＜0、ΔS0＞0（静电力）在高盐浓度下转变为ΔH0＜0、ΔS0＜0（非静电力）,表明 AG9/AB9与BSA相互作用时,它们的移动或局部运动由于主导力的转变而受阻。     

Globale Nahrungssicherung für eine wachsende Weltbevölkerung – Flächenbedarf und Klimarelevanz sich wandelnder Ernährungsgewohnheiten

Ohne Zusammenfassung Diesem Beitrag liegt – in gekürzter Form – die externe WBGU-Expertise „Globale Ern?hrungsgewohnheiten und –trends“ der Autoren zugrunde. Eingegangen: 24. M?rz 2009; angenommen: 1. April 2009