钙钛石型复合氧化物La_xSr_(1-x)M_yM'_(1-y)O_3(M, M' = Mn, Fe, Co)的固体物理化学性质和催化性能的研究

钙钛石型复合氧化物由于具有许多独特的物理化学性质，如多种类型的磁性和导电性、对多种物理和化学因素的敏感性、高温下的稳定性和结构的明确易调性等长期以来一直受到固体物理、固体化学和催化科技工作者重视，本文第一部分详细总结了文献中有关这类氧化物的结构、电子状态、电磁性质、表面吸附性能、稳定性以及反应机理和催化性能等方面的重要结果。第二部分为催化剂的制备和表征方法。第三部分针对文献中研究较少的B位取代钙钛石型氧化物，系统研究了系列化合物LaM_yM'_(1-y)O_a (M, M' = Mn, Fe, Co)的固体物理化学性质和对NH3和CO���化反应的催化性能，讨论了它们之间的关系。1. 催化剂的制备、晶体结构与光谱性质。2. LaM_yM'_(1-y)O_3(M、M' = Mn、Fe、Co)r的氧化还原性质和稳定性。3. 过渡金属离子的状态及其之间的相互作用。4. 催化剂中氧的形态。5. 氨氧化性能与固体物化性质之间的关系。6. 一氧化碳氧化与固体物化性质之间的关系。

高聚物辐射交联与裂解

本文从两个侧面研究了高聚物辐射交联与裂解反应。辐照高聚物分子量分布（MWD���的表征与研究。辐照高聚物MWD���研究对于辐射交联的理论与应用均有一定的意义。但由于长链支化的存在，实验准确测定MWD���困难。本文旨在运用SEC－LALLS技术来解决这一问题。为此，我们首先分析了长链支化存在下，SEC柱扩展效应对测定数据的影响，导出了一基本议程组。{c(t) = ∫g(t,τ) Co(τ)d�� (1) s(t) = ∫g(t,τ) So(τ) d�� τ = f(j)式中，t和τ均为流出时间，J为聚合物分子流体力学体积。g(t,τ)为柱扩展函数，f为标准校正函数，c(t)、s(t)分别为浓度和光散射响应函数，为可测量。Co(τ)、So(τ)分别为样品流体力学体积为f~(-1)(τ)的那部分分子的浓度及浓度与重均分子量的积。当样品为线型聚合物时，它就转化为相应的Tung和Yau方程。围绕（1）的解，我们分别利用最小二乘法拟合σ~2-T关系和Wiener滤波法解扩展方程，并用计算机模拟，检验了这些数值运算的可靠性。同时，还讨论了扩展效应、改正参数实验误差对测定结果的影响，为实际测定提供了依据。在此基础上，建议了以SEC－LALLS联用技术为核心的表征辐 照高聚物MWD���系统化方法。最后我们运用此方法初步研究了聚苯乙烯（PS）辐照后凝胶点前后溶胶性质的变化。从MWD���变化，证实反应初期参与交联反应的主要是较高分子量部分分子。低分子量分布的浓度在凝胶点前变化不大，而在凝胶点附近及以后变化较大，支化分布的变化证明这是由于小分子量部分被支化分子掩盖了的缘故。由平均分子量测点。我们观察到了凝胶点附近重均分子量变化急剧而数均分子量缓和这一现象，并求出反应G值。数学期望法在多分体系非线性交联反应中的应用。鉴于共混高聚物辐射交联技术的发展，本文运用数学期望法，系统地考虑了一类内涵很广的多组分体系的非线性交联反应。对于重均分子量及凝胶化条件，我们把它们归结为简单的矩阵运算各矩阵元的物理意义清晰、明确、可直接写出，这为不熟悉高分子反统计理论的工作者提供了方便。对于溶胶分数，我们给出了－非线性方程组，并就r元共混体系中，当初始分布皆为Flory分布时，给出了裂解和交联同时发生时的近似结果。特别地我们针对二元共混体系在实际应用中的广泛性，我们讨论了相结构，共混比的影响。最后，结合PDMS／EVA共混体系辐射交联的研究，提出了较为一般的共混体系溶胶分数分析方法。为了考察我们的方法的可靠性，文中我们还讨论了几个小分子参与的非线性交联反应体系，并与其它理论结果，作了对照，表明该方法的可靠性和直观性皆优于某些经典理论方法。

