These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
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. PMID:25023784

2014-01-01

2

Preparation of ferrous chelate of hairtail (Trichiurus haumela) protein hydrolysate (Fe(II)-HPH) and its antibacterial activity  

NASA Astrophysics Data System (ADS)

The preparation of a ferrous chelate of hairtail (Trichiurus haumela) protein hydrolysate (Fe(II)-HPH) and its antibacterial activity were studied. The optimal conditions of hydrolysis by papain and ferrous chelation were obtained by single-factor experiments and orthogonal test, with the antibacterial activities as the index. In addition, the antibacterial activity of Fe(II)-HPH was evaluated using the Plackett-Burman design. The orthogonal test results showed that Fe(II)-HPH had an antibacterial activity of 98.3% under a temperature of 40 °C at pH 6.5 for an enzymolysis duration of eight hours in the presence of 20,000 U/g of enzyme. The Plackett-Burman design analysis showed that the three most significant factors (P < 0.05) influencing the antibacterial activity of Fe(II)-HPH were pH, the concentration (mg/mL), and presence of magnesium sulfate.

Lin, Huimin; Zhang, Bin; Yu, Tian; Deng, Shanggui

3

Comparative Study of Gastrointestinal Tract and Liver Toxicity of Ferrous Sulfate, Iron Amino Chelate and Iron Polymaltose Complex in Normal Rats  

Microsoft Academic Search

Iron deficiency is a common worldwide problem leading to several morbidities including anemia. Although oral iron is the first choice in iron deficiency therapy, it may produce gastrointestinal (GI) and liver disorders. The aim of our study was to evaluate: (1) acute toxicity (LD50) in different oral iron compounds such as ferrous sulfate (FS), iron amino chelate (AC) and iron

Jorge E. Toblli; Gabriel Cao; Leda Olivieri; Margarita Angerosa

2008-01-01

4

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

Microsoft Academic Search

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

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

2004-01-01

5

Mössbauer Spectroscopy of Iron Containing Vitamins and Dietary Supplements  

NASA Astrophysics Data System (ADS)

Mössbauer spectroscopy was used to study various industrial samples of vitamins containing ferrous fumarate and ferrous bisglycinate chelate (Ferrochel®) and dietary supplements containing ferrous sulfate. The presence of small quantities of various ferric impurities was found. Two vitamins contained major iron compounds that did not correspond to ferrous fumarate and ferrous bisglycinate chelate.

Oshtrakh, M. I.; Milder, O. B.; Semionkin, V. A.

2004-12-01

6

FERROUS COMPOSITES: A REVIEW  

Microsoft Academic Search

In recent years considerable development has occurred in nonferrous composites and attention is now being given to make iron based composites. The objective of this paper is to review the on going research and development of ferrous composite materials. Cast iron in and of itself is viewed as a metal matrix composite, a predominately ferritic matrix with a random distribution

R. M. HATHAWAY; P. K. ROHATGI; N. SOBCZAK; J. SOBCZAK

7

Chelation Therapy  

MedlinePLUS

... tumor blood vessels. In a small study using mice, researchers studied iron-chelating agents to see if ... reduced the growth of skin cancer cells in mice. However, this experimental treatment has not been tested ...

8

Field evaluation of inorganic and chelated iron fertilizers as foliar sprays and soil application  

Microsoft Academic Search

A series of inorganic and chelated ferric and ferrous fertilizers were tested for their ability to alleviate Fe chlorosis as foliar and soil application on peach and grape under field conditions. Limited re?greening was obtained with foliar application of ferric citrate\\/ammonium nitrate, ferrous sulfate and DTPA on peaches, and with foliar application of ferric citrate\\/ammonium nitrate and ferrous sulfate and

David Wm. Reed; Calvin G. Lyons Jr; George Ray McEachern

1988-01-01

9

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

SciTech Connect

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

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

2010-07-13

10

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

NASA Astrophysics Data System (ADS)

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

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

2010-07-01

11

Hydroxyl radicals cause fluctuation in intracellular ferrous ion levels upon light exposure during photoreceptor cell death.  

PubMed

Iron accumulation is a potential pathogenic event often seen in age-related macular degeneration (AMD) patients. In this study, we focused on the relationship between AMD pathology and concentrations of ferrous ion, which is a highly reactive oxygen generator in biological systems. Murine cone-cells-derived 661 W cells were exposed to white fluorescence light at 2500 lx for 1, 3, 6, or 12 h. Levels of ferrous ions, reactive oxygen species (ROS), and hydroxyl radicals were detected by RhoNox-1, a novel fluorescent probe for the selective detection of ferrous ion, 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate, acetyl ester (CM-H2DCFDA), and 3'-p-(aminophenyl) fluorescein, respectively. Reduced glutathione, total iron levels and photoreceptor cell death were also measured. Two genes related to iron metabolism, transferrin receptor 1 (TfR1) and H ferritin (HFt), were quantified by RT-PCR. The effects of ferrous ion on cell death and hydroxyl radical production were determined by treatment with a ferrous ion chelating agent, 2,2'-bipyridyl. We found that the ferrous ion level decreased with light exposure in the short time frame, whereas it was upregulated during a 6-h light exposure. Total iron, ROS, cell death rate, and expression of TfR and HFt genes were significantly increased in a time-dependent manner in 661 W cells exposed to light. Chelation with 2,2'-bipyridyl reduced the level of hydroxyl radicals and protected against light-induced cell death. These results suggest that light exposure decreases ferrous ion levels and enhances iron uptake in photoreceptor cells. Ferrous ion may be involved in light-induced photoreceptor cell death through production of hydroxyl radicals. PMID:25447561

Imamura, Tomoyo; Hirayama, Tasuku; Tsuruma, Kazuhiro; Shimazawa, Masamitsu; Nagasawa, Hideko; Hara, Hideaki

2014-12-01

12

Hydroxypyridonate chelating agents  

SciTech Connect

Chelating agents are disclosed having 1-hydroxy-2-pyridinone (HOPO) and related moieties incorporated within their structures, including polydentate HOPO-substituted polyamines such as spermidine and spermine, and HOPO-substituted desferrioxamine. The chelating agents are useful in selectively removing certain cations from solution, and are particularly useful as ferric ion and actinide chelators. Novel syntheses of the chelating agents are provided.

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

1987-10-06

13

Hydroxypyridonate chelating agents  

DOEpatents

Chelating agents having 1-hydroxy-2-pyridinone (HOPO) and related moieties incorporated within their structures, including polydentate HOPO-substituted polyamines such as spermidine and spermine, and HOPO-substituted desferrioxamine. The chelating agents are useful in selectively removing certain cations from solution, and are particularly useful as ferric ion and actinide chelators. Novel syntheses of the chelating agents are provided.

Raymond, Kenneth N. (Berkeley, CA); Scarrow, Robert C. (Minneapolis, MN); White, David L. (Oakland, CA)

1987-01-01

14

Efficacy and safety of ferrous asparto glycinate in the management of iron deficiency anaemia in pregnant women.  

PubMed

Abstract The aim of the present investigation was to compare the efficacy and safety of oral ferrous asparto glycinate and ferrous ascorbate in pregnant women with iron deficiency anaemia (IDA). We performed a double blind, prospective, randomised, multicentre, parallel group comparative clinical study at three different centres in India. A total of 73 pregnant women at 12-26 weeks' gestation were divided into two arms. While one group received ferrous ascorbate, another group was treated with ferrous asparto glycinate for a period of 28 days. The mean rise in haemoglobin and ferritin levels on day 14 and 28 was evaluated. At both time points, significantly higher levels of haemoglobin and ferritin were noticed with ferrous asparto glycinate treatment as compared with ferrous ascorbate. Our results showed that ferrous asparto glycinate is an effective iron-amino acid chelate in the management of IDA in pregnant women as compared with ferrous ascorbate. Nevertheless, additional large scale prospective, randomised trials are warranted to confirm the findings of the present efficacy trial, and also to find out the anaemia eradication rate. PMID:24959663

Kamdi, S P; Palkar, P J

2015-01-01

15

21 CFR 582.5311 - Ferrous lactate.  

Code of Federal Regulations, 2011 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5311 Ferrous lactate. (a) Product. Ferrous lactate. (b) Conditions of use....

2011-04-01

16

21 CFR 582.5308 - Ferrous gluconate.  

Code of Federal Regulations, 2013 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5308 Ferrous gluconate. (a) Product. Ferrous gluconate. (b) Conditions of use....

2013-04-01

17

Chelation in Metal Intoxication  

PubMed Central

Chelation therapy is the preferred medical treatment for reducing the toxic effects of metals. Chelating agents are capable of binding to toxic metal ions to form complex structures which are easily excreted from the body removing them from intracellular or extracellular spaces. 2,3-Dimercaprol has long been the mainstay of chelation therapy for lead or arsenic poisoning, however its serious side effects have led researchers to develop less toxic analogues. Hydrophilic chelators like meso-2,3-dimercaptosuccinic acid effectively promote renal metal excretion, but their ability to access intracellular metals is weak. Newer strategies to address these drawbacks like combination therapy (use of structurally different chelating agents) or co-administration of antioxidants have been reported recently. In this review we provide an update of the existing chelating agents and the various strategies available for the treatment of heavy metals and metalloid intoxications. PMID:20717537

Flora, Swaran J.S.; Pachauri, Vidhu

2010-01-01

18

21 CFR 184.1308 - Ferrous gluconate.  

Code of Federal Regulations, 2011 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...

2011-04-01

19

21 CFR 184.1308 - Ferrous gluconate.  

Code of Federal Regulations, 2014 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...

2014-04-01

20

21 CFR 184.1308 - Ferrous gluconate.  

Code of Federal Regulations, 2012 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...

2012-04-01

21

Ferrous iron transport in Streptococcus mutans  

SciTech Connect

Radioiron uptake from /sup 59/FeCl/sub 3/ by Streptococcus mutans OMZ176 was increased by anaerobiosis, sodium ascorbate, and phenazine methosulfate (PMS), although there was a 10-min lag before PMS stimulation was evident. The reductant ascorbate may have provided ferrous iron. The PMS was reduced by the cells, and the reduced PMS then may have generated ferrous iron for transport; reduced PMS also may have depleted dissolved oxygen. It was concluded that S. mutans transports only ferrous iron, utilizing reductants furnished by glucose metabolism to reduce iron prior to its uptake.

Evans, S.L.; Arcenaeux, J.E.L.; Byers, B.R.; Martin, M.E.; Aranha, H.

1986-12-01

22

Improved ferrous shielding for flat cables  

NASA Technical Reports Server (NTRS)

To improve shielding of flat multicore cables, a thin, seamless ferrous shield around all cores optimizes low frequency magnetic shielding. Such shielding is covered with an ultrathin seamless coat of highly conductive nonferrous material.

Drechsler, R. J.

1969-01-01

23

Ferrous iron oxidation by anoxygenic phototrophic bacteria  

Microsoft Academic Search

NATURAL oxidation of ferrous to ferric iron by bacteria such as Thiobacillus ferrooxidans or Gallionella ferruginea1, or by chemical oxidation2,3 has previously been thought always to involve molecular oxygen as the electron acceptor. Anoxic photochemical reactions4-6 or a photobiological process involving two photosystems7-9 have also been discussed as mechanisms of ferrous iron oxidation. The knowledge of such processes has implications

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

1993-01-01

24

POLYCYCLIC AROMATIC HYDROCARBONS AND PHENOLICS IN FERROUS AND NON-FERROUS WASTE FOUNDRY SANDS  

Technology Transfer Automated Retrieval System (TEKTRAN)

A total of 43 sets of waste sand were collected from ferrous and non-ferrous foundries in the eastern United States. The concentration of organic compounds known as polycyclic aromatic hydrocarbons (PAHs) and phenolics were determined. These compounds are known to be toxic to humans. Since there ...

25

21 CFR 184.1311 - Ferrous lactate.  

Code of Federal Regulations, 2010 CFR

...lactate (iron (II) lactate, C6 H10 FeO6 , CAS Reg. No. 5905-52-2) in the trihydrate form is a greenish-white powder or crystalline mass. It is prepared by reacting calcium lactate or sodium lactate with ferrous sulfate,...

2010-04-01

26

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

27

Future Developments in NonFerrous Metallurgy  

Microsoft Academic Search

A major advance in the physical metallurgy of non-ferrous metals in recent years has been the use of knowledge, built on the foundation laid by Rosenhain, to predict unusual properties which can have considerable value in engineering applications. Much of the paper is therefore concerned with discussing these new discoveries and showing how they provide a possible escape from the

G. B. Brook; W. E. Duckworth

1976-01-01

28

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

Microsoft Academic Search

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

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

2011-01-01

29

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

30

Metal Chelating Crosslinkers Form Nanogels with High Chelation Stability  

PubMed Central

We present a series of hydrogel nanoparticles (nanogels) incorporating either acyclic or cyclic metal chelates as crosslinkers. These crosslinkers are used to formulate polyacrylamide-based nanogels (diameter 50 to 85 nm) yielding contrast agents with enhanced relaxivities (up to 6-fold greater than Dotarem®), because this nanogel structure slows the chelator's tumbling frequency and allows fast water exchange. Importantly, these nanogels also stabilize Gd3+ within the chelator thermodynamically and kinetically against metal displacement through transmetallation, which should reduce toxicity associated with release of free Gd3+. This chelation stability suggests that the chelate crosslinker strategy may prove useful for other applications of metal-chelating nanoparticles in medicine, including other imaging modalities and radiotherapy. PMID:24505553

Elst, Luce Vander; Schopf, Eric; Mahmoud, Enas; Laurent, Sophie; Almutairi, Adah

2013-01-01

31

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

32

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

33

Novel fluorescent chelate for Eu  

NASA Astrophysics Data System (ADS)

Novel high efficient fluorescent chelate for Eu based on diethylenethriaminepentaacetic acid and amino (beta) -diketones is proposed for time-resolved fluorescence immunoassay. The label surpasses all known chelates for europium in major spectral and luminescent characteristics. The proposed label has number of advantages over the well-known europium chelates. The assays with new fluorescent chelate do not require enhancement solution, but the sensitivity of Eu determination is the same as for DELFIA enhancement solution. The assay with new fluorescent chelate is insensitive to contamination of solutions and samples with ions of heavy metals, because the concentration of fluorescent chelate is measured and high excess of Eu prevents dissociation of fluorescent chelate complex. Techniques have been developed for covalent labeling of proteins with the new fluorescent chelate. The labelling proteins can be stored in the lyophilized state or in stabilized solution rather long and retain their immunological properties. Application of the new fluorescent chelate enables the washing step to be avoided and to develop the express non-separation assay.

Savitsky, Alexander P.; Chydinov, Alexander V.; Krilova, Svetlana M.

1995-05-01

34

Chelation of cadmium.  

PubMed Central

The toxicity of cadmium is determined by chelation reactions: in vivo, Cd2+ exists exclusively in coordination complexes with biological ligands, or with administered chelating agents. The Cd2+ ion has some soft character, but it is not a typical soft ion. It has a high degree of polarizability, and its complexes with soft ligands have predominantly covalent bond characteristics. Cd2+ forms the most stable complexes with soft donor atoms (S much greater than N greater than 0). The coordination stereochemistry of Cd2+ is unusually varied, including coordination numbers from 2 to 8. Even though the Cd2+ ion is a d10 ion, disturbed coordination geometries are often seen. Generally, the stability of complexes increases with the number of coordination groups contributed by the ligand; consequently, complexes of Cd2+ with polydentate ligands containing SH groups are very stable. Cd2+ in metallothionein (MT) is coordinated with 4 thiolate groups, and the log stability constant is estimated to 25.5. Complexes between Cd2+ and low molecular weight monodentate or bidentate ligands, e.g., free amino acids (LMW-Cd), seem to exist very briefly, and Cd2+ is rapidly bound to high molecular weight proteins, mainly serum albumin. These complexes (HMW-Cd) are rapidly scavenged from blood, mainly by the liver, and Cd2+ is redistributed to MT. After about 1 day the Cd-MT complex (MT-Cd) almost exclusively accounts for the total retained dose of Cd2+, independent of the route of exposure. MT-Cd is slowly transferred to and accumulated in kidney cortex. The acute toxicity and interorgan distribution of parenterally administered Cd2+ are strongly influenced by preceding MT induction, or decreased capacity for MT synthesis; however, the gastrointestinal (GI) uptake of Cd2+ seems unaffected by preceding MT induction resulting in considerable capacity for Cd2+ chelation in intestinal mucosa, and this finding indicates that endogenous MT is not involved in Cd2+ absorption. The toxicity of parenterally administered Cd2+ is strongly enhanced when administered as complexes with NTA or STPP , but it is much decreased when administered as a complex with EDTA. In chronic oral exposure the toxicity and GI uptake of Cd2+ is not changed when Cd2+ is administered as a complex with the detergent formula chelating agents NTA, EDTA and STPP . The uptake of Cd2+ from ligated intestine in vivo was not affected by administration of Cd2+ as complexes with CYS or GSH, but significantly reduced by complexation with EDTA or BAL. The acute toxicity of orally administered Cd2+ is reduced when Cd2+ is administered as a complex with EDTA.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:6734560

Andersen, O

1984-01-01

35

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

36

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

37

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

38

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

39

46 CFR 148.04-13 - Ferrous metal borings, shavings, turnings, or cuttings (excluding stainless steel).  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Ferrous metal borings, shavings, turnings, or cuttings...Certain Material § 148.04-13 Ferrous metal borings, shavings, turnings, or cuttings...hazardous materials described as ferrous metal borings, shavings, turnings,...

2010-10-01

40

21 CFR 184.1307c - Ferrous citrate.  

Code of Federal Regulations, 2010 CFR

...Ferrous citrate (iron (II) citrate, (C6 H6 FeO7 ), CAS Reg. No. 23383-11-1) is a slightly colored powder or white crystals. It is prepared from the reaction of sodium citrate with ferrous sulfate or by direct action of citric...

2010-04-01

41

Sintered ferrous antifriction materials for arduous operating conditions  

Microsoft Academic Search

The main methods by which the load carrying capacity of ferrous antifriction materials may be raised are to increase the strength of their metallic matrix by suitable alloying and to decrease their coefficient of friction by the addition of various sulfides. Researches in this field have led to the formulation of a new class of sulfidized ferrous materials. The investigation

I. M. Fedorchenko; L. I. Pugina; V. V. Pushkarev; Yu. F. Shevchuk; V. S. Ageeva

1967-01-01

42

The origin of ferrous zoning in Allende chondrule olivines  

Microsoft Academic Search

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

J. A. Peck; J. A. Wood

1987-01-01

43

Biogeochemistry and bacteriology of ferrous iron oxidation in geothermal habitats  

Microsoft Academic Search

A survey of hot, acid springs in Yellowstone Park has shown that high concentrations of ferrous and ferric iron are often present. Total ionic iron concentrations in different springs ranged from less than 1 ppm to greater than 200 ppm, and up to 50% of the ionic iron was in the ferrous form. Some of these springs also have high

Thomas D. Brock; Susan Cook; Sandra Petersen; J. L. Mosser

1976-01-01

44

21 CFR 184.1307a - Ferrous ascorbate.  

Code of Federal Regulations, 2010 CFR

...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 for its intended...

2010-04-01

45

Hydroxypyridonate chelating agents and synthesis thereof  

DOEpatents

Chelating agents having 1-hydroxy-2-pyridinone (HOPO) and related moieties incorporated within their structures, including polydentate HOPO-substituted polyamines such as spermidine and spermine, and HOPO-substituted desferrioxamine. The chelating agents are useful in selectively removing certain cations from solution, and are particularly useful as ferric ion and actinide chelators. Novel syntheses of the chelating agents are provided. 4 tabs.

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

1985-11-12

46

Removal of cyanides by complexation with ferrous compounds  

SciTech Connect

Alkaline chlorination, an oxidation process with chlorine (Cl{sub 2}) or hypochlorite (ClO{sup {minus}}), is the most widely accepted method of cyanide treatment. However, removal of cyanide from wastewater to the extent required by the effluent limits imposed by Federal and State regulatory authorities is practically impossible, especially when the majority of the cyanide is present as an iron-cyanide complex. One potential treatment method being further investigated uses ferrous (Fe{sup 2+}) compounds to react with free and complex cyanide ions and produce insoluble iron-cyanide complexes. However, sludges generated by this treatment method contain cyanide wastes which may be considered a hazardous waste by the US Environmental Protection Agency (US EPA). The studies reported in this paper demonstrate that ferrous (Fe{sup 2+}) precipitation can remove cyanide ions (both free and complex) to a concentration within the range of 1 to 2 mg/L. The wastewaters utilized in these tests were collected from a coke plant facility. Synthetic cyanide solutions were used in the studied as well. Ferrous compounds used in the studies included commercial-grade ferrous sulfate, commercial-grade ferrous chloride, and spent pickle liquor (containing ferrous ion). The desired effluent quality was successfully attained in the treatment of the above-mentioned wastewaters by using ferrous compounds as well as spent pickle liquor.

Varuntanya, C.P.; Zabban, W. [Chester Environmental, Moon Township, PA (United States)

1995-12-31

47

Metallic Recovery and Ferrous Melting Processes  

SciTech Connect

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

Luis Trueba

2004-05-30

48

Mössbauer Resonance Studies of Ferrous Ions in Ice  

Microsoft Academic Search

Mo¨ssbauer resonance experiments have been carried out over a wide temperature range on frozen aqueous solutions of ferrous chloride and ferrous sulfate. Well-resolved spectra were obtained which show the two-line absorption pattern characteristic of a nuclear quadrupole hyperfine interaction in 57Fe. Measurements of quadrupole splitting, resonance linewidths, and anisotropic intensities were made as a function of temperature and for samples

Arthur J. Nozik; Morton Kaplan

1967-01-01

49

Ferrous ion oxidation by Thiobacillus ferrooxidans immobilized on activated carbon  

Microsoft Academic Search

The immobilization of Thiobacillus ferrooxidans on the activated carbon particles as support matrix was investigated. Cycling batch operation results in the complete oxidation of ferrous iron in 8 d when the modified 9 K medium is set to flow through the mini-bioreactor at a rate of 0.104 L\\/h at 25 °C. The oxidation rate of ferrous iron with immobilized T.

Ji-kui ZHOU; Wen-qing QIN; Yin-jian NIU; Hua-xia LI

2006-01-01

50

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

51

Sensory evaluation of dairy supplements enriched with reduced iron, ferrous sulfate or ferrous fumarate.  

PubMed

Objective. To determine the degree of liking of the Oportunidades programme dietary supplements (DS) -purees and beverages- added with different iron salts (IS): reduced iron (RI), ferrous sulphate (FS) or ferrous fumarate (FF) during 24 weeks of storage. Materials and methods. The DS were evaluated through a hedonic scale for aroma, flavour and colour attributes; at time zero and every eight weeks, each panel member evaluated three DS with same flavour and presentation but different IS. Seventy women participated as panel members. Results. The chocolate and banana DS exhibited a change in preference by colour and flavour due to storage. DS with FS or RI showed the least preference by flavour and colour in the context of the three IS considered. The chocolate and neutral DS enriched with FS changed their colour and flavour. Conclusion. DS were, in general, well-liked; nonetheless, for purees enriched with FS and for beverages enriched with RI, the less-liked attributes were colour and flavour. PMID:25629275

Morales, Josefina C; Sánchez-Vargas, Elena; García-Zepeda, Rodrigo; Villalpando, Salvador

2015-02-01

52

Iron chelation and multiple sclerosis.  

PubMed

Histochemical and MRI studies have demonstrated that MS (multiple sclerosis) patients have abnormal deposition of iron in both gray and white matter structures. Data is emerging indicating that this iron could partake in pathogenesis by various mechanisms, e.g., promoting the production of reactive oxygen species and enhancing the production of proinflammatory cytokines. Iron chelation therapy could be a viable strategy to block iron-related pathological events or it can confer cellular protection by stabilizing hypoxia inducible factor 1?, a transcription factor that normally responds to hypoxic conditions. Iron chelation has been shown to protect against disease progression and/or limit iron accumulation in some neurological disorders or their experimental models. Data from studies that administered a chelator to animals with experimental autoimmune encephalomyelitis, a model of MS, support the rationale for examining this treatment approach in MS. Preliminary clinical studies have been performed in MS patients using deferoxamine. Although some side effects were observed, the large majority of patients were able to tolerate the arduous administration regimen, i.e., 6-8 h of subcutaneous infusion, and all side effects resolved upon discontinuation of treatment. Importantly, these preliminary studies did not identify a disqualifying event for this experimental approach. More recently developed chelators, deferasirox and deferiprone, are more desirable for possible use in MS given their oral administration, and importantly, deferiprone can cross the blood-brain barrier. However, experiences from other conditions indicate that the potential for adverse events during chelation therapy necessitates close patient monitoring and a carefully considered administration regimen. PMID:24397846

Weigel, Kelsey J; Lynch, Sharon G; LeVine, Steven M

2014-01-01

53

Continuous biological ferrous iron oxidation in a submerged membrane bioreactor.  

PubMed

Microbial oxidation of ferrous iron may be available alternative method of producing ferric iron, which is a reagent used for removal of H2S from biogas. In this study, a submerged membrane bioreactor (MBR) system was employed to oxidize ferrous iron to ferric iron. In the submerged MBR system, we could keep high concentration of iron-oxidizing bacteria and high oxidation rate of ferrous iron. There was membrane fouling caused by chemical precipitates such as K-jarosite and ferric phosphate. However, a strong acidity (pH 1.75) of solution and low ferrous iron concentration (below 3000 mg/I) significantly reduced the fouling of membrane module during the bioreactor operation. A fouled membrane module could be easily regenerated with a 1 M of sulfuric acid solution. In conclusion, the submerged MBR could be used for high-density culture of iron-oxidizing bacteria and for continuous ferrous iron oxidation. As far as our knowledge concerns, this is the first study on the application of a submerged MBR to high acidic conditions (below pH 2). PMID:16003962

Park, D; Lee, D S; Park, J M

2005-01-01

54

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

55

[Ferrous-manganese oxidizing bacteria from the nature water].  

PubMed

Glass slides were hanged into a canal to acquire the ferrous-manganese oxidizing bacteria settled bio-film. Two isolated methods for ferrous-manganese oxidizing bacteria with special iron-manganese oxidizing matrix from the bio-film were tested. Element component of bacteria product and sheath structure of bacteria were analyzed. With two methods, plate cultivation and the novel semi-solid in situ cultivation method, strains belong to Family Leptothrix were isolated. XRF showed that the amorphous iron and manganese were two major metal elements of the precipitation formed by one strain of Leptothrix spp.. Through the microscope observation, one strain of Family Leptothrix was determined to form branch-like structured sheath, while another strain formed spider web-like structured sheath. Those isolated bacteria provide model strains for future testing of FISH probe and PCR primer of ferrous-manganese oxidizing bacteria. PMID:18763517

Qin, Song-yan; Ma, Fang; Huang, Peng

2008-06-01

56

The origin of ferrous zoning in Allende chondrule olivines  

NASA Technical Reports Server (NTRS)

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 idendical to, and is not the precursor of, matrix olivine.

Peck, Julia A.; Wood, John A.

1987-01-01

57

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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

58

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

E-print Network

Ferrous iron-dependent drug delivery enables controlled and selective release of therapeutic agents and cancer. Here, we describe a method to exploit aberrant levels of mobile ferrous iron (Fe parasites produce high concentrations of mobile ferrous iron as a consequence of their catabolism of host

Bogyo, Matthew

59

Orange but not apple juice enhances ferrous fumarate absorption in small children  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ferrous fumarate is a common, inexpensive iron form increasingly used instead of ferrous sulfate as a food iron supplement. However, few data exist as to whether juices enhance iron absorption from ferrous fumarate. We studied 21 children, ages 4.0 to 7.9 years using a randomized crossover design. S...

60

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...

61

LIMESTONE AND LIME NEUTRALIZATION OF FERROUS IRON ACID MINE DRAINAGE  

EPA Science Inventory

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

62

Origin of ferrous zoning in Allende chondrule olivines  

SciTech Connect

Olivine crystals in Allende Type 1 chondrules have ferrous rims (Fa/sub 15-44/), a few microns thick, at grain surfaces and along crosscutting cracks. This ferrous olivine contains as much as 2 atomic pct. Al and Cr, and 0.2 pct. Ti. Along cracks, profiles of Fe, Al, Cr, and Ti are consistent with diffusional emplacement: these elements moved from an external source through the cracks as a vapor or by grain boundary diffusion, then into the olivine by lattice diffusion. The emplacement did not occur during an epoch of planetary metamorphism that partly equilibrated matrix and chondrule olivines, because (e.g.) neither matrix nor primary magnesian chondrule olivine contains even 1/10 this much, Al, Cr, and Ti. The authors argue that the source of these elements was the nebular gas, and emplacement occurred prior to accretion. The ferrous zones at olivine grain boundaries do not display simple diffusion profiles: rather they appear to be a composite of two concentric rims. The inner rims have compositions similar to those of the ferrous zones along cracks, and contain the highest concentrations of Al, Cr, and Ti. The outer rims are of uniformly high Fa content and relatively low Al, Cr, and Ti concentration. These outer rims appear to be additional material that condensed onto the chondrules after the diffusional emplacement event discussed earlier. Matrix olivine grains, which are identical to these rims in composition, condensed simultaneously.

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

1987-06-01

63

Method for the preparation of ferrous low carbon porous material  

SciTech Connect

A method for preparing a porous metal article using a powder metallurgy forming process is provided which eliminates the conventional steps associated with removing residual carbon. The method uses a feedstock that includes a ferrous metal powder and a polycarbonate binder. The polycarbonate binder can be removed by thermal decomposition after the metal article is formed without leaving a carbon residue.

Miller, Curtis Jack

2014-05-27

64

Wear of synthetic diamond when grinding ferrous metals  

Microsoft Academic Search

IT is well established that diamond is an inefficient abrasive for grinding ferrous materials especially the low carbon variety. The widely held view is that as ordinary carbon has a strong affinity for iron forming iron carbide (Fe3C) this should also be the case with diamond (cubic carbon) when grinding steel. The high rate at which diamond grinding wheels wear

R. Komanduri; M. C. Shaw

1975-01-01

65

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

66

21 CFR 184.1307c - Ferrous citrate.  

Code of Federal Regulations, 2012 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...

2012-04-01

67

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

Microsoft Academic Search

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

J. L. Means; C. A. Alexander

1981-01-01

68

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 PMID:23216870

2012-01-01

69

Iron Chelation Therapy in Myelodysplastic Syndromes  

PubMed Central

Myelodysplastic syndromes (MDS) are a heterogeneous disorder of the hematopoietic stem cells, frequently characterized by anemia and transfusion dependency. In low-risk patients, transfusion dependency can be long lasting, leading to iron overload. Iron chelation therapy may be a therapeutic option for these patients, especially since the approval of oral iron chelators, which are easier to use and better accepted by the patients. The usefulness of iron chelation in MDS patients is still under debate, mainly because of the lack of solid prospective clinical trials that should take place in the future. This review aims to summarize what is currently known about the incidence and clinical consequences of iron overload in MDS patients and the state-of the-art of iron chelation therapy in this setting. We also give an overview of clinical guidelines for chelation in MDS published to date and some perspectives for the future. PMID:20672005

Messa, Emanuela; Cilloni, Daniela; Saglio, Giuseppe

2010-01-01

70

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

71

Effect of Fe-chelating complexes on a novel M2FC performance with ferric chloride and ferricyanide catholytes.  

PubMed

As an effort to better utilize the microbial fuel cell (MFC) technology, we previously proposed an innovative MFC system named M2FC consisting of ferric-based MFC part and ferrous-based fuel cell (FC) part. In this reactor, ferric ion, the catholyte in the MFC part, was efficiently regenerated by the FC part with the generation of additional electricity. When both units were operated separately, the ferric-based MFC part produced approximately 1360 mW m(-2) of power density with FeCl(3) as catholyte and Fe-citrate as anolyte. The ferrous-based FC part with FeCl(3) as catholyte and Fe-EDTA as anolyte displayed the highest power density (1500 mW m(-2)), while that with ferricyanide as catholyte and Fe-noligand as anolyte had the lowest power density (380 mW m(-2)). The types of catholytes and chelating complexes as anolyte were found to play important roles in the reduction of ferric ions and oxidation of ferrous ion. Linear sweep voltammetry results supported that the cathode electrolytes were electrically active and these agreed well with the M2FC reactor performance. These results clearly showed that ligands played critical role in the efficiency and rate for recycling iron ion and thus the M2FC performance. PMID:22018860

Chung, Kyungmi; Lee, Ilgyu; Han, Jong-In

2012-01-01

72

Oral iron therapy with ferrous fumarate and polysaccharide iron complex.  

PubMed

Oral iron replacement therapy with Chromagen, containing ferrous fumarate, and Niferex, containing polysaccharide iron complex, can successfully maintain hematologic and iron indices in dialysis clients and demonstrated fewer adverse effects in selected clients. Their multiple ingredient dose forms, which further support erythropoiesis, and their possible decrease in distressing side effects should enhance client compliance, making these two drugs excellent alternatives to traditional iron therapies. PMID:1627011

Glassman, E

1992-06-01

73

Chromate removal from aqueous wastes by reduction with ferrous ion  

Microsoft Academic Search

Experimental measurements of reaction stoichiometries indicate that optimum conditions for chromate removal from oxygenated, 25°C aqueous wastes by reduction with ferrous ion occur at pH less than 10.0 in solutions containing the following anions: ClOâ⁻, Cl⁻, F⁻, NOâ⁻, and POâ\\/sup 3 -\\/. At pH greater than 10.0 and at lower pH in solutions that contain greater than 10⁻⁴ M total

L. E. Eary; Dhanpat Rai

1988-01-01

74

Recycling ferrous-nickel slag in blast cleaning.  

PubMed

The aim of this study is the development of a procedure for the recycling of the ferrous-nickel slag that is widely used in open dry blast cleaning operations in Greek shipyards thus annually generating thousands of tons of blast cleaning waste. Laboratory tests were carried out, based on the reclamation of the material fraction with size a distribution within the range -1,400 + 150 microm, in order to determine the number of the effective uses (life cycles) of the abrasive material. It is demonstrated that the reclamation yield in the first three life cycles is more than 80%. Laboratory tests also proved that the recycled ferrous-nickel slag has properties comparable to the fresh material's ones in terms of particle size distribution, consumption and other physical-chemical properties. A semi-industrial recycling unit of used ferrous-nickel slag was also designed and installed in a Greek shipyard (Neorion New SA of Syros Shipyards). The operation of the semi-industrial recycling unit verified the conclusions resulting from the laboratory tests, and most important, it was proved profitable for the ship- PMID:12152895

Katsikaris, K; Voutsas, E; Magoulas, K; Andronikos, G; Stamataki, S

2002-06-01

75

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

SciTech Connect

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

NONE

1992-12-01

76

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

77

Ferrous Iron Is a Significant Component of Bioavailable Iron in Cystic Fibrosis Airways  

PubMed Central

ABSTRACT Chronic, biofilm-like infections by the opportunistic pathogen Pseudomonas aeruginosa are a major cause of mortality in cystic fibrosis (CF) patients. While much is known about P. aeruginosa from laboratory studies, far less is understood about what it experiences in vivo. Iron is an important environmental parameter thought to play a central role in the development and maintenance of P. aeruginosa infections, for both anabolic and signaling purposes. Previous studies have focused on ferric iron [Fe(III)] as a target for antimicrobial therapies; however, here we show that ferrous iron [Fe(II)] is abundant in the CF lung (~39 µM on average for severely sick patients) and significantly correlates with disease severity (? = ?0.56, P = 0.004), whereas ferric iron does not (? = ?0.28, P = 0.179). Expression of the P. aeruginosa genes bqsRS, whose transcription is upregulated in response to Fe(II), was high in the majority of patients tested, suggesting that increased Fe(II) is bioavailable to the infectious bacterial population. Because limiting Fe(III) acquisition inhibits biofilm formation by P. aeruginosa in various oxic in vitro systems, we also tested whether interfering with Fe(II) acquisition would improve biofilm control under anoxic conditions; concurrent sequestration of both iron oxidation states resulted in a 58% reduction in biofilm accumulation and 28% increase in biofilm dissolution, a significant improvement over Fe(III) chelation treatment alone. This study demonstrates that the chemistry of infected host environments coevolves with the microbial community as infections progress, which should be considered in the design of effective treatment strategies at different stages of disease. PMID:23963183

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

2013-01-01

78

Chelated Indium Activable Tracers for Geothermal Reservoirs  

E-print Network

SGP-TR-99 Chelated Indium Activable Tracers for Geothermal Reservoirs Constantinos V. Chrysikopoulos Paul Kruger June 1986 Financial support was provided through the Stanford Geothermal Program under University Stanford Geothermal Program Interdisciplinary Research in Engineering and Earth Sciences STANFORD

Stanford University

79

Questions and Answers on Unapproved Chelation Products  

MedlinePLUS

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

80

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

81

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

82

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

83

Chelator Fragment Libraries for Targeting Metalloproteinases  

PubMed Central

A chelator fragment library based on a variety of metal binding groups was screened against a metalloproteinase. Lead hits were identified and an expanded library of select compounds was synthesized, resulting in numerous high-affinity hits against several metalloprotein targets. The findings clearly demonstrate that chelators can be used to generate libraries suitable for fragment-based lead design (FBLD) directed at important metalloproteins. PMID:20058293

Agrawal, Arpita; Johnson, Sherida L.; Jacobsen, Jennifer A.; Miller, Melissa T.; Chen, Li-Hsing

2010-01-01

84

Mercury emission and behavior in primary ferrous metal production  

NASA Astrophysics Data System (ADS)

Ferrous metal production is thought to be a major mercury emission source because it uses large amounts of coal and iron ore, which contain trace amounts of mercury impurities. However, there is limited information about mercury emissions during the production process. In this study, we focused on the coke-oven process, sintering furnace process, and blast furnace process. We measured the mercury concentration in the raw materials, products, and byproducts to estimate the amount of mercury emitted and to investigate the behavior of mercury during the processes. Average mercury concentrations were 30.8 ?g kg -1 in 54 samples of iron ore and 59.9 ?g kg -1 in 33 samples of coal. The total mercury used for ferrous metal production in Japan was estimated to be 8.45 tons in 2005, with 4.07 tons from iron ore, 3.76 tons from coal, and 0.478 tons from limestone. Emissions from the sintering process accounted for more than 90% of the total emissions, and mercury in the exhaust gas was reduced using an activated coke tower and desulfurization equipment installed downstream of an electrostatic precipitator. When byproduct gas generated from coke-oven and blast furnace processes were included, mercury emissions estimates based on actual measurements were 4.08 tons y -1 (in 2005). Thus, about 50% of the mercury input in ferrous metal production was emitted to the atmosphere. The emission factor was calculated as 0.0488 g Hg ton -1 for crude steel production. The introduction of activated coke tower or desulfurization equipment in sintering furnace facilities would reduce mercury emissions.

