Dislocations And Twins In Nanocrystalline Ni After Severe Plastic Deformation: The Effects Of Grain Size

Deformation microstructures have been investigated in nanocrystalline (nc) Ni with grain sizes in the 50-100 nm range. It was found that deformation twinning started to occur in grains of similar to 90 nm, and its propensity increased with decreasing grain size. In most of the nc grains dislocations were observed as well, in the form of individual dislocations and dipoles. It is concluded that dislocation-mediated plasticity dominates for grain sizes in the upper half, i.e. 50-100 nm, of the nanocrystalline regime. (C) 2007 Published by Elsevier B.V.

Explorations of electric-current system in solar active regions .1. Empirical inferences of the current flows

In this paper we explore techniques to identify sources of electric current systems and their channels of flow in solar active regions. Measured photospheric vector magnetic fields (VMF) together with high-resolution white-light and H filtergrams provide the data base to derive the current systems in the photosphere and chromosphere. Simple mathematical constructions of fields and currents are also adopted to understand these data. As an example, the techniques are then applied to infer current systems in AR 2372 in early April 1980. The main results are: (i) In unipolar sunspots the current density may reach values of 103 CGSE, and the Lorentz force on it can accelerate the Evershed flow, (ii) Spots exhibiting significant spiral pattrn in the penumbral filaments are the sources of vertical major currents at the photospheric surface, (iii) Magnetic neutral lines where the transverse field was strongly sheared were channels along which strong current system flows, (iv) The inferred current systems produced oppositely-flowing currents in the area of the delta configuration that was the site of flaring in AR 2372.

Study On Buoyancy Convection Phenomenon In The Crystal Growth Process

Real-time phase shift Mach-Zehnder interference technique, imaging technique, and computer image processing technique were combined to perform a real-time diagnosis of NaClO3 crystal, which described both the dissolution process and the crystallization process of the NaClO3 crystal in real-time condition. The dissolution fringes and the growth fringes in the process were obtained. Moreover, a distribution of concentration field in this process was obtained by inversion calculation. Finally, the buoyancy convection phenomenon caused by gravity in the crystal growth process was analyzed. The results showed that this convection phenomenon directly influences the growth rate of each crystal face in the crystal.

Even aberration measurement of lithographic projection system based on optimized phase-shifting marks

In the present paper, we propose a novel method for measuring the even aberrations of lithographic projection optics by use of optimized phase-shifting marks on the test mask. The line/space ratio of the phase-shifting marks is optimized to obtain the maximum sensitivities of Zernike coefficients corresponding to even aberrations. Spherical aberration and astigmatism can be calculated from the focus shifts of phase-shifting gratings oriented at 0 degrees, 45 degrees, 90 degrees and 135 degrees at multiple illumination settings. The PROLITH simulation results show that, the measurement accuracy of spherical aberration and astigmatism obviously increase, after the optimization of the measurement mark. (C) 2008 Elsevier B.V. All rights reserved.

水生植物的气体交换与输导代谢

中国科学院知识创新工程重要方向项目 (KSCX2-SW-10 2 ); 国家杰出青年基金 ( 3 992 5 0 0 7); 武汉市青年科技晨光计划 ( 2 0 0 0 5 0 0 40 44 ); 国家 973计划 ( 2 0 0 2CB412 3 0 0 )

Effects of 2,3,7,8-TCDD and benzo[a]pyrene on modulating vitellogenin expression in primary culture of crucian carp (Carassius auratus) hepatocytes

Vitellogenin (Vtg) is the precursor of yolk protein. Its expression and secretion are estrogen-regulated and are crucial for oocyte maturation. An in vitro xenoestrogen screening model was established by measuring Vtg induction in cultured primary hepatocytes from crucian carp. Vtg production was detected by biotin-avidin sandwich ELISA method while Vtg and cytochrome P4501A1 (CYP1A1) mRNA induction were measured by semi- quantitative PCR-primer dropping technique. Vtg and Vtg mRNA were dose-dependently induced by diethylstilbestrol (DES, 0.2-200 ng/mL) in hepatocytes of crucian carp. Co-treatment of the DES-induced hepatocytes with either 2,3,7,8-TCDD (TCDD, 0.1-4 pg/mL) or benzo[a]pyrene (B[a]P, 5-1000 ng/mL) resulted in a reduction of Vtg production and an increment of CYP1A1 mRNA expression both in a dose dependent manner, indicating the anti-estrogenic effects of the compounds. However, at lower tested concentrations, TCDD (0.1, 0.2 pg/mL), B[a]P (5 ng/mL) seemed to have a potentiating effect on Vtg expression and secretion, although by their own these compounds had no observable estrogenic effect on Vtg induction. Tamoxifen (a selective estrogen receptor modulators, 1 nmol/L-1 mumol/L), and P-naphtho-flavone (beta-NF, an aryl hydrocarbon receptor inducing compounds, 2.5-1000 ng/mL) also were employed to study the possible interactions in DES-induced Vtg expression. In co-treatment of the DES-induced hepatocytes with beta-NF or tamoxifen, the decrease in Vtg production did parallel induction of CYP1A1 for beta-NF, but tamoxifen inhibited Vtg induction did not parallel induced CYP1A1 expression in all test concentrations. On the contrary, it was found that in co-treatment of the TCDD-induced hepatocytes with DES, TCDD induced CYP1A1 mRNA production was inhibited by DES also. These results implicated a possible cross talk between estrogen receptor- and aryl hydrocarbon receptor-mediated pathways in the hepatocytes.

