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1

Effectiveness of treatment of iron-deficiency anemia in infants and young children with ferrous bis-glycinate chelate.  

PubMed

Forty infants, 6 to 36 mo old, with iron-deficiency anemia (hemoglobin < 11 g/dL) were matched and assigned to two groups. One group received FeS0(4) and the other received ferrous bis-glycinate chelate at a dose of 5 mg of Fe daily per kilogram of body weight for 28 d. Both groups had significant hemoglobin increases (P < 0.001), but only the group treated with ferrous bis-glycinate chelate had significant increases (P < 0.005) in plasma ferritin. Apparent iron bioavailabilities were calculated at 26.7% for FeS0(4) and 90.9% for ferrous bis-glycinate chelate. Regression analysis indicated that absorption of both sources of iron were similarly regulated by the body according to changes in hemoglobin. We concluded that ferrous bis-glycinate chelate is the iron of choice for the treatment of infants with iron-deficiency anemia because of its high bioavailability and good regulation. PMID:11377130

Pineda, O; Ashmead, H D

2001-05-01

2

Absorption of nitric oxide into aqueous solutions of ferrous chelates accompanied by instantaneous reaction  

Microsoft Academic Search

The absorption of nitric oxide (NO) into aqueous solutions of ferrous chelates of nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), hydroxyethylenediaminetriacetic acid (HEDTA), and diethylenetriaminepentaacetic acid (DTPA) was studied in a stirred cell reactor. The absorption leads to stable ferrous NO chelates. Due to the high reaction rate, in combination with the relatively high P{sub NO} applied, the absorption rate is

J. F. Demmink; I. C. F. van Gils; A. A. C. M. Beenackers

1997-01-01

3

Ferrous iron chelating property of low-molecular weight succinoglycans isolated from Sinorhizobium meliloti.  

PubMed

Iron is an essential nutrient for nitrogen-fixing legume root nodules, and the chelation of ferrous iron plays an important role in the mobility and availability of iron to the legume. In the present study, we investigated the iron-binding properties of low-molecular weight succinoglycans isolated from the nitrogen-fixing bacterium, Sinorhizobium meliloti. The low-molecular weight succinoglycans comprising three monomers (M1-M3), four dimers (D1-D4), and six trimers (T1-T6) of the succinoglycan repeating unit were purified by various chromatographic techniques. Interestingly, the colorimetric ferrozine method showed that the succinoglycans T6, M3, and D3 demonstrated a ferrous iron chelating ability of 83, 63, and 38 % per mg, respectively. The individual binding constants were determined as 43703, 2313, and 760 M(-1) for succinoglycans T6, M3, and D3 using ultraviolet-visible spectroscopy. The complexation of succinoglycan and ferrous iron can cause structural changes, which were analyzed by circular dichroism spectroscopy. Furthermore, the complex could provide antioxidant activity through an anti-Fenton reaction. These results demonstrate that the low-molecular weight succinoglycans can effectively modulate iron biochemistry as a novel ferrous iron-acquisition system of S. meliloti. PMID:23412708

Cho, Eunae; Choi, Jae Min; Kim, Hwanhee; Tahir, Muhammad Nazir; Choi, Youngjin; Jung, Seunho

2013-02-15

4

Persulfate oxidation for in situ remediation of TCE. II. Activated by chelated ferrous ion  

Microsoft Academic Search

In situ chemical oxidation (ISCO) is a technique used to remediate contaminated soil and groundwater systems. It has been postulated that sodium persulfate (Na2S2O8) can be activated by transition metal ions such as ferrous ion (Fe2+) to produce a powerful oxidant known as the sulfate free radical (SO4?) with a redox potential of 2.6 V, which can potentially destroy organic

Chenju Liang; Clifford J Bruell; Michael C Marley; Kenneth L Sperry

2004-01-01

5

Effect of the Conformation of Polymer Chain on the Reduction Rate of Polyacrylatopentaamminecobalt(III) by Polymer-Bound Ferrous Chelates and the Excited State of Tris(Bipyridine)Ruthenium(Ii)  

Microsoft Academic Search

Electron transfer reactions of Co(NH3)5PAA (PAA = polyacrylic acid) with either the polyanionic polymer-bound ferrous chelate, FeP-SS (P-SS = vinylbenzylaminediacetate-co-styrenesulfonate) or the uncharged polymer-bound ferrous chelate, FeP-VPRo (P-VPRo = vinylbenzylaminediacetate-co-vinylpyrrolidone), and the Ru(bpy) 3 photosensitized reduction of Co(NH3)5PAA have been investigated in aqueous solutions at pH 5.4, I = 0.06 (I is ionic strength), and 25癈. For the ferrous chelate

Yoshimi Kurimura; Masahiro Saito; Kyota Hiramatsu; Yoshihiro Sairenchi

1990-01-01

6

Modulation of Wnt\\/?-catenin signaling and proliferation by a ferrous iron chelator with therapeutic efficacy in genetically engineered mouse models of cancer  

Microsoft Academic Search

Using a screen for Wnt\\/?-catenin inhibitors, a family of 8-hydroxyquinolone derivatives with in vivo anti-cancer properties was identified. Analysis of microarray data for the lead compound N-((8-hydroxy-7-quinolinyl) (4-methylphenyl)methyl)benzamide (HQBA) using the Connectivity Map database suggested that it is an iron chelator that mimics the hypoxic response. HQBA chelates Fe2+ with a dissociation constant of ?10?19 M, with much weaker binding

G S Coombs; A A Schmitt; C A Canning; A Alok; I C C Low; N Banerjee; S Kaur; V Utomo; C M Jones; S Pervaiz; E J Toone; D M Virshup

2012-01-01

7

Growth and characterization of a nonlinear optical crystal: Bisglycine hydrogen chloride  

NASA Astrophysics Data System (ADS)

Single crystals of bisglycine hydrogen chloride (BGHC), a semiorganic nonlinear optical crystal, of dimensions 13󬝰 mm3 were grown in a period of 10 days. The grown crystals were confirmed by powder XRD, FTIR and DSC studies. For the first time, the defect content present in the crystals was estimated by chemical etching studies. The results indicate that the average dislocation density is about 3.1103/cm2. The load-hardness curves for BGHC were studied over the load range 10-100 g. The UV-Vis. studies indicate that the crystal has a wide transmission range. The Kurtz powder test indicates that the second harmonic generation efficiency of BGHC is almost two times that of KDP.

Chandra, Ch. Sateesh; Krishna, N. Gopi; Raja Shekar, P. V.; Nagaraju, D.

2013-02-01

8

Recycling Municipal Ferrous Scrap.  

National Technical Information Service (NTIS)

Changes in steelmaking technology since World War II, especially since the 1960's, are impacting the traditional ferrous scrap industry. The increased demand for old scrap is due to growth in electric-arc furnace steelmaking capacity, reduced availability...

J. G. Early

1982-01-01

9

The induction of an erosive arthropathy in the guinea pig with copper II bisglycinate and its treatment with antirheumatic drugs.  

PubMed

Single intra-articular injections of copper II bisglycinate [Cu(II)gly] (30-300 micrograms) into guinea-pig knee joints induce progressive joint degradation which first appears after about 2 weeks and peaks about 12 weeks after injection. The stable complex, copper II bishistidinate (300 micrograms) was without effect. The Cu(II)gly induced syndrome has features more in common with osteoarthritis than rheumatoid arthritis in that erosion occurs in the absence of persistent synovial inflammation. The possibility that the damage may be caused by Cu(II)gly inducing free radical formation within the joint, leading to a self-perpetuating chain reaction is discussed. D-Penicillamine and other drugs were tested for their effects on the histological changes induced 4 weeks after the intra-articular injections of 100 micrograms Cu(II)gly. Few significant effects were observed and these were restricted to D-penicillamine, which caused inconsistent protection, sodium aurothiomalate which protected at a dose causing weight loss and prednisolone which exacerbated joint damage. It is concluded that the variability of the control response will need to be reduced before the model can be used for routine drug evaluation but it may be of value in the study of chronic degradative joint disease. PMID:3607376

Cashin, C H

1987-08-01

10

Chelation Therapy  

MedlinePLUS

... chelation therapy may help reopen arteries blocked by mineral deposits, a condition called atherosclerosis or hardening of ... several years. Because the therapy removes some important minerals from the body, patients often receive high-dose ...

11

21 CFR 184.1315 - Ferrous sulfate.  

Code of Federal Regulations, 2013 CFR

... O, CAS Reg. No. 7782-63-0) is prepared by the action of sulfuric acid on iron. It occurs as pale, bluish-green crystals or granules. Progressive heating of ferrous sulfate heptahydrate produces ferrous sulfate (dried). Ferrous...

2013-04-01

12

Study of Vitamins and Dietary Supplements Containing Ferrous Fumarate and Ferrous Sulfate Using Moessbauer Spectroscopy  

SciTech Connect

A study of several samples of vitamins and dietary supplements containing ferrous fumarate and ferrous sulfate was carried out using Moessbauer spectroscopy with a high velocity resolution. A presence of ferrous and ferric impurities was revealed. Small variations of Moessbauer hyperfine parameters were found for both ferrous fumarates and ferrous sulfates in the investigated medicines.

Oshtrakh, M. I. [Faculty of Physical Techniques and Devices for Quality Control, Physical-Technical Department, Ural State Technical University-UPI, Ekaterinburg, 620002 (Russian Federation); Novikov, E. G.; Semionkin, V. A. [Faculty of Physical Techniques and Devices for Quality Control, Physical-Technical Department, Ural State Technical University-UPI, Ekaterinburg, 620002 (Russian Federation); Faculty of Experimental Physics, Physical-Technical Department, Ural State Technical University-UPI, Ekaterinburg, 620002 (Russian Federation); Dubiel, S. M. [Faculty of Physics and Computer Science, AGH University of Science and Technology, PL-30-059 Krakow (Poland)

2010-07-13

13

21 CFR 582.5308 - Ferrous gluconate.  

Code of Federal Regulations, 2013 CFR

...AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 搂 582.5308 Ferrous gluconate. (a) Product. Ferrous gluconate. (b)...

2013-04-01

14

21 CFR 582.5315 - Ferrous sulfate.  

Code of Federal Regulations, 2013 CFR

...AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 搂 582.5315 Ferrous sulfate. (a) Product. Ferrous sulfate. (b)...

2013-04-01

15

Iron Produced from Recycled Municipal Ferrous Waste.  

National Technical Information Service (NTIS)

Production of gray iron from magnetically separated municipal ferrous waste was investigated. Pig iron formed from the ferrous waste was melted in a local foundry together with regular charge materials to make gray iron. Tensile fracture tests of the cast...

M. A. Imam C. M. Gilmore E. A. H. Purcell

1981-01-01

16

21 CFR 184.1308 - Ferrous gluconate.  

Code of Federal Regulations, 2013 CFR

...6047-12-7) is a fine yellowish-gray or pale greenish-yellow powder or granules. It is prepared by reacting hot solutions of barium or calcium gluconate with ferrous sulfate or by heating freshly prepared ferrous carbonate with gluconic acid in aqueous...

2013-04-01

17

Evaluation of CYP450 inhibitory effects and steady-state pharmacokinetics of genistein in combination with cholecalciferol and citrated zinc bisglycinate in postmenopausal women  

PubMed Central

Background The combination of genistein 27 mg, cholecalciferol 200 IU, citrated zinc bisglycinate (4 mg elemental zinc) 20 mg per capsule in Fosteum, a prescription medical food regulated by the FDA and indicated for the dietary management of osteopenia and osteoporosis, was tested for drug interactions and to determine the pharmacokinetic profile for genistein, the principal bone-modulating ingredient in the product. Methods In vitro human liver microsome cytochrome P450 (CYP450) assays were used to test the product for potential drug interactions with the isoforms 1A2, 2C8, 2C9, 2C19, 2D6, and 3A4. Due to specific 2C8 and 2C9 inhibition, a steady-state pharmacokinetic study was performed to assess serum genistein concentrations by high-pressure liquid chromatography-coupled mass spectroscopy in healthy fasting (n = 10) and fed (n = 10) postmenopausal women. Results The product showed minimal inhibition of 1A2, 2C19, 2D6, and 3A4, exhibiting IC50 > 10 ?M, but 2C8 and 2C9 yielded IC50 of 2.5 ?M and 2.8 ?M, respectively, concentrations which are theroretically achievable when dosing the product twice daily. After seven days of administration in a steady-state pharmacokinetic study, significant differences were found for unconjugated genistein (including free and protein-bound), regarding time to peak concentration (1.88 1.36 hours), maximum concentration reached (0.052 0.055 ?M), elimination half-life (2.3 1.6 hours), and area under the concentration-time curve (53.75 17.59 ng hour/mL) compared with results for total genistein (including glucuronidated and sulfonated conjugates) time to peak concentration (2.22 1.09 hours), maximum concentration reached (2.95 1.64 ?M), elimination half-life (10.4 4.1 hours), and area under the concentration-time curve (10424 6290 ng hour/mL) in fasting subjects. Coadministration of food tended to extend the time and extent of absorption as well as slow elimination of genistein, but not in a statistically significant manner. Conclusion Because the serum genistein concentrations achieved during pharmacokinetic testing at therapeutic doses were well below those required for enzyme inhibition in the in vitro liver microsome assays, these results indicate a low potential for drug interactions.

Burnett, Bruce P; Pillai, Lakshmi; Bitto, Alessandra; Squadrito, Francesco; Levy, Robert M

2011-01-01

18

Chelation in Metal Intoxication  

PubMed Central

Chelation therapy is the preferred medical treatment for reducing the toxic effects of metals. Chelating agents are capable of binding to toxic metal ions to form complex structures which are easily excreted from the body removing them from intracellular or extracellular spaces. 2,3-Dimercaprol has long been the mainstay of chelation therapy for lead or arsenic poisoning, however its serious side effects have led researchers to develop less toxic analogues. Hydrophilic chelators like meso-2,3-dimercaptosuccinic acid effectively promote renal metal excretion, but their ability to access intracellular metals is weak. Newer strategies to address these drawbacks like combination therapy (use of structurally different chelating agents) or co-administration of antioxidants have been reported recently. In this review we provide an update of the existing chelating agents and the various strategies available for the treatment of heavy metals and metalloid intoxications.

Flora, Swaran J.S.; Pachauri, Vidhu

2010-01-01

19

Ferrous Pipeline Corrosion Processes, Detection, and Mitigation.  

National Technical Information Service (NTIS)

The purpose of this program was to determine the current state-of-the-art of corrosion of ferrous pipelines. This included corrosion mechanisms, frequency and causes of corrosion failure, corrosion mitigation, corrosion detection, and inspection of standa...

1971-01-01

20

Legionella pneumophila feoAB promotes ferrous iron uptake and intracellular infection.  

PubMed

In order to determine the role of ferrous iron transport in Legionella pathogenesis, we identified and mutated the feoB gene in virulent Legionella pneumophila strain 130b. As it is in Escherichia coli, the L. pneumophila feoB gene was contained within a putative feoAB operon. L. pneumophila feoB insertion mutants exhibited decreased ferrous but not ferric iron uptake compared to the wild type. Growth on standard buffered charcoal yeast extract agar or buffered yeast extract broth was unaffected by the loss of L. pneumophila FeoB. However, the L. pneumophila feoB mutant had a reduced ability to grow on buffered charcoal yeast extract agar with a reduced amount of its usual iron supplementation, a phenotype that could be complemented by the addition of feoB in trans. In unsupplemented buffered yeast extract broth, the feoB mutant also had a growth defect, which was further exacerbated by the addition of the ferrous iron chelator, 2,2'-dipyridyl. The feoB mutant was also 2.5 logs more resistant to streptonigrin than wild-type 130b, confirming its decreased ability to acquire iron during extracellular growth. Decreased replication of the feoB mutant was noted within iron-depleted Hartmannella vermiformis amoebae and human U937 cell macrophages. The reduced intracellular infectivity of the feoB mutant was complemented by the introduction of a plasmid containing feoAB. The L. pneumophila feoB gene conferred a modest growth advantage for the wild type over the mutant in a competition assay within the lungs of A/J mice. Taken together, these results indicate that L. pneumophila FeoB is a ferrous iron transporter that is important for extracellular and intracellular growth, especially in iron-limited environments. These data represent the first evidence for the importance of ferrous iron transport for intracellular replication by a human pathogen. PMID:12228295

Robey, Marianne; Cianciotto, Nicholas P

2002-10-01

21

Heterocyclic dithiocarbazate iron chelators: Fe coordination chemistry and biological activity.  

PubMed

The iron coordination and biological chemistry of a series of heterocyclic dithiocarbazate Schiff base ligands is reported with regard to their activity as Fe chelators for the treatment of Fe overload and also cancer. The ligands are analogous to tridentate heterocyclic hydrazone and thiosemicarbazone chelators we have studied previously which bear NNO and NNS donor sets. The dithiocarbazate Schiff base ligands in this work also are NNS chelators and form stable low spin ferric and ferrous complexes and both have been isolated. In addition an unusual hydroxylated ligand derivative has been identified via an Fe-induced oxidation reaction. X-ray crystallographic and spectroscopic characterisation of these complexes has been carried out and also the electrochemical properties have been investigated. All Fe complexes exhibit totally reversible Fe(III/II) couples in mixed aqueous solvents at potentials higher than found in analogous thiosemicarbazone Fe complexes. The ability of the dithiocarbazate Schiff base ligands to mobilise Fe from cells and also to prevent Fe uptake from transferrin was examined and all ligands were effective in chelating intracellular Fe relative to known controls such as the clinically important Fe chelator desferrioxamine. The Schiff base ligands derived from 2-pyridinecarbaldehyde were non-toxic to SK-N-MC neuroepithelioma (cancer) cells but those derived from the ketones 2-acetylpyridine and di-2-pyridyl ketone exhibited significant antiproliferative activity. PMID:22362375

Basha, Maram T; Chartres, Jy D; Pantarat, Namfon; Ali, Mohammad Akbar; Mirza, Aminul Huq; Kalinowski, Danuta S; Richardson, Des R; Bernhardt, Paul V

2012-02-24

22

Non-ferrous metal data yearbook 1986  

SciTech Connect

Non-Ferrous Metal Data Yearbook has been published annually since 1920. It contains data on metals production for five comparative years and has over 180 statistical tables for (1) imports and exports, (2) mine, smelter, and refined production, (3) inventory tonnages, and (4) listed prices for each metal. Significant non-ferrous metals include copper, lead, zinc, aluminum, silver, gold, antimony, cadmium, magnesium, molybdenum, cobalt, nickel, platinum, selenium, tellurium, titanium, tin, and uranium. Included in the yearbook is an extensive listing of the names, and in some cases, addresses of major producers, smelters, and refiners.

Not Available

1986-01-01

23

Ferrous Powder Metal Preform Forging Methods.  

National Technical Information Service (NTIS)

The research is designed to examine the three ferrous powder metal preform forging methods currently under consideration by the U.S. Army. The examination will answer the following question: which method is best for a particular complexity of parts. One o...

M. A. Perlman

1975-01-01

24

21 CFR 73.160 - Ferrous gluconate.  

Code of Federal Regulations, 2013 CFR

...gluconate is the ferrous gluconate defined in the Food Chemicals Codex, 3d Ed. (1981), pp. 122-123, which is incorporated...shall meet the specifications given in the Food Chemicals Codex, 3d Ed. (1981), which is incorporated by reference. The...

2013-04-01

25

Photo and thermal reactions of ferrous hydroxide  

NASA Astrophysics Data System (ADS)

The reactions of ferrous ion near neutral pH are of interest because of its known presence in the Archaean oceans. We have confirmed the long wavelength ultraviolet photochemical and the thermal reactions of ferrous hydroxide to form hydrogen. We have shown that a claim of the reduction of carbon dioxide to formaldehyde at neutral pH is mistaken. By the use of14C labelled compounds, we have found that less than 1 ppm of carbon dioxide is reduced to formaldehyde and less than 10 ppm of formate ion is so reduced. The thermal reaction to form hydrogen has a small activation energy of 7 kcal mole-1. We conclude that thermal and photochemical formation of hydrogen from ferrous ion in the Archaean ocean could be comparable at pH 8 9. At lower pH, toward its limit at pH 5, the photochemical reaction would predominate. Both the thermal and photochemical reactions are specific for ferrous hydroxide, being far slower for the phosphate (>50- and 7-fold) and the bicarbonate (2- and 30-fold) complexes.

Mauzerall, David; Borowska, Zofia; Zielinski, Irene

1993-04-01

26

Metallic Recovery and Ferrous Melting Processes  

Microsoft Academic Search

The effects of melting atmosphere and charge material type on the metallic and alloy recovery of ferrous charge materials were investigated in two sets of experiments (Tasks 1 and 2). In addition, thermodynamic studies were performed (Task 3) to determine the suitability of ladle treatment for the production of ductile iron using scrap charge materials high in manganese and sulfur.

Luis Trueba

2004-01-01

27

A comparison of the bioavailability of ferrous fumarate and ferrous sulfate in non-anemic Mexican women and children consuming a sweetened maize and milk drink  

Microsoft Academic Search

Background\\/Objectives:Ferrous fumarate is recommended for the fortification of complementary foods based on similar iron absorption to ferrous sulfate in adults. Two recent studies in young children have reported that it is only 30% as well absorbed as ferrous sulfate. The objective of this study was to compare iron absorption from ferrous fumarate and ferrous sulfate in infants, young children and

M Harrington; C Hotz; C Zeder; G O Polvo; S Villalpando; M B Zimmermann; T Walczyk; J A Rivera; R F Hurrell

2011-01-01

28

Recycling ferrous and nonferrous waste streams with FASTMET  

NASA Astrophysics Data System (ADS)

In metals processing, residue streams are routinely generated containing recoverable metallic compounds. These metallics represent both valuable materials and potential disposal problems to the producer. Midrex, primarily involved in ferrous conversion for many years, has developed a variety of new processing techniques for ferrous and non-ferrous recovery. The processing technologies involve either shaft or rotary hearth furnaces, and can be both hydrocarbon or coal based. Recent developments have included conversion studies for ferrous and non-ferrous residual streams that are energy efficient and environmentally friendly. The technologies to be presented, predominantly coal based, include FASTMET, FASTMELT, and Itmk3.

McClelland, James M.; Metius, Gary E.

2003-08-01

29

Chelation Therapy for Heart Disease  

MedlinePLUS

... up Definition Chelation therapy long a treatment for mercury and lead poisoning isn't a proven treatment ... therapy is a proven treatment for lead or mercury poisoning. Some doctors think that chelation therapy could ...

30

Liposome encapsulation of chelating agents  

DOEpatents

A method for transferring a chelating agent across a cellular membrane by encapsulating the charged chelating agent within liposomes and carrying the liposome-encapsulated chelating agent to the cellular membrane where the liposomes containing the chelating agent will be taken up by the cells, thereby transferring the chelating agent across the cellular membrane. A chelating agent can be introduced into the interior of a cell of a living organism wherein the liposomes will be decomposed, releasing the chelating agent to the interior of the cell. The released chelating agent will complex intracellularly deposited toxic heavy metals, permitting the more soluble metal complex to transfer across the cellular membrane from the cell and subsequently be removed from the living organism.

Rahman, Yueh Erh (Downers Grove, IL)

1976-01-13

31

Electron microscopy investigations of ferrous martensites  

Microsoft Academic Search

This paper is concerned with electron metallography of bcc or bet ferrous martensite in which particular attention is paid\\u000a to, the characterization of substructures., The transformation substructure is complex and new results are reported on multiple\\u000a {112} twinning. The factors controlling the martensitic substructure are evaluated and it is concluded that the strength and\\u000a deformation, characteristics of martensite are the

Gareth Thomas

1971-01-01

32

Ferrous sulfate adsorption by activated charcoal.  

PubMed

Although activated charcoal is thought to not appreciably adsorb iron salts, previous in vitro work indicates some adsorption of iron. This study characterized the adsorptive capacity of activated charcoal for ferrous sulfate at 3 pH environments. Langmuir adsorption isotherms were determined with a fixed amount of iron in the reaction vessels. Activated charcoal USP (20, 40, 60, 80, 100, or 120 mg) was placed in plastic tubes to which were added 1 of 3 different simulated gastrointestinal fluids (pH = 1.5, 4.5, or 7.5) and 1.49% ferrous sulfate in water. The reaction vessels were agitated and immersed in a water bath at 37 C for 30 min. Each series was performed in triplicate. Following temperature eQuilibration filtration yielded an aliquot that was assayed for iron by atomic absorption spectrophotometry. Adsorptive capacities (mean +/- SD) of activated charcoal for ferrous sulfate (mg elemental iron/g charcoal) at pH 4.5 (102.96+/-4.49) and pH 7.5 (100.94+/-19.02) were higher (P<0.01) than at pH 1.5 (-0.01+/-0.26). At pH 1.5 iron was not appreciably adsorbed by activated charcoal. Activated charcoal adsorbed ferrous sulfate to a greater extent at pH environments where iron is typically absorbed from the gastrointestinal tract. These results indicate that activated charcoal may prove an effective therapy for acute iron poisoning and further investigation is warranted. PMID:11205069

Chyka, P A; Butler, A Y; Herman, M I

2001-02-01

33

Removal of copper from ferrous scrap  

DOEpatents

A process for removing copper from ferrous or other metal scrap in which the scrap is contacted with a polyvalent metal sulfide slag in the presence of an excess of copper-sulfide forming additive to convert the copper to copper sulfide which is extracted into the slag to provide a ratio of copper in the slag to copper in the metal scrap of at least about 10.

Blander, M.; Sinha, S.N.

1987-07-30

34

Ferrous iron oxidation by anoxygenic phototrophic bacteria  

NASA Astrophysics Data System (ADS)

NATURAL oxidation of ferrous to ferric iron by bacteria such as Thiobacillus ferrooxidans or Gallionella ferruginea1, or by chemical oxidation2,3 has previously been thought always to involve molecular oxygen as the electron acceptor. Anoxic photochemical reactions4-6 or a photobiological process involving two photosystems7-9 have also been discussed as mechanisms of ferrous iron oxidation. The knowledge of such processes has implications that bear on our understanding of the origin of Precambrian banded iron formations10-14. The reducing power of ferrous iron increases dramatically at pH values higher than 2-3 owing to the formation of ferric hydroxy and oxyhydroxy compounds1,2,15 (Fig. 1). The standard redox potential of Fe3+/Fe2+ (E0 = +0.77 V) is relevant only under acidic conditions. At pH 7.0, the couples Fe(OH)3/Fe2+ (E'0 = -0.236V) or Fe(OH)3 + HCO-3FeCO3 (E'0 = +0.200 V) prevail, matching redox potentials measured in natural sediments9,16,17. It should thus be possible for Fe(n) around pH 7.0 to function as an electron donor for anoxygenic photosynthesis. The midpoint potential of the reaction centre in purple bacteria is around +0.45 V (ref. 18). Here we describe purple, non-sulphur bacteria that can indeed oxidize colourless Fe(u) to brown Fe(in) and reduce CO2 to cell material, implying that oxygen-independent biological iron oxidation was possible before the evolution of oxygenic photosynthesis.

Widdel, Friedrich; Schnell, Sylvia; Heising, Silke; Ehrenreich, Armin; Assmus, Bernhard; Schink, Bernhard

1993-04-01

35

Pressurized molten ferrous metal chemical reactor  

SciTech Connect

Research is in progress to develop a liquid ferrous metal chemical reactor to produce valuable products from petroleum refining waste and to achieve totally contained destruction of toxic chemicals. The work is an extension of the Hymelt{trademark} Process (patent pending) developed by the Ashland Petroleum Company. Materials to be processed, such as hydrocarbons, are fed into a crucible of molten iron at 1,600 C. The material decomposes, evolving hydrogen gas and combining carbon with the iron to form molten steel. Research is being pursued as a collaborative effort to Ashland Petroleum Company, Westinghouse Savannah River Company, Houston Advanced Research Center, and others.

Randolph, H.W.; Malone, D.P.; Margrave, J.L. [Westinghouse Savannah River Technology Center, Aiken, SC (United States)]|[Ashland Petroleum Co., Houston, TX (United States)]|[Rice Univ., Houston, TX (United States). Dept. of Chemistry

1995-04-01

36

METHOD OF REDUCING PLUTONIUM WITH FERROUS IONS  

DOEpatents

A process is presented for separating hexavalent plutonium from fission product values. To a nitric acid solution containing the values, ferrous ions are added and the solution is heated and held at elevated temperature to convert the plutonium to the tetravalent state via the trivalent state and the plutonium is then selectively precipitated on a BiPO/sub 4/ or LaF/sub 3/ carrier. The tetravalent plutonium formed is optionally complexed with fluoride, oxalate, or phosphate anion prior to carrier precipitation.

Dreher, J.L.; Koshland, D.E.; Thompson, S.G.; Willard, J.E.

1959-10-01

37

Feo Transport of Ferrous Iron into Bacteria  

Microsoft Academic Search

Summary牋Bacteria commonly utilise a unique type of transporter, called Feo, to specifically acquire the ferrous (Fe2+) form of iron from their environment. Enterobacterial Feo systems are composed of three proteins: FeoA, a small, soluble\\u000a SH3-domain protein probably located in the cytosol; FeoB, a large protein with a cytosolic N-terminal G-protein domain and\\u000a a C-terminal integral inner-membrane domain containing two 慓ate

Micha雔 L. Cartron; Sarah Maddocks; Paul Gillingham; C. Jeremy Craven; Simon C. Andrews

2006-01-01

38

Kinetic measurement of biological oxidation of ferrous iron at low ferric to ferrous ratios in a controlled potential batch reactor  

Microsoft Academic Search

Traditionally, the kinetics of microbial ferrous iron oxidation have been studied in continuous or in batch culture. Both methods have drawbacks: in continuous culture experiments have to be repeated at a number of dilution rates to cover the entire spectrum of ferrous to ferric ratios, which is time-consuming. Furthermore, experiments at very low ferric-to-ferrous ratios require high dilution rates which

Thierry Kamunga Kazadi; Jochen Petersen

2008-01-01

39

Natural chelates for radionuclide decorporation  

DOEpatents

This invention relates to the method and resulting chelates of desorbing a radionuclide selected from thorium, uranium, and plutonium containing cultures in a bioavailable form involving pseudomonas or other microorganisms. A preferred microorganism is Pseudomonas aeruginosa which forms multiple chelates with thorium in the range of molecular weight 1000 to 1000 and also forms chelates with uranium of molecular weight in the area of 100 to 1000 and 1000 to 2000.

Premuzic, E.T.

1983-08-25

40

Direct measurement of metal ion chelation in the active site of human ferrochelatase  

PubMed Central

The final step in heme biosynthesis, insertion of ferrous iron into protoporphyrin IX, is catalyzed by protoporphyrin IX ferrochelatase (E.C. 4.99.1.1). It is demonstrated that the pre-steady state human ferrochelatase (R115L) shows a stoichiometric burst of product formation and substrate consumption, consistent with a rate determining step following metal-ion chelation. Detailed analysis shows that chelation requires at least two steps, rapid binding followed by a slower (k ca. 1 s?1) irreversible step, provisionally assigned to metal ion chelation. Comparison with steady-state data reveals that the rate-determining step in the overall reaction, converting free porphyrin to free metalloporphyrin, occurs after chelation and is most probably product release. We have measured rate constants for significant steps on the enzyme and demonstrate that metal-ion chelation, with a rate constant of 0.96 s?1, is around 10 times faster than the rate determining step in the steady-state (kcat 0.1 s?1). The effect of an additional E343D mutation is apparent at multiple stages in the reaction cycle with a seven fold drop in kcat and three fold drop in kchel. This conservative mutation primarily affects events occurring after metal ion chelation. Further evaluation of structure-function data on site-directed mutants will therefore require both steady state and pre-steady state approaches.

Hoggins, M.; Dailey, H.A.; Hunter, C.N.; Reid, J.D.

2008-01-01

41

Heme-mediated binding of ?-casein to ferritin: evidence for preferential ?-casein binding to ferrous iron.  

PubMed

Bovine milk ?-casein was identified as a ferritin-binding protein, and ferritin is known to be a heme-binding protein. In this study, we found that the binding of ?-casein to bovine spleen ferritin in vitro was blocked by hemin, but not by iron-free hemin (protoporphyrin IX) or zinc-protoporphyrin IX, suggesting that the presence of iron in heme play a key role in this interaction. Indeed, the binding of ?-casein to ferritin and biotinylated hemin was inhibited by adding excess ferrous ammonium sulfate (FAS). To further elucidate the binding mechanism of ?-casein to biotinylated hemin, Ferrozine and nitrilotriacetic acid (NTA) were used as ferrous and ferric iron chelators, respectively. FAS-mediated inhibition of ?-casein to biotinylated hemin was neutralized with Ferrozine, but not NTA, while FAS- as well as ferric chloride-mediated inhibition in their interaction was neutralized by NTA. The following ions also inhibited ?-casein-biotinylated hemin binding in order of potency of inhibition: FAS (Fe(2+)) < ferric chloride (Fe(3+)) < copper sulfate (Cu(2+)) < zinc sulfate (Zn(2+)) < manganese chloride (Mn(2+)) < calcium chloride (Ca(2+)) < magnesium sulfate (Mg(2+)). These results suggests that the binding of ?-casein to ferritin is heme-mediated through direct binding of ?-casein to iron in the heme on the surface of ferritin molecule, and that ?-casein preferentially binds Fe(2+) compared with any other metal ions, including Fe(3+). PMID:21732136

Usami, Aya; Tanaka, Masakazu; Yoshikawa, Yasunaga; Watanabe, Kiyotaka; Ohtsuka, Hiromichi; Orino, Koichi

2011-07-06

42

Reverse Osmosis Treatment of Concentrated Ferrous Iron Acid Mine Drainage.  

National Technical Information Service (NTIS)

A 4,000 gpd reverse osmosis unit was tested on a severely polluted ferrous iron acid mine discharge near Morgantown, West Virginia. The water recovery rate was limited to fifty percent due to membrane fouling problems. The role of ferrous iron fouling cou...

R. C. Wilmoth R. B. Scott

1970-01-01

43

21 CFR 184.1307d - Ferrous fumarate.  

Code of Federal Regulations, 2013 CFR

...of Specific Substances Affirmed as GRAS 搂 184.1307d Ferrous fumarate. (a) Ferrous fumarate (iron (II) fumarate, (C4 H2 FeO4 ), CAS Reg. No. 141-01-5) is an odorless, reddish-orange to reddish-brown powder. It may...

2013-04-01

44

46 CFR 56.60-3 - Ferrous materials.  

Code of Federal Regulations, 2012 CFR

...60-3 Ferrous materials. (a) Ferrous pipe used for salt water service must be protected against corrosion by hotdip galvanizing...percent shall not be used in welded construction, nor be shaped by oxygen-cutting process or other thermal-cutting process....

2012-10-01

45

Effect of chelating agents and spice-derived antioxidants on myoglobin oxidation in a lipid-free model system.  

PubMed

This study compared myoglobin (Mb) oxidation in lipid-free model systems containing iron and Type I (radical quenching) or Type II (metal chelating) antioxidants. Oxidation was measured as loss of oxymyoglobin (MbO(2)) during 0 to 24 h holding at 22 degrees C. Sodium tripolyphosphate (STPP) demonstrated iron-binding ability at all concentrations tested (88% and 21% added iron bound at 1 and 0.05 mg/mL, respectively). Iron chelation was observed for phytic acid only at the highest concentration (9.5% bound at 1 mg/mL phytate). Neither Type I antioxidant (rosmarinate or eugenol) demonstrated any iron chelating ability (<0.5% bound). In presence of iron, Type I antioxidants had a significant (P < 0.05) prooxidant effect (54.7% retention of MbO(2) in control, 9.5% and 37.5% retention in rosmarinate and eugenol samples, respectively). The Type II antioxidants (STPP and phytate) were more effective inhibitors (P < 0.05) of Mb oxidation than Type I antioxidants, (68.7% and 61.1% for STPP and phytate, respectively). Type I antioxidants were capable of rapid reduction of ferric iron to the ferrous form, as measured by the ferrozine assay. This strong reducing ability accounted for the prooxidant effects of rosmarinic acid and eugenol, since ferrous iron is the form associated with generation of oxygen radicals, and subsequent Mb oxidation. Type II antioxidants chelated and thus prevented the oxidizing effect of added ferrous iron. Mb oxidation can proceed rapidly (within 15 min) in the presence of iron and the absence of lipid, especially if reducing compounds such as rosmarinic acid or eugenol are also present to maintain iron in an active ferrous form. PMID:19646030

Allen, Karin; Cornforth, Daren

2009-06-01

46

Chelating agents for neurodegenerative diseases.  

PubMed

It has become apparent in the last years that metal ion homeostasis and its dysfunction which results in increased accumulation in brain, notably of copper, iron and zinc, may be associated with a number of neurodegenerative diseases, such that chelation therapy may be one therapeutic option. We briefly outline chelators currently available together with strategies to develop new chelators capable of crossing the blood-brain-barrier. The homeostasis of iron in brain together with changes in brain iron with ageing are reviewed as well as the role of iron in Parkinson's disease, and the potential of chelation therapy in PD. Copper and zinc homeostasis in brain and age associated changes are then outlined, along with a discussion of the possible involvement of Zn, Cu and Fe in Alzheimer's disease. We conclude with a brief summary of chelation therapy in AD. PMID:22489724

Ward, R J; Dexter, D T; Crichton, R R

2012-01-01

47

Ferrous iron is a significant component of bioavailable iron in cystic fibrosis airways.  

PubMed

ABSTRACT Chronic, biofilm-like infections by the opportunistic pathogen Pseudomonas aeruginosa are a major cause of mortality in cystic fibrosis (CF) patients. While much is known about P.燼eruginosa from laboratory studies, far less is understood about what it experiences in vivo. Iron is an important environmental parameter thought to play a central role in the development and maintenance of P.燼eruginosa infections, for both anabolic and signaling purposes. Previous studies have focused on ferric iron [Fe(III)] as a target for antimicrobial therapies; however, here we show that ferrous iron [Fe(II)] is abundant in the CF lung (~39牭M on average for severely sick patients) and significantly correlates with disease severity (? = -0.56, P = 0.004), whereas ferric iron does not (? = -0.28, P = 0.179). Expression of the P.燼eruginosa genes bqsRS, whose transcription is upregulated in response to Fe(II), was high in the majority of patients tested, suggesting that increased Fe(II) is bioavailable to the infectious bacterial population. Because limiting Fe(III) acquisition inhibits biofilm formation by P.燼eruginosa in various oxic in vitro systems, we also tested whether interfering with Fe(II) acquisition would improve biofilm control under anoxic conditions; concurrent sequestration of both iron oxidation states resulted in a 58% reduction in biofilm accumulation and 28% increase in biofilm dissolution, a significant improvement over Fe(III) chelation treatment alone. This study demonstrates that the chemistry of infected host environments coevolves with the microbial community as infections progress, which should be considered in the design of effective treatment strategies at different stages of disease. IMPORTANCE Iron is an important environmental parameter that helps pathogens thrive in sites of infection, including those of cystic fibrosis (CF) patients. Ferric iron chelation therapy has been proposed as a novel therapeutic strategy for CF lung infections, yet until now, the iron oxidation state has not been measured in the host. In studying mucus from the infected lungs of multiple CF patients from Europe and the United States, we found that ferric and ferrous iron change in concentration and relative proportion as infections progress; over time, ferrous iron comes to dominate the iron pool. This information is relevant to the design of novel CF therapeutics and, more broadly, to developing accurate models of chronic CF infections. PMID:23963183

Hunter, Ryan C; Asfour, Fadi; Dingemans, Jozef; Osuna, Brenda L; Samad, Tahoura; Malfroot, Anne; Cornelis, Pierre; Newman, Dianne K

2013-08-20

48

Novel polycatecholamide chelating agents  

DOEpatents

Novel polybenzamide compounds useful for in vitro or in vivo chelation are described. Formulas of the compounds are given. To prepare them polyamines are reacted with 2,3-dimethoxy benzoyl chloride unsubstituted or substituted with SO/sub 3/H, SO/sub 3/M, NO/sub 2/, CO/sub 2/H or CO/sub 2/M as desired is reacted with a polyamine in an inert solvent then demethylated with BBr/sub 3/ or BCl/sub 3/ in an inert solvent. Where compounds symmetrically substituted on the terminal N's are desired, the polyamine is first reductively alkylated by reaction with an aldehyde or ketone and the resulting Schiff base is hydrogenated.

Weitl, F.L.; Raymond, K.N.

1981-08-24

49

Role of lipid oxidation, chelating agents, and antioxidants in metallic flavor development in the oral cavity.  

PubMed

This study investigated the production of metallic flavor, which is a combination of taste and retronasal odor. Chemical reactions in the oral cavity and saliva of healthy subjects were investigated after ingesting iron and copper solutions above and near threshold levels. Significant increase in lipid oxidation (p < 0.001) occurred after metal ingestion, detected as TBARS values. Ferrous ion caused the greatest flavor sensation and lipid oxidation, followed by cupric and cuprous ions. Ferric ion did not cause metallic sensation. Occurrence of oxidation was supported by damage to salivary proteins, detected as protein-carbonyls, and by a significant increase of odorous lipid oxidation related aldehydes. Sensory evaluation demonstrated that antioxidants (vitamins E and C) minimally reduced metallic flavor but that chelating agents (EDTA and lactoferrin) removed the metallic flavor. The role of lipid oxidation is essential for the production of a metallic flavor from ingestion of ferrous, cupric, and cuprous ions. PMID:22304665

Om黵-謟bek, Pinar; Dietrich, Andrea M; Duncan, Susan E; Lee, YongWoo

2012-02-21

50

METHOD OF FORMING A PROTECTIVE COATING ON FERROUS METAL SURFACES  

DOEpatents

A method is described of protecting ferrous metal surfaces from corrosive attack by liquid metals, such as liquid bismuth or lead-bismuth alloys. The nitrogen content of the ferrous metal surface is first reduced by reacting the metal surface with a metal which forms a stable nitride. Thereafter, the surface is contacted with liquid metal containing at least 2 ppm zirconium at a temperature in the range of 550 to 1100 deg C to form an adherent zirconium carbide layer on the ferrous surface.

Schweitzer, D.G.; Weeks, J.R.; Kammerer, O.F.; Gurinsky, D.H.

1960-02-23

51

Metallic Recovery and Ferrous Melting Processes  

SciTech Connect

The effects of melting atmosphere and charge material type on the metallic and alloy recovery of ferrous charge materials were investigated in two sets of experiments (Tasks 1 and 2). In addition, thermodynamic studies were performed (Task 3) to determine the suitability of ladle treatment for the production of ductile iron using scrap charge materials high in manganese and sulfur. Task 1--In the first set of experiments, the charge materials investigated were thin steel scrap, thick steel scrap, cast iron scrap, and pig iron in the rusty and clean states. Melting atmospheres in this set of experiments were varied by melting with and without a furnace cover. In this study, it was found that neither covered melting nor melting clean (non-rusty) ferrous charge materials improved the metallic recovery over the recovery experienced with uncovered melting or rusty charge materials. However, the silicon and manganese recoveries were greater with covered melting and clean materials. Silicon and manganese in the molten iron react with oxygen dissolved in the iron from uncovered melting and oxidized iron (surface rust). Silica and manganese silicates are formed which float to the slag decreasing recoveries of silicon and manganese. Cast iron and pig iron had higher metallic recoveries than steel scrap. Carbon recovery was affected by the carbon content of the charge materials, and not by the melting conditions. Irons with higher silicon contents had higher silicon recovery than irons with lower silicon contents. Task 2--In the second set of experiments, briquetted turnings and borings were used to evaluate the effects of briquette cleanliness, carbon additions, and melting atmosphere on metallic and alloy recovery. The melting atmosphere in this set of experiments was varied by melting in air and with an argon atmosphere using the SPAL process. In this set of experiments, carbon additions to the briquettes were found to have the greatest effect on metallic and alloy recovery. The use of an argon atmosphere was also found to increase recoveries, but to a lesser extent than with carbon additions to the briquettes. Task 3--Finally, thermodynamic studies were carried out to evaluate the potential for removing manganese and sulfur from iron melts for the production of ferritic ductile iron. Thermodynamic calculations indicated that manganese and sulfur might be removed from iron melts by careful control of the temperature and slag. In laboratory tests however, it was shown that the removal of sulfur was much less successful than that indicated by the thermodynamic analyses.

Luis Trueba

2004-05-30

52

High-Temperature Defect Structure of Ferrous Oxide.  

National Technical Information Service (NTIS)

Measurements of the electrical conductivity, the thermal electromotive force, and the deviation from stoichiometry by thermogravimetry were made on ferrous oxide (wustite) single crystals as well as on polycrystalline samples in the temperature range of 9...

I. Bransky D. S. Tannhauser

1966-01-01

53

Dehydration of Ferrous Sulfates Monitored by XRD - Implications for CHEMIN  

Microsoft Academic Search

We have studied the stability of a number of ferrous sulfates and carried out XRD measurements to track their stability in a controlled environment. We report on the stability of and breakdown products of melanterite, rozenite, szomolonokite, halotrichite and romerite.

A. J. Brown; D. L. Bish; J. L. Bishop

2008-01-01

54

Dehydration of Ferrous Sulfates Monitored by XRD - Implications for CHEMIN  

NASA Astrophysics Data System (ADS)

We have studied the stability of a number of ferrous sulfates and carried out XRD measurements to track their stability in a controlled environment. We report on the stability of and breakdown products of melanterite, rozenite, szomolonokite, halotrichite and romerite.

Brown, A. J.; Bish, D. L.; Bishop, J. L.

2008-03-01

55

Evaluation of Colorimetric Methods for Measuring Reduced (Ferrous) Iron.  

National Technical Information Service (NTIS)

This technical note describes a comparative study of colorimetric methods for real-time measurements of ferrous iron in reservoir tailwaters. Two methods were evaluated: the 1,10 phenanthroline method for the Hach DR/2000 spectrophotometer (Hach Company, ...

S. P. Faulkner P. E. Hintze S. L. Ashby

1999-01-01

56

Environmental geochemistry of chelating agents and radionuclide - chelate complexes. Final report  

Microsoft Academic Search

The disposal of chelated radioactive waste is discussed. Chelating agents are used in decontamination because they form very selective and strong complexes with nuerous radionuclides. However, if environmentally-persistent chelated wastes are disposed without pretreatment to eliminate the chelating agents, increased radionuclide migration rates from the disposal sites may occur. The environmental chemistry of the three most common aminopolycarboxylic acid chelating

J. L. Means; C. A. Alexander

1980-01-01

57

Composition and process for treatment of ferrous substrates  

SciTech Connect

A composition and process for treating ferrous substrates including black plate container bodies to inhibit in-process corrosion or rusting of the surfaces thereof by contacting the ferrous substrate with aqueous acidic composition containing controlled effective amounts of aluminum, fluoride, optionally a second metal selected from the group consisting of zirconium, titanium, hafnium and mixtures thereof and hydrogen ions to provide a pH on the acid side.

King, P.F.

1985-01-29

58

Bifunctional Chelates for Metal Nuclides  

PubMed Central

The use of 搉on-standard metallic radionuclides continues to be an expanding field of investigation. Radiolabeling small molecules, peptides, proteins, and up to nano-particles are all areas of active investigation for both diagnostic and therapeutic applications. All require a common variable the need for appropriate chelation chemistry for adequate sequestration of the metallic radionuclide that is equal to the intended application. A brief overview of the array of the chelation chemistry options available to researchers and the means for their selection is provided.

Brechbiel, Martin W.

2008-01-01

59

Enhanced NO{sub x} removal in wet scrubbers using metal chelates. Final report, Volume 1  

SciTech Connect

Successful pilot plant tests of simultaneous removal of S0{sub 2} and NO{sub x} in a wet lime flue gas desulfurization system were concluded in December. The tests, at up to 1.5 MW(e) capacity, were conducted by the Cincinnati Gas and Electric Company and Dravo Lime Company for the US Department of Energy at a pilot facility at the Miami Fort station of CG&E near Cincinnati, Ohio. The pilot plant scrubbed a slipstream of flue gas from Unit 7, a 530 MW coal-fired electric generating unit. Tests were conducted in three phases between April and December. The technology tested was wet scrubbing with Thiosorbic{reg_sign} magnesium-enhanced lime for S0{sub 2} removal and simultaneous NO scrubbing with ferrous EDTA, a metal chelate. Magnesium-enhanced lime-based wet scrubbing is used at 20 full-scale high-sulfur coal-fired electric generating units with a combined capacity of 8500 NW. Ferrous EDTA reacts with nitric oxide, NO, which comprises about 95% of NO{sub x} from coal-fired boilers. In this report, although not precise, NO and NO{sub x} are used interchangably. A major objective of the tests was to combine NO{sub x} removal using ferrous EDTA, a developing technology, with SO{sub 2} removal using wet lime FGD, already in wide commercial use. If successful, this could allow wide application of this NO{sub x} removal technology.

Smith, K.; Lani, B.; Berisko, D.; Schultz, C.; Carlson, W. [Dravo Lime Co., Pittsburgh, PA (United States); Benson, L.B. [Radian Corp. (United States)

1992-12-01

60

Hydroxypyridonate Chelating Agents and Synthesis Thereof.  

National Technical Information Service (NTIS)

Chelating agents having 1-hydroxy-2-pyridinone (HOPO) and related moieties incorporated within their structures, including polydentate HOPO-substituted polyamines such as spermidine and spermine, and HOPO-substituted desferrioxamine. The chelating agents ...

K. N. Raymond R. C. Scarrow D. L. White

1985-01-01

61

Treatment of cotton textile wastewater using lime and ferrous sulfate.  

PubMed

This technical note summarizes the results of a textile wastewater treatment process aiming at the destruction of the wastewater's color by means of coagulation/flocculation techniques using ferrous sulfate and/or lime. All the experiments were run in a pilot plant that simulated an actual industrial wastewater treatment plant. Treatment with lime alone proved to be very effective in removing the color (70-90%) and part of the COD (50-60%) from the textile wastewater. Moreover, the treatment with ferrous sulfate regulating the pH in the range 9.0+/-0.5 using lime was equally effective. Finally, the treatment with lime in the presence of increasing doses of ferrous sulfate was tested successfully, however; it proved to be very costly mainly due to the massive production of solids that precipitated. PMID:12691912

Georgiou, D; Aivazidis, A; Hatiras, J; Gimouhopoulos, K

2003-05-01

62

Ferrous polycrystalline shape-memory alloy showing huge superelasticity.  

PubMed

Shape-memory alloys, such as Ni-Ti and Cu-Zn-Al, show a large reversible strain of more than several percent due to superelasticity. In particular, the Ni-Ti-based alloy, which exhibits some ductility and excellent superelastic strain, is the only superelastic material available for practical applications at present. We herein describe a ferrous polycrystalline, high-strength, shape-memory alloy exhibiting a superelastic strain of more than 13%, with a tensile strength above 1 gigapascal, which is almost twice the maximum superelastic strain obtained in the Ni-Ti alloys. Furthermore, this ferrous alloy has a very large damping capacity and exhibits a large reversible change in magnetization during loading and unloading. This ferrous shape-memory alloy has great potential as a high-damping and sensor material. PMID:20299589

Tanaka, Y; Himuro, Y; Kainuma, R; Sutou, Y; Omori, T; Ishida, K

2010-03-19

63

Iron chelators and iron toxicity  

Microsoft Academic Search

Iron chelation may offer new approaches to the treatment and prevention of alcoholic liver disease. With chronic excess, either iron or alcohol alone may individually injure the liver and other organs. In combination, each exaggerates the adverse effects of the other. In alcoholic liver disease, both iron and alcohol contribute to the production of hepatic fibrosis through their effects on

Gary M. Brittenham

2003-01-01

64

Chelate Polymers of Phenolic Resin  

Microsoft Academic Search

Chelate polymers of the resin poly[3,5-(l-carboxy-2-hydroxy phenylene)ethyiene] with such bivalent ions as copper, nickel, cobalt, zinc, manganese, and trivalent iron have been synthesized. They have been analyzed, and some of their properties have been determined. On the basis of these, a polymeric structure is assigned to the polychelates.

M. N. Patel; J. B. Patel

1983-01-01

65

Natural chelating agents for radionuclide decorporation  

SciTech Connect

This invention relates to the preparation of new, naturally produced chelating agents as well as to the method and resulting chelates of desorbing cultures in a bioavailable form involving Pseudomonas species or other microorganisms. A preferred microorganism is Pseudomonas aeruginosa which forms multiple chelates with thorium in the range of molecular weight 100-1,000 and also forms chelates with uranium of molecular weight in the area of 100-1,000 and 1,000-2,000.

Premuzic, Eugene T. (East Moriches, NY)

1988-01-01

66

Iron chelators and iron toxicity.  

PubMed

Iron chelation may offer new approaches to the treatment and prevention of alcoholic liver disease. With chronic excess, either iron or alcohol alone may individually injure the liver and other organs. In combination, each exaggerates the adverse effects of the other. In alcoholic liver disease, both iron and alcohol contribute to the production of hepatic fibrosis through their effects on damaged hepatocytes, hepatic macrophages, hepatic stellate cells, and the extracellular matrix. The pivotal role of iron in these processes suggests that chelating iron may offer a new approach to arresting or ameliorating liver injury. For the past four decades, deferoxamine B mesylate has been the only iron-chelating agent generally available for clinical use. Clinical experience with deferoxamine has demonstrated the safety and effectiveness of iron chelation for the prevention and treatment of iron overload. Determined efforts to develop alternative agents have at last resulted in the development of a variety of candidate iron chelators that are now in or near clinical trial, including (a) the hexadentate phenolic aminocarboxylate HBED [N,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid], (b) the tridentate desferrithiocin derivative 4'-OH-dadmDFT [4'-hydroxy-(S)-desazadesmethyl-desferrithiocin; (S)-4,5-dihydro-2-(2,4-dihydroxyphenyl)-4-thiazolecarboxylic acid], (c) the tridentate triazole ICL670A [CGP72 670A; 4-[3,5-bis-(hydroxyphenyl)-1,2,4-triazol-1-yl]-benzoic acid], and (d) the bidentate hydroxypyridin-4-one deferiprone [L1, CP20; 1,2-dimethyl-3-hydroxypyridin-4-one]. These agents may provide new pharmacological means of averting or ameliorating liver damage in alcoholic liver disease by binding, inactivating, and eliminating the reactive forms of iron that contribute to oxidative injury of cellular components, are involved in signal transduction, or both. PMID:12957300

Brittenham, Gary M

2003-06-01

67

40 CFR 464.30 - Applicability; description of the ferrous casting subcategory.  

Code of Federal Regulations, 2010 CFR

... Applicability; description of the ferrous casting subcategory. 464.30 Section 464.30...GUIDELINES AND STANDARDS METAL MOLDING AND CASTING POINT SOURCE CATEGORY Ferrous Casting Subcategory 搂 464.30 Applicability;...

