In the present work, electrical conductivity (EC) and Vickers hardness of Mg–Zn– xCu ( x = 0, 0·5, 1·0 and 1·5) alloys in as cast, as solution and aged states have been investigated. The result shows that the EC of both as cast and as solution samples increases with Cu content, and Cu addition would have remarkably enhanced effect on EC and age hardening response during subsequent aging treatment. The 1·0Cu alloy aged at 160°C for 16 h after solution treatment had the optimal combined properties of high microhardness (94 HV) and high EC value (19·1, 106 S m−1), noting that the EC of pure Mg is 22·8 (106 S m−1). It is believed that the accelerated precipitation process for Cu containing alloy is attributed to the favourable interactions between Zn, Cu and vacancies. The microstructure associated with the improvement of EC and microhardness for Cu containing alloy is also discussed in detail.
Recognizing and distinguishing the dynamic characteristics of scanning tunneling microscopy (STM) system is fatal for studying STM image. In this paper, a method for analyzing system’s characteristics by using a damped harmonic oscillator model is presented. The model is driven by random force and all of its properties are described by damping and periodic. For the general solution of such harmonic oscillator’s Langevin equation is deduced and the auto-correlation function (ACF) is obtained for fitting curve. It is shown that damping and periodic property of the two curves have a good agreement by comparing the fitting curve with the auto-correlation curve of time series dates which are acquired by STM. It could be concluded that the damped harmonic oscillator model and auto-correlation method are feasible for analyzing the dynamic characteristics of STM system.
The design of atomic force microscopy (AFM) with high resolution is introduced in this paper. Mainly, we have developed the system design of the apparatus based on tunneling. AFM.IPC-208B, this kind of apparatus combines scanning tunnel microscopy (STM) and AFM availability, and its lens body with original frame enhances the capability of the machine. In order to analyze the performance of AFM.IPC-208B, as a new tool in the field of Life Science, we make use of the system to study natural mica and molecular protein structures of Cattle-insulin and human antibody immunoglobulin G (IgG) coupled with staphylococcus protein A (SPA). As the results of new applications, the resolution of AFM.IPC-208B is proved to be 0.1 nm, and these nanometer measurement results provide much valuable information for the study of small molecular proteins and HIV experiments.
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