STUDY ON THE FUNCTIONAL SITES OF Mg~(2+) -INDUCED Chl α FLUORESCENCE AND SURFACE CHARGE CHANGES OF THYLAKOID MEMBRANES

Thylakoid polypeptide components, Mg~(2+) -induced Chl a fluorescence at 77K and surface chargechanges were measured to investigate the functional sites of Mg~(2+) in the regulation of energy distri-bution between two photosystems in completely and incompletely developed barley chloroplasts. It wasfound that in contrast to the completely developed chloroplasts, the incompletely developed chloroplastslacked Chl b and did not contain the 23KDa and 25KDa polypeptide components of LHC-PSII. In themeantime, these membranes did nor present Mg~(2+) -induced Cbl a fluorescence and surface charge changesof thylakoids. These results provided strong evidence that the 23KDa and 25KDa polypeptides ofLHC-PSII are the specific acting sites of the cation that induced these two phenomena. It is suggested in this paper that Mg~(2+) -induced change of excitation energy distribution betweentwo photosystems is produced by the mechanism due to electrostatic neutralization of LHC-PSII bythe cation to cause a structural or con     

SrTiO_3单晶的色心与导电类型关系的研究

本文介绍了通过霍耳系数测量确定了半导体SrTiO_3单晶的导电类型。这种SrTiO_3单晶的生长方法与过去文献中所报道过生长方法不同,本实验所用的单晶是从化学配比熔体中,引入定向籽晶缓冷法生长而成的,而不是用Verneuil(火焰法)或助熔剂法。用色心的形成——准F心模型解释实验结果。这一色心是由SrTiO_3单晶生长过程中氧缺位所形成的。还通过XPS谱(x-ray photonelectric spectroscopy)从另一侧面证实了这一准F心缺陷。     

TRANSFER OF THE ATRAZINE-RESISTANT GENE OF BLACK NIGHTSHADE TO SOYBEAN CHLOROPLAST GENOME AND ITS EXPRESSION IN TRANSGENIC PLANTS

The atrazine-resistant psbA gene of black nightshade was transferred to the chloroplast genome of atrazine-susceptible soybean by means of ovary microinjection during the stage of zygote. The identification was carried out by using the methods of spraying the leaves directly with atrazine solution, examining the change of leaf fluorescence kinetics under a brighter light induction, molecular hybridization, etc. The experimental results show that the transgenic soybean plants do have been obtained for the first time.     

布里渊散射研究K_2SnCl_6晶体的弹性常数和声学模软化

本文测量了六卤素金属化合物六氯锡钾室温布里渊散射纵声速和横声速。计算了晶体的弹性常数、折射率、体积压缩系数。并进一步研究了[111]方向声子的纵声速随温度的变化关系,发现当温度从高温降到256K附近,C_(11)+2C_(12)发生突变。利用Pippard关系进行了分析,得出晶体在T=256K附近发生一级相变。这种声学反常行为可以用均匀弹性应变场与软模坐标涨落的非线性耦合来解释。     

STUDIES ON THE BEHAVIOR OF THE INTERNAL VIBRATIONAL MODES IN (NH4)2TexSn1-xCl6 MIXED CRYSTALS

The behavior of the internal lattice vibrational modes in (NH4)2TexSn1-xCl6 mixed crystals has been investigated by Raman scattering. All of the Raman-active [MX6]2- internal modes show two-mode property in the mixed crystals with compositions from x?=?0 to 1, and apart from the sample with x?=?0.5, their energy positions are composition-independent. Space group calculations including site symmetry considerations and frequency fittings describe a good force field model. It has been demonstrated that the composition-independent two-mode behavior may come from the strong clustering effect, rather than from the character of the gap and local modes of impurities in mixed crystals. For the sample with x?=?0.5, the two component elements seem to form a pseudo-periodic lattice structure.     

二极管激光器泵浦的固体激光器

本文简要介绍了二极管激光器泵浦的固体激光器的结构、优越性、研究现状以及发展前景，     

条形GaAs半导体激光器的非线性温度特性

一、前 言 在通常的(AlGa)As条形半导体双异质结激光器的输出功率随注入电流变化的过程中,由于非线性扭曲现象的存在,限制了输出功率的动态范围,带来了使用的局限性。尤其在模拟调制的通讯系统中,对讯号引入畸变,在与光纤的耦合上也造成困难。因此,非线性问题的研究成为重要课题之一。 目前对非线性问题的研究大多在固定温度条件下进行[1-3].对于非线性现象在低温下随温度的变化关系叙述不多.然而对激光器低温特性的研究还是重要的[4].我们在低温的不同温度下对激光器的非线性现象进行了观察。定性作了初步探讨,以便从实验结果进一步了解…     

界面态对半导体太阳能光电极性能的影响

用CVD法在不同表面处理后的n-Si片上生长n-Fe₂O₃,薄膜,构成双层结构半导体光电极,研究界面态对电极性能的影响。由光萤光谱判断在距Fe₂O₃价带顶1.6eV处存在高态密度的界面态,对费密能级起钉扎作用,按这种能带图所作的理论计算与分析,给出光萤光谱的合理解释,并为电容-电压曲线及光电流-电压曲线的实验结果所证实。这种具有高态密度界面态的双层半导体结构,为稳定性良好、光电转换效率高的太阳能光电极提供了有希望的途径。 关键词：     

室温下不同色心浓度SrTiO_3单晶的Raman谱

实验测量了三块不同颜色SrTiO_3单晶的Raman谱。室温下SrTiO_3单晶的Raman效应是二级过程,不同颜色样品的Raman频移相似,只是散射强度有差别。由霍耳效应测量和光电子谱测量得出,样品的色心由氧空位造成,氧空位起施立作用。     

RAMAN SPECTRUM OF SINGLE-CRYSTAL SrTiO_3 WITH VARIANT COLOR CENTRE DENSITY AT ROOM TEMPERATURE

The Raman spectra of the three differently colored single-crystal SrTiO_3 have been measured.Atroom temperature the Raman effect of SrTiO_3 is a second order process.The Raman frequency shiftsof samples with variant color are similar,but the Raman scattering intensities are different.FromHall effect and XPS measurements we can conclude that the color centre of sample is caused by oxygenvacancy.Oxygen vacancy acts as donor in the samples.