this study is focused on synthesis of nano-colloidal silica via alkaline water glass solution. sodium ions of water glass were removed by cation exchanging in a resin column to obtain the silicic acid which was titrated to the solution of sodium silicate. concentration of the colloidal silica and ph value of the solutions were controlled using different concentrations of alkaline sodium silicat...

Theoretical approaches to the thermochemistry of silicate anions have so far focused on gas-phase molecular orbital and density functional theory (DFT) calculations. These calculations predict that in the presence of hydroxide ligands the most stable singly charged anion of the silicic acid H4SiO4 is the five-coordinated anion H5SiO5 . However, experimental evidence from in situ nuclear magneti...

Two world ocean data sets, GEOSECS and NODC, were analyzed for patterns in the nitrate versus silicic acid regression relation. Significant regional nitrate or silicic acid excesses (i.e. amount of one of these plant nutrients remaining in the water after the other is no longer measurable) tend to occur in some areas of upwelling, shallow sills, deep convection or high rainfall/river outflow. T...

The competitive adsorption of arsenate and arsenite with silicic acid at the ferrihydrite-water interface was investigated over a wide pH range using batch sorption experiments, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, extended X-ray absorption fine structure (EXAFS) spectroscopy, and density functional theory (DFT) modeling. Batch sorption results indica...

Tissue cultures of fibrogenic cells which form collagen in vitro are a valuable model for quantitative study of the mechanism of this cellular function as well as of problems relevant to pneumoconiosis. We have found a pronounced stimulation of collagen formation in tissue cultures of embryonic chicken lung by silicic acid in a concentration of 0-005M in the medium. Higher concentrations (0 01 ...

Reconstruction of nutrient concentrations in the deep Southern Ocean has produced conflicting results. The cadmium/calcium (Cd/Ca) data set suggests little change in nutrient concentrations during the last glacial period, whereas the carbon isotope data set suggests that nutrient concentrations were higher. We determined the silicon isotope composition of sponge spicules from the Atlantic and P...

Primary production and uptake rates of ammonium, nitrate and silicic acid were measured during the 1996 spring bloom in the Oslofjord, southern Norway, using isotope methodology (14C, 15N and 32Si). Chlorophyll a (chl a) standing stock peaked at 38 mg chl a m–3. Diatoms, especially Thalassiosira nordenskioeldii, dominated the plankton community. The diatom bloom followed a sigmoid growth patter...

Silicic acid increased numbers of both aerobic and facultatively anaerobic bacteria in ultrapure water incubated under strict oligotrophic conditions; soil extracts acted as the bacterial inoculum. The results are discussed in relation to the possibility that silicic acid, produced by the hydrolysis of silicates on the early Earth, could have stimulated the growth of the first bacterium, thereb...

The adsorption of serum lipoproteins onto an insoluble matrix of colloidal silicic acid results in the removal of nonspecific inhibitors of rubella virus hemagglutinin. The procedure can be performed in 15 min at room temperature. Comparative studies using both the dextran sulfate-CaCl2 and heparin-MnCl2 methods for removal of inhibitors demonstrated that the colloidal silicic acid procedure yi...

This paper focuses on the effects of biological and synthetic polymers on the formation of amorphous silica. A concise review of relevant literature related to biosilicification is presented. The importance of synergies between polyelectrolytes on the inhibition of silicic acid condensation is discussed. A specific example of a zwitterionic polymer phosphonomethylated chitosan (PCH) is further ...