Nitrogen-containing carbon nanotubes

Carbon nanotubes containing small amounts of nitrogen are produced by the pyrolysis of aza-aromatics such as pyridine, methylpyrimidine and triazine over cobalt nanoparticles in an Ar atmosphere; good yields of such nanotubes are obtained by carrying out the pyrolysis of a mixture of pyridine and Fe(CO)(5) in flowing Ar + H-2.

Funcionalización y estudio de nanopartículas de magnetita para su aplicación en terapias de hipertermia magnética

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五步蛇蛇毒磷脂酶A_(2)的纯化及部分性质

从五步蛇蛇毒中纯化一种均一的酸性磷脂酶A_(2)。SDS-PAGE测得分子量为15.8KD, 按氨基酸残基计算其分子量为14.352KD, IEF-PAGE测得等电点为5.32。氨基酸组分分析表明磷脂酶A_(2)分子由128个氨基酸残基组成, 富含Asp和Glu, 不含中性糖。PLA_(2)酶活性 的最适温度为45℃, 最适pH为8.5左右, 没有抗胰蛋白酶的活性, 具有一定的热稳定性。K~(+)、Ca~(++)和Na~(+)离子激活, 而Ca~(++)、Sn~(++)、Cu~(++)、Li~(++)、Hg~(++)、Zn~(++)、Fe~(++)和Co~(++)离子可抑制或完全丧失酶活力。图5表2参 10

