Experimental studies of THGEM in different Ar/CO_2 mixtures

In this paper, the performance of a type of domestic THGEM (THick Gaseous Electron Multiplier) working in Ar/CO₂ mixtures is reported in detail. This kind of single THGEM can provide a gain range from 100 to 1000, which is very suitable for application in neutron detection. In order to study its basic characteristics as a reference for the development of a THGEM based neutron detector, the counting rate plateau, the energy resolution and the gain of the THGEM have been measured in different Ar/CO₂ mixtures with a variety of electrical fields. For the Ar/CO₂(90%/10%) gas mixture, a wide counting rate plateau is achieved from 720 V to 770 V, with a plateau slope of 2.4%/100 V, and an excellent energy resolution of about 22% is obtained at the 5.9 keV full energy peak of the ⁵⁵Fe X-ray source.     

光催化氧化丙烯产物的气相色谱分析

建立了光催化氧化微量丙烯所产生的CO2和H2O的气相色谱分析检测方法.CO2通过一个装有Ni催化剂的转化炉加氢转化成CH4,H2O通过一个CaC2反应管转化成C2H2,从而可以利用氢火焰离子化检测器（FID）进行微量分析.利用该分析方法能对反应生成的CO2进行定性和定量分析,对反应生成的H2O进行定性分析.实验证明该分析方法的准确度、精密度和灵敏度都能满足实验的要求.有氧气的存在下会出现＂鬼峰＂,文中对这一现象进行了讨论.     

1-(2-羟甲基-1,3-氧硫杂环戊基)吡啶酮类化合物的合成

研究了1,3-氧硫杂环戊烷核苷类似物的合成. 以吡啶酮为碱基, 利用三甲基硅基三氟甲磺酸酯(TMSOTf)催化, 与1,3-氧硫杂环戊烷发生Vorbruggen缩合反应, 合成了一系列的保护的核苷类似物, 经过进一步脱保护或者还原得到目标产物. 并测试了合成化合物的抗菌活性, 发现该类化合物对革兰氏阳性菌具有中等抑制活性.     

THGEM探测器X光斑寻迹和位置分辨实验研究

介绍了一种基于THGEM的X射线光斑寻迹探测器,用于X射线单光子计量技术研究和测量,探测器有效面积200 mm×200 mm,采用128路基于ASIC和FPGA的高速读出电子学,探测器分为中间高分辨区和外围低分辨区两部分,两部分共用一套读出电子学。实验在中国计量科学研究院利用X光机产生的束线,测试光斑位置、光斑精细分布以及探测器的位置分辨。实验结果表明,探测器实现了同时对光斑寻迹和光斑的精细测量,探测器中间高分辨区x方向的位置分辨率为0.63 mm（FWHM）,y方向位置分辨率为0.62mm（FWHM）,探测器各项性能指标均达到了预期目标。This paper introduces the detector of X-ray spot tracing based on the THGEM. It is used for X ray single photon measurement technology research and measurement with an effective area of 200 mm×200 mm. The circuit board has 128 array of high speed readout electronics based on ASIC and FPGA. And it is divided into two parts:the middle area of high sensitive and the peripheral area of low sensitive. The two parts share a set of readout electronics. The experiment tests the position and the fine structure of the beam line produced by X ray machine in National Institute of Metrology. The results of the experimental show that the detector realizes both the spot tracing and the fine structure of the spot. The position resolution is 0.63 mm in x direction and 0.62 mm in y direction in high sensitive of the detector, which achieve the desired goal of preliminary design.     

多孔介质中对流的研究

介绍多孔介质中对流研究的重要意义及半个世纪以来的研究进展，特别是近１０年来在对流振荡、分岔等方面的研究和对混饨的探讨．着重讨论多孔介质中的自然对流．     

芳纶改性聚合物基纳米复合皮革涂饰剂的制备和性能

以甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)、丙烯酸(AA)和丙烯酰胺(AM)为共聚单体,通过水乳液聚合制备一种四元共聚物(PBMAA)乳液并自然干燥成膜,然后对芳纶Kevlar-1313(K-1313)共聚物进行改性,得到改性共聚物(K-PBMAA),并优化其添加比例以期提高涂饰膜的强度和耐磨损性能。将制备的实心纳米二氧化硅(记为S-SiO₂)和中空纳米二氧化硅(记为H-SiO₂)分别添加到K-PBMAA中制备纳米复合皮革涂饰剂(记为S-SiO₂/K-PMBAA和H-SiO₂/K-PMBAA)并用于绵羊皮的涂饰,发现K-1313和纳米SiO₂的同时引入使得复合涂膜的最大热分解温度由404℃提升至411℃,力学性能由4.03 MPa提高到8.67 MPa。     

气体凝聚团簇源中团簇形成的DSMC研究

利用直接模拟蒙特卡洛方法(DSMC) ,模拟了气体凝聚团簇源的引出口尺寸和中心位置不同的条件下,Cu团簇的尺寸分布以及模拟了随着时间的增长,腔内团簇数目的变化.模拟结果表明:引出口的直径越大,产生大团簇的比例越小;在引出口的直径相同的情况下,引出口的中心位置偏离坐标原点比在原点产生的大团簇的比例要大;随着时间的增长,腔内团簇数目先变多后变少.     

Experimental studies of THGEM in different Ar/CO2 mixtures

In this paper, the performance of a type of domestic THGEM （THick Gaseous Electron Multiplier） working in Ar/CO2 mixtures is reported in detail. This kind of single THGEM can provide a gain range from 100 to 1000, which is very suitable for application in neutron detection. In order to study its basic characteristics as a reference for the development of a THGEM based neutron detector, the counting rate plateau, the energy resolution and the gain of the THGEM have been measured in different Ar/CO2 mixtures with a variety of electrical fields. For the Ar/CO2（90%/10%） gas mixture, a wide counting rate plateau is achieved from 720 V to 770 V, with a plateau slope of 2.4%/100 V, and an excellent energy resolution of about 22% is obtained at the 5.9 keV full energy peak of the 55Fe X-ray source.     

镶嵌CdS的纳米管钛酸制备及其光催化性能研究

制备了镶嵌硫化镉的纳米管钛酸,并用透射电镜(TEM)、X射线衍射(XRD)、扩散反射(DRS)等工具进行了表征.丙烯的光催化氧化研究结果表明,镶有CdS与未镶CdS的纳米管钛酸作为光催化剂,对丙烯的光催化去除活性相近.     

制备高质量聚苯乙烯微球胶粒晶体的蒸发自组装法

建立了一种组装亚微米级聚苯乙烯微球的方法，称作蒸发自组装法.该方法是在一定温度下 ，聚苯乙烯微球随着分散介质的蒸发在悬浮液的气-液相界面处进行高效组装的过程.扫描电 子显微镜显示组装体为规则排列的密堆积面心立方结构.研究发现，气-液界面处生成的组装 体强烈地阻碍着分散介质的蒸发，单位时间内消耗的颗粒总数量随组装面积的增大而增加. 通过调整悬浮液的蒸发温度和组装面积，可以有效地控制悬浮液相浓度的变化，从而实现在 相浓度基本不变的情况下组装出高质量的聚苯乙烯胶粒晶体. 关键词： 蒸发自组装法 胶粒晶体 聚苯乙烯微球 三维有序大孔材料