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1

Effect of supplementation with ferrous sulfate or iron bis-glycinate chelate on ferritin concentration in Mexican schoolchildren: a randomized controlled trial  

PubMed Central

Background Iron deficiency is one of the most common nutritional deficiencies worldwide. It is more prevalent when iron requirements are increased during pregnancy and during growth spurts of infancy and adolescence. The last stage in the process of iron depletion is characterized by a decrease in hemoglobin concentration, resulting in iron deficiency anemia. Iron deficiency, even before it is clinically identified as anemia, compromises the immune response, physical capacity for work, and intellectual functions such as attention level. Therefore, interventions addressing iron deficiency should be based on prevention rather than on treatment of anemia. The aim of this study was to compare short- and medium-term effects on ferritin concentration of daily supplementation with ferrous sulfate or iron bis-glycinate chelate in schoolchildren with iron deficiency but without anemia. Methods Two hundred schoolchildren from public boarding schools in Mexico City who had low iron stores as assessed by serum ferritin concentration but without anemia were randomly assigned to a daily supplement of 30 mg/day of elemental iron as ferrous sulfate or iron bis-glycinate chelate for 12 weeks. Iron status was evaluated at baseline, one week post-supplementation (short term), and 6 months (medium term) after supplementation. Results Ferritin concentration increased significantly between baseline and post-supplementation as well as between baseline and 6 months after supplementation. One week post-supplementation no difference was found in ferritin concentration between iron compounds, but 6 months after supplementation ferritin concentration was higher in the group that received bis-glycinate chelate iron. However, there is no difference in the odds for low iron storage between 6 months after supplementation versus the odds after supplementation; nor were these odds different by type of supplement. Hemoglobin concentration did not change significantly in either group after supplementation. Conclusions Supplementing with 30 mg/d of elementary iron, either as ferrous sulfate or iron bis-glycinate chelate for 90 days, showed positive effects on increasing ferritin concentration in schoolchildren with low iron stores, and this effect persisted 6 months after supplementation.

2014-01-01

2

Bispidine platform grants full control over magnetic state of ferrous chelates in water.  

PubMed

A bicyclic ligand platform for iron(II), which allows total control over the complex's magnetic properties in aqueous solution simply by varying one of the six coordination sites of the bispidine ligand, is reported. To achieve this, an efficient synthetic route to an N5 bispidine framework (ligand L4) that features an unsubstituted N-7 site is established. Then, by choosing appropriate N-7-coordinating substituents, the spin state of choice can be imposed on the corresponding ferrous complexes under environmentally relevant conditions in water and near-room temperature. Importantly, the first low-spin and diamagnetic iron(II) chelates in the bispidine series, both in the solid state and in aqueous solution, are reported. The eradication of head-on steric clashes between pendent coordinating arms is at the origin of this success. A new pair of constitutionally similar ferrous coordination compounds of a multidentate ligand system is obtained, which exhibits a distinctly binary (off-on) magnetic relationship. The new synthetic intermediate L4 may be substituted in just one step by any desired pendent arm, thus allowing access to complexes with finely tuned magnetic properties. PMID:23670831

Kolanowski, Jacek Lukasz; Jeanneau, Erwann; Steinhoff, Robert; Hasserodt, Jens

2013-07-01

3

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

4

Radical quenching activity, ferric-reducing antioxidant power, and ferrous ion-chelating capacity of 16 Ballota species and their total phenol and flavonoid contents.  

PubMed

The ethyl acetate, methanol, and water extracts of 16 Ballota species (Family Lamiaceae)-Ballota acetabulosa, Ballota antalyanse, Ballota cristata, Ballota glandulosissima, Ballota inaequidens, Ballota larendana, Ballota latibracteolata, Ballota macrodonta, Ballota nigra ssp. anatolica, B. nigra ssp. foetida, B. nigra ssp. nigra, B. nigra ssp. uncinata, Ballota pseudodictamnus ssp. lycia, Ballota rotundifolia, Ballota saxatilis ssp. brachyodonta, and B. saxatilis subsp. saxatilis-were screened for their 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical quenching, ferric-reducing antioxidant power, and ferrous ion-chelating capacity at 1mg/mL. Hispanolone, a major diterpene found in the Ballota genus, was also tested in the same manner. Total phenol and flavonoid contents of the extracts were determined by Folin-Ciocalteau and AlCl(3) reagents, respectively. The extracts showed insignificant quenching activity against DPPH radical, but they had moderate antioxidant activity (0.597 ± 0.03 to 1.342 ± 0.01) in the ferric-reducing test compared to chlorogenic acid (the reference compound) (3.618 ± 0.01). All of the extracts (ranging from 65.1 ± 0.64% to 96.3 ± 0.09%) and hispanolone (97.31 ± 0.30%) exerted a remarkable ferrous ion-chelating effect. The highest total phenol (gallic acid equivalent) and flavonoid (quercetin equivalent) contents were found in the ethyl acetate extract of B. glandulosissima (393.7 ± 3.03 and 140.6 ± 1.97 mg/g of extract, respectively). Therefore, Ballota species could be a good source of natural preservatives in foodstuffs. PMID:21091260

Erdogan-Orhan, Ilkay; Sever-Y?lmaz, Betül; Altun, M Levent; Saltan, Gülçin

2010-12-01

5

Ferrous Metallurgy.  

National Technical Information Service (NTIS)

The article reviews the performance of the ferrous metallurgy industry in 1972. Areas of non-fulfillment of plans and other shortcomings are noted. The program for opening up new metallurgical capacities during 1971 and 1972 was not fulfilled. Last year t...

1973-01-01

6

Synthesis, growth and characterization of organic nonlinear optical bis-glycine maleate (BGM) single crystals  

NASA Astrophysics Data System (ADS)

A new organic compound of bis-glycine maleate was synthesized in the alkaline medium of 10% ammonium hydroxide solution. The bulk single crystals of Bis-Glycine Maleate (BGM) have been grown by slow cooling method. The grown crystals were characterized by employing single crystal and powder X-ray diffraction, Fourier transform infrared, optical absorption spectral studies and thermo gravimetric analysis. The microhardness studies confirmed that the BGM has a fairly high Vicker's hardness number value (41 kg mm -2) in comparison to other organic NLO crystals. Second harmonic generation efficiency of the crystal measured by Kurtz-Perry powder method using Nd:YAG laser is found to be comparable to that of potassium dihydrogen phosphate (KDP). Frequency dependent dielectric studies were carried out along the major growth axis.

Balasubramanian, D.; Murugakoothan, P.; Jayavel, R.

2010-05-01

7

Deoxyribonucleic acid-protein and deoxyribonucleic acid interstrand cross-links induced in isolated chromatin by hydrogen peroxide and ferrous ethylenediaminetetraacetate chelates  

SciTech Connect

DNA-protein and DNA interstrand cross-links were induced in isolated chromatin after treatment with H/sub 2/O/sub 2/ and ferrous ethylenediaminetetraacetate (EDTA). Retention of DNA on membrane filters after heating of chromatin in a dissociating solvent indicated the presence of a stable linkage between DNA and protein. Treatment of protein-free DNA with H/sub 2/O/sub 2//Fe/sup 2 +/-EDTA did not result in enhanced filter retention. Incubation of cross-linked chromatin with proteinase K completely eliminated filter retention. Resistance to S/sub 1/ nuclease after a denaturation-renaturation cycle was used to detect DNA interstrand cross-links. Heating the treated chromatin at 45/sup 0/C for 16 h and NaBH/sub 4/ reduction enhanced the extent of interstrand cross-linking. The following data are consistent with, but do not totally prove, the hypothesis that cross-links are induced by hydroxyl radicals generated in Fenton-type reactions: (1) cross-linking was inhibited by hydroxyl radical scavengers; (2) the degree of inhibition of DNA interstrand cross-links correlated very closely with the rate constants of the scavengers for reaction with hydroxyl radicals; (3) cross-linking was eliminated or greatly reduced by catalase; (4) the extent of cross-linking was directly related to the concentration of Fe/sup 2 +/-EDTA. Partial inhibition of cross-linking by superoxide dismutase indicates that super-oxide-driven Fenton chemistry is involved. The data indicate that DNA cross-linking may play a role in the manifestation of the biological activity of agents of systems that generate reactive hydroxyl radicals.

Lesko, S.A.; Drocourt, J.; Yang, S.

1982-01-01

8

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 13×6×4 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 3.1×103/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

9

Preparation of Ferrous Ferricyanide  

Microsoft Academic Search

WE have synthesized ferrous ferricyanide, Fe3+2 (FeIII (CN)6)2 by vacuum pyrolysis of Prussian blue (ferric ferrocyanide, Fe4+3 (FeII (CN)6)3)-see refs. 1 and 2. This completes the preparation of the curious quartet of iron-iron cyanides. The cation in each case is high spin ferrous (2+) or ferric (3+) iron, and the cyanide-surrounded anion is low spin ferrous (II) or ferric (III)

D. S. Murty

1971-01-01

10

Enhanced flue gas denitrification using ferrous EDTA and a polyphenolic compound having combined antioxidant and reducing properties  

SciTech Connect

Previous work in this laboratory has involved studying the possibility of combined NO{sub x}/SO{sub x} scrubbing using various aqueous chemistries with a metal chelate additive. Recently, we have focused our work on the metal chelate ferrous*EDTA. A major problem encountered in the practical application of ferrous*EDTA is that the ferrous ion has been found to oxidize to the corresponding ferric species leading to a decrease of the NO{sub x} removal for the scrubbing solution containing the additive. We have found that addition of a polyphenolic compound leads to a sustained high NO{sub x} removal under various oxidizing conditions. We believe that the improved performance of ferrous*EDTA is due to the known capabilities of these organic compounds to both inhibit oxidation of ferrous chelates by dissolved oxygen and to rapidly reduce any ferric ions back to the original ferrous species. 5 refs., 7 figs.

Mendelsohn, M.H.; Harkness, J.B.L.

1990-01-01

11

Chelation Therapy  

MedlinePLUS

... none Scientific/medical name(s): ethylene diamine tetraacetic acid (EDTA), edetate sodium Description Chelation therapy is a mainstream ... involves the injection of ethylene diamine tetraacetic acid (EDTA), a chemical that binds, or chelates, heavy metals, ...

12

21 CFR 73.160 - Ferrous gluconate.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Ferrous gluconate. 73.160 Section 73.160 Food...CERTIFICATION Foods § 73.160 Ferrous gluconate. (a) Identity. The color additive ferrous gluconate is the ferrous gluconate...

2009-04-01

13

21 CFR 73.160 - Ferrous gluconate.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Ferrous gluconate. 73.160 Section 73.160 Food...CERTIFICATION Foods § 73.160 Ferrous gluconate. (a) Identity. The color additive ferrous gluconate is the ferrous gluconate...

2010-04-01

14

A bioavailability study comparing two oral formulations containing zinc (Zn bis-glycinate vs. Zn gluconate) after a single administration to twelve healthy female volunteers.  

PubMed

As the current nutritional zinc intake frequently falls outside the Dietary Reference Intake (DRI) and as zinc is an essential trace mineral involved in the function of many enzymes, zinc supplementation has been recommended to prevent or treat the adverse effects of zinc deficiency. The aim of the present study was to compare the oral bioavailability of zinc bis-glycinate (a new formulation) with zinc gluconate (reference formulation). A randomized, cross-over study was conducted in 12 female volunteers. The two products were administrated orally at the single dose of 15 mg (7.5 mg x 2), with a 7-day wash-out period between the two tests. Serum concentrations of zinc were assayed by a validated inductively coupled plasma optical emission spectrometry (ICP-OES) method and C(max), T(max), and areas-under-the-curve (AUCs) were determined. The comparison between the two treatments was performed by comparing the C(max), AUC(t), and AUC(inf) using an analysis of variance followed by the calculation of the 90% confidence intervals of the ratio test/reference. Bis-glycinate administration was safe and well tolerated and bis-glycinate significantly increased the oral bioavailability of zinc (+43.4%) compared with the gluconate. PMID:18271278

Gandia, Peggy; Bour, Dorothée; Maurette, Jean-Marc; Donazzolo, Yves; Duchène, Patrick; Béjot, Marie; Houin, Georges

2007-07-01

15

21 CFR 184.1308 - Ferrous gluconate.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Ferrous gluconate. 184.1308 Section 184.1308 Food and...Substances Affirmed as GRAS § 184.1308 Ferrous gluconate. (a) Ferrous gluconate (iron (II) gluconate dihydrate, C12...

2009-04-01

16

21 CFR 184.1308 - Ferrous gluconate.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2009-04-01 true Ferrous gluconate. 184.1308 Section 184.1308 Food and...Substances Affirmed as GRAS § 184.1308 Ferrous gluconate. (a) Ferrous gluconate (iron (II) gluconate dihydrate, C12...

2010-01-01

17

Machine Casting of Ferrous Alloys.  

National Technical Information Service (NTIS)

Due to the lack of economic permanent die materials for use in Hipocasting ferrous alloys, three innovative approaches for creating a mold cavity for use in machine casting of ferrous alloys were explored. They were: use of liquid metal cooling of a thin ...

G. D. Chandley G. Scholl

1975-01-01

18

Experimental and theoretical studies on bis(glycine) lithium nitrate (BGLiN): A physico-chemical approach  

NASA Astrophysics Data System (ADS)

Good quality and bulk size single crystal (size: 20×13×8 mm3) of bis(glycine) lithium nitrate (BGLiN) was grown by a slow evaporation solution technique from the aqueous solutions at constant temperature i.e. 27 °C using synthesized materials. Crystal system and lattice parameters were determined by single crystals as well as powder X-ray diffraction analysis. The lattice parameters of the titled compound are a=10.0223 Å, b=5.0343 Å, c=17.0510 Å, and V=860.312 Å3 and it crystallized in an orthorhombic system with space group Pca21 obtained by single crystal XRD. Elemental composition was confirmed by energy dispersive X-ray spectroscopic analysis. Optical absorption spectrum was recorded and various optical parameters such as optical transmission (~60%), and optical band gap (4.998 eV) were calculated. Photoluminescence study shows that the grown crystal is free from major defects. Crystalline perfection of the grown crystal was assessed and found good. Ground state optimized geometry has been obtained by using DFT with 6-31G(d,p) basis set. HOMO and LUMO energy gap was found to be 6.01 eV and dipole moment was 1.65 D.

Shkir, Mohd.; Abbas, Haider; Kumar, Sumeet; Bhagavannarayana, G.; AlFaify, S.

2014-08-01

19

Machine Casting of Ferrous Alloys.  

National Technical Information Service (NTIS)

This is the first semi-annual report describing research conducted at the University of Illinois at Urbana-Champaign as part of a joint university-industry research program on machine casting of ferrous alloys. During the six months covered by this report...

D. G. Backman R. Mehrabian R. J. Lauf S. D. E. Ramati Y. V. Murty

1976-01-01

20

Iron in ferrous gluconate and Ascofer®  

NASA Astrophysics Data System (ADS)

Ferrous gluconate and antianemic medicament Ascofer® were investigated with Mössbauer spectroscopy in order to determine forms of iron ions present in both types of samples. Room temperature spectra gave a clear evidence that two phases of iron were present viz. ferrous (Fe2+) as a major one with a contribution of ~85 ±5 %, and ferric (Fe3+) whose contribution was found to be ~15±5 %. Ferrous ions were shown to occupy at least two different sites.

Gozdyra, R.; Dubiel, S. M.; Cie?lak, J.

2010-03-01

21

The Rules of Ferrous Metallurgy  

PubMed Central

The ways in which the sciences have been delineated and categorized throughout history provide insights into the formation, stabilization, and establishment of scientific systems of knowledge. The Dresdener school’s approach for explaining and categorizing the genesis of the engineering disciplines is still valid, but needs to be complemented by further-reaching methodological and theoretical reflections. Pierre Bourdieu’s theory of social practice is applied to the question of how individual agents succeed in influencing decisively a discipline’s changing object orientation, institutionalisation and self-reproduction. Through the accumulation of social, cultural and economic capital, they succeed in realising their own organisational ideas and scientific programs. Key concepts for the analysis include the struggle for power and resources, monopolies of interpretation, and the degree of autonomy. A case study from the Aachener Technische Hochschule shows that the consolidation of ferrous metallurgy can be conceived as a symbolical struggle between Fritz Wüst, professor for ferrous metallurgy, and the German Iron and Steel Institute, leading to a construction of a system of differences in which scientists accepted being scientists rather than entrepreneurs, and entrepreneurs accepted becoming entrepreneurs and renounced science.

2010-01-01

22

21 CFR 184.1315 - Ferrous sulfate.  

Code of Federal Regulations, 2010 CFR

...consists primarily of ferrous sulfate monohydrate (CAS Reg. No. 17375-41-6) with varying amounts of ferrous sulfate tetrahydrate (CAS Reg. No. 20908-72-9) and occurs as a grayish-white to buff-colored powder. (b) The...

2009-04-01

23

21 CFR 184.1315 - Ferrous sulfate.  

Code of Federal Regulations, 2010 CFR

...consists primarily of ferrous sulfate monohydrate (CAS Reg. No. 17375-41-6) with varying amounts of ferrous sulfate tetrahydrate (CAS Reg. No. 20908-72-9) and occurs as a grayish-white to buff-colored powder. (b) The...

2010-01-01

24

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

25

The Chelate Effect Redefined.  

ERIC Educational Resources Information Center

Discusses ambiguities of the accepted definition of the chelate effect, suggesting that it be defined in terms of experimental observation rather than mathematical abstraction. Indicates that the effect depends on free energy change in reaction, ligand basicity, pH of medium, type of chelates formed, and concentration of ligands in solution. (JN)

da Silva, J. J. R. Frausto

1983-01-01

26

46 CFR 148.260 - Ferrous metal.  

Code of Federal Regulations, 2013 CFR

...must be compacted in the hold as frequently as practicable with a bulldozer or other means that provides equivalent surface compaction; (5) No other material may be loaded in a hold containing ferrous metal unlessâ (i) The material to be...

2013-10-01

27

Photomixotrophic growth of Rhodobacter capsulatus SB1003 on ferrous iron.  

PubMed

This study investigates the role iron oxidation plays in the purple non-sulfur bacterium Rhodobacter capsulatus SB1003. This organism is unable to grow photoautotrophically on unchelated ferrous iron [Fe(II)] despite its ability to oxidize chelated Fe(II). This apparent paradox was partly resolved by the discovery that SB1003 can grow photoheterotrophically on the photochemical breakdown products of certain ferric iron-ligand complexes, yet whether it could concomitantly benefit from the oxidation of Fe(II) to fix CO(2) was unknown. Here, we examine carbon fixation by stable isotope labeling of the inorganic carbon pool in cultures growing phototrophically on acetate with and without Fe(II). We show that R. capsulatus SB1003, an organism formally thought incapable of phototrophic growth on Fe(II), can actually harness the reducing power of this substrate and grow photomixotrophically, deriving carbon both from organic sources and from fixation of inorganic carbon. This suggests the possibility of a wider occurrence of photoferrotrophy than previously assumed. PMID:22212713

Kopf, S H; Newman, D K

2012-05-01

28

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

29

Ferrous iron-sulfide interactions in anoxic hypolimnetic waters  

Microsoft Academic Search

Seasonal polarographic measurements of sulfide and ferrous iron concentrations in the hypolimnion of a thermally stratified lake show that the inorganic chemistry in the waters nearest the sediment is dominated by ferrous sulfide precipitation. There is no evidence for supersaturation or organic interactions. The solubility product for ferrous sulfide at 10°C and near zero ionic strength was 0.9-2.0*10-\\

W. DAVISON; S. I. HEANEY

1978-01-01

30

21 CFR 184.1307a - Ferrous ascorbate.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Ferrous ascorbate. 184.1307a Section 184.1307a Food...Substances Affirmed as GRAS § 184.1307a Ferrous ascorbate. (a) Ferrous ascorbate (CAS Reg. No. 24808-52-4) is a...

2009-04-01

31

Ferrous-Ferric Ion exchange dosemeter.  

PubMed

In this work a three-dimensional ferrous-ferric ion exchange dosemeter is proposed and the dose response measured. The dosemeter consists of strong acid cation exchange resin beads in the H form in water. Amberlyst 15 Wet beads with a harmonic mean diameter of 0.600-0.850 mm were prepared by soaking them in an aqueous solution of ferrous ammonium sulphate to exchange ferrous ions for H(+) ions. The beads were rinsed with distilled water and packed in glass vials. Sets of samples with ferrous ion concentrations of 0.5 and 1.0 mM were dosed with 6 MV X rays from a Varian 2100C linac. The spin-lattice relaxation time constants (T1) for the samples were measured using an Apollo spectrometer (Tecmag, Houston, TX) interfaced to a 1.5 T magnet (Magnex, Abingdon, UK). Each sample had two T1 values; a long T1 at 1200 ms that did not significantly change with dose and a short T1 that ranged from 56 ms at 0 Gy to 36 ms at 100 Gy. The R1 vs. dose responses were linear with slopes of 0.066 and 0.079 s(-1) Gy(-1). PMID:16644977

Bauhs, John A; Hammer, Bruce E

2006-01-01

32

Combined SOâ\\/NOâ control using ferrous·EDTA and a secondary additive in a lime-based aqueous scrubber system  

Microsoft Academic Search

Integration of NOâ 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·EDTA in various wet FGD chemistries, to promote combined SOâ\\/NOâ scrubbing. A major process problem is oxidation of the iron to the ferric species, leading to a significant decrease in NOâ-removal

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

1991-01-01

33

Rigid bifunctional chelating agents  

DOEpatents

Bicyclo[2.2.2] octane-2,3 diamine-N,N,N`,N`-tetraacetic acids (BODTA) and bicyclo[2.2.1] heptane-2,3 diamine-N,N,N`,N`-tetraacetic acid (BHDTA) are chelating agents useful in forming detectably labeled bioconjugate compounds for diagnostic and therapeutic purposes. New compounds and processes of forming BODTA and BHDTA are disclosed. Radioimmunoconjugates of the present invention show high and prolonged tumor uptake with low normal tissue uptakes.

Sweet, M.P.; Mease, R.C.; Srivastava, S.C.

1998-07-21

34

Metal Chelates of Curcuminoids  

Microsoft Academic Search

Curcuminoids, a group of structurally related 1.3-dicarbonyl compounds. are the most important physiologically active components present in the traditional herbaceous medicinal plant oriental turmeric (Curcuma longa Linn., Zingiberaceae family). Nickel(II). copper(II), zinc(II) and palladium(II) chelates of synthetic analogues of these 1,7-diatyl-1.6-heptadiene-3.5-diones have been synthesized. UV, IR, H and C NMR and mass spectral data of the ML2 complexes clearly indicate

K. Krishnankutty; P. Venugopalan

1998-01-01

35

Rigid bifunctional chelating agents  

DOEpatents

Bicyclo›2.2.2! octane-2,3 diamine-N,N,N',N'-tetraacetic acids (BODTA) and bicyclo›2.2.1! heptane-2,3 diamine-N,N,N',N'-tetraacetic acid (BHDTA) are chelating agents useful in forming detectably labeled bioconjugate compounds for diagnostic and therapeutic purposes. New compounds and processes of forming BODTA and BHDTA are disclosed. Radioimmunoconjugates of the present invention show high and prolonged tumor uptake with low normal tissue uptakes.

Sweet, Mark P. (Coram, NY); Mease, Ronnie C. (Fairfax, VA); Srivastava, Suresh C. (Setauket, NY)

1998-07-21

36

Rigid bifunctional chelating agents  

DOEpatents

Bicyclo[2.2.2]octane-2,3 diamine-N,N,N',N'-tetraacetic acids (BODTA) and bicyclo[2.2.1]heptane-2,3 diamine-N,N,N',N'-tetraacetic acid (BHDTA) are chelating agents useful in forming detectably labeled bioconjugate compounds for diagnostic and therapeutic purposes. New compounds and processes of forming BODTA and BHDTA are disclosed. Radioimmunoconjugates of the present invention show high and prolonged tumor uptake with low normal tissue uptakes.

Sweet, Mark P. (Coram, NY); Mease, Ronnie C. (Fairfax, VA); Srivastava, Suresh C. (Setauket, NY)

2000-02-08

37

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

38

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, Milton (12833 S. 82nd Ct., Palos Park, IL 60464); Sinha, Shome N. (5748 Drexel, 2A, Chicago, IL 60637)

1990-01-01

39

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

40

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.

1990-05-15

41

Surface modification of ferrous alloys with boron  

Microsoft Academic Search

This paper presents the effects of boronizing on ferrous alloys such as plain-carbon steel AISI 1018, high-strength alloy\\u000a steel AISI 4340, and austenitic stainless steel AISI 304. The coatings were produced by thermochemical treatment with powder\\u000a mixtures at temperatures of 850C for 4 h. The microstructure of obtained coatings was investigated, the microhardness was\\u000a measured, and the corrosion resistance and

Roumiana S. Petrova; Naruemon Suwattananont

2005-01-01

42

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

43

Recycling ferrous sulfate via super-oxidant synthesis  

Microsoft Academic Search

Hydrated ferrous sulfate, a by-product of the titanium-dioxide and steel-surface-treatment industries, is usually disposed\\u000a of as waste at a significant extra cost for these industries. Due to tight environmental regulations in the European countries,\\u000a waste disposal of ferrous sulfate will not be an acceptable solution in the near future. Consequently, the waste will have\\u000a to be treated. Recently, ferrous sulfate

N. Kanari; O. Evrard; N. Neveux; L. Ninane

2001-01-01

44

Antioxidant Potential ofEcklonia cavaon Reactive Oxygen Species Scavenging, Metal Chelating, Reducing Power and Lipid Peroxidation Inhibition  

Microsoft Academic Search

The antioxidative potential of different fractions (respective organic and aqueous fractions of n-hexane, chloroform and ethyl acetate) of 70% methanol extract of Ecklonia cava(a brown seaweed) was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion, hydrogen peroxide, hydroxyl radical, nitric oxide, ferrous ion chelating, reducing power and lipid peroxidation inhibition (conjugated diene hydroperoxide and thiobarbituric acid-reactive substances production) assays. The 70% methanol

Mahinda Senevirathne; Soo-Hyun Kim; Nalin Siriwardhana; Jin-Hwan Ha; Ki-Wan Lee; You-Jin Jeon

2006-01-01

45

Ferrous-activated persulfate oxidation of arsenic(III) and diuron in aquatic system.  

PubMed

In situ chemical oxidation (ISCO) can be an effective technology for the remediation of soil and groundwater polluted by organic and inorganic contaminants. This study investigated the oxidation of arsenic(III) (As(III)) and diuron using ferrous activated persulfate-based ISCO. The results indicated that Fe(II)/persulfate oxidation could be an effective method to oxidize As(III) and diuron. Effects of pH, S2O8(2-) and Fe(II) amounts on the destruction of As(III) and diuron were examined in batch experiments. Acidic conditions favored the removal of As(III) and diuron. Four chelating agents, citric acid (CA), Na2S2O3, diethylene triamine pentaacetic acid (DTPA) and ethylene diamine tetraacetic acid disodium (EDTA-Na2) were used in attempt to maintain the quantity of ferrous ion in solution. In our experiments, CA and Na2S2O3 were found to be more effective than DTPA and EDTA-Na2. Our results also revealed a widely practical prospect of inorganic chelating agent Na2S2O3. Hydroxyl and sulfate radical were determined to play key roles in the oxidation process by using ethanol and tertiary butanol as molecular probes. Oxidation of As(III) yielded As(V) via the electron-transfer reaction. In the oxidation process of diuron, a stepwise nucleophilic substitution of chlorine by hydroxyl and a stepwise oxidation process of the methyl on the dimethylurea group by hydroxyl and sulfate radical were proposed. PMID:24220194

Zhou, Lei; Zheng, Wei; Ji, Yuefei; Zhang, Jinfeng; Zeng, Chao; Zhang, Ya; Wang, Qi; Yang, Xi

2013-12-15

46

Polycatecholamide chelating agents  

DOEpatents

Novel polybenzamide compounds useful for in vitro or in vivo chelation are described. The compounds have the formula ##STR1## 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, Frederick L. (Martinez, CA); Raymond, Kenneth N. (Berkeley, CA)

1984-01-01

47

Polycatecholamide chelating agents  

DOEpatents

Novel polybenzamide compounds useful for in vitro or in vivo chelation are described. The compounds have the formula given in patent. 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. No Drawings

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

1984-04-10

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

A case of ferrous sulfate addition enhancing chalcopyrite leaching  

Microsoft Academic Search

It is generally accepted that ferric ions as an oxidant are effective for leaching chalcopyrite but ferrous ions contribute to the leaching only as a source of ferric ions. However, this paper found that several chalcopyrite samples were more effectively leached in ferrous sulfate solution than in ferric sulfate solution. Chalcopyrite samples from four different sources were leached in 0.1

Naoki Hiroyoshi; Masahiko Hirota; Tsuyoshi Hirajima; Masami Tsunekawa

1997-01-01

50

Continuous ferrous iron biooxidation in flooded packed bed reactors  

Microsoft Academic Search

In this paper the biological ferrous iron oxidation in flooded packed bed reactors is studied. Bacterial oxidation of ferrous iron is a potential industrial process for the treatment of acid mine drainage and in the regeneration of ferric iron as a leaching agent in hydrometallurgical processes.The aim of this work is the development of a reactor capable of attaining the

A. Mazuelos; R. Romero; I. Palencia; N. Iglesias; F. Carranza

1999-01-01

51

High efficiency reactor for the biooxidation of ferrous iron  

Microsoft Academic Search

The biooxidation of ferrous iron is a potential industrial process in the regeneration of ferric iron, in hydrometallurgical leaching operations and in the removal of H2S in combustible gases. Another field of application is the treatment of acid mine drainage water. The aim of this work was the design of a continuous reactor for a high efficiency ferrous iron biooxidation

A Mazuelos; F Carranza; I Palencia; R Romero

2000-01-01

52

21 CFR 184.1307a - Ferrous ascorbate.  

Code of Federal Regulations, 2013 CFR

...ascorbate. (a) Ferrous ascorbate (CAS Reg. No. 24808-52-4) is a reaction product of ferrous hydroxide and ascorbic acid. It is a blue-violet product containing 16 percent iron. (b) The ingredient must be of a purity suitable...

2013-04-01

53

Iron fortification of infant cereals: a proposal for the use of ferrous fumarate or ferrous succinate13  

Microsoft Academic Search

ABSTRACI' Hemoglobin-repletion tests in rats, organoleptic studies, and iron-absorption studies in humans were used to search for Fe sources with high bioavailability that could be added to infant cereals as alternatives to the Fe compounds currently used for fortification. From rat and organoleptic studies on 1 1 alternative Fe sources, ferrous fumarate, ferrous succi- nate, and ferric saccharate were selected

Richard F Hurrell; Diane E Furniss; Joseph Burn; Paul Whittaker; Sean R Lynch; James D Cook

54

Fast Ferrous Heme-NO Oxidation in Nitric Oxide Synthases  

PubMed Central

During catalysis, the heme in nitric oxide synthase (NOS) binds NO before releasing it to the environment. Oxidation of the NOS ferrous heme-NO complex by O2 is key for catalytic cycling, but the mechanism is unclear. We utilized stopped-flow methods to study reaction of O2 with ferrous heme-NO complexes of the inducible and neuronal NOS enzymes. We found that the reaction does not involve heme-NO dissociation, but instead proceeds by a rapid, direct reaction of O2 with the ferrous heme-NO complex. This behavior is novel and may distinguish heme-thiolate enzymes like NOS from related heme proteins.

Tejero, Jesus; Santolini, Jerome; Stuehr, Dennis J.

2009-01-01

55

Laminated Ferrous Composites Based on Ultrahigh Carbon (UHC) Steels.  

National Technical Information Service (NTIS)

Ferrous laminated composites based on ultrahigh carbon (UHC) steel have been successfully manufactured by roll bonding below the Al transition temperature. Three unique mechanical property characteristics have been achieved by such lamination. First, rema...

O. D. Sherby J. Wadsworth D. W. Kum G. Deahn J. Whittenauer

1987-01-01

56

Sludge Generation from Ferrous/Sulfide Chromium Treatment.  

National Technical Information Service (NTIS)

The reaction pH and reduction chemical can drastically effect the volume of wastewater treatment sludges produced in chromium treatment. Experiments at the Air Force Engineering and Services Laboratory have shown that mixing sodium sulfide and ferrous chl...

J. R. Aldrich

1984-01-01

57

Preparation and Characterization of Cast Ferrous Metal Matrix Composites  

NASA Astrophysics Data System (ADS)

TiC/SiC reinforced cast ferrous composites have been prepared by smelting red mud—30 pct charcoal briquettes in a 20-kg basic lined, single-phase direct arc furnace. Elements like silicon, aluminum, zirconium, and so on are also reduced from their respective oxides in the red mud and dissolved in the ferrous matrix. TiC/SiC particulates in the composite grow in a typical spiraling fashion.

Dash, R. R.; Chakrabarti, A. K.; Mukherjee, P. S.

2012-02-01

58

Technetium behavior in sulfide and ferrous iron solutions  

Microsoft Academic Search

Pertechnetate oxyanion (⁹⁹TcOâ⁻), a potentially mobile species in leachate from a breached radioactive waste repository, was removed from a brine solution by precipitation with sulfide, iron, and ferrous sulfide at environmental pH's. Maghemite (..gamma..-FeâOâ) and geothite (..cap alpha..-FeOOH) were the dominant minerals in the precipitate obtained from the TcOâ⁻-ferrous iron reaction. The observation of small particle size and poor crystallinity

S. Y. Lee; E. A. Bondietti

1982-01-01

59

Technetium behavior in sulfide and ferrous iron solutions  

Microsoft Academic Search

Pertechnetate oxyanion (⁹⁹TcOâ⁻), a potentially mobile species in leachate from a breached radioactive waste repository, was removed from a brine solution by precipitation with sulfide, iron, and ferrous sulfide at environmental pH's. Maghemite (..gamma..-FeâOâ) and goethite (..cap alpha..-FeOOH) were the dominant minerals in the precipitate obtained from the TcOâ⁻-ferrous iron reaction. The observation of small particle size and poor crystallinity

S. Y. Lee; E. A. Bondietti

1983-01-01

60

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

61

Pulsed laser surface hardening of ferrous alloys.  

SciTech Connect

A high power pulsed Nd:YAG laser and special optics were used to produce surface hardening on 1045 steel and gray cast iron by varying the process parameters. Unlike CO{sub 2} lasers, where absorptive coatings are required, the higher absorptivity of ferrous alloys at the Nd:YAG laser wavelength eliminates the necessity of applying a coating before processing. Metallurgical analysis of the treated tracks showed that very fine and hard martensitic microstructure (1045 steel) or inhomogeneous martensite (gray cast iron) were obtained without surface melting, giving maximum hardness of HRC 61 and HRC 40 for 1045 steel and gray cast iron respectively. The corresponding maximum case depths for both alloys at the above hardness are 0.6 mm. Gray cast iron was more difficult to harden without surface melting because of its lower melting temperature and a significantly longer time-at-temperature required to diffuse carbon atoms from the graphite flakes into the austenite matrix during laser heating. The thermal distortion was characterized in term of flatness changes after surface hardening.

Xu, Z.; Reed, C. B.; Leong, K. H.; Hunter, B. V.

1999-09-30

62

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

63

Natural chelating agents for radionuclide decorporation  

DOEpatents

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) [East Moriches, NY

1988-01-01

64

Technetium behavior in sulfide and ferrous iron solutions  

SciTech Connect

Pertechnetate oxyanion (/sup 99/TcO/sub 4//sup -/), a potentially mobile species in leachate from a breached radioactive waste repository, was removed from a brine solution by precipitation with sulfide, iron, and ferrous sulfide at environmental pH's. Maghemite (..gamma..-Fe/sub 2/O/sub 3/) and geothite (..cap alpha..-FeOOH) were the dominant minerals in the precipitate obtained from the TcO/sub 4//sup -/-ferrous iron reaction. The observation of small particle size and poor crystallinity of the minerals formed in the presence of Tc suggested that the Tc was incorporated into the mineral structure after reduction to a lower valence state. Amorphous ferrous sulfide, an initial phase precipitating in the TcO/sub 4//sup -/-ferrous iron-sulfide reaction, was transformed to goethite and hematite (..cap alpha..-Fe/sub 2/O/sub 3/) on aging. The black precipitate obtained from the TcO/sub 4//sup -/-sulfide reaction was poorly crystallized technetium sulfide (Tc/sub 2/S/sub 7/) which was insoluble in both acid and alkaline solution in the absence of strong oxidents. The results suggested that ferrous- and/or sulfide-bearing groundwaters and minerals in host rocks or backfill barriers could reduce the mobility of Tc through the formation of less-soluble Tc-bearing iron and/or sulfide minerals.

Lee, S.Y.; Bondietti, E.A.

1982-01-01

65

The origin of ferrous zoning in Allende chondrule olivines  

NASA Astrophysics Data System (ADS)

Very similar major and minor element compositions are noted in the ferrous olivine occurring in chondrules at olivine grain boundaries, along cracks in olivine grains, interleaved with enstatite, and in the inner portions of exposed olivine grain surface rims; simultaneous formation by a single process is therefore suggested. The ferrous chondrule olivine probably formed by the reaction of chondrules with very hot nebular vapors over a period of several hours, followed by the condensation of residual metal vapors onto those olivine surfaces that were in direct contact with the gas as the system cooled. The ferrous chondrule olivine that occurs interleaved with enstatite in Allende does not have a composition identical to, and is not the precursor of, matrix olivine.

Peck, J. A.; Wood, J. A.

1987-06-01

66

Luminescent lanthanide chelates and methods of use  

DOEpatents

The invention provides lanthanide chelates capable of intense luminescence. The celates comprise a lanthanide chelator covalently joined to a coumarin-like or quinolone-like sensitizer. Exemplary sensitzers include 2- or 4-quinolones, 2- or 4-coumarins, or derivatives thereof e.g. carbostyril 124 (7-amino-4-methyl-2-quinolone), coumarin 120 (7-amino-4-methyl-2-coumarin), coumarin 124 (7-amino-4-(trifluoromethyl)-2-coumarin), aminomethyltrimethylpsoralen, etc. The chelates form high affinity complexes with lanthanides, such as terbium or europium, through chelator groups, such as DTPA. The chelates may be coupled to a wide variety of compounds to create specific labels, probes, diagnostic and/or therapeutic reagents, etc. The chelates find particular use in resonance energy transfer between chelate-lanthanide complexes and another luminescent agent, often a fluorescent non-metal based resonance energy acceptor. The methods provide useful information about the structure, conformation, relative location and/or interactions of macromolecules.

Selvin, Paul R. (Berkeley, CA); Hearst, John (Berkeley, CA)

1997-01-01

67

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

Federal Register 2010, 2011, 2012, 2013

...Activities: Comment Request for the Ferrous Metals Surveys AGENCY: U.S. Geological Survey...paperwork requirements for the Ferrous Metals Surveys. This collection consists of...consumption data of 13 ores, concentrates, metals, and ferroalloys, some of which...

2011-05-31

68

Comparative study of Ascofer®; and ferrous gluconate using Mössbauer spectroscopy with a high velocity resolution  

NASA Astrophysics Data System (ADS)

A comparative study of ferrous gluconate as well as fresh and outdated tablets of Ascofer®; was carried out using Mössbauer spectroscopy with a high velocity resolution. The obtained results revealed the presence of three ferrous and one ferric component in all investigated samples which may be related to ferrous gluconate molecules and ferric contamination and/or aging effect.

Oshtrakh, M. I.; Novikov, E. G.; Dubiel, S. M.; Semionkin, V. A.

2014-04-01

69

Modeling and production of fully ferrous components by indirect selective laser sintering  

Microsoft Academic Search

Purpose – The purpose of this paper is to develop a methodology to achieve successful infiltration of indirect selective laser sintered steel components with ferrous alloys and thereby to produce fully ferrous components with desirable properties while preserving part geometry. Design\\/methodology\\/approach – The approach is to generate a “green” part by selective laser sintering (SLS) of ferrous powder mixed with

Phani Vallabhajosyula; David L. Bourell

2011-01-01

70

Ferrous-iron induces lipid peroxidation with little damage to energy transduction in mitochondria  

Microsoft Academic Search

Addition of ferrous sulfate, but not ferric chloride, in micromolar concentrations to rat liver mitochondria induced high rates of consumption of oxygen. The oxygen consumed was several times in excess of the reducing capacity of ferrous-iron (O: Fe ratios 5–8). This occurred in the absence of NADPH or any exogenous oxidizable substrate. The reaction terminated on oxidation of ferrous ions.

