Biological uptake of dissolved silicate (DSi) and formation of biogenic silica (BSi) during diatom growth modifies the form of Si carried from the continents to the world ocean. Significant concentrations of BSi, averaging 28.0 pmol L-l, are found in all sizes of rivers. The global contribution of BSi carried by rivers was estimated as 1.05 ? 0.20 Tmol Si year’. Combined with the global mean ri...

This study examined the preparation of high-capacity silica supports containing immobilized protein G. A maximum content of 39 mg protein G/g silica was obtained when using 100 A pore size silica, followed by 33 mg/g for 50 A silica and 9.3-24 mg/g for 300-4000 A silica. The surface coverage of protein G increased with pore size, with a maximum level of 0.037 micromol/m(2) being obtained for 40...

extensive application of silica nanoparticles (snps) in various industrial products has led to the development of silica extraction methodologies out of various waste products. rice husk is an agricultural waste with a high content of amorphous silica. however, the presence of metal ion impurities and unburned carbon in the rice husk content may present an adverse effect on product color and pu...

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...

background: the main purpose of the current study was to determine the effect of treating helicobacter pylori (hp) infection on seizure frequency in patients with refractory epilepsy. methods: a small sample of adult patients above 18 years of age with a diagnosis of refractory epilepsy was studied at the outpatient epilepsy clinic at shiraz university of medical sciences, from january 2009 thr...

abstract despite sophisticated conventional medical treatment and the continued development and improvement of coronary revascularization modalities in recent years, a significant number of patients still suffer from refractory angina pectoris and cannot be successfully managed. advances in therapeutic options have led to an increase in the average of life expectancy even in such no-option pati...