3-D Simulations of Electroosmotic Sample Migration in Microchannels: Effects of Surface and Solution Property Variations

This article reports a 3-D numerical study on the effects of variation of surface and solution properties in microchannels on sample dispersion during electroosmotic migration. Zeta potential variations across and along the microchannel is found to generate a shear flow that increases the rate of dispersion of a sample plug. The electric conductivity variation due to the presence of a sample plug resulted in a complicated distortion of the sample plug due to the interaction between flow fields, electric potential, and species concentration. A study on the appropriateness of the 1-D Taylor dispersion method in microchip capillary electrophoresis modeling was also carried out.     

气升式环流反应器实验及三维模拟

利用Fluent软件对气升式环流反应器进行三雏全尺寸的数值模拟,采用欧拉多相流模型和标准k-ε模型模拟反应器内气液两相流动,得到了反应器内流场的详细分布.在此基础上还结合FLOW 3D软件模拟物理流动现象,得到了直观的真实清晰动画,而传统的实验很难测得相关具体的数据.两种数值模拟结果与文献实验值吻合较好,说明了数值模拟的可靠性.     

3-D solar cells by electrochemical-deposited Se layer as extremely-thin absorber and hole conducting layer on nanocrystalline TiO2 electrode

Ag₂S quantum dots were deposited on the surface of TiO₂ nanorod arrays by a two-step photodeposition. The prepared TiO₂ nanorod arrays as well as the Ag₂S deposited electrodes were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope, suggesting a large coverage of Ag₂S quantum dots on the ordered TiO₂ nanorod arrays. UV–vis absorption spectra of Ag₂S deposited electrodes show a broad absorption range of the visible light. The quantum dot-sensitized solar cells (QDSSCs) based on these electrodes were fabricated, and the photoelectrochemical properties were examined. A high photocurrent density of 10.25 mA/cm² with a conversion efficiency of 0.98% at AM 1.5 solar light of 100 mW/cm² was obtained with an optimal photodeposition time. The performance of the QDSSC at different incident light intensities was also investigated. The results display a better performance at a lower incident light level with a conversion efficiency of 1.25% at 47 mW/cm².     

凸截面注射成型全三维充填和纤维取向模拟研究

选用15 %玻璃纤维增强聚酰胺6（PA6）复合材料,根据Folgar-Tucker理论模型,研究了凸形截面零件全三维注射成型充填流动行为和纤维取向分布规律。结果表明,全三维模拟技术可以有效反映注射成型充填的流动形态和喷泉效应;凸形截面表层纤维沿剪切方向取向分布,且制品大端部分的纤维取向程度比小端部分差;3个坐标方向上的纤维取向分布非常复杂,沿x轴负方向（即充填方向）,随充填长度的增加,纤维取向程度先增大后减小;沿y轴方向,随着距中心距离的增大,凸形截面小端部分的纤维取向程度由内向外逐渐增大,而大端部分的纤维取向程度先增大后减少;沿z轴方向,凸形截面小端部分的纤维取向由内向外呈增大趋势,而大端部分的纤维取向程度却逐渐减小。     

电动三维工作台在涂装作业中的应用

主要阐述了电动三维工作台在大型零部件涂装作业中的应用。     

挡板偏心度对振荡流反应器三维流场对称性影响的研究

借助商业计算流体力学软件CFX,运用有限容积法离散振荡流反应器（OFR）的单个腔室,对具有理想对称几何边界和轻微挡板偏心度的OFR在系列振荡雷诺数（Reo）下的三维流场进行了仿真模拟,并将其可视化计算流场与实验流场进行比较,研究了OFR几何边界上的非对称因素对其内三维流场流型的影响.模拟结果表明在有效消除计算随机误差以及误差积累的情况下,几何边界理想对称OFR内的三维层流流场呈现出良好的中心对称性和周向均匀性,而湍流流场中心对称的同时呈现出周向非均匀结构--在圆周上生成8个中心对称排列的横向漩涡,其形态与Couette流中的泰勒涡类似.另外,挡板偏心度对OFR内的振荡流场的对称性有重要影响：在较大的下,其三维流场生成非对称性显著的大尺度漩涡对;并且随的增大,流场的非对称程度加大而增加.     

A study of solid behavior in spouted beds using 3-D particle tracking

A non-invasive γ-ray emission system, employing eight NaI detectors, has been developed to follow the motion of a single radioactive particle in a three-dimensional spouted bed reactor. The count-rates measured simultaneously by the detectors are converted into tracer coordinates (x, y, z) using a pre-established calibration model which accounts for every physical and geometrical aspects involved in the spouting facility. Typically four hundred thousands successive coordinates, obtained over 3.5 hours of particle tracking, are used for determining the average particle velocity field and other hydrodynamic quantities such as the cycle time distribution, the spout shape and the solid exchange distribution at the spout boundary, which could not be evaluated accurately using any available techniques.     

