Kinetics of batch production of single-cell protein from cheese whey

A kinetic model for single-cell protein batch fermentation was developed using the numerical simultaneous integration approach of the fourth-order Runge-Kutta method. The model takes into account the effect of substrate inhibtion, maintenance energy, and cell death on the cell growth and substrate utilization during the fermentation process. The theoretical results obtained from the model compared well with the experimental data. The model was used to study the effect of the initial substrate concentration on the lag period, fermentation time, specific growth rate, population size, and cell productivity of batch fermentation. Increasing the initial substrate concentration increased the lag period and fermentation time and decreased the specific growth rate and cell yield. The growth limiting substrate concentration was 2.9 g/L, whereas the growth inhibiting substrate concentration was 69.0 g/L. Increasing the initial substrate concentration above 150 g/L significantly decreased the yeast population size.     

Template‐Free Hydrothermal Synthesis of Mesoporous MgO Nanostructures and Their Applications in Water Treatment

The controlled synthesis of Mg(OH)₂ nanowires and microflowers composed of nanoplates was successfully achieved by a template‐free hydrothermal synthetic method. It was found that the reaction medium played a crucial role in the morphological control of the precursor nanostructures. The high polarity of water molecules favored the polar growth of the precursor, resulting in the formation of nanowires with a diameter of 80 nm, whereas a mixed water/ethanol medium with a lower degree of polarity led to the formation of microflowers. Moreover, mesoporous MgO nanostructures could be obtained by further annealing these as‐prepared precursors in air at 500 °C for 2 h. During thermal treatment, the wire‐ and flower‐like morphologies were retained. Porosity formation was due to thermal decomposition of Mg(OH)₂ and release of H₂O. Both the mesoporous MgO nanowires and microflowers showed superior ability of adsorbing the organic dye methyl orange, and thus they are promising candidates for polluted water treatment.     

骨断裂力学概述

本文涉及近年来骨断裂力学的发展成果.对建立在张开型和剪切型断裂能基础上的方法作了回顾,并讨论了密度、试件厚度和裂纹速度对骨断裂的影响.最后简述了人股骨的试验研究.      

间硝基苯胺晶体的定向生长及光学性能研究

采用过冷熔体定向约束生长方法生长了尺寸约为30×15×8 mm3的块状间硝基苯胺晶体,并对生长晶体的光学均匀性、光学透过率、二次谐波转换效率以及激光损伤阈值等性能进行了测试.结果表明:生长的间硝基苯胺晶体在500～1150 nm波段内的光学透过率均在92;以上;最高二次谐波转换效率达到69.6;;单点激光脉冲损伤阈值分别为19.8 GW/cm2(输入光波为1064 nm)和45.3 GW/cm2(输入光波为532 nm).采用过冷熔体定向约束生长的间硝基苯胺晶体适合用作Nd: YAG激光的二次倍频器件,也适于作500～1150 nm波段的光学调制器件.     

高等教育经费投入对经济增长的驱动力影响实证研究——基于西北五省数据的LMDI分解

以高等教育为主体的人力资本投入对地区经济增长具有推动力已成为经济发展在理论和实践上的普遍认识.首次将LMDI分解法引入高等教育经费投入与GDP增长之间的动态关系实证研究,通过构建GDP总量分解模型,深入分析二者之间内在的因果驱动关系.分析结果表明,对我国而言,代表高等教育经济投入总量的活动效应对GDP变动贡献最大,是主要驱动力;代表教育经费在区域问分布的结构效应对GDP变动影响很小;代表单位教育经费驱动效率的效率效应对GDP增长起到了重要促进作用.     

金刚石中氦、氢含量的变化及在金刚石生长中的意义

天然金刚石自中心至边缘的显微傅里叶变换红外光谱研究表明:氮和氢在金刚石中的分布是不均匀的,这说明金刚石在整个生长过程中的物质环境是有差异的;中心至边缘的含氮总量、C-H键含量的总体降低趋势表明金刚石的生长过程是一个氮、氢的消耗过程,而中部的升高变化说明金刚石生长环境中存在氮、氢的补充,但氮补充得比氢更早一些.据此,可以将金刚石的生长过程划分为早期成核与长大、中期长大及末期长大三个阶段,其中早期和末期是氮和氢的消耗阶段,中期需要进行氮和氢的补充,且氮应该更早补充.氢对金刚石的生长是有利的,氢和氮不是以氮氢化合物的形式存在于金刚石生长的物质环境中,这暗示着在高温高压合成金刚石中欲引入氢,应当避免氮氢化合物的形成.     

Electromechanical cracking in ferroelectrics driven by large scale domain switching

Experimental results indicate three regimes for cracking in a ferroelectric double cantilever beam (DCB) under combined electromechanical loading. In the loading, the maximum amplitude of the applied electric field reaches almost twice the coercive field of ferroelectrics. Thus, the model of small scale domain switching is not applicable any more, which is dictated only by the singular term of the crack tip field. In the DCB test, a large or global scale domain switching takes place instead, which is driven...     

基于单孔洞近似的高纯铝部分层裂实验的数值模拟研究

基于单孔洞近似,对不同撞击速度下高纯铝的部分层裂实验进行了数值模拟研究,讨论了微孔洞长大对波传播的影响及其在自由面速度波剖面上的表现. 通过分析微孔洞周围的应力场变化,认识到实测自由面速度波剖面出现"回跳"特征并不能说明材料发生完全层裂,其直接原因是样品内部微孔洞长大所引起的局部卸载效应. 将计算得到的自由面速度波剖面和微孔洞相对体积与实验结果进行了对比分析,发现两者均符合很好,表明采用单孔洞增长来近似描述部分层裂样品中随机损伤发展及其对波传播的影响是可行的. 关键词： 层裂 孔洞增长 自由面速度波剖面 微孔洞相对体积     

Synthesis, growth and characterization of a new derivative 4-ethoxy-N-methyl-4-stilbazolium besylate monohydrate single crystal

A new organic material 4-ethoxy-N-methyl-4-stilbazolium besylate monohydrate, a derivative in the stilbazolium family, known for efficient nonlinear optical materials, has been synthesized for the first time. Employing the slow evaporation technique, optically transparent good quality single crystals of size 15 mm×10 mm×5 mm were grown from methanol. The cell dimensions obtained by single crystal X-ray diffraction studies reveal that the crystal belongs to the monoclinic system. Functional groups of the grown crystal were identified from FTIR and NMR spectral analysis. UV−vis−NIR studies show that the crystal is transparent in the wavelength range 460-1100 nm. The thermal stability of the compound was determined by thermal analyses of the specimen.     

MgO和Si上NbN超薄薄膜的生长研究

我们在单晶MgO(100)、Si(100)和SiOx/Si基片上成功生长了纳米厚度的超薄NbN薄膜,利用现代分析手段:X射线衍射(XRD)、透射电子显微镜(TEM)、原子力显微镜(AFM)等技术分析研究了所制备的超薄NbN薄膜的微观结构、厚度、表面界面情况等物理特性。研究表明,在MgO(100)基片上获得了外延生长的单晶NbN超薄薄膜,在Si(100)和SiOx/Si基片上获得的是多晶NbN超薄薄膜。厚度均约6nm左右。这些超薄薄膜的超导转变温度分别为:MgO上薄膜是14.46K,Si和SiOx上薄膜分别是8.74K和9.01K.