Vidya Shivaswamy; C. K. Ramakrishna Kurup; T. Ramasarma

1993-01-01

71

DETERMINATION OF THE RATES AND PRODUCTS OF FERROUS IRON OXIDATION IN ARSENIC-CONTAMINATED POND WATER.  

EPA Science Inventory

Dissolved ferrous iron and arsenic in the presence of insufficient oxygenated ground water is released into a pond. When the mixing of ferrous iron and oxygenated water within the pond occurs, the ferrous iron is oxidized and precipitated as an iron oxide. Groups of experiments...

72

Control of NonFerrous Electric Arc Furnaces  

Microsoft Academic Search

An important aspect of non-ferrous metal production is the separation process known as smelting, in which the concentrated ore is melted and separated into two components of different densities: the slag and the matte. The smelting process is carried out through high-power heating in electric arc furnaces. In order to maintain a constant desired matte production rate and constant matte

Benoit Boulet; Vit Vaculik; Geoff Wong

73

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

74

Copper Removal from Molten Ferrous Scrap: A Pilot Plant Study.  

National Technical Information Service (NTIS)

The removal of copper from molten carbon - saturated iron melts by treatment with sodium sulfate compacts has been successfully demonstrated on a pilot-plant scale. Major equipment involved a one-ton arc furnace for melting ferrous scrap and a one and one...

H. V. Makar R. E. Brown

1974-01-01

75

21 CFR 184.1307c - Ferrous citrate.  

Code of Federal Regulations, 2013 CFR

...powder or white crystals. It is prepared from the reaction of sodium citrate with ferrous sulfate or by direct action of citric acid on iron filings. (b) The ingredient must be of a purity suitable for its intended use. (c) In...

2013-04-01

76

Preparation, characterization and the stability of ferrous glycinate nanoliposomes  

Microsoft Academic Search

Ferrous glycinate nanoliposomes prepared by the reverse-phase evaporation method (REV) from egg phosphatidylcholine (EPC) were investigated, based on the encapsulation efficiency, transmission electron microscopy (TEM), size distribution, and zeta potential. The nanoliposomes had high encapsulation efficiency, and TEM photomicrographs of nanoliposomes clearly showed their spherical shape. The size distribution and zeta potential indicated the stability of the nanoliposome suspensions. Retention

Baomiao Ding; Xiaoming Zhang; Khizar Hayat; Shuqin Xia; Chengsheng Jia; Mingyong Xie; Chengmei Liu

2011-01-01

77

Science and Technical Progress in Non-Ferrous Metallurgy.  

National Technical Information Service (NTIS)

The attainments of science in the field of non-ferrous metallurgy are discussed. The basic results of work in branches for 1966-1970 and for the first year of the ninth Five-year Plan are given. The book covers questions of adopting new processes and equi...

P. F. Lomako

1973-01-01

78

Synthesis and Thermodynamic Evaluation of Mixed Hexadentate Linear Iron Chelators Containing Hydroxypyridinone and Terephthalamide Units1  

PubMed Central

A series of new linear iron chelators containing hydroxypyridinone and terephthalamide moieties has been prepared. All are hexadentate ligands composed of a systematically varied combination of me-3,2-hydroxypyridinone and 2,3-dihydroxyterephthalamide binding units; most are based on a spermidine scaffold but one incorporates the bifunctional 2,3-dihydroxyterephthalamide unit as an integral part of the backbone. Protonation and ferric iron complex formation constants have been determined from solution thermodynamic studies giving log ?110 values of 25.7, 30.7, 36.3, 43.8, and 45.0 respectively. The ferric complexes display reversible reduction potentials from ?276 mV to ?1032 mV (measured relative to the normal hydrogen electrode NHE) in alkaline solution. The incremental replacement of hydroxypyridinone units by terephthalamide binding groups progressively reduces the ligand acidity, markedly increases the iron-chelate stability, and improves the selectivity for ferric ion over ferrous ion. While the majority of iron chelators forming very stable ferric complexes are based on a tripodal backbone such as TREN, the ferric 5-LIO(TAMmeg)2(TAM) complex, despite its non-tripodal scaffold, is one of the most stable iron complexes yet reported. Moreover, the high affinity for ferric ion of the discussed linear ligands strongly correlates with their ability to remove iron in vivo.

Abergel, Rebecca J.; Raymond, Kenneth N.

2011-01-01

79

Determination of the chelatable iron pool of isolated rat hepatocytes by digital fluorescence microscopy using the fluorescent probe, phen green SK.  

PubMed

The intracellular pool of chelatable iron is considered to be a decisive pathogenetic factor for various kinds of cell injury. We therefore set about establishing a method of detecting chelatable iron in isolated hepatocytes based on digital fluorescence microscopy. The fluorescence of hepatocytes loaded with the fluorescent metal indicators, phen green SK (PG SK), phen green FL (PG FL), calcein, or fluorescein desferrioxamine (FL-DFO), was quenched when iron was added to the cells in a membrane-permeable form. It increased when cellular chelatable iron available to the probe was experimentally decreased by an excess of various membrane-permeable transition metal chelators. The quenching by means of the ferrous ammonium sulfate + citrate complex and also the "dequenching" using 2,2'-dipyridyl (2,2'-DPD) were largest for PG. We therefore optimized the conditions for its use in hepatocytes and tested the influence of possible confounding factors. An ex situ calibration method was set up to determine the chelatable iron pool of cultured hepatocytes from the increase of PG SK fluorescence after the addition of excess 2,2'-DPD. Using this method, we found 9.8 +/- 2.9 micromol/L (mean +/- SEM; n = 18) chelatable iron in rat hepatocytes, which constituted 1.0% +/- 0.3% of the total iron content of the cells as determined by atomic absorption spectroscopy. The concentration of chelatable iron in hepatocytes was higher than the one in K562 cells (4.0 +/- 1.3 micromol/L; mean +/- SEM; n = 8), which were used for comparison. This method allowed us to record time courses of iron uptake and of iron chelation by different chelators (e.g., deferoxamine, 1,10-phenanthroline) in single, intact cells. PMID:10094962

Petrat, F; Rauen, U; de Groot, H

1999-04-01

80

Absorption of Iron from Ferritin Is Independent of Heme Iron and Ferrous Salts in Women and Rat Intestinal Segments123  

PubMed Central

Ferritin iron from food is readily bioavailable to humans and has the potential for treating iron deficiency. Whether ferritin iron absorption is mechanistically different from iron absorption from small iron complexes/salts remains controversial. Here, we studied iron absorption (RBC 59Fe) from radiolabeled ferritin iron (0.5 mg) in healthy women with or without non-ferritin iron competitors, ferrous sulfate, or hemoglobin. A 9-fold excess of non-ferritin iron competitor had no significant effect on ferritin iron absorption. Larger amounts of iron (50 mg and a 99-fold excess of either competitor) inhibited iron absorption. To measure transport rates of iron that was absorbed inside ferritin, rat intestinal segments ex vivo were perfused with radiolabeled ferritin and compared to perfusion with ferric nitrilotriacetic (Fe-NTA), a well-studied form of chelated iron. Intestinal transport of iron absorbed inside exogenous ferritin was 14.8% of the rate measured for iron absorbed from chelated iron. In the steady state, endogenous enterocyte ferritin contained >90% of the iron absorbed from Fe-NTA or ferritin. We found that ferritin is a slow release source of iron, readily available to humans or animals, based on RBC iron incorporation. Ferritin iron is absorbed by a different mechanism than iron salts/chelates or heme iron. Recognition of a second, nonheme iron absorption process, ferritin endocytosis, emphasizes the need for more mechanistic studies on ferritin iron absorption and highlights the potential of ferritin present in foods such as legumes to contribute to solutions for global iron deficiency.

Chen, Huijun; Miranda, Constanza; Janser, Heinz; Elsenhans, Bernd; Nunez, Marco T.; Pizarro, Fernando; Schumann, Klaus

2012-01-01

81

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 “necessity” for transfusion (96%), DFO chelation (92%) and oral chelation (89%), with lower “concern” 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

82

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

83

Exploring copper chelation in Alzheimer's disease protein  

NASA Astrophysics Data System (ADS)

Alzheimer's disease (AD) is a neurodegenerative disorder affecting millions of aging people in the U.S. alone. Clinical studies have indicated that metal chelation is a promising new approach in alleviating the symptoms of AD. Our study explores the as yet undetermined mechanism of copper chelation in amyloid-?, a protein implicated in AD. The structure of amyloid-? is derived from experimental results and incorporates a planar copper-ion-binding structure in a semi-solvated state. We investigate the chelation process using the nudged elastic band method implemented in our ab initio real-space multigrid code. We find that an optimal sequence of unbonding and rebonding events as well as proton transfers are required for a viable chelation process. These findings provide fundamental insight into the process of chelation that may lead to more effective AD therapies.

Rose, Frisco; Hodak, Miroslav; Bernholc, Jerry

2012-02-01

84

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

85

Precise determination of ferrous iron in silicate rocks  

Microsoft Academic Search

We have developed a highly precise method for the determination of ferrous iron (Fe2+) in silicate rocks. Our new method is based on Wilson’s procedure (1955) in which surplus V5+ is used to oxidize Fe2+ into Fe3+ while equivalently reducing V5+ into V4+. Because V4+ is more resistant to atmospheric oxidation than Fe2+, Fe2+ in the sample can be determined

Tetsuya Yokoyama; Eizo Nakamura

2002-01-01

86

Complexation of Nicotinamide Adenine Dinucleotide with Ferric and Ferrous Ions  

Microsoft Academic Search

Motivated by the observed influence of stainless steel and ferric and ferrous ions on the behavior of the peroxidase\\/oxidase oscillator, the mechanism and kinetics of interaction of 1,4-dihydronicotinamide adenine dinucleotide (NADH) with iron ions in 0.1 M acetic acid\\/sodium acetate buffer with pH 5.1 and with the solution\\/stainless steel interface were extensively studied. The character of a possible mutual influence

V. Lvovich; A. Scheeline

1995-01-01

87

[Influence of ionizing radiation, application of iron ions and their chelate complexes on the oxidative status of blood serum of rats].  

PubMed

Influence of ionizing radiation, ions of iron and their chelate complexes on the oxidative status of blood serum of rats has been investigated. Animals were irradiated by gamma-rays 60Co at a dose of 4 Gy. Ions of iron and iron chelates with nitrilotriacetic acid and citric acid were introduced into animals intra-abdominally at a doze of 10 mg of iron on 1 kg of body weight. The oxidative status of blood serum was determined according to the estimated content of oxidizing peroxide equivalents which oxidize ferrous iron in ferric iron with the subsequent estimation of ferric iron by means of xylenol orange. We also estimated the total content of iron in blood serum using ferrozine as an indicator. The oxidative status was defined 24 and 96 hours after irradiation and 2 hours after introduction of iron ions and their chelates. The research conducted has shown that the concentration of oxidizing peroxide equivalents in serum and the total iron concentration increase 1.47 times and 1.63 times correspondingly 24 hours after irradiation. The increase in the content of oxidizing peroxide equivalents and iron owing to Fenton's reaction can lead to the appearance of OH* radical and raise the level of damage of nuclear and membrane structures in irradiated cells. 2 hours after introduction of iron ions and their chelates, the content of oxidizing peroxide equivalents increased in the blood serum of irradiated and non-irradiated rats, and the maximum effect was observed when introducing ferrous iron and its chelate with citric acid. PMID:21674949

Riabchenko, N I; Ivannik, B P; Riabchenko, V I; Dzikovskaia, L A

2011-01-01

88

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

89

Photooxidation of 2,4-dichlorophenoxyacetic acid by ferrous oxalate-mediated system  

Microsoft Academic Search

The photodegradation of a herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) by ferrous oxalate\\/UV\\/H2O2 was studied. Ferrous oxalate, the more photoactive and reactive species, was found to react faster with hydrogen peroxide for hydroxyl radical production than ferrous ions under UV irradiation. About 2.9 times greater rate enhancement was found with the addition of 0.3 mM oxalate than that of a solution containing

C. Y. Kwan; W. Chu

2004-01-01

90

Chelation Therapy and Diamond Blackfan Anemia  

MedlinePLUS

... up in the body, a condition called iron overload. Eventually, after dozens of transfusions, the iron will ... red blood cells that carries oxygen. Fortunately, iron overload and organ damage can be prevented with chelation ...

91

Aminothiol multidentate chelators as antimalarials.  

PubMed

The antimalarial effects of two compounds from an aminothiol family of multidentate chelators, ethane-1,2-bis(N-1-amino-3-ethylbutyl-3-thiol) (BAT) and N',N',N'-tris(2-methyl-2-mercaptopropyl)-1,4,7-triazacyclononane (TAT), were studied in Plasmodium falciparum cultured in erythrocytes. Both drugs inhibited parasite growth, as was judged from [3H]hypoxanthine incorporation into the nucleic acids of parasites, with 50% inhibitory concentrations (IC50 values: 7.6 +/- 1.2 microM for BAT and 3.3 +/- 0.3 microM for TAT) that exceeded the antimalarial action of desferrioxamine B by 5-10 times. The inhibitory effects of both agents on P. falciparum cultures were fully reversed by pre-complexation with iron, suggesting that this action was related mainly to the withholding of iron. Spectrofluorometric studies with the fluorescent iron-sensing probe calcein showed that both compounds withheld iron from calcein at pH 8.2. The trophozoite and schizont stages of parasite development were the stages most susceptible to inhibition. The IC50 values of BAT and TAT for mammalian cells, which were estimated by [3H]thymidine incorporation into the nucleic acids of cells, were 10-20 times higher than those required to inhibit plasmodial growth. This indicates that multidentate aminothiols may prove to have a clinical margin of safety that makes them appropriate candidates for future clinical development. PMID:9313771

Loyevsky, M; John, C; Zaloujnyi, I; Gordeuk, V

1997-08-15

92

Heavy metal ions removal by chelating resin  

Microsoft Academic Search

Purpose – Preparation of chelating resin to be used in the removal of heavy metal ions from solutions. Design\\/methodology\\/approach – Chelating resin based on poly (glycidyl-methacrylate-co-N, N-methylene-bis-acrylamide) containing ethylenediamine was synthesised and used in removal of heavy metals from solutions. Findings – The optimal pH values for adsorption of different metal ions occur in the range 4.0-10.0 depending on the

N. M. Abd El-Moniem; M. R. El-Sourougy; D. A. F. Shaaban

2005-01-01

93

Self-diffusion of iron and sulfur in ferrous sulfide  

Microsoft Academic Search

By use of radiotracer techniques, the iron self-diffusion coefficient in ferrous sulfide single crystals above 620 K was found to be D = D0d exp {-[(81±4) + (84±20)d]\\/RT}where the exponential units are kJ\\/mole, D0 is 1.7± 0.1×10-2 and 3.0±0.2 × 10-2 cm2 sec-1for diffusion in the a- and c-directions, respectively, and d is the deviation from stoichiometry as given in

R. H. Condit; R. R. Hobbins; C. E. Birchenall

1974-01-01

94

Fluid extraction using carbon dioxide and organophosphorus chelating agents  

DOEpatents

Methods for extracting metalloid and metal species from a solid or liquid material by exposing the material to a fluid solvent, particularly supercritical CO{sub 2}, and a chelating agent are described. The chelating agent forms a chelate with the species, the chelate being soluble in the fluid to allow removal of the species from the material. In preferred embodiments the extraction solvent is supercritical CO{sub 2} and the chelating agent comprises an organophosphorous chelating agent, particularly sulfur-containing organophosphorous chelating agents, including mixtures of chelating agents. Examples of chelating agents include monothiophosphinic acid, di-thiophosphinic acid, phosphine sulfite, phosphorothioic acid, and mixtures thereof. The method provides an environmentally benign process for removing metal and metalloids from industrial waste solutions, particularly acidic solutions. Both the chelate and the supercritical fluid can be regenerated and the contaminant species recovered to provide an economic, efficient process. 1 fig.

Smart, N.G.; Wai, C.M.; Lin, Y.; Kwang, Y.H.

1998-11-24

95

Fluid extraction using carbon dioxide and organophosphorus chelating agents  

DOEpatents

Methods for extracting metalloid and metal species from a solid or liquid material by exposing the material to a fluid solvent, particularly supercritical CO.sub.2, and a chelating agent are described. The chelating agent forms a chelate with the species, the chelate being soluble in the fluid to allow removal of the species from the material. In preferred embodiments the extraction solvent is supercritical CO.sub.2 and the chelating agent comprises an organophosphorous chelating agent, particularly sulfur-containing organophosphorous chelating agents, including mixtures of chelating agents. Examples of chelating agents include monothiophosphinic acid, di-thiophosphinic acid, phosphine sulfite, phosphorothioic acid, and mixtures thereof. The method provides an environmentally benign process for removing metal and metalloids from industrial waste solutions, particularly acidic solutions. Both the chelate and the supercritical fluid can be regenerated and the contaminant species recovered to provide an economic, efficient process.

Smart, Neil G. (Moscow, ID); Wai, Chien M. (Moscow, ID); Lin, Yuehe (Moscow, ID); Kwang, Yak Hwa (Moscow, ID)

1998-01-01

96

Both immanently high active iron contents and increased root ferrous uptake in response to low iron stress contribute to the iron deficiency tolerance in Malus xiaojinensis.  

PubMed

To better understand the mechanism of low-iron stress tolerance in Malus xiaojinensis, the differences in physiological parameters and gene expression between an iron deficiency-sensitive species, Malus baccata, and an iron deficiency-tolerant species, M. xiaojinensis were investigated under low-iron (4 ?M Fe) conditions. Under iron sufficient conditions, the expressions of iron uptake- and transport-related genes, i.e. FIT1, IRT1, CS1, FRD3 and NRMAP1, and the immanent leaf and root active iron contents were higher in M. xiaojinensis than those in M. baccata. However, on the first three days of low iron stress, the rhizospheric pH decreased and the root ferric chelate reductase (FCR) activity and the expression of ferrous uptake- and iron transport-related genes in the roots increased significantly only in M. xiaojinensis. Leaf chlorosis occurred on the 3rd and the 9th day after low-iron treatment in M. baccata and M. xiaojinensis, respectively. The expression of iron relocalization-related genes, such as NAS1, FRD3 and NRMAP3, increased after the 5th or 6th day of low iron stress in leaves of M. xiaojinensis, whereas the expression of NAS1, FRD3 and NRMAP3 in the leaves of M. baccata increased immediately after the onset of low iron treatment. Conclusively, the relative high active iron contents caused by the immanently active root ferrous uptake and the increased root ferrous uptake in response to low iron stress were the dominant mechanisms for the tolerance to iron deficiency in M. xiaojinensis. PMID:24268163

Zha, Qian; Wang, Yi; Zhang, Xin-Zhong; Han, Zhen-Hai

2014-01-01

97

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

98

Wear study of carbide reinforced P/M ferrous composites  

SciTech Connect

Ferrous alloys have been used for decades as wear resistant materials for applications where severe wear (primarily abrasion) has been a problem. Irons and steels have an advantage in these applications because they can be alloyed with various elements to create structures which are quite harder than the iron matrix. For example, martensitic matrices can be developed as well as carbide structures (consisting usually of Cr-, Nb- or V-based carbides or some other complex carbide structure). However, these materials are usually made through melt/solidification techniques which can sometimes limit the type, volume fraction, and morphology of the carbide. In P/M processing these factors can be ignored in most instances. This paper will discuss the abrasive and impact-abrasive wear behavior of one class of wear resistant materials based on TiC. The materials removal mechanisms will be discussed with emphasis on microstructure-wear interactions. The results will be compared to traditional wear resistant ferrous based alloys.

Hawk, Jeffrey A.; Dogan, Omer N.; Wilson, Rick D.

2000-10-01

99

Biopharmaceutical characterization of ciprofloxacin HCl-ferrous sulfate interaction.  

PubMed

The ciprofloxacin-iron interaction, resulting in a lower bioavailability, is well documented in vivo; however, a mechanistic explanation supported by experimental data of this interaction is missing. In the present study, ciprofloxacin hydrochloride (HCl) and ferrous sulfate interaction was simulated in vitro by performing solubility and dissolution studies in the reactive media containing ferrous sulfate. Characterization of the precipitate formed indicated its probable chemical structure as Fe(SO(4) (2-) )(2) (Cl(-) )(2) (ciprofloxacin)(2) × (H(2) O)(n) , where n is up to 12 molecules of water. The solubility of this complex in water was estimated to be approximately 2? mg/mL, being about 20-fold lower than the solubility of ciprofloxacin HCl. The solubility of the complex was used as input parameter for an in silico modeling by GastroPlus™ and the resulting predicted plasma time curves were in good agreement with the in vivo data. These results strongly indicate that ciprofloxacin-iron interaction in vivo is caused by the formation of a low soluble complex. This interaction was also simulated by in vitro dissolution, in which a mini scale apparatus provided more biorelevant results than the standard dissolution apparatus, probably because the drug concentrations in the mini apparatus were higher and, thus, closer to the conditions encountered in vivo. PMID:21789771

Paroj?i?, Jelena; Stojkovi?, Aleksandra; Tajber, Lidia; Grbi?, Sandra; Paluch, Krzysztof J; Djuri?, Zorica; Corrigan, Owen I

2011-12-01

100

Iron (FeII) Chelation, Ferric Reducing Antioxidant Power, and Immune Modulating Potential of Arisaema jacquemontii (Himalayan Cobra Lily)  

PubMed Central

This study explored the antioxidant and immunomodulatory potential of ethnomedicinally valuable species, namely, Arisaema jacquemontii of north-western Himalayan region. The tubers, leaves, and fruits of this plant were subjected to extraction using different solvents. In vitro antioxidant studies were performed in terms of chelation power on ferrous ions and FRAP assay. The crude methanol extract of leaves was found to harbour better chelating capacity (58% at 100??g/mL) and reducing power (FRAP value 1085.4 ± 0.11??MFe3+/g dry wt.) than all the other extracts. The crude methanol extract was thus further partitioned with solvents to yield five fractions. Antioxidant study of fractions suggested that the methanol fraction possessed significant chelation capacity (49.7% at 100??g/mL) and reducing power with FRAP value of 1435.4??M/g dry wt. The fractions were also studied for immune modulating potential where it was observed that hexane fraction had significant suppressive effect on mitogen induced T-cell and B-cell proliferation and remarkable stimulating effect on humoral response by 141% and on DTH response by 168% in immune suppressed mice as compared to the controls. Therefore, it can be concluded that A. jacquemontii leaves hold considerable antioxidant and immunomodulating potential and they can be explored further for the identification of their chemical composition for a better understanding of their biological activities.

Sudan, Rasleen; Bhagat, Madhulika; Singh, Jasvinder; Koul, Anupurna

2014-01-01

101

Iron (FeII) Chelation, Ferric Reducing Antioxidant Power, and Immune Modulating Potential of Arisaema jacquemontii (Himalayan Cobra Lily).  

PubMed

This study explored the antioxidant and immunomodulatory potential of ethnomedicinally valuable species, namely, Arisaema jacquemontii of north-western Himalayan region. The tubers, leaves, and fruits of this plant were subjected to extraction using different solvents. In vitro antioxidant studies were performed in terms of chelation power on ferrous ions and FRAP assay. The crude methanol extract of leaves was found to harbour better chelating capacity (58% at 100? ? g/mL) and reducing power (FRAP value 1085.4 ± 0.11? ? MFe(3+)/g dry wt.) than all the other extracts. The crude methanol extract was thus further partitioned with solvents to yield five fractions. Antioxidant study of fractions suggested that the methanol fraction possessed significant chelation capacity (49.7% at 100? ? g/mL) and reducing power with FRAP value of 1435.4? ? M/g dry wt. The fractions were also studied for immune modulating potential where it was observed that hexane fraction had significant suppressive effect on mitogen induced T-cell and B-cell proliferation and remarkable stimulating effect on humoral response by 141% and on DTH response by 168% in immune suppressed mice as compared to the controls. Therefore, it can be concluded that A. jacquemontii leaves hold considerable antioxidant and immunomodulating potential and they can be explored further for the identification of their chemical composition for a better understanding of their biological activities. PMID:24895548

Sudan, Rasleen; Bhagat, Madhulika; Gupta, Sahil; Singh, Jasvinder; Koul, Anupurna

2014-01-01

102

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

2013-01-01

103

Ferrous Ferric Chloride Induces the Differentiation of Cultured Mouse Epidermal Melanocytes Additionally with Herbal Medicines  

Microsoft Academic Search

Ferrous ferric chloride (FFC) is a special form of aqueous iron that is a complex of ferrous chloride and ferric chloride and participates in oxidation and reduction reactions. My previous study showed that FFC stimulated the proliferation and differentiation of cultured epidermal melanoblasts or melanocytes derived from newborn mice. However, it is not known whether FFC stimulates the proliferation and

Tomohisa Hirobe

2009-01-01

104

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

105

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

106

Method and apparatus for back-extracting metal chelates  

DOEpatents

A method is described for extracting metal and metalloid species from a solid or liquid substrate using a supercritical fluid solvent containing one or more chelating agents followed by back-extracting the metal and metalloid species from the metal and metalloid chelates formed thereby. The back-extraction acidic solution is performed utilizing an acidic solution. Upon sufficient exposure of the metal and metalloid chelates to the acidic solution, the metal and metalloid species are released from the chelates into the acid solution, while the chelating agent remains in the supercritical fluid solvent. The chelating agent is thereby regenerated and the metal and metalloid species recovered. 3 figs.

Wai, C.M.; Smart, N.G.; Lin, Y.

1998-08-11

107

Method and apparatus for back-extracting metal chelates  

DOEpatents

A method of extracting metal and metalloid species from a solid or liquid substrate using a supercritical fluid solvent containing one or more chelating agents followed by back-extracting the metal and metalloid species from the metal and metalloid chelates formed thereby. The back-extraction acidic solution is performed utilizing an acidic solution. Upon sufficient exposure of the metal and metalloid chelates to the acidic solution, the metal and metalloid species are released from the chelates into the acid solution, while the chelating agent remains in the supercritical fluid solvent. The chelating agent is thereby regenerated and the metal and metalloid species recovered.

Wai, Chien M. (Moscow, IA); Smart, Neil G. (Moscow, IA); Lin, Yuehe (Moscow, IA)

1998-01-01

108

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

109

Bacterial oxidation of ferrous iron at low temperatures.  

PubMed

This study comprises the first report of ferrous iron oxidation by psychrotolerant, acidophilic iron-oxidizing bacteria capable of growing at 5 degrees C. Samples of mine drainage-impacted surface soils and sediments from the Norilsk mining region (Taimyr, Siberia) and Kristineberg (Skellefte district, Sweden) were inoculated into acidic ferrous sulfate media and incubated at 5 degrees C. Iron oxidation was preceded by an approximately 3-month lag period that was reduced in subsequent cultures. Three enrichment cultures were chosen for further work and one culture designated as isolate SS3 was purified by colony isolation from a Norilsk enrichment culture for determining the kinetics of iron oxidation. The 16S rRNA based phylogeny of SS3 and two other psychrotolerant cultures, SS5 from Norilsk and SK5 from Northern Sweden, was determined. Comparative analysis of amplified 16S rRNA gene sequences showed that the psychrotolerant cultures aligned within Acidithiobacillus ferrooxidans. The rate constant of iron oxidation by growing cultures of SS3 was in the range of 0.0162-0.0104 h(-1) depending on the initial pH. The oxidation kinetics followed an exponential pattern, consistent with a first order rate expression. Parallel iron oxidation by a mesophilic reference culture of Acidithiobacillus ferrooxidans was extremely slow and linear. Precipitates harvested from the 5 degrees C culture were identified by X-ray diffraction as mixtures of schwertmannite (ideal formula Fe(8)O(8)(OH)(6)SO(4)) and jarosite (KFe(3)(SO(4))(2)(OH)(6)). Jarosite was much more dominant in precipitates produced at 30 degrees C. PMID:17304566

Kupka, Daniel; Rzhepishevska, Olena I; Dopson, Mark; Lindström, E Börje; Karnachuk, Olia V; Tuovinen, Olli H

2007-08-15

110

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

111

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

112

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

113

Metal Chelate Catalysts for Fuel Cells.  

National Technical Information Service (NTIS)

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 al...

R. Darby R. White M. Yamana M. Tsutsui

1981-01-01

114

Multiple Emission in Mixed Ligand Metal Chelates.  

National Technical Information Service (NTIS)

Absorption and emission spectra, lifetimes and quantum yields are reported for mixed ligand chelates of 1,10-phenanthroline and 2,2'-dipyridyl of Rh(III). The mixed ligand complexes, (Rh(phen)2(dip))C3 and (Rh(dip)2(phen))C3, are found to possess more tha...

M. K. DeArmond W. Halper

1972-01-01

115

Current approach to iron chelation in children.  

PubMed

Transfusion-dependent children, mostly with thalassaemia major, but also and occasionally to a more significant degree, with inherited bone marrow failures, can develop severe iron overload in early life. Moreover, chronic conditions associated with ineffective erythropoiesis, such as non-transfusion-dependent thalassaemia (NTDT), may lead to iron overload through increased gut absorption of iron starting in childhood. Currently, the goal of iron chelation has shifted from treating iron overload to preventing iron accumulation and iron-induced end-organ complications, in order to achieve a normal pattern of complication-free survival and of quality of life. New chelation options increase the likelihood of achieving these goals. Timely initiation, close monitoring and continuous adjustment are the cornerstones of optimal chelation therapy in children, who have a higher transfusional requirements compared to adults in order to reach haemoglobin levels adequate for normal growth and development. Despite increased knowledge, there are still uncertainties about the level of body iron at which iron chelation therapy should be started and about the appropriate degree of iron stores' depletion. PMID:24646011

Aydinok, Yesim; Kattamis, Antonis; Viprakasit, Vip

2014-06-01

116

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

117

Iron mobilization from ferritin using alpha-oxohydroxy heteroaromatic chelators.  

PubMed Central

Several alpha-oxohydroxy heteroaromatic chelators have been shown to mobilize iron from horse spleen ferritin. Although the reactions were slow, taking up to 3 days to reach completion, the amounts of iron mobilized were higher than those reported for other chelators. These results increase the prospects for the clinical use of alpha-oxohydroxy chelators in the treatment of iron overload.

Kontoghiorghes, G J

1986-01-01

118

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

119

Chelation of iron within the erythrocytic Plasmodium falciparum parasite by iron chelators.  

PubMed

To examine the site of action of antimalarial iron chelators, iron ligands were added to control erythrocytes and to erythrocytes parasitized with Plasmodium falciparum, and the concentration of intracellular labile iron was monitored with the fluorescent probe, calcein. The fluorescence of calcein quenches upon binding iron and increases upon releasing iron. The chelators included desferrioxamine B, 2',2'-bipyridyl, and aminophenol II, a compound that is being newly reported as having anti-plasmodial properties. Calcein-loaded parasitized cells displayed fluorescence predominantly within the cytosol of both rings and trophozoites. The addition of chelators to both control and parasitized erythrocytes led to significant increases of fluorescence (P < 0.001). Fluorescence was observed to increase within the parasite itself after addition of iron chelators, indicating that these agents bound labile iron within the plasmodium. The relative increases of fluorescence after addition of chelators were greater in control than parasitized erythrocytes (P < 0.05) as were the estimated labile iron concentrations (P < or = 0.001). These results suggest that (i) the anti-malarial action of iron chelators might result from the ability to reach the infected cell's parasite compartment and bind iron within the parasite cytosol, and (ii) the labile iron pool of the host red cell may be either utilized or stored during plasmodial growth. PMID:10413042

Loyevsky, M; John, C; Dickens, B; Hu, V; Miller, J H; Gordeuk, V R

1999-06-25

120

Comparison of Mechanical and Acoustic Properties for Selected Nonferrous, Ferrous, and Plastic Materials.  

National Technical Information Service (NTIS)

Mechanical and acoustic properties have been tabulated for 356 nonferrous, 173 ferrous, and 67 plastic materials. These properties include density, Young's modulus of elasticity, ultimate tensile strength, yield strength, strength-to-density ratio, elasti...

F. P. Stecher S. L. Hanlein W. M. Hinckley

1970-01-01

121

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

122

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

123

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

124

Standard Reference Materials: Determination of Oxygen in Ferrous Materials Srm 1090, 1091, and 1092.  

National Technical Information Service (NTIS)

A description is presented of methods used for the determination of homogeneity and the establishment of the oxygen values certified by NBS for three ferrous standard reference materials. These standards are represented by ingot and vacuum melted iron con...

J. T. Sterling O. Menis

1966-01-01

125

Pilot Field Verification Studies of the Sodium Sulfide/Ferrous Sulfate Treatment Process.  

National Technical Information Service (NTIS)

In previous project, jar and dynamic testing showed that the sodium sulfide/ferrous sulfate process was a viable method for reducing hexavalent chromium and removing heavy metals from the Tinker AFB industrial wastewater with significant decrease in sludg...

D. F. Suciu D. S. Prescott F. S. Loyd P. M. Wiloff R. K. Schober

1988-01-01

126

Stability of vitamin B1 in Ultra Rice in the presence of encapsulated ferrous fumarate.  

PubMed

Food fortification with iron is effective in combating iron-deficiency anemia. As iron is reactive, it can destroy micronutrients, contribute to poor taste, and discolor the food. Encapsulation could be used to prevent the reaction of iron with food components. The stability of thiamin (vitamin B1) and its effects on organoleptic properties in Ultra Rice were investigated in the presence of encapsulated ferrous fumarate. The preparation of simulated rice grains did not affect the solubility of encapsulated ferrous fumarate in simulated gastric juice. After 20 weeks at 40 degrees C/ approximately 100% relative humidity, essentially all of the vitamin B1 and ferrous iron were retained. Antioxidants were effective in preventing the loss of thiamin and retarding oxidative rancidity catalyzed by ferrous iron. This study demonstrated the feasibility of incorporating both iron and vitamin B1 in a stable Ultra Rice formulation. Inclusion of other stable B vitamins in the formulation should be also feasible. PMID:17886086

Li, Yao; Diosady, Levente L; Jankowski, Shirley

2008-02-01

127

Inhibitory effect of iron-oxidizing bacteria on ferrous-promoted chalcopyrite leaching  

Microsoft Academic Search

A substantial amount of copper is obtained by dump leaching of low-grade ore that would otherwise become waste. It is generally accepted that iron-oxidizing bacteria. Thiobacillus ferrooxidans, enhance chalcopyrite leaching. However, this article details a case of the bacteria suppressing chalcopyrite leaching. Bacterial leaching experiments were performed with sulfuric acid solutions containing 0 or 0.04 mol\\/dm³ ferrous sulfate. Without ferrous

Naoki Hiroyoshi; Masahiko Hirota; Tsuyoshi Hirajima; Masami Tsunekawa

1999-01-01

128

Use of X-Ray Thickness Gauges in Manufacturing Rolled NonFerrous Metals  

Microsoft Academic Search

A technique of taking into account modifications of the chemical composition of alloys in measuring the thickness of rolled non-ferrous metal products by X-ray thickness gauges is described. The possibilities and perspectives of using RIT10 X-ray thickness gauges in rolling mills with a wide assortment of treated non-ferrous metals and their alloys are demonstrated. The accuracy reached in measurements of

B. V. Artem'ev; A. I. Maslov; V. N. Potapov; M. B. Vedernikov

2003-01-01

129

Remediation of chromite ore processing residue using ferrous sulfate and calcium polysulfide  

Microsoft Academic Search

Batch tests were conducted to assess the potential use of ferrous sulfate and calcium polysulfide for the remediation of chromite\\u000a ore processing residue (COPR). The remediation process entails addition of ferrous sulfate or calcium polysulfide to chemically\\u000a reduce hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] in slurry form and pH adjustment to precipitate Cr(III)\\u000a as chromium hydroxide. The present study

Mahmoud Wazne; Deok Hyun Moon; Santhi Chandra Jagupilla; Sarath Chandra Jagupilla; Christos Christodoulatos; Dimitris Dermatas; Maria Chrysochoou

2007-01-01

130

Friction and wear of some ferrous-base metallic glasses  

NASA Technical Reports Server (NTRS)

Sliding friction experiments, X-ray photoelectron spectroscopy (XPS) analysis, and electron microscopy and diffraction studies were conducted with ferrous base metallic glasses (amorphous alloys) in contact with aluminium oxide at temperatures to 750 C in a vacuum. Sliding friction experiments were also conducted in argon and air atmospheres. The results of the investigation indicate that the coefficient of friction increases with increasing temperature to 350 C in vacuum. The increase in friction is due to an increase in adhesion resulting from surface segregation of boric oxide and/or silicon oxide to the surface of the foil. Above 500 C the coefficient of friction decreased rapidly. The decrease correlates with the segregation of boron nitride to the surface. Contaminants can come from the bulk of the material to the surface upon heating and impart boric oxide and/or silicon oxide at 350 C and boron nitride above 500 C. The segregation of contaminants is responsible for the friction behavior. The amorphous alloys have superior wear resistance to crystalline 304 stainless steel. The relative concentrations of the various constituents at the surfaces of the amorphous alloys are very different from the nominal bulk compositions.

Miyoshi, K.; Buckley, D. H.

1984-01-01

131

Friction and wear of some ferrous-base metallic glasses  

NASA Technical Reports Server (NTRS)

Sliding friction experiments, X-ray photoelectron spectroscopy (XPS) analysis, and electron microscopy and diffraction studies were conducted with ferrous base metallic glasses (amorphous alloys) in contact with aluminum oxide at temperatures to 750 C in a vacuum. Sliding friction experiments were also conducted in argon and air atmospheres. The results of the investigation indicate that the coefficient of friction increases with increasing temperature to 350 C in vacuum. The increase in friction is due to an increase in adhesion resulting from surface segregation of boric oxide and/or silicon oxide to the surface of the foil. Above 500 C the coefficient of friction decreased rapidly. The decrease correlates with the segregation of boron nitride to the surface. Contaminants can come from the bulk of the material to the surface upon heating and impart boric oxide and/or silicon oxide at 350 C and boron nitride above 500 C. The segregation of contaminants is responsible for the friction behavior. The amorphous alloys have superior wear resistance to crystalline 304 stainless steel. The relative concentrations of the various constituents at the surfaces of the amorphous alloys are very different from the nominal bulk compositions.

Miyoshi, K.; Buckley, D. H.

1983-01-01

132

Obligatory Reduction of Ferric Chelates in Iron Uptake by Soybeans  

PubMed Central

The contrasting Fe2+ and Fe3+ chelating properties of the synthetic chelators ethylenediaminedi (o-hydroxyphenylacetate) (EDDHA) and 4,7-di(4-phenylsulfonate)-1, 10-phenanthroline (bathophenanthrolinedisulfonate) (BPDS) were used to determine the valence form of Fe absorbed by soybean roots supplied with Fe3+-chelates. EDDHA binds Fe3+ strongly, but Fe2+ weakly; BPDS binds Fe2+ strongly but Fe3+ weakly. Addition of an excess of BPDS to nutrient solutions containing Fe3+-chelates inhibited soybean Fe uptake-translocation by 99+%; [Fe(II) (BPDS)3]4? accumulated in the nutrient solution. The addition of EDDHA caused little or no inhibition. These results were observed with topped and intact soybeans. Thus, separation and absorption of Fe from Fe3+-chelates appear to require reduction of Fe3+-chelate to Fe2+-chelate at the root, with Fe2+ being the principal form of Fe absorbed by soybean.

Chaney, Rufus L.; Brown, John C.; Tiffin, Lee O.

1972-01-01

133

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 4×4 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

2013-07-01

134

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

PubMed

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. PMID:7811087

Ehrenreich, A; Widdel, F

1994-12-01

135

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

136

Characterisation of metal-chelate methacrylate monoliths.  