铝及其形态的分析方法

我在研究生期间所做的论文为铝及其形态的分析方法。为什么要做这项工作呢？许多研究表明：①铝是天然水和土壤中十分重要的pH缓冲剂，②铝能影响土壤中象磷和有机碳这些重要元素的环比，③铝对动物、植物及人体都有害，这些过程都与铝的形成有关，因此弄清铝的形态及测定各种形态的浓度十分有意义。由于铝在水中含量较低，且水中含有其它共存离子，因此围绕铝形态的分析，首先建立了一种抗干扰，高灵敏的方法来测定总铝量及各种形态铝的浓度。利用铬天青s试剂测定铝的方法很多，铝与铬天青s能形成红色的二元配合物，但其灵敏度低，稳定性差。近年来人们大多采用铝－铬天青S－表面活性剂三元体系，提高了灵敏度和选择性。本文研究了铝－铬天青S－溴代＋元烷基吡啶三元显色体系，试验确定了三元显色体系的最佳显色条件。其条件如下：实验结果及选定的条件 影响因素 实验结果 选定条件 显色酸度 pH 5.5～7.5 6.0 1 * 10~(-4)M CAS溶剂用量 0.3～0.5ml 0.4ml 5 * ~(-3)M CPB的用量 0.5～1.5ml 0.9ml此三元体系十分稳定，在常温下，显色液放置40分钟才能基本发色完全，其吸光度在24小时内无变化。实验方法为于50ml容量瓶中，加入铝标准液，然后加0.4ml 1 * 10~(-4)M CAS溶液，0.9ml CPB 5 * 10~(-3)M溶液，加入用盐酸调好的pH≈6的六次甲基四胺缓冲液5ml，用水定容，放置40分钟，于644nm处，1cm比色池，以试剂空白作参电测定吸光度。当铝量为0～5ug/50ml时，有色配合物遵从电尔定律，其线性相关系数为0.9999，表观摩尔吸光系数ε_(644nm) = 1.43 * 10~5 l·mol~(-1)·cm~(-1)。本法做了三十六种共存离子的影响实验，多数常见离子不干扰铝的测定，此法主要用于水中铝的测定，家Gr~(3+), Ln~(3+), Ti~(4+), Sn~(4+), Be~(2+)这些离子对铝离子测定的干扰尽管很大，但它们在水中的含量很低，因此可以不考察其干扰作用，F~-和PO_4~(3-)都易与铝离子形成配合物，但水中F~-，PO_4~(≡)含量很小，一般情况下不干扰铝的测定。本法主要考虑了Cu~(2+), Fe~(3+)对铝测定的干扰，用硫脲掩蔽Cu~(2+), 用抗坏血酸掩蔽Fe~(3+), 得到了满意的结果。应用本法测定实际水样，五次测定结果的相对标准偏差为5％，用标准加入法测得其回收率在92～104％之间。由以上工作可以看出，由于CPB的加入，使得Al-CAS-CPB三元体系的摩尔吸光系数较Al-CAS二元配合物的大3.5 倍，最大吸收波长也产生了较大的红移，因此，有必要进一步探讨一下此三元体系的反应机理。目前，阳离子表面活性剂对显色反应作用机理的研究较多，但尚没取得一致的见解，这些研究结果可以归纳为四个方面，1．拟均相萃取模型，2．电荷胶米模型，3．双区作用模型，4．配位体－配位体相互作用的理论和协同微扰机理。本文以Al-CAS-CPB体系作为代表，通过Al-CAS-CPB三元配合物的结构、吸收光谱的变化和表面能力测定的结果探讨了CPB作用机理。利用电泳和离子交换实验说明了Al-CAS-CPB的配阴离子，利用平衡移动法和直线法测得Al：CAS的配位电为1：2，用等摩尔连续变换法测定Al：CPB的配位电为1：4，因而配合物的组成比Al：CAS：CPB＝1：2：4。最后推出此配合物的可能结构。从CAS、Al-CAS、Al-CAS-CPB的结构出发，研究了配位体之间相互作用对CAS中大共轭π键中π－电子流动难易的影响，成功地解释了Al-CAS-CPB最大吸收波长产生红移的原因。通过对CAS溶液浓度与三元配合物最大吸收波长、吸光度影响的研究，说明CPB有三个作用，一是与Al、CAS反应形成三元配合物，同时提高了Al与CAS的配位电；二能与CASi试剂产生缔合作用；三是能够形成胶米；增大了三元配合物在水中的溶解充，这三种作用相互制约，并与Al、CAS及CPB之间的摩尔比有关。通过对配合物吸光度，表面张力和表面活性剂浓度关系的研究及CMC值前后此三元体系吸光度、表面张力变化的比较，结果表明，单分子和形成胶米的表面活性剂同样具有增敏作用，这与郑用熙提出的双区作用机理相一致。在CMC值前，单分子表面活性剂与Al、CAS形成三元配合物而起增敏作用，在CMC值以后，CPB与Al、CAS形成胶米配合物而产生增敏作用。最后，讨论了三元体系的最大吸收波长与表面活性剂浓度的关系，结果表明，随CPB浓度的增大，三元体系的最大吸收波长发生蓝移。产生蓝移的原因可以从结构化学的角度得到解释，导致最大吸收波长不同的原因是在CMC前后，Al-CAS-CPB三元配合物所处的微环境不同。对稀酸性水体中铝形态的分离分析及低浓度铝的测定已有人进行研究，普遍认为无机单核铝是致毒因子，因此无机单核铝的浓度较其实际浓度对生命物质的意义更为重要。本文基本上采用Dirscoll形态分离法进行测定土壤酸性浸出液中铝的形态，用Al-CAS-CPB三元显色反应测定各部分铝形态和浓度。其各部分铝形态的分离如下：总活性铝（Al_r）：将样品用0.2um微孔滤膜过滤，用1N HCl将样品酸化为pH等于1，持续24小时，用Al-CAS-CPB测得其中铝含量。总单核态铝（Ala）：将样品用0.2um微孔膜过滤，直接用Al-CAS-CPB法测定铝量。稳定单核铝（Alo）：稳定的单核铝和不稳定的单核铝通过阳离子交换树脂分离。稳定单核铝通过阳离子树脂后，不能被树脂交换，用Al-CAS-CPB法可以直接流出液中铝量为Alo。不稳定单核铝(Alb)为Ala-Alo。在铝形态的分离过程中，我们使用了过滤和树脂交换二种分离方法。对此做了较详细的条件实验。研究了pH值对滤液中铝的影响，随pH值升高，滤液中铝量减小，这就说明，pH值升高，可能形成某些不能通过滤膜的形态，另外也可能是由膜吸附引起的。本文还比较了用静态平衡法和动态法阳离子交换分离稳定单核铝和不稳定单核铝，指出静态平衡法受到溶液pH值的制约，平衡所需时间过长，容易引起溶液中铝形态的变化和沾污，而动态法则能克服这些缺点，因此在实验中采用动态法。把形态分离的方法应用到土壤酸性浸提液中，结果表明，不稳定的单核铝形态(Alb)远远大于稳定的单核铝形态，而不稳定的单核铝形态中含有对植物的致毒因子，因而酸雨能导致森林死亡，农作物发育不良。