分形及分维在单轴向三维编织复合材料拉伸实验中的应用

基于分形几何的计盒维数研究了三维编织复合材料拉伸实验的断裂样照,结果表明,该材料的断裂曲线具有统计自相似性,在不同的尺度范围内具有不同的空间分布格局;而计盒维数定量地表征了其尺度变化规律;准静态和低应变率加载条件下材料的分维数较大,表明其空间占据程度较大,曲线弯曲结构复杂,这是因为低应变率加载时材料内部结构断裂时间不同造成;而高应变率加载时,断裂曲线分维数较小,曲线空间占据小,弯曲结构比较简单,这是由高应变率加载时材料内部结构断裂时间差异缩小造成。     

具有长短叶片离心泵的全三维湍流数值模拟

使用FLUENT软件模拟计算具有长短叶片叶轮的离心泵的全三维流场。选用多重参考坐标系及标准k-ε湍流模型,计算对包括导入管、叶轮、泵壳及出水管在内的整个离心泵系统。计算结果表明,在大部分长短叶片的通道内,射流区偏向于叶片背面,尾迹区则位于叶片工作面出口附近。泵叶轮各通道的流量、流速及压力等流动参数的分布表现出明显的非对称性,流动参数的大小与叶轮、泵壳的相对位置密切相关。将泵性能的预测值与实测值作了对比,以验证计算结果的准确性。     

Effects of particle properties on flow structure in a 2-D circulating fluidized bed: Solids concentration distribution and flow development

The effects of particle properties (particle density, size and sphericity) on solids concentration in a 2-D riser were comprehensively investigated by measuring the axial and lateral solids concentration with an optical fiber probe. In this study, solids concentration of different types of particles shows that heavier particles have higher solids concentration laterally and axially than lighter particles; larger particles result in more compact solids distribution and such size effect is more evident at the riser bottom; more spherical particles lead to higher solids concentration. Various forces acting on particles and the change in the slip velocity between gas and particles were used to explain the effects of particle properties on solids distribution.     

QLED用空穴传输层WO3的形貌调控和光电性能研究

采用溶剂热法在FTO导电玻璃上制备WO3薄膜,通过改变溶剂和添加剂的种类,调控WO3的微观形貌、光学性质和电学性质,以期作为空穴传输材料应用在QLED器件中.利用XRD、FE-SEM、紫外可见分光透射光谱、霍尔测试等方法分析表征样品.实验结果表明,通过溶剂热法成功制备了不同形貌的WO3薄膜,其光学透过率高,载流子传输速率得到明显提高,有望应用在QLED器件中进而提高QLED的器件效率.其中,采用水作为溶剂,并添加2 mL乙腈和0.07 g尿素的溶剂热条件制备的WO3薄膜其载流子传输速率最高为2.678×102 cm2·Vs-1,导电性能最高,电阻率为5.334×10-2 Ω·cm.     

Regulation of Epigenetic Modifications in the Placenta during Preeclampsia: PPARγ Influences H3K4me3 and H3K9ac in Extravillous Trophoblast Cells

The aim of this study was to analyze the expression of peroxisome proliferator-activated receptor γ (PPARγ) and retinoid X receptor α (RxRα), a binding heterodimer playing a pivotal role in the successful trophoblast invasion, in the placental tissue of preeclamptic patients. Furthermore, we aimed to characterize a possible interaction between PPARγ and H3K4me3 (trimethylated lysine 4 of the histone H3), respectively H3K9ac (acetylated lysine 9 of the histone H3), to illuminate the role of histone modifications in a defective trophoblast invasion in preeclampsia (PE). Therefore, the expression of PPARγ and RxRα was analyzed in 26 PE and 25 control placentas by immunohistochemical peroxidase staining, as well as the co-expression with H3K4me3 and H3K9ac by double immunofluorescence staining. Further, the effect of a specific PPARγ-agonist (Ciglitazone) and PPARγ-antagonist (T0070907) on the histone modifications H3K9ac and H3K4me3 was analyzed in vitro. In PE placentas, we found a reduced expression of PPARγ and RxRα and a reduced co-expression with H3K4me3 and H3K9ac in the extravillous trophoblast (EVT). Furthermore, with the PPARγ-antagonist treated human villous trophoblast (HVT) cells and primary isolated EVT cells showed higher levels of the histone modification proteins whereas treatment with the PPARγ-agonist reduced respective histone modifications. Our results show that the stimulation of PPARγ-activity leads to a reduction of H3K4me3 and H3K9ac in trophoblast cells, but paradoxically decreases the nuclear PPARγ expression. As the importance of PPARγ, being involved in a successful trophoblast invasion has already been investigated, our results reveal a pathophysiologic connection between PPARγ and the epigenetic modulation via H3K4me3 and H3K9ac in PE.     

