scispace - formally typeset
Search or ask a question

Showing papers on "Ferric published in 1971"


Journal ArticleDOI
TL;DR: Oxyhemoglobin either spontaneously or under the influence of external oxidants is converted to the high spin ferric protein (acid methemoglobin) which can be studied both optically and with electron paramagnetic resonance (EPR).

236 citations


Journal ArticleDOI
TL;DR: Evidence is presented that the small amount of impurity in the ferrous sulfmyoglobin preparation is present as oxymyoglobin, and an analysis of optical properties supports the hypothesis of a structure in which the elements of H2S add across a β—β double bond of a pyrrole and thereby disrupt the porphyrin conjugation and form a chlorin type structure.

181 citations


Journal ArticleDOI
TL;DR: In this paper, Ferric heme pigments have been implicated as the major prooxidants in tissue lipid oxidation, and ferric hemes are believed to promote lipid oxidation.
Abstract: Lipid oxidation is a major cause of deterioration in the quality of meat and meat products Oxidation can occur in either the stored triglycerides or the tissue phospholipids Ferric heme pigments have been implicated as the major prooxidants in tissue lipid oxidation Pigment and lipid oxidation are interrelated, and ferric hemes are believed to promote lipid oxidation The resulting oxidation destroys the hemes Nonheme iron and ascorbic acid may also function as prooxidants in meat Sodium chloride accelerates oxidation of the triglycerides, although the mechanism of salt catalysis is not completely known Cooked meat undergoes rapid deterioration due to tissue lipid oxidation The meat pigment in the cured pink ferrous form does not promote the rapid oxidation undergone by cooked uncured meat Refrigerated and frozen fresh meats are also susceptible to lipid oxidation Protein denaturation and cross-linking may result from lipid oxidation in stored freeze-dried meat With increased consumption of prepackaged raw meat and precooked convenience meat items, control of oxidation has become increasingly important Antioxidants and chelating agents are the most effective inhibitors of lipid oxidation

174 citations



Journal ArticleDOI
TL;DR: From thermodynamic measurements, it is possible to identify the ligand atoms bound to Fe3+ in nearly rhombic environments and D, the second rank axial coefficient in the spin Hamiltonian, is more than 4 times larger for primarily sulfur-ligated than for primarily oxygen-ligate high spin ferric iron.

131 citations


Journal ArticleDOI
TL;DR: In this article, an analysis of a weathered biotite and of biotites converted to vermiculites and subsequently oxidized, showed that oxidation of octahedral ferrous ions to ferric ions is associated with reversible conversion of hydroxyl ions to oxide ions, resulting in an increased number of dioctahedral sites.
Abstract: Infra-red examination of a weathered biotite and of biotites that have been converted to vermiculites and subsequently oxidized, indicates that oxidation of octahedral ferrous ions to ferric ions is associated with a reversible conversion of hydroxyl ions to oxide ions. Subsequently, in high-iron biotites, there is an irreversible loss of ferric ions from the octahedral layer, resulting in an increased number of dioctahedral sites. Electron microscopy and X-ray diffraction indicate that ejected ferric ions form either amorphous interlayer oxides or, when bromine is used as an oxidant, a crystalline external phase of β-FeOOH. The high refractive index of some oxidized vermiculites is shown to be due largely to submicroscopic iron oxides.

125 citations


Journal ArticleDOI
TL;DR: A treatment of proton contact shifts based upon the above model is pertinent to proton magnetic resonance data already available and provides a means to identify directly the ligands at both iron atoms via further PMR experiments.

120 citations


Journal ArticleDOI
TL;DR: The lead ion-selective ceramic membrane electrode developed by sintering a mixture of lead, silver, and cuprous sulfides showed sensitivity, selectivity, and other response characteristics well suited to analytical utilization as mentioned in this paper.
Abstract: The lead(II) ion-selective ceramic membrane electrode developed by sintering a mixture of lead, silver, and cuprous sulfides showed sensitivity, selectivity, and other response characteristics well suited to analytical utilization. The Nernstian slope was obtained over a concentration range from 10−1 to 10−6M Pb2+ in activity, and the analytical range had a concentration of 10−1–10−7M when the membrane contained less than 30 wt% of cuprous sulfide and more than 1 wt% of lead sulfide. Among the common ions, silver, cupric, mercury(II), ferric, sulfide and iodide ions interfered seriously. About 10 times as many cadmium and bromide ions and more than 1000 times as many alkali metal, alkaline earth metal, zinc, aluminum, nickel, manganese(II), cobalt, and nitrate ions did not interfere with the lead ion, however. The electrode potentials did not change over a pH range from 2 to the pH at which the precipitation of lead hydroxide occurred. The electrode was safely used at temperatures from 0 to 95°C, and the ...