2010-07-01

68

40 CFR 464.30 - Applicability; description of the ferrous casting subcategory.  

Code of Federal Regulations, 2011 CFR

... Applicability; description of the ferrous casting subcategory. 464.30 Section 464.30...GUIDELINES AND STANDARDS METAL MOLDING AND CASTING POINT SOURCE CATEGORY Ferrous Casting Subcategory 搂 464.30 Applicability;...

2011-07-01

69

40 CFR 464.30 - Applicability; description of the ferrous casting subcategory.  

Code of Federal Regulations, 2010 CFR

... Applicability; description of the ferrous casting subcategory. 464.30 Section 464.30...GUIDELINES AND STANDARDS METAL MOLDING AND CASTING POINT SOURCE CATEGORY Ferrous Casting Subcategory 搂 464.30 Applicability;...

2009-01-01

70

40 CFR 464.30 - Applicability; description of the ferrous casting subcategory.  

Code of Federal Regulations, 2013 CFR

... Applicability; description of the ferrous casting subcategory. 464.30 Section 464.30...STANDARDS (CONTINUED) METAL MOLDING AND CASTING POINT SOURCE CATEGORY Ferrous Casting Subcategory 搂 464.30 Applicability;...

2013-07-01

71

Kinetics of Microbially Mediated Iron Reduction: The Role of Biomass, Ferrous Inhibition, and Electron Shuttles  

NASA Astrophysics Data System (ADS)

Microbially mediated reduction of poorly crystalline iron oxides in the subsurface controls the fate and transport of many organic and inorganic contaminants and plays a role in biogeochemical nutrient cycling. Despite recent advances in understanding this important process, much remains undiscovered. In particular, the influence of biomass on iron reducing kinetics is not well understood for surface bound microbes undergoing direct electron transfer to ferric iron oxides. Nor do we understand how Fe(II) sorption to ferric iron influences this process under direct electron transfer versus transfer via redox shuttles. Accordingly, this study investigates the iron reducing kinetics and mineralogy of geobacter sulfurreducens reducing poorly crystalline iron coated sand using acetate as electron donor, with and without AQDS, an electron shuttle and humic analog. This research demonstrates that the rate of iron reduction depends logarithmically on initial biomass for surface bound geobacter, suggesting surface area limitations with increasing biomass. However, electron shuttles remove these limitations and shift the kinetics such that the rate depends linearly on biomass over the range of cell concentrations explored. This study also finds that ferrous iron inhibits the rate of reduction with or without AQDS, but has a weaker effect in the presence of AQDS, and adding an Fe(II) specific chelator removes the negative feedback mechanism altogether.

MacDonald, L. H.; Moon, H.; Jaffe, P. R.

2007-12-01

72

Ferrous iron-induced luminol chemiluminescence: a method for hydroxyl radical study  

Microsoft Academic Search

We have investigated the chemiluminescence signal of the ferrous iron in the presence of the luminol and lucigenin. Ferrous, but not ferric, iron produced a transient signal in the presence of luminol, but not lucigenin. Ferrous iron-induced luminol chemiluminescence was significantly inhibited in a concentration-dependent manner by superoxide dismutase (SOD) and catalase. Specific hydroxyl radical scavengers, mannitol and dimethyl sulfoxide

G黮鼁ar Y?ld?z; A. Tuncay Demiry黵ek

1998-01-01

73

LIMESTONE AND LIME NEUTRALIZATION OF FERROUS IRON ACID MINE DRAINAGE  

EPA Science Inventory

The U.S. Environmental Protection Agency conducted a 2-yr study on hydrated lime and rock-dust limestone neutralization of acid mine drainage containing ferrous iron at the EPA Crown Mine Drainage Control Field Site near Rivesville, West Virginia. The study investigated optimizat...

74

Ferrous Ion Sites in Angrite Pyroxenes: A M鰏sbauer Spectroscopy Study  

NASA Astrophysics Data System (ADS)

M鰏sbauer spectra of angrites D'Orbigny and Sahara 99555 show that pyroxene ferrous ion is preominantly in the M1 site, not the M2 as for Angora dos Reis. These results are consistent with IR spectral data (Burbine et al., 2001, LPS XXXII,1857).

Hoffman, E. J.

2002-03-01

75

Lung cancer in ferrous foundry workers: a review  

Microsoft Academic Search

Epidemiologic studies indicate that an increased incidence of lung cancer may be associated with specific work areas in ferrous foundries. With the exception of crane operators, who were found to have an elevated lung cancer rate in one foundry, the excess lung cancer incidence is generally confined to molders, casters, and cleaning room operators whose lung cancer risk is two-

WINIFRED G. PALMER; WILLIAM D. SCOTT

1981-01-01

76

46 CFR 56.60-3 - Ferrous materials.  

Code of Federal Regulations, 2011 CFR

(a) Ferrous pipe used for salt water service must be protected against corrosion by hotdip galvanizing or by the use of extra heavy schedule material. (b) (Reproduces 124.2.C) Carbon or alloy steel having carbon content of more than...

2011-10-01

77

Effect of Sulfide Minerals on Ferrous Alloy Grinding Media Corrosion.  

National Technical Information Service (NTIS)

The U.S. Bureau of Mines determined the effect of common sulfide minerals on the corrosion rates of various types of ferrous alloy grinding media. Data obtained from the study will aid in determining the contribution of any electrochemical reactions betwe...

A. E. Isaacson

1989-01-01

78

FATIGUE CRACK INITIATION AND PROPAGATION IN FERROUS POWDER METALLURGY ALLOYS  

Microsoft Academic Search

Many of the targeted applications for powder metallurgy materials, particularly in the automotive industry, undergo cyclic loading. It is, therefore, essential to examine the fatigue mechanisms in these materials. The mechanisms of fatigue crack initiation and propagation in ferrous powder metallurgy components have been investigated. The fatigue mechanisms are controlled primarily by the inherent porosity present in these materials. Since

S. J. Polasik; J. J. Williams; N. Chawla; K. S. Narasimhan

79

Cu(II) - Catalyzed Hydrazine Reduction of Ferrous Nitrate  

SciTech Connect

This report discusses the results of a study of catalyzed hydrazine reduction of ferrous nitrate. It is apparent that there is a substantial reaction between hydrazine and nitrate ion (or nitric acid) to produce HN3 during both the reduction of Fe(III) and during storage at room temperature.

Karraker, D.G.

2001-10-15

80

Anaerobic, Nitrate-Dependent Microbial Oxidation of Ferrous Iron  

PubMed Central

Enrichment and pure cultures of nitrate-reducing bacteria were shown to grow anaerobically with ferrous iron as the only electron donor or as the additional electron donor in the presence of acetate. The newly observed bacterial process may significantly contribute to ferric iron formation in the suboxic zone of aquatic sediments.

Straub, K. L.; Benz, M.; Schink, B.; Widdel, F.

1996-01-01

81

Some Linguistic Detail on Chelation  

NASA Astrophysics Data System (ADS)

The term chelate was first applied by Morgan and Drew in 1920 to describe the heterocyclic rings formed from bidentate ligands bonding to a central atom. The history of the word ch_l_ is traced from its original Greek meaning through the Latin language to its anglicized form, chela. This word has a very rich history and has been cited by both Greek (Aristotle) and Latin (Cicero, Vergil) philosophers and poets.

Haworth, Daniel T.

1998-01-01

82

Transport of iron chelators and chelates across MDCK cell monolayers: implications for iron excretion during chelation therapy  

Microsoft Academic Search

Iron chelators are effective at removing iron from the body in iron overload, but little is known about the handling of iron\\u000a chelates by the kidney. We studied the transport of deferoxamine, deferasirox, and three hydroxypyridones, and their iron\\u000a chelates, in polarized renal epithelial MDCK cells growing on Transwell inserts. Directional iron efflux was also studied\\u000a in 59Fe-loaded cells. The

Xi-Ping Huang; Jake J. Thiessen; Michael Spino; Douglas M. Templeton

2010-01-01

83

Chelators for investigating zinc metalloneurochemistry.  

PubMed

The physiology and pathology of mobile zinc signaling has become an important topic in metalloneurochemistry. To study the action of mobile zinc effectively, specialized tools are required that probe the temporal and positional changes of zinc ions within live tissue and cells. In the present article we describe the design and implementation of selective zinc chelators as antagonists to interrogate the function of mobile zinc, with an emphasis on the pools of vesicular zinc in the terminals of hippocampal mossy fiber buttons. PMID:23478014

Radford, Robert J; Lippard, Stephen J

2013-03-13

84

The spatial organisation of macromolecular metal chelates  

NASA Astrophysics Data System (ADS)

The spatial organisation of metallopolymers (macromolecular metal chelates) is analysed on three levels; local, molecular, and supermolecular. The thermodynamic features of the formation of chelates with polymeric ligands are examined and data are presented concerning the dependence of the structure of the chelate units on various factors. The principal changes which the macrochain may undergo on formation of metal chelate centres are considered. The behaviour of the macromolecular ligands and their low-molecular- mass analogues is compared on the molecular level. The principal characteristics of the formation of intramolecular and intermolecular complexes are listed and the causes of their stability are examined. The bibliography includes 125 references.

Pomogailo, Anatolii D.; Uflyand, Igor E.; Vainshtein, E. F.

1995-09-01

85

Microbial Reduction of Ferrous Arsenate: Biogeochemical Implications for Arsenic Mobilization  

SciTech Connect

In reduced aqueous environments, the presence of As in solution is a function of both biotic and abiotic mechanisms. Recent studies have demonstrated a significant release of As(III) through the microbial reduction of dissolved and mineral-bound As(V), which raises health concerns when the greater comparative mobility and toxicity of As(III) is considered. These release mechanisms do not operate in isolation but occur in concert with a number of removal processes, including secondary mineralization and sorption to other natural substrates. Thermodynamic and applied experimental studies have shown that ferrous arsenates, such as symplesite [Fe(II){sub 3}(As(V)O{sub 4}){sub 2} {center_dot} 8H{sub 2}O], may provide a significant sink for Fe(II) and As(V). In this study, the stability of a representative ferrous arsenate phase in the presence of the arsenate-reducing bacterium Shewanella sp. strain ANA-3 is examined. The reduction of ferrous arsenate by ANA-3 results in the release of aqueous As(III) and, subsequently, the progressive nucleation of a biogenic ferrous arsenite phase proximal to the microbial cells. The valence states of secondary solid-phase products were verified using X-ray absorption spectroscopy (XAS). Electron microscopy reveals that nucleation occurs on cellular exudates which may imply a role of extracellular reduction through c-type cytochromes as investigated in recent literature. These observations provide new insights into the reduction mechanisms of ANA-3 and the biogeochemical cycling of As(III) in natural systems.

Babechuk, M.; Weisener, C.G.; Fryer, B.; Paktunc, D.; Maunders, C.; (Windsor); (CCM); (McMaster U.)

2010-11-12

86

Iron-Rich Saponite (Ferrous and Ferric Forms)  

Microsoft Academic Search

Clayey fragments colored deep bluish-green are widely found in glassy rhyolitic tufts at Oya, Tochigi Prefecture. In room-air the color changes to black or gray within one hour and finally to brown in a few weeks. The fragments are composed of an intimate mixture of two kinds of smectite: a ferrous iron-rich smectite (IR) with bo : 9.300 ~; and

Norihiko Kohyama; SUSUMU SHIMODA; TOSHIO SUDO

1973-01-01

87

Environmental biogeochemistry of chelating agents and recommendations for the disposal of chelated radioactive wastes  

Microsoft Academic Search

The environmental chemistry of the three most common aminopolycarboxylic acid chelating agents, NTA (nitrilotriacetic acid), EDTA (ethylenediaminetetraacetic acid), and DTPA (diethylenetriaminepentaacetic acid) is reviewed. This review includes information on their persistence in the environment, as well as their tendency to form complexes with actinides. Data on the sorption of chelated actinides by geologic substrates and on the uptake of chelated

J. L. Means; C. A. Alexander

1981-01-01

88

Beliefs about chelation among thalassemia patients  

PubMed Central

Background Understanding patients views about medication is crucial to maximize adherence. Thalassemia is a congenital blood disorder requiring chronic blood transfusions and daily iron chelation therapy. Methods The Beliefs in Medicine Questionnaire (BMQ) was used to assess beliefs in chelation in thalassemia patients from North America and London in the Thalassemia Longitudinal Cohort (TLC) of the Thalassemia Clinical Research Network (TCRN). Chelation adherence was based on patient report of doses administered out of those prescribed in the last four weeks. Results Of 371 patients (ages 5-58y, mean 24y), 93% were transfused and 92% receiving chelation (26% deferoxamine (DFO; a slow subcutaneous infusion via portable pump), 63% oral, 11% combination). Patients expressed high 搉ecessity for transfusion (96%), DFO chelation (92%) and oral chelation (89%), with lower 揷oncern about treatment (48%, 39%, 19% respectively). Concern about oral chelation was significantly lower than that of DFO (p<0.001). Self-reported adherence to chelation was not associated with views about necessity or concerns, but negatively correlated with perceived sensitivity to DFO (Sensitive Soma scale; r=?0.23, p=0.01) and side effects of oral chelation (r=?0.14, p=0.04). High ferritin iron levels, potentially indicating lower adherence, were found in 41% of patients reporting low necessity of oral chelation compared to 24% reporting high necessity (p=0.048). Concerns about treatment were associated with lower quality of life and more symptoms of anxiety and depression. Conclusions Despite their requirement for multimodal therapy, thalassemia patients have positive views about medicine, more so than in other disease populations. Patients may benefit from education about the tolerability of chelation and strategies to effectively cope with side effects, both of which might be beneficial in lowering body iron burden. Clinicaltrials.gov identifier NCT00661804

2012-01-01

89

Ascorbate status modulates reticuloendothelial iron stores and response to deferasirox iron chelation in ascorbate-deficient rats.  

PubMed

Iron chelation is essential to patients on chronic blood transfusions to prevent toxicity from iron overload and remove excess iron. Deferasirox (DFX) is the most commonly used iron chelator in the United States; however, some patients are relatively refractory to DFX therapy. We postulated that vitamin C supplementation would improve the availability of transfusional iron to DFX treatment by promoting iron's redox cycling, increasing its soluble ferrous form and promoting its release from reticuloendothelial cells. Osteogenic dystrophy rats (n = 54) were given iron dextran injections for 10 weeks. Cardiac and liver iron levels were measured after iron loading (n = 18), 12 weeks of sham chelation (n = 18), and 12 weeks of DFX chelation (n = 18) at 75 mg/kg/day. Ascorbate supplementation of 150 ppm, 900 ppm, and 2250 ppm was used in the chow to mimic a broad range of ascorbate status; plasma ascorbate levels were 5.4 1.9, 8.2 1.4, 23.6 9.8 ?M, respectively (p < 0.0001). The most severe ascorbate deficiency produced reticuloenthelial retention, lowering total hepatic iron by 29% at the end of iron loading (p < 0.05) and limiting iron redistribution from cardiac and hepatic macrophages during 12 weeks of sham chelation. Most importantly, ascorbate supplementation at 2250 ppm improved DFX efficiency, allowing DFX to remove 21% more hepatic iron than ascorbate supplementation with 900 ppm or 150 ppm (p < 0.05). We conclude that vitamin C status modulates the release of iron from the reticuloendothelial system and correlates positively with DFX chelation efficiency. Our findings suggest that ascorbate status should be probed in patients with unsatisfactory response to DFX. PMID:22713799

Brewer, Casey; Otto-Duessel, Maya; Lykkesfeldt, Jens; Nick, Hanspeter; Wood, John C

2012-06-17

90

Metal chelate catalysts for fuel cells  

Microsoft Academic Search

A variety of metal chelates were synthesized and evaluated for their activity as oxygen cathode electrocatalysts in strong acidic electrolytes. It was found that Cobalt tetraazaanulene (CoTAA) and iron phthalocyanine (FePc) exhibit the best activity of all the metal chelates synthesized, but have very limited stability. The proposed solution to this problem is the synthesis of polymeric forms of these

R. Darby; R. White; M. Yamana; M. Tsutsue

1981-01-01

91

Enhanced NO{sub x} removal in wet scrubbers using metal chelates. Final report, Volume 2  

SciTech Connect

Successful pilot plant tests of simultaneous removal of SO{sub 2} and NO{sub x} in a wet lime flue gas desulfurization system were concluded in December. The test, at up to 1.5 MW(e) capacity, were conducted by the Cincinnati Gas and Electric Company and Dravo Lime Company for the US Department of Energy at a pilot plant facility at the Miami Fort station of CG&E near Cincinnati, Ohio. The pilot plant scrubbed a slipstream of flue gas from Unit 7 a 530 MW coal-fired electric generating unit. Tests were conducted in three phases between April and December. The technology tested was wet scrubbing with Thiosorbic{reg_sign} magnesium-enhanced lime for SO{sub 2} removal and simultaneous NO scrubbing with ferrous EDTA, a metal chelate. Magnesium-enhanced lime-based wet scrubbing is used at 20 full-scale high-sulfur coal-fired electric generating units with a combined capacity of 8500 MW. Ferrous EDTA reacts with nitric oxide, NO, which comprises about 96% of NO{sub x} from coal-fired boilers. In this report, although not precise, NO and NO{sub x} are used interchangeably. A major objective of the tests was to combine NO{sub x} removal using ferrous EDTA, a developing technology, with SO{sub 2} removal using wet lime FGD, already in wide commercial use. If successful, this could allow wide application of this NO{sub x} removal technology. Volume 2 covers: description and results of NO{sub x} removal tests; and description and results of waste characterization studies.

NONE

1992-12-01

92

Natural chelating agents for radionuclide decorporation  

DOEpatents

This invention relates to the production of metal-binding compounds useful for the therapy of heavy metal poisoning, for biological mining and for decorporation of radionuclides. The present invention deals with an orderly and effective method of producing new therapeutically effective chelating agents. This method uses challenge biosynthesis for the production of chelating agents that are specific for a particular metal. In this approach, the desired chelating agents are prepared from microorganisms challenged by the metal that the chelating agent is designed to detoxify. This challenge induces the formation of specific or highly selective chelating agents. The present invention involves the use of the challenge biosynthetic method to produce new complexing/chelating agents that are therapeutically useful to detoxify uranium, plutonium, thorium and other toxic metals. The Pseudomonas aeruginosa family of organisms is the referred family of microorganisms to be used in the present invention to produce the new chelating agent because this family is known to elaborate strains resistant to toxic metals.

Premuzic, E.T.

1985-06-11

93

Agency Response Letter GRAS Notice No. GRN 000019  

Center for Food Safety and Applied Nutrition (CFSAN)

... bisglycinate chelate; (2) subchronic toxicity studies in rats, which have been accepted for publication in a peer-reviewed journal; (3) unpublished ... More results from www.fda.gov/food/ingredientspackaginglabeling/gras

94

Combined SO{sub 2}/NO{sub x} control using ferrous{center_dot}EDTA and a secondary additive in a lime-based aqueous scrubber system  

SciTech Connect

Integration of NO{sub x} control into existing flue-gas desulfurization (FGD) systems addresses site-specific control requirements while minimizing retrofit difficulties. Argonne has studied the use of the metal-chelate additives, such as ferrous{center_dot}EDTA in various wet FGD chemistries, to promote combined SO{sub 2}/NO{sub x} scrubbing. A major process problem is oxidation of the iron to the ferric species, leading to a significant decrease in NO{sub x}-removal capability. Argonne discovered a class of organic compounds that, when used with ferrous{center_dot}EDTA in a sodium carbonate chemistry, could maintain high levels of NO{sub x} removal. However, those antioxidant/reducing agents are not effective in a lime-based chemistry, and a broader investigation of antioxidants was initiated. This paper discusses results of that investigation, which found a practical antioxidant/reducing agent capable of maintaining NO{sub x} removals of about 50% (compared with about 15% without the agent) in a lime-based FGD chemistry with FE(II){center_dot}EDTA. 5 refs., 10 figs.

Mendelsohn, M.H.; Livengood, C.D.; Harkness, J.B.L.

1991-12-01

95

Questions and Answers on Unapproved Chelation Products  

MedlinePLUS

... involves the use of certain chemicals to remove heavy metals from the body. In medicine, chelation has been ... tests that claim to detect the presence of heavy metals in urine to falsely justify the need for ...

96

High-performance chelation ion chromatography  

Microsoft Academic Search

A review of so-called high-performance chelation ion chromatography (HPCIC) is presented. The principles of this separation technique are based on exploitation of the chelation effect of stationary phases in the presence of comparatively reduced electrostatic ion-exchange interactions. The common ways to suppress ion-exchange, including increasing the ionic strength and pH of the eluent and the column temperature, are discussed. Unlike

Phil Jones; Pavel N Nesterenko

1997-01-01

97

Chelation of trace metals in nutrient solutions  

Microsoft Academic Search

The effect of chelating agents added to nutrient solutions on plants growing in these solutions was investigated. Chelating chemicals used were: 8-hydroxyquinoline (oxine), sodium diethyldithiocarbamate (carbamate), sodium 1:8 dihydroxynaphthalene 3:6 disulphonate (chromatropic salt), sodium 1-nitroso-2-naphthol 3:6 disulphonate (nitroso-R-salt), tetrahydroxyanthraquinone (quinalizarin), and hydroxy-benzoic acid (salicylic acid). Germination and seedling studies with tomato, pea, bean, corn, and radish, and water culture tests

WALTER W. HECK; LOWELL F. BAILEY

1950-01-01

98

Ferrous sulphate gel dosimetry and MRI for proton beam dose measurements  

Microsoft Academic Search

Ferrous sulphate gel dosimetry has the potential for measurement of absorbed dose distributions in proton therapy. The chemical properties of the gel are altered according to the radiation dose and these changes can be evaluated in three dimensions using MRI. The purpose of this work was to investigate the properties of a ferrous gel used with clinical proton beams. The

Sven . J. B鋍k; Joakim Medin; Peter Magnusson; Peter Olsson; Erik Grusell; Lars E. Olsson

1999-01-01

99

Study on the Effect of Water on the Formation and Pyrophoricity of Ferrous Sulfide  

Microsoft Academic Search

Rust formed by corrosion on the inner surfaces of oil tanks can react with humidity-saturated hydrogen sulfide. The reactions produce pyrophoric ferrous sulfide and can cause fire and explosions when exposed to air during production or maintenance. Water content has an important effect on both the formation and the pyrophoricity of ferrous sulfide and the effect was investigated in detail

P. Li; S. Wang; Z. Zhang; S. Zhao

2011-01-01

100

Clean ferrous casting technology research. Final technical report, September 29, 1993--December 31, 1995  

SciTech Connect

This report details results of a 30-month program to develop methods of making clean ferrous castings, i.e., castings free of inclusions and surface defects. The program was divided into 3 tasks: techniques for producing clean steel castings, electromagnetic removal of inclusions from ferrous melts, and study of causes of metal penetration in sand molds in cast iron.

Piwonka, T.S. [ed.

1996-01-01

101

Formation of zinc protoporphyrin in cultured hepatocytes: effects of ferrochelatase inhibition, iron chelation or lead.  

PubMed

The formation of zinc protoporphyrin in response to lead or iron depletion has previously been investigated in erythroid systems. Because of its possible metabolic role in non-erythroid tissue, we investigated the formation of zinc protoporphyrin in cultured hepatocytes. The effects of lead and inhibitors of ferrochelatase, the iron insertion step of heme synthesis, on the conversion of 5-aminolevulinic acid to zinc protoporphyrin, protoporphyrin and heme were compared in rat and chick embryo hepatocyte cultures. In rat cultures, zinc protoporphyrin was synthesized enzymatically by ferrochelatase, since N-methylmesoporphyrin, an inhibitor of ferrochelatase. caused 40% or greater decreases in both heme and zinc protoporphyrin accumulation and markedly stimulated protoporphyrin accumulation. In addition, chelation of ferrous iron with 2,2'-dipyridyl decreased heme accumulation by 50%, but increased ZPP accumulation by 200%. Zinc protoporphyrin formation in chick embryo hepatocytes required the addition of zinc as well as 5-aminolevulinic acid and apparently was non-enzymatic, since it was not inhibited by N-methylmesoporphyrin nor increased by iron chelation. In the presence of 5-aminolevulinic acid, lead had no effect on zinc protoporphyrin, protoporphyrin or heme accumulation in chick hepatocytes, but decreased all three in rat hepatocytes, with the decrease in protoporphyrin being far greater than that of zinc protoporphyrin or heme. These findings indicate that, in contrast to the effect of lead in erythroid tissue, it did not specifically increase zinc protoporphyrin accumulation or alter iron availability in cultured hepatocytes. PMID:9570325

Jacobs, J M; Sinclair, P R; Sinclair, J F; Gorman, N; Walton, H S; Wood, S G; Nichols, C

1998-02-01

102

Ferrous versus Ferric Oral Iron Formulations for the Treatment of Iron Deficiency: A Clinical Overview  

PubMed Central

Iron deficiency anaemia represents a major public health problem, particularly in infants, young children, pregnant women, and females with heavy menses. Oral iron supplementation is a cheap, safe, and effective means of increasing haemoglobin levels and restoring iron stores to prevent and correct iron deficiency. Many preparations are available, varying widely in dosage, formulation (quick or prolonged release), and chemical state (ferrous or ferric form). The debate over the advantages of ferrous versus ferric formulations is ongoing. In this literature review, the tolerability and efficacy of ferrous versus ferric iron formulations are evaluated. We focused on studies comparing ferrous sulphate preparations with ferric iron polymaltose complex preparations, the two predominant forms of iron used. Current data show that slow-release ferrous sulphate preparations remain the established and standard treatment of iron deficiency, irrespective of the indication, given their good bioavailability, efficacy, and acceptable tolerability demonstrated in several large clinical studies.

Santiago, Palacios

2012-01-01

103

Influence of process variables on biooxidation of ferrous sulfate by an indigenous Acidithiobacillus ferrooxidans. Part II: Bioreactor experiments  

Microsoft Academic Search

The oxidation of ferrous iron in solution using Acidithiobacillus ferrooxidans has industrial applications in the regeneration of ferric iron as an oxidant agent for the removal of hydrogen sulfide from waste gases, desulphurization of coal, leaching of non-ferrous metallic sulfides and treatment of acid mine drainage. The aim of this attempt was to increase the biooxidation rate of ferrous sulfate

S. M. Mousavi; S. Yaghmaei; A. Jafari

2007-01-01

104

Iron chelators for the treatment of cancer.  

PubMed

The study of iron chelators as anti-tumor agents is still in its infancy. Iron is important for cellular proliferation and this is demonstrated by observations that iron-depletion results in cell cycle arrest and also apoptosis. In addition, many iron chelators are known to inhibit ribonucleotide reductase, the iron-containing enzyme that is the rate-limiting step for DNA synthesis. Desferrioxamine is a well known chelator used for the treatment of iron-overload disease, but it has also been shown to possess anti-cancer activity. Another class of chelators, namely the thiosemicarbazones, have been shown to possess anti-cancer activity since the 1950's, although their mechanism(s) of action have only recently been more comprehensively elucidated. In fact, the redox activity of thiosemicarbazone iron complexes is thought to be important in mediating their potent cytotoxicity. Moreover, unlike typical iron chelators which simply act to deplete tumors of iron, several thiosemicarbazones (i.e., Bp44mT and Dp44mT) do not induce this effect, their anti-cancer efficacy being due to other mechanisms e.g., redox activity. Other reports have also shown that some thiosemicarbazones inhibit topoisomerase II?, demonstrating that this class of agents have multiple molecular targets and act by various mechanisms. The most well characterized thiosemicarbazone iron chelator in terms of its assessment in humans is 3-aminopyridine-2-carboxaldehyde thiosemicarbazone (3-AP). Observations from these clinical trials highlight the less than optimal activity of this ligand and several side effects related to its use, including myelo-suppression, hypoxia and methemoglobinemia. The mechanisms responsible for these latter effects must be elucidated and the design of the ligand altered to minimize these problems and increase efficacy. This review discusses the development of chelators as unique agents for cancer treatment. PMID:22455580

Yu, Y; Gutierrez, E; Kovacevic, Z; Saletta, F; Obeidy, P; Suryo Rahmanto, Y; Richardson, D R

2012-01-01

105

Development of a liquid ferrous metal chemical reactor  

SciTech Connect

Research is in progress to develop a liquid ferrous metal chemical reactor to produce valuable products from petroleum refining waste and to achieve totally contained destruction of toxic chemicals. The work is an extension of a patented HyMelt process developed by the Ashland Petroleum Company. Materials to be processed, such as hydrocarbons, are fed into a crucible of molten iron at 1,650 degrees centigrade. The material decomposes, evolving hydrogen gas and combining carbon with the iron to form molten steel. Research is being doe to develop a continuous process by (1) solving problems of carbonization of feed before it enters the molten metal and (2) using physics and chemistry of oxygen sparging to remove the carbon from the melt as carbon dioxide gas. Research is being pursued as a collaborative effort of Ashland Petroleum Company, Westinghouse Savannah River Company, Houston Advanced Research center, and others.

Randolph, H.W. [Westinghouse Savannah River Technology Center, Aiken SC (United States); Malone, D.P. [Ashland Petroleum Co., Houston, TX (United States). Research and Development Dept.; Margrave, J.L. [Rice Univ., Houston, TX (United States). Dept. of Chemistry

1995-04-01

106

SteelMATTER: An Interactive Website for Ferrous Metallurgy  

NSDL National Science Digital Library

SteelMATTER is a "series of interactive educational software resources aimed at helping students understand the key concepts and relationships in ferrous metallurgy." Guided Study is the main section of the site, which describes the six stages of steel production. Starting the guided study can be slightly confusing because of poor site organization; instead of taking users directly to the first stage, an interactive quiz is presented before any material is covered. However, this can easily be bypassed by clicking the Raw Materials link at the bottom of the page. From this point, the site provides a good, step-by-step overview of the processes involved in making steel. There are also numerous Java applets accessible from the main page that simulate many metallurgy processes.

2000-01-01

107

Feo--transport of ferrous iron into bacteria.  

PubMed

Bacteria commonly utilise a unique type of transporter, called Feo, to specifically acquire the ferrous (Fe2+) form of iron from their environment. Enterobacterial Feo systems are composed of three proteins: FeoA, a small, soluble SH3-domain protein probably located in the cytosol; FeoB, a large protein with a cytosolic N-terminal G-protein domain and a C-terminal integral inner-membrane domain containing two 'Gate' motifs which likely functions as the Fe2+ permease; and FeoC, a small protein apparently functioning as an [Fe-S]-dependent transcriptional repressor. We provide a review of the current literature combined with a bioinformatic assessment of bacterial Feo systems showing how they exhibit common features, as well as differences in organisation and composition which probably reflect variations in mechanisms employed and function. PMID:16718600

Cartron, Micha雔 L; Maddocks, Sarah; Gillingham, Paul; Craven, C Jeremy; Andrews, Simon C

2006-04-01

108

Iron-chelation therapy with oral chelators in patients with thalassemia major.  

PubMed

In thalassemia major (TM), without iron chelation therapy, iron-mediated free radical damage causes liver, endocrine, and myocardial toxicities. Deferoxamine has universally been the standard therapeutic option for iron chelation therapy; however, its usage is troublesome, leading to suboptimal patient compliance. In order to maximize the effectiveness of iron chelation therapy, oral iron chelators deferiprone and deferasirox constitute an important development, offering a potential to improve compliance. Although both oral drugs are effective, they have differences including different pharmacokinetics and side-effect profiles. Our retrospective evaluation of TM patients using oral chelators showed that oral chelators are effective in reducing iron overload regarding ferritin level and partially in cardiac T2* value. However, in our study side effects and discontinuation rates were unexpectedly high and close follow-up of TM patients using oral chelators should be carefully done. The variability in rate of side effects and drug discontinuation in spelenectomized patients using oral chelators suggests that spleen may have a role in pharmacokinetics of these drugs, as well. PMID:23321010

Uygun, Vedat; Kurtoglu, Erdal

2012-11-19

109

Copper Chelation in Alzheimer's Disease Protein  

NASA Astrophysics Data System (ADS)

Alzheimer's disease (AD) is a neurodegenerative disorder affecting millions of people in the U.S. AD is primarily characterized at the cellular level by densely tangled fibrils of amyloid-? protein. These protein clusters have been found in association with elevated levels of multiple transition metals, with copper being the most egregious. Interestingly, metal chelation has shown promise in attenuating the symptoms of AD in recent clinical studies. We investigate this process by constructing an atomistic model of the amyloid-?-copper complex and profile the energetic viability in each of its subsequent disassociation stages. Our results indicate that five energetic barriers must be overcome for full metal chelation. The energy barriers are biologically viable in the presence water mediated bond and proton transfer between the metal and the protein. We model the chelation reaction using a consecutive path nudged elastic band method implemented in our ab initio real-space multi-grid code to obtain a viable sequence. This reaction model details a physically consistent explanation of the chelation process that could lead to the discovery of more effective chelation agents in the treatment of AD.

Rose, Frisco; Hodak, Miroslav; Bernholc, Jerry

2013-03-01

110

Method of encapsulating polyaminopolycarboxylic acid chelating agents in liposomes  

DOEpatents

A method is provided for transferring a polyaminopolycarboxylic acid chelating agent across a cellular membrane by encapsulating the charged chelating agent within liposomes, which liposomes will be taken up by the cells, thereby transferring the chelating agent across the cellular membrane. The chelating agent is encapsulated within liposomes by drying a lipid mixture to form a thin film and wetting the lipid film with a solution containing the chelating agent. Mixing then results in the formation of a suspension of liposomes encapsulating the chelating agent, which liposomes can then be separated.

Rahman, Yueh Erh (Downers Grove, IL)

1977-11-10

111

Advances in the chemistry of metal chelate monomers  

NASA Astrophysics Data System (ADS)

This review covers the chemistry of metal chelate monomers. Depending on the character of bonding of the metal to the chelating group, all metal chelate monomers are divided into three main types: molecular chelates, inner-sphere compounds, and macrocyclic complexes. The data are systematised according to methods for preparing such compounds. Special attention is paid to the specifics of homo- and co-polymerisation of metal chelate monomers. The principal applications of metal chelate monomers and polymers based on them are considered. The bibliography includes 102 references.

Uflyand, Igor E.; Pomogailo, Anatolii D.

1991-07-01

112

Mechanism and preventive measures for die soldering during Al casting in a ferrous mold  

NASA Astrophysics Data System (ADS)

This work provides a comprehensive understanding of the reactions at the ferrous die/molten metal interface in a metal mold casting operation. The literature has shown that several important factors influence reactions at the ferrous die/molten aluminum interface, including temperature of the melt, temperature of the die, alloy chemistry of the melt and die, die surface engineering, topographical features, and coatings. This article discusses the effect of the more critical factors on soldering, based on the authors investigations. Inaddition, based on a mechanistic understanding of the interface reactions between ferrous die and molten aluminum, recommendations are given for specific processing issues to alleviate soldering during die casting of aluminum alloys.

Shankar, Sumanth; Apelian, Diran

2002-08-01

113

Heme coordination states of unfolded ferrous cytochrome C.  

PubMed

The structural changes of ferrous Cyt-c that are induced by binding to SDS micelles, phospholipid vesicles, DeTAB, and GuHCl as well as by high temperatures and changes in the pH have been studied by RR and UV-Vis absorption spectroscopies. Four species have been identified in which the native methionine-80 ligand is removed from the heme iron. This coordination site is either occupied by a histidine (His-33 or His-26) to form a 6cLS configuration, which is the prevailing species in GuHCl at pH 7.0 and ambient temperature, or remains vacant to yield a 5cHS configuration. The three identified 5cHS species differ with respect to the hydrogen-bond interactions of the proximal histidine ligand (His-18) and include a nonhydrogen-bonded, a hydrogen-bonded, and a deprotonated imidazole ring. These structural motifs have been found irrespective of the unfolding conditions used. An unambiguous spectroscopic distinction of these 5cHS species is possible on the basis of the Fe-N(imidazole) stretching vibrations, the RR bands in the region between 1300 and 1650 cm(-1), and the electronic transitions in the Soret- and Q-band regions. In acid and neutral solutions, the species with a hydrogen-bonded and a nonhydrogen-bonded His-18 prevail, whereas in alkaline solutions a configuration with a deprotonated His-18 ligand is also observed. Upon lowering the pH or increasing the temperature in GuHCl solutions, the structure on the proximal side of the heme is perturbed, resulting in a loss of the hydrogen-bond interactions of the His-18 ligand. Conversely, the hydrogen-bonded His-18 of ferrous Cyt-c is stabilized by electrostatic interactions which increase in strength from phospholipid vesicles to SDS micelles. The results here suggest that unfolding of Cyt-c is initiated by the rupture of the Fe-Met-80 bond and structural reorganizations on the distal side of the heme pocket, whereas the proximal part is only affected in a later stage of the denaturation process. PMID:16877519

Droghetti, Enrica; Oellerich, Silke; Hildebrandt, Peter; Smulevich, Giulietta

2006-07-28

114

76 FR 9810 - Agency Information Collection Activities: Comment Request for the Ferrous Metals Surveys (17 Forms)  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF THE INTERIOR Geological Survey [USGS-GX11LR000F60100] Agency Information...Activities: Comment Request for the Ferrous Metals Surveys (17 Forms) AGENCY: U.S. Geological Survey (USGS), Interior. ACTION: Notice of...

2011-02-22

115

76 FR 31357 - Agency Information Collection Activities: Comment Request for the Ferrous Metals Surveys  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF THE INTERIOR U.S. Geological Survey [USGS-GX11LR000F60100] Agency Information...Activities: Comment Request for the Ferrous Metals Surveys AGENCY: U.S. Geological Survey (USGS), Interior. ACTION: Notice of a...

2011-05-31

116

Mechanism of radiation and thermal decomposition of sulphide non-ferrous metals.  

National Technical Information Service (NTIS)

This paper deals with the non-ferrous metals sulfides in term of their radiative sensitivity, directed chances of their physical-chemical, and hence technological properties by radiation influence both on sulfide materials and on the processes with their ...

N. Mazhrenova

1998-01-01

117

Ferrous/ferric Mossbauer analysis of simulated nuclear waste glass with and without computer fitting  

SciTech Connect

Wet-chemical and /sup 57/Fe Mossbauer analyses of ferrous/ferric ratios in complex borosilicate and simple silicate glasses were compared. The results support the validity of the colorimetric wet-chemical procedure and establish a linear calibration for the Mossbauer data. The resulting correlation indicates that using area ratios from Mossbauer spectra will overestimate the proportion of ferrous iron by a factor of 1.2. The linear calibration was achieved only after statistically optimizing the peak line shape for each Mossbauer spectrum. Samples with a greater proportion of ferrous iron tended to have a greater Gaussian contribution to the peak line shape. A procedure to determine ferrous/ferric ratios from measured intensity data at three velocity locations was developed. With instrument modification, this result will lead to a substantial reduction in data collection time and the elimination of complex spectral fitting.

Goldman, D.S.; Bewley, D.E.

1985-12-01

118

Determination of ferrous oxide in chromite and chrome-magnesite refractories  

Microsoft Academic Search

Conclusions In exact analyses of chromite and chrome-magnesite refractories for the ferrous oxide content, current-flow methods of titration using either Mohr's salt or permanganate can be used. The results are better in the first case.

Ye. G. Kondrakhina

1962-01-01

119

Interactions of Hydrazine, Ferrous Sulfamate, Sodium Nitrite, and Nitric Acid in Nuclear Fuel Processing Solutions.  

National Technical Information Service (NTIS)

Hydrazine and ferrous sulfamate are used as reductants in a variety of nuclear fuel processing solutions. An oxidant, normally sodium nitrite, must frequently be added to these nitric acid solutions before additional processing can proceed. The interactio...

L. W. Gray

1977-01-01

120

Absolute Ferrous Absorption Band Strength in the Lunar Feldspathic Highlands Terrane from the Moon Mineralogy Mapper  

NASA Astrophysics Data System (ADS)

We evaluate the ferrous band strength in the feldspathic highlands terrane with M^3 data. We find that the ground truth correction delivered with the M^3 PDS archive improves consistency between data collected over different phases of the mission.

Isaacson, P. J.; Petro, N. E.; Pieters, C. M.; Besse, S.; Boardman, J. W.; Clark, R. N.; Green, R. O.; Lundeen, S.; Malaret, E.; McLaughlin, S.; Sunshine, J. M.; Taylor, L. A.; M^3 Team

2012-03-01

121

Ferrous iron oxidation by Thiobacillus ferrooxidans: inhibition with benzoic acid, sorbic acid and sodium lauryl sulfate  

SciTech Connect

Acid mine drainage is formed by the weathering or oxidation of pyritic material exposed during coal mining. The rate of pyritic material oxidation can be greatly accelerated by certain acidophilic bacteria such as Thiobacillus ferrooxidans which catalyse the oxidation of ferrous to ferric iron. A number of organic compounds, under laboratory conditions, can apparently inhibit both the oxidation of ferrous to ferric iron by T. ferrooxidans and the weathering of pyritic material by mixed cultures of acid mine drainage micro-organisms. Sodium lauryl sulphate (SLS), an anionic surfactant has proved effective in this respect. Benzoic acid, sorbic acid and SLS at low concentrations, each effectively inhibited bacterial oxidation of ferrous iron in batch cultures of T. ferrooxidans. The rate of chemical oxidation of ferrous iron in low pH, sterile, batch reactors was not substantially affected at the tested concentrations of any of the compounds.

Onysko, S.J.

1984-07-01

122

Ferrous iron oxidation by Thiobacillus ferrooxidans: inhibition with benzoic acid, sorbic acid, and sodium lauryl sulfate  

SciTech Connect

Thiobacillus ferrooxidans promote indirect oxidation of pyrite through the catalysis of the oxidation of ferrous iron to ferric iron, which is an effective oxidant of pyrite. These bacteria also may catalyze direct oxidation of pyrite by oxygen. A number of organic compounds, under laboratory conditions, can apparently inhibit both the oxidation of ferrous iron to ferric iron by T. ferrooxidans and the weathering of pyritic material by mixed cultures of acid mine drainage microorganisms. In this study, benzoic acid, sorbic acid, and sodium lauryl sulfate at low concentrations (5 to 10 mg/liter) each effectively inhibited bacterial oxidation of ferrous iron in batch cultures of Thiobacillus ferrooxidans. The rate of chemical oxidation of ferrous iron in low-pH, sterile batch reactors was not substantially affected at the tested concentrations (5 to 50 mg/liter) of any of the compounds.

Onysko, S.J.; Kleinmann, R.L.P.; Erickson, P.M.

1984-07-01

123

High Performance Liquid Chromatography of Metal Chelates  

Microsoft Academic Search

Liquid chromatography, especially ion-exchange chromatography, has been used very successfully for the separation of ionic metal chelates for many years. More recently, ion chromatography, an ion exchange method proposed by Small et al. (1) in 1975 for the determination of ionic species at low concentrations has undergone a period of rapid growth. Fritz (2) has recently published a book on

Jerome W. Olaughlin

1984-01-01

124

Chelating Versatility of Toxic Metal Resistant Microorganisms.  

National Technical Information Service (NTIS)

Thorium- and uranium-resistant strains of Pseudomonas aeruginosa when grown in high concentration of these metals (100 to 1000 ppM) in citrate- or succinate-containing media produce several chelating agents. Crude extracts of the metal-induced products, w...

E. T. Premuzic M. Lin

1985-01-01

125

Metal chelate catalysts for fuel cells  

NASA Astrophysics Data System (ADS)

Various modified forms of several organometallic chelate compounds were synthesized and tested for their activity and stability as oxygen reduction electrocatalysts in sulfuric acid electrolyte. The most active catalysts found were cobalt tetraazaannulene (CoTAA), iron phthalocyanine (FePc) and cobalt tetraphenylporphyrin (CoTPP). However, these catalysts have limited stability in strong acids.

Darby, R.; Yamana, M.; Dhar, H.; White, R.

1982-10-01

126

New Advances in Iron Chelation Therapy  

Microsoft Academic Search

The emergence of new chelators is likely to have a major impact on the treatment of thalassemia major, sickle cell disease and other hematologic disorders for which regular red cell transfusions are required either to correct severe anemia or to prevent major complications of the underlying disease. In compari- son with deferoxamine, which requires prolonged parenteral infusion to achieve negative

Alan R. Cohen

127

Development of an upconverting chelate assay  

NASA Astrophysics Data System (ADS)

We report progress on performing a cell-based assay for the detection of EGFR on cell surfaces by using upconverting chelates. An upconversion microscope has been developed for performing assays and testing optical response. A431 cells are labeled with europium DOTA and imaged using this upconverting microscope.

Xiao, Xudong; Haushalter, Jeanne P.; Kotz, Kenneth T.; Faris, Gregory W.

2005-04-01

128

Metal chelate catalysts for fuel cells  

Microsoft Academic Search

Various modified forms of several organometallic chelate compounds were synthesized and tested for their activity and stability as oxygen reduction electrocatalysts in sulfuric acid electrolyte. The most active catalysts found were cobalt tetraazaannulene (CoTAA), iron phthalocyanine (FePc) and cobalt tetraphenylporphyrin (CoTPP). However, these catalysts have limited stability in strong acids.

R. Darby; M. Yamana; H. Dhar; R. White

1982-01-01

129

Deferiprone Chelation Therapy for Thalassemia Major  

Microsoft Academic Search

Iron overload is one of the major causes of morbidity in patients with thalassemia major. Deferiprone (DFP), an orally active iron chelator, emerged from an extensive search for new drugs to treat iron overload. Comparative studies have shown that at comparable doses the efficacy of DFP in removing body iron is similar to that of desferoxamine (DFO). In retrospective and

R. Galanello; S. Campus

2009-01-01

130

Thermal Stability of Chelated Indium Activable Tracers  

SciTech Connect

The thermal stability of indium tracer chelated with organic ligands ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) was measured for reservoir temperatures of 150, 200, and 240 C. Measurements of the soluble indium concentration was made as a function of time by neutron activation analysis. From the data, approximate thermal decomposition rates were estimated. At 150 C, both chelated tracers were stable over the experimental period of 20 days. At 200 C, the InEDTA concentration remained constant for 16 days, after which the thermal decomposition occurred at a measured rate constant of k = 0.09 d{sup -1}. The thermal decomposition of InNTA at 200 C showed a first order reaction with a measured rate constant of k = 0.16 d{sup -1}. At 240 C, both indium chelated tracers showed rapid decomposition with rate constants greater than 1.8 d{sup -1}. The data indicate that for geothermal reservoir with temperatures up to about 200 C, indium chelated tracers can be used effectively for transit times of at least 20 days. These experiments were run without reservoir rock media, and do not account for concomitant loss of indium tracer by adsorption processes.

Chrysikopoulos, Costas; Kruger, Paul

1986-01-21

131

Enumeration and Detection of Anaerobic Ferrous Iron Oxidizing, Nitrate-Reducing Bacteria from Diverse European Sediments  

Microsoft Academic Search

Anaerobic, nitrate-dependent microbial oxidation of ferrous iron was recently recognized as a new type of metabolism. In order to study the occurrence of three novel groups of ferrous iron-oxidizing, nitrate-reducing bacteria (represented by strains BrG1, BrG2, and BrG3), 16S rRNA-targeted oligonucleotide probes were developed. In pure-culture experiments, these probes were shown to be suitable for fluorescent in situ hybrid- ization,

KRISTINA L. STRAUB; BERIT E. E. BUCHHOLZ-CLEVEN

1998-01-01

132

Legionella pneumophila feoAB Promotes Ferrous Iron Uptake and Intracellular Infection  

Microsoft Academic Search

In order to determine the role of ferrous iron transport in Legionella pathogenesis, we identified and mutated the feoB gene in virulent Legionella pneumophila strain 130b. As it is in Escherichia coli, the L. pneumophila feoB gene was contained within a putative feoAB operon. L. pneumophila feoB insertion mutants exhibited decreased ferrous but not ferric iron uptake compared to the

Marianne Robey; Nicholas P. Cianciotto

2002-01-01

133

Studies of Chelate Polymers. V. Chelate Polymers of Bis-Dithiocarbamic Acids and Metals.  

National Technical Information Service (NTIS)

Chelate polymers of ethylene-, hexamethylene-, pphenylene-, and p, p'-diphenylene - bis-dithiocarbamic acids with metals were obtained: divalent nickel, zinc, and cobalt, and monovalent copper. It was shown that when divalent salts of copper react with di...

A. P. Terent'ev E. G. Rukhadze V. V. Rode

1964-01-01

134

Characterization of the ferrous iron uptake system of Escherichia coli.  

PubMed

Escherichia coli has an iron(II) transport system (feo) which may make an important contribution to the iron supply of the cell under anaerobic conditions. Cloning and sequencing of the iron(II) transport genes revealed an open reading frame (feoA) possibly coding for a small protein with 75 amino acids and a membrane protein with 773 amino acids (feoB). The upstream region of feoAB contained a binding site for the regulatory protein Fur, which acts with iron(II) as a corepressor in all known iron transport systems of E. coli. In addition, a Fnr binding site was identified in the promoter region. The FeoB protein had an apparent molecular mass of 70 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was localized in the cytoplasmic membrane. The sequence revealed regions of homology to ATPases, which indicates that ferrous iron uptake may be ATP driven. FeoA or FeoB mutants could be complemented by clones with the feoA or feoB gene, respectively. PMID:8407793

Kammler, M; Sch鰊, C; Hantke, K

1993-10-01

135

Characterization of the ferrous iron uptake system of Escherichia coli.  

PubMed Central

Escherichia coli has an iron(II) transport system (feo) which may make an important contribution to the iron supply of the cell under anaerobic conditions. Cloning and sequencing of the iron(II) transport genes revealed an open reading frame (feoA) possibly coding for a small protein with 75 amino acids and a membrane protein with 773 amino acids (feoB). The upstream region of feoAB contained a binding site for the regulatory protein Fur, which acts with iron(II) as a corepressor in all known iron transport systems of E. coli. In addition, a Fnr binding site was identified in the promoter region. The FeoB protein had an apparent molecular mass of 70 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was localized in the cytoplasmic membrane. The sequence revealed regions of homology to ATPases, which indicates that ferrous iron uptake may be ATP driven. FeoA or FeoB mutants could be complemented by clones with the feoA or feoB gene, respectively. Images

Kammler, M; Schon, C; Hantke, K

1993-01-01

136

Effect of abomasal ferrous lactate infusion on phosphorus absorption in lactating dairy cows.  

PubMed

The objective of this study was to evaluate the effect of ferrous lactate infusion on postruminal P absorption in lactating dairy cows. Four ruminally cannulated lactating cows were used in a 44 Latin square design with 14 d per period. Cows were fed a basal diet containing 0.39% P, providing 100% of the calculated P requirement. On d 8 to 14 of each period, each cow was infused with 0, 200, 500, or 1,250mg of Fe/d in the form of ferrous lactate solution (ferrous lactate in 1L of double-distilled water) into the abomasum. Infusate was formulated to approximate 0, 2, 5, or 12.5mg of Fe/L in drinking water with 100L of water intake/d. Total fecal collection was conducted in the last 4 d of each period to measure nutrient digestion and excretion. Dry matter intake, milk yield, and milk composition were not affected by treatment. Digestibility of DM, NDF, and nitrogen decreased linearly with increasing ferrous lactate infusion. Infusion of ferrous lactate did not affect intake and digestibility of total P, inorganic P, or phytate P. In lactating cows, P absorption was not negatively influenced by abomasally infused ferrous lactate up to 1,250mg of Fe/d. PMID:23660146

Feng, X; Knowlton, K F; Dietrich, A D; Duncan, S

2013-05-06

137

Shortened forms of provocative lead chelation  

SciTech Connect

Shortened urinary lead collections following provocative chelation have been standardized for pediatric patients, but have not been considered adequate for adults. This study compared shortened urine collections for lead excretion post chelation with standard 24-hour collections. Thirty-five patients without known current lead exposure and with serum creatinine measurements less than 2 mg/dL were hospitalized and had provocative chelation performed as follows: One gram of CaNa2-ethylenediaminetetraacetic acid (EDTA) was administered in 250 mL of a 5% dextrose in water solution intravenously over one hour; the same dose was repeated 12 hours later. A 24-hour urine collection for lead excretion was begun at the time of initiation of the first dose. At three hours and six hours from start of first dose, each patient was instructed to void, total volume to that point was recorded, and a 10-mL aliquot was withdrawn for lead measurement. Both three-hour and six-hour urinary lead excretion following a single dose of EDTA correlated linearly with 24-hour lead excretion post chelation (r = .89 and .94, respectively). When a 24-hour level of 600 micrograms was defined as true positive the three-hour collection had a sensitivity of 76% and specificity of 95% and six-hour urinary lead excretion had 82% sensitivity and 100% specificity. Mild renal insufficiency (reflected by serum creatinine levels between 1.5 and 2.1 mg/dL) did not significantly alter the correlation between three-, six-, and 24-hour urinary post-chelation lead excretion.

Sokas, R.K.; Atleson, J.; Keogh, J.P.

1988-05-01

138

Metal oxide powder synthesized with amorphous metal chelates  

Microsoft Academic Search

Chelate powder consisting of amorphous particles was synthesized through the process in which the droplet of the chelate solution is dried in the gas phase and solidified in a moment using a splay-dry technique. To investigate the advantage of the use of amorphous chelate powder in the processing of metal oxide powder, this study provides following two routes: a conventional

H. Saitoh; R. Satoh; A. Nakamura; N. Nambu; S. Ohshio

2002-01-01

139

Chelate-assisted phytoextraction of lead from contaminated soils  

Microsoft Academic Search

Phytoextraction, a remediation strategy for lead (Pb)-contaminated soils that removes soil Pb through plant uptake and harvest, may be enhanced by use of synthetic chelates. The authors evaluated Pb desorption from four contaminated soils by seven chelates (CDTA, DTPA, EDDHA, EFTA, HEDTA, HEIDA, and NTA) at three rates. The three most effective chelates (CDTA, DTPA, and HEDTA) were used in

E. M. Cooper; J. T. Sims; S. D. Cunningham; J. W. Huang; W. R. Berti

1999-01-01

140

Thermogravimetric study of some divalent metal chelate polymers of dithiooxamide  

Microsoft Academic Search

The thermal properties of polymeric chelates of dithiooxamide with divalent copper, cobalt, zinc and nickel have been investigated. The order of thermal stability is Ni>Co?Zn>Cu, which is the same as that observed for previously studied naphthazarin and rhodizonic acid chelates. The procedural decomposition temperatures indicate that the dithiooxamide chelates, which are not aromatic, are about as stable as the aromatic

R. S. Bottei; C. P. McEachern

1974-01-01

141

Anaerobic oxidation of ferrous iron by purple bacteria, a new type of phototrophic metabolism.  