PubMed

Monoliths are attractive stationary phases for purification of large biomolecules like proteins because of their flow-unaffected properties. Isolation of histidine containing proteins to high purity can be efficiently performed using metal-chelate interactions within a single chromatographic step. In this work, we investigated properties of commercial metal-chelate methacrylate monoliths-Convective Interaction Media (CIM). Analytical CIM disk monolithic columns and CIM 8 ml monolithic columns were used for purification of tumor necrosis factor-alpha (TNF-alpha) analog LK-801 and green fluorescence protein with 6 histidine tag (GFP-6His). In both cases, purity over 90% was achieved. Dynamic binding capacity at 10% of breakthrough was around 17-18 mg/ml for LK-801 and around 30 mg/ml for GFP-6His. Adsorption isotherm revealed that the maximal capacity is achieved at protein concentration above 60 microg/ml. Dynamic binding capacity and resolution were found to be flow unaffected. PMID:16517243

Peterka, M; Jarc, M; Banjac, M; Frankovic, V; Bencina, K; Merhar, M; Gaberc-Porekar, V; Menart, V; Strancar, A; Podgornik, A

2006-03-17

137

Chelating versatility of toxic metal resistant microorganisms  

Microsoft Academic Search

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, when tested for their toxicity and decorporation potential from mammalian tissues have shown that their efficiency is comparable to DTPA (Diethylene triamine pentaacetic acid) and DFOA

E. T. Premuzic; M. Lin

1985-01-01

138

Determination of chelated iron in the urine  

PubMed Central

A simplified wet-ashing technique is described for the determination of chelated iron in the urine, with special reference to DTPA-bound iron. The procedure dispenses with the need for quantitative transfer, and gives corresponding economy in time, labour, and glassware without loss of precision. The standard error of the mean estimate of a triplicate determination, using four reference standards, is ± 4 ?g/100 ml; precision may be further increased by the use of a calibration curve based on many standards.

Barry, Michael

1968-01-01

139

Metal chelate catalysts for fuel cells  

NASA Astrophysics Data System (ADS)

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 chelates, with comparable active and considerably greater stability than the monomers. Three methods for stability testing were developed: (1) Potentiostatic, with periodic measurement of the current potential characteristic; (2) potentiostatic, with continuous monitoring of the current, and; (3) galvanostatic, with continuous monitoring of potential. Each method provides a good evaluation of activity versus time, and the method to be used depends upon the objective of the test. A polymeric form of Co(TAA) was synthesized by means of an acetylene terminated monomer, which in turn was made via a Co(TAA)Br2 intermediate. The activity of the polymer was found to be comparable to that of Co(TAA) monomer, and significantly greater than that of either the stacked or sheet polymeric forms of Cobalt tetraphenylporphrine (CoTPP) previously synthesized and tested.

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

1981-07-01

140

Chromatographic methods for the separation of biocompatible iron chelators from their synthetic precursors and iron chelates.  

PubMed

Chromatographic methods have been developed for the separation of the three novel biocompatible iron chelators pyridoxal isonicotinoyl hydrazone (PIH), salicylaldehyde isonicotinoyl hydrazone (SIH), and pyridoxal 2-chlorobenzoyl hydrazone (o-108) from their synthetic precursors and iron chelates. The chromatographic analyses were achieved using analytical columns packed with 5 microm Nucleosil 120-5 C18. For the evaluation of all chelators in the presence of the synthetic precursors, EDTA was added to the mobile phase at a concentration of 2 mM. The best separation of PIH and its synthetic precursors was achieved using a mixture of phosphate buffer (0.01 M NaH2PO4, 5 mM 1-heptanesulfonic acid sodium salt; pH 3.0) and methanol (55:45, v/v). For separation of SIH and its synthetic precursors, the mobile phase was composed of 0.01 M phosphate buffer (pH 6.0) and methanol (60:40, v/v). o-108 was analyzed employing a mixture of 0.01 M phosphate buffer (pH 7.0), methanol, and acetonitrile (60:20:20, v/v/v). These mobile phases were slightly modified to separate each chelator from its iron chelate. Furthermore, a RP-TLC method has also been developed for fast separation of all compounds. The chromatographic methods described herein could be applied in the evaluation of purity and stability of these drug candidates. PMID:15638159

Kovaríková, Petra; Mokrý, Milan; Klime, Jirí; Vávrová, Katerina

2004-12-01

141

Regulation of AhFRO1, an Fe(III)-chelate reductase of peanut, during iron deficiency stress and intercropping with maize.  

PubMed

Iron deficiency-induced chlorosis in peanut during anthesis was alleviated when peanut was intercropped with maize in field and pot experiments. Iron acquisition of graminaceous plants is characterized by the synthesis and secretion of the iron-chelating phytosiderophores. Compared to the roots of monocropped maize, the roots of maize intercropped with peanut always secreted higher amounts of phytosiderophores during peanut anthesis. For non-graminaceous plants, reduction of ferric to ferrous iron on the root surface is the rate-limiting step for mobilizing iron from soil. The full-length cDNA, AhFRO1, which is encoding an Fe(III)-chelate reductase, was isolated from peanut. AhFRO1 expression in yeast conferred Fe(III)-chelate reductase activity to the cells. Consistent with its function in iron uptake, AhFRO1 was determined to be a membrane protein by transient expression analysis. AhFRO1 mRNA accumulated under iron deficiency conditions. During pre-anthesis, the Fe(III)-chelate reductase activity and the transcript levels of AhFRO1 were similar in monocropped and intercropped peanut. When the iron deficiency-induced chlorosis developed in the monocropped peanuts, both the Fe(III)-chelate reductase activity of peanut and the transcript levels of AhFRO1 were higher in intercropped than in monocropped peanuts, which is consistent with the secretion of phytosiderophores by maize roots. We conclude that AhFRO1 in peanut and phytosiderophores from maize co-operate to improve the iron nutrition of peanut when intercropped with maize. PMID:19453500

Ding, Hong; Duan, Lihong; Wu, Huilan; Yang, Rongxin; Ling, Hongqing; Li, Wen-Xue; Zhang, Fusuo

2009-07-01

142

Degradation of ciprofloxacin and sulfamethoxazole by ferrous-activated persulfate: implications for remediation of groundwater contaminated by antibiotics.  

PubMed

The wide occurrence of antibiotics in groundwater raised great scientific interest as well as public awareness in recent years due to their potential ability to spread antibiotic resistant gene and pose risk to humans. The present study investigated the ferrous ion (Fe(II)) activated decomposition of persulfate (S2O8(2-)), as a potential in situ chemical oxidation (ISCO) approach, for remediation of groundwater contaminated by antibiotics. Fe(II)-persulfate mediated ciprofloxacin (CIP) degradation was found to be more efficient than sulfamethoxazole (SMX) at near neutral pH (pH6.0), probably due to the higher electric density in CIP molecule and its ability to form complex with Fe(II) as a ligand. Hydroxyl (HO) and sulfate radical (SO4(-)) were determined to be responsible for the degradation of CIP and SMX in Fe(II)-persulfate system by molecular probes. No enhancement in the degradation of CIP was observed when citrate (CA), ethylenediaminetetraacetate (EDTA) and (S,S)-ethylenediamine-N,N'-disuccinate (EDDS) were used as Fe(II) chelating agents in Fe(II)-persulfate system. For SMX, CA and EDTA accelerated the degradation by Fe(II)-persulfate. Degradation of antibiotics in river water matrix was nearly the same as that in Milli-Q water, implying the possibility of using Fe(II)-persulfate for antibiotics depletion under environmentally relevant condition. A comparison of the degradation efficiency of SMX with other sulfonamides and sulfanilic acid indicated that the heterocyclic ring has a large impact on the degradation of sulfonamides. Transformation products of CIP and SMX by Fe(II)-persulfate were analyzed by solid phase extraction-liquid chromatography-mass spectrometry (SPE-LC-MS) technique. Based on the intermediate products, Fe(II)-persulfate mediated CIP degradation pathways were tentatively proposed. PMID:24342085

Ji, Yuefei; Ferronato, Corinne; Salvador, Arnaud; Yang, Xi; Chovelon, Jean-Marc

2014-02-15

143

Crystal structures of ferrous and ferrous-NO forms of verdoheme in a complex with human heme oxygenase-1: catalytic implications for heme cleavage.  

PubMed

Heme oxygenase oxidatively degrades heme to biliverdin resulting in the release of iron and CO through a process in which the heme participates both as a cofactor and substrate. One of the least understood steps in the heme degradation pathway is the conversion of verdoheme to biliverdin. In order to obtain a better understanding of this step we report the crystal structures of ferrous-verdoheme and, as a mimic for the oxy-verdoheme complex, ferrous-NO verdoheme in a complex with human HO-1 at 2.20 and 2.10 A, respectively. In both structures the verdoheme occupies the same binding location as heme in heme-HO-1, but rather than being ruffled verdoheme in both sets of structures is flat. Both structures are similar to their heme counterparts except for the distal helix and heme pocket solvent structure. In the ferrous-verdoheme structure the distal helix moves closer to the verdoheme, thus tightening the active site. NO binds to verdoheme in a similar bent conformation to that found in heme-HO-1. The bend angle in the verodoheme-NO structure places the terminal NO oxygen 1 A closer to the alpha-meso oxygen of verdoheme compared to the alpha-meso carbon on the heme-NO structure. A network of water molecules, which provide the required protons to activate the iron-oxy complex of heme-HO-1, is absent in both ferrous-verdoheme and the verdoheme-NO structure. PMID:15522396

Lad, Latesh; Ortiz de Montellano, Paul R; Poulos, Thomas L

2004-11-01

144

Ultrafine Particulate Ferrous Iron and Anthracene Associations with Mitochondrial Dysfunction  

SciTech Connect

The ultrafine size fraction of ambient particles (ultrafine particles, UFP, diameter < 100 nm) has been identified as being far more potent in their adverse health effects than their larger counterparts, yet, the detailed mechanisms for why UFP display such distinctive toxicity are not well understood. In the present study, ambient UFP were exposed to mitochondria while monitoring electron transport chain (ETC) activity as a model system for biochemical toxicity. UFP samples were collected in rural (Ellensburg, WA) and urban environments (Seattle, WA) and chemically characterized for total trace metals, ferrous (Fe(II)) and easily reducible ferric (Fe(III)) iron, polycyclic aromatic hydrocarbons, and surface constituents with X-ray photoelectron spectroscopy (XPS). Low doses of UFP (8 µg mL-1) caused a decrease in mitochondrial ETC function compared to controls in 94% of the samples after The 20 min of exposure. Significant correlations exist between initial %ETC inhibition (0-10 min) and Fe(II) (R=0.55, P=0.03, N=15), anthracene (R=0.74, P<0.01, N=13), and %C-O surface bonds (R=0.56, P=0.03, N=15), whereby anthracene and %C-O correlate as well (R=0.58, P=0.03, N=14). No significant associations were identified with total Fe and other trace metals. Results from this study indicate that the redox active fraction of Fe as well as the abundance of anthracene-related, C-O containing, surface structures may contribute to the initial detrimental behavior of UFP, thus supporting the idea that the Fe(II)/Fe(III) and certain efficient hydroquinone/quinone redox pairs may play an important role likely due to their potential to produce reactive oxygen species (ROS).

Faiola, Celia; Johansen, Anne M.; Rybka, Sara; Nieber, Annika; Thomas-Bradley, Carin; Bryner, Stephanie; Johnston, Justin M.; Engelhard, Mark H.; Nachimuthu, Ponnusamy; Owens, Kalyn S.

2011-04-20

145

Intermediate-spin ferrous iron in the Earth's lower mantle?  

NASA Astrophysics Data System (ADS)

Intermediate-spin (IS) ferrous iron (Fe2+) has been a controversy in mineral physics. Its existence can change the detailed spin map of the Earth interior and may significantly affect mantle properties. IS Fe2+ is also a topic of interdisciplinary interest. Its existence in coordination complexes enables potential molecular devices to process more information; its connection with the superconductivity of iron chalcogenides has also been discussed. Here, we use the density functional theory + self-consistent Hubbard U (DFT+Usc) method to investigate IS Fe2+ in lower-mantle minerals. In ferropericlase, we found two different types of IS (t2g5eg1) states. Their distinct orbital occupancies lead to distinct Jahn-Teller (J-T) distortions, nuclear quadrupole splittings (QS), and on-site Coulomb interactions. Consequently, one IS state is much more favorable than the other, making it the most possible IS state in ferropericlase. In light of these new findings, we re-examine the previously reported IS Fe2+ in magnesium silicate (MgSiO3) perovskite [Hsu et al., Earth Planet. Sci. Lett. 294, 19 (2010)] and post-perovskite [Yu et al., Earth Planet. Sci. Lett. 331-332, 1 (2011)]. While these two minerals are much more complicated, the reported IS states are highly similar to the most favorable IS state in ferropericlase, suggesting that they are indeed the most possible IS states in these two minerals. However, these most possible IS Fe2+ are still not energetically favorable. Therefore, IS Fe2+ is highly unlikely in the Earth's lower mantle. *This project is supported by NSC Grant 102-2112-M-008-001-MY3 (H.H.) and NSF Awards EAR-1319361, -1019853, and -0810272 (R.M.W).

Hsu, H.; Wentzcovitch, R. M.

2013-12-01

146

Effects of some naturally occurring iron ion chelators on in vitro superoxide radical formation.  

PubMed

The effects of some naturally occurring iron ion chelators and their derivatives on the electron transfer from ferrous ions to oxygen molecules were examined by measuring oxygen consumption rates. Of the compounds examined, quinolinic acid, fusaric acid, and 2-pyridinecarboxylic acid repressed the oxygen consumption, whereas chlorogenic acid, caffeic acid, gallic acid, catechol, L-beta-(3,4-dihydroxyphenyl)alanine, and xanthurenic acid accelerated it. Theoretical calculations showed that the energies of the highest occupied molecular orbitals (HOMOs) of [Fe(II)(ligand)3]- complexes were relatively high when the ligands were caffeic acid and its derivatives such as catechol, gallic acid, and L-beta-(3,4-dihydroxyphenyl)alanine. On the other hand, the energies of the HOMOs of [Fe(II)(ligand)3]- complexes were relatively low when the ligands were quinolinic acid and its derivatives such as 2-pyridinecarboxylic acid and fusaric acid. The energies of the HOMOs appear to be closely related with acceleration or repression of the oxygen consumption; that is to say, when the energy of the HOMO is high, the oxygen consumption is accelerated, and vice versa. PMID:16327062

Hirai, Tomihiro; Fukushima, Kazuaki; Kumamoto, Kazumasa; Iwahashi, Hideo

2005-01-01

147

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 °C), 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

2011-11-24

148

Chelators whose affinity for calcium is decreased by illumination  

NASA Technical Reports Server (NTRS)

The present invention discloses a group of calcium chelating compounds which have a descreased affinity for calcium following illumination. These new compounds contain a photolabile nitrobenzyl derivative coupled to a tetracarboxylate Ca.sup.2+ chelating parent compound having the octacoordinate chelating groups characteristic of EGTA or BAPTA. In a first form, the new compounds are comprised of a BAPTA-like chelator coupled to a single 2-nitrobenzyl derivative, which in turn is a photochemical precursor of a 2-nitrosobenzophenone. In a second form, the new compounds are comprised of a BAPTA-like chelator coupled to two 2-nitrobenzyl derivatives, themselves photochemical prcursors of the related 2-nitrosobenzophenones. The present invention also discloses a novel method for preparing 1-hydroxy- or 1-alkoxy-1-(2-nitroaryl)-1-aryl methanes. Methanes of this type are critical to the preparation of, or actually constitute, the photolabile Ca.sup.2+ chelating compounds disclosed and claimed herein.

Tsien, Roger Y. (Inventor); Grynkiewicz, Grzegorz (Inventor); Minta, Akwasi (Inventor)

1987-01-01

149

Evaluation of boron chelates in extracting soil boron  

Microsoft Academic Search

The hot water extractable boron (HWB) soil?test procedure does not lend itself to rapid routine analysis. This study was conducted to evaluate boron (B) chelates in extracting soil B in comparison to the HWB soil?test procedure. The following B chelates were examined as soil B extractants: mannitol, salicylic acid, 2?hydroxyisobutyric acid, and sorbitol. Soil B chelate extractants were prepared in

Byron Vaughan; John Howe

1994-01-01

150

Prophylactic chelation therapy in occupational lead poisoning: a review.  

PubMed

Chelating agents are useful in the therapy of acute overexposure to lead. However, prophylactic use of chelating agents, particularly under conditions of continued exposure to lead can be harmful to health. Potential adverse effects include kidney damage, symptomatic lead poisoning, increased absorption of lead from the gastrointestinal tract and disruption in the metabolism of trace metals other than lead. Prophylactic chelation is an unacceptable medical practice which cannot be condoned. PMID:411363

Bridbord, K; Blejer, H P

1977-10-01

151

Evaluation of Ferric and Ferrous Iron Therapies in Women with Iron Deficiency Anaemia  

PubMed Central

Introduction. Different ferric and ferrous iron preparations can be used as oral iron supplements. Our aim was to compare the effects of oral ferric and ferrous iron therapies in women with iron deficiency anaemia. Methods. The present study included 104 women diagnosed with iron deficiency anaemia after evaluation. In the evaluations performed to detect the aetiology underlying the iron deficiency anaemia, it was found and treated. After the detection of the iron deficiency anaemia aetiology and treatment of the underlying aetiology, the ferric group consisted of 30 patients treated with oral ferric protein succinylate tablets (2 × 40?mg elemental iron/day), and the second group consisted of 34 patients treated with oral ferrous glycine sulphate tablets (2 × 40?mg elemental iron/day) for three months. In all patients, the following laboratory evaluations were performed before beginning treatment and after treatment. Results. The mean haemoglobin and haematocrit increases were 0.95?g/dL and 2.62% in the ferric group, while they were 2.25?g/dL and 5.91% in the ferrous group, respectively. A significant difference was found between the groups regarding the increase in haemoglobin and haematocrit values (P < 0.05). Conclusion. Data are submitted on the good tolerability, higher efficacy, and lower cost of the ferrous preparation used in our study.

Berber, Ilhami; Erkurt, Mehmet Ali; Aydogdu, Ismet; Kuku, Irfan

2014-01-01

152

Radiation Chemical and MR Studies of Aqueous Agarose Gels Containing Ferrous Ions.  

NASA Astrophysics Data System (ADS)

Aqueous agarose gels containing ferrous ions, in 0.05 N sulfuric acid have been studied after irradiation with 6-18 MeV electrons or ^{137} Cs gamma-rays. Such gels can sustain a radiolytic chain reaction, producing Fe ^{3+} with G(Fe^ {3+})-values up to 100 having been observed. The Fe^{3+} production is independent of dose rate between 0.434 and 3.74 Gy min ^{-1}. Dissolved oxygen is needed to maintain the chain reaction, and initial ferric yields are increased if the gel is oxygen saturated or if the ferrous concentration is decreased below 1 mM. The oxidation of ferrous to ferric alters the magnetic moment of the ion and its electron spin relaxation time, which in turn affects its ability to promote proton spin relaxation rates. Longitudinal proton magnetic relaxation rates are increased in proportion to ferric production, permitting visualization of dose levels in these gels by magnetic resonance imaging (MRI) techniques. Non-uniform dose distribution images of electron irradiated ferrous/agarose (FA) systems have been obtained using MRI. Images of radiation doses surrounding capillary tubes filled with radioactive material embedded in FA systems have also been obtained. In this work, another new method of using the ferrous/agarose gel system doped with xylenol orange to visualize the radiation dose distribution directly by eye has been developed. The color change developed depends both quantitatively and qualitatively on the concentrations of solutes in the gel.

Leghrouz, Amin Ahmad

153

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 and 90 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. 34 figs.

Chang, S.G.; Littlejohn, D.; Shi, Y.

1997-08-19

154

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

155

Effect of chelating agents on the migration of radionuclides  

SciTech Connect

It has been stated that chelate formation of radionuclides with chelating agents such as decontamination reagents (e.g., ethylenediaminetetraacetic acid) and natural organic compounds (e.g., fulvic and humic acids) found in groundwater significantly influence the migration behavior of radionuclides. They form extremely strong chelates with radionuclides and mobilizes these radionuclides from the radioactive waste (especially from low-level waste) repository. In this study, a new retardation factor incorporating a chelation effect is introduced. A general convection-dispersion transport equation that includes a degradation of solute caused by various physicochemical reactions in porous medium is used and solved by an analytical method.

Min Hoon Baik; Kun Jai Lee

1991-11-01

156

Effect of time and storing conditions on iron forms in ferrous gluconate and Ascofer®  

NASA Astrophysics Data System (ADS)

Antianemic medicament Ascofer® and ferrous gluconate, its basic iron bearing ingredient, were studied with the use of Mössbauer spectroscopy. Room temperature spectra gave a clear evidence that two phases of iron were present viz. ferrous (Fe 2+) as a major one with a contribution of ˜85 ± 5%, and ferric (Fe 3+) whose contribution was found to be ˜15 ± 5%. However, the actual values of the contributions of the two kinds of the iron ions in Ascofer® were shown to depend on sample's age: the abundance of Fe 2+ ions increased with time by ˜10% after 51 months, while that of Fe 3+ decreased by the same amount. This means that an internal reduction of Fe 3+ ions took place. The ferrous ions were shown to occupy three different sites with populations of ˜75-79% for site 1, and ˜8-23% for site 2, and ˜1-13% for site 3.

Dubiel, S. M.; Cie?lak, J.; Gozdyra, R.

2011-04-01

157

Chemical treatment of chelated metal finishing wastes.  

PubMed

This study evaluated two chemical approaches for treatment of commingled cadmium-cyanide (Cd-CN) and zinc-nickel (Zn-Ni) wastewaters. The first approach, which involved application of sodium hypochlorite (NaOCl), focused on elimination of chelating substances. The second approach evaluated the use of sodium dimethyldithiocarbamate (DMDTC) to specifically target and precipitate regulated heavy metals. Results demonstrated that by maintaining a pH of 10.0 and an oxidation-reduction potential (ORP) value of +600 mV, NaOCl treatment was effective in eliminating all chelating substances. Cadmium, chromium, nickel, and zinc solution concentrations were reduced from 0.27, 4.44, 0.06, and 0.10 ppm to 0.16, 0.17, 0.03, and 0.06 ppm, respectively. Similarly, a 1% DMDTC solution reduced these same metal concentrations in commingled wastewater to 0.009, 1.142, 0.036, and 0.320 ppm. Increasing the DMDTC concentration to 2% improved the removal of all regulated heavy metals except zinc, the removal of which at high pH values is limited by its amphotericity. PMID:23342939

McFarland, Michael J; Glarborg, Christen; Ross, Mark A

2012-12-01

158

Removal of phosphorus from wastewaters using ferrous salts - a pilot scale membrane bioreactor study.  

PubMed

A pilot scale membrane bioreactor (3.7 m(3)/day capacity), configured for alternate point ferrous sulphate addition, was evaluated in a fourteen month trial to comply with an effluent discharge requirement of less than 0.15 mg-P/L at the 50(th) percentile and less than 0.30 mg-P/L at the 90th percentile. Ferrous sulphate was added at a molar ratio (Fe(II):PO4) of 2.99 in the filtration chamber for 85 days and 2.60 in the primary anoxic zone for 111 days. Addition of ferrous salts to the anoxic zone achieved a final effluent phosphorous concentration (mg-P/L) of <0.05 (29%), <0.15 (77%) and <0.30 (95%), while addition of ferrous salts in the filtration zone achieved <0.05 (18%), <0.15 (63%) and <0.30 (95%). Analysis of the concentration of iron(II) in the supernatant indicated that phosphorus was mainly removed via adsorption to amorphous iron oxyhydroxides particles in both dosing scenarios. However, analysis of residence time distribution (RTD) data of the reactor indicated that severe short-circuiting from the dosing point to the membrane outlet could occur when the ferrous salts were added to the membrane zone while the reactor behaved close to a completely mixed reactor when dosing to the primary anoxic zone, resulting in improved phosphorus removal. The addition of ferrous salt was also found to delay the onset of severe increase in trans-membrane pressure as a result of the removal of macro-molecules. However, detailed analysis of the form and concentration of iron species in the supernatant and permeate indicated that the presence of fine iron particles resulted in a higher fouling rate when Fe(II) was added to the membrane zone rather than the primary anoxic zone and could cause more severe irreversible fouling in long-term operation. PMID:24709534

Wang, Yuan; Tng, K Han; Wu, Hao; Leslie, Greg; Waite, T David

2014-06-15

159

Proton-linked subunit heterogeneity in ferrous nitrosylated human adult hemoglobin: an EPR study.  

PubMed

The effect of pH on the X-band electron paramagnetic resonance (EPR) spectrum of ferrous nitrosylated human adult tetrameric hemoglobin (HbNO) as well as of ferrous nitrosylated monomeric alpha- and beta-chains has been investigated, at -163 degrees C. At pH 7.3, the X-band EPR spectrum of tetrameric HbNO and ferrous nitrosylated monomeric alpha- and beta-chains displays a rhombic shape. Lowering the pH from 7.3 to 3.0, tetrameric HbNO and ferrous nitrosylated monomeric alpha- and beta-chains undergo a transition towards a species characterized by a X-band EPR spectrum with a three-line splitting centered at 334mT. These pH-dependent spectroscopic changes may be taken as indicative of the cleavage, or the severe weakening, of the proximal HisF8-Fe bond. In tetrameric HbNO, the pH-dependent spectroscopic changes depend on the acid-base equilibrium of two apparent ionizing groups with pK(a) values of 5.8 and 3.8. By contrast, the pH-dependent spectroscopic changes occurring in ferrous nitrosylated monomeric alpha- and beta-chains depend on the acid-base equilibrium of one apparent ionizing group with pK(a) values of 4.8 and 4.7, respectively. The different pK(a) values for the proton-linked spectroscopic transition(s) of tetrameric HbNO and ferrous nitrosylated monomeric alpha- and beta-chains suggest that the quaternary assembly drastically affects the strength of the proximal HisF8-Fe bond in both subunits. This probably reflects a 'quaternary effect', i.e., structural changes in both subunits upon tetrameric assembly, which is associated to a relevant variation of functional properties (i.e., proton affinity). PMID:15833350

Ascenzi, Paolo; Bocedi, Alessio; Fasano, Mauro; Gioia, Magda; Marini, Stefano; Coletta, Massimo

2005-05-01

160

A rapid, simple questionnaire to assess gastrointestinal symptoms after oral ferrous sulphate supplementation  

PubMed Central

Background Oral iron supplementation is often associated with rapid onset of gastrointestinal side-effects. The aim of this study was to develop and trial a short, simple questionnaire to capture these early side-effects and to determine which symptoms are more discriminating. Methods The study was a double-blind placebo-controlled randomized parallel trial with one week treatment followed by one week wash-out. Subjects were randomized into two treatment groups (n?=?10/group) to receive either ferrous sulphate (200 mg capsules containing 65 mg of iron) or placebo, both to be taken at mealtimes twice daily during the treatment period. Subjects completed the questionnaires daily for 14 days. The questionnaire included gastrointestinal symptoms commonly reported to be associated with the oral intake of ferrous iron salts (i.e. nausea, vomiting, heartburn, abdominal pain, diarrhoea, and constipation). Results Seventy five per cent of participants reporting the presence of one or more symptoms in the first week of the study were in the ferrous sulphate group. In the second week of the study (i.e. wash-out), 67% of the participants reporting one or more symptom(s) were in the ferrous sulphate group. In the first week of the study (treatment) the number of symptoms reported by participants in the ferrous sulphate group (mean?±?SEM?=?6.7?±?1.7) was significantly higher than that for participants in the placebo group (1.2?±?0.5) (p?=?0.01). In the second week of the study (wash-out) the number of symptoms reported by participants in the ferrous sulphate group (4.6?±?2.0) appeared higher than for participants in the placebo group (1.0?±?0.7) although this did not reach significance (p?=?0.12). Events for which the gastrointestinal symptom questionnaire was most discriminatory between ferrous sulphate and placebo groups were: heartburn, abdominal pain and the presence of black stools (all p???0.03). Conclusions A tool for the detection of commonly-occurring side effects should not require large study numbers to be effective. With just 10 subjects per group (iron or placebo), this simple questionnaire measures gastrointestinal side-effects associated with oral iron (ferrous sulphate) supplementation, and would be appropriate for use in intervention studies or clinical trials. Trial registration ClinicalTrials.gov Identifier: NCT02146053 (21/05/2014).

2014-01-01

161

Electron-transfer reduction of 1-deoxy-1-nitroalditols to glycamines with ferrous hydroxide.  

PubMed

Treatment of eight different 1-deoxy-1-nitroalditols with freshly prepared ferrous hydroxide at ambient temperature provides the corresponding glycamines that were isolated in 81-94% yields as salts with TFA. Under such modified reaction conditions, the retro-Henry reaction of the starting compounds is significantly suppressed due to the amphoteric character of the reducing agent in water. Lower, 58-75% yields were obtained by the classical process with ferrous sulfate in aqueous ammonia and employing an improved purification procedure for the product glycamines by irreversible capture of sulfate ions with barium carbonate. PMID:23123574

Pribulová, Božena; Petrušová, Mária; Smrti?ová, Hana; Petruš, Ladislav

2012-12-01

162

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

163

Iodine stability in iodized salt dual fortified with microencapsulated ferrous fumarate made by an extrusion-based encapsulation process  

Microsoft Academic Search

The development of a novel, extrusion-based process for making microencapsulated ferrous fumarate for salt double fortification has been reported earlier. This paper focuses on the results of a one-year storage test, specifically the stability of both iodine and ferrous iron in the double fortified salt (DFS) samples prepared using optimal formulations of the iron premix. The study was devised to

Yao O. Li; Levente L. Diosady; Annie S. Wesley

2010-01-01

164

Determination of 3D dose distribution from intracavitary brachytherapy of cervical cancer by MRI of irradiated ferrous sulphate gel  

Microsoft Academic Search

Background and purpose: MRI ferrous sulphate gel dosimetry has proven to be a valuable method for assessment of dose delivered in teletherapy. The intention of this study was to investigate ferrous sulphate gel as a possible dosimeter for intracavitary brachytherapy applications.Materials and methods: A plastic duplicate of a cervix ring applicator set was submerged in Fe2+-infused gelatin gel. The gel

Bjørn H. Knutsen; Arne Skretting; Taran P. Hellebust; Dag R. Olsen

1997-01-01

165

Thermal studies of some divalent metal chelates of croconic acid  

Microsoft Academic Search

The thermal properties of chelates of croconic acid and squaric acid with divalent copper, cobalt, nickel and zinc have been investigated by TG and DTA. The decreasing order of thermal stability for the decomposition of the croconate chelates was Ni > > Zn > Co=Cu and for the squarate complexes, Zn > Co=Cu > Ni. The copper croconate TG showed

R. S. Bottei; H. S. Chang; D. A. Lusardi

1979-01-01

166

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

167

Grafting of Some Carbohydrates with Multi-Group Chelating Monomer  

Microsoft Academic Search

Graft copolymerization reactions onto some polysaccarides were carried out using acryloylcyanoacetohydrazide (ACAH) as chelating monomer. Different grafting variables onto chitin were studied, namely time, temperature, concentrations of monomer and initiator. Grafting by the prementioned chelating monomer was also carried out on chitosan and bagasse raw materials for different periods. The grafting parameters obtained were compared with those values of PACAH-grafted

Houssni El-Saied; Altaf H. Basta

1999-01-01

168

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

169

The significance of copper chelators in clinical and experimental application.  

PubMed

The essentiality and redox-activity of copper make it indispensable in the mammalian system. However, a comprehensive understanding of copper metabolism and function has not been achieved. Copper chelators have been used as an approach to provide insights into copper acquisition, distribution, and disposition at both the cellular and organism level. Unfortunately, the understanding of effective copper chelators is predominantly based upon their chemical structures and their reactions with copper. The understanding of the efficacy of copper chelators in the biological system has been equivocal, thereby leading to under- or misleading-utilization of these agents in clinical and experimental approaches. Current use of copper chelators in vivo almost exclusively either limits the availability or focuses on the removal of copper in mammalian organ system. There are at least two aspects of copper chelators that are yet to be explored. First, copper chelators preferentially bind either cuprous or cupric. As a result, they potentially modulate copper redox-activity without removing copper from the system. Second, copper chelators are characterized as either membrane-permeable or -impermeable, thus would serve as an organ-selective copper delivery or deprivation system to manipulate the biological function of copper. Here we review clinically relevant copper chelators that have been experimentally or clinically studied for their role in manipulation of copper metabolism and function, paying critical attention to potentially more valuable usage of these agents. PMID:21109416

Ding, Xueqin; Xie, Huiqi; Kang, Y James

2011-04-01

170

Influence of iron chelation on the antioxidant activity of flavonoids  

Microsoft Academic Search

The antioxidant activity of flavonoids is believed to be caused by a combination of iron chelation and free radical scavenging activities. Several authors have attempted to separate the iron chelation and scavenging activity of flavonoids in order to study these processes individually. There are, however, several contradictions in the literature, and the outcome largely depends on the experimental conditions and

Saskia A. B. E van Acker; Georgette Plemper van Balen; Aalt Bast; Wim J. F van der Vijgh

1998-01-01

171

Iron chelators induce autophagic cell death in multiple myeloma cells.  

PubMed

We examined the antineoplastic effects of the iron chelators, deferasirox and deferoxamine in multiple myeloma cell lines as well as primary myeloma cells. These iron chelators showed marked antiproliferative activity as well as cytotoxicity toward myeloma cell lines and deferasirox was cytotoxic to bone marrow plasma cells from myeloma patients. We also demonstrate that autophagy induced by iron deprivation is the dominant mechanism that mediates the cytotoxicity of iron chelators in multiple myeloma. Exposure to iron chelators led to repression of mTOR signaling as evidenced by decreased phosphorylation of its target p70S6 kinase. Iron chelation, in particular with deferasirox has the potential to be readily translated to a clinical trial for multiple myeloma. PMID:24998390

Pullarkat, Vinod; Meng, Zhuo; Donohue, Cecile; Yamamoto, Vicky N; Tomassetti, Sarah; Bhatia, Ravi; Krishnan, Amrita; Forman, Stephen J; Synold, Timothy W

2014-08-01

172

Clawing Back: Broadening the Notion of Metal Chelators in Medicine  

PubMed Central

The traditional notion of chelation therapy is the administration of a chemical agent to remove metals from the body. But formation of a metal-chelate can have biological ramifications that are much broader than metal elimination. Exploring these other possibilities could lead to pharmacological interventions that alter the concentration, distribution, or reactivity of metals in targeted ways for therapeutic benefit. This review highlights recent examples that showcase four general strategies of using principles of metal chelation in medicinal contexts beyond the traditional notion of chelation therapy. These strategies include altering metal biodistribution, inhibiting specific metalloenzymes associated with disease, enhancing the reactivity of a metal complex to promote cytotoxicity, and conversely, passivating the reactivity of metals by site-activated chelation to prevent cytotoxicity.

Franz, Katherine J.

2013-01-01

173

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

174

Trypanosoma brucei brucei: effects of ferrous iron and heme on ecto-nucleoside triphosphate diphosphohydrolase activity.  

PubMed

Trypanosoma brucei brucei is the causative agent of animal African trypanosomiasis, also called nagana. Procyclic vector form resides in the midgut of the tsetse fly, which feeds exclusively on blood. Hemoglobin digestion occurs in the midgut resulting in an intense release of free heme. In the present study we show that the magnesium-dependent ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase) activity of procyclic T. brucei brucei is inhibited by ferrous iron and heme. The inhibition of E-NTPDase activity by ferrous iron, but not by heme, was prevented by pre-incubation of cells with catalase. However, antioxidants that permeate cells, such as PEG-catalase and N-acetyl-cysteine prevented the inhibition of E-NTPDase by heme. Ferrous iron was able to induce an increase in lipid peroxidation, while heme did not. Therefore, both ferrous iron and heme can inhibit E-NTPDase activity of T. brucei brucei by means of formation of reactive oxygen species, but apparently acting through distinct mechanisms. PMID:19027737

Leite, Milane S; Thomaz, Rachel; Oliveira, José Henrique M; Oliveira, Pedro L; Meyer-Fernandes, José Roberto

2009-02-01

175

Ferrous sulphate oxidation using Thiobacillus ferrooxidans cells immobilised in polyurethane foam support particles  

Microsoft Academic Search

Oxidation of ferrous iron by Thiobacillus ferrooxidans cells passively immobilised in polyurethane foam particles, using both repeated batches and continuous operation, was studied in a laboratory-scale reactor. Repeated batches yielded complete oxidation at higher rates than single batches, providing resident inocula for subsequent batches. In continuous operation maximum ferric iron productivities were achieved at dilution rates well above theoretical washout

H. Armentia; C. Webb

1992-01-01

176

Ceric and ferrous dosimeters show precision for 50-5000 rad range  

NASA Technical Reports Server (NTRS)

Ammonium thiocyanate, added to the usual ferrous sulfate dosimeter solution, yielded a very stable, precise and temperature-independent system eight times as sensitive as the classical Fricke system in the 50 to 5000 rad range. The ceric dosimeters, promising for use in mixed radiation fields, respond nearly independently of LET.

Frigerio, N. A.; Henry, V. D.

1968-01-01

177

Cadmium in the food chain near non-ferrous metal production sites  

Microsoft Academic Search

Dietary cadmium (Cd) exposure was estimated for adults living in Cd-contaminated areas close to non-ferrous metal plants and compared with dietary Cd exposure in the general Belgian adult population. To evaluate the contamination levels of locally produced food items, 35 fruit samples, 97 vegetable samples, 98 samples of potatoes and 53 samples of meat, liver and kidney of cattle, which

V. Vromman; C. Saegerman; L. Pussemier; A. Huyghebaert; L. DE Temmerman; J.-C. Pizzolon; N. Waegeneers

2008-01-01

178

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

179

Specificity of the ferrous oxidation of xylenol orange assay: analysis of autoxidation products of cholesteryl arachidonate  

Microsoft Academic Search

Autoxidation of polyunsaturated fatty acids and esters leads to a complex mixture containing hydroperoxides and cyclic peroxides. The oxidation mixture of cholesteryl arachidonate, which has been characterized by a variety of mass spectrometry techniques, was subject to analysis by conventional thiobarbituric acid-reactive substance (TBARS) and ferrous oxidation in xylenol orange (FOX) assays. Our results indicate that the FOX assay is

Huiyong Yin; Ned A Porter

2003-01-01

180

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

181

Copper and Silver Recovery from a Sulfide Concentrate by Ferrous Chloride-Oxygen Leaching.  

National Technical Information Service (NTIS)

A ferrous chloride-oxygen leaching system was investigated by the Federal Bureau of Mines to determine its effectiveness for recovering copper and silver from a tetrahedrite concentrate that had been pretreated to remove a majority of the antimony. The pr...

B. J. Scheiner G. A. Smyres P. R. Haskett R. E. Lindstrom

1978-01-01

182

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

183

ORGANIC EMISSIONS FROM FERROUS METALLURGICAL INDUSTRIES: COMPILATION OF EMISSION FACTORS AND CONTROL TECHNOLOGIES  

EPA Science Inventory

The report gives results of a review and analysis of the information and data available in the public domain on organic emissions from the ferrous metallurgy industry, specifically the iron and steel, iron foundry, and ferroalloy industries. Emission sources and information gaps ...

184

ANALYSIS OF FERRIC AND FERROUS IONS IN SOIL EXTRACTS BY ION CHROMATOGRAPHY  

EPA Science Inventory

A method using ion chromatography (IC) for the analysis of ferrous (Fe 2+) and ferric (Fe 3+) ions in soil extracts has been developed. This method uses an ion exchange column with detection at 520 nm after post-column derivatization. Selectivity is achieved by using an anionic...

185

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

186

Martian weathering/alteration scenarios from spectral studies of ferric and ferrous minerals  

NASA Technical Reports Server (NTRS)

We review the major aspects of our current knowledge of martian ferric and ferrous mineralogy based on the available ground-based telescopic and spacecraft data. What we know and what we don't know are used to constrain various weathering/alteration models and to identify key future measurements and techniques that can distinguish between these models.

Bell, James F., III; Adams, John B.; Morris, Richard V.