Fukuda, Naomichi; Takaoka, Masaki; Doumoto, Shingo; Oshita, Kazuyuki; Morisawa, Shinsuke; Mizuno, Tadao

2011-07-01

85

Overview of Lightweight Ferrous Materials: Strategies and Promises  

NASA Astrophysics Data System (ADS)

Reducing the density of steels is a novel approach for weight reduction of automobiles to improve fuel efficiency. In this overview article, strategies for the development of lightweight steels are presented with a focus on bulk ferrous alloys. The metallurgical principles of these steels and their mechanical properties of relevance to automotive applications are discussed. Some of the engineering aspects highlighting the possible problems related to mass production of these steels are also considered. Application prospects of these steels vis-à-vis standard automotive steels are shown.

Rana, Radhakanta; Lahaye, Chris; Ray, Ranjit Kumar

2014-08-01

86

Overview of Lightweight Ferrous Materials: Strategies and Promises  

NASA Astrophysics Data System (ADS)

Reducing the density of steels is a novel approach for weight reduction of automobiles to improve fuel efficiency. In this overview article, strategies for the development of lightweight steels are presented with a focus on bulk ferrous alloys. The metallurgical principles of these steels and their mechanical properties of relevance to automotive applications are discussed. Some of the engineering aspects highlighting the possible problems related to mass production of these steels are also considered. Application prospects of these steels vis-à-vis standard automotive steels are shown.

Rana, Radhakanta; Lahaye, Chris; Ray, Ranjit Kumar

2014-09-01

87

Electron Paramagnetic Resonance of Myoglobin and Related Ferrous Complexes.  

NASA Astrophysics Data System (ADS)

Electron paramagnetic resonance spectra of myoglobin (Mb), the O_2-storage protein of mammals, are reported for the first time. The EPR signals arise from the biologically active ferrous deoxyMb and photolyzed oxyMb, Mb*(O_2) complexes. Similar EPR signals were also discovered in photolyzed carbonmonoxy Mb, Mb*(CO), and from a model heme complex. The EPR signals in this work are from non-Kramers doublets which are not usually EPR active. These integer spin systems are nondegenerate in B = 0 and therefore split quadratically in B. In order to interpret the signals, a simulation program based on the spin Hamiltonian {cal H}_{rm s} = {bf Scdot Dcdot S} + beta{bf Scdot gcdot B} was developed. The experimental EPR spectra are rather broad, and analysis shows that the components of the tensor D have to be distributed in order to explain the lineshapes. The EPR signals from Mb and Mb*(CO) could be simulated well with this model, but not the Mb*(O_2) signals. It is suggested that the Mb*(O_2) spectrum results from magnetic coupling between the iron spin S = 2 and O_2^in S = 1. The model was tested on single crystals of magnetically dilute ferrous fluosilicate and found to be satisfactory. In addition, EPR data and simulations are presented for two ferrous solution complexes. The findings disagree with a previous report, and a flaw in the simulation of field-swept spectra is discussed. Further characterization of the complexes with magnetic susceptibility supports the EPR analysis presented here. The magnitude of the splitting of the non-Kramers doublet in zero magnetic field is crucial for observation of signals. The measurements were made using X (9 GHz) and Q (35 GHz) band microwave spectrometers and demonstrate the need for higher frequency measurements as only a fraction of the molecules give signals at 9 GHz. The EPR spectra of high-spin ferrous complexes are shown to be quite sensitive to the iron environment. As with most transition metal complexes, the EPR signals are observed only at low temperatures (T < 77 K).

Hendrich, Michael Paul

88

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

89

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. PMID:24895548

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

2014-01-01

90

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

91

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

92

Ferrous sulphate gel dosimetry and MRI for proton beam dose measurements  

Microsoft Academic Search

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

Sven Å. J. Bäck; Joakim Medin; Peter Magnusson; Peter Olsson; Erik Grusell; Lars E. Olsson

1999-01-01

93

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

94

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

95

Monitoring corrosion in boiler systems with colorimetric tests for ferrous and total iron  

SciTech Connect

Because of the low oxygen conditions that prevail in industrial boiler systems, active corrosion releases soluble corrosion products that contain iron in the ferrous, Fe(II), oxidation state. Active corrosion can be detected throughout boiler systems by colorimetric determination of ferrous iron. Ferrous iron measurements are particularly useful for detecting corrosion in once-through components such as feedwater (FW) systems. The same approach is equally valuable for detecting internal boiler corrosion when accurate information on cycles of concentration is available. Ferrous iron testing also can differentiate the dispersion of iron oxide particulates in the FW from corrosion of the boiler internals. Corrosion mechanisms that generate ferrous iron species are discussed as well as the interpretation of data obtained by total iron testing.

Godfrey, M.R.; Chen, T.Y. [Nalco Chemical Co., Naperville, IL (United States)

1995-10-01

96

Ferrous versus ferric oral iron formulations for the treatment of iron deficiency: a clinical overview.  

PubMed

Iron deficiency anaemia represents a major public health problem, particularly in infants, young children, pregnant women, and females with heavy menses. Oral iron supplementation is a cheap, safe, and effective means of increasing haemoglobin levels and restoring iron stores to prevent and correct iron deficiency. Many preparations are available, varying widely in dosage, formulation (quick or prolonged release), and chemical state (ferrous or ferric form). The debate over the advantages of ferrous versus ferric formulations is ongoing. In this literature review, the tolerability and efficacy of ferrous versus ferric iron formulations are evaluated. We focused on studies comparing ferrous sulphate preparations with ferric iron polymaltose complex preparations, the two predominant forms of iron used. Current data show that slow-release ferrous sulphate preparations remain the established and standard treatment of iron deficiency, irrespective of the indication, given their good bioavailability, efficacy, and acceptable tolerability demonstrated in several large clinical studies. PMID:22654638

Santiago, Palacios

2012-01-01

97

Analysis of chelators in complex matrices  

SciTech Connect

The behavior of radioactive wastes, both in storage tanks and potentially in the environment, depends heavily on the presence or absence of organic chelating agents. For example, migration of heavy metals in soils is enhanced by complexation with these compounds. As a result, we have studied various techniques for the analysis of a variety of semivolatile and nonvolatile complexing agents. To address current needs in the DOE complex, we studied these compounds in saturated brine matrices. Analysis of chelators from these matrices required development of extraction techniques. Using liquid-liquid extraction followed by GC-MS analysis, we have quantitatively analyzed acetamide, 1,10-phenanthroline, and 8-hydroxyquinoline at concentrations as low as 10 ppm. Other important chelators, such as EDTA, are ionic in nature and cannot be analyzed this way. These compounds were extracted using anion exchange and complexation methods, and were analyzed using electrospray mass spectrometry.

Borgerding, A.J.; Rogers, Y.C.; Spall, W.D. [Los Alamos National Lab., NM (United States)

1995-12-01

98

A macrocyclic chelator with unprecedented Th?? 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

99

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

100

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

101

Deferiprone Chelation Therapy for Thalassemia Major  

Microsoft Academic Search

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

R. Galanello; S. Campus

2009-01-01

102

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

103

Chelate adsorption for trace voltammetric measurements of iron(III)  

Microsoft Academic Search

A very sensitive electrochemical stripping procedure for trace measurements of iron(III) is described. The chelate of iron with Solochrome Violet RS is adsorbed on the hanging mercury drop electrode, and the reduction current of the accumulated chelate is measured by voltammetry. The adsorption and redox behaviours are explored by cyclic voltammetry. The height of the chelate peak, which is about

Joseph Wang; Jawad Mahmoud

1987-01-01

104

Effects of iron polymaltose complex, ferrous fumarate and ferrous sulfate treatments in anemic pregnant rats, their fetuses and placentas.  

PubMed

Although oral iron preparations are widely prescribed to prevent and to treat iron deficiency anemia in pregnancy, comparative data on their effects to the mother, fetus and placenta are limited. In this study, the effects of oral iron polymaltose complex (IPC), ferrous fumarate (FF) and ferrous sulfate (FS) were compared in anemic pregnant rats, their fetuses and placentas. Hematological variables and oxidative stress markers in the liver, heart and kidneys of the dams and fetuses as well as the markers for oxidative stress, inflammation and hypoxia in placentas were assessed. Pregnancy outcome was measured by number of fetuses, and by neonate and placental weight. All therapies were comparably effective in correcting anemia. FS and FF, but not IPC, resulted in liver damage in dams and oxidative stress in dams, fetuses and placentas. FS group presented the highest catalase and GPx levels in dams, fetuses and placentas. IPC, but not FF or FS, restored normal TNF-? and IL6 expression levels in placentas whereas FS-treated animals presented the highest cytokine levels, suggesting a local inflammatory reaction. Anemia-induced high levels of HIF-1? were partially lowered by IPC and FF but further elevated by FS. Most of the negative effects associated with IDA were resolved by IPC treatment. Especially FS treatment was found to elicit hepatic damage in the dams, oxidative stress in the dams, fetuses and placenta as well as inflammation and high levels of HIF-1? in the placenta. Pregnancy outcome of FFand FS-treated animals was worse than that of IPC-treated animals. PMID:23547731

Toblli, Jorge E; Cao, Gabriel; Oliveri, Leda; Angerosa, Margarita

2013-06-01

105

Chelation therapy after the Trial to Assess Chelation Therapy: results of a unique trial  

PubMed Central

Purpose of review EDTA chelation therapy has been in off-label use for the treatment of atherosclerosis. We review the results of the first large-scale randomized trial of this treatment. Recent findings The trial to assess chelation therapy was a $30 million National Institutes of Health-funded study of the safety and efficacy of EDTA-based chelation infusions in 1708 post-myocardial infarction (MI) patients. The trial to assess chelation therapy demonstrated a significant (P?=?0.035) 18% reduction in a combined primary endpoint of death, MI, stroke, coronary revascularization, or hospitalization for angina. In diabetic patients the benefit was more extreme, with a 41% relative reduction in risk (P?=?0.0002) and a 43% reduction in total mortality (P?=?0.011). Safety data were favorable. A reduction of oxidative stress by chelation of toxic metals has been proposed as a possible mechanism of action. Summary Recent research suggests that EDTA chelation may be a well-tolerated and effective treatment for post-MI patients. Future replication and mechanistic studies are important prior to implementation in all post-MI patients. PMID:25023079

Avila, Maria D.; Escolar, Esteban; Lamas, Gervasio A.

2014-01-01

106

Accelerating effect and mechanism of passivation of polyaniline on ferrous metals  

Microsoft Academic Search

To investigate the corrosion protection mechanism of polyaniline (PANI) films on ferrous metals, this work presents preparation method of a separate protonated PANI film electrode and results of its open-circuit potential (OCP) in 0.5M NaClO4 and 0.5M Na2SO4 solutions with different pH and the galvanic interaction between the PANI film electrode and ferrous metals. X-ray photoelectron spectroscopy (XPS) shows the

Hua Zhu; Lian Zhong; Shuhu Xiao; Fuxing Gan

2004-01-01

107

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

108

Determination of cerium in materials of ferrous metallurgy  

SciTech Connect

The determination of low contents of cerium in highly alloyed steels and alloys involves a long and laborious separation from accompanying components. A method of separation by adsorption of cerium fluoride in silicon dioxide, previously used in analytical laboratories of the rare-metal industry in the analysis of mineral raw materials and technological solution, has been used to increase the selectivity and rapidity of the separation of cerium. The purpose of this work was to study the possibility of using this method of separation of cerium in the analysis of highly alloyed steels and alloys. The degree of precipitation of cerium fluoride in the presence of iron (the basis of materials of ferrous metallurgy), which has virtually no effect on the adsorption process, was studied. The degree of adsorption is also 95-100% in the presence of 1 g of iron. After cerium was separated from accompanying components, it was determined by amperometric and photometric methods (the latter with arsenazo III) and by inversion voltammetry. Thus, the proposed method of separation from accompanying elements in alloyed steels is selective and rapid and permits the determination of microgram quantities of cerium with the requisite accuracy.

Popkova, G.N.; Fedorova, N.D.; Zubritskaya, L.D. [I.P. Bardin Central Scientific Research Inst. of Ferrous Metallurgy, Ekaterinburg (Russian Federation)

1994-06-01

109

Evaluation of iron-chelating agents in cultured heart muscle cells. Identification of a potential drug for chelation therapy.  

PubMed

Primary cultures of neonatal rat cardiac muscle cells incorporated radioiron from both [55Fe]transferrin and 59FeCl3 (added simultaneously). To evaluate the effect of iron chelators on such uptake, deferri chelators were added 6 hr after addition of the radioiron sources. The microbial chelator agrobactin was significantly more effective than the drug defoxamine in reduction of 55Fe uptake from [55Fe]transferrin; both chelators halted 59Fe3+ uptake. Agrobactin may have potential in chelation therpay for iron-overload disease. Certain other microbial chelators lowered radioiron uptake from either [55Fe]transferrin of 59FeCl3. These chelators should be useful inhibitors for studies of animal cell iron uptake and intracellular iron flow. PMID:7430764

Sciortino, C V; Byers, B R; Cox, P

1980-12-01

110

Mechanism of Ferrous Iron Binding and Oxidation by Ferritin from a Pennate Diatom*  

PubMed Central

A novel ferritin was recently found in Pseudo-nitzschia multiseries (PmFTN), a marine pennate diatom that plays a major role in global primary production and carbon sequestration into the deep ocean. Crystals of recombinant PmFTN were soaked in iron and zinc solutions, and the structures were solved to 1.65–2.2-? resolution. Three distinct iron binding sites were identified as determined from anomalous dispersion data from aerobically grown ferrous soaked crystals. Sites A and B comprise the conserved ferroxidase active site, and site C forms a pathway leading toward the central cavity where iron storage occurs. In contrast, crystal structures derived from anaerobically grown and ferrous soaked crystals revealed only one ferrous iron in the active site occupying site A. In the presence of dioxygen, zinc is observed bound to all three sites. Iron oxidation experiments using stopped-flow absorbance spectroscopy revealed an extremely rapid phase corresponding to Fe(II) oxidation at the ferroxidase site, which is saturated after adding 48 ferrous iron to apo-PmFTN (two ferrous iron per subunit), and a much slower phase due to iron core formation. These results suggest an ordered stepwise binding of ferrous iron and dioxygen to the ferroxidase site in preparation for catalysis and a partial mobilization of iron from the site following oxidation. PMID:23548912

Pfaffen, Stephanie; Abdulqadir, Raz; Le Brun, Nick E.; Murphy, Michael E. P.

2013-01-01

111

Effect of ferrous metal presence on lead leaching in municipal waste incineration bottom ashes.  

PubMed

The recovery of ferrous and non-ferrous metals from waste to energy (WTE) ash continues to advance as the sale of removed metals improves the economics of waste combustion. Published literature suggests that Fe and Fe oxides play a role in suppressing Pb leaching in the Toxicity Characteristic Leaching Procedure (TCLP); further removal of ferrous metals from WTE ashes may facilitate higher Pb leaching under the TCLP. Eight WTE bottom ash size-fractions, from three facilities, were evaluated to assess the effect of metallic Fe addition and ferrous metal removal on TCLP leaching. Metallic Fe addition was demonstrated to reduce Pb leaching; the removal of ferrous metals by magnet resulted in a decrease in total available Pb (mg/kg) in most ash samples, yet Pb leachability increased in 5 of 6 ash samples. The research points to two chemical mechanisms to explain these results: redox interactions between Pb and Fe and the sorption of soluble Pb onto Fe oxide surfaces, as well as the effect of the leachate pH before and after metals recovery. The findings presented here indicate that generators, processors, and regulators of ash should be aware of the impact ferrous metal removal may have on Pb leaching, as a substantial increase in leaching may have significant implications regarding the management of WTE ashes. PMID:25464288

Oehmig, Wesley N; Roessler, Justin G; Zhang, Jianye; Townsend, Timothy G

2015-02-11

112

Federal regulation of unapproved chelation products.  

PubMed

Chelation products can be helpful in the treatment of metal poisoning. However, many unapproved products with unproven effectiveness and safety are marketed to consumers, frequently via the internet. This paper describes the primary responsibility of the Health Fraud and Consumer Outreach Branch of the United States Food and Drug Administration to identify and address health fraud products. Efforts to prevent direct and indirect hazards to the population's health through regulatory actions are described. PMID:24197664

Lee, Charles E

2013-12-01

113

[Iron chelation. Biological significance and medical application].  

PubMed

Iron, an essential element for all aerobic organisms, exists in a very insoluble form under physiological conditions. Therefore, most microorganisms secrete iron chelating compounds called siderophores which are able to sequester ferric ions from the environment. A vast number of such compounds has been isolated from cultures of microorganisms and tested for enhancement of iron excretion in experimental animals. Only one compound, deferrioxamine B, has been shown to be clinically effective and well tolerated in humans suffering from chronic iron overload. However, this drug can only be administered successfully by injection or slow infusion. In spite of considerable research it has not been possible to overcome this drawback by developing suitable formulations or derivatives which are orally active. Deferri-ferrithiocin, a novel type of siderophore, has recently been isolated from a streptomyces culture. This substance is well absorbed orally and has been shown to enhance the excretion of ferric ion in iron loaded rats. Further investigations are now necessary to establish acute toxicity levels and longterm tolerability before efficacy tests in man can be planned. Other recent developments in the field of metal chelation include experimental studies using deferrioxamine for the treatment of conditions resulting from toxic levels of iron or aluminium in chronically dialyzed patients. In addition, attempts are being made to administer chelation therapy in the treatment of various infections and chronic inflammation, as well as other conditions linked with disorders of iron metabolism. PMID:6227988

Peter, H H

1983-10-01

114

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

115

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

116

Identification and characterization of a Saccharomyces cerevisiae gene (PAR1) conferring resistance to iron chelators.  

PubMed

o-Phenanthroline (1,10-phenanthroline) is a chemical known to chelate iron and other transition metal ions. This compound was added to solid yeast media to reduce the concentration of biologically available iron. Other essential divalent cations, like Zn2+ or Cu2+, which could also be bound, were supplemented. Growth of wild-type yeast strains was totally inhibited at specific concentrations of the chelator. However, several cells containing plasmids of a multicopy vector genomic library of S. cerevisiae could be selected by growth on these media. All of the resistant clones carried a single additional gene, PAR1 on their multicopy plasmids. Plasmid-directed overexpression of PAR1 increased the resistance of transformants to o-phenanthroline and additionally conferred resistance to 1-nitroso-2-naphthol, an iron(III)-binding molecule with different coordinating ligands. By supplementing the o-phenanthroline-containing media with several different metal ions, it could be proved that the selection plates really caused a specific iron limitation. These observations clearly demonstrated that the overexpressed PAR1 gene enables the cell to compete with iron-chelating organic molecules. PAR1 null mutants, constructed by insertion of the LEU2 gene into the open reading frame, showed a remarkable phenotype: they did not grow on slightly alkaline buffered media (pH greater than 7) and became hypersensitive to oxidative stress by hydrogen peroxide. Of several heavy metal ions, such as Fe3+, Fe2+, Co2+, Ni2+, Cu2+ and Zn2+, tested for supplementation of the alkaline growth deficiency, only iron, either added in the ferrous or ferric form, was able to restore cellular growth. It can be concluded from the DNA sequence that PAR1 encodes a highly acidic protein of 650 residues with mostly hydrophilic character. Some interesting repetitive amino acid motifs, such as (Asp-Asn)4 or Cys-Ser-Glu, may act as metal-binding sites. The possible role of PAR1 is discussed. PMID:1889413

Schnell, N; Entian, K D

1991-09-01

117

Orally active alpha-ketohydroxypyridine iron chelators: studies in mice  

SciTech Connect

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

Kontoghiorghes, G.J.

1986-12-01

118

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

119

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

120

Iron isotope fractionation during photo-oxidation of aqueous ferrous iron  

NASA Astrophysics Data System (ADS)

The classic interpretation of banded iron formations (BIFs) presumes the presence of dissolved O2 in the surface ocean to oxidize ferrous Fe. However, at least two alternative oxidation mechanisms are possible: UV photo-oxidation; and the activity of anaerobic Fe(II)-oxidizing photosynthetic bacteria. We are investigating Fe isotope fractionation as a means of differentiating amongst these mechanisms. Photo-oxidation has been examined at pH ~ 3 and 41°C in the absence of ligands other than H2O, OH-, and Cl- using UVA (316-400 nm) and UVC (200-280 nm) light sources. In these experiments, ferrous Fe was oxidized and precipitated as ferric oxyhydroxide. We find that isotopically heavy Fe was preferentially removed from solution. The fractionation factor (?) for the overall reaction is ~ 1.0025. This value is comparable to the ? between Fe2+ and Fe3+ hexaquo complexes, but larger than the effect seen during the overall process of ferrous Fe oxidation and precipitation at near-neutral pH. The magnitude of isotope fractionation is likely to change at higher pH for two reasons. First, ferric oxyhydroxide precipitation, which may impart a kinetic isotope effect, is faster at higher pH. Second, the major UV-absorbing ferrous species in the ocean is the ferrous hydroxide ion [Fe(OH)+], the concentration of which is strongly pH dependent. Photo-oxidation experiments at realistic seawater pH are under current investigation.

Staton, S.; Amskold, L.; Gordon, G.; Anbar, A.; Konhauser, K.

2006-05-01

121

Liposomal delivery systems for encapsulation of ferrous sulfate: Preparation and characterization.  

PubMed

Liposomal delivery systems for water-soluble bioactives were prepared using the pro-liposome and the microfluidization technologies. Iron, an essential micronutrient as ferrous sulfate and ascorbic acid, as an antioxidant for iron were encapsulated in the liposomes. Liposomes prepared by the microfluidization technology using 6% (w/w) concentration of the lipid encapsulated with ferrous sulfate and ascorbic acid had particle size distributions around 150 to 200 nm, whereas liposomes from the pro-liposome technology resulted in particle sizes of about 5 microm. The encapsulation efficiency of ferrous sulfate was 58% for the liposomes prepared by the microfluidization using 6% (w/w) lipid and 7.5% of ferrous sulfate concentrations, and it was 11% for the liposomes from pro-liposome technology using 1.5% (w/v) lipid and 15% of ferrous-sulfate concentration. Both the liposomes exhibited similar levels of oxidative stability, demonstrating the feasibility of microfluidization-based liposomal delivery systems for large-scale food/nutraceutical applications. PMID:17162577

Kosaraju, Shantha L; Tran, Cindy; Lawrence, Andrew

2006-01-01

122

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. PMID:25006339

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

2014-01-01

123

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

124

Ferrous sulfate versus iron polymaltose complex for treatment of iron deficiency anemia in children.  

PubMed

We assessed the clinical response and side effects of Ferrous sulfate (FS) and Iron polymaltose complex (IPC) in 118 children with Iron deficiency anemia (IDA). Subjects were randomized to receive therapy with either oral IPC (Group A, n=59) or oral FS (Group B, n=59); all were given elemental iron in three divided doses of 6 mg/kg/day. One hundred and six children could be followed up; 53 in each group. Children who received ferrous sulfate were having higher hemoglobin level, and less residual complaints as compared to those who had received iron polymaltose complex. Our study suggests ferrous sulfate has a better clinical response and less significant adverse effects during treatment of IDA in children. PMID:19430060

Bopche, Ankur Vikas; Dwivedi, Rashmi; Mishra, Rakesh; Patel, G S

2009-10-01

125

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

126

CHELATOR EDTA IN NUTRIENT SOLUTION DECREASES GROWTH OF WHEAT  

Microsoft Academic Search

Chelators have routinely been used to supply iron (Fe) in the nutrient solutions for growing plants. However, potential toxicity of these chelators to plants has not been assessed hitherto. In this study, wheat was grown in the presence or absence of EDTA (ethylenediaminetetraacetic acid) in the nutrient solution (with Fe supplied to plants as a foliar spray of Fe citrate).

Z. Rengel

2002-01-01

127

Cell cycle synchronisation by 3-hydroxypyridin-4-one iron chelators  

Microsoft Academic Search

We describe a protocol for the synchronisation of normal and tumour cells grown in suspension cultures using 3-hydroxypyridin-4-one iron chelators. These compounds inhibit ribonucleotide reductase, one of the rate limiting enzymes in DNA synthesis, and so block the cell cycle in late G1 phase. After removal of the chelator or repletion of cellular iron, cells progress through the cycle and

Katharine P. Hoyes; John B. Porter

1996-01-01

128

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

129

Heavy metal displacement in chelate-irrigated soil during phytoremediation  

Microsoft Academic Search

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.

M. S Liphadzi; M. B Kirkham

2003-01-01

130

Macrocyclic Chelator Assembled RGD Multimers for Tumor Targeting  

PubMed Central

Macrocyclic chelators have been extensively used for complexation of metal ions. A widely used chelator, DOTA, has been explored as a molecular platform to assemble multiple bioactive peptides in this paper. The multivalent DOTA-peptide bioconjugates demonstrate promising tumor targeting ability. PMID:21524578

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

2011-01-01

131

New Rare Earth (III) Chelates of Ferrocenyl Benzoyl Hydrazone  

Microsoft Academic Search

Nine new rare earth (III) chelates of the formula Ln (Fcbh)3 (where Eu, Gd, Dy, Ho, Er, and Yb) were synthesized via the reaction of rare earth chlorides with All the chelates have been identified by microanalyses and IR spectra, and some of them by H nmr and mass spectra.

Lun Zhang; Xinqin Fang; Guomin Zhang

1988-01-01

132

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

133

Reusable chelating resins concentrate metal ions from highly dilute solutions  

NASA Technical Reports Server (NTRS)

Column chromatographic method uses new metal chelating resins for recovering heavy-metal ions from highly dilute solutions. The absorbed heavy-metal cations may be removed from the chelating resins by acid or base washes. The resins are reusable after the washes are completed.

Bauman, A. J.; Weetal, H. H.; Weliky, N.

1966-01-01

134

Results of Long-Term Iron-Chelating Therapy  

Microsoft Academic Search

The improvement in survival and quality of life of iron-overloaded patients achieved by regular subcutaneous chelation has been extensively documented over the years. A review of the long-term results allows one to establish the following points: (1) with regular subcutaneous chelation, a negative iron balance can be obtained in most patients, except very young ones; (2) severe deferoxamine (DFO) toxicity

Vilma Gabutti; Antonio Piga

1996-01-01

135

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

136

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). PMID:24899360

2014-01-01

137

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

138

Chelators for copper radionuclides in positron emission tomography radiopharmaceuticals†  

PubMed Central

The development of chelating agents for copper radionuclides in positron emission tomography radiopharmaceuticals has been a highly active and important area of study in recent years. The rapid evolution of chelators has resulted in highly specific copper chelators that can be readily conjugated to biomolecules and efficiently radiolabeled to form stable complexes in vivo. Chelators are not only designed for conjugation to monovalent biomolecules but also for incorporation into multivalent targeting ligands such as theranostic nanoparticles. These advancements have strengthened the role of copper radionuclides in the fields of nuclear medicine and molecular imaging. This review emphasizes developments of new copper chelators that have most greatly advanced the field of copper-based radiopharmaceuticals over the past 5 years. PMID:24347474

Cai, Zhengxin; Anderson, Carolyn J.

2014-01-01

139

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. PMID:23332666

Franz, Katherine J.

2013-01-01

140

Luminescent polyaminocarboxylate chelates of terbium and europium. The effect of chelate structure  

Microsoft Academic Search

We have synthesized and spectrally characterized a series of new luminescent lanthanide complexes based on linear and macrocycle polyaminocarboxylate chelates, covalently joined to an organic sensitizer 7-amino-4-methyl-2(1H)-quinolinone (carbostyril 124). These complexes are luminescent with both terbium and europium and have millisecond lifetime, sharply spiked emission spectra (<10 nm fwhm), large Stokes shifts (>150 nm), excellent solubility, moderate absorption (12000 M⁻¹

Min Li; Paul R. Selvin

1995-01-01

141

Characterisation of a Ferrous Agarose Xylenol (FAX) gel for radiotherapy dose measurement.  

PubMed

The oxidation of ferrous to ferric ions due to ionizing radiation has been used for chemical dosimetry since 1927. The introduction of metal indicator dye xylenol orange (XO) sensitises the measurement of ferric ion yield. A ferrous sulphate- agarose- xylenol orange (FAX) gel was prepared and the gel then exposed to dose ranging from 0.2 to 10 Gy using various high energy photon and electron beams from a linear accelerator. Some general characteristics of FAX such as energy dependence, optical density (OD)-dose relationship, reproducibility and auto-oxidation of ferrous ions were analysed. The radiation yield G of the gel was calculated for gels prepared in oxygen and in air and the values were 46.3 +/- 2.1 and 40.9 +/- 1.4 Fe3+ per 100 eV for photons respectively. However for stock gel which was kept for 5 days pre-irradiation the G value decreased to 36.6 +/- 1.1. The gel shows linearity in OD-dose relationship, energy independence and reproducibility over the dose range investigated. Auto-oxidation of ferrous ions resulted in optical density changes of less than 1.5% per day. PMID:17682403

Leong, Lee Hon; Kandaiya, S; Seng, Ng Bong

2007-06-01

142

Sintering of powder mixtures and the growth of ferrous powder metallurgy  

Microsoft Academic Search

Advances in the understanding of sintering of powder mixtures contributed significantly to the growth of ferrous powder metallurgy industry. Solid-state sintering and liquid-phase activated sintering play an important role in the sintering of powder mixtures. In this paper, sintering of iron powder with graphite; iron powder with copper and graphite; iron powder with nickel and graphite; iron powder with phosphorus;

K. S Narasimhan

2001-01-01

143

COMBINATION LIMESTONE-LIME NEUTRALIZATION OF FERROUS IRON ACID MINE DRAINAGE  

EPA Science Inventory

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

144

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

145

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

146

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...

147

Simulation study of the ferrous ferric electron transfer at a metal-aqueous electrolyte interface  

Microsoft Academic Search

We report a new simulation study of the rate of ferrous–ferric electron transfer at a metal electrolyte interface. In contrast with earlier work, new features in our study include a detailed account of the effects of the field associated with the charging of the electrode, inclusion of entropic effects in the calculated free energy barriers, and a study of the

B. B. Smith; J. W. Halley

1994-01-01

148

Ferrous iron is found in mesenteric lymph bound to TIMP-2 following hemorrhage/resuscitation.  

PubMed

Extracellular iron has been implicated in the pathogenesis of post-injury organ failure. However, the source(s) and biochemical species of this iron have not been identified. Based upon evidence that distant organ injury results from an increase in intestinal permeability, we looked for ferrous iron in mesenteric lymph in anesthetized rats undergoing hemorrhage and fluid resuscitation (H/R). Ferrous iron increased in lymph from 4.7 nmol/mg of protein prior to hemorrhage to 86.6 nmol/mg during resuscitation. Utilizing immuno-spin trapping in protein fractions that were rich in iron, we tentatively indentified protein carrier(s) of ferrous iron by MALDI-TOF MS. One of the identified proteins was the metalloproteinase (MMP) inhibitor, TIMP-2. Antibody to TIMP-2 immunoprecipitated 74% of the ferrozine detectable iron in its protein fraction. TIMP-2 binds iron in vitro at pH 6.3, which is typical of conditions in the mesentery during hemorrhage, but it retains the ability to inhibit the metalloproteases MMP-2 and MMP-9. In summary, there is a large increase in extracellular ferrous iron in the gut in H/R demonstrating dysregulation of iron homeostasis. We have identified, for the first time, the binding of extracellular iron to TIMP-2. PMID:21229381

Atkins, James L; Gorbunov, Nikolai V; Trabosh, Valerie; Van Duyne, Rachel; Kashanchi, Fatah; Komarov, Andrei M

2011-04-01

149

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

150

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

151

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

152

Energy conservation and efficiency in Giprokoks designs at Ukrainian ferrous-metallurgical enterprises  

SciTech Connect

Energy conditions at Ukrainian ferrous-metallurgical enterprises are analyzed. Measures to boost energy conservation and energy efficiency are proposed: specifically, the introduction of systems for dry slaking of coke; and steam-gas turbines that employ coke-oven gas or a mixture of gases produced at metallurgical enterprises. Such turbines may be built from Ukrainian components.

M.I. Fal'kov [Giprokoks, the State Institute for the Design of Coke-Industry Enterprises, Kharkov (Ukraine)

2009-07-15

153

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

EPA Science Inventory

The behavior of two inert redox electrodes (Pt and wax-impregnated graphite) was investigated in anaerobic ferrous and ferric chloride solutions in order to establish if these electrodes respond to the FE3/Fe2+ couple in a Nernstian nanner. ew method for determining dissolved fer...

154

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

EPA Science Inventory

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

155

ThermoChemical Wear Mechanism of Diamond Tool in Machining of Ferrous Metals  

Microsoft Academic Search

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

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

2004-01-01

156

Characterization of ferrous ions in hafnium-doped yttrium iron garnet  

Microsoft Academic Search

The ferrous content of hafnium-doped yttrium iron garnet crystals has been determined by a number of methods and microwave measurements of the temperature dependence of the anisotropy constant found to give the most reliable value. The Fe2+ ions have a doublet energy level lying lowest with a maximum splitting of 75 cm-1.

J. M. Robertson; D. Elwell

1969-01-01

157

Chelation: harnessing and enhancing heavy metal detoxification--a review.  

PubMed

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. PMID:23690738

Sears, Margaret E

2013-01-01

158

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. PMID:23690738

Sears, Margaret E.

2013-01-01

159

Synthetic and natural iron chelators: therapeutic potential and clinical use  

PubMed Central

Iron-chelation therapy has its origins in the treatment of iron-overload syndromes. For many years, the standard for this purpose has been deferoxamine. Recently, considerable progress has been made in identifying synthetic chelators with improved pharmacologic properties relative to deferoxamine. Most notable are deferasirox (Exjade®) and deferiprone (Ferriprox®), which are now available clinically. In addition to treatment of iron overload, there is an emerging role for iron chelators in the treatment of diseases characterized by oxidative stress, including cardiovascular disease, atherosclerosis, neurodegenerative diseases and cancer. While iron is not regarded as the underlying cause of these diseases, it does play an important role in disease progression, either through promotion of cellular growth and proliferation or through participation in redox reactions that catalyze the formation of reactive oxygen species and increase oxidative stress. Thus, iron chelators may be of therapeutic benefit in many of these conditions. Phytochemicals, many of which bind iron, may also owe some of their beneficial properties to iron chelation. This review will focus on the advances in iron-chelation therapy for the treatment of iron-overload disease and cancer, as well as neurodegenerative and chronic inflammatory diseases. Established and novel iron chelators will be discussed, as well as the emerging role of dietary plant polyphenols that effectively modulate iron biochemistry. PMID:21425984

Hatcher, Heather C; Singh, Ravi N; Torti, Frank M; Torti, Suzy V

2013-01-01

160

Synthetic and natural iron chelators: therapeutic potential and clinical use.  

PubMed

Iron-chelation therapy has its origins in the treatment of iron-overload syndromes. For many years, the standard for this purpose has been deferoxamine. Recently, considerable progress has been made in identifying synthetic chelators with improved pharmacologic properties relative to deferoxamine. Most notable are deferasirox (Exjade(®)) and deferiprone (Ferriprox(®)), which are now available clinically. In addition to treatment of iron overload, there is an emerging role for iron chelators in the treatment of diseases characterized by oxidative stress, including cardiovascular disease, atherosclerosis, neurodegenerative diseases and cancer. While iron is not regarded as the underlying cause of these diseases, it does play an important role in disease progression, either through promotion of cellular growth and proliferation or through participation in redox reactions that catalyze the formation of reactive oxygen species and increase oxidative stress. Thus, iron chelators may be of therapeutic benefit in many of these conditions. Phytochemicals, many of which bind iron, may also owe some of their beneficial properties to iron chelation. This review will focus on the advances in iron-chelation therapy for the treatment of iron-overload disease and cancer, as well as neurodegenerative and chronic inflammatory diseases. Established and novel iron chelators will be discussed, as well as the emerging role of dietary plant polyphenols that effectively modulate iron biochemistry. PMID:21425984

Hatcher, Heather C; Singh, Ravi N; Torti, Frank M; Torti, Suzy V

2009-12-01

161

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. PMID:24363816

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

2013-01-01

162

Highly Diastereoselective Chelation-controlled Additions to ?-Silyloxy Ketones  

PubMed Central

The polar Felkin-Anh, Cornforth, and Cram-chelation models predict that the addition of organometallic reagents to silyl–protected ?–hydroxy ketones proceeds via a non-chelation pathway to give anti-diol addition products. This prediction has held true for the vast majority of additions reported in the literature and few methods for chelation-controlled additions of organometallic reagents to silyl–protected ?–hydroxy ketones have been introduced. Herein, we present a general and highly diastereoselective method for the addition of dialkylzincs and (E)-di-, (E)-tri- and (Z)-disubstituted vinylzinc reagents to ?-silyloxy ketones using alkyl zinc halide Lewis acids, RZnX, to give chelation-controlled products (dr ?18:1). The compatibility of organozinc reagents with other functional groups makes this method potentially very useful in complex molecule synthesis. PMID:21534530

Stanton, Gretchen R.; Koz, Gamze

2011-01-01

163

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

164

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

165

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

DOEpatents

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

Raymond, K.; Xu, J.

1999-04-06

166

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

DOEpatents

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

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

1999-01-01

167

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

168

An Evaluation of the Chelating Agent EDDS for Marigold Production  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

169

Cadmium mobilization by nitrogen donor chelating agents.  

PubMed

The relative abilities of a series of acyclic polyamine chelating agents containing only nitrogen donors (N-donors) to induce the urinary excretion of cadmium has been examined in the rat. The compounds examined include triethylenetetramine dihydrochloride (TRIEN), tris(2-aminoethyl)amine trihydrochloride (TREN), tetraethylenepentamine pentahydrochloride (TETRAEN), and pentaethylenehexamine hexahydrochloride (PENTAEN). Sodium N-methyl-D-glucamine-N-carbodithioate (NaG) was used as a positive control compound. The polyamines induced a significant increase in the urinary excretion of cadmium in rats that had been loaded with cadmium at least 4 d prior to the polyamine treatments. A comparison of these with similar data on macrocylic nitrogen donor systems, which form much more stable complexes with cadmium but are also ineffective in enhancing the excretion of cadmium from such aged deposits, suggests that the factors responsible for the relative inefficiency of these compounds may involve either a difficulty in penetrating cellular membranes or a slow rate of reaction with biologically bound cadmium. The occurrence of oliguria and anuria following the administration of the several of the polyamines indicates that their use is accompanied by significant renal damage in cadmium-exposed rats. PMID:8637059

Jones, M M; Xu, C; Singh, P K; Walker, E M

1996-05-01

170

Chelation of organoarsenate with dimercaptosuccinic acid.  