PubMed Central

Anoxic iron-rich sediment samples that had been stored in the light showed development of brown, rusty patches. Subcultures in defined mineral media with ferrous iron (10 mmol/liter, mostly precipitated as FeCO3) yielded enrichments of anoxygenic phototrophic bacteria which used ferrous iron as the sole electron donor for photosynthesis. Two different types of purple bacteria, represented by strains L7 and SW2, were isolated which oxidized colorless ferrous iron under anoxic conditions in the light to brown ferric iron. Strain L7 had rod-shaped, nonmotile cells (1.3 by 2 to 3 microns) which frequently formed gas vesicles. In addition to ferrous iron, strain L7 used H2 + CO2, acetate, pyruvate, and glucose as substrate for phototrophic growth. Strain SW2 had small rod-shaped, nonmotile cells (0.5 by 1 to 1.5 microns). Besides ferrous iron, strain SW2 utilized H2 + CO2, monocarboxylic acids, glucose, and fructose. Neither strain utilized free sulfide; however, both strains grew on black ferrous sulfide (FeS) which was converted to ferric iron and sulfate. Strains L7 and SW2 grown photoheterotrophically without ferrous iron were purple to brownish red and yellowish brown, respectively; absorption spectra revealed peaks characteristic of bacteriochlorophyll a. The closest phototrophic relatives of strains L7 and SW2 so far examined on the basis of 16S rRNA sequences were species of the genera Chromatium (gamma subclass of proteobacteria) and Rhodobacter (alpha subclass), respectively. In mineral medium, the new isolates formed 7.6 g of cell dry mass per mol of Fe(II) oxidized, which is in good agreement with a photoautotrophic utilization of ferrous iron as electron donor for CO2 fixation. Dependence of ferrous iron oxidation on light and CO2 was also demonstrated in dense cell suspensions. In media containing both ferrous iron and an organic substrate (e.g., acetate, glucose), strain L7 utilized ferrous iron and the organic compound simultaneously; in contrast, strain SW2 started to oxidize ferrous iron only after consumption of the organic electron donor. Ferrous iron oxidation by anoxygenic phototrophs is understandable in terms of energetics. In contrast to the Fe3+/Fe2+ pair (E0 = +0.77 V) existing in acidic solutions, the relevant redox pair at pH 7 in bicarbonate-containing environments, Fe(OH)3 + HCO3-/FeCO3, has an E0' of +0.2 V. Ferrous iron at pH 7 can therefore donate electrons to the photosystem of anoxygenic phototrophs, which in purple bacteria has a midpoint potential around +0.45 V. The existence of ferrous iron-oxidizing anoxygenic phototrophs may offer an explanation for the deposition of early banded-iron formations in an assumed anoxic biosphere in Archean times. Images

Ehrenreich, A; Widdel, F

1994-01-01

142

Cold-Drawn Bioabsorbable Ferrous and Ferrous Composite Wires: An Evaluation of Mechanical Strength and Fatigue Durability  

NASA Astrophysics Data System (ADS)

Yield strengths exceeding 1 GPa with elastic strains exceeding 1 pct were measured in novel bioabsorbable wire materials comprising high-purity iron (Fe), manganese (Mn), magnesium (Mn), and zinc (Zn), which may enable the development of self-expandable, bioabsorbable, wire-based endovascular stents. The high strength of these materials is attributed to the fine microstructure and fiber textures achieved through cold drawing techniques. Bioabsorbable vascular stents comprising nutrient metal compositions may provide a means to overcome the limitations of polymer-based bioabsorbable stents such as excessive strut thickness and poor degradation rate control. Thin, 125- ?m wires comprising combinations of ferrous alloys surrounding a relatively anodic nonferrous core were manufactured and tested using monotonic and cyclic techniques. The strength and durability properties are tested in air and in body temperature phosphate-buffered saline, and then they were compared with cold-drawn 316L stainless steel wire. The antiferromagnetic Fe35Mn-Mg composite wire exhibited more than 7 pct greater elasticity (1.12 pct vs 1.04 pct engineering strain), similar fatigue strength in air, an ultimate strength of more than 1.4 GPa, and a toughness exceeding 35 mJ/mm3 compared with 30 mJ/mm3 for 316L.

Schaffer, Jeremy E.; Nauman, Eric A.; Stanciu, Lia A.

2012-08-01

143

Anacardic acids and ferric ion chelation.  

PubMed

6-Pentadeca(e)nylsalicylic acids isolated from the cashew Anacardium occidentale L. (Anacardiaceae), commonly known as anacardic acids, inhibited the linoleic acid peroxidation catalyzed by soybean lipoxygenase-1 (EC 1.13.11.12, type 1) competitively without prooxidant effects. Their parent compound, salicylic acid, did not have this inhibitory activity up to 800 pm, indicating that the pentadeca(e)nyl group is an essential element to elicit the activity. The inhibition is attributed to its ability to chelate iron in the enzyme. Thus, anacardic acids chelate iron in the active site of the enzyme and then the hydrophobic tail portion slowly begins to interact with the hydrophobic domain close to the active site. Formation of the anacardic acids-ferric ion complex was detected in the ratio of 2:1 as the base peak in the negative ion electrospray ionization mass spectrometry. Hence, anacardic acids inhibit both Eox and Ered forms. PMID:18069245

Tsujimoto, Kazuo; Hayashi, Akio; Ha, Tae Joung; Kubo, Isao

144

Future of toxicology--iron chelators and differing modes of action and toxicity: the changing face of iron chelation therapy.  

PubMed

Iron (Fe) chelation therapy was initially designed to alleviate the toxic effects of excess Fe evident in Fe-overload diseases. However, the novel toxicological properties of some Fe chelator-metal complexes have shifted appreciable focus to their application in cancer chemotherapy. Redox-inactive Fe chelator complexes are well suited for the treatment of Fe-overload diseases, whereas Fe chelator complexes with high redox activity have shown promising results as chemotherapeutics against cancer. Within this perspective, we discuss the different modes of action and toxicological profiles of Fe chelators, including analogues of 2-pyridylcarboxaldehyde isonicotinoyl hydrazone, di-2-pyridylketone isonicotinoyl hydrazone, di-2-pyridylketone thiosemicarbazone, and the clinically trialed chelator 3-aminopyridine-2-carboxaldehyde thiosemicarbazone. The potential application of these agents in the changing face of Fe chelation therapy is discussed. PMID:17402750

Kalinowski, Danuta S; Richardson, Des R

2007-04-03

145

Melting of low-level radioactive non-ferrous metal for release  

SciTech Connect

Siempelkamp Nukleartechnik GmbH has gained lots of experience from melting ferrous metals for recycling in the nuclear cycle as well as for release to general reuse. Due to the fact that the world market prices for non-ferrous metals like copper, aluminium or lead raised up in the past and will remain on a high level, recycling of low-level contaminated or activated metallic residues from nuclear decommissioning becomes more important. Based on the established technology for melting of ferrous metals in a medium frequency induction furnace, different melt treatment procedures for each kind of non-ferrous metals were developed and successfully commercially converted. Beside different procedures also different melting techniques such as crucibles, gas burners, ladles etc. are used. Approximately 340 Mg of aluminium, a large part of it with a uranium contamination, have been molten successfully and have met the release criteria of the German Radiation Protection Ordinance. The experience in copper and brass melting is based on a total mass of 200 Mg. Lead melting in a special ladle by using a gas heater results in a total of 420 Mg which could be released. The main goal of melting of non-ferrous metals is release for industrial reuse after treatment. Especially for lead, a cooperation with a German lead manufacturer also for recycling of non releasable lead is being planned. (authors)

Quade, Ulrich; Kluth, Thomas; Kreh, Rainer [Siempelkamp Nukleartechnik GmbH (Germany)

2007-07-01

146

Iron chelation by polyamidoamine dendrimers: a second-order kinetic model for metal-amine complexation.  

PubMed

This study presents a kinetic model of the chelation of iron ions by generation 4 hydroxyl-terminated polyamidoamine (PAMAM) with ethylenediamine core (G4-OH). The coordination processes of iron ions from ferric chloride, FeCl(3), and ferrous bromide, FeBr(2), to G4-OH dendrimers were analyzed using ultraviolet-visible (UV-vis) spectroscopy, proton nuclear magnetic resonance ((1)H NMR) spectroscopy, and liquid chromatography-mass spectrometry (LC-MS). In the visible region, a charge-transfer was observed when the dendrimer was added to a ferric chloride solution. This phenomenon is a ligand-to-metal charge-transfer (LMCT) between the free electron group of the dendrimer's internal amines and the dehalogenated iron ion that takes 2 h to complete at room temperature. Analysis of potential rate laws and diffusion effects led to a second-order kinetic model for this reaction. By measuring the rate coefficients as a function of temperature (22-37 癈), an apparent activation energy of 41.5 kJ/mol was obtained using the Arrhenius method. The results of this study will fuel research of PAMAM dendrimers for environmental, pharmaceutical, and materials applications. PMID:21995617

Mankbadi, Michael R; Barakat, Mohamed A; Ramadan, Mohamed H; Woodcock, H Lee; Kuhn, John N

2011-10-28

147

Transport Kinetics of Iron Chelators and Their Chelates in Caco-2 Cells  

Microsoft Academic Search

\\u000a Purpose牋Caco-2 monolayers were used to contrast the bidirectional transport of iron chelators and their chelates and to estimate fundamental\\u000a kinetics associated with their intestinal absorption.\\u000a \\u000a \\u000a \\u000a Methods牋Bidirectional transport was studied at 37C and pH 7.4 using 500-?M concentrations. Monolayer integrity was tested via transepithelial\\u000a electrical resistance and sodium fluorescein permeability. Apical and basolateral analysis provided mass balance evidence.\\u000a Apparent permeability coefficient

Xi-Ping Huang; M. Spino; J. J. Thiessen

2006-01-01

148

Vibrational relaxation of NO stretching modes in ferrous NO and ferric NO in model heme  

NASA Astrophysics Data System (ADS)

Femtosecond IR-pump-IR-probe spectroscopy was used to measure the vibrational lifetimes (T1) of NO stretching modes of ferrous NO near 1600 cm-1 and ferric NO near 1900 cm-1 at room temperature. The T1 of NO bound to the heme, ranging from 3.5 to 34 ps, is much shorter in ferrous NO. The vibrational relaxation (VR) of NO was independent of solvent used and excess imidazole concentration, suggesting that intramolecular VR into the internal vibrational modes of the probed molecule may be the dominant pathway for VR of the bound NO. With estimated T1 of the bound NO, we simulated transient spectra of NO bound to ferrous hemoglobin (HbII) after photodeligation of HbIINO and discussed the influence of the hot band on the determination of the dynamics of geminate rebinding of NO to HbII using the change in the magnitude of the fundamental band.

Park, Jaeheung; Lee, Taegon; Lim, Manho

2013-08-01

149

Free radical inactivation of rabbit muscle creatinine kinase: catalysis by physiological and hydrolyzed ICRF-187 (ICRF-198) iron chelates.  

PubMed

Creatine kinase is a sulfhydryl containing enzyme that is particularly susceptible to oxidative inactivation. This enzyme is potentially vulnerable to inactivation under conditions when it would be used as a diagnostic marker of tissue damage such as during cardiac ischemia/reperfusion or other oxidative tissue injury. Oxidative stress in tissues can induce the release of iron from its storage proteins, making it an available catalyst for free radical reactions. Although creatinine kinase inactivation in a heart reperfusion model has been documented, the mechanism has not been fully described, particularly with regard to the role of iron. We have investigated the inactivation of rabbit muscle creatine kinase by hydrogen peroxide and by xanthine oxidase generated superoxide or Adriamycin radicals in the presence of iron catalysts. As shown previously, creatine kinase was inactivated by hydrogen peroxide. Ferrous iron enhanced the inactivation. In addition, micromolar levels of iron and iron chelates that were reduced and recycled by superoxide or Adriamycin radicals were effective catalysts of creatinine kinase inactivation. Of the physiological iron chelates studied, Fe(ATP) was an especially effective catalyst of inactivation by what appeared to be a site-localized reaction. Fe(ICRF-198), a non-physiological chelate of interest because of its putative role in alleviating Adriamycin-induced cardiotoxicity, also catalyzed the inactivation. Scavenger studies implicated hydroxyl radical as the oxidant involved in iron-dependent creatine kinase inactivation. Loss of protein thiols accompanied loss of creatine kinase activity. Reduced glutathione (GSH) provided marked protection from oxidative inactivation, suggesting that enzyme inactivation under physiological conditions would occur only after GSH depletion. PMID:7834053

Thomas, C; Carr, A C; Winterbourn, C C

150

Iron chelators as therapeutic agents for the treatment of cancer.  

PubMed

A wide variety of studies in vitro, in vivo, and in clinical trials have demonstrated that the chelator currently used to treat iron overload disease, desferrioxamine, has anti-proliferative effects against both leukemia and neuroblastoma. However, the efficacy of desferrioxamine is severely limited due to its poor ability to permeate cell membranes and chelate intracellular iron pools. These studies have led to the development of other iron chelators that are far more effective than desferrioxamine. Some of these chelators such as 3-aminopyridine-2-carboxaldehyde thiosemicarbazone (Triapine) have entered phase I clinical trials, while other chelators such as 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone or tachpyridine require evaluation in animal models. The high anti-tumor activity observed with these ligands certainly suggests further development of chelators as anti-cancer agents is warranted. PMID:12050019

Richardson, D R

2002-06-01

151

Development of an intelligent control system for ferrous iron oxidation by Thiobacillus ferrooxidans  

SciTech Connect

An intelligent control system (ICS) is being developed for ferrous iron oxidation by Thiobacillus ferroxidans. The ICS provides compterized data acquisition and control of process variables (temperature, Eh, pH, dissolved oxygen and carbon dioxide concentrations, and dilution rate) to maintain the ferrous iron oxidation at the highest possible rate. The ICS uses fuzzy logic for analysis of data inputs and implementation of control strategies. This paper provides preliminary information on the development of the ICS and its operation. 17 refs., 3 figs.

Light, M.D.; Torma, A.E.; Cordes, G.A.

1991-01-01

152

Study of electropolishing of ferrous alloys using rotating-disk electrodes  

SciTech Connect

This work deals with electropolishing of ferrous materials ranging from pure iron through carbon steels, with increasing carbon content, to a few low-alloy steels. The characteristics of electropolishing stainless and acid-proof steels are well known, and for this reason were not considered in this research. Studies were performed on the rotating disk electrode system under controlled electrochemical and hydrodynamic conditions. The purpose was to establish conditions at which the best surface finish, after electropolishing of different types of ferrous alloys, may be achieved. The work involved investigations over a wide range of applied current density, mass loss, and current efficiency.

Hryniewich, T.; Muller, R.H.; Tobias, C.W.

1981-06-01

153

Application of ferrous hydrogen peroxide for treatment of DSD-acid manufacturing process wastewater  

Microsoft Academic Search

A pretreatment method for the biological treatment of wastewater from 4,4?-diaminostilbene-2,2?-disulfonic acid (DSD-acid) manufacturing processes, a refractory dye intermediate wastewater, based on combined ferrous hydrogen peroxide oxidation and coagulation杅locculation, was developed. When the wastewater was treated with ferrous hydrogen peroxide oxidation ([Fe2+]=2.7mmol\\/L, [H2O2]=0.21mol\\/L) after a flocculation using an organic flocculant TS-1 at a dosage of 3g\\/L, the overall COD and

Wanpeng Zhu; Zhihua Yang; Li Wang

2001-01-01

154

The Effect of Ferrous Sulfate on Sulfide-Induced Corrosion of Copper-Base Condenser Alloys in Aerated Seawater.  

National Technical Information Service (NTIS)

Exposures were conducted for 30, 60, and 90 days in aerated seawater with and without continuous addition of 0.05 milligram per liter sulfide ion and 0.10 milligram per liter ferrous ions from ferrous sulfate on Alloys C70600 (90-10 copper-nickel), C71500...

H. P. Hack T. S. Lee

1982-01-01

155

Role of chelates in magnetic resonance imaging studies.  

PubMed

Imaging studies are tests performed with a variety of techniques that produce pictures of the inside of a patient's body. Magnetic resonance imaging (MRI) is an imaging technique based on the principles of nuclear magnetic resonance. MRI uses a powerful magnetic field, radio waves, and a computer to produce detailed pictures of organs, soft tissues, bone, and virtually all other internal body structures. Chelates have a wide application in such imaging techniques. Chelates in imaging studies are used alone as radioactive agents or conjugated to monoclonal antibodies or to DNA as radioactive agents. Technetium chelates and gadolinium chelates are being widely used as magnetic resonance contrast media. PMID:19841554

Tripathi, Laxmi; Kumar, Praveen; Singh, Ranjit

156

Orally active alpha-ketohydroxypyridine iron chelators: studies in mice  

SciTech Connect

Several N-substituted 3-hydroxypyrid-2-one and N-substituted 2-methyl-3-hydroxypyrid-4-one chelators were screened for /sup 59/Fe removal using iron-overloaded mice labeled with /sup 59/Fe. The most effectice chelators were found to be the N-methyl, N-ethyl, and N-propyl derivatives of 2-methyl-3-hydroxypyrid-4-one. When the above three chelators were administered intragastrically or intraperitoneally (200 mg/kg) to mice, they caused equivalent /sup 59/Fe excretions to intraperitoneal desferrioxamine (200 mg/kg). These results increase the prospects for the use of the alpha-ketohydroxypyridine chelators in the treatment of iron overload.

Kontoghiorghes, G.J.

1986-12-01

157

Metal regeneration of iron chelates in nitric oxide scrubbing  

DOEpatents

The present invention relates to a process of using metal particles to reduce NO to NH.sub.3. More specifically, the invention concerns an improved process to regenerate iron (II) (CHELATE) by reduction of iron (II) (CHELATE) (NO) complex, which process comprises: a) contacting an aqueous solution containing iron (II) (CHELATE) (NO) with metal particles at between about 20.degree. and 90.degree. C. to reduce NO present, produce ammonia or an ammonium ion, and produce free iron (II) (CHELATE) at a pH of between about 3 and 8. The process is useful to remove NO from flue gas and reduce pollution.

Chang, Shih-Ger (El Cerrito, CA); Littlejohn, David (Oakland, CA); Shi, Yao (Berkeley, CA)

1997-08-19

158

Study of Dosimetric Systems-Ferrous Sulfate-Ferric Sulfate, Glass Slides and Dyed Aqueous Solutions.  

National Technical Information Service (NTIS)

The effect of some variables which can effect the preparation of the ferrous sulfate used as dosimetric solution has been studied. Among these variables the purity of the water used for the preparation of the solution and the presence (or absence) of oxyg...

L. Fernandes

1979-01-01

159

ELECTRODE MEASUREMENT OF REDOX POTENTIAL IN ANAEROBIC FERRIC/FERROUS CHLORIDE SYSTEMS  

EPA Science Inventory

The behaviour of two inert redox electrodes (Pt and wax-impregnated graphite) was investigated in anaerobic ferrous and ferric chloride solutions in order to establish if these electrodes respond to the Fe3+/Fe2+ couple in a Nernstian manner. A new method fo...

160

ThermoChemical Wear Mechanism of Diamond Tool in Machining of Ferrous Metals  

Microsoft Academic Search

To understand the wear mechanism of diamond tool in machining of ferrous metals, an erosion test simulating wear process and ab-initio molecular orbital calculation are carried out. The results of the tests and analyses show that the essential wear mechanism at the temperature higher than 1000K is the dissociation of carbon atoms on diamond surface due to the interaction with

S. Shimada; H. Tanaka; M. Higuchi; T. Yamaguchi; S. Honda; K. Obata

2004-01-01

161

Impact of sulphide non?ferrous ore mining and dressing activities on the environment  

Microsoft Academic Search

An attempt has been made to assess the impact of sulphide non?ferrous ore mining and dressing activities on the environment in the Rhodopes region, South Bulgaria. Pollution of air, water (surface and ground) and soil has been investigated.It has been found that at present air and ground water in the region are not polluted. Surface water, especially Arda river and

M. Panayotova

1997-01-01

162

Photochemical Reactions connected with the Quenching of Fluorescence of Dyestuffs by Ferrous Ions in Solution  

Microsoft Academic Search

IT has been found recently that ferrous ions exert a strong quenching effect on different fluorescent dyestuffs in solution1. According to previous theoretical discussions2, in the elementary process of quenching, the light quantum (hnu), is transferred from the excited dyestuff molecule (Dshnu) to the Fe++ ion by a collision of the second kind. Unlike the case of direct irradiation, when

Joseph Weiss

1935-01-01

163

IN SITU CR(VI) TREATMENT USING A FERROUS IRON-BASED REDUCTANT  

EPA Science Inventory

Laboratory and field studies were conducted to evaluate the performance of a ferrous sulfate/ sodium hydrosulfite (dithionite) reductant blend in treating a hexavalent chromium (Cr(VI)) source area and Cr(VI) dissolved phase plume at a former industrial site in Charleston, South ...

164

Angular Dependence of Field-Induced Phase Transitions in Alpha-Ferrous Oxide.  

National Technical Information Service (NTIS)

The angular dependence of the field-induced phase transitions in single crystal alpha ferrous oxide are measured below the Morin temperature with a torquemeter. The results are in good agreement with calculations which include a fourth-order anisotropy. F...

C. Voigt H. C. Praddaude S. Foner

1971-01-01

165

Optimization of ferrous biooxidation rate in a packed bed bioreactor using Taguchi approach  

Microsoft Academic Search

The biological oxidation of ferrous ion by iron-oxidizing bacteria is potentially a useful industrial process for removal of H2S from industrial gases, desulphurization of coal, removal of sulfur dioxide from flue gas, treatment of acid mine drainage and regeneration of an oxidant agent in hydrometallurgical leaching operations. The main purpose of this study was to find optimum values of the

S. M. Mousavi; S. Yaghmaei; A. Jafari; M. Vossoughi; Z. Ghobadi

2007-01-01

166

Clean ferrous casting technology research. Annual report, September 29, 1994--September 28, 1995  

SciTech Connect

This annual report covers work performed in the second year of research on Clean Ferrous Casting Technology Research. Significant progress was made in establishing pouring practices which avoid re-oxidation of steel during pouring; application of revised pouring practices have led to reduced inclusion levels in commercially poured steel castings.

Griffin, J.; Bates, C.E.; Piwonka, T.S.

1995-10-31

167

Oral ferrous fumarate or intravenous iron sucrose for patients with inflammatory bowel disease  

Microsoft Academic Search

Objective. Iron therapy may reinforce intestinal inflammation by catalysing production of reactive oxygen species. The effects of oral ferrous fumarate and intravenous iron sucrose on clinical disease activity and plasma redox status were investigated in patients with inflammatory bowel disease (IBD). Material and methods. Nineteen patients with iron deficiency anaemia and Crohn's disease (11) or ulcerative colitis (8) were included

Kari Erichsen; Rune J. Ulvik; Gunnar Nysaeter; Jack Johansen; Jens Ostborg; Arnold Berstad; Rolf K. Berge; Trygve Hausken

2005-01-01

168

Effects of adding glycerol and sucrose to ferrous xylenol orange hydrogel  

NASA Astrophysics Data System (ADS)

Glycerol and sucrose were substituted up to 40% by mass for water in ferrous xylenol gelatin hydrogel (FX). Both materials increased the refractive index of the aqueous component of the gels and lowered the optical scatter coefficient. Diffusion of the FX products was reduced 3-fold at 40% substitution levels. The radiation response was more stable with glycerol.

Jordan, Kevin; Sekimoto, Masaya

2010-11-01

169

Characterization of Ferric and Ferrous Iron Transport Systems in Vibrio cholerae  

Microsoft Academic Search

Vibrio cholerae has multiple iron acquisition systems, including TonB-dependent transport of heme and of the catechol siderophore vibriobactin. Strains defective in both of these systems grow well in laboratory media and in the infant mouse intestine, indicating the presence of additional iron acquisition systems. Previously uncharacter- ized potential iron transport systems, including a homologue of the ferrous transporter Feo and

Elizabeth E. Wyckoff; Alexandra R. Mey; Andreas Leimbach; Carolyn F. Fisher; Shelley M. Payne

2006-01-01

170

COMBINATION LIMESTONE-LIME NEUTRALIZATION OF FERROUS IRON ACID MINE DRAINAGE  

EPA Science Inventory

Studies were conducted on ferrous-iron acid mine drainage (AMD) treatment by a two-step neutralization process in which rock-dust limestone was mixed with the influent AMD and then hydrated lime was added in a polishing reactor. This combination treatment process resulted in reag...

171

Determination of the electric field gradient tensor in ferrous ammonium sulphate using a polarized Mossbauer source  

Microsoft Academic Search

A Mossbauer source of 57Co in iron metal polarized in an external magnetic field has been used to determine the orientation of the electric field gradient tensor in a single-crystal absorber of ferrous ammonium sulphate at room temperature. Theoretical equations are given for the polarization dependence of the absorption cross section in an absorber of finite thickness, and are used

T. C. Gibb

1975-01-01

172

Three-dimensional determination of absorbed dose by spectrophotometric analysis of ferrous-sulphate agarose gel  

Microsoft Academic Search

We describe a technique to obtain three-dimensional (3-D) imaging of an absorbed dose by optical transmittance measurements of phantoms composed by agarose gel in which a ferrous sulphate and xylenol orange solution are incorporated. The analysis of gel samples is performed by acquiring transmittance images with a system based on a CCD camera provided with an interference filter matching the

G. Gambarini; G. Gomarasca; R. Marchesini; A. Pecci; L. Pirola; S. Tomatis

1999-01-01

173

Range Clearance by Enhancing Oxidation of Ferrous Ordnance In-Situ.  

National Technical Information Service (NTIS)

The patent application describes a method of clearing a target range or other area of buried unexploded ordnance (UXO) by advancing natural galvanic electro-chemical corrosion whereby ferrous parts of the UXO is simply rusted away at an accelerated rate a...

M. A. Pedersen

1982-01-01

174

Combination Limestone-Lime Neutralization of Ferrous Iron Acid Mine Drainage.  

National Technical Information Service (NTIS)

Studies were conducted on ferrous-iron acid mine drainage (AMD) treatment by a two-step neutralization process in which rock-dust limestone was mixed with the influent AMD and then hydrated lime was added in a polishing reactor. This combination treatment...

R. C. Wilmoth

1978-01-01

175

Mossbauer Spectroscopic Study of the Reversible Oxidation of Ferrous Ions in Y Zeolite.  

National Technical Information Service (NTIS)

The ferrous ions in dehydrated Fe(2+)-Y zeolite are oxidized to ferric ions by the adsorption of dry oxygen at 400C. Approximately one oxygen atom is adsorbed for two iron ions. It is proposed that the oxidation at 400C forms iron-oxygen-iron bridges insi...

M. Boudart R. L. Garten W. N. Delgass

1969-01-01

176

The chemistry of the thermal decomposition of pseudobrookite ferrous titanium oxides  

Microsoft Academic Search

The thermal decomposition of two metastable ferrous titanium oxide compounds of commercial interest have been studied by in situ X-ray and neutron diffraction at elevated temperatures as well as by 57Fe Mossbauer effect spectroscopy. Thermal decomposition was monitored by collecting neutron diffraction data (taken at the Argonne National Laboratory Intense Pulsed Neutron Source (IPNS) powder diffractometers) at 30-min intervals at

Raymond G. Teller; Mark R. Antonio; Alphonso E. Grau; Michel Gueguin; Edward Kostiner

1990-01-01

177

Macrocyclic Chelator Assembled RGD Multimers for Tumor Targeting  

PubMed Central

Macrocyclic chelators have been extensively used for complexation of metal ions. A widely used chelator, DOTA, has been explored as a molecular platform to assemble multiple bioactive peptides in this paper. The multivalent DOTA-peptide bioconjugates demonstrate promising tumor targeting ability.

Zhang, Xiaofen; Liu, Hongguang; Miao, Zheng; Kimura, Richard; Fan, Feiyue; Cheng, Zhen

2011-01-01

178

Clioquinol effects on tissue chelatable zinc in mice  

Microsoft Academic Search

Recent evidence for the involvement of zinc in the formation of -amyloid plaques in the brain in Alzheimer's disease has led to the establishment of new therapeutic strategies for the degenerative disorder based on metal chelation. The present experiment was conducted on a membrane-permeable zinc chelator, clioquinol (CQ), that has shown potential in initial studies on a mouse model of

Yuval B. Nitzan; Israel Sekler; Christopher J. Frederickson; Douglas A. Coulter; Rengarajan V. Balaji; Shu-Ling Liang; Ariel Margulis; Michal Hershfinkel; William F. Silverman

2003-01-01

179

Chelation Treatment for Autism Spectrum Disorders: A Systematic Review  

ERIC Educational Resources Information Center

Chelation treatment is used to eliminate specific metals from the body, such as mercury. It has been hypothesized that mercury poisoning may be a factor in autism and data suggest that perhaps 7% of individuals with autism spectrum disorder (ASD) have received chelation treatment. It would therefore seem timely to review studies investigating the

Davis, Tonya N.; O'Reilly, Mark; Kang, Soyeon; Lang, Russell; Rispoli, Mandy; Sigafoos, Jeff; Lancioni, Giulio; Copeland, Daelynn; Attai, Shanna; Mulloy, Austin

2013-01-01

180

Lead chelation to immobilised Symphytum officinale L. (comfrey) root tannins  

Microsoft Academic Search

Reported correlations between tannin level and metal accumulation within plant tissues suggest that metal-chelating tannins may help plants to tolerate toxic levels of heavy metal contaminants. This paper supports such correlations using a new method that demonstrated the ability of plant tannins to chelate heavy metals, and showed that the relative levels of tannins in tissues were quantitatively related to

Lily Chin; David W. M. Leung; H. Harry Taylor

2009-01-01

181

Chelation Treatment for Autism Spectrum Disorders: A Systematic Review  

ERIC Educational Resources Information Center

|Chelation treatment is used to eliminate specific metals from the body, such as mercury. It has been hypothesized that mercury poisoning may be a factor in autism and data suggest that perhaps 7% of individuals with autism spectrum disorder (ASD) have received chelation treatment. It would therefore seem timely to review studies investigating the

Davis, Tonya N.; O'Reilly, Mark; Kang, Soyeon; Lang, Russell; Rispoli, Mandy; Sigafoos, Jeff; Lancioni, Giulio; Copeland, Daelynn; Attai, Shanna; Mulloy, Austin

2013-01-01

182

Effects of additives and chelating agents on electroless copper plating  

Microsoft Academic Search

In this study, ethylenediaminetetraacetic acid (EDTA), triethanolamine (TEA), and ethylenediamine (En) were adopted herein as additives or chelating agents in electroless copper plating, with formaldehyde as the reduction agent. Linear sweep voltammetry was successfully applied to analyze the potential shift of copper complexes and the adsorption capability of chelating agents on a surface. Moreover, the grain size and surface roughness

Yi-Mao Lin; Shi-Chern Yen

2001-01-01

183

Iron chelators as therapeutic agents for the treatment of cancer  

Microsoft Academic Search

A wide variety of studies in vitro, in vivo, and in clinical trials have demonstrated that the chelator currently used to treat iron overload disease, desferrioxamine, has anti-proliferative effects against both leukemia and neuroblastoma. However, the efficacy of desferrioxamine is severely limited due to its poor ability to permeate cell membranes and chelate intracellular iron pools. These studies have led

D. R. Richardson

2002-01-01

184

Analysis, Characterization, and Effects of Heavy Metal Chelating Agents in Water.  

National Technical Information Service (NTIS)

A study was made of chelating agents in natural waters and wastewaters. Emphasis was placed upon the chemical analysis of total chelating agent capacity and specific chelating agents. The primary chemical analysis technique used consists of a high pressur...

S. E. Manahan

1976-01-01

185

Correlation of microstructure and wear resistance of ferrous coatings fabricated by atmospheric plasma spraying  

NASA Astrophysics Data System (ADS)

The correlation of microstructure and wear resistance in ferrous coatings applicable to diesel engine cylinder bores was investigated in this study. Seven kinds of ferrous spray powders, two of which were stainless steel powders and the others blend powders of ferrous powders mixed with Al2O3-ZrO2 powders, were sprayed on a low-carbon steel substrate by atmospheric plasma spraying. Microstructural analysis of the ferrous coatings showed that various Fe oxides such as FeO, Fe2O3, and ?-Fe2O3 were formed in the martensitic (or austenitic) matrix as a result of the reaction with oxygen in air. The blend coatings containing ?-Al2O3 and t-ZrO2 oxides, which were formed as Al2O3-ZrO2 powders, were rapidly solidified during plasma spraying. The wear test results revealed that the blend coatings showed better wear resistance than the ferrous coatings because they contained a number of hard Al2O3-ZrO2 oxides. However, delamination occurred when cracks initiated at matrix/oxide interfaces and propagated parallel to the worn surface in the case of the large hardness difference between the matrix and oxide. The wear rate of the coating fabricated with STS316 powders was slightly higher than other coatings, but the wear rate of the counterpart material was very low because of the smaller matrix/oxide hardness difference due to the presence of many Fe oxides. In order to reduce the wear of both the coating and its counterpart material, the matrix/oxide hardness difference should be minimized, and the hardness of the coating should be increased over a certain level by forming an appropriate amount of oxides.

Hwang, Byoungchul; Ahn, Jeehoon; Lee, Sunghak

2002-09-01

186

Organometallic Chelate Complexes of the ?-? and ?-n Type  

NASA Astrophysics Data System (ADS)

Organometallic chelate complexes in which either organic fragments ?-bonded to the metal (chelates of the ?-? type) or complexes where heteroatomic groups with an unshared electron pair (NR2, PR2, AsR2, OR, etc.) linked to the metal via an n-type bond (chelates of the ?-n type) are present together with the ?-bonded fragments are examined. Data on complexes with polydentate ligands, including different combinations of fragments ?- and n-coordinated to the metal are also surveyed. The characteristic features of the formation of organometallic chelates of the ?-? and ?-n types, which depend on the properties of the chelating ligand and the nature of the metal, are discussed. The bibliography includes 267 references.

Rybinskaya, Margarita I.; Krivykh, Vassily V.

1984-05-01

187

Chelation in metal intoxication XXI: chelation in lead intoxication during vitamin B complex deficiency  

SciTech Connect

The vitamin B-complex deficiency increases the vulnerability to neuro- and systemic toxicity of Pb in young rats. Thus, the nutritional status of vitamins like that of protein or minerals seems to influence the etiology of Pb toxicity and may be expected to affect the response toward Pb chelators. 2,3 dimercaptosuccinic acid (DMSA) and N-(2-hydroxyethyl) ethylene-diamine triacetic acid (HEDTA) have been found to be effective antidotes to Pb intoxication. In the present study, these selective metal chelating agents were compared for their ability to reduce the body burden of Pb and restore the altered biochemical parameters in young developing Pb intoxicated rats maintained on normal or vitamin B-complex deficient diet. The investigation was aimed to suggest suitable prophylaxis of Pb poisoning prevalent among children who may also be suffering from vitamin deficiency in developing and poor countries.

Not Available

1986-09-01

188

Liposomal Cu-64 labeling method using bifunctional chelators: polyethylene glycol spacer and chelator effects  

PubMed Central

Two bifunctional Cu-64 chelators (BFCs), (6-(6-(3-(2-pyridyldithio)propionamido)hexanamido)benzyl)-1,4,8,11-tetraazacyclotetradecane- 1,4,8,11-tetraacetic acid (TETA-PDP) and 4-(2-(2-pyridyldithioethyl)ethanamido)-11-carboxymethyl-1,4,8,11-tetraazabicyclo(6.6.2)hexadecane (CB-TE2A-PDEA), were synthesized and conjugated to long circulating liposomes (LCLs) via attachment to a maleimide lipid. An in vitro stability assay of 64Cu-TETA, 64Cu-TETA-PEG2k, and 64Cu-CB-TE2A-PEG2k liposomes showed that more than 86% of the radioactivity remains associated with the liposomal fraction after 48 hours of incubation with mouse serum. The in vivo time activity curves (TAC) for the three liposomal formulations showed that ~50% of the radioactivity cleared from the blood pool in 16 - 18 hours. As expected, the in vivo biodistribution and TAC data obtained at 48 hours demonstrate that the clearance of radioactivity from the liver slows with the incorporation of a polyethylene glycol-2k (PEG2k) brush. Our data suggest that 64Cu-TETA and 64Cu-CB-TE2A are similarly stable in the blood pool and accumulation of radioactivity in the liver and spleen is not related to the stability of Cu-64 chelator complex; however clearance of Cu-64 from the liver and spleen are faster when injected as 64Cu-TETA-chelated liposomes rather than 64Cu-CB-TE2A-chelated liposomes.

Seo, Jai Woong; Mahakian, Lisa M.; Kheirolomoom, Azadeh; Zhang, Hua; Meares, Claude F.; Ferdani, Riccardo; Anderson, Carolyn J.; Ferrara, Katherine W.

2010-01-01

189

Chelation therapy for metal intoxication: comments from a thermodynamic viewpoint.  

PubMed

Chelation therapy plays a prominent role in the clinical treatment of metal intoxication. In this paper the principal causes of metal toxicity are exposed, and the chemical and biomedical requisites of a chelating agent are sketched. The chelating agents currently in use for scavenging toxic metal ions from humans belong to few categories: those characterized by coordinating mercapto groups, by oxygen groups, poliaminocarboxylic acids, and dithiocarbamates. Considering that the complex formation equilibria have been studied for less than 50% of chelators in use, some reflections on the utility of stability constants are presented, together with an evaluation of ligands under the stability profile. The competition between endogenous and toxic target metal ions for the same chelating agent is furthermore examined. A thorough examination of stability constant databases has allowed to select, for each toxic metal, the ligands distinguished by the best pMe values. Even though this selection does not consider the biomedical requisites of a chelating agent, it gives a clear picture both of the pMe values that can be attained, and of the most appropriate chelators for each metal ion. PMID:23895193

Nurchi, Valeria Marina; Alonso, Miriam Crespo; Toso, Leonardo; Lachowicz, Joanna Izabela; Crisponi, Guido

2013-10-01

190

Active Insolubilized Antibiotics Based on Cellulose-Metal Chelates1  

PubMed Central

Cellulose was converted into a more reactive form by chelation with the transition metals titaniumIII, ironIII, tinIV, vanadiumIII, and zirconiumIV. The remaining unsubstituted ligands of the transition metal ions were found to be amenable to replacement by electron-donating groups of antibiotic molecules. Ampicillin, gentamicin, kanamycin, neomycin, paromomycin, polymyxin B, and streptomycin were used as antibacterial antibiotics, and amphotericin B and natamycin were used as antifungal antibiotics. Antibacterial activity of the products was tested against two gram-positive and two gram-negative bacteria, and antifungal activity was tested against four fungi. That the antibacterial antibiotics had complexed with the cellulose-metal chelates was demonstrated in that the product cellulose-metal-antibiotic chelates exhibited antibiotic activities whereas the metal chelates of cellulose themselves were inactive. Of 140 tests conducted, cellulose-metal-antibiotic chelates were active in 102 cases. Since the antibiotic derivatives were water insoluble and in fact retain some of the antibacterial activities of the parent compounds, the chelation method provides a facile way of rendering cellulose surfaces, etc., resistant to microbial attack over and above that degree of protection afforded by noncovalent adsorption of the antibiotic to cellulose itself. The underlying principles of the chelation reactions involved are discussed in detail.

Kennedy, J. F.; Barker, S. A.; Zamir, A.

1974-01-01

191

Decomposition rates of radiopharmaceutical indium chelates in serum  

Microsoft Academic Search

The rates at which six small aminopolycarboxylate chelates of trivalent111In and three protein-bound chelates of111In deliver indium to the serum protein transferrin have been studied in sterile human serum at pH 7.3, 37癈. Sterically hindered\\u000a chelates containing a substituent on an ethylene carbon of EDTA decompose with rates in the range 0.03 to 0.11% per day梠ne\\u000a to two orders of

S. M. Yeh; C. F. Meares; D. A. Goodwin

1979-01-01

192

Highly active hydrotreatment catalysts prepared with chelating agents  

Microsoft Academic Search

Hydrotreatment catalysts (Co朚o\\/Al2O3, Ni朚o\\/Al2O3 and Ni朩\\/Al2O3) were prepared by an impregnation method using an aqueous solution containing a chelating agent (nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA) or trans-1,2-cyclohexanediamine-N,N,N?,N?-tetraacetic acid (CyDTA)). Co朚o\\/Al2O3 and Ni朩\\/Al2O3 prepared with the chelating agents showed higher hydrodesulfurization (HDS) activity as well as hydrogenation (HYD) activity under high pressure (5.1MPa) than those prepared without the chelating agents.

Takehiro Shimizu; Kazutaka Hiroshima; Takehide Honma; Takeo Mochizuki; Muneyoshi Yamada

1998-01-01

193

Ferrous arrowheads and their oil quench hardening: Some early Indian evidence  

NASA Astrophysics Data System (ADS)

A wide variety of ferrous arrowheads were in use in ancient India. Several typical chemical analyses of arrowheads found from archaeological excavation carried out at Kaushambi are reported in this paper. The average carbon content of these arrowheads varied from as low as 0.1 wt.% to approximately 0.9 wt.%. Literary evidence for oil quench hardening of ferrous arrowheads, as reported in famous Sanskrit epics梩he R?m?yana and the Mah?bh?rata梙ave been discussed in this paper. This type of quench hardening was intentionally adopted as it helped in preventing distortion and formation of quench cracks in arrowheads. The oil quench-hardened arrowheads were rubbed on stones to sharpen them, which also brought about tempering of martensite due to frictional heat.

Dube, R. K.

2008-05-01

194

A modified ferrous oxidation-xylenol orange assay for lipoxygenase activity in rice grains.  

PubMed

Ferrous oxidation-xylenol orange assay reagent was reformulated by using spectral analysis of ferric-xylenol orange complex to detect low concentrations of lipoxygenase rice grain products. Reducing the levels of ferrous sulphate and xylenol orange in the FOX reagent enabled the detection of low concentrations of hydroperoxy fatty acid derived from lipoxygenase activity in the range of 0.1-1.5 ?M. Protein, substrate and time courses of the modified FOX assay were studied to determine lipoxygenase activity in rice grain. The assay was also applicable as a high throughput technique for comparisons of lipoxygenase activity from various rice varieties. This has important implications for rapid screening for low-lipoxygenase containing rice cultivars in rice breeding program and grain quality during storage. PMID:23870974

Timabud, Tarinee; Sanitchon, Jirawat; Pongdontri, Paweena

2013-05-18

195

The determination of ferric iron in plants by HPLC using the microbial iron chelator desferrioxamine E.  

PubMed

Common methods for plant iron determination are based on atomic absorption spectroscopy, radioactive measurements or extraction with subsequent spectrophotometry. However, accuracy is often a problem due to background, contamination and interfering compounds. We here describe a novel method for the easy determination of ferric iron in plants by chelation with a highly effective microbial siderophore and separation by high performance liquid chromatography (HPLC). After addition of colourless desferrioxamine E (DFE) to plant fluids, the soluble iron is trapped as a brown-red ferrioxamine E (FoxE) complex which is subsequently separated by HPLC on a reversed phase column. The formed FoxE complex can be identified due to its ligand-to-metal charge transfer band at 435 nm. Alternatively, elution of both, DFE and FoxE can be followed as separate peaks at 220 nm wavelength with characteristic retention times. The extraordinarily high stability constant of DFE with ferric iron of K = 10(32) enables extraction of iron from a variety of ferrous and ferric iron compounds and allows quantitation after separation by HPLC without interference by coloured by-products. Thus, iron bound to protein, amino acids, citrate and other organic acid ligands and even insoluble ferric hydroxides and phosphates can be solubilized in the presence desferrioxamine E. The "Ferrioxamine E method" can be applied to all kinds of plant fluids (apoplasmic, xylem, phloem, intracellular) either at physiological pH or even at acid pH values. The FoxE complex is stable down to pH 1 allowing protein removal by perchloric acid treatment and HPLC separation in the presence of trifluoroacetic acid containing eluents. PMID:15865410

Fern醤dez, Victoria; Winkelmann, G黱ther

2005-02-01

196

Laser beam welding non-ferrous metals. (Latest citations from METADEX). Published Search  

SciTech Connect

The bibliography contains citations concerning techniques and the evaluation of laser beam welding of non-ferrous metals. Welding parameters, such as incident laser power and welding speed, are reviewed in relation to their characterization of weld microstructure. Weld examination techniques are cited, including macrophotography, light and electron microscopy, and microhardness profiling. (Contains a minimum of 170 citations and includes a subject term index and title list.)

Not Available

1994-09-01

197

Application of ferrous-hydrogen peroxide for the treatment of H-acid manufacturing process wastewater  

Microsoft Academic Search

1-Amino-8-naphthol-3,6-disulfonic acid (H-acid) is widely used in chemical industries for synthesis of direct, acid, reactive and azoic dye. The wastewater from H-acid manufacturing process is rich in various substituted derivatives of naphthalene and is one of the most hardly-treated wastewaters. A pretreatment method, ferrous ion-peroxide oxidation combined with coagulation, has been studied. The results have shown that the optimum pH

Wanpeng Zhu; Zhihua Yang; Li Wang

1996-01-01

198

Microbial fuel cell operation with continuous biological ferrous iron oxidation of the catholyte.  

PubMed

The oxygen reduction rate at the cathode is a limiting factor in microbial fuel cell (MFC) performance. In our previous study, we showed the performance of an MFC with ferric iron (Fe3+) reduction at the cathode. Instead of oxygen, ferric iron was reduced to ferrous iron (Fe2+) at the cathode with a bipolar membrane between the anode and cathode compartment. This resulted in a higher cathode potential than is usually obtained with oxygen on metal-based chemical catalysts in MFCs. In this study, we investigated the operation of the same MFC with ferric iron reduction at the cathode and simultaneous biological ferrous iron oxidation of the catholyte. We show that the immobilized microorganism Acidithiobacillus ferrooxidans is capable of oxidizing ferrous iron to ferric iron at a rate high enough to ensure an MFC power output of 1.2 W/m2 and a current of 4.4 A/m2. This power output was 38% higher than in our previous study at a similar current density without ferrous iron oxidation. The bipolar membrane is shown to split water into 65-76% of the needed protons and hydroxides. The other part of the protons was supplied as H2SO4 to the cathode compartment. The remaining charge was transported by K+ and HSO4-/SO4(2-) from the one compartment to the other. This resulted in increased salt concentrations in the cathode. The increased salt concentrations reduced the ohmic losses and enabled the improved MFC power output. Iron could be reversibly removed from the bipolar membrane by exchange with protons. PMID:17612201

Ter Heijne, Annemiek; Hamelers, Hubertus V M; Buisman, Cees J N

2007-06-01

199

Ignition and combustion of ferrous metals in high pressure, high velocity, gaseous oxygen  

Microsoft Academic Search

The ignition-burn conditions of several ferrous metals, including AISI1025, AISI 4140, ductile iron and 304, 410, 17-4 PH,\\u000a and CA15 stainless steels have been determined. The oxygen conditions involved velocities of approximately 430 meters per\\u000a second (1400 feet per second) and pressures of 20 to 68 atm (300 to 1000 psig). When 1025 steel specimens were fractured in\\u000a 68 atm

Charles E. Bates; James E. Wren; Raymond Monroe; C. D. Pears

1979-01-01

200

TEM characterization of the fine scale microstructure of a Roman ferrous nail  

NASA Astrophysics Data System (ADS)

This paper describes the microstructure of a Roman ferrous nail through its observation by transmission electron microscopy. The morphologies of pearlitic colonies and ferritic grains are detailed and the relationship between pearlitic colonies and ferrite in Roman nails is explicitly demonstrated for the first time. Observations also confirm the presence of dislocations in ferritic grains and attest to the existence of very small carbide precipitates that have not been pointed out previously in standard archaeometric studies.

Douin, J.; Henry, O.; Dabosi, F.; Sciau, P.

2010-07-01

201

Enhancement of cytotoxicity of artemisinins toward cancer cells by ferrous iron  

Microsoft Academic Search

Iron(II) heme-mediated activation of the peroxide bond of artemisinins is thought to generate the radical oxygen species responsible for their antimalarial activity. We analyzed the role of ferrous iron in the cytotoxicity of artemisinins toward tumor cells. Iron(II)杇lycine sulfate (Ferrosanol) and transferrin increased the cytotoxicity of free artesunate, artesunate microencapsulated in maltosyl-?-cyclodextrin, and artemisinin toward CCRF-CEM leukemia and U373 astrocytoma

Thomas Efferth; Achille Benakis; Marta R. Romero; Maja Tomicic; Rolf Rauh; Daniel Steinbach; Ralf H鋐er; Thomas Stamminger; Franz Oesch; Bernd Kaina; Manfred Marschall

2004-01-01

202

An intergrown perovskite-wollastonite phase in some ferrous blast-furnace slags  

Microsoft Academic Search

During crystallization of silicate liquids, TiO2 tends to form its own mineral. Ferrous blast-furnace slags generally have perovskite as the titanium-rich phase. However, a rounded and fibrous phase, crystallizing instead of perovskite, has been observed in some slag samples: it has an apparently late position in the order of crystallization. Detailed electron microprobe analysis and X-ray diffraction have indicated that

E. Wearing

1983-01-01

203

Magnetic and electrical properties of gamma-Fe2O3 prepared from ferrous malonate dihydrate  

Microsoft Academic Search

gamma-Fe2O3 prepared from ferrous malonate dihydrate has been investigated using direct current electrical conductivity, the Seebeck coefficient, X-ray diffraction pattern, initial magnetization, magnetic hysteresis, M鰏sbauer spectroscopy and scanning electron microscopy. The study of the direct current electrical conductivity of freshly prepared gamma-Fe2O3 and that of a sample stored for seven days in static air suggests that gamma-Fe2O3 adsorbs oxygen and

A. K. Nikumbh; P. L. Sayanekar; M. G. Chaskar

1991-01-01

204

Silver toxicity to ferrous iron and pyrite oxidation and its alleviation by yeast extract in cultures of Thiobacillus ferrooxidans  

Microsoft Academic Search

Summary Ferrous-ion oxidation byThiobacillusferrooxidans was inhibited by 10-6 M Ag+ while a slight inhibition of growth was apparent with 10-7 M Ag+. The threshold toxic concentration was the seme for four different test strains. While prolonged lag phases resulted from culture exposure to Ag+, Fe2+ oxidation rates after the onset of growth showed little variation under these conditions. Yeast extract

Olli H. Tuovinen; Jaakko Puhakka; Paula Hiltunen; Katherine M. Dolan

1985-01-01

205

Chlorobium ferrooxidans sp. nov., a phototrophic green sulfur bacterium that oxidizes ferrous iron in coculture with a 揋eospirillum sp. strain  

Microsoft Academic Search

A green phototrophic bacterium was enriched with ferrous iron as sole electron donor and was isolated in defined coculture\\u000a with a spirilloid chemoheterotrophic bacterium. The coculture oxidized ferrous iron to ferric iron with stoichiometric formation\\u000a of cell mass from carbon dioxide. Sulfide, thiosulfate, or elemental sulfur was not used as electron donor in the light. Hydrogen\\u000a or acetate in the

Silke Heising; Lothar Richter; Wolfgang Ludwig; Bernhard Schink

1999-01-01

206

Stable intermediate-spin ferrous iron in lower-mantle perovskite  

SciTech Connect

The lower mantle is dominated by a magnesium- and iron-bearing mineral with the perovskite structure. Iron has the ability to adopt different electronic configurations, and transitions in its spin state in the lower mantle can significantly influence mantle properties and dynamics. However, previous studies aimed at understanding these transitions have provided conflicting results. Here we report the results of high-pressure (up to 110 GPa) and high-temperature (up to 1,000 K) experiments aimed at understanding spin transitions of iron in perovskite at lower-mantle conditions. Our Moessbauer and nuclear forward scattering data for two lower-mantle perovskite compositions demonstrate that the transition of ferrous iron from the high-spin to the intermediate-spin state occurs at approximately 30 GPa, and that high temperatures favour the stability of the intermediate-spin state. We therefore infer that ferrous iron adopts the intermediate-spin state throughout the bulk of the lower mantle. Our X-ray data show significant anisotropic compression of lower-mantle perovskite containing intermediate-spin ferrous iron, which correlates strongly with the spin transition. We predict spin-state heterogeneities in the uppermost part of the lower mantle associated with sinking slabs and regions of upwelling. These may affect local properties, including thermal and electrical conductivity, deformation (viscosity) and chemical behaviour, and thereby affect mantle dynamics.

McCammon, C.; Kantor, I.; Narygina, O.; Rouquette, J.; Ponkratz, U.; Sergueev, I.; Mezouar, M.; Prakapenka, V.; Dubrovinsky, L. (Bayreuth); (ESRF); (UC)

2008-11-10

207

EPR Characterisation of the Ferrous Nitrosyl Complex Formed within the Oxygenase Domain of NO Synthase.  

PubMed

Nitric oxide is produced in mammals by a class of enzymes called NO synthases (NOSs). It plays a central role in cellular signalling but also has deleterious effects, as it leads to the production of reactive oxygen and nitrogen species. NO forms a relatively stable adduct with ferrous haem proteins, which, in the case of NOS, is also a key catalytic intermediate. Despite extensive studies on the ferrous nitrosyl complex of other haem proteins (in particular myoglobin), little characterisation has been performed in the case of NOS. We report here a temperature-dependent EPR study of the ferrous nitrosyl complex of the inducible mammalian NOS and the bacterial NOS-like protein from Bacillus subtilis. The results show that the overall behaviours are similar to those observed for other haem proteins, but with distinct ratios between axial and rhombic forms in the case of the two NOS proteins. The distal environment appears to control the existence of the axial form and the evolution of the rhombic form. PMID:23943262

Santolini, J閞鬽e; Mar閏hal, Amandine; Boussac, Alain; Dorlet, Pierre

2013-08-13

208

Ferrous iron-dependent delivery of therapeutic agents to the malaria parasite  

PubMed Central

Background The malaria parasites Plasmodium falciparum and Plasmodium vivax generate significant concentrations of free unbound ferrous iron heme as a side product of hemoglobin degradation. The presence of these chemically reactive forms of iron, rare in healthy cells, presents an opportunity for parasite-selective drug delivery. Accordingly, our group is developing technologies for the targeted delivery of therapeutics to the intra-erythrocytic malaria parasite. These so-called 慺ragmenting hybrids employ a 1,2,4-trioxolane ring system as an iron(II)-sensing 憈rigger moiety and a 憈raceless retro-Michael linker to which a variety of partner drug species may be attached. After ferrous iron-promoted activation in the parasite, the partner drug is released via a ?-elimination reaction. Methods In this report, we describe three orthogonal experimental approaches that were explored in order to generate in vitro proof-of-concept for ferrous iron-dependent drug delivery from a prototypical fragmenting hybrid. Conclusion Studies of two fragmenting hybrids by orthogonal approaches confirm that a partner drug species can be delivered to live P. falciparum parasites. A key advantage of this approach is the potential to mask a partner drug抯 intrinsic bioactivity prior to release in the parasite.

