Naturally-occurring ferric

Note the naturally occurring ferric trihy-droxamates, such as ferrichrome, are much more resistant to dissociation in acid and the... 

The chromic-substituted siderophore complexes can be prepared and, in contrast to the naturally occurring ferric complexes, are kinetic-ally inert to isomerization or ligand substitution. 

Ferric tellurite occurs in nature as the mineral durdenite in Honduras,4 associated with metallic tellurium. Hardness 2 to 2 5. Its chemical composition closely approaches that represented by the formula Fe2O3.3TeO2.4H2O, or Fe(Te03)3.4H20. Emmonsite is another naturally occurring ferric tellurite found in Colorado 5 as yellowish green scales, associated with lead carbonate and quartz. 

Stable structures such as the naturally occurring ferric porphyrin complexes or porphyrins substituted with copper, cobalt, silver or vanadyl probe the active site of heme-containing enzyme [227]. Complexes of copper not associated with heme are also common. They are frequently formed at an amino terminus because the amino group provides a good primary amine donor atom. Two or three amino acid residues beginning at the N-terminus are often flexible until a more rigid portion of the polypeptide, such as the a helix, is encountered. A peptide nitrogen is available to... 

Bole, Armenian. Bolus armena bolus rubra red bole. A red variety of clay (aluminum silicate) cents naturally occurring ferric oxide (hematite). Originally found in Armenia. 

On the basis of a number of physico-chemical methods (Mossbauer spectroscopy, electron diffraction, EXAFS) the iron cores of naturally occurring haemosiderins isolated from various iron-loaded animals and man (horse, reindeer, birds and human old age) were consistently shown to have ferrihydrite-like iron cores similar to those of ferritin (Ward et ah, 1992, 2000). In marked contrast, in the tissues of patients with two pathogenic iron-loading syndromes, genetic haemochromatosis and thalassaemia, the haemosiderins isolated had predominantly amorphous ferric oxide and goethite cores, respectively (Dickson etah, 1988 Mann etah, 1988 ... 

Jang, M., Min, S.-H., Kim, T.-H. and Park, J.K. (2006) Removal of arsenite and arsenate using hydrous ferric oxide incorporated into naturally occurring porous diatomite. Environmental Science and Technology, 40(5), 1636-43. 

Indian red is a naturally occurring mineral whose ferric oxide content may vary from 80 to 95%, the remainder being clay and silica. It is made by grinding hematite and floating off the fines for use. 

Ocher is a naturally occurring pigment consisting of clay colored with 10 to 30% ferric hydroxide [Fe(OH)3], It must be ground and levigated. 

Mutation in the distal heme pocket of the a chain the heme iron atoms in the a chains are in the high-spin ferric state, i.e., (a2 p2), with five unpaired electrons per heme iron in the a chains and with four unpaired electrons per heme iron in the p chains a naturally occurring valency hybrid hemoglobin... 

Table 3. Stability constants of some naturally occurring trihydroxamic acids with ferric iron (G. Anderegg, F. L Eplattenier and G. Schwarzenbach Helv. Chim. Acta 46, 1409, 1963 J. B. Neilands Experentia Suppl. IX, 22, 1964).

Iron is an element almost ubiquitous in nature, occurring most commonly as ferric oxide ( rust ). The sand used for concrete and mortar, for example, contains up to 4% iron, while Portland cement contains between 2 to 5% iron.97 In general, the iron - in the form of rust - is the reason why building and similar materials (concrete, mortar, plaster, but loam and clay as well) are frequently ochre or red. 

The salt obtained in this way is not pure, but contains small quantities of ferric sulphate and the sulphates of metals such as manganese naturally occurring in the pyrites. Copper sulphate is removed by allowing the liquors to remain a sufficient length of time m contact with the scrap iron, the copper being precipitated out —... 

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