Metals transformation

The mechanism of the poisoning effect of nickel or palladium (and other metal) hydrides may be explained, generally, in terms of the electronic theory of catalysis on transition metals. Hydrogen when forming a hydride phase fills the empty energy levels in the nickel or palladium (or alloys) d band with its Is electron. In consequence the initially d transition metal transforms into an s-p metal and loses its great ability to chemisorb and properly activate catalytically the reactants involved. 

Cohen, I. Bernard. "Metallurgical and non-metallurgical alchemy." In Metal transformations informal proceedings of the second Buhl International conference on materials, eds. W.W. Mullins and M.C. Shaw, 135-171. New York Gordon Breach, 1968. 

Smith, C. S. (1968), The early history of casting, molds, and the science of solidification, Metal Transformations Informal Proc. 2nd Bull Int. Conf. on Materials in Pittsburgh, 1966, New York, pp. 3-51. 

C). In addition, enzymes often combine a high specificity for the recognized substrates with a large tolerance for secondary structure. Alternatively, noble metal transformations offer reaction conditions that are also mild enough to be compatible with sensitive, doubly lipidated peptides. 

Fig. 2.3-13. Molecular structure of 62 and relationships to Al metal (transformation of the position of the Al atoms of 62 in the direction of the closest packing in the bulk metal).

Direction a. Alkali metals transform saturated ketones into secondary alcohols. The reaction proceeds in the mixture of ethanol and liquid ammonia in the presence of ammonium chloride as a proton donor and follows Scheme 1.11 (Rautenstrauch et al. 1981). 

While Paracelsus often maintained that attempting to transmute base metals into gold was a waste of time, he nevertheless attempted the transmutation himself. He accepted the then-common idea that metals grew inside the Earth and that, given enough time, all of them would eventually become gold. If other metals transformed themselves into gold naturally, then it seemed only reasonable that the transformation could be made to happen by artificial means. 

At temperatures > 600 °C, ferrihydrite and also 5-FeOOH which have been partly substituted with divalent transition metals, transform to a... 

Nevertheless, the inspection of other transition metal series shows that, just as atomic volumes, there are regular variations of cohesive energies when the metal valence changes. Thus, a general increase of about 45 Kcal/mol is found when a metal transforms from a trivalent to a tetravalent state. 

Linak, W. P. Wendt, J. O. L. 1994. Trace-metal transformation mechanisms during coal combustion. Fuel Processing Technology, 39, 173-198. 

Ni-S behaves rather similarly to Co-S (see Sec. 6.5, Cobalt). Note that the freshly precipitated monosulphides of both metals transform in solution to a more insoluble form-possibly M(OH)S. 

Konetzka, W.A. (1977). Microbiology of metal transformations. In Microorganisms and Minerals, ed. E.D. Weinberg, pp. 317-42. New York Marcel Dekker. 

Flyhammer, R (1997) Estimation of heavy metal transformations in municipal solid waste. Sci. Total Environ., 198, 123-133. 

Gadd, G. M. (2001). Metal transformations. In Fungi in Bioremediation, ed. G. M. Gadd. Cambridge Cambridge University Press, pp. 359-82. 

POWDER OF PROJECTION — The Outcome of the Hermetic Work, which being projected upon metals, transforms them into Gold or into Silver, according as the work has been developed to the white or to the red stage. 

Barton L U of New Mexico Albuquerque NM Mechanisms of metal transformation in bacteria NIH, Natl Inst of Gen Med Science... 

Zirconium hydride is not a tme compound of fixed stoichiometry but rather a series of crystalline phases through which zirconium metal transforms with changing hydrogen concentration and temperature. The y-phase hydride exists below 250°C in the narrow composition range ZrH.Qg to ZrH the 5-phase has a compositional range Zftl to ZrH and the S-phase has a compositional range ZrH g—Z1H2. Most commercial hydride powder contains 5- and S-phase. 

Zaloum R, Lessard S, Mourato D, and Carriere J. Membrane bioreactor treatment of oily wastes from a metal transformation mill. Water Sci Technol. 1994 30(9) 21-27. 

There are a number of other important physiological events that must occur if the iron-oxidizing bacteria are to survive and perform in metal transformations. These include CO2 fixation, generation of reducing power (NADH and NADPH), heterotrophic metabolism and reduced sulfur oxidation. 

For many of the more abundant elements, such as Al, Fe, and Mn, precipitation of mineral forms is common and may greatly influence or even control their solubility. For most trace elements, direct precipitation from solution through homogeneous nucleation appears to be less likely than adsorption-desorption, by virtue of the low concentration of these metals and metalloids in soil solutions in well-aerated dryland soils. When soils become heavily polluted, metal solubility may reach a level to satisfy the solubility product to cause precipitation. Precipitation may also occur in the immediate vicinity of the phosphate fertilizer zone, where the concentration of heavy metals and metalloids present as impurities may be sufficiently high. Precipitation of trace metals as sulfides may have a significant role in metal transformation in reduced environments where the solution sulfide concentration is sufficiently high to satisfy the solubility product constants of metal sulfides (Robert and Berthelin, 1986). 

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