竹叶青蛇毒L一氨基酸氧化酶的纯化、诱导细胞凋亡和抗菌作用

经过分子筛层析和离子交换层析，我们从竹叶青(n妇删l黜3蚴堍g矾)蛇毒中纯化得到了竹叶青蛇毒L 氨基酸氧化酶(聊．L旧)。实验表明，7IsV．LAO是一种糖蛋白，其分子由非共价连接的两个相同的亚基组成， SDS-聚丙烯酰氨凝胶电泳一个亚基的表观分子量为58 kDa。俗v．LA0酶比活力为1100 U／IIlg，其分子脱掉糖基 化成分后不影响酶活力。聊．LA0在浓度为1．0隅／ⅡlL以上时可以诱导C8166细胞凋亡。7rsv．uLo对实验病原 微生物具有选择性抗生作用并具有明显的量效关系，对白色念珠菌(A-I℃c2002)、金黄色葡萄球菌(A，I℃c2592)和 短小芽孢杆菌(cMccBll207)的最小抑菌浓度分别是0．3，O．4和1．0∥nlL，即使在最高实验浓度10彬rIlL，’Isv- LA0对其它实验菌株也未显示抑菌作用。

稀土锰氧化物和双钙钛矿氧化物的合成及电磁性能研究

本文对钙钛矿锰氧化物La0.67Sr0.33MnO3、La0.67Sr0.33Mn1-xFexO3和双钙钛矿氧化物Sr2－xLaxMnMoO6、Sr2－xLaxMnWO6和Sr2(Ni，Co)WO6的结构、磁性和磁电阻效应进行了系统地研究。 利用溶胶-凝胶方法制得La0.67Sr0.33MnO3粉体，通过不同的烧结温度，可以对样品的微观结构进行调控。其中，晶界的状态对自旋电子的输运产生了明显的影响。900℃和1300℃烧结的样品，都出现了远低于居里温度的金属－半导体导电行为转变，表明自旋电子的传输不仅与晶粒的大小有关，而且与晶界状态密切联系。合适的烧结条件，可以得到大的，使用温区较宽的磁电阻效应。 在La0.67Sr0.33Mn1-xFexO3(0≤x≤0.2)体系中，Fe3＋的掺入没有明显改变La0.67Sr0.33MnO3的结构和晶胞参数，但却极大地降低了样品的居里温度。在x≥0.08时同样出现了低于居里温度的金属－半导体导电行为转变，这是由体系的铁磁态磁不均匀性导致的。电子顺磁共振研究表明，La0.67Sr0.33Mn1-xFexO3(0≤x≤0.20)的EPR谱中峰对峰宽（ΔHpp）在Tmin前后两种温区的线宽展宽机制不同。随着掺杂量的增加，在Tmin处的线宽逐渐变宽并且出现低场顺磁信号。x=0.20的样品，低场顺磁信号在380K左右开始衰减，与La0.67Sr0.33MnO3的顺磁信号具有类似的行为。我们利用相分离模型对系列样品的电子顺磁共振信号的变化规律进行了解释。 在Sr2－xLaxMnMoO6 (0≤x≤1)系列样品中，所有的样品都具有双钙钛矿有序结构。磁化强度、居里温度随掺杂量的增加而增大，但都存在磁受挫行为。在5T的外场下磁化强度依然没有饱和，实际测得的磁矩远远小于理论预测的结果。在低掺杂状态下出现分步磁化。La3+的掺入，不仅改变了体系电子能带的状况，而且极大的改变了体系的结构因素，两者竞争的结果，使体系的电磁性能产生了复杂的变化。

Structure and oxygen permeability of a dual-phase membrane

The dual-phase membrane of La0.15Sr0.85Ga0.3Fe0.7O3-delta-Ba0.5Sr0.5Fe0.2Co0.8O3-delta (LSGF-BSCF) was prepared successfully. This membrane was characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe micro-analyzer (EPMA). This membrane has a dense dual-phase structure: LSGF being the dense body of this membrane and BSCF as another phase running along the LSGF body. This structure is favorable for the oxygen permeation through the membrane. The oxygen permeation test shows that the oxygen permeation flux of LSGF-BSCF membrane (Jo(2) = 0.45 ml/min cm(2), at 915 degreesC) is much higher than that of LSGF membrane (Jo(2) = 0.05 ml/min cm(2)). Thickness dependence of oxygen permeation indicates that the oxygen permeation is controlled by the bulk diffusion. Compared to pure BSCF the dual-phase membrane of LSGF-BSCF is stable in reducing atmosphere. (C) 2003 Elsevier B.V. All rights reserved.

