Applications of medium-voltage STEM for the 3-D study of organelles within very thick sections

Scanning transmission electron microscopy at 300 kV enables the visualization of nucleolar silver-stained structures within thick sections (3–8 μm) of Epon-embedded cells at high tilt angles (–50°; + 50°). Thick sections coated with gold particles were used to determine the best conditions for obtaining images with high contrast and good resolution. For a 6-μm-thick section the values of thinning and shrinkage under the beam are 35 to 10%, respectively. At the electron density used in these experiments (100e^—/Å₂/s) it is estimated that these modifications of the section stabilized in less than 10 min. The broadening of the beam through the section was measured and calculations indicated that the subsequent resolution reached 100 nm for objects localized near the lower side of 4-μm-thick sections with a spot-size of 5·6 nm. Comparing the same biological samples, viewed alternately in CTEM and STEM, demonstrated that images obtained in STEM have a better resolution and contrast for sections thicker than 3 μm. Therefore, the visualization of densely stained structures, observed through very thick sections in the STEM mode, will be very useful in the near future for microtomographic reconstruction of cellular organelles.     

开口薄壁杆件单元刚度矩阵在形心坐标系下的表达形式

本文应用符拉索夫的开口薄壁杆件理论推导了一种新的开口薄壁杆件单元刚度矩阵。该单元刚度矩阵是建立在形心坐标系下的,它不仅消除了某些文章中由于混淆了形心坐标与扭心坐标所产生的错误,而且具有实用方便的特点。     

实施船板战略,提高船板生产能力

船板战略是济钢实施从市场信息、获取订单到合同兑现全过程的管理新模式。济钢中板厂实施船板战略,采取对设备薄弱环节进行改进,优化船板生产工艺和控制轧制工艺等措施,提高了船板的产量和质量,船板一次合格率达到99．63％,2006年产量达到43．77万t,其中高强度船板达到5．53万t。     

庙沟铁矿边坡结构面调查与岩体质量评价研究

应用奥地利结构面数字识别系统Shape MetriX3D对庙沟铁矿边坡进行结构面调查分析,获得了结构面的详细信息,为边坡稳定性研究提供数据支持。     

Comparison of Group Constants Using Single-and Multi-Level Formulas for the Resolved Resonance Region of Uranium-235 and Uranium-233

Using the single-level and the Adler-Adler multi-level resonance formulas for ²³⁵U, whose parameters were derived by fitting to common experimental data, group constants were obtained for the energy region from 59.8 to 0.215 eV, having the same group structure as the 70 group JAERI-FAST set.

It was found that use of the multi-level formula is preferable to the single-level alternative, the former being able to reproduce the experimental data more accurately than the latter. The resulting difference in the values of the group constants amounted to about 40% for some groups.

The group constants of ²³³U, determined by means of multi-level formula are also presented for the energy region from 36.0 to 0.215 eV.     

白云鄂博铁矿主采场爆破优化设计

文章针对白云鄂博铁矿主采场的爆破方法,从选取起爆方式、选择爆区规模、优化孔网参数和改善装药结构4个方面对主采场的爆破进行优化设计,合理选取适合主采场目前使用的爆破方法.     

冷轧连退线退火炉加热段炉辊辊型改造

分析了某连退线带钢在退火炉内常出现跑偏导致限速、擦炉墙断带等问题的原因,给出了采取改进加热段部分炉辊辊型的措施,从而减少了跑偏和断带的现象,取得了良好的效果.     

34Mn6大断面圆管坯表面渣沟缺陷分析

本文结合理论并通过试验对比分析说明了 34Mn6大断面铸坯表面渣沟缺陷的成因 ,并制定了改善措施 ,为以后改进表面质量提供依据     

东秦岭﹙河南段﹚钼矿床类型及找矿潜力分析

根据东秦岭﹙河南段﹚钼矿床3种成矿流体﹙燕山期岩浆作用形成的高温成矿热液、熊耳期火山期后热液、构造动力作用形成的中低温成矿流体﹚,对应划分3种钼矿床成因类型:岩浆热液交代型钼矿床、石英脉型钼矿床和构造蚀变岩型钼矿床。区内岩浆热液交代型钼矿床,是广义上的斑岩型钼矿,包括斑岩型钼矿、斑岩-矽卡岩型钼矿、斑岩-爆破角砾岩型钼矿、爆破角砾岩型、矽卡岩型钼矿钼矿。根据其产出空间位置不同,进一步划分内接触带型、接触带型和外接触带型矿床。文章还介绍了各类型典型钼矿床特征,分析了各类型钼矿床的找矿方向。     

235U快中子核反应截面协方差评价

本文基于最小二乘不确定度传递方法,建立²³⁵U中子裂变核反应截面模型依赖型与非模型依赖型协方差评价体系。通过针对实验测量较丰富的中子反应总截面、辐射俘获、(n,2n)等核反应实验数据不确定度源项分析,为协方差评价提供实验基础,并给出对应核反应截面的非模型依赖型协方差评价数据。通过开展快中子能区²³⁵U核反应理论模型参数灵敏度计算与分析,导出实验测量缺乏的核反应截面模型依赖型协方差评价数据。经上述系统评价,所得协方差数据与核反应截面中心值研究过程自洽、物理合理,并按国际标准ENDF-6格式输出,便于核工程用户使用。