Mahajan, Sumit S; Gut, Jiri; Rosenthal, Philip J; Renslo, Adam R

2013-01-01

209

Redox reaction of artemisinin with ferrous and ferric ions in aqueous buffer.  

PubMed

Artemisinin, a sesquiterpene with endoperoxide bond, possesses potent antimalarial activity against the ring and late stage of chloroqine-resistant Plasmodium falciparum malaria both in vitro and in vivo. The mode of antimalarial activity of artemisinin is iron-dependent. The aim of this study was to investigate the reactions of artemisinin with ferrous and ferric ions in aqueous buffer. Artemisinin generated a cycle of iron oxidation and reduction. It oxidized ferrous and reduced ferric ions with similar rate of reaction (k=10+/-0.5 M(-1) x s(-1) for ferrous and k=8.5+/-2.0 M(-1) x s(-1) for ferric ion). The major active product was dihydroartemisinin which exhibited antimalarial activity at least 3 times more potent than artemisinin. Dihydroartemisinin preferably binds to ferric ion, forming ferric-dihydroartemisinin complex. The re-oxidation of the complex gives artemisinin and ferric ion. This suggests that in aqueous buffer, the reaction of artemisinin with iron may give rise to the active reaction products, one of them being dihydroartemisinin, which is responsible for antimalarial activity. PMID:11767072

Sibmooh, N; Udomsangpetch, R; Kujoa, A; Chantharaksri, U; Mankhetkorn, S

2001-12-01

210

Covalent heme attachment in Synechocystis hemoglobin is required to prevent ferrous heme dissociation  

PubMed Central

Synechocystis hemoglobin contains an unprecedented covalent bond between a nonaxial histidine side chain (H117) and the heme 2-vinyl. This bond has been previously shown to stabilize the ferric protein against denaturation, and also to affect the kinetics of cyanide association. However, it is unclear why Synechocystis hemoglobin would require the additional degree of stabilization accompanying the His117杊eme 2-vinyl bond because it also displays endogenous bis-histidyl axial heme coordination, which should greatly assist heme retention. Furthermore, the mechanism by which the His117杊eme 2-vinyl bond affects ligand binding has not been reported, nor has any investigation of the role of this bond on the structure and function of the protein in the ferrous oxidation state. Here we report an investigation of the role of the Synechocystis hemoglobin His117杊eme 2-vinyl bond on structure, heme coordination, exogenous ligand binding, and stability in both the ferrous and ferric oxidation states. Our results reveal that hexacoordinate Synechocystis hemoglobin lacking this bond is less stable in the ferrous oxidation state than the ferric, which is surprising in light of our understanding of pentacoordinate Hb stability, in which the ferric protein is always less stable. It is also demonstrated that removal of the His117杊eme 2-vinyl bond increases the affinity constant for intramolecular histidine coordination in the ferric oxidation state, thus presenting greater competition for the ligand binding site and lowering the observed rate and affinity constants for exogenous ligands.

Hoy, Julie A.; Smagghe, Benoit J.; Halder, Puspita; Hargrove, Mark S.

2007-01-01

211

FeoB is not required for ferrous iron uptake in Campylobacter jejuni.  

PubMed

Among strains of Campylobacter jejuni, levels of ferrous iron (Fe2+) uptake was comparable. However, C. jejuni showed a lower level of ferrous iron uptake than Escherichia coli. Consistent with studies of E. coli, Fe2+ uptake in C. jejuni was significantly enhanced by low Mg2+ concentration. The C. jejuni genome sequence contains a single known ferrous iron uptake gene, feoB, whose product shares 50% amino acid identity to Helicobacter pylori FeoB and 29% identity to E. coli FeoB. However, Fe2+ uptake could not be attributed to FeoB for several reasons. Site-directed mutations in feoB caused no defect in 55Fe2+ uptake. Among C. jejuni strains, various nucleotide alterations were found in feoB, indicating that some C. jejuni feoB genes are defective. In addition, uptake could not be attributed to the magnesium transporter CorA, since no reduction in 55Fe2+ uptake was observed in the presence of a CorA-specific inhibitor. PMID:14735223

Raphael, Brian H; Joens, Lynn A

2003-11-01

212

LITERATURE REVIEW: REDUCTION OF NP(V) TO NP (IV)-ALTERNATIVES TO FERROUS SULFAMATE  

SciTech Connect

The baseline approach to control of Np oxidation in UREX and PUREX separation processes is the reduction of Np(V) and Np(VI) to Np(IV) using ferrous sulfamate. Use of this reagent results in increased sulfur and iron concentrations in the liquid waste streams from the process. Presence of these two elements, especially sulfur, increases the complexity of the development of wasteforms for immobilizing these effluents. Investigations are underway to identify reductants that eliminate sulfur and iron from the Np reduction process. While there are a variety of chemical reductants that will reduce Np to Np(IV) in nitric acid media, the reaction rates for most are so slow that the reductants are not be feasible for use in an operating plant process. In an attempt to identify additional alternatives to ferrous sulfamate, a literature search and review was performed. Based on the results of the literature review, it is concluded that photochemical and catalytic processes should also be investigated to test the utility of these two approaches. The catalytic process could be investigated for use in conjunction with chemical oxidants to speed the reaction rates for reductants that react slowly, but would otherwise be appropriate replacements for ferrous sulfamate. The photochemical approach, which has received little attention during the past few decades, also shows promise, especially the photocatalytic approach that includes a catalyst, such as Pt supported on SiC, which can be used in tandem with an oxidant, for Np reduction.

Kessinger, G.; Kyser, E.; Almond, P.

2009-09-28

213

Iron and pH-responsive FtrABCD ferrous iron utilization system of Bordetella species  

PubMed Central

Summary A putative operon encoding an uncharacterized ferrous iron transport (FtrABCD) system was previously identified in cDNA microarray studies. In growth studies using buffered medium at pH values ranging from pH 6.0 to 7.6, Bordetella pertussis and Bordetella bronchiseptica FtrABCD system mutants showed dramatic reductions in growth yields under iron-restricted conditions at pH 6.0, but had no growth defects at pH 7.6. Supplementation of culture medium with 2 mM ascorbate reductant was inhibitory to alcaligin siderophore-dependent growth at pH 7.6, but had a neglible effect on FtrABCD system-dependent iron assimilation at pH 6.0 consistent with its predicted specificity for ferrous iron. Unlike Bordetella siderophore-dependent and haem iron transport systems, and in agreement with its hypothesized role in transport of inorganic iron from periplasm to cytoplasm, FtrABCD system function did not require the TonB energy transduction complex. Gene fusion analysis revealed that ftrABCD promoter activity was maximal under iron-restricted growth conditions at acidic pH. The pH of human airway surface fluids ranges from pH 5.5 to 7.9, and the FtrABCD system may supply ferrous iron necessary for Bordetella growth in acidic host microenvironments in which siderophores are ineffective for iron retrieval.

Brickman, Timothy J.; Armstrong, Sandra K.

2012-01-01

214

An experimental determination of ferrous chloride and acetate complexation in aqueous solutions to 300癈  

NASA Astrophysics Data System (ADS)

The formation of the monochloroiron(II) complex, FeCl + , was studied potentiometrically from 125 to 295癈 at 25 degree intervals at one molal ionic strength in aqueous solutions containing acetic acid, sodium acetate, and sodium trifluoromethanesulfonate. In this method, competition between chloride and acetate ions for the ferrous cation resulted in a change in solution pH, which in turn was monitored in situ in a hydrogen-electrode, concentration cell. A simple empirical approach was used to extrapolate these formation quotients to infinite dilution. The resulting constants proved to be in excellent agreement with previous spectrophotometric results obtained from 25 to 200癈. Thus, the present study confirms the validity of the conclusions made based on these earlier data concerning the solubility of Fe-containing minerals in hydrothermal brines. Formation constants at infinite dilution for FeCl + are compared with the stability of ferrous acetate and hydroxide complexes. The original potentiometric titration data for ferrous acetate complex formation were combined in a new fit with values determined from the present study at unit ionic strength. Two empirical treatments (namely the isocoulombic method and the temperature/water density function) were considered for fitting and extrapolating the infinite dilution formation constants to 350癈.

Palmer, Donald A.; Hyde, K. E.

1993-04-01

215

Probing chelation motifs in HIV integrase inhibitors  

PubMed Central

A series of HIV integrase (HIV-1 IN) inhibitors were synthesized to evaluate the role of the metal-binding group (MBG) in this class of metalloenzyme inhibitors. A total of 21 different raltegravir-chelator derivative (RCD) compounds were prepared that differed only in the nature of the MBG. These IN strand-transfer inhibitors (INSTIs) were evaluated in vitro in cell-free enzyme activity assays, and the in vitro results were further validated in cell culture experiments. All of the active compounds showed selective inhibition of the strand-transfer reaction over 3?-processing, suggesting a common mode of action with raltegravir. The results of the in vitro activity suggest that the nature of the MBG donor atoms, the overall MBG structure, and the specific arrangement of the MBG donor atom triad are essential for obtaining maximal HIV-1 IN inhibition. At least two compounds (RCD-4, RCD-5) containing a hydroxypyrone MBG were found to display superior strand-transfer inhibition when compared to an abbreviated analogue of raltegravir (RCD-1). By isolating and examining the role of the MBG in a series of INSTIs, we have identified a scaffold (hydroxypyrones) that may provide access to a unique class of HIV-1 IN inhibitors, and may help overcome rising raltegravir resistance.

Agrawal, Arpita; DeSoto, Jamie; Fullagar, Jessica L.; Maddali, Kasthuraiah; Rostami, Shahrzad; Richman, Douglas D.; Pommier, Yves; Cohen, Seth M.

2012-01-01

216

Car朠arrinello molecular dynamics in the DFT + U formalism: Structure and energetics of solvated ferrous and ferric ions  

SciTech Connect

The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. We implemented a rotationally-invariant Hubbard U extension to density-functional theory in the Car朠arrinello molecular dynamics framework, with the goal of bringing the accuracy of the DFT + U approach to finite-temperature simulations, especially for liquids or solids containing transition-metal ions. First, we studied the effects on the Hubbard U on the static equilibrium structure of the hexaaqua ferrous and ferric ions, and the inner-sphere reorganization energy for the electron-transfer reaction between aqueous ferrous and ferric ions. It is found that the reorganization energy is increased, mostly as a result of the Fe朞 distance elongation in the hexa-aqua ferrous ion. Second, we performed a first-principles molecular dynamics study of the solvation structure of the two aqueous ferrous and ferric ions. The Hubbard term is found to change the Fe朞 radial distribution function for the ferrous ion, while having a negligible effect on the aqueous ferric ion. Moreover, the frequencies of vibrations between Fe and oxygen atoms in the first-solvation shell are shown to be unaffected by the Hubbard corrections for both ferrous and ferric ions.

Sit, P H L.; Cococcioni, Matteo; Marzari, Nicola N.

2007-09-01

217

An Evaluation of the Chelating Agent EDDS for Marigold Production  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aminopolycarboxylic acid (APCA) ligands (chelating agents) like ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) are commonly used in soluble fertilizers to supply copper (Cu), iron (Fe), manganese (Mn), and/or zinc (Zn) to plants. The offsite runoff and contamina...

218

Electrokinetic remediation of concrete: effect of chelating agents.  

PubMed

Contamination of concrete at various nuclear power plants and spent nuclear fuel reprocessing facilities by radionuclides represents a significant problem for the world's nuclear power industries and nuclear waste management. The present publication summarizes the most recently published data on Electrokinetic Remediation (EK) of various concrete installations and advantageous effects of the combination of EK with different chelating agents. The specific aspects of decontamination of concrete and mortar surfaces are analyzed, such as: (a) effect of chelating agents (EDTA, citric acid), (b) effect of the zeta-potential (zeta) of concrete surface, (c) effects of sorption and complex formation equilibrium, and (d) specific advantages and problems of the electrokinetic decontamination process. The results of laboratory and in situ tests of chelating agent assisted EK removal of radionuclides are reported. It is demonstrated that the correct combination of EK with specific chelating agents can be effectively employed for decontamination of concrete surfaces. PMID:18313182

Popov, K; Glazkova, I; Yachmenev, V; Nikolayev, A

2008-03-03

219

Ligation of water to magnesium chelates of biological importance.  

PubMed

Water binding to several Mg(2+) chelates, ethylenediamine, ethylenediamine-N,N'-diacetate, porphyrin, chlorophyll a and bacteriochlorophyll a, to form five- and six-coordinate complexes is studied by means of density functional theory. The results obtained for magnesium chelates are compared with the properties of the respective aqua complexes and the influence of the permittivity of environment on the ligand binding energies is discussed. Although the most common coordination number of Mg(2+) is six, in the tetrapyrrolic chelates it is reduced to five because the accommodation of the sixth water ligand results in no gain in energy. This is in line with the experimental observations made for coordination of chlorophylls in vivo. The binding between Mg(2+) and water is mostly of electrostatic nature, which is supported by the finding that its energy is correlated both with the electron density of the chelator and with electrostatic potential determined at the ligand binding site. PMID:22643978

Rutkowska-Zbik, Dorota; Witko, Ma?gorzata; Fiedor, Leszek

2012-05-29

220

3-hydroxy-2(1H)-pyridinone chelating agents  

DOEpatents

Disclosed is a series of improved chelating agents and the chelates formed from these agents, which are highly effective upon both injection and oral administration. Several of the most effective are of low toxicity. These chelating agents incorporate within their structure 3-hydroxy-2-pyridinone (3,2-HOPO) moieties with a substituted carbamoyl group ortho to the hydroxy group of the hydroxypyridinone ring. The electron-withdrawing carbamoyl group increases the acidity, as well as the chemical stability towards oxidation and reduction, of the hydroxypyridinones. In the metal complexes of the chelating agents, the amide protons form very strong hydrogen bonds with the adjacent HOPO oxygen donor, making these complexes very stable at physiological conditions. The terminal N-substituents provide a certain degree of lipophilicity to the 3,2-HOPO, increasing oral activity.

Raymond, Kenneth (Berkeley, CA); Xu, Jide (Berkeley, CA)

1999-01-01

221

Strategies for the preparation of bifunctional gadolinium(III) chelators  

PubMed Central

The development of gadolinium chelators that can be easily and readily linked to various substrates is of primary importance for the development high relaxation efficiency and/or targeted magnetic resonance imaging (MRI) contrast agents. Over the last 25 years a large number of bifunctional chelators have been prepared. For the most part, these compounds are based on ligands that are already used in clinically approved contrast agents. More recently, new bifunctional chelators have been reported based on complexes that show a more potent relaxation effect, faster complexation kinetics and in some cases simpler synthetic procedures. This review provides an overview of the synthetic strategies used for the preparation of bifunctional chelators for MRI applications.

Frullano, Luca; Caravan, Peter

2012-01-01

222

Minding Metals: Tailoring Multifunctional Chelating Agents for Neurodegenerative Disease  

PubMed Central

Neurodegenerative diseases like Alzheimer's and Parkinson's disease are associated with elevated levels of iron, copper, and zinc and consequentially high levels of oxidative stress. Given the multifactorial nature of these diseases, it is becoming evident that the next generation of therapies must have multiple functions to combat multiple mechanisms of disease progression. Metal-chelating agents provide one such function as an intervention for ameliorating metal-associated damage in degenerative diseases. Targeting chelators to adjust localized metal imbalances in the brain, however, presents significant challenges. In this perspective, we focus on some noteworthy advances in the area of multifunctional metal chelators as potential therapeutic agents for neurodegenerative diseases. In addition to metal chelating ability, these agents also contain features designed to improve their uptake across the blood-brain barrier, increase their selectivity for metals in damage-prone environments, increase antioxidant capabilities, lower A? peptide aggregation, or inhibit disease-associated enzymes such as monoamine oxidase and acetylcholinesterase.

Perez, Lissette R.; Franz, Katherine J.

2010-01-01

223

Metal chelate process to remove pollutants from fluids  

SciTech Connect

The present invention relates to improved methods using an organic iron chelate to remove pollutants from fluids, such as flue gas. Specifically, the present invention relates to a process to remove NO.sub.x and optionally SO.sub.2 from a fluid using a metal ion (Fe.sup.2+) chelate wherein the ligand is a dimercapto compound wherein the --SH groups are attached to adjacent carbon atoms (HS--C--C--SH) or (SH--C--CCSH) and contain a polar functional group so that the ligand of DMC chelate is water soluble. Alternatively, the DMC' is covalently attached to a water insoluble substrate such as a polymer or resin, e.g., polystyrene. The chelate is regenerated using electroreduction or a chemical additive. The dimercapto compound bonded to a water insoluble substrate is also useful to lower the concentration or remove hazardous metal ions from an aqueous solution.

Chang, Shih-Ger T. (El Cerrito, CA)

1994-01-01

224

Chelators at the cancer coalface: desferrioxamine to Triapine and beyond.  

PubMed

The importance of iron and copper in cancer biology has been well established. Iron plays a fundamental role in cellular proliferation and copper has been shown to be a significant cofactor for angiogenesis. Early observations with the chelator used for the treatment of iron overload, desferrioxamine, showed that it had promise as an anticancer agent. These results sparked great interest in the possibility of developing more effective iron chelators for cancer therapy. The recent entry into clinical trials of the iron-binding drug, Triapine, provides evidence of the potential of this antitumor strategy. Likewise, chelators originally designed to treat disorders of copper overload, such as penicillamine, trientine, and tetrathiomolybdate, have also emerged as potential anticancer drugs, as they are able to target the key angiogenic cofactor, copper. In this review, we will discuss the development of these and other chelators that show potential as anticancer agents. PMID:17145804

Yu, Yu; Wong, Jacky; Lovejoy, David B; Kalinowski, Danuta S; Richardson, Des R

2006-12-01

225

3-hydroxy-2(1H)-pyridinone chelating agents  

DOEpatents

Disclosed is a series of improved chelating agents and the chelates formed from these agents, which are highly effective upon both injection and oral administration. Several of the most effective are of low toxicity. These chelating agents incorporate within their structure 3-hydroxy-2-pyridinone (3,2-HOPO) moieties with a substituted carbamoyl group ortho to the hydroxy group of the hydroxypyridinone ring. The electron-withdrawing carbamoyl group increases the acidity, as well as the chemical stability towards oxidation and reduction, of the hydroxypyridinones. In the metal complexes of the chelating agents, the amide protons form very strong hydrogen bonds with the adjacent HOPO oxygen donor, making these complexes very stable at physiological conditions. The terminal N-substituents provide a certain degree of lipophilicity to the 3,2-HOPO, increasing oral activity. 2 figs.

Raymond, K.; Xu, J.

1999-04-06

226

Chelation in metal intoxication XVI. Influence of chelating agents on chromate poisoned rats  

SciTech Connect

The ability of selective polyaminocarboxylic acids and common drugs to reduce the body burden of chromium and restore Cr induced biochemical alterations in chromate intoxicated rats was investigated. 1,2 Cychlohexylene dinitrilotetraacetic acid (CDTA) and triethylenetetramine hexacetic acid (TTHA) were more effective than p-aminosalicylic acid (PAS) and isoniazid (INH) in enhancing urinary excretion of Cr, lowering hepatic and blood levels of Cr and restoring inhibited activity of hepatic aldolase. The chromate antidotal property of chelators seem to be related to the combination of nitrogen and oxygen as the electron donating centres.

Tandon, S.K.; Srivastava, L.

1985-01-01

227

Effects of chelators on mercury, iron, and lead neurotoxicity in cortical culture  

Microsoft Academic Search

Chelation therapy for the treatment of acute, high dose exposure to heavy metals is accepted medical practice. However, a much wider use of metal chelators is by alternative health practitioners for so called chelation therapy. Given this widespread and largely unregulated use of metal chelators it is important to understand the actions of these compounds. We tested the effects of

Travis Rush; Julie Hjelmhaug; Doug Lobner

2009-01-01

228

Effect of Fe stress on utilization of Fe chelates by efficient and inefficient plant species  

Microsoft Academic Search

Using a double labelled Fe chelate (FeEDDHA) it has been possible to show that plants can take up Fe both, as an intact Fe chelate molecule and as ionic Fe after chelate splitting.The rate of chelate splitting in the roots is determined mainly by the Fe nutritional status of the particular plant species but also by the cation exchange capacity

V. R鰉held; H. Marschner

1981-01-01

229

Bidentate palladium(II) chelation by the common aldoses.  

PubMed

The [Pd(II){(R,R)-chxn}(OH)(2)] reagent (chxn=1,2-diaminocyclohexane) is introduced as a metal probe for the detection of the bidentate chelating sites of a glycose. Two moles of hydroxide per mole palladium support double deprotonation of potentially chelating diol functions at a glycose's backbone. The individual chelating sites are detected using one- and two-dimensional NMR techniques. At equimolar amounts of palladium(II) and aldose, the metal-binding sites include mostly the hydroxy function at the anomeric carbon atom. Chelators are derived from both the pyranose and the furanose isomers. Most pyranose-based chelators form five-membered chelate rings by using their 1,2-diol function. Though 1,2-diolate bonding is also common to the furanoses, the formation of six-membered chelate rings by 1,3-bonding is more significant for them. Metal-excess conditions provoke mostly bis-bidentate 1,2;3,4-chelation but unusual isomers form also: thus d-xylose is dimetallated in its all-axial beta-pyranose form, and erythrose's dimetallation results in the formation of two isomers of a metal derivative of the open-chain hydrate. The spectroscopic results are supported by crystal-structure determinations on [Pd{(R,R)-chxn}(alpha-D-Xylp1,2H(-2)-kappaO(1,2))].H(2)O (Xyl=xylose), [Pd{(R,R)-chxn}(alpha-D-Ribp1,2H(-2)-kappaO(1,2))].2.25H(2)O (Rib=ribose), [Pd{(R,R)-chxn}(alpha-L-Thrf1,3H(-2)-kappaO(1,3))].2H(2)O (Thr=threose) and [Pd{(R,R)-chxn}(alpha-D-Eryf1,3H(-2)-kappaO(1,3))].3H(2)O (Ery=erythrose). PMID:19508913

Arendt, Yvonne; Labisch, Oliver; Kl黤ers, Peter

2009-04-12

230

Antibacterial Activities of Iron Chelators against Common Nosocomial Pathogens  

PubMed Central

The activities of iron chelators (deferoxamine, deferiprone, Apo6619, and VK28) were evaluated against type strains of Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli. Deferiprone, Apo6619, and VK28 each inhibited growth in standard and RPMI tissue culture medium, while deferoxamine had no effect. Additionally, time-kill assays revealed that VK28 had a bacteriostatic effect against S. aureus. Therefore, these newly developed iron chelators might provide a nontraditional approach for treatment of bacterial infections.

Thompson, Mitchell G.; Corey, Brendan W.; Si, Yuanzheng; Craft, David W.

2012-01-01

231

Kinetics of dissociation of trivalent actinide chelates of TMDTA  

Microsoft Academic Search

Measurements by a radiotracer technique show that the dissociation of TMDTA (trimethylenediamine-N,N-tetraacetic acid) chelates with Am, Cm, Bk, Cf, and Eu proceeds through an acid-catalyzed pathway. The rates of dissociation of An(TMDTA)鈦 are 2 orders of magnitude faster than those of the corresponding EDTA chelates, presumably due to the greater lability of the nitrogen atom in the six-membered nitrogen-metal-nitrogen ring

A. C. Muscatello; G. R. Choppin; W. DOlieslager

1989-01-01

232

Metal ion chelating peptides with superoxide dismutase activity  

Microsoft Academic Search

The superoxide dismutase activities of two novel synthetic chelating peptides are reported. The peptides comprise a polyaminocarboxylic acid chelator (EDTA) conjugated to tyrosine (ET1) and phenylalanine (EP1). Superoxide dismutase (SOD) activity was exhibited for Cu(II) but not the Fe(III) complexes. The mimetic activities were compared to bovine erythrocyte SOD (3730 U\\/mg) and exhibited activities of 1119 U\\/mg for ET1-Cu(II) and

A. E. O. Fisher; D. P. Naughton

2005-01-01

233

Synthetic Iron Chelates to Correct Iron Deficiency in Plants  

Microsoft Academic Search

This article reviews the effectiveness of synthetic Fe-chelates to correct Fe chlorosis. Soil application of such compounds is usually a more efficient strategy to overcome Fe chlorosis of crops grown on calcareous soils as compared with treatments based on inorganic Fe salts or weak Fe-complexes. To understand the effectiveness of Fe-chelates, it is necessary to have knowledge on their stability,

Juan J. Lucena

234

Iron chelators ICL670 and 311 inhibit HIV-1 transcription  

SciTech Connect

HIV-1 replication is induced by an excess of iron and iron chelation by desferrioxamine (DFO) inhibits viral replication by reducing proliferation of infected cells. Treatment of cells with DFO and 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone (311) inhibit expression of proteins that regulate cell-cycle progression, including cycle-dependent kinase 2 (CDK2). Our recent studies showed that CDK2 participates in HIV-1 transcription and viral replication suggesting that inhibition of CDK2 by iron chelators might also affect HIV-1 transcription. Here we evaluated the effect of a clinically approved orally effective iron chelator, 4-[3,5-bis-(hydroxyphenyl)-1,2,4-triazol-1-yl]-benzoic acid (ICL670) and 311 on HIV-1 transcription. Both ICL670 and 311 inhibited Tat-induced HIV-1 transcription in CEM-T cells, 293T and HeLa cells. Neither ICL670 nor 311 induced cytotoxicity at concentrations that inhibited HIV-1 transcription. The chelators decreased cellular activity of CDK2 and reduced HIV-1 Tat phosphorylation by CDK2. Neither ICL670A or 311 decreased CDK9 protein level but significantly reduced association of CDK9 with cyclin T1 and reduced phosphorylation of Ser-2 residues of RNA polymerase II C-terminal domain. In conclusion, our findings add to the evidence that iron chelators can inhibit HIV-1 transcription by deregulating CDK2 and CDK9. Further consideration should be given to the development of iron chelators for future anti-retroviral therapeutics.

Debebe, Zufan; Ammosova, Tatyana [Center for Sickle Cell Disease, Howard University College of Medicine, 520 W. St., N.W., Washington, DC 20060 (United States); Jerebtsova, Marina [Children's National Medical Center, CRI Center for Cancer and Immunology, 111 Michigan Ave., N.W., Washington, DC 20060 (United States); Kurantsin-Mills, Joseph [Department of Biophysics and Physiology, Howard University College of Medicine, 520 W. St., N.W., Washington, DC 20060 (United States); Niu, Xiaomei; Charles, Sharroya [Center for Sickle Cell Disease, Howard University College of Medicine, 520 W. St., N.W., Washington, DC 20060 (United States); Richardson, Des R. [Iron Metabolism and Chelation Program, Department of Pathology, Blackburn Building (D06), University of Sydney, Sydney, New South Wales, 2006 Australia (Australia); Ray, Patricio E. [Children's National Medical Center, CRI Center for Cancer and Immunology, 111 Michigan Ave., N.W., Washington, DC 20060 (United States); Gordeuk, Victor R. [Center for Sickle Cell Disease, Howard University College of Medicine, 520 W. St., N.W., Washington, DC 20060 (United States); Nekhai, Sergei [Center for Sickle Cell Disease, Howard University College of Medicine, 520 W. St., N.W., Washington, DC 20060 (United States); Department of Biochemistry and Molecular Biology, Howard University College of Medicine, 520 W. St., N.W., Washington, DC 20060 (United States)], E-mail: snekhai@howard.edu

2007-10-25

235

Lead chelates of meso- and racemic-dimercaptosuccinic acid.  

PubMed

Lead chelates of racemic- and meso-dimercaptosuccinic acid (DMSA) were synthesized and isolated from aqueous solutions and characterized by potentiometric measurements and infrared spectroscopy. Two types of lead chelates of racemic DMSA were isolated: one in which racemic-DMSA is coordinated to Pb+2 via one oxygen and one sulfur atom and the other in which the Pb2+ is coordinated via two sulfur atoms. The latter form of the chelate is converted into the former upon dissolution in dimethylsulfoxide. Only one type of Pb2+ chelate of the meso form of the ligand was formed. In this case, meso-DMSA is coordinated to Pb+2 via one oxygen and one sulfur atom. Meso- and racemic-DMSA have very different solubilities in aqueous solutions. Meso-DMSA is slightly soluble in water, whereas racemic-DMSA is very soluble in water even in the presence of strong acids. The solubilities of the chelates were found to be pH dependent. When the uncoordinated sulfhydryl and carboxylic acid groups dissociate, the chelates dissolve and remain in aqueous solution. The infrared spectra of meso- and racemic-DMSA show distinct features that can be used to detect the presence of either diastereoisomer. PMID:2560792

Rivera, M; Aposhian, H V; Fernando, Q

1989-12-01

236

Lead chelation to immobilised Symphytum officinale L. (comfrey) root tannins.  

PubMed

Reported correlations between tannin level and metal accumulation within plant tissues suggest that metal-chelating tannins may help plants to tolerate toxic levels of heavy metal contaminants. This paper supports such correlations using a new method that demonstrated the ability of plant tannins to chelate heavy metals, and showed that the relative levels of tannins in tissues were quantitatively related to lead chelation in vitro. Using this in vitro metal chelation method, we showed that immobilised tannins prepared from lateral roots of Symphytum officinale L., that contained high tannin levels, chelated 3.5 times more lead than those from main roots with lower tannin levels. This trend was confirmed using increasing concentrations of tannins from a single root type, and using purified tannins (tannic acid) from Chinese gallnuts. This study presents a new, simple, and reliable method that demonstrates direct lead-tannin chelation. In relation to phytoremediation, it also suggests that plant roots with more 'built-in' tannins may advantageously accumulate more lead. PMID:19477483

Chin, Lily; Leung, David W M; Harry Taylor, H

2009-05-27

237

Extraction of metals using supercritical fluid and chelate forming ligand  

DOEpatents

A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent is described. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated {beta}-diketone. In especially preferred embodiments the extraction solvent is supercritical carbon dioxide, and the chelating agent comprises a fluorinated {beta}-diketone and a trialkyl phosphate, or a fluorinated {beta}-diketone and a trialkylphosphine oxide. Although a trialkyl phosphate can extract lanthanides and actinides from acidic solutions, a binary mixture comprising a fluorinated {beta}-diketone and a trialkyl phosphate or a trialkylphosphine oxide tends to enhance the extraction efficiencies for actinides and lanthanides. The method provides an environmentally benign process for removing contaminants from industrial waste without using acids or biologically harmful solvents. The method is particularly useful for extracting actinides and lanthanides from acidic solutions. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process. 7 figs.

Wai, C.M.; Laintz, K.E.

1998-03-24

238

Modeling ferrous ferric iron chemistry with application to martian surface geochemistry  

NASA Astrophysics Data System (ADS)

The Mars Global Surveyor, Mars Exploration Rover, and Mars Express missions have stimulated considerable thinking about the surficial geochemical evolution of Mars. Among the major recent mission findings are the presence of jarosite (a ferric sulfate salt), which requires formation from an acid-sulfate brine, and the occurrence of hematite and goethite on Mars. Recent ferric iron models have largely focused on 25 癈, which is a major limitation for models exploring the geochemical history of cold bodies such as Mars. Until recently, our work on low-temperature iron-bearing brines involved ferrous but not ferric iron, also obviously a limitation. The objectives of this work were to (1) add ferric iron chemistry to an existing ferrous iron model (FREZCHEM), (2) extend this ferrous/ferric iron geochemical model to lower temperatures (<0 癈), and (3) use the reformulated model to explore ferrous/ferric iron chemistries on Mars. The FREZCHEM model is an equilibrium chemical thermodynamic model parameterized for concentrated electrolyte solutions using the Pitzer approach for the temperature range from <-70 to 25 癈 and the pressure range from 1 to 1000 bars. Ferric chloride and sulfate mineral parameterizations were based, in part, on experimental data. Ferric oxide/hydroxide mineral parameterizations were based exclusively on Gibbs free energy and enthalpy data. New iron parameterizations added 23 new ferrous/ferric minerals to the model for this Na-K-Mg-Ca-Fe(II)-Fe(III)-H-Cl-SO 4-NO 3-OH-HCO 3-CO 3-CO 2-O 2-CH 4-H 2O system. The model was used to develop paragenetic sequences for Rio Tinto waters on Earth and a hypothetical Martian brine derived from acid weathering of basaltic minerals. In general, model simulations were in agreement with field evidence on Earth and Mars in predicting precipitation of stable iron minerals such as jarosites, goethite, and hematite. In addition, paragenetic simulations for Mars suggest that other iron minerals such as lepidocrocite, schwertmannite, ferricopiapite, copiapite, and bilinite may also be present on the surface of Mars. Evaporation or freezing of the Martian brine led to similar mineral precipitates. However, in freezing, compared to evaporation, the following key differences were found: (1) magnesium sulfates had higher hydration states; (2) there was greater total aqueous sulfate (SO 4T = SO 4 + HSO 4) removal; and (3) there was a significantly higher aqueous Cl/SO 4T ratio in the residual Na-Mg-Cl brine. Given the similarities of model results to observations, alternating dry/wet and freeze/thaw cycles and brine migration could have played major roles in vug formation, Cl stratification, and hematite concretion formation on Mars.

Marion, Giles M.; Kargel, Jeffrey S.; Catling, David C.

2008-01-01

239

Modeling aqueous ferrous iron chemistry at low temperatures with application to Mars  

USGS Publications Warehouse

Major uncertainties exist with respect to the aqueous geochemical evolution of the Martian surface. Considering the prevailing cryogenic climates and the abundance of salts and iron minerals on Mars, any attempt at comprehensive modeling of Martian aqueous chemistry should include iron chemistry and be valid at low temperatures and high solution concentrations. The objectives of this paper were to (1) estimate ferrous iron Pitzer-equation parameters and iron mineral solubility products at low temperatures (from < 0 ??C to 25 ??C), (2) incorporate these parameters and solubility products into the FREZCHEM model, and (3) use the model to simulate the surficial aqueous geochemical evolution of Mars. Ferrous iron Pitzer-equation parameters were derived in this work or taken from the literature. Six new iron minerals [FeCl2??4H2O, FeCl2??6H2O, FeSO4??H2O, FeSO4??7H2O, FeCO3, and Fe(OH)3] were added to the FREZCHEM model bringing the total solid phases to 56. Agreement between model predictions and experimental data are fair to excellent for the ferrous systems: Fe-Cl, Fe-SO4, Fe-HCO3, H-Fe-Cl, and H-Fe-SO4. We quantified a conceptual model for the aqueous geochemical evolution of the Martian surface. The five stages of the conceptual model are: (1) carbonic acid weathering of primary ferromagnesian minerals to form an initial magnesium-iron-bicarbonate-rich solution; (2) evaporation and precipitation of carbonates, including siderite (FeCO3), with evolution of the brine to a concentrated NaCl solution; (3) ferrous/ferric iron oxidation; (4) either evaporation or freezing of the brine to dryness; and (5) surface acidification. What began as a dilute Mg-Fe-HCO3 dominated leachate representing ferromagnesian weathering evolved into an Earth-like seawater composition dominated by NaCl, and finally into a hypersaline Mg-Na-SO4-Cl brine. Weathering appears to have taken place initially under conditions that allowed solution of ferrous iron [low O2(g)], but later caused oxidation of iron [high O2(g)]. Surface acidification and/or sediment burial can account for the minor amounts of Martian surface carbonates. This model rests on a large number of assumptions and is therefore speculative. Nevertheless, the model is consistent with current understanding concerning surficial salts and minerals based on Martian meteorites, Mars lander data, and remotely-sensed spectral analyses. ?? 2003 Elsevier Ltd.

Marion, G. M.; Catling, D. C.; Kargel, J. S.

2003-01-01

240

Carboxylate-containing chelating agent interactions with amorphous chromium hydroxide: Adsorption and dissolution  

Microsoft Academic Search

Anthropogenic chelating agents and biological chelating agents produced by indigenous organisms may dissolve CrIII (hydr)oxides in soils and sediments. The resulting dissolved CrIII-chelating agent complexes are more readily transported through porous media, thereby spreading contamination. With this work, we examine chelating agent-assisted dissolution of amorphous chromium hydroxide (ACH) by the (amino)carboxylate chelating agents iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), tricarballylic

Richard F. Carbonaro; Benjamin N. Gray; Charles F. Whitehead; Alan T. Stone

2008-01-01

241

Method for preparing radionuclide-labeled chelating agent-ligand complexes  

DOEpatents

Radionuclide-labeled chelating agent-ligand complexes that are useful in medical diagnosis or therapy are prepared by reacting a radionuclide, such as .sup.90 Y or .sup.111 In, with a polyfunctional chelating agent to form a radionuclide chelate that is electrically neutral; purifying the chelate by anion exchange chromatography; and reacting the purified chelate with a targeting molecule, such as a monoclonal antibody, to form the complex.

Meares, Claude F. (Davis, CA); Li, Min (Davis, CA); DeNardo, Sally J. (El Macero, CA)

1999-01-01

242

Use of > 1:1 Chelator:Iron Ratios and Strong Iron(III) Chelators in Hydroponic Solutions for Barley  

Microsoft Academic Search

This study examined two guidelines for preparing hydroponic solutions to ensure adequate iron (Fe) for Poaceae plants: (1) not to add chelator in excess of Fe concentrations and (2) to use only weaker forms of Fe(III) chelators. Barley was grown in low-Fe solutions for 9 d and transferred to Fe-spiked nutrient solutions at pH 8.1 containing ligand:Fe ? M concentrations

Paul F. Bell; G. L. Kerven; D. G. Edwards; C. J. Asher

2005-01-01

243

Amelioration of iron overload-induced liver toxicity by a potent antioxidant and iron chelator, Emblica officinalis Gaertn.  

PubMed

In liver, the major site of iron storage, iron overload is associated with oxidative damage of protein, lipid, and DNA and causes protein oxidation, lipid peroxidation, and rupture of hepatocytes, leading to cell death. Serum ferritin and liver iron content are the main forecasters of moderate to severe iron overload in the liver. The sequels of excess iron deposition in the liver are fibrosis and enhanced levels of serum enzymes and bilirubin markers. Emblica officinalis (EO) fruit extract was found efficient in lessening intraperitoneally injected iron dextran-induced liver toxicity in Swiss albino mice. Mice administered with different doses of 70% methanol extract of EO (50, 100, and 200 mg kg(-1) body weight) showed significant decrease in liver iron, serum ferritin, and serum enzyme levels, along with the decrease in lipid peroxidation, protein oxidation, and collagen content. The activity was further supported by its considerable iron chelation with half-maximal inhibitory concentration of 70.24 2.74 ?g ml(-1) and the protection on ferrous ion-mediated DNA breakdown with 50% protection ([P]50) of 1.04 0.01 ?g ml(-1). Simultaneously, the extract effectively induced the antioxidant enzyme levels and also exhibited the potential activity of reductive release of ferritin iron. These findings suggest that the EO extract may be used as a potent drug for the treatment of pathological sequences arisen in the iron overload-induced liver damage. PMID:23524878

Sarkar, Rhitajit; Hazra, Bibhabasu; Mandal, Nripendranath

2013-03-22

244

The magnesium chelation step in chlorophyll biosynthesis  

SciTech Connect

In photosynthetic organisms, the biogenesis of energy transducing membranes requires the coordinate synthesis of prosthetic groups, proteins, and various lipids. Two of the major prosthetic groups, chlorophyll and heme, share a common biosynthetic pathway that diverges at the point of metal insertion into protoporphyrin IX (Proto). Insertion of iron leads to the formation of hemes, while insertion of magnesium is the first step unique to chlorophyll formation. This project is directed toward identifying the enzyme(s) responsible for magnesium chelation and elucidating the mechanism which regulates the flux of precursors through the branch point enzymes in isolated chloroplasts. Using intact chloroplasts from greening cucumber cotyledons, we have confirmed the ATP requirement for Mg-Proto formation. Use of non-hydrolyzable ATP analogs, uncouplers and ionophores has led to the conclusions that ATP hydrolysis is necessary, but that this hydrolysis is not linked to the requirement for membrane intactness by transmembrane ion gradients or electrical potentials. The enzyme(s) are flexible with respect to the porphyrin substrate specificity, accepting porphyrins with -vinyl, -ethyl, or -H substituents at the 2 and 4 positions. The activity increases approximately four-fold during greening. Possible physiological feedback inhibitors such as heme, protochlorophyllide, and chlorophyllide had no specific effect on the activity. The activity has now been assayed in barely, corn and peas, with the system from peas almost ten-fold more active than the cucumber system. Work is continuing in pea chloroplasts with the development of a continuous assay and investigation of the feasibility of characterizing an active, organelle-free preparation. 6 figs.

Weinstein, J.

1990-11-01

245

Development of tridentate iron chelators: from desferrithiocin to ICL670.  

PubMed

Successful treatment of beta-thalassemia requires two key elements: blood transfusion and iron chelation. Regular blood transfusions considerably expand the lifespan of patients, however, without the removal of the consequential accumulation of body iron, few patients live beyond their second decade. In 1963, the introduction of desferrioxamine (DFO), a hexadentate chelator, marked a breakthrough in the treatment of beta-thalassemia. DFO significantly reduces body iron burden and iron-related morbidity and mortality. DFO is still the only drug for general use in the treatment of transfusion dependent iron overload. However, its very short plasma half-life and poor oral activity necessitate special modes of application (subcutaneous or intravenous infusion) which are inconvenient, can cause local reactions and are difficult to be accepted by many patients. Over the past four decades, many different laboratories have invested major efforts in the identification of orally active iron chelators from several hundreds of molecules of synthetic, microbial or plant origin. The discovery of ferrithiocin in 1980, followed by the synthesis of the tridentate chelator desferrithiocin and proof of its oral activity raised a lot of hope. However, the compound proved to be toxic in animals. Over a period of about fifteen years many desferrithiocin derivatives and molecules with broader alterations led to the discovery of numerous new compounds some of which were much better tolerated and were more efficacious than desferrithiocin in animals, however, none was safe enough to proceed to the clinical use. The discovery of a new chemical class of iron chelators: The bis-hydroxyphenyltriazoles re-energized the search for a safe tridentate chelator. The basic structure of this completely new chemical class of iron chelators was discovered by a combination of rational design, intuition and experience. More than forty derivatives of the triazole series were synthesized at Novartis. These compounds were evaluated, together with more than 700 chelators from various chemical classes. Using vigorous selection criteria with a focus on tolerability, the tridentate chelator 4-[(3,5-Bis-(2-hydroxyphenyl)-1,2,4)triazol-1-yl]-benzoic acid (ICL670) emerged as an entity which best combined high oral potency and tolerability in animals. ICL670 is presently being evaluated in the clinic. PMID:12678677

Nick, Hanspeter; Acklin, Pierre; Lattmann, Ren; Buehlmayer, Peter; Hauffe, Suzanne; Schupp, Joachim; Alberti, Daniele

2003-06-01

246

Chelating Polymers. III. Chelating Monomers and Polymers from s-Triazinyl Substituted Hydrazinoacetic Acids  

Microsoft Academic Search

The model chelating compounds ?-[2,4-bis(dimethylamino)-s-triazin-6-yl] hydrazinoacetic acid, ?-[2,4-bis(dimethylaniino)-s-triazind-yl] hydrazino-N, N-diacetic acid, 2,4-bis(dimethylamino)-s-triazin-6-yl-aminoacetic acid, and 2,4-bis(dimethylamino)-s-triazin-6-yl-iminodiacetic acid have been synthesized and characterized by composition analysis, infrared spectroscopy, and potentiometric titration data. The copper(II), nickel(II), cobalt(II), zinc(II), magnesium(II), and palladium(II) complexes of the first two model compounds, and the copper, nickel, cobalt, and zinc complexes of the third and fourth model compounds

G. F. Dalelio; E. T. Hofman; T. R. Dehner

1970-01-01

247

3-hydroxy-2(1H)-pyridinone chelating agents  

DOEpatents

Disclosed is a series of improved metal chelating agents, which are highly effective upon both injection and oral administration; several of the most effective are of low toxicity. These chelating agents incorporate within their structure 1-hydroxy-2-pyridinone (1,2-HOPO) and 3-hydroxy-2-pyridinone (3,2-HOPO) moieties with a substituted carbamoyl group ortho to the hydroxy or oxo groups of the hydroxypyridinone ring. The electron-withdrawing carbamoyl group increases the acidity of the hydroxypyridinones. In the metal complexes of the chelating agents, the amide protons form very strong hydrogen bonds with its adjacent HOPO oxygen donor, making these complexes very stable at physiological conditions. The terminal N-substituents provides a certain degree of lipophilicity to the 3,2-HOPO, increasing oral activity. Also disclosed is a method of making the chelating agents and a method of producing a known compound, 3-hydroxy-1-alkyl-2(1H)pyridinone, used as a precursor to the chelating agent, safely and in large quantities. 2 figs.

Raymond, K.N.; Xu, J.

1997-04-29

248

Laser-induced photochemistry of nickel chelate thin films  

NASA Astrophysics Data System (ADS)

This work is devoted to the investigation of laser-induced decomposition mechanism of solid films and powders of nickel (II) chelate complexes with dimethylglyoxime Ni (DMG)2 and with dehydrogenated free-radical methyl derivative of 1,2- hydroxylaminooxime Ni(HAO)2. A comparison of stable gaseous products of laser-induced decay of these complexes with those of thermal decomposition have shown considerable difference between them. Sufficiently threshold character of the conversion degree dependence on the power density of XeCl excimer laser irradiation was revealed in the experiments. These two facts being correlated with the data on positive and negative ion chemical ionization mass spectrometry allow to propose a primary process to be predominantly photochemical with two-photon initiation mechanism. The vertical photoionization of one of chelate molecules is suggested to be accompanied by electron transfer to lattice and then by localization of excess electron on antibonding level of neighboring chelate molecule resulting in its fragmentation. The secondary processes of solid chelate decomposition are determined by the pecularities of electronic and stereochemical structure of the complexes. Thin layers of these chelates applied onto Si and SiO2 substrates decompose explosion-like in air under the influence of radiation pulse of XeCl excimer laser. A plume of decomposition products is thrown from the substrate into atmosphere, and a thin layer of dielectric film with refractive index close to the value for nickel hydroxide is deposited on the substrate.

Larionov, Stanislav V.; Badalian, Aram M.; Polyakov, Oleg V.; Prokhorova, Stalina A.; Bakhturova, Lyudmila F.; Myachina, Lyudmila I.

1994-07-01

249

3-hydroxy-2(1H)-pyridinone chelating agents  

DOEpatents

Disclosed is a series of improved metal chelating agents, which are highly effective upon both injection and oral administration; several of the most effective are of low toxicity. These chelating agents incorporate within their structure 1-hydroxy-2-pyridinone (1,2-HOPO) and 3-hydroxy-2-pyridinone (3,2-HOPO) moieties with a substituted carbamoyl group ortho to the hydroxy or oxo groups of the hydroxypyridinone ring. The electron-withdrawing carbamoyl group increases the acidity of the hydroxypyridinones. In the metal complexes of said chelating agents, the amide protons form very strong hydrogen bonds with its adjacent HOPO oxygen donor, making these complexes very stable at physiological conditions. The terminal N-substituents provides a certain degree of lipophilicity to said 3,2-HOPO, increasing oral activity. Also disclosed is a method of making the chelating agents and a method of producing a known compound, 3-hydroxy-1-alkyl-2(1H)pyridinone, used as a precursor to the chelating agent, safely and in large quantities.

Raymond, Kenneth N. (Berkeley, CA); Xu, Jide (Berkeley, CA)

1997-01-01

250

[Iron chelating therapy in adults: How and when?].  

PubMed

Iron overload can lead to tissue damage derived from free radical toxicity. Phlebotomy is the treatment of choice for treating iron overload. However, iron chelating therapy can be used if phlebotomies are impossible, mainly because of anemia. In thalassemia major, iron chelating therapy has dramatically improved life expectancy; it is also used in sickle cell disease and myelodysplastic syndromes. Desferioxamine is the gold standard of iron chelation, but parenteral administration and the burden of a daily infusion pump hinder optimal compliance. Deferiprone is orally active but should be administered three times a day. It has the advantage of removing toxic iron from myocardium, but agranulocytosis (1%) can limit its use. Deferasirox is orally active in a single daily dose, is well tolerated but its cardiac effect is limited. Iron chelating therapy can be considered if serum ferritin is above 1000?g/L and if liver iron concentration assessing by MRI exceeds 80?mol/g. MRI is a very important mean to monitor cardiac iron load. If the relaxing parameter T2* is lower than 20ms, a cardiac effective iron chelator agent or an association with deferoxamine should be used. Benefit/risk ratio should be closely evaluated, mainly in myelodysplastic syndromes. PMID:23195912

Ruivard, M

2012-11-26

251

Characterization of a ferrous iron-responsive two-component system in nontypeable Haemophilus influenzae.  

PubMed

Nontypeable Haemophilus influenzae (NTHI), an opportunistic pathogen that is commonly found in the human upper respiratory tract, has only four identified two-component signal transduction systems. One of these, an ortholog to the QseBC (quorum-sensing Escherichia coli) system, was characterized. This system, designated firRS, was found to be transcribed in an operon with a gene encoding a small, predicted periplasmic protein with an unknown function, ygiW. The ygiW-firRS operon exhibited a unique feature with an attenuator present between ygiW and firR that caused the ygiW transcript level to be 6-fold higher than the ygiW-firRS transcript level. FirRS induced expression of ygiW and firR, demonstrating that FirR is an autoactivator. Unlike the QseBC system of E. coli, FirRS does not respond to epinephrine or norepinephrine. FirRS signal transduction was stimulated when NTHI cultures were exposed to ferrous iron or zinc but was unresponsive to ferric iron. Notably, the ferrous iron-responsive activation only occurred when a putative iron-binding site in FirS and the key phosphorylation aspartate in FirR were intact. FirRS was also activated when cultures were exposed to cold shock. Mutants in ygiW, firR, and firS were attenuated during pulmonary infection, but not otitis media. These data demonstrate that the H. influenzae strain 2019 FirRS is a two-component regulatory system that senses ferrous iron and autoregulates its own operon. PMID:22961857

Steele, Kendra H; O'Connor, Lauren H; Burpo, Nicole; Kohler, Katharina; Johnston, Jason W

2012-09-07

252

Elucidating the Role of Ferrous Ion Cocatalyst in Enhancing Dilute Acid Pretreatment of Lignocellulosic Biomass  

SciTech Connect

Recently developed iron cocatalyst enhancement of dilute acid pretreatment of biomass is a promising approach for enhancing sugar release from recalcitrant lignocellulosic biomass. However, very little is known about the underlying mechanisms of this enhancement. In the current study, our aim was to identify several essential factors that contribute to ferrous ion-enhanced efficiency during dilute acid pretreatment of biomass and to initiate the investigation of the mechanisms that result in this enhancement. During dilute acid and ferrous ion cocatalyst pretreatments, we observed concomitant increases in solubilized sugars in the hydrolysate and reducing sugars in the (insoluble) biomass residues. We also observed enhancements in sugar release during subsequent enzymatic saccharification of iron cocatalyst-pretreated biomass. Fourier transform Raman spectroscopy showed that major peaks representing the C-O-C and C-H bonds in cellulose are significantly attenuated by iron cocatalyst pretreatment. Imaging using Prussian blue staining indicated that Fe{sup 2+} ions associate with both cellulose/xylan and lignin in untreated as well as dilute acid/Fe{sup 2+} ion-pretreated corn stover samples. Analyses by scanning electron microscopy and transmission electron microscopy revealed structural details of biomass after dilute acid/Fe{sup 2+} ion pretreatment, in which delamination and fibrillation of the cell wall were observed. By using this multimodal approach, we have revealed that (1) acid-ferrous ion-assisted pretreatment increases solubilization and enzymatic digestion of both cellulose and xylan to monomers and (2) this pretreatment likely targets multiple chemistries in plant cell wall polymer networks, including those represented by the C-O-C and C-H bonds in cellulose.

Wei, H.; Donohoe, B. S.; Vinzant, T. B.; Ciesielski, P. N.; Wang, W.; Gedvilas, L. M.; Zeng, Y.; Johnson, D. K.; Ding, S. Y.; Himmel, M. E.; Tucker, M. P.

2011-01-01

253

Pulsed ENDOR Determination of the Arginine Location in Ferrous-NO Form of Neuronal NOS  

PubMed Central

Mammalian nitric oxide synthases (NOSs) are enzymes responsible for oxidation of L-arginine (L-Arg) to nitric oxide (NO). Mechanisms of reactions at the catalytic heme site are not well understood, and it is of current interest to study structures of the heme species that activates O2 and transforms the substrate. The NOS ferrous-NO complex is a close mimic of the obligatory ferric (hydro)peroxo intermediate in NOS catalysis. In this work, pulsed electron-nuclear double resonance (ENDOR) was used to probe the position of the L-Arg substrate at the NO-coordinated ferrous heme center(s) in the oxygenase domain of rat neuronal NOS (nNOS). The analysis of 2H and 15N ENDOR spectra of samples containing D7- or guanidino-15N2 labeled L-Arg has resulted in distance estimates for the nearby guanidino nitrogen and the nearby proton (deuteron) at C?. The L-Arg position was found to be noticeably different from that in the X-ray crystal structure of nNOS ferrous-NO complex [Li et al., J. Biol. Inorg. Chem. 2006, 11, 753768], with the nearby guanidino nitrogen being ~ 0.5 closer to, and the nearby H? about 1 further from the NO ligand than in the X-ray structure. The difference might be related to the structural constraints imposed on the protein by the crystal. Importantly, in spite of its closer position, the guanidino nitrogen does not form a hydrogen bond with the NO ligand, as evidenced by the absence of significant isotropic hfi constant for Ng1. This is consistent with the previous reports that it is not the L-Arg substrate itself that would most likely serve as a direct proton donor to the diatomic ligands (NO and O2) bound to the heme.

