Materials Literature
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We report a route to the fabrication of unique flowerlike polymer superstructures with uniform petals at the nanoscale. In this method, polymer/zeolite composite is first prepared by loading corresponding monomer and initiator into the channels of the host zeolite with the aid of supercritical (SC) CO2, followed by th…
A novel molecular based magnet of three-dimensional (3-D) cyanide-bridged bimetallic assembly, [{(323)Ni}3{FeIII(CN)6}2]n x 2nH2O where 323 = N,N'-bis(3-aminopropyl) ethylenediamine, was synthesized and structurally characterized. The compound crystallizes in the orthorhombic space group Pbca with a = 15.6560 A, b = 1…
Transient-state kinetics by its inherent nature can potentially provide more directly observed detailed resolution of discrete events in the mechanistic time courses of enzyme-catalyzed reactions than its more widely used steady-state counterpart. The use of the transient-state approach, however, has been severely lim…
Reverse Monte Carlo (RMC) modelling is now widely used for obtaining structural models of amorphous materials that are in quantitative agreement with available experimental structure data. In the case of ion conducting glasses it has been possible to determine the distribution and local environment of the mobile ions.…
We report a study of the displacive phase transition in SrTiO 3 using neutron total scattering with analysis by the reverse Monte Carlo method. The resultant configurations have been analysed in terms of bond distance and bond angle distribution functions, and using recently developed methods based on geometric algebr…
[reaction: see text] Four kinds of bispyridinio-appended gamma-cyclodextrin (gamma-CD) were prepared to make a molecular flask for controlling the stereoselectivity of photocyclodimerization of 2-anthracenecarboxylate. When the photocyclodimerization of 2-anthracenecarboxylate was carried out in the presence of A,E-bi…
Liquid anhydrous sulfuric acid forms molecular "shells" wrapped around single-walled carbon nanotubes (SWNTs). Temperature-dependent X-ray scattering from aligned acid-swollen fibers shows that crystallization of the bulklike acid surrounding the structured shells is templated by the aligned SWNTs, while the structure…
We have studied the compatibility of various catalysts for ethylene and ethanol chemical vapor deposition (CVD) syntheses of single-walled carbon nanotubes (SWNTs) on Si substrates. A strong selectivity between the catalyst elemental species and carbon source was found; SWNT yield for Fe (Co) catalysts was much higher…
Oxidized individual single-walled carbon nanotubes and amine polymers have been assembled into 11-32-nm-thick well-ordered conductive films. The films show highly anisotropic electrical conductivity, which is dominated by the nanotubes in the horizontal plane and by polymer-mediated tunneling in the vertical direction…
The peripheral functionalization of amine-terminated fourth-generation poly(amidoamine) (PAMAM) with thiophene dendrons and the preparation of dendrimer-encapsulated metal nanoparticles are described. Interesting nanoparticle stabilization and energy-transfer properties were observed with these hybrid materials. The s…
The reverse Monte Carlo (RMC) modelling method, although initially developed for interpreting structural data from liquids and amorphous materials, has been extensively applied to similar data from crystalline systems. This has been especially beneficial for materials which display a large amount of disorder. The work…
Here, we report the role of crystal structure and crystal size on the photoluminescence properties of Ce3+ ions in Y2SiO5 nanocrystals. The emission at 430 nm (5d1 --> 4f1) and lifetime of the excited state of Ce3+ ion doped Y2SiO5 nanocrystals are found to be sensitive to the crystal structure, crystal size, and dopa…
A model of silica glass consisting of a fully connected corner-sharing network of SiO 4 tetrahedra is refined using neutron diffraction data and reverse Monte Carlo modelling. This model is then used to investigate optimal inter-tetrahedral Si–O–Si bond angle distributions. The distribution which is most consistent wi…
The local structure of nanoparticles can be determined by a direct interpretation of the first peaks observed in the radial distribution function obtained from powder diffraction data measured to high Q values. Single peak fits to these maxima yield the mean distances and width of the distribution in the first few nei…
The synthesis of porous aminopropylsilsesquioxane (APSS) has been achieved with 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM(+)PF(6-)) ionic liquid (IL) as a template solvent by a nonhydrolytic sol-gel method of 3-aminopropyltrimethoxysilane under mild temperature. By the alteration of the amount of IL or the…
Reaction of equimolar amounts of AgCN and PCy3 gave the polymer [(Cy3P)Ag(NCAgCN)]infinity (1), whereas employment of excess PCy3 yielded the discrete compound [(Cy3P)2Ag(NCAgCN)] (2). Reacting bis(dicyclohexylphosphino)methane (dcpm) with AgCN in 1:1 and 1:2 molar ratios gave two crystalline forms, namely [Ag2(mu-dcp…
The total structure factors, S ( Q ), obtained from high-energy x-ray and neutron diffraction measurements on vitreous SiO 2 (v-SiO 2 ) and vitreous GeO 2 (v-GeO 2 ) have been analysed by the reverse Monte Carlo (RMC) modelling technique to generate a three-dimensional structural model. The bond angle distributions an…
A variety of novel opaque, white polymers ranging from rubbery materials to tough and rigid plastics have been prepared by the thermal polymerization at 85-160 degrees C of varying amounts of 87% conjugated linseed oil, styrene, and divinylbenzene. Gelation of the reactants typically occurs at temperatures higher than…
Earlier studies have shown that the most stable structures for (ZnS)n clusters with n = 10-47 are hollow polyhedral clusters ("bubbles"). We report a detailed study of larger clusters, where n = 50, 60, 70, and 80, for which onionlike or "double bubble" structures are predicted. We report calculations of the vibration…
We propose a one-step interface reaction for the direct synthesis of hexagonally arranged spherical silver nanoparticles under microwave-assisted solvothermal conditions without the requirement of the presynthesis of uniform silver nanoparticles or special precursors and the technique of size-selective precipitation.…