objective: silicon is an effective element in bone biomineralization; hence si-substituted hydroxyapatite can be a relevant bioceramic as bone materials substitution. materials and methods: stoichiometric hydroxyapatite (ha) and si-substituted hydroxyapatite (si-ha) with different contents of si substitution were synthesized successfully by a hydrothermal method using ca(no3)2, (nh4)3po4 or (n...

the b3lyp/6-31++g** density functional calculations were used to obtain minimum geometries and interaction energies between the molecular hydrogen and nanostructures of fullerenes, c20 (cage), c20 (bowl), c19si (bowl, penta), c19si (bowl, hexa). the h2 molecule is set as adsorbed in the distance of 3å at vertical position from surface above the pentagonal and hexagonal sites of nanostructures. ...

geopolymer cement (inorganic polymeric binder) based on natural pozzolan are investigated. SiOof activator and total molar ratios of Nacomposition exhibiting the highest 28-day compressive strength. Mixtures exhibiting the highest compressive strength were studied for their molecular structure using laboratory technique of Fourier transform infrared spectroscopy.Results obtained confirm that ch...

The substitution reaction of pure, silicon doped and germanium doped fullerenes and tetryl were evaluated computationally at two configurations, in this study. For this purpose, all of the studied structures were optimized geometrically and then IR and NBO calculations were performed on them in the temperature range of 300-400 K at 10˚ intervals. The obtained negative values of Gibbs free energ...

In this study, the radial distribution and gravimetric storage capacities of hydrogen on coronene (C24H12) and its Si substituted forms, C24H12, C24-nSinH12 (n= 4-24), have been investigated at 298 K and 0.1 MPa (standard situation) using (N,V,T) Monte Carlo simulation by Lennard-Jones (LJ) 12-6 potential. The results show that the increase of number of silicon substitution doesn’t have any eff...

In this study, the radial distribution and gravimetric storage capacities of hydrogen on coronene (C24H12) and its Si substituted forms, C24H12, C24-nSinH12 (n= 4-24), have been investigated at 298 K and 0.1 MPa (standard situation) using (N,V,T) Monte Carlo simulation by Lennard-Jones (LJ) 12-6 potential. The results show that the increase of number of silicon substitution doesn’t have any eff...

in this study, the radial distribution and gravimetric storage capacities of hydrogen on coronene (c24h12) and its si substituted forms, c24h12, c24-nsinh12 (n= 4-24), have been investigated at 298 k and 0.1 mpa (standard situation) using (n,v,t) monte carlo simulation by lennard-jones (lj) 12-6 potential. the results show that the increase of number of silicon substitution doesn’t have any eff...

Cementite precipitation from austenite in steels can be suppressed by alloying with silicon. There are, however, no validated thermodynamic data to enable phase equilibria to be estimated when silicon is present in cementite. The formation energies of Fe3C, (Fe11Si 4c Fe)C4 and (Fe11Si 8d Fe)C4 have therefore been estimated using firstprinciples calculations based on the total-energy all-electr...

The Cp*Si(+) cation acts as a stoichiometric source of silicon in the reaction with the disilenide Tip(2)Si=Si(Tip)Li (Tip = 2,4,6-(i)Pr(3)C(6)H(2)) affording known neutral unsaturated silicon clusters. It thereby provides a conceptually different approach to this novel class of compounds. The proposed mechanism involves a Cp*-substituted cyclotrisilene in which Cp*(-) acts as a leaving group u...