Astashkin, Andrei V.; Elmore, Bradley O.; Chen, Li; Fan, Weihong; Guillemette, J. Guy; Feng, Changjian

2012-01-01

254

Characterization of a Ferrous Iron-Responsive Two-Component System in Nontypeable Haemophilus influenzae  

PubMed Central

Nontypeable Haemophilus influenzae (NTHI), an opportunistic pathogen that is commonly found in the human upper respiratory tract, has only four identified two-component signal transduction systems. One of these, an ortholog to the QseBC (quorum-sensing Escherichia coli) system, was characterized. This system, designated firRS, was found to be transcribed in an operon with a gene encoding a small, predicted periplasmic protein with an unknown function, ygiW. The ygiW-firRS operon exhibited a unique feature with an attenuator present between ygiW and firR that caused the ygiW transcript level to be 6-fold higher than the ygiW-firRS transcript level. FirRS induced expression of ygiW and firR, demonstrating that FirR is an autoactivator. Unlike the QseBC system of E. coli, FirRS does not respond to epinephrine or norepinephrine. FirRS signal transduction was stimulated when NTHI cultures were exposed to ferrous iron or zinc but was unresponsive to ferric iron. Notably, the ferrous iron-responsive activation only occurred when a putative iron-binding site in FirS and the key phosphorylation aspartate in FirR were intact. FirRS was also activated when cultures were exposed to cold shock. Mutants in ygiW, firR, and firS were attenuated during pulmonary infection, but not otitis media. These data demonstrate that the H. influenzae strain 2019 FirRS is a two-component regulatory system that senses ferrous iron and autoregulates its own operon.

Steele, Kendra H.; O'Connor, Lauren H.; Burpo, Nicole; Kohler, Katharina

2012-01-01

255

Ferrous Hydroxy Carbonate is a Stable Transformation Product of Biogenic Magnetite  

SciTech Connect

A ~1:1 mixture of ferrihydrite and nanocrystalline akaganeite (?-FeOOH; 10-15 nm) was incubated with Shewanella putrefaciens (strain CN32) under anoxic conditions with lactate as an electron donor and anthraquinone-2,6-disulfonate (AQDS) as an electron shuttle. The incubation was carried out in a 1,4-piperazinediethanesulfonic acid (PIPES)-buffered medium, without PO?? at circumneutral pH. Iron reduction was measured as a function of time (as determined by 0.5 N HCl extraction), and solids were characterized by X-ray diffraction (XRD), electron microscopy, and M鰏sbauer spectroscopy. The biogenic reduction of Fe(III) was rapid; with 60% of the total Fe (Fe???) reduced in one day. Only an additional 10% of Fe??? was reduced over the next three years. A fine-grained (10 nm), cation-excess (CE) magnetite with a Fe(II)/Fe??? ratio of 0.5-0.6 was the sole biogenic product after one day of incubation. The CE magnetite was unstable and partially transformed to micron-sized ferrous hydroxy carbonate [FHC; Fe2 (OH)2CO3?], a rosasite-type mineral, with time. Ferrous hydroxy carbonate dominated the mineral composition of the three year incubated sample. The Fe(II)/Fe??? ratio of the residual CE magnetite after three years of incubation was lower than the day 1 sample and was close to that of stochiometric magnetite (0.33). To best of our knowledge, this is the first report of biogenic FHC, and only the third observation of this material in nature. Ferrous hydroxy carbonate appeared to form by slow reaction of microbially produced carbonate with Fe(II)-excess magnetite. The FHC may be an overlooked mineral phase that explains the infrequent occurrence of fine-grained, biogenic magnetite in anoxic sediments.

Kukkadapu, Ravi K.; Zachara, John M.; Fredrickson, Jim K.; Kennedy, David W.; Dohnalkova, Alice; McCready, David E.

2005-02-02

256

Elucidating the role of ferrous ion cocatalyst in enhancing dilute acid pretreatment of lignocellulosic biomass  

PubMed Central

Background Recently developed iron cocatalyst enhancement of dilute acid pretreatment of biomass is a promising approach for enhancing sugar release from recalcitrant lignocellulosic biomass. However, very little is known about the underlying mechanisms of this enhancement. In the current study, our aim was to identify several essential factors that contribute to ferrous ion-enhanced efficiency during dilute acid pretreatment of biomass and to initiate the investigation of the mechanisms that result in this enhancement. Results During dilute acid and ferrous ion cocatalyst pretreatments, we observed concomitant increases in solubilized sugars in the hydrolysate and reducing sugars in the (insoluble) biomass residues. We also observed enhancements in sugar release during subsequent enzymatic saccharification of iron cocatalyst-pretreated biomass. Fourier transform Raman spectroscopy showed that major peaks representing the C-O-C and C-H bonds in cellulose are significantly attenuated by iron cocatalyst pretreatment. Imaging using Prussian blue staining indicated that Fe2+ ions associate with both cellulose/xylan and lignin in untreated as well as dilute acid/Fe2+ ion-pretreated corn stover samples. Analyses by scanning electron microscopy and transmission electron microscopy revealed structural details of biomass after dilute acid/Fe2+ ion pretreatment, in which delamination and fibrillation of the cell wall were observed. Conclusions By using this multimodal approach, we have revealed that (1) acid-ferrous ion-assisted pretreatment increases solubilization and enzymatic digestion of both cellulose and xylan to monomers and (2) this pretreatment likely targets multiple chemistries in plant cell wall polymer networks, including those represented by the C-O-C and C-H bonds in cellulose.

2011-01-01

257

Oxygen isotope fractionation of dissolved oxygen during reduction by ferrous iron  

NASA Astrophysics Data System (ADS)

The oxygen isotope fractionation factor of dissolved oxygen gas has been measured during inorganic reduction by aqueous FeSO 4 at 10-54 癈 under neutral (pH 7) and acidic (pH 2) conditions, with Fe(II) concentrations ranging up to 0.67 mol L -1, in order to better understand the geochemical behavior of oxygen in ferrous iron-rich groundwater and acidic mine pit lakes. The rate of oxygen reduction increased with increasing temperature and increasing Fe(II) concentration, with the pseudo-first-order rate constant k ranging from 2.3 to 82.9 10 -6 s -1 under neutral conditions and 2.1 to 37.4 10 -7 s -1 under acidic conditions. The activation energy of oxygen reduction was 30.9 6.6 kJ mol -1 and 49.7 13.0 kJ mol -1 under neutral and acidic conditions, respectively. Oxygen isotope enrichment factors ( ?) become smaller with increasing temperature, increasing ferrous iron concentration, and increasing reaction rate under acidic conditions, with ? values ranging from -4.5 to -11.6. Under neutral conditions, ? does not show any systematic trends vs. temperature or ferrous iron concentration, with ? values ranging from -7.3 to -10.3. Characterization of the oxygen isotope fractionation factor associated with O 2 reduction by Fe(II) will have application to elucidating the process or processes responsible for oxygen consumption in environments such as groundwater and acidic mine pit lakes, where a number of possible processes (e.g. biological respiration, reduction by reduced species) may have taken place.

Oba, Yasuhiro; Poulson, Simon R.

2009-01-01

258

Hydrocracking with molten zinc chloride catalyst containing 2-12% ferrous chloride  

DOEpatents

In a process for hydrocracking heavy aromatic polynuclear carbonaceous feedstocks to produce hydrocarbon fuels boiling below about 475.degree. C. by contacting the feedstocks with hydrogen in the presence of a molten zinc chloride catalyst and thereafter separating at least a major portion of the hydrocarbon fuels from the spent molten zinc chloride catalyst, an improvement comprising: adjusting the FeCl.sub.2 content of the molten zinc chloride to from about 2 to about 12 mol percent based on the mixture of ferrous chloride and molten zinc chloride.

Zielke, Clyde W. (McMurray, PA); Bagshaw, Gary H. (Library, PA)

1981-01-01

259

DECHLORINATION OF CHLORINATED METHANES BY FERROUS ION ASSOCIATED WITH VARIOUS IRON OXIDE MINERALS  

Microsoft Academic Search

The dechlorination of carbon tetrachloride (CT) by Fe(II) ion in the suspensions of crystalline iron oxide minerals including goethite (?-FeOOH), hematite (?-Fe2O3), magnetite (Fe3O4), and amorphous ferrihydrite (Fe(OH)3) was investigated. Experiments were performed using 10 mM iron oxides and 3 mM Fe(II) to form surface-bound iron suspensions at pH 7.2 under anoxic conditions. Ferrous ion can rapidly sorb onto the

Ruey-An Doong

260

Density functional theory study of an all ferrous 4Fe-4S cluster.  

PubMed

The all-ferrous, carbene-capped Fe(4)S(4) cluster, synthesized by Deng and Holm (DH complex), has been studied with density functional theory (DFT). The geometry of the complex was optimized for several electronic configurations. The lowest energy was obtained for the broken-symmetry (BS) configuration derived from the ferromagnetic state by reversing the spin projection of one of the high spin (S(i) = 2) irons. The optimized geometry of the latter configuration contains one unique and three equivalent iron sites, which are both structurally and electronically clearly distinguishable. For example, a distinctive feature of the unique iron site is the diagonal Fe贩稴 distance, which is 0.3 longer than for the equivalent irons. The calculated (57)Fe hyperfine parameters show the same 1:3 pattern as observed in the M鰏sbauer spectra and are in good agreement with experiment. BS analysis of the exchange interactions in the optimized geometry for the 1:3, M(S) = 4, BS configuration confirms the prediction of an earlier study that the unique site is coupled to the three equivalent ones by strong antiferromagnetic exchange (J > 0 in J ?(j<4)?(4)?(j)) and that the latter are mutually coupled by ferromagnetic exchange (J' < 0 in J' ?(iferrous cluster of the Fe-protein of nitrogenase, results from a remarkably strong dependence of the exchange interactions on cluster core geometry. The structure dependence of the exchange-coupling constants in the Fe(II)-(?(3)-S)(2)-Fe(II) moieties of the all-ferrous clusters is compared with the magneto-structural correlations observed in the data for dinuclear copper complexes. Finally, we discuss two all-ferric clusters in the light of the results for the all-ferrous cluster. PMID:21476577

Chakrabarti, Mrinmoy; M黱ck, Eckard; Bominaar, Emile L

2011-04-08

261

Clean Ferrous Casting Technology Research. Annual report, September 29, 1993--September 28, 1994  

SciTech Connect

This annual report covers work performed in the first year of research on Clean Ferrous Casting Technology Research. During this year the causes of penetration of cast iron in sand molds were defined and a program which predicts the occurrence of penetration was written and verified in commercial foundries. Calculations were made to size a reaction chamber to remove inclusions from liquid steel using electromagnetic force and the chamber was built. Finally, significant progress was made in establishing pouring practices which avoid re-oxidation of steel during pouring application of revised pouring practices have led to reduced inclusion levels in commercially poured steel castings.

Stefanescu, D.M.; Lane, A.M.; Giese, S.R.; Pattabhi, R.; El-Kaddah, N.H.; Griffin, J.; Bates, C.E.; Piwonka, T.S.

1994-10-01

262

Ascorbic acid-ferrous iron (Fe ++ )complexes and after cooking darkening of potatoes  

Microsoft Academic Search

A complex of ascorbic acid plus ferrous iron (Fe+ +) forms a purple pigment similar to the after cooking darkening pigment (ACD) in potatoes. The ascorbic acid-Fe+ + complex is similar to the ACD pigment in the following ways:\\u000a \\u000a \\u000a 1.燶\u000a \\u000a Both require O2 in an oxidation reaction to form the final pigment.\\u000a \\u000a \\u000a \\u000a \\u000a 2.燶\u000a \\u000a The color changes with pH are similar.

Paul Muneta; Fred Kaisaki

1985-01-01

263

Competitive Inhibition of Ferrous Iron Oxidation by Thiobacillus ferrooxidans by Increasing Concentrations of Cells  

PubMed Central

The oxidation of ferrous iron (Fe2+) to ferric iron (Fe3+) with dioxygen (O2) by various strains of Thiobacillus ferrooxidans was studied by measuring the rate of O2 consumption at various Fe2+ concentrations and cell concentrations. The apparent Km values for Fe2+ remained constant at different cell concentrations of laboratory strains ATCC 13661 and ATCC 19859 but increased with increasing cell concentrations of mine isolates SM-4 and SM-5. The latter results are explained by the competitive inhibition of the Fe2+-binding site of a cell by other cells in the reaction mixture. Possible mechanisms involving cell surface properties are discussed.

Suzuki, Isamu; Lizama, Hector M.; Tackaberry, Patrick D.

1989-01-01

264

Clean ferrous casting technology research. Final technical report, September 29, 1993--December 31, 1995  

SciTech Connect

This is the final report covering work performed on research into methods of attaining clean ferrous castings. In this program methods were developed to minimize the formation of inclusions in steel castings by using a variety of techniques which decreased the tendency for inclusions to form during melting, casting and solidification. In a second project, a reaction chamber was built to remove inclusions from molten steel using electromagnetic force. Finally, a thorough investigation of the causes of sand penetration defects in iron castings was completed, and a program developed which predicts the probability of penetration formation and indicates methods for avoiding it.

Bates, C.E.; Griffin, J.; Giese, S.R.; Lane, A.M. [and others

1996-01-31

265

Removal of copper from iron-based metal with an aluminum sulfide/ferrous sulfide matte  

NASA Astrophysics Data System (ADS)

An economically viable method for the removal of copper from iron, if available, could be used by steelmakers to turn high-copper-content scrap (above 0.1 wt.%) into useful products. Molten salt mixtures of charge-asymmetric cation species show a significant drop in the activity coefficient for monovalent cation species in the presence of trivalent or higher cation species. This phenomenon can be used to design a flux for the removal of copper as a cuprous species (monovalent) from iron-based metal. Distribution coefficients of copper (i.e., the ratio of the weight percent copper in a matte to that in the metal) were determined between a sulfide flux (containing aluminum sulfide, ferrous sulfide, and dilute concentrations of either magnesium sulfide or calcium sulfide) and carbon-saturated iron at 1,638 K. A maximum distribution coefficient of 30 5 was found, and the copper level in the iron was reduced to as low as 0.07 wt.%. Magnesium sulfide and calcium sulfide both adversely affected the copper removal. The activity coefficient of cuprous sulfide dropped from 2.9 with a pure FeS matte to 0.4 with a binary matte containing XsbFeS = 0.18. The decrease with increasing concentrations of aluminum sulfide was due to the presence of the polyvalent aluminum cation in the flux. A liquid-liquid miscibility gap above XsbFeS = 0.43 was confirmed in the aluminum sulfide/ferrous sulfide pseudobinary system. Because a sulfide matte would result in a large sulfur content in the treated metal, distribution coefficients were also determined between an oxide flux (consisting of alumina, silica, calcia, and ferrous oxide) and iron with various concentration of carbon at 1,923 K. A maximum distribution coefficient of 0.5 was found. Finally, distribution coefficients were determined between a sulfide-modified oxide flux (consisting of alumina, silica, ferrous sulfide, and dilute amounts of calcia, magnesia, calcium sulfide, or magnesium sulfide) and iron with various concentrations of carbon at 1,823 K. A maximum distribution coefficient of 6.8 was found for iron with 0.1 wt.% carbon; distribution coefficients increased as carbon content decreased. Although the results are considered preliminary, further research with the mixed flux is strongly recommended because significantly higher distribution coefficients should be possible.

Cohen, Adam Barrett

266

Novel chelate-induced magnetic alignment of biological membranes.  

PubMed Central

A phospholipid chelate complexed with ytterbium (DMPE-DTPA:Yb3+) is shown to be readily incorporated into a model membrane system, which may then be aligned in a magnetic field such that the average bilayer normal lies along the field. This so-called positively ordered smectic phase, whose lipids consist of less than 1% DMPE-DTPA:Yb3+, is ideally suited to structural studies of membrane proteins by solid-state NMR, low-angle diffraction, and spectroscopic techniques that require oriented samples. The chelate, 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine diethylenetriaminepentaacetic acid, which strongly binds the lanthanide ions and serves to orient the membrane in a magnetic field, prevents direct lanthanide-protein interactions and significantly reduces paramagnetic shifts and line broadening. Similar low-spin lanthanide chelates may have applications in field-ordered solution NMR studies of water-soluble proteins and in the design of new magnetically aligned liquid crystalline phases.

Prosser, R S; Volkov, V B; Shiyanovskaya, I V

1998-01-01

267

Polyvalent metal ion chelating agents for xanthan solutions  

SciTech Connect

A stable xanthan solution with superior filterability and subterranean injectivity characteristics comprises biopolymer and a chelating agent selected from aliphatic alpha-hydroxy acids having from about 2-7 carbon atoms; aliphatic and aromatic beta-keto compounds having from about 4-9 carbon atoms; or 2- and 4-pyrones having a hydroxyl group alpha to the carbonyl and having 5 or 6 carbon atoms; said chelating agent being present in an amount of at least about 1.0 ppm of the total solution. A method of enhancing oil recovery comprising employing as a mobility control solution in oil-bearing formations a mixture of xanthan biopolymer and a chelating agent is also disclosed.

Miller, J.W.; Tate, B.E.

1984-08-21

268

Ferrous Analysis.  

ERIC Educational Resources Information Center

|Elements covered in this review include: aluminum, antimony, arsenic, bismuth, boron, calcium, carbon, chromium, cobalt, copper, hydrogen, iron, lead, magnesium, manganese, molybdenum, nickel, niobium, nitrogen, oxygen, phosphorus, platinum, rare earths, silicons, sulfur, tin, titanium, tungsten, vanadium, zinc, and zirconium. Analytical methods

Straub, William A.

1989-01-01

269

Lauriston S. Taylor Lecture: the quest for therapeutic actinide chelators.  

PubMed

All of the actinides are radioactive. Taken into the body, they damage and induce cancer in bone and liver, and in the lungs if inhaled, and U(VI) is a chemical kidney poison. Containment of radionuclides is fundamental to radiation protection, but if it is breached accidentally or deliberately, decontamination of exposed persons is needed to reduce the consequences of radionuclide intake. The only known way to reduce the health risks of internally deposited actinides is to accelerate their excretion with chelating agents. Ethylendiaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) were introduced in the 1950's. DTPA is now clinically accepted, but its oral activity is low, it must be injected as a Ca(II) or Zn(II) chelate to avoid toxicity, and it is structurally unsuitable for chelating U(VI) or Np(V). Actinide penetration into the mammalian iron transport and storage systems suggested that actinide ions would form stable complexes with the Fe(III)-binding units found in potent selective natural iron chelators (siderophores). Testing of that biomimetic approach began in the late 1970's with the design, production, and assessment for in vivo Pu(IV) chelation of synthetic multidentate ligands based on the backbone structures and Fe(III)-binding groups of siderophores. New efficacious actinide chelators have emerged from that program, in particular, octadentate 3,4,3-LI(1,2-HOPO) and tetradentate 5-LIO(Me-3,2-HOPO) have potential for clinical acceptance. Both are much more effective than CaNa3-DTPA for decorporation of Pu(IV), Am(III), U(VI), and Np(IV,V), they are orally active, and toxicity is acceptably low at effective dosage. PMID:18849679

Durbin, Patricia W

2008-11-01

270

Antibacterial activities of iron chelators against common nosocomial pathogens.  

PubMed

The activities of iron chelators (deferoxamine, deferiprone, Apo6619, and VK28) were evaluated against type strains of Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli. Deferiprone, Apo6619, and VK28 each inhibited growth in standard and RPMI tissue culture medium, while deferoxamine had no effect. Additionally, time-kill assays revealed that VK28 had a bacteriostatic effect against S. aureus. Therefore, these newly developed iron chelators might provide a nontraditional approach for treatment of bacterial infections. PMID:22850524

Thompson, Mitchell G; Corey, Brendan W; Si, Yuanzheng; Craft, David W; Zurawski, Daniel V

2012-07-30

271

Ettringite-induced heave in chromite ore processing residue (COPR) upon ferrous sulfate treatment.  

PubMed

A pilot-scale treatment study was implemented at a deposition site of chromite ore processing residue (COPR) in New Jersey. Ferrous sulfate heptahydrate (FeSO4 x 7H2O) was employed to reduce hexavalent chromium in two dosages with three types of soil mixing equipment. XANES analyses of treated samples cured for 240 days indicated that all treatment combinations failed to meet the Cr(VI) regulatory limit of 240 mg/kg. More importantly, the discrepancy between XANES and alkaline digestion results renders the latter unreliable for regulatory purposes when applied to ferrous-treated COPR. Regardless of Cr-(VI), the introduction of reductant containing sulfate, mechanical mixing, water, acidity, and the resulting temperature increase in treated COPR promoted dissolution of brownmillerite (Ca2FeAlO5), releasing alumina and alkalinity. The pH increase caused initially precipitated gypsum (CaSO4 x 2H2O) to progressively convert to ettringite (Ca6Al2(SO4)3 x 32H2O) and its associated volume expansion under both in situ and ex situ conditions, with a maximum of 0.8 m vertical swell within 40 days of curing. While Cr-(VI) treatment remains a challenge, the intentional exhaustion of the heave potential of COPR by transforming all Al sources to ettringite emerges as a possible solution to delayed ettringite formation, which would hamper site redevelopment. PMID:17007141

Dermatas, Dimitris; Chrysochoou, Maria; Moon, Deok Hyun; Grubb, Dennis G; Wazne, Mahmoud; Christodoulatos, Christos

2006-09-15

272

A ferrous oxalate mediated photo-Fenton system: toward an increased biodegradability of indigo dyed wastewaters.  

PubMed

This study assessed the applicability of a ferrous oxalate mediated photo-Fenton pretreatment for indigo-dyed wastewaters as to produce a biodegradable enough effluent, likely of being derived to conventional biological processes. The photochemical treatment was performed with ferrous oxalate and hydrogen peroxide in a Compound Parabolic Concentrator (CPC) under batch operation conditions. The reaction was studied at natural pH conditions (5-6) with indigo concentrations in the range of 6.67-33.33 mg L(-1), using a fixed oxalate-to-iron mass ratio (C(2)O(4)(2-)/Fe(2+)=35) and assessing the system's biodegradability at low (257 mg L(-1)) and high (1280 mg L(-1)) H(2)O(2) concentrations. In order to seek the optimal conditions for the treatment of indigo dyed wastewaters, an experimental design consisting in a statistical surface response approach was carried out. This analysis revealed that the best removal efficiencies for Total Organic Carbon (TOC) were obtained for low peroxide doses. In general it was observed that after 20 kJ L(-1), almost every treated effluent increased its biodegradability from a BOD(5)/COD value of 0.4. This increase in the biodegradability was confirmed by the presence of short chain carboxylic acids as intermediate products and by the mineralization of organic nitrogen into nitrate. Finally, an overall decrease in the LC(50) for Artemia salina indicated a successful detoxification of the effluent. PMID:23142056

Vedrenne, Michel; Vasquez-Medrano, Ruben; Prato-Garcia, Dorian; Frontana-Uribe, Bernardo A; Hernandez-Esparza, Margarita; de Andr閟, Juan Manuel

2012-10-22

273

The photochemical origins of life and photoreaction of ferrous ion in the archaean oceans  

NASA Astrophysics Data System (ADS)

A general argument is made for the photochemical origins of life. A constant flux of free energy is required to maintain the organized state of matter called life. Solar photons are the unique source of the large amounts of energy probably require to initiate this organization and certainly required for the evolution of life to occur. The completion of this argument will require the experimental determination of suitable photochemical reactions. Our work shows that biogenetic porphyrins readily photooxidize substrates and emit hydrogen in the presence of a catalyst. These results are consistent with the Granick hypothesis, which relates a biosynthetic pathway to its evolutionary origin. We have shown that photoexcitation of ferrous ion at neutral pH with near ultraviolet light produces hydrogen with high quantum yield. This same simple system may reduce carbon dioxide to formaldehyde and further products. These reactions offer a solution to the dilemma confronting the Oparin-Urey-Miller model of the chemical origin of life. If carbon dioxide is the main form of carbon on the primitive earth, the ferrous photoreaction may provide the reduced carbon necessary for the formation of amino acids and other biogenic molecules. These results suggest that this progenitor of modern photosynthesis may have contributed to the chemical origins of life.

Mauzerall, David C.

1990-05-01

274

Enzymes hydrolyzing structural components and ferrous ion cause rusty-root symptom on ginseng (Panax ginseng).  

PubMed

Microbial induction of rusty-root was proved in this study. The enzymes hydrolyzing plant structural materials, including pectinase, pectolyase, ligninase, and cellulase, caused the rusty-root in ginseng. Pectinase and pectolyase produced the highest rusty-color formation. Ferrous ion (Fe+++) caused the synergistic effect on rusty-root formation in ginseng when it was used with pectinase. The effect of ferric ion (Fe++) on rusty-root formation was slow, compared with Fe+++, probably due to gradual oxidation to Fe+++. Other metal ions including the ferric ion (Fe++) did not affect rusty-root formation. The endophytic bacteria Agrobacterium tumefaciens, Lysobacter gummosus, Pseudomonas veronii, Pseudomonas marginalis, Rhodococcus erythropolis, and Rhodococcus globerulus, and the rotten-root forming phytophathogenic fungus Cylindrocarpon destructans, caused rusty-root. The polyphenol formation (rusty color) was not significantly different between microorganisms. The rotten-root-forming C. destructans produced large quantities of external cellulase activity (about 2.3 U[micronM/min/mg protein]), which indicated the pathogenecity of the fungus, whereas the bacteria produced 0.1-0.7 U. The fungal external pectinase activities (0.05 U) and rusty-root formation activity were similar to those of the bacteria. In this report, we proved that microbial hydrolyzing enzymes caused rusty-root (Hue value 15 degrees) of ginseng, and ferrous ion worsened the symptom. PMID:21364303

Lee, Chanyong; Kim, Kwang Yup; Lee, Jo-Eun; Kim, Sunghan; Ryu, Dongkul; Choi, Jae-Eul; An, Gilhwan

2011-02-01

275

Selective Inhibition of the Oxidation of Ferrous Iron or Sulfur in Thiobacillus ferrooxidans  

PubMed Central

The oxidation of either ferrous iron or sulfur by Thiobacillus ferrooxidans was selectively inhibited or controlled by various anions, inhibitors, and osmotic pressure. Iron oxidation was more sensitive than sulfur oxidation to inhibition by chloride, phosphate, and nitrate at low concentrations (below 0.1 M) and also to inhibition by azide and cyanide. Sulfur oxidation was more sensitive than iron oxidation to the inhibitory effect of high osmotic pressure. These differences were evident not only between iron oxidation by iron-grown cells and sulfur oxidation by sulfur-grown cells but also between the iron and sulfur oxidation activities of the same iron-grown cells. Growth experiments with ferrous iron or sulfur as an oxidizable substrate confirmed the higher sensitivity of iron oxidation to inhibition by phosphate, chloride, azide, and cyanide. Sulfur oxidation was actually stimulated by 50 mM phosphate or chloride. Leaching of Fe and Zn from pyrite (FeS2) and sphalerite (ZnS) by T. ferrooxidans was differentially affected by phosphate and chloride, which inhibited the solubilization of Fe without significantly affecting the solubilization of Zn.

Harahuc, Lesia; Lizama, Hector M.; Suzuki, Isamu

2000-01-01

276

Studies with Ferrous Sulfamate and Alternate Reductants for 2nd Uranium Cycle  

SciTech Connect

A wide range of miniature mixer-settler tests were conducted to determine the source of iron and sulfur contamination in the uranium product stream (''1EU'') of H Canyon's 2nd Uranium Cycle. The problem was reproduced on the laboratory scale mixer-settlers by changing the feed location of ferrous sulfamate from stage D4 to stage D1. Other process variables effected no change. It was later determined that ferrous sulfamate (FS) solids had plugged the FS line to stage D4, causing FS to backup a ventline and enter the Canyon process at stage D1. Pluggage was almost certainly due to precipitation of FS solids during extended process downtime. During the search for the root cause, tests showed that FS solids were quite small (1-10 mm), and a portion of them could bypass the current Canyon prefilter (3-mm). Also, additional tests were done to find an alternate means of reducing and thereby removing plutonium and neptunium from the uranium product. These tests showed that FS was a more effective reductant than either ascorbic acid or a hydroxylamine nitrate (HAN) / dilute FS combination.

Crowder, M.L.

2003-01-15

277

Efficient near ultraviolet light induced formation of hydrogen by ferrous hydroxide  

NASA Astrophysics Data System (ADS)

A possible origin of early hydrogen by UV-induced photoreduction of ferrous ions was investigated by measuring the rate of H2 formation from irradiated FeSO4 solutions as a function of pH and the range of UV sources. It was found that, in addition to the known reaction in acid solution which decreases in yield with increasing pH and requires far-UV light, there is an efficient reaction occurring between pH 6 and 9 which utilizes near-UV light (of a 200-W mercury arc lamp). This latter reaction is a linear function of both the concentration of Fe(2+) and the light intensity. These results support the suggestion of Braterman et al. (1983) that the near-UV-driven photooxidation of ferrous ions may be responsible for the origin of the banded iron formations on the early earth. The efficient photoreaction could also explain the source of reducing equivalents for CO2 reduction.

Borowska, Zofia K.; Mauzerall, David C.

1987-09-01

278

Kinetics of Triscarbonato Uranyl Reduction by Aqueous Ferrous Iron: A Theoretical Study  

SciTech Connect

Uranium is a pollutant whose mobility is tied to its oxidation state. While U(VI) in the form of the uranyl cation is capable of being reduced by a range of natural reductants, complexation by carbonate greatly reduces its reduction potential as well as imposing increased electron transfer (ET) distances. Very little is known about the elementary processes involved in uranium reduction from U(VI) to U(V) to U(IV) in general. In this study, we examine the theoretical kinetics of ET from ferrous iron to triscarbonato uranyl in aqueous solution. A combination of molecular dynamics (MD) simulations and density functional theory (DFT) electronic structure calculations are employed to compute the ET parameters that enter into Marcus model, including the thermodynamic driving force, reorganization energies, and electronic coupling matrix elements. MD simulations predict that two ferrous iron atoms will bind in an inner-sphere fashion to the three-membered carbonate ring of tricarbonato uranium, forming the charge-neutral Fe2UO2(CO3)3(H2O)8 complex. Through a sequential proton-coupled electron transfer mechanism, the first ET step converting U(VI) to U(V) is predicted by DFT to occur at a rate on the order of 1 s^-1. The second ET step converting U(V) to U(IV) is predicted to be significantly endergonic. Therefore, U(V) is a stabilized end-product in this ET system.

Wander, Matthew C.; Kerisit, Sebastien N.; Rosso, Kevin M.; Schoonen, Martin A.

2006-08-01

279

The effect of titanium and phosphorus on ferric/ferrous ratio in silicate melts: an experimental study  

NASA Astrophysics Data System (ADS)

The effect of TiO2 and P2O5 on the ferric/ferrous ratio in silicate melts was investigated in model silicate melts at air conditions in the temperature range 1,400-1,550 癈 at 1-atm total pressure. The base composition of the anorthite-diopside eutectic composition was modified with 10 wt % Fe2O3 and variable amounts of TiO2 (up to 30 wt %) or P2O5 (up to 20 wt %). Some compositions also contained higher SiO2 concentrations to compare the role of SiO2, TiO2, and P2O5 on the Fe3+/Fe2+ ratio. The ferric/ferrous ratio in experimental glasses was analyzed using a wet chemical technique with colorimetric detection of ferrous iron. It is shown that at constant temperature, an increase in SiO2, TiO2, and P2O5 content results in a decrease in the ferric/ferrous ratio. The effects of TiO2 and SiO2 on the Fe3+/Fe2+ ratio was found to be almost identical. In contrast, adding P2O5 was found to decrease ferric/ferrous ratio much more effectively than adding silica. The results were compared with the predictions from the published empirical equations forecasting Fe3+/Fe2+ ratio. It was demonstrated that the effects of TiO2 are minor but that the effects of P2O5 should be included in models to better describe ferric/ferrous ratio in phosphorus-bearing silicate melts. Based on our observations, the determination of the prevailing fO2 in magmas from the Fe3+/Fe2+ ratio in natural glasses using empirical equations published so far is discussed critically.

Borisov, Alexander; Behrens, Harald; Holtz, Francois

2013-10-01

280

Adverse effects of iron supplementation: a comparative trial of a wax-matrix iron preparation and conventional ferrous sulfate tablets.  

PubMed

The acceptability of supplemental iron delivered from a wax-matrix tablet of ferrous sulfate was compared with that of a conventional ferrous sulfate tablet in a single-blind, parallel-group study. Both tablets were formulated to deliver 50 mg of elemental iron. The incidence of adverse effects was found to be significantly greater among 272 subjects taking the conventional tablets than among 271 subjects taking the wax-matrix preparation. Eighty-one percent of the subjects taking the wax-matrix preparation experienced no severe or moderate side effects as compared with only 50% of those taking the conventional tablets. PMID:4053146

Brock, C; Curry, H; Hanna, C; Knipfer, M; Taylor, L

1985-01-01

281

An experimental study for enhancing the catalytic effects of various copper forms on the oxidation of ferrous iron.  

PubMed

In this research the catalytic effect of copper compounds (ionic, oxide and oxide nanopowder) on the oxidation of ferrous iron by aeration was studied experimentally. When copper exists in solution, the oxidation rate of iron(II) will increase. The experimental results showed that the oxidation rate increases with an increasing copper concentration. From the experimental data it can be determined that the copper oxide nanopowder is the most effective for the oxidation reaction among the used copper forms. Aeration is the most economical oxidation method when water exhibits a high ferrous iron concentration. PMID:23530309

Babak, Manizhe Moradi Shahre; Goharrizi, Ataallah Soltani; Mirzaei, Mohammad; Roayaei, Emad

282

TREATMENT OF HEXAVALENT CHROMIUM IN CHROMITE ORE PROCESSING SOLID WASTE USING A MIXED REDUCTANT SOLUTION OF FERROUS SULFATE AND SODIUM DITHIONITE  

EPA Science Inventory

We developed a method for disseminating ferrous iron in the subsurface to enhance chemical reduction of hexavalent chromium (Cr(VI)) in a chromite ore processing solid waste derived from the production of ferrochrome alloy. The method utilizes ferrous sulfate (FeSO4) in combinati...

283

Experimental investigation of the effect of oxygen fugacity on ferric-ferrous ratios and unit-cell parameters of four natural clinoamphiboles  

Microsoft Academic Search

but the results suggest that other mechanisms may also be involved. All four amphiboles exhibited systematically higher ferric-ferrous ratios with increasing 6, of equilibration. Equilibrium R values were achieved relatively rapidly and could be readily restored to onginal values by treatment at the appropriate buffer. In some cases, a metastable equi- librium of ferric-ferrous ratio was achieved before the amphibole

A. Cr-own; Ronnnr K. Popp

284

Chelating Extractants of Improved Selectivity. Progress Report, September 1, 1976--October 31, 1977.  

National Technical Information Service (NTIS)

New means of characterizing metal chelating reagent selectivity have been developed and incorporated into a theoretical factor analysis of the chelate stability constants of 24 metal ions with 14 ligands of the EDTA family. The factor analysis will be ext...

H. Freiser

1977-01-01

285

Studies of Ion Exchange and Chelation Compounds Adsorbed on Granular Graphite.  

National Technical Information Service (NTIS)

Several compounds that have particular ion exchange or chelation properties have been adsorbed on granular graphite and coke. The resulting materials exhibit ion exchange and chelation properties similar to typical commercial exchange resins used for sepa...

J. L. Hern

1976-01-01

286

Detection of decontamination solution chelating agents using ion selective coated-wire electrodes.  

National Technical Information Service (NTIS)

This thesis explores feasibility of using coated-wire electrodes to measure chelating agent concentration. Chelating agents are often found in radioactive decontamination solutions because they aid in the removal of radionuclides from contaminated surface...

M. L. Banks

1992-01-01

287

Regeneration of the Heart in Diabetes by Selective Copper Chelation  

Microsoft Academic Search

Heart disease is the major cause of death in diabetes, a disorder characterized by chronic hyperglycemia and cardiovascular complications. Although altered system- ic regulation of transition metals in diabetes has been the subject of previous investigation, it is not known whether changed transition metal metabolism results in heart disease in common forms of diabetes and whether metal chelation can reverse

Garth J. S. Cooper; Anthony R. J. Phillips; Soon Y. Choong; Bridget L. Leonard; David J. Crossman; Dianne H. Brunton; Etuate L. Saafi; Ajith M. Dissanayake; Brett R. Cowan; Alistair A. Young; Christopher J. Occleshaw; Yih-Kai Chan; Fiona E. Leahy; Geraldine F. Keogh; Gregory D. Gamble; Grant R. Allen; Adele J. Pope; Peter D. W. Boyd; Sally D. Poppitt; Thomas K. Borg; Robert N. Doughty; John R. Baker

288

Effect of iron chelators on dopamine D2 receptors.  

PubMed

Nutritional iron deficiency induced in rats causes a selective reduction of [3H]spiperone binding in caudate nucleus. This effect can be reversed by iron supplementation in vivo. The possibility that iron may be involved in the dopamine D2 receptor was investigated by examining the effect of various iron and noniron chelators on the binding of [3H]spiperone in rat caudate nucleus. Iron chelators 1,10-phenanthroline, 2,4,6-tripyridyl-s-triazine, alpha, alpha'-dipyridyl, and desferrioxamine mesylate inhibited the binding of [3H]spiperone. The inhibition by 1,10-phenanthroline was noncompetitive and reversible. In the presence of FeCl2 or FeCl3, the inhibitory effect of 1,10-phenanthroline was potentiated. Iron salts or chelators were without effect on the binding of [3H]dihydroalprenolol to beta-adrenoreceptors in caudate nucleus; thus the action of iron chelators on the dopamine D2 receptor tends to be selective. Incubation of caudate nucleus membrane prepared from iron-deficient rats with FeCl2 or FeCl3 did not reverse the diminished binding of [3H]spiperone. The present study indicates that if iron is involved in the physiological regulation of dopamine D2 agonist-antagonist binding sites, it is more complex than hitherto considered. PMID:2993525

Ben-Shachar, D; Finberg, J P; Youdim, M B

1985-10-01

289

Purification of metal plating rinse waters with chelating ion exchangers  

Microsoft Academic Search

A wide range of chelating ion exchangers was tested for their abilities to remove Zn, Ni, Cu and Cd from solutions simulating waste effluents from the metal-plating industry. The task was to reduce metal discharges to the environment so that metal-plating shops could keep up with the modern, more stringent regulations of waste effluents. The resins were tested by batch

Risto Koivula; Jukka Lehto; Leena Pajo; Thomas Gale; Heikki Leinonen

2000-01-01

290

Efficacy of reversal of aortic calcification by chelating agents.  

PubMed

Elastin-specific medial vascular calcification, termed "Monckeberg's sclerosis," has been recognized as a major risk factor for various cardiovascular events. We hypothesize that chelating agents, such as disodium ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and sodium thiosulfate (STS) might reverse elastin calcification by directly removing calcium from calcified tissues into soluble calcium complexes. We assessed the chelating ability of EDTA, DTPA, and STS on removal of calcium from hydroxyapatite (HA) powder, calcified porcine aortic elastin, and calcified human aorta in vitro. We show that both EDTA and DTPA could effectively remove calcium from HA and calcified tissues, while STS was not effective. The tissue architecture was not altered during chelation. In the animal model of aortic elastin-specific calcification, we further show that local periadventitial delivery of EDTA loaded in to poly(lactic-co-glycolic acid) nanoparticles regressed elastin-specific calcification in the aorta. Collectively, the data indicate that elastin-specific medial vascular calcification could be reversed by chelating agents. PMID:23963635

Lei, Yang; Grover, Arjun; Sinha, Aditi; Vyavahare, Naren

2013-11-01

291

Chelating water-soluble polymers for waste minimization  

Microsoft Academic Search

Within the DOE complex and in industry there is a tremendous need for advanced metal ion recovery and waste minimization techniques. This project sought to employ capabilities for ligand-design and separations chemistry in which one can develop and evaluate water- soluble chelating polymers for recovering actinides and toxic metals from various process streams. Focus of this work was (1) to

B. Smith; M. Cournoyer; B. Duran; D. Ford; R. Gibson; M. Lin; A. Meck; P. Robinson; T. Robison

1996-01-01

292

Labeling Biomolecules with Radiorhenium - a Review of the Bifunctional Chelators  

PubMed Central

For radiotherapy, biomolecules such as intact antibodies, antibody fragments, peptides, DNAs and other oligomers have all been labeled with radiorhenium (186Re and 188Re). Three different approaches have been employed that may be referred to as direct, indirect and integral labeling. Direct labeling applies to proteins and involves the initial reduction of endogenous disulfide bridges to provide chelation sites. Indirect labeling can apply to most biomolecules and involves the initial attachment of an exogenous chelator. Finally, integral labeling is a special case applying only to small molecules in which the metallic radionuclide serves to link two parts of a biomolecule together in forming the labeled complex. While the number of varieties for the direct and integral radiolabeling approaches is rather limited, a fairly large and diverse number of chelators have been reported in the case of indirect labeling. Our objective herein is to provide an overview of the various chelators that have been used in the indirect labeling of biomolecules with radiorhenium, including details on the labeling procedures, the stability of the radiolabel and, where possible, the influence of the label on biological properties.

Liu, Guozheng; Hnatowich, Donald J.

2007-01-01

293

Chelating amides of lithium. Synthesis, structure and coordination chemistry  

Microsoft Academic Search

A limited review of the use of mixed-donor ligands that contain amides is presented. By combining amides with phosphines and amines in a chelating array, a variety of tridentate and macrocyclic ligands have been prepared. The synthesis and structures of a variety of lithium derivatives are presented since these are the typical starting materials in the preparation of transition metal,

Michael D. Fryzuk; Garth R. Giesbrecht; Samuel A. Johnson; James E. Kickham; Jason B. Love

1998-01-01

294

The Octahedral-Square-Planar Transition of Nickel Chelates  

NASA Astrophysics Data System (ADS)

An experiment for an advanced inorganic chemistry laboratory is proposed that involves the study of the equilibrium between the (blue) octahedral and (yellow) square planar chelates of nickel(II) with tetraaza ligands in solution. The ligands employed are the linear triethylenetetramine and the cyclic cyclam. Changes in the ionic strength or the temperature of the solutions shift the equilibrium, which is followed spectrophotometrically.

Ben-Dor, Lina; Marcus, Yizhak

1998-11-01

295

Evaluation of intakes of transuranics influenced by chelation therapy  

SciTech Connect

Once an intake of transuranics occurs, there are only three therapeutic procedures available to the physician for reducing the intake and mitigating the dose: excision of material from wounds, removal of material from the lungs with lavage, and chelation therapy. The only chelation agents approved in the United States for the treatment of occupational intakes of transuranics are the zinc and calcium salts of diethylene-triamine-pentaacetic acid, better known as Zn-DTPA and Ca-DTPA. In the past 35 years, approximately 3000 doses of DTPA have been administrated to over 500 individuals who had intakes of transuranics. The drug is considered to be quiet safe and has few side effects. For the internal dosimetrist, perhaps the most important aspects of chelation therapy is that if enhances the excretion rate of a transuranic and perturbs the shape of the urinary excretion curve. These perturbations last for months and are so great that standard urinary excretion models cannot be used to evaluate the intake. We review here a method for evaluating intakes of transuranics influenced by chelation therapy that has been used with some degree of success at the Savannah River Site for over 20 years.

LaBone, T.R.

1994-02-01

296

Aluminium and iron in the brain梡rospects for chelation  

Microsoft Academic Search

Aluminium and iron both accumulate in the brain in the course of ageing. We first briefly review how aluminium may interfere with iron metabolism through its interaction with iron homeostatic mechanisms. Then we present comparative data on the chelation of brain aluminium and iron in appropriate animal models of loading with the two metals. With both desferrioxamine (DFO) B and

Robert R Crichton; Anne Florence; Roberta J Ward

2002-01-01

297

Desorption-complexation-dissolution characteristics of adsorbed cadmium from kaolin by chelators  

Microsoft Academic Search

In order to provide a sound experimental background for the remediation of metal-contaminated soil by chelators, the desorption\\/complexation\\/dissolution characteristics of Cd from kaolin as a representative soil component by four chelators (NTA, EDTA, EGTA and DCyTA) have been investigated as a function of solution pH. For all chelating agents under examination, the ratio of Cd (desorbed from kaolin) to chelator

Jihua Hong; Peter N. Pintauro

1996-01-01

298

Tests of stability on waste produced in pilot plant testing using ferrous{center_dot}EDTA and magnesium-enhanced lime for combined SO{sub 2}/NO{sub x} removal  

SciTech Connect

A pilot-plant-scale study of combined sulfur dioxide/nitrogen oxides (SO{sub 2}/NO{sub x}) removal has been performed by the Dravo Lime Company at the Cincinnati Gas and Electric Company`s Miami Fort Station in North Bend, Ohio. This study used Dravo`s patented Thiosorbic{reg_sign} lime process, utilizing a magnesium-enhanced lime, along with Argonne National Laboratory`s (ANL`s) patented ARGONOX metal-chelate additive, ferrous{center_dot}ethylenediaminetetraacetic acid (Fe{center_dot}EDTA). For approximately nine months, scrubbing tests were carried out, and waste samples were collected. Waste testing at ANL involved two types of long-term chemical stability experiments. In one experiment, the gas-phase composition above several different samples was studied by mass spectrometry over a period of about 22 months. Significant changes were noted for oxygen (O{sub 2}), carbon dioxide (CO{sub 2}), and hydrogen sulfide (H{sub 2}S) gases. The other experiment involved solid-phase leaching using the Toxicity Characteristic Leaching Procedure (TCLP). Samples were stored for up to 14 months before leaching. Then each leachate was tested for total Kjeldahl nitrogen and for some nitrogen-containing species. Total leachable nitrogen was found to stabilize after about the first seven months of storage.

Mendelsohn, M.H.; Livengood, C.D.

1994-03-01

299

Lipophilic aroylhydrazone chelator HNTMB and its multiple effects on ovarian cancer cells  

Microsoft Academic Search

BACKGROUND: Metal chelators have gained much attention as potential anti-cancer agents. However, the effects of chelators are often linked solely to their capacity to bind iron while the potential complexation of other trace metals has not been fully investigated. In present study, we evaluated the effects of various lipophilic aroylhydrazone chelators (AHC), including novel compound HNTMB, on various ovarian cancer

Kyu Kwang Kim; Thilo S Lange; Rakesh K Singh; Laurent Brard

2010-01-01

300

A randomised double-blind study comparing sodium feredetate with ferrous fumarate in anaemia in pregnancy.  

PubMed

Iron deficiency anaemia is a major health problem in India especially in women of reproductive age group. The World Health Organisation recommends that the haemoglobin concentration should not fall below 11.0 g/dl at any time during pregnancy. The aim of study was to compare the efficacy and safety of two doses of sodium feredetate with ferrous fumarate in improving haemoglobin profile in pregnant anaemic women. Pregnant women with gestation period between 12 and 26 weeks having serum haemoglobin < 10 g/dl, serum ferritin levels less than 12 microg/l were included in the study. Patients were divided into 3 groups and drugs administered accordingly. A total of 48 patients were available for analysis which included 37 patients who had completed all the visits up to 75 days follow-up and 11 patients who were treatment failures. In group A combination of sodium feredetate (containing 33 mg of elemental iron) along with vitamin B12 (15 microg) and folic acid (1.5 mg) was administered twice a day. In group B combination of sodium feredetate (containing 66 mg of elemental iron) along with vitamin B12 (15 microg) and folic acid (1.5 mg) was administered twice a day. In group C combination of ferrous fumarate (containing 100 mg of elemental iron) along with vitamin B12 (15 microg) and folic acid (1.5 mg) was administered twice a day. Patients were evaluated for Hb, RBC count, MCV, MCH and MCHC at day 0, 30, 45, 60 and 75. Serum ferritin, serum iron, TIBC and transferrin saturation were assessed at recruitment and end study. Mean rise of haemoglobin at the completion of study, over that of basal values was 1.79 g/dl (0.71 to 2.87, 95% CI, p < 0.05) in group A, 1.84 g/dl (0.82 to 2.86, 95% CI, p < 0.05) in group B and 1.63 g/dl (0.38 to 2.88, 95% CI, p < 0.05) in group C. Safety assessment was done by doing liver and kidney function test at the time of recruitment and end study. Low doses of sodium feredetate (33 mg and 66 mg of elemental iron given twice daily) produce comparable results as higher dose of ferrous fumarate (100 mg elemental iron given twice daily). As there were no adverse effects reported with sodium feredetate, it can be concluded from this study that this new formulation appears to be effective in improving haemoglobin profile in pregnant anaemic women and is tolerated well. PMID:17915799

Sarkate, Pankaj; Patil, Amrapali; Parulekar, Shashank; Rege, N N; Samant, B D; Lokhande, Jaisen; Gupta, Ashwaria; Kulkarni, Kamlakar

2007-05-01

301

Ferrous iron phosphorus in sediments: development of a quantification method through 2,2'-bipyridine extraction.  

PubMed

The role of ferrous iron in the phosphorus cycle of an aquatic ecosystem is poorly understood because of a lack of suitable methods to quantitatively evaluate ferrous iron phosphorus (FIP) phases. Using sediments sampled from Fubao Bay of Dianchi Lake in China, a novel extraction method for FIP using 2,2'-bipyridine was explored. Total phosphorus and iron in the sediments ranged from 1.0 to 5.0 mg/g (dry weight) and 28.5 to 90.6 mg/g, respectively. Organic content (as indicated by loss on ignition or LOI) and iron(II) ranged from 3.1 to 27.0% and 26.5 to 64.9 mg/g, respectively. The dissolution dynamics of FIP extraction with a low solid/liquid ratio (1:25) indicated that a single application of 0.2% 2,2'-bipyridine extracted both iron(II) (Fe(II)) and phosphorus (as PO4(3-)) in sediments with different organic contents with low efficiency. The extraction efficiency of Fe(II) was improved by alteration of the solid/liquid ratio, but the effect was limited. However, addition of a 1:1000 solid/liquid ratio of 0.5 M potassium chloride to a 0.2% 2,2'-bipyridine solution significantly accelerated extraction of FIP with the release of Fe(II) and phosphorus toward equilibrium at approximately 150 hours. Further investigation demonstrated that 2,2'-bipyridine exhibited a higher selectivity in distinguishing FIP from phosphorus bound to ferric (Fe(III)) oxides or precipitated by calcium (Ca2+). Air-drying sediments significantly decreased the amount of extracted FIP, which indicates that fresh, wet sediment should be used in this type of FIP extraction. Based on experimental results using the proposed extraction protocol, (1) FIP in sediments of Fubao Bay had a predominant status in the lake sediment and accounted for 23.4 to 39.8% of total phosphorus, and (2) Fe(II)(FIP) released in the extraction is directly proportional to phosphorus(FIP) (Fe(II)(FIP) = 2.84 x P(FIP) + 0.0007; R2 = 0.97) with an average molar ratio of Fe(II)(FIP)/P(FIP) of 2.7. This study shows that FIP extraction with 2,2'-bipyridine is a robust method for releasing ferrous iron associated with phosphorus. Further, the high percentage of FIP in total phosphorus (40%) measured in the study site using this extraction method suggests that FIP might have been often underestimated in previous studies. PMID:23356019

Li, Qingman; Wang, Xingxiang; Bartlett, Rebecca; Pinay, Gilles; Kan, Dan; Zhang, Wen; Sun, Jingxian

2012-11-01

302

Protonation of ferrous dinitrogen complexes containing a diphosphine ligand with a pendent amine.  

PubMed

The addition of acids to ferrous dinitrogen complexes [FeX(N2)(P(Et)N(Me)P(Et))(dmpm)](+) (X = H, Cl, or Br; P(Et)N(Me)P(Et) = Et2PCH2N(Me)CH2PEt2; and dmpm = Me2PCH2PMe2) gives protonation at the pendent amine of the diphosphine ligand rather than at the dinitrogen ligand. This protonation increased the ?N2 band of the complex by 25 cm(-1) and shifted the Fe(II/I) couple by 0.33 V to a more positive potential. A similar IR shift and a slightly smaller shift of the Fe(II/I) couple (0.23 V) was observed for the related carbonyl complex [FeH(CO)(P(Et)N(Me)P(Et))(dmpm)](+). [FeH(P(Et)N(Me)P(Et))(dmpm)](+) was found to bind N2 about three times more strongly than NH3. Computational analysis showed that coordination of N2 to Fe(II) centers increases the basicity of N2 (vs free N2) by 13 and 20 pKa units for the trans halides and hydrides, respectively. Although the iron center increases the basicity of the bound N2 ligand, the coordinated N2 is not sufficiently basic to be protonated. In the case of ferrous dinitrogen complexes containing a pendent methylamine, the amine site was determined to be the most basic site by 30 pKa units compared to the N2 ligand. The chemical reduction of these ferrous dinitrogen complexes was performed in an attempt to increase the basicity of the N2 ligand enough to promote proton transfer from the pendent amine to the N2 ligand. Instead of isolating a reduced Fe(0)-N2 complex, the reduction resulted in isolation and characterization of HFe(Et2PC(H)N(Me)CH2PEt2)(P(Et)N(Me)P(Et)), the product of oxidative addition of the methylene C-H bond of the P(Et)N(Me)P(Et) ligand to Fe. PMID:23506204

Heiden, Zachariah M; Chen, Shentan; Mock, Michael T; Dougherty, William G; Kassel, W Scott; Rousseau, Roger; Bullock, R Morris

2013-03-18

303

Rotating biological contactor for biochemical ferrous iron oxidation in the treatment of coal mine drainage. Master's thesis  

Microsoft Academic Search

Pilot scale testing of the rotating biological contactor for the oxidation of ferrous iron in acid coal mine drainage has shown the process to be dependable, efficient, and economically comparable to purely chemical methods of iron oxidation. The 0.5 meter device consisted of four sets of plastic discs affixed to a centralized shaft. As the discs rotated half immersed in

Olem

1975-01-01

304

Evaluation of the Impact of Diamond Film Hardcoatings on the Machining of Non-Ferrous Materials. Final Report. Volume 1.  

National Technical Information Service (NTIS)

The increased usage of very abrasive non-ferrous alloys including Silicon-Aluminum alloys is requiring the development of low-cost wear resistant tooling to replace cemented carbides(WC/Co). Developments with Chemical Vapor Deposition (CVD) of diamond fil...

