Occurrence and characteristics of Vibrio vulnificus in retail marine shrimp in China

Vibrio vulnificus is a gram-negative bacterium that naturally occurs in estuarine waters and marine environment. Consumption of seafood contaminated with V. vulnificus or exposure to the contaminated water causes septicemia, gastroenteritis or wound infections in humans. This study aimed at identifying the prevalence of V. vulnificus in shrimps in Chinese seafood market. From June to September 2009, 239 samples encompassing six shrimp species were collected from ten cities in China. To quantify the prevalence and the levels of V. vulnificus in shrimps, the most probable number (MPN) method was used combining with the polymerase chain reaction (PCR) which was used to classify the isolates by detecting V. vulnificus hemolysin gene (vvhA). One hundred and forty out of 239 samples were positive for V. vulnificus, with the geometric mean level at 153.3 MPN/g. The prevalence and levels of V. vulnificus in shrimps varied in different geographic areas, with the values for the samples in the South cities (179.6 MPN/g) remarkably higher than that in the North cities (7.6 MPN/g). In addition, we found that 61.7% (79/128) of the V. vulnificus positive samples contained C-type (Clinical) strains and 8 contained E-type (Environmental) strains. The antimicrobial susceptibility of the isolates to 12 antibiotics was tested as well. Most of the 169 isolates remained susceptible to the majority of antimicrobials tested, whereas some strains tend to be less sensitive to amikacin, ampicillin, tetracycline and gentamicin. In conclusion, V. vulnificus is commonly found in retail marine shrimp in Chinese seafood market, and most of the shrimp samples contained C-type strains, which may pose a potential threat to human health.     

Study of HgCdSe Material Grown by Molecular Beam Epitaxy

Much progress has been made in developing high-quality HgCdTe/Si for large-area focal-plane array (FPA) applications. However, even with all the material advances made to date, there is no guarantee that this technology will be mature enough to meet the stringent FPA specifications required for long-wavelength infrared (LWIR) systems. With this in mind, the Army Research Laboratory (ARL) has begun investigating HgCdSe material for infrared (IR) applications. Analogous to HgCdTe, HgCdSe is a tunable semiconductor that can detect any wavelength of IR radiation through control of the alloy composition. In addition, several mature, large-area bulk III–V substrates are nearly lattice matched to HgCdSe, giving this system a possible advantage over HgCdTe, for which no scalable, bulk substrate technology exists. We have initiated a study of the growth of HgCdSe using molecular beam epitaxy (MBE). Growth temperature and material flux ratios were varied to ascertain the best growth conditions. Smooth surface morphology has been achieved using a growth temperature much lower than that used for HgCdTe. Additionally, zero void defects were nucleated at these lower temperatures. Preliminary data suggest a linear relationship between the Se/Cd flux ratio used during growth and the cutoff wavelength as measured by Fourier-transform infrared (FTIR) spectroscopy.     

Aqueous-Develop,Photosensitive Polynorbornene Dielectric: Optimization of Mechanical and Electrical Properties

The impact of thermal cure conditions on the mechanical and electrical properties of an epoxy cross-linked network incorporating a polynorbornene (PNB) dielectric polymer was studied. The cross-linking of the dielectric composition was achieved by an acid-catalyzed cationic cure reaction initiated by either thermal or photolytic activation of a photoacid generator. It is proposed that the observed mechanical and electrical properties of the fully cured polymer composition are the result of the development of a three-dimensional cross-linked network tying together the PNB polymer and multifunctional epoxy additives. The epoxy ring-opening reaction was measured using Fourier-transform infrared spectroscopy. The reduced modulus, internal film stress, dielectric constant, and swelling behavior of cross-linked films were studied as a function of curing temperature. Trends in the observed properties are explained by formation of a three-dimensional cross-linked network and degradation of the cross-links between the multifunctional epoxy additives at high temperature. It was also found that exposure of the film to aqueous base plays a role in the cure process and has a positive effect on the final properties. The optimum values of modulus, dielectric constant, residual stress, and moisture content were found for films cured at 160°C for 1 h. This relatively low cure temperature is potentially advantageous in device assembly and processing.     

