Well vertically aligned ZnO nanowire arrays with an ultra-fast recovery time for UV photodetector

Well-crystallized ZnO nanowire arrays were grown on GaN/sapphire by one-step chemical vapor deposition under control of the fabrication pressure of 1000–2500 Pa and the best-aligned arrays were obtained at 1000 Pa. A photoluminescence study shows a red shift with nanowire diameter increase. Under 365-nm UV irradiation of 0.3 mW/cm², the photoresponse study of the best ZnO arrays shows an ultra-fast tri-exponential rise with three constants of 0.148, 0.064 and 0.613 s, and a bi-exponential decay behavior with two recovery constants of 30 and 270 ms. The ZnO/GaN heterojunction barriers could be responsible for the ultra-fast tri-exponential rise and bi-exponential decay behavior.     

Extraction,identification and antimicrobial activity of a new furanone,grifolaone A,from Grifola frondosa

A furanone (1), (S)-methyl 2-(2-hydroxy-3,4-dimethyl-5-oxo-2,5-dihydrofuran-2-yl)acetate, was isolated from the edible mushroom Grifola frondosa. Mass spectrometry and NMR analyses were used to elucidate the structure of this compound, and its absolute configuration was determined using circular dichroism spectroscopy. Compound 1 exhibited specific antifungal activity against the plant pathogens, Fusarium oxysporum, Gibberella zeae and Piricularia oryzae and the opportunistic human pathogen, Pseudallescheria boydii, resulting in minimum inhibitory concentration values of 2.5, 2.5, 1.25 and 0.15 μg/mL, respectively. In contrast, the furanone showed only weak activity towards Aspergillus spp., Candida albicans and several other fungal strains tested as well as no appreciable antibacterial activity.     

Pd/SiC催化碘代芳烃和芳基硼酸羰化Suzuki偶联反应性能

以高比表面积碳化硅为载体,通过液相还原法制备出Pd/SiC催化剂,并用于催化碘代芳烃和芳基硼酸羰化Suzuki偶联反应.利用X射线衍射、电感耦合等离子体质谱和高分辨透射电子显微镜等对催化剂进行了表征.结果表明, SiC表面的Pd纳米颗粒分散均匀,平均粒径约为2.8 nm.在优化溶剂、碱、压力和温度等反应条件后,发现以3 mmol的K2CO3和10 mL苯甲醚分别为碱和溶剂,1.0 mmol碘苯和1.5 mmol苯硼酸在3 wt% Pd/SiC催化剂存在的条件下,在CO压力为1.0 MPa和100oC下反应8 h即可实现羰化偶联,碘苯转化率为90%,二苯甲酮选择性为99%.并且, Pd/SiC对含有不同官能团的碘代芳烃和芳基硼酸羰化Suzuki偶联反应具有较好的普适性.同时, Pd/SiC也具有较好的稳定性,经5次循环反应后,碘苯转化率从90%降至76%;催化剂活性降低的主要原因是活性组分Pd在有机反应体系中的流失.     

金纳米簇的制备及其在生物医学中的应用

金纳米簇由几个到几十个金原子组成,具有尺寸小、荧光性能好、无毒等优点,被广泛应用于生物医学领域。本文介绍了包括模板法,刻蚀法,可逆相转移法和动力学控制法等金纳米簇的主要制备方法,并综述了金纳米簇在生物医学上的主要应用,包括生物检测、荧光成像和药物控释。     

基于金纳米棒的DNA超灵敏检测研究

采用氯金酸和硼氢化钠为原料合成金纳米粒子,在含有CTAB的生长溶液中加入一定量的种子溶液成长形成金纳米棒。在金纳米棒表面分别组装两种不同的巯基寡核苷酸探针,并通过靶探针进行"三明治"杂交。采用透射电子显微镜、紫外-可见-近红外光谱对杂交体系进行了表征。结果表明,所制备的金纳米棒分布均匀、分散性好,对寡核苷酸的检测限可达1pmol/L,能明显区分正错配。该方法简单易行,可应用于DNA、蛋白质等生物分子的识别。     

Monte Carlo simulation algorithm for B‐DNA

Understanding the structure–function relationship of biomolecules containing DNA has motivated experiments aimed at determining molecular structure using methods such as small‐angle X‐ray and neutron scattering (SAXS and SANS). SAXS and SANS are useful for determining macromolecular shape in solution, a process which benefits by using atomistic models that reproduce the scattering data. The variety of algorithms available for creating and modifying model DNA structures lack the ability to rapidly modify all‐atom models to generate structure ensembles. This article describes a Monte Carlo algorithm for simulating DNA, not with the goal of predicting an equilibrium structure, but rather to generate an ensemble of plausible structures which can be filtered using experimental results to identify a sub‐ensemble of conformations that reproduce the solution scattering of DNA macromolecules. The algorithm generates an ensemble of atomic structures through an iterative cycle in which B‐DNA is represented using a wormlike bead–rod model, new configurations are generated by sampling bend and twist moves, then atomic detail is recovered by back mapping from the final coarse‐grained configuration. Using this algorithm on commodity computing hardware, one can rapidly generate an ensemble of atomic level models, each model representing a physically realistic configuration that could be further studied using molecular dynamics. © 2016 Wiley Periodicals, Inc.     

关于序超半群的左超理想的研究

本文在序超半群中引入了极小左超理想和极大左超理想的概念, 并讨论了它们的一些相关性质. 进一步地, 引入了序超半群的弱素左超理想、拟素左超理想、拟半素左超理想及弱拟素左超理想的概念, 并讨论这四种素超理想之间的关系. 而且通过左超理想和弱~$m$-系刻画了序超半群的弱拟素左超理想. 同时, 借助于$m$-系对序超半群的拟素左超理想给出刻画. 尤其证明了序超半群$S$是强半单的当且仅当$S$的每个左超理想是$S$的包含它的所有拟素左超理想的交.     

水合锑酸钠中微量Sb(Ⅲ)的测定

以甲基橙为指示剂，在４ｍｏｌ．Ｌ＾－３ＨＣｌ中用硫酸测水合锑酸钠中微量Ｓｂ（Ⅲ），研究了溶样方法，介质酸度、等影响。结果表明，该法准确度较高，分析手续简便。     

正格序半群的格序和

本文将〔1～2〕中关于全序半群的有序和的讨论推广到格序半群的情况,由一类正格序半群构造出一新的正格序半群并讨论了正格序半群的一些性质。     

Research of an SHPB Device in Two-by-Two Form for Impact Experiments of Concrete-Like Heterogeneous Materials

A split Hopkinson pressure bar(SHPB)device in two-by-two form,including the bar bundle form and the single cylindrical bar form,was designed in response to the ...