Enhanced affinochromism of polydiacetylene monolayer in response to bacteria by incorporating CdS nano-crystallites

By incorporating bio-specific receptors, such as p-10,12-pentacosadiyne-1-N-(3,6,9-trioxaundecylamide)-alpha-D-mannopyranoside (MPDA), into 10,12-pentacosadiyonic acid (PDA) monolayer, the MPDA/PDA monolayer underwent affinochromatic transition in response to the bacteria binding to the receptor. Here, we described a new method to study the membrane/macromolececular interaction between Escherichia coli (E. coli) and mannose and its relative affinochromism by modifying MPDA/PDA with CdS nano-crystallites (MPDA/PDA-CdS). CdS not only triggered the strong tropism of the bacteria but also reduced the rigidity of the MPDA/PDA backbone, resulting in the enhanced affinochromism. This discovery might be of significance in basic biophysical studies of membrane/macromolececular and designing novel biosensor.     

Hydrothermal synthesis and characterization of NiS flower-like architectures

Under the influence of thiocyanate anions (SCN^?) and cetyltrimethyl ammonium bromide (CTAB), NiS flower-like architectures were successfully synthesized by a one-step hydrothermal method. The synthesized flower-like architectures, with a multilayered and highly ordered texture, have diameters of several micrometers. X-ray powder diffraction (XRD) shows that the NiS flower-like architectures are rhombohedral crystalline. On the basis of condition-dependent experiments, the diffusion-limited aggregation (DLA) model and cage effect were used to explain the growth process of rhombohedral crystalline NiS flower-like architectures. Magnetic measurements showed that the coercivity (H_c) of the as-obtained NiS flower-like architectures was 102.14 Oe.     

The synthesis of a new cardiac sympathetic nerve imaging agent N-[11C]CH3-dopamine and biodistribution study

In this study, we synthesized and characterized N-[¹¹C]methyl-dopamine ([¹¹C]MDA) for cardiac sympathetic nerve imaging. [¹¹C]MDA was synthesized by direct N-methylation of dopamine with [¹¹C]methyl iodide and purified by semi-preparation reverse high pressure liquid chromatography (HPLC). The total synthesis time was 45 min including HPLC purification. The radiochemical yields of [¹¹C]MDA was 20 ± 3 %, without decay correction. The radiochemical purity was >98 % and the specific activity was about 50 GBq/mmol. The biological properties of [¹¹C]MDA were evaluated by biodistribution study in normal mice. PET imaging was performed in healthy Chinese mini-swines. Biodistribution study showed that [¹¹C]MDA had high myocardium uptake. PET/CT imaging showed [¹¹C]MDA had clear and symmetrical myocardium uptake, which was blocked obviously by injecting imipramine hydrochloride. [¹¹C]MDA would be a promising candidate of radiotracer for cardiac sympathetic nervous system imaging.     

1,1-二苯基乙烯存在下无皂乳液聚合制备磁性复合微球

报道了一种制备磁性复合微球的方法——DPE法.在自由基控制剂1,1-二苯基乙烯(DPE)存在条件下,甲基丙烯酸甲酯(MMA)与丙烯酸(AA)发生无皂乳液聚合,制备能与Fe3O4粒子相螯合的活性短链共聚物,加入Fe3O4粒子把短链共聚物引到其表面,引发其它单体继续在Fe3O4粒子表面聚合,制备磁性复合微球.研究了AA、DPE、引发剂及Fe3O4粒子加入量等对制备磁性复合微球的影响.并在此基础上,对优化后工艺制备的磁性复合微球进行了TEM、TGA及磁响应性表征.结果表明,利用该新的方法制备出了磁含量为20%、比饱和磁化强度为32.2emu/g、平均粒径为265nm且表面不含任何杂质的磁性复合微球.     

