Mobility limited by cluster scattering in ternary alloy quantum wires

The mobility limited by cluster scattering in ternary alloy semiconductor quantum wire(QWR) is theoretically investigated under Born approximation. We calculate the screened mobility due to clusters(high indium composition InGaN) scattering in the InxGa1 xN QWR structure. The characteristics of the cluster scattering mechanism are discussed in terms of the indium composition of clusters, the one-dimensional electron gas(1DEG) concentration, and the radius of QWR. We find that the density, breadth of cluster, and the correlation length have a strong effect on the electron mobility due to cluster scattering. Finally, a comparison of the cluster scattering is made with the alloy-disorder scattering. It is found that the cluster scattering acts as a significant scattering event to impact the resultant electron mobility in ternary alloy QWR.     

Effects of V/Ⅲ ratio on a-plane GaN epilayers with an InGaN interlayer

The effects of V/Ⅲgrowth flux ratio on a-plane GaN films grown on r-plane sapphire substrates with an InGaN interlayer are investigated.The surface morphology,crystalline quality,strain states,and density of basal stacking faults were found to depend heavily upon the V/Ⅲratio.With decreasing V/Ⅲratio,the surface morphology and crystal quality first improved and then deteriorated,and the density of the basal-plane stacking faults also first decreased and then increased.The optimal V/Ⅲratio growth condition for the best surface morphology and crystalline quality and the smallest basalplane stacking fault density of a-GaN films are found.We also found that the formation of basal-plane stacking faults is an effective way to release strain.     

聚合物防污材料表面水化层的分子动力学模拟

采用分子动力学方法研究了吸附在聚二甲基硅氧烷(PDMS)和接枝聚磺酸基甜菜碱甲基丙烯酸甲酯(pSBMA)改性后的防污材料膜水化层内的水分子的结构及其动力学性质, 从微观角度解释了聚合物膜具有防污性能的原因. 模拟发现: (1)紧靠聚合物膜形成的水化层是聚合物具有防污性能的关键因素, 该水化层是溶液中的粒子(包括蛋白质分子)与聚合物膜相接触时所要克服的最主要的物理能障; (2)相对PDMS聚合物膜而言, 双离子特性自组装膜(pSBMA)在氢键、静电力的共同作用下, 可以形成空间笼状水分子网结构对水分子具有更强的束缚作用并有效降低水分子的可运动性, 形成的稳定水化层使得pSBMA具有更强的阻碍蛋白质吸附的能力.     

Ground state of excitons in quantum-dot quantum-well nanoparticles： stochastic variational method

Within the framework of effective mass approximation, the ground state of excitons confined in spherical core-shell quantum-dot quantum-well (QDQW) nanoparticles is solved by using the stochastic variational method, in which the finite band offset and the heavy (light) hole exciton states are considered. The calculated 1s_e－1s_h transition energies for the chosen CdS/HgS/CdS QDQW samples are in good agreement with the experimental measurements. Moreover, some previous theoretical results are improved.     

可压缩气体中带电Newton流体平面液膜的不稳定性分析

液体雾化被广泛应用于工业、农业等领域,雾化过程中液体首先形成液膜,液膜在气液边界层内出现不稳定,导致液膜破碎。因此液膜的不稳定性对液体雾化起着非常重要的作用,有必要对液膜的不稳定性进行研究。采用数值计算的方法对可压缩气体中黏性平面液膜的不稳定性进行了研究,首先对黏性平面液膜和气体的速度分布进行推导,在此基础上采用谱方法对黏性平面液膜的不稳定性进行了研究。研究发现：在正弦和曲张模式下,施加电场会加速平面液膜的破碎;正弦模式比曲张模式更加不稳定,说明正弦模式在平面液膜不稳定中起主导作用;气体Mach数、电Euler数、气体Reynolds数、 Weber数和动量通量比的增加会加速液膜的破裂;随着气体边界层与液膜厚度比和液体Reynolds数的增加,扰动波的增长速率降低,液膜变得更加稳定。     

Improving the performance of perovskite solar cells with glycerol-doped PEDOT:PSS buffer layer

