聚丙撑碳酸酯的辐射效应

研究了室温条件下聚丙撑碳酸酯(PPC)在钴-60和电子加速器辐照过程中的响应行为。结果表明,聚丙撑碳酸酯是一种辐射裂解型聚合物,其分子量随着辐射剂量的增加而减小。1mm厚PPC片材在室温和N2气保护条件下,其裂解G值为Gs,γ-ray=10.81;Gs,EB=4.9。不同的裂解G值表明,O2气在聚丙撑碳酸酯的辐射裂解过程中有重要影响。红外光谱研究表明,辐射后聚丙撑碳酸酯在3474cm-1处的峰宽峰高增加,表明其裂解后端—OH基增加。由于裂解作用,辐射后聚丙撑碳酸酯的抗张强度和断裂伸长率均下降。在通常的辐射消毒剂量范围内(25~50kGy),PPC的保留抗张强度大于23MPa,断裂伸长率大于4%,裂解后试样的力学性能依然能够满足实际应用需要,因此PPC可以经受辐射消毒。

Effects of Pr dopant on grain boundary and electrical properties of Ce5.2Sm0.8MoO15-delta

Material formulated as Ce5.2Sm0.8-xPrxMo15-(delta) (x=0.08) was prepared by adding small amounts of Pr dopant in oxide Ce5.2SM0.8-xPrxMoO15-delta. Structural and electrical properties were investigated by means of X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and AC impedance spectroscopy. The effect of small amounts of Pr on microstructure and electrical conductivity was discussed. It was showed that the material doped with Pr has a lot of dents and small openings, which provide channels for oxygen ions, resulting in lower grain boundary and total conductivity activation energy. Thus the corresponding grain boundary conductivity and total conductivity of the material were improved notably. The grain boundary conductivity of the material doped with Pr is 6.79 X 10(-3) S center dot cm(-1) at 500 degrees C, which is twice as large as that without Pr (5.61 X 10(-5) S center dot cm(-1)).

吗啉胍同多十钒酸盐的自组装合成、结构表征及抗菌活性

通过十钒酸盐与吗啉胍在不同 p H值水溶液中的自组装 ,合成了 2个新化合物 ( C6 H1 4N5O) 4·[H2 V1 0 O2 8]· 9H2 O( 1 )和 ( C6 H1 4N5O) 6 [V1 0 O2 8]· 4H2 O( 2 ) .通过 IR,51 V NMR和 X射线衍射等方法对其结构进行了表征 .结果表明 ,化合物 1和 2是通过十钒酸根阴离子与质子化的吗啉胍阳离子以静电力和氢键构筑的 ,多阴离子及吗啉胍的结构基本保持不变 .抗菌试验结果表明 ,两种化合物对金黄色葡萄球菌、表皮葡萄球菌、耐甲氧西林金黄葡萄球菌和耐甲氧西林表皮葡萄球菌均具有较强的抑制活性.

(类)钙钛石型催化剂上NO分解反应机理的研究

研究了NO分解反应中NO2和O2形成的反应机理,同时也关联了吸附氧的脱附方式.结果表明,NO2的形成主要是在催化剂表面通过NO和吸附氧反应进行的,吸附的氧脱附是通过NO2的形式进行的,而O2的形成则主要是通过NO2的分解进行.

含铜氧化酶在活性炭上的固定及直接电化学

以吸附的方法将两种具有代表性的含铜氧化酶酪氨酸酶(Tyr)和漆酶(Lac)固定在活性炭粉表面, 结果表明, 活性炭能促进Tyr和Lac的直接电子转移反应, 循环伏安曲线上表现出一对准可逆的氧化还原峰; 式量电位E0' 几乎不随扫速而变化. 进一步的实验结果显示, 固定在活性炭上的Tyr和Lac能保持对O2还原的电催化作用. 本文固定酶的方法具有简单、易于操作和酶活性保持良好等优点, 可用于获得其他生物氧化还原蛋白质和酶的直接电子转移以及制备生物燃料电池电极催化剂.