J. A. Herb

1991-01-01

305

Efflorescent minerals from the metallurgical waste heaps of the KCM non-ferrous metal smelter, Plovdiv, Bulgaria  

Microsoft Academic Search

Alteration processes in the waste dumps of the KCM non-ferrous metal smelter near Plovdiv and their environmental impact have been focussed in this study. The waste materials from the metallurgical production (weltz-clinker) expected to be relatively insoluble were found to be affected by spontaneously initiated burning processes, turning the chemically resistant glassy phases into highly water soluble mineral phases. Newly

Radostina Atanassova; Thomas Kerestedjian

2009-01-01

306

Basic tendencies in producing standard specimens for chemical analysis of ferrous materials in the USSR and abroad  

Microsoft Academic Search

The intense growth of new industries does not diminish the acuteness of the problem of developing one of the most important spheres of material production and consumption, namely, the iron and steel industry. TILe growth in the production and consumption of ferrous metals and the requirement of improving their quality have led to the fact that the standard specimens (SS)

Yu. L. Pliner; A. B. Shaevich; M. I. Tsekhanskii; V. S. Kudryavtseva

1971-01-01

307

Financial risk management and enterprise value creation : Evidence from non-ferrous metal listed companies in China  

Microsoft Academic Search

Purpose The purpose of this paper is to explore whether financial risk management (FRM) can improve enterprise value in China's current economic environment. Design\\/methodology\\/approach A theoretical model is constructed which decomposes firms by different combinations expressed by cash flow and risk scale. Then, regression testing is conducted, taking the non-ferrous metal industry in Shanghai and Shenzhen Stock Exchanges

Peng-fei Wang; Shi Li; Jian Zhou

2010-01-01

308

Use of a Ferrous Sulfate - Sodium Dithionite Blend to Treat a Dissolved Phase Cr(VI) Plume  

EPA Science Inventory

A field study was conducted to evaluate the use of a combination of sodium dithionite and ferrous sulfate in creating an in situ redox zone for treatment of a dissolved phase Cr(VI) plume at a former industrial site. The reductant blend was injected into the path of a dissolved ...

309

An experimental study for enhancing the catalytic effects of various copper forms on the oxidation of ferrous iron  

Microsoft Academic Search

In this research the catalytic effect of copper compounds (ionic, oxide and oxide nanopowder) on the oxidation of ferrous iron by aeration was studied experimentally. When copper exists in solution, the oxidation rate of iron(ii) will increase. The experimental results showed that the oxidation rate increases with an increasing copper concentration. From the experimental data it can be determined that

Manizhe Moradi Shahre Babak; Ataallah Soltani Goharrizi; Mohammad Mirzaei; Emad Roayaei

2012-01-01

310

Copper electrowinning using spouted-bed electrodes: Part II. Copper electrowinning with ferrous ion oxidation as the anodic reaction  

Microsoft Academic Search

This Part II of the article describes an investigation at the University of California, Berkeley into the spouted-bed electrowinning\\u000a of copper with ferrous ion oxidation as the anodic reaction. The results of an experimental study are evaluated and compared\\u000a with the performance of the anodes of Part I.

V. Jiricny; A. Roy; J. W. Evans

2002-01-01

311

The Bacillus subtilis EfeUOB transporter is essential for high-affinity acquisition of ferrous and ferric iron.  

PubMed

Efficient uptake of iron is of critical importance for growth and viability of microbial cells. Nevertheless, several mechanisms for iron uptake are not yet clearly defined. Here we report that the widely conserved transporter EfeUOB employs an unprecedented dual-mode mechanism for acquisition of ferrous (Fe[II]) and ferric (Fe[III]) iron in the bacterium Bacillus subtilis. We show that the binding protein EfeO and the permease EfeU form a minimal complex for ferric iron uptake. The third component EfeB is a hemoprotein that oxidizes ferrous iron to ferric iron for uptake by EfeUO. Accordingly, EfeB promotes growth under microaerobic conditions where ferrous iron is more abundant. Notably, EfeB also fulfills a vital role in cell envelope stress protection by eliminating reactive oxygen species that accumulate in the presence of ferrous iron. In conclusion, the EfeUOB system contributes to the high-affinity uptake of iron that is available in two different oxidation states. PMID:23764491

Miethke, Marcus; Monteferrante, Carmine G; Marahiel, Mohamed A; van Dijl, Jan Maarten

2013-06-10

312

INJECTION OF A FERROUS SULFATE/SODIUM DITHIONITE REDUCTANT FOR IN-SITU TREATMENT OF HEXAVALENT CHROMIUM  

EPA Science Inventory

An in situ pilot study was conducted to evaluate the performance of a ferrous iron-based reductant solution in treating hexavalent chromium within a saturated zone source area at a former industrial site in Charleston, South Carolina (USA). The hexavalent source area, consisting...

313

Lead Speciation in the Dusts Emitted from Non-Ferrous Metallurgy Processes.  

PubMed

The paper presents results for the speciation analysis of lead in dusts derived from dedusting of technological gasses from metallurgical processes of non-ferrous metals with different elementary content, made in accordance with two equal sequential extractions. Analytical procedure A provided possibilities for determination of fraction of Pb(2+), metallic lead and fraction containing mainly lead sulfides. The second procedure (procedure B) was sequential extraction in accordance with Tessier. The results obtained in accordance with procedure A indicate that, regardless of the dust origin, the dominant group of Pb compounds is composed of lead salts which are soluble under alkaline conditions or lead compounds that form plumbites in the reaction with NaOH. PMID:21743754

Czaplicka, Marianna; Buzek, Lucja

2010-09-23

314

Corrosion performance of ferrous and refractory metals in molten salts under reducing conditions  

SciTech Connect

A lithium reduction technique to condition spent fuel for disposal has been developed at the Argonne National Laboratory. There is a need to ensure adequate vessel longevity through corrosion testing and, if necessary, materials development. Several ferrous alloys and tantalum specimens were submitted to a corrosion test at 725&hthinsp;{degree}C for thirty days in an argon atmosphere, using a lithium-chloride salt saturated with lithium metal and containing small amounts of lithium oxide and lithium nitride. The samples did not show dimensional or weight change, nor could corrosion attack be detected metallographically. The lithium-saturated salt system did not show any behavior similar to that of liquid lithium corrosion. From testing in other gas compositions, it appears that the presence of oxygen in the system is necessary to produce severe corrosion. {copyright} {ital 1999 Materials Research Society.}

Indacochea, J.E.; Smith, J.L.; Litko, K.R.; Karell, E.J. [Argonne National Laboratory, Chemical Technology Division, Building 205, 9700 South Cass Avenue, Argonne, Illinois 60439-4837 (United States)

1999-05-01

315

Spin transition in ferrous iron in MgSiO3 perovskite under pressure  

NASA Astrophysics Data System (ADS)

We present a density functional study of the pressure-induced spin transition in ferrous iron in MgSiO3 perovskite. We address the influence of iron concentration and configuration (structural and magnetic), as well as technical issues such as the nature of the exchange correlation (XC) functional (CA-LDA versus PBE-GGA) on the spin transition pressure. Supercells containing up to 160 atoms were adopted to tackle these issues. We show that there are preferred configurations for high-spin and low-spin iron and that the spin transition pressure depends strongly on iron concentration and XC functionals. We also address changes of atomic structure around Fe atoms and electronic structure including the blue shift accompanying the spin transition. Research supported by NSF/EAR 013533, 0230319, and NSF/ITR 0428774 (VLab). Computations were performed at the Minnesota Supercomputing Institute and Indiana University's BigRed system.

Umemoto, K.; Yu, Y.; Wentzcovitch, R. M.

2009-05-01

316

Spin transition in ferrous iron in MgSiO3 perovskite under pressure  

NASA Astrophysics Data System (ADS)

We present a density functional study of the pressure-induced spin transition in ferrous iron in MgSiO3 perovskite. We address the influence of iron concentration and configuration (structural and magnetic), as well as technical issues such as the nature of the exchange correlation (XC) functional (CA-LDA versus PBE-GGA) on the spin transition pressure. Supercells containing up to 160 atoms were adopted to tackle these issues. We show that there are preferred configurations for high-spin and low-spin iron and that the spin transition pressure depends strongly on iron concentration and XC functionals. We also address changes of atomic structure around Fe atoms and electronic structure including the blue shift accompanying the spin transition. Research supported by NSF/EAR 013533, 0230319, and NSF/ITR 0428774 (VLab). Computations were performed at the Minnesota Supercomputing Institute and Indiana University's BigRed system.

Umemoto, K.; Wentzcovitch, R.; Yu, Y.; Requist, R.

2007-12-01

317

Spin transition in ferrous iron in MgSiO3 perovskite under pressure  

NASA Astrophysics Data System (ADS)

We present a density functional study of the pressure-induced spin transition in ferrous iron in MgSiO3 perovskite. We address the influence of iron concentration and configuration (structural and magnetic), as well as technical issues such as the nature of the exchange correlation (XC) functional (CA-LDA versus PBE- GGA) on the spin transition pressure. Supercells containing up to 160 atoms were adopted to tackle these issues. We show that there are preferred configurations for high-spin and low-spin iron and that the spin transition pressure depends strongly on iron concentration and XC functionals. We also address changes of atomic structure around Fe atoms and electronic structure including the blue shift accompanying the spin transition. Research supported by NSF/EAR 013533, 0230319, and NSF/ITR 0428774 (VLab). Computations were performed at the Minnesota Supercomputing Institute and Indiana University"fs BigRed system.

Umemoto, K.; Wentzcovitch, R.; Yu, Y.; Requist, R.

2008-12-01

318

Iron oxide and hydroxide precipitation from ferrous solutions and its relevance to Martian surface mineralogy  

NASA Astrophysics Data System (ADS)

Experiments were performed to examine if the ubiquitousness of a weak magnetic component in all Martian surface fines tested with the Viking Landers can be attributed to ferric iron precipitation in aqueous solution under oxidizing conditions at neutral pH. Ferrous solutions were mixed in deionized water and various minerals were added to separate liquid samples. The iron-bearing additives included hematite, goethite, magnetite, maghemite, lepidocrocite and potassium bromide blank at varying concentrations. IR spectroscopic scans were made to identify any precipitates resulting from bubbling oxygen throughout the solutions; the magnetic properties of the precipitates were also examined. The data indicated that the lepidocrocite may have been preferentially precipitated, then aged to maghemite. The process would account for the presumed thin residue of maghemite on the present Martian surface, long after abundant liquid water on the Martian surface vanished.

Posey-Dowty, J.; Moskowitz, B.; Crerar, D.; Hargraves, R.; Tanenbaum, L.; Dowty, E.

1986-04-01

319

Relationship between fractional porosity and tensile strength for high-porosity sintered ferrous powder compacts  

SciTech Connect

The current study examines the mechanical properties of pressed and sintered ferrous powder metallurgy compacts with low relative densities, between 0.6 and 0.8. Three different powder particle compositions were investigated: eutectoid steel, stainless steel, and stainless tool steel compacts. To obtain information concerning the tensile properties of these low-density compacts, simple tensile tests were performed. In addition, Vickers microhardness tests were performed on metallographic sections of the tensile bars. The results from these tests are used to compare the measured relative strength values with estimates generated by previously published models. Also, the fracture surfaces of selected compacts were examined in the scanning electron microscope to obtain information concerning the fracture process.

Baron, R.P.; Wawner, F.E.; Wert, J.A. [Univ. of Virginia, Charlottesville, VA (United States). Dept. of Materials Science and Engineering

1998-07-03

320

Iron metabolism in aerobes: managing ferric iron hydrolysis and ferrous iron autoxidation.  

PubMed

Aerobes and anaerobes alike express a plethora of essential iron enzymes; in the resting state, the iron atom(s) in these proteins are in the ferrous state. For aerobes, ferric iron is the predominant environmental valence form which, given ferric iron's aqueous chemistry, occurs as 'rust', insoluble, bio-inert polymeric ferric oxide that results from the hydrolysis of [Fe(H(2)O)(6)](3+). Mobilizing this iron requires bio-ferrireduction which in turn requires managing the rapid autoxidation of the resulting Fe(II) which occurs at pH > 6. This review examines the aqueous redox chemistry of iron and the mechanisms evolved in aerobes to suppress the 'rusting out' of Fe(III) and the ROS-generating autoxidation of Fe(II) so as to make this metal ion available as the most ubiquitous prosthetic group in metallobiology. PMID:23264695

Kosman, Daniel J

2013-01-01

321

Local and structural characterisation of chlorinated phases formed on ferrous archaeological artefacts by ?XRD and ?XANES  

NASA Astrophysics Data System (ADS)

The deterioration after excavation of archaeological artefacts buried in soil is often associated with the presence of chlorine ions which play an important role in iron corrosion mechanisms. The understanding of these processes, related to the presence of chlorine, has to be made towards a precise study of the morphological and physicochemical properties of the iron corrosion products. A characterisation study on ferrous artefacts coming from four archaeological sites has been carried out; the rust layers have been studied using several techniques. The composition analyses were performed by energy dispersive spectroscopy coupled to scanning electron microscope. Structural information has been obtained by micro X-ray diffraction, micro Raman spectrometry and micro X-ray absorption experiments. The results obtained illustrate the necessity of the combination of these different techniques for the detailed study about corrosion typology.

Reguer, Solenn; Dillmann, Philippe; Mirambet, Fran鏾is; Bellot-Gurlet, Ludovic

2005-10-01

322

Plutonium-uranium separation in the Purex process using mixtures of hydroxylamine nitrate and ferrous sulfamate  

SciTech Connect

Laboratory studies, followed by plant operation, established that a mixture of hydroxylamine nitrate (HAN) and ferrous sulfamate (FS) is superior to FS used alone as a reductant for plutonium in the Purex first cycle. FS usage has been reduced by about 70% (from 0.12 to 0.04M) compared to the pre-1978 period. This reduced the volume of neutralized waste due to FS by 194 liters/metric ton of uranium (MTU) processed. The new flowsheet also gives lower plutonium losses to waste and at least comparable fission product decontamination. To achieve satisfactory performance at this low concentration of FS, the acidity in the 1B mixer-settler was reduced by using a split-scrub - a low acid scrub in stage one and a higher acid scrub in stage three - to remove acid from the solvent exiting the 1A centrifugal contactor. 8 references, 14 figures, 1 table.

McKibben, J.M.; Chostner, D.F.; Orebaugh, E.G.

1983-11-01

323

Inhibition of bacterial oxidation of ferrous iron by lead nitrate in sulfate-rich systems  

USGS Publications Warehouse

Inhibition of bacterial oxidation of ferrous iron (Fe(II)) by Pb(NO3)2 was investigated with a mixed culture of Acidithiobacillus ferrooxidans. The culture was incubated at 30 癈 in ferrous-sulfate medium amended with 024.2 mM Pb(II) added as Pb(NO3)2. Anglesite (PbSO4) precipitated immediately upon Pb addition and was the only solid phase detected in the abiotic controls. Both anglesite and jarosite (KFe3(SO4)2(OH)6) were detected in inoculated cultures. Precipitation of anglesite maintained dissolved Pb concentrations at 16.917.6 ?M regardless of the concentrations of Pb(NO3)2 added. Fe(II) oxidation was suppressed by 24.2 mM Pb(NO3)2 addition even when anglesite was removed before inoculation. Experiments with 048 mM KNO3 demonstrated that bacterial Fe(II) oxidation decreased as nitrate concentration increased. Therefore, inhibition of Fe(II) oxidation at 24.2 mM Pb(NO3)2 addition resulted from nitrate toxicity instead of Pb addition. Geochemical modeling that considered the initial precipitation of anglesite to equilibrium followed by progressive oxidation of Fe(II) and the precipitation of jarosite and an amorphous iron hydroxide phase, without allowing plumbojarosite to precipitate were consistent with the experimental time-series data on Fe(II) oxidation under biotic conditions. Anglesite precipitation in mine tailings and other sulfate-rich systems maintains dissolved Pb concentrations below the toxicity threshold of A. ferrooxidans.

Wang, Hongmei; Gong, Linfeng; Cravotta, Charles A.; Yang, Xiaofen; Tuovinen, Olli H.; Dong, Hailiang; Fu, Xiang

2013-01-01

324

Uptake of ferrous iron histidinate, a promoter of lipid peroxidation, by Ehrlich ascites tumor cells.  

PubMed

The kinetics of the uptake of Fe(II)-histidinate, a known promoter of lipid peroxidation, into Ehrlich ascites tumor (EAT) cells and the intracellular binding of iron were studied in vitro. EAT cells (27.10(6)/ml) were incubated in Hanks' balanced salts solution at 37 degrees C for various time intervals in the presence of FeSO4 (1 mM) and L-histidine (10 mM). Total iron was determined by the 1,10-phenanthroline/ascorbate method and ferric iron by reaction with 5-sulfosalicylic acid; the difference was ascribed to ferrous iron. Total iron decreased rapidly in the medium (242 nmol within the first 10 min), and a corresponding increase of total iron (saturation value 376 nmol after 60 min) was determined within the cells, after the cellular proteins had been solubilized with 6 M urea. In the absence of EAT cells, Fe(II)-histidinate was readily oxidized to Fe(III)-histidinate by oxygen, but this reaction was strongly retarded by the tumor cells. The uptake of iron histidinate occurred in the oxidized state, while an uptake of ferrous iron could not be proven unambiguously. When EAT cells were saturated with iron, it was found that 93% of intracellular iron was bound to water-insoluble proteins and 7% was associated with soluble proteins, while no unbound iron was detectable by the method used. It was concluded that, despite the high uptake of total iron, only a very small portion of the intracellular iron was available as a redox catalyst for lipid peroxidation. PMID:3416005

Sharaf El Din, M; Schaur, R J; Schauenstein, E

1988-09-01

325

Kinetics of triscarbonato uranyl reduction by aqueous ferrous iron: a theoretical study.  

PubMed

Uranium is a pollutant whose mobility is strongly dependent on its oxidation state. While U(VI) in the form of the uranyl cation is readily reduced by a range of natural reductants, by contrast complexation of uranyl by carbonate greatly reduces its reduction potential and imposes increased electron transfer (ET) distances. Very little is known about the elementary processes involved in uranium reduction from U(VI) to U(V) to U(IV) in general. In this study, we examine the theoretical kinetics of ET from ferrous iron to triscarbonato uranyl in aqueous solution. A combination of molecular dynamics (MD) simulations and density functional theory (DFT) electronic structure calculations is employed to compute the parameters that enter into Marcus' ET model, including the thermodynamic driving forces, reorganization energies, and electronic coupling matrix elements. MD simulations predict that two ferrous iron atoms will bind in an inner-sphere fashion to the three-membered carbonate ring of triscarbonato uranyl, forming the charge-neutral ternary Fe(2)UO(2)(CO(3))(3)(H(2)O)(8) complex. Through a sequential proton-coupled electron-transfer mechanism (PCET), the first ET step converting U(VI) to U(V) is predicted by DFT to occur with an electronic barrier that corresponds to a rate on the order of approximately 1 s(-1). The second ET step converting U(V) to U(IV) is predicted to be significantly endergonic. Therefore, U(V) is a stabilized end product in this ET system, in agreement with experiment. PMID:16884201

Wander, Matthew C F; Kerisit, Sebastien; Rosso, Kevin M; Schoonen, Martin A A

2006-08-10

326

Degradation and decolorization of a biodegradable-resistant polymeric dye by chelator-mediated Fenton reactions  

Microsoft Academic Search

Chelator-mediated Fenton reactions (CMFRs) were used to decolorize a biodegradable-resistant polymeric dye (Poly R-478). Screening of different iron chelators was performed on Fe3+-reduction activity. All chelators showed Fe3+-reduction activity over a wide range of pH (27) and each mol of catecholate chelators (3,4-dihydroxiphenilacetic acid桪OPAC and 2,3-dihydroxibenzoic acid桪HBA) reduced about 56moles of Fe3+ whereas hydroxamate chelators (acetohydroxamic acid桝HA and desferrioxamine B桪FB)

Valdeir Arantes; Carolina Baldocchi; Adriane Maria Ferreira Milagres

2006-01-01

327

MULTIDENTATE TEREPHTHALAMIDATE AND HYDROXYPYRIDONATE LIGANDS: TOWARDS NEW ORALLY ACTIVE CHELATORS  

SciTech Connect

The limitations of current therapies for the treatment of iron overload or radioisotope contamination have stimulated efforts to develop new orally bioavailable iron and actinide chelators. Siderophore-inspired tetradentate, hexadentate and octadentate terephthalamidate and hydroxypyridonate ligands were evaluated in vivo as selective and efficacious iron or actinide chelating agents, with several metal loading and ligand assessment procedures, using {sup 59}Fe, {sup 238}Pu, and {sup 241}Am as radioactive tracers. The compounds presented in this study were compared to commercially available therapeutic sequestering agents [deferoxamine (DFO) for iron and diethylenetriaminepentaacetic acid (DPTA) for actinides] and are unrivaled in terms of affinity, selectivity and decorporation efficacy, which attests to the fact that high metal affinity may overcome the low bioavailability properties commonly associated to multidenticity.

Abergel, Rebecca J.; Raymond, Kenneth N.

2011-07-13

328

Iron chelates: a challenge to chemists and M鰏sbauer spectroscopists  

NASA Astrophysics Data System (ADS)

The speciation of iron in aqueous solutions containing Fe3 + and selected chelates such as EDTA, EDDA, CDTA and HEDTA has been studied using transmission 57Fe M鰏sbauer spectrometry in frozen solutions. The protonation of various complexes as well as binuclear complex formation could be detected as a function of pH. Autoreduction of Fe3 + to Fe2 + was observed in several cases. Reaction with hydrogen peroxide proved to be rather different for the four ligands, while the dihapto complex [XFe( ? 2-O2)]3 - had surprisingly identical M鰏sbauer parameters for X = EDTA, CDTA or HEDTA. Paramagnetic spin relaxation observed in the M鰏sbauer spectra was found to be strongly influenced by the identity of the chelating ligand, despite the basically spin-spin origin of the phenomenon.

Homonnay, Z.; Szil醙yi, P. .; V閞tes, A.; Kuzmann, E.; Sharma, V. K.; Moln醨, G.; Bousseksou, A.; Gren鑓he, J.-M.; Brausam, A.; Meier, R.; van Eldik, R.

2008-02-01

329

Doping of graphene nanomeshes by ion-chelation  

NASA Astrophysics Data System (ADS)

Graphene nanomeshes (GNM's) are formed by the creation of a superlattice of pores in graphene. Depending upon the pore shape, size, superlattice constant and symmetry, GNM's can be semimetallic, or semiconducting with a fractional eV band gap, allowing them to be fruitfully employed in applications that pristine graphene cannot. In this work, first principles calculations are used to study the doping of semiconducting GNM's using a chemically motivated approach. It is shown that ion-chelation leads to a stable doping of the GNM's, and that it occurs within a rigid band doping picture. Such chelated or ``crown'' GNM structures are thus stable, high mobility semiconducting materials which can serve as building blocks for novel graphene-based nanoelectronics applications.

Maarouf, Ahmed; Nistor, Razvan; Afzali, Ali; Kuroda, Marcelo; Newns, Dennis; Martyna, Glenn

2013-03-01

330

Activation of rotavirus RNA polymerase by calcium chelation  

Microsoft Academic Search

Summary Two types of particles were isolated during purification of rotavirus. Dense (D) particles have a density of 1.38 in CsCl and exhibit spontaneously a fully active endogenous transcriptase. Light (L) particles (density 1.36 in CsCl) need to be treated with chelating agents to show a polymerase activity. The activation process of L particles was studied under strictly controlled monovalent,

J. Cohen; J. Laporte; A. Charpilienne; R. Scherrer

1979-01-01

331

Chelation ion chromatography of trace metal ions using metallochromic ligands  

Microsoft Academic Search

Hydrophobic metallochromic ligands can be used to coat high-performance reversed-phase substrates producing chelating stationary phases with the capacity to separate metal ions. To date the main approaches have been to `pre-coat' the substrate with the ligand and use it with a mobile phase containing an inorganic salt or alternatively to include the ligand itself within the mobile phase, where the

Paul R Haddad

1999-01-01

332

Amelioration of aluminum toxicity to sorghum seedlings by chelating agents  

Microsoft Academic Search

At the pH levels found in acid soils (4.5 to 5.5), theoretical equilibrium models predict that Al will be complexed on a nearly one to one molar basis by NTA, EGTA. oxalate (OX) and citrate (CIT). Growth chamber experiments were initiated using solutions containing Al (0, 2, or 10 ?M), Ca (400 ?.M). and a chelate (0 or 10 ?M)

L. M. Shuman; D. O. Wilson; E. L. Ramseur

1991-01-01

333

Chelate-Enhanced Phytoremediation of Soils Polluted with Heavy Metals  

Microsoft Academic Search

In general, hyperaccumulators are low biomass, slow-growing plants. High biomass non-hyperaccumulator plants by themselves are not a valid alternative for phytoextraction as they also have many limitations, such as small root uptake and little root-to-shoot translocation. In this context, chemically-induced phytoextraction (based on the fact that the application of certain chemicals, mostly chelating agents, to the soil significantly enhances metal

I. Alkorta; J. Hern醤dez-Allica; J. M. Becerril; I. Amezaga; I. Albizu; M. Onaindia; C. Garbisu

2004-01-01

334

Untersuchungen zum polarographischen Verhalten des Samarium(III)-Cupferron-Chelats  

Microsoft Academic Search

In aqueous solutions of samarium(III), cupferron and ammonium chloride a high sensitive polarographic wave is observed, which is suitable for the trace determination of samarium. The investigation of the electrode mechanism indicates that the polarographic process belongs to the adsorptive complex waves, which results from the reduction of the ligands of the Sm(III)-cupferron-chelate. The experimental results indicate that the electroactive

X. G. Yang; E. Jackwerth

1986-01-01

335

Phosphate compounds as iron chelators in animal cell cultures  

Microsoft Academic Search

Summary牋We have studied the capacity of a number of phosphate compounds to act in the double role as a phosphate source and a detoxifier\\u000a of ferric chloride hydroxo compounds, i.e. as Fe(III) chelators. The tested compounds were: orthophosphate, trimetaphosphate,\\u000a ?-glycerophosphate, ?-glycerophosphate, phytic acid, and phosphorylcholine; the test organism the ciliate protozoonTetrahymena thermophila, an animal cell; and the nutrient medium was

Leif Rasmussen; Hans Toftlund

1986-01-01

336

Removal of Trace Contaminants from Water Using New Chelating Resins  

Microsoft Academic Search

The modification of cross?linked polyacrylamide (CPAAm) and incorporation of methyl thiourea (MeTU) or phenyl thiourea (PhTU) group were utilized in the preparation of two new chelating resins CPAAm?EDA?MeTU (resin I) and CPAAM?EDA?PhTU (resin II), [EDA=ethylenediamine]. The prepared resins were characterized by elemental analysis and IR spectroscopy. The sorption behaviors of Cd(II), Pb(II), and Zn(II) ions on the prepared resins were

Mohammed A. Sharaf; Said A. Sayed; Ahmed A. Younis; A. B. Farag; Hassan A. Arida

2007-01-01

337

Performance of Chelating Resins Containing Calixpyrroles in Sorption of Anions  

Microsoft Academic Search

Characteristics and sorptive properties of three series of chelating resins having incorporated calixpyrrole ligands within their structures is reported. Two sets of resins were obtained by immobilization of calix[4]pyrrole or calix[4]pyrrole[2]thiophene on the beads of crosslinked (vinylbenzyl chloride)\\/divinylbenzene copolymer. The third series was synthesized by condensation of calix[4]pyrrole with formaldehyde. All resins displayed sorptive properties towards halide anions and cyanides

Andrzej Ka??dkowski; Andrzej W. Trochimczuk

2006-01-01

338

The removal of strontium from the mouse by chelating agents  

Microsoft Academic Search

The effects of the chelating agents monosodium glutamate, Tiron, tartaric acid, ascorbic acid, 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6), 2,3-dimercaptosuccinic acid (DMSA), succinic acid, malic acid, ethylendiaminetetraacetic acid (EDTA), ethylenglycol-bis-(-amino-ethylether)-N,N' tetraacetic acid (EGTA), cyclohexanediaminetetraacetic acid (CDTA) and diethylentriaminepentaacetic acid (DTPA) on the distribution and excretion of intraperitoneally injected strontium were investigated in male Swiss mice. Strontium nitrate was given at a dose equal to

Arturo Ortega; Mercedes G髆ez; Jose L. Domingo; Jacinto Corbella

1989-01-01

339

Chelate-Assisted Heavy Metal Movement Through the Root Zone  

NASA Astrophysics Data System (ADS)

Chelating agents are added to soil as a means to mobilize heavy metals for plant uptake during phytoremediation. Yet almost no studies follow the displacement of heavy metals through the vadose zone following solubilization with chelating agents. The objective of this work was to determine the movement of heavy metals through the soil profile and their absorption by barley (Hordeum vulgare L.) in a soil amended with biosolids and in the presence of a chelating agent (EDTA). Twelve columns 75 cm in height and 17 in diameter were packed with a Haynie very fine sandy loam (coarse-silty, mixed, calcareous, mesic Mollic Udifluvents) and watered with liquid biosolids applied at the surface at a rate of 120 kg N/ha. Three weeks after plants germinated, soil was irrigated with a solution of the disodium salt of EDTA added at a rate of 0.5 g/kg soil. Four treatments were imposed: columns with no plants and no EDTA; columns with no plants plus EDTA; columns with plants and no EDTA; and columns with plants and EDTA. Columns were watered intensively for 35 days until two pore volumes of water had been added, and the leachates were collected daily. With or without plants, columns with EDTA had lower total concentrations of Cu, Zn, Cd, Ni, and Pb in the surface 20 cm than columns without EDTA. Concentrations of the heavy metals in this layer were not afffected by the presence of roots. Iron in leachate was followed as an indicator metal for movement to groundwater. No iron appeared in the leachate without EDTA, either in the columns with plants or without plants. The peak concentration of iron in the leachate occurred three days earlier in the columns without plants and EDTA compared to the columns with plants and EDTA. The results indicated the importance of vegetation on retarding heavy metal leaching to groundwater during chelate-facilitated phytoremediation.

Kirkham, M.; Madrid, F.; Liphadzi, M. S.

2001-12-01

340

Reaction of gadolinium chelates with ozone and hydroxyl radicals.  

PubMed

Gadolinium chelates are used in increasing amounts as contrast agents in magnetic resonance imaging, and their fate in wastewater treatment has recently become the focus of research. Oxidative processes, in particular the application of ozone, are currently discussed or even implemented for advanced wastewater treatment. However, reactions of the gadolinium chelates with ozone are not yet characterized. In this study, therefore, rate constants with ozone were determined for the three commonly used chelates Gd-DTPA, Gd-DTPA-BMA, and Gd-BT-DO3A, which were found to be 4.8 0.88, 46 2.5, and 24 1.5 M(-1) s(-1), respectively. These low rate constants indicate that a direct reaction with ozone in wastewater is negligible. However, application of ozone in wastewater leads to substantial yields of ()OH. Different methods have been applied and compared for determination of k(()OH+Gdchelate). From rate constants determined by pulse radiolysis experiments (k(()OH+Gd-DTPA) = 2.6 0.2 10(9) M(-1) s(-1), k(()OH+Gd-DTPA-BMA) = 1.9 0.7 10(9) M(-1) s(-1), k(()OH+Gd-BT-DO3A) = 4.3 0.2 10(9) M(-1) s(-1)), it is concluded that a reaction in wastewater via ()OH radicals is feasible. Toxicity has been tested for educt and product mixtures of both reactions. Cytotoxicity (MTT test) and genotoxicity (micronuclei assay) were not detectable. PMID:23888885

Cyris, Maike; Knolle, Wolfgang; Richard, Jessica; Dopp, Elke; von Sonntag, Clemens; Schmidt, Torsten C

2013-08-22

341

Flue gas desulfurization/denitrification using metal-chelate additives  

DOEpatents

A method of simultaneously removing SO.sub.2 and NO from oxygen-containing flue gases resulting from the combustion of carbonaceous material by contacting the flue gas with an aqueous scrubber solution containing an aqueous sulfur dioxide sorbent and an active metal chelating agent which promotes a reaction between dissolved SO.sub.2 and dissolved NO to form hydroxylamine N-sulfonates. The hydroxylamine sulfonates are then separated from the scrubber solution which is recycled.

Harkness, John B. L. (Naperville, IL); Doctor, Richard D. (Glen Ellyn, IL); Wingender, Ronald J. (Deerfield, IL)

1986-01-01

342

EDTA bis-(Methyl tyrosinate): A chelating peptoid peroxynitrite scavenger  

Microsoft Academic Search

Conjugation of ethylenediaminetetra-acetic acid (EDTA) to methyl tyrosinate generates a chelating peptoid EDTA bis-(methyl tyrosinate), (EBMT). Peroxynitrite-mediated nitration was studied for the free peptoid and its ferric and cupric complexes. The nitration products were monitored by electronic absorption spectroscopy at ?max of 420nm (mono-nitrated) and 440nm (di-nitrated). Peak deconvolution was effected by pH manipulation as the mono-nitrated analogue of tyrosine

Anna E. O. Fisher; Declan P. Naughton

2003-01-01

343

Effect of tetraalkylammonium salt on the retention of metal chelates in reversed phase-high performance liquid chromatography  

Microsoft Academic Search

The retention of metal chelates with azo dye chelating agents was greatly reduced when tetraalkylammonium salts (TAAS) were added to the aqueous organic mobile phase in reversed phase-high performance liquid chromatography (RP-HPLC). TAAS was very effective for decreasing the retention time of the chelates including positively charged chelates strongly retained on the reversed phase stationary support. This was probably due

Jun'ichiro Miura

1992-01-01

344

Personalization of multiple sclerosis treatments: using the chelation therapy approach.  

PubMed

Though Multiple Sclerosis (MS) sufferers are probably genetically predisposed, toxic metal poisoning (TMP) does seem an increasingly likely environmental trigger. The technique for measuring and clearing TMP was chelation therapy using ethylene-diamine-tetracetic acid (EDTA), which revealed aluminum accumulation in both cases. The first patient, initially benefiting from removing dental fillings that had leaked mercury, also showed gadolinium accumulation from scan contrast medium, and a genomic deficiency of glutathione transferase M1. Glutathione production was impaired and hence also liver detoxification functions. The personal protocol involved glutathione administration and deutrosulfazyme to enhance oxygenation and alleviate oxidative stress. As aluminum began to clear with EDTA infusion, the extracellular/intracellular water ratio was carefully monitored, and carbohydrates limited. In the second case, aluminum poisoning responded to EDTA chelation therapy with eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA), multivitamins, and glutathione administration, again followed by deutrosulfazyme, water ratio control, and dietary correction. The two personalized protocols presented here tend to confirm the hypothesis of TMP as an environmental or iatrogenic trigger for MS, especially when inadequate detoxification lies at the root. Cleansing by chelation therapy, properly understood, can be efficacious, especially bearing in mind the altered cellular water ratio. PMID:23906103

Zanella, Sante Guido; di Sarsina, Paolo Roberti

345

Mercury removal in utility wet scrubber using a chelating agent  

DOEpatents

A method for capturing and reducing the mercury content of an industrial flue gas such as that produced in the combustion of a fossil fuel or solid waste adds a chelating agent, such as ethylenediaminetetraacetic acid (EDTA) or other similar compounds like HEDTA, DTPA and/or NTA, to the flue gas being scrubbed in a wet scrubber used in the industrial process. The chelating agent prevents the reduction of oxidized mercury to elemental mercury, thereby increasing the mercury removal efficiency of the wet scrubber. Exemplary tests on inlet and outlet mercury concentration in an industrial flue gas were performed without and with EDTA addition. Without EDTA, mercury removal totaled 42%. With EDTA, mercury removal increased to 71%. The invention may be readily adapted to known wet scrubber systems and it specifically provides for the removal of unwanted mercury both by supplying S.sup.2- ions to convert Hg.sup.2+ ions into mercuric sulfide (HgS) and by supplying a chelating agent to sequester other ions, including but not limited to Fe.sup.2+ ions, which could otherwise induce the unwanted reduction of Hg.sup.2+ to the form, Hg.sup.0.

Amrhein, Gerald T. (Louisville, OH)

2001-01-01

346

Ferrous Iron and Sulfur Oxidation and Ferric Iron Reduction Activities of Thiobacillus ferrooxidans Are Affected by Growth on Ferrous Iron, Sulfur, or a Sulfide Ore  

PubMed Central

Eight strains of Thiobacillus ferrooxidans (laboratory strains Tf-1 [= ATCC 13661] and Tf-2 [= ATCC 19859] and mine isolates SM-1, SM-2, SM-3, SM-4, SM-5, and SM-8) and three strains of Thiobacillus thiooxidans (laboratory strain Tt [= ATCC 8085] and mine isolates SM-6 and SM-7) were grown on ferrous iron (Fe2+), elemental sulfur (S0), or sulfide ore (Fe, Cu, and Zn). The cells were studied for their aerobic Fe2+ - and S0-oxidizing activities (O2 consumption) and anaerobic S0-oxidizing activity with ferric iron (Fe3+) (Fe2+ formation). Fe2+-grown T. ferrooxidans cells oxidized S0 aerobically at a rate of 2 to 4% of the Fe2+ oxidation rate. The rate of anaerobic S0 oxidation with Fe3+ was equal to the aerobic oxidation rate in SM-1, SM-3, SM-4, and SM-5, but was only one-half or less that in Tf-1, Tf-2, SM-2, and SM-8. Transition from growth on Fe2+ to that on S0 produced cells with relatively undiminished Fe2+ oxidation activities and increased S0 oxidation (both aerobic and anaerobic) activities in Tf-2, SM-4, and SM-5, whereas it produced cells with dramatically reduced Fe2+ oxidation and anaerobic S0 oxidation activities in Tf-1, SM-1, SM-2, SM-3, and SM-8. Growth on ore 1 of metal-leaching Fe2+-grown strains and on ore 2 of all Fe2+-grown strains resulted in very high yields of cells with high Fe2+ and S0 oxidation (both aerobic and anaerobic) activities with similar ratios of various activities. Sulfur-grown Tf-2, SM-1, SM-4, SM-6, SM-7, and SM-8 cultures leached metals from ore 3, and Tf-2 and SM-4 cells recovered showed activity ratios similar to those of other ore-grown cells. It is concluded that all the T. ferrooxidans strains studied have the ability to produce cells with Fe2+ and S0 oxidation and Fe3+ reduction activities, but their levels are influenced by growth substrates and strain differences.

Suzuki, Isamu; Takeuchi, Travis L.; Yuthasastrakosol, Trin D.; Oh, Jae Key

1990-01-01

347

Chelation therapy in Wilson's disease: from D-penicillamine to the design of selective bioinspired intracellular Cu(I) chelators.  

PubMed

Wilson's disease is an orphan disease due to copper homeostasis dysfunction. Mutations of the ATP7B gene induces an impaired functioning of a Cu-ATPase, impaired Cu detoxification in the liver and copper overload in the body. Indeed, even though copper is an essential element, which is used as cofactor by many enzymes playing vital roles, it becomes toxic when in excess as it promotes cytotoxic reactions leading to oxidative stress. In this perspective, human copper homeostasis is first described in order to explain the mechanisms promoting copper overload in Wilson's disease. We will see that the liver is the main organ for copper distribution and detoxification in the body. Nowadays this disease is treated life-long by systemic chelation therapy, which is not satisfactory in many cases. Therefore the design of more selective and efficient drugs is of great interest. A strategy to design more specific chelators to treat localized copper accumulation in the liver will then be presented. In particular we will show how bioinorganic chemistry may help in the design of such novel chelators by taking inspiration from the biological copper cell transporters. PMID:22327203

Delangle, Pascale; Mintz, Elisabeth

2012-02-13

348

Comparison of measures of lead exposure, dose, and chelatable lead burden after provocative chelation in organolead workers.  

PubMed Central

OBJECTIVES--To describe 6 h urinary lead excretion (6 h PbU) after 1 g intravenous ethylene diamine tetraacetic acid (EDTA) in organolead manufacturing workers with mixed exposure to organic and inorganic lead; to determine the predictors of lead excretion (PbU); and to determine the extent to which internal lead stores and ongoing external exposure govern blood concentrations of lead (PbB). METHODS--A case series of 21 active workers were studied. Personal industrial hygiene data, grouped by 29 exposure zones, in combination with personal interviews about work location and times were used to derive several measures of recent and cumulative exposure to organic and inorganic lead. The average exposure intensities assigned to the 29 zones ranged from 4 to 119 micrograms/m3 (0.02-0.57 mumol/m3 as lead) for organic lead and from 1 to 56 micrograms/m3 (0.004-0.27 mumol/m3) for inorganic lead. RESULTS--After controlling for age, 6 h PbU was significantly and positively correlated with summary measures of PbB--for example, lifetime peak PbB, time weighted PbB--and zinc protoporphyrin concentrations--for example, lifetime peak zinc protoporphyrin, time weighted zinc protoporphyrin--but not with measures of estimated external exposure--for example, duration of exposure and cumulative exposure to inorganic or organic lead. Among workers with higher chelatable lead burdens (6 h PbU > or = 212.4 micrograms (1.03 mumol) divided at the median), there was no apparent relation between recent inorganic lead exposure and PbB at the time of chelation. Among workers with lower chelatable lead burdens (6 h PbU < 212.4 micrograms (1.03 mumol) however, there was a significant relation between exposure and effect between recent exposure to inorganic lead and PbBs. CONCLUSION--These findings are consistent with the concept of physiological dampening. The high chelatable lead burden, a source of internal exposure, dampens the effect of external exposure on PbBs. The data suggest that in organolead workers with high chelatable lead burdens, PbBs may be more influenced by internal lead stores than by variations in airborne exposure to organic and inorganic lead.

Schwartz, B S; McGrail, M P; Stewart, W; Pluth, T

1994-01-01

349

Leaching of Zinc Sulfide by Thiobacillus ferrooxidans: Bacterial Oxidation of the Sulfur Product Layer Increases the Rate of Zinc Sulfide Dissolution at High Concentrations of Ferrous Ions  

PubMed Central

This paper reports the results of leaching experiments conducted with and without Thiobacillus ferrooxidans at the same conditions in solution. The extent of leaching of ZnS with bacteria is significantly higher than that without bacteria at high concentrations of ferrous ions. A porous layer of elemental sulfur is present on the surfaces of the chemically leached particles, while no sulfur is present on the surfaces of the bacterially leached particles. The analysis of the data using the shrinking-core model shows that the chemical leaching of ZnS is limited by the diffusion of ferrous ions through the sulfur product layer at high concentrations of ferrous ions. The analysis of the data shows that diffusion through the product layer does not limit the rate of dissolution when bacteria are present. This suggests that the action of T. ferrooxidans in oxidizing the sulfur formed on the particle surface is to remove the barrier to diffusion by ferrous ions.

Fowler, T. A.; Crundwell, F. K.

1999-01-01

350

Leaching of zinc sulfide by Thiobacillus ferrooxidans: bacterial oxidation of the sulfur product layer increases the rate of zinc sulfide dissolution at high concentrations of ferrous ions.  

PubMed

This paper reports the results of leaching experiments conducted with and without Thiobacillus ferrooxidans at the same conditions in solution. The extent of leaching of ZnS with bacteria is significantly higher than that without bacteria at high concentrations of ferrous ions. A porous layer of elemental sulfur is present on the surfaces of the chemically leached particles, while no sulfur is present on the surfaces of the bacterially leached particles. The analysis of the data using the shrinking-core model shows that the chemical leaching of ZnS is limited by the diffusion of ferrous ions through the sulfur product layer at high concentrations of ferrous ions. The analysis of the data shows that diffusion through the product layer does not limit the rate of dissolution when bacteria are present. This suggests that the action of T. ferrooxidans in oxidizing the sulfur formed on the particle surface is to remove the barrier to diffusion by ferrous ions. PMID:10583978

Fowler, T A; Crundwell, F K

1999-12-01

351

Rates of cuticular penetration of chelated Fe(III): role of humidity, concentration, adjuvants, temperature, and type of chelate.  

PubMed

Time courses of cuticular penetration of FeCl3 and Fe(III) complexes of citric acid, EDTA, EDDHA (Sequestrene 138Fe), imidodisuccinic acid (IDHA), and ligninsulfonic acid (Natrel) were studied using astomatous cuticular membranes (CMs) isolated from Populus x canescens leaves. At 100% relative humidity, the Fe(III) chelates disappeared exponentially with time from the surface of the CMs; that is, penetration was a first-order process that can be described using rate constants or half-times of penetration (t(1/2)). Half-times ranged from 20 to 30 h. At 90% humidity, penetration rates were insignificant with the exception of Natrel, for which t(1/2) amounted to 58 h. Rate constants were independent of temperature (15, 25, and 35 degrees C). Permeability decreased with increasing Fe chelate concentration (IDHA and EDTA). At 100% humidity, half-times measured with FeIDHA were 11 h (2 mmol L(-1)), 17 h (10 mmol L(-1)) and 36 h (20 mmol L(-1)), respectively. In the presence of FeEDTA, penetration of CaCl2 was slowed greatly. Half-times for penetration of CaCl2, which were 1.9 h in the absence of FeEDTA, rose to 3.12 h in the presence of an equimolar concentration of EDTA and 13.3 h when the FeEDTA concentration was doubled. Hence, Fe chelates reduced permeability of CMs to CaCl2 and to the Fe chelates themselves. It is suggested that Fe chelates reduced the size of aqueous pores. This view is supported by the fact that rate constants for calcium salts were about 5 times higher than for Fe chelates with the same molecular weights. Adding Tween 20 (5 g L(-1)) as a humectant did not increase permeability to FeIDHA at 90% humidity and below, while addition of glycine betaine did. Penetration of FeCl3 applied at 5 g L(-1) (pH 1.5) was not a first order process as rate constants decreased rapidly with time. Only 2% of the dose penetrated during the first 2 h and less than that in the subsequent 8 h. Recovery was only 70%. This was attributed to the formation of insoluble Fe hydroxide precipitates on CMs. These results explain why in the past foliar application of Fe compounds had limited success. Inorganic Fe salts are instable and phytotoxic because of low pH, while Fe chelates penetrate slowly and 100% humidity is required for significant penetration rates. Concentrations as low as reasonably possible should be used. These physical facts are expected to apply to stomatous leaf surfaces as well, but absolute rates probably depend on leaf age and plant species. High humidity in stagnant air layers may favor penetration rates across stomatous leaf surfaces when humidity in bulk air is below 100%. PMID:15913315

Sch鰊herr, J鰎g; Fern醤dez, Victoria; Schreiber, Lukas

2005-06-01

352

Using AC field measurement data at an arbitrary liftoff distance to size long surface-breaking cracks in ferrous metals  

Microsoft Academic Search

We propose a model-based inversion method to size long surface-breaking cracks in ferrous metals using alternative current field measurement (ACFM) data at an arbitrary liftoff distance. This method employs conjugate gradients optimization to invert measured surface ACFM signal to crack depth. To alleviate the adverse effect of sensor liftoff uncertainty on crack sizing, we propose a blind de-convolution algorithm for

Reza Khalaj Amineh; Maryam Ravan; S. H. Hesam Sadeghi; Rouzbeh Moini

2008-01-01

353

Effect of manganese on an iron-based Fischer朤ropsch synthesis catalyst prepared from ferrous sulfate  

Microsoft Academic Search

The effects of manganese on the textural properties, bulk and surface phase compositions, reduction\\/carburization behaviors and surface basicity of an Fe朚n朘\\/SiO2 catalyst prepared from ferrous sulfate were investigated by N2 physisorption, M鰏sbauer spectroscopy, X-ray photoelectron spectroscopy (XPS), H2 (or CO) temperature-programmed reduction (TPR) and CO2 temperature-programmed desorption (TPD). The Fischer朤ropsch synthesis (FTS) performance of the catalysts with different contents of

Tingzhen Li; Yong Yang; Chenghua Zhang; Xia An; Haijun Wan; Zhichao Tao; Hongwei Xiang; Yongwang Li; Fan Yi; Binfu Xu

2007-01-01

354

Biodegradation kinetics of ferrous(II) cyanide complex ions by immobilized Pseudomonas fluorescens in a packed bed column reactor  

Microsoft Academic Search

Combined external mass transfer and intrinsic biodegradation effects on the observed biodegradation rate were investigated for ferrous (II) cyanide complex (ferrocyanide) ions removal with calcium朼lginate gel immobilized Pseudomonas fluorescens in a packed bed column reactor. Assuming first-order biodegradation kinetics, observed first-order biodegradation rate constants (kp) were calculated at different flow rates. To investigate the effect of external film diffusion on

Arzu Y. Dursun; Z黰riye Aksu

2000-01-01

355

Advances in understanding atmospheric corrosion of iron. I. Rust characterisation of ancient ferrous artefacts exposed to indoor atmospheric corrosion  

Microsoft Academic Search

Metallic substrates and rust layers of several hundred year old (y.o.) ferrous artefacts were characterised. Composition, structure and porosity of the rust were analysed by different methods: OM, SEM, EDS, EPMA, XRD, ?XRD, SAXS, BET and mercury porosimetry.Several important parameters to describe an old rust layer were determined and measured. These parameters will be used for the modelling of long-term

Ph Dillmann; F Mazaudier; S H渞l

2004-01-01

356

Dose-response curve slope improvement and result reproducibility of ferrous-sulphate-doped gels analysed by NMR imaging  

Microsoft Academic Search

Ferrous sulphate gel analysed by relaxation time measurements with NMR imaging is considered a useful dosimeter for 3D determinations of absorbed dose. A protocol for the gel preparation with agarose SeaPlaque that leads to a dosimeter with very high dose sensitivity is described. The dose-response curve slope is about 0.2 s-1 Gy-1 and the G factor turns out to be

G. Gambarini; S. Arrigoni; M. C. Cantone; N. Molho; L. Facchielli; A. E. Sichirollo

1994-01-01

357

The effect of water and fO 2 on the ferricferrous ratio of silicic melts  

Microsoft Academic Search

New experiments on the effect of dissolved water on the ferricferrous ratio of silicic melts have been performed at 200 MPa, between 800癈 and 1000癈 and for fO2 between NNO?1.35 and NNO+6.6. Water-saturated conditions were investigated. Compositions studied include six metaluminous synthetic melts, with FeOtot progressively increasing from 0.47 to 4.25 wt.%, two natural obsidian glasses (one peraluminous and the

Fabrice Gaillard; Bruno Scaillet; Michel Pichavant; Jean-Michel B閚y

2001-01-01

358

The role of ferrous ion in Fenton and photo-Fenton processes for the degradation of phenol  

Microsoft Academic Search

The efficiency of different Fenton-related oxidative processes such as Fenton, solar-Fenton and UV-Fenton were examined using phenol as a model compound in simulated and industrial wastewater. A batch study was conducted to optimize parameters like pH, hydrogen peroxide concentration and ferrous ion concentration governing the Fenton process. At optimum conditions, different Fenton-related processes were compared for the degradation of phenol.

V. Kavitha; K. Palanivelu

2004-01-01

359

Effect of boronizing and shot peening in ferrous based FeCu朑raphite powder metallurgy material on wear, microstructure and mechanical properties  

Microsoft Academic Search

Ferrous based materials manufactured by powder metallurgy (P\\/M) method are widely used in industry. These materials are very important because they do not require machining, have self-lubricated properties as journal bearing material, find applications in medical industry. In this study, powder metal parts were manufactured from ferrous based FeCu朑raphite composites by P\\/M method. Wear and mechanical test samples were manufactured

Selim Sarper Yilmaz; Bekir Sad?k 躰l; Remzi Varol

2010-01-01

360

Neutral thiol as a proximal ligand to ferrous heme iron: Implications for heme proteins that lose cysteine thiolate ligation on reduction  

PubMed Central

Cysteine plays a key role as a metal ligand in metalloproteins. In all well-recognized cases, however, it is the anionic cysteinate that coordinates. Several cysteinate-ligated heme proteins are known, but some fail to retain thiolate ligation in the ferrous state, possibly following protonation to form neutral cysteine. Ligation by cysteine thiol in ferrous heme proteins has not been documented. To establish spectroscopic signatures for such systems, we have prepared five-coordinate adducts of the ferrous myoglobin H94G cavity mutant with neutral thiol and thioether sulfur donors as well as six-coordinate derivatives such as with CO and, when possible, with NO and O2. A thiol-ligated oxyferrous complex is reported, to our knowledge for the first time. Further, a bis-thioether ferrous H93G model for bis-methionine ligation, as found in Pseudomonas aeruginosa bacterioferritin heme protein, is described. Magnetic CD spectroscopy has been used due to its established ability in axial ligand identification. The magnetic CD spectra of the H93G complexes have been compared with those of ferrous H175C/D235L cytochrome c peroxidase to show that its proximal ligand is neutral cysteine. We had previously reported this cytochrome c peroxidase mutant to be cysteinate-ligated in the ferric state, but the ferrous ligand was undetermined. The spectral properties of ferrous liver microsomal cytochrome P420 (inactive P450) are also consistent with thiol ligation. This study establishes that neutral cysteine can serve as a ligand in ferrous heme iron proteins, and that ferric cysteinate-ligated heme proteins that fail to retain such ligation on reduction may simply be ligated by neutral cysteine.

Perera, Roshan; Sono, Masanori; Sigman, Jeffrey A.; Pfister, Thomas D.; Lu, Yi; Dawson, John H.

2003-01-01

361

Bioavailability of stabilised ferrous gluconate with glycine in fresh cheese matrix: a novel iron compound for food fortification.  

