金属离子在细菌浸取金属硫化矿中的催化作用

用氧化亚铁硫杆菌浸取某低品位原生硫化矿中Ｃｕ、Ｎｉ时，金属离子对细菌浸矿有明显的催化作用．金属离子（Ａｇ＋，Ｈｇ２＋，Ｃｏ２＋，Ｂｉ３＋）能显著提高细菌浸出Ｃｕ、Ｎｉ的浸出率．对细菌浸Ｃｕ而言，金属离子催化能力排序为：Ａｇ＋Ｃｏ２＋＞Ｂｉ３＋＞Ｈｇ２＋；对浸Ｎｉ，其排序则为：Ｂｉ３＋＞Ａｇ＋＞Ｃｏ２＋＞Ｈｇ２＋．金属离子的浓度、性质及矿石粒度等影响金属离子的催化能力．金属离子的催化作用机理与其性质、矿物结构及细菌氧化作用等因素有关     

A netlike DNA-templated Au nanoconjugate as the matrix of the direct electrochemistry of horseradish peroxidase

Herein, a novel DNA-templated Au nanoparticles (Au-DNA) nanoconjugate was prepared by using the combination of metallization and DNA compaction. The electrostatic interaction between Au(Ш) and the phosphate backbone of DNA formed the netlike coordination compound of Au(Ш)-DNA, and then the complex was chemically reduced to form Au nanoparticles in this network-like DNA conformation. The negatively charged nanoconjugate was used as the matrix for immobilization of horseradish peroxidase (HRP). A stable and well-defined redox peaks of HRP were observed on the Au-DNA nanoconjugate modified glassy carbon (GC) electrode, which indicated that the modified enzyme electrode displayed good direct electron transfer behavior and excellent reducing ability toward hydrogen peroxide (H₂O₂) with the apparent Michaelis–Menten constant (K_m) estimated to be 0.147 mM.     

Properties of Dendrimer‐Encapsulated Pt Nanoparticles Doped Polypyrrole Composite Films and Their Electrocatalytic Activity for Glucose Oxidation

A type of novel electroanalytical sensing nanobiocomposite material was prepared by electropolymerization of pyrrole containing poly(amidoamine) dendrimers‐encapsulated platinum nanoparticles (Pt‐PAMAM), and glucose oxidase (GOx). The Pt nanoparticles encapsulated in PAMAM are nearly monodisperse with an average diameter of 3 nm, and they provide electrical conductivity. Polypyrrole acts as a polymer backbone to give stable and homogeneous cast thin films, and it also defines the electrical conductivity. Both Polypyrrole and PAMAM can provide a favorable microenvironment to keep the bioactivity of enzymes such as glucose oxidase. The homogeneity of GOx/Pt‐PAMAM‐PPy nanobiocomposite films was characterized by atomic force microscopy (AFM). Amperometric biosensors fabricated with these materials were characterized electrochemically using cyclic voltammetry (CV), electrochemical impedance spectra (EIS) and amperometric measurements in the presence of hydrogen peroxide or glucose. All those show the resultant biosensor sensitivity was strongly enhanced within the nanobiocomposite film. The optimized glucose biosensor displayed a sensitivity of 164 μA mM^?1 cm^?1, a linear range of 0.2 to 600 μM, a detection limit of 10 nM, and a response time of <3 s.     

百焦耳级KrF准分子激光实验

介绍闪光Ⅱ号加速器泵浦的百焦耳级氟化氢激光研制情况，给出了激光器的构造和主要性能。在二极管电压为８４０ｋＶ，电流为２００ＫＡ条件下，获得了１５７Ｊ的最大激光能量，峰值功率为２．０ＧＷ。研究了激光输出能量随Ｆ２和Ｋｆ气体浓度的变化规律．     

基于回收期的科技创新项目决策模型分析

回收期方法是一种常用的评价方法.本文通过实物期权思想,对在不确定性下的科技创新项目,论证了回收期方法是合理的,通过本文的计算分析可知,较短的回收期隐含着较少的等待价值,也隐含着较高的单位资本回报.因此,利用回收期方法评价科技创新项目,不仅能得出与NPV方法评价的同样结论,而且还给投资者更多的信息,如几年之内可望收回投资.这对于资本不太雄厚的投资者来说更具有实际的意义,而对于资本雄厚的投资者也提供了能获得更多回报的投资决策评价方法.     