水肥措施对文冠果叶片、果实养分分配的影响

文冠果（Xanthoceras sorbifolia Bunge）是我国北方特有的木本油料树种，已被列为生物质能源树种之一。现阶段产量低是限制其发展的重要因素。本文以内蒙古赤峰市翁牛特旗文冠果经济林场内50年生文冠果树为研究对象，对文冠果生物学、生态学特性进行定位观测和试验，分析了文冠果发育节律与积温的关系。野外布置水肥措施试验，测定了文冠果产量和叶片、果实养分元素（N、P、K、Mg、Ca、Fe、Zn、Cu、Mn）的含量，分析了水肥措施对叶片、果实养分分配的影响。 主要结论： 1.文冠果物候期与积温呈显著的直线函数关系。能够用来预测文冠果年生长发育期有效积温的理论值，为经营管理提供依据。 2.文冠果叶片中主要元素含量随物候期的变化呈下降趋势，但微量元素呈增加趋势。养分重吸收水平由大到小的顺序是：Mg>N>K>P，一定的水肥措施提高了文冠果养分再吸收水平，并降低了功能叶中的N/P、C/N。 3.文冠果果实中Ca和Fe随物候期的变化呈下降趋势，其他元素呈先减后增趋势。水肥措施降低了果实对养分元素的分配和收获系数；提高了养分利用效率。 4.合理的水肥措施能显著提高种子产量，增加含油率。最佳水肥措施为：5月初灌水50mm，施肥量为N 63 g•株-1、P2O5 83.3 g•株-1，于5、7月初分2次等量施入。 5.水分、P是文冠果生长的主要限制性因子，限制性因子具有阶段性。水分对肥效有“激发效应”。

低能离子注入小麦种子胚内的射程分布

采用110keV56Fe1+离子束垂直注入小麦种胚后,将小麦沿腹面的纵沟掰开,形成剖面,将剖面水平朝上粘贴在金属铜托上,用扫描电镜在剖面上从胚表面向纵深进行点分析,测定不同深度上由Fe元素激发出的特征X射线强度,由此得到了该种离子注入小麦胚内的最大射程约5μm,最可几射程为0.935μm.并对这种低能离子注入作物种子能诱发突变的机理进行了详细讨论.

