Preparation and Characterization of Transparent Conductive Nb-Doped ZnO Films by Radio-Frequency Sputtering

Niobium-doped ZnO （NZO） transparent conductive films are deposited on glass substrates by rt sputtering at 300℃. Effects of sputtering power on the structural, morphologie, electrical, and optical properties of NZO films are investigated by x-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, Hall measurement, and optical transmission spectroscopy. The obtained films are polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the （002） crystallographic direction. The minimum resistivity of 4.0×10^-4Ω·cm is obtained from the film grown at the sputtering power of 170W. The average optical transmittance of the films is over 90%.     

CFETR偏滤器靶板的概念设计与分析

基于以前的偏滤器研究,提出了中国核聚变工程实验堆(CFETR)偏滤器靶板的概念设计。在最差工况下进行的热工水力分析和力学分析表明,应力和温度都在允许范围内,验证了该设计模型的可靠性。该概念模型和对其所做的分析可以为以后的工程设计提供参考。     

基于加权TV正则化的X射线CT系统能谱估计方法

在CT硬化伪影校正、双能CT图像重建以及CT辐射剂量计算等实际应用中,X射线的能谱信息具有重要的作用。然而,由于透射测量方程组系数矩阵的病态性、X光子的统计涨落和噪声的干扰,使得EM等能谱估计方法难以获得较精细的能谱刻画。针对该问题,提出一种基于加权TV正则化的X射线CT系统能谱估计方法。首先采用能谱能量范围内带有不同K-edge的材料作为体模以降低投影测量方程之间的相关性。然后,利用CT成像系统的几何参数来获取投影测量数据所对应的准确透射长度信息来减小投影方程的测量误差。最后,综合利用透射衰减测量数据的保真性、轫致辐射能谱部分的连续性、特征辐射能谱部分的离散性、能谱的非负性和归一性以及平均有效衰减系数等信息,使用加权TV正则化方法建立目标函数,利用正则化理论中的L曲线准则通过黄金分割参数搜索策略求得最优正则化参数及对应的能谱估计结果。分别通过不同统计波动模型下的仿真能谱和实际测量数据对算法性能进行了验证,结果表明该方法与EM等方法相比,不受初始能谱的影响,有效提高了能谱估计结果的稳定性和准确性。     

可见光响应型ZnO/Bi2O3复相光催化剂的制备及其性能研究

以Zn(Ac) 2·2H2O和Bi( NO3)3·5H2O为主要原料,采用溶胶-凝胶法成功制备了可见光响应型的高效复相ZnO/Bi2O3催化剂.利用X射线衍射(XRD)、扫描电镜(SEM)对样品进行了表征,并以甲基橙为目标污染物,测试样品的光催化性能,研究了初始合成条件、光源等对样品光催化性能的影响.实验结果表明:在nZn∶nBi为1∶1,浓度为0.05 mol/L条件下制得的凝胶,经600℃煅烧2h后,样品呈现六方纤锌矿结构的氧化锌晶相并伴有单斜α-Bi2O3、三斜ω-Bi2O3晶相.在16 W紫外灯、500W卤素灯照射下,2.5h后,甲基橙的脱色率为95.73;,68.36;,而经太阳光照射2.5h,甲基橙的脱色率分别为53.8;,但将其继续置于阳台上24h,脱色率可达97.6;.在16 W紫外灯的辐照下,样品重复使用6次,甲基橙的脱色率仍在90;以上,表明催化剂具有较高的重复使用率.     

Transient optical modulation properties in the terahertz metamaterial of split ring resonators

The ultrafast optical modulation properties of split ring resonators are characterized by utilizing optical pump-terahertz probe spectroscopy.The experimental results show that when the terahertz electric vector is perpendicular to the gap of the split ring resonator,resonant absorption can be quenched significantly under high pump excitation.However,when the terahertz electric vector is parallel to the gap,the resonant absorption is less sensitive to pump excitation due to the structural properties of the metamaterial.Our numerical simulations also demonstrate that the pump pulse significantly influences the split ring resonator current by generating carriers in the substrate.     

