The recent Spitzer detections of the 9.7μm Si–O silicate emission in type 1 active galactic nuclei (AGN) provide support for the AGN unification scheme. The properties of the silicate dust are of key importance to understand the physical, chemical and evolutionary properties of the obscuring dusty torus around the AGN. Compared to that of the Galactic interstellar medium (ISM), the 10μm silicat...

Interstellar extinction curve E(λ-V)/E(B-V) vs 1/λ is evaluated in the spectral range 3.4 μm and 0.1 μm using the extinction efficiencies of the porous silicate and graphite grains. The extinction efficiencies of the porous silicate and graphite grains are computed using the discrete dipole approximation (DDA). The model curves are compared with the average observed interstellar extinction curv...

A novel calcium silicate filler can be made from fly ash. This new filler, known as fly ash based calcium silicate (FACS), has a highly porous surface structure, high brightness (91% ISO), low bulk density (0.31 g/cm 3 ), and high specific surface area (121 m 2 /g). In this paper, its potential application as a paper filler was studied and its effect on drainage, retention, and paper properties...

Oxynitride glasses are found as grain boundary phases in silicon nitride ceramics. They are effectively alumino-silicate glasses in which nitrogen substitutes for oxygen in the glass network, and this causes increases in glass transition and softening temperatures, viscosities (by two to three orders of magnitude), elastic moduli and microhardness. Calcium silicate-based glasses containing fluo...

A novel hierarchically ordered porous vanado-silicate nanocomposite with interconnecting macroporous windows and meso-microporous walls containing well dispersed vanadyl species has been fabricated and used as a heterogeneous catalyst for the oxidation of a bulky organic molecule, namely cyclooctene.

Wemodel the infrared (IR) emission from the double-ring disk of HD 141569A, using a porous dust model that was previously shown to be successful in reproducing the spectral energy distributions (SEDs) of the disks around Pictoris and HR 4796A. The dust consists of either unaltered or highly processed interstellar materials and vacuum with a volume fraction of 90%. Together with a population of ...

High-porosity magnesia phosphate paste (HPMPP) was prepared via the pre-foaming method. In the pre-foaming method, sintering treatment was not required. The bulk density and maximum compressive strength of the HPMPP prepared according to the ratio of water to solids (W/So) of 0.32 reached 464.00 ± 5.00 Kg/m(3) and 0.30 ± 0.05 MPa, respectively. The compressive strength increased with the increa...

A mathematical model is developed that captures the transport of liquid water in hardened concrete, as well as the chemical reactions that occur between the imbibed water and the residual calcium silicate compounds residing in the porous concrete matrix. The main hypothesis in this model is that the reaction product – calcium silicate hydrate gel – clogs the pores within the concrete thereby hi...

Objective(s): Bioactive silicate ceramics have favorable features for applying as off-the-shelf bone and artificial tissue. Calcium silicate can enhance the generation of an immediate bond with host bone without an intervening rough surface in the bone layer. However, the silicate bioceramics have some drawback regarding their mechanical properties and chemical stabilities. Materials and Method...

The flattening of the 10 µm silicate emission feature observed in the spectra of T Tauri and Herbig Ae/Be stars is usually interpreted as an indicator of grain growth. We show in this paper that a similar behaviour of the feature shape occurs when the porosity of composite grains varies. We modelled the fluffy aggregates with inclusions of different sizes with multi-layered spheres consisting o...