重离子辐照引起的金属/金属界面混合与相变研究

本论文用重离子在室温下辐照Fe/Cu(Si/Fe(10nm)/[Cu(2.5nm)/Fe(2.5nm)]8/Cu(5n m)、Si/Fe(10nm)/[Cu(4nm)/Fe(4nm)]5(8)/Cu(4nm)、Si/[Fe(10nm)/Cu(10nm)]5)和Fe/Nb(Si /[Fe(10nm)/Nb(4nm)/Fe(4nm)/Nb(4nm)]2/[Fe(4nm)/Nb(4nm)]4))金属多层膜样品，然后利用X射线衍射谱、俄歇电子元素深度剖析谱、透射电子显微镜和振动样品磁强计对样品进行分析。主要研究界面原子混合、相变现象及其与离子辐照参数之间的关系。 1. 室温下用400 keV Xe离子辐照Fe/Cu(Si/Fe(10nm)/[Cu(2.5nm)/Fe(2.5nm)]8/Cu (5nm)、Si/Fe(10nm)/[Cu(4nm)/Fe(4nm)]5/Cu(4nm))和Fe/Nb多层膜。结果显示：随着辐照量的增加，离子辐照引起了Fe/Cu多层膜中Fe与Cu原子的混合和Cu基fcc固溶体和Fe基bcc固溶体地出现；而在Fe/Nb多层膜中，离子辐照引起Fe与Nb原子的混合和FeNb固溶体和非晶态FeNb合金相的出现。随着样品的结构变化，样品的磁滞回线也发生了变化。 2. 室温下用2 MeV Xe离子辐照Fe/Cu和Fe/Nb多层膜。结果显示：随着辐照量的增加，首先发生Fe、Cu原子的偏析和界面锐化，接着发生混合，辐照量较大时形成Cu基fcc固溶体和Fe基bcc固溶体；而在Fe/Nb多层膜中，低辐照量辐照引起多层膜的界面锐化，高辐照量辐照引起Fe与Nb原子混合和FeNb固溶体和非晶态FeNb合金相的出现。随着样品的结构变化，样品的磁滞回线也发生了变化。 3. 室温下用2.03 GeV Kr离子辐照Fe/Cu和Fe/Nb多层膜。结果显示：对于Si/Fe(10nm)/[Cu(4nm)/Fe(4nm)]5/Cu(4nm)多层膜，辐照量为1.0×1013ions/cm2时，发生Fe、Cu原子的偏析和界面锐化；对于Si/[Fe(10nm)/Cu(10nm)]5多层膜，随着辐照量的增加，首先发生Fe、Cu原子的偏析和界面锐化，接着发生混合；对于Fe/Nb多层膜，低辐照量辐照引起多层膜的界面锐化，高辐照量辐照引起Fe与Nb原子混合。随着样品的结构变化，多层膜样品的磁滞回线也发生了变化。 4. 室温下用1.08 GeV Kr离子辐照Fe/Cu和Fe/Nb多层膜。结果显示：在Si/Fe(10nm)/[Cu(4nm)/Fe(4nm)]5/Cu(4nm)、Si/[Fe(10nm)/Cu(10nm)]5和Fe/Nb多层膜中，辐照引起Fe层与Cu（Nb）层混合。随着样品的结构变化，多层膜样品的磁滞回线也发生了变化。 最后，对重离子辐照引起多层膜界面原子混合及相变的机理进行了探讨

Coking kinetics on the catalyst during alkylation of fcc off-gas with benzene to ethylbenzene

The production of ethylbenzene from the alkylation of dilute ethylene in fee off-gases with benzene has been commercialized in China over a newly developed catalyst composed of ZSM-5/ZSM-11 co-crystallized zeolite. The duration of an operation cycle of the commercial catalyst could be as long as 180 days. The conversion of ethylene could attain higher than 95%, while the amount of coke deposited on the catalyst was only about 10 wt.%. Thermogravimetry (TG) was used to study the coking behavior of the catalyst during the alkylation of fee off-gas with benzene to ethylbenzene. Based on effects of reaction time, reaction temperature, reactants and products on coking during the alkylation process, it is found that the coking rate during the alkylation procedure follows the order: ethylbenzene > ethylene > propylene > benzene for single component, and benzene-ethylene > benzene-propylene for bi-components under the same reaction condition. Furthermore, the coking kinetic equations for benzene-ethylene, benzene-propylene and ethylbenzene were established. (C) 2003 Elsevier B.V. All rights reserved.