In this paper, we investigate the effects of glycerol doping on transmittance, conductivity and surface morphology of poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate))(PEDOT:PSS) and its influence on the performance of perovskite solar cells.. The conductivity of PEDOT:PSS is improved obviously by doping glycerol. The maximum of the conductivity is 0.89 S/cm when the doping concentration reaches 6 wt%, which increases about 127 times compared with undoped. The perovskite solar cells are fabricated with a configuration of indium tin oxide(ITO)/PEDOT:PSS/CH_3NH_3PbI_3/PC_(61)BM/Al, where PEDOT:PSS and PC_(61)BM are used as hole and electron transport layers, respectively. The results show an improvement of hole charge transport as well as an increase of short-circuit current density and a reduction of series resistance, owing to the higher conductivity of the doped PEDOT:PSS. Consequently, it improves the whole performance of perovskite solar cell. The power conversion efficiency(PCE) of the device is improved from 8.57% to 11.03% under AM 1.5 G(100 mW/cm~2 illumination) after the buffer layer has been modified.     

一步水热合成Cu-SSZ-13分子筛选择性催化C3H6还原NO

采用铜胺配合物(Cu²⁺-四乙烯五胺,Cu-TEPA)作为结构导向剂,通过一步水热法合成不同铜铝比(n_Cu/n_Al)和硅铝比(n_Si/n_Al)的Cu-SSZ-13分子筛催化剂,研究其在贫燃条件下丙烯选择性催化还原NO(C₃H₆-SCR)的性能。当n_Cu/n_Al=2、n_Si/n_Al=6时2.0Cu-SSZ-13(6)催化剂具有最好的低温脱硝活性,200℃时NO转化率超过80%,在250~300℃可实现100%脱硝效率和~100%N₂选择性,同时具有较强的抗水、抗硫性能。为研究不同n_Cu/n_Al和n_Si/n_Al对催化剂物理化学特性的影响,通过X射线衍射(XRD)、扫描电子显微镜(SEM)、N₂吸附-脱附测试、H₂程序升温还原(H₂-TPR)、氨气程序升温脱附(NH₃-TPD)、紫外可见光谱(UV-Vis)等手段对样品进行表征。结果表明,2.0Cu-SSZ-13(6)具有最佳的脱硝性能,这是因为其具有最大的比表面积、最强的表面酸性和分布最多的孤立态Cu²⁺离子。Cu-SSZ-13上丰富的酸性位可以有效促进C₃H₆和NO的吸附和活化,SSZ-13分子筛八元环中孤立的Cu²⁺离子具有良好的氧化还原性能,是C₃H₆-SCR反应的主要活性位。随着n_Cu/n_Al的增加,孤立的Cu²⁺离子会在分子筛表面迁移、集聚形成CuO物种,从而导致C₃H₆-SCR活性下降。     

玻色-费米混合气体的非线性Landau-Zener隧穿

在有相互作用的非线性两模系统中, 通过对相互作用参数的调节, 研究了该系统中玻色-费米混合气体的Landau-Zener隧穿现象. 研究发现, 其中某一组分的自相互作用会影响另一组分粒子的隧穿, 使得隧穿出现临界现象. 关键词： 玻色-费米混合气体 Landau-Zener隧穿 量子绝热隧穿     

截短新型冠状病毒N蛋白在荧光层析法上的应用

基于截短新型冠状病毒(Severe Acute Respiratory Syndrome Coronavirus 2,SARS-CoV-2)N 蛋白和全长N蛋白,采用荧光免疫层析技术,建立了一种高灵敏度快速评价新型冠状病毒肺炎患者体内SARS-CoV-2抗体水平的方法.以荧光微球为标记物制备试纸条,进行阴性和阳性检测并...     

基于未标定序列图的形貌测量方法

提出一种形貌测量方法,从未标定序列图中同时提取出特征点的三维坐标和摄像机的运动矩阵,实现对目标物体的三维测量。首先用齐次坐标表达了空间点的投影变换矩阵,并根据该矩阵推导出投影比例式,运用投影深度和投影矩阵之间的循环相关性进行迭代运算,得到比普通双目视觉更加精确的深度数据。其次对分解得到的摄像机运动矩阵和空间点坐标施加度量约束。运用基于因式分解的归一化算法,恢复出欧氏空间里的摄像机运动矩阵和空间点坐标。基于这种方法,实现了曲面标记点的坐标测量,得到了三维形貌数据,误差小于0.16mm。