Magnetization of microorganism cells by sol-gel method

Microorganism cells could be used as templates during fabrication of magnetic or conductive microstructures in different standard shapes. In this paper, feasibility of magnetizing microorganism cells by sol-gel method, which is to coat cells of Spirulina (a type of natural micro-helical microorganism) with the ferrite (a kind of magnetic material), was discussed and investigated. Then the cell form, components and the phase structure were observed and analyzed using various tools including optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray detector (EDX), transmission electron microscopy (TEM), and X-ray diffraction analysis (XRD). Results showed that spirulina cells could be coated with ferrite after the sol-gel process, with the shape of natural helixes well kept, that the components of different sampling points on the surface layer were consistent and the thickness of layer was uniform, and that the type of the surface ferrite layer formed was cubic Fe₃O₄. It was also observed that there were nano-particles yielded in the cells and certain deposit on the walls between cells. The kinetics of the cell magnetization technology by sol-gel was also discussed. Supported by the National Natural Science Foundation of China (Grant No. 59975007), the National Hi-Tech Research and Development Program of China (863 Program) (Grant No. 2001AA421120), and the Innovative Fund of Beihang University in 2005 (Grant No. 200505)     

温压技术的应用、发展及其在我国的工业化前景

根据国内外粉末冶金零件市场的走势，论证了温压技术在我国工业化的重要性。综述并讨论了温压技术的应用及发展趋势。介绍了作者们开发的温压专用粉末加热装置和温压成形粉末冶金材料的性能，其成果为温压原材料及设备的国产化打下了基础。     

邯钢CSP加热炉的设计原则和特点

根据邯钢CSP加热炉谈判、设计、生产以及维护中积累的经验 ,讲述了CSP加热炉设计应注意的几个重要问题 ,使之能更好地满足薄板坯连铸连轧生产的要求     

RBF网络在光纤陀螺动态误差模型辨识中的应用

提出了基于径向基(Radial Basis Function 简称RBF)神经网络的动态误差模型的辨识方法.对如何从一般正交三轴转台速率实验获取训练样本及对网络的学习训练给予了详细的介绍.仿真结果证明了这个方法是可行有效的,可以提高光纤陀螺的输出精度.     

混凝改善超滤膜过滤性能的研究

研究有机物的特性如亲、疏水性以及相对分子质量的大小对超滤膜通量的影响.着重考察混凝对有机物特性的影响以及改善超滤膜通量的效果.试验表明,超滤膜直接过滤原水时,主要截留疏水性有机物,从而造成膜通量的下降.投加硫酸铝25 mg/L和100 mg/L时,虽然TOC去除率仅为18.4%和48.2%,但明显提高了膜通量,这是由于混凝有效地去除小分子疏水性有机物的缘故.研究表明,膜通量的下降与膜截留疏水性有机物的多少有密切关系.     

浅析符号学对产品形态设计的导向作用

本文通过对产品形态设计中运用符号学理论的分析,探讨了符号学在产品形态设计中的重要性和启示作用,体现利用符号学创造出舒适、和谐的产品形态视觉效果的观点。     

超低硫钢冶炼过程钢包渣改质剂的作用

在超低硫钢冶炼过程中对转炉出钢下渣进行了改质处理试验。使用钢包渣改质处理工艺 ,不仅可以降低钢包顶渣氧化性、提高顶渣碱度、优化顶渣脱硫条件 ,为LF炉生产超低硫钢创造了有利条件 ,实现精炼前移功能 ,使成品钢中最低硫质量分数达到 1 0×1 0 - 6 ,而且缩短冶炼时间、提高合金收得率和钢水纯净度     

恒高温下钢管混凝土界面黏结性能试验研究

钢管混凝土的界面黏结性能是钢管和混凝土之间共同受力与协调变形的基础。为探讨高温下钢管混凝土界面黏结破坏特点和平均黏结强度的主要影响因素,文中以恒温温度、长径比和径厚比等为主要研究参数,进行钢管混凝土试件恒高温下的推出滑移试验,得到钢管混凝土界面的温度-时间和荷载-滑移关系曲线。试验结果表明,在20℃～900℃研究范围内,恒温温度对圆钢管混凝土平均黏结强度有显著的影响,平均黏结强度随恒温温度的升高先减小后增加再减小,降低幅度最高达到90%;平均黏结强度随钢管长径比的增大而减小,降低幅度最高达50%;钢管径厚比对平均黏结强度影响很小,降低幅度在10%以内。     

Identification of structural domains by considering multiple discontinuity characteristics: a case study of the Songta Dam

Discontinuities formed by different geological processes strongly affect the inhomogeneity of a rock mass. Demarcation of statistically homogeneous regions is useful to speculate the tectonic evolution history. Therefore, a new method is introduced to divide the homogeneous structural domains based on multiple discontinuity characteristics. The new method is divided into three steps. Firstly, the 34-patch network on the lower-hemisphere Schmidt projection and the correlation coefficient are adopted to quantify the similarity of discontinuity orientation. Secondly, the Wald–Wolfowitz runs test is utilized to identify the similarity for trace length and trace type. Thirdly, the structural domains are comprehensively identified based on the similarity of discontinuity orientation, trace length and trace type. The comprehensive method is subsequently adopted to divide the structural domains within the Songta right abutment rock mass. The results illustrate that the rock mass around PD222 and PD234 belongs to the same structural domain D1 and the rock mass around PD224 and PD236 belongs to the other structural domain D2. The D2 located at the high elevation suffers longer and stronger unloading effect of the river valley, which is more likely to form the long discontinuities. However, the D1 located at the low elevation develops mainly the short discontinuities. Hence, it is reasonable and consistent with geological development background that the abutment rock mass is divided into two structural regions along the vertical direction using the new method.     

Using XFEM to model the effect of different axial compression on the hysteretic behaviour of the flexure‐dominant RC columns

The axial compression ratio has a significant effect on the strength and ductility of reinforced concrete (RC) columns subjected to seismic loads. However, limited numerical models have been found to be able to consider the effect of axial compression ratio in mesoscopic scale. To achieve a sound understanding of the hysteretic mechanism of RC columns with different axial compression ratios, a novel modelling method was developed by employing the following techniques: (a) the extended finite element method for modelling crack initiating and propagating in concrete; (b) the contact algorithm for modelling the crack closure; and (c) the Cartesian type “connector” for modelling the interaction between concrete and steel bars. The effectiveness of the proposed model was validated in macroscopic scale by the results of a previous experimental study. Further analysis indicates that the axial compression ratio controls the axial deformations of RC columns, thus leads to different performances of concrete and steel under seismic loads. Based on the individual flexural contributions of the concrete and the steel bars, the effect of the axial compression ratio and the pinching effect is explained in a finer scale. The analytical results shed some light on the seismic mechanism of RC columns with different axial compression ratios.