Investigation on the catalytic roles of silver species in the selective catalytic reduction of NOx with methane

Silver impregnated H-ZSM-5 zeolite catalysts with silver loading from 3 to 15 wt.% were investigated for the selective catalytic reduction (SCR) of NOx with CH4 in the excess of oxygen. X-ray diffraction (XRD) and UV-Vis measurements established the structure of silver catalysts. A relationship between the structure of silver catalysts and their catalytic functions for the SCR of NOx by CH4 was clarified. The NO conversion to N-2 showed a S-shape dependence on the increase of Ag loading. No linear dependence of catalytic activity on the amount of silver ions in the zeolite cation sites was observed. Contrastively, the activity was significantly enhanced by the nano-sized silver particles formed on the higher Ag loading samples (greater than or equal to7 wt.%). Temperature programmed desorption (TPD) and temperature programmed reduction (TPR) studies showed that nano-silver particles provided much stronger adsorption centers for active intermediates NO3-(s) on which adsorbed NO3-(s) could be effectively reduced by the activated methane. Silver ions in the zeolite cation sites might catalyze the reaction through activation of CH4 at lower temperatures. Activated CH4 reacted with NO3-(s) adsorbed on nano-silver particles to produce N-2 and CO2. (C) 2003 Elsevier B.V. All rights reserved.

On the induction period of methane aromatization over Mo-based catalysts

The behavior of different species during the temperature-programmed surface reaction (TPSR) of methane over various catalysts is traced by an online mass spectrometer, It is demonstrated that the transformation of MoO3 to molybdenum carbide hinders the activation of methane as well as the succeeding aromatization in the TPSR, If this transformation process is done before the reaction, the temperature needed for methane activation and benzene formation will be greatly lowered (760 and 847 K, respectively). On the basis of comparison of the catalytic behavior of molybdenum supported on different zeolites, it is suggested that the initial activation of methane is the rate-determining step of this reaction. For the cobalt catalysts supported on HMCM-22 or Mo catalysts supported on TiO2, no benzene formation could be observed during the TPSR, However, the prohibition of benzene formation is different in nature over these two catalysts: the former lacks the special properties exhibited by molybdenum carbide, which can continuously activate methane even when multiple layers of carbonaceous species are formed on its surface, while the latter cannot accomplish the aromatization reaction since there are no Bronsted acid sites to which the activated intermediates can migrate, although the activation of methane can be achieved on it. Only for the catalysts that possess both of these properties, together with the special channel structure of zeolite, can efficient methane aromatization be accomplished. (C) 2000 Academic Press.

The combined catalytic action of solid acids with nickel for the transformation of polypropylene into carbon nanotubes by pyrolysis

The effects of both organically modified montmorillonite (OMMT) and Ni2O3 on the carbonization of polypropylene (PP) during pyrolysis were investigated. The results from TEM and Raman spectroscopy showed that the carbonized products of PP were mainly multiwalled carbon nanotubes (MWNTs). Surprisingly, a combination of OMMT and Ni2O3 led to high-yield formation of MWNTs. X-ray powder diffraction (XRD) and GC-MS were used to investigate the mechanism of this combination for the high-yield formation of MWNTs from PP. Bronsted acid sites were created in degraded OMMT layers by thermal decomposition of the modifiers. The resultant carbenium ions play an important role in the carbonization of PP and the formation of MWNTs. The degradation of PP was induced by the presence of carbenium ions to form predominantly products with lower carbon numbers that could be easily catalyzed by the nickel catalyst for the growth of MWNTs. Furthermore, carbenium ions are active intermediates that promote the growth of MWNTs from the degradation products with higher carbon numbers through hydride-transfer reactions. The XRD measurements showed that Ni2O3 was reduced into metallic nickel (Ni) in situ to afford the active sites for the growth of MWNTs.

Co-assembly of ferrocene-terminated and alkylthiophene thiols on gold and its redox chemistry modulated by surfactant adsorption

Coadsorption of ferrocene-terminated alkanethiols (FcCO(2)(CH2)(8)SH, Fc=(mu(5)-C5H5)Fe(mu(5)-C5H4)) with alkylthiophene thiols (2-mercapto-3-n-octylthiophene) yields stable, electroactive self-assembled monolayers on gold. The resulting mixed monolayer provides an energetically favorable hydrophobic surface for the adsorption of the surfactant aggregates in aqueous solution. The adsorptions have been characterized via their effect on the redox properties of ferrocenyl alkanethiols immobilized as minority components in the monolayers and on the interfacial capacitance of the electrode. Surfactant adsorption causes a decrease in the overall capacitance at the electrode and dramatically shifts the redox potential for ferrocene oxidation in a positive or negative direction depending on the identity of the surfactant employed. A structural model is proposed in which the alkane chains of the adsorbed surfactants interdigitate with those of the underlying self-assembled monolayer, leading to the formation of a hybrid bilayer membrane.

