Highly efficient photocatalytic degradation for antibiotics and mechanism insight for Bi2S3/g-C3N4 with fast interfacial charges transfer and excellent stability

Bi₂S₃/g-C₃N₄ (BSCN) samples with different mass ratios of CN to BS were prepared by a facile and practicable hydrothermal method with 2D g-C₃N₄ nanosheets (CN). The microscopic morphology and structure of pure CN, BS and BSCN were measured by multiple testing methods. Analysis results show that the BSCN was prepared successfully, and the Bi₂S₃ nanoparticles closely and uniformly adhered to the surface of CN with sheet-like structure. The introduction of Bi₂S₃ did not change the structure of the CN. The results of the ultraviolet–visible spectroscopic analysis, photoluminescence spectra and electrochemical performance indicated that BSCN showed superior visible-light response compared with CN, and the separation and transfer efficiency of photogenerated carriers was significantly improved. With the decrease of mass ratio of CN/BS, the photocatalytic activity of BSCN initially increased and then decreased for 20 ppm of Rhodamine B solution (RhB), and the Bi₂S₃/g-C₃N₄-B with a mass ratio of 8:1 for CN to BS showed optimal photocatalytic performance (98.98%). Furthermore, the Bi₂S₃/g-C₃N₄-B exhibited apparent degradation effects (1.021 x10^-2, 0.879 x10^-2 and 0.793 x10^-2 min^?1) to three kinds of antibiotics (tetracycline, ciprofloxacin, and oxytetracycline). The BSCN samples still maintained higher degradation efficiency after five cycles of degradation to tetracycline. The capture experiments and the electron spin resonance (ESR) spectra analysis indicated that the h⁺ and ·O₂^? played a major role, and ·OH played secondary role during the photocatalytic reaction.     

陈化体系组成对Ce0.65Zr0.35O2储氧材料性能的影响

采用共沉淀法制备了Ce_0.65Zr_0.35O₂(CZ)储氧材料, 在传统的水陈化体系中引入了乙醇, 研究了乙醇的加入对CZ储氧材料性能的影响. 对所制备样品进行了傅里叶变换红外(FTIR)光谱、X射线光电子能谱(XPS)、粉末X射线衍射(XRD)、扫描电镜(SEM)、N₂吸附-脱附、储氧量(OSC)和H₂程序升温还原(H₂-TPR)的表征, 并考察了以CZ储氧材料为载体制备的单钯催化剂的三效性能. 结果表明, 乙醇引入陈化体系对样品的结构和性能有显著影响. 以醇水共存体系陈化制备的CZ储氧材料颗粒小、堆积松散、孔径分布宽、孔容大, 具有优异的储氧性能和热稳定性, 经1000 °C焙烧后, 比表面积为29.3 m²·g^-1, 储氧量仍高达520 μmol·g^-1. 以此为载体制备的单钯催化剂, 空燃比操作窗口宽, 对C₃H₈、CO、NO的转化明显优于水陈化体系制备的储氧材料所制备的催化剂.     

Separation and Detection of Arsenic and Selenium Species in Environmental Samples by HPLC-ICP-MS

A method is presented for arsenic speciation analysis of an oyster sample using ion chromatography coupled with an inductively coupled plasma mass spectrometry (ICP-MS) instrument. A strong anion exchange resin was employed with a step gradient elution of 0.1 mM/0.1 M K 2 SO 4 at pH 10.2. Arsenobetaine and dimethylarsinic acid were determined following extraction based on trypsin enzymolysis with 95-100% extraction efficiency. Limits of detection in the range 0.1-0.3 mg kg m 1 of arsenic were obtained for organic arsenic species. No inorganic arsenic was detected. Validation was performed using TORT-2 as a certified reference material. Although high performance liquid chromatography (HPLC) coupled to ICP-MS is an effective method for speciation analysis it is not always necessary to obtain such a detailed picture. A simple liquid chromatographic separation technique based upon mini-column technology is presented. It was developed to obtain a fast, efficient and reliable separation of inorganic from organic, i.e. assumed toxic from non-toxic, arsenic and selenium species suitable for use as an initial screening method for environmental analysis. Two types of strong anion exchange resin were tested. Excellent separation was obtained for both min-column resins and analysis times were within 7 min. Limits of detection obtained for inorganic arsenic, organic arsenic, selenomethionine, Se IV and Se VI were 1.6, 1.8, 66, 32 and 22 µg kg m 1 , respectively.     

