Subcellular localization and characterization of G protein-coupled receptor homolog from lymphocystis disease virus isolated in China

G protein-coupled receptors (GPCRs) constitute a large superfamily involved in various types of signal transduction pathways, and play an important role in coordinating the activation and migration of leukocytes to sites of infection and inflammation. Viral GPCRs, on the other hand, can help the virus to escape from host immune surveillance and contribute to viral pathogenesis. Lymphocystis disease virus isolated in China (LCDV-C) contains a putative homolog of cellular GPCRs, LCDV-C GPCR. In this paper, LCDV-C GPCR was cloned, and the subcellular localization and characterization of GPCR protein were investigated in fish cells. LCDV-C GPCR encoded a 325-amino acid peptide, containing a typical seven-transmembrane domain characteristic of the chemokine receptors and a conserved DRY motif that is usually essential for receptor activation. Transient transfection of GPCR-EGFP in fathead minnow (FHM) cells and epithelioma papulosum cyprini (EPC) cells indicated that LCDV-C GPCR was expressed abundantly in both the cytoplasm and nucleoplasm. Transient overexpression of GPCR in these two cells cannot induce obvious apoptosis. FHM cells stably expressing GPCR showed enhanced cell proliferation and significant anchorage-independent growth. The effects of GPCR protein on external apoptotic stimuli were examined. Few apoptotic bodies were observed in cells expressing GPCR treated with actinomycin D (ActD). Quantitative analysis of apoptotic cells indicated that a considerable decrease in the apoptotic fraction of cells expressing GPCR, compared with. the control cells, was detected after exposure to ActD and cycloheximide. These data suggest that LCDV-C GPCR may inhibit apoptosis as part of its potential mechanism in mediating cellular transformation.

20 Gb/s mode-group-division multiplexing employing Hermite-Gaussian launches over worst-case multimode fiber links

For the first time, mode group division multiplexing is achieved in a multimode fiber link using a 2-D Hermite-Gaussian mode launch. 20 Gb/s error-free transmission is achieved over a 250 m worst-case OM1 multimode fiber link. © OSA 2014.

Large g factors of higher-lying excitons detected with reflectance difference spectroscopy in GaAs-based quantum wells

Exciton g factors in GaAs-based quantum wells (QWs) were evaluated by reflectance difference spectroscopy (RDS) under a weak magnetic field. The well-width dependence of the n=1 heavy-hole exciton (1H1E) g factor agrees well with the reported results, demonstrating RDS as a sensitive tool for detection of g factor. By comparison, the n=1 light-hole exciton g factor increases with the well width, and shows a larger value than that of 1H1E. In a 20-nm-wide Al0.02Ga0.98As/AlAs multiple QW sample, the g factors of up to ten excitons are obtained, and the higher-lying exciton g factors are found to be one order larger than that of the 1H1E exciton.

Electron g factors and optical properties of InAs quantum ellipsoids

The electronic structure, electron g factors and optical properties of InAs quantum ellipsoids are investigated, in the framework of the eight-band effective-mass approximation. It is found that the light-hole states come down in comparison with the heavy-hole states when the spheres are elongated, and become the lowest states of the valence band. Circularly polarized emissions under circularly polarized excitations may have opposite polarization factors to the exciting light. For InAs ellipsoids the length, which is smaller than 35 nm, is still in a strongly quantum-confined regime. The electron g factors of InAs spheres decrease with increasing radius, and are nearly 2 when the radius is very small. The quantization of the electron states quenches the orbital angular momentum of the states. Actually, as some of the three dimensions increase, the electron g factors decrease. As more dimensions increase, the g factors decrease more. The dimensions perpendicular to the direction of the magnetic field affect the g factors more than the other dimension. The magnetic field along the z axis of the crystal structure causes linearly polarized emissions in the spheres, which emit unpolarized light in the absence of magnetic field.

H+ISFET-based biosensor for determination of penicillin G

A biosensor based on an H+ ion sensitive field effect transistor (H+-ISFET) and penicillin G acylase has been developed. The response time of the sensor to different concentrations of penicillin G was 30 s. In a 20 mM phosphate buffer at pH 7.0, the linear range of the calibration curve was from 0.5 to 8 mM. The coefficients of variation for three samples with 20 repeated measurements were below 5%. Stability of the sensor could reach about 6 months and more than 1000 runs were performed without a significant decrease of the output value. The sensor was tested for measurement of the penicillin G content in penicillin fermentation broth. Forty samples with low and high concentrations of penicillin G were chosen for the correlation test. The values assayed by the sensor method were compared with the values assayed by HPLC method, the correlation coefficient (r) was 0.9944 and the regression equation was y = 1.034X - 2083.7 respectively. The different measuring methods are discussed in the text. (C) 1998 Published by Elsevier Science S.A. All rights reserved.