The study of laser self-mixing vibrometer employing different feedback regime using a VCSELS

Laser interferometry based on self-mixing effect widely used to measure displacement, velocity, vibration and distance due to compactness, non-contact, as well as low cost. An important use of the self-mixing effect inside a laser diode is in optical self-mixing vibrometer. We have experimentally investigated self-mixing interference produced by the feedback of light from a vibrated target into a vertical-cavity surface-emitting laser for sensing applications. In this paper, the self-mixing vibrometer employing different feedback regime is discussed and a theoretical analysis is also proposed. Numerical analysis focused on the distortion self-mixing waveform. Numerical analysis and experimental results show that mode-hop occurs when the laser self-mixing vibrometer employing at high feedback level.     

Vertically Oriented Silica Mesochannels as the Template for Electrodeposition of Polyaniline Nanostructures and Their Electrocatalytic and Electroanalytical Applications

A mesoporous silica film (MSF) with vertically oriented mesochannels on a conductive substrate serves as a hard‐template for electrodeposition of polyaniline (PANI). The PANI nanostructures thus prepared are orderly confined in silica mesochannels, eventually producing a robust hybrid film. The film displays a good electrocatalytic activity toward oxidation of ascorbic acid, and can be used for potentiometric pH sensing with a Nernstian response.     

放电泵浦准分子激光器电路参数测定

用同轴型电阻分压器和微型罗柯夫斯基线圈测量了紫外自动预电离放电泵浦ＸｅＣｌ难分子激光器充放电电压和电流，并由此给出了充放电回路参数。     

Vaporisation characteristics of methanol,ethanol and heptane droplets in opposed stagnation flow at low temperature and pressure

A computational model is developed and applied to study the vaporisation behaviour of three liquid fuels. This fundamental study is motivated by a need to understand how the performance of direct-injection-spark-ignition (DISI) engines may be affected by changes in fuel composition, especially alcohols. Currently, most DISI engines are designed for homogeneous-charge combustion, where the in-cylinder fuel injection, vaporisation and mixing is accomplished during the intake and early in the compression process. Thus the temperature and pressure are low, compared to post-compression conditions. The two-phase axisymmetric model is based upon an ideal opposed stagnation flow field. Liquid droplets are carried in one air stream that is met by an opposed air flow. Because of stagnation-flow similarity, the mathematical model can be represented as a one-dimensional boundary-value problem. Results show significant differences between methanol, ethanol and heptane fuels, which have potentially important impacts on the design and modification of fuel-injection systems for direct-injection engines with alternative fuels.     

Tribological properties of magnetite nanoparticles with various morphologies as lubricating additives

The manipulation of matter at the nanoscale has unleashed a great potential for engineering biomedical drug carriers, but the transport of nanoparticles (NPs) under nanoscale confinement is still poorly understood. Using colloidal physics to describe NP interactions, we have computationally studied the passive transport of NPs using experimentally relevant conditions from bulk into a nanochannel of 60–90 nm height. NP size, channel height, and the Debye length are comparable so that changes in nanoscale dimensions may induce substantial changes in NP transport kinetics. We show that subtle changes in nanochannel dimensions may alter the energy barrier by about six orders of magnitude resulting in different NP penetration depths and diffusion mechanisms: ballistic, first-order and quasi zero-order transport regimes. The analysis of NP diffusion by continuum methods reveals that apparent diffusivity is reduced by decreasing channel size. The continuum finite element (FE) numerical method reproduced the colloidal model results only when surface interactions were accounted for. These results give a new insight into NP passive transport at the boundaries of nanoconfined domains, and have implications on the design of nanoscale fluidics and NP systems for biomedical and engineering applications.