磁场电源在 HL-2M 装置初始等离子体放电中的应用

磁场电源是 HL-2M 装置初始等离子体放电的重要组成部分,它关系到 HL-2M 装置零场的建立,等 离子体的击穿和维持及位形控制。为实现初始等离子体放电所需的供电电压和电流,对磁场电源从主回路、控制、 测量和保护分别作了相应的调整。在此基础上进行了大量的工程调试,确保了磁场电源的控制和保护等性能达到 初始等离子体放电的需求。在磁场电源运行中,电源控制性能和输出参数的一致性、纹波质量等都有显著提高。 介绍了磁场电源在调试及 HL-2M 装置初始放电中的应用。     

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引进了美国GAMMA公司的高精度数字式可调标准光源RS-5B,并对其性能参数进行了测试。结果表明,该光源光强空间分布非常稳定,在光强大于0.001μW•cm-2时,复位性优于1%;在光强大于0.01μW•cm-2时,稳定性优于0.5%。其输出光强与标称值呈线性分布关系。这些优良的参数和特性满足聚变物理标定研究中对标定源的需求,为物理实验数据分析和计算模拟提供了条件。     

Characterization of a low concentrator photovoltaics module

Low concentration photovoltaic (LCPV) systems have the potential to reduce the cost per kWh of electricity compared to conventional flat-plate photovoltaics (PV) by up to 50%. The cost-savings are realised by replacing expensive PV cells with relatively cheaper optical components to concentrate incident solar irradiance onto a receiver and by tracking the sun along either 1 axis or 2 axes. A LCPV module consists of three interrelated subsystems, viz., the optical, electrical and the thermal subsystems, which must be considered for optimal module design and performance. Successful integration of these subsystems requires the balancing of cost, performance and reliability. In this study LCPV experimental prototype modules were designed, built and evaluated with respect to optimisation of the three subsystems and overall performance. This paper reports on the optical and electrical evaluation of a prototype LCPV module.     

一种用于土壤非金属养分测试的光纤探头式分光光度计

针对测土配方施肥技术中要求快速、便捷、高效地进行土壤养分测试的需求,文章基于浸入式光纤探头、平场凹面全息光栅、二极管线阵检测器开发了一种光纤探头式分光光度计用于土壤养分中非金属元素的快速、准确测试。基于国家计量检定规程JJG 178—2007对紫外、可见、近红外分光光度计的性能检测方法测试的该仪器的波长最大允许误差与波长重复性、基线平直度、透射比最大允许误差与透射比重复性均达到了国标第Ⅲ级别标准,其最小光谱带宽、噪声与漂移、杂散光基本达到了国标第Ⅳ级别标准。基于该仪器测试的土壤硝态氮、铵态氮、有效磷、有效硫、有效硼、和有机质含量与基于商用的国产单光束和进口双光束分光光度计测试的结果呈极显著的线性相关关系,其回归方程的斜率接近于1,且对比数据之间无显著性差异。因此,该光纤探头式分光光度计可用于土壤非金属养分的快速、准确测试。     

容积式制冷机组性能测试的一种改进实验装置

针对容积式压缩机组测试设备的初始投资高,能耗高的问题,介绍了一种改进的实验装置.其制冷量测量采用制冷剂液体流量计法。研究测试结果表明:(1)改进实验装置控制精度较高;(2)改进的实验装置的相对误差为1.5%。与房间量热计相比,该实验装置节能72.2%且初始投资节省60%。     

Numerical investigation of finite-source multiserver systems with different vacation policies

Systems with vacations are usually modeled and analyzed by queueing theory, and almost all works assume that the customer source is infinite and the arrival process is Poisson. This paper aims to present an approach for modeling and analyzing finite-source multiserver systems with single and multiple vacations of servers or all stations, using the Generalized Stochastic Petri nets model. We show how this high level formalism, allows a simple construction of detailed and compact models for such systems and to obtain easily the underlying Markov chains. However, for real vacation systems, the models may have a huge state space. To overcome this problem, we give the algorithms for automatically computing the infinitesimal generator, for the different vacation policies. In addition, we develop the formulas of the main exact stationary performance indices. Through numerical examples, we discuss the effect of server number, vacation rate and vacation policy on the system’s performances.     

Performance appraisal based on distance function methods

Performance appraisal is a process used by some firms to evaluate their employees’ efficiency and productivity in order to plan their promotion policy, salary policy, layoffs policy, etc. Initially this process was just carried out by the executive staff, but recently it has evolved into an evaluation process based on the opinion of different reviewers, supervisors, collaborators, customers and the employees themselves (360-degree method). In such an evaluation process the reviewers evaluate some indicators related to employees performance appraisal. In this paper we propose an evaluation framework where there are different sets of reviewers taking part in the evaluation process. Since reviewers have a different knowledge about the evaluated employee, it seems suitable to offer a flexible framework in which different reviewers can express their assessments in different finite scales according to their knowledge. The final aim is to compute a global evaluation for each employee, that can be used by the management team to make their decisions regarding their human resources policy. In this way, to obtain a global evaluation for each employee, we propose a methodology able to aggregate individual valuation in a metric L_p framework. In this context, the associated optimization problems can be reduced to an Extended Goal Programming formulation that is very easy to compute.