Materials Literature
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A new strategy, dendrimer bridging, is developed for simultaneous formation and functionalization of biocompatible and bioaccessible semiconductor box nanocrystals a dendron box around each colloidal semiconductor nanocrystal. CdSe plain core or CdSe/CdS core/shell nanocrystals coated by a monolayer of organic dendron…
A novel sol-gel route to c-axis orientated undoped and Co, Fe, Mn and V doped ZnO films is reported. Sols were prepared from a hydrated zinc acetate precursor and dimethyl formamide (DMF) solvent. Films were spin-coated on to hydrophilic sapphire substrates then dried, annealed and post-annealed, producing almost pure…
A hybrid scheme between large-scale electronic structure calculations is developed and applied to nanocrystalline silicon with more than 10$^5$ atoms. Dynamical fracture processes are simulated under external loads in the [001] direction. We shows that the fracture propagates anisotropically on the (001) plane and rec…
The effects of crystal size and crystal phase on the upconverted emission of Er3+ in ZrO2 oxide nanocrystals are reported. Green (550 nm) and red (670 nm) upconversion emission were observed at room temperature from the S43/2 and F49/2 levels of Er3+:ZrO2 nanocrystals. It is found that at 850 mW of cw excitation power…
Light converter: The emission of visible light (Vis) upon excitation in the near-infrared (NIR) has been observed for the first time in a transparent solution. Excitation at 975 nm (marked red in the picture) of optically clear colloidal solutions of LuPO4:Yb3+, Tm3+, and YbPO4:Er3+ nanocrystals in chloroform leads to…
Large cavities (≈10–12.3 nm) of cubic (Fm-3m) mesoporous silica without intergrowth are synthesized in the presence of block copolymer templates. The entrance sizes of these cavities can be adjusted in the range of ≈4–9 nm as confirmed by nitrogen sorption studies and an examination of the negative gold replicas. The…
Abstract For Abstract see ChemInform Abstract in Full Text.
We have presented a model of the electron-trapping process at edge-sharing ${\mathrm{SiO}}_{4}$ units that are supposed to exist as structural defects especially at the surface of silica-based materials. It has been shown that the edge-sharing ${\mathrm{SiO}}_{4}$ dimer can trap an electron, giving rise to a paramagne…
Abstract For Abstract see ChemInform Abstract in Full Text.
Physical adsorption of SO 2 on exfoliated graphite is studied using classical adsorption volumetry and Monte Carlo computer simulations. The experimental isotherms have been obtained in a wide temperature range to determine the critical temperature for the completion of several layers. The computer simulations are in…
Ultrathin SiO 2 films in the range of 2−50-nm thickness were readily fabricated from inexpensive sodium silicate as starting material by its alternate adsorption with cationic polymer and subsequent treatment with O 2 plasma and calcination. Film thickness can be controlled by adjusting the number of adsorption cycles…
Abstract Plastomers are new alternatives that provide a higher impact strength in polypropylene synthesized by conventional methods. This study presents an analysis of the structure and thermal characterization of two sets of polypropylene/plastomer blends. The difference between the two polypropylene samples is their…
Nitrogen physical adsorption on carbon nanotubes bundles is studied with grand canonical ensemble Monte Carlo computer simulations in a wide temperature range. The results are compared with experimental data obtained in our laboratory and with that published in the literature. The characteristics of the sample employe…
Carbon nanotube (CNT) based composite materials were obtained by covering the surface of multiwalled carbon nanotubes (MWCNTs) with alumina. The coverage material was prepared by either thermal or chemical decomposition of aluminum sources, such as aluminum trichloride (AlCl 3 ) and aluminum isopropoxide (AlIP). To va…
Abstract A technique was developed for preparing poly(dimethylsiloxane) nanocomposites having unusually high transparencies as quantitatively judged by ultraviolet–visible spectroscopy. The method was the in situ generation of silica particles by a two‐step sol–gel procedure in which the required water of hydrolysis w…
A series of arylamino- and alkylamino-substituted diphenylporphyrins and tetraphenylporphyrins were efficiently synthesized by reactions of brominated porphyrin precursors with amines via palladium-catalyzed amination. The multiple amination reactions are general and suitable for a variety of amines, affording the des…
We have studied nanocrystalline metastable $P6/mmm$ ${\mathrm{Sm}(\mathrm{F}\mathrm{e},\mathrm{S}\mathrm{i})}_{9}$ by means of x-ray diffraction, M\"ossbauer spectroscopy coupled with Curie temperature and magnetization measurements. The structural transformation towards equilibrium $R3\ifmmode\bar\else\textasciimacro…
Ion beam deposition of carbon films was studied by molecular-dynamics simulations. Using an analytic hydrocarbon potential of Brenner with an increased C-C interaction cutoff value, deposition of films with a thickness of up to 10 nm was simulated for ion energies ${E}_{\mathrm{ion}}=10\ensuremath{-}80\mathrm{eV},$ an…
Abstract Time‐resolved real‐space observations of morphology and pattern formation resulting from crystallization of ultrathin films of low‐molecular‐weight poly(ethylene oxide) (PEO) or diblock copolymers containing PEO shed light on the mechanisms of how polymer crystals are formed. We used simple but restricted geo…
The thermodynamic stabilities of the Gd(III) complexes of five hexadentate ligands, which incorporate the 2,3-dihydroxyterephthalamide and 2,3-hydroxypyridonate chelating moieties, have been determined by potentiometric and spectrophotometric titration. The ligands were chosen to span a range of basicities while maint…