A New Discrimination Method of Maize Seed Varieties Based on Near-Infrared Spectroscopy

A new discrimination method for the maize seed varieties based on the near-infrared spectroscopy was proposed. The reflectance spectra of maize seeds were obtained by a FT-NIR spectrometer (12 000-4 000 cm(-1)). The original spectra data were preprocessed by first derivative method. Then the principal component analysis (PCA) was used to compress the spectra data. The principal components with the cumulate reliabilities more than 80% were used to build the discrimination models. The model was established by Psi-3 neuron based on biomimetic pattern recognition (BPR). Especially, the parameter of the covering index was proposed to assist to discriminating the variety of a seed sample. The authors tested the discrimination capability of the model through four groups of experiments. There were 10, 18, 26 and 34 varieties training the discrimination models in these experiments, respectively. Additionally, another seven maize varieties and nine wheat varieties were used to test the capability of the models to reject the varieties not participating in training the models. Each group of the experiment was repeated three times by selecting different training samples at random. The correct classification rates of the models in the four-group experiments were above 91. 8%. The correct rejection rates for the varieties not participating in training the models all attained above 95%. Furthermore, the performance of the discrimination models did not change obviously when using the different training samples. The results showed that this discrimination method can not only effectively recognize the maize seed varieties, but also reject the varieties not participating in training the model. It may be practical in the discrimination of maize seed varieties.

一种需求变更驱动的软件项目人力资源调度方法

摘　要 需求开发和维护是软件生产的基础，是软件开发的重要部分。需求变更是软件项目中最常见、影响最大的风险之一,会对软件项目的成本、进度和软件产品的质量产生不同程度的影响。本文提出一种需求变更驱动的软件项目人力资源再调度方法。该方法通过建立需求变更模型来分析需求变更对软件项目计划的影响，并在此基础上使用人力资源调度算法来获得满足时间、成本双重约束的人力资源分配方案，为软件项目管理人员提供决策参考，从而提高软件企业的风险管理能力和资源利用率。最后，本文通过一个示例说明了该方法的可行性和有效性。

利用力致分子动力学模拟方法构建剪切流场

<正>在传统计算力学的研究领域,利用Fluent等软件实现连续介质流体的模拟,已有很成熟的经验及范例;同时,分子动力学模拟也在其擅长的微观结构分析及预测领域有了长足的发展。但是到目前为止,连续介质力学仍无法和分子动力学方法有机地结合起来。因此,仍无法在分子动力学模拟体系构建理想的(即速度梯度和温度可控的)剪切流场。Grattona与Delgado-Buscalioni等的研究表明,在分子动力学模拟中,利用

腐植酸有机硒肥与食品安全及食疗健康

硒对高血压、心肌病及多种癌症有防治效果,因此,硒肥是一种功能性肥料。其施用对土壤脲酶,转化酶和磷酸酶有激活作用,能减少作物体内自由基,提高抗逆性,是一种安全肥料。施用硒肥能提高作物的含硒量,其中,粮食作物含硒量增加2.352～134.0倍,以大豆和小麦含量为最高;蔬菜作物含硒量增加6.78～74.50倍,以西兰花、菜花、红萝卜和菜豆角含量最高。硒肥的施用使玉米产量提高11.27%～26.06%,大豆产量提高9.63%～12.00%,且能改善大豆品质,异亮氨酸、甘氨酸、缬氨酸、亮氨酸和谷氨酸等含量增加4.07%～10.00%,保健功能明显增强。

