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...

various concentrations of copper were embedded into silica matrix to xerogel forms using copper source cu(no3)2∙3h2o. the xerogel samples were prepared by hydrolysis and condensation of tetraethyl ortho-silicate (teos) with determination of new molar ratio of the components by the sol-gel method. after ambient drying, the xerogel samples were heated from 60 to 1000˚c at a slow heating rate (50°...

proteases are important enzymes that their role in various industries is undeniable. however, keeping enzymes stable during its activity in harsh conditions is so important. in this study, protease enzyme was immobilized on the porous silica particles and its stability in different temperatures and phs was evaluated. first silica particles were aminated by 3-aminopropyltriethoxysilane then the ...

in this study, alkaline colloidal silica was prepared by titration of an alkaline solution such as sodium silicate with silicic acid in constant range of ph  .this constant range of ph was achieved by using concentrated soduim silicate solutions as ph adjusting solutions during titration.the sodium silicate solutions  having a variety of concentrations were passed  through ion-exchange resin to...

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Doped and undoped silica slabs were fabricated through the use of the sol-gel technique. Extended UV transmission was observed for HCl-catalyzed sol-gel silica. Under transverse pumping with a XeCl laser, narrow-linewidth (<0.9-nm) laser oscillation from silica slabs doped with coumarin 460 (C460) was achieved in a grating-resonator cavity configured in the grazing-indicence geometry. Tuning of...

The effect of colloidal silica fillers on the cross-linking behavior of a model UV-curable polymer system (thiol-ene) is studied using in situ rheology and real-time FTIR spectroscopy. The validity of the Winter-Chambon criterion (convergence of the loss tangents at the gel point) is examined for the cross-linking of these filled polymers, some of which are strongly flocculated dispersions (phy...

The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene–poly(ethylene/butylene)–polystyrene (PS–PEB–PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order to evaluate the influence of the compatibility between gel and filler. Time-resolved SANS and small-a...

As part of a general study of the interaction between gases and solids in the laboratory of Alfred Magnus (Fig. 1) at the University of Frankfurt, Magnus and Grähling (2) reported the adsorption of ozone on silica gel in 1929. These measurements were complicated by the thermal instability of ozone, which, as shown by Magnus and Grähling, was further catalyzed by silica gel. A second problem was...

Silica aerogels prepared by the sol-gel process are often used as solid desiccants in enthalpy wheels for dehumidifying ventilation air in air-conditioning systems. These hygroscopic materials have good moisture adsorption and desorption characteristics due to their porous structure. The current study is focused on the evaluation of the mass diffusivity of solid silica aerogels and silica aerog...