Molecular analysis of human immunoglobulin heavy chain variable genes (IgVH) in normal and malignant B cells

The diagnostic value of monitoring human cytomegalovirus (HCMV) late pp67 mRNA expression by nucleic acid sequence-based amplification (NASBA) after renal-allograft transplantation was evaluated. RNAs were isolated from 489 whole-blood specimens of 42 patients for the specific amplification of the late pp67 (UL65) mRNA. NASBA results were compared to results from the pp65 antigenemia assay, virus isolation by cell culture, and serology. The sensitivity value for NASBA proved to be higher than that for the antigenemia assay (50 versus 35%) for the detection of HCMV infection, while the sensitivity values of cell culture and NASBA were comparable (54 and 50%, respectively). NASBA detected the onset of HCMV infection simultaneously with cell culture and the antigenemia assay. Both the antigenemia assay and NASBA are very specific (100%) and highly predictive (100%) for the onset of HCMV infection. Antiviral therapy with ganciclovir resulted in negative results for cell culture, the antigenemia assay, and NASBA. In conclusion, monitoring HCMV pp67 mRNA expression by NASBA is a highly specific method for the detection of HCMV infection in renal-allograft recipients and is more sensitive than the antigenemia assay. Furthermore, NASBA can be used to monitor the progression of HCMV infections and the effect of antiviral therapy on viral activity.     

Core–Shell Photoanodes for Photoelectrochemical Water Oxidation

Photoelectrochemical (PEC) water splitting into hydrogen and oxygen is a promising solution for the conversion and storage of solar energy. Because sluggish water oxidation is the bottleneck of water splitting, the design and preparation of an efficient photoanode is intensively investigated. Currently, all known photoanode materials suffer from at least one of the following drawbacks: ① low carriers separation efficiency; ② sluggish surface water oxidation reaction; ③ poor long-term stability; ④ insufficient water adsorption and gas desorption. Core–shell configurations can endow a photoanode with improved activity and stability by coating an overlayer that plays energetic, catalytic, and/or protective roles. The construction strategy has an important effect on the activity of a core–shell photoanode. Nonetheless, the mechanism for the improvement of performance is still ambiguous and is worthy of a closer examination. In this review, the successes and challenges of core–shell photoanodes for water oxidation, focusing on synthesis strategies as well as functionalities (facilitating carrier separation, surface reaction promotion, corrosion prevention, and bubble detachment) are explored. Finally, the perspectives of this class of materials in terms of new opportunities and efforts are discussed.     

MBE-grown ZnSSe thin films on ITO substrates for liquid-crystal light valve applications

The MBE growth of ZnSSe alloy thin films on ITO substrates using ZnS and Se sources was studied and various structural and opto-electronic properties of the as-grown thin films were characterised. The XRD rocking curves resulting from these films indicate that the as-grown polycrystalline ZnSSe thin films have a preferred orientation along (1 1 1) direction. The evaluated crystal sizes as deduced from the FWHM of the XRD layer peaks were found to show a strong growth temperature dependence with the optimised temperature at about 290°C. TEM measurements done on these thin films also indicate a similar growth temperature dependence. The TEM cross-sectional micrograph of the sample grown at the optimised temperature shows a well-defined columnar structure whose nucleation seems to be highly correlated with the ITO grains. UV responsivity as high as 0.01 A/W and more than three orders of magnitude in rejection power for wavelengths longer than 450 nm have been achieved. It was also found that the sample grown at the optimised temperature has the lowest resistivity of 4.3×10¹¹ Ω cm, which provides a good match with that of a liquid-crystal layer. These results indicate that MBE-grown ZnSSe thin film is a promising candidate as the photoconductive material of liquid-crystal light valves for UV imaging applications.     

Effects of metallization characteristics on gold wire bondability of organic printed circuit boards

Organic printed circuit boards (PCBs) with Au/Ni plates on bond pads are widely used in chip-on-board (COB), ball grid array (BGA), and chip-scale packages. These packages are interconnected using thermosonic gold wire bonding. The wire bond yield relies on the bondability of the Ni/Au pads. Several metallization parameters, including elemental composition, thickness, hardness, roughness, and surface contamination, affect the success of the solid state joining process. In this study, various characterization and mechanical testing techniques are employed to evaluate these parameters for different metallization schemes with varying Ni and Au layer thicknesses. The pull force of Au wires is measured as a function of plasma treatment applied before wire bonding to clean the bond pads. Close correlations are established between metallization characteristics and wire bond quality.     

Visualization of Negative Refraction in Chiral Nihility Media

Chiral nihility media are known to produce a backward wave as one of their two polarizations, yielding negative refraction at the interface of the chiral nihility medium and free space. In this paper, the analysis of chiral nihility effects is illustrated by showing the propagation of a Gaussian beam, both reflected and refracted from an air-chiral interface, and through layered chiral nihility media that are matched to free space. The critical angle for total reflection, and the index-matched total transmission in a matched chiral half-space, are demonstrated. Also demonstrated are the wave splitting, wave widening, and a wave of “standing phase” in matched chiral nihility slabs.     