共存物对中药有效成分七叶内酯-bsa结合的扰动方式

共存物;扰动方式;中药有效成分;牛血清白蛋白     

质谱技术在文书鉴定中的应用研究进展

文书鉴定的对象具有复杂性、多样性,检验难度大等问题,因而要求立足各要素,多种方法并用的系统检验。质谱技术具有快速、高效、准确、灵敏度高等优点,且随着敞开式电离质谱技术的发展,质谱技术在文书鉴定领域展现出越来越重要的应用价值。本文通过归纳质谱技术在文书鉴定的应用研究案例,分析不同质谱技术在文书鉴定领域的优势与适用范围,为不同类型、不同条件的文书鉴定的质谱分析提供参考方法,为完善系统鉴定、增强检验效果、提高文书鉴定质量及创新提供理论依据与分析策略。最终质谱技术将从文书鉴定的实验应用研究真正转化为司法实践中的有效手段及技术标准。     

Fast local reconstruction by selective backprojection for low dose in dental computed tomography

The high radiation dose in computed tomography (CT) scans increases the lifetime risk of cancer, which becomes a major clinical concern. The backprojection-filtration (BPF) algorithm could reduce the radiation dose by reconstructing the images from truncated data in a short scan. In a dental CT, it could reduce the radiation dose for the teeth by using the projection acquired in a short scan, and could avoid irradiation to the other part by using truncated projection. However, the limit of integration for backprojection varies per PI-line, resulting in low calculation efficiency and poor parallel performance. Recently, a tent BPF has been proposed to improve the calculation efficiency by rearranging the projection. However, the memory-consuming data rebinning process is included. Accordingly, the selective BPF (S-BPF) algorithm is proposed in this paper. In this algorithm, the derivative of the projection is backprojected to the points whose x coordinate is less than that of the source focal spot to obtain the differentiated backprojection. The finite Hilbert inverse is then applied to each PI-line segment. S-BPF avoids the influence of the variable limit of integration by selective backprojection without additional time cost or memory cost. The simulation experiment and the real experiment demonstrated the higher reconstruction efficiency of S-BPF.     

Transitional Area of Ce~(4+) to Ce~(3+) in Sm_xCa_yCe_(1-x-y)O_(2-δ) with Various Doping and Oxygen Vacancy Concentrations: A GGA + U Study

In this work,we perform DFT+U periodic calculations to study geometrical and electronic structures and oxygen vacancy formation energies of Sm_xCa_yCe_(1-x-y)O_(2-δ)systems(x=0.0312,0.0625,0.125 and 0.250;y=0.0312,0.0625,0.125 and 0.250;δ=0.0312,0.0625,0.125,0.250 and 0.50)with different oxygen vacancy and doping concentrations.The calculated results show that the V_1-Sm~(3+)-V_2 structures where there is a position relationship of the face diagonal between V_1 and V_2 both nearest to Sm~(3+)have the lowest energy configurations.The study on electronic structures of the Sm_xCa_yCe_(1-x-y)O_(2-δ)systems finds that excess electrons arise from oxygen vacancies and are localized on f-level traps of their neighbor Ce,and Ca~(2+)and Sm~(3+)co-doping effectively restrains the reduction of Ce~(4+).In order to avoid the existence of Ce~(3+),x and y must be both larger than 0.0625 asδ=0.125 orδmust be smaller than 0.125 as x=y=0.0625.The Ce~(3+)/Ce~(4+)change ratio k has an obvious monotonous increase with increasing the vacancy oxygen concentration.The introduction of Sm~(3+)decreases k.In addition,the doped Sm~(3+)can restrain the reduction of Ce~(4+)when the V_1-Sm~(3+)-V_2 structure with a face diagonal position relationship in lower reduced atmosphere exists.It need be pointed out that the Sm_(0.25)Ce_(0.75)O_(1.5) system should be thought of as a Sm-doped Ce_2O_3 one.     

壳体约束对液体爆炸抛撒流场特性的影响

进行了不同壳体约束条件下的液体爆炸抛撒实验,讨论了壳体对起爆后早期抛撒流场特征的影响,分析了爆炸分散过程中液体的状态变化和破碎分散机理,并通过数值模拟进行了对比分析。结果表明,在爆炸反射稀疏波的作用下液体发生空化现象,壳体强度越高,空化发生的延迟越大,发生位置越靠近爆心,同时,爆炸产物气体与液体在其界面附近越早发生掺混。