Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

β-Cyclodextrin facilitates simultaneous analysis of six bioactive components in Rhizoma Smilacis Glabrae by capillary zone electrophoresis

A cyclodextrin-modified capillary zone electrophoretic method was developed for the separation and determination of trans-resveratrol, astilbin, taxifolin, shikimic acid, syringic acid and ferulic acid in Rhizoma Smilacis Glabrae. A running buffer comprising 20 mM borax and 2 mM β-cyclodextrin at pH 9.46 was used. These six components were well separated from each other within 8 min at a voltage of 25 kV, temperature of 25 °C and detection wavelength of 214 nm. The relative standard deviations of migration time ranged from 0.07% to 0.30% while those of the peak area ratios ranged from 2.66% to 4.12% for six determinations of analytes at the concentration of 5 and 25 μg mL⁻¹. The correlation coefficients of the calibration curves of analytes were all >0.9990, and the recoveries were from 97.5% to 108.3%. The method was successfully applied to determine the bioactive components in 12 samples of Rhizoma Smilacis Glabrae collected from China.     

碳源在连续批式反应器中对生物养分移动的影响

连续批式操作用来研究利用不同的碳源从合成废水中移动养分(COD、 NH4-N、 NO3-N、 PO4-P)的过程,本操作包括缺氧症、缺氧的、有氧的、缺氧和有氧的(An、Ax、Ox、Ax、Ox)时期,分别持续2 h、1 h、4.5 h、1.5 h、1.5 h.葡萄糖、醋酸盐、葡萄糖和醋酸盐混合物作为碳源在机械中产生的COD∶N∶P为100∶5∶1.5,污泥稳定保存10 d.当葡萄糖和醋酸盐混合物比例是50∶50时,COD、NH4-N、NO3-N和PO4-P最大迁移率分别是96%、87%、81%和90%.     

Si和C共掺杂的SiO2薄膜的光致发光

采用双离子束溅射技术制备了Si和C共掺杂的SiO2薄膜,在N2气氛下进行了不同温度的退火处理。分析了样品在室温下的光致发光(PL)特性,在该样品中观察到分别位于410nm和470nm的两个发光峰。这两个发光峰的强度随着退火温度的变化呈现不同的变化趋势,表明两个发光峰的来源并不相同。用XRD和FTIR测试手段分析了样品的结构,认为470nm的发光来源于中性氧空位缺陷(O3≡Si～Si≡O3),而410nm的发光来源于Si1-xCx纳米晶粒与SiO2基质之间的界面缺陷。     

MnO2/SMWCNT/PANI三元复合材料的合成及其电化学电容性能

用液相沉淀法制备了二氧化锰/酸化多壁碳纳米管(MnO₂/SMWCNT)和二氧化锰/酸化多壁碳纳米管/聚苯胺(MnO₂/SMWCNT/PANI)电极材料。通过循环伏安、恒电流充放电等方法测试了样品的电化学性能。结果表明, 当MnO₂:SMWCNT:PANI的质量比为1:1:0.4时,它的电化学性能最好, 在0.1 A/g电流密度下的比电容为318.6 F/g, 氧化电流为6.02 A/g, 循环100次后电流保持率保持在92.7%。     

ZnO纳米阵列增强大功率蓝光LED出光效率的研究

采用低成本的化学溶液法在大功率GaN基蓝光LED芯片上生长ZnO纳米阵列, 以提高LED芯片的出光效率. 通过改变生长溶液中氨水及锌离子浓度实现对纳米阵列结构形貌的可控性, 进而得到不同形貌的ZnO纳米阵列. 在此基础上, 进一步研究纳米结构形貌对LED芯片出光性能的影响, 探讨纳米结构增强LED芯片发光效率的机理. 结果表明, 较高密度、锥形形貌的ZnO纳米阵列更有利于增强LED芯片的出光效率. 在优化的实验条件下, 表面沉积ZnO纳米阵列的LED芯片比普通LED的出光效率高出60%以上, 并且纳米阵列不影响LED器件的电学性能和发光稳定性.     

考虑车轮-路面接触长度的桥头跳车动力荷载分析

对车辆经过桥头错台时的动力荷载进行分析,提出考虑轮胎-路面接触长度的车轮模型,并计及车轮的滚动轨迹。结合有限元动力学分析方法,对车辆上、下桥头错台时的动力荷载进行定量分析。数值仿真表明：考虑接触长度的模型更符合车轮与路面接触的实际情况,动力荷载计算值较平缓;下桥跳车时车轮脱空的临界速度计算值大大提高,10 mm错台跳车临界速度约60 km/h;跳车动力荷载与车轮悬挂方式、车速、跳车高度等有关,可由此控制轮载冲击系数;考虑车轮-路面接触长度后,桥头错台跳车的冲击系数仍较大。车辆以30 km/h以上速度通过10 mm错台时,冲击系数超过我国桥梁规范设计值,需引起重视。     

黄酒品质评价方法的研究进展

对近年来黄酒品质、酒龄和产地鉴别评价方法的研究进展,以及近红外光谱技术、色谱技术/质谱(气相色谱和高效液相色谱)、电子感官(电子鼻和电子舌)等现代分析技术进行概述,并对评价检测方法的发展趋势进行了讨论和展望。     

Electron holography study of remanence states in exchange-biased MnPd/Fe bilayers grown epitaxially on MgO(001)

We investigated magnetic remanence states of epitaxially grown, exchange-biased MnPd/Fe bilayers by electron holography emphasizing the crystallographic orientations of the layers. Thin-foil transmission electron microscopy (TEM) specimens were carefully prepared along both hard and easy axes of the Fe layer. The ex situ magnetization-reversal process was carried out using the TEM specimens, and magnetic flux densities of the ultra-thin Fe layers were evaluated at different remanence states. We show that a spin configuration in the TEM specimens is determined by the competition between an exchange coupling at the MnPd/Fe bilayer interface, shape anisotropy of TEM specimens and intrinsic magnetocrystalline anisotropy of Fe.     

白酒香味成分研究进展

白酒是世界七大蒸馏酒之一，白酒的香味成分决定着白酒的风格和质量。本文综述了白酒香味成分的研究技术和白酒香型的分类等方面研究成果，并详细介绍了白酒香味成分分析方面的研究进展。指出了白酒风味质量的稳定和提高有赖于对白酒香味成分种类及其作用的定性和定量研究。