1992-01-01

187

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

Microsoft Academic Search

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,

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

1986-01-01

188

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

Microsoft Academic Search

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

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

2011-01-01

189

Recovery of iron as a form of ferrous acetate precipitates from low-grade magnetite ore  

Microsoft Academic Search

This paper describes the recovery process of iron as a form of ferrous acetate from low-grade magnetite ore (Shinyemi Mine, Gangwon province, Korea). The magnetically separated magnetite powder was dissolved in aqueous oxalic acid solution. The dissolution fraction of magnetite concentrates was measured as a function of initial pH, reaction temperature and oxalic acid concentration. Optimum conditions for dissolution of

Jae-Kyeong Kim; Han-Sang Oh; Chang-Wha Jo; Yong-Jae Suh; Hee-Dong Jang; Kee-Kahb Koo

2010-01-01

190

Full-Scale Implementation of the Sodium Sulfide/Ferrous Sulfate Treatment Process.  

National Technical Information Service (NTIS)

In Phase I, jar and dynamic testing showed that the sodium sulfide/ferrous sulfate process was a viable method for reducing hexavalent chromium and removing heavy metals from the Tinker AFB industrial wastewater with a significant decrease in sludge produ...

J. M. Beller G. S. Carpenter R. E. McAtee P. A. Pryfogle D. F. Suciu

1989-01-01

191

Oral administration of dihydroartemisinin and ferrous sulfate retarded implanted fibrosarcoma growth in the rat  

Microsoft Academic Search

In the presence of iron, dihydroartemisinin forms free radicals and causes cell death. Since most cancer cells have high rates of iron intake, dihydroartemisinin would have selective cytotoxic effect on cancer cells. The present experiment was designed to study the effect of dihydroartemisinin and ferrous sulfate on the growth of implanted fibrosarcoma in the rat. We found that the growth

James C. Moore; Henry Lai; Jian-Ren Li; Ru-Long Ren; John A. McDougall; Narendra P. Singh; Chung-Kwang Chou

1995-01-01

192

Effects of Ferrous Iron Toxicity on the Growth and Mineral Composition of an Interspecific Rice  

Microsoft Academic Search

Ferrous iron (Fe) toxicity is one of the major constraints to lowland rice production. It disrupts the rice plant physiology in several respects. The critical iron toxicity concentration in plant tissue depends partly on the overall nutritional status of the plant. African cultivars are generally less sensitive to this stress than Asian ones, but their yield potential is significantly lower.

Sophie De Dorlodot; Stanley Lutts; Pierre Bertin

2005-01-01

193

Peroxynitrite-mediated oxidation of ferrous carbonylated myoglobin is limited by carbon monoxide dissociation.  

PubMed

Peroxynitrite-mediated oxidation of ferrous nitrosylated myoglobin (Mb(II)-NO) involves the transient ferric nitrosylated species (Mb(III)-NO), followed by ()NO dissociation and formation of ferric myoglobin (Mb(III)). In contrast, peroxynitrite-mediated oxidation of ferrous oxygenated myoglobin (Mb(II)-O2) involves the transient ferrous deoxygenated and ferryl derivatives (Mb(II) and Mb(IV)O, respectively), followed by Mb(III) formation. Here, kinetics of peroxynitrite-mediated oxidation of ferrous carbonylated horse heart myoglobin (Mb(II)-CO) is reported. Values of the first-order rate constant for peroxynitrite-mediated oxidation of Mb(II)-CO (i.e., for Mb(III) formation) and of the first-order rate constant for CO dissociation from Mb(II)-CO (i.e., for Mb(II) formation) are h=(1.2+/-0.2)x10(-2)s(-1) and k(off(CO))=(1.4+/-0.2)x10(-2)s(-1), respectively, at pH 7.2 and 20.0 degrees C. The coincidence of values of h and k(off(CO)) indicates that CO dissociation represents the rate limiting step of peroxynitrite-mediated oxidation of Mb(II)-CO. PMID:17910950

Ascenzi, Paolo; Ciaccio, Chiara; Coletta, Massimo

2007-11-30

194

Radiation-chemical and MR studies of aqueous agarose gels containing ferrous ions  

SciTech Connect

Aqueous agarose gels containing ferrous ions, in 0.05 N sulfuric acid have been studied after irradiation with 6-18 MeV electrons or {sup 137}Cs {gamma}-rays. Such gels can sustain a radiolytic chain reaction, producing Fe{sup 3+} with G (Fe{sup 3+})-values up to 100 having been observed. The Fe{sup 3+} production is independent of dose rate between 0.434 and 3.74 Gy min{sup {minus}1}. Dissolved oxygen is needed to maintain the chain reaction, and initial ferric yields are increased if the gel is oxygen saturated or if the ferrous concentration is decreased below 1 mM. The oxidation of ferrous to ferric alters the magnetic moment of the ion and its electron spin relaxation time, which in turn affects its ability to promote proton spin relaxation rates. Longitudinal proton magnetic relaxation rates are increased in proportion to ferric production, permitting visualization of dose levels in these gels by magnetic resonance imaging (MRI) techniques. Non-uniform dose distribution images of electron irradiated ferrous/agarose (FA) systems have been obtained using MRI. Images of radiation doses surrounding capillary tubes filled with radioactive material embedded in PA systems have also been obtained. In this work, another new method of using the ferrous/agarose gel system doped with xylenol orange to visualize the radiation dose distribution directly by eye has been developed. The color change developed depends both quantitatively and qualitatively on the concentrations of solutes in the gel.

Leghrous, A.A.

1989-01-01

195

Differential Protein Expression during Growth of Acidithiobacillus ferrooxidans on Ferrous Iron, Sulfur Compounds, or Metal Sulfides  

PubMed Central

A set of proteins that changed their levels of synthesis during growth of Acidithiobacillus ferrooxidans ATCC 19859 on metal sulfides, thiosulfate, elemental sulfur, and ferrous iron was characterized by using two-dimensional polyacrylamide gel electrophoresis. N-terminal amino acid sequencing and mass spectrometry analysis of these proteins allowed their identification and the localization of the corresponding genes in the available genomic sequence of A. ferrooxidans ATCC 23270. The genomic context around several of these genes suggests their involvement in the energetic metabolism of A. ferrooxidans. Two groups of proteins could be distinguished. The first consisted of proteins highly upregulated by growth on sulfur compounds (and downregulated by growth on ferrous iron): a 44-kDa outer membrane protein, an exported 21-kDa putative thiosulfate sulfur transferase protein, a 33-kDa putative thiosulfate/sulfate binding protein, a 45-kDa putative capsule polysaccharide export protein, and a putative 16-kDa protein of unknown function. The second group of proteins comprised those downregulated by growth on sulfur (and upregulated by growth on ferrous iron): rusticyanin, a cytochrome c552, a putative phosphate binding protein (PstS), the small and large subunits of ribulose biphosphate carboxylase, and a 30-kDa putative CbbQ protein, among others. The results suggest in general a separation of the iron and sulfur utilization pathways. Rusticyanin, in addition to being highly expressed on ferrous iron, was also newly synthesized, as determined by metabolic labeling, although at lower levels, during growth on sulfur compounds and iron-free metal sulfides. During growth on metal sulfides containing iron, such as pyrite and chalcopyrite, both proteins upregulated on ferrous iron and those upregulated on sulfur compounds were synthesized, indicating that the two energy-generating pathways are induced simultaneously depending on the kind and concentration of oxidizable substrates available.

Ramirez, Pablo; Guiliani, Nicolas; Valenzuela, Lissette; Beard, Simon; Jerez, Carlos A.

2004-01-01

196

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

197

Chelation: Harnessing and Enhancing Heavy Metal Detoxification--A Review  

PubMed Central

Toxic metals such as arsenic, cadmium, lead, and mercury are ubiquitous, have no beneficial role in human homeostasis, and contribute to noncommunicable chronic diseases. While novel drug targets for chronic disease are eagerly sought, potentially helpful agents that aid in detoxification of toxic elements, chelators, have largely been restricted to overt acute poisoning. Chelation, that is multiple coordination bonds between organic molecules and metals, is very common in the body and at the heart of enzymes with a metal cofactor such as copper or zinc. Peptides glutathione and metallothionein chelate both essential and toxic elements as they are sequestered, transported, and excreted. Enhancing natural chelation detoxification pathways, as well as use of pharmaceutical chelators against heavy metals are reviewed. Historical adverse outcomes with chelators, lessons learned in the art of using them, and successes using chelation to ameliorate renal, cardiovascular, and neurological conditions highlight the need for renewed attention to simple, safe, inexpensive interventions that offer potential to stem the tide of debilitating, expensive chronic disease.

Sears, Margaret E.

2013-01-01

198

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

199

Luminescent Properties of Eu(III) Chelates on Metal Nanorods  

PubMed Central

In this article, we report the change of optical properties for europium chelates on silver nanorods by near-field interactions. The silver rods were fabricated in a seed-growth method followed by depositing thin layers of silica on the surfaces. The europium chelates were physically absorbed in the silica layers on the silver rods. The silver rods were observed to exhibit two plasmon absorption bands from longitudinal and transverse directions, respectively, centered at 394 and 675 nm, close to absorption and emission bands from the Eu(III) chelates. As a result, the immobilized Eu(III) chelates on the silver rods should have strong interactions with the silver nanorods and lead to greatly improved optical properties. The Eu–Ag rod complexes were observed to have enhanced emission intensity up to 240-fold in comparison with the Eu(III) chelates in the metal-free silica templates. This enhancement is much larger than the value for the Eu(III) chelates on the gold rods or silver spheres indicating the presence of stronger interactions for the Eu(III) chelates with the silver rods. The interactions of Eu(III) chelates with the silver rods were also proven by extremely reduced lifetime. Moreover, the Eu–Ag rod complexes exhibited a polarized emission, which was also due to strong interactions of the Eu(III) chelates with the silver rods. All of these features may promise that the Eu(III)–Ag rod complexes have great potential for use as fluorescence imaging agents in biological assays.

Zhang, Jian; Fu, Yi; Ray, Krishanu; Wang, Yuan; Lakowicz, Joseph. R.

2013-01-01

200

[Dithiols as chelators. A cause of bullous skin reactions].  

PubMed

Chelation therapy with (RS)-2,3-Bis(sulfonyl)propane-1-sulfonic acid (DMPS) after an occupational lead exposure led to the development of a severe bullous drug eruption. Skin tests and histology/immunohistology of the test reactions indicated a T-cell-mediated immune response against DMPS. Metal-binding thiol groups as in DMPS are chemically highly reactive and therefore effectively mediate the development of immunogenic hapten (DMPS)-protein complexes. Therefore, the pharmacological effects and sensitization potential of dithiols are tightly connected. Cross-reactivity of DMPS to other chelators like D-penicillamine is possible; the indications for chelation therapy should be weighed carefully. PMID:20945055

Storim, J; Stoevesandt, J; Anders, D; Kneitz, H; Bröcker, E-B; Trautmann, A

2011-03-01

201

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

Fernández, Victoria; Winkelmann, Günther

2005-02-01

202

Development of multi-functional chelators based on sarcophagine cages.  

PubMed

A new class of multifunctionalized sarcophagine derivatives was synthesized for 64Cu chelation. The platform developed in this study could have broad applications in 64Cu-radiopharmaceuticals. PMID:24705567

Liu, Shuanglong; Li, Zibo; Conti, Peter S

2014-01-01

203

Metal chelate process to remove pollutants from fluids  

DOEpatents

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. 26 figures.

Chang, S.G.T.

1994-12-06

204

Minding metals: tailoring multifunctional chelating agents for neurodegenerative disease.  

PubMed

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 Abeta peptide aggregation, or inhibit disease-associated enzymes such as monoamine oxidase and acetylcholinesterase. PMID:20162187

Perez, Lissette R; Franz, Katherine J

2010-03-01

205

Metal chelate process to remove pollutants from fluids  

DOEpatents

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

206

Comparing potential copper chelation mechanisms in Parkinson's disease protein  

NASA Astrophysics Data System (ADS)

We have implemented the nudged elastic band (NEB) as a guided dynamics framework for our real-space multigrid method of DFT-based quantum simulations. This highly parallel approach resolves a minimum energy pathway (MEP) on the energy hypersurface by relaxing intermediates in a chain-of-states. As an initial application we present an investigation of chelating agents acting on copper ion bound to ?-synuclein, whose misfolding is implicated in Parkinson's disease (PD). Copper ions are known to act as highly effective misfolding agents in a-synuclein and are thus an important target in understanding PD. Furthermore, chelation therapy has shown promise in the treatment of Alzheimer's and other neuro-degenerative diseases with similar metal-correlated pathologies. At present, our candidate chelating agents include nicotine, curcumin and clioquinol. We examine their MEP activation barriers in the context of a PD onset mechanism to assess the viability of various chelators for PD remediation.

Rose, Frisco; Hodak, Miroslav; Bernholc, Jerry

2011-03-01

207

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

2013-11-01

208

Cell assay using a two-photon-excited europium chelate  

PubMed Central

We report application of two-photon excitation of europium chelates to immunolabeling of epidermal growth factor receptor (EGFR) cell surface proteins on A431 cancer cells. The europium chelates are excited with two photons of infrared light and emit in the visible. Europium chelates are conjugated to antibodies for EGFR. A431 (human epidermoid carcinoma) cells are labeled with this conjugate and imaged using a multiphoton microscope. To minimize signal loss due to the relatively long-lived Eu3+ emission, the multiphoton microscope is used with scanning laser two-photon excitation and non-scanning detection with a CCD. The chelate labels show very little photobleaching (less than 1% during continuous illumination in the microscope for 20 minutes) and low levels of autofluorescence (less than 1% of the signal from labeled cells). The detection limit of the europium label in the cell assay is better than 100 zeptomoles.

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

2011-01-01

209

Modification of MSW fly ash by anionic chelating surfactant  

Microsoft Academic Search

This paper elucidates a study on the re-utilization and stabilization of municipal solid waste (MSW) fly ash in producing a high value-added product by the surface modification of anionic chelating surfactant on the particles. After modification, MSW fly ash can be expected using as a filler of ultra-high molecular weight polymers. The effects of anionic chelating surfactants (ACS) on surface

Guangren Qian; Houhu Zhang; Xiaolan Zhang; Peng-Cheong Chui

2005-01-01

210

Chelated Ruthenium Catalysts for Z-Selective Olefin Metathesis  

PubMed Central

We report the development of ruthenium-based metathesis catalysts with chelating N-heterocyclic carbene (NHC) ligands which catalyze highly Z-selective olefin metathesis. A very simple and convenient synthetic procedure of such a catalyst has been developed. An intramolecular C-H bond activation of the NHC ligand, which is promoted by anion ligand substitution, forms the appropriate chelate for stereo- controlled olefin metathesis.

Endo, Koji; Grubbs, Robert H.

2011-01-01

211

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

2009-07-01

212

Chelation of heavy metals by potassium butyl dithiophosphate.  

PubMed

Potassium butyl dithiophosphate (PBD) was developed and introduced as a new chelating agent for heavy metal removal. The synthesized PBD were characterized by IR and NMR. The effects of pH, chelating agent dosage, and other heavy metal ions on the performance of PBD in Cd2+ removal from water are investigated. Experimental results showed that the chelating agent could be used to treat acidic heavy metal wastewater. The Cd2+ removal was not affected by solution pH value within the range of 2 to 6. The Cd2+ removal rate could reach over 99%. Therefore, the deficiency of the precipitation process using hydroxide under alkaline condition can be overcome. Without the need for pH adjustment, the method could save on costs. If Cd2+ co-exists with Pb2+ and Cu2+, the affinity of the chelating agent with these three heavy metal ions was in the order of: Cu2+ > Pb2+ > Cd2+. Through PBD chelating precipitation, all the contents of Pb2+, Cd2+, and Cu2+ in wastewater met the standard levels through a one-step treatment. The one-step treatment process was superior to the process (sectional treatment is required) of precipitation with hydroxide. When the pH was between 3 and 11, the amount of leached chelated Cd2+ was much lower than that obtained by precipitation with hydroxide. Therefore, the risk of environmental pollution could be further reduced. PMID:21790050

Xu, Ying; Xie, Zhigang; Xue, Lu

2011-01-01

213

In vivo chemistry of 99mTc-chelates.  

PubMed

The structure-activity relationships involved in the in vivo localization and clearance of 99mTc-chelates is reviewed. Most 99mTc-chelates used for renal studies are mixed function agents and their uptake in the kidney is affected by the presence or absence of stannous ions; only a relatively few chelates are almost exclusively cleared from the body by glomerular filtration or tubular excretion. The uptake of 99mTc-phosphates and -phosphonates in metabolically active and metabolically inactive bone and the plasma clearance rate of these complexes depend upon the structure of the complexing ligand. 99mTc-chelates considered optimal for hepatobiliary imaging have a high liver extraction efficiency, are rapidly transported through the liver and have a comparatively slow renal clearance rate. Even though the elucidation of the in vivo behavior of 99mTc-chelates continues, quantitating structure-activity relationships requires that the structure of the chelates be carefully characterized, both before and after injection. PMID:7152711

Eckelman, W C; Volkert, W A

1982-10-01

214

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

215

Effectiveness of Ferrous Sulfate as an Inhibitor for Sulfide-Induced Corrosion of Copper-Nickel Alloys.  

National Technical Information Service (NTIS)

A program is described which investigates accelerated corrosion of ship piping systems during and after outfitting in polluted brackish harbor waters. As part of this program, various ferrous sulfate inhibitor treatments were evaluated in laboratory expos...

H. P. Hack

1977-01-01

216

Method for preparing radionuclide-labeled chelating agent-ligand complexes  

SciTech Connect

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, C.F.; Li, M.; DeNardo, S.J.

1999-09-28

217

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

218

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

2013-12-01

219

Possible Association of Ferrous Phosphates and Ferric Sulfates in S-rich Soil on Mars  

NASA Astrophysics Data System (ADS)

NASA Mars Exploration Rover (MER) Spirit explored Gusev Crater to look for signs of ancient aqueous activity, assess past environmental conditions and suitability for life. Spirit excavated light-toned, S-rich soils at several locations. These are likely of hydrothermal, possibly fumarolic origin. At a location dubbed Paso Robles the light-toned soil was also rich in P - a signature from surrounding rock. While S is mainly bound in ferric hydrated sulfates [1], the mineralogy of P is ill-constrained [2]. P is a key element for life and its mineralogy constrains its availability. Ferrous phases observed in Paso Robles Mössbauer spectra may represent olivine and pyroxene from surrounding basaltic soil [1] or ferrous phosphate minerals [3]. Phosphate is well-known to complex and stabilize Fe 2+ against oxidation to Fe 3+ . Schröder et al. [3] proposed a formation pathway of ferrous phosphate/ferric sulfate associations: sulfuric acid reacts with basalt containing apatite, forming CaSO4 and phosphoric acid. The phosphoric and/or excess sulfuric acid reacts with olivine, forming Fe2+-phosphate and sulfate. The phosphate is less soluble and precipitates. Ferrous sulfate remains in solution and is oxidized as pH increases. To verify this pathway, we dissolved Fe2+-chloride and Na-phosphate salts in sulfuric acid inside an anoxic glovebox. The solution was titrated to pH 6 by adding NaOH when a first precipitate formed, which was ferrous phosphate according to Mössbauer spectroscopy (MB). At that point the solution was removed from the glovebox and allowed to evaporate in the presence of atmospheric oxygen, leading to the oxidation of Fe2+. The evaporation rate was controlled by keeping the suspensions at different temperatures; pH was monitored during the evaporation process. The final precipitates were analyzed by MB and X-Ray Fluorescence (XRF), comparable to MER MB and Alpha Particle X-ray Spectrometer instrument datasets, and complementary techniques such as X-ray diffraction. Fourier Transform Infrared spectroscopy measurements to compare to MER miniature thermal emission spectrometer data are planned. We observed differences depending on the heat source during evaporation. The closest match to Martian data on the basis of Mössbauer spectra was achieved with a suspension evaporated at 80°C on a hot plate, i.e. heated from below with a temperature gradient in the bottle. The Fe2+/FeT ratio matched, and ferrous phases were all phosphate. When heated in a water bath, i.e. without a temperature gradient in the bottle, Fe2+/FeT ratios increased and ferrous sulfates precipitated also. These results indicate that the Martian light-toned S-rich deposits formed by evaporation on the surface where temperature gradients would be expected rather than underground. They confirm that ferrous phosphate/ferric sulfate associations are possible on Mars and could be preserved in the oxygen-free Martian atmosphere. References: [1] Morris et al., J.Geophys. Res. 111 (2006) E02S13; [2] Ming et al., J. Geophys. Res. 111 (2006) E02S12; [3] Schröder et al., GSA Annual Meeting 2008, Paper No. 171-3.

Mao, J.; Schroeder, C.; Haderlein, S.

2012-12-01

220

Effective chelation of iron in beta thalassaemia with the oral chelator 1,2-dimethyl-3-hydroxypyrid-4-one  

Microsoft Academic Search

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

G J Kontoghiorghes; M A Aldouri; A V Hoffbrand; J Barr; B Wonke; T Kourouclaris; L Sheppard

1987-01-01

221

Structural Basis of the Ferrous Iron Specificity of the Yeast Ferroxidase, Fet3p †  

Microsoft Academic Search

Fet3p is a multicopper oxidase (MCO) that functions together with the iron permease, Ftr1p, to support high-affinity Fe uptake in yeast. Fet3p is a ferroxidase that, like ceruloplasmin and hephaestin, couples the oxidation of 4 equiv of FeII to the reduction of O2 to 2H2O. The ferrous iron specificity of this subclass of MCO proteins has not been delineated by

Christopher S. Stoj; Anthony J. Augustine; Lynn Zeigler; Edward I. Solomon; Daniel J. Kosman

2006-01-01

222

Cytoplasmic ATPase involved in ferrous ion uptake from magnetotactic bacterium Magnetospirillum magneticum AMB-1  

Microsoft Academic Search

A non-magnetic mutant of Magnetospirillum magneticum AMB-1 (NMA61), harboring a defective gene located in ORF4 (gene ID: amb4111) was generated by transposon mutagenesis. Biochemical characterization of the gene product of ORF4 revealed that it was localized in the cytoplasm and displayed ATPase activity. The ability of NMA61 to take up iron was severely compromised. Ferrous ion concentration in the medium

Takeyuki Suzuki; Yoshiko Okamura; Atsushi Arakaki; Haruko Takeyama; Tadashi Matsunaga

2007-01-01

223

Pricing of non-ferrous metals futures on the London Metal Exchange  

Microsoft Academic Search

The London Metal Exchange (LME) is the most important centre for spot and futures trading in the main industrially-used non-ferrous metals. In this study, data on 3-month futures contracts for aluminium, aluminium alloy, copper, lead, nickel, tin, and zinc are analysed. The risk premium hypothesis and the cost-of-carry model are the standard theoretical models for pricing futures contracts, but these

Clinton Watkins; Michael McAleer

2006-01-01

224

Application of the ferrous oxidation–xylenol orange assay for the screening of 5-lipoxygenase inhibitors  

Microsoft Academic Search

5-Lipoxygenase (5-LO) is the key enzyme involved in leukotriene synthesis and its improper regulation is implicated in several inflammatory diseases. A rapid and sensitive assay for 5-LO activity suitable for high-throughput format is not yet available. In this study, we examined whether the ferrous oxidation–xylenol orange (FOX) assay could be applicable for the high-throughput screening of 5-LO inhibitors. Using insect

Young Sik Cho; Hyo Sun Kim; Chi Hyun Kim; Hyae Gyeong Cheon

2006-01-01

225

Reevaluation of the ferrous oxidation in xylenol orange assay for the measurement of plasma lipid hydroperoxides  

Microsoft Academic Search

The ferrous oxidation in xylenol orange version 2 (FOX2) assay coupled with triphenylphosphine has recently been employed for the measurement of total plasma hydroperoxides (ROOHs). In this study, we have evaluated sample handling and the effect of storage conditions on ROOH levels in human plasma (n=32). Mean level of ROOHs in fresh plasma was 8.35±3.09 ?mol\\/l (range 4.03–19.5 ?mol\\/l). Addition

Eva Södergren; Jaffar Nourooz-Zadeh; Lars Berglund; Bengt Vessby

1998-01-01

226

Advanced Oxidation Protein Products, Ferrous Oxidation in Xylenol Orange, and Malondialdehyde Levels in Thyroid Cancer  

Microsoft Academic Search

Aims and Background  The oxidation of protein plays an essential role in the pathogenesis of an important number of degenerative and cancer diseases,\\u000a which is now widely recognized. The aim is to examine advanced oxidation protein products (AOPPs), lipid peroxidation products\\u000a malondialdehyde (MDA), and ferrous oxidation in xylenol orange (FOX) in blood samples of papillary thyroid cancer patients\\u000a compared with healthy

Funda Kosova; Bahad?r Çetin; Melih Ak?nc?; Sabahattin Aslan; Zeki Ar?; Aylin Sepici; Nilgün Altan; Abdullah Çetin

2007-01-01

227

Ferric-ferrous equilibria in natural silicate liquids at 1 bar  

Microsoft Academic Search

Ferric and ferrous iron concentrations have been measured in 57 silicate liquids equilibrated at temperatures (1,200°–1,330°C) above the liquidus and at oxygen fugacities close to those defined by quartz-fayalite-magnetite. The experimental results reported here span virtually the entire known compositional range of lavas. An empirical equation relating the mole fraction of Fe2O3 and FeO to oxygen fugacity, absolute temperature and

R. O. Sack; I. S. E. Carmichael; M. Rivers; M. S. Ghiorso

1981-01-01

228

Optimal conditions for bio-oxidation of ferrous ions to ferric ions using Thiobacillus ferrooxidans  

Microsoft Academic Search

A chemo-biochemical process using Thiobacillus ferrooxidans for desulphurization of gaseous fuels and emissions containing hydrogen sulphide (H2S) has been developed. In the first stage, H2S present in fuel gas and emissions is selectively oxidized to elemental sulphur using ferric sulphate. The ferrous sulphate produced in the first stage of the process is oxidized to ferric sulphate using Thiobacillus ferrooxidans for

S. Malhotra; A. S. Tankhiwale; A. S. Rayvaidya; R. A. Pandey

2002-01-01

229

Predictions of scenarios for the consumption of scrap metal in ferrous metallurgy  

Microsoft Academic Search

This article analyzes the development of a method for using secondary sources of iron in ferrous metallurgy and examines the\\u000a main models that have been created in the EC nations and Japan in recent decades to optimize the recycling of dormant scrap.\\u000a Various national and regional models now exist to describe the production and consumption of steel products. Optimizing the

O. V. Golubev; A. S. Korotchenko; P. I. Chernousov

2011-01-01

230

Immobilization of Acidithiobacillus ferrooxidans by a PVA–boric acid method for ferrous sulphate oxidation  

Microsoft Academic Search

Acidithiobacillus ferrooxidans was immobilized in poly(vinyl alcohol) (PVA) by a PVA–boric acid method, and spherical beads of uniform size were produced. Biooxidation of ferrous iron by immobilized cells was investigated in repeated batch culture and continuous operation in a laboratory scale packed-bed bioreactor. During repeated batch culture, the cell-immobilized gels were stable and showed high constant iron-oxidizing activity. In continuous

Zhong-er Long; Yunhong Huang; Zhaoling Cai; Wei Cong; Fan Ouyang

2004-01-01

231

Arsenic removal from aqueous solution using ferrous based red mud sludge  

Microsoft Academic Search

Ferrous based red mud sludge (FRS) which combined the iron–arsenic co-precipitation and the high arsenic adsorption features was developed aimed at low arsenic water treatment in rural areas. Arsenic removal studies shown that FRS in dosage of 0.2 or 0.3g\\/l can be used effectively to remove arsenic from aqueous solutions when initial As(V) concentration was 0.2 or 0.3mg\\/l. Meanwhile, turbidity

Yiran Li; Jun Wang; Zhaokun Luan; Zhen Liang

2010-01-01

232

Stress corrosion cracking of several high strength ferrous and nickel alloys  

NASA Technical Reports Server (NTRS)

The stress corrosion cracking resistance of several high strength ferrous and nickel base alloys has been determined in a sodium chloride solution. Results indicate that under these test conditions Multiphase MP35N, Unitemp L605, Inconel 718, Carpenter 20Cb and 20Cb-3 are highly resistant to stress corrosion cracking. AISI 410 and 431 stainless steels, 18 Ni maraging steel (250 grade) and AISI 4130 steel are susceptible to stress corrosion cracking under some conditions.

Nelson, E. E.

1971-01-01

233

Scanning electrochemical microscopy measurement of ferrous ion fluxes during localized corrosion of steel  

Microsoft Academic Search

Local fluxes of ferrous ions at low carbon steel surfaces coated with tin and an epoxy-phenolic resin on tinplate samples, and at chrome steel (tin-free steel) have been monitored by oxidation of Fe2+ ions at the tip of a Pt scanning electrochemical microscope (SECM). The samples were immersed in 10mM H2SO4 in order to avoid Fe(OH)3 precipitation. The SECM was

Edgar Völker; Carlota González Inchauspe; Ernesto J. Calvo

2006-01-01

234

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

235

Bioavailability of microencapsulated ferrous sulfate in powdered milk produced from fortified fluid milk: a prophylactic study in rats  

Microsoft Academic Search

OBJECTIVE: We investigated the iron bioavailability of microencapsulated ferrous sulfate (SFE-171) in a diet based on powdered milk by using the prophylactic method in rats.METHODS: The SFE-171 was added into fluid milk and industrially processed into powdered milk, which was then mixed in our laboratory with a normalized diet (17.2 ± 2.1 mg Fe\\/kg). A reference standard diet using ferrous

Alexis E Lysionek; Marcela B Zubillaga; Mar??a J Salgueiro; Adriana Piñeiro; Ricardo A Caro; Ricardo Weill; José R Boccio

2002-01-01

236

Molecular aspects of the electron transfer system which participates in the oxidation of ferrous ion by Thiobacillus ferrooxidans.  

PubMed

The enzymes and redox proteins, which participate in the oxidation of ferrous ion by the acidophilic iron-oxiding bacterium Thiobacillus ferrooxidans, have been isolated and characterized. They are Fe(II)-cytochrome c oxidoreductase, cytochromes c-552(s), c-552(m) and c-550(m), rusticyanin, and cytochrome c oxidase. On the basis of the interactions of these components, an electron transfer system has been proposed which seems to function in the oxidation of ferrous ion by the bacterium. PMID:8845189

Yamanaka, T; Fukumori, Y

1995-12-01

237

The role of organic ligands in ferrous-induced photochemical degradation of 2,4-dichlorophenoxyacetic acid  

Microsoft Academic Search

Recent studies have shown that hydrogen peroxide is generated in a ferrioxalate-induced photoreductive reaction, but information about the effect of organic ligands on the photochemical behaviour of ferrous species is limited. The degradation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) by a ferrous-catalyzed oxidation in the presence of various ligands such as formate, citrate, malelate, oxalate, and ethylenediaminetetra-acetic acid (EDTA) was

C. Y. Kwan; W. Chu

2007-01-01

238

Potential of Thiobacillus ferrooxidans for waste gas purification. Part 2. Increase in continuous ferrous iron oxidation kinetics using immobilized cells  

Microsoft Academic Search

Thiobacillus ferrooxidans could be used to regenerate ferrous sulphate solution produced in a process to remove H2S from waste gas if the reaction rate could be increased. The aim of the present study was to increase the volumetric productivity by using immobilized cells. Kinetic data of ferrous iron oxidation were determined in fixed-bed and fluidized-bed reactor configurations with different support

H. Halfmeier; W. Schäfer-Treffenfeldt; M. Reuss

1993-01-01

239

Bifunctional chelates optimized for molecular MRI.  

PubMed

Important requirements for exogenous dyes or contrast agents in magnetic resonance imaging (MRI) include an effective concentration of paramagnetic or superparamagnetic ions at the target to be imaged. We report the concise synthesis and characterization of several new enantiopure bifunctional derivatives of (?(1)R,?(4)R,?(7)R,?(10)R)-?(1),?(4),?(7),?(10)-tetramethyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTMA) (and their 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) analogues as controls) that can be covalently attached to a contrast agent delivery system using either click or peptide coupling chemistry. Gd complexes of these derivatives can be attached to delivery systems while maintaining optimal water residence time for increased molecular imaging sensitivity. Long chain biotin (LC-biotin) derivatives of the Eu(III) and Gd(III) chelates associated with avidin are used to demonstrate higher efficiencies. Variable-temperature relaxometry, (17)O NMR, and nuclear magnetic resonance dispersion (NMRD) spectroscopy used on the complexes and biotin-avidin adducts measure the influence of water residence time and rotational correlation time on constrained and unconstrained systems. The Gd(III)-DOTMA derivative has a shorter water residence time than the Gd(III)-DOTA derivative. Compared to the constrained Gd(III)-DOTA derivatives, the rotationally constrained Gd(III)-DOTMA derivative has ?40% higher relaxivity at 37 °C, which could increase its sensitivity as an MRI agent as well as reduce the dose of the targeting agent. PMID:24933389

Wiener, Erik C; Abadjian, Marie-Caline; Sengar, Raghvendra; Vander Elst, Luce; Van Niekerk, Christoffel; Grotjahn, Douglas B; Leung, Po Yee; Schulte, Christie; Moore, Curtis E; Rheingold, Arnold L

2014-07-01

240

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

241

Ferrous iron-dependent drug delivery enables controlled and selective release of therapeutic agents in vivo  

PubMed Central

The precise targeting of cytotoxic agents to specific cell types or cellular compartments is of significant interest in medicine, with particular relevance for infectious diseases and cancer. Here, we describe a method to exploit aberrant levels of mobile ferrous iron (FeII) for selective drug delivery in vivo. This approach makes use of a 1,2,4-trioxolane moiety, which serves as an FeII-sensitive “trigger,” making drug release contingent on FeII-promoted trioxolane fragmentation. We demonstrate in vivo validation of this approach with the Plasmodium berghei model of murine malaria. Malaria parasites produce high concentrations of mobile ferrous iron as a consequence of their catabolism of host hemoglobin in the infected erythrocyte. Using activity-based probes, we successfully demonstrate the FeII-dependent and parasite-selective delivery of a potent dipeptidyl aminopeptidase inhibitor. We find that delivery of the compound in its FeII-targeted form leads to more sustained target inhibition with greatly reduced off-target inhibition of mammalian cathepsins. This selective drug delivery translates into improved efficacy and tolerability. These findings demonstrate the utility of a purely chemical means to achieve selective drug targeting in vivo. This approach may find useful application in parasitic infections and more broadly in any disease state characterized by aberrant production of reactive ferrous iron.

Deu, Edgar; Chen, Ingrid T.; Lauterwasser, Erica M. W.; Valderramos, Juan; Li, Hao; Edgington, Laura E.; Renslo, Adam R.; Bogyo, Matthew

2013-01-01

242

Folding process of silk fibroin induced by ferric and ferrous ions  

NASA Astrophysics Data System (ADS)

Bombyx mori silk fiber has useful mechanical properties largely due to a high content of ordered ?-sheet crystallites separated by non-crystalline spacers. Metallic ions present in the silk dope in nature could affect the ?-sheet content. In this work, we used solid-state 13C NMR, EPR and Raman spectroscopy to investigate how the ferric/ferrous ions affect the folding process of the silk fibroin. NMR and Raman results indicate that ferric and ferrous ions have different effects on the secondary structure of silk fibroin. Ferric ions can induce a conformation change from helix to ?-sheet form in silk fibroin when their concentration exceeds a critical value, while ferrous ions cannot. EPR results indicate that the ferric ions bound with silk fibroin have a high-spin state ( S = 5/2) with g-value of g1 = 1.950, g2 = 1.990 and g3 = 1.995, zero-field splitting interaction D of 1.2-2 cm -1, and symmetric character of E/ D = 1/3, resulting in an effective g-value of g' = 4.25. The hydrophilic spacer GTGSSGFGPYVAN(H)GGYSGYEYAWSSESDFGT in the heavy chain of silk fibroin is likely to be involved in the binding of ferric ions, and His, Asn and Tyr residues are considered as the potential binding sites.

Ji, Dan; Deng, Yi-Bin; Zhou, Ping

2009-12-01

243

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

244

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 ‘fragmenting hybrids’ employ a 1,2,4-trioxolane ring system as an iron(II)-sensing ‘trigger’ moiety and a ‘traceless’ 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’s intrinsic bioactivity prior to release in the parasite.

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

2013-01-01

245

Efficient near ultraviolet light induced formation of hydrogen by ferrous hydroxide.  

PubMed

The formation of hydrogen on irradiating ferrous ion in aqueous solution or suspension was studied over a wide range of pH. In addition to the known reaction in acid solution which decreases in yield with increasing pH and required far UV light, there is an efficient reaction occurring between pH 6 and 9 which utilizes near UV light. The latter reaction is an approximately linear function of both the concentration of ferrous ion and the light intensity. The quantum yield of hydrogen from the suspension of Fe(OH)2 at pH 7.2 is very high: > or = 0.3. The quantum yield decreases by a factor of five at 1 mole percent of ferric ions. To explain these observations it is proposed that an intermediate formed on excitation of the Fe(OH)2 polymer is further reduced by a neighboring Fe(+2) to form H2. These results support the work of Braterman et al. (1983) which claimed that the near UV driven photooxidation of ferrous ions could be responsible for formation of the Banded Iron Formations on the early earth. The efficient photoreaction observed in the present work could also serve as a source of active reducing equivalents to reduce CO2 and thus provide a solution to a dilemma in the arguments on the role of reduced carbon in the origin of life. PMID:11540891

Borowska, Z K; Mauzerall, D C

1987-01-01

246

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

NASA Astrophysics Data System (ADS)

The formation of the monochloroiron(II) complex, FeCl +, was studied potentiometrically from 125 to 295°C 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°C. 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°C.

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

1993-04-01

247

Stabilization of the T-state of ferrous human adult haemoglobin by chlorpromazine and trifluoperazine.  

PubMed

In the present study, the effect of the neuroleptics chlorpromazine (2-chloro-N,N-dimethyl-10H-phenothiazine-10-propanamine) and trifluoperazine {10-[3-(4-methylpiperazin-l-yl)-propyl]-2-trifluoromethyl)-10-H- [phenothiazine}-10H-phenothiazine¿ on the EPR-spectroscopic properties of ferrous human adult nitrosylated haemoglobin (HbNO) is reported. Addition of the two drugs to HbNO shifted the conformational equilibrium from the high- to the low-affinity form of the ligated tetramer, as observed for 2,3-D-glycerate bisphosphate, the physiological modulator of haemoglobin action. The effect of chlorpromazine and trifluoperazine on the EPR-spectroscopic properties of HbNO was enhanced by inositol hexakisphosphate. The binding of neuroleptics to ferrous human adult haemoglobin may represent an important undesirable side effect. In fact, oxygen affinity for ferrous human adult haemoglobin decreases on increasing chlorpromazine and trifluoperazine concentration. In addition, red blood cells may act as neuroleptic scavengers. PMID:10512800

Ascenzi, P; Bertollini, A; Coletta, M; Lucacchini, A

1999-10-01

248

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

249

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

250

Car–Parrinello 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–Parrinello 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–O 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–O 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

251

A study of the interface reaction mechanism between molten aluminum and ferrous die materials  

NASA Astrophysics Data System (ADS)

One of the main concerns in the aluminum die casting industry is the problem of die soldering. Die soldering is when aluminum sticks to the surface of the die material, mostly H-13 tool steel, and remains there after ejection of the cast part. In recent times, this defect has posed a major concern because of the notable decrease in productivity and efficiency of casting operations. Due to the high affinity that aluminum has for iron, a vigorous physio-chemical reaction occurs at the die/molten metal interface when aluminum melt comes in direct contact with the ferrous die. This reaction results in the immediate formation of a series of iron-aluminum-silicon intermetallic compounds over the die surface and eventually the cast metal sticks to this intermetallic layer. The aim of this work is to illustrate and quantify the effect of the various die casting parameters, which enhance die soldering, and subsequently alleviate or mitigate the defect. The primary objective was to establish the mechanism of die soldering and other aluminum/ferrous die interface reactions. Two sets of experimental work was carried out---L-9 Taguchi Matrix, L-16 Taguchi matrix. These experiments quantified the effect of various critical casting parameters that influenced the molten aluminum/ferrous die interface reactions. In addition critical diffusion couple experiments between aluminum 380 alloy and H-13 tool steel was carried out to establish the reaction mechanisms between the two. Based on the analysis of the results from the above-mentioned set of experiments, a mechanism for the molten aluminum/ferrous die interface reactions was presented. The interaction is a diffusion controlled process consisting of six stages. Stage I is the erosion of the die material by the aluminum melt to form pits on the surface. In Stage II, binary iron-aluminum intermetallic compounds grow on these pits. Stages II through VI deals with the different stages of development of these intermetallic phase layers due to the diffusion of iron atoms from the die surface into the aluminum melt, and the subsequent soldering of aluminum alloy on these layers of intermetallic compounds, respectively. Subsequently, recommendations were put forth to alleviate the reaction between aluminum and ferrous die.

