Availability, metals

NOTES M = metal, carbon steel. Other metals available. 

Standard probe body from cadmium-plated mild steel (other metals available on special order)... 

Metallothioneins are a group of small proteins (about 6.5 kDa), found in the cytosol of cells, particularly of liver, kidney, and intestine. They have a high content of cysteine and can bind copper, zinc, cadmium, and mercury. The SH groups of cysteine are involved in binding the metals. Acute intake (eg, by injection) of copper and of certain other metals increases the amount (induction) of these proteins in tissues, as does administration of certain hormones or cytokines. These proteins may function to store the above metals in a nontoxic form and are involved in their overall metaboHsm in the body. Sequestration of copper also diminishes the amount of this metal available to generate free radicals. 

Are used to accelerate autoxidation and hardening of oxidisable coatings. Metal soaps, used as paint driers, can be made from a variety of carboxylic acids, including the commercially important naphthenic and 2-ethyl hexanoic acids, tall oil, fatty acids, neodecanoic and isononanoic acid. Cobalt is unquestionably the most active drier metal available. Metallic driers such as cobalt naphthenate or octoate and zinc salts can interact with UVAs, HALS, or AOs. 

It is well known that the energy profiles of Compton scattered X-rays in solids provide a lot of important information about the electronic structures [1], The application of the Compton scattering method to high pressure has attracted a lot of attention since the extremely intense X-rays was obtained from a synchrotron radiation (SR) source. Lithium with three electrons per atom (one conduction electron and two core electrons) is the most elementary metal available for both theoretical and experimental studies. Until now there have been a lot of works not only at ambient pressure but also at high pressure because its electronic state is approximated by free electron model (FEM) [2, 3]. In the present work we report the result of the measurement of the Compton profile of Li at high pressure and pressure dependence of the Fermi momentum by using SR. 

Kornyshev et al.76 proposed several models of the interface, including both orienting solvent dipoles and polarizable metal electrons, to calculate the position of the capacitance hump. Although it had been shown32,79 101 that this was one of the features of the interfacial capacity curves that should depend on the nature of the metal, available calculations did not give the proper position of the hump. The solvent molecules in the surface layer were modeled as charged layers, associated with the protons and the oxygen atoms of molecules oriented either toward or away from the surface. These layers also carried Harrison-type pseudopoten-... 

Simeoni L.A., Barbarick K.A., Sabey B.R. Effect of small-scale composting of sewage sludge on heavy metal availability to plants. J Environ Qual 1984 13 264-268. 

The purest grade of europium metal available from the Lindsay Chemical Division of American Potash is 99.9% Eu in terms of rare earth content, but it may contain up to 1% of other metal impurities (mainly tantalum when prepared in tantalum vessels) and typically contains 2.8 mol % oxygen.6... 

Decreasing the pH makes more metal available to the electrode during the plating period. The metals are apparently made available through a number of processes ... 

In Limnodrilus sp., an oligochaete worm, copper bioavailability from surhcial freshwater sediments is associated with the amount of copper present in the manganese oxide fraction of the sediment. The redox potential and pH in the gut of Limnodrilus allows the dissolution of the manganese oxide coating, making copper and other metals available for uptake (Diks and Allen 1983). 

Parker, D. R. and Pedler, J. F. (1997). Reevaluating the free-ion activity model of trace metal availability to higher plants, Plant and Soil, 196, 223-228. 

In-situ infrared spectroscopy has been used in much the same fashion at TGA, but temperature profiles have been combined with monitoring changes at constant temperature. " IR spectroscopy does not yield the same direct information about the complete removal of organic residues that TGA provides. On the other hand, CO adsorption experiments performed along with dendrimer decomposition experiments provide direct information regarding metal availability. Further, IR experiments provide... 

The metals treatment process is not tolerant of free oil and grease. In order to be useful for a soil with free oil and grease, prior treatment will be required. The metals treatment process uses an acid solubilization step to make the metals available for removal. If the soil matrix contains... 