PubMed

Iron fortification of foods continues to be one of the preferred ways of improving the iron status of the population. Dairy product is a common product in the diet; therefore, it is a plausible vehicle for iron fortification. This study aims to investigate the bioavailability of ferrous gluconate stabilised with glycine (FGSG) in a fresh cheese fortified with zinc. The iron bioavailability of fresh cheese fortified with either FGSG and with or without zinc and FGSG in aqueous solution and a water solution of ferrous ascorbate (reference dose) was studied using double radio iron ((55)Fe and (59)Fe) erythrocyte incorporation in 15 male subjects. All subjects presented with normal values for iron status parameters. The geometric mean of iron bioavailability for the water solution of FGSG was 38.2 %, adjusted to 40 % from reference doses (N.S.). Iron bioavailability in fresh cheese fortified with Ca and Zn was 15.4 % and was 23.1 % without Zn, adjusted to 40 % from reference doses (N.S.). The results of the present study show that the novel iron compound ferrous gluconate stabilised with glycine in a fresh cheese matrix is a good source of iron and can be used in iron fortification programmes. PMID:23271679

Pizarro, Fernando; Boccio, Jos; Salgueiro, Mar韆; Olivares, Manuel; Carmuega, Esteban; Weill, Ricardo; Marque, Sebastien; Frereux, Marine; Noirt, Florence

2012-12-29

362

Rheological parameter estimation for a ferrous-nanoparticle-based magnetorheological fluid using genetic algorithms  

NASA Astrophysics Data System (ADS)

The primary objective of this study is to estimate the parameters of a constitutive model characterizing the rheological properties of a ferrous nanoparticle-based magnetorheological fluid. Constant shear rate rheometer measurements were carried out using suspensions of nanometer sized iron particles in hydraulic oil. These measurements provided shear stress vs. shear rate as a function of applied magnetic field. The MR fluid was characterized using both a Bingham-Plastic constitutive model and a Herschel-Bulkley constitutive model. Both these models have two regimes: a rigid pre-yield behavior for shear stress less than a field-dependant yield stress, and viscous behavior for higher shear rates. While the Bingham-Plastic model assumes linear post-yield behavior, the Herschel-Bulkley model uses a power law dependent on the dynamic yield shear stress, a consistency parameter and a flow behavior index. Determination of the model parameters is a complex problem due to the non-linearity of the model and the large amount of scatter in the experimentally observed data. Usual gradient-based numerical methods are not sufficient to determine the characteristic values. In order to estimate the rheological parameters, we have used a genetic algorithm and carried out global optimization. The obtained results provide a good fit to the data and support the choice of the Herschel-Bulkley fluid model.

Chaudhuri, Anirban; Wereley, Norman M.; Radhakrishnan, Radhakumar; Sudarshan, T. S.

2004-07-01

363

Thermodynamics and kinetics of the formation of Widmanstaetten ferrite plates in ferrous alloys  

SciTech Connect

Experimental data on the formation of Widmanstaetten/bainitic ferrite in ferrous alloys (i.e., the Widmanstaetten start temperature, partition of alloying elements, incomplete transformation, lengthening kinetics, etc.) are examined on the basis of thermodynamic calculations and kinetic analyses. A morphological change of ferrite from grain-boundary allotriomorph to Widmanstaetten plate occurs well above the T[sub 0] temperature, except in high Mn and Ni alloys, but does so in the regime of carbon diffusion control in all alloys. Under the assumption that the plate tip consists of a pair of ledges of the height equal to the tip radius, the reported lengthening kinetics of ferrite plates can be accounted for very well by the diffusion-controlled motion of these ledges in a wide range of carbon supersaturation. It is also shown that the transformation stasis (incomplete transformation) observed below the kinetically defined B[sub s] in some iron alloys cannot be unequivocally attributed to either the completion of the precipitation of no-partitioned ferrite or the loss of the driving force for subsequent shear transformation.

Enomoto, Masato (Ibaraki Univ., Hitachi (Japan). Dept. of Materials Science)

1994-09-01

364

Vibrational Assignments of Six-Coordinate Ferrous Heme Nitrosyls: New Insight From Nuclear Resonance Vibrational Spectroscopy  

SciTech Connect

This Communication addresses a long-standing problem: the exact vibrational assignments of the low-energy modes of the Fe-N-O subunit in six-coordinate ferrous heme nitrosyl model complexes. This problem is addressed using nuclear resonance vibrational spectroscopy (NRVS) coupled to {sup 15}N{sup 18}O isotope labeling and detailed simulations of the obtained data. Two isotope-sensitive features are identified at 437 and 563 cm{sup -1}. Normal coordinate analysis shows that the 437 cm{sup -1} mode corresponds to the Fe-NO stretch, whereas the 563 cm{sup -1} band is identified with the Fe-N-O bend. The relative NRVS intensities of these features determine the degree of vibrational mixing between the stretch and the bend. The implications of these results are discussed with respect to the trans effect of imidazole on the bound NO. In addition, a comparison to myoglobin-NO (Mb-NO) is made to determine the effect of the Mb active site pocket on the bound NO.

Paulat, F.; Berto, T.C.; George, S.DeBeer; Goodrich, L.; Praneeth, V.K.K.; Sulok, C.D.; Lehnert, N.

2009-05-21

365

The chemistry of the thermal decomposition of pseudobrookite ferrous titanium oxides  

SciTech Connect

The thermal decomposition of two metastable ferrous titanium oxide compounds of commercial interest have been studied by in situ x-ray and neutron diffraction at elevated temperatures as well as by {sup 57}Fe Mossbauer effect spectroscopy. Thermal decomposition was monitored by collecting neutron diffraction data (taken at the Argonne National Laboratory Intense Pulsed Neutron Source (IPNS) powder diffractometers) at 30-min intervals at 900 and 1,000{degree}C. Previous work has shown that each of these materials (pseudobrookite structure, AB{sub 2}O{sub 5}), (Mn{sub 0.05}Fe{sub 0.33}Ti{sub 0.52})(Ti{sub 2.0})O{sub 5} and (Mg{sub 0.21}Fe{sub 0.33}Ti{sub 0.46})(Ti{sub 1.9}Mg{sub 0.1})O{sub 5}, has a significant amount of Ti in the +3 oxidation state and is completely ordered (no Fe located in the B site). The results of these in situ diffraction studies show that, prior to the thermal decomposition of the slags, there is a redistribution of cations within the pseudobrookite structure.

Teller, R.G.; Antonio, M.R. (BP Research, Cleveland, OH (USA)); Grau, A.E.; Gueguin, M. (QIT-Fer et Titane Inc., Sorel, Quebec (Canada)); Kostiner, E. (Univ. of Connecticut, Storrs (USA))

1990-10-01

366

Oxidation of ferrous hydroxides with nitrate: a versatile method for the preparation of magnetic colloidal particles.  

PubMed

Slightly over 30 years ago, Sugimoto and Matijevi? published an article in this journal on the synthesis of uniform magnetite particles by the partial oxidation of ferrous hydroxide gels. The article has become a widely-used reference for the preparation of magnetite particles in aqueous media. A reason for this was the thoroughness of their study and the versatility of the process: the authors described conditions under which cubic nanometric (30-100 nm) crystals, or larger (0.4-1.1 ?m) spherical particles, the latter having either a smooth or a rough surface, could be obtained. Further work by Matijevi? and other authors has shown that small modifications of the process, such as the addition of divalent cations other than Fe(2+) to the system or the superposition of a magnetic field, can be used for the preparation of ferrite particles or rod-like particles, respectively. In this article we present a short description of the synthesis process and a brief overview of subsequent work carried out by other researchers that illustrates the versatility and the potential of this method. PMID:23178092

Vereda, F; de Vicente, J; Hidalgo-Alvarez, R

2012-10-10

367

Oxidative precipitation of groundwater-derived ferrous iron in the subterranean estuary of a coastal bay  

NASA Astrophysics Data System (ADS)

Sediment cores from the intertidal zone of Waquoit Bay (Cape Cod, Massachusetts) yielded iron oxide-coated sands in the subterranean estuary, which underlies the head of the bay. The oxides were dark red, yellow and orange colors and are formed by the oxidation of ferrous iron-rich groundwater near the groundwater-seawater interface. Within these iron oxide-rich sediments, the concentration of the combined amorphous and crystalline forms of iron oxides ranged between 2500 and 4100 ppm of Fe. These concentrations were 4-6 times greater than the surface sands, and 10-15 times more Fe rich than sands collected from an off-site location. The precipitation of iron oxides in subterranean estuaries could act as a geochemical barrier by retaining and accumulating certain dissolved chemical species carried to the coast by groundwater. Indeed, phosphorus concentrations in the iron oxide-rich sands of Waquoit Bay were 5-7 times greater than the overlying surface sands.

Charette, Matthew A.; Sholkovitz, Edward R.

2002-05-01

368

Investigation and analysis of ferrous sulfate polyvinyl alcohol (PVA) gel dosimeter  

NASA Astrophysics Data System (ADS)

Ferrous sulfate (Fe(SO4)2) PVA gels were investigated for a range of absorbed doses up to 20 Gy using both magnetic resonance imaging (MRI) and spectrophotometry to determine R1 and optical density (OD) dose responses and G values. It was found that R1- and OD-dose sensitivities increased with O2 saturation or by the introduction of a freeze-thaw cycle during preparation of the PVA gel. The storage temperature of the Fe(SO4)2 PVA gel at -18 癈 increased R1-dose sensitivity above that of gels stored at 5 癈. The addition of sucrose to the formulation was found to result in the largest increase in both R1- and OD-dose sensitivities. Fe(SO4)2 PVA gel with and without the addition of xylenol orange was demonstrated to have a G value of ~20 ions/100 eV and with sucrose ~24 ions/100 eV.

Hill, Brendan; B鋍k, Sven . J.; Lepage, Martin; Simpson, John; Healy, Brendan; Baldock, Clive

2002-12-01

369

Phosphate removal by refined aspen wood fiber treated with carboxymethyl cellulose and ferrous chloride.  

PubMed

Biomass-based filtration media are of interest as an economical means to remove pollutants and nutrients found in stormwater runoff. Refined aspen wood fiber samples treated with iron salt solutions demonstrated limited capacities to remove (ortho)phosphate from test solutions. To provide additional sites for iron complex formation, and thereby impart a greater capacity for phosphate removal, a fiber pretreatment with an aqueous solution of a non-toxic anionic polymer, carboxymethyl cellulose (CMC), was evaluated. Problems with excessive viscosities during the screening of commercially available CMC products led to the selection of an ultra low viscosity CMC product that was still usable at a 4% concentration in water. Soxhlet extractions of chipped aspen wood and refined aspen wood fiber samples showed a higher extractives content for the refined material. Analysis of these extracts by FTIR spectroscopy suggested that the higher extractives content for the refined material resulted from the fragmentation of cell wall polymers (e.g., lignin, hemicelluloses) normally insoluble in their native states. Spectroscopic analysis of CMC and ferrous chloride treated fibers showed that the complex formed was sufficiently stable to resist removal during subsequent water washes. Equilibrium sorption data, which fit better with a Freundlich isotherm model than a Langmuir isotherm model, showed that phosphate removal could be enhanced by the CMC pretreatment. Results suggest that the process outlined may provide a facile means to improve the phosphate removal capacity of biomass-based stormwater filtration media. PMID:16361096

Eberhardt, Thomas L; Min, Soo-Hong; Han, James S

2005-12-19

370

Development of a New Ferrous Aluminosilicate Refractory Material for Investment Casting of Aluminum Alloys  

NASA Astrophysics Data System (ADS)

Investment casting is a time-consuming, labour intensive process, which produces complex, high value-added components for a variety of specialised industries. Current environmental and economic pressures have resulted in a need for the industry to improve current casting quality, reduce manufacturing costs and explore new markets for the process. Alumino-silicate based refractories are commonly used as both filler and stucco materials for ceramic shell production. A new ceramic material, norite, is now being produced based on ferrous aluminosilicate chemistry, having many potential advantages when used for the production of shell molds for casting aluminum alloy. This paper details the results of a direct comparison made between the properties of a ceramic shell system produced with norite refractories and a typical standard refractory shell system commonly used in casting industry. A range of mechanical and physical properties of the systems was measured, and a full-scale industrial casting trial was also carried out. The unique properties of the norite shell system make it a promising alternative for casting aluminum based alloys in the investment foundry.

Yuan, Chen; Jones, Sam; Blackburn, Stuart

2012-12-01

371

Vegetable oil stability at elevated temperatures in the presence of ferric stearate and ferrous octanoate.  

PubMed

The thermoxidative stability of partially hydrogenated soybean oil (PHSBO) was examined after addition of ferric stearate and ferrous octanoate, and then heating the samples at 120, 160, 180, and 200 degrees C. In a second experiment, the effect of iron concentration (ferric stearate) on PHSBO stability was examined at 180 degrees C, and at concentrations of approximately 0.5 and 1.2 mg of added iron/kg PHSBO. Oil samples were heated continuously for 72 h and sampled every 12 h. The acid value, p-anisidine value, color, dielectric constant and the triacylglycerol polymer content of oil samples were compared to oil samples containing no added iron. Generally, the value of each oxidative index increased with (1) an increase in temperature, (2) an increase in heating time, and/or (3) an increase in iron. The results demonstrate that low concentrations of iron will substantially increase the rate of oxidation for vegetable oil samples heated to temperatures of 120 degrees C to 200 degrees C. PMID:15769140

Coscione, Aline R; Artz, William E

2005-03-23

372

Photoelectro-Fenton mineralization of phenol through optimization of ferrous regeneration.  

PubMed

The degradation of phenol in acidic solution at pH3 has been investigated under various photo- and electrochemical conditions. A laboratory-scale reactor on which were mounted net electrodes (RuO2/IrO2-coated Ti anodes (DSA) and stainless steel cathodes) and 254爊m UV lamps was established to effectively reduce ferric reagents. The experimental results of the photoelectron-chemical reaction suggested that the current efficiency of reducing ferric ion was improved by increasing the number of electrodes used, and the UV lamps were important to inducing the reduction of ferric carboxylates, which were the major intermediates that were formed upon a particular degree of phenol oxidation. Accordingly, the addition of an initial concentration of 400爌pm ferrous salt and 10,200爌pm hydrogen peroxide (in a continuous mode) resulted in the removal of over 92% of TOC (initial phenol?=?2,000爌pm, TOC?=?1,532爌pm) by 4爃 of the photoelectro-Fenton and the sequential 2爃 of the photo-Fenton processes. HPLC was utilized to monitor the formation of aromatic and carboxylate byproducts, and revealed that the aid of photo irradiation eliminated most of the oxalate residue from the final solution, which would have contributed to the 25% of the TOC that was inactive in the electrolytic system. PMID:23589255

Shih, Yu-Jen; Su, Hsiao-Ting; Huang, Yao-Hui

2013-04-16

373

Role of ferrous ions in synthetic cobaltous sulfide leaching of Thiobacillus ferrooxidans  

SciTech Connect

Microbiological leaching of synthetic cobaltous sulfide (CoS) was investigated with a pure strain of Thiobacillus ferrooxidans. The strain could not grow on CoS-salts medium in the absence of ferrous ions (Fe/sup 2 +/). However, in CoS-salts medium supplemented with 18 mM Fe/sup 2 +/, the strain utilized both Fe/sup 2 +/ and the sulfur moiety in CoS for growth, resulting in an enhanced solubilization of Co/sup 2 +/. Cell growth on sulfur-salts medium was strongly inhibited by Co/sup 2 +/, and this inhibition was completely protected by Fe/sup 2 +/. Cobalt-resistant cells, obtained by subculturing the strain in medium supplemented with both Fe/sup 2 +/ and Co/sup 2 +/, brought a marked decrease in the amount of Fe/sup 2 +/ absolutely required for cell growth on CoS-salts medium. As one mechanism of protection by Fe/sup 2 +/, it is proposed that the strain utilizes one part of Fe/sup 2 +/ externally added to CoS-salts medium to synthesize the cobalt-resistant system. Since a similar protective effect by Fe/sup 2 +/ was also observed for cell inhibition by stannous, nickel, zinc, silver, and mercuric ions, a new role of Fe/sup 2 +/ in bacterial leaching in T. ferrooxidans is proposed. 21 references, 8 figures, 1 table.

Sugio, T.; Domatsu, C.; Tano, T.; Imai, K.

1984-09-01

374

Ferrous iron mediated oxidation of arachidonic acid: studies employing nitroblue tetrazolium (NBT).  

PubMed

The oxidation of arachidonic acid by ferrous sulfate provides a useful model to study the role of iron in lipid oxidation reactions. We have employed nitroblue tetrazolium (NBT) in the present investigation to evaluate the mechanism of this reaction. In the presence of arachidonic acid, Fe +++, and O2, the yellow dye NBT was rapidly reduced to the blue form, NBTH2. The molar ratio of arachidonic acid to Fe++ in this rapid reaction was 1:1, showing an interaction of one fatty acid molecule per iron molecule. Approximately one molecule of NBT was reduced per four molecules of arachidonic acid and Fe++. Reduction of NBT was accompanied by oxidation of Fe++ to Fe+++, suggesting the transfer of four electrons from the Fe++ to NBT to reduce the dye. Arachidonic acid was found to be unchanged when extracted at the end of the reaction, indicating formation of a complex that could dissociate leaving intact arachidonic acid. Evidence for the presence of such a complex which slowly dissociates during the reaction was obtained after longer incubations with small amounts of arachidonic acid. NBT reduction was not inhibited by agents which hydrolyze superoxide, by catalase or by agents which trap hydroxy radicals. We, therefore, propose a model in which NBT traps a radical generated on the arachidonic acid molecule. The proposed model suggests mechanisms for other fatty acid oxidation reactions such as prostaglandin and hydroperoxy fatty acid synthesis. PMID:715068

Peterson, D A; Gerrard, J M; Rao, G H; Krick, T P; White, J G

1978-10-01

375

Efficacy, Tolerability, and Acceptability of Iron Hydroxide Polymaltose Complex versus Ferrous Sulfate: A Randomized Trial in Pediatric Patients with Iron Deficiency Anemia  

PubMed Central

Iron polymaltose complex (IPC) offers similar efficacy with superior tolerability to ferrous sulfate in adults, but randomized trials in children are rare. In a prospective, open-label, 4-month study, 103 children aged >6 months with iron deficiency anemia (IDA) were randomized to IPC once daily or ferrous sulfate twice daily, (both 5?mg iron/kg/day). Mean increases in Hb to months 1 and 4 with IPC were 1.2 0.9?g/dL and 2.3 1.3?g/dL, respectively, (both P = 0.001 versus baseline) and 1.8 1.7?g/dL and 3.0 2.3?g/dL with ferrous sulfate (both P = 0.001 versus baseline) (n.s. between groups). Gastrointestinal adverse events occurred in 26.9% and 50.9% of IPC and ferrous sulfate patients, respectively (P = 0.012). Mean acceptability score at month 4 was superior with IPC versus ferrous sulfate (1.63 0.56 versus 2.14 0.75, P = 0.001). Efficacy was comparable with IPC and ferrous sulfate over a four-month period in children with IDA, but IPC was associated with fewer gastrointestinal adverse events and better treatment acceptability.

Yasa, Beril; Agaoglu, Leyla; Unuvar, Emin

2011-01-01

376

Ferrous iron oxidation by sulfur-oxidizing Acidithiobacillus ferrooxidans and analysis of the process at the levels of transcription and protein synthesis.  

PubMed

In contrast to iron-oxidizing Acidithiobacillus ferrooxidans, A. ferrooxidans from a stationary phase elemental sulfur-oxidizing culture exhibited a lag phase in pyrite oxidation, which is similar to its behaviour during ferrous iron oxidation. The ability of elemental sulfur-oxidizing A. ferrooxidans to immediately oxidize ferrous iron or pyrite without a lag phase was only observed in bacteria obtained from growing cultures with elemental sulfur. However, these cultures that shifted to ferrous iron oxidation showed a low rate of ferrous iron oxidation while no growth was observed. Two-dimensional gel electrophoresis was used for a quantitative proteomic analysis of the adaptation process when bacteria were switched from elemental sulfur to ferrous iron. A comparison of total cell lysates revealed 39 proteins whose increase or decrease in abundance was related to this phenotypic switching. However, only a few proteins were closely related to iron and sulfur metabolism. Reverse-transcription quantitative PCR was used to further characterize the bacterial adaptation process. The expression profiles of selected genes primarily involved in the ferrous iron oxidation indicated that phenotypic switching is a complex process that includes the activation of genes encoding a membrane protein, maturation proteins, electron transport proteins and their regulators. PMID:23291738

Kucera, Jiri; Bouchal, Pavel; Lochman, Jan; Potesil, David; Janiczek, Oldrich; Zdrahal, Zbynek; Mandl, Martin

2013-01-05

377

The development of chelate metal complexes as an organic electroluminescent material  

Microsoft Academic Search

The chelate metal complexes, such as tris(8-hydroxyquinolinate)aluminum (Alq3), have excellent electroluminescent (EL) properties. Several chelate metal complexes were developed and the experimental rule of molecular design for use in an organic EL device was found. When the chelate metal complex has the structure of an inner complex sell, the EL device is fabricated by conventional vacuum-vapor deposition. This rule was

Yuji Hamada

1997-01-01

378

Plasma membrane ferric reductase activity of iron-limited algal cells is inhibited by ferric chelators  

Microsoft Academic Search

Iron-limited cells of the green alga Chlorella kesslerii use a reductive mechanism to acquire Fe(III) from the extracellular environment, in which a plasma membrane ferric reductase\\u000a reduces Fe(III)-chelates to Fe(II), which is subsequently taken up by the cell. Previous work has demonstrated that synthetic\\u000a chelators both support ferric reductase activity (when supplied as Fe(III)-chelates) and inhibit ferric reductase. In the

Mathew B. Sonier; Harold G. Weger

2010-01-01

379

Timing and rate of iron chelate application to correct chlorosis of peanut  

Microsoft Academic Search

The timing and rate of application of iron (Fe) chelates (seques?trene 138 Fe) to correct Fe chlorosis of peanut grown on calcareous soils was studied for three seasons (198587) in seven experiments. It was found that the biological yield of peanut increased up to the highest rate of chelate used (8 g\\/m). However, under the existing prices of the chelate

I. Papastylianou

1993-01-01

380

THE THERMAL DECOMPOSITION OF THE 5,7-DIHALO-8QUINOLINOL RARE EARTH METAL CHELATES  

Microsoft Academic Search

S>The thermal decomposition of the 5,7-dichloro-, 5,7dibromo- and 5,7-; diiodo-8-quinolinol chelates of La, Ce, Pr, Nd, Sm, and Y was investigated on the ; thermobalance. The chelates decomposed in the temperature range from 65 to 125 ; deg C while the oxide levels were obtained from 395 to 805 deg C. Although the ; chelate thermal stability temperatures varied little

W Wendlandt

1957-01-01

381

Chelating Tendencies of N,N'-Ethylenebis-[2-(o-Hydroxyphenyl)] Glycine  

Microsoft Academic Search

RECENT investigations of a wide variety of chelate compounds as carriers of ferric ions in plant nutrition showed the ferric chelate of N,N'-ethylenebis-[2-(o-hydroxyphenyl)] glycine to be a very effective iron carrier in biological systems. Because of the remarkable properties of this new chelating agent, investigation of its affinity for ferric ions and other metal ions seemed desirable. The structure of

H. H. Freedman; A. E. Frost; S. J. WESTERBACK; A. E. MARTELL

1957-01-01

382

Zinc Chelation Reduces Hippocampal Neurogenesis after Pilocarpine-Induced Seizure  

PubMed Central

Several studies have shown that epileptic seizures increase hippocampal neurogenesis in the adult. However, the mechanism underlying increased neurogenesis after seizures remains largely unknown. Neurogenesis occurs in the subgranular zone (SGZ) of the hippocampus in the adult brain, although an understanding of why it actively occurs in this region has remained elusive. A high level of vesicular zinc is localized in the presynaptic terminals of the SGZ. Previously, we demonstrated that a possible correlation may exist between synaptic zinc localization and high rates of neurogenesis in this area after hypoglycemia. Using a lithium-pilocarpine model, we tested our hypothesis that zinc plays a key role in modulating hippocampal neurogenesis after seizure. Then, we injected the zinc chelator, clioquinol (CQ, 30 mg/kg), into the intraperitoneal space to reduce brain zinc availability. Neuronal death was detected with Fluoro Jade-B and NeuN staining to determine whether CQ has neuroprotective effects after seizure. The total number of degenerating and live neurons was similar in vehicle and in CQ treated rats at 1 week after seizure. Neurogenesis was evaluated using BrdU, Ki67 and doublecortin (DCX) immunostaining 1 week after seizure. The number of BrdU, Ki67 and DCX positive cell was increased after seizure. However, the number of BrdU, Ki67 and DCX positive cells was significantly decreased by CQ treatment. Intracellular zinc chelator, N,N,N0,N-Tetrakis (2-pyridylmethyl) ethylenediamine (TPEN), also reduced seizure-induced neurogenesis in the hippocampus. The present study shows that zinc chelation does not prevent neurodegeneration but does reduce seizure-induced progenitor cell proliferation and neurogenesis. Therefore, this study suggests that zinc has an essential role for modulating hippocampal neurogenesis after seizure.

Kim, Jin Hee; Jang, Bong Geom; Choi, Bo Young; Kwon, Lyo Min; Sohn, Min; Song, Hong Ki; Suh, Sang Won

2012-01-01

383

Organoosmium complexes of imidazole-containing chelate acceptor ligands  

Microsoft Academic Search

The complexes [(L)Os(?6-Cym)Cl](PF6), Cym=p-cymene and L=bis(1-methylimidazol-2-yl)ketone (bik) or bis(1-methylimidazol-2-yl)glyoxal (big), were obtained and characterized with respect to spectroscopy, crystal structure (big complex) and (spectro)electrochemical behaviour at variable temperatures. DFT calculations confirm the structure of [(big)Os(?6-Cym)Cl]+ with imidazolyl-N-bonded OsII in a boat-shaped seven-membered chelate ring with small N朞s朜 angles (<84). Reduction of this compound proceeds reversibly to a neutral complex of

Orkan Sarper; Biprajit Sarkar; Jan Fiedler; Falk Lissner; Wolfgang Kaim

2010-01-01

384

The lead-chelating effects of substituted dithiocarbamates.  

PubMed

The effectiveness of certain substituted dithiocarbamates in mobilizing lead from preexposed rats was investigated. The animals received 10 mg Pb/kg/day, intragastrically, for 8 weeks and were treated thereafter with 400 mumol/kg, intraperitoneally, of morpholine dithiocarbamate, tetraammonium ethylenediamine diacetic acid dithiocarbamate (EDDTC), ammonium diethanolamine dithiocarbamate (ADDTC), sodium diethyldithiocarbamate, N-benzyl-D-glucamine dithiocarbamate (NBGDTC), or dimercaptosuccinic acid, daily for 5 days. All the chelating agents were effective in lowering the hepatic and renal burden of Pb. ADDTC, EDDTC, and NBGDTC were also able to lower the long bone Pb content. The lowering of Pb burden had no relationship to restoration of Pb-induced hematopoietic alterations. The relatively lower lipophilicity of substituted dithiocarbamates, owing to the presence of hydrophilic groups, seems to be advantageous in preventing passage of metal chelate into the brain. None of the substituted dithiocarbamates caused excessive excretion of urinary Cu and Zn. ADDTC and EDDTC appear to be promising in the management of Pb poisoning. PMID:2252549

Tandon, S K; Hashmi, N S; Kachru, D N

1990-09-01

385

Branched polymeric media: boron-chelating resins from hyperbranched polyethylenimine.  

PubMed

Extraction of boron from aqueous solutions using selective resins is important in a variety of applications including desalination, ultrapure water production, and nuclear power generation. Today's commercial boron-selective resins are exclusively prepared by functionalization of styrene-divinylbenzene (STY-DVB) beads with N-methylglucamine to produce resins with boron-chelating groups. However, such boron-selective resins have a limited binding capacity with a maximum free base content of 0.7 eq/L, which corresponds to a sorption capacity of 1.16 0.03 mMol/g in aqueous solutions with equilibrium boron concentration of ?70 mM. In this article, we describe the synthesis and characterization of a new resin that can selectively extract boron from aqueous solutions. We show that branched polyethylenimine (PEI) beads obtained from an inverse suspension process can be reacted with glucono-1,5-D-lactone to afford a resin consisting of spherical beads with high density of boron-chelating groups. This resin has a sorption capacity of 1.93 0.04 mMol/g in aqueous solution with equilibrium boron concentration of ?70 mM, which is 66% percent larger than that of standard commercial STY-DVB resins. Our new boron-selective resin also shows excellent regeneration efficiency using a standard acid wash with a 1.0 M HCl solution followed by neutralization with a 0.1 M NaOH solution. PMID:22827255

Mishra, Himanshu; Yu, Changjun; Chen, Dennis P; Goddard, William A; Dalleska, Nathan F; Hoffmann, Michael R; Diallo, Mamadou S

2012-08-10

386

Structural analysis of metastable pseudobrookite ferrous titanium oxides with neutron diffraction and Mossbauer spectroscopy  

SciTech Connect

Four synthetic iron titanium oxides with the pseudobrookite (AB{sub 2}O{sub 5}, Cmcm, Z = 4) structure have been prepared and characterized by neutron diffraction and zero-field, natural abundance {sup 57}Fe Mossbauer effect spectroscopy (MES). The combination of the element specificity of MES with the different neutron scattering lengths of Ti and Fe ({minus}0.33 and 0.95 {times} 10{sup {minus}12} cm, respectively) offers a unique opportunity to distinguish between cation distributions on the two (A and B) sites. Two of the samples have been prepared in low temperature experiments (quenched from 1,200{degree}C) and have the stoichiometry FeTi{sub 2}O{sub 5}, and Fe{sub .6}Mg{sub .6}Ti{sub 1.8}O{sub 5}. The third and fourth samples are commercial iron titanium oxides prepared by the reduction of ilmenite ore with carbon above 1,700{degree}C. The stoichiometries of these samples are Mn{sub 0.05}Fe{sub 0.33}Ti{sub 2.52}O{sub 5} and Fe{sub .33}Mg{sub .31}Ti{sub 2.36}O{sub 5}. Results from these experiments indicate that for each of these samples the B site is predominantly (> 65%) occupied by Ti, while the A site contains a mixture of Ti, Fe, and/or Mg. However, only at higher temperatures (> 1,700{degree}C) is the B site devoid of ferrous cations.

Teller, R.G.; Antonio, M.R. (BP Research, Cleveland, OH (USA)); Grau, A.E.; Gueguin, M. (QIT-Fer et Titane Inc., Sorel, Quebec (Canada)); Kostiner, E. (Univ. of Connecticut, Storrs (USA))

1990-10-01

387

Effect of saccharide additives on response of ferrous-agarose-xylenol orange radiotherapy gel dosimeters.  

PubMed

Glucose, sucrose, starch, and locust bean gum have been used as additives to the ferrous-agarose-xylenol orange (FAX) gel dosimeter. The saccharide enhanced dosimeters were found to have a higher dose sensitivity over a standard FAX gel as measured by both optical density change and magnetic resonance imaging (MRI). With optical density measurement, OD-dose sensitivity increases were up to 55% for glucose, 122% for sucrose and 43% for starch, while locust bean gum did not give a consistent response. With MRI, R1-dose sensitivity increases were up to 178% with sucrose addition. The FAX gel with sucrose was studied in greatest detail. The OD-dose sensitivity dependence on cooling rate was reduced for the sucrose FAX gel over the standard FAX gel, which has significant implications for uniform dose sensitivity in large gel phantoms. The thermal oxidation rate in the sucrose FAX gel was up to 2.3 times higher than in the standard gel. The OD-dose sensitivity of oxygenated sucrose FAX gels was 4.3 times greater than standard FAX gels, while continued enhancement in OD-dose sensitivity with increased sucrose concentrations beyond 2.0 g/l was found only for the oxygenated sucrose FAX gels. Both the molar absorption coefficient of the ferric ion-xylenol orange complex at 543 nm and gel pH were not affected by the presence of sucrose, with the implication that the higher OD-dose sensitivity of gels with saccharides is due to increased chain reaction production of ferric ions. PMID:14528948

Healy, B J; Zahmatkesh, M H; Nitschke, K N; Baldock, C

2003-09-01

388

Phenazine-1-carboxylic acid promotes bacterial biofilm development via ferrous iron acquisition.  

PubMed

The opportunistic pathogen Pseudomonas aeruginosa forms biofilms, which render it more resistant to antimicrobial agents. Levels of iron in excess of what is required for planktonic growth have been shown to promote biofilm formation, and therapies that interfere with ferric iron [Fe(III)] uptake combined with antibiotics may help treat P. aeruginosa infections. However, use of these therapies presumes that iron is in the Fe(III) state in the context of infection. Here we report the ability of phenazine-1-carboxylic acid (PCA), a common phenazine made by all phenazine-producing pseudomonads, to help P. aeruginosa alleviate Fe(III) limitation by reducing Fe(III) to ferrous iron [Fe(II)]. In the presence of PCA, a P. aeruginosa mutant lacking the ability to produce the siderophores pyoverdine and pyochelin can still develop into a biofilm. As has been previously reported (P. K. Singh, M. R. Parsek, E. P. Greenberg, and M. J. Welsh, Nature 417:552-555, 2002), biofilm formation by the wild type is blocked by subinhibitory concentrations of the Fe(III)-binding innate-immunity protein conalbumin, but here we show that this blockage can be rescued by PCA. FeoB, an Fe(II) uptake protein, is required for PCA to enable this rescue. Unlike PCA, the phenazine pyocyanin (PYO) can facilitate biofilm formation via an iron-independent pathway. While siderophore-mediated Fe(III) uptake is undoubtedly important at early stages of infection, these results suggest that at later stages of infection, PCA present in infected tissues may shift the redox equilibrium between Fe(III) and Fe(II), thereby making iron more bioavailable. PMID:21602354

Wang, Yun; Wilks, Jessica C; Danhorn, Thomas; Ramos, Itzel; Croal, Laura; Newman, Dianne K

2011-05-20

389

Potassium-activated GTPase reaction in the G Protein-coupled ferrous iron transporter B.  

PubMed

FeoB is a prokaryotic membrane protein responsible for the import of ferrous iron (Fe(2+)). A defining feature of FeoB is that it includes an N-terminal 30-kDa soluble domain with GTPase activity, which is required for iron transport. However, the low intrinsic GTP hydrolysis rate of this domain appears to be too slow for FeoB either to function as a channel or to possess an active Fe(2+) membrane transport mechanism. Here, we present crystal structures of the soluble domain of FeoB from Streptococcus thermophilus in complex with GDP and with the GTP analogue derivative 2'-(or -3')-O-(N-methylanthraniloyl)-beta,gamma-imidoguanosine 5'-triphosphate (mant-GMPPNP). Unlike recent structures of the G protein domain, the mant-GMPPNP-bound structure shows clearly resolved, active conformations of the critical Switch motifs. Importantly, biochemical analyses demonstrate that the GTPase activity of FeoB is activated by K(+), which leads to a 20-fold acceleration in its hydrolysis rate. Analysis of the structure identified a conserved asparagine residue likely to be involved in K(+) coordination, and mutation of this residue abolished K(+)-dependent activation. We suggest that this, together with a second asparagine residue that we show is critical for the structure of the Switch I loop, allows the prediction of K(+)-dependent activation in G proteins. In addition, the accelerated hydrolysis rate opens up the possibility that FeoB might indeed function as an active transporter. PMID:20220129

Ash, Miriam-Rose; Guilfoyle, Amy; Clarke, Ronald J; Guss, J Mitchell; Maher, Megan J; Jormakka, Mika

2010-03-10

390

Phenazine-1-Carboxylic Acid Promotes Bacterial Biofilm Development via Ferrous Iron Acquisition?  

PubMed Central

The opportunistic pathogen Pseudomonas aeruginosa forms biofilms, which render it more resistant to antimicrobial agents. Levels of iron in excess of what is required for planktonic growth have been shown to promote biofilm formation, and therapies that interfere with ferric iron [Fe(III)] uptake combined with antibiotics may help treat P. aeruginosa infections. However, use of these therapies presumes that iron is in the Fe(III) state in the context of infection. Here we report the ability of phenazine-1-carboxylic acid (PCA), a common phenazine made by all phenazine-producing pseudomonads, to help P. aeruginosa alleviate Fe(III) limitation by reducing Fe(III) to ferrous iron [Fe(II)]. In the presence of PCA, a P. aeruginosa mutant lacking the ability to produce the siderophores pyoverdine and pyochelin can still develop into a biofilm. As has been previously reported (P. K. Singh, M. R. Parsek, E. P. Greenberg, and M. J. Welsh, Nature 417:552-555, 2002), biofilm formation by the wild type is blocked by subinhibitory concentrations of the Fe(III)-binding innate-immunity protein conalbumin, but here we show that this blockage can be rescued by PCA. FeoB, an Fe(II) uptake protein, is required for PCA to enable this rescue. Unlike PCA, the phenazine pyocyanin (PYO) can facilitate biofilm formation via an iron-independent pathway. While siderophore-mediated Fe(III) uptake is undoubtedly important at early stages of infection, these results suggest that at later stages of infection, PCA present in infected tissues may shift the redox equilibrium between Fe(III) and Fe(II), thereby making iron more bioavailable.

Wang, Yun; Wilks, Jessica C.; Danhorn, Thomas; Ramos, Itzel; Croal, Laura; Newman, Dianne K.

2011-01-01

391

A novel approach to oral iron delivery using ferrous sulphate loaded solid lipid nanoparticles.  

PubMed

Iron (Fe) loaded solid lipid nanoparticles (SLN's) were formulated using stearic acid and iron absorption was evaluated in vitro using the cell line Caco-2 with intracellular ferritin formation as a marker of iron absorption. Iron loading was optimised at 1% Fe (w/w) lipid since an inverse relation was observed between initial iron concentration and SLN iron incorporation efficiency. Chitosan (Chi) was included to prepare chitosan coated SLN's. Particle size analysis revealed a sub-micron size range (300.331.75nm to 495.180.42nm), with chitosan containing particles having the largest dimensions. As expected, chitosan (0.1%, 0.2% and 0.4% w/v) conferred a net positive charge on the particle surface in a concentration dependent manner. For iron absorption experiments equal doses of Fe (20?M) from selected formulations (SLN-FeA and SLN-Fe-ChiB) were added to Caco-2 cells and intracellular ferritin protein concentrations determined. Caco-2 iron absorption from SLN-FeA (583.9840.83ng/mg cell protein) and chitosan containing SLN-Fe-ChiB (642.7729.37ng/mg cell protein) were 13.42% and 24.9% greater than that from ferrous sulphate (FeSO4) reference (514.6620.43ng/mg cell protein) (p?0.05). We demonstrate for the first time preparation, characterisation and superior iron absorption in vitro from SLN's, suggesting the potential of these formulations as a novel system for oral iron delivery. PMID:24012860

Zariwala, M Gulrez; Elsaid, Naba; Jackson, Timothy L; Corral L髉ez, Francisco; Farnaud, Sebastien; Somavarapu, Satyanarayana; Renshaw, Derek

2013-09-05

392

Metal chelate catalysts for fuel cells. Annual report Jul 80-Jun 81  

Microsoft Academic Search

A variety of metal chelates were synthesized and evaluated for their activity as oxygen cathode electrocatalysts in strong acidic electrolytes. It was found that cobalt tetraazaanulene (CoTAA) and iron phthalocyanine (FePc) exhibit the best activity of all the metal chelates synthesized, but have very limited stability. The proposed solution to this problem is the synthesis of polymeric forms of these

R. Darby; R. White; M. Yamana; M. Tsutsui

1981-01-01

393

Removal of heavy metals from a chelated solution with electrolytic foam separation  

SciTech Connect

An experimental study was conducted on the chelation and electrolytic foam separation of trace amounts of copper, nickel, zinc, and cadmium from a synthetic chelated metal wastewater. Sodium ethylenediaminetetraacetate (EDTA), citrate, sodium diethyldithiocarbamate (NDDTC), and potassium ethyl xanthate (KEtX) were used with sodium dodecylsulfate (NaDS) as a foam-producing agent. Experimental results from an electrolytic foam separation process showed that chelating agents NDDTC and KEtX, due to their higher chelating strength and hydrophobic property, can efficiently separate Cu and Ni from chelated compounds (Cu, Ni/EDTA, and Cu, Ni/citrate). In a Cu-EDTA-NDDTC system with a chelating agent/metal ratio of 4, the residual Cu(II) concentration is 0.7 mg/L. The effects of chelating agent types and different chelating agents concentrations on the removal of metal ions were studied. The effect of NaDS dosage on flotation behavior and the efficiency of metal removal were also investigated.

Min-Her Leu; Juu-En Chang; Ming-Sheng Ko [National Cheng Kung Univ., Taiwan (China)

1994-11-01

394

Comparative Effects of Several Chelating Agents on the Toxicity, Distribution and Excretion of Aluminium  

Microsoft Academic Search

The relative efficacy of citric, malic, malonic, oxalic and succinic acids, and deferoxamine mesylate (DFOA) on the toxicity, distribution and excretion in mice exposed to aluminium were compared. Chelating agents were administered intraperitoneally at a dose equal to one-fourth of their respective LD50. To determine the effect of the various chelators on the toxicity of aluminium, various doses of aluminium

J. L. Domingo; M. G髆ez; J. M. Llobet; J. Corbella

1988-01-01

395

Rates of Metal Electrodeposition from Aqueous Solutions in the Presence of Chelating Agents  

Microsoft Academic Search

The rates of Cu deposition from aqueous solutions containing chelating agents, such as citric acid, nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA), in an electrochemical membrane cell were measured. An equimolar solution of chelating agents and metals was examined. The iridium oxide and Pt coated on titanium electrodes were used as the anode and cathode, respectively. The cation-exchange membrane Neosepta

RUEY-SHIN JUANG; LI-CHUN LIN

2000-01-01

396

Preparation and characterization of poly(amidoxime) chelating resin from polyacrylonitrile grafted sago starch  

Microsoft Academic Search

The preparation of a chelating ion-exchange resin containing amidoxime functional group was carried out by polyacrylonitrile (PAN) grafted sago starch. The PAN grafted copolymer was obtained by free-radical initiating process using ceric ammonium nitrate as an initiator. Conversion of nitrile groups of the grafted copolymer into the amidoxime was carried out by treatment with hydroxylamine under alkaline solution. The chelating

M. R. Lutfor; Sidik Silong; M. Z. Ab Rahman; Mansor Ahmad; Jelas Haron

2000-01-01

397

PCTH: a novel orally active chelator of the aroylhydrazone class that induces iron excretion from mice  

Microsoft Academic Search

?-Thalassaemia major is an inherited blood disorder which is complicated by repeated blood transfusion and excessive gastrointestinal iron (Fe) absorption, which leads to toxic Fe overload. Current treatment using the chelator, desferrioxamine (DFO), is expensive and cumbersome since the drug requires long subcutaneous infusions and it is not orally active. A novel chelator, 2-pyridylcarboxaldehyde 2-thiophenecarboxyl hydrazone (PCTH), was recently designed

C. S. M. Wong; J. C. Kwok; D. R. Richardson

2004-01-01

398

Development of novel aroylhydrazone ligands for iron chelation therapy: 2-Pyridylcarboxaldehyde isonicotinoyl hydrazone analogs  

Microsoft Academic Search

Previous studies have demonstrated that aroylhydrazone iron (Fe) chelators of the pyridoxal isonicotinoyl hydrazone (PIH) class have high Fe chelation efficacy both in vitro and in vivo. Depending on their design, these drugs may have potential as agents for the treatment of Fe overload disease or cancer. Considering the high potential of this class of ligands, we have synthesized seven

Erika Becker; Des R Richardson

1999-01-01

399

Association of antigens to ISCOMATRIX adjuvant using metal chelation leads to improved CTL responses  

Microsoft Academic Search

The association of antigen with ISCOMATRIX adjuvant has been shown to be important for the optimal induction of cytotoxic T lymphocyte (CTL) responses. Here, we describe a simple broadly applicable method for associating recombinant proteins with hexa-histidine tags to ISCOMATRIX adjuvant utilising metal-affinity chelating interactions. The metal chelation binding step can be performed in a wide range of buffers, including

Jim Malliaros; Charles Quinn; Frances H. Arnold; Martin J. Pearse; Debbie P. Drane; Trina J. Stewart; Roderick I. Macfarlan

2004-01-01

400

The effect of some polymeric metal chelates on the flammability properties of polypropylene  

Microsoft Academic Search

A copolymer of acrylonitrile with N-(4-chlorophenyl)acrylamide was prepared and was reacted with ferric chloride, cobalt acetate and zinc acetate to obtain the corresponding metal chelates. The metal chelates were used with 16% kaolin as flame retardants for polypropylene. The flammability properties of the various polypropylene compositions were evaluated by thermogravimetric analysis (TGA) and cone calorimetry. It was found that the

M. A. Hassan; A. B. Shehata

2004-01-01

401

Enhancing Potentially Plant-Available Lead Concentrations in Contaminated Residential Soils Using a Biodegradable Chelating Agent  

Microsoft Academic Search

Chelation of heavy metals is an important factor in enhancing metal solubility and, hence, metal availability to plants to promote phytoremediation. In the present study, we compared the effects of application of a biodegradable chelating agent, namely, ethylenediaminedisuccinic acid (EDDS) on enhancing plant available form of lead (Pb) in Pb-based paint contaminated residential soils compared to that of a more

S. Andra; R. Datta; D. Sarkar; S. Saminathan

2007-01-01

402

Prevention of oxidant-induced cell death by lysosomotropic iron chelators  

Microsoft Academic Search

Intralysosomal iron powerfully synergizes oxidant-induced cellular damage. The iron chelator, desferrioxamine (DFO), protects cultured cells against oxidant challenge but pharmacologically effective concentrations of this drug cannot readily be achieved in vivo. DFO localizes almost exclusively within the lysosomes following endocytic uptake, suggesting that truly lysosomotropic chelators might be even more effective. We hypothesized that an amine derivative of ?-lipoamide (LM),

Hans L Persson; Zhengquan Yu; Oren Tirosh; John W Eaton; Ulf T Brunk

2003-01-01

403

Fluorinated Paramagnetic Chelates as Potential Multi-chromic 19F Tracer Agents  

PubMed Central

A class of potential multi-chromic 19F imaging tracers is made by pairing metal ions with a fluorinated chelator. All fluorinated metal chelates emit a single 19F signal. Paramagnetic metal ions shifted the 19F signal frequency and made the 19F relaxation rates insensitive toward local chemical environment.

Jiang, Zhong-Xing; Feng, Yue

2012-01-01

404

Fluoride ion recognition by chelating and cationic boranes.  

PubMed

Because of the ubiquity of fluoride ions and their potential toxicity at high doses, researchers would like to design receptors that selectively detect this anion. Fluoride is found in drinking water, toothpaste, and osteoporosis drugs. In addition, fluoride ions also can be detected as an indicator of uranium enrichment (via hydrolysis of UF(6)) or of the chemical warfare agent sarin, which releases the ion upon hydrolysis. However, because of its high hydration enthalpy, the fluoride anion is one of the most challenging targets for anion recognition. Among the various recognition strategies that are available, researchers have focused a great deal of attention on Lewis acidic boron compounds. These molecules typically interact with fluoride anions to form the corresponding fluoroborate species. In the case of simple triarylboranes, the fluoroborates are formed in organic solvents but not in water. To overcome this limitation, this Account examines various methods we have pursued to increase the fluoride-binding properties of boron-based receptors. We first considered the use of bifunctional boranes, which chelate the fluoride anion, such as 1,8-diborylnaphthalenes or heteronuclear 1-boryl-8-mercurio-naphthalenes. In these molecules, the neighboring Lewis acidic atoms can cooperatively interact with the anionic guest. Although the fluoride binding constants of the bifunctional compounds exceed those of neutral monofunctional boranes by several orders of magnitude, the incompatibility of these systems with aqueous media limits their utility. More recently, we have examined simple triarylboranes whose ligands are decorated by cationic ammonium or phosphonium groups. These cationic groups increase the electrophilic character of these boranes, and unlike their neutral analogs, they are able to complex fluoride in aqueous media. We have also considered cationic boranes, which form chelate complexes with fluoride anions. Our work demonstrates that Coulombic and chelate effects are additive and can be combined to boost the anion affinity of Lewis acidic hosts. The boron compounds that we have investigated present a set of photophysical and electrochemical properties that can serve to signal the fluoride-binding event. We can also apply this approach to cyanide complexation and are continuing our investigations in that area. PMID:19140747

Hudnall, Todd W; Chiu, Ching-Wen; Gabba, Fran鏾is P

2009-02-17

405

Role of pH in metal adsorption from aqueous solutions containing chelating agents on chitosan  

SciTech Connect

The role of pH in adsorption of Cu(II) from aqueous solutions containing chelating agents on chitosan was emphasized. Four chelating agents including ethylenediaminetetraacetic acid (EDTA), citric acid, tartaric acid, and sodium gluconate were used. It was shown that the adsorption ability of Cu(II) on chitosan from its chelated solutions varied significantly with pH variations. The competition between coordination of Cu(II) with unprotonated chitosan and electrostatic interaction of the Cu(II) chelates with protonated chitosan took place because of the change in solution pH during adsorption. The maximum adsorption capacity was obtained within each optimal pH range determined from titration curves of the chelated solutions. Coordination of Cu(II) with the unprotonated chitosan was found to dominate at pH below such an optimal pH value.

Wu, F.C.; Tseng, R.L. [Lien Ho Junior Coll. of Technology, Maio-Li (Taiwan, Province of China). Dept. of Chemical Engineering and Environmental Engineering; Juang, R.S. [Yuan Ze Univ., Chung-li (Taiwan, Province of China)

1999-01-01

406

Major role for FeoB in Campylobacter jejuni ferrous iron acquisition, gut colonization, and intracellular survival.  

PubMed

To assess the importance of ferrous iron acquisition in Campylobacter physiology and pathogenesis, we disrupted and characterized the Fe2+ iron transporter, FeoB, in Campylobacter jejuni NCTC 11168, 81-176, and ATCC 43431. The feoB mutant was significantly affected in its ability to transport 55Fe2+. It accumulated half the amount of iron than the wild-type strain during growth in an iron-containing medium. The intracellular iron of the feoB mutant was localized in the periplasmic space versus the cytoplasm for the wild-type strain. These results indicate that the feoB gene of C. jejuni encodes a functional ferrous iron transport system. Reverse transcriptase PCR analysis revealed the cotranscription of feoB and Cj1397, which encodes a homolog of Escherichia coli feoA. C. jejuni 81-176 feoB mutants exhibited reduced ability to persist in human INT-407 embryonic intestinal cells and porcine IPEC-1 small intestinal epithelial cells compared to the wild type. C. jejuni NCTC 11168 feoB mutant was outcompeted by the wild type for colonization and/or survival in the rabbit ileal loop. The feoB mutants of the three C. jejuni strains were significantly affected in their ability to colonize the chick cecum. And finally, the three feoB mutants were outcompeted by their respective wild-type strains for infection of the intestinal tracts of colostrum-deprived piglets. Taken together, these results demonstrate that FeoB-mediated ferrous iron acquisition contributes significantly to colonization of the gastrointestinal tract during both commensal and infectious relationship, and thus it plays an important role in Campylobacter pathogenesis. PMID:16988218

Naikare, Hemant; Palyada, Kiran; Panciera, Roger; Marlow, Denver; Stintzi, Alain

2006-10-01

407

Structural analysis of isomeric europium(III) chelates of NB-DOTMA.  

PubMed

Water exchange in lanthanide(III) chelates is a key parameter in developing more effective MRI contrast agents. Our own efforts to optimize water exchange have focused on isolating single coordination geometries of LnDOTA-type chelates (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate.) This isolation may be achieved by appropriately substituting the ligand framework to freeze-out the conformational exchange processes that interconvert coordination geometries. When a single nitrobenzyl substituent is used to "lock" the conformation of the macrocyclic ring, two regioisomeric chelates may be produced; the substituent may be alternatively located on the corner or the side of the ring. Here, we unambiguously demonstrate this regioisomerism by examining the COSY spectra of some conformationally locked Eu(3+) chelates. This exercise also demonstrated that diastereoisomeric chelates arising from racemization of chiral centers during the ligand synthesis, recently discounted as the origin of multiple isomeric chelates, can be produced and isolated. Furthermore, these COSY data revealed several through space NOE correlations that afford a great deal of information about the conformation of the nitrobenzyl substituent. In those isomers in which the substituent is located on the corner of the ring, the nitrobenzyl group is oriented approximately perpendicular to the plane of the macrocycle pointing upward and away from the chelate. In contrast, when the substituent is located on the side of the ring, the nitrobenzyl group is oriented approximately in plane with the macrocycle, pointing along the side of the chelate. Because the main purpose of the nitro group is to facilitate chemical modification and conjugation to biologically relevant molecules, these differences may have important consequences. Specifically, it seems likely that the same chelate may interact very differently with biological systems and molecules depending upon the regioisomer and therefore the orientation of the chelate relative to the biomolecule. PMID:22809081

Webber, Benjamin C; Woods, Mark

2012-07-18

408

Chemistry and biology of the copper chelator methanobactin  

PubMed Central

Methanotrophic bacteria, organisms that oxidize methane, produce a small copper chelating molecule called methanobactin (Mb). Mb binds Cu(I) with high affinity and is hypothesized to mediate copper acquisition from the environment. Recent advances in Mb characterization include revision of the chemical structure of Mb from Methylosinus trichosporium OB3b and further investigation of its biophysical properties. In addition, Mb production by several other methanotroph strains has been investigated and preliminary characterization suggests diversity in chemical composition. Initial clues into Mb biosynthesis have been obtained by identification of a putative precursor gene in the M. trichosporium OB3b genome. Finally, direct uptake of intact Mb into the cytoplasm of M. trichosporium OB3b cells has been demonstrated and studies of the transport mechanism have been initiated. Taken together, these advances represent significant progress and set the stage for exciting new research directions.

Kenney, Grace E.; Rosenzweig, Amy C.

2012-01-01

409

[Microbiological consequences of chelation of bivalent metal cations by nitroxoline].  

PubMed

The present work deals with the physico-chemical and microbiological investigations made in order to explain the role of divalent cations in the mechanism of the action of nitroxoline (NIT), an antibiotic used in the treatment of uncomplicated urinary tract infections. Preliminary studies reported that bacteriostatic and bactericidal activities of NIT on Escherichia coli strains are decreased in the presence of Mg2+ and Mn2+ but not with Ca2+. A spectrophotometric study, conducted in order to elucidate the interaction between metal ions and NIT, showed the formation of drug-metal ion complexes. In addition, we examined the relationships between the metal ions-chelating property of NIT and its effects on the decrease of the mannose sensitive hemagglutination titer and the production of siderophores from E. coli. The results suggested that these antimicrobial activities of NIT would also be due to the complexation of metal ions by this molecule. PMID:7824304

Pelletier, C; Prognon, P; Latrache, H; Villart, L; Bourlioux, P

1994-05-01

410

Comparison of 225actinium chelates: tissue distribution and radiotoxicity.  