Simulation of aerosol dynamics and transport in chemically reacting particulate matter laden flows. Part II: Application to CVD reactors

A highly computationally efficient and accurate semi-implicit numerical technique based on the concept of operator splitting (described in detail in Part I of this paper) has been used to solve the General Dynamic Equation in complex, non-isothermal reacting flows to predict aerosol dynamics and particle deposition rates. The numerically efficient algorithm has made it possible to solve the GDE in complex two-dimensional and three-dimensional simulations, hitherto not done due to the computational intensiveness. Simulations have been performed to elucidate the role of different process parameters on aerosol dynamics and particle deposition rates in idealized and commercial horizontal single wafer CVD reactors. Specifically, it has been demonstrated that the gas phase kinetics, particle formation, growth and deposition rates result in very complex aerosol size distributions in the reactor that cannot be captured with simplistic models that do not couple the GDE to the detailed flow field simulations. Guidelines for minimizing particle contamination in CVD reactors on the basis of the simulation results are presented.     

3-D structure of the D153G mutant of Escherichia coli alkaline phosphatase: an enzyme with weaker magnesium binding and increased catalytic activity

The substitution of aspartate at position 153 in Escherichiacoli alkaline phosphatase by glycine results in a mutant enzymewith 5-fold higher catalytic activity (k_cat but no change inKm at pH 8.0 in 50 mM Tris-HCl. The increased k_cat is achievedby a faster release of the phosphate product as a result ofthe lower phosphate affinity. The mutation also affects Mg²⁺binding, resulting in an enzyme with lower metal affinity. The3-D X-ray structure of the D153G mutant has been refined at2.5 Å to a crystallographic Rfactor of 16.2%. An analysisof this structure has revealed that the decreased phosphateaffinity is caused by an apparent increase in flexibility ofthe guanidinium side chain of Argl66 involved in phosphate binding.The mutation of Aspl53 to Gly also affects the position of thewater ligands of Mg²⁺, and the loop Glnl52–Thrl55 is shiftedby 0.3 Å away from the active site. The weaker Mg²⁺ bindingof the mutant compared with the wild type is caused by an alteredcoordination sphere in the proximity of the Mg²⁺ ion, and alsoby the loss of an electrostatic interaction (Mg²⁺.COO^-Aspl53)in the mutant Its ligands W454 and W455 and hydroxyl of Thrl55,involved in the octahedral coordination of the Mg²⁺ ion, arefurther apart in the mutant compared with the wild-type     

Purification and Characterization of Aporphine Alkaloids from Leaves of Nelumbo nucifera Gaertn and Their Effects on Glucose Consumption in 3T3-L1 Adipocytes

Aporphine alkaloids from the leaves of Nelumbo nucifera Gaertn are substances of great interest because of their important pharmacological activities, particularly anti-diabetic, anti-obesity, anti-hyperlipidemic, anti-oxidant, and anti-HIV’s activities. In order to produce large amounts of pure alkaloid for research purposes, a novel method using high-speed counter-current chromatography (HSCCC) was developed. Without any initial cleanup steps, four main aporphine alkaloids, including 2-hydroxy-1-methoxyaporphine, pronuciferine, nuciferine and roemerine were successfully purified from the crude extract by HSCCC in one step. The separation was performed with a simple two-phase solvent system composed of n-hexane-ethyl acetate-methanol-acetonitrile-water (5:3:3:2.5:5, v/v/v/v/v). In each operation, 100 mg crude extracts was separated and yielded 6.3 mg of 2-hydroxy-1-methoxyaporphine (95.1% purity), 1.1 mg of pronuciferine (96.8% purity), 8.5 mg of nuciferine (98.9% purity), and 2.7 mg of roemerine (97.4%) respectively. The chemical structure of four aporphine alkaloids are identified by means of electrospray ionization MS (ESI-MS) and nuclear magnetic resonance (NMR) analysis. Moreover, the effects of four separated aporphine alkaloids on insulin-stimulated glucose consumption were examined in 3T3-L1 adipocytes. The results showed that 2-hydroxy-1-methoxyaporphine and pronuciferine increased the glucose consumption significantly as rosiglitazone did.