PubMed

Alkane arsenate herbicides are available commercially, and their acute toxicity has been well documented in previous studies. Animal studies have indicated that dimercaptosuccinic acid (DMSA) can be used as an oral chelating agent. A 20-y-old white male cocaine addict attempted suicide by drinking approximately 500 ml of a 16% monosodium methanearsenate solution. He vomited 10 or more times and was admitted to the intensive care unit with impending shock and early liver and renal involvement. Four 5-day courses of 30 mg DMSA/kg/24 h were given. This brought the serum arsenic level from 2,871 micrograms/L to 6 micrograms/L, and his urine arsenic level from 78,920 micrograms/L to 21 micrograms/L in 30 d. Renal function tests returned to normal, with normal renal creatinine clearance, normal blood urea nitrogen and serum creatinine. However liver functions were abnormal, with elevation of serum transaminases, which later proved secondary to chronic hepatitis. No side effects of DMSA was encountered during the therapy. DMSA was successfully used to detoxify acute organoarsenate poisoning in a clinical setting, supporting experimental reports in the literature. PMID:7571355

Shum, S; Whitehead, J; Vaughn, L; Shum, S; Hale, T

1995-06-01

171

Potentials and drawbacks of chelate-enhanced phytoremediation of soils  

Microsoft Academic Search

Chelate-enhanced phytoremediation has been proposed as an effective tool for the extraction of heavy metals from soils by plants. However, side-effects related to the addition of chelates, e.g. metal leaching and effects on soil micro-organisms, were usually neglected. Therefore, greenhouse and lysimeter studies were conducted to study the phytoremedation potential of EDGA and citric acid and to evaluate its effects

P. F. A. M. Römkens; Lucas Bouwman; Jan Japenga; Cathrina Draaisma

2002-01-01

172

Synthesis of feralex a novel aluminum\\/iron chelating compound  

Microsoft Academic Search

There is a need for in vivo applicable Fe3+ and Al3+ chelation compounds for use as medicines to treat toxic overload conditions of these ions. A novel compound, 2-deoxy-2-(N-carbamoylmethyl-[N?-2?-methyl-3?-hydroxypyrid-4?-one])-d-glucopyranose, designed to chelate Fe3+ or Al3+, has been synthesised utilising three naturally occurring products: maltol, glycine and glucosamine. The synthesis is a simple two step process. First, glycine is coupled to

Theo P. A Kruck; Timothy E Burrow

2002-01-01

173

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

174

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

175

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

Microsoft Academic Search

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

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

2005-01-01

176

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

177

The magnesium chelation step in chlorophyll biosynthesis  

SciTech Connect

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

Weinstein, J.

1990-11-01

178

Strain dependence of electromagnetic generation of ultrasonic surface waves in ferrous metals  

Microsoft Academic Search

It is demonstrated that the efficiency of the electromagnetic generation of ultrasonic surface waves in ferrous metals is strongly influenced by superimposed elastic strains. A graph of efficiency versus applied magnetic field has many features, and the changes of these in Armco iron and 1018 Steel are reported for the strain range -3×10-3

R. Bruce Thompson

1976-01-01

179

Strain dependence of electromagnetic generation of ultrasonic surface waves in ferrous metals  

Microsoft Academic Search

It is demonstrated that the efficiency of the electromagnetic generation of ultrasonic surface waves in ferrous metals is strongly influenced by superimposed elastic strains. A graph of efficiency versus applied magnetic field has many features, and the changes of these in Armco iron and 1018 Steel are reported for the strain range ?3×10?3

R. Bruce Thompson

1976-01-01

180

Stabilization\\/solidification of waste ferrous sulphate from titanium dioxide production by fluidized bed combustion product  

Microsoft Academic Search

A treatment procedure to allow the disposal of waste ferrous sulphate was developed. This waste contains sulphuric acid and originates from titanium dioxide production. The process is based on simultaneous neutralization and stabilization\\/solidification (S\\/S) of the waste by means of fluidized bed combustion product (FBC-P). The prepared stabilized waste specimens have a solid matrix and their batch leachates display practically

M. Vondruska; V. Bednarik; M. Sild

2001-01-01

181

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

182

Equivalent bioavailability of iron from ferrous salts and a ferric polymaltose complex. Clinical and experimental studies.  

PubMed

In both experimental animals and human subjects iron absorption over a wide dosage range was quantitatively equivalent from ferrous salts and a ferric polymaltose complex under basal conditions. The comparable bioavailability was maintained when demand was increased by iron depletion or erythroid stimulation and depressed by expansion of body stores or impaired erythropoiesis. This common pattern for iron retention from both salt and complex supports the interchangeable use of these products in therapy of absolute iron deficiency. PMID:3566865

Jacobs, P

1987-01-01

183

IN SITU PRECIPITATION FOR REMEDIATION OF HEAVY METAL CONTAMINATED GROUNDWATER AT A NON FERROUS INDUSTRIAL SITE  

Microsoft Academic Search

An extensive pilot program is performed in order to design an in-situ remediation system for historic groundwater contamination with heavy metals near a non ferrous metals producing plant in Belgium. A profound site characterization has been performed, in order to obtain a detailed cross-section of the subsoil and a detailed understanding of the contaminated aquifer(s) present in the water bearing

Karolien Vanbroekhoven; Francis Van den Broeck; Karel Feyaerts; Eric Van den Broeck

2007-01-01

184

Regional siderosis: a new challenge for iron chelation therapy  

PubMed Central

The traditional role of iron chelation therapy has been to reduce body iron burden via chelation of excess metal from organs and fluids and its excretion via biliary-fecal and/or urinary routes. In their present use for hemosiderosis, chelation regimens might not be suitable for treating disorders of iron maldistribution, as those are characterized by toxic islands of siderosis appearing in a background of normal or subnormal iron levels (e.g., sideroblastic anemias, neuro- and cardio-siderosis in Friedreich ataxia- and neurosiderosis in Parkinson's disease). We aimed at clearing local siderosis from aberrant labile metal that promotes oxidative damage, without interfering with essential local functions or with hematological iron-associated properties. For this purpose we introduced a conservative mode of iron chelation of dual activity, one based on scavenging labile metal but also redeploying it to cell acceptors or to physiological transferrin. The “scavenging and redeployment” mode of action was designed both for correcting aberrant iron distribution and also for minimizing/preventing systemic loss of chelated metal. We first examine cell models that recapitulate iron maldistribution and associated dysfunctions identified with Friedreich ataxia and Parkinson's disease and use them to explore the ability of the double-acting agent deferiprone, an orally active chelator, to mediate iron scavenging and redeployment and thereby causing functional improvement. We subsequently evaluate the concept in translational models of disease and finally assess its therapeutic potential in prospective double-blind pilot clinical trials. We claim that any chelator applied to diseases of regional siderosis, cardiac, neuronal or endocrine ought to preserve both systemic and regional iron levels. The proposed deferiprone-based therapy has provided a paradigm for treating regional types of siderosis without affecting hematological parameters and systemic functions. PMID:24427136

Cabantchik, Zvi Ioav; Munnich, Arnold; Youdim, Moussa B.; Devos, David

2013-01-01

185

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

186

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. PMID:24145449

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

2013-01-01

187

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

PubMed

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. PMID:22924881

Brickman, Timothy J; Armstrong, Sandra K

2012-11-01

188

Oral iron therapy in human subjects, comparative absorption between ferrous salts and iron polymaltose.  

PubMed

Iron absorption was directly compared between equivalent doses of ferrous salts and a polymaltose complex using a twin-isotope technique in which each individual acts as his own control. In the first study, bioavailability of iron from ferrous sulfate and the complex was defined at physiologic doses of 5 mg (Group 1: n = 14) and therapeutic doses of 50 mg (Group 2: n = 13). In Group 1, mean absorption from salt was 47.77% (SD 14.58%) and from polymaltose, 46.56% SD 17.07%). In Group 2, mean absorption from salt was 32.92% (SD 13.42%) and from polymaltose, 27.07% (SD 6.50%). In a second study, 100 mg of iron in a chewable formulation was used to compare absorption between equal doses of ferrous fumarate and the polymaltose complex. Mean absorption from salt was 10.25% (SD 6.89%) and from polymaltose 10.68% (SD 4.68%). At all three dosage levels, iron is equally available from salt or polymaltose for hemoglobin synthesis (p greater than 0.20), and absorption negatively correlated with plasma ferritin (p less than 0.01). These two materials may be used interchangeably in the treatment of patients with absolute iron deficiency. PMID:6599114

Jacobs, P; Johnson, G; Wood, L

1984-01-01

189

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

190

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. PMID:22924881

Brickman, Timothy J.; Armstrong, Sandra K.

2012-01-01

191

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

PubMed Central

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

Santolini, Jérôme; Maréchal, Amandine; Boussac, Alain; Dorlet, Pierre

2013-01-01

192

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

193

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

194

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

NASA Astrophysics Data System (ADS)

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 [FeCl 2·4H 2O, FeCl 2·6H 2O, FeSO 4·H 2O, FeSO 4·7H 2O, FeCO 3, 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-SO 4, Fe-HCO 3, H-Fe-Cl, and H-Fe-SO 4. 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 (FeCO 3), 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-HCO 3 dominated leachate representing ferromagnesian weathering evolved into an Earth-like seawater composition dominated by NaCl, and finally into a hypersaline Mg-Na-SO 4-Cl brine. Weathering appears to have taken place initially under conditions that allowed solution of ferrous iron [low O 2(g)], but later caused oxidation of iron [high O 2(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.

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

2003-11-01

195

Chelation in metal intoxication-Principles and paradigms.  

PubMed

The present review provides an update of the general principles for the investigation and use of chelating agents in the treatment of intoxications by metals. The clinical use of the old chelators EDTA (ethylenediamine tetraacetate) and BAL (2,3-dimercaptopropanol) is now limited due to the inconvenience of parenteral administration, their own toxicity and tendency to increase the neurotoxicity of several metals. The hydrophilic dithiol chelators DMSA (meso-2,3-dimercaptosuccinic acid) and DMPS (2,3-dimercapto-propanesulphonate) are less toxic and more efficient than BAL in the clinical treatment of heavy metal poisoning, and available as capsules for oral use. In copper overload, DMSA appears to be a potent antidote, although d-penicillamine is still widely used. In the chelation of iron, the thiols are inefficient, since iron has higher affinity for ligands with nitrogen and oxygen, but the new oral iron antidotes deferiprone and desferasirox have entered into the clinical arena. Comparisons of these agents and deferoxamine infusions are in progress. General principles for research and development of new chelators are briefly outlined in this review. PMID:25457281

Aaseth, Jan; Skaug, Marit Aralt; Cao, Yang; Andersen, Ole

2014-10-19

196

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

197

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

198

In vitro analysis of iron chelating activity of flavonoids.  

PubMed

Flavonoids have been demonstrated to possess miscellaneous health benefits which are, at least partly, associated with iron chelation. In this in vitro study, 26 flavonoids from different subclasses were analyzed for their iron chelating activity and stability of the formed complexes in four patho/physiologically relevant pH conditions (4.5, 5.5, 6.8, and 7.5) and compared with clinically used iron chelator deferoxamine. The study demonstrated that the most effective iron binding site of flavonoids represents 6,7-dihydroxy structure. This site is incorporated in baicalein structure which formed, similarly to deferoxamine, the complexes with iron in the stoichiometry 1:1 and was not inferior in all tested pH to deferoxamine. The 3-hydroxy-4-keto conformation together with 2,3-double bond and the catecholic B ring were associated with a substantial iron chelation although the latter did not play an essential role at more acidic conditions. In agreement, quercetin and myricetin possessing all three structural requirements were similarly active to baicalein or deferoxamine at the neutral conditions, but were clearly less active in lower pH. The 5-hydroxy-4-keto site was less efficient and the complexes of iron in this site were not stable at the acidic conditions. Isolated keto, hydroxyl, methoxyl groups or an ortho methoxy-hydroxy groups were not associated with iron chelation at all. PMID:21450273

Mlad?nka, P?emysl; Macáková, Kate?ina; Filipský, Tomáš; Zatloukalová, Libuše; Jahodá?, Lud?k; Bovicelli, Paolo; Silvestri, Ilaria Proietti; Hrdina, Radomír; Saso, Luciano

2011-05-01

199

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

PubMed

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

Ruivard, M

2013-01-01

200

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

DOEpatents

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

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

1997-01-01

201

Histological detection of catalytic ferrous iron with the selective turn-on fluorescent probe RhoNox-1 in a Fenton reaction-based rat renal carcinogenesis model.  

PubMed

Iron overload of a chronic nature has been associated with a wide variety of human diseases, including infection, carcinogenesis, and atherosclerosis. Recently, a highly specific turn-on fluorescent probe (RhoNox-1) specific to labile ferrous iron [Fe(II)], but not to labile ferric iron [Fe(III)], was developed. The evaluation of Fe(II) is more important than Fe(III) in vivo in that Fe(II) is an initiating component of the Fenton reaction. In this study, we applied this probe to frozen sections of an established Fenton reaction-based rat renal carcinogenesis model with an iron chelate, ferric nitrilotriacetate (Fe-NTA), in which catalytic iron induces the Fenton reaction specifically in the renal proximal tubules, presumably after iron reduction. Notably, this probe reacted with Fe(II) but with neither Fe(II)-NTA, Fe(III) nor Fe(III)-NTA in vitro. Prominent red fluorescent color was explicitly observed in and around the lumina of renal proximal tubules 1 h after an intraperitoneal injection of 10-35 mg iron/kg Fe-NTA, which was dose-dependent, according to semiquantitative analysis. The RhoNox-1 signal colocalized with the generation of hydroxyl radicals, as detected by hydroxyphenyl fluorescein (HPF). The results demonstrate the transformation of Fe(III)-NTA to Fe(II) in vivo in the Fe-NTA-induced renal carcinogenesis model. Therefore, this probe would be useful for localizing catalytic Fe(II) in studies using tissues. PMID:24580501

Mukaide, T; Hattori, Y; Misawa, N; Funahashi, S; Jiang, L; Hirayama, T; Nagasawa, H; Toyokuni, S

2014-09-01

202

Molecular nanotechnologies of gelatin-immobilization using macrocyclic metal chelates  

PubMed Central

This article is a review of recent developments in the self-assembled nanostructures based on chelate coordination compounds. Molecular nanotechnologies of self-assembly of 3d-element aza- and thiazametalmacrocyclic complexes that happen in nanoreactors on the basis of metal hexacyanoferrate(II) gelatin-immobilized matrix under their contact with water solutions containing various (N,O,S)-donor atomic ligands and organic compounds having one or two carbonyl groups have been considered in this review. It has been noted that the assortment of macrocyclic metal chelates obtained as a result of using molecular nanotechnologies in such specific conditions considerably differs from the assortment of metal chelates formed at the conditions traditional for chemical synthesis. PMID:24516711

Mikhailov, Oleg V.

2014-01-01

203

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

204

Iron chelating strategies in systemic metal overload, neurodegeneration and cancer.  

PubMed

Iron is a trace element required for normal performance of cellular processes. Because both the deficiency and excess of this metal are dangerous, its absorption, distribution and accumulation must be tightly regulated. Disturbances of iron homeostasis and an increase in its level may lead to overload and neurodegenerative diseases. Phlebotomy was for a long time the only way of removing excess iron. But since there are many possible disadvantages of this method, chelation therapy seems to be a logical approach to remove toxic levels of iron. In clinical use, there are three drugs: desferrioxamine, deferiprone and deferasirox. FBS0701, a novel oral iron chelator, is under clinical trials with very promising results. Developing novel iron-binding chelators is an urgent matter, not only for systemic iron overload, but also for neurodegenerative disorders, such as Parkinson's disease. Deferiprone is also used in clinical trials in Parkinson's disease. In neurodegenerative disorders the main goal is not only to remove iron from brain tissues, but also its redistribution in system. Few chelators are tested for their potential use in neurodegeneration, such as nonhalogeneted derivatives of clioquinol. Such compounds gave promising results in animal models of neurodegenerative diseases. Drugs of possible use in neurodegeneration must meet certain criteria. Their development includes the improvement in blood brain barrier permeability, low toxicity and the ability to prevent lipid peroxidation. One of the compounds satisfying these requirements is VK28. In rat models it was able to protect neurons in very low doses without significantly changing the iron level in liver or serum. Also iron chelators able to regulate activity of monoamine oxidase were tested. Polyphenols and flavonoids are able to prevent lipid peroxidation and demonstrate neuroprotective activity. While cancer does not involve true iron overload, neoplastic cells have a higher iron requirement and are especially prone to its depletion. It was shown, that desferrioxamine and deferasirox are antiproliferative agents active in several types of cancer. Very potent compounds with possible use as anticancer drugs are thiosemicarbazones. They are able to inhibit ribonucleotide reductase, an enzyme involved in DNA synthesis. Because the relationship between the development of overload / neurodegenerative disorders, or cancer, and iron are very complex, comprehension of the mechanisms involved in the regulation of iron homeostasis is a crucial factor in the development of new pharmacological strategies based on iron chelation. In view of various factors closely involved in pathogenesis of such diseases, designing multifunctional metal-chelators seems to be the most promising approach, but it requires a lot of effort. In this perspective, the review summarizes systemic iron homeostasis, and in brain and cancer cells, iron dysregulation in neurodegenerative disease and possible chelation strategies in the treatment of metal systemic overload, neurodegeneration and cancer. PMID:25005181

Gumienna-Kontecka, Elzbieta; Pyrkosz-Bulska, Monika; Szebesczyk, Agnieszka; Ostrowska, Malgorzata

2014-01-01

205

Chelation-controlled addition of organozincs to ?-chloro aldimines.  

PubMed

Nucleophilic additions to ?-chiral ?-halo carbonyl derivatives are well-known to generate Cornforth-Evans products via a nonchelation pathway. What was unprecedented before this report is C-X bonds reversing the diastereoselectivity through coordination to metals during C-C bond-forming reactions (chelation control). Herein we describe chelation control involving C-X bonds in highly diastereoselective additions of organozinc reagents to a variety of ?-chloro aldimines. The unique ability of alkylzinc halide Lewis acids to coordinate to the Cl, N, and O of ?-chloro sulfonyl imine substrates is supported by computational studies. PMID:23003333

Stanton, Gretchen R; Norrby, Per-Ola; Carroll, Patrick J; Walsh, Patrick J

2012-10-24

206

Antibacterial Activities of Iron Chelators against Common Nosocomial Pathogens  

PubMed Central

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

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

2012-01-01

207

Removal of phenol from saline water by polyamine chelating resin.  

PubMed

Removal of phenol from saline water was carried out with chelating resin. A polyamine chelating resin, Diaion CR-20, removed phenol compounds selectively from industrial wastewater containing 2% salt. From saline water containing 20 mg/L phenol, 70% of the phenol was removed. After treatment, phenol was eluted from the resin by aqueous NaOH, and the resin could also be regenerated by heating in air. Diaion CR-20 adsorbed phenol even in the presence of FeCl3, indicating that treatment with this resin of wastewater containing metal can remove phenol and metal cations in a single step. PMID:24185065

Yamada, Arisa; Matsui, Akihiro; Tsuji, Hideyuki

2013-01-01

208

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. PMID:22074910

2011-01-01

209

Oral iron absorption test in patients on CAPD: comparison of ferrous sulfate and a polysaccharide ferric complex.  

PubMed

We prospectively compared the absorption of ferrous sulfate to that of a polysaccharide ferric complex (Niferex) in 5 healthy controls and 7 stable patients on continuous ambulatory peritoneal dialysis (CAPD). All study subjects received an equivalent of 150 mg of elemental iron of either preparation, in a random fashion. After a baseline fasting serum iron level was obtained, the serum iron concentration was measured at 2 h in the control group and at 2 and 4 h in the CAPD patients. One to 2 months later, all study subjects received the alternative iron compound and were studied in an identical manner. A significant rise in serum iron was only observed in the healthy subjects after the ingestion of ferrous sulfate and not Niferex (ferrous sulfate 102 +/- (SE) 9 vs. 142 +/- 7 Mg/dl, p = 0.0005; Niferex 96 +/- (SE) 10 vs. 102 +/- 12 mg/dl; baseline vs. 2 h, respectively). The absorption of both compounds was poor in the patients on CAPD, with the 2- and 4-hour serum iron levels not significantly higher than the baseline values (ferrous sulfate 73 +/- 7 vs. 107 +/- 21 vs. 109 +/- 21 mg/dl, p = NS; Niferex 57 +/- 11 vs. 65 +/- 14 vs. 60 +/- 11 mg/dl, p = NS; baseline vs. 2 vs. 4 h, respectively). Our data suggest that the absorption of both ferrous sulfate and ferric polysaccharide complex is poor in patients on CAPD. PMID:8893143

Tinawi, M; Martin, K J; Bastani, B

1996-01-01

210

Characterization of Jarosite Formed upon Bacterial Oxidation of Ferrous Sulfate in a Packed-Bed Reactor †  

PubMed Central

A packed-bed bioreactor with activated-carbon particles as a carrier matrix material inoculated with Thiobacillus ferrooxidans was operated at a pH of 1.35 to 1.5 to convert ferrous sulfate to ferric sulfate. Despite the low operating pH, trace amounts of precipitates were produced in both the reactor and the oxidized effluent. X-ray diffraction and chemical analyses indicated that the precipitates were well-ordered potassium jarosite. The chemical analyses also revealed a relative deficiency of Fe and an excess of S in the reactor sample compared with the theoretical composition of potassium jarosite. Images PMID:16347799

Grishin, Sergei I.; Bigham, Jerry M.; Tuovinen, Olli H.

1988-01-01

211

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

PubMed Central

The oxidation of ferrous iron (Fe2+) to ferric iron (Fe3+) with dioxygen (O2) by various strains of Thiobacillus ferrooxidans was studied by measuring the rate of O2 consumption at various Fe2+ concentrations and cell concentrations. The apparent Km values for Fe2+ remained constant at different cell concentrations of laboratory strains ATCC 13661 and ATCC 19859 but increased with increasing cell concentrations of mine isolates SM-4 and SM-5. The latter results are explained by the competitive inhibition of the Fe2+-binding site of a cell by other cells in the reaction mixture. Possible mechanisms involving cell surface properties are discussed. PMID:16347904

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

1989-01-01

212

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

213

Stabilization/solidification of waste ferrous sulphate from titanium dioxide production by fluidized bed combustion product.  

PubMed

A treatment procedure to allow the disposal of waste ferrous sulphate was developed. This waste contains sulphuric acid and originates from titanium dioxide production. The process is based on simultaneous neutralization and stabilization/solidification (S/S) of the waste by means of fluidized bed combustion product (FBC-P). The prepared stabilized waste specimens have a solid matrix and their batch leachates display practically neutral pH and also satisfactory conductivity values. The leachate composition is notable in its absence of toxic metals and even iron. PMID:11150128

Vondruska, M; Bednarik, V; Sild, M

2001-01-01

214

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

DOEpatents

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

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

1981-01-01

215

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

216

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

217

Water-soluble, redox-active organometallic calcium chelators.  

PubMed

This paper describes a new series of organometallic water-soluble chelators combining a redox moiety (ferrocene) and a selective Ca2+ chelator (BAPTA) separated by an ethynyl bridge. We report the synthesis and characterization of organometallic derivatives of the BAPTA chelator featuring one (2a) and two ferrocenyl (2b) moieties. Single crystal X-ray structural analysis on these chelators revealed unexpected conformations for the ferrocenyl substituent with respect to the phenyl ring of the BAPTA unit. DFT calculations on a model system of the ferrocenyl-ethynyl-BAPTA molecule were carried out to evaluate the energy separation between the two limiting conformations observed experimentally in the solid state, and to check the effective electronic communication between the binding pocket and the redox probe. The binding affinity of 2a–b for Ca2+, as probed by UV-Vis and cyclic voltammetry, revealed distinct behaviors in the presence of a metal ion depending on whether BAPTA is substituted by one or two ferrocenyl groups. PMID:23037863

Bhattacharyya, Koyel X; Boubekeur-Lecaque, Leïla; Tapsoba, Issa; Maisonhaute, Emmanuel; Schöllhorn, Bernd; Amatore, Christian

2012-12-21

218

Labeling Biomolecules with Radiorhenium - a Review of the Bifunctional Chelators  

PubMed Central

For radiotherapy, biomolecules such as intact antibodies, antibody fragments, peptides, DNAs and other oligomers have all been labeled with radiorhenium (186Re and 188Re). Three different approaches have been employed that may be referred to as direct, indirect and integral labeling. Direct labeling applies to proteins and involves the initial reduction of endogenous disulfide bridges to provide chelation sites. Indirect labeling can apply to most biomolecules and involves the initial attachment of an exogenous chelator. Finally, integral labeling is a special case applying only to small molecules in which the metallic radionuclide serves to link two parts of a biomolecule together in forming the labeled complex. While the number of varieties for the direct and integral radiolabeling approaches is rather limited, a fairly large and diverse number of chelators have been reported in the case of indirect labeling. Our objective herein is to provide an overview of the various chelators that have been used in the indirect labeling of biomolecules with radiorhenium, including details on the labeling procedures, the stability of the radiolabel and, where possible, the influence of the label on biological properties. PMID:17504162

Liu, Guozheng; Hnatowich, Donald J.

2007-01-01

219

Desferrithiocin: a search for clinically effective iron chelators.  

PubMed

The successful search for orally active iron chelators to treat transfusional iron-overload diseases, e.g., thalassemia, is overviewed. The critical role of iron in nature as a redox engine is first described, as well as how primitive life forms and humans manage the metal. The problems that derive when iron homeostasis in humans is disrupted and the mechanism of the ensuing damage, uncontrolled Fenton chemistry, are discussed. The solution to the problem, chelator-mediated iron removal, is clear. Design options for the assembly of ligands that sequester and decorporate iron are reviewed, along with the shortcomings of the currently available therapeutics. The rationale for choosing desferrithiocin, a natural product iron chelator (a siderophore), as a platform for structure-activity relationship studies in the search for an orally active iron chelator is thoroughly developed. The study provides an excellent example of how to systematically reengineer a pharmacophore in order to overcome toxicological problems while maintaining iron clearing efficacy and has led to three ligands being evaluated in human clinical trials. PMID:25207964

Bergeron, Raymond J; Wiegand, Jan; McManis, James S; Bharti, Neelam

2014-11-26

220

Efficacy of reversal of aortic calcification by chelating agents  

PubMed Central

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 ethylene diamine tetraacetic acid (EDTA), diethylene triamine pentaacetic acid (DTPA) and sodium thiosulfate (STS) might reverse elastin calcification by directly removing calcium (Ca) 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) (PLGA) 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; Sinha, Aditi; Vyavahare, Naren

2013-01-01

221

Electrokinetic remediation of concrete: Effect of chelating agents  

Microsoft Academic Search

Contamination of concrete at various nuclear power plants and spent nuclear fuel reprocessing facilities by radionuclides represents a significant problem for the world's nuclear power industries and nuclear waste management. The present publication summarizes the most recently published data on Electrokinetic Remediation (EK) of various concrete installations and advantageous effects of the combination of EK with different chelating agents. The

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

2008-01-01

222

Hydroxamate recognition during iron transport from hydroxamate-iron chelates  

Microsoft Academic Search

Kinetics of radioactive iron transport from three structurally different ; secondary hydroxandate-iron chelates (schizokineniron, produced by Bacillus ; megaterium ATCC 19213; Desferaliron, produced by an actinomycete; and aerobactin-; iron, produced by Aerobacter aerogenes 62-1) revealed that B. megateriurm SK 11 ; (a mutant that cannot synthesize schizokinen) has a specific transport system for ; utilization of ferric hydroxamates with a

A. H. Haydon; W. B. Davis; E. L. Arceneaux; B. R. Byers

1973-01-01

223

SORPTION OF TRACE HEAVY METALS BY THIOL CONTAINING CHELATING RESINS  

Microsoft Academic Search

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 characterisation 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

B. Saha; M. Iglesias; I. W. dimming; M. Streat

2000-01-01

224

?-Aminobutyrohydroxamate resins as stationary phases of chelation ion chromatography  

Microsoft Academic Search

?-Aminobutyrohydroxamate resin and its derivatives were prepared and employed as stationary phases in chelation ion chromatography for the simultaneous determination of trace metal ions in sea water and biological sample. The method consists of preconcentration of a 25ml sea water or biological sample on a ?-aminobutyrohydroxamate resin column; alkali and alkaline earth metal ions are removed from the resin with

Chuen-Ying Liu; N-Ming Lee; Jian-Lian Chen

1998-01-01

225

Scintigraphic monitoring of immunotoxins using radionuclides and heterobifunctional chelators  

SciTech Connect

This patent describes a method for in vivo radioimmunodetection of cytotoxic immunotoxin. It comprises administering internally to a mammal a radio-labeled immunotoxin, wherein a heterobifunctional chelating agent provides a chemical bridge between a radiolabel and a cytotoxic component bound to the antigen-binding component of the immunotoxin, and detecting externally the distribution of the immunotoxin in the mammal.

Reardan, D.; Bernhard, S.

1991-10-22

226

Fluorescence probing of the ferric Fenton reaction via novel chelation.  

PubMed

A new probe-chelator PET dyad was synthesised, which can be used to detect Fe(3+)via fluorescence enhancement to discriminate between Fe(2+) and Fe(3+)via Fenton chemistry involving hydrogen peroxide. This is the first BODIPY which works as a 2?:?1 multiplexer for Fe(3+), Fe(2+) and H2O2. PMID:24247302

Murale, Dhiraj P; Manjare, Sudesh T; Lee, Yoon-Sup; Churchill, David G

2014-01-11

227

Heavy metal stabilization in municipal solid waste incineration flyash using heavy metal chelating agents  

Microsoft Academic Search

Heavy metal chemical stabilization with synthesized heavy metal chelating agent was assessed for flyash from municipal solid waste incinerator. Flyash can contain heavy metals (e.g. Pb, Cd) which can leach. A new kind of heavy metal chelating agent showed more attractive competition than inorganic chemicals in stabilizing flyash. The synthesizing method of this kind of heavy metal chelating agent was

Jiang Jianguo; Wang Jun; Xu Xin; Wang Wei; Deng Zhou; Zhang Yan

2004-01-01

228

Cations reduce antimicrobial efficacy of lysozyme-chelator combinations.  

PubMed

Reduction of the antimicrobial efficacy of lysozyme-chelator combinations against two Escherichia coli O157:H7 strains on addition of mineral salts was studied. The objective of the study was to determine the effect of type and concentration of mono-, di-, and trivalent mineral salts on the antimicrobial effectiveness of lysozyme and various chelators against E. coli O157:H7. Seven salts (Al3+, Ca2+, Fe2+, Fe3+, K+, Mg2+, and Na+) at 1 to 10 mM were added to aqueous solutions of lysozyme and disodium ethylenediamine tetraacetic acid (EDTA), disodium pyrophosphate (DSPP), or pentasodium tripolyphosphate (PSTPP) at pH 6, 7, or 8 and applied to cultures of E. coli O157:H7 strains 932 and H1730. Inhibitory activity of lysozyme chelator combinations against both strains was completely lost after addition of > or = 1 mM Ca2+ and Mg2+ at pH 7 and 8. At pH 6, antimicrobial activity of lysozyme-EDTA against both strains was retained in the presence of calcium or magnesium cations. DSPP-lysozyme inhibited strain H1730 at pH 6 despite the presence of Mg2+. Concentrations above 4 mM Fe2+ neutralized activity of all lysozyme-chelator combinations. Reversal of inhibition by lysozyme-chelator complexes by the monovalent Na+ and K+ ions depended on E. coli O157:H7 strain type. Neither monovalent cation reversed inhibition of strain 932. However, Na+ and K+ reversed lysozyme-chelator inhibition of strain H1730. The addition of > or = 1 mM Fe3+ or Al3+ was effective in reversing inhibition of both strains by lysozyme and EDTA at pH 6, 7, and 8. Isothermal titration calorimetry was used to determine the amount of ion-specific competitive binding of free cations by EDTA-lysozyme combinations. A mechanistic model for the antimicrobial functionality of chelator-lysozyme combinations is proposed. PMID:14968960

Boland, J S; Davidson, P M; Bruce, B; Weiss, J

2004-02-01

229

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

230

Copper chelators: chemical properties and bio-medical applications.  

PubMed

Copper is present in different concentrations and chemical forms throughout the earth crust, surface and deep water and even, in trace amounts, in the atmosphere itself. Copper is one of the first metals used by humans, the first artifacts dating back 10,000 years ago. Currently, the world production of refined copper exceeds 16,000 tons/year. Copper is a micro-element essential to life, principally for its red-ox properties that make it a necessary cofactor for many enzymes, like cytochrome-c oxidase and superoxide dismutase. In some animal species (e.g. octopus, snails, spiders, oysters) copper-hemocyanins also act as carriers of oxygen instead of hemoglobin. However, these red-ox properties also make the pair Cu(+)/Cu(2+) a formidable catalyst for the formation of reactive oxygen species, when copper is present in excess in the body or in tissues. The treatment of choice in cases of copper overloading or intoxication is the chelation therapy. Different molecules are already in clinical use as chelators or under study or clinical trial. It is worth noting that chelation therapy has also been suggested to treat some neurodegenerative diseases or cardiovascular disorders. In this review, after a brief description of the homeostasis and some cases of dyshomeostasis of copper, the main (used or potential) chelators are described; their properties in solution, even in relation to the presence of metal or ligand competitors, under physiological conditions, are discussed. The legislation of the most important Western countries, regarding both the use of chelating agents and the limits of copper in foods, drugs and cosmetics, is also outlined. PMID:24934357

Tegoni, M; Valensin, D; Toso, L; Remelli, M

2014-01-01

231

Iron chelation studies using desferrioxamine and the potential oral chelator, 1,2-dimethyl-3-hydroxypyrid-4-one, in normal and iron loaded rats.  

PubMed Central

A novel iron chelator, 1,2-dimethyl-3-hydroxypyrid-4-one, and desferrioxamine were compared for their ability to remove iron and for their site of action in iron release in rats. Repeated intraperitoneal injections of the chelators in rats with widespread tissue labelling by 59Fe derived from transferrin showed comparable 59Fe mobilisation by each chelator in normal and iron loaded rats. Specific labelling of a chelatable "cold" iron pool in hepatocytes by 59Fe derived from ferritin showed this pool to be equally accessible to parenteral doses of both chelators and also to oral 1,2-dimethyl-3-hydroxypyrid-4-one, which is an effective oral iron chelating agent that removes iron from parenchymal cells. This and other alpha-ketohydroxypyridines need further development as potential therapeutic agents in human iron overload. PMID:3584483

Kontoghiorghes, G J; Sheppard, L; Hoffbrand, A V; Charalambous, J; Tikerpae, J; Pippard, M J

1987-01-01

232

Bioleaching of realgar by Acidithiobacillus ferrooxidans using ferrous iron and elemental sulfur as the sole and mixed energy sources.  

PubMed

The characteristics of the bioleaching of realgar by Acidithiobacillus ferrooxidans BY-3 (A. ferrooxidans) were investigated in this work. We examined the effects of using ferrous iron and elemental sulfur as the sole and mixed energy sources on the bioleaching of realgar. Under all experimental conditions, A. ferrooxidans BY-3 significantly enhanced the dissolution of realgar. Moreover, arsenic was more efficiently leached using A. ferrooxidans BY-3 in the presence of ferrous iron than in other culture conditions. A high concentration of arsenic was observed in the absence of alternative energy sources. This concentration was higher than that in cultures with sulfur only and lower than that in cultures with ferrous iron and sulfur. Linear or nonlinear models best fit the experimental data; the nonlinear model exhibited the dual effects of dissolution and removal on the bioleaching of realgar, whereas the linear model only applied to situations of slow bioleaching rather than removal. PMID:21146407

Chen, Peng; Yan, Lei; Leng, Feifan; Nan, Wenbing; Yue, Xiaoxuan; Zheng, Yani; Feng, Na; Li, Hongyu

2011-02-01

233

Efficient and stereocontrolled synthesis of 1,2,4-trioxolanes useful for ferrous iron-dependent drug delivery.  

PubMed

Ferrous iron-promoted reduction of a hindered peroxide bond underlies the antimalarial action of the 1,2,4-trioxane artemisinin and the 1,2,4-trioxolane arterolane. In appropriately designed systems, a 1,2,4-trioxolane ring can serve as a trigger to realize ferrous iron-dependent and parasite-selective drug delivery, both in vitro and in vivo. A stereocontrolled, expeditious (three steps), and efficient (67-71% overall yield) synthesis of 1,2,4-trioxolanes possessing the requisite 3? substitution pattern that enables ferrous iron-dependent drug delivery is reported. The key synthetic step involves a diastereoselective Griesbaum co-ozonolysis reaction to afford primarily products with a trans relationship between the 3? substituent and the peroxide bridge, as confirmed by X-ray structural analysis of a 3?-substituted 4-nitrobenzoate analogue. PMID:25331549

Fontaine, Shaun D; DiPasquale, Antonio G; Renslo, Adam R

2014-11-01

234

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

235

Effects of dissolved low molecular weight organic acids on oxidation of ferrous iron by Acidithiobacillus ferrooxidans.  

PubMed

A few researchers have reported on work concerning bioleaching of heavy-metal-contaminated soil using Acidithiobacillus ferrooxidans, since this acidophile is sensitive to dissolved low molecular weight (LMW) organic acids. Iron oxidation by A. ferrooxidans R2 as well as growth on ferrous iron was inhibited by a variety of dissolved LMW organic acids. Growth experiments with ferrous iron as an oxidant showed that the inhibition capability sequence was formic acid>acetic acid>propionic acid>oxalic acid>malic acid>citric acid. The concentrations that R2 might tolerate were formic acid 0.1mmolL(-1) (2mmolkg(-1)soil), acetic and propionic acids 0.4mmolL(-1) (8mmolkg(-1)soil), oxalic acid 2.0mmolL(-1) (40mmolkg(-1)soil), malic acid 20mmolL(-1) (400mmolkg(-1)soil), citric acid 40mmolL(-1) (800mmolkg(-1)soil), respectively. Although R2 was sensitive to organic acids, the concentrations of LMW organic acids in the contaminated soils were rather lower than the tolerable levels. Hence, it is feasible that R2 might be used for bioleaching of soils contaminated with metals or metals coupled with organic compounds because of the higher concentrations of LMW organic acids to which R2 is tolerant. PMID:18554786

Ren, Wan-Xia; Li, Pei-Jun; Zheng, Le; Fan, Shu-Xiu; Verhozina, V A

2009-02-15

236

Degradation of trichloroethylene in aqueous solution by calcium peroxide activated with ferrous ion.  

