Examination of the Causes of Instability of Soy Protein Isolate During Storage Through Probing of the Heat‐Induced Aggregation

This study investigated the mechanism of instability of soy protein isolate (SPI) as influenced by thermal aggregation during SPI preparation. Samples with different degrees of aggregation but similar protein solubility were prepared by heating native SPI (5 % w/v) at 80 or 90 °C for different times before spray‐drying. The samples were then stored at 37 °C for up to 12 weeks and analyzed periodically by atomic force microscopy, gel permeation chromatography, and SDS–PAGE. All SPI samples underwent remarkable protein solubility decreases during the first 8 weeks of storage. The rates of solubility loss were positively correlated with the amounts and/or sizes of soluble aggregates contained in the initial samples (time zero), suggesting their nucleation and activation effects. Solubility tests in SDS–urea solutions and disulfide analysis indicated that non‐covalent interactions were the main driving forces for protein storage instability. Conversely, disulfide bonds and protein carbonyls were abundant in soluble aggregates, and their content increased markedly during storage. This effect suggested that covalent linkages acted as blockers for hydrophobic aggregation.     

青岛市土地利用动态变化及驱动力探究

以青岛市1990-2006年土地利用统计资料和卫星图片等相关资料为基础,通过土地利用的时空变化模型分析,归纳出了其动态变化规律,即：居民点及工矿用地面积、林地面积、交通用地面积和其他农用地面积大幅度增加,耕地、园地和未利用地则表现为不同程度的减少.在此基础上,进一步分析得出了影响青岛市土地利用类型动态变化的几种主要因素,分别是：地形地貌、区域位置、经济发展、城镇化和工业化以及中央和地方各级政府的宏观政策.     

By Words and Deeds: Racial Steering by Real Estate Agents in the U.S. in 2000

Although prohibited by the federal Fair Housing Act of 1968, studies in the 1980s found that racial steering by real estate agents in the U.S. was still occurring. That legislation was strengthened in 1988, but throughout the 1990s, no study examined whether these tougher strictures helped eliminate steering. In 2000, HUD and the Urban Institute conducted the national Housing Discrimination Study in 20 U.S. metropolitan areas to replicate and extend that earlier work. In this article, we report the results of this latest study, which examined three types of steering and three steering mechanisms, all at three geographic scales. The results indicate that steering of all types is occurring when Black and White homebuyers are involved. In at least 12 to 15% of the cases, agents provided gratuitous commentary that gave more information to White homebuyers and encouraged them to choose homes in areas with more White and fewer poor households. Steering is less prevalent when Hispanic and White buyers are involved. We also found no evidence that steering declined over the last decade, despite the toughening of the federal legislation in 1988. We conclude by discussing the implications for interracial wealth differentials and new fair housing enforcement initiatives.     

Application of shape memory alloy bars in self-centring precast segmental columns as seismic resistance

The objective of this study is to investigate analytically the performance of self-centring precast segmental bridge columns with shape memory alloy (SMA) starter bars under nonlinear static and lateral seismic loading. For this purpose, a 3D finite element model for hybrid post-tensioned bridge column has been developed. The precast post-tensioned segmental bridge columns possessing a central tendon and adequate transverse confinement provided by the steel tube jacketing as self-centring bridge columns have an undesirable high lateral seismic demand due to their low energy dissipation. In order to eliminate this deficiency while keeping the residual displacement small, SMA starter bars are applied in this system. The effect of post-tensioning (PT) forces of the central strands and SMA bar size are investigated. The results indicate that in high seismicity zones, bridge columns with SMA bars at a higher level of PT forces have a superior performance against earthquake loading.     

航母编队防空舰阵位配置优化研究

针对航母编队防空舰阵位配置问题的复杂性和重要性,提出一种航母编队防空舰阵位配置优化方法。根据防空舰部署距离、拦截扇区大小、拦截扇区内空袭目标概率函数,构建描述防空舰防空作战能力的防护条件下航母可生存概率函数,通过将防空舰配置问题转化为二维平面内防空扇区配置问题,建立一个航母编队防空舰配置优化模型,并通过仿真实验,对不同作战目标情况下模型的可行性进行验证。仿真结果表明:该模型具备有效性和可行性,可为提升航母编队防空舰作战能力提供参考。     

Large‐Scale Synthesis of a Porous Co3O4 Nanostructure and Its Application in Metastable Intermolecular Composites

Three‐dimensional nanostructured porous Co₃O₄ was synthesized on a silicon substrate via a hydrothermal route in conjunction with annealing treatment. The structure and morphology of the obtained Co₃O₄ samples were systemically examined using field‐emission scanning electron microscopy and X‐ray diffraction. The Co₃O₄ structures were composed of nanosheets forming a pore‐network architecture that promoted Al penetration into its inner regions during deposition resulting in enhanced interfacial contact area, which significantly improve metastable intermolecular composites (MICs) burning rate and the release of energy. The successfully Co₃O₄ was used to synthesize Al/Co₃O₄ based MICs by integration with nano‐Al deposited via thermal evaporation. The heat of reaction of Al/Co₃O₄, particularly the exothermic reaction before Al melting, was greatly enhanced by the Co₃O₄ nanostructures. The Al/Co₃O₄ based MICs were fabricated on a silicon substrate, which is very convenient for integrating MICs with silicon‐based microelectromechanical systems to achieve functional nanoenergetics‐on‐a‐chip.     

Fe2O3-Al纳米铝热剂与超细RDX复合物的制备与性能

采用溶胶-凝胶方法,制备出了纳米铝热剂nano-Fe2O3-Al,并获得了其与超细RDX的复合含能材料nanoFe2O3-Al/SFRDX。采用BET法、SEM、XRD综合表征了nano-Fe2O3-Al的结构,采用TG/DSC联用技术测试了nano-Fe2O3-Al的热性能,结果表明气凝胶铝热剂的反应温度更低;nano-Fe2O3-Al的静电火花感度测试结果表明纳米铝热剂对静电十分敏感。对nano-Fe2O3-Al/SFRDX在无约束条件和密闭条件下的燃烧行为进行了研究,高速相机照片法发现在无约束条件下,nanoFe2O3-Al燃烧高达300 m/s,且nano-Fe2O3-Al/SFRDX具有在无约束条件下由燃烧转为爆轰的趋势。     

防空兵被动测距方法研究

防空兵双活动平台被动测距方法采用带码盘和CCD的结合,依据“双站交会”原理完成距离计算,利用软件系统对单帧视频数据中的弹、目距离进行准确求取。从其误差曲线对比可知,对各型测距模型运用中,保持光学视场轴中心与目标之间方位、高低夹角在π／4时,系统精度最高。从各种测距模型曲线绘制图显示可知,基线测量精度对系统影响较小,测角误差才是系统测距误差的主要误差源。     

机载合成孔径雷达对地面防空力量的威胁及干扰对策研究

描述了机载合成孔径雷达的特点,分析某机载合成孔径雷达对地面防空力量的威胁,从有源干扰、无源干扰两方面研究地面部队对其实施干扰的技术对策。     

将管理创新转化为生产力

通过改善管理机制,将管理创新转化为生产力,探求我国热处理生产改造的方向,尽早使我国的热处理生产和机械产品质量进入世界先进行列,并且使能源的消耗、环境的污染得到有效的治理和改善,为此我们提出了热处理生产零污染、能源零损耗和质量零分散度的目标,并分别从质量、能源、环境等方面总结了先进的管理方法.