Biologically active metal

Two different objectives are common when extracting soil to determine its metal content. The first is to determine the amount of biologically active metal present. This is typically the goal for determining the levels of plant-required metals. In terms of total samples analyzed, this is the most common reason for extracting soil. Metals in soil that are essential to plants and that are most... 

Vanadium has been demonstrated to be a biologically active metal. It has the ability to influence soil enzyme systems which affect mineralisation processes and release of plant nutrients, thus indirectly affecting primary production (Bengtsson and Tyler, 1976). High levels of V may cause colour deepening in the shoots followed by chlorosis. Bowen (1979) has reported that concentrations of 10-40 mg L1 of V in nutrient solutions is toxic for plant seeds. 

Vanadium has long been recognized as a biologically active metal which has an important metabolic role in various marine organisms 53). A vanadium concentration 5 x 105 times that found in natural sea water has been reported in the blood of the ascidian Phallusia mamillata 57). Vanadium is concentrated in form of the blood pigment hemovanadium58). Moreover, vanadium enrichment factors of 4500 in scallops, 2500 in mussels, and 1500 in oysters were observed 59). 

Recent publications indicate the cloud-point extraction by phases of nonionic surfactant as an effective procedure for preconcentrating and separation of metal ions, organic pollutants and biologically active compounds. The effectiveness of the cloud-point extraction is due to its high selectivity and the possibility to obtain high coefficients of absolute preconcentrating while analyzing small volumes of the sample. Besides, the cloud-point extraction with non-ionic surfactants insures the low-cost, simple and accurate analytic procedures. 

Contamination of waters with ai senic occurs as a result of a number of industrial activities such as treatment of industrial wastes, fertilizers, pesticides production, mining, metal smelting etc. and natural processes (e.g. weathering of minerals, volcanic and biological activities). 

One of the most important tasks in Analytical chemistry is the effective and express microquantity determination of toxic metals and biologically active organic materials in different objects of environment, raw materials and products of food technology and biotechnology. 

Finally, in 1797, the Frenchman L. N. Vauquelin discovered the oxide of a new element in a Siberian mineral, now known as crocoite (PbCr04), and in the following year isolated the metal itself by charcoal reduction. This was subsequently named chromium (Greek xpco ia, chroma, colour) because of the variety of colours found in its compounds. Since their discoveries the metals and their compounds have become vitally important in many industries and, as one of the biologically active transition elements, molybdenum has been the subject of a great deal of attention in recent years, especially in the field of nitrogen fixation (p. 1035). 

The Knorr pyrazole synthesis has been extensively utilized in the preparation of a number of pyrazoles as metal chelators, photographic dyes, herbicides, and biologically active... 

Reaction of the host tissue to metallic implants is affected by many factors including shape and size of the implant, movement between the implant and tissue, extent of corrosion attack, general degradation of the implant, and the biological activity of the resulting by-products of corrosion or degradation. 

Quinoline-5-sulfonic acid, 8-hydroxy-7-iodo-metal complexes absorptiometry, 1,549 Quinolinium salts in gravimetry, 1, 535 Quinolinol metal complexes color photography, 6,107 8-Quinolinol biological activity, 6, 771 gallium and indium complexes radiopharmacology, 6, 971 radionuclide complexes radiopharmacology, 6,994 8-Quinolyl sulfate hydrolysis metal catalysis, 6,465 Quinones... 

Biomedical materials include ceramics such as the biologically active hydroxylapatite and tricalcium phosphate, and high-strength metals such as titanium alloys.These materials are not produced by CVD as this time, except on an experimental basis. CVD, however, is the major process used in the production of another very important biomedical material, i.e., isotropic... 

Figure 8-15. The biological activity of some transition-metal ions illustrating the Irving-Williams series.

Sediment Analysis. Sediment is the most chemically and biologically active component of the aquatic environment. Benthic invertebrate and microbial life concentrate in the sediment, a natural sink for precipitated metal forms, and an excellent sorbent for many metal species. TTie extent to which potentially toxic trace element forms bind to sediment is determined by the sediment s binding intensity and capacity and various solution parameters, as well as the concentration and nature of the metal forms of interest. Under some conditions sediment analyses can readily indicate sources of discharged trace elements. 

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