多功能两亲梳状聚合物的合成及包覆荧光量子点

利用溶液聚合和成酰胺反应合成了多功能梳状两亲性共聚物,聚(甲基丙烯酸-co-甲基丙烯酸十八酯)-(乙醇胺-乙二胺叶酸)(PSM-EE-FA).用红外光谱(FTIR),核磁共振(1H-NMR)及凝胶渗透色谱(GPC)表征了该聚合物的结构及分子量分布.实验结果证明合成了该聚合物,其数均分子量(Mn)为28600,多分散性为1.375.用该两亲梳状聚合物包覆油溶性CdSe/ZnS量子点,通过相转移作用,得到水溶性靶向量子点(PSM-EE-FA-QDs).该水溶性量子点溶液具有较好的稳定性.通过紫外-可见(UV-Vis)及荧光发射光谱分析对该量子点的光学性质进行研究.结果表明,PSM-EE-FA-QDs的紫外-可见光谱及荧光发射光谱峰形与原量子点基本一致.由于量子点表面聚合物层的形成,峰位发生少量红移.该量子点水溶液的荧光强度是原量子点氯仿溶液的98%,荧光产率是原量子点氯仿溶液的95%.动态光散射(DLS)及透射电镜(TEM)测试结果表明水溶性量子点分布均匀.合成的水溶性量子点不但光学性能稳定,而且聚合物及水溶性量子点的合成方法较为简便.     

Combinatorial Structure of Faces in Triangulations on Surfaces

Siberian Mathematical Journal - The degree $ d(x) $ of a vertex or face $ x $ in a graph $ G $ on the plane or other orientable surface is the number of incident edges. A face $ f=v_{1}ldots...     

Formation of Structural-Phase States in Alumina Ceramics VK-95 by Sintering in a Constant Magnetic Field

Russian Physics Journal -     

Structural Organization of Nanocomposite Crystals

Russian Physics Journal - A possibility of simulating the structure of real nanomaterials in the elliptical Riemannian space is discussed. It is shown that the experimentally determined parameters...     

Feasibility of covalent quasicrystals

An algorithm for constructing a quasicrystalline structure based on atoms with tetrahederal coordination of covalent atomic bonds (the typical coordination for group IV atoms) is proposed. The algorithm is used to construct a computer model of a cluster with icosahedral symmetry. The model is used to estimate the energy parameters of the structure and the distributions of bonds over interatomic bond lengths and interbond angles. The distributions obtained correlate well with the analogous results for silicon glasses and do not impose any fundamental constraints on the implementation of such structures in practice. Zh. éksp. Teor. Fiz. 114, 2187–2193 (December 1998)     

A new upper bound on the cyclic chromatic number

A cyclic coloring of a plane graph is a vertex coloring such that vertices incident with the same face have distinct colors. The minimum number of colors in a cyclic coloring of a graph is its cyclic chromatic number χ^c. Let Δ^* be the maximum face degree of a graph. There exist plane graphs with χ^c = ?3/2 Δ^*?. Ore and Plummer [ 5 ] proved that χ^c ≤ 2, Δ^*, which bound was improved to ?9/5, Δ^*? by Borodin, Sanders, and Zhao [ 1 ], and to ?5/3,Δ^*? by Sanders and Zhao [ 7 ]. We introduce a new parameter k^*, which is the maximum number of vertices that two faces of a graph can have in common, and prove that χ^c ≤ max {Δ^* + 3,k^* + 2, Δ^* + 14, 3, k^* + 6, 18}, and if Δ^* ≥ 4 and k^* ≥ 4, then χ^c ≤ Δ^* + 3,k^* + 2. © 2006 Wiley Periodicals, Inc. J Graph Theory     

A new proof of the 6 color theorem

In 1965 Ringel raised a 6 color problem for graphs that can be stated in at least three different forms. In particular, is it possible to color the vertices and faces of every plane graph with 6 colors so that any two adjacent or incident elements are colored differently? This 6 color problem was solved in 1984 by the present author; the proof used about 35 reducible configurations. A shorter new proof is given here using only half as many of reducible configurations. © 1995 John Wiley & Sons, Inc.     

Synchrotron Cerenkov radiation and electron self-polarization

Synchrotron Cerenkov radiation in a medium whose refractive index is given by a polynomial n(y) = 1+c₁+c₂y is examined. The self-polarization effect in this medium is investigated. The optimum values of and n for which the degree of electron self-polarization P may increase and the region of their values for which the degree of self-polarization decreases are found.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 42–47, January, 1990.