Experimental results on the formation of molecular hydrogen on amorphous silicate surfaces are presented for the first time and analyzed using a rate equation model. The energy barriers for the relevant diffusion and desorption processes are obtained. They turn out to be significantly higher than those obtained earlier for polycrystalline silicates, demonstrating the importance of grain morphol...

First principles density functional theory calculations are carried out to investigate the scaling trends of band offsets at model silicon/zirconium silicate interfaces. Owing to the d character of zirconium silicate conduction bands, the band gap and band offset are shown to decrease as the zirconium concentration is increased. Since the valence band character of silicates remains unchanged re...

We have calculated the thermal emission spectrum of the dust of comet P/Borrelly (1994l), a short-period comet (Jupiter family), from 3 μm to 14 μm as well as the 10 μm silicate feature in terms of the comet dust model as porous aggregates of interstellar grains. Compared to comet P/Halley dust, the dust grains of P/Borrelly appear to be relatively more processed (more carbonized), less fluffy,...

1 Calcium Silicate Hydrates in cementitious materials 1.1 Sustainability Challenge .... ..................... 1.2 Cement Chemistry Notation A Primer ............ 1.3 Hydration of Portland Cement ...................... 1.3.1 Initial and slow reaction periods . . . . . . . . . . . . . 1.3.2 Nucleation & Growth of C-S-H . . . . . . . . . . . . . 1.3.3 Open Questions in Cement Hydration . . . . . ....

Ab initio Car-Parrinello molecular dynamics simulations were carried out to investigate the melt precursor of a modified phosphosilicate glass with bioactive properties, and to quench the melt to the vitreous state. The properties of the 3000 K liquid were extensively compared with those of the final glass structure. The melt is characterized by a significant fraction of structural defects smal...

The aim of this study was to investigate the effects of solid carriers and processing routes on the properties of amorphous solid dispersions of itraconazole. Three solid carriers with a range of surface properties were studied, (1) a mesoporous silicate, magnesium aluminum silicate (Neusilin US2), (2) a nonporous silicate of corresponding composition (Veegum) and (3) a non-silicate, inorganic ...

Hydrothermally grown crystals of beta-K3NdSi6O15, potassium neodymium silicate, have been studied by single-crystal X-ray methods. Under appropriate conditions, the compound crystallizes in space group Bb2(1)m and has lattice constants a = 14.370 (2), b = 15.518 (2) and c = 14.265 (2) A. There are 30 atom sites in the asymmetric unit of the basic structure. With eight formula units per unit cel...

[1] Knowledge about the properties of silicate melts is needed by volcanologists and petrologists to evaluate the dynamics of volcanic eruptions and magmatic processes. These properties include the solubility and diffusivity of volatile components in silicate melts, silicate melt viscosity, and the fragmentation condition. Data and models of each property are reviewed and assessed. For rhyoliti...

Accurate control of groundwater pH is of critical importance for in situ biological treatment of chlorinated solvents. This study evaluated a novel approach for buffering subsurface pH that relies on the use of silicate minerals as a long-term source of alkalinity. A screening methodology based on thermodynamic considerations and numerical simulations was developed to rank silicate minerals acc...