We study chemical aging in "Cooee bitumen" using molecular dynamic simulations. This model bitumen is composed of four realistic molecule types: saturated hydrocarbon, resinous oil, resin, and asphaltene. The aging reaction is modelled by the chemical reaction: "2 resins → 1 asphaltene." Molecular dynamic simulations of four bitumen compositions, obtained by a repeated application of the aging ...

Silica scaling potential from geothermal waters puts limits on to what extent the heat from the water can be extracted. Once the waters become over-saturated with respect to amorphous silica, the handling of such waters becomes problematic. Many methods have been proposed to address this problem. One of them is aging the geothermal waste water allowing monomeric silica in excess of amorphous si...

Our recent work showed there existed a composition window for mixed Langmuir monolayers of homopolystyrene (h-PS) and a symmetric diblock copolymer polystyrene-block-poly(2-vinylpyridine) (PSb-P2VP) to form necklace-network structures at the air/water interface. In order to study further the possible mechanism and control the network structure (i.e., surface coverage and nanoaggregate diameter)...

ethylene polymerization was carried out using phillips chromium catalyst based on silica supports such as silicaaerogel, sio2 (grace 643), and titanium modified sio2 (g 643), and the results were compared with othercatalysts based on sio2 (aldrich), sba-15(hex), sba-15(sp) and mcm-41. a combination of tga, dsc, xrd,nitrogen adsorption, sem, icp, ftir and other analyses were used to characterize...

“Silica,” is a term which refers broadly to the mineral compound silicon dioxide (SiO2). Silica can be crystalline or amorphous. Crystalline silica is significantly more hazardous to employees than amorphous silica. In addition to causing the disabling and irreversible lung disease known as silicosis, crystalline silica has been classified as a human carcinogen by the International Agency for R...

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...