Equations have been derived and computations carried out for the demineralization rates of tooth enamel employing the “Fluorapatite” model. The model assumes that when hydroxyapatite is exposed to a low fluoride concentration, a layer of fluorapatite is formed around the apatite crystal and this fluorapatite is assumed to be the thermodynamic governing phase during dissolution. The demineralixa...

Previous studies have demonstrated that both the glucosamine and glucuronic acid moieties of hyaluronic acid synthesized by Group A streptococci are derived from glucose without previous scission of the glucose molecule (1). Shortly after the discovery by Caputto et al. (2) of the role of uridine diphosphoglucose in the epimerization of glucose, Park (3-5) noted the accumulation of uridine nucl...

Nanoparticulate composites of hydroxyapatite (HAp) and chitosan were synthesized by ultrasound-assisted sequential precipitation and characterized for their microstructure at the atomic scale, surface charge, drug release properties, and combined antibacterial and osteogenic response. Crystallinity of HAp nanoparticles was reduced because of the interference of the surface layers of chitosan wi...

The mechanism by which a chemical agent binds to proteins is of considerable interest, particularly since a large number of compounds with carcinogenic activity have been found to bind firmly to cellular proteins at the site of tumor formation. Included in this category are the polycyclic aromatic hydrocarbons (l), the aminoazo dyes (2), N-(2.fluorenyl)acetamide (3), and the nitrogen and the su...

Macroand micro-perthitic microclines from pegmatites from Perth, Ontario (Wards catalogue 46 E 0510) and Keystone, South Dakota (Wards 46 E 5125) have been studied using light and electron microscopy. A sample of the type perthite from Perth, Ontario (Hunterian Museum, Glasgow, M2361) was compared using light microscopy. It differs in bulk composition and microtexture from the Wards sample. The...

Our study of the Seti River in far western Nepal shows that the solute chemistry of the river and its tributaries is strongly controlled by geology. The Seti flows through four distinct terranes, starting with the Tethyan sedimentary series (TSS) and Greater Himalayan series (GHS). TSS/GHS waters display Sr/Sr ratios of ,0.73 and high Sr and Ca, consistent with the composition of limestone and ...

The glycosylphosphatidylinositol (GPI)-anchored membrane protein urokinase plasminogen activator-receptor (uPA-R; CD87) is one of the key molecules involved in migration of leukocytes and tumor cells. uPA bound to uPA-R provides the cell proteolytic potential used for degradation of extracellular matrix. uPA-R is also involved in induction of cell adhesion and chemotaxis. Here, we provide a mol...

Young basalts from Kilauea Volcano, Hawai'i, frequently feature opaque surface coatings, 1–80 μm thick, composed of amorphous silica and Fe-Ti oxides. These coatings are the product of interaction of the basaltic surface with volcanically-derived acidic fluids. Previous workers have identified these coatings in a variety of contexts on Hawai'i, but the timescales of coating development, coating...

The magnetites and sulfides located in the rims of carbonate globules in the Martian meteorite ALH84001 have been claimed as evidence of past life on Mars. Here, we consider the possibility that the rims were formed by dissolution and reprecipitation of the primary carbonate by the action of water. To estimate the rate of these solution-precipitation reactions a kinetic model of magnesite-sider...

BACKGROUND Calcium phosphate manufactured samples, prepared with hydroxyapatite, are used as either spacers or fillers in orthopedic surgery, but these implants have never been used under conditions of mechanical stress. Similar conditions also apply with cements. Many authors have postulated that cements are a useful substitute material when implanted in vivo. The aim of this research is to de...