铝衰减膜表面氧化对软X光透过率的影响与修正

对用不同方法制备的软Ｘ光激光实验用的Ａｌ衰减膜样品,用Ａｕｇｅｒ电子能谱（ＡＥＳ）结合氩离子束刻蚀进行了组分的表面和深度分布分析,结果表明表面氧化层主要由Ａｌ２Ｏ３组成,氧化达到饱和时的氧化层厚度≈７．５ｎｍ。由于在软Ｘ光波段内,氧的吸收系数比铝大一个多数量级,这一氧化层对软Ｘ光透过率的影响甚大。将ＡＥＳ测试结果作为参数,使用公式Ｉ＝Ｉ０·ｅｘｐ［－μ（Ｅ）·（ρｄ）］对Ｘ光透过强度进行修正。同步辐射软Ｘ光对样品透过率的直接测量表明,对于透过率大于２０％的Ａｌ膜,直接测量结果与按修正公式计算的结果在最大偏差１１％范围内符合。     

一种新型的太阳自动跟踪系统研究

为了最大限度的利用太阳能,采用自动跟踪太阳的方式以获得更多的能量。简要介绍了现有的几种主要跟踪方式,光电探测器跟踪方式容易受天气条件干扰,时钟跟踪方式有累积误差或者因数据库庞大导致反应变慢等缺点。提出了一种时钟跟踪与光电探测器跟踪相结合的双轴跟踪方式,方位角采用时钟跟踪,俯仰角采用四象限光电探测器跟踪,控制核心选用ATmega16单片机。该跟踪方式结合这两种跟踪方式的优点,很好地克服了两者的缺点。实验表明,本系统转动精度高,工作稳定性好,太阳能接收损失小。     

Elucidating the Origins of Subgap Tail States and Open‐Circuit Voltage in Methylammonium Lead Triiodide Perovskite Solar Cells

Recombination via subgap trap states is considered a limiting factor in the development of organometal halide perovskite solar cells. Here, the impact of active layer crystallinity on the accumulated charge and open‐circuit voltage (V_oc) in solar cells based on methylammonium lead triiodide (CH₃NH₃PbI₃, MAPI) is demonstrated. It is shown that MAPI crystallinity can be systematically tailored by modulating the stoichiometry of the precursor mix, where small quantities of excess methylammonium iodide (MAI) improve crystallinity, increasing device V_oc by ≈200 mV. Using in situ differential charging and transient photovoltage measurements, charge density and charge carrier recombination lifetime are determined under operational conditions. Increased V_oc is correlated to improved active layer crystallinity and a reduction in the density of trap states in MAPI. Photoluminescence spectroscopy shows that an increase in trap state density correlates with faster carrier trapping and more nonradiative recombination pathways. Fundamental insights into the origin of V_oc in perovskite photovoltaics are provided and it is demonstrated why highly crystalline perovskite films are paramount for high‐performance devices.     

Nanoporous PtRu Alloy Enhanced Nonenzymatic Immunosensor for Ultrasensitive Detection of Microcystin‐LR

A novel nonenzymatic immunosensor for sensitive detection of Microcystin‐LR (MC‐LR) is constructed using a graphene platform combined with mesoporous PtRu alloy as a label for signal amplification. Primary antibody‐Microcystin‐LR (Ab₁) is immobilized onto the surface of a graphene sheet (GS) through an amidation reaction between the carboxylic acid groups attached to the GS and the available amine groups of Ab₁. Mesoporous PtRu alloy, prepared by corrosion PtRuAl alloys, is employed as a label to immobilize secondary antibody (Ab₂). The resulting nanoparticles, PtRu‐Ab₂, are used as labels for the immunosensor to detect MC‐LR. Under optimal conditions, the immunosensor exhibits a wide linear response to MC‐LR that ranges from 0.01 to 28 ng·mL^?1, with a low detection limit of 9.63 pg·mL^?1 MC‐LR. The proposed immunsensor shows good reproducibility, selectivity, and stability. The assayed results of polluted water with the sandwich‐type sensor are acceptable. Importantly, this methodology may provide a promising ultrasensitive assay strategy for other environmental pollutants.     

光子晶体垂直腔型表面发射和接收光电子器件

介绍了制作光子晶体垂直腔面发射激光器实验研究的主要内容,包括材料的光谱测试分析、氧化工艺以及制作光子晶体等,成功制作了波长在980nm附近的光子晶体垂直腔面发射激光器.在此基础上,采用高精度湿法腐蚀和感应耦合等离子体干法刻蚀技术,研究制作了基于垂直腔面发射激光器外延材料的光子晶体谐振腔增强型探测器.     