PubMed

The application of calcium peroxide (CaO2) activated with ferrous ion to stimulate the degradation of trichloroethylene (TCE) was investigated. The experimental results showed that TCE could be completely degraded in 5min at a CaO2/Fe(II)/TCE molar ratio of 4/8/1. Probe compound tests demonstrated the presence of reactive oxygen species HO and O2(-) in CaO2/Fe(II) system, while scavenging tests indicated that HO was the dominant active species responsible for TCE removal, and O2(-) could promote TCE degradation in CaO2/Fe(II) system. In addition, the influences of initial solution pH and solution matrix were evaluated. It suggested that the elevation of initial solution pH suppressed TCE degradation. Cl(-) had significant scavenging effect on TCE removal, whereas HCO3(-) of high concentration showed favorable function. The influences of NO3(-) and SO4(2-) could be negligible, while natural organic matter (NOM) had a negative effect on TCE removal at a relatively high concentration. The results demonstrated that the technique of CaO2 activated with ferrous ion is a highly promising technique in in situ chemical oxidation (ISCO) remediation in TCE contaminated sites. PMID:25463240

Zhang, Xiang; Gu, Xiaogang; Lu, Shuguang; Miao, Zhouwei; Xu, Minhui; Fu, Xiaori; Qiu, Zhaofu; Sui, Qian

2015-03-01

237

Emission of the greenhouse gas nitrous oxide resulting from ferrous iron disturbance of denitrification  

NASA Astrophysics Data System (ADS)

A chemical pathway invoked by reaction of ferrous iron (Fe2+) with nitrite (NO2-) can short circuit denitrification and potentially increase production of nitrous oxide (N2O). Here, we report on the NO2- reaction with Fe(II) -- chemodenitrification--in anoxic batch incubations at neutral pH. Aqueous Fe2+ and NO2- reacted rapidly and produced N2O, which is autocatalyzed by the Fe(III) (hydr)oxide mineral products. Lepidocrotite and goethite, identified by synchrotron x-ray diffraction (XRD) and extended x-ray absorption fine structure (EXAFS) spectroscopy, were observed with poorly crystalline two-line ferrihydrite increasing in abundance later in the reaction sequence. The mineral assemblages result in an autocatalytic reaction within ferrous-iron induced chemodenitrification. Based on the similarity of apparent rate constants in the presence of different minerals, we hypothesize that the type of ferric (hydr)oxide does not have a great effect on chemodenitrification rates. We also reveal that the isotopic composition of chemically produced N2O differs from biologically (denitrification) produced N2O --a finding important for determine the source of N2O emission from natural systems.

Jones, L.; Peters, B. D.; Lezama, J.; Casciotti, K. L.; Fendorf, S. E.

2013-12-01

238

Absorption of iron polymaltose and ferrous sulphate in rats and humans. A comparative study.  

PubMed

Free iron in the circulation in contrast to iron complexed with protein or carbohyrdate, is intensely toxic. The annual morbidity and mortality from accidental overdose with iron salts is significant and has directed attention to the evaluation of safer forms of therapy. Comparative studies between oral ferrous sulphate and iron polymaltose in rats established an LD100 of 350 mg/kg for the salt, whereas neither morbidity nor mortality could be produced in doses exceeding 1 000 mg/kg for the complex. Bio-availability of iron from salt and complex for haemoglobin synthesis was then compared both in rats and in man with a twin-isotope technique. In experimental animals and in the human studies, venesected individuals were used to reproduce the iron deficiency state where treatment would be indicated. It was concluded that bioavailability is comparable for therapeutic doses of ferrous sulphate and iron polymaltose in iron-deficient subjects. The marginally lower absorption of complex was offset by a greater degree of gastrointestinal tract tolerance; the wide margin of safety may be of importance in reducing the danger of accidental iron overdose. PMID:472964

Jacobs, P; Wormald, L A; Gregory, M C

1979-06-23

239

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

PubMed

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

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

2011-02-01

240

Erythrocytes: Better Tolerance of Iron Polymaltose Complex Compared with Ferrous Sulphate in the Treatment of Anaemia.  

PubMed

BackgroundAbsolute iron deficiency, irrespective of aetiology, remains a major and worldwide cause of morbidity. After correction of the causative lesion, reconstitution of haemoglobin level and body iron stores is traditionally achieved with oral administration of ferrous salts. The latter have significant gastrointestinal tract side-effects that, in the short-term, may impair compliance. With protracted administration these products can cause lipid peroxidation which, in turn, may accelerate atherogenesis. An alternative formulation is an iron polymaltose complex where animal data supported a promoting effect of glycerophosphate. Setting and Trial Design This was a single-centre, open, randomised, multidose four treatment parallel group study. A standard dose of ferric polymaltose complex with two differing levels of glycerophosphate was compared with an equivalent amount of iron supplied as ferrous sulphate in anaemic volunteer blood donors. The endpoints were rate of haemoglobin rise and re-expansion of body iron stores reflected in blood ferritin concentration, as well as percentage saturation of transferrin. Secondary observations were changes in the proportion of hypochromic red cells during the course of treatment, erythropoietin levels and tolerability of the two formulations. Results Outcome in the rat model suggested that the utilisation of iron from polymaltose might be enhanced by glycerophosphate. However, in donors this difference was not evident and, accordingly, the data from the three polymaltose groups combined and compared to those receiving ferrous sulphate. The rate at which haemoglobin level improved, red cell indices returned to normal, and the number of hypochromic and microcytic red cells fell was not significantly different between the groups. Similarly the serum iron, percentage saturation of transferrin and red cell ferritin were comparable. In contrast the serum ferritin levels were higher for those receiving ferrous sulphate. Additionally, side-effects were significantly more frequently encountered with the latter preparation. Conclusion These data demonstrate that the addition of glycerophosphate, observed to be beneficial in rats, did not occur in humans. Secondly, in the blood donors, equivalent amounts of iron provided as the polymaltose, with or without glycerophosphate or ferrous sulphate, corrected haemoglobin concentration and morphologically abnormal erythropoiesis at comparable rates. Similarly iron stores are replenished to an equivalent extent as seen in the matching percentage saturation of transferrin and red cell ferritin levels. Interestingly, there is a discrepancy in the serum ferritin which is higher with the salt and this may reflect oxidative stress. Thirdly, corresponding efficacy can be achieved with better patient tolerance for the complex. Finally it is postulated that the iron polymaltose complex formulation more closely approximates the way in which enterocytes handle dietary iron and thus physiologic regulatory mechanisms would be expected to reciprocally slow down absorption as stores expand. Logically, therefore and, if confirmed, the latter finding suggests that this formulation may have a potential role in longer-term supplementation programmes. PMID:11399604

Jacobs, PETER; Wood, LUCILLE; Bird, ARTHUR R.

2000-01-01

241

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...

242

Comparison of a combination ferrous fumarate product and a polysaccharide iron complex as oral treatments of iron deficiency anemia: a Taiwanese study.  

PubMed

Despite efforts to improve iron supplements for iron deficiency anemia, there is no consensus on products that balance efficacy, safety and tolerability, and cost. Ferrous products are effective, but they are associated with more gastrointestinal side effects than ferric products. Ferric products tend to have lower absorption. We present results from a 12-week study that randomized 72 people with uncomplicated iron deficiency anemia to receive a ferrous iron supplement (Ferall, a combination of ferrous fumarate with ascorbic acid, folic acid, and cyanocobalamin) or a ferric iron polysaccharide complex (Niferex, ferro-glycine sulfate) plus ascorbic acid. The ferrous product was significantly more effective, the primary and secondary endpoints including changes in levels of hemoglobin and serum ferritin. There was a slightly higher frequency of gastrointestinal side effects in patients taking the ferrous product, but both supplements were well tolerated. No participant withdrew from the study because of side effects. We concluded that the ferrous product is safe and effective for use in uncomplicated iron deficiency anemia. The lack of direct comparison between single-agent ferrous fumarate and the combination ferrous product limited interpretation of results in terms of possible effects due to other components, such as ascorbic acid. PMID:15646652

Liu, Ta-Chih; Lin, Shen-Fung; Chang, Chao-Sung; Yang, Wen-Chi; Chen, Tyen-Po

2004-12-01

243

Fractionation and identification of Alaska pollock skin collagen-derived mineral chelating peptides.  

PubMed

Peptides with the ability to chelate dietary minerals have been reported to have potential as functional food ingredients. A collagen tryptic hydrolysate (CTH), previously shown to chelate iron, was further investigated for the presence of Ca, Fe and Cu chelating peptides. Sequential purification steps, including immobilised metal affinity chromatography (IMAC) and gel permeation chromatography (GPC) were employed for the separation of chelating peptides. GPC analysis showed that the mineral chelating peptides were mainly between 500 and 2000 Da. Subsequent identification was carried out using UPLC-ESI-QTOF MS/MS. Overall, 10 sequences were identified as potential chelating peptides. The Ca, Fe and Cu chelating activity of GPAGPHGPPG was 11.52±2.23 nmol/?mol, 1.71±0.17 nmol/?mol and 0.43±0.02 ?mol/?mol, respectively. This study identifies collagen as a good source of peptides with potential applications as functional ingredients in the management of mineral deficiencies. PMID:25466056

Guo, Lidong; Harnedy, Pádraigín A; O'Keeffe, Martina B; Zhang, Li; Li, Bafang; Hou, Hu; FitzGerald, Richard J

2015-04-15

244

Incidence of ototoxicity in pediatric patients with transfusion-dependent thalassemia who are less well-chelated by mono- and combined therapy of iron chelating agents.  

PubMed

Ototoxicity due to iron chelation therapy, especially deferoxamine (DFO), is frequently observed in patients who have a higher chelation index (>0.025). However, there is limited data on patients who are less well-chelated and on other chelating regimens, including deferiprone (L1), deferasirox (DFX), and a combination of DFO and L1. To determine the incidence of ototoxicity from iron chelators, we retrospectively analyzed our clinical records from January 1997 to December 2010. All transfusion-dependent thalassemia (TDT) patients received iron chelation therapy with mono DFX, DFO, L1, or a combination. All patients underwent routine otolaryngologic examination and pure-tone audiometry before starting each chelation regimen and were regularly followed every 6 months. One hundred thalassemic patients were enrolled and analyzed (48 males and 52 females), with a mean age of 12.11?±?4.48 years (range 2.5-22.5 years). Total summative duration of iron chelation therapy in all patients was 596.50 years. Nine patients were found to have conductive hearing loss. Sensorineural hearing loss (SNHL) was identified in seven patients but only four were determined to be associated with iron chelators; three patients were detected while undergoing DFO therapy and one patient with L1 therapy. None of patients undergoing DFO therapy had reached over the levels of chelation index. In our resource-limited setting with poor treatment compliance, there was a rather low incidence of ototoxicity after exposure to iron chelators. However, a routine audiometry remains recommended for early detection and intervention since SNHL still develops and results in a long-term morbidity. PMID:25051423

Tanphaichitr, Archwin; Kusuwan, Thisarat; Limviriyakul, Siriporn; Atipas, Suvajana; Pooliam, Julaporn; Sangpraypan, Tuangrat; Tanphaichitr, Voravarn S; Viprakasit, Vip

2014-01-01

245

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

246

Improved paramagnetic chelate for molecular imaging with MRI  

NASA Astrophysics Data System (ADS)

The relaxivity and transmetallation of two lipophilic paramagnetic chelates incorporated onto perfluorocarbon nanoparticles, i.e., gadolinium-methoxy-tetraazacyclododecane-tetraacetic acid phosphatidylethanolamine (Gd-MeO-DOTA-PE) and gadolinium-methoxy-tetraazacyclododecane-tetraacetic acid triglycine phosphatidylethanolamine (Gd-MeO-DOTA-triglycine-PE (Gd-MeO-DOTA-triglycine-PE)), were compared to a prototypic gadolinium-diethylene-triamine-pentaacetic acid bis-oleate (Gd-DTPA-BOA) paramagnetic formulation. Nanoparticles with MeO-DOTA-based chelates demonstrated higher relaxivity (40% higher for Gd-MeO-DOTA-PE and 55% higher for Gd-MeO-DOTA-triglycine-PE) and less transmetallation than the original Gd-DTPA-BOA-based agent.

Winter, Patrick; Athey, Phillip; Kiefer, Garry; Gulyas, Gyongyi; Frank, Keith; Fuhrhop, Ralph; Robertson, David; Wickline, Samuel; Lanza, Gregory

2005-05-01

247

Lanthanides caged by the organic chelates; structural properties  

NASA Astrophysics Data System (ADS)

The structure, in particular symmetry, geometry and morphology of organic chelates coordinated with the lanthanide ions are analyzed in the present review. This is the first part of a complete presentation of a theoretical description of the properties of systems, which are widely used in technology, but most of all, in molecular biology and medicine. The discussion is focused on the symmetry and geometry of the cages, since these features play a dominant role in the spectroscopic activity of the lanthanides caged by organic chelates. At the same time, the spectroscopic properties require more formal presentation in the language of Racah algebra, and deserve a separate analysis. In addition to the parent systems of DOTA, DOTP, EDTMP and CDTMP presented here, their modifications by various antennas are analyzed. The conclusions that have a strong impact upon the theory of the energy transfer and the sensitized luminescence of these systems are based on the results of numerical density functional theory calculations.

Smentek, Lidia

2011-04-01

248

Iron overload and chelation therapy in myelodysplastic syndromes.  

PubMed

Iron overload remains a concern in MDS patients especially those requiring recurrent blood transfusions. The consequence of iron overload may be more relevant in patients with low and intermediate-1 risk MDS who may survive long enough to experience such manifestations. It is a matter of debate whether this overload has time to yield organ damage, but it is quite evident that cellular damage and DNA genotoxic effect are induced. Iron overload may play a critical role in exacerbating pre-existing morbidity or even unmask silent ones. Under these circumstances, iron chelation therapy could play an integral role in the management of these patients. This review entails an in depth analysis of iron overload in MDS patients; its pathophysiology, effect on survival, associated risks and diagnostic options. It also discusses management options in relation to chelation therapy used in MDS patients and the impact it has on survival, hematologic response and organ function. PMID:24529413

Temraz, Sally; Santini, Valeria; Musallam, Khaled; Taher, Ali

2014-07-01

249

Removal of cadmium from fish sauce using chelate resin.  

PubMed

Fish sauce that is prepared from squid organs contains cadmium (Cd), which may be present at hazardous concentrations. Cd molecules are predominantly protein bound in freshly manufactured fish sauce, but are present in a liberated form in air-exposed fish sauce. In the present study, we developed a new method for removing both Cd forms from fish sauce using chelate resin and a previously reported tannin treatment. Sixteen-fold decreases in Cd concentrations were observed (0.78-0.05mg/100mL) following the removal of liberated Cd using chelate resin treatment, and the removal of protein-bound Cd using tannin treatment. Major nutritional components of fish sauce were maintained, including free amino acids and peptides, and angiotensin I-converting enzyme inhibitory and antioxidant activities. PMID:25466035

Sasaki, Tetsuya; Araki, Ryohei; Michihata, Toshihide; Kozawa, Miyuki; Tokuda, Koji; Koyanagi, Takashi; Enomoto, Toshiki

2015-04-15

250

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

251

Lanthanides caged by the organic chelates; structural properties.  

PubMed

The structure, in particular symmetry, geometry and morphology of organic chelates coordinated with the lanthanide ions are analyzed in the present review. This is the first part of a complete presentation of a theoretical description of the properties of systems, which are widely used in technology, but most of all, in molecular biology and medicine. The discussion is focused on the symmetry and geometry of the cages, since these features play a dominant role in the spectroscopic activity of the lanthanides caged by organic chelates. At the same time, the spectroscopic properties require more formal presentation in the language of Racah algebra, and deserve a separate analysis. In addition to the parent systems of DOTA, DOTP, EDTMP and CDTMP presented here, their modifications by various antennas are analyzed. The conclusions that have a strong impact upon the theory of the energy transfer and the sensitized luminescence of these systems are based on the results of numerical density functional theory calculations. PMID:21422507

Smentek, Lidia

2011-04-13

252

Iron chelates: a challenge to chemists and Mössbauer spectroscopists  

NASA Astrophysics Data System (ADS)

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

Homonnay, Z.; Szilágyi, P. Á.; Vértes, A.; Kuzmann, E.; Sharma, V. K.; Molnár, G.; Bousseksou, A.; Grenèche, J.-M.; Brausam, A.; Meier, R.; van Eldik, R.

2008-02-01

253

Dissolution of Nickel Ferrite in Aqueous Solutions Containing Oxalic Acid and Ferrous Salts.  

PubMed

The dissolution of nickel ferrite in oxalic acid and in ferrous oxalate-oxalic acid aqueous solution was studied. Nickel ferrite was synthesized by thermal decomposition of a mixed tartrate; the particles were shown to be coated with a thin ferric oxide layer. Dissolution takes place in two stages, the first one corresponding to the dissolution of the ferric oxide outer layer and the second one being the dissolution of Ni(1.06)Fe(1.96)O(4). The kinetics of dissolution during this first stage is typical of ferric oxides: in oxalic acid, both a ligand-assisted and a redox mechanism operates, whereas in the presence of ferrous ions, redox catalysis leads to a faster dissolution. The rate dependence on both oxalic acid and on ferrous ion is described by the Langmuir-Hinshelwood equation; the best fitting corresponds to K(1)(ads)=25.6 mol(-1) dm(-3) and k(1)(max)=9.17x10(-7) mol m(-2) s(-1) and K(2)(ads)=37.1x10(3) mol(-1) dm(-3) and k(2)(max)=62.3x10(-7) mol m(-2) s(-1), respectively. In the second stage, Langmuir-Hinshelwood kinetics also describes the dissolution of iron and nickel from nickel ferrite, with K(1)(ads)=20.8 mol(-1) dm(3) and K(2)(ads)=1.16x10(5) mol(-1) dm(3). For iron, k(1)(max)=1.02x10(-7) mol of Fe m(-2) s(-1) and k(2)(max)=2.38x10(-7) mol of Fe m(-2) s(-1); for nickel, the rate constants k(1)(max) and k(2)(max) are 2.4 and 1.79 times smaller, respectively. The factor 1.79 agrees nicely with the stoichiometric ratio, whereas the factor 2.4 implies the accumulation of some nickel in the residual particles. The rate of nickel dissolution in oxalic acid is higher than that in bunsenite by a factor of 8, whereas hematite is more reactive by a factor of 9 (in the absence of Fe(II)) and 27 (in the presence of Fe (II)). It may be concluded that oxalic acid operates to dissolve iron, and the ensuing disruption of the solid framework accelerates the release of nickel. Copyright 2000 Academic Press. PMID:11254279

Figueroa, Carlos A.; Sileo, Elsa E.; Morando, Pedro J.; Blesa, Miguel A.

2000-05-15

254

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

PubMed

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

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

2012-11-01

255

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. PMID:22101631

Eckes, Ellen J.

2011-01-01

256

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. PMID:24251381

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

2014-01-01

257

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

258

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

259

Novel 99 m Tc radiopharmaceuticals with bifunctional chelating agents  

Microsoft Academic Search

Today the main radionuclide used for preparing radiopharmaceuticals throughout the world is 99m\\u000a Tc, thanks to its optimal nuclear-physical characteristics and ready availability. Several approaches are used for tethering\\u000a this radionuclide to biomolecules (peptides, antibodies, etc.); one of them involves the use of so-called bifunctional chelating\\u000a agents (BCAs). These compounds are capable both of binding 99m\\u000a Tc and of linking

A. Ya. Maruk; A. B. Bruskin; G. E. Kodina

2011-01-01

260

Chelate-Assisted Heavy Metal Movement Through the Root Zone  

NASA Astrophysics Data System (ADS)

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

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

2001-12-01

261

Occurrence of hydroxamate siderophore iron chelators in soils  

Microsoft Academic Search

Although iron is abundant in soils (1-6%), it is often unavailable to plants because its solubility is dependent on pH and controlled by the low solubility of ferric oxides. Iron availability to plant roots may thus depend on organic chelators which Lindsay reports would maintain an adequate iron supply by diffusion and mass flow at concentrations as low as 10-8

P. E. Powell; G. R. Cline; C. P. P. Reid; P. J. Szaniszlo

1980-01-01

262

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

263

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...

264

Reclamation of a bare industrial area contaminated by non-ferrous metals: In situ metal immobilization and revegetation  

Microsoft Academic Search

To reduce the environmental impact of a 135-ha bare industrial area with a highly phytotoxic soil contaminated by non-ferrous metals, a rehabilitation strategy was developed, aimed at the restoration of a vegetation cover. Two different techniques to overcome the high phytotoxicity of the soil were first evaluated on a laboratory scale: reduction of soil phytotoxicity by the addition of a

J. Vangronsveld; F. Van Assche; H. Clijsters

1995-01-01

265

Bioavailability and the mechanisms of intestinal absorption of iron from ferrous ascorbate and ferric polymaltose in experimental animals  

Microsoft Academic Search

The comparative bioavailability from matching quantities of iron in the form of ferrous ascorbate or ferric polymaltose was defined in rats. Studies were carried out in the intact animals under basal conditions and also when requirements for this metal were either increased or decreased by manipulating stores or erythropoietic activity. No significant difference was found in the total quantity of

G. Johnson; P. Jacobs

1990-01-01

266

IMPROVEMENT OF MAGNETICALLY SEPARATED FERROUS CONCENTRATE BY SHREDDING: A PERFORMANCE TEST. TEST NO. 4.07, RECOVERY 1, NEW ORLEANS  

EPA Science Inventory

This report describes a series of test runs in which ferrous product magnetically recovered from municipal waste was further shredded in a small (50 hp) hammermill to free attached or entrapped contaminant. A belt magnet was then used to separate metal from the liberated contamin...

267

Oral Iron Absorption Test in Patients on CAPD: Comparison of Ferrous Sulfate and a Polysaccharide Ferric Complex  

Microsoft Academic Search

We prospectively compared the absorption of ferrous sulfate to that of a polysaccharide ferric complex (Niferex®) in 5 healthy controls and 7 stable patients on continuous ambulatory peritoneal dialysis (CAPD). All study subjects received an equivalent of 150 mg of elemental iron of either preparation, in a random fashion. After a baseline fasting serum iron level was obtained, the serum

Mohammad Tinawi; Kevin J. Martin; Bahar Bastani

1996-01-01

268

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 ...

269

Characterization of arsenopyrite oxidizing Thiobacillus. Tolerance to arsenite, arsenate, ferrous and ferric iron.  

PubMed

Two strains of Thiobacillus, T. ferrooxidans and T. thiooxidans, have been isolated from a bacterial inoculum cultivated during a one-year period in a 1001 continuous laboratory pilot for treatment of an arsenopyrite/pyrite concentrate. The optimum pH for the growth of both strains has been found to be between 1.7 and 2.5. Because of the high metal toxicity in bioleach pulps, the tolerance of T. ferrooxidans and T. thiooxidans with respect to iron and arsenic has been studied. The growth of both strains is inhibited with 10 g/l of ferric ion, 5 g/l of arsenite and 40 g/l of arsenate. 20 g/l of ferrous iron is toxic to T. ferrooxidans but 30 g/l is necessary to impede the growth of T. thiooxidans. PMID:2191624

Collinet, M N; Morin, D

1990-05-01

270

Mechanism of formation of magnetite from ferrous hydroxide in aqueous corrosion processes  

NASA Astrophysics Data System (ADS)

The stoichiometric conditions for the formation of ferrous hydroxide Fe(OH)2, by mixing Fe2+ ions with caustic soda NaOH, leads by oxidation to magnetite, irrelevant of the foreign anions, e.g. Cl- or SO4 2-, as demonstrated from Mössbauer spectroscopy. The electrochemical potential Eh and pH value of the initial conditions correspond to the drastic change from basic to acidic medium, observed when varying the initial Fe2+/OH- ratio. Mössbauer analysis of the end products of oxidation at various temperatures shows that magnetite is only obtained at stoichiometry at very low temperature, but extends off stoichiometry at higher temperatures. The mechanism of formation of magnetite through an intermediate compound is discussed.

Olowe, A. A.; Rezel, D.; Génin, J. M. R.

1989-03-01

271

In situ synthesis of TiC reinforcements in ferrous matrix  

SciTech Connect

The addition of ceramic particles to ferrous matrix dramatically changes the properties of the alloy and consequently its behavior in services. By judicious selection of hard carbides such as TiC in iron matrix, it is possible to design metal matrix composites which can withstand high abrasive wear environments. In this paper the authors highlight a novel in situ technique of producing TiC reinforcements in iron matrix. The paper also discusses the highly exothermic chemical reaction of TiC formation which is moderated by the availability of carbon in the molten metal. Shrinking core model to explain the reaction paths, solidification rate and rate limiting steps in the formation of TiC are proposed. The paper concludes with the definite note on the crystallographic growth direction of in situ produced TiC in the matrix.

Raghunath, C.; Bhat, M.S. [Univ. of Arizona, Tucson, AZ (United States). Dept. of Materials Science and Engineering

1995-08-01

272

Simulation study of the ferrous ferric electron transfer at a metal--aqueous electrolyte interface  

SciTech Connect

We report a new simulation study of the rate of ferrous--ferric electron transfer at a metal electrolyte interface. In contrast with earlier work, new features in our study include a detailed account of the effects of the field associated with the charging of the electrode, inclusion of entropic effects in the calculated free energy barriers, and a study of the dependence of the relevant free energy surfaces on the distance of the ion from the electrode. The qualitative picture of the reaction mechanism which emerges is significantly more detailed than that in earlier work. The dominant factors in determining the rate and mechanisms of electron transfer are the distance dependence of the work function of the metal, the redox species concentration profile, and the electronic matrix element. Calculated free energy barriers are consistent with experimentally measured ones. We also estimate the equilibrium potential for this reaction from the model, and find it to be consistent with the experimental equilibrium potential.

Smith, B.B.; Halley, J.W. (School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States))

1994-12-15

273

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

PubMed Central

Aerobes and anaerobes alike express a plethora of essential iron enzymes; in the resting state, the iron atom(s) in these proteins are in the ferrous state. For aerobes, ferric iron is the predominant environmental valence form which, given ferric iron’s aqueous chemistry, occurs as ‘rust’, insoluble, bio-inert polymeric ferric oxide that results from the hydrolysis of [Fe(H2O)6]3+. Mobilizing this iron requires bio-ferrireduction which in turn requires managing the rapid autoxidation of the resulting FeII which occurs at pH > 6. This review examines the aqueous redox chemistry of iron and the mechanisms evolved in aerobes to suppress the ‘rusting out’ of FeIII and the ROS-generating autoxidation of FeII so as to make this metal ion available as the most ubiquitous prosthetic group in metallobiology. PMID:23264695

Kosman, Daniel J.

2012-01-01

274

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

275

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

276

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

277

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

PubMed

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

Delangle, Pascale; Mintz, Elisabeth

2012-06-01

278

Zinc deficiency in wheat genotypes grown in conventional and chelator-buffered nutrient solutions  

Microsoft Academic Search

Chelator-buffered nutrient solutions have been used extensively in studying plant–micronutrient relationships, but the effects of the chelator on plants are poorly understood. This study compared responses to Zn deficiency of two wheat genotypes (Triticum aestivum, cv. Aroona, and T. turgidum L. conv. durum, cv. Durati) grown in conventional and chelator-buffered nutrient solutions. With the same low activity of Zn2+ in

Z. Rengel

1999-01-01

279

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

280

Di-macrocyclic terephthalamide ligands as chelators for the PET radionuclide zirconium-89.  

PubMed

The development of bifunctional chelators (BFCs) which can stably chelate zirconium-89 ((89)Zr) while being conjugated to targeting molecules is an area of active research. Herein we report the first octadentate terephthalamide ligands, which are easily radiolabeled with (89)Zr and are highly stable in vitro. They represent a novel class of chelators, which are worthy of further development as BFCs for (89)Zr. PMID:25556851

Pandya, Darpan N; Pailloux, Sylvie; Tatum, David; Magda, Darren; Wadas, Thaddeus J

2015-01-27

281

Synthesis and antioxidant evaluation of some novel ortho-hydroxypyridine-4-one iron chelators  

PubMed Central

A series of ortho-hydroxypyridine-4-ones were prepared in high yields and evaluated for antioxidant and iron chelating activities. N1-H hydroxypyridinones Va, Vb, and Ve were the best radical scavengers in DPPH free radical scavenging assay. Compound Vb was proved to be the most potent compound in hydrogen peroxide scavenging assay. All of the synthesized compounds had very close chelating ability, compounds containing N1-CH3 hydroxypyridinone ring were stronger chelating agents. PMID:23181095

Mohammadpour, M.; Sadeghi, A.; Fassihi, A.; Saghaei, L.; Movahedian, A.; Rostami, M.

2012-01-01

282

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

283

Effect of metal chelators on the oxidative stability of model wine.  

PubMed

Oxidation is a major problem with respect to wine quality, and winemakers have few tools at their disposal to control it. In this study, the effect of exogenous Fe(II) (bipyridine; Ferrozine) and Fe(III) chelators (ethylenediaminetetraacetic acid, EDTA; phytic acid) on nonenzymatic wine oxidation was examined. The ability of these chelators to affect the formation of 1-hydroxyethyl radicals (1-HER) and acetaldehyde was measured using a spin trapping technique with electron paramagnetic resonance (EPR) and by HPLC-PDA, respectively. The chelators were then investigated for their ability to prevent the oxidative loss of an important aroma-active thiol, 3-mercaptohexan-1-ol (3MH). The Fe(II)-specific chelators were more effective than the Fe(III) chelators with respect to 1-HER inhibition during the early stages of oxidation and significantly reduced oxidation markers compared to a control during the study. However, although the addition of Fe(III) chelators was less effective or even showed an initial pro-oxidant activity, the Fe(III) chelators proved to be more effective antioxidants compared to Fe(II) chelators after 8 days of accelerated oxidation. In addition, it is shown for the first time that Fe(II) and Fe(III) chelators can significantly inhibit the oxidative loss of 3MH in model wine. PMID:24001152

Kreitman, Gal Y; Cantu, Annegret; Waterhouse, Andrew L; Elias, Ryan J

2013-10-01

284

Correlation of molecular structure with fluorescence spectra in rare earth chelates. I.  

NASA Technical Reports Server (NTRS)

Rare earth chelates fluorescence spectra correlation with molecular structure, analyzing emission spectrum internal Stark splitting of tetramethylammonium tetrakis /dibenzoylmethido/europate microcrystals

Bjorklund, S.; Degnan, J.; Filipescu, N.; Mcavoy, N.

1968-01-01

285

Transfusional iron overload and iron chelation therapy in thalassemia major and sickle cell disease.  

PubMed

Iron overload is an inevitable consequence of blood transfusions and is often accompanied by increased iron absorption from the gut. Chelation therapy is necessary to prevent the consequences of hemosiderosis. Three chelators, deferoxamine, deferiprone, and deferasirox, are presently available and a fourth is undergoing clinical trials. The efficacy of all 3 available chelators has been demonstrated. Also, many studies have shown the efficacy of the combination of deferoxamine plus deferiprone as an intensive treatment of severe iron overload. Alternating chelators can reduce adverse effects and improve compliance. Adherence to therapy is crucial for good results. PMID:25064709

Marsella, Maria; Borgna-Pignatti, Caterina

2014-08-01

286

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

PubMed Central

Eight strains of Thiobacillus ferrooxidans (laboratory strains Tf-1 [= ATCC 13661] and Tf-2 [= ATCC 19859] and mine isolates SM-1, SM-2, SM-3, SM-4, SM-5, and SM-8) and three strains of Thiobacillus thiooxidans (laboratory strain Tt [= ATCC 8085] and mine isolates SM-6 and SM-7) were grown on ferrous iron (Fe2+), elemental sulfur (S0), or sulfide ore (Fe, Cu, and Zn). The cells were studied for their aerobic Fe2+ - and S0-oxidizing activities (O2 consumption) and anaerobic S0-oxidizing activity with ferric iron (Fe3+) (Fe2+ formation). Fe2+-grown T. ferrooxidans cells oxidized S0 aerobically at a rate of 2 to 4% of the Fe2+ oxidation rate. The rate of anaerobic S0 oxidation with Fe3+ was equal to the aerobic oxidation rate in SM-1, SM-3, SM-4, and SM-5, but was only one-half or less that in Tf-1, Tf-2, SM-2, and SM-8. Transition from growth on Fe2+ to that on S0 produced cells with relatively undiminished Fe2+ oxidation activities and increased S0 oxidation (both aerobic and anaerobic) activities in Tf-2, SM-4, and SM-5, whereas it produced cells with dramatically reduced Fe2+ oxidation and anaerobic S0 oxidation activities in Tf-1, SM-1, SM-2, SM-3, and SM-8. Growth on ore 1 of metal-leaching Fe2+-grown strains and on ore 2 of all Fe2+-grown strains resulted in very high yields of cells with high Fe2+ and S0 oxidation (both aerobic and anaerobic) activities with similar ratios of various activities. Sulfur-grown Tf-2, SM-1, SM-4, SM-6, SM-7, and SM-8 cultures leached metals from ore 3, and Tf-2 and SM-4 cells recovered showed activity ratios similar to those of other ore-grown cells. It is concluded that all the T. ferrooxidans strains studied have the ability to produce cells with Fe2+ and S0 oxidation and Fe3+ reduction activities, but their levels are influenced by growth substrates and strain differences. PMID:16348205

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

1990-01-01

287

Mesoporous organosilica nanotubes containing a chelating ligand in their walls  

NASA Astrophysics Data System (ADS)

We report the synthesis of organosilica nanotubes containing 2,2'-bipyridine chelating ligands within their walls, employing a single-micelle-templating method. These nanotubes have an average pore diameter of 7.8 nm and lengths of several hundred nanometers. UV-vis absorption spectra and scanning transmission electron microscopy observations of immobilized nanotubes with an iridium complex on the bipyridine ligands showed that the 2,2'-bipyridine groups were homogeneously distributed in the benzene-silica walls. The iridium complex, thus, immobilized on the nanotubes exhibited efficient catalytic activity for water oxidation using Ce4+, due to the ready access of reactants to the active sites in the nanotubes.

Liu, Xiao; Goto, Yasutomo; Maegawa, Yoshifumi; Ohsuna, Tetsu; Inagaki, Shinji

2014-11-01

288

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

289

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

290

Gold nanoparticles functionalised with fast water exchanging Gd(3+) chelates: linker effects on the relaxivity.  

PubMed

The relaxivity displayed by Gd(3+) chelates immobilized onto gold nanoparticles is the result of the complex interplay between the nanoparticle size, the water exchange rate and the chelate structure. In this work we study the effect of the length of ?-thioalkyl linkers, anchoring fast water exchanging Gd(3+) chelates onto gold nanoparticles, on the relaxivity of the immobilized chelates. Gold nanoparticles functionalized with Gd(3+) chelates of mercaptoundecanoyl and lipoyl amide conjugates of the DO3A-N-(?-amino)propionate chelator were prepared and studied as potential CA for MRI. High relaxivities per chelate, of the order of magnitude 28-38 mM(-1) s(-1) (30 MHz, 25 °C), were attained thanks to simultaneous optimization of the rotational correlation time and of the water exchange rate. Fast local rotational motions of the immobilized chelates around connecting linkers (internal flexibility) still limit the attainable relaxivity. The degree of internal flexibility of the immobilized chelates seems not to be correlated with the length of the connecting linkers. Biodistribution and MRI studies in mice suggest that the in vivo behavior of the gold nanoparticles was determined mainly by size. Small nanoparticles (HD = 3.9 nm) undergo fast renal clearance and avoidance of the RES organs while larger nanoparticles (HD = 4.8 nm) undergo predominantly hepatobiliary excretion. High relaxivities, allied to chelate and nanoparticle stability and fast renal clearance in vivo suggest that functionalized gold nanoparticles hold great potential for further investigation as MRI contrast agents. This study contributes to a better understanding of the effect of linker length on the relaxivity of gold nanoparticles functionalized with Gd(3+) complexes. It is a relevant contribution towards "design rules" for nanostructures functionalized with Gd(3+) chelates as Contrast Agents for MRI and multimodal imaging. PMID:25611006

Ferreira, Miguel F; Gonçalves, Janaina; Mousavi, Bibimaryam; Prata, Maria I M; Rodrigues, Sérgio P J; Calle, Daniel; López-Larrubia, Pilar; Cerdan, Sebastian; Rodrigues, Tiago B; Ferreira, Paula M; Helm, Lothar; Martins, José A; Geraldes, Carlos F G C

2015-02-17

291

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. PMID:10583978

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

1999-01-01

292

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 PMID:23278384

Keeler, BD; Brookes, MJ

2013-01-01

293

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

294

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. PMID:22754573

Mounsey, Ross B.; Teismann, Peter

2012-01-01

295

Synthesis of feralex a novel aluminum/iron chelating compound.  

PubMed

There is a need for in vivo applicable Fe(3+) and Al(3+) chelation compounds for use as medicines to treat toxic overload conditions of these ions. A novel compound, 2-deoxy-2-(N-carbamoylmethyl-[N'-2'-methyl-3'-hydroxypyrid-4'-one])-D-glucopyranose, designed to chelate Fe(3+) or Al(3+), has been synthesised utilising three naturally occurring products: maltol, glycine and glucosamine. The synthesis is a simple two step process. First, glycine is coupled to maltol by an aminolysis reaction, to yield the intermediate product 1-carboxymethyl -3-hdroxy-2-methylpyrid-4-one, which is joined with glucosamine using a dicyclohexylcarbodiimide promoted peptide coupling method to produce the desired end product, 2-deoxy-2-(N-carbamoylmethyl-[N'-2'-methyl-3'-hydroxypyrid-4'-one])-D-glucopyranose. The latter has been given the trivial name Feralex-G. NMR analysis permitted assignment of frequencies for all carbon and covalently bound hydrogen atoms and was consistent with the proposed structure of the compound. Electron spray Ionisation Mass Spectrometry (ESI-MS) yielded the expected molecular mass of 344. Proton displacement/pH titration analysis yielded three Feralex-G molecules bound to 1 Al(3+) or Fe(3+) over a measurable pH range of 3-10.5. A rapid TLC method to monitor progression of the synthetic procedures is also described. PMID:11750021

Kruck, Theo P A; Burrow, Timothy E

2002-01-01

296

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. PMID:16348031

Lizama, Hector M.; Suzuki, Isamu

1989-01-01

297

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

Microsoft Academic Search

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

V. Kavitha; K. Palanivelu

2004-01-01

298

Alginate Inhibits Iron Absorption from Ferrous Gluconate in a Randomized Controlled Trial and Reduces Iron Uptake into Caco-2 Cells  

PubMed Central

Previous in vitro results indicated that alginate beads might be a useful vehicle for food iron fortification. A human study was undertaken to test the hypothesis that alginate enhances iron absorption. A randomised, single blinded, cross-over trial was carried out in which iron absorption was measured from serum iron appearance after a test meal. Overnight-fasted volunteers (n?=?15) were given a test meal of 200 g cola-flavoured jelly plus 21 mg iron as ferrous gluconate, either in alginate beads mixed into the jelly or in a capsule. Iron absorption was lower from the alginate beads than from ferrous gluconate (8.5% and 12.6% respectively, p?=?0.003). Sub-group B (n?=?9) consumed the test meals together with 600 mg calcium to determine whether alginate modified the inhibitory effect of calcium. Calcium reduced iron absorption from ferrous gluconate by 51%, from 11.5% to 5.6% (p?=?0.014), and from alginate beads by 37%, from 8.3% to 5.2% (p?=?0.009). In vitro studies using Caco-2 cells were designed to explore the reasons for the difference between the previous in vitro findings and the human study; confirmed the inhibitory effect of alginate. Beads similar to those used in the human study were subjected to simulated gastrointestinal digestion, with and without cola jelly, and the digestate applied to Caco-2 cells. Both alginate and cola jelly significantly reduced iron uptake into the cells, by 34% (p?=?0.009) and 35% (p?=?0.003) respectively. The combination of cola jelly and calcium produced a very low ferritin response, 16.5% (p<0.001) of that observed with ferrous gluconate alone. The results of these studies demonstrate that alginate beads are not a useful delivery system for soluble salts of iron for the purpose of food fortification. Trial Registration ClinicalTrials.gov NCT01528644 PMID:25391138

Wawer, Anna A.; Harvey, Linda J.; Dainty, Jack R.; Perez-Moral, Natalia; Sharp, Paul; Fairweather-Tait, Susan J.