119 citations


Journal ArticleDOI
TL;DR: The two-iron ferredoxins from spinach, parsley, Azotobacter vinelandii, Clostridium pasteurianum and the pig adrenal cortex were investigated by Mossbauer spectroscopy at temperatures from 4 to 256°K and in magnetic fields up to 46 kGauss, and the properties of the active center are established.

109 citations


Journal ArticleDOI
TL;DR: The composition of the anodic passive oxide film on iron in neutral solution has been investigated by cathodic reduction, chemical analysis and ellipsometry as mentioned in this paper, and it was found that the film retains nearly constant thickness above a critical potential where transpassive dissolution begins to occur.

103 citations


Journal ArticleDOI
TL;DR: In this article, a new ellipsometric transient technique was used to examine the dissolution and film formation on iron, even though this is undergoing roughening by etching.

Journal ArticleDOI
TL;DR: The Mössbauer spectra of Scenedesmus ferredoxin enriched in (57)Fe were measured and found to be identical with those of two other plant-type ferredoxins that had been previously measured, in agreement with the model proposed by Gibson, Hall, Thornley & Whatley (1966).
Abstract: 1. The Mossbauer spectra of Scenedesmus ferredoxin enriched in 57Fe were measured and found to be identical with those of two other plant-type ferredoxins (from spinach and Euglena) that had been previously measured. Better resolved Mossbauer spectra of spinach ferredoxin are also reported from protein enriched in 57Fe. All these iron–sulphur proteins are known to contain two iron atoms in a molecule that takes up one electron on reduction. 2. The Mossbauer spectra at 195°K have electric hyperfine structure only and show that on reduction the electron goes to one of the iron atoms, the other appearing to remain unchanged. 3. In the oxidized state, both iron atoms are in a similar chemical state, which appears from the chemical shift and quadrupole splitting to be high-spin Fe3+, but they are in slightly different environments. In the reduced state the iron atoms are different and the molecule appears to contain one high-spin Fe2+ and one high-spin Fe3+ atom. 4. At lower temperatures (77 and 4.2°K) the spectra of both iron atoms in the reduced proteins show magnetic hyperfine structure which suggests that the iron in the oxidized state also has unpaired electrons. This provides experimental evidence for earlier suggestions that in the oxidized state there is antiferromagnetic exchange coupling, which would result in a low value for the magnetic susceptibility. 5. In a small magnetic field the spectrum of the reduced ferredoxin shows a Zeeman splitting with hyperfine field (Hn) of 180kG at the nuclei. On application of a strong magnetic field H the spectrum splits into two spectra with effective fields Hn±H, thus confirming the presence of the two antiferromagnetically coupled iron atoms. 6. These results are in agreement with the model proposed by Gibson, Hall, Thornley & Whatley (1966); in the oxidized state there are two Fe3+ atoms (high spin) antiferromagnetically coupled and on reduction of the ferredoxin by one electron one of the ferric atoms becomes Fe2+ (high spin).

Journal ArticleDOI
Norio Sato1, K. Kudo1
TL;DR: In this article, the passivation of a passivation film on iron was investigated and it was shown that the film thickness is linearly related to the oxidation potential in a limited potential region, which extrapolates to a film thicker than a monolayer even at zero anode overvoltage.

Journal ArticleDOI
TL;DR: In this article, the authors determined the selenium (Se) in soil and plant samples after wet digestion with HNO3 and HClO4, using a mixture of 2,3-diaminonaphthalene and piazselenol in cyclohexane followed by fluorometric measurements.
Abstract: Selenium (Se) was determined in soil and plant samples after wet digestion with HNO3 and HClO4 The method included the usual steps, namely, the reduction of Se, complexing Se with 2,3-diaminonaphthalene, and the extraction of the piazselenol in cyclohexane followed by fluorometric measurements The most important step, the stabilization of selenium at the oxidative state Se+4, was achieved by reducing Se+6 to Se+4 with 2 ml of 1 N HCl while the system was kept in a boiling water bath For best results and adequate control of interfering ferric ions, the system was adjusted to pH 18, and a stabilizing agent consisting of 10% hydroxylamine hydrochloride in a 004 M EDTA solution was used Fluorescence measurements obtained for soil samples gave average coefficients of variation and recovery percentages of 335 and 974, respectively For radioactivity counts made on cyclohexane extracts, the coefficients of variation and the recovery percentages were 231 and 931, respectively Similar results were obtai

Journal ArticleDOI
TL;DR: In this paper, the p.z.c between ferric oxide surface and a series of anions and cations having characteristics ranging from structure promoters to structure breakers was studied, showing that the interface acts as a structure promoter for water molecules.
Abstract: Ferric oxide hydrosols are composed of a haematite core surrounded by an hydrated oxide shell. Interactions have been studied, on both sides of the p.z.c., between ferric oxide surface and a series of anions and cations having characteristics ranging from structure promoters to structure breakers. Although ferric oxide has a moderate crystalline field, the observed adsorption sequences show that the interface acts as a structure promoter for water molecules. The large spreading of the measured adsorption sequences, especially at extreme pH values, proved the coagulation technique to be a good tool for the study of ion-surface interactions. A new type of behaviour has been observed; at low surface potentials the ions behave as indifferent but at higher surface potentials they are specifically adsorbed.

