a new polymorph crystalline silica composition having uniform pore dimensions were synthesized by calcining a crystalline hydrated alkyl-ammonium silicate. the pore dimensions approximately were 6 angstrom for silicalite-1 and 11 angstrom for silicalite-2 units. the silicalite-1 was prepared hydrothermally at a ph of about 10 from a reaction mixture consist of water, amorphous silica and a quat...

abstract self compacting concrete (scc) is a new construction material in the world. the aim of this research is to construct self compacting concrete with high compressive strength using combination of nano silica and micro silica. for this purpose, nano silica, micro silica, portland cement type 2, superplasticizer (sp), and gravel and sand have been used. three different groups of samples wi...

The authors’ research group has previously developed a novel method for the fabrication of silica/perfluoropolymer nanocomposites, wherein nano-sized silica particles without surface modification were dispersed uniformly through breakdown of loosely packed agglomerates of silica nanoparticles with low fracture strength in a polymer melt during direct melt-compounding. The method consists of two...

Exposure to respirable crystalline silica is a hazard common to many industries in Alberta but particularly so in abrasive blasting. Alberta occupational health and safety legislation requires the consideration of silica substitutes when conducting abrasive blasting, where reasonably practicable. In this study, exposure to crystalline silica during abrasive blasting was evaluated when both sili...

Silica-based materials with favourable biocompatibility are generally considered as excellent candidates for applications in biomedical fields. However, previous researches mainly focused on the safety of silica-based materials, their effects on osteogenic differentiation of human mesenchymal stem cells (hMSCs) still need further investigations. In this study, core-shell fluorescent silica nano...

alteration of ophiolitic ultramafic rocks, formation of listwaenite and associated mineralization are interesting phenomena of metallogeny of khoy ophiolite. it seems that the hydrothermal circulations responsible for mercury mineralization were derived from geothermal systems caused by intermediate to acidic magmatism in neogene-pleistocene time. reactivation of brecciated serpentinite with hy...

Freestanding and well-ordered two-dimensional (2D) silica monolayers with tetrahedral (T-silica) and octahedral (O-silica) building blocks are found to be stable by first-principles calculations. T-silica is formed by corner-sharing SiO4 tetrahedrons in a rectangular network, and O-silica consists of edge-sharing SiO6 octahedrons. Moreover, the insulating O-silica is the strongest silica monola...

The study of preparing silica/rubber composites used in tires with low rolling resistance in an energy-saving method is fast-growing. In this study, a novel strategy is proposed, in which silica was modified by combing alcohol polyoxyethylene ether (AEO) and 3-mercaptopropyltriethoxysilane (K-MEPTS) for preparing silica/natural rubber (NR) master batches. A thermal gravimetric analyzer and Rama...

BACKGROUND Silicon dioxide composites have been found to enhance the mechanical properties of scaffolds and to support growth of human adipose tissue-derived stem cells (hADSCs) both in vitro and in vivo. Silica (silicon dioxide alone) exists as differently sized particles when suspended in culture medium, but it is not clear whether particle size influences the beneficial effect of silicon dio...