The colloidal stability, phase behavior, and solubility of silica nanoparticles (3-10 nm) that are formed in basic solutions of monovalent cations (primarily tetrapropylammonium) are investigated using a combination of chemical equilibria and electrostatic models. The free-energy gain associated with the formation of an electric double layer surrounding the nanoparticle was obtained by solving ...

Silica-supported molybdenum surface complexes were prepared by the reaction between (N=)Mo(OtBu)3 and silica via displacement of the tert-butoxy ligands for siloxyls from the silica surface. The structure of the surface molybdenum complexes was well defined by in-situ FT-IR, elemental analysis, H NMR and C CP/MAS NMR techniques. The surface complexes could undergo alcoholysis reaction with CD3O...

BACKGROUND Tobacco smoke is a toxic gas-phase cocktail consisting of a broad range of organics, and free radical intermediates. The formation of smoke from a burning cigarette depends on a series of mechanisms, including generation of products by pyrolysis and combustion, aerosol formation, and physical mass transfer processes. METHODS The current study simulates the deposition of particulate...

Changes in the optical absorption and the formation of point defects in three types of synthetic SiO2 glasses, wet ~OH content; 120 ppm!, dry ~OH content ,1 ppm!, and fluorine ~F!-doped ~;1 mol %! SiO2 glasses, by irradiation with fluorine dimer (F2) excimer laser light pulses (;8 mJ/cm / pulse33.6310 pulses) were examined by various spectroscopic methods. Intense optical absorptions were induc...

Free-radical polymerization inside mesoporous silica has been investigated in order to open a route to functional polymer-silica composite materials with well-defined mesoporosity. Various vinyl monomers, such as styrene, chloromethyl styrene, 2-hydroxyethyl methacrylate, and methacrylic acid, were polymerized after impregnation into mesoporous silicas with various structures, which were synthe...

A simple thermal oxidation-etching process was developed to translate vertical silicon nanowire arrays into silica nanotube arrays. The obtained nanotubes perfectly retain the orientation of original silicon nanowire arrays. The inner tube diameter ranges from 10 to 200 nm. High-temperature oxidation produces relative thick, rigid, and pinhole-free walls that are made of condensed silica. This ...

in this article, hybrid organic-inorganic materials were prepared by free radical copolymerization of 2-hydroxyethyl methacrylate (hema) and 3-methacryloxy-propyltrimethoxysilane (mptms) via sol-gel process. the methoxysilane-containing copolymer precursors were synthesized at different compositions. these copolymer precursors were then hydrolyzed and condensed to produce phema-sio2 nanocomposi...

Encapsulation of glycosylated porphyrins in silica nanoparticles enhanced the efficacy cancer photodynamic therapy compared with free porphyrins.

Perchloric acid adsorbed on silica gel efficiently catalyses acetylation of structurally diverse phenols, alcohols, thiols, and amines under solvent free conditions.

Alumina or silica gel are used as catalysts for a solvent-free oxidation of benzoins to the corresponding benzils. These catalysts are easily recovered after completion of the reactions, which are carried out either by heating in a sand bath or using microwave irradiation. Comparison of the results obtained with both catalysts indicates that all the reactants examined were oxidized faster on al...