Further improvement of a transformerless, voltage-boosting inverter for AC modules

For reducing the manufacturing cost and for increasing the efficiency of module-integrated converter the transformerless concept is suitable. The new type inverter, which is proposed in this paper, basically works as buck boost DC–DC converter. Therefore, it is possible to reduce the number of the active switches in comparison with conventional inverter for AC modules because of simple circuit topology. In this paper authors present the control method and operation test results including both stand alone and grid connected for the new type transformerless inverter. These measurement results show that the performances can compete with the conventional small inverter (rated capacity around 50 W).     

InGaP/GaAs HBT X波段混合集成功率合成放大器的研制

研制了面向X波段应用的InGaP/GaAs HBT混合集成功率合成放大器模块.电路采用一种新颖的具有片上RC稳定网络的InGaP/GaAs HBT功率管作为功率合成单元以提高电路的稳定性,并采用紧凑的微带线并联匹配网络进行功率分配和合成.在8.1GHz,偏置为Vcc=7V,Ic=230mA的AB类工作条件下,连续波最大输出功率为28.9dBm,功率合成效率达到80%.     

Microbial community structure of a low sulfate oil producing facility indicate dominance of oil degrading/nitrate reducing bacteria and Methanogens

Analysis of microbial community structure of a low sulfate oil producing facility in Nigeria using 16S rRNA gene sequencing technique revealed dominance of oil degrading and nitrate reducing bacteria and methanogenic archaea in produced waters and oil samples namely, Marinobacter (37%), Azovibrio (21%), Thauera (10–28%), and Methanolobus (22%). On the contrary, the associated oil pipeline samples revealed massive dominance of potentially corrosive Methanolobus (60%) and Methanobacterium (25-27%). Further experimentation shows that the methanogens implicated in oil pipelines are corrosive moderate halophile that utilizes H₂/CO₂ and methanol as substrates. More emphasis should therefore be on methanogenic archaea as opposed to sulfate reducing bacteria (SRBs) during mitigation plans for microbially induced corrosion (MIC) in a low sulfate oil producing facility.     

MIC薄膜多晶硅材料的动态镍吸除技术基本机理及其应用

首先阐述了MIC薄膜多晶硅材料动态镍吸杂技术的基本机理和主要工艺过程,然后以多晶硅薄膜晶体管(poly-Si TFT)为例研究了动态吸杂技术的应用.在研究金属诱导晶化多晶硅材料(MIC poly-Si)和以之为有源层的poly-Si TFT的过程中,发现在MIC多晶硅薄膜中含有部分残余的镍成份.而大部分存在于对撞晶界的残余镍成份会造成大量的缺陷,这将导致TFT器件性能乃至整个系统的稳定性和可靠性的降低.为了改善MIC薄膜及器件质量,我们采用磷硅玻璃(PSG)动态镍吸杂技术,有效地吸除镍,降低多晶硅中镍的残留量,改善对撞晶界的缺陷密度,降低用之制备TFT的漏电流.该技术工艺过程简单,处理成本低,适合于大批量的工业化生产,有望成为制备高稳定性微电子器件与电路系统的必需工艺技术.     

微波集成MESFET放大器的全自动设计

本文发表了一种ＭＩＣ ＭＥＳ ＦＥＴ放大器的全自动设计方法，通常需要由设计者本人设定的初始考虑和网络拓扑，在这个基于知识库的智能化设计方法中全部可以机助自动确定，因而可提高设计质量。     

Ni金属诱导晶化非晶硅(a-Si:H)薄膜

对在氢化非晶硅薄膜（a-Si：H）上溅射金属Ni的样品进行金属诱导晶化（MIC）／金属诱导横向晶化（MILC），制备多晶硅薄膜（p-Si）的上艺及薄膜特性进行了研究。XRD测最结果表明非晶硅在500℃退火1h后就已经全部晶化。金属诱导晶化的优选晶向为（220）．而且晶粒随退火时间的延长而长大。非晶硅薄膜样品500℃下退火6h后的扫描电镜照片显示，原金属镍覆盖区非晶硅全部晶化．晶粒均匀．平均晶粒大小约为0．3μm，而且已经发生横向晶化。EDS测试Ni在晶化的非晶硅薄膜中的原子百分含量分析表明，金属Ni在MILC过程中的作用只是催化晶化．除了少量残留在MILC多晶硅中外．其余的Ni原子都迁移至晶化的前沿。500℃下退火20h后样品的Raman测试结果也表明．金属离子向周边薄膜扩散．横向晶化了非晶硅薄膜。     

