Interfacial tension approach toward drug loading with two-dimensional crosslinked polymer embedded gold: Adsorption kinetics evaluation

Interfacial tension of drugs with hydrophilic polymer (A) embedded gold resulting into selective drug adsorption, which also affected the drug adsorption kinetics. Two-dimensional crosslinked polymer embedded gold was synthesized for drug loading application in an acidic buffer. Lower interfacial tension of pantoprazole sodium (B) revealed the exponential loading inversely loading was gradual for chloroquine (C) having more interfacial tension with adsorbent. Initial 2 h was the exponential adsorption period for a pantoprazole sodium whereas exponential adsorption begins after 12 h for a chloroquine. Monolayer drug adsorption was obtained because Langmuir adsorption isotherm was obeyed by both drugs. Moreover, pseudo first- and pseudo second-order kinetics was also evaluated which demonstrated that reactive sites of the adsorbent are homogeneous and drug adsorption mechanism is chemisorption and not the physisorption. Thermal analysis was evaluated to confirm the polymer thermostability and glass transition temperature during catalytic applications in thermal reactions.     

Spontaneous growth of GaN nanowire nuclei on N- and Al-polar AlN: A piezoresponse force microscopy study of crystallographic polarity

The polarity of gallium nitride (GaN) nanowire nuclei grown on AlN layers was studied by piezoresponse force microscopy (PFM). N- or Al-polar AlN layers were grown by molecular beam epitaxy (MBE) on Si (111) substrates by use of Al- or N-rich growth conditions, respectively. Short and low density GaN nanowires were then grown on each AlN polarity type. PFM measurements verified the expected AlN layer polarity and further indicated that predominantly N-polar nanowires are produced for growth on both AlN polarity types. Cross-section scanning transmission electron microscopy (STEM) images further reveal that the nanowires on Al-polar AlN films are nucleated on regions in the AlN layer that contain inversion domains, which propagate into the GaN nanowire nuclei. PFM measurements were found to be a convenient technique for mapping the polarity of a statistically significant number of individual GaN nanowires.     

Feature integration across space, time, and orientation.

The perception of a visual target can be strongly influenced by flanking stimuli. In static displays, performance on the target improves when the distance to the flanking elements increases—presumably because feature pooling and integration vanishes with distance. Here, we studied feature integration with dynamic stimuli. We show that features of single elements presented within a continuous motion stream are integrated largely independent of spatial distance (and orientation). Hence, space-based models of feature integration cannot be extended to dynamic stimuli. We suggest that feature integration is guided by perceptual grouping operations that maintain the identity of perceptual objects over space and time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microstructures of InN film on 4H-SiC (0001) substrate grown by RF-MBE

InN film was grown on 4H-SiC (0001) substrate by RF plasma-assisted molecular beam epitaxy (RF-MBE). Prior to the growth of InN film, an InN buffer layer with a thickness of ~ 5.5 nm was grown on the substrate. Surface morphology, microstructure and structural quality of InN film were investigated. Micro-structural defects, such as stacking faults and anti-phase domain in InN film were carefully investigated using transmission electron microscopy (TEM). The results show that a high density of line contrasts, parallel to the growth direction (c-axis), was clearly observed in the grown InN film. Dark field TEM images recorded with diffraction vectors g = 1120 and g = 0002 revealed that such line contrasts evolved from a coalescence of the adjacent misoriented islands during the initial stage of the InN nucleation on the substrate surface. This InN nucleation also led to a generation of anti-phase domains.     

分布式电源多点接入配电系统的集成保护

针对分布式电源多点接入的配电系统,提出了一种基于暂态极性保护原理的集成保护新方案。暂态极性比较保护是运用小波变换提取故障暂态高频信号的某一频段信息作为故障判断的依据,通过比较暂态高频信号的极性,迅速准确判断出故障位置。将暂态极性比较保护原理应用于配电网集成保护方案中,以母线作为载体构建集成保护单元,利用本地故障信息和相邻保护单元故障信息对母线各出线以及线路两端信号的极性进行比较,从而对母线故障和线路故障进行判断。与此同时,集成网络保护单元提取多点信息,对整体区域暂态信号极性进行综合比较,实现对故障的快速定位与隔离,为本地保护提供后备保护。最后,利用MATLAB软件对其进行了仿真分析,仿真结果验证了此保护方案的正确性和可行性。     

铝合金LB-VPPA复合焊接热源模型

激光-变极性等离子弧(Laser beam-variable polarity plasma arc,LB-VPPA)属双高能束新型复合焊接热源。采用Y4-S2型高速摄像检测了LB-VPPA复合焊接热源形态,在理论分析复合热源产热机理的基础上,利用Fortran语言对SYSWELD软件热源模型进行二次开发,建立能够实现正、反极性循环加载的LB-VPPA复合焊接热源模型。经与实际焊接熔池形状对比研究发现,熔池上部采用双椭球体热源,下部采用三维锥体热源,同时在小孔根部植入圆柱体热源的组合式热源模型与实际LB-VPPA复合焊接热源吻合。从模拟6 mm厚7A52铝合金板的VPPA焊和LB-VPPA复合焊接温度场分布结果发现,LB-VPPA复合焊能量更为集中,可以在平焊位置下实现穿孔型焊接。经实际焊接工艺试验验证了上述模拟结果的准确性。因此建立精确的LB-VPPA复合焊接热源模型对开展厚板铝合金LB-VPPA复合高效焊接提供强有力的理论支持。     

场击穿式TVS时延特性的测量与分析

触发真空开关(TVS)是脉冲功率技术中的重要控制元件,为满足对TVS时延及可靠性等提出的更高要求,研究了场击穿式TVS时延特性。时延分为触发时延和导通时延两部分,时延及其分散性主要受主间隙电压、触发能量和主电极极性配置等因素的影响。实验研究表明,极性配置对TVS时延特性有很大的影响,主间隙电压为正,TVS可靠性高且存在一个稳定工作区域,在这个稳定工作区内,主间隙电压对其触发时延影响不大,且触发能量增大能改善TVS时延特性。     

高频脉冲变极性焊接电源及电弧压力分析

采用变极性和高频脉冲电路叠加,设计了一套变极性和高频脉冲复合电流输出特性的焊接电源,将高频脉冲电弧特性引入变极性焊接过程.建立电弧压力数学模型,结合具体工艺试验,分析了高频脉冲电流对于变极性焊接电弧特性的改善.结果表明,在相等电流有效值的情况下,电弧压力随脉冲频率的提高而增加,高频脉冲电流频率达到5kHz附近时,弧柱区电弧压力较常规直流电弧提高2倍左右,电弧的挺度和能量密度都有所增加,为进一步研究高频脉冲变极性焊接方法在铝合金焊接中的应用提供了理论依据.     

水溶性香豆素衍生物的合成及其光谱性能

4-甲氧基水杨醛和丙二酸二乙酯反应合成了中间体7-甲氧基香豆素-3-甲酸,该中间体与二乙醇胺反应合成了水溶性香豆素类衍生物7-甲氧基香豆素-3-甲酰二乙醇胺。用核磁共振(NMR)表征了产物的结构,研究了其紫外吸收光谱和荧光光谱。