炭载细胞色素c电极对H_2O_2还原的电催化性能

通过平衡吸附法将细胞色素c(Cytc)沉积到活性炭上制成Cytc C催化剂 ,循环伏安的结果表明 ,所得到的Cytc C催化剂对H2 O2 的电化学还原具有较好的催化活性 ,这为生物燃料电池的研制提供了一种较好的生物大分子固定方法和制备O2 和H2 O2 还原的催化剂的方法

新型橙红色长余辉发光材料Gd_2O_2S:Sm~(3+)的合成

采用固相反应法合成了一种新型的橙红色长余辉磷光粉 Gd2 O2 S:Sm3 + ,并用全自动 X射线粉末衍射仪表征了其结构 ,用荧光光谱仪测试了其激发、发射光谱、余辉光谱和余辉衰减曲线。 XRD证实其为单相的硫氧化钆。该磷光体呈现 Sm3 +的三个特征发射 (4G5/2 → 6HJ,J=5 /2 ,7/2 ,9/2 )。经紫外或可见光激发后能观察到长时间明亮的余辉发光。

Structure and catalytic properties of magnesia-supported copper salts of molybdovanadophosphoric acid

The structure and stability of magnesia-supported copper salts of molybdovanadophosphoric acid (Cu2PMo11VO40) were characterized by different techniques. The catalyst was prepared in ethanol by impregnation because this solvent does not hurt texture of the water-sensitive MgO and Cu2PMo11VO40. The Keggin-type structure compound may be degraded partially to form oligomerized polyoxometalate when supported on MgO. However, the oligomers can rebuild as the Keggin structure again after thermal treatment in air or during the reaction. Meanwhile, the V atoms migrate out of the Keggin structure to form a lacunary structure, as observed by Fourier transform IR spectroscopy. Moreover, the presence of Cu2+ as a countercation showed an affirmative influence on the migration of V atoms, and the active sites derived from the lacunary species generated after release of V from the Keggin anion. The electron paramagnetic resonance data imply that V5+ autoreduces to V4+ in the fresh catalyst, and during the catalytic reaction a large number of V4+ ions are produced, which enhance the formation of O2- vacancies around the metal atoms. These oxygen vacancies may also improve the reoxidation function of the catalyst. This behavior is correlated to higher catalytic properties of this catalyst. The oxidative dehydrogenation of hexanol to hexanal was studied over this catalyst.

Optical spectroscopy properties of KMgF3 : Eu2+ nanocrystals and powder synthesized by microemulsion and solvothermal process

Nanocrystals and powders of KMgF3 doped with Eu2+ were synthesized by the microemulsion method and the solvothermal process, respectively. The emission and excitation spectra of KMgF3:Eu2+ phosphors were measured and compared with those of the samples synthesized through a solid. state reaction, Bridgman-Stockbarger method, and mild hydrothermal technique. The KMgF3: Eu2+ samples synthesized by means of the microemulsion method and the solvothermal process show only a sharp emission peak located at 360 nm, in the emission spectra, which arises from the f -> f(P-6(1/2)-> S-8(1/2)) transition of Eu2+. The broad emission bands appear at 420 nm,,which arises from Eu2+ <- O2- cannot be observed(in the mild hydrothermal and single crystal samples, the emission peak at 420 nm besides the emission of Eu2+ at 360 nm is observed). In the excitation spectrum of the KMgF3: Eu2+ samples synthesized by the microemulsion method and the solvothermal process, the excitation peaks show an intensive blue shift. The blue shift can he attributed to the lower oxygenic content in the KMgF3: Eu2+ samples synthesized by the microemulsion method and the solvothermal process.

纳米CeO_2/阴离子聚氨酯复合材料

采用纳米微粒直接分散法合成了纳米 Ce O2 /阴离子聚氨酯复合材料 ,粘度分析表明 ,随着纳米Ce O2 含量的增加 ,复合材料的粘度降低 ;FT- IR分析表明 ,Ce O2 的吸收峰出现蓝移现象 ;TEM和光散射粒径分析表明 ,复合粒子仍以纳米量级存在 ,平均粒径为 35 nm,且呈单分散状态 ,Ce O2 纳米粒子均匀分散在聚氨酯中。并且对复合粒子形成机理及稳定性进行了初步探讨