以亚磷酸二乙酯为第三组分的铁系催化体系催化异戊二烯聚合

以乙酰丙酮铁 (简称Fe) /三异丁基铝 (简称Al) /亚磷酸二烷基酯 (简称DP)为催化体系 ,对异戊二烯进行聚合 ,考察了不同DP(烷基为甲基、乙基、正丁基或异辛基 )、催化剂组成及反应条件对聚合的影响。结果表明 ,以亚磷酸二乙酯 (DEP)为第三组分的催化体系 ,在己烷中于相对较高温度 (5 0℃ )下的催化活性最高。催化剂最佳配比为Al/Fe(摩尔比 ) 1 5 ,DEP/Fe(摩尔比 ) 2 0。所得聚异戊二烯橡胶的 3 ,4-结构(含 1 ,2 -结构 )摩尔分数约为 60 % ,微观结构基本不受反应条件的影响。

Half-sandwich metal diselenolate complexes Cp#M(NO)(SePh)(2) (M = Mo or W; Cp# = Cp or MeCp) as ligands. Synthesis of selenolate-bridged heterobimetallic compounds

The reactions of half-sandwich diselenolate Mo and W complexes (CpM)-M-#(NO)(SePh)(2) (M = Mo; Cp-# = Cp' (1a), MeCp (1b); M = W; Cp-# = Cp' (1c)) with (Norb)Mo(CO)(4), Ni(COD)(2) and Fe(CO)(5) have been investigated. Treatment of (1a), (1b) and (1c) with (Norb)Mo(CO)(4) in PhMe gave the bimetallic complexes: Cp'Mo(NO)(mu -SePh)(2)Mo(CO)(4) (2a), MeCpMo(NO)(mu -SePh)(2)Mo(CO)(4) (2b) and Cp'W(NO)(mu -SePh)(2)Mo(CO)(4) (2c) in moderate yields. Irradiation of (1a) and (1c) in the presence of Fe(CO)(5) gave heterobimetallic complexes Cp'Mo(CO)(mu -SePh)(2)Fe(CO)(3) (3a) and Cp'W(NO)(mu -SePh)(2)Fe(CO)(3) (3c). Ni(COD)(2) reacts with two equivalents of (1a), (1b) and (1c) to give [Cp'Mo(NO)(mu -SePh)(2)](2)Ni (4a), [MeCpMo(NO)(mu -SePh)(2)](2)Ni (4b) and [Cp'W(NO)(mu -SePh)(2)](2)Ni (4c) in good yields. The new heterobimetallic complexes were characterized by i.r., H-1-n.m.r., C-13-n.m.r. and EI-MS spectroscopy.

烯丙基取代的铁系“茂后”烯烃聚合催化剂的合成及其催化乙烯聚合的研究

合成了烯丙基取代的含氮中性配体 [( p-C3H5) C12 H16]2 N3C9H9,然后与 Fe Cl2 反应合成含烯丙基取代的三齿“茂后”烯烃聚合催化剂 [( p-C3H5) ( C12 H16) ]2 N3C9H9Fe Cl2 ,通过 IR,1H NHR,EI-MS对化合物进行了表征 .研究了它催化乙烯聚合的能力 ,这种催化剂与 MAO组成的催化体系可在常压下催化乙烯聚合 ,活性最高达 1 .9× 1 0 6g PE/ ( mol Fe· h) .所得聚乙烯粘均分子量在 5× 1 0 4 ～ 2 .6× 1 0 5之间