PubMed

The biodistribution and tissue toxicity of intravenously administered 225-actinium (225Ac) complexed with acetate, ethylene diamine tetraacetic acid (EDTA), 1, 4, 7, 10, 13-pentaazacyclopentadecane-N, N', N", N"', N"-pentaacetic acid (PEPA), or the "a" isomer of cyclohexyl diethylenetriamine pentaacetic acid (CHX-DTPA), were examined. The percent of injected dose per organ and per gram of tissue for each chelate complex was determined. 225Ac-CHX-DTPA was evaluated further for radiotoxic effects. Mice receiving > or =185 kBq 225Ac-CHX-DTPA suffered 100% morbidity by 5 days and 100% mortality by 8 days postinjection, and all animals evaluated had significant organ damage. The in vivo instability of the 225Ac-CHX-DTPA complex likely allowed accumulation of free 225Ac in organs, which resulted in tissue pathology. PMID:10473198

Davis, I A; Glowienka, K A; Boll, R A; Deal, K A; Brechbiel, M W; Stabin, M; Bochsler, P N; Mirzadeh, S; Kennel, S J

1999-07-01

411

Iron chelation therapy in myelodysplastic syndromes: where do we stand?  

PubMed

Anemia leading to transfusion dependency (TD) and iron overload (IO) is commonly observed in patients with myelodysplastic syndromes (MDS). In MDS, TD and IO have been retrospectively associated with inferior survival and worse clinical outcomes, including cardiac, hepatic and endocrine dysfunction, and, in some analyses, with leukemic progression and infectious complications. Although suggested by retrospective analyses, clear prospective documentation of the beneficial effects of iron chelation therapy (ICT) on organ function and survival in MDS patients with TD and IO is currently lacking. Consequently, the role of ICT in MDS patients with TD and IO remains a very controversial aspect in the management of MDS. In this review, the authors summarize the current knowledge regarding IO in MDS and the role of ICT. PMID:23991926

Mitchell, Mhairi; Gore, Steven D; Zeidan, Amer M

2013-08-01

412

Molecular Models of EDTA and Other Chelating Agents  

NSDL National Science Digital Library

Deirdre Bell-Oudry presents a variation on an old theme in her paper on using an indirect EDTA titration for sulfate analysis (1). EDTA and (often loosely) related species are this month's Featured Molecules.EDTA is a hexaprotic acid (H6Y2+) having the pKa values given in the featured paper (1). Figure 1 shows a distribution diagram for the EDTA system (2). At the pH of normal waters, the predominant species have one or both of the nitrogen atoms protonated.Complexation, however, requires that both nitrogens be deprotonated and it is generally assumed that the form that complexes with metal ions is Y4−. Structures of several forms of EDTA are included in the molecule collection (Figure 2). These structures are quite flexible having many conformations that are readily accessible at room temperature.An introduction to EDTA chemistry leads to broader questions of metal ion chelation or sequestration. Related chelating agents included in the molecule collection are EGTA, DCTA, NTA, BAPTA, and DTPA. Molecular dynamics and Hartree-Fock calculations on BAPTA (Figure 2) confirm that many conformations, ranging from those with the phenyl rings parallel to one another, to more elongated forms, are essentially isoenergetic in room temperature aqueous solution (3).Also included in the molecule collection are several crown ethers, an isophore (nonactin), and a cryptand. These not only provide students with a glimpse of the types of molecules being employed for metal ion sequestration but open a wide range of topics of current research in a variety of areas of inorganic, industrial, environmental, and biological chemistry.

413

Potentials and drawbacks of chelate-enhanced phytoremediation of soils.  

PubMed

Chelate-enhanced phytoremediation has been proposed as an effective tool for the extraction of heavy metals from soils by plants. However, side-effects related to the addition of chelates, e.g. metal leaching and effects on soil micro-organisms, were usually neglected. Therefore, greenhouse and lysimeter studies were conducted to study the phytoremedation potential of EDGA and citric acid and to evaluate its effects on microbial activity and leaching of Cd, Zn Cu and Pb. Grass, lupine and yellow mustard were grown on a moderately polluted acid (pH 4.5) sandy soil that contained 2 mg kg(-1) Cd and 200 mg kg(-1) Zn. Citric acid appeared to be degraded microbially within a few days after addition which limited its potential for long-lasting remediation studies. EDGA enhanced metal solubility but plant uptake did not increase accordingly. The metal shoot:root ratio increased upon addition of EDGA but it also reduced the net shoot and root biomass production of both lupine and yellow mustard. Bacterial biomass was higher in both the citric and EDGA treated pots but bacterial activity remained unaffected. The number of microbivorous nematodes was greatly reduced upon addition of EDGA which was most likely related to the reduced biomass production and, to a smaller extent, to the changes in the composition of the available food. Furthermore, EDGA enhanced metal leaching in the lysimeter study which could lead to groundwater pollution. To prevent these unwanted side-effects, careful management of phytoremediation methods, therefore, seems necessary. PMID:11808546

R鰉kens, Paul; Bouwman, Lucas; Japenga, Jan; Draaisma, Cathrina

2002-01-01

414

Mechanistic basis for overcoming platinum resistance using copper chelating agents.  

PubMed

Platinum-based antitumor agents are widely used in cancer chemotherapy. Drug resistance is a major obstacle to the successful use of these agents because once drug resistance develops, other effective treatment options are limited. Recently, we conducted a clinical trial using a copper-lowering agent to overcome platinum drug resistance in ovarian cancer patients and the preliminary results are encouraging. In supporting this clinical study, using three pairs of cisplatin (cDDP)-resistant cell lines and two ovarian cancer cell lines derived from patients who had failed in platinum-based chemotherapy, we showed that cDDP resistance associated with reduced expression of the high-affinity copper transporter (hCtr1), which is also a cDDP transporter, can be preferentially resensitized by copper-lowering agents because of enhanced hCtr1 expression, as compared with their drug-sensitive counterparts. Such a preferential induction of hCtr1 expression in cDDP-resistant variants by copper chelation can be explained by the mammalian copper homeostasis regulatory mechanism. Enhanced cell-killing efficacy by a copper-lowering agent was also observed in animal xenografts bearing cDDP-resistant cells. Finally, by analyzing a public gene expression dataset, we found that ovarian cancer patients with elevated levels of hCtr1 in their tumors, but not ATP7A and ATP7B, had more favorable outcomes after platinum drug treatment than those expressing low hCtr1 levels. This study reveals the mechanistic basis for using copper chelation to overcome cDDP resistance in clinical investigations. PMID:22914438

Liang, Zheng D; Long, Yan; Tsai, Wen-Bin; Fu, Siqing; Kurzrock, Razelle; Gagea-Iurascu, Mihai; Zhang, Fan; Chen, Helen H W; Hennessy, Bryan T; Mills, Gordon B; Savaraj, Niramol; Kuo, Macus Tien

2012-08-21

415

Temporally and spectrally resolved imaging microscopy of lanthanide chelates.  

PubMed Central

The combination of temporal and spectral resolution in fluorescence microscopy based on long-lived luminescent labels offers a dramatic increase in contrast and probe selectivity due to the suppression of scattered light and short-lived autofluorescence. We describe various configurations of a fluorescence microscope integrating spectral and microsecond temporal resolution with conventional digital imaging based on CCD cameras. The high-power, broad spectral distribution and microsecond time resolution provided by microsecond xenon flashlamps offers increased luminosity with recently developed fluorophores with lifetimes in the submicrosecond to microsecond range. On the detection side, a gated microchannel plate intensifier provides the required time resolution and amplification of the signal. Spectral resolution is achieved with a dual grating stigmatic spectrograph and has been applied to the analysis of luminescent markers of cytochemical specimens in situ and of very small volume elements in microchambers. The additional introduction of polarization optics enables the determination of emission polarization; this parameter reflects molecular orientation and rotational mobility and, consequently, the nature of the microenvironment. The dual spectral and temporal resolution modes of acquisition complemented by a posteriori image analysis gated on the spatial, spectral, and temporal dimensions lead to a very flexible and versatile tool. We have used a newly developed lanthanide chelate, Eu-DTPA-cs124, to demonstrate these capabilities. Such compounds are good labels for time-resolved imaging microscopy and for the estimation of molecular proximity in the microscope by fluorescence (luminescence) resonance energy transfer and of molecular rotation via fluorescence depolarization. We describe the spectral distribution, polarization states, and excited-state lifetimes of the lanthanide chelate crystals imaged in the microscope.

Vereb, G; Jares-Erijman, E; Selvin, P R; Jovin, T M

1998-01-01

416

Effects of iron glycine chelate on growth, tissue mineral concentrations, fecal mineral excretion, and liver antioxidant enzyme activities in broilers.  

PubMed

The study was conducted to determine the effects of iron glycine chelate (Fe-Gly) on growth, tissue mineral concentrations, fecal mineral excretion, and liver antioxidant enzyme activities in broilers. A total of 360 1-day-old commercial broilers (Ross Ross) were randomly allotted to six dietary treatments with six replications of ten chicks per replicate. Broilers were fed a control diet with no Fe supplementation, while five other treatments consisted of 40, 80, 120, and 160 mg Fe/kg diets from Fe-Gly, and 160 mg Fe/kg from ferrous sulfate, respectively. After a 42-day feeding trial, the results showed that 120 and 160 mg Fe/kg as Fe-Gly improved the average daily gain (P < 0.05) and average daily feed intake (P < 0.05) of broilers (4-6 weeks). Addition with 120 and 160 mg Fe/kg from Fe-Gly and 160 mg Fe/kg from FeSO(4) increased Fe concentration in serum (P < 0.05), liver (P < 0.05), breast muscle (P < 0.05), tibia (P < 0.05), and feces (P < 0.01) at 21 and 42 days. There were linear responses to the addition of Fe-Gly from 0 to 160 mg/kg Fe on Fe concentration in serum (21 days, P = 0.005; 42 days, P = 0.001), liver (P = 0.001), breast muscle (P = 0.001), tibia (P = 0.001), and feces (21 days, P = 0.011; 42 days, P = 0.032). Liver Cu/Zn superoxide dismutase activities of chicks were increased by the addition of 80, 120, and 160 mg Fe/kg as Fe-Gly to diets at 42 days. There were no differences in liver catalase activities of chicks among the treatments (P > 0.05). This study indicates that addition with Fe-Gly could improve growth performance and iron tissue storage and improves the antioxidant status of broiler chickens. PMID:22549700

Ma, W Q; Sun, H; Zhou, Y; Wu, J; Feng, J

2012-05-02

417

Effective chelation of iron in beta thalassaemia with the oral chelator 1,2-dimethyl-3-hydroxypyrid-4-one.  

PubMed Central

The main iron chelator used for transfusional iron overload is desferrioxamine, which is expensive, has toxic side effects, and has to be given subcutaneously. An orally active iron chelator is therefore required. The effects of oral 1,2-dimethyl-3-hydroxypyrid-4-one on urinary iron excretion were studied in eight patients who had received multiple transfusions: four had myelodysplasia and four beta thalassaemia major. Different daily doses of the drug up to 100 mg/kg/day, alone or in combination with ascorbic acid, were used. In three patients with thalassaemia the effect of the drug was compared with that of subcutaneous desferrioxamine at the same daily dose. In all eight patients a single dose of oral 1,2-dimethyl-3-hydroxypyrid-4-one resulted in substantial urinary iron excretion, mainly in the first 12 hours. Urinary iron excretion increased with the dose and with the degree of iron loading of the patient. Giving two or three divided doses over 24 hours resulted in higher urinary iron excretion than a single dose of the same amount over the same time. In most patients coadministration of oral ascorbic acid further increased urinary iron excretion. 1,2-Dimethyl-3-hydroxypyrid-4-one caused similar iron excretion to that achieved with subcutaneous desferrioxamine at a comparable dose. In some cases the iron excretion was sufficiently high (maximum 99 mg/day) to suggest that a negative iron balance could be easily achieved with these protocols in patients receiving regular transfusions. No evidence of toxicity was observed on thorough clinical examination or haematological and biochemical testing in any of the patients. None of the patients had any symptoms that could be ascribed to the drug. These results suggest that the oral chelator 1,2-dimethyl-3-hydroxypyrid-4-one is as effective as subcutaneous desferrioxamine in increasing urinary iron excretion in patients loaded with iron. Its cheap synthesis, oral activity, and lack of obvious toxicity at effective doses suggest that it should be developed quickly and thoroughly tested for the management of transfusional iron overload.

Kontoghiorghes, G J; Aldouri, M A; Hoffbrand, A V; Barr, J; Wonke, B; Kourouclaris, T; Sheppard, L

1987-01-01

418

Contribution of ferrous iron to maintenance of the gastric colonization of Helicobacter pylori in miniature pigs.  

PubMed

Our previous study showed that the colonization levels of Helicobacter pylori were higher in the stomachs of 5-day-old miniature pigs than in 2-week-old ones. As dietary factors can cause these differences, we compared two diets, i.e., Weanymilk and a similar formula with a higher concentration of Fe(II), Weanylobulin. The colonization levels in the fundic mucosa were significantly higher in 2-week-old pigs fed Weanylobulin than in those fed Weanymilk. Supplementing Weanylobulin with an iron chelator, deferoxamine mesylate, significantly lowered the bacteria counts in the gastric mucosa. Normal diets supplemented with Fe(II) in 2-month-old pigs caused significantly more sites of bacteria in the antrum compared with normal diets alone. In addition, ranitidine, an inhibitor of gastric acid secretion that reduces Fe(III) to Fe(II) in the stomach, decreased the bacteria counts in 10-month-old pigs. These results suggested that Fe(II) maintained the colonization levels of H. pylori in the stomach of the miniature pigs. PMID:12501997

Koga, Tetsufumi; Shimada, Yukio; Sato, Kiyoshi; Takahashi, Keigo; Kikuchi, Isamu; Okazaki, Yoko; Miura, Tomoko; Katsuta, Mitsuo; Iwata, Masayuki

2002-01-01

419

Ferrous ion binding to recombinant human H-chain ferritin. An isothermal titration calorimetry study.  

PubMed

Iron deposition within the iron storage protein ferritin involves a complex series of events consisting of Fe(2+) binding, transport, and oxidation at ferroxidase sites and mineralization of a hydrous ferric oxide core, the storage form of iron. In the present study, we have examined the thermodynamic properties of Fe(2+) binding to recombinant human H-chain apoferritin (HuHF) by isothermal titration calorimetry (ITC) in order to determine the location of the primary ferrous ion binding sites on the protein and the principal pathways by which the Fe(2+) travels to the dinuclear ferroxidase center prior to its oxidation to Fe(3+). Calorimetric titrations show that the ferroxidase center is the principal locus for Fe(2+) binding with weaker binding sites elsewhere on the protein and that one site of the ferroxidase center, likely the His65 containing A-site, preferentially binds Fe(2+). That only one site of the ferroxidase center is occupied by Fe(2+) implies that Fe(2+) oxidation to form diFe(III) species might occur in a stepwise fashion. In dilute anaerobic protein solution (3-5 microM), only 12 Fe(2+)/protein bind at pH 6.51 increasing to 24 Fe(2+)/protein at pH 7.04 and 7.5. Mutation of ferroxidase center residues (E62K+H65G) eliminates the binding of Fe(2+) to the center, a result confirming the importance of one or both Glu62 and His65 residues in Fe(2+) binding. The total Fe(2+) binding capacity of the protein is reduced in the 3-fold hydrophilic channel variant S14 (D131I+E134F), indicating that the primary avenue by which Fe(2+) gains access to the interior of ferritin is through these eight channels. The binding stoichiometry of the channel variant is one-third that of the recombinant wild-type H-chain ferritin whereas the enthalpy and association constant for Fe(2+) binding are similar for the two with an average values (DeltaH degrees = 7.82 kJ/mol, binding constant K = 1.48 x 10(5) M(-)(1) at pH 7.04). Since channel mutations do not completely prevent Fe(2+) binding to the ferroxidase center, iron gains access to the center in approximately one-third of the channel variant molecules by other pathways. PMID:12220183

Bou-Abdallah, Fadi; Arosio, Paolo; Santambrogio, Paolo; Yang, Xiaoke; Janus-Chandler, Christine; Chasteen, N Dennis

2002-09-17

420

Arsenite sequestration by nanosized ferrous minerals after bioreduction of arsenic-sorbed lepidocrocite by Shewanella putrefaciens  

NASA Astrophysics Data System (ADS)

X-ray absorption spectroscopy was used in combination with high resolution transmission electron microscopy, X-ray powder diffraction, and M鰏sbauer spectroscopy to obtain detailed information on arsenic and iron speciation in the products of anaerobic reduction of pure and As(V)- or As(III)-adsorbed lepidocrocite (?-FeOOH) by Shewanella putrefaciens ATCC 12099. We found that this strain is capable of using both Fe(III) in lepidocrocite and As(V) in solution or adsorbed on lepidocrocite surfaces as electron acceptors. Bioreduction of lepidocrocite in the absence of arsenic resulted in the formation of hydroxycarbonate green rust 1 [FeII4FeIII2(OH)12CO3: GR1(CO3)], which completely converted into ferrous- carbonate hydroxide (FeII2(OH)2CO3: FCH). Bioreduction of As(III)-adsorbed lepidocrocite also led to the formation of GR1(CO3) prior to formation of FCH, but the presence of As(III) slows down this transformation, leading to the co-occurrence of both phases. At the end of this experiment, As(III) was found to be adsorbed on the surfaces of GR1(CO3) and FCH. Bioreduction of As(V)-bearing lepidocrocite led directly to the formation of FCH in association with nanometer-sized particles of a minor As-rich Fe(OH)2 phase, with no evidence for green rust formation. At the end of this experiment, As(V) was fully converted to As(III) and dominantly sorbed at the surface of the Fe(OH)2 nanoparticles as oligomers binding to the edges of Fe(OH)6 octahedra in the octahedral layers of Fe(OH)2. These multinuclear As(III) surface complexes are characterized by As-As pairs at a distance of 3.32 0.02 and by As-Fe pairs at a distance of 3.50 0.02 and represent a new form of As(III) surface complexes. Chemical analyses show that the majority of As(III) produced in the experiments with As present is associated with iron-bearing hydroxycarbonate or hydroxide solids, reinforcing the idea that, at least under some circumstances, bacterial reduction can promote As(III) sequestration instead of mobilizing it into solution.

Ona-Nguema, G.; Morin, G.; Wang, Y.; Juillot, F.; Abdelmoula, M.; Ruby, C.; Guyot, F.; Calas, G.; Brown, G.

2008-12-01

421

Long-term Chelation Therapy in Thalassaemia Major: Effect on Liver Iron Concentration, Liver Histology, and Clinical Progress  

Microsoft Academic Search

A prospective trial of continuous chelation therapy in children with homozygous thalassaemia on a high transfusion regimen was started in April 1966. The effect of treatment on iron concentration in the liver and on hepatic histology was examined in 49 biopsy specimens obtained from nine chelator-treated patients and nine control patients between April 1966 and April 1973.Chelation therapy was associated

Michael Barry; David M. Flynn; Elizabeth A. Letsky; R. A. Risdon

1974-01-01

422

Product Release Rather Than Chelation Determines Metal Specificity for Ferrochelatase  

PubMed Central

SUMMARY Ferrochelatase (protoheme ferrolyase, E.C. 4.99.1.1) is the terminal enzyme in heme biosynthesis and catalyzes the insertion of ferrous iron into protoporphyrin IX to form protoheme IX (heme). Within the past two years x-ray crystallographic data obtained with human ferrochelatase have clearly shown that significant structural changes occur during catalysis that are predicted to facilitate metal insertion and product release. One unanswered question about ferrochelatase involves defining the mechanism whereby some metals, such as divalent Fe, Co, Ni and Zn, can be used by the enzyme in vitro to produce the corresponding metalloporphyrins while other metals, such as divalent Mn, Hg, Cd or Pb, are inhibitors of the enzyme. Through the use of high resolution x-ray crystallography along with characterization of metal species via their anomalous diffraction, the identity and position of Hg, Cd, Ni, or Mn in the center of enzyme-bound porphyrin macrocycle was determined. When Pb, Hg, Cd or Ni was present in the macrocycle the conserved ? helix was in the extended, partially unwound 損roduct release state. Interestingly, in the structure of ferrochelatase with Mn-porphyrin bound the ? helix is not extended or unwound and is in the 搒ubstrate-bound conformation. These findings show that at least in the cases of Mn, Pb, Cd and Hg, metal 搃nhibition of ferrochelatase is not due to the inability of the enzyme to insert the metal into the macrocycle or by binding to a second metal binding site as has been previously proposed. Rather, inhibition occurs after metal insertion and results from poor or diminished product release. Possible explanations for the lack of product release are proposed herein.

Medlock, Amy E.; Carter, Michael; Dailey, Tamara A.; Dailey, Harry A.; Lanzilotta, William N.

2009-01-01

423

Product Release Rather than Chelation Determines Metal Specificity for Ferrochelatase  

SciTech Connect

Ferrochelatase (protoheme ferrolyase, E.C. 4.99.1.1) is the terminal enzyme in heme biosynthesis and catalyzes the insertion of ferrous iron into protoporphyrin IX to form protoheme IX (heme). Within the past two years, X-ray crystallographic data obtained with human ferrochelatase have clearly shown that significant structural changes occur during catalysis that are predicted to facilitate metal insertion and product release. One unanswered question about ferrochelatase involves defining the mechanism whereby some metals, such as divalent Fe, Co, Ni, and Zn, can be used by the enzyme in vitro to produce the corresponding metalloporphyrins, while other metals, such as divalent Mn, Hg, Cd, or Pb, are inhibitors of the enzyme. Through the use of high-resolution X-ray crystallography along with characterization of metal species via their anomalous diffraction, the identity and position of Hg, Cd, Ni, or Mn in the center of enzyme-bound porphyrin macrocycle were determined. When Pb, Hg, Cd, or Ni was present in the macrocycle, the conserved {pi} helix was in the extended, partially unwound 'product release' state. Interestingly, in the structure of ferrochelatase with Mn-porphyrin bound, the {pi} helix is not extended or unwound and is in the 'substrate-bound' conformation. These findings show that at least in the cases of Mn, Pb, Cd, and Hg, metal 'inhibition' of ferrochelatase is not due to the inability of the enzyme to insert the metal into the macrocycle or by binding to a second metal binding site as has been previously proposed. Rather, inhibition occurs after metal insertion and results from poor or diminished product release. Possible explanations for the lack of product release are proposed herein.

Medlocka, Amy E.; Cartera, Michael; Daileya, Tamara A.; Daileya, Harry A.; Lanzilotta, William N.; (Georgia)

2009-11-16

424

Prevention of Gastrointestinal Iron Absorption by Chelation From an Orally Administered Premixed Deferoxamine\\/Charcoal Slurry  

Microsoft Academic Search

See related editorial, p 687.Study objective: To investigate the effect of an orally administered premixed slurry of deferoxamine mesylate (DFO) and activated charcoal (AC) on the gastrointestinal (GI) absorption of ferrous sulfate under physiologic conditions. Methods: This was a prospective, crossover, controlled human volunteer study. Participants were healthy adult subjects aged 25 to 38 years. Volunteers ingested either 5 mg\\/kg

Hernan F Gomez; Hilary H McClafferty; David Flory; Jeffrey Brent; Richard C Dart

1997-01-01

425

Metal chelate\\/anti-oxidant combinations with dimer-trimer acids, pipeline corrosion inhibitors  

Microsoft Academic Search

A composition is disclosed for inhibiting the corrosion of ferrous metal pipelines used to transport petroleum hydrocarbons. The inhibitor consists of a mixture of C36 dicarboxylic dimer acid and a C54 trimer acid. The mixture has an acid number of at least 110 and from 0.5 up to about 5% of a composition from the group consisting of: (A) an

Gainer

1980-01-01

426

Statistical Analysis of Metal Chelating Activity of Centella asiatica and Erythroxylum cuneatum Using Response Surface Methodology.  

PubMed

The purpose of the study is to evaluate the relationship between the extraction parameters and the metal chelating activity of Centella asiatica (CA) and Erythroxylum cuneatum (EC). The response surface methodology was used to optimize the extraction parameters of methanolic extract of CA and EC with respect to the metal chelating activity. For CA, Run 17 gave optimum chelating activity with IC50 = 0.93?mg/mL at an extraction temperature of 25癈, speed of agitation at 200?rpm, ratio of plant material to solvent at 1?g?:?45?mL and extraction time at 1.5 hour. As for EC, Run 13 with 60癈, 200?rpm, 1?g?:?35?mL and 1 hour had metal chelating activity at IC50 = 0.3817?mg/mL. Both optimized extracts were further partitioned using a solvent system to evaluate the fraction responsible for the chelating activity of the plants. The hexane fraction of CA showed potential activity with chelating activity at IC50 = 0.090 and the ethyl acetate fraction of EC had IC50 = 0.120?mg/mL. The study showed that the response surface methodology helped to reduce the extraction time, temperature and agitation and subsequently improve the chelating activity of the plants in comparison to the conventional method. PMID:23533781

Mohd Salim, R J; Adenan, M I; Amid, A; Jauri, M H; Sued, A S

2013-02-27

427

[Effectiveness of ferrous sulfate supplementation in the prevention of anemia in children: a systematic literature review and meta-analysis].  

PubMed

This was a systematic review and meta-analysis of studies evaluating the effectiveness of ferrous sulfate supplementation in the prevention of anemia in children under five. The database search included PubMed, Scopus, LILACS, and SciELO. Articles published between 1980 and 2011 in Spanish, English, or Portuguese were included, using the keywords child, preschool, infant, anemia, prevention, and iron supplementation. The authors selected 13 studies, which showed that regardless of dose and duration of supplementation, daily regimen was more consistently related to improvement in hemoglobin levels (pooled effect 0.56mg/dL, 95%CI: 0.31; 0.81, p < 0.001) as compared to weekly intervention (pooled effect 0.28mg/dL, 95%CI: -0.22; 0.78, p = 0.273). Iron supplementation was not associated with decreased prevalence of anemia, even with daily doses, and administration with other micronutrients did not bring additional benefits compared to the exclusive administration of iron supplement. Daily supplementation of ferrous sulfate was more effective than weekly doses in improving hemoglobin levels. PMID:24068220

Cembranel, Francieli; Dallazen, Camila; Gonz醠ez-Chica, David Alejandro

2013-09-01

428

Dissimilatory ferrous iron oxidation at a low pH: a novel trait identified in the bacterial subclass Rubrobacteridae.  

PubMed

A novel iron-oxidizing acidophilic actinobacterium was isolated from spoil material at an abandoned copper mine. Phylogenetic analysis placed the isolate within the Rubrobacteridae subclass of the Actinobacteria. Its optimum temperature and pH for growth are 30-35 degrees C and pH 3.0, respectively. Although it could catalyze the dissimilatory oxidation of ferrous iron, growth yields declined progressively in media containing ferrous iron concentrations >100 microM. The isolate, Pa33, did not grow or oxidize iron in the absence of organic carbon, and appeared to be an obligate heterotroph. Specific rates of iron oxidation were much smaller than those determined for the autotrophic iron-oxidizing proteobacterium Acidithiobacillus ferrooxidans and the heterotrophic iron-oxidizing actinobacterium Ferrimicrobium acidiphilum. Iron oxidation by isolate Pa33 appears to be a defensive mechanism, in which iron oxidation converts a soluble species to which the bacterium is sensitive to an oxidized species (ferric iron) that is highly insoluble in the spoil from which it was isolated. This is the first report of acidophily or dissimilatory iron oxidation within the Rubrobacteridae subclass and one of very few within the Actinobacteria phylum as a whole. PMID:18803673

Bryan, Christopher G; Johnson, David B

2008-09-18

429

Dynamic Simulation of Pressure Driven Flow of Fluids with Suspended Ferrous Particles in a Micro Channel Under Magnetic Field  

NASA Astrophysics Data System (ADS)

This computational study focuses on the dynamics of individual ferrous particles and the flow of the incompressible Newtonian fluid under the effect of an externally applied magnetic field and pressure gradient in a two-dimensional micro channel with smooth walls. The particle dynamics is simulated as a discrete phase using MATLAB code and the fluid flow is solved as a continuous phase using Computational Fluid Dynamics Software FLUENT. Interaction between the particle and fluid phases are included as hydrodynamic forces predicated by the fluid phase simulation and updated particle locations determined by the particle phase solution under non-uniform magnetic field. Non-uniform magnetic field forces the particles to move to poles of the magnet, and results in their accumulation. This causes drastic change on the continuous phase flow and pressure distribution, which in turn influences the particle motion. Predicted dynamics of the suspended ferrous particles under magnetic field and flow of the carrier fluid with pressure gradient is in reasonably well agreement with previous work. The results show that non-uniform magnetic field generated by externally placed magnets can be used to control the locations of the particles and flow of the fluid in a micro channel.

Ozcan, Sinan; Evrensel, Cahit A.; Pinsky, Mark A.; Fuchs, Alan

430

Effect of VOCs and methane in the biological oxidation of the ferrous ion by an acidophilic consortium.  

PubMed

During the elimination of H2S from biogas in an aqueous ferric sulphate solution, volatile organic compounds (VOCs) and methane are absorbed and may have an effect on the subsequent biological regeneration of ferric ion. This study was conducted to investigate the effect of maximum concentrations of methane and some VOCs found in biogas on the ferrous oxidation of an acidophilic microbial consortium (FO consortium). The presence and impact of heterotrophic microorganisms on the activity of the acidophilic consortium was also evaluated. No effect on the ferrous oxidation rate was found with gas concentrations of 1500 mg toluene m(-3), 1400 mg 2-butanol m(-3) or 1250 mg 1,2-dichloroethane m(-3), nor with methane at gas concentrations ranging from 15-25% (v/v). A tenfold increase in VOCs concentrations totally inhibited the microbial activity of the FO consortium and the heterotrophs. The presence of a heterotrophic fungus may promote the autotrophic growth of the FO consortium. PMID:22629626

Almenglo, F; Ram韗ez, M; G髆ez, J M; Cantero, D; Revah, S; Gonz醠ez-S醤chez, A

431

Ferric, not ferrous, heme activates RNA-binding protein DGCR8 for primary microRNA processing  

PubMed Central

The RNA-binding protein DiGeorge Critical Region 8 (DGCR8) and its partner nuclease Drosha are essential for processing of microRNA (miRNA) primary transcripts (pri-miRNAs) in animals. Previous work showed that DGCR8 forms a highly stable and active complex with ferric [Fe(III)] heme using two endogenous cysteines as axial ligands. Here we report that reduction of the heme iron to the ferrous [Fe(II)] state in DGCR8 abolishes the pri-miRNA processing activity. The reduction causes a dramatic increase in the rate of heme dissociation from DGCR8, rendering the complex labile. Electronic absorption, magnetic circular dichroism, and resonance Raman spectroscopies indicate that reduction of the heme iron is accompanied by loss of the cysteines as axial ligands. ApoDGCR8 dimers, generated through reduction and removal of the heme, show low levels of activity in pri-miRNA processing in vitro. Importantly, ferric, but not ferrous, heme restores the activity of apoDGCR8 to the level of the native ferric complex. This study demonstrates binding specificity of DGCR8 for ferric heme, provides direct biochemical evidence for ferric heme serving as an activator for miRNA maturation, and suggests that an intracellular environment increasing the availability of ferric heme may enhance the efficiency of pri-miRNA processing.

Barr, Ian; Smith, Aaron T.; Chen, Yanqiu; Senturia, Rachel; Burstyn, Judith N.; Guo, Feng

2012-01-01

432

Exogenous ferrous iron is required for the nitric oxide-catalysed destruction of the iron-sulphur centre in adrenodoxin.  

PubMed Central

No effects of gaseous NO added at a pressure of 19.95 kPa on the stability of the binuclear iron-sulphur centre (ISC) of reduced iron-sulphur protein adrenodoxin (0.2 mM) have been observed using the EPR method. However, the incubation of the protein with NO in the presence of ferrous iron (1.8 mM) led to complete ISC degradation, accompanied by the formation of protein-bound dinitrosyl iron complexes (DNICs; 0.3+/-0.1 mM). Similar results were obtained when low-molecular-mass DNIC with phosphate or cysteine (1.8 mM) were added to solutions of pre-reduced adrenodoxin. The degradation of the ISC was suggested to be due to the attack of the Fe(+)(NO(+))(2) group from low-molecular-mass DNICs added or formed during the interaction between NO and ferrous ions on the thiol groups in active centres of adrenodoxin. This attack leads to a release of endogenous iron from the centres, which is capable of forming both low-molecular-mass and protein-bound DNIC, thereby ensuring further ISC degradation.

Voevodskaya, Nina V; Serezhenkov, Vladimir A; Cooper, Chris E; Kubrina, Lioudmila N; Vanin, Anatoly F

2002-01-01

433

Alteration of tissue disposition of cadmium by chelating agents. [Mice; rats  

SciTech Connect

The effect of several chelating agents (diethyldithiocarbamic acid, DDC; nitrilotriacetic acid, NTA; 2,3-dimercaptopropanol, BAL; d,l-penicillamine, PEN; 2,3-dimercaptosuccinic acid, DMSA; ethylenediaminetetraacetic acid, EDTA; and diethylenetriaminepentaacetic acid, DTPA) on the toxicity, distribution and excretion of cadmium (Cd) was determined in mice. When chelators were administered immediately after Cd, significant increases in survival were noted after treatment with DMSA, EDTA, and DTPA. DTPA, followed by EDTA and then DMSA, were consistently the most effective in decreasing the tissue concentrations of Cd and increasing the excretion of Cd. NTA, BAL, DDC and PEN had no beneficial effects. To determine the role of MT in the acute decrease in chelator efficacy following Cd poisoning, rats were injected IV with Cd followed by DTPA at various times after Cd. Although DTPA reduced Cd content in the various organs when given immediately after Cd, the chelator was ineffective at all later times. Increases in hepatic and renal metallothionein (MT) did not occur until 2 hr after Cd, and did not coincide with the earlier drop in chelator efficacy. Blockade of MT synthesis by actinomycin D failed to eliminate this decreased DTPA effectiveness. Therefore, it appears that MT does not play an important role in the acute decrease in efficacy of chelation therapy for Cd poisoning. The effect of repeated daily administration of chelators on the distribution and excretion of Cd was studied by administering chelators daily for 5 days starting 48 hr after Cd. DTPA, EDTA, DMSA and BAL significantly increased the urinary elimination of Cd. Thus, mobilization of Cd into urine occurs with repeated chelation therapy, which may decrease tissue concentrations of Cd and reduce the toxicity of the metal. 4 references, 15 figures, 2 tables.

Klaassen, C.D.; Waalkes, M.P.; Cantilena, L.R. Jr.

1984-03-01

434

Photoreduction of carbon dioxide by aqueous ferrous ion: An alternative to the strongly reducing atmosphere for the chemical origin of life  

PubMed Central

We have shown that ferrous ion at neutral pH photoreduces water to hydrogen with a high quantum yield on excitation with near-ultraviolet light. This simple system also efficiently reduces carbon dioxide (bicarbonate ions) to formaldehyde. Overall, these reactions offer a solution to a dilemma confronting the standard or Oparin-Urey model of the origin of life. If carbon dioxide was the main form of carbon on the primitive earth, the ferrous photoreaction would have provided the reduced carbon necessary to form amino acids and other biogenetic molecules. We believe this system may have been the progenitor to the biological photosynthetic systems.

Borowska, Zofia; Mauzerall, David

1988-01-01

435

Removal of vanadium by combining desferrioxamine and deferiprone chelators in rats  

Microsoft Academic Search

Investigations were conducted to evaluate the ability of two chelators, desferrioxamine (DFO), and deferiprone (1,2-dimethy1-3-hydroxypyride-4-one,\\u000a L1), for the excretion of vanadium after a period of administration of vanadium salts in 6-week-old male Wistar rats. Immediately\\u000a after 60燿ays of vanadium administration, the rats received chelators (L1, DFO or L1+燚FO) for a period of 1爓eek. Chelators were given orally (L1), intraperitoneally (DFO),

Solmaz Tubafard; S. Jamilaldine Fatemi; Amir Shokooh Saljooghi; Masoud Torkzadeh

2010-01-01

436

Design, synthesis, and evaluation of polyhydroxamate chelators for selective complexation of actinides  

SciTech Connect

Specific chelating polymers targeted for actinides have much relevance to problems involving remediation of nuclear waste. Goal is to develop polymer supported, ion specific extraction systems for removing actinides and other hazardous metal ions from wastewaters. This is part of an effort to develop chelators for removing actinide ions such as Pu from soils and waste streams. Selected ligands are being attached to polymeric backbones to create novel chelating polymers. These polymers and other water soluble and insoluble polymers have been synthesized and are being evaluated for ability to selectively remove target metal ions from process waste streams.

Gopalan, A.; Jacobs, H.; Koshti, N.; Stark, P.; Huber, V.; Dasaradhi, L.; Caswell, W. [New Mexico State Univ., Las Cruces, NM (United States); Smith, P.; Jarvinen, G. [Los Alamos National Lab., NM (United States)

1995-08-01

437

Selective divalent copper chelation for the treatment of diabetes mellitus.  

PubMed

Oxidative stress and mitochondrial dysfunction have been identified by many workers as key pathogenic mechanisms in ageing-related metabolic, cardiovascular and neurodegenerative diseases (for example diabetes mellitus, heart failure and Alzheimer's disease). However, although numerous molecular mechanisms have been advanced to account for these processes, their precise nature remains obscure. This author has previously suggested that, in such diseases, these two mechanisms are likely to occur as manifestations of a single underlying disturbance of copper regulation. Copper is an essential but highly-toxic trace metal that is closely regulated in biological systems. Several rare genetic disorders of copper homeostasis are known in humans: these primarily affect various proteins that mediate intracellular copper transport processes, and can lead either to tissue copper deficiency or overload states. These examples illustrate how impaired regulation of copper transport pathways can cause organ damage and provide important insights into the impact of defects in specific molecular processes, including those catalyzed by the copper-transporting ATPases, ATP7A (mutated in Menkes disease), ATP7B (Wilson's disease), and the copper chaperones such as those for cytochrome c oxidase, SCO1 and SCO2. In diabetes, impaired copper regulation manifests as elevations in urinary CuII excretion, systemic chelatable-CuII and full copper balance, in increased pro-oxidant stress and defective antioxidant defenses, and in progressive damage to the blood vessels, heart, kidneys, retina and nerves. Linkages between dysregulated copper and organ damage can be demonstrated by CuII-selective chelation, which simultaneously prevents/reverses both copper dysregulation and organ damage. Pathogenic structures in blood vessels that contribute to binding and localization of catalytically-active CuII probably include advanced glycation end products (AGEs), as well as atherosclerotic plaque: the latter probably undergoes AGE-modification itself. Defective copper regulation mediates organ damage through two general processes that occur simultaneously in the same individual: elevation of CuII-mediated pro-oxidant stress and impairment of copper-catalyzed antioxidant defence mechanisms. This author has proposed that diabetes-evoked copper dysregulation is an important new target for therapeutic intervention to prevent/reverse organ damage in diabetes, heart failure, and neurodegenerative diseases, and that triethylenetetramine (TETA) is the first in a new class of anti-diabetic molecules, which function by targetting these copper-mediated pathogenic mechanisms. TETA prevents tissue damage and causes organ regeneration by acting as a highly-selective CuII chelator which suppresses copper-mediated oxidative stress and restores anti-oxidant defenses. My group has employed TETA in a comprehensive programme of nonclinical studies and proof-of-principle clinical trials, thereby characterizing copper dysregulation in diabetes and identifying numerous linked cellular and molecular mechanisms though which TETA exerts its therapeutic actions. Many of the results obtained in nonclinical models with respect to the molecular mechanisms of diabetic organ damage have not yet been replicated in patients' tissues so their applicability to the human disease must be considered as inferential until the results of informative clinical studies become available. Based on evidence from the studies reviewed herein, trientine is now proceeding into the later stages of pharmaceutical development for the treatment of heart failure and other diabetic complications. PMID:22455587

Cooper, G J S

2012-01-01

438

Iron chelation properties of an extracellular siderophore exochelin MN.  

PubMed

The coordination chemistry of an extracellular siderophore produced by Mycobacterium neoaurum, exochelin MN (ExoMN), is reported along with its pK(a) values, Fe(III) and Fe(II) chelation constants, and aqueous solution speciation as determined by spectrophotometric and potentiometric titration techniques. Exochelin MN is of particular interest as it can efficiently transport iron into pathogenic M. leprae, which is responsible for leprosy, in addition to its own parent cells. The Fe(III) coordination properties of ExoMN are important with respect to understanding the Fe(III) acquisition and uptake mechanism in pathogenic M. leprae, as the siderophores from this organism are very difficult to isolate. Exochelin MN has two hydroxamic acid groups and an unusual threo-beta-hydroxy-l-histidine available for Fe(III) chelation. The presence of threo-beta-hydroxy-l-histidine gives rise to a unique mode of Fe(III) coordination. The pK(a) values for the two hydroxamic acid moieties, the histidine imidazole ring and the alkylammonium groups on ExoMN, correspond well with the literature values for these moieties. Proton-dependent Fe(III)- and Fe(II)-ExoMN equilibrium constants were determined using a model involving sequential protonation of the Fe(III)- and Fe(II)-ExoMN complexes. These data were used to develop a model whereby deprotonation reactions on the surface of the complex in the second coordination shell result in first coordination shell isomerization. The overall formation constants were calculated: log beta(110) = 39.12 for Fe(III)-ExoMN and 16.7 for Fe(II)-ExoMN. The calculated pFe value of 31.1 is one of the highest among all siderophores and their synthetic analogues and indicates that ExoMN is thermodynamically capable of removing Fe(III) from transferrin. The E(1/2) for the Fe(III)ExoMN/Fe(II)ExoMN(-) couple was determined to be -595 mV from quasi-reversible cyclic voltammograms at pH = 10.8, and the pH-dependent E(1/2) profile was used to determine the Fe(II)-ExoMN protonation constants. PMID:12812507

Dhungana, Suraj; Miller, Marvin J; Dong, Li; Ratledge, Colin; Crumbliss, Alvin L

2003-06-25

439

Frequency-domain measurement of luminescent lanthanide chelates.  

PubMed

The sinusoidal modulation of excitation intensity and phase-sensitive detection of emission is ideally suitable for the accurate determination of the lifetime and intensity of lanthanide luminescence. In this work we elaborate on the general mathematical and instrumental techniques of the frequency-domain (FD) measurements in the low-frequency domain below 100 kHz. A modular FD luminometer is constructed by using a UV-LED as the excitation source, proper light filters in the excitation and emission paths, a photomultiplier with a fast preamplifier, and a conventional dual-phase lock-in amplifier. Starting from the set of linear differential equations governing the excited-state processes of the lanthanide chelates, an equation linking the luminescence intensity to the general form of the excitation modulation was derived. Application to the sinusoidal modulation in the Euler's exponential form gives the expression for the in-phase and out-of-phase signals of a dual-phase lock-in amplifier. It is shown that by using a relatively large number of logarithmically equidistant modulation frequencies it is possible to use the Kramers-Kronig relation for checking the compatibility of the out-of-phase and in-phase signals. As an example, the emission from two different europium(III) chelates were measured by using 200 modulation frequencies between 10 Hz and 100 kHz. In addition to the conventional transition between (5)D(0) and (7)F(2) levels emitting at 615 nm, also the emission from the transition between (5)D(1) and (7)F(1) levels at ca. 540 nm was measured. The latter emission was also measured at different temperatures, yielding the energy difference between the (5)D(1) and (5)D(0) levels. The relatively large number of modulation frequencies allows also an accurate determination of lifetimes and corresponding amplitudes by using an appropriate nonlinear regression method. Comparison of the time-domain and frequency-domain methods shows that the weighting of data is different and both methods have application areas of their own. PMID:20617797

Hypp鋘en, Iko; Soukka, Tero; Kankare, Jouko

2010-08-01

440

Soil Remediation of an Arsenic-Contaminated Site With Ferrous Sulfate and Type V Portland Cement  

NASA Astrophysics Data System (ADS)

High levels of arsenic are present in a site adjacent to San Francisco Bay (in East Palo Alto, CA) as a consequence of the activity of a former pesticide manufacturing plant. Most of the readily accessible arsenic at the site has been removed by remedial excavation and surface capping. In-situ fixation of residual arsenic was performed close to the source about 10 years ago where arsenic values in capped soils ranged from 500 to 5000 mg kg-1. The fixation method consisted of the addition of ferrous sulfate (3% w/w), type V Portland cement (10% w/w) and water. Both products were mixed with the contaminated soil to a treatment depth between 1.5 and 9 meters. The treated soil was then capped to prevent weathering. This long-term amended soil offers an opportunity to compare the processes that prevent microbial arsenic reduction and control the immobilization of arsenic in the treated soils versus natural soils, and to study the aging effects of arsenic sorption. Solid phase characterization of soil samples from both the field and controlled laboratory experiments were carried out to study the speciation and bioavailability of arsenic and to ascertain the mechanisms of the arsenic immobilization in the treated soil. These methods included physical description by field observations, X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy, total elemental concentrations, and solid phase fractionation by sequential extraction. Both synchrotron X-ray absorption spectroscopy (XAS) and XRD measurements were used to determine oxidation state of arsenic and iron and host phases present in the soil. The remedial treatment was successful in immobilizing the arsenic in the contaminated soil, and decreasing its leachability. Measurements taken at short aging times (during the first month) showed that the treatment was effective in reducing leachable arsenic as evidenced by the TCLP wet test (< 5 mg l-1 leached). The field amendment influenced arsenic speciation. The treated soil in both field samples and short-term laboratory experiments contained only As(V), suggesting that the microbial reduction of arsenic is prevented in the amended soils. Natural soils from cores adjacent to the amended soils contained both As(III) and As(V), and sulfides associated with the arsenic. The addition of Portland cement to soils caused alkaline conditions and pH buffering, changing the pH from 7 before the treatment to 12 afterwards. Calcium and iron sulfates are typical precipitates of iron sulfate and cement applications. Our characterizations suggest that arsenate was incorporated into new phases, either as solid solutions with sulfate or as localized arsenate phases. Arsenic incorporated into these less soluble phases is resistant to desorption and leaching, particularly under changing subsurface conditions.

Illera, V.; O'Day, P. A.; Rivera, N.; Root, R.; Rafferty, M. T.; Vlassopoulos, D.

2005-12-01

441

Curcumin Inhibits Growth of Saccharomyces cerevisiae through Iron Chelation ? 唵  

PubMed Central

Curcumin, a polyphenol derived from turmeric, is an ancient therapeutic used in India for centuries to treat a wide array of ailments. Interest in curcumin has increased recently, with ongoing clinical trials exploring curcumin as an anticancer therapy and as a protectant against neurodegenerative diseases. In vitro, curcumin chelates metal ions. However, although diverse physiological effects have been documented for this compound, curcumin's mechanism of action on mammalian cells remains unclear. This study uses yeast as a model eukaryotic system to dissect the biological activity of curcumin. We found that yeast mutants lacking genes required for iron and copper homeostasis are hypersensitive to curcumin and that iron supplementation rescues this sensitivity. Curcumin penetrates yeast cells, concentrates in the endoplasmic reticulum (ER) membranes, and reduces the intracellular iron pool. Curcumin-treated, iron-starved cultures are enriched in unbudded cells, suggesting that the G1 phase of the cell cycle is lengthened. A delay in cell cycle progression could, in part, explain the antitumorigenic properties associated with curcumin. We also demonstrate that curcumin causes a growth lag in cultured human cells that is remediated by the addition of exogenous iron. These findings suggest that curcumin-induced iron starvation is conserved from yeast to humans and underlies curcumin's medicinal properties.

Minear, Steven; O'Donnell, Allyson F.; Ballew, Anna; Giaever, Guri; Nislow, Corey; Stearns, Tim; Cyert, Martha S.

2011-01-01

442

Acute mercury intoxication and use of chelating agents.  

PubMed

There is a great hazard of mercury intoxication in the third world for artisanal miners using mercury as amalgam for extracting and refining gold. In developing countries, there is the possibility of risk regarding exposure to Hg from amalgam tooth fillings, ethyl-Hg (thimerosal) added as antiseptic to vaccines and methyl-Hg in fish. In one case, a 41-year-old man attempted suicide by ingesting 100 mg of HgCl2. After 8 hours, he developed hematemesis and entered the intensive care unit; his urinary Hg was 10.1 mg/l. Treatment with 2,3-dimercaptopropanol (BAL) was started by intramuscular route after 16 hours at the dosage of 5 mg/kg body weight every 4 hours on days 2-3 and 3 mg/kg every 6 hours on days 4-5 and then every 12 hours on days 6-14 without adverse side effects. Acute Hg intoxication can be managed with BAL as first choice chelator, whereas the less toxic 2,3-dimercaptosuccinic acid (DMSA) and 2,3-dimercaptopropane-1-sulfonic acid (DMPS) should be reserved for cases of less severe inorganic Hg or methyl-Hg acute intoxication. Such agents, recommended only for the treatment of acute Hg poisoning, should not be used for patients suffering from neurological diseases in which environmental Hg exposure is hypothesised. PMID:20003760

Boscolo, M; Antonucci, S; Volpe, A R; Carmignani, M; Di Gioacchino, M

443

Chelating water-soluble polymers for waste minimization  

SciTech Connect

Within the DOE complex and in industry there is a tremendous need for advanced metal ion recovery and waste minimization techniques. This project sought to employ capabilities for ligand-design and separations chemistry in which one can develop and evaluate water- soluble chelating polymers for recovering actinides and toxic metals from various process streams. Focus of this work was (1) to develop and select a set of water-soluble polymers suitable for a selected waste stream and (2) demonstrate this technology in 2 areas: removal of (a) actinides and toxic RCRA metals from waste water and (b) recovery of Cu and other precious metals from industrial process streams including from solid catalysts and aqueous waste streams. The R&D was done in 4 phases for each of the 2 target areas: polymer synthesis for scaleup, equipment assembly, process demonstration at a DOE or industrial site, and advanced ligand/polymer synthesis. The TA- 50 site at Los Alamos was thought to be appropriate due to logistics and to its being representative of similar problems throughout the DOE complex.

Smith, B.; Cournoyer, M.; Duran, B.; Ford, D.; Gibson, R.; Lin, M. [Los Alamos National Lab., NM (United States); Meck, A.; Robinson, P. [N,P Energy, Inc. (United States); Robison, T. [Los Alamos National Lab., NM (United States)

1996-11-01

444

Supramolecular Structures of Zinc (II) (8-quinolinolato) Chelates  

SciTech Connect

We investigate the oligomeric purity and stability of zinc (8-quinolinolato) (Znq2) and its methylated derivatives (nMeq2Zn: n = 2, 4, 5) through a combination of theoretical modeling of oligomerizaton energetics leading to supramolecular structures and experimental size exclusion chromatography studies. Gas and solution phase (CHCl3) formation energies for dimeric, trimeric, and tetrameric species are reported. Favorable Gas phase thermodynamics were calculated and found to favor tetrameric structures for all Znq2 chelates ({approx} -50 kcal/mol for monomer dimerization to {approx} -35 kcal/mol for dimer dimerization), with the exception of 2Meq2Zn, which gave lower formation energies by 30-45% due to steric hindrance. Solvation model computations indicate that these energies are reduced by {approx}10-25% with the introduction of a dielectric medium. Computed structural parameters for the basic Zn-O core structure formed via bridging of phenolato oxygens do not change significantly as oligomer growth progresses. Size exclusion chromatography experiments of crystalline and amorphous films (vapor deposited) dissolved in CHCl3 or CHCl3/DMSO mixtures showed that the dominant species for Znq2, 4Meq2Zn, and 5Meq2Zn is tetrameric, but partial disassociation to monomers can occur in the presence of nucleophilic solvent. The sterically hindered 2Meq2Zn was monomeric in all solvent systems. Implications for organic light emitting devices using these materials are discussed.

Sapochak, Linda S.; Falkowitz, Anna; Ferris, Kim F.; Steinberg, Spencer; Burrows, Paul E.

2004-06-24

445

CONTROL OF CHELATOR-BASED UPSETS IN SURFACE FINISHING SHOP WASTE WATER TREATMENT SYSTEMS  

EPA Science Inventory

Actual surface finishing shop examples are used to illustrate the use of process chemistry understanding and analyses to identify immediate, interim and permanent response options for industrial waste water treatment plant (IWTP) upset problems caused by chelating agents. There i...

446

Mathematical modeling of the effects of aerobic and anaerobic chelate bioegradation on actinide speciation.  

National Technical Information Service (NTIS)

Biodegradation of natural and anthropogenic chelating agents directly and indirectly affects the speciation, and, hence, the mobility of actinides in subsurface environments. We combined mathematical modeling with laboratory experimentation to investigate...

J. E. Banaszak J. VanBriesen B. E. Rittmann D. T. Reed

1998-01-01

447

Iron Chelators: In vitro Inhibitory Effect on the Liver Stage of Rodent and Human Malaria.  

National Technical Information Service (NTIS)

The activity of desferrioxamine (Desferal) and desferrithiocin (a newly developed oral iron chelator) was evaluated against the liver stage of Plasmodium yoelii and P. falciparum in the rodent and the human hepatocyte in vitro culture system. The two iron...

E. Stahel D. Nazier A. Guillouzo F. Miltgen I. Landau

1988-01-01

448

Click-to-Chelate: development of technetium and rhenium-tricarbonyl labeled radiopharmaceuticals.  

PubMed

The Click-to-Chelate approach is a highly efficient strategy for the radiolabeling of molecules of medicinal interest with technetium and rhenium-tricarbonyl cores. Reaction of azide-functionalized molecules with alkyne prochelators by the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC; click reaction) enables the simultaneous synthesis and conjugation of tridentate chelating systems for the stable complexation of the radiometals. In many cases, the functionalization of (bio)molecules with the ligand system and radiolabeling can be achieved by convenient one-pot procedures. Since its first report in 2006, Click-to-Chelate has been applied to the development of numerous novel radiotracers with promising potential for translation into the clinic. This review summarizes the use of the Click-to-Chelate approach in radiopharmaceutical sciences and provides a perspective for future applications. PMID:23481882

Kluba, Christiane A; Mindt, Thomas L

2013-03-12

449

Chelation and Effectiveness of Salicylate Related Compounds on Pyresis, Sedimentation Rate and Hematocrit.  

National Technical Information Service (NTIS)

The mechanism of action and identification of sites of salicylates and related compounds in antipyresis were studied. Structure-activity investigations of antipyresis were made using Sprague-Dawley rats. Results showed copper was chelated by the salicylat...

J. Schubert M. W. Rosenthal J. F. Fried

1984-01-01

450

Behavioral Consequences of Chelator Administration in Acute Cadmium Toxicity (Journal Version).  

National Technical Information Service (NTIS)

The conditioned flavor-aversion paradigm was used to assess the toxicity of acutely administered cadmium and the interaction of cadmium with the heavy-metal chelating agents dimercaprol (BAL) and dimercaptosuccinic acid (DMSA). Shortly after consuming sac...

D. B. Peele J. D. Farmer R. C. MacPhail

1988-01-01