AIM To report the hydration mechanism of white mineral trioxide aggregate (White MTA, Dentsply, Tulsa Dental Products, Tulsa, OK, USA). METHODOLOGY The chemical constitution of white MTA was studied by viewing the powder in polished sections under the scanning electron microscope (SEM). The hydration of both white MTA and white Portland cement (PC) was studied by characterizing cement hydrate...

The Chah-Shaljami polymetal ore deposit contains heavy metal anomalies in various mineralization zones. Geochemical distribution and correlation of elements in surficial soilsindicate that sulfide, sulfate, sulfosalt and silicate mineral occurrences (e.g. Pyrite, chalcopyrite, galena, sphalerite, molybdenite, enargite, hornblend and biotite) in mineralization and stockwork zones resulted in the...

OBJECTIVE Aim of the present study was to evaluate the retreatability and reestablishment of apical patency of two calcium silicate-based sealers, TotalFill BC Sealer (BCS) and mineral trioxide aggregate Fillapex (MTA F), versus AH Plus, when used in combination with Gutta-percha (GP). MATERIALS AND METHODS The canals of 54 single-rooted anterior teeth were instrumented and filled with GP/AH ...

To evaluate the physiological responses of chrysanthemum to silicon spray in non-stress conditions, this study was performed in two separate experiments (at 4 to 5 and 8 to 12-leaf stages) as a factorial randomized completely design with two factors: silicon source (in two levels: sodium silicate and calcium silicate) and the concentration of silicate at five levels (0, 50, 100, 150 and 200 mg ...

Cement is produced by co-grinding clinker, gypsum and other components defined in the Cement Standards like limestone, pozzolans, fly ash and slag. The grinding is usually performed in horizontal ball mills. Gypsum is typically the basic source of sulphates (SO3) in the cement. The effect of gypsum on the cement quality is critical and twofold. It affects two of the main properties of this prod...

The pathway from simple abiotically made organic compounds to the molecular bricks of life, as we know it, is unknown. The most efficient geological abiotic route to organic compounds results from the aqueous dissolution of olivine, a reaction known as serpentinization (Sleep, N.H., et al. (2004) Proc. Natl. Acad. Sci. USA 101, 12818-12822). In addition to molecular hydrogen and a reducing envi...

Estimation of the temperature dependence of natural feldspar weathering in two catchments at different elevations yields an apparent Arrhenius activation energy of 18.4 kcal/mol (77.0 kj/mol), much higher than most laboratory values. This finding supports recent suggestions that hydrolytic weathering of silicate minerals may consume carbonic acid and thereby remove atmospheric carbon dioxide mo...

Si adsorption onto Bacillus subtilis and Fe and Al oxide coated cells of B. subtilis was measured both as a function of pH and of bacterial concentration in suspension in order to gain insight into the mechanism of association between silica and silicate precipitates and bacterial cell walls. All experiments were conducted in undersaturated solutions with respect to silicate mineral phases in o...

Field studies indicate an intensification of mineral weathering with advancement from arbuscular mycorrhizal (AM) to later-evolving ectomycorrhizal (EM) fungal partners of gymnosperm and angiosperm trees. We test the hypothesis that this intensification is driven by increasing photosynthate carbon allocation to mycorrhizal mycelial networks using 14CO2-tracer experiments with representative tre...

Mineral trioxide aggregate (MTA) and Portland cement (PC) are calcium silicate cements. They have similar physicochemical, mechanical and biological properties. The addition of zirconium oxide (ZrO2) to PC provides radiopacity. Silver nanoparticles (AgNPs) may improve some properties of cements. The aim of this study was to evaluate the effect of AgNPs on physicochemical/mechanical properties a...