Theoretical study of p-d hybridization in Co perovskite

The real-space recursion method and unrestricted Hartree-Fock approximation have been applied to calculate the density of states of various Co perovskite, CeCoO3, SrCoO3 and Sr1-xCexCoO3. We have studied the magnetically ordered states of these Co perovskites in an enlarged double cell, and find its various magnetic structures due to the occupancy of 3d band and its interaction with neighboring Co ions. In this study, we have studied the p-d hybridization of the three Co perovskites, we find t(2g) electrons are localized and the flat e(g) band is responsible for the itinerant behavior, and although the rare earth elements itself contribute little to the DOS at the Fermi energy, the DOS at Fermi energy and the magnetic moment changed consequently because of different valence of Co ions in these compounds and p-d hybridization effect is very important. (C) 2009 Elsevier B.V. All rights reserved.

Strong visible up-conversion emission in Tb3+, Tm3+ and Tb3+-Tm3+ co-doped tellurite glasses sensitized by Yb3+

Up-conversion luminescence characteristics under 975 nm excitation have been investigated with Tb3+/Tm3+/Yb3+ triply doped tellurite glasses. Here, green (547 nm: D-5(4) --> F-7(4)) and red (660 nm: D-5(4) --> F-7(2)) up-conversion (UC) luminescence originating from Tb3+ is observed strongly, because of the quadratic dependences of emission intensities on the excitation power. Especially, the UC luminescence was intensified violently with the energy transfer from the Tm3+ ions involves in the Tb3+ excitation. To the Tb3+/Tm3+/Yb3+ triply doped glass system, a novel up-conversion mechanism is proposed as follows: the energy of (3)G(4) level (Tm3+) was transferred to D-5(4) (Tb3+) and the 477-nm UC luminescence of Tm3+ was nearly quenched. (C) 2006 Elsevier B.V. All rights reserved.

Ridge optical waveguide in an Er3+/Yb3+ co-doped phosphate glass produced by He+ ion implantation combined with Ar+ ion beam etching

This paper reports on the fabrication and characterization of a ridge optical waveguide in an Er3+/Yb3+ co-doped phosphate glass. The He+ ion implantation (at energy of 2.8 MeV) is first applied onto the sample to produce a planar waveguide substrate, and then Ar+ ion beam etching (at energy of 500 eV) is carried out to construct rib stripes on the sample surface that has been deposited by a specially designed photoresist mask. According to a reconstructed refractive index profile of the waveguide cross section, the modal distribution of the waveguide is simulated by applying a computer code based on the beam propagation method, which shows reasonable agreement with the experimentally observed waveguide mode by using the end-face coupling method. Simulation of the incident He ions at 2.8 MeV penetrating into the Er3+/Yb3+ co-doped phosphate glass substrate is also performed to provide helpful information on waveguide formation.