Patent
07 Oct 1971
TL;DR: In this article, a hydrometallurgical process for the recovery of metallic copper from chalcopyrite and other copper-containing materials by ferric chloride oxidation thereof to produce cupric chloride, reduction of the cupric and cuprous chloride to cuprous and recovery of the metallic copper, preferably by electrolysis, and regeneration of ferric by oxidation with concurrent purge of iron, and sulfate ions and other impurities from the process solution.
Abstract: A hydrometallurgical process for the recovery of metallic copper from chalcopyrite and other copper-containing materials by ferric chloride oxidation thereof to produce cupric chloride, reduction of the cupric chloride to cuprous chloride, recovery of metallic copper, preferably by electrolysis, and regeneration of ferric chloride by oxidation with concurrent purge of iron, and sulfate ions and other impurities from the process solution. By combining the ferric chloride oxidation and the ferric chloride regeneration, an advantageous reduction in iron content of the process solution is effected along with significant retardation of scaling. The desired chloride molal concentration is maintained by the addition to the process solution of sodium chloride, potassium chloride and/or magnesium chloride. Potassium chloride is a preferred source of chloride ions as a means of purging substantially all sulfate ions from the process solution.

Journal ArticleDOI
TL;DR: The depressant action of phosphate salts and phosphate-containing foods on iron absorption was measured in vivo and compared to the interactions observed between iron and phosphate compounds under conditions similar to those in the gastrointestinal tract.

Journal ArticleDOI
TL;DR: Observations suggest a conformation change involving a possible reorientation of the multi-heme moieties in the partially or fully-reduced tate, and depending on the reactant(s) present this process may be reversible.

Journal ArticleDOI
TL;DR: The low oxygen affinity of sulfmyoglobin is discussed in terms of structural features of the molecule which lower the electron density at the iron and is an example of electronic control of oxygen affinity in hemoglobin-like compounds.

Journal ArticleDOI
06 Sep 1971-Nature
TL;DR: In this paper, the authors used Mossbauer spectroscopy to determine the ratio of ferric to ferrous iron in natural pyroxenes with compositions within the diopside enstatite-ferrosilite-hedenbergite quadrilateral.
Abstract: RATIOS of ferric to ferrous iron in natural pyroxenes reflect the oxygen fugacity of the environment during crystallization. This ratio can be determined with precision using Mossbauer spectroscopy. Natural pyroxenes with compositions within the diopside-enstatite-ferrosilite-hedenbergite quadrilateral generally have values of Fe3+/(Fe2+ + Fe3+) which range from 0.01 to ∼0.2. Members of the augite solid solution series, however, may exhibit much larger ratios which average about 0.5 but may reach 0.94 in extreme cases1. The large Fe3+ content of augites may be attributed to a hypothetical ferri-Tschermak's molecule CaFe3+ SiO6 in which MgSi of diopside is replaced by two Fe32 ions2,3.

Journal ArticleDOI
TL;DR: It was proposed that the conformational constraint exerted by the loss of the α-β subunit contacts in the β chains and the steric hindrance caused by frozen media might be responsible for the proposed bonding of the distal group directly to the heme iron.

Patent
30 Nov 1971
TL;DR: In this article, an improved method of making a ferrous ion-containing, heat absorbing glass article is disclosed, where the improvement resides in incorporating iron and tin in the glass, and establishing and maintaining during the glass melting, refining and forming period at least 80 percent of the iron in glass in the ferrous state.
Abstract: An improved method of making a ferrous ion-containing, heat absorbing glass article is disclosed. The improvement resides in incorporating iron and tin in the glass, and establishing and maintaining during the glass melting, refining and forming period at least 80 percent of the iron in the glass in the ferrous state. Further, sufficient tin is maintained in the stannous state to act as an internal reducing agent to prevent oxidation of the ferrous ion to the ferric species in a subsequent glass reheating step.

