等温结晶化条件对氟化孔洞聚丙烯膜电荷稳定性的显著影响

基于开路热刺激放电电流和电荷等温衰减测量系统地研究了等温结晶化条件对氟化孔洞聚丙烯(PP)膜电荷稳定性的影响.结果表明等温结晶化温度和时间对氟化PP膜的电荷稳定性或电荷陷阱的构造具有显著的影响,即使90 ℃,0.5 h的等温结晶化处理也能显著地加深其电荷陷阱、改善电荷的稳定性.而且随着等温结晶化温度的提高和时间的延长,电荷陷阱进一步被加深、电荷稳定性进一步被改善,如130 ℃,2 h以上的等温结晶化情形.衰减全反射红外分析和宽角X射线衍射分析表明,电荷稳定性的改善归因于PP膜的组成和结构变化.     

介质壁加速腔加速结构优化

为了在介质壁加速器中增大轴向加速电场, 提高加速梯度的同时抑制径向电场对束包络的扩张, 提出了在每个加速电极上添加金属栅网结构。采用基于粒子云网格方法的电磁粒子模拟软件对不加栅网与添加栅网的电极结构进行了数值仿真, 分析了不同结构下加速管道中的电场分布和束包络变化。通过实验对比了两种不同结构下经过相同的加速长度获得的粒子能量。结果表明:添加金属栅网结构相对于不加栅网的金属小孔式结构, 轴向加速电场强度提高20%, 同时径向电场得到有效抑制;栅网结构下, 被加速的粒子束在自由漂移空间中的径向发散基本得到抑制;在相同的加速长度下加速H3+粒子, 栅网结构得到的能量增益提高了一倍。     

纳米二氧化硅体内与体外氧化应激及细胞毒性实验研究

研究了纳米二氧化硅(SiO2)体内及体外氧化应激损伤及细胞毒性作用及机制.体内实验采用ICR小鼠,纳米SiO2经口灌胃染毒3次,检测肺组织中MDA(丙二醛)和SOD(超氧化物歧化酶)含量,观察纳米SiO2对小鼠肺的氧化应激毒性.采用体外培养的小鼠上皮细胞(JB6细胞),观察不同质量浓度纳米SiO2染毒后的细胞形态改变,通过蛋白免疫印迹实验检测纳米SiO2是否通过FAS信号途径引起细胞凋亡.研究结果表明:纳米SiO2经口染毒后对小鼠肺具有氧化应激损伤作用,表现为随染毒剂量的升高,肺组织中MDA产生量增加,呈一定的剂量-反应关系.同时,肺组织内SOD水平总体趋势降低,但是差别未见统计学意义.体外培养细胞实验中,纳米SiO2染毒后可引起细胞出现凋亡并呈空泡样变.蛋白免疫印迹实验中,纳米SiO2可引起FAS信号蛋白表达量明显上升,但是FADD表达水平并不升高.     

二酯基连接链乙基头基季铵盐Gemini表面活性剂的合成及性质

以长链溴代烷、二乙胺、氯乙酰氯和乙二醇为原料合成了5种新型二酯基连接链乙基头基季铵盐双子表面活性剂Gemini C10,Gemini C12,Gemini C14,Gemini C16,Gemini C18(尾链碳原子数依次为10,12,14,16,18),并研究了它们的表面性能和聚集体形态.结果显示,Gemini C10的临界胶束浓度(cmc)在20～40℃间随着温度升高而减小,而其他4种Gemini表面活性剂的cmc却随温度升高而增大;25℃时Gemini C10～C18在cmc时的表面张力随疏水链长度的增加呈降低趋势;Gemini产物在较高浓度下有囊泡聚集体形成,尺寸为40～200nm.     

EFFECTS OF ISLAND-EDGE EXCHANGE BARRIER ON 2D PATTERN FORMATION IN SURFACTANT-MEDIATED EPITAXY

The nucleation and growth of two-dimensional islands in a surfactant-mediated epitaxy system have been studied by computer simulation. To improve the recent results published in the literature, we use a configuration-dependent energy barrier for the exchange process at the island edge in our model. The simulations produce fractal islands at high temperatures or low deposition fluxes, and a transition to regular compact islands occurs at lower temperatures or higher fluxes, in good agreement with the recent experimental results. The barrier for the island-edge exchange has quite a strong effect on the island density as a function of temperature and flux. A small change of the island-edge exchange barrier induces a large variation of the island density in the low-temperature or high-flux region. The flux-dependent island density shows a clear scaling-law behaviour in the intermediate-flux region. The scaling exponent increases evidently as the island-edge exchange barrier increases.     