2014-01-01

299

Hardness improvement of TiC-reinforced ferrous surface composites fabricated by high-energy electron beam irradiation  

Microsoft Academic Search

Metal matrix composites in general have excellent performance compared with metallic materials because of the ductile fracture behavior in addition to high strength and elastic modulus. Particularly, TiC-reinforced ferrous composites have highly stabilized TiC particles inside the matrix, and thus can be applied to structures requiring resistance to abrasion and corrosion and high-temperature properties. They are typically fabricated by powder

Soon-Ju Kwon; Seong-Hun Choo; Sunghak Lee

1998-01-01

300

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

301

Formation Damage Due to Iron Precipitation during Matrix Acidizing Treatments of Carbonate Reservoirs and Ways to Minimize it Using Chelating Agents  

E-print Network

on both chelate-to-iron mole ratio and the initial permeability of the cores. Calcium is chelated along with iron, which limits the effectiveness of chelating agents to control iron (III) precipitation. Acid solutions should be designed considering...

Assem, Ahmed I

2013-07-11

302

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

303

Control of ferrous iron oxidation within circumneutral microbial iron mats by cellular activity and autocatalysis.  

PubMed

Ferrous iron (Fe2+) oxidation by microbial iron mat samples, dominated by helical stalks of Gallionella ferruginea or sheaths of Leptothrix ochracea, was examined. Pseudo-first-order rate constants for the microbial mat samples ranged from 0.029 +/- 0.004 to 0.249 +/- 0.042 min(-1) and correlated well with iron content (R2 = 0.929). Rate constants for Na azide-treated (1 mM) samples estimated autocatalytic oxidation by iron oxide stalks or sheaths, with values ranging from 0.016 +/- 0.008 to 0.062 +/- 0.006 min(-1). Fe2+ oxidation attributable to cellular activities was variable with respect to sampling location and sampling time, with rate constants from 0.013 +/- 0.005 to 0.187 +/- 0.037 min(-1). Rates of oxidation of the same order of magnitude for cellular processes and autocatalysis suggested that bacteria harnessing Fe2+ as an energy source compete with their own byproducts for growth, not chemical oxidation (under conditions where aqueous oxygen concentrations are less than saturating). The use of cyclic voltammetry within this study for the simultaneous measurement of Fe2+ and oxygen allowed the collection of statistically meaningful and reproducible data, two factors that have limited aerobic, circumneutral, Fe2+ -oxidation rate studies. PMID:17937285

Rentz, Jeremy A; Kraiya, Charoenkwan; Luther, George W; Emerson, David

2007-09-01

304

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. PMID:3395580

Ades, A E; Kazantzis, G

1988-01-01

305

INTERPRETATION OF AT-LINE SPECTRA FROM AFS-2 BATCH #3 FERROUS SULFAMATE TREATMENT  

SciTech Connect

Spectra from the “at-line” spectrometer were obtained during the ferrous sulfamate (FS) valence adjustment step of AFS-2 Batch #3 on 9/18/2013. These spectra were analyzed by mathematical principal component regression (PCR) techniques to evaluate the effectiveness of this treatment. Despite the complications from Pu(IV), we conclude that all Pu(VI) was consumed during the FS treatment, and that by the end of the treatment, about 85% was as Pu(IV) and about 15% was as Pu(III). Due to the concerns about the “odd” shape of the Pu(IV) peak and the possibility of this behavior being observed in the future, a follow-up sample was sent to SRNL to investigate this further. Analysis of this sample confirmed the previous results and concluded that it “odd” shape was due to an intermediate acid concentration. Since the spectral evidence shows complete reduction of Pu(VI) we conclude that it is appropriate to proceed with processing of this the batch of feed solution for HB-Line including the complexation of the fluoride with aluminum nitrate.

Kyser, E.; O'Rourke, P.

2013-12-10

306

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

NASA Astrophysics Data System (ADS)

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

Yuan, Chen; Jones, Sam; Blackburn, Stuart

2012-12-01

307

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

PubMed

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

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

2013-04-01

308

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

PubMed Central

Iron polymaltose complex (IPC) offers similar efficacy with superior tolerability to ferrous sulfate in adults, but randomized trials in children are rare. In a prospective, open-label, 4-month study, 103 children aged >6 months with iron deficiency anemia (IDA) were randomized to IPC once daily or ferrous sulfate twice daily, (both 5?mg iron/kg/day). Mean increases in Hb to months 1 and 4 with IPC were 1.2 ± 0.9?g/dL and 2.3 ± 1.3?g/dL, respectively, (both P = 0.001 versus baseline) and 1.8 ± 1.7?g/dL and 3.0 ± 2.3?g/dL with ferrous sulfate (both P = 0.001 versus baseline) (n.s. between groups). Gastrointestinal adverse events occurred in 26.9% and 50.9% of IPC and ferrous sulfate patients, respectively (P = 0.012). Mean acceptability score at month 4 was superior with IPC versus ferrous sulfate (1.63 ± 0.56 versus 2.14 ± 0.75, P = 0.001). Efficacy was comparable with IPC and ferrous sulfate over a four-month period in children with IDA, but IPC was associated with fewer gastrointestinal adverse events and better treatment acceptability. PMID:22121379

Yasa, Beril; Agaoglu, Leyla; Unuvar, Emin

2011-01-01

309

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

PubMed

Iron polymaltose complex (IPC) offers similar efficacy with superior tolerability to ferrous sulfate in adults, but randomized trials in children are rare. In a prospective, open-label, 4-month study, 103 children aged >6 months with iron deficiency anemia (IDA) were randomized to IPC once daily or ferrous sulfate twice daily, (both 5?mg iron/kg/day). Mean increases in Hb to months 1 and 4 with IPC were 1.2 ± 0.9?g/dL and 2.3 ± 1.3?g/dL, respectively, (both P = 0.001 versus baseline) and 1.8 ± 1.7?g/dL and 3.0 ± 2.3?g/dL with ferrous sulfate (both P = 0.001 versus baseline) (n.s. between groups). Gastrointestinal adverse events occurred in 26.9% and 50.9% of IPC and ferrous sulfate patients, respectively (P = 0.012). Mean acceptability score at month 4 was superior with IPC versus ferrous sulfate (1.63 ± 0.56 versus 2.14 ± 0.75, P = 0.001). Efficacy was comparable with IPC and ferrous sulfate over a four-month period in children with IDA, but IPC was associated with fewer gastrointestinal adverse events and better treatment acceptability. PMID:22121379

Yasa, Beril; Agaoglu, Leyla; Unuvar, Emin

2011-01-01

310

Uptake of zinc from chelate-buffered nutrient solutions by wheat genotypes differing in zinc efficiency  

Microsoft Academic Search

Zinc-efficient Triticum aestivum (cv. Warigal) and Zn-inefficient Triticum turgidum conv. durum (cv. Durati) were grown in chelate-buffe red, complete nutrient solutions providing either deficient or suffi- cient Zn supply. When transferred to fresh chelate- buffered nutrient solutions containing a wide range of Zn supplies (0-1.28\\/rniol m\\

Zdenko Rengel; Robin D. Graham

1996-01-01

311

Investigation of para-sulfonatocalix[n]arenes [n = 6, 8] as potential chelates for 230  

E-print Network

be useful for in vivo chelation of the novel therapeutic alhpa-emitter 230 U. We have studied;2 Introduction The alpha emitter 230 U (t1/2 = 20.8 d) is a promising novel therapeutic radionuclide, such as antibodies or peptides, via bifunctional chelating agents (BCAs). Due to the short range (

Paris-Sud XI, Université de

312

A new caged Ca 2+, azid-1, is far more photosensitive than nitrobenzyl-based chelators  

Microsoft Academic Search

Background: Photolabile chelators that release Ca2+ upon illumination have been used extensively to dissect the role of this important second messenger in cellular processes such as muscle contraction and synaptic transmission. The caged calcium chelators that are presently available are often limited by their inadequate changes in Ca2+ affinity, selectivity for Ca2+ over Mg2+ and sensitivity to light. As these

Stephen R. Adams; Varda Lec-Ram; Roger Y. Tsien

1997-01-01

313

Synthesis and Characterization of Hemicage 8-Hydroxyquinoline Chelates with Enhanced Electrochemical and Photophysical Properties  

E-print Network

Synthesis and Characterization of Hemicage 8-Hydroxyquinoline Chelates with Enhanced, tripodal 8-hydroxyquinoline ligand (QH3) and its trivalent metal chelates (MQ, M ) Al3+, Ga3+, In3 facial geometry, in contrast to their uncaged cousins with 8-hydroxyquinoline (Mq3) and 3-methyl-8

Bernhard, Stefan

314

ADSORPTION AND LIGAND-ASSISTED FEOOH(GOETHITE) DISSOLUTION BY AMINOCARBOXYLATE CHELATING AGENTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

In order for extracellular chelating agents to solubilize Fe(III) (hydr)oxides, the following criteria must be met: 1. The chelating agent must adsorb. Amine groups structurally close to a carboxylate group strongly diminish adsorption (via hydrogen-bonding), while distal amine groups slightly dimi...

315

Removal of PCR Error Products and Unincorporated Primers by Metal-Chelate Affinity Chromatography  

E-print Network

Removal of PCR Error Products and Unincorporated Primers by Metal-Chelate Affinity Chromatography of America Abstract Immobilized Metal Affinity Chromatography (IMAC) has been used for decades to purify Products and Unincorporated Primers by Metal-Chelate Affinity Chromatography. PLoS ONE 6(1): e14512. doi:10

Fox, George

316

Biosensors and Bioelectronics 21 (2006) 10771085 Application of europium(III) chelate-dyed nanoparticle labels in a  

E-print Network

Biosensors and Bioelectronics 21 (2006) 1077­1085 Application of europium(III) chelate for immunosensors with fluorescent europium(III) chelate nanoparticle labels (Seradyn) in a competitive atrazine

Hammock, Bruce D.

317

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

MedlinePLUS

... years). They were assigned randomly to receive 40 infusions of either the disodium EDTA chelation solution or ... Participants also were randomly assigned to receive 40 infusions of either the disodium EDTA chelation solution or ...

318

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

319

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

320

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

321

Removal of cadmium by combining deferasirox and desferrioxamine chelators in rats.  

PubMed

An investigation was conducted to evaluate the ability of two chelators, deferasirox and desferrioxamine (DFO), in removing cadmium from biological system. The potential efficiency of those chelators were investigated after cadmium administration for 60 days following two dose levels of 20 and 40 mg/kg body weight daily to male rats. However, abnormalities were observed in clinical signs after cadmium administration, such as yellowish discoloration of hair, flaccid and hypotonic muscles, irritability, weakness and loss of weight. The hypothesis that the two chelators might be more efficient as combined therapy than single therapy in removing metal ions from the body was considered. In this way, two known chelators, deferasirox and DFO were chosen and tested in the acute rat model. The chelation therapy results show that deferasirox and DFO are able (?)to remove cadmium ions from the body, while iron concentration returned to the normal level and symptoms are decreased. PMID:22134990

Fatemi, S Jamilaldine; Saljooghi, Amir Shokooh; Balooch, Faezeh Dahooee; Iranmanesh, Marzieh; Golbafan, Mohammad Reza

2012-02-01

322

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. PMID:24478610

Veríssimo, 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

323

Role of pH in metal adsorption from aqueous solutions containing chelating agents on chitosan  

SciTech Connect

The role of pH in adsorption of Cu(II) from aqueous solutions containing chelating agents on chitosan was emphasized. Four chelating agents including ethylenediaminetetraacetic acid (EDTA), citric acid, tartaric acid, and sodium gluconate were used. It was shown that the adsorption ability of Cu(II) on chitosan from its chelated solutions varied significantly with pH variations. The competition between coordination of Cu(II) with unprotonated chitosan and electrostatic interaction of the Cu(II) chelates with protonated chitosan took place because of the change in solution pH during adsorption. The maximum adsorption capacity was obtained within each optimal pH range determined from titration curves of the chelated solutions. Coordination of Cu(II) with the unprotonated chitosan was found to dominate at pH below such an optimal pH value.

Wu, F.C.; Tseng, R.L. [Lien Ho Junior Coll. of Technology, Maio-Li (Taiwan, Province of China). Dept. of Chemical Engineering and Environmental Engineering] [Lien Ho Junior Coll. of Technology, Maio-Li (Taiwan, Province of China). Dept. of Chemical Engineering and Environmental Engineering; Juang, R.S. [Yuan Ze Univ., Chung-li (Taiwan, Province of China)] [Yuan Ze Univ., Chung-li (Taiwan, Province of China)

1999-01-01

324

Clinically Approved Iron Chelators Influence Zebrafish Mortality, Hatching Morphology and Cardiac Function  

PubMed Central

Iron chelation therapy using iron (III) specific chelators such as desferrioxamine (DFO, Desferal), deferasirox (Exjade or ICL-670), and deferiprone (Ferriprox or L1) are the current standard of care for the treatment of iron overload. Although each chelator is capable of promoting some degree of iron excretion, these chelators are also associated with a wide range of well documented toxicities. However, there is currently very limited data available on their effects in developing embryos. In this study, we took advantage of the rapid development and transparency of the zebrafish embryo, Danio rerio to assess and compare the toxicity of iron chelators. All three iron chelators described above were delivered to zebrafish embryos by direct soaking and their effects on mortality, hatching and developmental morphology were monitored for 96 hpf. To determine whether toxicity was specific to embryos, we examined the effects of chelator exposure via intra peritoneal injection on the cardiac function and gene expression in adult zebrafish. Chelators varied significantly in their effects on embryo mortality, hatching and morphology. While none of the embryos or adults exposed to DFO were negatively affected, ICL -treated embryos and adults differed significantly from controls, and L1 exerted toxic effects in embryos alone. ICL-670 significantly increased the mortality of embryos treated with doses of 0.25 mM or higher and also affected embryo morphology, causing curvature of larvae treated with concentrations above 0.5 mM. ICL-670 exposure (10 µL of 0.1 mM injection) also significantly increased the heart rate and cardiac output of adult zebrafish. While L1 exposure did not cause toxicity in adults, it did cause morphological defects in embryos at 0.5 mM. This study provides first evidence on iron chelator toxicity in early development and will help to guide our approach on better understanding the mechanism of iron chelator toxicity. PMID:25329065

Hamilton, Jasmine L.; Hatef, Azadeh; Imran ul-haq, Muhammad; Nair, Neelima; Unniappan, Suraj; Kizhakkedathu, Jayachandran N.

2014-01-01

325

Next generation barrier CMP slurry with novel weakly alkaline chelating agent  

NASA Astrophysics Data System (ADS)

To strengthen the device performance with the pattern wafer by enhancing the Cu polishing rate and improve the surface roughness with the Cu lines, a new weakly alkaline chelating agent with a barrier slurry is developed to meet the process demand of the advanced barrier chemical mechanical planarization (CMP). This new chelating agent has a stronger chelating ability and a lower pH value than the previous generation-FA/O I chelating agent researched before. Without an unstable oxidant agent added in the polishing slurry, it is difficult to enhance the copper polishing rate during the barrier CMP. The stronger chelating ability of the new chelating agent could increase the copper polishing rate along with controlling the Cu/Ta/TEOS removal rate selectivity to meet the requirements of the IC fabrication process. Thus it has solved the problem of excessive roughness due to the lower polishing rate, avoiding reducing the device performance with the pattern wafer. The new chelating agent with its lower pH value could make it possible to protect the low-k dielectric under the barrier layer from structurally breaking. The CMP experiment was performed on the 12 inch MIT 854 pattern wafers with the barrier slurry containing the new weakly alkaline chelating agent. By the DOE optimization, the results indicate that as the new chelating agent concentration in the slurry was up to 2.5 mL/L, the copper polishing rate is about 31.082 nm/min. Meanwhile, the wafer surface has a rather low roughness value of 0.693 nm (10 × 10 ?m), the correction ability with the above slurry is adapted to the next generation barrier CMP and the k value of the low-k dielectric seems to have no k-shift. All the results presented show that the new weakly alkaline chelating agent with its superior performance can be used for the advanced barrier CMP.

Shiyan, Fan; Yuling, Liu; Ming, Sun; Jiying, Tang; Chenqi, Yan; Hailong, Li; Shengli, Wang

2015-01-01

326

Long-term Chelation Therapy in Thalassaemia Major: Effect on Liver Iron Concentration, Liver Histology, and Clinical Progress  

Microsoft Academic Search

A prospective trial of continuous chelation therapy in children with homozygous thalassaemia on a high transfusion regimen was started in April 1966. The effect of treatment on iron concentration in the liver and on hepatic histology was examined in 49 biopsy specimens obtained from nine chelator-treated patients and nine control patients between April 1966 and April 1973.Chelation therapy was associated

Michael Barry; David M. Flynn; Elizabeth A. Letsky; R. A. Risdon

1974-01-01

327

Mesoporous organosilica nanotubes containing a chelating ligand in their walls  

SciTech Connect

We report the synthesis of organosilica nanotubes containing 2,2?-bipyridine chelating ligands within their walls, employing a single-micelle-templating method. These nanotubes have an average pore diameter of 7.8 nm and lengths of several hundred nanometers. UV-vis absorption spectra and scanning transmission electron microscopy observations of immobilized nanotubes with an iridium complex on the bipyridine ligands showed that the 2,2?-bipyridine groups were homogeneously distributed in the benzene-silica walls. The iridium complex, thus, immobilized on the nanotubes exhibited efficient catalytic activity for water oxidation using Ce{sup 4+}, due to the ready access of reactants to the active sites in the nanotubes.

Liu, Xiao; Goto, Yasutomo; Maegawa, Yoshifumi; Inagaki, Shinji, E-mail: inagaki@mosk.tytlabs.co.jp [Toyota Central R and D Laboratories, Inc., Nagakute, Aichi 480-1192 (Japan); Japan Science and Technology Agency (JST)/ACT-C, Nagakute, Aichi, 480-1192 (Japan); Ohsuna, Tetsu [Toyota Central R and D Laboratories, Inc., Nagakute, Aichi 480-1192 (Japan)

2014-11-01

328

Chemistry and biology of the copper chelator methanobactin  

PubMed Central

Methanotrophic bacteria, organisms that oxidize methane, produce a small copper chelating molecule called methanobactin (Mb). Mb binds Cu(I) with high affinity and is hypothesized to mediate copper acquisition from the environment. Recent advances in Mb characterization include revision of the chemical structure of Mb from Methylosinus trichosporium OB3b and further investigation of its biophysical properties. In addition, Mb production by several other methanotroph strains has been investigated and preliminary characterization suggests diversity in chemical composition. Initial clues into Mb biosynthesis have been obtained by identification of a putative precursor gene in the M. trichosporium OB3b genome. Finally, direct uptake of intact Mb into the cytoplasm of M. trichosporium OB3b cells has been demonstrated and studies of the transport mechanism have been initiated. Taken together, these advances represent significant progress and set the stage for exciting new research directions. PMID:22126187

Kenney, Grace E.; Rosenzweig, Amy C.

2012-01-01

329

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. PMID:9591648

Vereb, G; Jares-Erijman, E; Selvin, P R; Jovin, T M

1998-01-01

330

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

331

Chelate-assisted phytoextraction of mercury in biosolids.  

PubMed

Mercury contaminated stockpiles of biosolids (8.4 mg kg?¹ Hg) from Melbourne Water's Western Treatment Plant (MW-WTP) were investigated to evaluate the possibility of their Hg chelate-assisted phytoextraction. The effects of ammonium thiosulphate (NH?)?S?O?, cysteine (Cys), nitrilotriacetic acid (NTA), and potassium iodide (KI) were studied to mobilize Hg and to increase its uptake in plant shoots. Three plant species were selected for this study, one herbaceous and two grasses: Atriplex codonocarpa, Austrodanthonia caespitosa and Vetiveria zizanioides. KI proved to be the best candidate for Hg phytostabilization in biosolids because it facilitated the concentration of this metal mainly in roots. (NH?)?S?O? was shown to be the most effective chelating agent among those tested for Hg phytoextraction as it allowed the highest translocation of Hg into the above-ground tissues of the selected plant species. The phytoextraction conditions using A. caespitosa as the best performing plant species were optimized at an (NH?)?S?O? concentration of 27 mmol kg?¹ and contact time with biosolids of seven day. Monitoring of the Hg concentration in biosolids and in leachate water during a 9-day treatment revealed that the biosolids Hg concentration decreased significantly after the first day of treatment and then it decreased only slightly with time reaching a value of 5.6 mg kg?¹ Hg at the end of the 9-day period. From the corresponding results obtained for the leachate water, it was suggested that a relatively large fraction of Hg (0.7 mg kg?¹ Hg) was promptly mobilized and consequently the plants were able to take up the metal and translocate it into shoots. PMID:21514623

Lomonte, Cristina; Doronila, Augustine; Gregory, David; Baker, Alan J M; Kolev, Spas D

2011-06-01

332

Cultivable diversity of thermophilic arsenite/ferrous-oxidizing microorganisms in hot springs of Taiwan  

NASA Astrophysics Data System (ADS)

Elevated levels of arsenic in groundwater and surface water bodies have posed a stringent threat to the deterioration of the water quality for drinking and agriculture purposes around the world. In particular, arsenic liberated from volcanic and sedimentary rocks at high temperatures would be immobilized through adsorption on iron oxide and/or crystallization of iron-bearing minerals downstream at low temperatures. Understanding how microbially-catalytic reactions are involved in the changes of the redox state of arsenic and iron along a flow path would provide important constraints on the arsenic mobility in natural occurrences. The aims of this study were to isolate and characterize thermophilic arsenite- and iron-oxidizing microbes that would facilitate to establish the linkages between microbial distribution and in situ Fe/As cycling processes. Four source waters (LH05, LH08, SYK and MT) from acid-sulfate springs (pH 2-3, 60-97oC) located in the Tatun volcanic area of northern Taiwan were collected and inoculated into media targeting on autotrophic ferrous iron (FC3), arsenite (AC3 ,ACC3, AC7, ACC7), arsenite-resistant hydrogen (AH23), arsenite-resistant hydrogen-sulfur (AH2S3), and arsenite-resistant sulfur oxidations(AS3), and heterotrophic arsenite oxidation(AH3, AH7) at pH 3, and 7 at temperatures of 50, 70 and 80oC. Samples from the Kuantzuling mud springs (KTL) in southwestern Taiwan known with elevated arsenic levels (0.4 ppm) were also collected, inoculated into the heterotrophic medium and incubated at 50, 60, 70 and 80oC. Isolates obtained from KTL were subject to test on the AH7 and ACC7. Two positive enrichments for iron oxidation at 50oC and 70oC were confirmed by the steadily decrease of ferrous iron and increase of precipitates over 4 transfers for samples from the SYK spring. Diverse morphological types of microbes were enriched in all types of arsenite-bearing media at 50oC except for AH23. At 70oC, positive enrichments were found in media which are AH3, AH2S3 and ACC3 from almost all sampling sites. Positive heterotrophic enrichments at 80oC were also obtained from almost all sampling sites. Coccus was the dominant morphotype in this enrichment. One 16S rDNA sequence affiliated with Sulfolobus tokodaii was detected from MT enrichments at 80oC. Alicyclobacillus, Geobacillus, Thermus and Meiothermus related strains were purified from 50oC and 70oC heterotrophic enrichments for samples from LH05 SYK, MT and KTL. Physiological tests indicated that these Alicyclobacillus-related strains are firstly reported to be capable of relying solely on arsenite as the energy source. Hydrogenobaculum-related strains were isolated from AH2S3. Both H2 and S were required for growth. Their 16S rRNA sequences resembled Hydrogenobaculum acidophilum H55 obtained from the Yellowstone National Park of USA. The results expand the current view about the diversity of arsenite-resistant microbes in high temperature environments. More molecular and microscopic works are undergoing to characterize interactions between mineral and microbe in enrichments and natural settings and to place better constraints on the biological effect for Fe/As cycling in hot spring.

Lu, G.; Lin, Y.; Chang, Y.; Wang, P.; Lin, L.

2009-12-01

333

Addition of ferrous sulfate to cement and risk of chromium dermatitis among construction workers.  

PubMed

Lowering the water-soluble chromium content of cement to < 2 ppm has been suggested to diminish the risk of allergic hand dermatitis caused by chromium among construction workers. The prevalence of chromium dermatitis was determined for a representative sample of 913 house construction workers and 707 concrete element prefabrication workers, with a questionnaire and clinical examination, before the use of cement with such a low content of water-soluble chromium was started on Finnish construction sites in 1987. The prevalence of allergic contact dermatitis caused by water-soluble chromium, diagnoses confirmed with patch tests among the workers with hand dermatitis, was 9/117 (7.7%). 4 of them were new 4/105 (4%) and 5 had been diagnosed earlier. In 1987, the prevalence of work-related hand dermatitis (allergic and irritant together) was 6.8% among the construction workers and 8.9% among the concrete element prefabrication workers. The Finnish Register of Occupational Diseases was checked for reports of chromium dermatitis and other forms of hand dermatitis from 1978 to 1992. The results indicated that, after 1987, the occurrence of allergic contact dermatitis caused by chromium decreased to less than 1/3 the previous level, whereas the occurrence of irritant contact dermatitis remained stable throughout the observation period. Regardless of some potential confounders, the addition of ferrous sulfate to cement during the production process may have reduced the number of cases of allergic contact dermatitis among construction and concrete element prefabrication workers. Our results agree with the results of Danish studies and Swedish observations. PMID:8789225

Roto, P; Sainio, H; Reunala, T; Laippala, P

1996-01-01

334

Overriding Felkin Control: A General Method for Highly Diastereoselective Chelation-Controlled Additions to ?-Silyloxy Aldehydes  

PubMed Central

According to the Felkin-Anh and Cram-chelation models, nucleophilic additions to ?-silyloxy aldehydes procees through a non-chelation pathway due to the steric and electronic properties of the silyl group, giving rise to Felkin addition products. Herein we describe a general method to promote chelation-control in additions to ?-silyloxy aldehydes. Dialkylzincs, functionalized dialkylzincs, and (E)-disubstituted, (E)-trisubstituted, and (Z)-disubstituted vinylzinc reagents add to silyl-protected ?-hydroxy aldehydes with high selectivity for chelation-controlled products (dr of 10:1 to >20:1) in the presence of alkylzinc halides or triflates, RZnX. With the high functional group tolerance of organozinc reagents, the mild Lewis acidity of RZnX, and the excellent diastereoselectivities favoring the chelation-controlled products, this method will be useful in the synthesis of natural products. A mechanism involving chelation is supported by 1) NMR studies of a model substrate, 2) a dramatic increase in reaction rate in the presence of an alkylzinc halide, and 3) higher diastereoselectivity with larger alkyl substituents on the ?-carbon of the aldehyde. This method provides access to chelation-controlled addition products with high diastereoselectivity previously unavailable using achiral organometallic reagents. PMID:20218659

Stanton, Gretchen R.; Johnson, Corinne N.; Walsh, Patrick J.

2010-01-01

335

A competition model between Pseudomonas fluorescens and pathogens via iron chelation.  

PubMed

In this study we present a competition model between a non-chelator (e.g. pathogen) microorganism and an iron chelator microorganism (e.g. Pseudomonas fluorescens). This latter is a beneficial bacteria that can inhibit the growth of the non-chelator through its iron chelating capability. This phenomena of iron chelation is shown to prevent the pathogen from proliferating to numbers capable of causing disease. A mathematical model is formulated and used to study this competition. The model proposes a new and simple conceptual explanation of interactions. It is a nonlinear system of ordinary differential equations. A qualitative analysis of the model for the batch case (no inflow or outflow from the system) is carried out and the global behavior of the model variables is studied. For the chemostat case, the equilibrium points were derived and their stability was performed through extensive numerical simulations. It is found that iron chelation is able to control the non-chelator microorganism growth under a wide range of conditions. PMID:20005236

Fgaier, Hedia; Eberl, Hermann J

2010-04-21

336

Design, synthesis, and evaluation of polyhydroxamate chelators for selective complexation of actinides  

SciTech Connect

Specific chelating polymers targeted for actinides have much relevance to problems involving remediation of nuclear waste. Goal is to develop polymer supported, ion specific extraction systems for removing actinides and other hazardous metal ions from wastewaters. This is part of an effort to develop chelators for removing actinide ions such as Pu from soils and waste streams. Selected ligands are being attached to polymeric backbones to create novel chelating polymers. These polymers and other water soluble and insoluble polymers have been synthesized and are being evaluated for ability to selectively remove target metal ions from process waste streams.

Gopalan, A.; Jacobs, H.; Koshti, N.; Stark, P.; Huber, V.; Dasaradhi, L.; Caswell, W. [New Mexico State Univ., Las Cruces, NM (United States); Smith, P.; Jarvinen, G. [Los Alamos National Lab., NM (United States)

1995-08-01

337

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

338

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

339

Fortifying milk with ferrous gluconate and zinc oxide in a public nutrition program reduced the prevalence of anemia in toddlers.  

PubMed

We aimed to assess the efficacy of whole cow's milk fortified with ferrous gluconate and zinc oxide, along with ascorbic acid, in reducing the prevalence of anemia and improving iron status of low income children 10-30 mo of age. Healthy children were randomly assigned to drink 400 mL/d of cow's whole milk, either fortified milk (FM) with 5.8 mg/400 mL of iron as ferrous gluconate, 5.28 mg/400 mL of zinc as zinc oxide, and 48 mg/400 mL of ascorbic acid, or nonfortified milk (NFM) with 0.2 mg iron/400 mL, 1.9 mg zinc/400 mL, and 6.8 mg ascorbic acid/400 mL. Hemoglobin, serum ferritin, soluble transferrin receptors (TfR), and C-reactive protein concentrations were measured at baseline and 6 mo after intervention. The prevalence of anemia declined from 41.4 to 12.1% (P < 0.001), or 29 percentage points, in the FM group; there was no change in the NFM group. Hemoglobin (coefficient = 0.22, P < 0.01) was positively and TfR (coefficient = -0.29, P < 0.001) negatively associated with treatment, controlling for their respective baseline values, age, and gender. Treatment with FM was negatively associated with the likelihood of being anemic (pseudo R(2) = 0.085, P < 0.03) after 6 mo of intervention. Ferrous gluconate added to whole cow's milk as a fortificant along with ascorbic acid is efficacious in reducing the prevalence of anemia and in improving iron status of Mexican toddlers. The results of this study lead to broadening a subsidized FM distribution program to 4.2 million beneficiary children 1-11 y of age in Mexico. PMID:16988138

Villalpando, Salvador; Shamah, Teresa; Rivera, Juan A; Lara, Yaveth; Monterrubio, Eric

2006-10-01

340

Assessment of mapping exposed ferrous and ferric iron compounds using Skylab-EREP data. [Pisgah Crater, California  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. The S190B color photography is as useful as LANDSAT data for the mapping of color differences in the rocks and soils of the terrain. An S192 ratio of 0.79 - 0.89 and 0.93 - 1.05 micron bands produced an apparently successful delineation of ferrous, ferric, and other materials, in agreement with theory and ratio code studies. From an analysis of S191 data, basalt and dacite were separated on the basis of differences in spectral emissivity in the 8.3 - 12 micron region.

Vincent, R. (principal investigator); Wagner, H.; Pillars, W.; Bennett, C.

1976-01-01

341

Radiolabeled technetium chelates for use in renal function determinations  

DOEpatents

The present invention is directed to novel radiopharmaceutical imaging agents incorporating Tc-99m as a radiolabel. In particular, the novel imaging agents disclosed herein have relatively high renal extraction efficiencies, and hence are useful for conducting renal function imaging procedures. The novel Tc-99m compounds of a present invention have the following general formula: ##STR1## wherein X is S or N; and wherein Y is--H or wherein Y is ##STR2## and where R.sub.1 is --H, --CH.sub.3, or --CH.sub.2 CH.sub.3 ; R.sub.2 is --H, --CH.sub.2 CO.sub.2 H, --CH.sub.2 CONH.sub.2, --CH.sub.2 CH.sub.2 CO.sub.2 H, --CH.sub.2 CH.sub.2 CONH.sub.2, --CH.sub.3, --CH.sub.2 CH.sub.3, CH.sub.2 C.sub.6 H.sub.5, or --CH.sub.2 OH; and Z is --H, --CO.sub.2 H, --CONH.sub.2, --SO.sub.3 H, --SO.sub.2 NH.sub.2, or --CONHCH.sub.2 CO.sub.2 H; and the Tc is Tc-99m; and water-soluble salts thereof. Of the foregoing, the presently preferred Tc-99m compound of the present invention is Tc-99m-mercaptoacetylglycylglycylglycine (Tc-99m-MAGGG). The present invention is also directed to novel chelating agents that may be reacted with Tc-99m to form the foregoing compounds. Such novel chelating agents have the following general formula. ##STR3## where X and Y have the same definitions as above, and wherein Y' is --H.sub.2 when X is N, or wherein Y' is --H, or a suitable protective group such as --COCH.sub.3, --COC.sub.6 H.sub.5, --CH.sub.2 NHCOCH.sub.3, --COCF.sub.3, or --COCH.sub.2 OH when X is S. The present invention also provides methods for preparing and using the novel Tc-99m compounds.

Fritzberg, Alan (Edmonds, WA); Kasina, Sudhakar (Kirkland, WA); Johnson, Dennis L. (Las Cruces, NM)

1990-01-01

342

Radiolabeled technetium chelates for use in renal function determinations  

DOEpatents

The present invention is directed to novel radiopharmaceutical imaging agents incorporating Tc-99m as a radiolabel. In particular, the novel imaging agents disclosed herein have relatively high renal extraction efficiencies, and hence are useful for conducting renal function imaging procedures. The novel Tc-99m compounds of a present invention have the following general formula: ##STR1## wherein X is S or N; and wherein Y is --H or wherein Y is ##STR2## and where R.sub.1 is --H, --CH.sub.3, or --CH.sub.2 CH.sub.3 ; R.sub.2 is --H, --CH.sub.2 CO.sub.2 H, --CH.sub.2 CONH.sub.2, --CH.sub.2 CH.sub.2 CO.sub.2 H, --CH.sub.2 CH.sub.2 CONH.sub.2, --CH.sub.3, --CH.sub.2 CH.sub.3, CH.sub.2 C.sub.6 H.sub.5, or --CH.sub.2 OH; and Z is --H, --CO.sub.2 H, --CONH.sub.2, --SO.sub.3 H, --SO.sub.2 NH.sub.2, or --CONHCH.sub.2 CO.sub.2 H; and the Tc is Tc-99m; and water-soluble salts thereof. Of the foregoing, the presently preferred Tc-99m compound of the present invention is Tc-99m-mercaptoacetylglycylglycylglycine (Tc-99m-MAGGG). The present invention is also directed to novel chelating agents that may be reacted with Tc-99m to form the foregoing compounds. Such novel chelating agents have the following general formula. ##STR3## where X and Y have the same definitions as above, and wherein Y' is --H.sub.2 when X is N, or wherein Y' is --H, or a suitable protective group such as --COCH.sub.3, --COC.sub.6 H.sub.5, --CH.sub.2 NHCOCH.sub.3, --COCF.sub.3, or --COCH.sub.2 OH when X is S. The present invention also provides methods for preparing and using the novel Tc-99m compounds.

Fritzberg, Alan (Edmonds, WA); Kasina, Sudhaker (Kirkland, WA); Johnson, Dennis L. (Las Cruces, NM)

1994-01-01

343

Predominant Intermediate-Spin Ferrous Iron in Lowermost Mantle Post-Perovskite and Perovskite  

NASA Astrophysics Data System (ADS)

Silicate post-perovskite and perovskite are believed to be the dominant minerals of the lowermost mantle and the lower mantle, respectively, and their properties, which can be strongly influenced by the electronic state of iron in these phases, affect our understanding of the nature of the deep Earth. To date, in these minerals the electronic spin state of iron remains unknown under lowermost-mantle pressure-temperature conditions, although recent studies have showed an electronic spin crossover from high-spin to low-spin in ferropericlase over an extended pressure-temperature range of the lower mantle (i.e., Lin et al., Science, 2007) and from high-spin to intermediate-spin in silicate perovskite near the top of the lower mantle (McCammon et al., Nature Geoscience, 2008). Here we report the spin and valence states of iron in post-perovskite and perovskite at pressure-temperature conditions relevant to the lowermost mantle using in situ X-ray emission, X-ray diffraction, and synchrotron Mossbauer spectroscopies in a laser-heated diamond cell. Perovskite and post-perovskite display extremely high quadrupole splitting (QS) of approximately 4 mm/s and relatively high center shift in the synchrotron Mossbauer spectra at 110 GPa and 134 GPa, respectively. Our results show that Fe2+ exists predominantly in the intermediate-spin state with a total spin number of one in both phases (Lin et al., Nature Geoscience, 2008). Together with recent results on the effects of the spin transition in the lower-mantle ferropericlase (see a recent review by Lin and Tsuchiya, PEPI, 2008), here we will address how the electronic spin states in lower-mantle phases and their associated effects affect our understanding on the composition, geophysics, and dynamics of the lower mantle.. References: 1. Lin, J. F., H. C. Watson, G. Vanko, E. E. Alp, V. B. Prakapenka, P. Dera, V. V. Struzhkin, A. Kubo, J. Zhao, C. McCammon, W. J. Evans, Intermediate-spin ferrous iron in lowermost mantle post-perovskite and perovskite, Nature Geosciences, 2008. 2. Lin, J. F., and T. Tsuchiya, Spin transition of iron in the Earth's lower mantle, Phys. Earth Planet. Inter., doi:10.1016/j.pepi.2008.01.005, 2008. 3. Lin, J. F., G. Vanko, S. D. Jacobsen, V. Iota-Herbei, V. V. Struzhkin, V. B. Prakapenka, A. Kuznetsov, and C.-S.Yoo, Spin transition zone in Earth's lower mantle, Science, 317, 1740-1743, 2007.

