(n.) Formerly, the metallic base of a fixed alkali, or alkaline earth; -- applied by Sir H. Davy to sodium, potassium, and some other metallic substances whose metallic character was supposed to be not well defined.
(n.) Now, one of several elementary substances which in the free state are unlike metals, and whose compounds possess or produce acid, rather than basic, properties; a nonmetal; as, boron, carbon, phosphorus, nitrogen, oxygen, sulphur, chlorine, bromine, etc., are metalloids.
(a.) Having the appearance of a metal.
(a.) Having the properties of a nonmetal; nonmetallic; acid; negative.
Example Sentences:
(1) As with other elements, the interest here is the potential effect of environmental acidification on environmental behavior in ways that are relevant to human exposure to these metalloids.
(2) The effects of the well established carcinogenic metals or metalloids (As, Be, Cr, Ni), hypothetically carcinogenic but well-established cocarcinogenic metals (Cd, Pb, Co) and weak co-carcinogenic metals (Al, Cu, Fe, Zn) and the antagonism between Mg and these metals were studied on the ionic transfer through the isolated human amnion.
(3) New information about the toxic effect of some metals and metalloids and about their kinetics of absorption, distribution and excretion in experimental animals, and particularly in man, is necessary for elaborating suitable biological exposure tests.
(4) Selenium (Se) is a metalloid with chemical properties closed to those of sulfur, but they can not substitute for one another in vivo.
(5) In order to invalidate or confirm the affirmation that non antithyroid sulphide molecules alter the measure of the thyroid fixation rate of iodine 131 we undertook on the rat: on one hand a kinetic study of thyroid fixation of sodium thiosulfate labelled with sulphur 35, which showed a very low captation not exceeding 0,01% of injected radioactivity; on the other hand the study of the effects of some sulphide molecules on thyroid fixation of iodine 131 in the rat: sodium thiosulfate, association of sodium thiosulfate + metalloidal sulphur + methionine, carbutamide and dimethylsulfoxyde in various kinds of dose administration and periods.
(6) Main group metals and metalloids were surveyed for the identification of species that can either donate or accept methyl groups.
(7) Diethyl maleate, indocyanine green and sulfobromophthalein (BSP), which decreased biliary excretion of GSH, significantly diminished excretion of antimony and bismuth into bile indicating that hepatobiliary transport of these metalloids is GSH-dependent.
(8) In recent years, however, it has become clear that several metals and metalloids undergo transformations in mammalian tissues and that metabolism may have important implications in clinical pharmacology, toxicology, and environmental health.
(9) Proportionally to their biliary excretion rates, these metalloids generate increased biliary excretion of GSH probably because they are transported from liver to bile as unstable GSH complexes.
(10) The potential impact of acidic deposition on As and Se in soils cannot readily be assessed with respect to human exposure, but it would appear that the behavior of these metalloids in poorly buffered, poorly immobilizing soils, e.g., sandy soils of low metal hydrous oxide content, would be most affected.
(11) Biological monitoring of exposure to metals and metalloids involves not only determination of these elements in selected body fluids and tissues but, in some cases, also determination of a certain biochemical indicator which signalises the presence of the monitored element in the organism.
(12) Methylcobalamin (methyl-B12) has been implicated in the biomethylation of the heavy metals (mercury, tin, platinum, gold, and thallium) as well as the metalloids (arsenic, selenium, tellurium and sulfur).
(13) Details of the kinetics and mechanisms for biomethylation of arsenic are presented, with special emphasis on synergistic reactions between metal and metalloids in different oxidation states.
(14) The exchange rates for metals and metalloids between sediments, soils, water and aquatic biota are discussed in terms of normal and acidified ecosystems.
(15) The occupational history highlighted heavy exposure to inhalation of ash derived from mineral oil combustion and containing several elements, metals and metalloids, including vanadium and nickel.