Journal ArticleDOI
TL;DR: Kinetics of radioactive iron transport were examined in three strains of Bacillus megaterium and certain characteristics of transport from both ferric hydroxamates and FeCl(3) suggest that iron uptake was an active process.
Abstract: Kinetics of radioactive iron transport were examined in three strains of Bacillus megaterium. In strain ATCC 19213, which secretes the ferric-chelating secondary hydroxamic acid schizokinen, 59Fe3+ uptake from 59FeCl3 or the ferric hydroxamate Desferal-59Fe3+ was rapid and reached saturation within 3 min. In strain SK11, which does not secrete schizokinen, transport from 59FeCl3 was markedly reduced; the two ferric hydroxamates Desferal-59Fe3+ or schizokinen-59Fe3+ increased both total 59Fe3+ uptake and the 59Fe3+ appearing in a cellular trichloroacetic acid-insoluble fraction, although 10 min was required to reach saturation. Certain characteristics of transport from both ferric hydroxamates and FeCl3 suggest that iron uptake was an active process. The growth-inhibitory effect of aluminum on strain SK11 was probably due to the formation of nonutilizable iron-aluminum complexes which blocked uptake from 59FeCl3. Desferal or schizokinen prevented this blockage. A strain (ARD-1) resistant to the ferric hydroxamate antibiotic A22765 was isolated from strain SK11. Strain ARD-1 failed to grow with Desferal-Fe3+ as an iron source, and it was unable to incorporate 59Fe3+ from this source. Growth and iron uptake in strain ARD-1 were similar to strain SK11 with schizokinen-Fe3+ or the iron salt as sources. It is suggested that the ferric hydroxamates, or the iron they chelate, may be transported by a special system which might be selective for certain ferric hydroxamates. Strain ARD-1 may be unable to recognize both the antibiotic A22765 and the structurally similar chelate Desferal-Fe3+, while retaining its capacity to utilize schizokinen-Fe3+.

Journal ArticleDOI
TL;DR: Ferrous compounds did not cause rancidity in whole milk as discussed by the authors, but they did cause definite oxidized flavor when added to raw whole milk before pasteurization, and this off-flavor was markedly reduced by deacrating the milk before adding the iron.


Journal ArticleDOI
TL;DR: It is concluded that the conformation of the prosthetic group is dependent upon the nature of the detergent used, the age of the preparation, and the valence state of heme a, whereas oxidized oxidase seems to be more or less insensitive to both.

Journal ArticleDOI
TL;DR: In this article, the interaction of various exogenous ligands (nitrite, hydroxylamine, cyanide, azide, imidazole, fluoride, chloride, ammonia, histidine or Tris) on the oxidation-reduction states of cytochrome c 3 was studied by low-temperature EPR.

Journal ArticleDOI
TL;DR: In this article, a reaction mechanism for radiolytic degradation of F in aqueous solution has been described, and the effects of ferrous ion and methanol on the course of radiolysis were also investigated.

Patent
13 Sep 1971
TL;DR: In this paper, the authors proposed a process in which the sulfuric acid leaching of oxidic titaniferous ironcontaining ironcontaining ore is coordinated with the leaching process of lateritic nickel ores, such that the iron sulfate solution resulting from the titanium leach is employed as a leaching solution for the nickel ore by utilizing the hydrolysis of ferric sulfate under superatmospheric pressure and elevated temperature to regenerate free sulfuric acids in situ for leaching the ore, whereby the same leaching reagent is employed economically in the sequential leaching
Abstract: Oxidic nickel or nickel-cobalt containing materials, e.g. lateritic nickel ores, are leached at superatmospheric pressure and elevated temperature with ferrous sulfate under conditions in which the ferrous sulfate is oxidized to ferric sulfate which is caused to hydrolyze to provide free sulfuric acid for leaching the ore. The invention lends itself most suitably to a process in which the sulfuric acid leaching of oxidic titaniferous ironcontaining ore is coordinated with the leaching of oxidic nickel ore, such that the iron sulfate solution resulting from the titanium leach is employed as the leaching solution for the nickel ore by utilizing the hydrolysis of ferric sulfate under superatmospheric pressure and elevated temperature to regenerate free sulfuric acid in situ for leaching the ore, whereby the same leaching reagent is employed economically in the sequential leaching of both the titanium and nickel ores.

Journal ArticleDOI
01 Feb 1971-JOM
TL;DR: In this paper, the Bureau of Mines developed a hydro-metallurgical procedure to obtain elemental sulfur from chalcopyrite by means of the following reaction: CuFeS2 + 3FeCl3 → CuCl + 4FeCl2 + 2S.
Abstract: Smelting of copper concentrates results in the discharge of millions of tons of SO, to the atmosphere each year. Because of increasing concern with air pollution, the Bureau of Mines has developed a hydro-metallurgical procedure to obtain elemental sulfur from chalcopyrite by means of the following reaction: CuFeS2 + 3FeCl3 → CuCl + 4FeCl2 + 2S. Under optimum conditions, 99.9% of the copper and 73.7% of the iron was extracted in 2 hr from a typical mill concentrate containing ~ 75% CuFeS2 and 15% FeS2. At the same time, 70.5% of the sulfur was oxidized to the elemental form. The leach was highly selective; gangue minerals, including pyrite, were not attacked, thus accounting for the relatively low recoveries of iron and sulfur.