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We open this special issue of SILICON with a preface and some observations on Biological and Bioactive Silicon Systems by the guest editor of this special issue and the editor-in-chief of the journal SILICON.
Fiber reinforced composites (FRCs) are more and more widely applied in dentistry to substitute for metallic restorations: periodontal splints, fixed partial dentures, endodontic posts, orthodontic appliances, and some other indirect restorations. In general in FRCs, the fiber reinforcement provides the composite structure with better biomechanical performance due to their superior properties in tension...
During valve formation of the siliceous frustules of diatoms, bulk uptake of silicic acid and its subsequent transport through the cell is required before it can be deposited in the silica deposition vesicle (SDV). It has been assumed that transport takes place via silicon transporters (SITs), but if that were the case a control mechanism would have to exist for stabilization of the large amounts...
The generation of siliceous spicules by marine sponges is a highly co-ordinated effort between enzymes and scaffold proteins. A common theme across the glassy sponges is the periodic arrangement of these proteins into a central, axial filament. If science is to mimic the biosilification process, a goal which is highly sought after because it occurs at standard temperatures and pressures, then artificial...
Rice husk ash has been used to prepare amorphous silica bioactive ceramics. Three varieties of silica powders, namely brown ash, white ash and silica gel containing 96.0, 99.8 and 99.9% silica respectively, were used to prepare silica ceramics. The bioactivity and biodegradability properties of these ceramics were evaluated. The formation of crystalline apatite was observed on all the specimens in...
Many enzymes have been identified that can participate in the hydrolysis of alkoxysilanes; each with a different degree of specificity. Our working hypothesis was that the nature of the active site of the enzyme (i.e., the compatibility of binding pockets with the substrate) could have a direct effect on the rate of catalysis. This communication reports our experiments on the relative rates of hydrolysis...
Biopolymers are promising alternatives to synthetic macromolecules for the design of composite materials complying with Green Chemistry principles. In this context, the conditions to associate hydroxypropyl-cellulose and polymethylhydrosiloxane within homogeneous membranes were studied. The stability of these membranes in water and in the presence of a cellulase enzyme were investigated by Thermogravimetric...
Six different samples from borosilicate and phosphate glassy systems have been synthesized. Glass batches were prepared from chemically pure materials and melted in platinum or porcelain crucibles and at temperatures in the range 1,000–1,450 °C for 2-3 h until homogeneity was reached. The prepared specimens were annealed at the appropriate temperatures of 380 or 520 °C for the phosphate and borosilicate...
We close this special issue of SILICON with a personal commentary on Biological and Bioactive Silicon Systems by the editor-in-chief of the journal SILICON and the guest co-editor of this special issue.
The recycling of biogenic silica (bSiO2) produced by diatoms is a vital process sustaining a significant fraction of primary production in the oceans. The efficiency with which bSiO2 dissolves controls the availability of nutrient silicon in the water column, and modulates the export of organic carbon to the deep sea. Environmental conditions during biomineralization (temperature, nutrient availability,...
The sponge protein silicatein is the first enzyme that has been described to form an inorganic polymer (silica) from a monomeric precursor (tetraethoxysilane or orthosilicic acid). The models proposed for silicatein-mediated silica formation are mainly based on the use of synthetic substrates (hydrolytic cleavage of tetraethoxysilane to silanol compounds) or only consider the formation of less reactive...
The self-organization of polyhedral silsesquioxane (POSS) moieties tethered as side groups onto flexible backbones of amorphous siloxanes and poly(1,2-butadiene) was investigated. For comparison, linear oligosiloxanes substituted with POSS units at the chain end (α- or α,ω-functionalization) were examined. The properties of POSS-functionalized materials were studied (SAXS, WAXD, DSC, TGA, and optical...
In this paper, the effect of different tempers and thermal ageing treatments on the hardness characteristics and yield strength of A356.0-type Al-Si-Mg alloy has been studied. The investigations consist of artificial ageing without solution heat treatments (T5), solution heat treated with artificial ageing (T6), interrupted-quenching-ageing (IQA) and step-quenching-ageing (SQA) under artificial ageing...
Efficient low-cost processes for solar-grade Si production are needed to overcome the deficiency in the supply of Si. We have demonstrated a new method for the purification of Si crystal. Low-purity Si powder was dissolved in a Na melt (solvent), and Si grains were crystallized by Na evaporation from the Na-Si solution at 1173 K. Glow discharge mass spectrometry analysis revealed that the concentrations...
A mixed-phase of amorphous (a-Si:H) and ultra nanocrystalline silicon thin films (ultra nc-Si:H) were grown in a low deposition pressure regime (0.10–0.62 Torr) using a very high frequency (60 MHz) plasma enhanced chemical vapor deposition (VHF PECVD) technique. The deposition rate, stress, hydrogen configuration and morphology varying with the deposition pressure were systematically studied. The...
A hydrophilic silane was obtained from the reaction of ethylene carbonate and 3-aminopropyldiethoxymethylsilane. This silane undergoes rearrangement to yield an AB2-type hyperbranched polymer under anhydrous conditions but hydrolyzes and condenses to produce linear siloxanes under acid hydrolysis. The hydrolysis and condensation reactions as a function of time, HCl concentration and water content...
Cerium oxide is one of the most important rare earth elements that is introduced into glass compositions due to its great effects on the optical properties. CeO2 was introduced in Hench’s patented SiO2-Na2O-CaO-P2O5 glasses with different concentrations in order to study its effect on the optical behavior of this glass including optical band gap, transmittance, reflectance and refractive index and...
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