Synthesis and photoluminescent properties of silica-coated LaCeF3 : Tb nanocrystals

La0.45Ce0.45F3:Tb (10 mol% Tb) nanoparticles was synthesized via sonochemical method and then coated with silica (SiO2) shells through a microemulsion process, resulting in the formation of core/shell structured LaCeF3:Tb/SiO2 nanoparticles. The obtained core/shell LaCeF3:Tb/SiO2 nanoparticles are spherical and uniform in size (average size about 60 nm), strongly fluorescent, and long fluorescence lifetime (1.87 ms). This kind of nanoparticles was water-soluble, which could be applied in biological labeling and other fields.

Effect of La-Mg-based alloy addition on structure and electrochemical characteristics of Ti0.10Zr0.15V0.35Cr0.10Ni0.30 hydrogen storage alloy

Effect of La-Mg-based alloy (AB(5)) addition on Structure and electrochemical characteristics of Ti0.10Zr0.15V0.35Cr0.10Ni0.30 hydrogen storage alloy has been investigated systematically. XRD shows that the matrix phase structure is not changed after adding AB(5) alloy, however, the amount of the secondary phase increases with increasing AB(5) alloy content. The electrochemical measurements show that the plateau pressure Ti0.10Zr0.15V0.35Cr0.10Ni0.30 + x% La0.85Mg0.25Ni4.5Co0.35Al0.15 (X = 0, 1, 5, 10, 20) hydrogen storage alloys increase with increasing x, and the width of the pressure plateau first increases when x increases from 0 to 5 and then decreases as x increases further, and the maximum discharge capacity changes in the same trend.

微观结构对溶胶-凝胶法合成的La_(0.67)Sr_(0.33)MnO_3电磁性能影响

采用溶胶-凝胶法制备了不同烧结温度的钙钛矿类锰氧化物La0.67Sr0.33MnO3样品。实验结果表明,在1573 K以上烧结的样品,晶粒出现异常长大,晶界效应明显。随着烧结温度的提高,磁化强度逐渐增大,但样品的居里温度基本不变。此外,在1173和1573 K温度下烧结的样品,均出现了低于居里温度的金属-半导体导电行为转变。在合适的烧结条件下,可以观察到隧道磁电阻(TMR)和超大磁电阻(CMR)2种磁电阻效应。实验表明,自旋电子的输运,不仅与样品平均粒径的大小和密度有关,而且与晶界的微观结构有密切关系。

Crystal structure and electrochemical properties of rare earth non-stoichiometric AB(5)-type alloy as negative electrode material in Ni-MH battery

The La0.85MgxNi4.5Co0.35Al0.15 (0.05less than or equal toxless than or equal to0.35) system compounds have been prepared by are melting method under Ar atmosphere. X-ray diffraction (XRD) analysis reveals that the as-prepared alloys have different lattice parameters and cell volumes. The electrochemical properties of these alloys have been studied through the charge-discharge recycle testing at different temperatures and discharge currents. It is found that the La0.85Mg0.25Ni4.5Co0.35Al0.(15) alloy electrode is capable of performing high-rate discharge. Moreover, it has very excellent electrochemical properties as negative electrode materials in Ni-MH battery at low temperature, even at -40degreesC.

Systematic synthesis and characterization of single-crystal lanthanide phenylphosphonate nanorods

Using low-temperature hydrothermal methods, nanoscale lanthanide phenylphosphonates species with different morphologies, namely, nanoparticles and nanorods, have been systematically synthesized. The possible growth mechanism of these nanorods was discussed. X-ray diffraction, transmission electron microscopy, electron diffraction, and photoluminescence spectra were used to characterize these materials. The photoluminescent properties of EU(O3PC6H5)(HO3PC6H5) and La0.91EU0.09(O3PC6H5)(HO3PC6H5) nanorods were discussed.

