(n.) An impure, massive, flintlike quartz or hornstone, of a dull color.
Example Sentences:
(1) Occurrence of well-preserved rod-shaped and coccoid bacteria in the Precambrian Gunflint chert (1.9 x 10(9) years old) has been demonstrated by electron microscopy.
(2) In order to evaluate the degree of morphological preservation of erythrocytes in bloodstains, an accidental human blood smear on white chert and several experimental bloodstains on hard substrates (the same stone-white chert; another type of stone-graywacke; a non-stone support-stainless steel), were stored in a room, in non-sterile and fluctuating conditions, for lengths of time ranging from 3 to 18 months.
(3) Large amounts of well preserved microfossils have been reported from the cherts of the Upper Proterozoic of the Bohemian Massif (Middle Europe).
(4) Two billion year old black chert lenses from the Duck Creek formation, northwestern Western Australia, contain abundant organically preserved microorganisms which are morphologically similar to fossils of approximately the same age from the Gunflint formation, Ontario.
Silicate
Definition:
(n.) A salt of silicic acid.
Example Sentences:
(1) Folch extraction and partition followed by silicic acid column chromatography revealed the antigens to be glycolipids.
(2) The UE and KE fractions were then separated by silicic acid column chromatography with a stepwise elution method using ether-hexane.
(3) Increased levels of influenza virus multiplication concomitant with decreased levels of interferon occurred in cell monolayers pretreated with silicates.
(4) The dissolution t50 and various pharmacokinetic parameters showed directly compressible starch and carboxymethylstarch to be the most effective disintegrants in the concentrations employed while magnesium aluminum silicate and microcrystalline cellulose were about equal but less effective than the previous disintegrants.
(5) As with SRS-A, pSRS could be absorbed onto Amberlite XAD-2 and silicic acid.
(6) The in vivo experiments confirmed previous reports concerning unfavourable pulp reaction caused by silicate cement, while the glass ionomer cement caused mainly a mild pulp reaction after 8 days of observation.
(7) The results are negative in swampy meadow -- habitats on siliceous soils.
(8) The origin of aluminum silicate inclusions in pulmonary macrophages has yet to be determined, although preliminary evidence strongly suggests that they are derived from inhaled tobacco smoke.
(9) Purification was achieved by sequential use of partitioning in solvents, DEAE-Sephadex chromatography, base treatment, and silicic acid chromatography.
(10) Chromatography of rat-liver lipids on a column of silicic acid or a mixture of silicic acid and Hyflo Super-Cel, with chloroform-methanol mixtures, gave monophosphoinositide-containing fractions which were invariably contaminated by the presence of nitrogen-containing phospholipids.
(11) Hemolysis from silicates is decreased by interventions which remove superoxide anion or hydrogen peroxide from the medium, or by pretreatment of dusts with iron chelators.
(12) Condensation of 1,2,3,4,6-penta-O-acetyl-beta-D-galactopyranose with benzyl 2-azido-4,6-di-O-benzyl-2-deoxy-beta-D-galactopyranoside in the presence of trimethylsilyl triflate gave crystalline benzyl 2-azido-4,6-di-O-benzyl-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl-beta-D-ga lactopyranosyl)-beta-D-galactopyranoside (76%), which was converted into benzyl 2-azido-4,6-di-O-benzyl-2-deoxy-3-O-(2,6-di-O-benzyl-beta-D-galactopy ranosyl)-beta-D-galactopyranoside and condensed with 3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-galactopyranosyl bromide in the presence of silver silicate on alumina and molecular sieve 4 A to give 61% of benzyl O-(3,4,6-tri-O-acetyl-2-azido-2-deoxy-beta-D-galactopyranosyl)-(1----4)- O-(2,6-di- O-benzyl-beta-D-galactopyranosyl)-(1----3)-2-azido-4,6-di-O-benzyl-2-deo xy- beta-D-galactopyranoside.
(13) Total neutral and acidic glycosphingolipids were prepared from whole tissues of the sea-water bivalve, Meretrix lusoria, and the former preparation was further fractionated into subgroups by silicic acid column chromatography.
(14) Talc (magnesium silicate) is a widely used, generally considered benign substance.
(15) Silica is a component of talc (magnesium silicate) used as a drug filler.
(16) Silicic acid could, by hydrogen bonding, alter the conformation of organic macromolecules, since hydrogen bond association can inhibit silanol condensation.
(17) A novel phosphonoglycosphingolipid named SGL-I' containing 1 mol of 2-aminoethylphosphonate residue was isolated from the skin of Aplysia kurodai using two silicic acid chromatography systems.
(18) Treatment of exposed dentin with calcium hydroxide reduced the pulp irritating effect of silicate cement restorations, but induced only limited volumes of irregular secondary dentin formation.
(19) The activity to induce IgE antibody production by fly ash instillation was almost the same as that by aluminum silicate, studied previously.
(20) Isolated cells from the siliceous sponge Geodia cydonium as well as small primary aggregates (diameter: 70 mum) consisting of them show no increase in rates of programmed syntheses and mitotic activity with time.