氧化物气敏半导体与H_2O(g)、O_2(g)及还原性气体相互作用的研究

本文采用自行设计的均速增加加热电压改变元件温度的方法以及动、静态气敏特性测试方法并借助其它测试手段（X光衍射、BET、扫描电流）系统地研究了表面电导控制型SnO_2系元件和体电导控制型γ-Fe_2O_3元件在变温过程中与H_2O(g)、O_2(g)和还原性气体相互作用的规律。实验结果表明：添加剂Al_2O_3、MgO、Pd、Pt和Sb_2O_3均对元件的体电阴均有调制作用。Al_2O_3是以微粒状存在于元件内，它为元件提供了活化中心，提高了元件的灵敏度。而γ-Fe_2O_3具有超微细结构。SnO_2系元件和γ-FeO_3元件取样电压(V_L)与温度（T）的变化关系在空气和惰性气氛中均是非线性的。材料组份不同的元件，其V_L～T变化规律不同。各元件在空气和惰性气氛中的变化，除阻值不同外，其V_L～T变化规律基本相同。综合考虑添加剂(Al_2O_3、MgO)和气氛（空气、惰性气氛、纯氧气）的影响，SnO_2系元件的V_L～T变化规律不仅是由于氧在元件表面上的吸附及吸附状态的不同所引起，很大程度上取决于元件材料的组成和温度对材料内载流子浓度和逐移率的影响。基于对SnO_2系元件的V_L～T变化规律的分析，γ-Fe_2O_3元件V_L随温度的变化也是由于环境中的氧和材料内载流子迁移率随温度的变化所致。SnO_2系元件和γ-Fe_2O_3元件在不同温度所测的V_L～T变化关系表明：SnO_2元件在低温(<72%RH)条件下，具有与干燥空气中相同的V_L～T变化关系；在高温度(>72%RH)的空气中，H_2O(g)的存在对元件低温区(<100 ℃) (200 ℃-400 ℃)的V_L值均有影响，在低温区的V_L值较干燥空气中的V_L值高；中温区的V_L值较干燥空气中的V_L值低。把在约98%RH的空气和氩气中的V_L～T变化曲线比较表明：中温区的实验现象是由于空气中H_2O(g)与O_2(g)共存所致。γ-Fe_2O_3元件在不同温气气氛中的V_L～T变化规律相同，且在元件工作温度（129 ℃～320 ℃）范围内V_L值相同，但均较干燥空气中该条件下的V_L值高。在实验中亦观察到SnO_2元件在温度低于72%RH中长期放置亦可观察到与实验中温度>72%RH条件下相同的V_L～T变化。SnO_2元件在空气和惰性气氛中对还原性气体均有气敏性。而且在惰性气氛中对微量还原性气体（H_2）的灵敏度比在空气中的灵敏度高。掺贵金属Pd或Pt的SnO_2元件在惰性气氛中，当H_2浓度高于8000ppm时，元件电导突变式增加。我们认为SnO_2系元件在空气中检测还原性气体的工作机理是表面化学反应过程；在惰性气氛中其工作机理是表面解离吸附过程。γ-Fe_2O_3元件在空气中对C_4H_(10)具有较高的选择性。但在惰性气氛中对还原性气体不具有气敏性。我们认为环境中氧是体电导控制型气敏元件气敏性不可缺少的中间媒介。其检测机理是微观可逆氧化-还原过程。

维生素C二步发酵新组合菌G.529及其应用

本文筛选一株苏芸金杆菌与氧化葡萄糖酸杆菌组成的新组合菌G. B529，并对其生物学性质进行研究，结果表明：新组合菌的摇瓶发酵转化率较原菌系提高4.83个百分点，发酵速度快，且具有耐受高浓度（10%）山梨糖的特性。为使G. B529的潜能得到最大程度的发挥，对其影响因素进行研究。首先应用均匀设计方法确立了G. B529的发酵培养基优化配比，在所实验的范围内，发酵转化率与玉米浆浓度成正相关性，尿素浓度 1．45%佩W/V)时，转化率达最大。其次种液各参数对发酵影响实验确立了判断种子质量高低的方法。结果显示种液中的大菌OD值一1.6 X小菌OD值可以作为种液的质量指数。最后对种子质量的影响实验显示适当提高玉米浆、葡萄糖等成分的浓度与降低尿素的浓度及调高pH值均有利于种液质量的改善。同时低接种量、大通气量和选择种龄为14小时均有助于种液质量指数的提高。 新组合菌系在选定的条件下枷3罐中4批发酵显示出很强的发酵能力，平均醇酸转化率较对照提高8.16个百分点，周期缩短10.6小时。其在300M3罐中生产试用行，连续26批次的平均醇酸转化率达87.40%,较生产用菌提高3.32个百分点。平均周期也缩短1．3小时。