Lin, J.; Watson, H. C.; Vanko, G.; Alp, E. E.; Prakapenka, V.; Dera, P.; Struzhkin, V. V.; Kubo, A.; Zhao, J.; McCammon, C.; Evans, W. J.

2008-12-01

344

Highly Bright Avidin-based Affinity Probes Carrying Multiple Lanthanide Chelates  

PubMed Central

Lanthanide ion luminescence has a long lifetime enabling highly sensitive detection in time-gated mode. The sensitivity can be further increased by using multiple luminescent labels attached to a carrier molecule, which can be conjugated to an object of interest. We found that up to 30 lanthanide chelates can be attached to avidin creating highly bright constructs. These constructs with Eu3+ chelates display synergistic effect that enhance the brightness of heavily modified samples, while the opposite effect was observed for Tb3+ chelates thereby significantly reducing their light emission. This undesirable quenching of Tb3+ luminophores was completely suppressed by the introduction of an aromatic spacer between the chelate and the protein attachment site. The estimated detection limit for the conjugates is in the 10-14 – 10-15 M range. We demonstrated a high sensitivity for the new probes by using them to label living cells of bacterial and mammalian origin. PMID:23018156

Wirpsza, Laura; Pillai, Shyamala; Batish, Mona; Marras, Salvatore; Krasnoperov, Lev; Mustaev, Arkady

2012-01-01

345

Bifunctional chelates of RH-105 and AU199 as potential radiotherapeutic agents  

SciTech Connect

Research is presented on new bifunctional chelating ligand systems with stability on the macroscopic and radiochemical levels. The synthesis of the following complexes are described: rhodium 105, palladium 109, and gold 198.

Droege, P.

1997-03-01

346

Design, synthesis and characterization of new iron and aluminium chelating agents.  

E-print Network

??Chelation therapy is widely used for metal-unbalance related diseases, namely those due to disorders on metal metabolism, such as beta-thalassemia, hemochromatosis (Fe), and neurodegenerative diseases… (more)

Toso, Leonardo

2014-01-01

347

Iron chelators inhibit human platelet aggregation, thromboxane A2 synthesis and lipoxygenase activity.  

PubMed

The iron chelators desferrioxamine and 1,2-dimethyl-3-hydroxypyrid-4-one (L1) inhibited human platelet aggregation in vitro as well as thromboxane A2 synthesis and conversion of arachidonate to lipoxygenase-derived products. Non-chelating compounds related to L1 were without effect on cyclooxygenase or lipoxygenase activity. Since both cyclooxygenase and lipoxygenase are iron-containing enzymes, it is suggested that the inhibition of platelet function by these iron chelators may be related to the removal or binding of iron associated with these enzymes. These iron chelators may therefore be of potential therapeutic value as platelet antiaggregatory agents and of possible use in the treatment of atherosclerotic and inflammatory joint diseases. PMID:2494068

Barradas, M A; Jeremy, J Y; Kontoghiorghes, G J; Mikhailidis, D P; Hoffbrand, A V; Dandona, P

1989-03-13

348

Click-to-Chelate: development of technetium and rhenium-tricarbonyl labeled radiopharmaceuticals.  

PubMed

The Click-to-Chelate approach is a highly efficient strategy for the radiolabeling of molecules of medicinal interest with technetium and rhenium-tricarbonyl cores. Reaction of azide-functionalized molecules with alkyne prochelators by the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC; click reaction) enables the simultaneous synthesis and conjugation of tridentate chelating systems for the stable complexation of the radiometals. In many cases, the functionalization of (bio)molecules with the ligand system and radiolabeling can be achieved by convenient one-pot procedures. Since its first report in 2006, Click-to-Chelate has been applied to the development of numerous novel radiotracers with promising potential for translation into the clinic. This review summarizes the use of the Click-to-Chelate approach in radiopharmaceutical sciences and provides a perspective for future applications. PMID:23481882

Kluba, Christiane A; Mindt, Thomas L

2013-01-01

349

21 CFR 176.150 - Chelating agents used in the manufacture of paper and paperboard.  

Code of Federal Regulations, 2010 CFR

...Chelating agents used in the manufacture of paper and paperboard. 176.150 Section...CONTINUED) INDIRECT FOOD ADDITIVES: PAPER AND PAPERBOARD COMPONENTS Substances for Use Only as Components of Paper and Paperboard § 176.150...

2010-04-01

350

BENCH-SCALE RECOVERY OF LEAD USING AN ELECTROMEMBRANE/CHELATION PROCESS  

EPA Science Inventory

This report presents the results of a bench-scale treatability test to investigate key process parameters influencing an innovative chelation electrodeposition process for recovery of lead from contaminated sons. thylenediamine tetraacetic acid (EDTA) and diethylenetriamine penta...

351

BENCH-SCALE RECOVERY OF LEAD USING AND ELECTRO- MEMBRANE/CHELATION PROCESS  

EPA Science Inventory

This report presents the results of a bench-scale treatability test to investigate key process parameters influencing an innovative chelation electrodeposition process for recovery of lead from contaminated sons. thylenediamine tetraacetic acid (EDTA) and diethylenetriamine penta...

352

Theoretical analysis of the influence of chelate-ring size and vicinal effects on electronic circular dichroism spectra of cobalt(III) EDDA-type complexes.  

PubMed

To assess the contributions of configurational and vicinal effects as well as chelate-ring size to rotational strengths, the geometries of a series of cobalt(III) complexes [Co(EDDA-type)(L)](±) with the tetradentate EDDA-type ligands, EDDA (ethylenediamine-N,N'-diacetate), DMEDDA (N,N'-dimethylethylenediamine-N,N'-diacetate), DEEDDA (N,N'-diethylethylenediamine-N,N'-diacetate), and a bidentate ancillary ligand L (L = ethylenediamine, oxalate, carbonate, (S)-alanine, and malonate) in aqueous solution have been optimized at the DFT/B3LYP/6-311++G(2d,p) level of theory. Based on the optimized geometries, the excitation energies and oscillator and rotational strengths have been calculated using the time-dependent density functional theory (TDDFT) method with the same functional and basis set. The calculated circular dichroism (CD) curves are in excellent agreement with the observed ones except for some small red or blue shifts in peak wavelengths. For the influence of chelate-ring size of the bidentate ligands on the CD intensities, a qualitative analysis together with the quantitative TDDFT calculation reveal that it depends on the symmetry of the cobalt-EDDA backbone. For the s-cis-isomers, the influence is negligible due to the perturbation is symmetric. For the uns-cis-isomers, the perturbation is unsymmetric. Since a small ring size means a large perturbation, this leads to the integral CD intensities decreasing with increasing the chelate ring size. The vicinal effects of asymmetric nitrogens incorporate both the substitutent effects and conformational relaxation effects, with the former being dominant. By analyzing the contributions of chiral arrays to rotational strengths, we found that the part of contributions dominated by the S-type chiral nitrogens could be considered as a good measure for the vicinal effects of chiral nitrogens. In addition, we found that the twist form (?/?) of the backbone ethylenediamine ring (E-ring) of the coordinated EDDA-type ligands is a key factor to understand the properties of these chelates, because it not only dominates the relative stabilities of the s-cis-?(SS)-diastereoisomers with the result that ? > ? but also affects the major CD band by changing the order of the first two transitions. Moreover, the twist angle of E-ring is inversely related to the vicinal effect of chiral nitrogens. These findings may help us to understand the chelate ring size as well as vicinal effect related chiroptical phenomenon of the cobalt EDDA-type chelates. PMID:23713886

Wang, Ai; Wang, Yuekui; Jia, Jie; Feng, Lixia; Zhang, Chunxia; Liu, Linlin

2013-06-20

353

Chelating ability and biological activity of hesperetin Schiff base.  

PubMed

Hydrazone hesperetin Schiff base (HHSB) - N-[(±)-[5,7-dihydroxy-2-(3-hydroxy-4-methoxy-phenyl)chroman-4-ylidene]amino]benzamide has been synthesized and its crystal structure was determined. This compound was used for the formation of Cu(II) complexes in solid state and in solution which were characterized using different spectroscopic methods. The analyses of potentiometric titration curves revealed that monomeric and dimeric complexes of Cu(II) are formed above pH7. The ESI-MS (electrospray ionization-mass spectrometry) spectra confirmed their formation. The EPR and UV-visible spectra evidenced the involvement of oxygen and nitrogen atoms in Cu(II) coordination. Hydrazone hesperetin Schiff base can show keto-enol tautomerism and coordinate Cu(II) in the keto (O(-), N, Oket) and in the enolate form (O(-), N, O(-)enol). The semi-empirical molecular orbital method PM6 and DFT (density functional theory) calculations have revealed that the more stable form of the dimeric complex is that one in which the ligand is present in the enol form. The CuHHSB complex has shown high efficiency in the cleavage of plasmid DNA in aqueous solution, indicating its potential as chemical nuclease. Studies on DNA interactions, antimicrobial and cytotoxic activities have been undertaken to gain more information on the biological significance of HHSB and copper(II)-HHSB chelate species. PMID:25486205

Lodyga-Chruscinska, Elzbieta; Symonowicz, Marzena; Sykula, Anna; Bujacz, Anna; Garribba, Eugenio; Rowinska-Zyrek, Magdalena; Oldziej, Stanislaw; Klewicka, Elzbieta; Janicka, Magdalena; Krolewska, Karolina; Cieslak, Marcin; Brodowska, Katarzyna; Chruscinski, Longin

2014-11-28

354

Multifunctional iron-chelators with protective roles against neurodegenerative diseases.  

PubMed

The multifactorial nature of Alzheimer's disease (AD), and the absence of a disease modifying drug, makes the development of new multifunctional drugs an attractive therapeutic strategy. Taking into account the hallmarks of AD patient brains, such as low levels of acetylcholine, misfolding of proteins and associated beta-amyloid (A?) aggregation, oxidative stress and metal dyshomeostasis, we have developed a series of compounds that merge three different approaches: metal attenuation, anti-A? aggregation and anti-acetylcholinesterase activity. Therefore, 3-hydroxy-4-pyridinone (3,4-HP) and benzothiazole molecular moieties were selected as starting frameworks due to their well known affinity for iron and A? peptides, respectively. The linkers between these two main functional groups were selected on the basis of virtual screening, so that the final molecule could further inhibit the acetylcholinesterase, responsible for the cholinergic losses. We describe herein the design and synthesis of the new hybrid compounds, followed by the assessment of solution properties, namely iron chelation and anti-oxidant capacity. The compounds were bioassayed for their capacity to inhibit AChE, as well as self- and Zn mediated-A?(1-42) aggregation. Finally, we assessed their effects on the viability of neuronal cells stressed with A?(42). PMID:23487286

Nunes, Andreia; Marques, Sérgio M; Quintanova, Catarina; Silva, Diana F; Cardoso, Sandra M; Chaves, Sílvia; Santos, M Amélia

2013-05-01

355

Desferrithiocin analogue iron chelators: iron clearing efficiency, tissue distribution, and renal toxicity  

Microsoft Academic Search

The current solution to iron-mediated damage in transfusional iron overload disorders is decorporation of excess unmanaged\\u000a metal, chelation therapy. The clinical development of the tridentate chelator deferitrin (1, Table 1) was halted due to nephrotoxicity. It was then shown by replacing the 4?-(HO) of 1 with a 3,6,9-trioxadecyloxy group, the nephrotoxicity could be ameliorated. Further structure–activity relationship studies\\u000a have established that

Raymond J. Bergeron; Jan Wiegand; Neelam Bharti; James S. McManis; Shailendra Singh

2011-01-01

356

Design and Methodology of the Trial to Assess Chelation Therapy (TACT)  

Microsoft Academic Search

The Trial to Assess Chelation Therapy (TACT) is an NIH-sponsored, randomized, double blind, placebo-controlled, 2x2 factorial clinical trial testing the benefits and risks of 40 infusions of a multi-component Na2EDTA-chelation solution compared with placebo, and of an oral, high-dose multivitamin and mineral supplement. TACT has randomized and will follow 1708 patients for an average of approximately 4 years. The primary

Gervasio A. Lamas; Christine Goertz; Robin Boineau; Daniel B. Mark; Theodore Rozema; Richard L. Nahin; Jeanne A. Drisko; Kerry L. Lee

357

Pulmonary embolism developing in patients with sickle cell disease on hypertransfusion and IV deferoxamine chelation therapy  

Microsoft Academic Search

Pulmonary disease, including thromboembolic problems, accounts for a large portion of the morbidity of sickle cell disease.\\u000a Chronic transfusion therapy is now a part of long-term treatment of sickle cell patients with stroke and chest syndrome. The\\u000a resultant iron overload must be treated with chelation therapy using deferoxamine. Poor compliance with subcutaneous chelation\\u000a therapy has necessitated intravenous deferoxamine treatment. We

Sujit Sheth; Carrie Ruzal-Shapiro; Anne Hurlet-Jensen; Sergio Piomelli; Walter E. Berdon

1997-01-01

358

Comparative efficacy and toxicity of desferrioxamine, deferiprone and other iron and aluminium chelating drugs.  

PubMed

The efficacy and toxicity aspects of the iron and aluminium chelating drugs desferrioxamine and deferiprone (L1, 1,2-dimethyl-3-hydroxypyrid-4-one), have been compared. Major emphasis was given in the use of these two and also of other chelators in conditions of iron overload, imbalance and toxicity, as well as the incidence and possible causes of toxic side effects in both animals and humans. The chemical basis of chelation and the interaction of these chelators with the iron pools are discussed within the context of clinical application in iron overload and other conditions such as renal dialysis, rheumatoid arthritis, cancer, heart disease, malaria, etc. The design and development of new orally active alpha-ketohydroxypyridine and other chelators are considered and compared with 14 other chelators which have been previously tested in man for the removal of iron, most of which, however, were later abandoned because of low efficacy or major toxicity. The design of new therapeutic protocols based on the pharmacological, toxicological and metabolic transformation properties of the chelating drugs is also being considered, within the context of maximising their efficacy and minimising their toxicity. Overall, oral deferiprone appears to be as effective as s.c. desferrioxamine in the removal of iron and aluminium in man and to have a similar but different toxicity profile from desferrioxamine in both animals and man. The low cost and oral activity of deferiprone will make it the drug of choice for the vast majority of patients, who are not currently being chelated either because they cannot afford the high cost of desferrioxamine therapy or are not complying or have toxic side effects with its s.c. administration. PMID:7482575

Kontoghiorghes, G J

1995-10-01

359

Removal of Heavy Metal Ions using New Chelating Material Containing N, O, and S Donor Sites  

Microsoft Academic Search

A new chelating material (AT?PHE?HCHO) was synthesized by reacting 2?aminothiazole?phenol (AT?PHE) azodye and formaldehyde (HCHO) in an alkaline medium. The materials were characterized by elemental analysis, FT?IR and H?NMR spectroscopic studies. The chelating material was used for the adsorption of Cu(II), Zn(II), Mn(II), and Cr(III) from dilute aqueous solutions with variation of adsorption parameters. The adsorption was described quantitatively by

R. K. Dey; Tanushree Patnaik; Neelkamal Mohapatra; S. Samal

2007-01-01

360

Adsorption of metal ions on polyaminated highly porous chitosan chelating resin  

Microsoft Academic Search

Highly porous chelating resin was fabricated from the natural polysaccharide chitosan. The adsorption capacity was increased by polyamination with poly(ethylene imine) (MW = 10,000). The capacity was about 1-2 times larger than that of commercial chelate resins. The selectivity for adsorption of metal ions on the resin, which was determined for a single solute at pH [approx equal] 7, was

Yoshihide Kawamura; Masaki Mitsuhashi; Hiroaki Tanibe; Hiroyuki Yoshida

1993-01-01

361

Europium(III)-chelates embedded in nanoparticles are protected from interfering compounds present in assay media.  

PubMed

Lanthanide chelates are excellent labels in ligand binding assays due to their long lifetime fluorescence, which enables efficient background reduction using time-resolved measurement. In separation-free homogeneous assays, however, some compounds in the sample may cause quenching of the lanthanide fluorescence and extra steps are required before these samples can be measured. In this study we have evaluated whether europium chelates packed inside a polystyrene nanoparticle are better protected from the environment than individual Eu(III)-chelates, and do these particles have higher tolerance against known interfering compounds (bivalent metal ions and variation of pH). We also tested whether metal ions had any effect on a fluorescence resonance energy transfer (FRET) based detection of a bioaffinity binding reaction. The presence of metal ions or variation of pH did not affect the fluorescence of the Eu(III)-chelate dyed nanoparticles, while significant decrease of the fluorescence was detected with a 9-dentate Eu(III)-chelate. Metal ions also decreased the fluorescence lifetime of the 9-dentate Eu(III)-chelate from 0.960 to 0.050 ms. Coloured metal ions caused a minor decrease in sensitised emission generated by FRET when Eu(III)-chelate dyed nanoparticles were used as donor labels. The decreased signal was due to the absorption of the sensitised emission by the coloured metal ions, since the metal ions had no effect on the lifetime of the sensitised emission. Thus the Eu(III)-chelate dyed nanoparticles are preferred labels in homogeneous bioaffinity assays, when interfering compounds are known to be present. PMID:17386642

Kokko, Leena; Lövgren, Timo; Soukka, Tero

2007-02-28

362

Alternative chelating agents: evaluation of the ready biodegradability and complexation properties.  

PubMed

The ready biodegradability of four chelating agents, N,N'-(S,S)-bis[1-carboxy-2-(imidazol-4-yl)ethyl]ethylenediamine (BCIEE), N'-ethylenedi-L-cysteine (EC), N,N'-bis (4-imidazolymethyl)ethylenediamine (EMI) and 2,6-pyridine dicarboxylic acid (PDA), was tested according to the OECD guideline for testing of chemicals. PDA proved to be a readily biodegradable substance. However, none of the other three compounds were degraded during the 28 days of the test. Chemical simulations were performed for the four compounds in order to understand their ability to complex with some metal ions (Ca, Cd, Co, Cu, Fe, Mg, Mn, Ni, Pb, Zn) and discuss possible applications of these chelating agents. Two different conditions were simulated: (i) in the presence of the chelating agent and one metal ion, and (ii) in the simultaneous presence of the chelating agent and all metal ions with an excess of Ca. For those compounds that were revealed not to be readily biodegradable (BCIEE, EC and EMI), applications were evaluated where this property was not fundamental or even not required. Chemical simulations pointed out that possible applications for these chelating agents are: food fortification, food process, fertilizers, biocides, soil remediation and treatment of metal poisoning. Additionally, chemical simulations also predicted that PDA is an efficient chelating agent for Ca incrustations removal, detergents and for pulp metal ions removal process. PMID:24279626

Martins, João G; Neto, Isabel F F; Pinto, Isabel S S; Soares, Eduardo V; Barros, Maria Teresa; Soares, Helena M V M

2014-01-01

363

Translational Downregulation of HSP90 Expression by Iron Chelators in Neuroblastoma Cells.  

PubMed

Iron is an essential cellular nutrient, being a critical cofactor of several proteins involved in cell growth and replication. Compared with normal cells, neoplastic cells have been shown to require a greater amount of iron, thus laying the basis for the promising anticancer activity of iron chelators. In this work, we evaluated the effects of molecules with iron chelation activity on neuroblastoma (NB) cell lines. Of the 17 iron chelators tested, six reduced cell viability of two NB cell lines with an inhibition of growth of 50% below 10 µM; four of the six molecules-ciclopirox olamine (CPX), piroctone, 8-hydroxyquinoline, and deferasirox-were also shown to efficiently chelate intracellular iron within minutes after addition. Effects on cell viability of one of the compounds, CPX, were indeed dependent on chelation of intracellular iron and mediated by both G0/G1 cell cycle block and induction of apoptosis. By combined transcriptome and translatome profiling we identified early translational downregulation of several members of the heat shock protein group as a specific effect of CPX treatment. We functionally confirmed iron-dependent depletion of HSP90 and its client proteins at pharmacologically achievable concentrations of CPX, and we extended this effect to piroctone, 8-hydroxyquinoline, and deferasirox. Given the documented sensitivity of NB cells to HSP90 inhibition, we propose CPX and other iron chelators as investigational antitumor agents in NB therapy. PMID:25564462

Sidarovich, Viktoryia; Adami, Valentina; Gatto, Pamela; Greco, Valentina; Tebaldi, Toma; Tonini, Gian Paolo; Quattrone, Alessandro

2015-03-01

364

Dynamic Simulation of Pressure Driven Flow of Fluids with Suspended Ferrous Particles in a Micro Channel Under Magnetic Field  

NASA Astrophysics Data System (ADS)

This computational study focuses on the dynamics of individual ferrous particles and the flow of the incompressible Newtonian fluid under the effect of an externally applied magnetic field and pressure gradient in a two-dimensional micro channel with smooth walls. The particle dynamics is simulated as a discrete phase using MATLAB code and the fluid flow is solved as a continuous phase using Computational Fluid Dynamics Software FLUENT. Interaction between the particle and fluid phases are included as hydrodynamic forces predicated by the fluid phase simulation and updated particle locations determined by the particle phase solution under non-uniform magnetic field. Non-uniform magnetic field forces the particles to move to poles of the magnet, and results in their accumulation. This causes drastic change on the continuous phase flow and pressure distribution, which in turn influences the particle motion. Predicted dynamics of the suspended ferrous particles under magnetic field and flow of the carrier fluid with pressure gradient is in reasonably well agreement with previous work. The results show that non-uniform magnetic field generated by externally placed magnets can be used to control the locations of the particles and flow of the fluid in a micro channel.

Ozcan, Sinan; Evrensel, Cahit A.; Pinsky, Mark A.; Fuchs, Alan

365

Performance of nitrate-dependent anaerobic ferrous oxidizing (NAFO) process: A novel prospective technology for autotrophic denitrification.  

PubMed

Nitrate-dependent anaerobic ferrous oxidizing (NAFO) is a valuable biological process, which utilizes ferrous iron to convert nitrate into nitrogen gas, removing nitrogen from wastewater. In this work, the performance of NAFO process was investigated as a nitrate removal technology. The results showed that NAFO system was feasible for autotrophic denitrification. The volumetric loading rate (VLR) and volumetric removal rate (VRR) under steady state were 0.159±0.01kg-N/(m(3)d) and 0.073±0.01kg-N/(m(3)d), respectively. In NAFO system, the effluent pH was suggested as an indicator which demonstrated a good correlation with nitrogen removal. The nitrate concentration was preferred to be less than 130mg-N/L. Organic matters had little influence on NAFO performance. Abundant iron compounds were revealed to accumulate in NAFO sludge with peak value of 51.73% (wt), and they could be recycled for phosphorus removal, with capacity of 16.57mg-P/g VS and removal rate of 94.77±2.97%, respectively. PMID:25576990

Zhang, Meng; Zheng, Ping; Li, Wei; Wang, Ru; Ding, Shuang; Abbas, Ghulam

2015-03-01

366

Dissimilatory ferrous iron oxidation at a low pH: a novel trait identified in the bacterial subclass Rubrobacteridae.  

PubMed

A novel iron-oxidizing acidophilic actinobacterium was isolated from spoil material at an abandoned copper mine. Phylogenetic analysis placed the isolate within the Rubrobacteridae subclass of the Actinobacteria. Its optimum temperature and pH for growth are 30-35 degrees C and pH 3.0, respectively. Although it could catalyze the dissimilatory oxidation of ferrous iron, growth yields declined progressively in media containing ferrous iron concentrations >100 microM. The isolate, Pa33, did not grow or oxidize iron in the absence of organic carbon, and appeared to be an obligate heterotroph. Specific rates of iron oxidation were much smaller than those determined for the autotrophic iron-oxidizing proteobacterium Acidithiobacillus ferrooxidans and the heterotrophic iron-oxidizing actinobacterium Ferrimicrobium acidiphilum. Iron oxidation by isolate Pa33 appears to be a defensive mechanism, in which iron oxidation converts a soluble species to which the bacterium is sensitive to an oxidized species (ferric iron) that is highly insoluble in the spoil from which it was isolated. This is the first report of acidophily or dissimilatory iron oxidation within the Rubrobacteridae subclass and one of very few within the Actinobacteria phylum as a whole. PMID:18803673

Bryan, Christopher G; Johnson, David B

2008-11-01

367

Ferricyanide-mediated oxidation of ferrous nitrosylated sperm whale myoglobin involves the formation of the ferric nitrosylated intermediate.  

PubMed

Ferricyanide-mediated oxidation of ferrous oxygenated and carbonylated myoglobin (Mb(II)-O(2) and Mb(II)-CO, respectively) is limited by O(2) and CO dissociation, respectively, then the transient deoxygenated derivative (Mb(II)) is rapidly oxidized. Here, kinetics of ferricyanide-mediated oxidation of ferrous nitrosylated sperm whale myoblobin (Mb(II)-NO) is reported. Unlike for Mb(II)-O(2) and Mb(II)-CO, ferricyanide reacts with Mb(II)-NO forming first a transient ferric nitrosylated species (Mb(III)-NO), followed by the ()NO dissociation from Mb(III)-NO. Values of the second-order rate constant for ferricyanide-mediated oxidation of Mb(II)-NO (i.e., for the formation of the transient Mb(III)-NO species) and of the first-order rate constant for ()NO dissociation from Mb(III)-NO (i.e., for Mb(III) formation) are (1.3+/-0.2)x10(6)M(-1)s(-1) and 7.6+/-1.3s(-1), respectively, at pH 8.3 and 20.0 degrees C. Since ()NO dissociation from Mb(II)-NO is very slow, and (unlike O(2) and CO) ()NO is a ligand for both Mb(II) and Mb(III), Mb(II)-NO can be oxidized without requiring ()NO dissociation. PMID:17562327

Ascenzi, Paolo; Petrella, Giovanni; Coletta, Massimo

2007-08-10

368

Study of the dose response of the system ferrous ammonium sulfate-sucrose-xylenol orange in acid aqueous solution  

NASA Astrophysics Data System (ADS)

An aqueous solution of ammonium ferrous sulfate-sucrose-xylenol orange in sulfuric acid (FSX) is proposed as a dosimetric system for the processes of gamma irradiation in a range between 0.3 and 6 Gy. This system is based on the indirect oxidation of ferrous ion by an organic compound (sucrose) to ferric ion and on the formation of a color complex of Fe3+ in an acidic medium with xylenol orange (a dye). After gamma radiation, an observable change occurs in the color of the system. Irradiation was executed at three different temperatures (13 °C, 22 °C, and 40 °C). A spectrometric readout method at 585 nm was employed to evaluate the system's dose response. In all of the cases analyzed, the responses had a linear behavior, and a slight effect of irradiation temperature was observed. Post-irradiation response was also evaluated and showed the stability of the solutions 24 h after the irradiation. The results obtained suggest that FSX might be used as a dosimeter for low doses of gamma irradiation because it provides a stable signal, good reproducibility, and an accessible technique for analysis.

Juarez-Calderon, J. M.; Negron-Mendoza, A.; Ramos-Bernal, S.

2014-11-01

369

Nitrate-dependent anaerobic ferrous oxidation (NAFO) by denitrifying bacteria: A perspective autotrophic nitrogen pollution control technology.  

PubMed

The nitrate-dependent anaerobic ferrous oxidation (NAFO) is an important discovery in the fields of microbiology and geology, which is a valuable biological reaction since it can convert nitrate into nitrogen gas, removing nitrogen from wastewater. The research on NAFO can promote the development of novel autotrophic biotechnologies for nitrogen pollution control and get a deep insight into the biogeochemical cycles. In this work, batch experiments were conducted with denitrifying bacteria as biocatalyst to investigate the performance of nitrogen removal by NAFO. The results showed that the denitrifying bacteria were capable of chemolithotrophic denitrification with ferrous salt as electron donor, namely NAFO. And the maximum nitrate conversion rates (qmax) reached 57.89mg(gVSSd)(-1), which was the rate-limiting step in NAFO. Fe/N ratio, temperature and initial pH had significant influences on nitrogen removal by NAFO process, and their optimal values were 2.0°C, 30.15°C and 8.0°C, respectively. PMID:25461924

Zhang, Meng; Zheng, Ping; Wang, Ru; Li, Wei; Lu, Huifeng; Zhang, Jiqiang

2014-10-14

370

Hardness improvement of TiC-reinforced ferrous surface composites fabricated by high-energy electron beam irradiation  

SciTech Connect

Metal matrix composites in general have excellent performance compared with metallic materials because of the ductile fracture behavior in addition to high strength and elastic modulus. Particularly, TiC-reinforced ferrous composites have highly stabilized TiC particles inside the matrix, and thus can be applied to structures requiring resistance to abrasion and corrosion and high-temperature properties. They are typically fabricated by powder metallurgy route, casting, liquid phase sintering, self-sustaining high-temperature synthesis, plasma spraying, and surface alloying using laser, but these methods usually demand complex processes to achieve homogeneous distribution of TiC particles. Recently, an attempt has been made in direct irradiation with high-energy electron beam in order to achieve surface hardening or surface alloying. In this study, a simple process was presented to fabricate a TiC-reinforced ferrous surface composite with enhanced surface hardness by depositing TiC powders on the surface of a plain carbon steel substrate and then irradiating high-energy electron beam.

Kwon, S.J.; Choo, S.H.; Lee, S. [Pohang Univ. of Science and Technology (Korea, Republic of)] [Pohang Univ. of Science and Technology (Korea, Republic of)

1998-12-18

371

Structure and catalytic activities of ferrous centers confined on the interface between carbon nanotubes and humic acid.  

PubMed

Preparation of heterogeneous catalysts with active ferrous centers is of great significance for industrial and environmental catalytic processes. Nanostructured carbon materials (NCM), which possess free-flowing ? electrons, can coordinate with transition metals, provide a confinement environment for catalysis, and act as potential supports or ligands to construct analogous complexes. However, designing such catalysts using NCM is still seldom studied to date. Herein, we synthesized a sandwich structured ternary complex via the coordination of Fe-loaded humic acid (HA) with C[double bond, length as m-dash]C bonds in the aromatic rings of carbon nanotubes (CNTs), in which the O/N-Fe-C interface configuration provides the confinement environment for the ferrous sites. The experimental and theoretical results revealed octahedrally/tetrahedrally coordinated geometry at Fe centers, and the strong hybridization between CNT C ?* and Fe 3d orbitals induces discretization of the atomic charges on aromatic rings of CNTs, which facilitates O2 adsorption and electron transfer from carbon to O2, which enhances O2 activation. The O2 activation by the novel HA/Fe-CNT complex can be applied in the oxidative degradation of phenol red (PR) and bisphenol A (BPA) in aqueous media. PMID:25580558

Wang, Bing; Zhou, Xiaoyan; Wang, Dongqi; Yin, Jun-Jie; Chen, Hanqing; Gao, Xingfa; Zhang, Jing; Ibrahim, Kurash; Chai, Zhifang; Feng, Weiyue; Zhao, Yuliang

2015-01-28

372

Effect of VOCs and methane in the biological oxidation of the ferrous ion by an acidophilic consortium.  

PubMed

During the elimination of H2S from biogas in an aqueous ferric sulphate solution, volatile organic compounds (VOCs) and methane are absorbed and may have an effect on the subsequent biological regeneration of ferric ion. This study was conducted to investigate the effect of maximum concentrations of methane and some VOCs found in biogas on the ferrous oxidation of an acidophilic microbial consortium (FO consortium). The presence and impact of heterotrophic microorganisms on the activity of the acidophilic consortium was also evaluated. No effect on the ferrous oxidation rate was found with gas concentrations of 1500 mg toluene m(-3), 1400 mg 2-butanol m(-3) or 1250 mg 1,2-dichloroethane m(-3), nor with methane at gas concentrations ranging from 15-25% (v/v). A tenfold increase in VOCs concentrations totally inhibited the microbial activity of the FO consortium and the heterotrophs. The presence of a heterotrophic fungus may promote the autotrophic growth of the FO consortium. PMID:22629626

Almenglo, F; Ramírez, M; Gómez, J M; Cantero, D; Revah, S; González-Sánchez, A

2012-01-01

373

Evaluation of efficacy and safety of iron polymaltose complex and folic acid (Mumfer) vs iron formulation (ferrous fumarate) in female patients with anaemia.  

PubMed

Treatment of iron deficiency anaemia with conventional oral preparations is handicapped by unpredictable haematological response in addition to potential for irritating gastrointestinal adverse events. Iron polymaltose complex (IPC), a novel oral iron formulation with better absorbability, predictable haematinic response and less side effects was compared with oral ferrous fumarate in 100 female patients with documented iron deficiency anaemia. Clinical parameters (pallor, weakness) as well as biochemical parameters (Hb, serum iron, total iron binding capacity) show favourable changes with IPC; the physician and patient assessment also favour IPC over ferrous fumarate. PMID:11478761

Reddy, P S; Adsul, B B; Gandewar, K; Korde, K M; Desai, A

2001-03-01

374

Enhancing Potentially Plant-Available Lead Concentrations in Contaminated Residential Soils Using a Biodegradable Chelating Agent  

NASA Astrophysics Data System (ADS)

Chelation of heavy metals is an important factor in enhancing metal solubility and, hence, metal availability to plants to promote phytoremediation. In the present study, we compared the effects of application of a biodegradable chelating agent, namely, ethylenediaminedisuccinic acid (EDDS) on enhancing plant available form of lead (Pb) in Pb-based paint contaminated residential soils compared to that of a more commonly used, but non-biodegradable chelate, i.e., ethylenediaminetetraacetic acid (EDTA). Development of a successful phytoremediation model for metals such as Pb depends on a thorough understanding of the physical and chemical properties of the soil, along with the optimization of a chelate treatment to mobilize Pb from `unavailable' pools to potentially plant available fraction. In this context, we set out to perform batch incubation experiments to investigate the effectiveness of the two aforementioned chelates in enhancing plant available Pb at four different concentrations (0, 5, 10 and 15 mM/kg soil) and three treatment durations (0, 10 and 30 days). We selected 12 contaminated residential soils from two major metropolitan areas (San Antonio, TX and Baltimore, MD) with varying soil physico-chemical properties - the soils from San Antonio were primarily alkaline and those from Baltimore were typically acidic. Total soil Pb concentrations ranged between 256 mg/kg and 4,182 mg/kg. Our results show that both chelates increased the solubility of Pb, otherwise occluded in the complex soil matrix. For both EDTA and EDDS, the exchangeable concentrations of soil Pb also increased with increase in chelate concentration and incubation time. The most effective treatment was 15 mM chelate kg-1 soil incubated for 30 days, which caused many fold increase in potentially plant available Pb (a combination of the soluble and exchangeable fractions) relative to the unamended controls. Step wise multiple linear regression analysis using chelate-extractable Pb and soil properties showed that plant available Pb fraction could be assessed from the two inter-related soil parameters: soil organic matter and soil pH. Although EDTA was more effective in Pb solubilization than EDDS, the rapid kinetics of the Pb-EDTA complexation process and the prolonged persistence of EDTA in soils pose a potential groundwater contamination problem via metal leaching. In contrast to EDTA, EDDS addition caused relatively slow release of Pb from the soil matrix. The biodegradable nature (and short half life) of EDDS in soils makes it a promising chelating agent for use as soil amendment to enhance Pb solubilization and hence, potential plant uptake.

Andra, S.; Datta, R.; Sarkar, D.; Saminathan, S.

2007-12-01

375

Combined chelation therapy with deferasirox and deferoxamine in thalassemia.  

PubMed

Iron overload is the primary cause of mortality and morbidity in thalassemia major despite advances in chelation therapy. We performed a pilot clinical trial to evaluate the safety and efficacy of combined therapy with deferasirox (DFX, 20-30 mg/kg daily) and deferoxamine (DFO, 35-50mg/kg on 3-7 days/week) in 22 patients with persistent iron overload or organ damage. In the 18 subjects completing 12 months of therapy, median liver iron concentration decreased by 31% from 17.4 mg/g (range 3.9-38.2mg/g) to 12.0mg/g (range 0.96-26.7 mg/g, p<0.001). Median ferritin decreased by 24% from 2465 ng/mL (range 1110-10,700 ng/mL) to 1875 ng/mL (range 421-5800 ng/mL, p=0.002). All 6 subjects with elevated myocardial iron showed improvement in MRI T2* (p=0.031). The mean±S.E. plasma non-transferrin-bound iron (NTBI) declined from 3.10±0.25?M to 2.15±0.29?M (p=0.028). The administration of DFX during infusion of DFO further lowered NTBI (-0.28±0.08 ?M, p=0.004) and labile plasma iron (LPI, -0.03±0.01 ?M, p=0.006). The simultaneous administration of DFO and DFX rapidly reduced systemic and myocardial iron, and provided an excellent control of the toxic labile plasma iron species without an increase in toxicity. PMID:23151373

Lal, Ashutosh; Porter, John; Sweeters, Nancy; Ng, Vivian; Evans, Patricia; Neumayr, Lynne; Kurio, Gregory; Harmatz, Paul; Vichinsky, Elliott

2013-02-01

376

Thumbnail Sketches: EDTA-Type Chelating Agents in Everyday Consumer Products: Some Medicinal and Personal Care Products.  

ERIC Educational Resources Information Center

Discusses various ethylenediaminetetraacetate (EDTA)-type chelating agents found in ophthalmic products, personal care products, and disinfectants. Also discusses the properties and action of these EDTA agents. (JN)

Hart, J. Roger

1984-01-01

377

Ferrous Silicate Spherules with Euhedral Fe,Ni-Metal Grains in CH Carbonaceous Chondrites: Evidence for Condensation Under Highly Oxidizing Conditions  

NASA Technical Reports Server (NTRS)

A population of ferrous silicate spherules composed of cryptocrystalline ol-px-normative material, +/-SiO2-rich glass and rounded-to-euhedral Fe,Ni-metal grains preserved a condensation signature of the precursors formed under oxidizing conditions.

Krot, A. N.; Meibom, A.; Petaev, M. I.; Keil, K.; Zolensky, M. E.; Saito, A.; Mukai, M.; Ohsumi, K.

2000-01-01

378

Elimination of matrix effects in the determination of oxygen in some non-ferrous metals by activation with 14 MeV neutrons  

Microsoft Academic Search

It is shown in this paper that the lower limit of detection and specificity of oxygen determination in strongly activated\\u000a non-ferrous metals can be improved by means of the optimization of Pb-absorber thickness, cooling time and cyclic activation\\u000a analysis. Some mathematical predictions are verified by oxygen determination in copper and yttrium.