The efficacy of disinfectant misting in the lairage of a pig abattoir to reduce Salmonella and Enterobacteriaceae on pigs prior to slaughter

Water misting/showers are used in abattoir lairages to improve meat quality, and to cool and calm pigs after transport and during hot weather. One novel approach, which has not been investigated to date, is to add a disinfectant to the misting water as a means of topically reducing Salmonella on pigs prior to slaughter, thereby potentially controlling this organism in the abattoir. The objective of this study was therefore to evaluate misting with water or with Virkon^® S (an approved disinfectant for use in the presence of animals), for their ability to topically reduce Salmonella on high seroprevalence pig herds before stunning and to reduce Enterobacteriaceae.Three experimental groups were investigated: control group (i.e., no misting); water group (misting with cold, 15–17 °C, water, herein referred to as water); and a disinfectant group (misting with 0.5% Virkon^® S). As pigs entered the abattoir, each animal was swabbed along its back before being allocated to its experimental group. Each group was randomly assigned to one of 3 lairage pens that were separated by non-trial pens. After 30 min of misting with water or disinfectant, pigs were moved to the stunning area, where each pig was again swabbed, as above. Swabs were analyzed for the presence of Salmonella and enumeration of Enterobacteriaceae.Before misting, Salmonella prevalence on the pigs was 79.0%, 72.1% and 83.6% for the control, water and disinfectant groups, respectively. After misting, Salmonella prevalence increased to 94.3% in the water group; whereas for the disinfectant group, the prevalence increased marginally to 85.9%. No change in Salmonella prevalence was detected for the control group. In line with the Salmonella results, no significant differences were observed in Enterobacteriaceae counts in the control group at either time point (4.37 and 5.01 log₁₀ CFU/cm², respectively) or in the disinfectant group before and after misting (4.02 and 4.26 log₁₀ CFU/cm², respectively). However, a 2.3 log₁₀ CFU/cm² increase in Enterobacteriaceae was recorded for the water group after misting as compared to before misting (p < 0.05).Since misting with water alone increased topical Salmonella contamination on pigs before slaughter, a risk assessment based on known Salmonella data, meat quality and welfare is recommended to determine whether its use is justifiable. On the other hand, the findings from this study suggest that misting with Virkon^® S at 0.5% could have a role in topical antisepsis of pigs contaminated with Salmonella prior to slaughter and as such this warrants further investigation.     

Potential use of carvacrol and citral to inactivate biofilm cells and eliminate biofouling

Biofouling (i.e., accumulation of microorganisms on wetted surfaces) represents a major problem in the food industries, since bacterial biofilms are common sources of persistent infections due to their resilience to cleaning and disinfection treatments. Therefore, alternative treatments based on the use of essential oils or their individual compounds against this bacterial adaptation phenomenon are currently being studied. This work presents a quantitative comparison of the disinfectant potential of 500–2000 μL/L of carvacrol or citral against mature biofilms of Staphylococcus aureus SC-01, Listeria monocytogenes EGD-e or Escherichia coli MG1655. Treatments with 1000 ppm of carvacrol or citral at 45 °C for 60 min were capable of reducing more than 5 logarithmic cycles of the sessile cells forming part of mature biofilms of all the three species. Furthermore, the synergism observed between carvacrol and heat allowed for the physical removal of biofilms by treatments simulating in situ wash conditions (80 °C/60 s). These results demonstrate the great potential of the essential oils’ constituents citral and carvacrol in the eradication of biofilms formed by foodborne pathogenic microorganisms.     

WPA被破解后的对策

本文介绍了Wi-Fi网络安全机制的演变和WPA如何被攻破以及可能产生的危害，由此应采取的对策。     

基于异构系统的生物序列比对并行处理研究进展

序列比对工作属于生物信息学的基础性研究领域。由于它具有应用广泛、计算复杂以及海量数据等特点,加之现在高性能计算的兴起,使得近年来序列比对并行处理技术快速发展。首先介绍了序列比对领域高性能计算的新进展,接着从体系结构特征入手对其研究进行分类,并对每类方法的实现细节和性能进行分析比较,从中不难看出访存控制、同步、数据交互以及算法可扩展性等问题均为目前基于异构系统的序列比对并行处理研究的关键点。最后,对该领域的未来研究方向进行了展望。