半透明介质中辐射传递方程的反演计算及数值模拟

本文介绍了一侧为半透明、另一侧为非透明界面时一维半透明介质的辐射强度计算式。采用辐射与导热复合换热模型计算半透明介质内温度场。利用已知的温度场求半透明介质的辐射强度一正问题计算。将此辐射强度代入辐射反问题计算模型，引入测量误差，采用Ｃｈａｈｉｎｅ方法及演半透明介质内温度场一反问题计算。数值模拟表明，本文所采用的辐射反演法具有较高的精度及稳定性。     

Off-axial contribution of beam self-focusing in plasma with density ripple

Off-axial contribution of beam self-focusing in plasma with density ripple is investigated. Apply paraxial ray theory and Wentzel–Krammers–Brillouin approximation, the results shown that, in interaction of laser and plasma with density ripple, beam self-focusing presents some interesting diverse features when off-axial contribution is obvious. In the paper, we find, on the one hand, density ripple can minimize the defocusing and beam still retains a localized profile with an oscillatory self-focusing and defocusing, on the other hand, with the increase of off-axial contribution, laser beams presents four various self-focusing features, which laser beam intensity profile splits into three-splitted with central axial convex profile, three-splitted with equal amplitude profile, three-splitted with central axial concave profile and two-splitted intensity profile.     

Relative density-based classification noise detection

Classification noise is a common byproduct of traditional data mining approaches, and no specialized approach for detecting classification noise is currently available. Methods for outlier detection are well-developed, but outliers and classification noise have characteristics different enough to make outlier detection algorithms unsuitable for classification noise detection. In this paper, a new, specialized approach to detect classification noise is proposed, named relative density based classification noise detection (RDBCND). Computational experiments in artificial data sets described herein show that RDBCND has time complexity of O(n log n), indicating greater efficiency than traditional approaches, which exhibit time complexity of at least O(n²). The use of classification noise detection to improve the generalization ability of common classifier algorithms is also described. In particular, a new unified approach based on RDBCND is compared to a cross validation approach applied to a BP neural network. Trials in both artificial and real-life datasets show that the RDBCND-based approach can greatly accelerate the process of identifying the best decision function. The novel method can also eliminate underfitting, as the algorithm simply searches for the highest training accuracy. The experiments also show that the RDBCND-based method has greater accuracy and lower cpu time in reaching global solutions than the cross-validation method. Since the relative density is a local concept, our new approach can be directly used in nonlinear datasets without data transformation. It is a great advantage compared to some linear classifier algorithms. As in current linear classifiers, the kernel functions or other transformations need to be used to make them suitable for non-linear datasets, and that will increase their complexity.     

常压溶剂法合成抗氧剂3114反应热力学和动力学

研究了常压溶剂法一步合成抗氧剂3114反应热力学和动力学过程。控制温度在117±2℃,研究结果表明,反应是零级反应,反应速率常数为k=1．91×10^-3／min,反应的平衡常数为K=138．4（mol／L）^-6,反应活化能Ea=1366J／mol。     

毫米波二阶分形频率选择表面寄生谐振的抑制

二阶分形频率选择表面具有良好的双频特性, 是实现准光学选频网络小型化的理想选择. 但是由于其自相似迭代结构的复杂性, 导致其长期受到寄生谐振的影响, 为了提高二阶分形结构在工程应用中的可靠性, 本文建立了二阶方环分形周期单元的等效电路并分析了寄生谐振产生时的场分布情况, 研究了寄生谐振的形成机理; 进而通过单元间去耦合操作, 并引入基于离散粒子群算法的多参数优化过程, 克服了这一问题. 仿真和实验结果表明: 在保证双频工作特性、对于入射角和极化稳定的前提下, 通过去耦合和粒子群算法实现的频率选择表面实测对寄生谐振的抑制可达13dB, 且避免了新的寄生谐振的产生. 关于寄生谐振抑制的研究, 为增强二阶分形阵列结构的可靠性提供了新的思路. 关键词： 二阶分形 频率选择表面 寄生谐振 离散粒子群算法