Z. Szopa; S. Sterlinski; G. Tetteh

1981-01-01

379

Effects of ferrous sulphate and non-ionic iron-polymaltose complex on markers of oxidative tissue damage in patients with inflammatory bowel disease  

Microsoft Academic Search

SUMMARY Background: Iron deficiency is a common complication of inflammatory bowel disease. Oral iron therapy may reinforce intestinal tissue injury by catalyzing produc- tion of reactive oxygen species. Aim: To compare the effects of ferrous sulphate and non- ionic iron-polymaltose complex on markers of oxidative tissue damage and clinical disease activity in patients with inflammatory bowel disease. Methods: Forty-one patients

E RICHSEN

380

Identifying Chelators for Metalloprotein Inhibitors Using a Fragment-Based Approach  

PubMed Central

Fragment-based lead design (FBLD) has been used to identify new metal-binding groups for metalloenzyme inhibitors. When screened at 1 mM, a chelator fragment library (CFL-1.1) of 96 compounds produced hit rates ranging from 29–43% for five matrix metalloproteases (MMPs), 24% for anthrax lethal factor (LF), 49% for 5-lipoxygenase (5-LO), and 60% for tyrosinase (TY). The ligand efficiencies (LE) of the fragment hits are excellent, in the range of 0.4–0.8 kcal/mol. The MMP enzymes all generally elicit the same chelators as hits from CFL-1.1; however, the chelator fragments that inhibit structurally unrelated metalloenzymes (LF, 5-LO, TY) vary considerably. To develop more advanced hits, one hit from CFL-1.1, 8-hydroxyquinoline, was elaborated at four different positions around the ring system to generate new fragments. 8-Hydroxyquinoline fragments substituted at either the 5- or 7-positions gave potent hits against MMP-2, with IC50 values in the low micromolar range. The 8-hydroxyquinoline represents a promising, new chelator scaffold for the development of MMP inhibitors that was discovered by use of a metalloprotein-focused chelator fragment library. PMID:21189019

Jacobsen, Jennifer A.; Fullagar, Jessica; Miller, Melissa T.; Cohen, Seth M.

2011-01-01

381

Comparison of various iron chelators and prochelators as protective agents against cardiomyocyte oxidative injury.  

PubMed

Oxidative stress is a common denominator of numerous cardiovascular disorders. Free cellular iron catalyzes the formation of highly toxic hydroxyl radicals, and iron chelation may thus be an effective therapeutic approach. However, using classical iron chelators in diseases without iron overload poses risks that necessitate more advanced approaches, such as prochelators that are activated to chelate iron only under disease-specific oxidative stress conditions. In this study, three cell-membrane-permeable iron chelators (clinically used deferasirox and experimental SIH and HAPI) and five boronate-masked prochelator analogs were evaluated for their ability to protect cardiac cells against oxidative injury induced by hydrogen peroxide. Whereas the deferasirox-derived agents TIP and TRA-IMM displayed negligible protection and even considerable toxicity, the aroylhydrazone prochelators BHAPI and BSIH-PD provided significant cytoprotection and displayed lower toxicity after prolonged cellular exposure compared to their parent chelators HAPI and SIH, respectively. Overall, the most favorable properties in terms of protective efficiency and low inherent cytotoxicity were observed with the aroylhydrazone prochelator BSIH. BSIH efficiently protected both H9c2 rat cardiomyoblast-derived cells and isolated primary rat cardiomyocytes against hydrogen peroxide-induced mitochondrial and lysosomal dysregulation and cell death. At the same time, BSIH was nontoxic at concentrations up to its solubility limit (600 ?M) and in 72-h incubation. Hence, BSIH merits further investigation for prevention and/or treatment of cardiovascular disorders associated with a known (or presumed) component of oxidative stress. PMID:24992833

Jansová, Hana; Machá?ek, Miloslav; Wang, Qin; Hašková, Pavlína; Jirkovská, Anna; Pot??ková, Eliška; Kielar, Filip; Franz, Katherine J; Sim?nek, Tomáš

2014-09-01

382

Chelating agents for the sequestration of mercury(II) and monomethyl mercury(II).  

PubMed

Both mercury(II) and monomethyl mercury(II) poisonings are of great concern for several reasons. As it happens for other metals, chelation therapy is the most indicated treatment for poisoned patients. The efficacy of the therapy and the reduction of side-effects can be sensibly enhanced by an accurate knowledge of all the physiological mechanisms involved in metal uptake, transport within and between various tissues, and (possibly) clearance. All these aspects, however, are strictly dependent on the chemical speciation (i.e., the distribution of the chemical species of a component in a given system) of both the metal and the chelating agent in the systems where they are present. In this light, this review analyzes the state of the art of research performed in this field for mercury(II) and methylmercury(II). After a brief summary of their main sources, the physiological patterns for the treatment of mercury poisoning have also been considered. The binding ability of various chelating agents toward mercury has been then analyzed by modeling the behavior of the main classes of ligands present in biological fluids and/or frequently used in chelation therapy. Their sequestering ability has been successively evaluated by means of a semiempirical parameter already proposed for its objective quantification, and the main characteristics of an efficient chelating agent have been evaluated on this basis. PMID:24934341

Crea, Francesco; De Stefano, Concetta; Foti, Claudia; Milea, Demetrio; Sammartano, Silvio

2014-01-01

383

Application of anion-exchange resin to remove lipophilic chelates from liposomes  

SciTech Connect

Lipophilic chelates such as 8-hydroxyquinoline, acetylacetone, and tropolone are useful to load high levels of radioactive cations into the inner aqueous compartments of liposomes for investigating the fate of liposomes by the technique of gamma imaging or gamma-ray perturbed angular correlation measurements. However, if lipophilic chelates are not completely removed from liposomes the very same lipophilic chelates can also cause leakage of the entrapped cations from liposomes. Thus, it is essential to make sure that all the lipophilic chelates are removed from liposomes after the loading process. The results of the present study show that more than 99.85% of acetylacetone in liposomal suspension can be removed by a minicolumn of AG1-X8 (phosphate form) anion exchange resin. Virtually all the 8-hydroxyquinoline and tropolone in liposomal suspension are adsorbed tightly to the resin. The procedure is rapid, and the dilution of liposomes is minimal. For experiments involving high levels of gamma-emitting radionuclides, the cleaning up process of removing lipophilic chelates from liposomes can be conveniently operated behind a lead glass.

Choi, H.O.; Hwang, K.J.

1986-07-01

384

PHARMACOLOGICAL PROPERTIES OF ORALLY AVAILABLE, AMPHIPATHIC POLYAMINOCARBOXYLIC ACID CHELATORS FOR ACTINIDE DECORPORATION  

PubMed Central

Commonly used water-soluble polyaminocarboxylic acid (PACA) chelators, such as (EDTA) and DTPA, require intravenous or subcutaneous administration due to their poor bioavailability. The bioavailability of PACAs can be improved by the addition of differing lengths of alkyl side chains that alter amphipathic properties. Orally administered amphipathic triethylenetetramine pentaacetic acid (TT) compounds are efficacious for decorporation of Pu and Am. The synthesis, efficacy, binding affinities, and some initial pharmacokinetics properties of amphipathic TT chelators are reviewed. 14C-Labeled C12TT and C22TT chelators are reasonably well absorbed from the intestine and have a substantial biliary/fecal excretion pathway, unlike DTPA, which is mostly excreted in the urine. Whole body retention times are increased as a function of increasing lipophilicity. Neutron-induced autoradiography studies demonstrate that the oral administration of the chelators can substantially inhibit the redistribution of 239Pu in skeletal tissues. In summary, amphipathic TT-based chelators have favorable bioavailability, have a significant biliary excretion pathway, have demonstrated efficacy for americium and plutonium and are thus good candidates for further development. Furthermore, some of the pharmacological properties can be manipulated by changing the lengths of the alkyl side chains and this may have some advantage for decorporation of certain metals and radionuclides. PMID:20699705

Miller, Scott C.; Wang, Xuli; Bowman, Beth M.

2010-01-01

385

Iron Chelators with Topoisomerase-Inhibitory Activity and Their Anticancer Applications  

PubMed Central

Abstract Significance: Iron and topoisomerases are abundant and essential cellular components. Iron is required for several key processes such as DNA synthesis, mitochondrial electron transport, synthesis of heme, and as a co-factor for many redox enzymes. Topoisomerases serve as critical enzymes that resolve topological problems during DNA synthesis, transcription, and repair. Neoplastic cells have higher uptake and utilization of iron, as well as elevated levels of topoisomerase family members. Separately, the chelation of iron and the cytotoxic inhibition of topoisomerase have yielded potent anticancer agents. Recent Advances: The chemotherapeutic drugs doxorubicin and dexrazoxane both chelate iron and target topoisomerase 2 alpha (top2?). Newer chelators such as di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone and thiosemicarbazone -24 have recently been identified as top2? inhibitors. The growing list of agents that appear to chelate iron and inhibit topoisomerases prompts the question of whether and how these two distinct mechanisms might interplay for a cytotoxic chemotherapeutic outcome. Critical Issues: While iron chelation and topoisomerase inhibition each represent mechanistically advantageous anticancer therapeutic strategies, dual targeting agents present an attractive multi-modal opportunity for enhanced anticancer tumor killing and overcoming drug resistance. The commonalities and caveats of dual inhibition are presented in this review. Future Directions: Gaps in knowledge, relevant biomarkers, and strategies for future in vivo studies with dual inhibitors are discussed. Antioxid. Redox Signal. 00, 000–000. PMID:22900902

2013-01-01

386

[Extraction of Cd by ramie from soils as affected by applications of chelators and peat].  

PubMed

Pot experiments were performed to study the effectiveness of chelators (EDTA, citric acid) and peat in enhancing phyremediation of heavy metal Cd by ramie. The results showed that peat increased the ramie's biomass by improving soil's physical and chemical properties, and the relative yields of peat alone, chelators(EDTA, citric acid) combined with peat were 1.23, 1.13 and 1.41 respectively. So the combination of citric acid and peat was more useful for growth of the ramie. As far as improving Cd uptake was concerned, it seemed that the combination of chelators with peat significantly promoted Cd uptake by the plant, and the percent of changeable Cd in soil were 61.6% and 58.3% . In addition, it had better bioaccumulation effects to combine with chelators and peat, of which Cd bioaccumulation coefficients were 1.33 and 1.32, compared to 1.11, 1.11 and 1.05 in application of peat, EDTA and citric acid respectively. What's more, cadmium removal rates in soil were up to 1.13% and 1.22% respectively in applications of two kinds of chleators (EDTA, citric acid) combined with peat. Therefore, it had better effects of phytoremediation to accumulate more cadmium amounts by combining with citric acid and peat because of more biomass. In conclusion, the phytoremediation by ramie can be more effective when chelators and peat were combined and added to soils. PMID:19927838

Shen, Li-Ping; Zong, Liang-Gang; Jiang, Pei; Liu, Wei-Xing; Jiang, Bo; Chen, Ya-Hua

2009-09-15

387

Comparison of various iron chelators and prochelators as protective agents against cardiomyocyte oxidative injury  

PubMed Central

Oxidative stress is a common denominator of numerous cardiovascular disorders. Free cellular iron catalyzes formation of highly toxic hydroxyl radicals and iron chelation may thus be an effective therapeutic approach. However, using classical iron chelators in diseases without iron overload poses risks that necessitate more advanced approaches, such as prochelators that are activated to chelate iron only under disease-specific oxidative stress conditions. In this study, three cell membrane-permeable iron chelators (clinically-used deferasirox and experimental SIH and HAPI) and five boronate-masked prochelator analogs were evaluated for their ability to protect cardiac cells against oxidative injury induced by hydrogen peroxide. Whereas the deferasirox-derived agents TIP and TRA-IMM displayed negligible protection and even considerable toxicity, aroylhydrazone prochelators BHAPI and BSIH-PD provided significant cytoprotection and displayed lower toxicity following prolonged cellular exposure compared to their parent chelators HAPI and SIH, respectively. Overall, the most favorable properties in terms of protective efficiency and low inherent cytotoxicity were observed with aroylhydrazone prochelator BSIH. BSIH efficiently protected both H9c2 rat cardiomyoblast-derived cells as well as isolated primary rat cardiomyocytes against hydrogen peroxide-induced mitochondrial and lysosomal dysregulation and cell death. At the same time, BSIH was non-toxic at concentrations up to its solubility limit (600 µM) and 72-hour incubation. Hence, BSIH merits further investigation for prevention and/or treatment of cardiovascular disorders associated with a known (or presumed) component of oxidative stress. PMID:24992833

Jansová, Hana; Machá?ek, Miloslav; Wang, Qin; Hašková, Pavlína; Jirkovská, Anna; Pot??ková, Eliška; Kielar, Filip; Franz, Katherine J.; Šim?nek, Tomáš

2014-01-01

388

Enhancement of the photocatalytic activity of Ferrous Oxide by doping onto the nano-clinoptilolite particles towards photodegradation of tetracycline.  

PubMed

Photodegradation of tetracycline (TC) aqueous solution by FeO doped onto nano-clinoptilolite particles was investigated using a high pressure Hg lamp as radiation source. Nano-particles of clinoptilolite were prepared using ball-milling of micro crystals of zeolite. The pretreated nano-particles ion exchanged in a ferrous solution and the Fe(II)-exchanged form was calcined at 450°C. All samples were characterized by FT-IR, DRS, SEM and XRD. The degradation extent was determined via UV-Vis absorption spectroscopy and COD. Based on the study of the effect of key operating parameters, the optimal conditions were determined to reach the higher efficiency of the process. The best photocatalytic activity was obtained in presence of the catalyst containing 5.4% FeO. PMID:24875881

Nezamzadeh-Ejhieh, Alireza; Shirzadi, Arezoo

2014-07-01

389

Optimisation of polymer coating process for microencapsulating ferrous fumarate for salt double fortification with iodine and iron.  

PubMed

An extrusion-based encapsulation process has been developed for making salt grain-sized iron premix for salt fortification. The first step of extrusion agglomeration process has been studied and reported previously. The focus of this study is on the optimisation of the colour-masking and polymer coating steps. Several colour-masking techniques and polymer encapsulants were investigated at various encapsulation levels. Salt samples prepared by blending the resulting iron premixes with iodised salt retained more than 90% of the original iodine and more than 93% of the ferrous iron after 3 months storage at 35°C and 60% relative humidity (RH). Hydrophilic coatings such as hydroxypropyl methyl cellulose (HPMC) offered more protection at the 10% encapsulation level compared to other coating materials studied. All iron premix formulations exhibited high particle density, good bioavailability and acceptable organoleptic properties. The process using the most effective formulations and optimised operation parameters is ready for pilot scale testing and field studies. PMID:22873200

Yadava, Divya; Olive Li, Yao; Diosady, Levente L; Wesley, Annie S

2012-01-01

390

X-ray absorption spectroscopic investigation of the resting ferrous and cosubstrate-bound active sites of phenylalanine hydroxylase.  

PubMed

Previous studies of ferrous wild-type phenylalanine hydroxylase, [Fe(2+)]PAH(T)[], have shown the active site to be a six-coordinate distorted octahedral site. After the substrate and cofactor bind to the enzyme ([Fe(2+)]PAH(R)[L-Phe,5-deaza-6-MPH(4)]), the active site converts to a five-coordinate square pyramidal structure in which the identity of the missing ligand had not been previously determined. X-ray absorption spectroscopy (XAS) at the Fe K-edge further supports this coordination number change with the binding of both cosubstrates to the enzyme, and determines this to be due to the loss of a water ligand. PMID:12009881

Wasinger, Erik C; Miti?, Natasa; Hedman, Britt; Caradonna, John; Solomon, Edward I; Hodgson, Keith O

2002-05-21

391

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

SciTech Connect

This thesis explores feasibility of using coated-wire electrodes to measure chelating agent concentration. Chelating agents are often found in radioactive decontamination solutions because they aid in the removal of radionuclides from contaminated surfaces by increasing their solubility. However, this characteristic will also enhance the mobility of the radionuclide and thus its transport out of a waste disposal site. Coated-wire ion selective electrodes, based on a polyvinylchloride membrane using dioctylphthalate as a plasticizer and dinonylnaphthalenesulfonic acid as a counterion, were constructed for five commonly utilized chelating agents (ethylenediaminetetracetic acid (EDTA), nitrilotriacetic acid (NTA), citric acid, oxalic acid and tartaric add). The EDTA and NTA electrodes` calibration characteristics exhibited acceptable behavior in pure standard solutions. From data obtained while using the EDTA and NTA electrodes in a cement environment, further research needs to be done in the area of ion interference.

Banks, M.L. [Arizona Univ., Tucson, AZ (United States)

1992-12-31

392

Renal handling of amino acid /sup 99m/technetium chelates  

SciTech Connect

Four amino acids--alanine, 2,3-diaminopropionic acid, cystine, and cystein--and also one diamine, ethylenediamine, were chelated with /sup 99m/-technetium (/sup 99m/Tc), and their renal excretion patterns were studied in rabbits in the presence and absence of two renal tubular transport inhibitors, probenecid and 2,4-dinitrophenol. From the depression of renal excretion for the first three amino acid chelates, in the presence of the inhibitors, a renal tubular excretory pathway of elimination was suggested for these compounds. The renal excretions of /sup 99m/Tc-cystein and /sup 99m/Tc-ethylenediamine however, remained undepressed under similar experimental conditions. An explanation of these observations was forwarded from the possible chemical structures of these chelates.

Chattopadhyay, M.; Banerjee, S.

1988-09-01

393

Assessment of methylsulfonylmethane as a permeability enhancer for regional EDTA chelation therapy.  

PubMed

Pharmacologic chelators do not effectively penetrate cell membranes and blood-brain barrier. This study assesses methylsulfonylmethane (MSM) as a permeability enhancer and an excipient to facilitate EDTA transport across biologic membranes, and to make possible localized, regional chelation. Topical application of MSM with C(14)EDTA onto the rat cornea led to uptake of the C(14)EDTA in all tested ocular tissues. Without MSM, EDTA did not penetrate the eye. The ability of MSM to deliver EDTA into an eye provides an opportunity for regional chelation therapy. Additionally, these studies suggest that MSM could also be an adjuvant for delivering ciprofloxacin and other chemical compounds to specific, local tissue sites. PMID:19538004

Zhang, Min; Wong, Ira G; Gin, Jerry B; Ansari, Naseem H

2009-07-01

394

A pro-chelator triggered by hydrogen peroxide inhibits iron-promoted hydroxyl radical formation.  

PubMed

The synthesis and structural characterization of a new pro-chelating agent, isonicotinic acid [2-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-benzylidene]-hydrazide (BSIH), are presented. BSIH only weakly interacts with iron unless hydrogen peroxide (H2O2) is present to remove the boronic ester protecting group to reveal a phenol that is a key metal-binding group of tridentate salicylaldehyde isonicotinoyl hydrazone (SIH). BSIH prevents deoxyribose degradation caused by hydroxyl radicals that are generated from H2O2 and redox-active iron by sequestering Fe3+ and preventing iron-promoted hydroxyl radical formation. The rate-determining step for iron sequestration is conversion of BSIH to SIH, followed by rapid Fe3+ complexation. The pro-chelate approach of BSIH represents a promising strategy for chelating a specific pool of detrimental metal ions without disturbing healthy metal ion distribution. PMID:16984186

Charkoudian, Louise K; Pham, David M; Franz, Katherine J

2006-09-27

395

Radiopharmaceutical stannic Sn-117m chelate compositions and methods of use  

DOEpatents

Radiopharmaceutical compositions including .sup.117m Sn labeled stannic (Sn.sup.4+) chelates are provided. The chelates are preferably polyhydroxycarboxylate, such as oxalates, tartrates, citrates, malonates, gluconates, glucoheptonates and the like. Methods of making .sup.117m Sn-labeled (Sn.sup.4+) polyhydroxycarboxylic chelates are also provided. The foregoing pharmaceutical compositions can be used in methods of preparing bone for scintigraphical analysis, for radiopharmaceutical skeletal imaging, treatment of pain resulting from metastatic bone involvement, treatment of primary bone cancer, treatment of cancer resulting from metastatic spread to bone from other primary cancers, treatment of pain resulting from rheumatoid arthritis, treatment of bone/joint disorders and to monitor radioactively the skeletal system.

Srivastava, Suresh C. (Setauket, NY); Meinken, George E. (Middle Island, NY)

2001-01-01

396

Methyl and ethyl ketone analogs of salicylaldehyde isonicotinoyl hydrazone: novel iron chelators with selective antiproliferative action.  

PubMed

Salicylaldehyde isonicotinoyl hydrazone (SIH) is a lipophilic, orally-active tridentate iron chelator providing both effective protection against various types of oxidative stress-induced cellular injury and anticancer action. However, the major limitation of SIH is represented by its labile hydrazone bond that makes it prone to plasma hydrolysis. Recently, nine new SIH analogues derived from aromatic ketones with improved hydrolytic stability were developed. Here we analyzed their antiproliferative potential in MCF-7 breast adenocarcinoma and HL-60 promyelocytic leukemia cell lines. Seven of the tested substances showed greater selectivity than the parent agent SIH towards the latter cancer cell lines compared to non-cancerous H9c2 cardiomyoblast-derived cells. The tested chelators induced a dose-dependent dissipation of the inner mitochondrial membrane potential, an induction of apoptosis as evidenced by Annexin V positivity or significant increases of activities of caspases 3, 7, 8 and 9 and cell cycle arrest. With the exception of nitro group-bearing NHAPI, the studies of iron complexes of the chelators confirmed the crucial role of iron in the mechanism of their antiproliferative action. Finally, all the assayed chelators inhibited the oxidation of ascorbate by iron ions indicating lack of redox activity of the chelator-iron complexes. In conclusion, this study identified several important design criteria for improvement of the antiproliferative selectivity of the aroylhydrazone iron chelators. Several of the novel compounds--in particular the ethylketone-derived HPPI, NHAPI and acetyl-substituted A2,4DHAPI--merit deeper investigation as promising potent and selective anticancer agents. PMID:22521999

Macková, Eliška; Hrušková, Kate?ina; Bendová, Petra; Vávrová, Anna; Jansová, Hana; Hašková, Pavlína; Kova?íková, Petra; Vávrová, Kate?ina; Sim?nek, Tomáš

2012-05-30

397

Synthesis and evaluation of analogues of HYNIC as bifunctional chelators for technetium.  

PubMed

6-Hydrazinonicotinic acid (HYNIC, 1) is a well-established bifunctional technetium-binding ligand often used to synthesise bioconjugates for radiolabelling with Tc-99m. It is capable of efficient capture of technetium at extremely low concentrations, but the structure of the labelled complexes is heterogeneous and incompletely understood. In particular, it is of interest to determine whether, at the no-carrier-added level, it acts in a chelating or non-chelating mode. Here we report two new isomers of HYNIC: 2-hydrazinonicotinic acid (2-HYNIC, 2), which (like 1) is capable of chelation through the mutually ortho hydrazine and pyridine nitrogens and 4-hydrazinonicotinic acid (4-HYNIC, 3), which is not (due to the para-relationship of the hydrazine and pyridine nitrogens). LC-MS shows that the coordination chemistry of 2 with technetium closely parallels that of conventional 1, and no advantages of one over the other in terms of potential labelling efficiency or isomerism were discernable. Both 1 and 2 formed complexes with the loss of 5 protons from the ligand set, whether the co-ligand was tricine or EDDA. Ligand 3, however, failed to complex technetium except at very high ligand concentration: the marked contrast with 1 and 2 suggests that chelation, rather than nonchelating coordination, is a key feature of technetium coordination by HYNIC. Two further new HYNIC analogues, 2-chloro-6-hydrazinonicotinic acid (2-chloro-HYNIC, 4a) and 2,6-dihydrazinonicotinic acid (diHYNIC, 5) were also synthesised. The coordination chemistry of 4a with technetium was broadly parallel to that of 1 and 2 although it was a less efficient chelator, while 5 also behaved as an efficient chelator of technetium, but its coordination chemistry remains poorly defined and requires further investigation before it can sensibly be adopted for (99m)Tc-labelling. The new analogues 4a and 5 present an opportunity to develop trifunctional HYNIC analogues for more complex bioconjugate synthesis. PMID:21350776

Meszaros, Levente K; Dose, Anica; Biagini, Stefano C G; Blower, Philip J

2011-06-21

398

Cytoprotection and iron mobilization in rat hepatocyte cultures by a new synthetic dihydroxamate chelator  

Microsoft Academic Search

The cytoprotection and iron mobilization effect of a new dihydroxamate chelator 1,1 bis [(11-N-hydroxy)-2,5,11-triaza-1,6,10-trioxo dodecanyl] ethane or KD was studied in primary rat hepatocyte cultures exposed to iron-citrate. Lactate dehydrogenase (LDH) release and malondialdehyde (MDA) production were measured as indexes of cytotoxicity. Cell viability was evaluated using the [3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyl tetrazolium bromide] (MTT) reduction test. To demonstrate that this chelator

N Rakba; M. K Nguyen-Van-Duong; L Nicolas; V Guillot; I Morel; N Pasdeloup; P Brissot; G Lescoat

1999-01-01

399

Origin of renal proximal tubular injuries by Fe(III)-nta chelate.  

PubMed

Interaction between apo-transferrin and several iron(III) chelates has been investigated in terms of the capillary electrophoresis method. Based on the results, it has been clarified that (i) a binuclear iron(III) unit with an oxo-bridge is necessary for the facile transfer of an iron atom from the iron(III) chelate to apo-transferrin, and (ii) the renal proximal tubular injuries by Fe(III)-nitrilotriacetate (Fe-nta) should be due to the unique binuclear structure of this complex, which gives a peroxide adduct of the binuclear Fe-nta in the presence of glutathione cycle and oxygen. PMID:17913081

Nishida, Yuzo; Ito, Yuuta; Satoh, Takahiro

2007-01-01

400

NADH:Fe(III)-chelate reductase of maize roots is an active cytochrome b 5 reductase  

Microsoft Academic Search

Microsomal NADH:Fe(III)-chelate reductase (NFR) of maize roots has been purified as a monomeric flavoprotein of 32 kDa with non-covalently bound FAD. In the presence of NADH, NFR efficiently reduced the physiological iron-chelate Fe(III)-citrate (Kcat\\/Km(Fe(III)-citrate)=6.0×106 M?1 s?1) with a sequential reaction mechanism. Purified NFR was totally inhibited by the sulfhydryl reagent PHMB at 10?9 M, and it could use cyt b5

Francesca Sparla; Paolo Bagnaresi; Sandra Scagliarini; Paolo Trost

1997-01-01

401

Chelation as a weathering mechanism--I. Effect of complexing agents on the solubilization of iron from minerals and granodiorite  

Microsoft Academic Search

This work is a continuation of previous studies on the role of chelation as a weathering mechanism. Salicylate and several naturally-occurring chelating agents, in the form of free acids or their alkali salts, extracted Fe from goethite, hematite, magnetite, epidote, augite, biotite and granodiorite. The removal of Fe from granodiorite by salicylate was demonstrable within a matter of minutes and

E. B. Sohalscha; H. Appelt; A. Schatz

1967-01-01

402

Extraction of Micronutrient Metals from Peat-based Media Using Various Chelate-ligand and Iron-source Extractants  

Technology Transfer Automated Retrieval System (TEKTRAN)

Objectives of the study were to determine effects of chelate-ligand (experiment 1) and iron-source (experiment 2) unbuffrered extractant solutions on substrate pH and Cu, Fe, Mn, and Zn extraction from peat-based media. Chelate-ligand extractants consisted of 5 mM solutions of ethylenediaminedisucc...

403

Reactivity and molecular modeling of new solvatochromic mixed-ligand copper(II) chelates of 2-acetylbutyrolactone and dinitrogen bases.  

PubMed

A new series of solvatochromic mononuclear mixed ligand chelates with the general formula: Cu(AcBL)(L)X; where AcBL=2-acetylbutyrolactonate, L=N,N,N',N'-tetramethylethylenediamine (Me4en), N,N,N',N'-tetramethylpropylene diamine (Me4pn), 1,10-phenanthroline (Phen) or 2,2'-bipyridyl (Bipy) and X=ClO4(-), NO3(-) or Br(-) have been synthesized and characterized by the analytical and spectral methods, as well as magnetic and molar conductance measurements. The d-d absorption bands of Me4en-chelates as Nujol mulls or weak donor solvents solutions revealed square-planar, distorted octahedral and/or distorted trigonal bipyramid geometries for the perchlorate, nitrate and bromide chelates, respectively. However, an octahedral structure is identified for chelates in strong donor solvents. Perchlorate chelates show a remarkable color change from violet to green as the Lewis basicity of the donor solvent increases, whereas bromide chelates are mainly affected by the Lewis acidity of solvent. Specific and non-specific interactions of solvent molecules with the chelates were investigated on the basis of unified solvation model. Structural parameters of the free ligands and their Cu(II)-chelates have been calculated on the basis of semiempirical PM3 level and correlated with the experimental data. PMID:25589389

Taha, A; Adly, Omima M I; Shebl, Magdy

2015-04-01

404

Amelioration of Metal-Induced Toxicity in Caenorhabditis elegans: Utility of Chelating Agents in the Bioremediation of Metals  

PubMed Central

The presence of toxic amounts of transition metals in the environment may originate from a range of human activities and natural processes. One method for the removal of toxic levels of metals is through chelation by small molecules. However, chelation is not synonymous with detoxification and may not affect the bioavailability of the metal. To test the bioavailability of chelated metals in vivo, the effects of several metal/chelator combinations were tested in the environmentally relevant organism Caenorhabditis elegans. The effect of metal exposure on nematode growth was used to determine the toxicity of cadmium, copper, nickel, and zinc. The restoration of growth to levels observed in nonexposed nematodes was used to determine the protective effects of the polydentate chelators: acetohydroxamic acid (AHA), cyclam, cysteine, calcium EDTA, desferrioxamine B, 1,2-dimethyl,3-hydroxy,4-pyridinone, and histidine. Cadmium toxicity was removed only by EDTA; copper toxicity was removed by all of the chelators except AHA; nickel toxicity was removed by cyclam, EDTA, and histidine; and zinc toxicity was removed by only EDTA. These results demonstrate the utility of polydentate chelators in the remediation of metal-contaminated systems. They also demonstrate that although the application of a chelator to metal contaminants may be effective, binding alone cannot be used to predict the level of remediation. Remediation depends on a number of factors, including metal complex speciation in the environment. PMID:22641620

Freedman, Jonathan H.

2012-01-01

405

Improvement of Oxidative and Metabolic Parameters by Cellfood Administration in Patients Affected by Neurodegenerative Diseases on Chelation Treatment  

PubMed Central

Objective. This prospective pilot study aimed at evaluating the effects of therapy with antioxidant compounds (Cellfood, and other antioxidants) on patients affected by neurodegenerative diseases (ND), who displayed toxic metal burden and were subjected to chelation treatment with the chelating agent calcium disodium ethylenediaminetetraacetic acid (CaNa2EDTA or EDTA). Methods. Two groups of subjects were studied: (a) 39 patients affected by ND and (b) 11 subjects unaffected by ND (controls). The following blood parameters were analyzed before and after three months' treatment with chelation + Cellfood or chelation + other antioxidants: oxidative status (reactive oxygen species, ROS; total antioxidant capacity, TAC; oxidized LDL, oxLDL; glutathione), homocysteine, vitamin B12, and folate. Results. After 3-months' chelation + Cellfood administration oxLDL decreased, ROS levels were significantly lower, and TAC and glutathione levels were significantly higher than after chelation + other antioxidants treatment, both in ND patients and in controls. Moreover, homocysteine metabolism had also improved in both groups. Conclusions. Chelation + Cellfood treatment was more efficient than chelation + other antioxidants improving oxidative status and homocysteine metabolism significantly in ND patients and controls. Although limited to a small number of cases, this study showed how helpful antioxidant treatment with Cellfood was in improving the subjects' metabolic conditions. PMID:25114898

Fulgenzi, Alessandro; Giuseppe, Rachele De; Bamonti, Fabrizia; Ferrero, Maria Elena

2014-01-01

406

Determination and metabolism of dithiol chelating agents: the zinc chelate of the dimethyl ester of meso-2,3-dimercaptosuccinic acid increase biliary excretion of cadmium and platinum.  

PubMed

meso-2,3-Dimercaptosuccinic acid is an orally active chelating agent useful for the treatment of lead intoxication. Since it is believed to be extracellular in its distribution, analogs have been synthesized in a search for one that will enter the cell and successfully complete for firmly bound intracellular toxic heavy metals such as cadmium and platinum. The biological properties of the zinc chelate of DiMeDMSA, ([Zn(DiMeDMSA)2]2- with tetramethylammonium or sodium as the counterion, have been investigated in the rat. In short-term (hourly) experiments, [Zn(DiMeDMSA)2]2- increased the biliary excretion of cadmium and platinum. In experiments of longer duration (days), severe renal toxicity was noted even in the absence of any exogenously administered cadmium chloride or cis-dichlorodiammineplatinum(II). The zinc content of the kidneys of rats receiving Na2[Zn(DiMeDMSA)2]2- was found to be about 10-fold greater than rats receiving saline or meso-dimethyldimercaptosuccinic acid. Although it appears that the source of the zinc is the injected [Zn(DiMeDMSA)2]2-, at this time it is unknown as to whether the toxicity is due to the Zn chelate molecule, per se, or Zn derived from the molecule after its degradative biotransformation. PMID:8386560

Aposhian, H V; Levine, D J; Rivera, M; Fernando, Q

1993-01-01

407

Coupling fast water exchange to slow molecular tumbling in Gd3+ chelates: why faster is not always better  

PubMed Central

The influence of dynamics on solution state structure is a widely overlooked consideration in chemistry. Variations in Gd3+ chelate hydration with changing coordination geometry and dissociative water exchange kinetics substantially impact the effectiveness (or relaxivity) of mono-hydrated Gd3+ chelates as T1-shortening contrast agents for MRI. Theory shows that relaxivity is highly dependent upon the Gd3+-water proton distance (rGdH) and yet this distance is almost never considered as a variable in assessing the relaxivity of a Gd3+ chelate as a potential contrast agent. The consequence of this omission can be seen when considering the relaxivity of isomeric Gd3+ chelates that exhibit different dissociative water exchange kinetics. The results described herein show that the relaxivity of a chelate with ‘optimal’ dissociative water exchange kinetics is actually lower than that of an isomeric chelate with ‘sub-optimal’ dissociative water exchange. When the rate of molecular tumbling of these chelates is slowed, an approach that has long been understood to increase relaxivity, the observed difference in relaxivity is increased with the more rapidly exchanging (‘optimal’) chelate exhibiting lower relaxivity than the ‘sub-optimally’ exchanging isomer. The difference between the chelates arises from a non-field dependent parameter: either the hydration number (q) or rGdH. For solution state Gd3+ chelates, changes in the values of q and rGdH are indistinguishable. These parametric expressions simply describe the hydration state of the chelate – i.e. the number and position of closely associating water molecules. The hydration state (q/rGdH6) of a chelate is intrinsically linked to its dissociative water exchange rate kex and the interrelation of these parameters must be considered when examining the relaxivity of Gd3+ chelates. The data presented herein indicates that the changes in the hydration parameter (q/rGdH6) associated with changing dissociative water exchange kinetics has a profound effect on relaxivity and suggest that achieving the highest relaxivities in monohydrated Gd3+ chelates is more complicated than simply “optimizing” dissociative water exchange kinetics. PMID:23841587

Avedano, Stefano; Botta, Mauro; Haigh, Julian S.; Longo, Dario; Woods, Mark

2013-01-01

408

OPTIMIZING PHOSPHORUS AND ZINC CONCENTRATIONS IN HYDROPONIC CHELATOR-BUFFERED NUTRIENT SOLUTION FOR RUSSET BURBANK POTATO  

Microsoft Academic Search

High rates of phosphorus (P) fertilizer for potato production have potentially negative environmental and nutritional consequences, including antagonistic interactions with micronutrients. Variable P or zinc (Zn) treatments were evaluated in chelator-buffered solutions to identify deficient, sufficient, and excess concentrations for Russet Burbank potato. Visual observations, dry matter, and nutrient concentrations confirmed 0.1 and 2 ?M as deficient, 6 to 54

Steven A. Barben; Bryan G. Hopkins; Von D. Jolley; Bruce L. Webb; Brandt A. Nichols

2010-01-01

409

An Evaluation of the Chelating Agent EDDS for Floriculture Crop Production  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

410

Biodegradable chelating agents for industrial, domestic, and agricultural applications--a review.  

PubMed

Aminopolycarboxylates, like ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA), are chelating agents widely used in several industrial, agricultural, and domestic applications. However, the fact that they are not biodegradable leads to the presence of considerable amounts in aquatic systems, with serious environmental consequences. The replacement of these compounds by biodegradable alternatives has been the object of study in the last three decades. This paper reviews the most relevant studies towards the use of environmentally friendly chelating agents in a large number of applications: oxidative bleaching, detergents and cleaning compositions, scale prevention and reduction, remediation of soils, agriculture, electroplating, waste treatment, and biocides. Nitrilotriacetic acid (NTA), ethylenediaminedisuccinic acid (EDDS), and iminodisuccinic acid (IDS) are the most commonly suggested to replace the nonbiodegradable chelating agents. Depending on the application, the requirements for metal complexation might differ. Metal chelation ability of the most promising compounds [NTA, EDDS, IDS, methylglycinediacetic acid (MGDA), L-glutamic acid N,N-diacetic acid (GLDA), ethylenediamine-N,N'-diglutaric acid (EDDG), ethylenediamine-N,N'-dimalonic acid (EDDM), 3-hydroxy-2,2-iminodisuccinic acid (HIDS), 2-hydroxyethyliminodiacetic acid (HEIDA), pyridine-2,6-dicarboxylic acid (PDA)] with Fe, Mn, Cu, Pb, Cd, Zn, Ca, and Mg was simulated by computer calculations. The advantages or disadvantages of each compound for the most important applications were discussed. PMID:24554295

Pinto, Isabel S S; Neto, Isabel F F; Soares, Helena M V M

2014-10-01

411

Europium chelate labels in time-resolved fluorescence immunoassays and DNA hybridization assays  

Microsoft Academic Search

Like many analytical methodologies, immunoassays and nucleic acid hybridization assays rely on the reaction between an analyte of interest and a specific reagent. The analyte concentration is then deduced by measuring either the amount of analyte-reagent complex formed (product) or the amount of residual reagent. The authors describe the application of fluorescent rare-earth chelates to immunoassay and DNA probing.

Eleftherios P. Diamandis; Theodore K. Christopoulos

1990-01-01

412

Flavonoids function as antioxidants: By scavenging reactive oxygen species or by chelating iron?  

NASA Astrophysics Data System (ADS)

Flavonoids have been reported to exhibit strong antioxidative activity. In the present work, a systematic mechanistic study has been performed on five flavonoids (baicalin, hesperidin, naringin, quercetin and rutin) selected according to their structural characteristics. The experimental results reveal that flavonoids function as antioxidant mainly by chelating iron ions and by scavenging peroxyl radicals whereas their OH radical scavenging effect is much less important.

