Sulfated silica-titania aerogel as a bifunctional oxidative and acidic catalyst in the synthesis of diols

Sulfated silica-titania aerogel (SO₄/ST) catalyst was prepared by direct synthesis and modified with H₂SO₄ by wet impregnation method. Brønsted acid sites were generated after sulfation of the silica-titania aerogel with a pKa of −14.52. Consecutive transformation of 1-octene, catalyzed by sulfated silica-titania aerogel using aqueous hydrogen peroxide as oxidant shows high activity towards 1,2-octanediol through the formation of 1,2-epoxyoctane. The formation of 1,2-octanediol is enabled by the co-existence of sulfated Ti species with Brønsted acid sites in the SO₄/ST system. Sulfated silica-titania aerogel catalyst produced 1,2-octanediol (326 μmol) with selectivity of 63%. In contrast, no diol was produced when silica-titania aerogel was used.     

Luminescent and scintillation properties of the Pr3+ doped single crystalline films of Lu3Al5−xGaxO12 garnet

The Pr³⁺ d–f luminescence was investigated in the single crystalline films (SCF) of Lu₃Al_5−xGa_xO₁₂:Pr garnet solid solution at x = 1–3, grown by the liquid phase epitaxy (LPE) method from the melt-solution based on the PbO–B₂O₃ flux. The shape of CL spectra and decay kinetics of Pr³⁺ ions in Lu₃Al_5−xGa_xO₁₂ SCFs strongly depend on the total gallium concentration x and distribution of Ga³⁺ ions between the tetrahedral and octahedral position of the garnet host. The best scintillation properties of Lu₃Al_5−xGa_xO₁₂:Pr SCF are achieved at the nominal Ga content in melt-solution in the x = 2–2.5 range.     

Modification of montmorillonite by quaternary polyesters

In this paper, we report on the preparation of organically modified montmorillonite (OMM) and its properties, using quaternary polyesters. The polyester was synthesized from N-methyldiethanolamine and succinic acid anhydride, converted to the quaternary polyester using benzyl bromide, and characterized by nuclear magnetic resonance (NMR), size exclusion chromatography (SEC), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Quaternary polyesters with a quaternization degree of 0.25 and 0.5 were used to modify montmorillonite (MMT). The intercalation was determined by X-ray diffraction. Interlayer spacing increased with decreased MMT/polyester ratio and with increased degree of quaternization. The thermal stability of polyester bound to MMT greatly increased.     

Fabrication of nanocomposites by collagen templated synthesis of layered double hydroxides assisted by an acrylic silane coupling agent

The purpose of this study was to control the fabrication of nanocomposites at the nanoscale interface by collagen templated synthesis of Zn-Al layered double hydroxides (LDHs) assisted by γ-methacryloxypropyl trimethoxy silane (KH570) with further treatment of graft polymerization. The results show that collagen directs the growth of LDHs into curved nanorods by length of 300 nm in perfect consistency with collagen chain in both the size and flexility under the essential hydrophobic environment on the solid surface provided by KH570. The nanorods are aggregated into thin curved platelets due to strong interaction between collagen molecules themselves and strong interaction between collagen and LDH sheets. By further treatment of graft polymerization, the adjacent curved platelets encircle into numerous hollows via chemical linkage, achieving polyporous nanocomposites. Nanohybrid materials with this structure are especially interesting for applications as biosensors or supported catalysis.     

掺Er/Pr的GaN薄膜深能级的研究

利用深能级瞬态谱(DLTS)、傅里叶变换红外光谱(FT-IR)对GaN以及GaN掺Er/Pr的样品进行了 电学和光学特性分析.研究发现未掺杂的GaN样品只在导带下0.270eV处有一个深能级；GaN注 入Er经900℃,30min退火后的样品出现了四个深能级，能级位置位于导带下0.300 eV,0.188 eV,0.600 eV 和0.410 eV；GaN注入Pr经1050℃,30min退火后的样品同样出现了四个深能级 ，能级位置位于导带下0.280 eV,0.190 eV,0.610 eV 和0.390 eV；对每一个深能级的来源 进行了讨论.光谱研究表明，掺Er的GaN样品经900℃,30min退火后，可以观察到Er的1538nm 处的发光，而且对能量输运和发光过程进行了讨论. 关键词： GaN Er Pr 深能级     

The -spectrum and spanning trees of tensor products of bipartite graphs

Recently, Knuth and Ciucu independently proved the surprising fact, conjectured by Stanley, that one connected component of the tensor product of a path with itself (the so-called ``Aztec diamond graph') has four times as many spanning trees as the other connected component, independent of the length of the path. We show here that much more is true: the connected components of the tensor product of any connected bipartite multigraphs all have essentially the same -spectrum. It follows at once that there is a simple formula relating their numbers of spanning trees.

     

ICP－AES直接测定荧光级氧化铕中5个稀土杂质

本文采用ＪｏｂｉｎＹｖｏｎ３８Ⅱ光谱仪直接测定高纯氧化铕中Ｃｓ、Ｐｒ、Ｓｍ、Ｇａ、Ｄｙ５个稀土杂质，试验考查了氧化铕基体，共存元素，酸度等因素的影响。利用正文试验Ｌ＿（２５）（５）￣６确定了仪器最佳条件。当基体纯度为９９．９９％时；回收率在９４．０～１０８．０％之间。在实际应用中获得满意的结果。     

钙钛矿型层状化合物K2Pr2Ti3O10的合成及XRD研究

在K2CO3-镧系元素氧化物(Pr2O3)-TiO2三元体系中,用固相反应法合成K2Pr2Ti3O10,利用X射线粉晶衍射仪对K2Pr2Ti3O10进行扫描测定,获得X射线衍射数据,进行指标化,得到其晶胞参数。XRD分析结果表明,K2Pr2Ti3O10为四方晶系,空间群I4/mmm。