379 Biominerals are the inorganic phases of minerals found in biological systems, which are distributed from microorganisms to the highest animals and plants (Mann et al. 1989, Simkiss and Wilbur 1989, Weiner and Lowenstam 1989, Mann 2001). Although minerals composed of calcium predominate, biominerals of barium, strontium, iron, and silica are also well known. Biominerals generally occur as ox...

The possible combination of specific physicochemical properties operating at unique sites of action within cells and tissues has led to considerable uncertainty surrounding nanomaterial toxic potential. We have investigated the importance of proteins adsorbed onto the surface of two distinct classes of nanomaterials (single-walled carbon nanotubes [SWCNTs]; 10-nm amorphous silica) in guiding na...

Silica biomineralization associated with unicellular microbes (Cyanidium caldarium) living in strongly acidic hot springs were observed by electron microscopy. The unicellular microbes form green biomats undergoing photosynthesis in Kamuiwakka Falls, Hokkaido, Japan. The hot-spring water is strongly acidic, with pH less than 2, and rich in S. Electron microscopy observations showed that the cel...

The mechanisms by which amorphous silica dissolves have proven elusive because noncrystalline materials lack the structural order that allows them to be studied by the classical terrace, ledge, kink-based models applied to crystals. This would seem to imply amorphous phases have surfaces that are disordered at an atomic scale so that the transfer of SiO(4) tetrahedra to solution always leaves t...

A robust and accurate dissociative potential that reproduces the structural and dynamic properties of bulk and nanoconfined water, and proton transport similar to ab initio calculations in bulk water, is used for reactive molecular dynamics simulations of the proton dynamics at the silica/water interface. The simulations are used to evaluate the lifetimes of protonated sites at the interfaces o...

Silica, or silicon dioxide (SiO2), is a group IV metal oxide, which naturally occurs in both crystalline and amorphous forms (i.e. polymorphic; NTP, 2005). The various forms of crystalline silica are: α-quartz, β-quartz, α-tridymite, β-tridymite, α-cristobalite, β-cristobalite, keatite, coesite, stishovite, and moganite (NIOSH, 2002). The most abundant form of silica is α-quartz, and the term q...

Least toxic physical and chemical solutions are often part of an IPM program. Various forms of amorphous silica are commonly used as part of this strategy. Diatomaceous earth and silica gel are used in various physical formulations with or without added pesticide. The type of silica and the formulation depend on the target pest. In this issue advantages and disadvantages of diatomaceous earth a...

Mid-infrared spectra of a few T Tauri stars (TTS) taken with the Infrared Spectrograph on board the Spitzer Space Telescope show prominent narrow emission features indicating silica (crystalline silicon dioxide). Silica is not a major constituent of the interstellar medium; therefore, any silica present in the circumstellar protoplanetary disks of TTS must be largely the result of processing of...