Analysis of leaky bucket mechanism based on burstiness characterization

In high-speed networks, a congestion control strategy has to manage bandwidth allocation based on the characteristics of input traffic sources. Accordingly, the definition of traffic characterization becomes significant in all aspects concerning network performance. In this paper, the burstiness characterization of a traffic stream is based on a virtual queue principle. We study the leaky bucket mechanism as a regulator element that controls input traffic before access to a newwork, as well as inside a network. To protect an input traffic stream, we investigate the optimal parameter settings of a leaky bucket. In addition, we analyse the worst case performance, and obtain upper bounds on loss probability and packet delay. We also determine the characteristics of an output stream in the worst case. Such performance bounds reveal the effectiveness of a leaky bucket, and provide enough information for the QOS satisfaction of the network users.     

Diurnal thermal cycling effects on microwave signatures of thin seaice

To investigate effects of diurnal thermal cycles on C-band polarimetric backscatter and millimeter-wave emission from sea ice, the authors carried out a winter experiment at the outdoor geophysical research facility (GRF) in the cold regions research and engineering laboratory (CRREL), the ice sheet grew from open sea water to a thickness of 10 cm in 2.5 days, during which they took polarimetric backscatter data with a C-band scatterometer, interlaced with brightness temperature measurements at 90 GHz in conjunction with meteorological and sea ice characterizations. The initial ice growth in the late morning was slow due to high insolation. As the air temperature dropped during the night, the growth rate increased significantly. Air temperature changed drastically from about -12 to -36°C between day and night, the diurnal thermal cycle repeated itself the next day and the growth rate varied in the same manner. Ice temperature profiles clearly show the diurnal response in the ice sheet with a lag of 2.5 h behind the time of the maximum short-wave incident solar radiation. The diurnal cycles are also evident in the millimeter-wave brightness temperature data, measured sea ice backscatter revealed substantial diurnal variations up to 6 dB with repeatable cycles in synchronization with the temperature cycles and the brightness temperature modulations, the diurnal cycles in backscatter indicate that the dominant scattering mechanism related to thermodynamic processes in sea ice is reversible, a diurnal backscatter model based on sea ice electrodynamics and thermodynamics explains the observed diurnal signature. This work shows that diurnal effects are important for inversion algorithms to retrieve sea ice geophysical parameters from remote sensing data acquired with a satellite synthetic aperture radar (SAR) or scatterometer on Sun-synchronous orbits     

分段显示器成就各式智能面板

电子纸（EPD）技术有一些瑕疵．缺乏市场成熟性。电子纸用户是少数,围绕EPD的生态体系和下层基础构建还在发展中,比如LCD显示器拥有众多的标准驱动电路支持,但可以设想,EPD的瑕疵会随着市场的发展而淡化。EPD的其它缺陷还包括有电压要求：即高压驱动（〉10V）,尽管驱动电流非曾低。随着时间推移EPD比其它显示媒介缩短了响应时间。当然,尽管存在这些缺点,但都会在：降来得到改正,EPD为各种创新应用提供了独到的方案。分段式EPD凭据其超薄、不规謦性、柔韧性能,可为各种类型的显示器提供高对比显示,通过运用低功耗电子系统来匹配低功耗图形显示,设计师可以实现产品便携和长寿电池的双重性能。     

Data hiding watermarking for halftone images

In many printer and publishing applications, it is desirable to embed data in halftone images. We proposed some novel data hiding methods for halftone images. For the situation in which only the halftone image is available, we propose data hiding smart pair toggling (DHSPT) to hide data by forced complementary toggling at pseudo-random locations within a halftone image. The complementary pixels are chosen to minimize the chance of forming visually undesirable clusters. Our experimental results suggest that DHSPT can hide a large amount of hidden data while maintaining good visual quality. For the situation in which the original multitone image is available and the halftoning method is error diffusion, we propose the modified data hiding error diffusion (MDHED) that integrates the data hiding operation into the error diffusion process. In MDHED, the error due to the data hiding is diffused effectively to both past and future pixels. Our experimental results suggest that MDHED can give better visual quality than DHSPT. Both DHSPT and MDHED are computationally inexpensive.     

Finite-difference time-domain simulation of scattering from objectsin continuous random media

A three-dimensional (3D) finite-difference time-domain (FDTD) scheme is introduced to model the scattering from objects in continuous random media. FDTD techniques have been previously applied to scattering from random rough surfaces and randomly placed objects in a homogeneous background, but little has been done to simulate continuous random media with embedded objects where volumetric scattering effects are important. In this work, Monte Carlo analysis is used in conjunction with FDTD to study the scattering from perfectly electrically conducting (PEC) objects embedded in continuous random media. The random medium models under consideration are chosen to be inhomogeneous soils with a spatially fluctuating random permittivities and prescribed correlation functions. The ability of frequency averaging techniques to discriminate objects in this scenarion is also briefly investigated. The simulation scheme described in this work can be adapted and used to help in interpreting the scattered field data from targets in random environments such as geophysical media, biological media, or atmospheric turbulence