Shankar, Sumanth

252

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

253

Vaginal contraceptive activity of a chelated vanadocene.  

PubMed

Bis(cyclopentadienyl) complexes of vanadium (IV) or vanadocenes are rapid and potent inhibitors of human sperm motility with potential as a new class of contraceptive agents. This study sought to determine the vaginal contraceptive activity of vanadocene dithiocarbamate (VDDTC), a stable vanadocene (IV)-chelated complex, using the standard rabbit model as well as the domestic pig as a physiologically relevant animal model for contraception. In experiment I, ovulating New Zealand White does in subgroups of eight were artificially inseminated (AI) with semen mixed with VDDTC (0.01-1 mM) or vehicle. In experiment II, ovulating does in subgroups of 18 were AI at 5 and 60 min after intravaginal application of a gel with and without 0.1% VDDTC or 2% nonoxynol-9 (N-9) (Gynol II, Ortho Pharmaceutical, Raritan, NJ), and allowed to complete term pregnancy. In experiment III, seven sexually mature Duroc gilts in standing estrus were AI with and without intravaginal application of 0.1% VDDTC gel microemulsion. Exposure of rabbit semen to VDDTC at the time of artificial insemination resulted in a dose-dependent reduction in fertility. Exposure of semen to 1 mM VDDTC led to complete inhibition of fertility as assessed by the number of embryos (control 49/94 vs. VDDTC-treated 0/117, p<.0001) or the percent embryos (52% vs. 0%, respectively) based on number of embryos to corpora lutea. Intravaginal administration of 0.1% VDDTC gel microemulsion or Gynol II prior to artificial insemination significantly inhibited term pregnancy rates (88% and 62% inhibition, respectively) when compared to control gel alone. Vanadocene dithiocarbamate gel microemulsion provided 80% inhibition of fertility even when insemination was delayed until 60 min after intravaginal application of VDDTC gel microemulsion. Rabbits that delivered litters despite intravaginal exposure of semen to VDDTC via gel microemulsion had healthy offsprings with no apparent perinatal repercussions. In domestic pigs, intravaginal applications of 0.1% VDDTC gel microemulsion prior to artificial insemination led to complete inhibition of fertility as assessed by the number of embryos (control 29/52 vs. VDDTC-treated 0/44, p<.0001) or the percent embryos (56% vs. 0%, respectively) based on the number of embryos to corpora lutea. These results suggest that VDDTC is a potent contraceptive agent in vivo. Intravaginal use of VDDTC via a gel microemulsion has clinical potential as a safe alternative to currently used detergent-type contraceptives. PMID:16022855

D'Cruz, Osmond J; Uckun, Fatih M

2005-08-01

254

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) [Berkeley, CA; Xu, Jide (Berkeley, CA) [Berkeley, CA

1997-01-01

255

Iron chelation in the biological activity of curcumin.  

PubMed

Curcumin is among the more successful chemopreventive compounds investigated in recent years, and is currently in human trials to prevent cancer. The mechanism of action of curcumin is complex and likely multifactorial. We have made the unexpected observation that curcumin strikingly modulates proteins of iron metabolism in cells and in tissues, suggesting that curcumin has properties of an iron chelator. Curcumin increased mRNA levels of ferritin and GSTalpha in cultured liver cells. Unexpectedly, however, although levels of GSTalpha protein increased in parallel with mRNA levels in response to curcumin, levels of ferritin protein declined. Since iron chelators repress ferritin translation, we considered that curcumin may act as an iron chelator. To test this hypothesis, we measured the effect of curcumin on transferrin receptor 1, a protein stabilized under conditions of iron limitation, as well as the ability of curcumin to activate iron regulatory proteins (IRPs). Both transferrin receptor 1 and activated IRP, indicators of iron depletion, increased in response to curcumin. Consistent with the hypothesis that curcumin acts as an iron chelator, mice that were fed diets supplemented with curcumin exhibited a decline in levels of ferritin protein in the liver. These results suggest that iron chelation may be an additional mode of action of curcumin. PMID:16545682

Jiao, Yan; Wilkinson, John; Christine Pietsch, E; Buss, Joan L; Wang, Wei; Planalp, Roy; Torti, Frank M; Torti, Suzy V

2006-04-01

256

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

257

Chemical decontamination of process equipment using recyclable chelating agents  

SciTech Connect

The Babcock and Wilcox Company is performing research and development in the application of chelating chemicals to dissolve uranium compounds and other actinide species from the surfaces of DOE process equipment. A chelating system specific for the removal of uranium and other actinides will be applied to the component selected for full-scale demonstration of the process. After application of the chelating solvent for an appropriate time period, the spent solvent will be removed to a waste processing facility, and the dissolved radioactive contaminants will be precipitated out of the solution. The regenerated chelating solvent will then be available for reuse in the cleaning system, thereby minimizing the amount of secondary waste generated by the process. Phase 1 activity has begun with bench-scale tests in the laboratory, to screen and optimize candidate solvent systems, and will proceed to development of a chemical cleaning process that will be tested in a pilot facility on an actual piece of contaminated equipment. The potential for application of the chelating agent as a foam rather than a liquid will also be investigated. The advantage of foaming application is a reduction of solvent volume requiring eventual treatment. The second phase of this program will be a full-scale demonstration of the developed technology on contaminated process equipment at a DOE site.

Palmer, P.A.

1994-10-01

258

Studies on the chelation of aluminum for neurobiological application.  

PubMed

The formation and strength of chelation of A1(III) with salicylic acid (SA), citric acid (CIT), ethylenediaminetetraacetic acid (EDTA), ethylenediamine-di-(o-hydroxyphenylacetic acid) (EDDHA), N,N'-di-(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED), and some mixed ligand systems consisting of the above ligands were examined at an ionic strength of 0.12 M NaCl and 25.0 +/- 0.1 degrees C. All the ligands under consideration form strong chelates with A1(III). The order of the stabilities (log KML) of their A1(III) chelates are SA (13.7) less than EDTA (15.3) less than CIT (18.0) less than EDDHA (24.5) approximately equal to HBED (24.8). An equilibrium analysis of the A1(III)-SA (1:1), A1(III)-CIT (1:1) and A1(III)-SA-CIT (1:1:1) systems indicated the occurrence of hydrolysis and polymerization reactions in each one of them. The A1(III)-EDTA (1:1) chelate was found to undergo hydrolysis even at pH 5. However, EDDHA and HBED each formed a very stable mononuclear chelate with A1(III) and did not show hydrolytic or polymerization tendencies. PMID:7276932

Rajan, K S; Mainer, S; Rajan, N L; Davis, J M

1981-07-01

259

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

PubMed Central

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 hybridization, as well as for hybridization analysis of denaturing gradient gel electrophoresis (DGGE) patterns. However, neither enumeration by in situ hybridization nor detection by the DGGE-hybridization approach was feasible with sediment samples. Therefore, the DGGE-hybridization approach was combined with microbiological methods. Freshwater sediment samples from different European locations were used for enrichment cultures and most-probable-number (MPN) determinations. Bacteria with the ability to oxidize ferrous iron under nitrate-reducing conditions were detected in all of the sediment samples investigated. At least one of the previously described types of bacteria was detected in each enrichment culture. MPN studies showed that sediments contained from 1 × 105 to 5 × 108 ferrous iron-oxidizing, nitrate-reducing bacteria per g (dry weight) of sediment, which accounted for at most 0.8% of the nitrate-reducing bacteria growing with acetate. Type BrG1, BrG2, and BrG3 bacteria accounted for an even smaller fraction (0.2% or less) of the ferrous iron-oxidizing, nitrate-reducing community. The DGGE patterns of MPN cultures suggested that more organisms than those isolated thus far are able to oxidize ferrous iron with nitrate. A comparison showed that among the anoxygenic phototrophic bacteria, organisms that have the ability to oxidize ferrous iron also account for only a minor fraction of the population.

Straub, Kristina L.; Buchholz-Cleven, Berit E. E.

1998-01-01

260

Iron chelation inhibits the development of pulmonary vascular remodeling  

PubMed Central

Reactive oxygen species (ROS) have been implicated in the pathogenesis of pulmonary hypertension. Since iron is an important regulator of ROS biology, the present study examined the effect of iron chelation on the development of pulmonary vascular remodeling. The administration of an iron chelator, deferoxamine, to rats prevented chronic hypoxia-induced pulmonary hypertension and pulmonary vascular remodeling. Various iron chelators inhibited growth of cultured pulmonary artery smooth muscle cells. Protein carbonylation, an important iron-dependent biological event, was promoted in association with pulmonary vascular remodeling and cell growth. A proteomic approach identified that Rho GDP-dissociation inhibitor (a negative regulator of RhoA) is carbonylated. In human plasma, the protein carbonyl content was significantly higher in patients with idiopathic pulmonary arterial hypertension than in healthy controls. These results suggest that iron plays an important role in the ROS-dependent mechanism underlying the development of pulmonary hypertension.

Wong, Chi-Ming; Preston, Ioana R.; Hill, Nicholas S.; Suzuki, Yuichiro J.

2012-01-01

261

Heavy metal displacement in chelate-irrigated soil during phytoremediation  

NASA Astrophysics Data System (ADS)

Heavy metals in wastewater sewage sludge (biosolids), applied to land, contaminate soils. Phytoremediation, the use of plants to clean up toxic heavy metals, might remove them. Chelating agents are added to soil to solubilize the metals for enhanced phytoextraction. Yet no studies follow the displacement and leaching of heavy metals in soil with and without roots following solubilization with chelates. The objective of this work was to determine the mobility of heavy metals in biosolids applied to the surface of soil columns (76 cm long; 17 cm diam.) with or without plants (barley; Hordeum vulgare L.). Three weeks after barley was planted, all columns were irrigated with the disodium salt of the chelating agent, EDTA (ethylenediamine tetraacetic acid) (0.5 g/kg soil). Drainage water, soil, and plants were analyzed for heavy metals (Cd, Cu, Fe, Mn, Ni, Pb, Zn). Total concentrations of the heavy metals in all columns at the end of the experiment generally were lower in the top 30 cm of soil with EDTA than without EDTA. The chelate increased concentrations of heavy metals in shoots. With or without plants, the EDTA mobilized Cd, Fe, Mn, Ni, Pb, and Zn, which leached to drainage water. Drainage water from columns without EDTA had concentrations of these heavy metals below detection limits. Only Cu did not leach in the presence of EDTA. Even though roots retarded the movement of Cd, Fe, Mn, Ni, Pb, and Zn through the EDTA-treated soil from 1 d (Cd) to 5 d (Fe), the drainage water from columns with EDTA had concentrations of Cd, Fe, Mn, and Pb that exceeded drinking water standards by 1.3, 500, 620, and 8.6 times, respectively. Because the chelate rendered Cd, Fe, Mn, Ni, Pb, and Zn mobile, it is suggested that the theory for leaching of soluble salts, put forward by Nielsen and associates in 1965, could be applied to control movement of the heavy metals for maximum uptake during chelate-assisted phytoremediation.

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

2003-03-01

262

Interaction of chelating agents with cadmium in mice and rats.  

PubMed

The influence of several chelating agents (CaDTPA, ZnDTPA, CaEDTA, ZnEDTA, DMSA, D-penicillamine and DMPS, DMP and DDC) on the acute toxicity of CdCl2 and on the whole body retention and tissue distribution of cadmium after the IV application of 115mCdCl2 was compared in mice. The chelating agents were applied immediately after the application of cadmium. CaDTPA, ZnDTPA and DMSA appeared to be the most effective antidotes. However, DMSA increased the amount of cadmium retained in kidneys. The treatment of cadmium-poisoned mice with the combination of DMSA (IP) and ZnDTPA (SC) (all the compounds were injected in equimolar dose) decreased the toxicity of cadmium more than treatment with one chelating agents (given in a 2:1 dose). However, by studying the effect of these chelating agents and their combination of the retention and distribution of Cd in mice, it was demonstrated that the combined application of the antidotes showed little or no improvement over the results obtained with the most effective of the individual components. In the urine of rats injected with CdCl2 and treated with the chelating agents (CaDTPA, ZnDTPA, DMSA), the presence of cadmium complexes was demonstrated. The formation of mixed ligand chelates in vivo was not proved. Experiments in mice given a single injection of 115mCd-labeled Cd complexes of DMPS, DMSA and DTPA showed a high retention of cadmium in the organisms after the IV application of CdDMPS and CdDMSA complexes. PMID:6734561

Eybl, V; Sýkora, J; Koutenský, J; Caisová, D; Schwartz, A; Mertl, F

1984-03-01

263

Iron chelators reduce chromosomal breaks in ataxia-telangiectasia cells.  

PubMed

Ataxia-telangiectasia (A-T) is characterized by ataxia, genomic instability, and increased cancer incidence. Previously, iron chelator concentrations which suppressed normal cell colony formation increased A-T cell colony formation. Similarly, iron chelators preferentially increased A-T cell colony formation following peroxide exposure compared to normal cells. Last, A-T cells exhibited increased short-term sensitivity to labile iron exposure compared to normal cells, an event corrected by recombinant ATM (rATM) expression. Since chromosomal damage is important in A-T pathology and iron chelators exert beneficial effects on A-T cells, we hypothesized that iron chelators would reduce A-T cell chromosomal breaks. We treated A-T, normal, and A-T cells expressing rATM with labile iron, iron chelators, antioxidants, and t-butyl hydroperoxide, and examined chromosomal breaks and ATM activation. Additionally, the effect of ATM-deficiency on transferrin receptor (TfR) expression and TfR activity blockage in A-T and syngeneic A-T cells expressing rATM was examined. We report that (1) iron chelators and iron-free media reduce spontaneous and t-butyl hydroperoxide-induced chromosomal breaks in A-T, but not normal, or A-T cells expressing rATM; (2) labile iron exposure induces A-T cell chromosomal breaks, an event lessened with rATM expression; (3) desferal, labile iron, and copper activate ATM; (4) A-T cell TfR expression is lowered with rATM expression and (5) blocking TfR activity with anti-TfR antibodies increases A-T cell colony formation, while lowering chromosomal breaks. ATM therefore functions in iron responses and the maintenance of genomic stability following labile iron exposure. PMID:16959548

Shackelford, Rodney E; Fu, Yumei; Manuszak, Ryan P; Brooks, Torrie C; Sequeira, Adrian P; Wang, Suming; Lowery-Nordberg, Mary; Chen, Anping

2006-11-01

264

Combinational chelation therapy abrogates lead-induced neurodegeneration in rats  

SciTech Connect

Lead, a ubiquitous and potent neurotoxicant causes oxidative stress which leads to numerous neurobehavioral and physiological alterations. The ability of lead to bind sulfhydryl groups or compete with calcium could be one of the reasons for its debilitating effects. In the present study, we addressed: i) if chelation therapy could circumvent the altered oxidative stress and prevent neuronal apoptosis in chronic lead-intoxicated rats, ii) whether chelation therapy could reverse biochemical and behavioral changes, and iii) if mono or combinational therapy with captopril (an antioxidant) and thiol chelating agents (DMSA/MiADMSA) is more effective than individual thiol chelator in lead-exposed rats. Results indicated that lead caused a significant increase in reactive oxygen species, nitric oxide, and intracellular free calcium levels along with altered behavioral abnormalities in locomotor activity, exploratory behavior, learning, and memory that were supported by changes in neurotransmitter levels. A fall in membrane potential, release of cytochrome c, and DNA damage indicated mitochondrial-dependent apoptosis. Most of these alterations showed significant recovery following combined therapy with captopril with MiADMSA and to a smaller extend with captopril + DMSA over monotherapy with these chelators. It could be concluded from our present results that co-administration of a potent antioxidant (like captopril) might be a better treatment protocol than monotherapy to counter lead-induced oxidative stress. The major highlight of the work is an interesting experimental evidence of the efficacy of combinational therapy using an antioxidant with a thiol chelator in reversing neurological dystrophy caused due to chronic lead exposure in rats.

Pachauri, Vidhu; Saxena, Geetu; Mehta, Ashish; Mishra, Deepshikha [Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Jhansi Road, Gwalior-474 001 (India); Flora, Swaran J.S. [Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Jhansi Road, Gwalior-474 001 (India)], E-mail: sjsflora@hotmail.com

2009-10-15

265

A macrocyclic chelator with unprecedented th(4+) affinity.  

PubMed

A novel macrocyclic octadentate ligand incorporating terephthalamide binding units has been synthesized and evaluated for the chelation of Th(4+). The thorium complex was structurally characterized by X-ray diffraction and in solution with kinetic studies and spectrophotometric titrations. Dye displacement kinetic studies show that the ligand is a much more rapid chelator of Th(4+) than prevailing ligands (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid and diethylenetriaminepentaacetic acid). Furthermore, the resulting complex was found to have a remarkably high thermodynamic stability, with a formation constant of 10(54). These data support potential radiotherapeutic applications. PMID:24870296

Pham, Tiffany A; Xu, Jide; Raymond, Kenneth N

2014-06-25

266

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?³? 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 Mössbauer 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

267

Protonation of Ferrous Dinitrogen Complexes Containing a Diphosphine Ligand with a Pendant Amine  

SciTech Connect

The addition of protons to pendant amine containing ferrous dinitrogen complexes, of the type [FeX(N2)(PEtNMePEt)(dmpm)]+ (X = H, Cl, or Br; PEtNMePEt = Et2PCH2N(Me)CH2PEt2 and dmpm = Me2PCH2PMe2), was found to protonate at the pendant amine as opposed to the dinitrogen ligand. This protonation increased the ?N2 of the complex by about 25 cm-1, shifting the Fe(II/I) couple 330 mV to a more positive potential. A similar shift was observed in the case of [FeX(CO)(PEtNMePEt)(dmpm)]+ (X = H, Cl, or Br). Computational analysis verified these experimental results and showed the 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 was found to increase the basicity of the bound N2 ligand, coordinated N2 is not sufficiently basic to be protonated. In the case of ferrous dinitrogen complexes containing a basic pendant methylamine, the amine site was determined to be the most basic site by 30 pKa units compared to protonation at the N2 ligand. To increase the basicity of the N2 ligand in order to promote proton transfer from the pendant amine to the N2 ligand, chemical reduction of these ferrous dinitrogen complexes was performed and found to result in oxidative addition of the methylene C-H bond of the PEtNMePEt ligand to Fe, preventing isolation of a reduced Fe(0) N2 complex. This work was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy Office of Science, Office of Basic Energy Sciences.

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

2013-04-01

268

Ordered complexes of cytochrome c fragments. Kinetics of formation of the reduced (ferrous) forms.  

PubMed

The kinetics of formation of noncovalently bound ferrous complexes derived from fragments of horse heart cytochrome c have been investigated. When the reactions are initiated by combining ferrous heme fragments with an appropriate apofragment, in the presence of 50 mM imidazole, second order rate processes are observed with rate constants essentially the same as those reported with ferric heme fragments (Parr, G. R., and Taniuchi, H. (1979) J. Biol. Chem. 254, 4836-4842). An additional, probably consecutive, kinetic process is also demonstrated. If imidazole is not present in the reaction buffer, the kinetic profiles are dramatically altered. While this is partially due to aggregation (dimerization) of the ferrous heme fragments, it can nevertheless be demonstrated that the complementation reactions with apofragments are much faster than those observed with the corresponding ferric heme fragments (in the absence of imidazole). These results reflect the effect of the oxidation state of the heme iron on the folding mechanism and, thus, the manifold nature of protein folding pathways. The rate of reduction of productive ferric complexes by sodium ascorbate was investigated and biphasic reactions were found in all cases. The data indicate an equilibrium between two forms of the ferric complexes. The results of an experiment in which the complementation of ferric (1-25)H and (23-104) was carried out in the presence of sodium ascorbate indicate that the intermediate complex (Parr, G. R., and Taniuchi, H. (1980) J. Biol. Chem. 255, 8914-8918) is not reducible by ascorbate. Thus, the increase in oxidation-reduction potential occurring on formation of the productive complex from the unbound heme fragment occurs at a late stage of the overall reaction, possibly coinciding with ligation of methionine 80 to the heme iron. PMID:6256341

Parr, G R; Taniuchi, H

1981-01-10

269

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

270

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

271

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

272

Friction and surface chemistry of some ferrous-base metallic glasses  

NASA Technical Reports Server (NTRS)

The friction properties of some ferrous-base metallic glasses were measured both in argon and in vacuum to a temperature of 350 C. The alloy surfaces were also analyzed with X-ray photoelectron spectroscopy to identify the compounds and elements present on the surface. The results of the investigation indicate that even when the surfaces of the amorphous alloys, or metallic glasses, are atomically clean, bulk contaminants such as boric oxide and silicon dioxide diffuse to the surfaces. Friction measurements in both argon and vacuum indicate that the alloys exhibit higher coefficients of friction in the crystalline state than they do in the amorphous state.

Miyoshi, K.; Buckley, D. H.

1982-01-01

273

Determination of hydroperoxides in aqueous solutions containing surfactants by the ferrous oxidation-xylenol orange method.  

PubMed

Some surfactants widely used as additives in food, pharmaceuticals, and cosmetic formulations are susceptible to peroxidation resulting in accumulation of hydroperoxides (HP). Our investigation was aimed to study the possible influence of different surfactants on the proportionality and reproducibility of the ferrous oxidation-xylenol orange method developed originally for the determination of hydroperoxides. We also attempted to apply this method to determine hydroperoxides produced radiolytically in surfactant molecules. From our preliminary studies we conclude that the method can be applied for determination of hydroperoxides in systems containing non-ionic or anionic surfactants provided careful calibration is performed for each surfactant. PMID:19738936

Meisner, Piotr; Gebicki, Jerzy L

2009-01-01

274

Characterisation of the ferrous-xylenol orange-gelatin (FXG) gel dosimeter  

NASA Astrophysics Data System (ADS)

Recent studies have used the ferrous-xylenol orange-gelatin (FXG) gel dosimeter for 3D radiation field mapping using the optical computed tomography technique. However the characterisation of the dosimetry performance of the FXG gel has not been detailed, such as the variation in dose-response of the FXG gel with changes in preparation techniques, constituent concentrations, pre-irradiation storage time, and concentrations of additives such as oxygen and saccharides. In this paper these issues are addressed with the aim of developing a standard FXG gel for future use in radiation dosimetry applications.

Healy, B.; Brindha, S.; Zahmatkesh, M.; Baldock, C.

2004-01-01

275

Reproducibilty test of ferrous xylenol orange gel dose response with optical cone beam CT scanning  

NASA Astrophysics Data System (ADS)

Our previous studies of ferrous xylenol orange gelatin gel have revealed a spatial dependence to the dose response of samples contained in 10 cm diameter cylinders. Dose response is defined as change in optical attenuation coefficient divided by the dose (units cm-1 Gy-1). This set of experiments was conducted to determine the reproducibility of our preparation, irradiation and full 3D optical cone beam CT scanning. The data provided an internal check of a larger storage time-dose response dependence study.

Jordan, K.; Battista, J.

2004-01-01

276

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

277

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

278

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

279

Ferrous analysis  

SciTech Connect

This review is the seventh in the series compiled by using the Dialog on-line CA Search facilities at the Information Resource Center of USS Technical Center covering the period from Oct. 1984 to Nov. 1, 1986. The quest for better surface properties, through the application of various electrochemical and other coating techniques, seems to have increased and reinforces the notion that only through the value added to a steel by proper finishing steps can a major supplier hope to compete profitably. The detection, determination, and control of microalloying constituents has also been generating a lot of interest as evidenced by the number of publications devoted to this subject in the last few years. Several recent review articles amplify on the recent trends in the application of modern analytical technology to steelmaking. Another review has been devoted to the determination of trace elements and the simultaneous determination of elements in metals by mass spectrometry, atomic absorption spectrometry, and multielement emission spectrometry. Problems associated with the analysis of electroplating wastewaters have been reviewed in a recent publication that has described the use of various spectrophotometric methods for this purpose. The collection and treatment of analytical data in the modern steel making environment have been extensively reviewed emphasis on the interaction of the providers and users of the analytical data, its quality, and the cost of its collection. Raw material treatment and beneficiation was the dominant theme.

Straub, W.A.

1987-06-15

280

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

281

Chelation And Extraction Of Metals For GC-MS Analysis  

NASA Technical Reports Server (NTRS)

Chelation followed by supercritical-fluid extraction enables mass-spectrometric analysis. When fully developed, method implemented in field-portable apparatus for detection and quantification of metals in various matrices without need for elaborate preparation of samples. Used to analyze soil samples for toxic metals.

Sinha, Mahadeva P.

1995-01-01

282

Purification of Carboxypeptidase B by Zinc Chelate Chromatography  

Microsoft Academic Search

A method is described to purify pancreatic carboxypeptidases B (CPB), removing contaminating endoproteinases that interfere with use of CPB for carboxy-terminal analysis or modification of proteins. The separation uses zinc chelate chromatography and is based on the property that CPB has higher affinity for immobilized zinc ions than do serine proteinases such as trypsin and chymotrypsin. which are abundant endoproteolytic

G. L. Hortin; B. L. Gibson

1989-01-01

283

Chelation-controlled regioselective alkylation of pyrimidine 2'-deoxynucleosides.  

PubMed

Protection-deprotection steps, which are usually needed for regioselective alkylation of pyrimidine deoxynucleosides, can be avoided by choosing the appropriate solvent. The combined effects of low dielectric constant and possible sodium chelation by pyrimidine nucleosides may account for the unexpected regioselectivity observed in THF. PMID:19932891

Lucas, R; Teste, K; Zerrouki, R; Champavier, Y; Guilloton, M

2010-01-26

284

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

285

Role of chelation during pregnancy in the lead poisoned patient.  

PubMed

Cultural and environmental factors can cause lead poisoning in the pregnant patient. The data regarding the reproductive risks associated with chelation during human pregnancy are sparse. Assessment of the exposure setting, including anticipatory counseling for each pregnant woman, would help assure the ideal outcome of no added lead intake. PMID:24243290

Brown, Mary Jean

2013-12-01

286

Amine-chelated aryllithium reagents--structure and dynamics.  

PubMed

Multinuclear NMR studies of five-membered-ring amine chelated aryllithium reagents 2-lithio-N,N-dimethylbenzylamine (1), the diethylamine and diisopropylamino analogues (2, 3), and the o-methoxy analogue (4), isotopically enriched in (6)Li and (15)N, have provided a detailed picture of the solution structures in ethereal solvents (usually in mixtures of THF and dimethyl ether, ether, and 2,5-dimethyltetrahydrofuran). The effect of cosolvents such as TMEDA, PMDTA, and HMPA has also been determined. All compounds are strongly chelated, and the chelation is not disrupted by these cosolvents. Reagents 1, 2, and 3 are dimeric in solvents containing a large fraction of THF. Below -120 degrees C, three chelation isomers of the dimers are detectable by NMR spectroscopy: one (A) with both nitrogens coordinated to one lithium of the dimer, and two (B and C) in which each lithium bears one chelating group. Dynamic NMR studies have provided rates and activation energies for the interconversion of the 1-A, 1-B, and 1-C isomers. They interconvert either by simple ring rotation, which interconverts B and C, or by amine decoordination (probably associative, DeltaG(++)(-93) = 8.5 kcal/mol), which can interconvert all of the isomers. The dimers of 1 are thermodynamically more stable than those of model systems such as phenyllithium, o-tolyllithium, or 2-isoamylphenyllithium (5, DeltaDeltaG > or = 3.3 kcal/mol). They are not detectably deaggregated by TMEDA or PMDTA, although HMPA causes partial deaggregation. The dimers are also more robust kinetically with rates of interaggregate exchange, measured by DNMR line shape analysis of the C-Li signal, orders of magnitude smaller than those of models (DeltaDeltaG(++) > or = 4.4 kcal/mol). Similarly, the mixed dimer of 1 and phenyllithium, 13, is kinetically more stable than the phenyllithium dimer by >2.2 kcal/mol. X-ray crystal structures of the TMEDA solvate of 1-A and the THF solvate of 3-B showed them to be dimeric and chelated in the solid state as well. Compound 4, which has a methoxy group ortho to the C-Li group, differs from the others in being only partially dimeric in THF, presumably for steric reasons. This compound is fully deaggregated by 1 equiv of HMPA. Excess HMPA leads to the formation of ca. 15% of a triple ion (4-T) in which both nitrogens appear to be chelated to the central lithium. PMID:11506563

Reich, H J; Goldenberg, W S; Gudmundsson, B O; Sanders, A W; Kulicke, K J; Simon, K; Guzei, I A

2001-08-22

287

Enhancement of growth and ferrous iron oxidation rates of T. ferrooxidans by electrochemical reduction of ferric iron  

SciTech Connect

Thiobacillus ferrooxidans, the bacterium most widely used in bioleaching or microbial desulfurization of coal, was grown in an electrolytic bioreactor containing a synthetic, ferrous sulfate medium. Passage of current through the medium reduced the bacterially generated ferric iron to the ferrous iron substrate. When used in conjunction with an inoculum that had been adapted to the electrolytic growth conditions, this technique increased the protein (cell) concentration by 3.7 times, increased the protein (cell) production rate by 6.5 times, increased the yield coefficient (cellular efficiency) by 8.0 times, and increased the ferrous iron oxidation rate by 1.5 times at 29/sup 0/C, compared with conventional cultivation techniques. A Monod-type equation with accepted values for the maximum specific growth rate could not account for the increased growth rate under electrolytic conditions.

Yunker, S.B.; Radovich, J.M.

1986-01-01

288

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

289

Molecular mechanisms of in vivo metal chelation: implications for clinical treatment of metal intoxications.  

PubMed Central

Successful in vivo chelation treatment of metal intoxication requires that a significant fraction of the administered chelator in fact chelate the toxic metal. This depends on metal, chelator, and organism-related factors (e.g., ionic diameter, ring size and deformability, hardness/softness of electron donors and acceptors, route of administration, bioavailability, metabolism, organ and intra/extracellular compartmentalization, and excretion). In vivo chelation is not necessarily an equilibrium reaction, determined by the standard stability constant, because rate effects and ligand exchange reactions considerably influence complex formation. Hydrophilic chelators most effectively promote renal metal excretion, but they complex intracellular metal deposits inefficiently. Lipophilic chelators can decrease intracellular stores but may redistribute toxic metals to, for example, the brain. In chronic metal-induced disease, where life-long chelation may be necessary, possible toxicity or side effects of the administered chelator may be limiting. The metal selectivity of chelators is important because of the risk of depletion of the patient's stores of essential metals. Dimercaptosuccinic acid and dimercaptopropionic sulfonate have gained more general acceptance among clinicians, undoubtedly improving the management of many human metal intoxications, including lead, arsenic, and mercury compounds. Still, development of new safer chelators suited for long-term oral administration for chelation of metal deposits (mainly iron), is an important research challenge for the future.

Andersen, Ole; Aaseth, Jan

2002-01-01

290

Field-Portable Immunoassay Instruments and Reagents to Measure Chelators and Mobile Forms of Uranium  

SciTech Connect

A collaborator in the Chemistry Department at Tulane University, Dr. Harry Ensley, has synthesized a new bifunctional chelator with specificity for ionic mercury (Hg2+) and methymercury (MeHg+). These chelators are based upon phenantholine derivative containing sulfhydryl functional groups. Experiments are underway to generate protein conjugates of this chelator to use in immunizations and screening.

Blake, Diane A.

2005-06-01

291

Performance Evaluation of Chelated Minerals in Idaho Open-formula Diets  

Microsoft Academic Search

Chelated minerals added to cutthroat trout (Salmo clarki) diets in 1964 and 1965 appeared to be beneficial to trout reared in extremely soft water and of no benefit in moderately hard water.Limited tests with chelated minerals added to rainbow trout (Salmo gairdneri) diets during 1967 indicated a possible beneficial effect.During the 1968 feeding trials, chelated minerals were tested in two

Paul Cuplin

1969-01-01

292

Mössbauer spectroscopic study of iron-chelate trammels  

NASA Astrophysics Data System (ADS)

Any kind of waste effluent in the Indian context and other countries contains a lot of iron in any ore. During mining, milling, extraction and purification process iron acts as contaminant towards other metal's purity. It is essential to remove iron to the maximum extent. In this case, an "IN-HOUSE" resin polyacrylamidehydroxamic acid (PHOA) has been designed and developed which is highly hydrophilic three dimensionally cross-linked. It has an excellent iron binding capacity with almost no leaching. Interaction of resin with ammonium ferrous sulphate and red-mod (Fe2O3) is studied using Mössbauer spectroscopy.

Pal, Sangita; Meena, S. S.; Ningthoujam, R. S.; Goswami, D.

2014-04-01

293

The role of organic ligands in ferrous-induced photochemical degradation of 2,4-dichlorophenoxyacetic acid.  

PubMed

Recent studies have shown that hydrogen peroxide is generated in a ferrioxalate-induced photoreductive reaction, but information about the effect of organic ligands on the photochemical behaviour of ferrous species is limited. The degradation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) by a ferrous-catalyzed oxidation in the presence of various ligands such as formate, citrate, malelate, oxalate, and ethylenediaminetetra-acetic acid (EDTA) was studied. The experiments were conducted under either dark or irradiated (350n m) conditions. Forty-two percent and 34% of 2,4-D were removed by the Fe(2+)/oxalate/UV and Fe(2+)/citrate/UV processes, respectively, after 30 min of reaction and oxidative intermediates were obtained in both cases. The presence of hydroxylated intermediates suggests that 2,4-D may be attacked by hydroxyl radicals, which are the products of the photo-Fenton-like reaction. As such, hydrogen peroxide was produced by the photolysis of ferrous oxalate or ferrous citrate, referred to hereafter as photogenerated H(2)O(2). As expected, the total removal percentage of 2,4-D jumped to 97% when 1mM of hydrogen peroxide (so-called spiked H(2)O(2)) was externally added to the reaction vessel to initiate the Fe(2+)/oxalate/UV process. Therefore, the treatment of 2,4-D by the Fe(2+)/oxalate/H(2)O(2)/UV system can be operated in two steps: the photolysis of ferrous oxalate first, followed by adding the spiked H(2)O(2) sometime after the commencement of the reaction. A two-phase model has been developed to describe this tandem ferrous-catalyzed photooxidation, which would help to achieve the mineralization of 2,4-D. PMID:17239922

Kwan, C Y; Chu, W

2007-04-01

294

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 °C 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

2013-12-01

295

Prospects for Ukrainian ferrous metals in the post-soviet period  

USGS Publications Warehouse

Two specialists on the mineral industries of the countries of the former USSR survey current problems confronting producers of ferrous metals in Ukraine and future prospects for domestic production and exports. A series of observations documenting the importance of ferrous metals production to Ukraine's economy is followed by sections describing investment plans and needs in the sector, and the role played by Ukraine within the iron and steel industry of the Soviet Union. The focus then turns to assessment of the current regional and global competitive position of Ukrainian producers for each of the major commodities of the sector-iron ore, manganese ore, ferroalloys, steel, and the products of the machine manufacturing and metal working industries. In conclusion, the paper discusses a potential regional industrial integration strategy analogous to that employed in the United States' Great Lakes/Midwest region, which possesses similar types of iron ore deposits and similar transport cost advantages and metallurgical and manufacturing industries. Journal of Economic Literature, Classification Numbers: F14, L61, L72. 1 table, 26 references.

Levine, R. M.; Bond, A. R.

1998-01-01

296

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 Andrés, Juan Manuel

2012-12-01

297

Low frequency spectral density of ferrous heme: perturbations induced by axial ligation and protein insertion.  

PubMed

Femtosecond coherence spectroscopy is used to probe low frequency (20-400 cm(-1)) modes of the ferrous heme group in solution, with and without 2-methyl imidazole (2MeIm) as an axial ligand. The results are compared to heme proteins (CPO, P450(cam), HRP, Mb) where insertion of the heme into the protein results in redistribution of the low frequency spectral density and in (approximately 60%) longer damping times for the coherent signals. The major effect of imidazole ligation to the ferrous heme is the "softening" of the low frequency force constants by a factor of approximately 0.6 +/- 0.1. The functional consequences of imidazole ligation are assessed and it is found that the enthalpic CO rebinding barrier is increased significantly when imidazole is bound. The force constant softening analysis, combined with the kinetics results, indicates that the iron is displaced by only approximately 0.2 A from the heme plane in the absence of the imidazole ligand, whereas it is displaced by approximately 0.4 A when imidazole (histidine) is present. This suggests that binding of imidazole (histidine) as an axial ligand, and the concomitant softening of the force constants, leads to an anharmonic distortion of the heme group that has significant functional consequences. PMID:17766351

Gruia, Flaviu; Ye, Xiong; Ionascu, Dan; Kubo, Minoru; Champion, Paul M

2007-12-15

298

Low Frequency Spectral Density of Ferrous Heme: Perturbations Induced by Axial Ligation and Protein Insertion  

PubMed Central

Femtosecond coherence spectroscopy is used to probe low frequency (20–400 cm?1) modes of the ferrous heme group in solution, with and without 2-methyl imidazole (2MeIm) as an axial ligand. The results are compared to heme proteins (CPO, P450cam, HRP, Mb) where insertion of the heme into the protein results in redistribution of the low frequency spectral density and in (?60%) longer damping times for the coherent signals. The major effect of imidazole ligation to the ferrous heme is the “softening” of the low frequency force constants by a factor of ?0.6 ± 0.1. The functional consequences of imidazole ligation are assessed and it is found that the enthalpic CO rebinding barrier is increased significantly when imidazole is bound. The force constant softening analysis, combined with the kinetics results, indicates that the iron is displaced by only ?0.2 Å from the heme plane in the absence of the imidazole ligand, whereas it is displaced by ?0.4 Å when imidazole (histidine) is present. This suggests that binding of imidazole (histidine) as an axial ligand, and the concomitant softening of the force constants, leads to an anharmonic distortion of the heme group that has significant functional consequences.

Gruia, Flaviu; Ye, Xiong; Ionascu, Dan; Kubo, Minoru; Champion, Paul M.

2007-01-01

299

Efficient near ultraviolet light induced formation of hydrogen by ferrous hydroxide. [in primitive earth  

NASA Technical Reports Server (NTRS)

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.

1987-01-01

300

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

301

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

NASA Technical Reports Server (NTRS)

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 required 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. It is shown 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. It has been 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.

1990-01-01

302

Effect of ferrous and ferric ions on copigmentation in model solutions  

NASA Astrophysics Data System (ADS)

The thermodynamics of the molecular association process between malvidin-3- O-glucoside and ellagic acid (so-called "copigmentation") was studied in model wine solutions in the presence and absence, respectively, of ferrous and ferric ions. The Gibbs free energy, enthalpy, and entropy values of the complexation process were determined by means of a spectrofluorometric method. A combination of the Job's method with the van't Hoff theory was used for data evaluation. The results show the generally exothermic character of the process. The free enthalpy changes obtained during formation of malvidin-3- O-glucoside-ellagic acid complexes increase from -17.8 kJ/mol to -40.5 kJ/mol in the presence of Fe(II) ions. The increased free enthalpy is a consequence of the drastic reduction of entropy change due to the slight "swinging" movement of the interacting malvidin and ellagic acid molecules in the complexes stabilized by the ferrous ions. These results are also supported by the findings of other authors stating that iron ions play an important role in the stabilization of color in the plant kingdom and various plant products.

Kunsági-Máté, Sándor; Ortmann, Erika; Kollár, László; Szabó, Kornélia; Nikfardjam, Martin Pour

2008-11-01

303

Oxidation of elemental sulfur, tetrathionate and ferrous iron by the psychrotolerant Acidithiobacillus strain SS3.  