合成甲醇铜系催化剂硫中毒机理与该催化剂上CO���H_2吸附机理的研究

合成甲醇铜系催化剂是广泛用于工业反应的高活性催化剂。但对含硫气体十分敏感，易硫中毒。本论文通过常压、220 ℃反应温度下硫中毒对催化活性、反应物吸附性质、催化剂表面组成与体相结构、孔分布的影响探讨了铜系催化剂硫中毒机理。同时通过考察CO���H_2在米中毒铜系催化剂上咐附、脱附、程脱及竞争吸附的性质，探讨了CO���H_2吸附机理。得到以下结果。常压下，铜系催化剂遇含硫气体引起不可逆中毒。当硫浓度较低时，H_2S占据了铜活性中心，使CO���能在该吸附中心吸附，造成失活。由于H_2S吸附引起催化剂表面铜晶相冲长也是失活的直接原因。中毒时，硫并非均匀吸附，而主要是吸附在50～80A孔内。H_2S浓度较高时，硫与催化剂反应形成硫化物是失活的主要原因。H_2在铜系催化剂上的吸附当吸附温度为225 ℃时可分为两部分，可逆吸附与不可逆吸附。可逆吸附中心属铜吸附中心，不可逆吸附中心是H_2与部分吸附的CO���同的竞争的咐附中心。CO���该温度下的可逆吸附发生在催化剂铜活性表面上。

Co(salen)作为辅酶B_(12)模型物及化学修饰电极的电化学研究

本论文从合成Co(salen)开始，对Co(salen)在电化学现场合成辅酶B_(12)模型物的工作进行了尝试。进一步地，用Co(salen)制作了两种化学修饰电极，并对它们的性质进行了较为详细的考察。同时还将这两种修饰电极应用于电催化研究工作，得到了较为满意的结果。

湖南尖吻蝮(D. acutus)蛇毒出血毒素的纯化、性质和溶液构象研究

通过Sephadex G-75凝胶过滤，QAE-Sephadex A-50和CM_Sephadex C-25离子交换的步骤，我们从湖南产尖吻蝮(Dienagkistrodon acutus)蛇毒中纯化出两个出血毒素，分别称之为DaHT-1和DaHT-2。在聚丙烯酰胺凝胶电泳(PAGE)和SDS-聚丙烯酰胺凝胶电泳中均呈单一蛋白带，显示两个出血毒素皆为电泳纯。DaHT-1和DaHT-2的分子量相同，都为23,500道尔顿，具有相似的氨基酸组成，其中酸性氨基酸(Asx和GLx)分别占23%和24%。经等电聚焦(IEF)测得它们的等电点分别为5.6和5.2。两个出血毒素具有较强的出血活性(MHD���别为0.5和0.8μg)，都具蛋白水解酶活力，无精氨酸水解酶和PLA~2活性，但蛋白水解酶活性与出血活性并非正相关。DaHT-1，DaHT-2的最适温度分别为35 ℃，40 ℃；最适pH为6-9。对热不稳定，温度变高于60 ℃，活性完全丧失。在中性和碱性条件下稳定，在酸性条件下不稳定，pH<3，出血活性丧失。EDTA完全抑制，半胱氨酸部分抑制它们的出血活性，表明两个出血毒素都是依赖金属离子的蛋白酶，且二硫键对其活性是必需的。金属离子的分析表明每摩尔毒蛋白大约含0.5摩尔的Zn，1摩尔的Ca，较多的Na，K。Mg，不含Co���两者是糖蛋白，含糖总量分别为11%和7%。用远紫外CD���探讨DaHT-1和DaHT-2的溶液构象所得DaHT-1的α-螺旋，β-折叠和无规卷曲分别为36.9%，27.6%和31.4%；DaHT-2的α-螺旋，β-折迭和无规卷曲分别为23.4%，37.3%和45.3%。随着pH的增大或减少，DaHT-1和DaHT-2的峰位蓝移，在酸性条件下的变化比在碱性条件下大，计算表明：α-螺旋减少，无规卷曲增多，β-折迭基本未变。温度的影响和pH相似，50 ℃时峰位蓝移，α-螺旋减少，无规卷曲增多。EDTA对其影响很大，0.02M EDTA便导致两个出血毒素呈极度的无序状态。

Room-Temperature Ferromagnetism in Co-Doped In2O3 Nanocrystals

Co-doped In2O3 nanocrystals showing room-temperature ferromagnetism have been successfully prepared by a simple sol-gel synthesis route. The sample displays it clear ferromagnetism behavior above 300 K. Phase and structure analyses reveal that the nanocrystals are crystallized with Co ions substituted for In ions in the In2O3 matrix, and no trace of secondary phases or clusters is detected. The experimental results are explained theoretically by first-principles calculations based on density functional theory, which indicate that the native ferromagnetic behavior of Co-doped In2O3 could be mainly ascribed to the strong d-d coupling of the magnetic ions.

