三氧化二铝溶胶-凝胶固定过氧化氢生物传感器

三氧化二铝溶胶凝胶将辣根过氧化物酶和硫堇同时固定在玻碳电极上,紫外-可见光谱结果表明酶在固定过程中生物活性保持得较好.传感器在pH 7.0外加电压为-0.22 V条件下,对过氧化氢浓度为1.76×10-3～5.5×10-2 mol/L的范围内呈线性响应,检出限为1.1×10-4 mol/L.传感器的选择性和稳定性较好,使用3个星期后,仍能保持其初始活性的80%.     

Modeling Studies of the Formation and Destruction of NO in Pulsed Barrier Discharges in Nitrogen and Air

This paper presents the results of modeling studies on the formation and destruction of NO in pulsed barrier discharges in nitrogen and air. The goals of this work are to identify the major processes involved in the formation and destruction of NO in air discharges, to distinguish between oxidative and reductive paths for NO destruction, to explore the potential importance of excited state reactions, to evaluate the role of water in such systems, and to identify the final products in the absence of heterogeneous processes. In all cases, the systems were modeled with 100×10^–4% (100 ppm) of added NO, with and without 3% added water. The focus in all of this work is chemistry in the post-pulse regime.     

2-Quinazolylguanidines in Heterocyclization Reactions. 2. Condensation with α,β-Unsaturated Carbonyl Compounds

4,6,6-Trimethyl-1,4-dihydropyrimidines have been synthesized by condensation of 2-quinazolylguanidines with mesityl oxide. The analogous reaction with benzalacetone leads to unstable 4-methyl-6-phenyl-1,4-dihydropyrimidines, which are oxidized to the corresponding 4-methyl-6-phenylpyrimidines.     

Evolution of water vapor from indium-tin-oxide transparent conducting films fabricated by dip coating process

Tin-doped indium oxide In₂O₃ (indium-tin-oxide) transparent conducting films were fabricated on silicon substrates by a dip coating process. The thermal analysis of the ITO films was executed by temperature-programmed desorption (TPD) or thermal desorption spectroscopy (TDS) in high vacuum. Gas evolution from the ITO film mainly consisted of water vapor. The total amount of evolved water vapor increased on increasing the film thickness from approx. 25 to 250 nm and decreased by increasing the preparation temperature from 365 to 600°C and by annealing at the same temperature for extra 10 h. The evolution occurred via two steps; the peak temperatures for 250 nm thick films were approx. 100-120 and 205-215°C. The 25 nm thick films evolved water vapor at much higher temperatures; a shoulder at approx. 150-165°C and a peak at approx. 242°C were observed. The evolution temperatures increased by increasing the preparation and the annealing temperatures except in case of the second peak of the 25 nm thick films. The evolution of water vapor at high temperature was tentatively attributed to thermal decomposition of indium hydroxide, In(OH)₃, formed on the surface of the nm-sized ITO particles. This revised version was published online in August 2006 with corrections to the Cover Date.     

Ti-Si复氧化物载体对金催化剂上丙烯环氧化的影响

 以TiCl4和SiCl4为原料,采用水解和非水水解溶胶-凝胶两种方法制备了一系列不同Ti含量的Ti-Si复氧化物载体,继而用沉积-沉淀法制得载金催化剂. 采用X射线衍射、紫外-可见漫反射光谱、 N2吸附和高分辨透射电镜对催化剂进行了表征,并考察了催化剂在氢气和氧气存在下的丙烯气相环氧化催化性能. 研究表明,钛含量在6%～14%范围内时,两种方法制得的Ti-Si复氧化物均为无定形结构,但采用非水水解溶胶-凝胶法制得的载体比表面积较高. 以非水水解溶胶-凝胶法制备的钛含量10%的Ti-Si复氧化物为载体得到的载金催化剂表现出较高的活性和选择性,反应60 min时,丙烯转化率为5.7%, 240 min后降为3.3%, 环氧丙烷的选择性稳定于95%左右. 还考察了非水水解溶胶-凝胶的陈化时间和金沉积-沉淀溶液的pH值等对反应结果的影响.     