PubMed

Mesophilic iron and sulfur-oxidizing acidophiles are readily found in acid mine drainage sites and bioleaching operations, but relatively little is known about their activities at suboptimal temperatures and in cold environments. The purpose of this work was to characterize the oxidation of elemental sulfur (S(0)), tetrathionate (S4O6(2-)) and ferrous iron (Fe2+) by the psychrotolerant Acidithiobacillus strain SS3. The rates of elemental sulfur and tetrathionate oxidation had temperature optima of 20 degrees and 25 degrees C, respectively, determined using a temperature gradient incubator that involved narrow (1.1 degrees C) incremental increases from 5 degrees to 30 degrees C. Activation energies calculated from the Arrhenius plots were 61 and 89 kJ mol(-1) for tetrathionate and 110 kJ mol(-1) for S(0) oxidation. The oxidation of elemental sulfur produced sulfuric acid at 5 degrees C and decreased the pH to approximately 1. The low pH inhibited further oxidation of the substrate. In media with both S(0) and Fe2+, oxidation of elemental sulfur did not commence until all available ferrous iron was oxidized. These data on sequential oxidation of the two substrates are in keeping with upregulation and downregulation of several proteins previously noted in the literature. Ferric iron was reduced to Fe2+ in parallel with elemental sulfur oxidation, indicating the presence of a sulfur:ferric iron reductase system in this bacterium. PMID:19782750

Kupka, Daniel; Liljeqvist, Maria; Nurmi, Pauliina; Puhakka, Jaakko A; Tuovinen, Olli H; Dopson, Mark

2009-12-01

304

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

305

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

306

Chemical Fixation of Trace Elements in Coal Fly Ash using Ferrous Sulfate Treatment  

NASA Astrophysics Data System (ADS)

Coal fired electric power plants produce 50% of the electricity consumed in the US and generate large volumes of fly ash and other coal combustion by-products (CCBs). The majority of the CCB materials are disposed of in surface impoundments and landfills located throughout the US. Fly ash contains trace elements such as As, B, Cr, Mo, Ni, Se, Sr and V which can have a negative impact on the environment due to leaching by acid rain and groundwater with time. The potential release of these toxic trace elements into the environment is a big concern for the US power industry due to the high cost involved in lining the old and existing ash disposal sites. As a result, simple and effective treatment techniques are needed to stabilize the coal combustion by-products produced by power plants in the ash disposal sites and also to increase the use of coal fly ash for beneficial purposes. This paper reports the results of batch experiments designed to chemically treat coal fly ash with ferrous sulfate solution by promoting the formation of insoluble iron oxy- hydroxide phases that immobilize the toxic trace elements. Four fly ash samples, three acidic (HA, HB and MA) and one alkaline (PD), were treated with a ferrous sulfate (FS) solution (322 ppm Fe) and a ferrous sulfate + calcium carbonate (FS+CC) solution (322 ppm Fe and 28 ppm CaCO3) at solid:liquid ratios of 1:3 and 1:30. The effectiveness of this treatment technique was evaluated by the batch sequential leaching of treated and untreated coal fly ash samples using a synthetic acid rain (SAR) solution (USEPA Method 1312B) and also by a 7-step sequential chemical extraction procedure (SCEP) to understand the mechanism of treatment. The unbuffered FS solution at the 1:30 ratio was highly successful in reducing the mobility of the oxyanionic trace elements As (24-91%), Cr (82-97%), Mo (79-100%), Se (41-87%) and V (55-100%). However, the unbuffered FS treatment failed to reduce the mobility of B, Ni and Sr for the acidic fly ash samples. The buffered FS + CC solution greatly increased the mobility of the oxyanionic trace elements in the acidic fly ash samples, except for Cr in HA and HB fly ash. The buffered FS+CC solution reduced the mobility of all the trace elements except Ni in the alkaline PD fly ash. The ferrous sulfate treatment can be applied directly to the fresh fly ash produced in the electric power plants as well as to the fly ash already placed in the ash disposal facilities. A preliminary estimate indicates that ferrous sulfate treatment of fly ash at a power plant would be cost effective.

Bhattacharyya, S.; Donahoe, R. J.

2008-12-01

307

Dose response of ferrous-xylenol orange gels: the effects of gel substrate, gelation time and dose fractionation  

NASA Astrophysics Data System (ADS)

Investigations of the dose dependent change in optical transmission, dose response, for radiochromic ferrous-xylenol orange-gelatin gels (FXG) 3D optical CT scanning has revealed that gelation time, temperature, and dose fractionation affect the dose response (??/?dose). Correction for these factors is important for developing a reproducible dosimeter that can be reliably calibrated and used clinically. The purpose of this report is to examine trends in dose response changes for the following parameters: gelation time-temperature, concentrations of ferrous ion and xylenol orange (XO), dose range and dose fractionation.

Jordan, K.; Battista, J.

2004-01-01

308

FERROUS METALS RECOVERY AT RECOVERY 1, NEW ORLEANS: PERFORMANCE OF THE MODIFIED SYSTEM. TEST NO. 4.05 AND TEST NO. 4.09, RECOVERY 1, NEW ORLEANS  

EPA Science Inventory

This report documents two series of samplings and the monitoring of enery consumption and shredder hammer wear of the upgraded ferrous recovery system that produces a light ferrous product from the processing of municipal refuse at the New Orleans resource recovery project. A ser...

309

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...

310

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

311

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 (2–7) and each mol of catecholate chelators (3,4-dihydroxiphenilacetic acid—DOPAC and 2,3-dihydroxibenzoic acid—DHBA) reduced about 5–6moles of Fe3+ whereas hydroxamate chelators (acetohydroxamic acid—AHA and desferrioxamine B—DFB)

Valdeir Arantes; Carolina Baldocchi; Adriane Maria Ferreira Milagres

2006-01-01

312

Chelating compounds as potential flash rust inhibitors and melamine & aziridine cure of acrylic colloidal unimolecular polymers (CUPs)  

NASA Astrophysics Data System (ADS)

Waterborne coatings on ferrous substrates usually show flash rusting which decreases the adhesion of the coating and the corrosion products can form a stain. Chelating compounds were investigated as potential flash rust inhibitors. Compounds being evaluated include amine alcohols, diamines and sulfur containing amines. A new corrosion inhibitor 2,5-bis(thioaceticacid)-1,3,4-thiadiazole (H2ADTZ) was synthesized and its performance characteristics were evaluated. It was noted that the observed structure of 1,3,4-thiadiazolidine-2,5-dithione (also known as 2,5-dimercapto-1,3,4-thiadiazole (DMTD or DMcT)) has been previously reported in three different tautomeric forms including -dithiol and -dithione. The relative stability of each form as well as the synthesis and characterization of the structures of mono- and dialkylated forms of 5-mercapto-1,3,4-thiadiazole-2(3H)-thione (MTT) were examined. The methods of X-ray crystallography, NMR spectroscopy and ab-initio electronic structure calculations were combined to understand the reactivity and structure of each compound. Polymers were synthesized with a 1:7 or 1:8 ratio of acrylic acid to acrylate monomers to produce an acid rich resin. The polymers were reduced and solvent stripped to produce Colloidal Unimolecular Polymers (CUPs). These particles are typically 3-9 nanometers in diameter depending upon the molecular weight. They were then formulated into a clear coating with either a melamine (bake) or an aziridine (ambient cure) and then cured. The melamine system was solvent free, a near zero VOC and the aziridine system was very low to near zero VOC. The coatings were evaluated for their MEK resistance, adhesion, hardness, gloss, flexibility, wet adhesion, abrasion and impact resistance properties.

Mistry, Jigar Kishorkumar

313

Iron chelation therapy with deferoxamine in Cooley anemia.  

PubMed

The iron-chelating agent, deferoxamine, was studied in 16 patients with thalassemia major. Urinary excretion of iron in response to 0.75 gm of deferoxamine, intramuscularly, ranged from 2.2 to 44.8 mg Fe/24 hours. In response to a subcutaneous infusion of 1.5 gm deferoxamine for 18 hours, iron excretion increased by an average of 240%. The intravenous infusion of large doses of deferoxamine for 18 hours resulted in the highest rate of iron excretion, as much as 447.5 mg Fe/24 hours in response to 16 gm of deferoxamine. Administration of vitamin C increased chelation-induced excretion of iron in most patients more than five years of age. Preliminary evidence suggests that further iron accumulation can be prevented and excessive iron stores can be depleted by the intramuscular, subcutaneous, or intravenous administration of deferoxamine. PMID:633031

Cohen, A; Schwartz, E

1978-04-01

314

Preconcentration and selective metal ion separation using chelating micelles.  

PubMed

Chelating aggregates consisting of Triton X100 host micelles and hydrophobic derivatives of PAN have been examined as suitable candidates for preconcentration and selective separation of transition metal ions through micellar-enhanced ultrafiltration. The effective accumulation in the surfactant-rich retentate of nickel(II), copper(II), cobalt(II), manganese(II) and zinc(II), present at trace levels in aqueous samples, has been achieved by operating at pH ca. 6 with a ligand having a binding constant to the host micelles higher than 2000 l./mol. The efficient separation of micelle-bound metal chelates from unreactive ions has been assessed, together with the feasibility of selective enrichment and purification of the investigated metal ions present in mixtures through a multistage process. PMID:18966066

Pramauro, E; Prevot, A B; Zelano, V; Hinze, W L; Viscardi, G; Savarino, P

1994-08-01

315

Iron chelation: a potential therapeutic strategy in oesophageal cancer.  

PubMed

Raised intracellular iron has been identified as a potential aetiological factor in the development of several epithelial malignancies, including those of the gastrointestinal tract. The mechanism behind this increase is thought to include disorders of iron uptake and storage. Several iron chelators have been identified as potential anti-tumour agents, with much work undertaken to ascertain the exact mode of action. Despite this, there is little known about the role that these drugs play in the cellular iron metabolism of oesophageal cancer. Consequently, the present study looks to review the relationship of two clinically important iron-chelating agents, deferoxamine and deferasirox, on cellular iron uptake and storage in oesophageal squamous and adenocarcinoma. This provides important evidence for the debate about the role these agents have in the clinical management of such tumours. PMID:23278384

Keeler, B D; Brookes, M J

2013-03-01

316

Iron Chelators as Potential Therapeutic Agents for Parkinson's Disease  

PubMed Central

Parkinson’s disease (PD) is a neurological disorder characterized by the progressive impairment of motor skills in patients. Growing evidence suggests that abnormal redox-active metal accumulation, caused by dysregulation, plays a central role in the neuropathology of PD. Redox-active metals (e.g. Fe and Cu) catalyze essential reactions for brain function. However, these metals can also participate in the generation of highly toxic free radicals that can cause oxidative damage to cells and ultimately lead to the death of dopamine-containing neurons. The emergence of redox-active metals as key players in the pathogenesis of PD strongly suggests that metal-chelators could be beneficial in the treatment of this condition. This mini-review summarizes major recent developments on natural, synthetic iron chelating compounds and hydrogen peroxide-triggered prochelators as potential candidates for PD treatment.

Perez, Carlos A.; Tong, Yong; Guo, Maolin

2009-01-01

317

Specific iron chelators determine the route of ferritin degradation  

PubMed Central

Deferoxamine (DFO) is a high-affinity Fe (III) chelator produced by Streptomyces pilosus. DFO is used clinically to remove iron from patients with iron overload disorders. Orally administered DFO cannot be absorbed, and therefore it must be injected. Here we show that DFO induces ferritin degradation in lysosomes through induction of autophagy. DFO-treated cells show cytosolic accumulation of LC3B, a critical protein involved in autophagosomal-lysosomal degradation. Treatment of cells with the oral iron chelators deferriprone and desferasirox did not show accumulation of LC3B, and degradation of ferritin occurred through the proteasome. Incubation of DFO-treated cells with 3-methyladenine, an autophagy inhibitor, resulted in degradation of ferritin by the proteasome. These results indicate that ferritin degradation occurs by 2 routes: a DFO-induced entry of ferritin into lysosomes and a cytosolic route in which iron is extracted from ferritin before degradation by the proteasome.

De Domenico, Ivana; Ward, Diane McVey

2009-01-01

318

Nanomagnetic chelators for removal of toxic metal ions  

NASA Astrophysics Data System (ADS)

Ethylenediamine trtraaceteic acid (EDTA) functionalized Fe3O4 nanomagnetic chelators (NMCs) were synthesized by co-precipitation method followed by in-situ grafting of EDTA. XRD and TEM analyses reveal the formation of highly crystalline single-phase Fe3O4 nanoparticles of size about 10 nm. Surface functionalization of Fe3O4 with EDTA was evident from FTIR spectroscopy, TGA analysis and zeta-potential measurement. These NMCs exhibit superparamagnetic behavior at room temperature with strong field dependent magnetic responsivity. It has been observed that NMCs have strong tendency for adsorption of various toxic metal ions (Ni2+, Cr3+, Cu2+, Cd2+, Co2+ and Pb2+) from waste-water. Furthermore, these magnetic chelators can be used as highly efficient separable and reusable material for removal of toxic metal ions.

Singh, Sarika; Barick, K. C.; Bahadur, D.

2013-02-01

319

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

2013-10-01

320

A new method for preparation of magnetite from iron oxyhydroxide or iron oxide and ferrous salt in aqueous solution  

NASA Astrophysics Data System (ADS)

In this study, a new method is proposed for the preparation of Fe 3O 4 from iron oxyhydroxides (goethite, akaganeite, lepidocrocite, feroxyhyte and ferrihydrite) or iron oxide (hematite) and ferrous salt in aqueous solution. The product is magnetite with various particle sizes. Products are characterized by X-ray powder diffraction, IR spectra and vibrating sample magnetometery.

Kahani, S. A.; Jafari, M.

2009-07-01

321

Composition of Aqueous Extracts of Broiler Litter Treated with Aluminum Sulfate, Ferrous Sulfate, Ferric Chloride and Gypsum  

Microsoft Academic Search

More knowledge on the composition of aqueous extracts of broiler litter amended for Water Soluble P (WSP) reduction would help to understand how amendments work. We measured pH, concentrations of Ca, Mg, Fe, Al, Cu, Mn, Zn, Molybdate Reactive P (MRP), and Dissolved Unreactive P (DUP) in water extracts of broiler litter treated with aluminum sulfate (ALS), ferrous sulfate (FES),

ARMANDO S. TASISTRO; DAVID E. KISSEL

2006-01-01

322

Lead poisoning combined with cadmium in sheep and horses in the vicinity of non-ferrous metal smelters  

Microsoft Academic Search

The diagnosis of lead poisoning combined with cadmium in sheep and horses living on farmland in the vicinity of non-ferrous metal smelters in Baiyin of Gansu province in China was based on laboratory findings as well as clinical signs. The concentrations of lead, cadmium, copper and zinc in soils, water, forages, feed and blood, hair and tissues of affected sheep

Z. P. Liu

2003-01-01

323

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

324

An intelligent system for calculating the scale of rational, enlarged production of an underground non-ferrous metal mine  

Microsoft Academic Search

The enlarged production scale of underground non-ferrous metal mines is affected by many uncertain factors difficult to describe mathematically with any level of accuracy. The problem can be solved by a synthesis of artificial intelligence. Based on the analysis of the major factors affecting the scale of enlarged production, we first interpreted in detail the design principles and structure of

Ming-gui ZHENG; Si-jing CAI

2008-01-01

325

Arsenic Encapsulation Using Portland Cement With Ferrous Sulfate/Lime And Terra-BondTM Technologies - Microcharacterization And Leaching Studies  

EPA Science Inventory

This work reports the results of an investigation on the treatment and encapsulation of arsenic-containing materials by Portland cement with ferrous sulfate and lime (PFL) and Terra-BondTM, a commercially available patented technology. The arsenic materials treated we...

326

Chemical Cleaning of a Brass-Tubed Turbine Condenser after Five Years of Operation with Ferrous Sulphate Dosing.  

National Technical Information Service (NTIS)

The purpose of chemically cleaning the brass-tubed turbine condenser was to remove the ferrous oxide layer and corrosion products which are mainly copper oxide Cu sub 2 O. Laboratory tests were conducted where 1 m long pieces of tube were installed in a s...

H. Gutberlet

1983-01-01

327

Potential CO 2 emission reduction for BF–BOF steelmaking based on optimised use of ferrous burden materials  

Microsoft Academic Search

Currently, the blast furnace (BF) to basic oxygen furnace (BOF) is the dominant steel production route in the steel industry. The direct CO2 emission in this process system exceeds 1t of CO2\\/t of crude steel produced. Different ferrous burden materials, for instance iron ore and scrap, can be used in various proportions in this steelmaking route. This paper analyses how

Chuan Wang; Christer Ryman; Jan Dahl

2009-01-01

328

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 ...

329

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

330

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...

331

Targeting Chelatable Iron as a Therapeutic Modality in Parkinson's Disease  

PubMed Central

Abstract Aims: The pathophysiological role of iron in Parkinson's disease (PD) was assessed by a chelation strategy aimed at reducing oxidative damage associated with regional iron deposition without affecting circulating metals. Translational cell and animal models provided concept proofs and a delayed-start (DS) treatment paradigm, the basis for preliminary clinical assessments. Results: For translational studies, we assessed the effect of oxidative insults in mice systemically prechelated with deferiprone (DFP) by following motor functions, striatal dopamine (HPLC and MRI-PET), and brain iron deposition (relaxation-R2*-MRI) aided by spectroscopic measurements of neuronal labile iron (with fluorescence-sensitive iron sensors) and oxidative damage by markers of protein, lipid, and DNA modification. DFP significantly reduced labile iron and biological damage in oxidation-stressed cells and animals, improving motor functions while raising striatal dopamine. For a pilot, double-blind, placebo-controlled randomized clinical trial, early-stage Parkinson's patients on stabilized dopamine regimens enrolled in a 12-month single-center study with DFP (30?mg/kg/day). Based on a 6-month DS paradigm, early-start patients (n=19) compared to DS patients (n=18) (37/40 completed) responded significantly earlier and sustainably to treatment in both substantia nigra iron deposits (R2* MRI) and Unified Parkinson's Disease Rating Scale motor indicators of disease progression (p<0.03 and p<0.04, respectively). Apart from three rapidly resolved neutropenia cases, safety was maintained throughout the trial. Innovation: A moderate iron chelation regimen that avoids changes in systemic iron levels may constitute a novel therapeutic modality for PD. Conclusions: The therapeutic features of a chelation modality established in translational models and in pilot clinical trials warrant comprehensive evaluation of symptomatic and/or disease-modifying potential of chelation in PD. Antioxid. Redox Signal. 21, 195–210.

Moreau, Caroline; Devedjian, Jean Christophe; Kluza, Jerome; Petrault, Maud; Laloux, Charlotte; Jonneaux, Aurelie; Ryckewaert, Gilles; Garcon, Guillaume; Rouaix, Nathalie; Duhamel, Alain; Jissendi, Patrice; Dujardin, Kathy; Auger, Florent; Ravasi, Laura; Hopes, Lucie; Grolez, Guillaume; Firdaus, Wance; Sablonniere, Bernard; Strubi-Vuillaume, Isabelle; Zahr, Noel; Destee, Alain; Corvol, Jean-Christophe; Poltl, Dominik; Leist, Marcel; Rose, Christian; Defebvre, Luc; Marchetti, Philippe; Cabantchik, Z. Ioav; Bordet, Regis

2014-01-01

332

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

333

CHELATION THERAPY FOR IRON OVERLOAD: NURSING PRACTICE IMPLICATIONS  

PubMed Central

Many diseases of the blood are treated with blood transfusion therapy. Chronic transfusions can cause iron overload, and, if untreated, can cause end-organ damage. Chelation therapy provides a way of treating iron overload and minimizing its adverse effects. Nurses need to understand that iron overload is a consequence of chronic blood transfusion, and they need to know what effects it has on end-organs and what treatment options are available.

Eckes, Ellen J.

2011-01-01

334

Metal Chelation and Inhibition of Bacterial Growth in Tissue Abscesses  

Microsoft Academic Search

Bacterial infection often results in the formation of tissue abscesses, which represent the primary site of interaction between invading bacteria and the innate immune system. We identify the host protein calprotectin as a neutrophil-dependent factor expressed inside Staphylococcus aureus abscesses. Neutrophil-derived calprotectin inhibited S. aureus growth through chelation of nutrient Mn2+ and Zn2+: an activity that results in reprogramming of

Brian D. Corbin; Erin H. Seeley; Andrea Raab; Joerg Feldmann; Michael R. Miller; Victor J. Torres; Kelsi L. Anderson; Brian M. Dattilo; Paul M. Dunman; Russell Gerads; Richard M. Caprioli; Wolfgang Nacken; Walter J. Chazin; Eric P. Skaar

2008-01-01

335

Targeting chelatable iron as a therapeutic modality in Parkinson's disease.  

PubMed

Abstract Aims: The pathophysiological role of iron in Parkinson's disease (PD) was assessed by a chelation strategy aimed at reducing oxidative damage associated with regional iron deposition without affecting circulating metals. Translational cell and animal models provided concept proofs and a delayed-start (DS) treatment paradigm, the basis for preliminary clinical assessments. Results: For translational studies, we assessed the effect of oxidative insults in mice systemically prechelated with deferiprone (DFP) by following motor functions, striatal dopamine (HPLC and MRI-PET), and brain iron deposition (relaxation-R2*-MRI) aided by spectroscopic measurements of neuronal labile iron (with fluorescence-sensitive iron sensors) and oxidative damage by markers of protein, lipid, and DNA modification. DFP significantly reduced labile iron and biological damage in oxidation-stressed cells and animals, improving motor functions while raising striatal dopamine. For a pilot, double-blind, placebo-controlled randomized clinical trial, early-stage Parkinson's patients on stabilized dopamine regimens enrolled in a 12-month single-center study with DFP (30?mg/kg/day). Based on a 6-month DS paradigm, early-start patients (n=19) compared to DS patients (n=18) (37/40 completed) responded significantly earlier and sustainably to treatment in both substantia nigra iron deposits (R2* MRI) and Unified Parkinson's Disease Rating Scale motor indicators of disease progression (p<0.03 and p<0.04, respectively). Apart from three rapidly resolved neutropenia cases, safety was maintained throughout the trial. Innovation: A moderate iron chelation regimen that avoids changes in systemic iron levels may constitute a novel therapeutic modality for PD. Conclusions: The therapeutic features of a chelation modality established in translational models and in pilot clinical trials warrant comprehensive evaluation of symptomatic and/or disease-modifying potential of chelation in PD. Antioxid. Redox Signal. 21, 195-210. PMID:24251381

Devos, David; Moreau, Caroline; Devedjian, Jean Christophe; Kluza, Jérome; Petrault, Maud; Laloux, Charlotte; Jonneaux, Aurélie; Ryckewaert, Gilles; Garçon, Guillaume; Rouaix, Nathalie; Duhamel, Alain; Jissendi, Patrice; Dujardin, Kathy; Auger, Florent; Ravasi, Laura; Hopes, Lucie; Grolez, Guillaume; Firdaus, Wance; Sablonnière, Bernard; Strubi-Vuillaume, Isabelle; Zahr, Noel; Destée, Alain; Corvol, Jean-Christophe; Pöltl, Dominik; Leist, Marcel; Rose, Christian; Defebvre, Luc; Marchetti, Philippe; Cabantchik, Z Ioav; Bordet, Régis

2014-07-10

336

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. Hernández-Allica; J. M. Becerril; I. Amezaga; I. Albizu; M. Onaindia; C. Garbisu

2004-01-01

337

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. 3 figs.

Harkness, J.B.L.; Doctor, R.D.; Wingender, R.J.

1985-08-05

338

Cytoplasmic ATPase involved in ferrous ion uptake from magnetotactic bacterium Magnetospirillum magneticum AMB-1.  

PubMed

A non-magnetic mutant of Magnetospirillum magneticum AMB-1 (NMA61), harboring a defective gene located in ORF4 (gene ID: amb4111) was generated by transposon mutagenesis. Biochemical characterization of the gene product of ORF4 revealed that it was localized in the cytoplasm and displayed ATPase activity. The ability of NMA61 to take up iron was severely compromised. Ferrous ion concentration in the medium decreased more with the wild-type than with NMA61, while the iron content in the cytoplasmic fraction of NMA61 was much lower than the wild-type strain. This cytoplasmic ATPase is essential for iron trafficking within M. magneticum AMB-1. PMID:17618623

Suzuki, Takeyuki; Okamura, Yoshiko; Arakaki, Atsushi; Takeyama, Haruko; Matsunaga, Tadashi

2007-07-24

339

Inhibition of Clostridium perfringens by heated combinations of nitrite, sulfur, and ferrous or ferric ions.  

PubMed Central

Heating mixtures of sodium nitrite, cysteine, and either ferrous sulfate or ferric chloride at 121 C for 20 min at pH 6.5 or 6.3 produced a potent inhibitor of Clostridium perfringens vegetative cells and spores when added to previously heat-sterilized fluid thioglycolate medium. When the mixtures containing FeSO4 at pH 5.2 or FeCl3 at pH 2.7 were heated, the inhibitory effect was not produced. These responses seem to eliminate the possibility that cysteine nitrosothiol is the agent responsible for the heated-nitrite inhibition known as the Perigo effect. The variable pH responses also cast doubt upon the role of the black Roussin salt as the agent of the Perigo effect.

Asan, T; Solberg, M

1976-01-01

340

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

NASA Astrophysics Data System (ADS)

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 optical absorption peak of interest. The proposed technique for 3-D measurements of an absorbed dose is based on the imaging of phantoms composed of sets of properly piled up gel slices. The slice thickness was optimized in order to obtain a good image contrast as well as a good in-depth spatial resolution. To test the technique, a phantom has been irradiated with a collimated ?-beam and then analysed. Proper software was adapted in order to visualise the images of all slices and to attain the 2-D profiles of the dose absorbed by each slice.

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

1999-02-01

341

Evaluation of a ferrous benzoic xylenol orange transparent PVA cryogel radiochromic dosimeter.  

PubMed

A stable cryogel dosimeter was prepared using ferrous benzoic xylenol orange (FBX) in a transparent poly-(vinyl alcohol) (PVA) cryogel matrix. Dose response was evaluated for different numbers of freeze-thaw cycles (FTCs), different concentrations of PVA, and ratios of water/dimethyl sulfoxide. Linear relationships between dose and absorbance were obtained in the range of 0-1000 cGy for all formulations. Increasing the concentration of PVA and number of FTCs resulted in increased absorbance and sensitivity. The effects of energy and dose rate were also evaluated. No significant dose rate dependence was observed over the range 1.05 to 6.33 Gy min(-1). No energy response was observed over photon energies of 6, 10, and 18 MV. PMID:24619200

Eyadeh, Molham M; Farrell, Thomas J; Diamond, Kevin R

2014-04-01

342

Mars: Compositional variability of ferric/ferrous minerals and polar volatiles from groundbased imaging spectroscopy  

NASA Technical Reports Server (NTRS)

In an attempt to further constrain the ferric and ferrous mineralogy of Mars, Bell et al. (1989; 1990) obtained high resolution imaging spectroscopic data of much of the Martian surface in the visible and near-infrared (0.4-1.1 micron) during the 1988 opposition. Preliminary analysis of these data showed further evidence of crystalline hematite absorption features at 0.8-0.9 microns and 0.6-0.7 microns. Additionally, the 0.6-0.7 micron Fe(III) band was shown to vary across the surface, with a substantial correlation with albedo in the region studied. Calibration of this 1988 data set (along with a similar data set obtained during the 1990 opposition) has been ongoing, and some of the most recent results of the analysis of these data using linear spectral mixture modeling are reported.

Bell, James F., III

1992-01-01

343

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

NASA Technical Reports Server (NTRS)

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.

1986-01-01

344

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

345

Ferritin versus ferrous sulphate preparations: a controlled study in sideropaenic patients.  

PubMed

A double-blind study was carried out in 54 patients requiring iron therapy to compare the effects of orally administered bivalent and trivalent iron over a period of 12 weeks. Patients were allocated at random to receive ferrous sulphate (100 mg/day), ferritin (80 mg/day as Fe3+) or a combination of ferritin (80 mg Fe3+/day), folinic acid and vitamin B12 coenzyme. Haematological measurements made before and during treatment showed that, whilst there were significant improvements in all of the parameters studied with both the bivalent and trivalent forms of iron, the results were more progressive and consistent with the two ferritin preparations, indicating that ferritin is clinically effective as a physiological iron donor in sideropaenic conditions. PMID:3299394

Sás, G; Scheffer, K; Schreiber, G; Bräuer, H; Ceccarelli, G

1986-01-01

346

Antibacterial and antibiofilm effects of iron chelators against Prevotella intermedia.  

PubMed

Prevotella intermedia, a major periodontopathogen, has been shown to be resistant to many antibiotics. In the present study, we examined the effect of the FDA-approved iron chelators deferoxamine (DFO) and deferasirox (DFRA) against planktonic and biofilm cells of P. intermedia in order to evaluate the possibility of using these iron chelators as alternative control agents against P. intermedia. DFRA showed strong antimicrobial activity (MIC and MBC values of 0.16 mg ml(-1)) against planktonic P. intermedia. At subMICs, DFRA partially inhibited the bacterial growth and considerably prolonged the bacterial doubling time. DFO was unable to completely inhibit the bacterial growth in the concentration range tested and was not bactericidal. Crystal violet binding assay for the assessment of biofilm formation by P. intermedia showed that DFRA significantly decreased the biofilm-forming activity as well as the biofilm formation, while DFO was less effective. DFRA was chosen for further study. In the ATP-bioluminescent assay, which reflects viable cell counts, subMICs of DFRA significantly decreased the bioactivity of biofilms in a concentration-dependent manner. Under the scanning electron microscope, P. intermedia cells in DFRA-treated biofilm were significantly elongated compared to those in untreated biofilm. Further experiments are necessary to show that iron chelators may be used as a therapeutic agent for periodontal disease. PMID:23329319

Moon, Ji-Hoi; Kim, Cheul; Lee, Hee-Su; Kim, Sung-Woon; Lee, Jin-Yong

2013-09-01

347

Metal-chelating nanopolymers for antibody purification from human plasma.  

PubMed

The purification of immunoglobulin G (IgG) from human plasma was performed by using a novel metal-chelated adsorbent with nano size. The non-porous nanoparticles were produced by surfactant free emulsion polymerization of ethylene glycol dimethacrylate (EDMA) and 2-methacryloylamidohistidine (MAH). Then, Cu(II) ions were chelated on the nanoparticles. The nano-poly(EDMA-MAH) nanoparticles were characterized by Fourier transform infrared, scanning electron microscope, atomic force microscope and elemental analysis. The non-porous nanoparticles were spherical form and have 100-250 nm size distribution. The maximum IgG adsorption capacity of the Cu(II) chelated nanoparticles was found to be 463 mg/g polymer at pH 7.0 in HEPES buffer. Desorption of IgG was performed by 1.0 M NaCl and desorption rate was found to be 97 %. IgG was obtained from human plasma with purity of 94 % (up to 578 mg/g polymer). The non-porous nanoparticles allowed one-step purification of IgG from human plasma. PMID:22971831

Uygun, Deniz Akta?; ?enay, R Hilal; Türkcan, Ceren; Akgöl, Sinan; Denizli, Adil

2012-11-01

348

Determination of aluminium using high performance chelation ion chromatography.  

PubMed

The suitability of high performance chelation ion chromatography (HPCIC) using postcolumn reaction for the separation and determination of dissolved aluminium in complex samples was investigated. Use of a chelating ion-exchanger allowed for differentiation between kinetically labile and kinetically stable species of aluminium. Separation through a combination of chelation and cation-exchange was achieved using a 200 x 4.0 mm id column packed with particles of silica functionalised with iminodiacetic acid, with nitric acid-potassium chloride eluents. A temperature anomaly causing a five-fold increase in column efficiency for aluminium is believed to be a result of localised temperature effects in the particular type of instrument used. Postcolumn reagents investigated for the photometric detection included Tiron, Pyrocatechol Violet, Chrome Azurol S, and Eriochrome Cyanine R. The lowest detection limit (2.7 microg/L for a 100 microL sample volume) was achieved using 0.25 mM Eriochrome Cyanine R in 0.2 M hexamine (pH 6.1) with 1 mM cetyltrimethylpyridium bromide (CTAB). The optimised HPCIC system was applied successfully to the quantification of labile aluminium in paper mill process water. PMID:18563745

Tria, Juliette; Haddad, Paul R; Nesterenko, Pavel N

2008-07-01

349

Effectiveness of chelation therapy with time after acute uranium intoxication  

SciTech Connect

The effect of increasing the time interval between acute uranium exposure and chelation therapy was studied in male Swiss mice. Gallic acid, 4,5-dihydroxy-1,3- benzenedisulfonic acid (Tiron), diethylenetriaminepentaacetic acid (DTPA), and 5-aminosalicylic acid (5-AS) were administered ip at 0, 0.25, 1, 4, and 24 hr after sc injection of 10 mg/kg of uranyl acetate dihydrate. Chelating agents were given at doses equal to one-fourth of their respective LD50 values. Daily elimination of uranium into urine and feces was determined for 4 days after which time the mice were killed, and the concentration of uranium was measured in kidney, spleen, and bone. The excretion of uranium was especially rapid in the first 24 hr. Treatment with Tiron or gallic acid at 0, 0.25, or 1 hr after uranium exposure significantly increased the total excretion of the metal. In kidney and bone, only administration of Tiron at 0, 0.25, or 1 hr after uranium injection, or gallic acid at 1 hr after uranium exposure significantly reduced tissue uranium concentrations. Treatment at later times (4 to 24 hr) did not increase the total excretion of the metal and did not decrease the tissue uranium concentrations 4 days after uranyl acetate administration. The results show that the length of time before initiating chelation therapy for acute uranium intoxication greatly influences the effectiveness of this therapy.

Domingo, J.L.; Ortega, A.; Llobet, J.M.; Corbella, J. (Univ. of Barcelona, Reus (Spain))

1990-01-01

350

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

351

Structural basis of the ferrous iron specificity of the yeast ferroxidase, Fet3p.  

PubMed

Fet3p is a multicopper oxidase (MCO) that functions together with the iron permease, Ftr1p, to support high-affinity Fe uptake in yeast. Fet3p is a ferroxidase that, like ceruloplasmin and hephaestin, couples the oxidation of 4 equiv of Fe(II) to the reduction of O2 to 2 H2O. The ferrous iron specificity of this subclass of MCO proteins has not been delineated by rigorous structure-function analysis. Here the crystal structure of Fet3p has been used as a template to identify the amino acid residues that confer this substrate specificity and then to quantify the contributions they make to this specific reactivity by thermodynamic and kinetic analyses. In terms of the Marcus theory of outer-sphere electron transfer, we show here that D283, E185, and D409 in Fet3p provide a Fe(II) binding site that actually favors ferric iron; this site thus reduces the reduction potential of the bound Fe(II) in comparison to that of aqueous ferrous iron, providing a thermodynamically more robust driving force for electron transfer. In addition, E185 and D409 constitute parts of the electron-transfer pathway from the bound Fe(II) to the protein's type 1 Cu(II). This electronic matrix coupling relies on H-bonds from the carboxylate OD2 atom of each residue to the NE2 NH group of the two histidine ligands at the type 1 Cu site. These two acidic residues and this H-bond network appear to distinguish a fungal ferroxidase from a fungal laccase since the specificity that Fet3p has for Fe(II) is completely lost in a Fet3pE185A/D409A mutant. Indeed, this double mutant functions kinetically better as a laccase, albeit a relatively inefficient one. PMID:17042492

Stoj, Christopher S; Augustine, Anthony J; Zeigler, Lynn; Solomon, Edward I; Kosman, Daniel J

2006-10-24

352

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 °C in ferrous-sulfate medium amended with 0–24.2 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 16.9–17.6 ?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 0–48 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

353

Optical Imaging of Radiation Dose Distributions in a Ferrous-Gelatin Orange Gel Dosimeter.  

NASA Astrophysics Data System (ADS)

A new tissue-equivalent radiation dosimeter was developed and studied. The dosimeter consists of a ferrous -xylenol orange solution suspended in a gelatin matrix. Ferric ions produced from irradiation react with the xylenol orange dye to form a complex which absorbs light maximally at 585 nm, in the visible band. The optical density at this wavelength increases in proportion to the absorbed dose over a limited dose range. The dosimeter's gelatin component serves to solidify the chemical system so that an irradiated dosimeter yields a stable three-dimensional image of its dose distribution. The dosimeter is transparent to most other visible wavelengths so that the image of the dose distribution is clearly visible to the naked eye. Experiments were conducted in order to optimize the sensitivity of the chemical system and determine the conditions which produce a linear dose response for doses up to 6 Gray. A computed-tomography system was developed in order to quantify the dose-distribution images recorded by the dosimeter. The accuracy of the tomographic-reconstruction process was to be determined by comparing the resulting data to that obtained by standard dosimetry techniques. It was found that dosimeter sensitivity is gained with increasing ferrous and/or gelatin concentration and decreasing xylenol orange concentration. It was also determined that a dose range which provides a linear response can be extended by increasing the xylenol orange concentration and/or decreasing the dosimeter's sensitivity. An optimal chemical formulation that achieves a balance among sensitivity, linearity, and dosimeter stability was defined. In preliminary tests involving a homogeneous-dose simulation, the tomography code was tested and determined to be in error as it produced an inaccurate rendering of the dosimeter volume. Reasons for this error are discussed and suggestions for an improved optical-tomography system are made.

Fried, Richard Marc

354

Cysteine, a chelating moiety for synthesis of 99Tcm radiopharmaceuticals. III: Functionalization of hydroxy group for 99Tcm chelation.  

PubMed

A method is offered for converting an organic hydroxy compound to a 99Tcm-binding ligand under mild experimental conditions. Cyclohexanol was selected as a typical hydroxy compound and to this molecule cysteine was attached through substitution at the sulphur atom by a two-step chemical synthesis. The ligand thus obtained could be successfully radiolabelled with 99Tcm. The biodistribution of the resulting radiolabelled compound had the characteristic of a mixed hydrophilic-lipophilic 99Tcm chelate and was similar to that of 99Tcm-HIDA derivatives, a well established class of 99Tcm-chelates. So it may be concluded that the above method of functionalization of a hydroxy compound does not generate any unusual physiological properties and may be recommended as a general method for radiolabelling an organic compound at the alcoholic site with 99Tcm. PMID:2362743

Chatterjee, M; Banerjee, S

1990-04-01

355

High Incidence of Cardiomyopathy in Beta-Thalassaemia Patients Receiving Regular Transfusion and Iron Chelation: Reversal by Intensified Chelation  

Microsoft Academic Search

Cardiac scintigraphy has been performed in 60 ?-thalassaemia major patients aged 8-35 years who received regular blood transfusions and subcutaneous desferrioxamine (DFX) chelation. Fifty-seven showed no clinical, radiological or electrocardiographic evidence of heart disease and 3 had clinically apparent cardiac failure. Twenty-two patients (37%) showed severe cardiac functional impairment defined by a resting left ventricular ejection fraction (LVEF) < 45%

M. A. Aldouri; B. Wonke; A. V. Hoffbrand; D. M. Flynn; S. E. Ward; J. E. Agnew; A. J. W. Hilson

1990-01-01

356

Ulceration of the oral mucosa following direct contact with ferrous sulfate in elderly patients: a case report and a review of the French National Pharmacovigilance Database  

PubMed Central

Objective To report a series of cases of ulceration of the oral mucosa linked to direct contact with ferrous sulfate in elderly patients. Case summary The first case report concerns the occurrence of widespread oral ulceration in an 87-year-old woman with Alzheimer’s disease. The ulceration extended from the side of the tongue to the floor of the mouth. No clear explanation was found and various local treatments were ineffective. Once it was realized that the ferrous sulfate tablets (given as an iron supplement) were crushed prior to administration (due to the patient’s deglutition disorder), withdrawal of this treatment led to rapid resolution of the ulceration. Nine other cases of oral ulcerations associated with ferrous sulfate were identified in the French National Pharmacovigilance Database. All but one of the patients were over 80 years of age and the youngest patient (a 54-year-old) had dysphagia associated with facial paralysis. Discussion Only two other reports of oral ulceration due to ferrous sulfate have been published to date. Mucosal toxicity of ferrous sulfate (which is probably related to oxidative stress) has previously been reported for the hypopharynx, the esophageal lumen, and (after inhalation of a tablet) the tracheobronchial tree. Conclusion The mucosal toxicity of ferrous sulfate must be taken into account when deglutition disorders are present (as in elderly patients) and appropriate pharmaceutical formulations (such as syrups) should be administered to at-risk patients. The use of iron salts other than ferrous sulfate could be considered.

