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[Dental material testing; contribution to testing standards of silicate-cements].
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[Bacteria destroyed by aluminum silicate].
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[Ranitidine, cimetidine and magnesium silicate in the prevention of aspiration pneumonia].
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Silicon dioxide calculi in humans in the absence of silicate antacid medication.
The occurrence of silicon dioxide in human urinary calculi is more common than generally believed. During a 3 year study we have analyzed about 750 human urinary calculi using the scanning electron microscope and x-ray crystallographic methods. Silicon dioxide of the alpha quartz variety was found to be the principal constituent in calculi from 5 male patients. Some of the patients were recurrent stone formers and 1 patient has previously produced a silicon dioxide calculus. In none of the 5 cases was there any history of gastric disorders or of any ingestion of antacids in the form of magnesium trisilicate. Some of the silica particles have a morphology typical of glacial sand.
[Sodium silicate as an adhesive in histologic technology].
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Ca[Si(2)O(2)N(2)]--a novel layer silicate.
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Monosaccharides as silicon chelators: pentacoordinate bis(diolato)(phenyl)silicates with the cis-furanose isomers of common pentoses and hexoses.
Five-coordinate phenylsilicates are formed from the reaction of trimethoxy(phenyl)silane with monosaccharides in methanol in the presence of a stoichiometric amount of base. Five complexes have been isolated and characterized with two ketoses and three aldopentoses. The silicon central atom in [K([18]crown-6)][PhSi(beta-D-Fruf 2,3H-2)2].MeOH (1, Fru=fructose) is part of two chelate rings, with the ligands being beta-D-fructofuranose-O2,O3 dianions. The beta-furanose isomer is best suited for silicon ligation because it exhibits a torsion angle close to 0 degrees for the most acidic diol function, thus assuring a flat chelate ring. The same structural principles are also found in [K([18]crown-6)][PhSi(beta-D-Araf1,2H-2)2].2 MeOH (2, Ara=arabinose), [K([18]crown-6)][PhSi(alpha-D-Ribf1,2H-2)2] (3, Rib=ribose), [K([18]crown-6)][PhSi(alpha-D-Xylf1,2H-2)2]. acetone (4, Xyl=xylose), and [K([18]crown-6)][PhSi(alpha-D-Rulf2,3H-2)2] (5, Rul=ribulose).
A new quantitative method to evaluate the in vitro bioactivity of melt and sol-gel-derived silicate glasses.
Two melt-derived glasses (45S5 and 60S) and four sol-gel glasses (58S, 68S, 77S, and 91S) have been synthesized. The activation energy for the silicon release was determined, and a very close correlation was observed between this value and published results of the bioactive behavior of the glasses. This relationship can be explained in terms of the influence of chemical composition, textural properties, and structural density on the silanol group formation and silicon dissolution. These measurements provide a quantitative method to evaluate the in vitro bioactivity of SiO(2)-based glasses. Preliminary studies suggest an activation energy gap (Ea) of 0.35-0.5 eV as a boundary between bioactive and nonbioactive glasses.
Complementary use of Fourier transform laser microprobe mass spectrometry and time-of-flight static secondary ion mass spectrometry for the study of the surface adsorption of organic dyes on silicate materials.
The adsorption of organic ionic dyes on different pore size engineered silica materials with potential application for industrial wastewater treatment has been investigated using Fourier transform laser microprobe mass spectrometry (FT-LMMS) and time-of-flight secondary ion mass spectrometry (TOF-S-SIMS). The complementary use of the two methods with different information depth allowed data on the subsurface distribution and pore penetration of the adsorbed organic compounds. Macroscopic methods were employed to determine the amount adsorbed on the particles and the specific external surface area. Local MS analysis allows identification of the organic dyes exclusively at the outer particle surface when the pore size is inferior to the size of the adsorbing molecule, or at the surface of the channels inside the material. Specifically, the monolayer information depth of TOF-S-SIMS causes a signal to refer essentially to the adsorbate at the outer particle surface, which is only a fraction of the total adsorption in mesoporous materials, while FT-LMMS allowed detection of the presence of adsorbates at the outer surface as well as inside the subsurface of 10 to 50 nm depending on the material under study. The observed data open perspectives for the molecular monitoring of the adsorption behaviour of different materials at the (sub) microm scale.
Directed growth of well-aligned zinc silicate nanowires along the channels of surfactant-assembled mesoporous silica.
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Mn-doped silicate micro/nanowire bundles on silicon wafers: synthesis and visible luminescence.
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Visualization of size-selective protein separations on spherical mesoporous silicates.
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Delamination behavior of silicate layers by adsorption of cationic surfactants.
Smectite that has reacted for 48 h with hexadecyltrimethylammonium (HDTMA) cations equivalent to 0.01-3.0 times the cation exchange capacity (CEC) converts to HDTMA-smectite. The microstructure of this organoclay is observed using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). When Na cations in the interlayer of clay are exchanged with HDTMA ions, the changes in internal and external surface configuration are augmented by the intercalation of organic surfactants, showing a heterogeneous increase of interlayer spacings. As HDTMA loading increases, the chance of delaminated layers being developed increases locally in the low-charge interlayer regions by the sufficient adsorption of organic surfactants beyond the CEC due to the tendency of alkyl chain interaction.
Categorization and nomenclature of vitreous silicate wools.
There is substantial interest among government agencies in categorizing fibers for hazard classification purposes, particularly the commercially important synthetic vitreous fibers (e.g., rock wool, slag wool, glass wool, and refractory ceramic fibers). The intent of this categorization is to partition the population of fibers into distinct categories, which are mutually exclusive, collectively exhaustive, easy to understand and implement, and homogeneous with respect to potential biological activity. This paper identifies criteria for categorization, summarizes historical systems for categorization (e.g., by origin, chemistry and structure, physical form and morphology, and application), analyzes the current categorization schemes used by the European Community (EC) and the International Agency for Research on Cancer (IARC), and proposes an improved partitioning method based upon biopersistence/durability. The proposed basis for categorization incorporates the best features of the EC and IARC methods, eliminates some of their inconsistencies, exploits available knowledge of fiber toxicology (much of which was developed in recent years), and is practical to implement.
THE FIBROGENETIC EFFECT OF A GRANULATED IRON SILICATE INTENDED FOR USE IN SAND BLASTING. AN EXPERIMENTAL STUDY.
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[The silicic acid level in human blood].
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