有关中国细齿缺萼苔(Gymnomitrioncrenulatum)和中华缺萼苔(G.sinense)资料

细齿缺萼苔 (G .crenulatumGott.exCarr.)的中国记录为错误鉴定 ,标本实为中华缺萼苔(G .sinenseK .Muell.) ,应被移出中国苔藓植物区系。研究发现了多号西藏产中华缺萼苔标本 ,将中华缺萼苔其在中国的分布范围从云南的模式产地扩展到了西藏。对中华缺萼苔进行了形态特征描述和分布分析 ,并提供了特征示意图

温度对Ti_(45)Zr_(35)Ni_(20)合金电化学贮氢性能的影响

采用真空熔炼法制备了Ti45Zr35Ni20合金,研究了合金在不同温度下的电化学贮氢性能。结果表明,Ti45Zr35-Ni20电极的电化学性能随着温度而变化,温度从323 K升高到343 K时,电极的活化次数从22次减少到8次,放电容量从86.1 mAh/g增到135.0 mAh/g,快速放电能力也有所提高,然而,高温使电极的循环稳定性显著下降,自放电率增大。

Crystallographic and electrochemical properties of ball-milled quasicrystalline Ti45Zr35Ni17Cu3 alloy with 20 mass% Ni

Icosahedral quasicrystalline Ti45Zr35Ni17Cu3 alloy powder was ball-milled with 20 mass% Ni, and the effect of the ball-milling time (t) on crystallographic and electrochemical characteristics were investigated. The amounts of icosahedral quasicrystalline and Ni phases decreased when ball-milling time increased from 30 to 180 min. The powder consisted of amorphous and (Ni and Ti) phases after 360 min of ball-milling. The maximum discharge capacity of the powder electrodes first increased from 89 (t = 0 min) to 192 mAh g(-1) (t = 180 min), and then decreased to 138 mAh g(-1) (t = 360 min). The high-rate dischargeability and the discharge capacity after 15 cycles increased with increasing ball-milling time.

Temperature dependence of the distribution of the first passage time: Results from discontinuous molecular dynamics simulations of an all-atom model of the second beta-hairpin fragment of protein G

More than 22 000 folding kinetic simulations were performed to study the temperature dependence of the distribution of first passage time (FPT) for the folding of an all-atom Go-like model of the second beta-hairpin fragment of protein G. We find that the mean FPT (MFPT) for folding has a U (or V)-shaped dependence on the temperature with a minimum at a characteristic optimal folding temperature T-opt*. The optimal folding temperature T-opt* is located between the thermodynamic folding transition temperature and the solidification temperature based on the Lindemann criterion for the solid. Both the T-opt* and the MFPT decrease when the energy bias gap against nonnative contacts increases. The high-order moments are nearly constant when the temperature is higher than T-opt* and start to diverge when the temperature is lower than T-opt*. The distribution of FPT is close to a log-normal-like distribution at T* greater than or equal to T-opt*. At even lower temperatures, the distribution starts to develop long power-law-like tails, indicating the non-self-averaging intermittent behavior of the folding dynamics. It is demonstrated that the distribution of FPT can also be calculated reliably from the derivative of the fraction not folded (or fraction folded), a measurable quantity by routine ensemble-averaged experimental techniques at dilute protein concentrations.

Morphology, thermal behavior, and mechanical properties of PA6/UHMWPE blends with HDPE-g-MAH as a compatibilizing agent

A functionalized high-density polyethylene (HDPE) with maleic anhydride (MAH) was prepared using a reactive extruding method. This copolymer was used as a compatibilizer of blends of polyamide 6 (PA6) and ultrahigh molecular weight polyethylene (UHMWPE). Morphologies were examined by a scanning electron microscope. It was found that the dimension of UHMWPE and HDPE domains in the PA6 matrix decreased dramatically, compared with that of the uncompatibilized blending system. The size of the UHMWPE domains was reduced from 35 mu m (PA6/UHMWPE, 80/20) to less than 4 mu m (PA6/UHMWPE/HDPE-g-MAH, 80/20/20). The tensile strength and Izod impact strength of PA6/UHMWPE/HDPE-g-MAH (80/20/20) were 1.5 and 1.6 times as high as those of PA6/UHMWPE: (80/20), respectively. This behavior could be attributed to chemical reactions between the anhydride groups of HDPE-g-MAH and the terminal amino groups of PA6 in PA6/UHMWPE/HDPE-g-MAH blends. Thermal analysis was performed to confirm that the above chemical reactions took place during the blending process. (C) 2000 John Wiley & Sons, Inc.