Liabeuf, Sophie; Gras, Valerie; Moragny, Julien; Laroche, Marie-Laure; Andrejak, Michel

2014-01-01

357

Action of 1,10-phenanthroline transition metal chelates on P388 mouse lymphocyte leukaemic cells.  

PubMed

(1)Fully coordinated 1,10-phenanthroline and 2,2'-bipyridine chelates of Ru(II) are lethal in vitro to cultured and ascites P388 mouse lymphocytic leukaemic cells; 1,10-phenanthroline chelates are generally more potent than corresponding 2,2'-bipyridine compounds, and mixed-ligand (acetylacetonato) monovalent chelates of both series are more active than the corresponding identical-ligand divalent chelates. Lethal potency is greatest for Ru(II) chelates containing highly alkylated ligands. (2) Within two series of tetramethyl-1,10-phenanthroline chelates, the inert Ru(II) and Ni(II) members are less active against P388 cultured and ascites cells than the corresponding more labile chelates of Cu(II), Cd(II), Zn(II), Fe(II), and Co(II); for the ascites cells, the rank order of lethal potency of the chelates correlates reasonably well with their anticipated rank order of kinetic reactivity. (3) Repeated subculture of P388 cells in the presence of a mixed-ligand Ru(II) chelate has produced a cell line that shows a stable 10-fold resistance to the chelate; the resistant cell line is selectively cross-resistant to certain Ru(II) identical and mixed-ligand chelates. (4) The presence of a fluorescent Ru(II) chelate has been demonstrated at the surface and within the cytoplasm and nucleus of P388 ascites cells exposed to it either in vitro or in the mouse. (5) Ru(II) and Cu(II) chelates of tetramethyl-1,10-phenanthroline do not appear to be chemotherapeutically active against P388 ascites cells in the mouse. PMID:837467

Shulman, A; Laycock, G A

1977-01-01

358

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

359

Synthesis and characterization of poly(acrylaminophosphonic-carboxyl-hydrazide) chelating fibre  

Microsoft Academic Search

The poly(acrylaminophosphonic-carboxyl-hydrazide) chelating ion exchange fibre was prepared by the amination and phosphorization reaction of the hydrazine-modified polyacrylonitrile fibre. The structure of the chelating fibre and the same fibre saturated by Cu(II) and Ag(I) ions was investigated by IR spectrometer in detail. In addition, the crystalline and surface characteristics of the chelating fibre were determined by X-ray diffraction and SEM.

R. X Liu; B. W Zhang; H. X Tang

1999-01-01

360

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

361

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

362

Radiation protection and radiation recovery with essential metalloelement chelates  

SciTech Connect

This review presents the roles of some essential metalloelement-dependent enzymes in tissue maintenance and function, and their responses to radiation injury in accounting for radiation protection and recovery effects observed for nontoxic doses of essential metalloelement compounds. Effects of biochemicals including water undergoing bond radiolysis and the effects of free radicals derived from diatomic oxygen account for the acute and chronic aspects of radiation injury. Copper chelates have radiation protection and radiation recovery activities and cause rapid recovery of immunocompetency and recovery from radiation-induced histopathology. Mice treated with Cu(II){sub 2}(3,5-disopropylsalicy-late){sub 4}[Cu(II){sub 2}(3,5-DIPS){sub 4}] had increased survival and corresponding increases in numbers of myeloid and multipotential progenitor cells early after irradiation and earlier recovery of immune reactivity. Examination of radiation-induced histopathology in spleen, bone marrow, thymus, and small intestine also revealed Cu(II){sub 2}(3,5-DIPS){sub 4}-mediated rapid recovery of radiation-induced histopathology. Most recently, Fe, Mn, and Zn complexes have also been found to prevent death in lethally irradiated mice. These pharmacological effects of essential metalloelement chelates can be understood as due to facilitation of de novo synthesis of essential metalloelement-dependent enzymes which have roles in preventing the accumulation of pathological concentrations of oxygen radicals or repairing biochemical damage caused by radiation-induced bond homolysis. Essential metalloelement chelates offer a physiological approach to prevention and/or treatment of radiation injury. 97 refs., 5 figs., 1 tab.

Sorenson, J.R.J.; Soderberg, L.S.F.; Chang, L.W. [Univ. of Arkansas for Medical Sciences, Little Rock, AR (United States)

1995-12-01

363

H4octapa: an acyclic chelator for 111In radiopharmaceuticals.  

PubMed

This preliminary investigation of the octadentate acyclic chelator H(4)octapa (N(4)O(4)) with (111)In/(115)In(3+) has demonstrated it to be an improvement on the shortcomings of the current industry "gold standards" DOTA (N(4)O(4)) and DTPA (N(3)O(5)). The ability of H(4)octapa to radiolabel quantitatively (111)InCl(3) at ambient temperature in 10 min with specific activities as high as 2.3 mCi/nmol (97.5% radiochemical yield) is presented. In vitro mouse serum stability assays have demonstrated the (111)In complex of H(4)octapa to have improved stability when compared to DOTA and DTPA over 24 h. Mouse biodistribution studies have shown that the radiometal complex [(111)In(octapa)](-) has exceptionally high in vivo stability over 24 h with improved clearance and stability compared to [(111)In(DOTA)](-), demonstrated by lower uptake in the kidneys, liver, and spleen at 24 h. (1)H/(13)C NMR studies of the [In(octapa)](-) complex revealed a 7-coordinate solution structure, which forms a single isomer and exhibits no observable fluxional behavior at ambient temperature, an improvement to the multiple isomers formed by [In(DTPA)](2-) and [In(DOTA)](-) under the same conditions. Potentiometric titrations have determined the thermodynamic formation constant of the [In(octapa)](-) complex to be log K(ML) = 26.8(1). Through the same set of analyses, the [(111/115)In(decapa)](2-) complex was found to have nonoptimal stability, with H(5)decapa (N(5)O(5)) being more suitable for larger metal ions due to its higher potential denticity (e.g., lanthanides and actinides). Our initial investigations have revealed the acyclic chelator H(4)octapa to be a valuable alternative to the macrocycle DOTA for use with (111)In, and a significant improvement to the acyclic chelator DTPA. PMID:22540281

Price, Eric W; Cawthray, Jacqueline F; Bailey, Gwendolyn A; Ferreira, Cara L; Boros, Eszter; Adam, Michael J; Orvig, Chris

2012-05-23

364

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

365

Zinc chelation reduces hippocampal neurogenesis after pilocarpine-induced seizure.  

PubMed

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. PMID:23119054

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

2012-01-01

366

Vanadyl complexes bearing bi- and triphenolate chelate ligands: highly active ethylene polymerisation procatalysts.  

PubMed

Vanadyl procatalysts bearing chelating aryloxide ligands are found to polymerise ethylene, in the presence of dimethylaluminium chloride, with (for this metal) exceptionally high activities. PMID:15340618

Redshaw, Carl; Warford, Lee; Dale, Sophie H; Elsegood, Mark R J

2004-09-01

367

Chelation and determination of labile iron in primary hepatocytes by pyridinone fluorescent probes  

PubMed Central

A series of fluorescent iron chelators has been synthesized such that a fluorescent function is covalently linked to a 3-hydroxypyridin-4-one. In the present study, the fluorescent iron chelators were loaded into isolated rat hepatocytes. The intracellular fluorescence was not only quenched by an addition of a highly lipophilic 8-hydroxyquinoline–iron(III) complex but also was dequenched by the addition of an excess of the membrane-permeable iron chelator CP94 (1,2-diethyl-3-hydroxypyridin-4-one). The time course of uptake of iron and iron chelation in single, intact cells was recorded on-line by using digital fluorescence microscopy. Intracellular concentrations of various fluorescent iron chelators were determined by using a spectrofluorophotometer subsequent to lysis of probe-loaded cells and were found to depend on their partition coefficients; the more hydrophobic the compound, the higher the intracellular concentration. An ex situ calibration method was used to determine the chelatable iron pool of cultured rat hepatocytes. CP655 (7-diethylamino-N-[(5-hydroxy-6-methyl-4-oxo-1,4-dihydropyridin-3-yl)methyl]-N-methyl-2-oxo-2H-chromen-3-carboxamide), which is a moderately lipophilic fluorescent chelator, was found to be the most sensitive probe for monitoring chelatable iron, as determined by the intracellular fluorescence increase induced by the addition of CP94. The concentration of the intracellular chelatable iron pool in hepatocytes was determined by this probe to be 5.4±1.3 ?M.

Ma, Yongmin; de Groot, Herbert; Liu, Zudong; Hider, Robert C.; Petrat, Frank

2005-01-01

368

Chelate-modified polymers for atmospheric gas chromatography  

NASA Technical Reports Server (NTRS)

Chromatographic materials were developed to serve as the stationary phase of columns used in the separation of atmospheric gases. These materials consist of a crosslinked porous polymer matrix, e.g., a divinylbenzene polymer, into which has been embedded an inorganic complexed ion such as N,N'-ethylene-bis-(acetylacetoniminato)-cobalt (2). Organic nitrogenous bases, such as pyridine, may be incorporated into the chelate polymer complexes to increase their chromatographic utility. With such materials, the process of gas chromatography is greatly simplified, especially in terms of time and quantity of material needed for a gas separation.

Christensen, W. W.; Mayer, L. A.; Woeller, F. H. (inventors)

1980-01-01

369

Treatment of superficial siderosis with iron chelation therapy.  

PubMed

Superficial siderosis is caused by recurrent haemorrhage in the subarachnoid space leading to haemosiderin deposition. It typically causes the triad of ataxia, deafness and myelopathy. We report a patient who developed superficial siderosis following neurosurgery for syringomyelia and who had an improvement in his hearing and mobility following treatment with a new iron chelation therapy that can penetrate the blood-brain barrier. It provides an intriguing insight into a therapy that could potentially modify the course of this rare neurodegenerative disorder. Further studies are required to assess the clinical efficacy of deferiprone in superficial siderosis. PMID:23843408

Cummins, Gemma; Crundwell, Gemma; Baguley, David; Lennox, Graham

2013-01-01

370

Influence of globin structures on the state of the heme. Ferrous low spin derivatives.  

PubMed

Studies of high spin ferrous and ferric derivatives led us to conclude that in the quaternary R structure the state of the hemes is similar to that in the free alpha and beta subunits, but in the T structure a tension acts on the hemes which tries to pull the iron and the proximal histidine further from the plane of the porphyrin. We have now studied the effect of inositol hexaphosphate (IHP) on the three low spin ferrous compounds of hemoglobin with O2, CO, and NO. IHP failed to switch the quaternary structure of carbonmonoxy- and oxyhemoglobin A to the T state, but merely caused a transition to an as yet undefined modification of the R structure. IHP is known to cause a switch to the T structure in hemoglobin Kansas. We have found that this switch induces red shifts of the visible alpha and beta absorption bands and the appearance of a shoulder on the red side of the alpha band; these changes are very weak in carbonmonoxy- and slightly stronger in oxyhemoglobin Kansas. As already noted by previous authors, addition of IHP to nitrosylhemoglobin A induces all the changes in uv absorption and CD spectra, sulfhydryl reactivities, and exchangeable proton resonances normally associated with the R leads to T transition, and is accompanied by large changes in the Soret and visible absorption bands. Experiments with nitrosyl hybrids show that these changes in absorption are caused predominantly by the hemes in the alpha subunits. In the accompanying paper Maxwell and Caughey (J. C. Maxwell and W. S. Caughey (1976), Biochemistry, following paper in this issue) report that the NO in nitrosylhemoglobin without IHP gives a single ir stretching frequency characteristic for six-coordinated nitrosyl hemes; addition of IHP causes the appearance of a second ir band, of intensity equal to that of the first, which is characteristic for five-coordinated nitrosyl hemes. Taken together, these results show that the R leads to T transition causes either a rupture or at least a very dramatic stretching of the bond from the iron to the heme-linked histidine, such that an equilibrium is set up between five- and six-coordinated hemes, biased toward five-coordinated hemes in the alpha and six-coordinated ones in the beta subunits. The reason why IHP can switch nitrosyl-, but not carbonmonoxy- or oxyhemoglobin A, from the R to the T structure is to be found in the weakening of the iron-histidine bond by the unpaired NO electron and by the very short Fe-NO bond length. PMID:1247524

Perutz, M F; Kilmartin, J V; Nagai, K; Szabo, A; Simon, S R

1976-01-27

371

Depassivation of aged Fe0 by ferrous ions: implications to contaminant degradation.  

PubMed

Investigation of the effects of ferrous iron (Fe(II)) on the ability of aged (iron oxide coated) Fe(0) to degrade trichloroethylene (TCE) has revealed that, while neither aged Fe(0) nor Fe(II) separately were able to degrade TCE, approximately 95% of the TCE present was degraded after exposure to a mixture of aged Fe(0) and Fe(II) for 21 days. The rates of TCE degradation increased with an increase in Fe(II) concentration from 0 to 1.6 mM and then reached a relative plateau. Results of Fe(II) "adsorption" studies revealed that the equilibrium pH decreased significantly with an increase in Fe(II) concentration. Proton release during adsorption of Fe(II) to iron oxide coatings was identified as being responsible for promotion of surface dissolution and, concomitantly, enhancement in extent of TCE reduction by aged Fe(0). Results of open circuit potential analysis and Tafel plot measurement showed that the corrosion potential of aged Fe(0) (E(corr)) in the presence of Fe(II) decreased to levels similar to that of Fe(0)/Fe(2+), while significant increase in corrosion current (I(corr)) and decrease in polarization resistance (Rp) were found with an increase in Fe(II) concentration. The fact that the effects of different Fe(II) concentrations on the E(corr), I(corr), and Rp was decoupled from their effects on TCE degradation by aged Fe(0) suggested that the enhancement of TCE degradation in the presence of Fe(II) was attributable to the dissolution of the Fe(III) oxyhydroxide layer coating the aged Fe(0). While the presence of Fe(II) may also lead to transformation of the Fe(III) (oxy)hydroxide coating to more crystalline phases, the rate of reduction of compounds such as TCE by Fe(II) associated with the Fe(III) (oxy)hydroxide coating is substantially slower than that mediated by Fe(0). These findings provide new insight into the molecular-scale interaction of aged Fe(0) and ferrous iron with particular implications for sustaining the reactivity of Fe(0)-mediated degradation of contaminants in iron-bearing environments. PMID:24195471

Liu, Tongxu; Li, Xiaomin; Waite, T David

2013-12-01

372

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

373

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

374

Effect of succinate on mitochondrial lipid peroxidation. 1. Comparative studies on ferrous ion and ADP · Fe\\/NADPH-induced peroxidation  

Microsoft Academic Search

Lipid peroxidation in isolated rat liver mitochondria, mitoplast, and mitochondrial inner membrane fragments was induced either by ferrous ions, or in an NADPH-dependent process by complexing with adenine nucleotides (ADP or ATP) iron. The Fe2+-induced lipid peroxidation is nonenzymic when inner membrane fragments are used, while the differences in the inhibitory effect of Mn2+ ions and the stimulatory effect of

Gy. Szabados; A. Andó; L. Tretter; I. Horváth

1987-01-01

375

Influence of chloride and sulfate on formation of akaganéite and schwertmannite through ferrous biooxidation by Acidithiobacillus ferrooxidans cells.  

PubMed

Iron (oxyhydr)oxides play important roles in the fixation of toxic elements and also in the distribution of nutrients for plants in soils. Akaganéite and schwertmannite, as the iron oxyhydroxides having an analogous tunnel structure, have been widely recognized in Fe-rich environments. The objective of this study was to examine the formation of akaganéite/ schwertmannite via biooxidation of 0.1 M of ferrous solution containing only Cl-, SO4(2-) or both the anions with a Cl-/SO4(2-) mole ratio of 1, 3, 6, and 10 by chloride-acclimated Acidithiobacillus ferrooxidans cells. Results showed that ferrous iron in chloride/sulfate-containing solutions could be easily biooxidized to ferric iron, and subsequent Fe(III)-hydrolysis/precipitation could result in the formation of large quantity of akaganéite/schwertmannite precipitates. The resulting precipitates were identified to be the pure akaganéite (Fe8O8(OH)7.1(Cl)0.9, the pure schwertmannite (Fe8O8(OH)4.42(SO4)1.79, and the main schwertmannite phase (Fe8O8(OH)(8-2x)(SO4)x, with 1.09 < or = x < or = 1.73), respectively, under different Cl-/SO4(2-) mole ratio conditions. Obviously, sulfate inhibited drastically the bioformation of akaganéite but facilitated schwertmannite phase occurrence in the ferrous solution containing both sulfate and chloride. However, the presence of chloride ion in initial ferrous solution containing sulfate and Acidithiobacillus ferrooxidans cells would affect the morphology and other characteristics of schwertmannite generated. PMID:19192781

Xiong, Huixin; Liao, Yuehua; Zhou, Lixiang

2008-12-01

376

Experimental determination of the diffusion coefficient in two-dimensions in ferrous sulphate gels using the finite element method  

Microsoft Academic Search

A novel two-dimensional finite element method for modelling the diffusion which occurs in Fricke or ferrous sulphate type\\u000a radiation dosimetry gels is presented. In most of the previous work, the diffusion coefficient has been estimated using simple\\u000a one-dimensional models. This work presents a two-dimensional model which enables the diffusion coefficient to be determined\\u000a in a much wider range of experimental

C. Baldock; P. J. Harris; A. R. Piercy; B. Healy

2001-01-01

377

Three-dimensional radiation dose measurements with Ferrous Benzoic Acid Xylenol Orange in Gelatin gel and optical absorption tomography  

Microsoft Academic Search

The optical characteristics of a Ferrous Benzoic Acid Xylenol Orange in Gelatin (FBXG) gel have been studied over the wavelength range 300–700nm as a function of radiation dose. The unirradiated gel exhibits a strong absorption peak at 440nm; with increasing dose this peak starts to reduce in intensity while a new broad peak centred at 585nm begins to appear. Using

M. A Bero; W. B Gilboy; P. M Glover; J. L Keddie

1999-01-01

378

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

PubMed Central

Oxidation of ferrous iron by Thiobacillus ferrooxidans SM-4 was inhibited competitively by increasing concentrations of ferric iron or cells. A kinetic analysis showed that binding of one inhibitor did not exclude binding of the other and led to synergistic inhibition by the two inhibitors. Binding of one inhibitor, however, was affected by the other inhibitor, and the apparent inhibition constant increased with increasing concentrations of the other inhibitor.

Lizama, Hector M.; Suzuki, Isamu

1989-01-01

379

Kinetic modelling of a solid–liquid reaction: reduction of ferric iron to ferrous iron with zinc sulphide  

Microsoft Academic Search

Reduction of metal ions with solid compounds can be used as a model system to verify various models for reactions between liquids and reactive solids. The reduction of dissolved ferric iron (Fe3+) to ferrous iron (Fe2+) with solid zinc sulphide (ZnS) was investigated in an isothermal, completely back-mixed batch reactor. The influence of temperature, initial concentration of ferric iron, zinc

Heidi Markus; Sigmund Fugleberg; Daniel Valtakari; Tapio Salmi; Dmitry Yu. Murzin; Marko Lahtinen

2004-01-01

380

Ferrous sulphate oxidation using Thiobacillus ferrooxidans cells immobilised on sand for the purpose of treating acid mine-drainage  

Microsoft Academic Search

Thiobacillus ferrooxidans was immobilised on sand (size 0.85 mm to 1.18 mm) for use in a repeated batch and continuously operated packed-bed bioreactor which has not been previously reported in the literature. Repeated batch operation resulted in the complete oxidation of ferrous to ferric iron. The bacteria were active immediately after 3-4 weeks in a non-aqueous medium; i.e. the sand

T. A. Wood; K. R. Murray; J. G. Burgess

2001-01-01

381

Ferrous ion-induced strand breaks in the DNA plasmid pBR322 are not mediated by hydrogen peroxide  

Microsoft Academic Search

Ferrous ion-induced generation of single and multiple strand breaks in the DNA plasmid pBR322 induces the formation of two\\u000a new plasmid forms with altered electrophoretic mobility. The yield of these plasmid forms, the circular relaxed and the linear\\u000a forms, depended on the applied Fe2+ concentration. This property was independent of the presence of hydrogen peroxide in the incubation mixture indicating

Jörg Flemmig; Jürgen Arnhold

2007-01-01

382

Solid-State MultiSensor Array System for Real Time Imaging of Magnetic Fields and Ferrous Objects  

Microsoft Academic Search

In this paper the development of a solid-state sensors based system for real-time imaging of magnetic fields and ferrous objects is described. The system comprises 1089 magneto inductive solid state sensors arranged in a 2D array matrix of 33×33 files and columns, equally spaced in order to cover an approximate area of 300 by 300 mm. The sensor array is

D. Benitez; P. Gaydecki; S. Quek; V. Torres

2008-01-01

383

A review of rate equations proposed for microbial ferrous-iron oxidation with a view to application to heap bioleaching  

Microsoft Academic Search

In view of the fact that the microbial oxidation of ferrous iron to the ferric form is an essential sub-process in the bioleaching of sulphide minerals, the development of a comprehensive rate equation for this sub-process is critical. Such a rate equation is necessary for the design and modelling of both tank and heap bioleach systems.Most of the rate equations

T. V. Ojumu; J. Petersen; G. E. Searby; G. S. Hansford

2006-01-01

384

Study of industrial microencapsulated ferrous sulfate by means of the prophylactic-preventive method to determine its bioavailability.  

PubMed

Radio-iron tests are frequently used to measure the bioavailability of different iron sources for food fortification. As the labeling procedures must be done under laboratory conditions, complementary studies should be carried out to evaluate the bioavailability of iron sources produced on an industrial scale. The iron bioavailability of SFE-171 (ferrous sulfate microencapsulated with phospholipids) was studied in previous reports using the compounds labeled with 59Fe and 55Fe; the results showed an iron bioavailability similar to that of ferrous sulfate. In the present work, the iron bioavailability of industrial SFE-171 was studied by the prophylactic-preventive method in rats using ferrous sulfate as the reference standard. Elemental iron powder was also studied by the same method for comparative purposes. The liver iron concentration of each animal was determined at the end of the experiment in order to evaluate the influence of each iron source on the liver iron stores. Relative biological values of 98 and 34% were found for SFE-171 and elemental iron powder, respectively, while the corresponding relative liver iron concentrations were 104 and 45%. The results provided by the prophylactic-preventive method show that the iron bioavailability of industrial SFE-171 is similar to that of ferrous sulfate; these results are also in agreement to those obtained with the radioactive compounds. We can conclude that the SFE-171 obtained by industrial procedures for massive use in iron food fortification has the same bioavailability as that of the SFE-171 produced and labeled under laboratory conditions. PMID:10955278

Lysionek, A E; Zubillaga, M B; Salgueiro, M J; Sarabia, M I; Caro, R A; Weill, R; Boccio, J R

2000-06-01

385

Were mercury emission factors for Chinese non-ferrous metal smelters overestimated? Evidence from onsite measurements in six smelters.  

PubMed

Non-ferrous metal smelting takes up a large proportion of the anthropogenic mercury emission inventory in China. Zinc, lead and copper smelting are three leading sources. Onsite measurements of mercury emissions were conducted for six smelters. The mercury emission factors were 0.09-2.98 g Hg/t metal produced. Acid plants with the double-conversion double-absorption process had mercury removal efficiency of over 99%. In the flue gas after acid plants, 45-88% was oxidized mercury which can be easily scavenged in the flue gas scrubber. 70-97% of the mercury was removed from the flue gas to the waste water and 1-17% to the sulfuric acid product. Totally 0.3-13.5% of the mercury in the metal concentrate was emitted to the atmosphere. Therefore, acid plants in non-ferrous metal smelters have significant co-benefit on mercury removal, and the mercury emission factors from Chinese non-ferrous metal smelters were probably overestimated in previous studies. PMID:22892573

Zhang, Lei; Wang, Shuxiao; Wu, Qingru; Meng, Yang; Yang, Hai; Wang, Fengyang; Hao, Jiming

2012-12-01

386

The stabilization of ferrous iron by a toxic beta-amyloid fragment and by an aluminum salt.  

PubMed

Aluminum is a recognized neurotoxin in dialysis encephalopathy and may also be implicated in the etiology of neurodegenerative disease, particularly Alzheimer's disease. Alzheimer's disease is suspected to be associated with oxidative stress, possibly due to the pro-oxidant properties of beta-amyloid present in the senile plaques. The underlying mechanism by which this occurs is not well understood although interactions between amyloid and iron have been proposed. The presence of low molecular weight iron compounds can stimulate free radical production in the brain. This study provides a possible explanation whereby both aluminum and beta-amyloid can potentiate free radical formation by stabilizing iron in its more damaging ferrous (Fe2+) form which can promote the Fenton reaction. The velocity, at which Fe2+ is spontaneously oxidized to Fe3+ at 37 degrees C in 20 mM Bis-Tris buffer at pH 5.8, was significantly slowed in the presence of aluminum salts. A parallel effect of prolongation of stability of soluble ferrous ion, was found in the presence of beta-amyloid fragment (25-35). Ascorbic acid, known to potentiate the pro-oxidant properties of iron, was also capable of markedly stabilizing ferrous ions. PMID:10519044

Yang, E Y; Guo-Ross, S X; Bondy, S C

1999-08-28

387

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, José; Salgueiro, María; Olivares, Manuel; Carmuega, Esteban; Weill, Ricardo; Marque, Sebastien; Frereux, Marine; Noirt, Florence

2013-03-01

388

Chelation of lysosomal iron protects against ionizing radiation.  

PubMed

Ionizing radiation causes DNA damage and consequent apoptosis, mainly due to the production of hydroxyl radicals (HO•) that follows radiolytic splitting of water. However, superoxide (O2•-) and H2O2 also form and induce oxidative stress with resulting LMP (lysosomal membrane permeabilization) arising from iron-catalysed oxidative events. The latter will contribute significantly to radiation-induced cell death and its degree largely depends on the quantities of lysosomal redox-active iron present as a consequence of autophagy and endocytosis of iron-rich compounds. Therefore radiation sensitivity might be depressed by lysosome-targeted iron chelators. In the present study, we have shown that cells in culture are significantly protected from ionizing radiation damage if initially exposed to the lipophilic iron chelator SIH (salicylaldehyde isonicotinoyl hydrazone), and that this effect is based on SIH-dependent lysosomal stabilization against oxidative stress. According to its dose-response-modifying effect, SIH is a most powerful radioprotector and a promising candidate for clinical application, mainly to reduce the radiation sensitivity of normal tissue. We propose, as an example, that inhalation of SIH before each irradiation session by patients undergoing treatment for lung malignancies would protect normally aerated lung tissue against life-threatening pulmonary fibrosis, whereas the sensitivity of malignant lung tumours, which usually are non-aerated, will not be affected by inhaled SIH. PMID:20846118

Berndt, Carsten; Kurz, Tino; Selenius, Markus; Fernandes, Aristi P; Edgren, Margareta R; Brunk, Ulf T

2010-12-01

389

Sorption of trace heavy metals by thiol containing chelating resins  

SciTech Connect

The sorption of copper, cadmium, nickel and zinc ions on thiol (-SH) based chelating polymeric resins (thiomethyl resin and Duolite GT-73) has been investigated. The physical and chemical characterization of these polymers in the form of scanning electron micrographs (SEM), BET and Langmuir surface area measurements. Fourier transform infra red spectroscopy (FTIR) analysis, X-ray photoelectron spectroscopy (XPS) analysis, atomic composition measurement, sodium capacity determination and zeta potential measurements have been conducted to assess their performance as sorbents for trace toxic metal removal. Density functional theory (DFT) has been used to analyze the pore size distribution data. The adsorption of metal ions from aqueous solution on these sorbents has been studied in batch equilibrium experiments. The influence of pH on metal adsorption capacity has also been examined. The kinetic performance of these polymers has been assessed and the results have been analyzed by a pore diffusion model. The resins have been used in mini-columns to study the selectivity towards the desired metal ion. The desorption of metal ions has been studied using hydrochloric acid (1 M and 4 M), sulfuric acid (1 M and 4 M) and acidified thiourea. The present study confirms that these thiol based chelating resins are very effective for selective removal of trace heavy metals from water.

Saha, B.; Iglesias, M.; Cumming, I.W.; Streat, M.

2000-01-01

390

Multivalent chelators for spatially and temporally controlled protein functionalization.  

PubMed

Site-specific protein modification-e.g. for immobilization or labelling-is a key prerequisite for numerous bioanalytical applications. Although modification by use of short peptide tags is particularly attractive, efficient and bio-orthogonal systems are still lacking. Here, we review the application of multivalent chelators (MCH) for high-affinity yet reversible recognition of oligohistidine (His)-tagged proteins. MCH are based on multiple nitrilotriacetic acid (NTA) moieties grafted on to molecular scaffolds suitable for conjugation to surfaces, probes or other biomolecules. Reversible interaction with the His-tag is mediated via transition metal ions chelated by the NTA moieties. The small size and biochemical compatibility of these recognition units and the possibility of rapid dissociation of the interaction with His-tagged proteins despite sub-nanomolar binding affinity, enable distinct and versatile handling and modification of recombinant proteins. In this review, we briefly introduce the key principles and features of MCH-His-tag interactions and recapitulate the broad spectrum of bioanalytical applications with a focus on quantitative protein interaction analysis on micro or nano-patterned solid surfaces and specific protein labelling in living cells. PMID:24770786

You, Changjiang; Piehler, Jacob

2014-05-01

391

Chelating polymeric beads as potential therapeutics for Wilson's disease.  

PubMed

Wilson's disease is a genetic disorder caused by a malfunction of ATPase 7B that leads to high accumulation of copper in the organism and consequent toxic effects. We propose a gentle therapy to eliminate the excessive copper content with oral administration of insoluble non-resorbable polymer sorbents containing selective chelating groups for copper(II). Polymeric beads with the chelating agents triethylenetetramine, N,N-di(2-pyridylmethyl)amine, and 8-hydroxyquinoline (8HQB) were investigated. In a preliminary copper uptake experiment, we found that 8HQB significantly reduced copper uptake (using copper-64 as a radiotracer) after oral administration in Wistar rats. Furthermore, we measured organ radioactivity in rats to demonstrate that 8HQB radiolabelled with iodine-125 is not absorbed from the gastrointestinal tract after oral administration. Non-resorbability and the blockade of copper uptake were also confirmed with small animal imaging (PET/CT) in mice. In a long-term experiment with Wistar rats fed a diet containing the polymers, we have found that there were no signs of polymer toxicity and the addition of polymers to the diet led to a significant reduction in the copper contents in the kidneys, brains, and livers of the rats. We have shown that polymers containing specific ligands could potentially be novel therapeutics for Wilson's disease. PMID:24815561

Mattová, Jana; Pou?ková, Pavla; Ku?ka, Jan; Skodová, Michaela; Vetrík, Miroslav; St?pánek, Petr; Urbánek, Petr; Pet?ík, Miloš; Nový, Zbyn?k; Hrubý, Martin

2014-10-01

392

Iron chelation: a potential therapeutic strategy in oesophageal cancer  

PubMed Central

Raised intracellular iron has been identified as a potential aetiological factor in the development of several epithelial malignancies, including those of the gastrointestinal tract. The mechanism behind this increase is thought to include disorders of iron uptake and storage. Several iron chelators have been identified as potential anti-tumour agents, with much work undertaken to ascertain the exact mode of action. Despite this, there is little known about the role that these drugs play in the cellular iron metabolism of oesophageal cancer. Consequently, the present study looks to review the relationship of two clinically important iron-chelating agents, deferoxamine and deferasirox, on cellular iron uptake and storage in oesophageal squamous and adenocarcinoma. This provides important evidence for the debate about the role these agents have in the clinical management of such tumours. Linked Article This article is a commentary on Ford et al., pp. 1316–1328 of this issue. To view this paper visit http://dx.doi.org/10.1111/bph.12045

Keeler, BD; Brookes, MJ

2013-01-01

393

Functional characterization of the chloroplast ferric chelate oxidoreductase enzyme.  

PubMed

Iron (Fe) has an essential role in the biosynthesis of chlorophylls and redox cofactors, and thus chloroplast iron uptake is a process of special importance. The chloroplast ferric chelate oxidoreductase (cFRO) has a crucial role in this process but it is poorly characterized. To study the localization and mechanism of action of cFRO, sugar beet (Beta vulgaris cv Orbis) chloroplast envelope fractions were isolated by gradient ultracentrifugation, and their purity was tested by western blotting against different marker proteins. The ferric chelate reductase (FCR) activity of envelope fractions was studied in the presence of NAD(P)H (reductants) and FAD coenzymes. Reduction of Fe(III)-ethylenediaminetetraacetic acid was monitored spectrophotometrically by the Fe(II)-bathophenanthroline disulfonate complex formation. FCR activity, that is production of free Fe(II) for Fe uptake, showed biphasic saturation kinetics, and was clearly associated only to chloroplast inner envelope (cIE) vesicles. The reaction rate was > 2.5 times higher with NADPH than with NADH, which indicates the natural coenzyme preference of cFRO activity and its dependence on photosynthesis. FCR activity of cIE vesicles isolated from Fe-deficient plants also showed clear biphasic kinetics, where the KM of the low affinity component was elevated, and thus this component was down-regulated. PMID:24506824

Solti, Adám; Müller, Brigitta; Czech, Viktória; Sárvári, Éva; Fodor, Ferenc

2014-05-01

394

Chelators in the Treatment of Iron Accumulation in Parkinson's Disease  

PubMed Central

Iron is an essential element in the metabolism of all cells. Elevated levels of the metal have been found in the brains of patients of numerous neurodegenerative disorders, including Parkinson's disease (PD). The pathogenesis of PD is largely unknown, although it is thought through studies with experimental models that oxidative stress and dysfunction of brain iron homeostasis, usually a tightly regulated process, play significant roles in the death of dopaminergic neurons. Accumulation of iron is present at affected neurons and associated microglia in the substantia nigra of PD patients. This additional free-iron has the capacity to generate reactive oxygen species, promote the aggregation of ?-synuclein protein, and exacerbate or even cause neurodegeneration. There are various treatments aimed at reversing this pathologic increase in iron content, comprising both synthetic and natural iron chelators. These include established drugs, which have been used to treat other disorders related to iron accumulation. This paper will discuss how iron dysregulation occurs and the link between increased iron and oxidative stress in PD, including the mechanism by which these processes lead to cell death, before assessing the current pharmacotherapies aimed at restoring normal iron redox and new chelation strategies undergoing research.

Mounsey, Ross B.; Teismann, Peter

2012-01-01

395

Synthesis and coordination properties of chelating dithiophenolate ligands.  

PubMed

Chelating 3,3'-R(1)-5,5'-R(2)-2,2'-dithiobiphenyl ligands (R(1) = R(2) = Cl, 4a; R(1) = R(2) = (t)Bu, 4b; R(1) = allyl, R(2) = H, 4c) and the 2,2'-methylenedibenzenethiol ligand (4d) were synthesized from the corresponding diols (1a-1d) via a three-step procedure involving a Miyazaki-Newman-Kwart rearrangement. Zinc complexes and a tin complex (for 4c) have been prepared to explore their coordination potential, and the substitution pattern, as well as the chelate ring size, is shown to severely effect their ligating properties. Four of the complexes have been characterized crystallographically in the solid state, and the nuclearity of the zinc complexes in solution has been studied by diffusion-ordered NMR spectroscopy. Depending on the ligand, zinc complexes [(4)Zn(4,4'-(t)Bu-bipyridine)](n) (5a-d) are monomeric (n = 1; 4b, 4c), monomeric in solution and dimeric in the solid state (n = 1, 2; 4a), or dimeric overall (n = 2; 4d). The tin complex (4c)SnPh(2) (6c) was additionally synthesized to prove the coordinating abilities of the allyl substituted ligand 4c. PMID:19035679

Ballmann, Joachim; Fuchs, Michael G G; Dechert, Sebastian; John, Michael; Meyer, Franc

2009-01-01

396

Anti-tumour studies of metal chelates of synthetic curcuminoids.  

PubMed

Four synthetic curcuminoids, 1,7-bis(4-hydroxy-3-methoxyphenyl)-1, 6-heptadiene-3, 5-dione (curcumin1), 1,7-bis(piperonyl)-1,6-heptadiene-3, 5-dione (piperonyl curcumin), 1, 7-bis(2-hydroxy naphthyl)-1, 6-heptadiene-2, 5-dione (2-hydroxy naphthyl curcumin), 1,1-bis(phenyl)-1, 3, 8, 10- undecatetraene-5, 7-dione (cinnamyl curcumin) and their copper(II) complexes were investigated for their possible cytotoxic and antitumour activities. Copper chelates of synthetic curcuminoids showed enhanced antitumour activity. All the compounds were found to be cytotoxic to cultured L929 cells, concentration needed for 50% inhibition being around 10 microg/ml for curcuminoids and 1 microg/ml for their copper complexes. Copper complexes of curcuminoids with a hydroxy group on the ring such as 2-hydroxy naphthyl curcumin were found to be most active (1 microg/ml produced 60.45+/-2.1% cell death). Copper complex of cinnamyl curcumin which has an extended conjugation showed considerable activity in increasing the life span (ILS=78.6%) of ascites tumour bearing animals. Whereas complex of piperonyl curcumin was found to show least antitumour activity. Copper chelates of curcuminoids showed a significant reduction (p< .001) of solid tumour volume in mice. PMID:12148581

John, V D; Kuttan, G; Krishnankutty, K

2002-06-01

397

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

2012-08-21

398

Zn(II) Robson macrocycles as templates for chelating diphosphines.  

PubMed

Chelating diphosphines were constructed using dinuclear Zn(II) complexes of Robson macrocycles (Zn-RMCs) as templates. The assembly process is driven by the interaction between the metal centers (Lewis acids) with anionic and neutral Lewis base-functionalized monophosphines. The stability of the final structure depends on the geometry and the affinity of the functional groups of the ditopic phosphines and on the structure of the RMC. In the free ligand the ditopic phosphines coordinate at opposite faces of the pseudo-planar macrocycle as is shown in the molecular structure of several of the assemblies, according to X-ray diffraction. Pre-organization of the system by coordinating the phosphorus atoms to a transition metal center enforced coordination of the functional groups at the same face of the RMC. For several templated diphosphines cis-PtCl(2) complexes were identified by NMR. The in situ assembled diphosphines showed a chelating effect in the rhodium catalyzed hydroformylation of 1-octene. Combination of Zn-RMC 3 and phosphine A gave the highest l/b ratio (13) in acetonitrile. PMID:21874185

Ponsico, Sergio; Gulyas, Henrik; Martínez-Belmonte, Marta; Escudero-Adán, Eduardo C; Freixa, Zoraida; van Leeuwen, Piet W N M

2011-10-28

399

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

NASA Astrophysics Data System (ADS)

Experimental data on the formation of Widmanstätten/bainitic ferrite in ferrous alloys (i.e., the Widmanstätten 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 Widmanstätten plate occurs well above the T 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 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

1994-09-01

400

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 °C increased R1-dose sensitivity above that of gels stored at 5 °C. 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; Bäck, Sven Å. J.; Lepage, Martin; Simpson, John; Healy, Brendan; Baldock, Clive

2002-12-01

401

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

402

Comparison of Ferrous Calcium Silicate Slag and Calcium Ferrite Slag Interactions with Magnesia-Chrome Refractories  

NASA Astrophysics Data System (ADS)

The cost of maintaining and eventually replacing refractories as a result of slag attack is a significant cost component in the copper industry. Converting matte to blister copper takes place in reactors lined with direct-bonded magnesia-chrome refractories, and several continuous converting operations use calcium ferrite slag. Unfortunately, the low viscosity of calcium ferrite slag makes it aggressive toward the refractories. Ferrous calcium silicate (FCS) slag has been proposed as a replacement; however, the effect of this slag on magnesia-chrome refractories has not been studied. In this work, the interactions between FCS slag and magnesia-chrome refractory at 1573 K (1300 °C) with an oxygen partial pressure of 10-6 atm were studied and compared with that experienced with calcium ferrite slag under the same conditions. Both slags penetrated the pores in the refractory and caused compositional change in the chromite spinel intergranular bonding phase through cation interdiffusion, which resulted in cracking and debonding of periclase grains. It was observed that the refractory was penetrated much more deeply by calcium ferrite slag than FCS slag because of the higher surface tension and lower viscosity of calcium ferrite slag. As a result, the refractory was attacked less by FCS slag than it was by calcium ferrite slag. It is concluded that the use of FCS slag in continuous copper converting is likely to extend refractory life.