水分处理对沙地樟子松幼苗膜脂过氧化作用及保护酶活性影响

通过盆栽控水实验,模拟科尔沁沙地由东至西50年的年均降水量及最大、最小年降水量下的土壤水势,分析了不同水分处理(土壤水势分别为-16.18、-5.09和-4.50bars,即A、B和C处理)对樟子松2年生幼苗膜脂过氧化产物[丙二醛(MDA)、脂膜相对透性(RC)和超氧阴离子自由基(O2.-)产生速率]、渗透调节物质[可溶性糖(SS)、可溶性蛋白(SP)和脯氨酸(Pro)]和膜保护酶(SOD酶和POD酶)的影响。不同水分处理对樟子松幼苗针叶内的保护酶、渗透调节物质及膜脂过氧化的作用影响显著。随着土壤水势的降低,幼苗的SOD酶呈现微下降再升高的趋势;POD酶活性呈逐渐升高的趋势;幼苗的渗透调节物质(SS、SP和Pro)的含量均呈现上升趋势;3种水分处理的可溶性糖和可溶性蛋白含量上升的幅度最大,A处理分别是C处理的1.8倍和2.4倍,脯氨酸的含量持续积累;随干旱胁迫加重,MDA、RC和O2.-产生速率均有明显上升趋势,以O2.-产生速率上升幅度最大。这表明,樟子松幼苗通过体内的生理生化机制,尤其是增加渗透调节物质的含量,实现对干旱胁迫较强的忍耐性和较好的适应性。A处理针叶内的自由基大量积累和膜脂过氧化程度加重,对植物造成不可逆的损伤。

Effect of substituting cerium-rich mischmetal with lanthanum on microstructure and mechanical properties of die-cast Mg-Al-RE alloys

Die-cast Mg-4Al-4RE-0.4Mn (RE = Ce-rich mischmetal) and Mg-4Al-4La-0.4Mn magnesium alloys were prepared successfully and their microstructure, tensile and creep properties have been investigated. The results show that two binary Al-RE phases, Al11RE3 and Al2RE, are formed along grain boundaries in Mg-4Al-4RE-0.4Mn alloy, while the phase compositions of Mg-4Al-4La-0.4Mn alloy mainly consist of alpha-Mg phase and Al11La3 phase. And in Mg-4Al-4La-0.4Mn alloy the Al11La3 phase occupies a large grain boundary area and grows with complicated morphologies, which is characterized by scanning electron microscopy in detail. Changing the rare earth content of the alloy from Ce-rich mischmetal to lanthanum gives a further improvement in the tensile and creep properties, and the later could be attributed to the better thermal stability of Al11La3 phase in Mg-4Al-4La-0.4Mn alloy than that of Al11RE3 phase in Mg-4Al-4RE-0.4Mn alloy.

一种生产二甲醚的催化剂及制备方法和应用

一种生产二甲醚的催化剂重量百分比组成为γ－Ａｌ↓［２］Ｏ↓［３］６０～８０ｗｔ％、ＴｈＯ↓［２］１～１５ｗｔ％、Ｇａ↓［２］Ｏ↓［３］１～１５ｗｔ％、ＺｒＯ↓［２］１～１５ｗｔ％、粘合剂１０～２５ｗｔ％。采用将原料分别破碎到２００目以下，按催化剂重量百分比组成将其混合，搅拌，成型，在干燥，焙烧制得催化剂。本发明具有制备简便、快速；操作条件比较温和，反应性能好，无污染的优点。

句容海安区块热史、成烃史与二次生烃

Jurong -Hai'an block of lower Yangtz area is one of the important petroleum exploration area among the residual marine basins in the south China. In the history of the basin's evolution, the strongly compressing, napping, folding and deforming during Indosinian to Yanshan epoch resulted in destruction of the early formed petroleum pool. Therefore, the strategy exploration of the secondary hydrocarbon generation and later formation of petroleum pool was brought forward for petroleum exploration and planning in the study area..On the basis of tectonic and sedimentary as well as present-day thermal regime evolution, using vitrinite reflectance and apatite fission track data and the paleo-heat flow based method, the basin's thermal history is reconstructed and hence the strata's temperature history are obtained. In addition, the maturation histories of the main four sets of marine hydrocarbon source rocks in the block are calculated. Furthermore, taking the maturity in the end of early Cretaceous as the original maturity and according to the formulas fitted by the secondary hydrocarbon generation model, the secondary hydrocarbon generation potential of the four sets of source rock is evaluated.The results of thermal history reconstruction show that Jurong-Hai'an block was under an uniform thermal setting during the Caledonian to Hercynian period and characterized by middle heat flow (52~57rnW/ m2). The uniform thermal setting was divided during and after Indosinian to Yanshan epoch. Wuwei area of southern Anhui province was under the high heat flow setting(~90 mW/m2)between 236Ma and 137Ma; Jurong area of southern Jiangsu ,Huangqiao area and Subei basin reached its maximum heat flow of 90,84 and 78-82 mW/m2 at 101Ma,157Ma and 56Ma respectivelyThe study of secondary hydrocarbon generation shows that the upper Paleozoic and Triassic source rocks have excellent secondary hydrocarbon generation potential. Silurian source rock posses some secondary hydrocarbon generation. Cambrian source rock, however, nearly has no secondary hydrocarbon generation. Overall there are no advantages of secondary hydrocarbon generation in the southern area of Jiansu. The intensity of secondary hydrocarbon generation in North Jiangsu basin is definitely better than that in the southern area of Jiangsu.