Shot noise in nano-electronic systems under the perturbation of ac fields

Current noise exists in circuits and electronic devices generally, and it exhibits specific features as the system reaches nanometer size. The noise in the nano-system where external ac fields are applied plays an important role, since the properties of the fields and the nano-system together govern the resulting noise. In this paper, we present the derivation of shot noise by employing the non-equilibrium Green’s function technique. The more general formulas for the current correlation and noise spectral density are given. The system is composed of a central nanosystem coupled to electrodes, and the obtained noise formulas are related to the Green’s functions of detailed central regime and the terminals. As an example, we have performed the numerical calculation on a system with a toroidal carbon nanotube coupled to normal metal leads. The noise and Fano factor show intimate relation with the structure of the system and ac fields. The Aharonov-Bohm-like behaviors on the shot noise spectral density and Fano factor are observed to exhibit oscillation structures with period of quantum flux.      

加弧辉光离子渗NiCr与喷丸强化复合处理对钛合金微动疲劳性能的影响研究

研究了钛合金表面加弧辉光离子渗NiCr层的相组合和分布,对NiCr渗 层进行喷丸形变强化后处理,以协同提高钛合金耐微动疲劳性能。研究结果表明：利用加弧辉光离子渗技术可以获得由Ni3Ti金属间化合物等组成的渗镀复合层,从而提高钛合金的表面硬度和耐磨性能;NiCr渗层的耐磨性能与喷丸强化引入的表面残余压应力协同作用,使钛合金经加弧辉光离子渗NiCr和喷丸形变强化复合处理后的耐微动疲劳性能较单一喷丸强化处理更好。     

Polymer‐anchored Ru(II) complex as an efficient catalyst for the synthesis of primary amides from nitriles and of secondary amides from alcohols and amines

A polymer‐anchored ruthenium(II) catalyst was synthesized and characterized. Its catalytic activity was evaluated for the preparation of primary amides from aqueous hydration of nitriles in neutral condition. A range of nitriles were successfully converted to their corresponding amides in good to excellent yields. The catalyst was also effective in the preparation of secondary amides from the coupling of alcohols and amines. The catalyst can be facilely recovered and reused six times without a significant decrease in its activity. Copyright © 2014 John Wiley & Sons, Ltd.     

One‐shot pseudo‐time method for aerodynamic shape optimization using the Navier–Stokes equations

This paper presents a numerical method for aerodynamic shape optimization problems in compressible viscous flow. It is based on simultaneous pseudo‐time stepping in which stationary states are obtained by solving the pseudo‐stationary system of equations representing the state, costate and design equations. The main advantages of this method are that it blends in nicely with previously existing pseudo‐time‐stepping methods for the state and the costate equations, that it requires no additional globalization in the design space, and that a preconditioner can be used for convergence acceleration which stems from the reduced SQP methods. For design examples of 2D problems, the overall cost of computation can be reduced to less than 2 times the forward simulation runs. Copyright © 2011 John Wiley & Sons, Ltd.     

INFLUENCE OF DISPLACEMENT OF SATURATED SAND STRATUM ON PRE-STRESSED ANCHORS

土层变形是造成预应力值波动甚至失效的重要原因. 利用载荷位移传递函数,基于弹性理论建立了饱和粉细砂层变形过程中锚索受力模型,通过实例研究了锚索预应力值在施工过程中的变化规律及锚固体在地层变形中的受力特性,结果表明锚固体接触面剪切刚度,锚索倾斜角度以及锚固体直径都是影响锚固体内力及接触面剪切应力的重要因素,为类似的预应力锚索支护工程的设计施工提供经验.     

变弹模成层岩基受预锚荷载作用的三维光弹性实验研究

本文介绍了变弹模成层岩基受预锚荷载作用的三维光弹性实验过程。求出了岩基在锚固应力作用下锚根附近的应力场,并和电测成果、理论计算成果进行了比较,结果非常相近.为进一步探讨这些问题提供了可靠的依据.     

基于遗传算法的铅球投掷过程分析

运用有关力学知识建立了铅球投掷过程的数学模型，采用遗传算法对投掷过程进行优化，获得了投掷过程的各项最佳参数，并给出了最大的投掷距离．还对铅球投掷过程中的影响因素进行了灵敏度分析，确定出各影响因素的主次关系，为制定科学的运动训练计划提供了参考依据。     

预应力锚杆加固围岩的力学机制研究

本文通过弹性理论分析, 给出了预应力锚杆施加于围岩(开挖边界附近的岩体)的附加应力场和附加位移场, 并由此得到预应力锚杆提供给围岩的附加应力状态的普遍形式。     

Development of a Simple and Inexpensive Optical Absorption One‐Shot Sensor Membrane for Detection and Determination of Cyanide Ions in Water Samples

A new one‐shot optical cyanide ion sensor is proposed for determination of cyanide ions. The sensor was constructed by immobilizing crystal violet (CV) on triacetylcellulose membrane. The sensing mechanism involves reaction between cyanide ions and the immobilized CV at pH = 5.4, which results in a decrease in absorbance of the membrane at 600 nm. The sensor shows sufficient repeatability, reproducibility, operational lifetime of 3 weeks, and a response of less then 10 min under the optimum conditions and response time of 8 min. Cyanide can be determined in the concentration range of 50.0‐800 μg mL^‐1 with a detection limit of 5.0 μg mL^‐1. Most ions do not interfere with the determination of cyanide ions. The proposed sensor was successfully applied to the determination of cyanide in spiked water samples.     

Sortase-Mediated Transpeptidation for Site-Specific Modification of Peptides,Glycopeptides, and Proteins

Sortases are a family of transpeptidases found in gram-positive bacteria responsible for covalent anchoring of cell surface proteins to bacterial cell walls. It has been discovered that sortase A (SrtA) of Staphylococcus aureus origin is rather promiscuous and can accept various molecules as substrates. As a result, SrtA has been widely used to ligate peptides and proteins with a variety of nucleophiles, and the ligation products are useful for research in chemical biology, proteomics, biomedicine, etc. This review summarizes the recent applications of SrtA with special emphasis on SrtA-catalyzed ligation of carbohydrates with peptides and proteins.