Wuguo, Deng; Xingwang, Fang; Jilan, Wu

1997-09-01

413

Refolding of Escherichia coli produced membrane protein inclusion bodies immobilised by nickel chelating chromatography  

Microsoft Academic Search

Two distinctly different membrane proteins, which produced inclusion bodies in Escherichia coli, have been refolded to reconstitute properties appropriate to their native counterparts. The method employed utilises nickel chelating chromatography, where the solubilised inclusion bodies bind, refold and elute. Our aims were to release a large pool of membrane protein for functional, mutational and crystallisation screening studies. It is hoped

H Rogl; K Kosemund; W Kühlbrandt; I Collinson

1998-01-01

414

Teratogenic Effects of a Chelating Agent and Their Prevention by Zinc  

Microsoft Academic Search

Ingestion of a chelating agent (ethylenediaminetetraacetic acid) by female rats during pregnancy impaired reproduction and resulted in congenitally malformed young. When ethylenediaminetetraacetic acid was fed from days 6 to 21 of gestation, all of the full-term young had gross congenital malformations. These effects were prevented by simultaneous supplementation with 1000 parts per million of dietary zinc.

Helene Swenerton; Lucille S. Hurley

1971-01-01

415

Spectroscopy, modeling and computation of metal chelate solubility in supercritical CO{sub 2}  

SciTech Connect

The overall objectives of this project were to gain a fundamental understanding of the solubility and phase behavior of metal chelates in supercritical CO{sub 2}. Extraction with CO{sub 2} is an excellent way to remove organic compounds from soils, sludges and aqueous solutions, and recent research has demonstrated that, together with chelating agents, it is a viable way to remove metals, as well. In this project the authors sought to gain fundamental knowledge that is vital to computing phase behavior, and modeling and designing processes using CO{sub 2} to separate organics and metal compounds from DOE mixed wastes. The overall program was a comprehensive one to measure, model and compute the solubility of metal chelate complexes in supercritical CO{sub 2} and CO{sub 2}/cosolvent mixtures. Through a combination of phase behavior measurements, spectroscopy and the development of a new computational technique, the authors have achieved a completely reliable way to model metal chelate solubility in supercritical CO{sub 2} and CO{sub 2}/co-contaminant mixtures. Thus, they can now design and optimize processes to extract metals from solid matrices using supercritical CO{sub 2}, as an alternative to hazardous organic solvents that create their own environmental problems, even while helping in metals decontamination.

J. F. Brennecke; M. A. Stadtherr

1999-12-10

416

Polymeric precursor derived nanocrystalline ZnO thin films using EDTA as chelating agent  

E-print Network

], molecular beam epitaxy [11, 12], chemical vapor deposition [13], and sol­gel process [14-16]. However, thin, such as citric acid, is generally employed as the chelating agent. However, it has been proven that ethylene-depth. Citric acid in Pechini process has been replaced with EDTA as the complexing a

Mohanty, Saraju P.

417

Pressure-Assisted Chelating Extraction as a Teaching Tool in Instrumental Analysis  

ERIC Educational Resources Information Center

A novel instrumental-digestion technique using pressure-assisted chelating extraction (PACE), for undergraduate laboratory is reported. This procedure is used for exposing students to safe sample-preparation techniques, for correlating wet-chemical methods with modern instrumental analysis and comparing the performance of PACE with conventional…

Sadik, Omowunmi A.; Wanekaya, Adam K.; Yevgeny, Gelfand

2004-01-01

418

BEHAVIORAL CONSEQUENCES OF CHELATOR ADMINISTRATION IN ACUTE CADMIUM TOXICITY (JOURNAL VERSION)  

EPA Science Inventory

The conditioned flavor-aversion paradigm was used to assess the toxicity of acutely administered cadmium and the interaction of cadmium with the heavy-metal chelating agents dimercaprol (BAL) and dimercaptosuccinic acid (DMSA). Shortly after consuming saccharin, rats received cad...

419

Effects of Chelator Modifications on 68Ga-Labeled [Tyr3]Octreotide Conjugates  

PubMed Central

Purpose Somatostatin receptors (SSTR) have been reported as promising targets for imaging agents for cancer. Recently, 68Ga-DOTATOC-based PET imaging has been used successfully for diagnosis and management of SSTR-expressing tumors. The purpose of this study was to evaluate the influence of chelator modifications and charge on 68Ga-labeled peptide conjugates. Procedures We have synthesized a series of [Tyr3]octreotide conjugates that consisted of different NOTA-based chelators with two to five carboxylate moieties, and compared our results with 68Ga-DOTATOC in both in vitro and in vivo studies. Results With the exception of 68Ga-1 (three carboxylates), the increased number of carboxylates on the NOTA-based chelators resulted in a reduced binding affinity and internalization. Additionally, the tumor uptake for 68Ga-2 (four carboxylates) and 68Ga-3 (five carboxylates) was reduced compared to that of 68Ga-DOTATOC (three carboxylates) and 68Ga-NO2ATOC (two carboxylates) and 68Ga-1 (three carboxylates) at 2 h p.i. suggesting the presence of an optimal charge for this compound. Conclusions Chelator modifications can lead to the altered pharmacokinetics. These results may impact further design considerations for peptide-based imaging agents. PMID:23529373

Lin, Mai; Welch, Michael J.; Lapi, Suzanne E.

2015-01-01

420

Production of strong, extracellular Cu chelators by marine cyanobacteria in response to Cu stress  

Microsoft Academic Search

Copper speciation in the upper marine water column is dominated b>, strong ligands thought to be of recent biological origin. Cultures of the marine cyanobacteria Synechococcu.? spp., a ubiquitous and important group of phytoplankton highly sensitive to Cu toxicity, were previously shown to produce chelators com- parable in strength to those detected in the water column. Here we shoyw that

James W. Moffett

1996-01-01

421

Synthesis, conjugation, and radiolabeling of a novel bifunctional chelating agent for (225)Ac radioimmunotherapy applications.  

PubMed

225Ac (t(1/2) = 10 days) is an alternative alpha-emitter that has been proposed for radioimmunotherapy (RIT) due to its many favorable properties, such as half-life and mode of decay. The factor limiting use of (225)Ac in RIT is the lack of an acceptably stable chelate for in vivo applications. Herein is described the first reported bifunctional chelate for (225)Ac that has been evaluated for stability for in vivo applications. The detailed synthesis of a bifunctional chelating agent 2-(4-isothiocyanatobenzyl)-1,4,7,10,13, 16-hexaazacyclohexadecane- 1,4,7,10,13,16-hexaacetic acid (HEHA-NCS) is reported. This ligand was conjugated to three monoclonal antibodies, CC49, T101, and BL-3 with chelate-to-protein ratios between 1.4 and 2. The three conjugates were radiolabeled with (225)Ac, and serum stability study of the [(225)Ac]BL-3-HEHA conjugate was performed. PMID:10898572

Chappell, L L; Deal, K A; Dadachova, E; Brechbiel, M W

2000-01-01

422

SPECTROSCOPY, MODELING AND COMPUTATION OF METAL CHELATE SOLUBILITY IN SUPERCRITICAL CO2  

EPA Science Inventory

The objectives of this project are to gain a fundamental understanding of the solubility and stability of metal chelates in supercritical CO2. Extraction with CO2 is a excellent way to remove organic compounds from soils, sludges and aqueous solutions and recent research has demo...

423

Application of immobilized metal ion chelate complexes as pseudocation exchange adsorbents for protein separation.  

PubMed

The interactions of horse muscle myoglobin (MYO), tuna heart cytochrome c (CYT), and hen egg white lysozyme (LYS) with three different immobilized metal ion affinity (IMAC) adsorbents involving the chelated complexes of the hard Lewis metal ions Al3+, Ca2+, Fe3+, and Yb3+ and the borderline Lewis metal ion Cu2+ have been investigated in the presence of low- and high-ionic strength buffers and at two different pH values. In contrast to the selectivity behavior noted with buffers of high ionic strength, with low-ionic strength buffers, these three proteins interact with the hard metal ion IMAC adsorbents in a manner more characteristic of cation exchange behavior, although in contrast to the cation exchange chromatography of these proteins, as the pH value of the elution buffer was increased, the retention also increased. The selectivity differences observed under these conditions appear to be due to the formation of hydrolytic complexes of these immobilized metal ion chelate systems involving a change in the coordination geometry of the im-M(n+)-chelate at higher pH values. The experimental observations have been evaluated in terms of the effective charge on the immobilized metal ion chelate complex and the charge characteristics of the specific proteins. PMID:8555175

Zachariou, M; Hearn, M T

1996-01-01

424

A family of hydroxypyrone ligands designed and synthesized as iron chelators.  

PubMed

The use of chelating agents for iron and aluminum in different clinical applications has found increasing attention in the last thirty years. Desferal, deferiprone and deferasirox, chelating agents nowadays in use, are based on hydroxamic groups, hydroxyl-substituted pyridinones or aromatic ring systems. With the aim of designing new chelators, we synthesized a series of kojic acid derivatives composed by two kojic units joined by linkers variously substituted. The huge advantages of these molecules are that they are easy and cheap to produce. Preliminary works on complex formation equilibria of the first group of ligands with iron and aluminium highlighted extremely good pMe values and gave evidence of the ability to scavenge iron from inside cells. On these bases a second set of bis-kojic ligands, whose linkers between the kojic chelating moieties are differentiated both in terms of type and size, has been designed, synthesized and characterized. The structural characterization of these new ligands is presented, and the protonation and iron(III) complex formation equilibria studied by potentiometry, UV-Visible spectrophotometry, electrospray ionization mass (ESI-MS) and (1)H NMR spectroscopy will be described and discussed. PMID:23859830

Toso, Leonardo; Crisponi, Guido; Nurchi, Valeria M; Crespo-Alonso, Miriam; Lachowicz, Joanna I; Santos, M Amelia; Marques, Sergio M; Niclós-Gutiérrez, Juan; González-Pérez, Josefa M; Domínguez-Martín, Alicia; Choquesillo-Lazarte, Duane; Szewczuk, Zbigniew

2013-10-01

425

Prodrug and covalent linker strategies for the solubilization of dual-action antioxidants/iron chelators.  

PubMed

Water soluble prodrugs of hybrid free radical scavenger/iron chelating molecules, based on 3,5-disubstituted-4-hydroxyphenyl derivatives and 3-hydroxy-2-methyl-4(1H)-pyridinone (deferiprone), have been prepared. Related hybrid molecules containing a covalent poly(ethylene)glycol or an amine linker were also synthesized. PMID:12392736

Bebbington, David; Dawson, Claire E; Gaur, Suneel; Spencer, John

2002-11-18

426

Korean Guideline for Iron Chelation Therapy in Transfusion-Induced Iron Overload  

PubMed Central

Many Korean patients with transfusion-induced iron overload experience serious clinical sequelae, including organ damage, and require lifelong chelation therapy. However, due to a lack of compliance and/or unavailability of an appropriate chelator, most patients have not been treated effectively. Deferasirox (DFX), a once-daily oral iron chelator for both adult and pediatric patients with transfusion-induced iron overload, is now available in Korea. The effectiveness of deferasirox in reducing or maintaining body iron has been demonstrated in many studies of patients with a variety of transfusion-induced anemias such as myelodysplastic syndromes, aplastic anemia, and other chronic anemias. The recommended initial daily dose of DFX is 20 mg/kg body weight, taken on an empty stomach at least 30 min before food and serum ferritin levels should be maintained below 1000 ng/mL. To optimize the management of transfusion-induced iron overload, the Korean Society of Hematology Aplastic Anemia Working Party (KSHAAWP) reviewed the general consensus on iron overload and the Korean data on the clinical benefits of iron chelation therapy, and developed a Korean guideline for the treatment of iron overload. PMID:24265517

Jang, Jun Ho; Lee, Je-Hwan; Yoon, Sung-Soo; Jo, Deog-Yeon; Kim, Hyeoung-Joon; Chung, Jooseop

2013-01-01

427

Chelation and permeation of heavy metals using affinity membranes from cellulose acetate–chitosan blends  

Microsoft Academic Search

Affinity membranes have attracted the attention of membrane researchers especially in the field of wastewater treatment specifically in removing heavy metals by chelation from aqueous solutions. In the present work, several membranes are made from either cellulose di-acetate (CA) or CA together with chitosan (CS) solutions, the CS prepared in our lab from shrimp shells or from readymade shrimp or

M. M. Naim; H. E. M. Abdel Razek

2012-01-01

428

Luminescence energy transfer using a terbium chelate: Improvements on fluorescence energy transfer  

Microsoft Academic Search

The authors extend the technique of fluorescence resonance energy transfer (FRET) by introducing a luminescent terbium chelate as a donor and an organic dye, tetramethylrhodamine, as an acceptor. The results are consistent with a Foerster theory of energy transfer, provided the appropriate parameters are used. The use of lanthanide donors in general, and this pair in particular, has many advantages

P. R. Selvin; J. E. Hearst

1994-01-01

429

Relative efficacy of chelating agents on excretion and tissue distribution of manganese in mice.  

PubMed

The effect of repeated parenteral administration of a number of structurally diverse chelating agents on the excretion and tissue distribution of manganese was assessed in mice following 4 weeks of manganese exposure. Males Swiss mice received s.c. injections of manganese(II) chloride tetrahydrate (8.9 mg Mn kg-1 body wt.) for 4 weeks (5 days per week). After the end of this exposure period, cyclohexanediaminetetraacetic acid (CDTA), ethyleneglycol-bis-(beta-aminoethylether)-N,N-tetraacetic acid (EGTA), N-(2-hydroxyethyl)ethylenediamine triacetic acid (HEDTA), isonicotinyl hydrazine (INH), L-dopa, sodium 4.5-dihydroxy-1.3-benzenedisulphonate (Tiron), p-aminosalicylic acid (PAS) or 0.9% saline (control group) were given i.p. for five consecutive days. The doses of the chelators were approximately equal to one-eighth of their respective LD50 values. Urine and faeces were daily collected for 5 days. Twenty-four hours after the final chelator injection, mice were killed and manganese concentrations were determined in various tissues. Although CDTA, EGTA and HEDTA significantly enhanced the elimination of manganese into urine, none of the chelators increased faecal excretion. Tissue concentrations of manganese were significantly reduced only by CDTA. According to these results, among the compounds tested only CDTA would mobilize effectively manganese in manganese-loaded mice. PMID:7594197

Sánchez, D J; Gómez, M; Domingo, J L; Llobet, J M; Corbella, J

1995-01-01

430

Pyrolysed N{sub 4}-chelates: Novel electrocatalysts for chemical and biosensors  

SciTech Connect

During the last few years the use of different types of N{sub 4}-metal chelates (especially phtalocyanines and phorphyrins) for electroanalytical and biosensor applications has been attracting increasing attention. Electroanalytical application of such catalysts is generally based on their use as electrode modifiers. The use of N{sub 4}-metal chelates offers several advantages: they show high catalytic activity combined with some analyte selectivity; they are suitable for forming thin layers over an inert electrode; they demonstrate compatibility with enzymes and different immobilization reagents; the electrode modification procedures can be arranged as a step in the sensor micromanufacturing procedure. Oxygen reduction as well as redox properties of numerous organic compounds have been studied on electrodes modified with N{sub 4}-metal chelates. Some of the N{sub 4}-metal chelates have been employed as catalysts for oxygen electroreduction and the electrochemical oxidation of hydrogen peroxide. During the work described, catalysts were prepared by deposition of CoTMPP or H{sub 2} TMPP on non-carbon dispersed carrier, followed by the pyrolysis of the compound and by removal of the carrier. Both pyrolysis products possess high electrocatalytic activity for oxygen reduction and hydrogen peroxide reduction and oxidation.

Atanasov, P.; Wilkins, E. [Univ. of New Mexico, Albuquerque, NM (United States); Gamburzev, S. [Texas A& M Univ., College Station, TX (United States)] [and others

1996-12-31

431

Growth and Decay: An Experiment Demonstrating Radioactivity Relationships and Chelate Solvent Extraction Separations.  

ERIC Educational Resources Information Center

The separation of lead and bismuth by chelate solvent extraction is of interest because of the simplicity which the use of radiotracers allows in its demonstration. Theoretical background information, procedures, materials needed, and typical results are provided for an experiment involving the extraction. (JN)

Downey, D. M.; And Others

1984-01-01

432

Copper chelation selectively kills colon cancer cells through redox cycling and generation of reactive oxygen species  

PubMed Central

Background Metals including iron, copper and zinc are essential for physiological processes yet can be toxic at high concentrations. However the role of these metals in the progression of cancer is not well defined. Here we study the anti-tumor activity of the metal chelator, TPEN, and define its mechanism of action. Methods Multiple approaches were employed, including cell viability, cell cycle analysis, multiple measurements of apoptosis, and mitochondrial function. In addition we measured cellular metal contents and employed EPR to record redox cycling of TPEN–metal complexes. Mouse xenografts were also performed to test the efficacy of TPEN in vivo. Results We show that metal chelation using TPEN (5?M) selectively induces cell death in HCT116 colon cancer cells without affecting the viability of non-cancerous colon or intestinal cells. Cell death was associated with increased levels of reactive oxygen species (ROS) and was inhibited by antioxidants and by prior chelation of copper. Interestingly, HCT116 cells accumulate copper to 7-folds higher levels than normal colon cells, and the TPEN-copper complex engages in redox cycling to generate hydroxyl radicals. Consistently, TPEN exhibits robust anti-tumor activity in vivo in colon cancer mouse xenografts. Conclusion Our data show that TPEN induces cell death by chelating copper to produce TPEN-copper complexes that engage in redox cycling to selectively eliminate colon cancer cells. PMID:25047035

2014-01-01

433

Preclinical and clinical development of deferitrin, a novel, orally available iron chelator.  

PubMed

Deferitrin, a novel, orally available iron chelator, is in the early stage of clinical development for the treatment of chronic iron overload due to transfusional therapy. Preclinical pharmacology studies demonstrate iron excretion largely by the fecal route. Initial clinical studies have shown deferitrin to be well absorbed. Further clinical studies are ongoing to determine the efficiency and safety of deferitrin. PMID:16339704

Donovan, Joanne M; Plone, Melissa; Dagher, Rafif; Bree, Mark; Marquis, Judith

2005-01-01

434

662 American Society of Hematology Supportive care and chelation therapy in MDS  

E-print Network

with respect to iron overload. T he myelodysplastic syndromes (MDS) are clonal disorders characterized patients at risk of iron overload (IOL),5 which in turn may lead to cardiac, hepatic and endocrine this disorder.12 While the benefits of reducing iron with chelation therapy (ICT) are well established

Strynadka, Natalie

435

ENHANCEMENT OF THE ELECTROKINETIC REMEDIATION OF SOIL CONTAINMENT WITH U(VI) BY CHELATING AGENTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The various effects of introduction of chelating agents during electrokinetic remediation of clay soil contaminated with uranium (VI) in pilot scale electrokinetic tests are reported. The combination of the DC electric field (0.7~1.8 V/cm) and citric acid (an inexpensive and environmentally benign c...

436

Safety and effectiveness of long-term therapy with the oral iron chelator deferiprone  

Microsoft Academic Search

The identification of a safe, orally active iron chelator is critically important for the prevention of morbidity and early death in patients receiving regular red cell transfu- sions. Based on our findings in a 1-year multicenter, prospective study of the safety and efficacy of deferiprone in pa- tients with thalassemia major, we have extended the treatment period to 4 years.

Alan R. Cohen; Renzo Galanello; Antonio Piga; Vincenzo De Sanctis; Fernando Tricta

2003-01-01

437

Synthesis and radiolabeling of chelator-RNA aptamer bioconjugates with copper-64 for targeted molecular imaging  

PubMed Central

Ribonucleic acid (RNA) aptamers with high affinity and specificity for cancer-specific cell-surface antigens are promising reagents for targeted molecular imaging of cancer using positron emission tomography (PET). For this application, aptamers must be conjugated to chelators capable of coordinating PET-radionuclides (e.g. copper-64, 64Cu) to enable radiolabeling for in vivo imaging of tumors. This study investigates the choice of chelator and radiolabeling parameters such as pH and temperature for the development of 64Cu-labeled RNA-based targeted agents for PET imaging. The characterization and optimization of labeling conditions are described for four chelator-aptamer complexes. Three commercially available bifunctional macrocyclic chelators (1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid mono N-hydroxysuccinimide [DOTA-NHS]; S-2-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid [p-SCN-Bn-NOTA]; and p-SCN-Bn-3,6,9,15-tetraazabicyclo [9.3.1]pentadeca-1(15),11,13-triene-3,6,9-triacetic acid [p-SCN-Bn-PCTA]), as well as the polyamino-macrocyclic diAmSar (3,6,10,13,16,19-hexaazabicyclo[6.6.6] icosane-1,8-diamine) were conjugated to A10–3.2, a RNA aptamer which has been shown to bind specifically to a prostate cancer-specific cell-surface antigen (PSMA). Although a commercial bifunctional version of diAmSar was not available, RNA conjugation with this chelator was achieved in a two-step reaction by the addition of a disuccinimidyl suberate linker. Radiolabeling parameters (e.g. pH, temperature, and time) for each chelator-RNA conjugate were assessed in order to optimize specific activity and RNA stability. Furthermore, the radiolabeled chelator-coupled RNA aptamers were evaluated for binding specificity to their target antigen. In summary, key parameters were established for optimal radiolabeling of RNA aptamers for eventual PET imaging with 64Cu. PMID:21658962

Rockey, William M.; Huang, Ling; Kloepping, Kyle C.; Baumhover, Nicholas J.; Giangrande, Paloma H.; Schultz, Michael K.

2014-01-01

438

An intercomparison of results from ferrous sulphate and photolytic converter techniques for measurements of NO(x) made during the NASA GTE/CITE 1 aircraft program  

NASA Technical Reports Server (NTRS)

Two techniques designed for measurements of NO(x (NO + NO2) were intercompared during aircraft flights made in the spring of 1984 in the middle free troposphere over the eastern Pacific Ocean and southwestern U.S. One NO chemiluminescence instrument was equipped with a ferrous sulphate converter, another with a photolytic converter. The ferrous sulphate-equipped instrument was apparently much less specific for NO2. It registered levels about three times larger than the photolytic converter and gave NO2/NO ratios that were much larger than photochemical calculations would indicate as reasonable. Additionally, the results imply that active NO(x) was only 10-20 percent of the total odd nitrogen in the middle free troposphere.

Ridley, B. A.; Carroll, M. A.; Torres, A. L.; Condon, E. P.; Sachse, G. W.; Hill, G. F.; Gregory, G. L.

1988-01-01

439

Comparison of flame atomic absorption spectrometry (FAAS) and Cerimetric methods for the determination of ferrous sulfate content of some pharmaceutical products.  

PubMed

The iron content of ferrous sulphate syrup and tablet, ferroglobin, and Fefol were determined by both titration with cerium (Cerimetric method) proposed by united state pharmacopeias and flame atomic absorption spectrometry (FAAS). In FAAS both external calibration and standard addition method were used to evaluate the matrix effects. In the determination of iron content of ferrous sulphate tablet and syrup FAAS using external standard give approximately the same results as cerimetric methods of analysis. But in the case of ferroglobin syrup and Fefol capsule the external calibration results had large deviation from cerimetric method of analysis. So flame atomic absorption spectrometric involving standard addition is proposed for the analysis of iron content of these pharmaceutical products. The coefficient of variation for the FAAS determinations were in the range of 0.73-5.85 in one day and 2.39-7.51 between different days. Statistical evaluation showed good correlation between two methods. PMID:18930861

Zahra, Ramezani; Nadere, Rahbar; Azam, Ghanaatian

2008-10-01

440

Characterization of amorphous yttria layers deposited by aqueous solutions of Y-chelate alkoxides complex  

NASA Astrophysics Data System (ADS)

Crack-free amorphous yttria layers were deposited by dip coating in solutions of different Y-chelate alkoxides complex. Three Y-chelate solutions of different concentrations were prepared using yttrium acetate tetrahydrate, yttrium stearic acid as Y source materials. PEG, diethanolamine were used as chelating agents, while ethanol, methanol and tetradecane were used as solvent. Three different combinations of chelating and solvents were used to prepare solutions for Y2O3 dip coating on SUS, electropolished and non-electropolished Hastelloy C-276 substrates. The thickness of the films was varied by changing the number of dipping cycles. At an optimized condition, the substrate surface roughness (rms) value was reduced from ?50 nm to ?1 nm over a 10 × 10 ?m2 area. After Y2O3 deposition, MgO was deposited using ion-beam assisted deposition (IBAD), then LaMnO3 (LMO) was deposited using sputtering and GdBCO was deposited using reactive co-evaporation by deposition and reaction (RCE-DR). Detailed X-ray study indicates that LMO/MgO/Y2O3 and GdBCO/LMO/MgO/Y2O3 stack films have good out-of-plane and in-plane textures with strong c-axis alignment. The critical current (Ic) of GdBCO/LMO/MgO/Y2O3 multilayer structure varied from 190 to 420 A/cm with different solutions, when measured at 77 K. These results demonstrated that amorphous yttria can be easily deposited by dip coating using Y-chelates complex as a diffusion barrier and nucleation layer.

Kim, Young-Soon; Lee, Yu-Ri; Kim, Byeong-Joo; Lee, Jae-Hun; Moon, Seung-Hyun; Lee, Hunju

2015-01-01

441

Chelation technology: a promising green approach for resource management and waste minimization.  

PubMed

Green chemical engineering recognises the concept of developing innovative environmentally benign technologies to protect human health and ecosystems. In order to explore this concept for minimizing industrial waste and for reducing the environmental impact of hazardous chemicals, new greener approaches need to be adopted for the extraction of heavy metals from industrial waste. In this review, a range of conventional processes and new green approaches employed for metal extraction are discussed in brief. Chelation technology, a modern research trend, has shown its potential to develop sustainable technology for metal extraction from various metal-contaminated sites. However, the interaction mechanism of ligands with metals and the ecotoxicological risk associated with the increased bioavailability of heavy metals due to the formation of metal-chelant complexes is still not sufficiently explicated in the literature. Therefore, a need was felt to provide a comprehensive state-of-the-art review of all aspects associated with chelation technology to promote this process as a green chemical engineering approach. This article elucidates the mechanism and thermodynamics associated with metal-ligand complexation in order to have a better understanding of the metal extraction process. The effects of various process parameters on the formation and stability of complexes have been elaborately discussed with respect to optimizing the chelation efficiency. The non-biodegradable attribute of ligands is another important aspect which is currently of concern. Therefore, biotechnological approaches and computational tools have been assessed in this review to illustrate the possibility of ligand degradation, which will help the readers to look for new environmentally safe mobilizing agents. In addition, emerging trends and opportunities in the field of chelation technology have been summarized and the diverse applicability of chelation technology in metal extraction from contaminated sites has also been reviewed. PMID:25476956

Chauhan, Garima; Pant, K K; Nigam, K D P

2015-01-23

442

Efficiency and purity control in the preparation of pure and\\/or aluminum-doped barium ferrites by hydrothermal methods using ferrous ions as reactants  

Microsoft Academic Search

The synthesis of hexagonal barium ferrite (BaFe12O19) was studied under hydrothermal conditions by a method in which a significant amount of ferrous chloride was introduced alongside ferric chloride among the starting materials. Though all of the Fe2+ ions in the starting material were converted to Fe3+ ions in the final product, Fe2+ was confirmed to participate differently from the Fe3+

Ying Liu; Michael G. B. Drew; Jingping Wang; Milin Zhang; Yue Liu

2010-01-01

443

Ferrous iron transport protein B gene ( feoB1) plays an accessory role in magnetosome formation in Magnetospirillum gryphiswaldense strain MSR1  

Microsoft Academic Search

To investigate the role of ferrous iron transport (Feo) systems in magnetosome formation, the gene for protein FeoB (feoB1), encoding 704 amino acids, was cloned from magnetotactic bacterium Magnetospirillum gryphiswaldense strain MSR-1. feoB1 constitutes a putative operon with feoA1, and the interval between the two genes is 36 base pairs. A feoB1-deficient mutant (?feoB1) was constructed, and compared with wild-type

Chengbo Rong; Yijun Huang; Weijia Zhang; Wei Jiang; Ying Li; Jilun Li

2008-01-01

444

Comparison of a Combination Ferrous Fumarate Product and a Polysaccharide Iron complex as Oral Treatments of Iron Deficiency Anemia: A Taiwanese Study  

Microsoft Academic Search

Despite efforts to improve iron supplements for iron deficiency anemia, there is no consensus on products that balance efficacy,\\u000a safety and tolerability, and cost. Ferrous products are effective, but they are associated with more gastrointestinal side\\u000a effects than ferric products. Ferric products tend to have lower absorption. We present results from a 12-week study that\\u000a ran domized 72 people with

Ta-Chih Liu; Shen-Fung Lin; Chao-Sung Chang; Wen-Chi Yang; Tyen-Po Chen

2004-01-01

445

Persulfate oxidation for in situ remediation of TCE. I. Activated by ferrous ion with and without a persulfate–thiosulfate redox couple  

Microsoft Academic Search

The objective of the laboratory study is to examine the conditions under which transition metal ions (e.g., ferrous ion, Fe2+) could activate the persulfate anion (S2O82?) to produce a powerful oxidant known as the sulfate free radical (SO4?) with a standard redox potential of 2.6 V. The SO4? is capable of destroying groundwater contaminants in situ such as trichloroethylene (TCE).

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

2004-01-01

446

Feasibility and optimization study of using cold-forming extrusion process for agglomerating and microencapsulating ferrous fumarate for salt double fortification with iodine and iron.  

PubMed

A microencapsulation-based technology platform has been developed for salt double fortification with iron and iodine, aiming to address two globally prevalent micronutrient deficiencies simultaneously. Specifically, ferrous fumarate was microencapsulated into a form of salt grain-sized premix, and then added into iodised salt. The earlier process involved fluidised-bed agglomeration followed by lipid coating. To improve physico-chemical properties of the iron premix, the use of cold-forming extrusion for agglomerating and microencapsulating ferrous fumarate was investigated and optimized in this study, leading to optimal formulations and operation parameters. Grain flours were suitable for forming an extrudable dough incorporating high percentages of ferrous fumarate. All extruded iron particles, regardless of binders used, were rich in iron and had excellent iron in vitro digestibility. The extruded iron particles formed the basis of the final, microencapsulated iron premixes with desired particle size (300-700?µm), and other physical, chemical, nutritional, and organoleptic properties suitable for salt fortification. PMID:21824067

Li, Yao Olive; Yadava, Divya; Lo, Kit Lan; Diosady, Levente L; Wesley, Annie S

2011-01-01

447

Role of surface reactions in the transpassive dissolution of ferrous alloys in concentrated H 3PO 4  

NASA Astrophysics Data System (ADS)

The transpassive dissolution of a range of ferrous alloys (Fe-12% Cr, Fe-12% Cr-5% Mo, Fe-25% Cr, Fe-25% Cr-10% Mo) in concentrated H 3PO 4 was studied within the frames of an investigation of electropolishing mechanisms. Measurements by the contact electric resistance (CER) technique have demonstrated that in the transpassive region, the resistance of the anodic film first decreases with increasing potential due to enhanced conductivity of that film and then increases at higher potentials, indicating transpassive film growth. The release of soluble Cr(VI) as detected by rotating ring-disc measurements is the higher, the higher the Cr content in the alloy, and further increases upon addition of 10% Mo to the Fe-Cr alloys. Impedance spectra in the transpassive region have been found to include contributions both from the anodic film and a multistep transpassive dissolution reaction at the film/solution interface. The results were interpreted using a generalised model of transpassive dissolution. The kinetic parameters of the process were determined and the influence of alloy composition on their values is discussed in relation to the processes of anodic surface treatment.

Betova, Iva; Bojinov, Martin; Tzvetkoff, Tzvety

2003-12-01

448

Correlation between ferrous ammonium sulfate concentration, sensitivity and stability of Fricke gel dosimeters exposed to clinical X-ray beams  

NASA Astrophysics Data System (ADS)

This work describes the characterization of various Fricke-Agarose-Xylenol gels (FXG) dosimeters using NMR relaxometry and MRI analysis. Using X-rays from a clinical linear accelerator (LINAC), the gels were irradiated in the dose range from 0 Gy to 20 Gy. The photon sensitivity of the FXGs was measured in terms of NMR relaxation rates; its dependence on radiation dose was determined as a function of ferrous ammonium sulfate contents (from 0.5 mM to 5 mM). Furthermore, the stability of the NMR signal was monitored over several days after irradiation. These measurements were aided by Magnetic Resonance Imaging (MRI) scans which allowed three-dimensional (3D) dose mapping. In order to maximize the MRI response, a systematic study was performed to optimize acquisition sequences and parameters. In particular, we analyzed the dependence of MRI signal on the repetition time (TR) and on the inversion time (TI) using inversion recovery sequences. The results are reported and discussed from the point of view of the dosimeter use in clinical radiotherapy. This work highlights that the optimization of additive content inside gel matrix is fundamental for optimizing photon sensitivity of these detectors.

Marrale, Maurizio; Brai, Maria; Gagliardo, Cesare; Gallo, Salvatore; Longo, Anna; Tranchina, Luigi; Abbate, Boris; Collura, Giorgio; Gallias, Kostantinos; Caputo, Vittorio; Lo Casto, Antonio; Midiri, Massimo; D'Errico, Francesco

2014-09-01

449

Relationship between magnetocrystalline anisotropy, including second-order contribution, and initial magnetic permeability for monocrystalline MnZn ferrous ferrite  

NASA Astrophysics Data System (ADS)

For monocrystalline MnZn ferrous ferrite the magnetocrystalline anisotropy constants K1 and K2, the initial permeability ?i, and the saturation magnetization Ms have been measured in considerable detail as functions of temperature T. The effect of K2 has been incorporated in the commonly used expressions describing the dependence on K1 and Ms of ?i due to rotation of magnetization and displacement of domain walls. It is shown that a nonzero K2 can limit considerably the secondary maximum of ?i(T) at the temperature of anisotropy compensation. The results of measurements on monocrystalline Mn0.42Zn0.44Fe2.145O4 are interpreted with the aid of the theoretical expressions obtained for ?i as a function of K1, K2, and Ms. Special attention has been paid to the temperature range around the secondary maximum of ?i(T) at -82 °C and the temperature range around the primary maximum of ?i(T) close to the Curie temperature.

Stoppels, D.

1980-05-01

450

Inhibition of viral replication by nitric oxide and its reversal by ferrous sulfate and tricarboxylic acid cycle metabolites  

PubMed Central

IFN-gamma-induced nitric oxide (NO) in the murine macrophage-derived cell line RAW 264.7 was previously shown to inhibit replication of the poxviruses ectromelia and vaccinia (VV) and HSV-1. In the current study we demonstrate that murine macrophages activated as a consequence of VV infection express inducible nitric oxide synthase. These activated macrophages were resistant to infection with VV and efficiently blocked the replication of VV and HSV-1 in infected bystander cells of epithelial and fibroblast origin. This inhibition was arginine dependent, correlated with nitrite production in cultures, and reversible by the NOS inhibitor N omega-monomethyl-L-arginine. NO- mediated inhibition of VV replication was studied by treatment of virus- infected human 293 cells with the NO donor S-nitroso-N-acetyl- penicillamine. Using a VV-specific DNA probe, antibodies specific for temporally expressed viral proteins, and transmission electron microscopy, we have shown that NO inhibited viral late gene protein synthesis, DNA replication, and virus particle formation, but not expression of the early proteins that were analyzed. Putative enzymatic targets of NO were identified by reversing the NO-mediated inhibition of VV replication in the 293 cells with exogenous ferrous sulfate and L- cysteine. Reversal of inhibition may derive from the capacity of these reagents to protect or regenerate nonheme iron or thiol groups, respectively, which are essential for the catalytic activities of enzymes susceptible to inactivation by NO. PMID:7539042

1995-01-01

451

Melatonin and its metabolites as copper chelating agents and their role in inhibiting oxidative stress: a physicochemical analysis.  

PubMed

The copper sequestering ability of melatonin and its metabolites cyclic 3-hydroxymelatonin (3OHM), N(1) -acetyl-N(2) -formyl-5-methoxykynuramine (AFMK), and N(1) -acetyl-5-methoxykynuramine (AMK) was investigated within the frame of the Density Functional Theory. It was demonstrated that these compounds are capable of chelating copper ions, yielding stable complexes. The most likely chelation sites were identified. Two different mechanisms were modeled, the direct-chelation mechanism (DCM) and the coupled-deprotonation-chelation mechanism (CDCM). It is proposed that, under physiological conditions, CDCM would be the main chelation route for Cu(II). It was found that melatonin and its metabolites fully inhibited the oxidative stress induced by Cu(II)-ascorbate mixtures, via Cu(II) chelation. In the same way, melatonin, AFMK, and 3OHM also prevented the first step of the Haber-Weiss reaction, consequently turning off the ?OH production via the Fenton reaction. Therefore, it is proposed that, in addition to the previously reported free radical scavenging cascade, melatonin is also involved in a concurrent 'chelating cascade', thereby contributing to a reduction in oxidative stress. 3OHM was identified as the most efficient of the studied compounds for that purpose, supporting the important role of this metabolite in the beneficial effects of melatonin against oxidative stress. PMID:25424557

Galano, Annia; Medina, Manuel E; Tan, Dun Xian; Reiter, Russel J

2015-01-01

452

Assessment of the Efficacy of Chelate-Assisted Phytoextraction of Lead by Coffeeweed (Sesbania exaltata Raf.)  

PubMed Central

Lead (Pb), depending upon the reactant surface, pH, redox potential and other factors can bind tightly to the soil with a retention time of many centuries. Soil-metal interactions by sorption, precipitation and complexation processes, and differences between plant species in metal uptake efficiency, transport, and susceptibility make a general prediction of soil metal bioavailability and risks of plant metal toxicity difficult. Moreover, the tight binding characteristic of Pb to soils and plant materials make a significant portion of Pb unavailable for uptake by plants. This experiment was conducted to determine whether the addition of ethylenediaminetetraacetic acid (EDTA), ethylene glycol tetraacetic acid (EGTA), or acetic acid (HAc) can enhance the phytoextraction of Pb by making the Pb soluble and more bioavailable for uptake by coffeeweed (Sesbania exaltata Raf.). Also we wanted to assess the efficacy of chelates in facilitating translocation of the metal into the above-ground biomass of this plant. To test the effect of chelates on Pb solubility, 2 g of Pb-spiked soil (1000 mg Pb/kg dry soil) were added to each 15 mL centrifuge tube. Chelates (EDTA, EGTA, HAc) in a 1:1 ratio with the metal, or distilled deionized water were then added. Samples were shaken on a platform shaker then centrifuged at the end of several time periods. Supernatants were filtered with a 0.45 ?m filter and quantified by inductively cou