Late cenozoic chemical weathering and environmental changes recorded in the Co Ngoin sediments, central Qinghai-Tibet Plateau

IEECAS SKLLQG

重离子~(12)C对~(60)Co��射线诱发人染色体畸变效应的比较研究

目的　重离子和高剂量率6 0 Co��射线照射离体人血建立染色体畸变的剂量 效应曲线 ;比较重离子1 2 C照射与6 0 Co��射线照射诱发染色体畸变的相对生物效能。方法　重离子1 2 C和6 0 Co��射线照射离体人血 ,吸收剂量率为 3Gy min ,吸收剂量为 1 0～ 8 0Gy。主要记录染色体型畸变的非稳定性畸变 ,对双着丝粒体和着丝粒环做曲线拟合 ,并检验回归系数的显著性和曲线的拟合度。结果　重离子1 2 C和6 0 Co��射线照射离体血诱发的染色体畸变 (双 +环 ) ,在 0～ 8Gy范围内 ,呈良好的剂量 效应关系。1 2 C离子诱发染色体畸变的RBE值是不恒定的 ,它随吸收剂量增加而减少 ,在 0 3～ 8 0Gy范围内 ,RBE值 (D�� Dc)从 2 6 2到 1 0 0 ,平均 1 5 8。结论　1 2 C离子对6 0 Co��射线照射诱发染色体畸变 ,在照射剂量较低时 ,有较高的生物效应。

Synthesis and magnetic characterization of nickel ferrite nanoparticles prepared by co-precipitation route

Magnetic nanoparticles of nickel ferrite (NiFe2O4) have been synthesized by co-precipitation route using stable ferric and nickel salts with sodium hydroxide as the precipitating agent and oleic acid as the surfactant. X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses confirmed the formation of single-phase nickel ferrite nanoparticles in the range 8-28 nm depending upon the annealing temperature of the samples during the synthesis. The size of the particles (d) was observed to be increasing linearly with annealing temperature of the sample while the coercivity with particle size goes through a maximum, peaking at similar to 11 nm and then decreases for larger particles. Typical blocking effects were observed below similar to 225 K for all the prepared samples. The superparamagnetic blocking temperature (T-B) was found to be increasing with increasing particle size that has been attributed to the increased effective anisotropy energy of the nanoparticles. The saturation moment of all the samples was found much below the bulk value of nickel ferrite that has been attributed to the disordered surface spins or dead/inert layer in these nanoparticles. (c) 2008 Elsevier B. V. All rights reserved.

On the propagation rate of the chemical waves observed during the course of CO oxidation on a Ag/Pt(110) composite surface

We have analyzed the propagation rate of the chemical waves observed during the course of CO oxidation on a Ag/Pt(I 10) composite surface that were reported in our previous papers [Surf Interface Anal. 2001, 32, 179; J. Phys. Chem. B 2002, 106, 5645]. In all cases, the propagation rate v can be adequately fitted as v = v(0) + D-0/d, in which v(0) and D-0 are constants, and d is the distance between the reaction front of the chemical wave and the boundary from which the chemical wave originates. We propose that the surface species responsible for the formation of the chemical wave comes from two paths: the adsorption of molecules in the gas phase on the surface and the migration from the adjacent surface with different catalytic activity. v(0) corresponds to the contribution from the surface species due to the adsorption, and D-0/d to that of the surface species that migrates from the adjacent surface. The rate equation clearly suggests that the observed chemical wave results from the coupling between adjacent surfaces with different catalytic activities during the course of heterogeneous catalysis. These results, together with our previous reports, provide a good fundamental understanding of spillover, an important phenomenon in heterogeneous catalysis.