Cloning of a putative high-affinity kainate receptor expressed predominantly in hippocampal CA3 cells.

Kainic acid is a potent neurotoxin for certain neurons. Its neurotoxicity is thought to be mediated by an excitatory amino-acid-gated ion channel (ionotropic receptor) possessing nanomolar affinity for kainate. Here we describe a new member of the rat excitatory amino-acid receptor gene family, KA-1, that has a 30% sequence similarity with the previously characterized alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptor subunits GluR-A to -D. The pharmacological profile of expressed recombinant KA-1 determined in binding experiments with [3H]kainate is different from that of the cloned AMPA receptors and similar to the mammalian high-affinity kainate receptor (kainate greater than quisqualate greater than glutamate much greater than AMPA) with a dissociation constant of about 5 nM for kainate. The selectively high expression of KA-1 messenger RNA in the CA3 region of the hippocampus closely corresponds to autoradiographically located high-affinity kainate binding sites. This correlation, as well as the particular in vivo pattern of neurodegeneration observed on kainate-induced neurotoxicity, suggests that KA-1 participates in receptors mediating the kainate sensitivity of neurons in the central nervous system.     

Bcl-2 maintains B cell memory

The number of lymphocytes in an animal is remarkably constant despite antigen-driven proliferation and a high rate of B-cell lymphopoiesis. This reflects the relatively brief lifespan of many newly generated B cells and argues for a well-regulated death mechanism. Even so, a secondary immune response can be generated years after a primary exposure to antigen. Antigen that might restimulate B cells persists for extended periods on follicular dendritic cells in the light zone of germinal centres. Antigen-binding B cells have also been found months after the end of obvious cell division. The precise signal that enables certain B cells to emerge as long-term surviving memory cells is unknown. Bcl-2, an inner mitochondrial membrane protein, blocks programmed cell death in B cells. We report here that this proto-oncogene maintains immune responsiveness. Transgenic mice overproducing Bcl-2 have a long-term persistence of immunoglobulin-secreting cells and an extended lifetime for memory B cells.     

开关电容网络故障子网络的诊断

本文给出了一种开关电容网络(SCN)的故障子网络诊断算法。该算法建立在电荷守恒原理基础上。应用本算法,能识别出故障子网络或确定出包含故障子网络的局部网络。本文的算法是一种直接算法,具有可靠、计算量小、适用于大规模SCN等特点。而且,该算法不限于双时相SCN,可推广到多时相SCN。     

Chetaev型实用不稳定性判据

利用 Ｖ函数方法研究非线性系统的实用不稳定性。根据Ｃｈｅｔａｅｖ不稳定性定理的基本思想,结合对过初始状态集合边界特解的性态分析,建立了一般形式的实用不稳定性直接判据。此结果能够有效地用于分析非线性系统的实用不稳定性,避免了因使用比较方法使所得条件过强和不便于实际检验的困难,并举例说明所得结果。     

Synthesis of ochratoxins TA and TC,analogs of ochratoxins A and C

Zusammenfassung Zwei Ochratoxinanaloge, Ochratoxin T_A (OT_A) und T_C (OT_C) wurden aus Ochratoxin- chemisch synthetisiert indem Phenylalanin und sein Äthylester im Molekül durch Tyrosin und Tyrosinäthylester substituiert wurden. Der Hühnerembryonentest ergab, dass OT_C etwas toxischer und OT_A etwas weniger toxisch ist als Ochratoxin A (OA).     

Chiral supramolecular gold-cysteine nanoparticles: Chiroptical and nonlinear optical properties

Cysteine is a sulfur-containing amino acid that easily coordinates to soft metal ions and grafts to noble metal surfaces. We report a simple synthetic approach for the production of chiral gold-cysteine polymeric nanoparticles soluble in water. Conjugation of cysteine with gold in a polymeric way, leading to ~50 nm diameter nanoparticles, resulted in the generation of new characteristic circular dichroism (CD) signals in the region of 250–400 nm, whereas no CD signal changes were found with cysteine alone. We also investigate their nonlinear optical properties after two-photon absorption. Two-photon emission spectra and first hyper-polarizabilities, as obtained by the hyper-Rayleigh scattering technique, of these particles are presented.     

Au plasmon enhanced high performance β-Ga_2O_3 solar-blind photo-detector

Surface plasmon polariton(SPP) is electro-magnetic wave coupled to free electron oscillations near the surface of metal, and has been used to improve the photoelectric properties in many optoelectronic devices. In the present study, the Au nanoparticles(NPs)/β-Ga_2O_3 composite thin film was fabricated through depositing Au ultra-thin film on the β-Ga_2O_3 thin film followed by post-thermal treatment. Compared to bare β-Ga_2O_3 thin film, a significant absorption around 510 nm, which is attributed to SPP of Au NPs, was observed in the UV–vis spectrum of Au NPs/β-Ga_2O_3 composite thin film. The results showed that the photoresponse of Au NPs/Ga_2O_3 photodetector illuminated under 254 nm +532 nm light was much higher than that illuminated under 254 nm light, indicating an enhancement of photoelectric property for the solar-blind photodetector based on β-Ga_2O_3 thin film.     

基于多用途车的螺旋齿轮限滑差速器结构设计

对多用途乘用车差速器进行改造,分析了螺旋齿轮限滑差速器的结构及工作原理,并对其结构设计参数进行优化,给出了螺旋齿轮参数化设计中相关参数的初步设计值.研究成果可为多用途乘用车限滑差速器的改进与创新奠定基础,提升螺旋齿轮限滑差速器的工作效率.