Structures and electrochemical characteristics of several kinds of alloys

The structures and the electrochemical characteristics of La0.7-xCexMg0.3Ni2.8Co0.5 (x = 0.1-0.5) alloy, Ti0.25-xZrxV0.35Cr0.1Ni0.3 (x = 0.05-0.15) alloy and AB(3

Synthesis, structure and ionic conductivity of La2/3-xLi3xMoO4

A series of compounds, La2/3 - xLi3xMoO4, were first prepared. Their structures are tetragonal scheelites with the cationic defects. The cell parameters a, c and values of c/a decrease with the increasing of the substitution amount (3x) of lithium ion. Cationic vacancies are getting more as Li+ concentration is lower. The diffusion of lithium ion is predominant. The concentration of charge carriers increases with increasing the substitution amount (3x) of lithium ion, meanwhile, the concentration of cationic vacancies decreases. The conductivity approaches the best when the substitution amount (3x) of lithium ion is about 0.3. The conductivity of La0.567Li0.3MoO4 is 6.5 x 10(-6) S . cm(-1) at room temperature.

La_(1-x)Pr_xP_5O_(14) 晶体的光谱性质

分析了室温下晶体在紫外、可见区的吸收、荧光和红外光谱,利用Judd Ofeld理论计算了PrPP和La0.2Pr0.8PP晶体中Pr3+的实验振子强度,PrPP和La0.2Pr0.8PP晶体中Pr3+离子振子强度变化不大,说明在该晶体中Pr3+的浓度猝灭效应较小。红外光谱和结构分析确定了晶体的结构为单斜晶系,并观察到Pr3+的3P0 3H6跃迁的红色发射很强。

La(1-x)Pr_xP_5O_(14)晶体的研究

用水热法研究了La12xPr xP5O14(LaPrPP)(0 < x < 1,原子百分含量)晶体的生长,测定了La0.2Pr0.8PP晶体结构为 单斜晶系,空间群为P21/c。晶体的密度为3.27g/cm3,分解温度为915℃。分析了室温下晶体在紫外、可见区的吸 收、荧光和红外光谱,利用Judd2Ofeld 理论计算了PrPP 和La0. 2Pr0. 8PP 晶体中Pr3 + 的实验振子强度,得到一些规律性结果,观察到Pr3 + 的3 P0 —3 H6 跃迁的红色发射很强。

Catalytic combustion of CH4 and CO on La1-xMxMnO3 perovskites

The activities of perovskites depend on compositions and preparation methods. Various perovskites, La1-xMxMnO3 (M=Ag, Sr, Ce, La), have been prepared by two different methods (co-precipitation and spray decomposition). The new preparation method, spray decomposition, produced perovskites of a high surface area of over 10 m(2)/g. The catalytic activities for CH4 and CO oxidation have been studied on a series of catalysts, La1-xMxMnO3. The perovskite-type oxide, La0.7Ag0.3MnO3, shows the highest catalytic activity: the complete conversion of CO and CH4 at 370 and 825 K, respectively. (C) 1999 Elsevier Science B.V. All rights reserved.

Ni系ABO_3和A_2BO_4型复合氧化物的固态物化性质与NO+CO反应的催化性能

合成了具有钙钛石ABO3结构的LaNiO3和La0.1Sr0.9NiO3及具有类钙钛石A2BO4结构的La2NiO4和LaSrNiO4等四个Ni系复合氧化物催化剂．研究了该系列复合氧化物的晶体结构，缺陷结构，B位Ni离子的价态，氧化还原性能及对NO分子的吸附性能等固态物化性质．考察了它们对NO＋CO反应的催化性能，并与NO直接分解进行了对比研究．探讨了结构因素对Ni系复合氧化物催化剂的固态物化性质及催化性能的影响．提出了NO＋CO反应的反应机理