共沉淀法合成稀土正磷酸盐(La,Gd)PO_4∶RE~(3+)(RE=Eu,Tb)及其真空紫外光谱特性

采用共沉淀法制备了稀土正磷酸盐荧光粉 ( La,Gd) PO4∶ RE3 +( RE=Eu,Tb) .红外光谱分析发现Gd PO4的红外光谱吸收峰与 La PO4一致 ,只是峰位向高波数方向移动 . ( La,Gd) PO4∶ RE3 +的真空紫外光谱特性研究表明 ,Gd3 +在能量传递过程中起中间体作用 .XPS研究揭示 ,La PO4的价带由 O2 -的 2 p能级构成 ,而 Gd PO4的价带则是由 O2 - 的 2 p能级和 Gd3 +的 4 f能级共同构成.

新型笼状同多钒酸盐[Ni(1,10′-phen)_3]_2·[V_2~ⅣV_8~ⅤO_(26)]的水热合成和晶体结构

尽管多金属氧酸盐 (POMs)的研究已有180多年的历史,但大量的POMs结构在最近几十年才被陆续解析出来[1～4].其中 ,同多钒酸盐由于钒配位几何形状的多样性,结构最为丰富 ,例如:[V4 O12 ]4-[5],[V5O14 ]3-[6],[V10 O2 8]6-[7] ,[V15O4 2 ]9-[8],[V13 O3 4 ]3-[9].值得注意的是,在这些化合物中,钒的化合价均处于最高氧化态+5价.由于+4价钒不易在溶液中(尤其是水中)稳定存在,因此在以往的常压溶液合成中具有混合价态的同多钒酸盐报道很少.与饱和价态的同多钒酸盐相比,混价多钒酸盐具有更为新奇的电荷分布和拓扑学几何构型,并且在 POMs的理论研究和抗病毒药物、电存储材料以及磁性材料等应用领域有特殊的研究和开发价值[1,10,11].因此,制备具有混价的新型同多钒酸盐一直倍受关注.近年来,水热合成技术的引入使同多钒酸盐合成化学迅速发展.水热体系提供了一个特殊的反应环境 [12 ],使制备各种具有混合价态的同多钒酸盐成为可能.Müller等[13]对这一领域开...

超导型复合氧化物在苯酚羟化反应中催化作用

采用柠檬酸络合法合成了一系列含铜复合氧化物 (超导体 ) .用化学滴定方法和O2 TPD等技术对所合成的复合氧化物的组成和表面性质进行了测定 .通过探讨催化剂结构与活性的关系 ,发现含铜复合氧化物中的非化学计量氧和铜离子的平均价态与苯酚羟化活性和过氧化氢分解活性密切相关 .在实验中观察到醌类化合物在苯酚羟化反应循环中具有增强电子传递功能 ,在此基础上提出了醌类化合物参与催化循环的机理.

耐甲醇氧还原复合催化剂四苯基铁卟啉-铂的研究

用平衡吸附法制备了炭载四苯基铁卟啉 铂 (FeTPP Pt/C)复合催化剂 ,比较了经不同温度热处理的FeTPP Pt/C和Pt/C对O2 还原的催化活性和耐甲醇能力。结果表明 ,热处理可改善Pt/C催化剂的耐甲醇能力 ;热处理的FeTPP Pt/C复合催化剂具有较高的氧还原催化活性和良好的耐甲醇能力 ,并且 70 0℃处理的FeTPP Pt/C对O2 还原的催化活性最高。

甲醇对微过氧化酶-11电化学行为的影响

用电化学和圆二色性 (CD)光谱方法比较了不含和含质量分数为 2 0 %甲醇的微过氧化物酶 -1 1 (MP-1 1 )溶液的电化学和电催化性能及结构的差别 .发现加入甲醇使 MP-1 1的电化学反应的可逆性和对 H2 O2 还原的电催化活性增加 ,这是由于加入甲醇使部分双聚的 MP-1 1分子变成单体分子 ,分子的 α-螺旋和 β-转角的结构含量增加 ,无规卷曲的结构含量降低 ,MP-1 1分子中血红素的暴露程度增加而引起的.