High pressure γ-to-β phase transition in bulk and nanocrystalline In2Se3

Pressure-dependent phase transitions of In₂Se₃ bulk powders and nanowire samples were studied at room temperature using synchrotron X-ray diffraction and a diamond anvil cell. γ-In₂Se₃, metastable under ambient conditions, transforms into to the stable high pressure β phase between 2.8 and 3.2?GPa in bulk powder samples and at slightly higher pressures, between 3.2 and 3.7?GPa, in nanowire samples. While the γ phase bulk modulus is similar to that of the β phase, the decrease due to pressure in the unit cell parameter ratio, c/a, is less than half the decrease seen in the β phase. First-principles calculations show that γ-In₂Se₃ has a higher energy and unit-cell volume than β-In₂Se₃, consistent with the experimental observations.     

激光相干合成中单元的相位和振幅波动对合成光束远场分布的影响

运用傅里叶光学分析法推导出系统抖动造成单个光源的相位和振幅发生波动时的远场光强表达式,以1维阵列为例分析了系统抖动对远场的影响。研究表明:随着参与合束的发光单元数目的增加,尖峰变锐,能量更集中;系统抖动引起了远场峰值光强的减少,出现了本底现象,破坏了远场的对称性和光束质量;激光阵列单个光源的相位随机抖动应该控制在3/8范围内;相干合束发光单元数目越多,系统抖动对远场的影响越小。     

化学激光器用文氏咀流场特性的数值模拟

 基于现有的文氏咀流量供给管道,提取出轴对称2维计算模型,计算了不同背压下文氏咀及下游管道的流场特性。计算结果显示,随着背压的升高,激波在管道内经历了3种状态,在直管道内为斜激波,到转接段时为拟正激波,进入文氏咀后则为正激波。在进行文氏咀流量计的设计时,应尽量将正激波控制在文氏咀喉道或向下游延伸的一小段距离内,此时是文氏咀的最佳工作状态。另外,采用壁面开孔法在文氏咀下游选取测压点时,为了准确测量截面上的静压,应将测压点选取在距离直管道入口数倍管径处,一般不低于8倍管径。     

乳状液膜分离肌酐的研究

以液体石蜡为膜相、以氧化环糊精为内相捕捉剂制备一种新的乳状液膜，尝试运用其清除分离肌酐。实验发现当外相肌酐溶液浓度为1．3g/L，载体月桂醛含量为5％，内相氧化环糊精浓度为10％时，乳状液膜吸附容量为22．5mg／g。内相氧化环糊精的浓度对单位吸附量起决定作用。此种吸附剂对氨基酸吸附量仅为肌酐的1／10，这为其在含大量氨基酸的人体环境中有效的清除肌酐提供了优良的选择性。     

收缩段线型对超音速喷管氟原子气相复合的影响

使用移轴维氏曲线和双三次方曲线作为收缩段线型分别设计了两种环形 HYLTE主喷管，给出了环形HYLTE喷管三维的多组分有反应湍流场的控制方程、边界条件和 模拟区域的选择. 计算结果表明，这两种线型的喷管均能避免边界层的分离，获得均匀的流 场分布及相同的出口马赫数分布，但移轴维氏曲线在收缩段前部收缩快速，气流速度相应较 快，因此F原子的气相复合程度弱于另外一种收缩段设计的喷管，相应地，使用移轴维氏曲 线设计的喷管F原子流量比另外一种喷管高5%左右, 因此使用移轴维氏曲线作为环形HYLTE主喷管收缩段的设计有助于提高化学激光器的效率.     

Swine Manure-Based Pilot-Scale Algal Biomass Production System for Fuel Production and Wastewater Treatment—a Case Study

Integration of wastewater treatment with algae cultivation is one of the promising ways to achieve an economically viable and environmentally sustainable algal biofuel production on a commercial scale. This study focused on pilot-scale algal biomass production system development, cultivation process optimization, and integration with swine manure wastewater treatment. The areal algal biomass productivity for the cultivation system that we developed ranged from 8.08 to 14.59 and 19.15–23.19 g/m²?×?day, based on ash-free dry weight and total suspended solid (TSS), respectively, which were higher than or comparable with those in literature. The harvested algal biomass had lipid content about 1.77–3.55 %, which was relatively low, but could be converted to bio-oil via fast microwave-assisted pyrolysis system developed in our lab. The lipids in the harvested algal biomass had a significantly higher percentage of total unsaturated fatty acids than those grown in lab conditions, which may be attributed to the observed temperature and light fluctuations. The nutrient removal rate was highly correlated to the biomass productivity. The NH₃-N, TN, COD, and PO₄-P reduction rates for the north-located photo-bioreactor (PBR-N) in July were 2.65, 3.19, 7.21, and 0.067 g/m²?×?day, respectively, which were higher than those in other studies. The cultivation system had advantages of high mixotrophic growth rate, low operating cost, as well as reduced land footprint due to the stacked-tray bioreactor design used in the study.     

Shifted convolution of cusp-forms with $$\theta $$-series

In this paper we apply some simple approaches to improve a recent result of Luo on the shifted convolution sum of the Fourier coefficients of a cusp form and a theta series. A mean square formula is established in order to explore the right order of magnitude of this shifted convolution sum.     

On the Distribution of r-Full and l-Free Integersin Short Intervals

 We study the distribution of r-full and l-free numbers in short intervals () and sharpen Kr?tzel’s and Wu’s results.     

CeO2掺杂MgO-ZrO2陶瓷的阻抗特性

利用共沉淀法合成了CexMg0.06Zr（1-x）O1.94（x=0～16%）超细粉体,压制成型后分别在1300,1400,1500,1600 ℃下,保温3 h烧结.对烧结样品用XRD研究了相组成.在不同温度下（700～1200 ℃）测试了CexMg0.06Zr（1-x）O1.94陶瓷的交流阻抗谱.结果表明： 随着CeO2掺入量的增加,促进了CexMg0.06Zr（1-x）O1.94陶瓷立方相结构的形成,扩展了氧离子迁移的通道,降低了导电相粒子间的接触电阻,减低了氧离子的迁移阻碍,从而使得 CexMg0.06Zr（1-x）O1.94陶瓷的导电性能提高.     

On a Diophantine Inequality Over Primes (II)

In this short note we prove that if 1 < c < 81/40, c ≠ 2, N is a large real number, then the Diophantine inequality |p₁^c+p₂^c+p₃^c+p₄^c+p₅^c-N| < log^-1 N \vert p_1^c+p_2^c+p_3^c+p_4^c+p_5^c-N\vert < \log^{-1} N is solvable, where p ₁,···,p ₅ are primes.