利用偏置磁极周期会切磁铁产生边聚焦场

 利用理论分析和数值计算的方法,研究了偏置磁极周期会切磁铁产生的、可用于带状电子束宽边聚焦的边聚焦场。结果表明:增加偏置长度,减小电子束通道宽度,增大磁极轴向长度可以在基本不改变边聚焦场在x方向上分布特性的前提下提高幅值;增大电子束通道的高度,增大磁极厚度均可以减小边聚焦场在x方向上分布曲线的曲率,但同时其幅值也会降低,该降低可利用前述方法予以补偿。在对带状电子束宽边聚焦进行束匹配时,可以先进行曲率匹配,再进行幅值匹配。在进行参数选择时,应合理选择束通道高度和磁极厚度的取值,以避免束通道内的边聚焦场在x方向上的分布出现曲率反向。     

紧凑型P波段相对论返波振荡器的粒子模拟

 设计了一种紧凑型P波段相对论返波振荡器,其电动力学结构是由同轴慢波结构和同轴引出结构组成的。同轴慢波结构缩小了器件的径向尺寸;同轴引出结构缩短了器件的轴向长度,且提高了束波作用效率。通过粒子模拟研究了器件内束波作用的物理过程,模拟结果表明：器件具有结构紧凑、束波作用效率高的特点。在二极管电压700 kV,电流7 kA,导引磁场1.5 T时,器件在频率833 MHz处获得较高的微波输出,饱和后输出微波的平均功率达1.58 GW,效率约为32%,器件电磁结构尺寸仅为108 mm×856 mm。     

中等能量P波段相对论返波振荡器的理论设计与粒子模拟

提出了一种新型的中等能量P波段相对论返波振荡器,该器件将慢波结构由低波段普遍采用的同轴外波纹结构变为同轴双波纹结构,使得径向束-波作用空间扩大了2倍,一定程度上增加了器件的功率容量;另外同轴双波纹结构还较大提高了器件的时间增长率,从而有效地减小了微波输出饱和时间.经优化设计,该结构在二极管电压300 kV、电流3 kA...     

微波注入反相器基本电路的非线性效应

采用理论分析和微波注入实验相结合的方法,分别研究了以74HC04和74LVCU04A两种芯片为核心的反相器基本缓冲及数模转换电路的微波效应问题,通过反相器闩锁过程对非线性扰乱进行了机理分析,并利用微波注入实验详细分析了非线性扰乱效应的微波有效功率阈值及其随频率、脉冲宽度的变化。实验结果表明:在固定环境温度条件下,有效注入功率大于33 dBm,频率在3 GHz以下的微波均可使74HC04效应电路的非线性扰乱强度达到10%以上;有效注入功率大于30 dBm,频率在3 GHz以下的微波均可使74LVCU04A效应电路的非线性扰乱强度达到10%以上。相同非线性扰乱强度的注入有效功率阈值近似随频率的提高而增大。非线性扰乱阈值随注入微波信号脉宽变化明显,拐点为40~70 ns不等,与反相器中的互补型金属氧化物半导体器件寄生三级管的导通电流积累有关。     

测量行波管电子注的法拉第筒的热分析

利用ANSYS软件对测量行波管电子注截面的法拉第筒探头进行了热分析研究.分析了在单脉冲情况下,测量各种直径的不同脉冲功率密度的电子注、不同脉冲宽度对法拉第筒温度的影响,研究了测量不同功率密度的电子注可以使用的脉冲宽度.结果表明,仅法拉第筒上的注斑区域温度迅速上升,温度梯度较大,其它部分温度基本不变,为保证法拉第筒能够持...     

基于卷绕型带状线的感应电压叠加器的初步实验

 提出了一种基于卷绕型带状线和感应电压叠加器的重复频率脉冲电子束加速器的技术方案。介绍了一台感应电压叠加器感应单元的结构设计,并建立相应的电路模型,对其响应特性进行了模拟研究。介绍了卷绕型带状线的设计原理,制作了一台输出阻抗约3 Ω、脉冲宽度约230 ns的固态化卷绕型带状脉冲形成线。利用该脉冲发生器作为馈源,对感应电压叠加器感应单元的响应特性进行了实验研究,表明感应单元响应良好。对4级感应电压叠加器分别进行了单次脉冲和5 Hz重复频率的实验研究,结果表明叠加器的输出电压约为输入电压幅值的4倍,电流效率约80%,重复频率条件下,脉冲序列重复性较好。