Mechanisms of attenuation of metal availability in in situ remediation treatments. Environmental Science Technology, 36, 2991-2996. 

Further evidence has been obtained to support the contention that the active catalysts are metal complexes dissolved in solution. With experiments reported in Table II, the kinetics of oxidation under standard conditions in the presence of various metal salts are compared with the rates of reaction when solid residues have been filtered from solution. The agreement between the rates in Cases 1 and 3 of Table II (where the amount of metal available is dictated by the solubility of metal complexes) shows that solid precipitates play little or no part in catalysis in all the systems studied. The amount of metal in solution has been measured in Cases 2 and 3 metal hydroxide complexes (Case 2) are not as soluble as metal-thiol complexes, and neither is as soluble as metal phthalocyanines (19). The results of experiments involving metal pyrophosphates are particularly interesting, in that it has previously been suggested that cobalt pyrophosphates act as heterogeneous catalysts. The result s in Table II show that this is not true in the present system. 

When assessing the in vivo relevance of metal chelation to explain the antioxidant capacity of polyphenols, another physiological fact that should be considered is the very modest amount of metals available to catalyze free... 

The simple definition of biological availability as the fraction of the total trace metal available for uptake by the biota implicitly assumes that all relevant organisms will have similar uptake characteristics. In addition the use of biological availability as a chemical parameter involves the assumption that it can be identified with particular chemical species or groups of species. Perhaps surprisingly many of the studies carried out to date have lent support to these assumptions, though the detailed mechanisms of the uptake processes remain unclear. Some of the inorganic chemical species identified as... 

Del Castilho and Rix [265] reviewed the suitability of the ammonium acetate extraction method to predict heavy metal availability in soils. 

We have addressed the topic of metal bioavailability and metal toxicity in environmental samples. Traditionally, metal availability is investigated using a chemical approach. Afterwards, the concept of Water Effect Ratio (WER) was proposed by the U.S. EPA and employed bioassays (e.g., fish and invertebrate tests) to assess metal bioavailability and toxicity. In the HMBC approach discussed in this review, we have made use of a bacterial assay that is specific for metal toxicity to achieve this goal. This is only a preliminary survey of the potential applications of the HMBC concept. Some preliminary results on the use of MetPLATE for the fractionation of HMBC to obtain information on the factor(s) that control metal bioavailability in environmental samples were also presented. Using MetPLATE eliminates or diminishes the confounding factor represented by the presence of organic toxicants in a given sample. Further work is needed to refine the fractionation scheme. 

This topic has been comprehensively discussed for soils (Pickering, 1986 Ure, 1996) for soils, sewage sludges and sludged soils (Beckett, 1989 McGrath, 1996) for soils and sediments (Ure et al., 1995) and for radionuclide and heavy metal availability (Kennedy et al., 1997). 

A further area in which sequential extraction continues to be applied successfully is in assessment of the likelihood of mobilisation of metal contaminants from sediment-derived soil. When dredged sediment is used to reclaim land from the coastal margins or applied to arable soil to improve fertility, there is concern that potentially toxic elements accumulated under reducing conditions may be released on exposure to an oxygen-rich environment. Sequential extraction can be used to characterise the sediment prior to application, or to monitor changes in metal availability in the soil with time (e.g. Singh et al, 1998). 

Kennedy, VH., Sanchez, A.L., Oughton, D.H. and Rowland, A.R (1997) Use of single and sequential extractants to assess radionuclide and heavy metal availability from soil to roots. Analyst, 122, 89R-100R. 

Maiz, I., Esnaola, M.V and Millan, E. (1997) Evaluation of heavy metal availability in contaminated soils by a short sequential extraction procedure. Sd. Total Environ., 206,107-115. 

Rainbow, P.S. 1995. Biomonitoring of heavy metal availability in the marine environment. Mar. Pollut. Bull. 31 183-192. 

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