(16) Available information on acid precipitation and the environmental behavior of these metalloids do, however, permit some preliminary conclusions to be drawn.
(17) Over the past 15 years, these methods have led to the establishment of causal factors in metal- and metalloid-induced toxicity.
(18) The present studies in rats aimed to determine whether antimony and bismuth, other metalloids in group Va of the periodic table, also possess similar properties.
(19) The abnormal life--potentially the death--of the cell can be restored by a metalloid--lithium--which is nearly as common as sodium in the mineral world.
(20) In this report we present details of the mechanisms for biological methylation of certain metals and metalloids with special emphasis on those elements that are widely dispersed in the biosphere.
Silicon
Definition:
(n.) A nonmetalic element analogous to carbon. It always occurs combined in nature, and is artificially obtained in the free state, usually as a dark brown amorphous powder, or as a dark crystalline substance with a meetallic luster. Its oxide is silica, or common quartz, and in this form, or as silicates, it is, next to oxygen, the most abundant element of the earth's crust. Silicon is characteristically the element of the mineral kingdom, as carbon is of the organic world. Symbol Si. Atomic weight 28. Called also silicium.
Example Sentences:
(1) There fore, the adverse effects may be induced by such quartz or silicon compounds.
(2) Of all materials evaluated, Xantopren Blue and Silene silicone impression materials provided the best results in vivo.
(3) We describe an enzymatic fluorometric method for determining glucose concentrations in blood samples by analysis on a semi-solid surface (silicone-rubber pads).
(4) Silicon, a relatively unknown trace element in nutritional research, has been uniquely localized in active calcification sites in young bone.
(5) A critical attitude towards the use of silicone breast implants, when these are used for purely cosmetic purposes, is recommended at present.
(6) An in vitro, eccentric arterial stenosis model was created using 15 canine carotid arteries cannulated with silicone plugs containing special pressure-transducing catheters designed to measure pressure directly, within the stenosis.
(7) The scaphoid silicone implant bore significant, although less, load than the normal scaphoid.
(8) A visual acuity of 0.05 or better was achieved in 36% of the eyes treated with silicone oil versus 67% of the eyes treated with gas tamponade.
(9) The biocompatibility and fixation of a new silicone intraocular lens was evaluated in the cat eye.
(10) The numbers in the holey tube regenerate are statistically different from normal but they are closer to normal than after similar regeneration in a regular silicone tube.
(11) Silicon levels tend to be higher in foods derived from plants than in foods from animal sources.
(12) The most common complications in breast augmentation surgery with homologous fat grafts obtained from fresh cadavers are presented, showing subsequent surgical procedures to reconstruct the breasts of such patients through use of silicone prostheses and muscle flaps from the latissimus dorsi.
(13) The lid is fiddly to fit on to the cup, and smells so strongly of silicone it almost entirely ruins the taste of the coffee if you don’t remove it.
(14) Perry and I are on our way to the Silicon Drinkabout , a get-together for anyone connected to the tech scene, hosted every week by a different local bar.
(15) A further increase in silicon dioxide concentration produced tablets with relatively larger pore sizes.
(16) Porous polyethylene was thus better incorporated into the soft tissues than silicone rubber as long as the overlying soft tissues were not stressed by an oversized implant or inadequate soft tissue coverage.
(17) Obliteration of the empty sella with an extradural silicone balloon via the transsphenoidal approach seemed to have been effective for headache and visual complaints of primary empty sella syndrome which did not respond to medical therapy.
(18) Mice were exposed to hypoxia by enclosure in cages covered with dimethyl-silicone rubber membranes for 1-14 days.
(19) Mid-shaft sections of 100% silicone (Bardex) and hydrogel-coated latex (Biocath) catheters were subjected to controlled in vitro encrustation conditions for periods of up to 18 weeks.
(20) "Posterior collagenous layer" was observed subendothelial in eyes injected with various silicone oil fluids including highly purified one.