Morphologies and physical properties of PA1010/HIPS/HIPS-g-MA ternary blends

The effect of the content of a copolymer consisting of high impact polystyrene grafted with maleic anhydride (HIPS-g-MA) on morphological and mechanical properties of PA1010/HIPS blends has been studied. Blend morphologies were controlled by adding HIPS-g-MA during melt processing, thus the dispersion of the HIPS phase and interfacial adhesion between the domains and matrices in these blends were changed obviously. The weight fractions of HIPS-g-MA in the blends increased from 2.5 to 20, then much finer dispersions of discrete HIPS phase with average domain sizes decreased from 6.1 to 0.1 mu m were obtained. It was found that a compatibilizer, a graft copolymer of HIPS-g-MA and PA1010 was synthesized in situ during the melt mixing of the blends. The mechanical properties of compatibilized blends were obviously better than those of uncompatibilized PA1010/HIPS blends. These behaviors could be attributed to the chemical interactions between the two components of PA1010 and HIPS-g-MA and good dispersion in PA1010/HIPS/HIPS-g-MA blends. Evidence of reactions in the blends was seen in the morphology and mechanical behaviour of the solid. The blend containing 5 wt % HIPS-g-MA component exhibited outstanding toughness. (C) 1999 Kluwer Academic Publishers.

Effects of the compatibilizer PP-g-GMA on morphology and mechanical properties of PP/PC blends

Effects of the compatibilizer polypropylene grafted with glycidyl methacrylate(PP-g-GMA) on the morphology, thermal, rheological and mechanical properties of polypropylene and polycarbonate blends (PP/PC) were studied. It was found that the addition of PP-g-GMA significantly changed their morphology. The mean size of domains reduced from 20 mu m to less than 5 mu m. The dispersed domain size is also strongly dependent upon the content of PP-g-GMA. The interfacial tension of PP/PC/PP-g-GMA (50/30/20) is only about one-tenth of PP/PC (70/30). The crystallization temperature of PP in PP/PC/PP-g-GMA is 5-8 degrees C higher than that of PP in PP/PC blends. Characterization studies based on mechanical properties, differential scanning calorimetry, rheology and morphological evidence obtained by using scanning electron microscopy support the hypothesis that an in-situ copolymer PP-g-PC was formed during the blending process. (C) 1997 Elsevier Science Ltd.

STUDIES ON OLEFIN-COORDINATING TRANSITION-METAL CARBENE COMPLEXES .20. SYNTHESIS OF 1,3-CYCLOHEXADIENE(DICARBONYL) [ETHOXY(ARYL)-CARBENE]IRON COMPLEXES AND THEIR PHOSPHINE ADDUCTS - CRYSTAL-STRUCTURE OF C6H8(CO)2FEC(OC2H5)C6H4CH3-O

Reaction of 1,3-cyclohexadiene(tricarbonyl)iron (1) with ortho-substituted aryllithium reagents ArLi (Ar=o-CH3C6H4, o-CH3OC6H4, o-CF3C6H4) in ether at low temperature, and subsequent alkylation of the acylmetalates formed with Et3OBF4 in aqueous solution at 0-degrees-C or in CH2Cl2 at -60-degrees-C gave the 1,3-cyclohexadiene(dicarbonyl)[ethoxy(aryl)carbene]iron complexes (eta4-C6H8)(CO)2FeC(OC2H5)Ar (3, Ar = o-CH3C6H4; 4, Ar = o-CH3OC6H4), and the isomerized product (eta3-C6H8)(CO)2FeC(OC2H5)C6H4CF3-o (5), respectively, among which the structure of 3 has been established by an X-ray diffraction study. Complex 3 is monoclinic, space group P2(1) with a = 8.118(4), b = 7.367(4), c = 14.002(6) angstrom, beta = 104.09(3)-degrees, V = 812.2(6) angstrom3, Z = 2, D(c) = 1.39 g cm-3, R = 0.056, and R(w) = 0.062 for 976 observed reflections. Complexes 3 and 5 were converted into the chelated allyliron phosphine adducts(eta3-C6H8)(CO)2(PR31)FeC(OC2H5)Ar (6, Ar = o-CH3C6H4, R1 = Ph; 7, Ar = o-CH3C6H4, R1 = OPh; 9, Ar = o-CF3C6H4, R1 = Ph), by reaction with phosphines in petroleum ether at low temperatures.