Molecular Simulation to Explore the Dissolution Behavior of Sulfur in Carbon Disulfide

Soluble sulfur (S₈) and insoluble sulfur (IS) have different application fields, and molecular dynamics simulation can reveal their differences in solubility in solvents. It is found that in the simulated carbon disulfide (CS₂) solvent, soluble sulfur in the form of clusters mainly promotes the dissolution of clusters through van der Waals interaction between solvent molecules (CS₂) and S₈, and the solubility gradually increases with the increase in temperature. However, the strong interaction between polymer chains of insoluble sulfur in the form of polymer hinders the diffusion of IS into CS₂ solvent, which is not conducive to high-temperature dissolution. The simulated solubility parameter shows that the solubility parameter of soluble sulfur is closer to that of the solvent, which is consistent with the above explanation that soluble sulfur is easy to dissolve.     

Effect of Different Processing Methods on the Chemical Constituents of Scrophulariae Radix as Revealed by 2D NMR-Based Metabolomics

Scrophulariae Radix (SR) is one of the oldest and most frequently used Chinese herbs for oriental medicine in China. Before clinical use, the SR should be processed using different methods after harvest, such as steaming, “sweating”, and traditional fire-drying. In order to investigate the difference in chemical constituents using different processing methods, the two-dimensional (2D) ¹H-¹³C heteronuclear single quantum correlation (¹H-¹³C HSQC)-based metabolomics approach was applied to extensively characterize the difference in the chemical components in the extracts of SR processed using different processing methods. In total, 20 compounds were identified as potential chemical markers that changed significantly with different steaming durations. Seven compounds can be used as potential chemical markers to differentiate processing by sweating, hot-air drying, and steaming for 4 h. These findings could elucidate the change of chemical constituents of the processed SR and provide a guide for the processing. In addition, our protocol may represent a general approach to characterizing chemical compounds of traditional Chinese medicine (TCM) and therefore might be considered as a promising approach to exploring the scientific basis of traditional processing of TCM.     

HIGH-FREQUENCY VIBRATIONS OF CORRUGATED CYLINDRICAL PIEZOELECTRIC SHELLS

Coupled extensional and flexural cylindrical vibrations of a corrugated cylindrical piezoelectric shell consisting of multiple pieces of circular cylindrical surfaces smoothly connected along their generatrix are studied. To validate the results for the case of relatively thick shells or equivalently high-frequency modes with short wavelengths, existing analysis is extended by considering shear deformation and rotatory inertia. An analytical solution is obtained. Based on the solution, resonant frequencies and mode shapes are calculated.     

Cloning,Expression, Purification,and Characterization of β-Galactosidase from Bifidobacterium longum and Bifidobacterium pseudocatenulatum

Expression and purification of β-galactosidases derived from Bifidobacterium provide a new resource for efficient lactose hydrolysis and lactose intolerance alleviation. Here, we cloned and expressed two β-galactosidases derived from Bifidobacterium. The optimal pH for BLGLB1 was 5.5, and the optimal temperature was 45 °C, at which the enzyme activity of BLGLB1 was higher than that of commercial enzyme E (300 ± 3.6 U/mg) under its optimal conditions, reaching 2200 ± 15 U/mg. The optimal pH and temperature for BPGLB1 were 6.0 and 45 °C, respectively, and the enzyme activity (0.58 ± 0.03 U/mg) under optimum conditions was significantly lower than that of BLGLB1. The structures of the two β-galactosidase were similar, with all known key sites conserved. When o-nitrophenyl-β-D-galactoside (oNPG) was used as an enzyme reaction substrate, the maximum reaction velocity (V_max) for BLGLB1 and BPGLB1 was 3700 ± 100 U/mg and 1.1 ± 0.1 U/mg, respectively. The kinetic constant (K_m) of BLGLB1 and BPGLB1 was 1.9 ± 0.1 and 1.3 ± 0.3 mmol/L, respectively. The respective catalytic constant (k_cat) of BLGLB1 and BPGLB1 was 1700 ± 40 s⁻¹ and 0.5 ± 0.02 s⁻¹, respectively; the respective k_cat/K_m value of BLGLB1 and BPGLB1 was 870 L/(mmol∙s) and 0.36 L/(mmol∙s), respectively. The K_m, k_cat and V_max values of BLGLB1 were superior to those of earlier reported β-galactosidase derived from Bifidobacterium. Overall, BLGLB1 has potential application in the food industry.     

水杨酸甲酯在β-环糊精水溶液中的双重荧光光谱

研究了β-环糊精(β-CD)及其衍生物甲基-β-环糊精(M-β-CD)、羟丙基-β-环糊精(HP-β-CD)对水杨酸甲酯(MS)双重荧光光谱的影响,并将其与MS在不同溶剂中的荧光光谱进行对比。结果表明,MS的双重荧光与所处微环境的氢键性质密切相关,β-CD取代基的大小会导致空腔口处的极性和空间位阻不同,相应改变了分子间氢键相互作用,当MS分子进入β-CDs空腔时会引起其基态互变异构体之间平衡的移动,从而导致光谱的变化。包合物稳定常数测定表明,三种β-CDs对MS包合能力的大小为M-β-CD>HP-β-CD>β-CD。