四元配合物[Nd(C_4H_3OCOO)_2·NO_3·C_(10)H_8N_2]_2的合成与晶体结构

稀土羧酸配合物在萃取分离、杀菌、催化和发光材料等方面有广泛的应用[1]。将氮杂环双齿配位体引入到这类配合物中可增强配合物的共轭作用,提高稳定性并增强其杀菌能力和发光性质[2]。虽然氮杂环双齿配位体邻菲咯啉的稀土羧酸配合物报道较多,但含2,2′联吡啶配位的稀土羧酸配合物的研究相对较少,尤其是含2,2′联吡啶的四元稀土羧酸混配配合物的研究更为少见[3]。2呋喃甲酸是糠醛在人体中的代谢产物,可做为防腐剂、熏蒸剂等,本文报道[Nd(C4H3OCOO)2·NO3·C10H8N2]2配合物的合成和单晶X射线衍射分析结果。2呋喃甲酸(分析纯)、2,2′联吡…     

Effect of Ba and Bi doping on the synthesis and sintering of Ge-based apatite phases

Recently, high oxide ion conduction has been observed in the apatite-type systems La_9.33+x(Si/Ge)₆O_26+x/2, with conductivities approaching and even exceeding that of yttria-stabilized zirconia. The Ge-based phases have been reported to suffer from Ge loss and undergo irreversible structural changes on sintering at the high temperatures required to obtain dense pellets. In this paper we discuss doping studies (Ba, Bi for La) aimed at stabilizing the hexagonal apatite lattice to high temperature, and/or lowering the synthesis and sintering temperatures. The results show that doping with Ba helps to stabilize the hexagonal lattice at high temperatures, although Ge loss appears to still be a problem. Conductivity data show that, as previously reported for the Si-based systems, non-stoichiometry in the form of cation vacancies and/or oxygen excess is required to achieve high oxide ion conduction in these Ge-based systems. Neutron diffraction structural data for the fully stoichiometric phase La₈Ba₂Ge₆O₂₆ shows that the channel oxygen atoms show little anisotropy in their thermal displacement parameters, consistent with the low oxide ion conductivity of this phase. Bi doping is shown to lower the synthesis and sintering temperatures, although the presence of Bi means that these samples are not stable at high temperatures under reducing conditions.Presented at the OSSEP Workshop Ionic and Mixed Conductors: Methods and Processes, Aveiro, Portugal, April 10–12, 2003     

催化裂化USY／ZnO／Al2O3脱硫添加剂的高温水热失活

 对USY／ZnO／Al2O3汽油催化裂化脱硫添加剂经高温水热老化处理前后的脱硫性能进行了考察，发现老化后添加剂的脱硫性能大幅度下降．采用XRD和IR等技术对USY／ZnO／Al2O3添加剂在高温和高温水热条件下失活的原因进行了研究．结果表明，在高温下，ZnO可与USY沸石中的铝发生固相反应生成ZnAl2O4尖晶石，从而造成USY晶体结构崩塌，转变成无定形状态．在ZnO含量较高的条件下，ZnO可继续与USY晶体结构崩塌后生成的无定形的硅和铝的氧化物反应，生成Zn2SiO4硅锌矿和ZnAl2O4尖晶石结构．这一方面使添加剂失去了可形成硫化物吸附中心的ZnO，另一方面破坏了硫化物的裂化活性组分USY，从而造成添加剂脱硫性能下降甚至失去脱硫活性．ZnO对USY的破坏作用主要与温度有关．在USY／ZnO／Al2O3体系中，ZnO被ZnO与Al2O3之间形成的锌铝尖晶石膜固定并与USY隔离，单纯的高温条件对添加剂的破坏不显著，而水蒸气可以促进ZnO的移动，有利于ZnO与USY的接触，因此在高温和有水蒸气存 在的条件下添加剂的结构易遭到破坏．     

电化学聚合吡咯/噻吩导电共聚物纳米纤维阵列及其表征

导电聚合物因其具有良好的空气稳定性、电化学成膜性和导电性等特点,在二次电池、电色显示及固体电容器等方面都有诱人的应用前景.近年来人们研究导电聚合物的纳米结构时发现,由于超分子效应,纳米纤维中聚合物链会以平行于纤维轴向为优先取向,这种优先取向使导电聚合物纳米纤维的电导率比块材有极大提高.     

水溶性聚合物和两亲聚合物:12.环氧乙烷-环氧丙烷无规共聚醚结构与性能的关系

来用连续加料法,以二元醇-KOH为引发剂合成一组不同组成的环氧乙烷-环氧丙烷无规共聚醚,并用核磁共振、红外光谱、示差扫描量热计和热失重等方法对其本体聚合物,用浊点和表面张力测定的方法对其水溶液,进行系统的表征。