Absorptivity of metals

In a review of data on occupational chemicals that may contaminate breast milk (Byczkowski et al. 1994), it is stated that lead may be excreted in milk in amounts lethal to the infant and that the metal may be mobilized from bone stores to milk during the lactation period. Even when the concentration of lead in mother s milk is low, the absorption of metals into the systemic circulation of infants is generally high when they are on a milk diet. To better understand the sensitivity of the nursing infant to chemicals, epidemiological studies, chemical monitoring, and model development and application are needed. 

We discuss here two major processes, the absorption growth process where particle nuclei grow up with absorption of metal atoms, and the coalescence growth process where particles grow up by collision of particle nuclei or clusters (2). The combination of these processes leads to two well-known distributions, the normal-like distribution and the lognormal distribution, depending on the growth condition. These distributions are frequently found for the size distribution of small particles. The... 

A number of spectral regularities can be noted from Fig. 5. In the vCH bondstretching region, it normally remains possible to distinguish between vCH absorptions of metal-substituted alkanes (3000-2800 cm 1 or, with agostic interactions, below 2800 cm-1), alkenes (3120-2960 cm-, with vCH of / =CH groups somewhat lowered relative to the normal hydrocarbon value), or alkynes (3320-3100 cm-1). 

Preparation of metal oxide thin film by means of stepwise absorption of metal alkoxide has been carried out in the past for the activation of heterogeneous catalysts [13]. For example, Asakura et al. prepared one-atomic layer of niobium oxide by repeating chemisorption of Nb(OEt)5 on silica beads. The catalyst obtained by immobilizing platinum particles on a niobum oxide layer showed improved reactivity for hydrogenation of ethylene in comparison with... 

Becker, W.M. and Hoekstra, W.C. "Intestinal Absorption of Metal Ions, Trace Elements and Radionuclides. Skonyna, S.C. and Waldron-Edward.D., Eds.,Pergamon, Elmsford, NY, 1971 p.229. 

Absorption of metallic acetylacetonates was carried out by immersing test papers in nonaqueous solutions of the iron (III) or copper (II) compound. In both cases, the solution concentration was 5 X 10-3 M. Iron(III) acetylacetonate was dissolved in acetone, and a mixture of acetone and chloroform (1 1) was used to dissolve copper(II) acetylacetonate. Test samples were immersed in metallic acetylacetonate solutions for 30 min and then were air dried. 

The enhancement of surface plasmon absorption of metal nanoparticles may be a result of strong near-field coupling in the close-packed copper-silver nanostructure. The effect is more considerable at the spectral range outside of the copper interband absorption that is why it is not evident at the LSPA band of silver nanoparticles. At th e fi equency range near the LSPA band of copper nanoparticles, near-field coupling is not suppressed by die interband absorption so much and the LSPA enhancement is well seen. 

Using isolated intact epithelial mucosal preparations, we have shown that, when lithium associated with the extracellular space was taken into account, acute cellular uptake of lithium was negligible (172). This is confirmed by experiments on lithium efflux from everted rings of rat jejunum (173). The recognition that intestinal uptake and transport of lithium may not involve transcellular transport of the metal agrees with proposed transport mechanisms for other alkali metals and magnesium (174). Metal-ion carrier proteins are not essential for rapid absorption of metals to occur their function is to assist when existing equilibrium conditions are unfavorable. 

Outside the hepatic system, MTs facilitate absorption of metals such as cadmium into the kidneys and liver. Also, the induction of MTs via reactive metals protects hepatic enzymes against cellular damage. Without this intervention, zinc may stimulate... 

Inorganic Mercury. The oral absorption of metallic mercury is negligible, and even massive doses have not resulted in neurological effects. The wo case histories identified are unusual in that the dose levels could be reasonably well quantified. The first case history reported ingestion of 15 mL (204 g) of... 

The most sensitive end point following oral exposure of any duration to inorganic salts of mercury appears to be the kidneys. Liquid metallic mercury can volatilize at ambient temperatures. The absorption of metallic mercury vapors from lungs is high (about 80%) (Hursh et al. 1976), and the most sensitive target following inhalation exposure to metallic mercury is the central nervous system. 

The physiological role of metallothioneins remains unknown, but it may be, in part, to protect cells from metal toxicity by binding metal ions. Metallothioneins may also be important for intestinal and renal absorption of metals and for metal storage and excretion. 

The speciation behavior of an element in soils profoundly affects its bioavailability. Sometimes this is not evident until a soil property is changed. For example, absorption of metal ions such as Cu and Cd by plant roots is correlated to the... 

Bommann, G., G. Henke, H. AUes, and H. Mollmaim. 1970. Intestinal absorption of metallic mercury, [in German]. Arch. Toxicol. 26(3) 203-209. 

Diamond GL, Goodrum PE, Eelter SP and Ruoee WL (1998) Gastrointestinal absorption of metals [corrected and republished article originally printed in Drug Chem Toxicol 1997 Nov 20 345-368]. Drug Chem Toxicol 21 223-251. 

Respiratory aspects dyspnea from absorption of metal dust or fume, emphysema, pulmonary fibrosis, formation of granuloma, chronic asthma. 

Skog E and Wahlberg J (1964) A comparative investigation ofthe percutaneous absorption of metal compounds in the guinea pig by means of radioactive isotopes "Cr, Co, Zit, " Ag, Cd, Hg. J Invest Dermatol 43 187-192. 

Rashid, M.A., 1974. Absorption of metals on sedimentary and peat humic acids. Chem. Geol., 13 115-123. 

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