Free energy perturbation approach for the rational engineering of the antibody for human hepatitis B virus

HzKR127 is the humanized monoclonal antibody effective for the neutralization of human hepatitis B virus. By means of the free energy perturbation (FEP) calculations based on molecular dynamic (MD) simulations, we examine the mutation-induced variations in the energetic and structural features associated with the interactions between HzKR127 and its antigen. N58A, Y96A, D97A, and D97A/Y102A mutants of HzKR127 are taken in account in this study for which the experimental data for relative efficacies with respect to the wild-type antibody are available. The results of the present MD-FEP simulation studies show that in order to enhance the affinity for the antigen, the engineering of HzKR127 should be made in such a way as to promote the dynamic stability of the overall protein conformation and that of the translational motion of the antigen in the antibody-antigen complex. The relative binding free energies of the four mutant antibodies obtained from MD-FEP calculations compare pretty well with the experimental mutagenesis data with the associated squared correlation coefficient of 0.96. This indicates that MD-FEP calculations may serve as a useful computational tool for rational antibody engineering. Discussed in detail are the differences in the structural features of antibody-antigen interactions between the wild-type and the mutant antibodies that are responsible for the change in binding affinities for the antigen.     

A comparative study of two techniques for improving power‐handling capability of CMOS T/R switches

This article proposes an asymmetric topology for transmit/receive (T/R) switches and more importantly presents a comparative study of both LC‐tuned and resistive body‐floating techniques for improving the power‐handling capability of the T/R switches in the same 0.18‐μm triple‐well CMOS. It is shown from simulations and measurements that the switches adopting either technique achieve comparable performances. For instance, the switch employing the LC‐tuned body‐floating technique exhibits insertion loss of 1.5 dB, isolation of 23.5 dB, and power‐handling capability of 22.5 dBm at 5.2 GHz, whereas the switch using the resistive body‐floating technique exhibits insertion loss of 1.3 dB, isolation of 24 dB, and power‐handling capability of 22.2 dBm, respectively. Therefore, one can conclude that the asymmetric topology with the resistive body‐floating technique is more suitable for designing T/R switches for wireless local area network applications as it consumes smaller silicon area. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.     

基于感应无线的高分辨率位置检测系统研究

为了提高移动机车位置检测精度,提出了一种感应无线位置的检测方法.该方法采用一条独特的编码电缆,利用电磁感应原理,建立了发送线圈与编码电缆之间的信息传输系统,并通过检测感应电动势的相位和幅度,得到移动机车的位置.分析了感应无线检测的原理和方法,推导出了位置检测公式,并进行相关试验.试验结果表明,感应无线位置检测分辨率为2mm,检测精度达到了国际先进水平,可广泛应用于移动机车自动定位中.     

A fuzzy-based interleaved multi-hop authentication scheme in wireless sensor networks

In sensor networks, a compromised node can either generate fabricated reports with false votes or inject false votes into real reports, which causes severe damage such as false alarms, energy drain and information loss. An interleaved hop-by-hop authentication (IHA) scheme addresses the former attack by detecting and filtering false reports in a deterministic and hop-by-hop fashion. Unfortunately, in IHA, all en-route nodes must join to verify reports while only a few are necessary to the authentication procedure. In this paper, we propose a fuzzy-based interleaved multi-hop authentication scheme based on IHA. In our scheme, the fuzzy logic system only selects some nodes for verification based on the network characteristics. Moreover, we apply a voting method and a hash-based key assignment mechanism to improve network security. Through performance evaluation, the proposed scheme is found to save up to 13% of the energy consumption and to provide more network protection compared to IHA.