Kaur, R. R.; Swinbourne, D. R.; Wadsley, M. W.; Nexhip, C.

2011-06-01

403

Ferrous iron oxidation in moderately thermophilic acidophile Sulfobacillus sibiricus N1(T).  

PubMed

The iron-oxidizing system of a moderately thermophilic, extremely acidophilic, gram-positive mixotroph, Sulfobacillus sibiricus N1(T), was studied by spectroscopic, high-performance liquid chromatography and inhibitory analyses. Hemes B, A, and O were detected in membranes of S. sibiricus N1(T). It is proposed that the electron transport chain from Fe²(+) to O? is terminated by 2 physiological oxidases: aa?-type cytochrome, which dominates in the early-exponential phase of growth, and bo?-type cytochrome, whose role in iron oxidation becomes more prominent upon growth of the culture. Both oxidases were sensitive to cyanide and azide. Cytochrome aa? was more sensitive to cyanide and azide, with K(i) values of 4.1 and 2.5 µmol·L?¹, respectively, compared with K(i) values for cytochrome bo?, which were 9.5 µmol·L?¹ for cyanide and 7.0 µmol·L?¹ for azide. This is the first evidence for the participation of a bo?-type oxidase in ferrous iron oxidation. The respiratory chain of the mixotroph contains, in addition to the 2 terminal oxidases, a membrane-bound cytochrome b???. PMID:20962902

Dinarieva, Tatiana Y; Zhuravleva, Anna E; Pavlenko, Oksana A; Tsaplina, Iraida A; Netrusov, Alexander I

2010-10-01

404

Effect of ferrous sulfate fortification in germinated brown rice on seed iron concentration and bioavailability.  

PubMed

The present study evaluated the effectiveness of germination and iron fortification on iron concentration and bioavailability of brown rice. Iron fortification during germination process with 0.05-2 g/L ferrous sulfate increased the iron concentration in germinated brown rice from 1.1 to 15.6 times than those in raw brown rice. Based on the recommended dietary allowance of iron, maximum germination rate and ?-aminobutyric acid, we recommend the brown rice fortified with 0.25 g/L FeSO(4) as a suitable fortification level to use in germination process. Iron fortification during the germination process has a positive effect on iron concentration and bioavailability. A significant difference was observed among the cultivars in respect to the capacity for iron accumulation and bioavailability. Germination alone could improve in vitro iron solubility, but had no effect on iron bioavailability in Caco-2 cell, the additional fortification process should be combined to get high amount of bioavailable iron from the brown rice. PMID:23411330

Wei, Yanyan; Shohag, M J I; Ying, Feng; Yang, Xiaoe; Wu, Chunyong; Wang, Yuyan

2013-06-01

405

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

406

Lung cancer in a non-ferrous smelter: the role of cadmium.  

PubMed Central

Lung cancer mortality was examined in a cohort of 4393 men employed at a zinc-lead-cadmium smelter. There was an excess of lung cancer (overall SMR = 124.5, 95% confidence interval 107-144) which was particularly evident for those employed for more than 20 years. A statistically significant trend in SMRs with increasing duration of employment was apparent. Quantitative estimates of exposure to cadmium and ordinal rankings for lead, arsenic, zinc, sulphur dioxide, and dust were used to calculate cumulative exposures from job histories. Matched logistic regression was used to compare the cumulative exposures of cases of lung cancer to those of controls matched for date of birth and date of starting work and surviving at the time of death of the matched cases. The increasing risk of lung cancer associated with increasing duration of employment could not be accounted for by cadmium and did not appear to be restricted to any particular process or department. Although lung cancer mortality was associated with estimates of cumulative exposure to arsenic and to lead, it was not possible to determine whether the increased risk might be due to arsenic, lead, or to other contaminants in the smelter. These results are compared with findings from other non-ferrous smelters.

Ades, A E; Kazantzis, G

1988-01-01

407

A novel BF2-chelated azadipyrromethene-fullerene dyad: synthesis, electrochemistry and photodynamics.  

PubMed

The synthesis, structure, electrochemistry and photodynamics of a BF(2)-chelated azadipyrromethene-fullerene dyad are reported in comparison with BF(2)-chelated azadipyrromethene without fullerene. The attachment of fullerene resulted in efficient generation of the triplet excited state of the azadipyrromethene via photoinduced electron transfer. PMID:22083226

Amin, Anu N; El-Khouly, Mohamed E; Subbaiyan, Navaneetha K; Zandler, Melvin E; Fukuzumi, Shunichi; D'Souza, Francis

2012-01-01

408

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

409

Failure of Iron Chelators to Reduce Tumor Growth in Human Neuroblastoma Xenografts1  

Microsoft Academic Search

Neuroblastoma (NB) is a high risk tumor of childhood, and raised serum ferritin is an adverse prognostic factor. The hypothesis that iron chelation therapy impacts tumor status and patient prognosis through changes in iron metabolism has been systematically evaluated here in a xenograft model of human NB. One of two iron chelators was given in seven different regimens to nude

Ruth A. Selig; Cilinia Gramacho; Katy Sterling-Levis; Ian W. Fraser; Daya Naidoo

2002-01-01

410

Rapid anaerobic benzene oxidation with a variety of chelated Fe(III) forms  

Microsoft Academic Search

Techniques for stimulating aromatic hydrocarbon degradation in anaerobic portions of contaminated aquifers could be helpful in restoring polluted groundwater. Some studies have suggested that chelated Fe (III) might be an alternative electron acceptor that could be used instead of o2 for the bioremediation of aquifers contaminated with aromatic hydrocarbons. However, for this to be feasible an appropriate form of chelated

DEREK R. LOVLEY; JOAN C. WOODWARD; F. H. Chapelle

1996-01-01

411

Synthetic chelating agents and compounds exhibiting complexing properties in the aquatic environment  

Microsoft Academic Search

Synthetic chelating agents are utilized in many industrial applications because of their capability of binding and masking metal ions. This review of 20 main compounds includes chelating agents and other compounds, such as the organophosphonates or polycarboxylates, which, by binding metal ions, also exhibit some complexing properties. It aimed to gather data about production, use, toxicity, entry into the aquatic

Thomas P Knepper

2003-01-01

412

[FTIR spectroscopic study on synthesis and adsorption performance of amino phosphonic acid chelating fiber].  

PubMed

During the preparation of amino phosphoric chelating fiber, polypropylene grafted styrene, acetyl, amine series and amino phosphonic acid chelating fibers were certified by infrared spectrum, and the functionalization degree of raw fibers was studied. By the semi-qualitative method of infrared spectrum, the adsorption performance of indium and copper on amino phosphonic chelating fiber was also discussed. The results showed that (1) The peak at 1 116 cm(-1) was assigned to--P(ONa)2 in amino phosphonic acid chelating fiber. So the success of phosphorylation was verified. (2) During preparation, the phosphorylation effect of amino phosphonic acid chelating fiber could be reflected by the change of the peaks at 1 056 and 1 110 cm(-)1. (3) After adsorption of In3+ on amino phosphonic acid chelating fiber, the new forming N-In coordination key was absorbed strongly at the bands of 1 000-1 200 cm(-1) and at 1 107, 699 and 617 cm(-1). After adsorption Cu2+ on amino phosphonic acid chelating fiber two new strong and wide peaks were found at 1 110 and 618 cm(-1), respectively. (4) Through the area change of the bands at 1 200-900 and 600 cm(-1), the adsorption performance of indium and copper on amino phosphonic acid chelating fiber was compared. PMID:23427532

Feng, Chang-Gen; Sun, Yao-Ran; Li, Ming-Yu; Zeng, Qing-Xuan; Liang, Chun-Bo

2012-12-01

413

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

414

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; Gabbaï, François P

2009-02-17

415

Method for separating metal chelates from other materials based on solubilities in supercritical fluids  

DOEpatents

A method for separating a desired metal or metalloi from impurities using a supercritical extraction process based on solubility differences between the components, as well as the ability to vary the solvent power of the supercritical fluid, is described. The use of adduct-forming agents, such as phosphorous-containing ligands, to separate metal or metalloid chelates in such processes is further disclosed. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is selected from the group consisting of .beta.-diketones; phosphine oxides, such as trialkylphosphine oxides, triarylphosphine oxides and alkylarylphosphine oxides; phosphinic acids; carboxylic acids; phosphates, such as trialkylphosphates, triarylphosphates and alkylarylphosphates; crown ethers; dithiocarbamates; phosphine sulfides; phosphorothioic acids; thiophosphinic acids; halogenated analogs of these chelating agents; and mixtures of these chelating agents. In especially preferred embodiments, at least one of the chelating agents is fluorinated.

Wai, Chien M. (Moscow, ID); Smart, Neil G. (Workington, GB); Phelps, Cindy (Moscow, ID)

2001-01-01

416

Fourier transform infrared studies on the dissociation behavior of metal-chelating polyelectrolyte brushes.  

PubMed

The dissociation behavior of surface-grafted polyelectrolytes is of interest for the development of stimuli-responsive materials. Metal-chelating polyelectrolyte brushes containing acrylic acid (PAA) or hydroxamic acid (PHA) chelating moieties were grafted from the surface of polypropylene (PP). Fourier transform infrared (FTIR) spectroscopy was used to determine the effective bulk pKa of the polyelectrolyte brushes (pKa(bulk)) and to characterize metal-chelating behavior. The pKa(bulk) values of PP-g-PAA and PP-g-PHA were 6.45 and 9.65, respectively. Both PP-g-PAA and PP-g-PHA exhibited bridging bidentate and chelating bidentate iron chelation complexes. This is the first reported determination of the pK(a,bulk) of surface-grafted poly(hydroxamic) acid. PMID:24697588

Roman, Maxine J; Decker, Eric A; Goddard, Julie M

2014-04-23

417

Toward resolving the unsettled role of iron chelation therapy in myelodysplastic syndromes.  

PubMed

Transfusion dependent low risk myelodysplastic syndromes (MDS) patients, eventually develop iron overload. Iron toxicity, via oxidative stress, can damage cellular components and impact organ function. In thalassemia major patients, iron chelation therapy lowered iron levels with recovery of cardiac and liver functions and significant improvement in survival. Several noncontrolled studies show inferior survival in MDS patients with iron overload, including an increase in transplant-related mortality and infection risk while iron chelation appears to improve survival in both lower risk MDS patients and in stem cell transplant settings. Collated data are presented on the pathophysiological impact of iron overload; measuring techniques and chelating agents' therapy positive impact on hematological status and overall survival are discussed. Although suggested by retrospective analyses, the lack of clear prospective data of the beneficial effects of iron chelation on morbidity and survival, the role of iron chelation therapy in MDS patients remains controversial. PMID:24641787

Merkel, Drorit G; Nagler, Arnon

2014-07-01

418

Combined chelation of lead (II) by deferasirox and deferiprone in rats as biological model.  

PubMed

In order to investigate the capability of two chelators deferasirox (DFX or ICL670) and deferiprone (L1) in removing lead from the body, the present research was performed. Two does levels of 40 and 80 mg/kg body weight of lead (II) chloride was given to rats as biological model for 45 days. After 45 days, some toxicity symptoms were observed in rats such as loss of hair and weight, appearance of red dots around eyes, weakness and irritability. After lead application, chelation therapy with DFX and L1 as mono and combined (DFX, L1 and DFX + L1) was done for 10 days. After chelation therapy, lead level in different tissues reduced. The combined chelation therapy results showed that these chelators are able to remove lead from the body and toxicity symptoms decreased. The combined therapy results (DFX + L1) show higher efficacy and lower toxicity compared to single therapies. PMID:24309925

Balooch, F Dahooee; Fatemi, S J; Iranmanesh, M

2014-02-01

419

Brazilian Thalassemia Association protocol for iron chelation therapy in patients under regular transfusion  

PubMed Central

In the absence of an iron chelating agent, patients with beta-thalassemia on regular transfusions present complications of transfusion-related iron overload. Without iron chelation therapy, heart disease is the major cause of death; however, hepatic and endocrine complications also occur. Currently there are three iron chelating agents available for continuous use in patients with thalassemia on regular transfusions (desferrioxamine, deferiprone, and deferasirox) providing good results in reducing cardiac, hepatic and endocrine toxicity. These practice guidelines, prepared by the Scientific Committee of Associação Brasileira de Thalassemia (ABRASTA), presents a review of the literature regarding iron overload assessment (by imaging and laboratory exams) and the role of T2* magnetic resonance imaging (MRI) to control iron overload and iron chelation therapy, with evidence-based recommendations for each clinical situation. Based on this review, the authors propose an iron chelation protocol for patients with thalassemia under regular transfusions.

Verissimo, Monica Pinheiro de Almeida; Loggetto, Sandra Regina; Fabron Junior, Antonio; Baldanzi, Giorgio Roberto; Hamerschlak, Nelson; Fernandes, Juliano Lara; Araujo, Aderson da Silva; Lobo, Clarisse Lopes de Castro; Fertrin, Kleber Yotsumoto; Berdoukas, Vasilios Antonios; Galanello, Renzo

2013-01-01

420

Chelation Shows Benefit in Diabetic Patients After Heart Attack, But Findings Do Not Support Its Routine Use  

MedlinePLUS

... to Assess Chelation Therapy (TACT) suggest that the EDTA-based chelation treatments produced a marked reduction in ... therapy with disodium ethylene diamine tetra-acetic acid (EDTA) has a decades-long history as a treatment ...

421

Reciprocal Allosteric Modulation of Carbon Monoxide and Warfarin Binding to Ferrous Human Serum Heme-Albumin  

PubMed Central

Human serum albumin (HSA), the most abundant protein in human plasma, could be considered as a prototypic monomeric allosteric protein, since the ligand-dependent conformational adaptability of HSA spreads beyond the immediate proximity of the binding site(s). As a matter of fact, HSA is a major transport protein in the bloodstream and the regulation of the functional allosteric interrelationships between the different binding sites represents a fundamental information for the knowledge of its transport function. Here, kinetics and thermodynamics of the allosteric modulation: (i) of carbon monoxide (CO) binding to ferrous human serum heme-albumin (HSA-heme-Fe(II)) by warfarin (WF), and (ii) of WF binding to HSA-heme-Fe(II) by CO are reported. All data were obtained at pH 7.0 and 25°C. Kinetics of CO and WF binding to the FA1 and FA7 sites of HSA-heme-Fe(II), respectively, follows a multi-exponential behavior (with the same relative percentage for the two ligands). This can be accounted for by the existence of multiple conformations and/or heme-protein axial coordination forms of HSA-heme-Fe(II). The HSA-heme-Fe(II) populations have been characterized by resonance Raman spectroscopy, indicating the coexistence of different species characterized by four-, five- and six-coordination of the heme-Fe atom. As a whole, these results suggest that: (i) upon CO binding a conformational change of HSA-heme-Fe(II) takes place (likely reflecting the displacement of an endogenous ligand by CO), and (ii) CO and/or WF binding brings about a ligand-dependent variation of the HSA-heme-Fe(II) population distribution of the various coordinating species. The detailed thermodynamic and kinetic analysis here reported allows a quantitative description of the mutual allosteric effect of CO and WF binding to HSA-heme-Fe(II).

Bocedi, Alessio; De Sanctis, Giampiero; Ciaccio, Chiara; Tundo, Grazia R.; Di Masi, Alessandra; Fanali, Gabriella; Nicoletti, Francesco P.; Fasano, Mauro; Smulevich, Giulietta; Ascenzi, Paolo; Coletta, Massimo

2013-01-01

422

5-Aminolevulinic acid combined with ferrous iron enhances the expression of heme oxygenase-1.  

PubMed

5-Aminolevulinic acid (5-ALA) is the naturally occurring metabolic precursor of heme. Heme negatively regulates the Maf recognition element (MARE) binding- and repressing-activity of the Bach1 transcription factor through its direct binding to Bach1. Heme oxygenase (HO)-1 is an inducible enzyme that catalyzes the rate-limiting step in the oxidative degradation of heme to free iron, biliverdin and carbon monoxide. These metabolites of heme protect against apoptosis, inflammation and oxidative stress. Monocytes and macrophages play a critical role in the initiation, maintenance and resolution of inflammation. Therefore, the regulation of inflammation in macrophages is an important target under various pathophysiological conditions. In order to address the question of what is responsible for the anti-inflammatory effects of 5-ALA, the induction of HO-1 expression by 5-ALA and sodium ferrous citrate (SFC) was examined in macrophage cell line (RAW264 cells). HO-1 expression induced by 5-ALA combined with SFC (5-ALA/SFC) was partially inhibited by MEK/ERK and p38 MAPK inhibitor. The NF-E2-related factor 2 (Nrf2) was activated and translocated from the cytosol to the nucleus in response to 5-ALA/SFC. Nrf2-specific siRNA reduced the HO-1 expression. In addition, 5-ALA/SFC increased the intracellular levels of heme in cells. The increased heme indicated that the inactivation of Bach1 by heme supports the upregulation of HO-1 expression. Taken together, our data suggest that the exposure of 5-ALA/SFC to RAW264 cells enhances the HO-1 expression via MAPK activation along with the negative regulation of Bach1. PMID:24530569

Nishio, Yoshiaki; Fujino, Masayuki; Zhao, Mingyi; Ishii, Takuya; Ishizuka, Masahiro; Ito, Hidenori; Takahashi, Kiwamu; Abe, Fuminori; Nakajima, Motowo; Tanaka, Tohru; Taketani, Shigeru; Nagahara, Yukitoshi; Li, Xiao-Kang

2014-04-01

423

Computational methods for intramolecular electron transfer in a ferrous-ferric iron complex  

SciTech Connect

The limitations of common theoretical and molecular computational approaches for predicting electron transfer quantities were assessed, using an archetypal bridged ferrous-ferric electron transfer system in aqueous solution. The basis set effect on the magnitude of the electronic coupling matrix element computed using the quasi-diabatic method was carefully examined, and it was found that the error related to a poor basis set could exceed the thermal energy at room temperature. A range of approaches to determining the external (solvent) reorganization energy were also investigated. Significant improvements from the Marcus continuum model can be obtained by including dipolar Born-Kirkwood-Onsager correction. In this regard we also found that Klamt’s Conductor-Like Screening Model (COSMO) yields estimations of the external reorganization energy similar to those obtained with explicit solvent molecular dynamics simulations, if the fast-frequency modes are neglected, which makes it an attractive alternative to laborious umbrella sampling simulations. As expected, dielectric saturation observed in the first solvation shell decreases the curvature of the potential energy surface, but it nonetheless remains a quadratic function of the reaction coordinate. The linearity of solvent response to the charge redistribution was assessed by analyzing the energy gap autocorrelation function as well as the solvent density and dipole moment fluctuations. Molecular dynamics was also used to evaluate the sign and magnitude of the solvent reorganization entropy, to determine its effect on the predicted electron transfer rate. Finally, we present a simple way of estimating the vibration frequency along the reaction coordinate, which also enables prediction of the mass dependent isotopic signature of electron-transfer reactions.

Zarzycki, Piotr P.; Kerisit, Sebastien N.; Rosso, Kevin M.

2011-07-29

424

Degradation of bisphenol A in aqueous solution by persulfate activated with ferrous ion.  

PubMed

Degradation of bisphenol A (BPA) in aqueous solution was studied with high-efficiency sulfate radical (SO4(-·)), which was generated by the activation of persulfate (S2O8(2-)) with ferrous ion (Fe(2+)). S2O8(2-) was activated by Fe(2+) to produce SO4(-·), and iron powder (Fe(0)) was used as a slow-releasing source of dissolved Fe(2+). The major oxidation products of BPA were determined by liquid chromatography-mass spectrometer. The mineralization efficiency of BPA was monitored by total organic carbon (TOC) analyzer. BPA removal efficiency was improved by the increase of initial S2O8(2-) or Fe(2+) concentrations and then decreased with excess Fe(2+) concentration. The adding mode of Fe(2+) had significant impact on BPA degradation and mineralization. BPA removal rates increased from 49 to 97% with sequential addition of Fe(2+), while complete degradation was observed with continuous diffusion of Fe(2+), and the latter achieved higher TOC removal rate. When Fe(0) was employed as a slow-releasing source of dissolved Fe(2+), 100% of BPA degradation efficiency was achieved, and the highest removal rate of TOC (85%) was obtained within 2 h. In the Fe(0)-S2O8(2-) system, Fe(0) as the activator of S2O8(2-) could offer sustainable oxidation for BPA, and higher TOC removal rate was achieved. It was proved that Fe(0)-S2O8(2-) system has perspective for future works. PMID:23322415

Jiang, Xiaoxuan; Wu, Yanlin; Wang, Peng; Li, Hongjing; Dong, Wenbo

2013-07-01

425

Purification of carboxypeptidase B by zinc chelate chromatography.  

PubMed

A method is described to purify pancreatic carboxypeptidases B (CPB), removing contaminating endoproteinases that interfere with use of CPB for carboxy-terminal analysis or modification of proteins. The separation uses zinc chelate chromatography and is based on the property that CPB has higher affinity for immobilized zinc ions than do serine proteinases such as trypsin and chymotrypsin, which are abundant endoproteolytic activities in pancreas. CPB preparations are loaded onto a column of iminodiacetic acid-Sepharose that has been saturated with ZnCl2. A step gradient with buffers of decreasing pH is used to elute bound proteins. CPB elutes at a lower pH than do the serine proteinases. PMID:2662173

Hortin, G L; Gibson, B L

1989-01-01

426

Antioxidative activity of a zinc-chelating substance in coffee.  

PubMed

Coffee brew contains a brownish zinc-chelating polymer designated ApV. ApV was prepared from the precipitate formed in a solution of instant coffee by adding ZnCl(2) and purified using ion-exchange and cellulose column chromatographies. The antioxidative activities of ApV and related compounds were evaluated in this study. The free-radical scavenging activity of ApV estimated by ABTS assay was at a similar level to that of instant coffee, while the O(2)(-) scavenging activity of ApV, which is superoxide dismutase-like activity, was lower than that of instant coffee. The hydroxyl-radical scavenging activity of ApV was higher than that of instant coffee, and the auto-oxidation of linoleic acid was more strongly inhibited by ApV than by caffeic acid. PMID:15564670

Wen, Xu; Takenaka, Makiko; Murata, Masatsune; Homma, Seiichi

2004-11-01

427

Mechanistic studies of chelating resins using two-phase potentiometry.  

PubMed

The elucidation of metal ion binding mechanisms with chelating resins by treating the resin as a collection of monomeric units is an established approach. In this paper, this approach is used to treat data obtained from two-phase potentiometric titrations by the programme ESTA. Apparent protonation and formation constants could be calculated. From these, species distribution plots could be obtained. These, in turn, allowed the calculation of the more familiar distribution ratios. The method was tested on Fe(III) and Nd(III) bonding with the iminodiacetate functionalized resin, Chelex 100; and Ca(II) bonding to the aminomethylphosphonate functionalized resin, Purolite S940. Good results were obtained indicating the applicability of this method. Comparisons with the literature are made. PMID:18965994

Jarvis, N V; Wagener, J M

1994-05-01

428

Photolabile chelators for the rapid photorelease of divalent cations.  

PubMed Central

The properties of a recently synthesized photolabile chelator for divalent cations are described, the affinity of which for Ca2+ changes by some 5 orders of magnitude on illumination. The compound 1-(2-nitro-4,5-dimethoxyphenyl)-N,N,N',N'-tetrakis[(oxycarbonyl)me thyl]-1,2-ethanediamine (DM-nitrophen) binds Ca2+ (Kd approximately 5.0 x 10(-9) M) and Mg2+ (Kd approximately 2.5 x 10(-6) M) with relatively high affinities. On exposure of the DM-nitrophen-Ca2+ complex to UV light in the 350-nm range, the chelator is cleaved yielding iminodiacetic products with a much lower affinity for Ca (Kd approximately 3 x 10(-3) M) and the free [Ca2+] increases. The quantum yield for Ca2+ release is 0.18. In experiments with chemically skinned skeletal muscle fibers, a fully relaxed fiber equilibrated with DM-nitrophen-Ca2+ complex produced maximal contraction after a single flash from a frequency-doubled ruby laser (347 nm). Half-maximal tension was achieved in approximately 40 ms, some 5 times faster than that obtained after a rapid solution change from a Ca2+-free to a Ca2+-containing solution. In experiments with resealed human erythrocyte ghosts, irradiation of ghosts containing the DM-nitrophen-Ca2+ complex activates a Ca2+-dependent K+ efflux pathway, which is not observed in the absence of illumination. DM-nitrophen is sufficiently stable and photolabile to be used as a caged Ca (or caged Mg) for the rapid photoinitiation of divalent cation-dependent processes over a wide concentration range with a significant increase in temporal resolution over conventional mixing methods.

Kaplan, J H; Ellis-Davies, G C

1988-01-01

429

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

430

Anomalies in solution behavior of an alkyl aminopolycarboxylic chelating surfactant.  

PubMed

The solution behavior of a DTPA (diethylenetriamine pentaacetic acid)-based chelating surfactant, 4-C12-DTPA, has been studied by tensiometry and NMR diffusometry. In the absence of metal ions, the eight donor atoms in the headgroup are titrating, and the charge of the headgroup can thus be tuned by altering the pH. 4-C12-DTPA changes from cationic at very low pH, over a number of zwitterionic species as the pH is increased, and eventually becomes anionic at high pH. Around the isoelectric point, the chelating surfactant precipitated. The solution properties, studied above the solubility gap, were found strongly pH dependent. When increasing the amount of negative charges in the headgroup, by increasing the pH, the adsorption efficiency was reduced and the cmc was increased. An optimum in surface tension reduction was found at pH 5, due to a proper balance between protonated and dissociated groups. Anomalies between surface tension measurements and NMR diffusometry in determination of cmc revealed a more complex relation between surface tension, surface coverage, and cmc than usually considered, which is not in line with the common interpretation of the Gibbs adsorption equation. At some of the investigated pH levels, measurements of bulk pH could confirm the location of cmc, due to the increased protonation of micelles compared to monomers in solution. The adsorption of monomers to the air-water interface showed unusually slow time dependence, evident from decreasing surface tension for several hours. This is explained by rearrangements of the large head groups to reduce the headgroup area and increase the packing parameter. PMID:24111734

Svanedal, Ida; Persson, Gerd; Norgren, Magnus; Edlund, Håkan

2013-11-12

431

Protein fractionation using fast flow immobilized metal chelate affinity membranes.  

PubMed

A new group-specific affinity membrane using metal chelates as ligands and inorganic glass hollow fiber microfiltration membranes as support matrices is developed and tested. The study focused on developing the optimum activation and coupling procedures to bind the chelating agent (iminodiacetic acid, IDA) to the surface of the microporous glass hollow fiber membrane and testing the resultant affinity membrane. Starting with three different glass surfaces, five modification reactions were evaluated. All the modified "active surfaces" were first tested for their protein adsorptive properties in batch mode with suspended microporous glass grains using model proteins with known binding characteristics with Cu-IDA systems. The metal loading capacities of the surfaces exhibiting favorable fractionation were then measured by atomic absorption spectroscopy.The results were compared with the results obtained with a commercial material used in immobilized metal affinity column chromatography. The protein binding characteristics of the hollow fiber affinity membranes were also evaluated under conditions of convective flow. This was performed by flowing single solute protein solutions through the microporous membrane at different flow rates. These results were then used to estimate the optimum loading and elution times for the process. A mathematical model incorporating radial diffusion was solved using a finite difference discretization method. Comparison between model predictions and experimental results was performed for four different proteins at one flow rate. These results suggested that the kinetics of adsorption was concentration dependent. Finally, the hollow fiber affinity membranes were challenged with two component mixtures to test their ability to fractionate mixed protein solutions. Efficient separation and good purity were obtained.The results presented here represent the development of a new fast flow affinity membrane process-immobilized metal affinity membranes (IMAM). (c) 1994 John Wiley & Sons, Inc. PMID:18613307

Serafica, G C; Belfort, G; Pimbley, J

1994-01-01

432

Copper chelator ATN-224 inhibits endothelial function by multiple mechanisms.  

PubMed

Copper is required for the proliferation of endothelial cells and copper-lowering therapy reduces tumour growth in animal models. It has been reported that ATN-224, a novel copper chelator, potently inhibits the activity of the copper-dependent enzyme superoxide dismutase 1 (SOD1) in endothelial cells. We performed microarray analysis of gene expression in endothelial cells exposed to ATN-224 which revealed upregulation of stress response genes including heme-oxygenase 1 (HO-1) and differential regulation of several genes previously implicated in angiogenesis including CXCR4, ANGP2, PGES2, RHAMM, ITB4 and AQP1 (p<0.01). These changes were confirmed on qPCR. Treatment of HUVEC with ATN-224 caused increased superoxide levels, phospho-ERK signalling, nuclear NRF1 expression, HO-1 expression and induction of the anti-apoptotic proteins P21, BCL2 and BCLXL. There was also nuclear translocation of SOD1. SOD1 RNA interference replicated the effects of ATN-224 on endothelial cell function but did not cause upregulation of HO-1 or PGES2, suggesting additional mechanisms of action of ATN-224. Downregulation of AQP1, which has been shown to have a role in angiogenesis, was seen with both ATN-224 and SOD1 siRNA. AQP1 expression could be rescued after ATN-224 by added copper. RNA interference to AQP1 inhibited endothelial proliferation and migration, confirming the role of AQP1 in endothelial cell function. Therefore regulation of AQP1 may represent an important action of copper chelation therapy. PMID:19323979

Lowndes, Sarah A; Sheldon, Helen V; Cai, Shijie; Taylor, Jennifer M; Harris, Adrian L

2009-05-01

433

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.

434

Bifunctional chelates of Rh-105 and Au-199 as potential radiotherapeutic agents. (Progress report, June 1, 1989-May 31, 1990).  

National Technical Information Service (NTIS)

Since last year we have: continued the synthesis of pentadentate bifunctional chelating agents based on diethylene triamine; studied the chelation Rh-105, Au-198 (as model for Au-199) and Tc-99m with these agents as well as chelation of Pd-109, Cu-67, In-...

D. E. Troutner E. O. Schlemper

1990-01-01

435

Function of the iron-binding chelator produced by Coriolus versicolor in lignin biodegradation.  

PubMed

An ultrafiltered low-molecular-weight preparation of chelating compounds was isolated from a wood-containing culture of the white-rot basidiomycete Coriolus versicolor. This preparation could chelate Fe3+ and reduce Fe3+ to Fe2+, demonstrating that the substance may serve as a ferric chelator, oxygen-reducing agent, and redox-cycling molecule, which would include functioning as the electron transport carrier in Fenton reaction. Lignin was treated with the iron-binding chelator and the changes in structure were investigated by 1H-NMR, 13C-NMR, difference spectrum caused by ionization under alkaline conditions and nitrobenzene oxidation. The results indicated that the iron-binding chelator could destroy the beta-O-4 bonds in etherified lignin units and insert phenolic hydroxyl groups. The low-molecular-weight chelator secreted by C. versicolor resulted in new phenolic substructures in the lignin polymer, making it susceptible to attack by laccase or manganese peroxidase. Thus, the synergic action of the iron-binding chelator and the lignocellulolytic enzymes made the substrate more accessible to degradation. PMID:18246309

Wang, Lu; Yan, WenChao; Chen, JiaChuan; Huang, Feng; Gao, PeiJi

2008-03-01

436

Statistical Analysis of Metal Chelating Activity of Centella asiatica and Erythroxylum cuneatum Using Response Surface Methodology  

PubMed Central

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°C, 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°C, 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.

Mohd Salim, R. J.; Adenan, M. I.; Amid, A.; Jauri, M. H.; Sued, A. S.

2013-01-01

437

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

438

Near-infrared spectra of ferrous mineral mixtures and methods for their identification in planetary surface spectra  

NASA Astrophysics Data System (ADS)

Iron-bearing minerals are a major component of planetary surfaces, and many can be identified by their characteristic absorption bands in the near-infrared (NIR). Here we present laboratory NIR spectra of a wide range of common Fe-bearing minerals (e.g., olivines, pyroxenes), glasses, and mineral/glass mixtures. We then use this suite of spectra to evaluate the effects of mixtures on mineral detection methods, including olivine and pyroxene spectral indices developed for the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) onboard Mars Reconnaissance Orbiter. We find that although these indices can be compromised by minerals with atypical compositions, mineral mixtures, and the presence of other ferrous minerals, these issues can generally be mitigated by visual inspection of the spectra. However, a special case occurs when the mineral or mixture in question is spectrally indistinguishable from a more common mineral. In particular, we show that spectra of high-calcium pyroxene mixed with Fe-bearing glass can be virtually indistinguishable from common Fe-bearing olivine compositions. This effect, combined with the fact that Fe-bearing glass is generally much more difficult to detect than other ferrous minerals, may be causing glass occurrences on planetary surfaces to be underreported. In support of this hypothesis, we use Mars Express OMEGA observations to show that previous olivine detections in the north polar sand sea on Mars are actually more consistent with local mixing of glass and pyroxene. To address these issues, we present an alternative ferrous mineral identification method based on the position and shape of the 1 and 2 ?m iron absorption bands, which are sensitive to mineralogy, composition, and mineral mixtures in planetary surface spectra, including glass and mixtures with glass. Using Chandrayaan-1 Moon Mineralogy Mapper (M3) observations of Aristarchus Crater on the Moon, we show that these band parameters can reveal subtle spectral variations and can produce mineralogical maps at an exceptional level of detail.

Horgan, Briony H. N.; Cloutis, Edward A.; Mann, Paul; Bell, James F.

2014-05-01

439

O{sub 2}-mediated oxidation of ferrous nitrosylated human serum heme-albumin is limited by nitrogen monoxide dissociation  

SciTech Connect

Research highlights: {yields} Human serum heme-albumin displays globin-like properties. {yields} O{sub 2}-mediated oxidation of ferrous nitrosylated human serum heme-albumin. {yields} Allosteric modulation of human serum heme-albumin reactivity. {yields} Rifampicin is an allosteric effector of human serum heme-albumin. {yields} Human serum heme-albumin is a ROS and NOS scavenger. -- Abstract: Human serum heme-albumin (HSA-heme-Fe) displays globin-like properties. Here, kinetics of O{sub 2}-mediated oxidation of ferrous nitrosylated HSA-heme-Fe (HSA-heme-Fe(II)-NO) is reported. Values of the first-order rate constants for O{sub 2}-mediated oxidation of HSA-heme-Fe(II)-NO (i.e., for ferric HSA-heme-Fe formation) and for NO dissociation from HSA-heme-Fe(II)-NO (i.e., for NO replacement by CO) are k = 9.8 x 10{sup -5} and 8.3 x 10{sup -4} s{sup -1}, and h = 1.3 x 10{sup -4} and 8.5 x 10{sup -4} s{sup -1}, in the absence and presence of rifampicin, respectively, at pH = 7.0 and T = 20.0 {sup o}C. The coincidence of values of k and h indicates that NO dissociation represents the rate limiting step of O{sub 2}-mediated oxidation of HSA-heme-Fe(II)-NO. Mixing HSA-heme-Fe(II)-NO with O{sub 2} does not lead to the formation of the transient adduct(s), but leads to the final ferric HSA-heme-Fe derivative. These results reflect the fast O{sub 2}-mediated oxidation of ferrous HSA-heme-Fe and highlight the role of drugs in modulating allosterically the heme-Fe-atom reactivity.

Ascenzi, Paolo, E-mail: ascenzi@uniroma3.it [Interdepartmental Laboratory of Electron Microscopy, University Roma Tre, Via della Vasca Navale 79, I-00146 Roma (Italy) [Interdepartmental Laboratory of Electron Microscopy, University Roma Tre, Via della Vasca Navale 79, I-00146 Roma (Italy); National Institute for Infectious Diseases I.R.C.C.S. 'Lazzaro Spallanzani', Via Portuense 292, I-00149 Roma (Italy); Gullotta, Francesca; Gioia, Magda; Coletta, Massimo [Department of Experimental Medicine and Biochemical Sciences, University of Roma 'Tor Vergata', Via Montpellier 1, I-00133 Roma (Italy) [Department of Experimental Medicine and Biochemical Sciences, University of Roma 'Tor Vergata', Via Montpellier 1, I-00133 Roma (Italy); Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems, Piazza Umberto I 1, I-87100 Bari (Italy); Fasano, Mauro [Department of Structural and Functional Biology, and Center of Neuroscience, University of Insubria, Via Alberto da Giussano 12a, I-21052 Busto Arsizio, VA (Italy)] [Department of Structural and Functional Biology, and Center of Neuroscience, University of Insubria, Via Alberto da Giussano 12a, I-21052 Busto Arsizio, VA (Italy)

2011-03-04

440

N-Acetylcysteine Protects Rats with Chronic Renal Failure from Gadolinium-Chelate Nephrotoxicity  

PubMed Central

The aim of this study was to evaluate the effect of Gd-chelate on renal function, iron parameters and oxidative stress in rats with CRF and a possible protective effect of the antioxidant N-Acetylcysteine (NAC). Male Wistar rats were submitted to 5/6 nephrectomy (Nx) to induced CRF. An ionic - cyclic Gd (Gadoterate Meglumine) was administrated (1.5 mM/KgBW, intravenously) 21 days after Nx. Clearance studies were performed in 4 groups of anesthetized animals 48 hours following Gd- chelate administration: 1? Nx (n?=?7); 2? Nx+NAC (n?=?6); 3? Nx+Gd (n?=?7); 4?Nx+NAC+Gd (4.8 g/L in drinking water), initiated 2 days before Gd-chelate administration and maintained during 4 days (n?=?6). This group was compared with a control. We measured glomerular filtration rate, GFR (inulin clearance, ml/min/kg BW), proteinuria (mg/24 hs), serum iron (µg/dL); serum ferritin (ng/mL); transferrin saturation (%), TIBC (µg/dL) and TBARS (nmles/ml). Normal rats treated with the same dose of Gd-chelate presented similar GFR and proteinuria when compared with normal controls, indicating that at this dose Gd-chelate is not nephrotoxic to normal rats. Gd-chelate administration to Nx-rats results in a decrease of GFR and increased proteinuria associated with a decrease in TIBC, elevation of ferritin serum levels, transferrin oversaturation and plasmatic TBARS compared with Nx-rats. The prophylactic treatment with NAC reversed the decrease in GFR and the increase in proteinuria and all alterations in iron parameters and TBARS induced by Gd-chelate. NAC administration to Nx rat did not modify the inulin clearance and iron kinetics, indicating that the ameliorating effect of NAC was specific to Gd-chelate. These results suggest that NAC can prevent Gd-chelate nephrotoxicity in patients with chronic renal failure.

Pereira, Leonardo Victor Barbosa; Shimizu, Maria Heloisa Massola; Rodrigues, Lina Paola Miranda Ruiz; Leite, Claudia Costa; Andrade, Lucia; Seguro, Antonio Carlos

2012-01-01

441

Increase in Fe3+/Fe2+ ratio and iron-induced oxidative stress in Eales disease and presence of ferrous iron in circulating transferrin.  

PubMed

Eales disease was shown to be associated with oxidant stress and weak antioxidant defense. Total iron, ferrous iron, thiobarbituric acid reactive substances (TBARS), and ceruloplasmin were estimated in the blood samples of patients with inflammation, perivasculitis, and venous insufficiency. Levels of ferric iron were determined from the difference in those of total iron and ferrous iron. All biochemical parameters were estimated in age and sex-matched controls. Fe3+/Fe2+ ratio was greater in patients with Eales disease than in normal controls. Similar increase in TBARS and ceruloplasmin levels were noted. The patients were treated with prednisone and vitamins E and C, then Fe3+/Fe2+ ratios and TBARS decreased progressively; the active state of the disease was reduced to 16%. So Fe3+/Fe2+ ratio in addition to TBARS levels could be considered an index of the active state of the disease. Circulating transferrin in blood did contain ferrous iron. Binding of ferrous iron to transferrin was confirmed by estimating iron-binding capacity using ferrous ammonium sulphate. PMID:17852192

Selvi, Radhakrishnan; Angayarkanni, Narayanasamy; Bharathselvi, Muthuvel; Sivaramakrishna, Ramakrishnan; Anisha, Thomas; Jyotirmoy, Biswas; Vasanthi, Badrinath

2007-01-01

442