一种改进的基于FFT的信号插值算法

在传统运用FFT进行信号插值运算的基础上,提出了一种提高插值精度的改进算法.通过子序列重叠和裁剪,舍弃重建序列边缘误差较大的样点,再将相对准确的样点进行重组,从而大幅提高插值精度.实验结果表明:与Prasad等算法相比,在计算量增加3.1％的情况下,不同子序列长度对应的归一化均方误差平均下降至原来的1/19;在计算量增加2倍的情况下,不同子序列长度对应的归一化均方误差平均下降至原来的1/75.     

Detoxification of Zearalenone by viable and inactivated cells of Planococcus sp

The capacity of Planococcus sp. strain S118 to remove Zearalenone (ZEN) from liquid medium in varying conditions was investigated. The results indicated that Planococcus sp. S118 removed ZEN by binding process. Strain S118 significantly reduced the levels of ZEN in the liquid medium; the viable and heat-inactivated bacteria could remove 21.82% and 47.82% of ZEN, respectively. Heat, acid, and Triton-100 treatment significantly enhanced the capability of removing ZEN. The detoxifying capability depended on the incubation period, concentration of bacteria, pH, and temperature. Planococcus sp. S118 likewise possessed the capability to remove Zearalanone (ZAN), which is one of ZEN analogues. The viable and heat-inactivated bacteria could remove 16.36% and 34.26% of ZAN, respectively. The detoxifying capability of ZEN and ZAN by heat-inactivated bacteria were significantly influenced by each other.     

另一个“红色13”——海因里希·巴特勒斯的Bf109G-6/R6战斗机

我本次制作的是巴特勒斯于在1943年秋,驻地中海战区希腊卡拉马基(Kalamaki)时驾驶的一架Bf109G-6/R6型红色13号,此时他已经取得70个击落战果,翼下挂载R6武器套件MG151/20吊     

Investigation of growth behavior of Al-Cu intermetallic compounds in Cu wire bonding

In this work, we investigate the intermetallic compound formation in Cu wire bonded device. Voids near the Cu side at the bond interface are clearly seen. Nevertheless, these voids do not seem to interfere with the function of the unit. High temperature storage test (HTST) results show that there are Al₂Cu and AlCu in the damaged unit while Al₂Cu and Al₄Cu₉ appear in the good unit. The results clearly show that the Al layer is exhausted in the damaged unit while those with Al₄Cu₉ on the Cu side pass HTST with unconsumed Al. Theoretical calculations indicate that AlCu and Al₄Cu₉ are energetically more favorable than Al₂Cu, which is consistent with the reported IMC forming sequence. Formation energy of AlCu is compatible but slightly lower to that of Al₄Cu₉, suggesting AlCu tends to be the most stable phase among all. The reason why the Al layer is completely consumed in one case and some Al layer remains in the other is due to the fact that the formation of AlCu requires more than twice the amount of Al than Al₄Cu₉ for the same amount of Cu consumed. The complete consumption of Al is proposed as the reason responsible for the failure of the damaged unit.     

High electrical performance liquid-phase HBr oxidation gate insulator of InAlAs/InGaAs metamorphic MOS-mHEMT

The InAlAs/InGaAs metal-oxide-semiconductor metamorphic high electron mobility transistors (MOS-mHEMTs) were demonstrated by using liquid-phase HBr treatment technology to form a high-quality gate insulator layer. In this study, liquid-phase HBr treatment technology was used instead of traditional plasma-assisted chemical vapor deposition (PECVD) because the proposed technology can prevent the device from plasma-induced damage. The novel HBr + ultraviolet (UV) illumination treated InGaAs provided a lower surface states such that MOS structure can be efficiently obtained. Besides, based on the atomic force microscopy (AFM) measurement, the native oxides film formed by HBr + UV illumination treatment also provided a better surface roughness compared to traditional NH₄OH and only HBr treatment solutions. It is beneficial for reducing the surface traps and lowering the leakage current in MOS-mHEMTs. Based on the flicker noise and load-pull power measurement results, HBr + UV treatment mHEMT achieved a low flicker noise at high current level and the power-added efficiency can be enhanced up to 9%. Therefore, the novel liquid phase method of HBr + UV illumination treatment exhibited a highly potential for low noise microwave power device applications.