Effect of a low magnetic field on crystallinity and magnetic susceptibility of molecular magnet {NBu4[FeCr(ox)3]}x (NBu4=tetra( n-butyl) ammonium ion; ox=oxalate ion)

Molecular magnet {NBu₄[Fe Cr(ox)₃]}_x (NBu₄⁺=tetra(n-buty1) ammonium ion; ox²⁻=oxalate ion) was synthesized under an applied low magnetic field of 0.3 T in comparison to that synthesized without a field. Their crystallinities, morphologies and magnetic properties were characterized by using the X-ray diffractionmeter, the transmission electron microscope, and a superconducting quantum interference device. It is found that the average size of particles synthesized under the applied field appears larger than that synthesized without a field. Moreover, its crystallinity, morphology and magnetic susceptibility have also been improved. However, its chemical structure and ferromagnetic phase transition temperature T_c do not change. Possible reasons to explain this effect are also discussed.     

Sr1-xLaxTiO3的高温高压合成及XPS研究

 利用高温高压方法合成了有稀土元素La掺杂的钙钛矿氧化物Sr_1-xLa_xTiO₃。XRD测试表明，在x≤0.5时，样品基本为单相，呈立方相；晶胞体积随x的增加而增加，在x=0.4时开始减小。XPS测量发现，样品中存在Ti离子的变价。讨论了Ti离子价态的变化对晶格参数的影响。     

偶氮侧基聚合物光致异构动力学研究

本文对偶氮侧基聚合物相位共轭光时间特性进行了研究,得到了相位共扼光产生机制─光致异构过程的时间常数.在相位共轭光上升阶段,其时间常数在0.4～0.5s之间,在相让共轭光的衰减过程,衰减满足双指数关系,分段拟合得到较好的结果,且得到快过程的时间常数为0.27s,慢过程的时间常数为0.78s.     

稀土富勒烯生成的影响因素初探

采用某些特殊的放电和提取方法，如反向放电和甲苯高温高压提取等可以有效地提高稀土富勒烯的生成效率［‘，‘’，并已先后成功高效地合成了许多含稀土富勒烯「‘’．对其提纯、表征、衍生和应用也进行了研究［‘－’j．但对影响稀土富勒烯生成的因素研究较少．在石墨律中同时填入La，Y，Sc的稀土氧化物，对其稀土富勒烯生成效率的情况进行了研究，认为稀土元素的第一电离能是影响稀土富勒烯生成的主要因素‘’，’‘．Moro等采用激光和热解吸质谱对稀土富勒烯的研究结果表明，稀土元素的氧化态是影响稀土富勒烯生成的决定性因素”’．本…     

含CdS的聚碳酸醋薄膜的光电效应

近来有一些学者从理论或实践上探讨了模拟植物光合作用的光电化学膜体系用于太阳能转换的可能性。这种体系的核心是一个具有光活性的膜,把两个含有氧化还原偶的水溶液分隔开;当膜受光照时在膜里产生电荷(电子和空穴)的分离,电子到膜的一侧引起一个还原反应而空穴到膜的另一侧引起一个氧化反应。本文用一种聚碳酸酯的透明薄膜(商品名Nuclepore membrane),膜上已用中子照射的方法打好了大小和分布都很均匀的大量微孔,然后在这些微孔里形成CdS沉淀。这样得到的光活性膜体系,改性后在光照时能     

统计模拟分光光度法测定复方消咳新片组分含量

用统计模拟分光光度法测定复方消咳新片４个组分含量。按均匀设计表制备合成样品，绘制溶液的ＵＶ－ＶＩＳ吸收曲线，获得有限但足够的实验数据，用逐步回归法构造反映该复方制剂组分在灵敏波长的吸光度－组分含量经验关系的“最优”数学模型，用改进单纯形法寻优，求出未知样品的各组分含量。磺胺甲基异恶唑、甲氧苄胺嘧啶、盐酸溴已新、枸橼酸维静宁的回收率分别为１００３％、１００４％、９９９％、９９０％，标准差分别为０９１％、１４％、１２％、３９％。     

微波场中甲烷部分氧化制合成气 Ⅱ.Co/ZrO_2催化剂在微波场中的升温行为及催化活性

近年来，甲烷部分氧化制合成气（ＰＯＭ）的研究一直十分活跃［１，２］．前文报道了用于甲烷部分氧化制合成气的镍基催化剂（Ｎｉ／Ｌａ２Ｏ３）在微波场中的升温行为和催化活性［３］，发现在达到相同的ＣＨ４转化率时，微波活化方式下的催化剂床层温度比常规加热低得多...     

Robust core-shell supramolecular assemblies based on cationic vesicles and ring-shaped [Mo154] polyoxomolybdate nanoclusters: template-directed synthesis and characterizations

Substantial progress has been made recently in extending the supramolecular assembly of biomimetic structures to vesicle-based sophisticated nanocomposites and mesostructures. We report herein the successful preparation of unilamellar surfactant vesicles coated with a monolayer of ring-shaped [Mo(154)] polyoxometalate (POM) nanoclusters, (NH(4))(28)[Mo(154)(NO)(14)O(448)H(14)(H(2)O)(70)]. approximately 350 H(2)O, by coulomb attractions using preformed didodecyldimethylammonium bromide (DDAB) surfactant vesicles as templates. The resultant vesicle-templated supramolecular assemblies are robust (they do not disintegrate upon dehydration) both at room-temperature ambient and vacuum conditions, as characterized by conventional transmission electron microscopy (TEM) and atomic force microscopy (AFM). The flexibility of the complex soft assemblies was also revealed by AFM measurements. The effect of POM-vesicle coulomb attractions on the dimensions of the templating vesicles was also investigated by using dynamic light scattering (DLS). Although origins of the structure stability of the as-prepared supramolecular assemblies are not clear yet, the nanometer scale cavities and the related properties of macroions of the POM clusters may play an important role in it.