Metal associations

What are Refractory MetaM Refractory Metals Association, Metal Powder Industries Eederation, Princeton, N.J., 1980, pp. 4—5. 

Because a length of metal associated with the connector contact is ordinarily in the path between the contact end to which a wire is terminated and the contact interface, its resistance (bulk resistance) must be added to contact resistance when considering the connector as a circuit element. This overall resistance is sometimes erroneously called contact resistance. 

In this work, atmospheric particles (PM 10 and PM 2.5) were collected by a dichotomos air sampler. Several leaching procedures were investigated for decomposition of heavy metals. The digests were pre-concentrated with sodium diethyldithiocarbamate. The determinations were canted out on a Vartan Model AA-220 atomic absorption spectrometer. The instrarment was equipped with a GTA-110 graphite furnace system. Table 1 shows the concentrations of heavy metals associated with PM 10 and PM 2.5 particles. Table 1. Concentrations of heavy metals in PM 10 and PM 2.5 atmospheric particles (ng/m )... 

Depending upon the stress load, time, and temperature, the extension of a metal associated with creep finally ends in failure. Creep-rupture or stress-rupture are the terms used to indicate the stress level to produce failure in a material at a given temperature for a particular period of time. For example, the stress to produce rupture for carbon steel in 10,000 hours (1.14 years) at a temperature of900°F is substantially less than the ultimate tensile strength of the steel at the corresponding temperature. The tensile strength of carbon steel at 900°F is 54,000 psi, whereas the stress to cause rupture in 10,000 hours is only 11,500psi. 

The atmosphere may be an important transport medium for many other trace elements. Lead and other metals associated with industrial activity are found in remote ice caps and sediments. The transport of iron in wind-blown soil may provide this nutrient to remote marine areas. There may be phosphorus in the form of phosphine, PH3, although the detection of volatile phosphorus has not been convincingly or extensively reported to date. 

They indicated that the softness parameter may reasonably be considered as a quantitative measure of the softness of metal ions and is consistent with the HSAB principle by Pearson (1963, 1968). Wood et al. (1987) have shown experimentally that the relative solubilities of the metals in H20-NaCl-C02 solutions from 200°C to 350°C are consistent with the HSAB principle in chloride-poor solutions, the soft ions Au" " and Ag+ prefer to combine with the soft bisulfide ligand the borderline ions Fe +, Zn +, Pb +, Sb + and Bi- + prefer water, hydroxyl, carbonate or bicarbonate ligands, and the extremely hard Mo + bonds only to the hard anions OH and. Tables 1.23 and 1.24 show the classification of metals and ligands according to the HSAB principle of Ahrland et al. (1958), Pearson (1963, 1968) (Table 1.23) and softness parameter of Yamada and Tanaka (1975) (Table 1.24). Compari.son of Table 1.22 with Tables 1.23 and 1.24 makes it evident that the metals associated with the gold-silver deposits have a relatively soft character, whereas those associated with the base-metal deposits have a relatively hard (or borderline) character. For example, metals that tend to form hard acids (Mn +, Ga +, In- +, Fe +, Sn " ", MoO +, WO " ", CO2) and borderline acids (Fe +, Zn +, Pb +, Sb +) are enriched in the base-metal deposits, whereas metals that tend to form soft acids... 

Type Temperature, pressure and geologic condition Common ore metal association... 

Air pollution control (APC) dust and sludge Metal dusts (consisting of iron particulate, zinc, and other metals associated with the scrap, and flux) Slag Kish... 

Campbell, K.R. 1994. Concentrations of heavy metals associated with urban runoff in fish living in stormwater treatment ponds. Arch. Environ. Contam. Toxicol. 27 352-356. 

McCallum, I.S., Loucks, R.R., Carlson, R.R., Cooley, E.F., and Doerge, T.A., Platinum Metals Associated with Hydrothermal Copper Ores of the New Rambler Mine, Medicine Bow Mountain, Economic Geology, Vol. 71, pp. 1429-1459, 1976. 

Measurement of trace metal concentrations can provide fundamental insights into marine geochemical processes. Many metals are important micronutrients in seawater and can play a significant role in upper ocean biogeochemistry and carbon cycling. Under certain conditions, elevated concentrations of metals associated with human activities can have negative impacts on marine ecosystems. 

Anal. Chem. 316 616-620 Gerth, J. (1990) Unit-cell dimensions of pure and trace metal-associated goethites. Geo-chim. Cosmochim. Acta 54 363-371 Ghanem, S.A. Miklelson, D.S. (1998) Sorption of zinc on iron hydrous oxide. Sod Sd. 146 11-21... 

Chiu found that the diastereoselectivity had eroded slightly from an earlier synthetic study that included a methyl group in place of the MEM ether side chain of the A ring. Since it had been demonstrated that many of these catalytic systems are metal associated, Chiu attempted to change rhodium ligands from acetate to the... 

Metals associated with organic materials, inert compounds, or iron oxides may not be recovered during the extraction phase of the technology. Complexed hexavalent uranium has been shown to inhibit the growth of one strain of bacteria used for remediation. The effect becomes more pronounced at higher concentrations of uranium. 

Mosander, C. G., On the new metals lanthanium and didymium, which are associated with cerium and on erbium and terbium, new metals associated with yttria, Phil. Mag., [3], 23, 241-54 (Oct., 1843). 

By coupling flow field-flow fractionation (flow FFF) to ICP-MS it is possible to investigate trace metals bound to various size fractions of colloidal and particulate materials.55 This technique is employed for environmental applications,55-57 for example to study trace metals associated with sediments. FFF-ICP-MS is an ideal technique for obtaining information on particle size distribution and depth profiles in sediment cores in addition to the metal concentrations (e.g., of Cu, Fe, Mn, Pb, Sr, Ti and Zn with core depths ranging from 0-40 cm).55 Contaminated river sediments at various depths have been investigated by a combination of selective extraction and FFF-ICP-MS as described by Siripinyanond et al,55... 

The negative charge distribution in the adducts was evaluated on the basis of the chemical shift values and found to be nearly 75% concentrated on the nitrogen atom. In the reactions of l-ethoxycarbonyl-l,4-dihydropyridines with organosodium and organopotassium compounds, the resulting metal-associated (j-adducts were not soluble in aliphatic hydrocarbons alone but were made so by addition of 18-crown-6. This behavior would support ionic structures for the potassium and sodium adducts. 

Carbonate of lead—sparry lead ore—is remarkable for its transparency and lustre when in its purity. Several varieties of this ore are known. It is fouud in the form of ncicular crystals, in compact masses, and often presenting a fibrous, lamellar, and earthy appearance. They all, with the exception of the earthy species, possess a peculiar lustre, like that of whita lead. Earthy carbonate of lead presente several shades of color— brown, green, or blue—dependent upon the nature of the metal associated with it. The mineral is veiy brittle, and its fracture has a waved eonclioidal ap-pearanoe. Its specific gravity varies from 6 to 6 7. 

DHS. February 1989. Detoxifying Foundry Sand. California Department of Health Services, Toxic Substances Control Division, Alternative Technology Section. Prepared by California Cast Metals Association. Contract No. 86-T0106. 

---