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

Science.gov (United States)

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

2013-06-20

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 (δ/λ) of the backbone ethylenediamine ring (E-ring) of the coordinated EDDA

ct-DNA Binding and Antibacterial Activity of Octahedral Titanium (IV Heteroleptic (Benzoylacetone and Hydroxamic Acids Complexes

Directory of Open Access Journals (Sweden)

Raj Kaushal

2016-01-01

Full Text Available Five structurally related titanium (IV heteroleptic complexes, [TiCl2(bzac(L1–4] and [TiCl3(bzac(HL5]; bzac = benzoylacetonate; L1–5 = benzohydroximate (L1, salicylhydroximate (L2, acetohydroximate (L3, hydroxyurea (L4, and N-benzoyl-N-phenyl hydroxylamine (L5, were used for the assessment of their antibacterial activities against ten pathogenic bacterial strains. The titanium (IV complexes (1–5 demonstrated significant level of antibacterial properties as measured using agar well diffusion method. UV-Vis absorption spectroscopic technique was applied, to get a better insight into the nature of binding between titanium (IV complexes with calf thymus DNA (ct-DNA. On the basis of the results of UV-Vis absorption spectroscopy, the interaction between ct-DNA and the titanium (IV complexes is likely to occur through the same mode. Results indicated that titanium (IV complex can bind to calf thymus DNA (ct-DNA via an intercalative mode. The intrinsic binding constant (Kb was calculated by absorption spectra by using Benesi-Hildebrand equation. Further, Gibbs free energy was also calculated for all the complexes.

Peroxy-Titanium Complex-based inks for low temperature compliant anatase thin films.

Science.gov (United States)

Shabanov, N S; Asvarov, A Sh; Chiolerio, A; Rabadanov, K Sh; Isaev, A B; Orudzhev, F F; Makhmudov, S Sh

2017-07-15

Stable highly crystalline titanium dioxide colloids are of paramount importance for the establishment of a solution-processable library of materials that could help in bringing the advantages of digital printing to the world of photocatalysis and solar energy conversion. Nano-sized titanium dioxide in the anatase phase was synthesized by means of hydrothermal methods and treated with hydrogen peroxide to form Peroxy-Titanium Complexes (PTCs). The influence of hydrogen peroxide on the structural, optical and rheological properties of titanium dioxide and its colloidal solutions were assessed and a practical demonstration of a low temperature compliant digitally printed anatase thin film given. Copyright © 2017 Elsevier Inc. All rights reserved.

Chelation in root canal therapy reconsidered.

Science.gov (United States)

Zehnder, Matthias; Schmidlin, Patrick; Sener, Beatrice; Waltimo, Tuomas

2005-11-01

The aim of this study was to assess interactions of EDTA and citric acid (CA) with sodium hypochlorite (NaOCl), the indispensable endodontic irrigant. Other chelators were simultaneously evaluated as possible alternatives: sodium triphosphate (STP), amino tris methylenephosphonic acid (ATMA), and 1- hydroxyethylidene-1, 1-bisphosphonate (HEBP). Available chlorine was titrated in chelator-NaOCl solutions. All chelators other than HEBP and STP caused an almost complete, immediate loss of available chlorine in solution. Atomic absorbtion spectrometry and SEM evaluation of root canal walls of instrumented teeth indicated that NaOCl had no negative effect on calcium-complexing ability of chelators. STP was too weak a complexing agent to warrant further studies. Finally, CA-, EDTA-, and HEBP-NaOCl mixtures were evaluated for their antimicrobial capacity. Again, EDTA and CA negatively interfered with NaOCl, while HEBP did not.

Bowl adamanzanes-bicyclic tetraamines: syntheses and crystal structures of complexes with cobalt(III) and chelating coordinated oxo-anions

DEFF Research Database (Denmark)

Broge, Louise; Søtofte, Inger; Jensen, Kristian

2007-01-01

complex is provided. Four of the seven complexes contain a chelate coordinating oxo-anion ( sulfate, formiate, nitrate, carbonate). Equilibration of these species with the corresponding diaqua complex is generally slow. The rates of equilibration in 5 mol dm(-3) perchloric acid at 25 degrees C have been...

Complexation studies of actinides (U, Pu, Am) with linear polyamino-carboxylate ligands and sidero-chelates

International Nuclear Information System (INIS)

Nguyen, L.V.

2010-01-01

As part of our research endeavour aimed at developing and improving decontamination processes of wastewater containing alpha emitters, physico-chemical complexation studies of actinides (U, Pu, Am) with organic open-chain ligands such as poly-aminocarboxylic acids (H 4 EDTA) and sidero-chelates (di-hydroxamic acids and desferrioxamine B) have been carried out. Gaining a clear understanding of the coordination properties of the targeted actinides is an essential step towards the selection of the most appropriate chelating agents that will exhibit high uptake efficiencies. EXAFS (Extended X-ray Absorption Fine Structure) measurements at the ESRF synchrotron enabled to elucidate the coordination scheme of uranium and plutonium complexes. Solution thermodynamic investigations were intended to provide valuable information about the nature and the stability of the uranium(VI) and americium(III) complexes prevailing at a given pH in solution. The set of stability constants determined from potentiometric and UV-visible spectrophotometric titrations, allowed to predict the speciation of the selected actinides in presence of the aforementioned ligands and to determine the pH range required for achieving 'ultimate' decontamination. (author) [fr

Synthesis and Properties of Chelating N-Heterocyclic Carbene Rhodium(I) Complexes: Synthetic Experiments in Current Organometallic Chemistry

Science.gov (United States)

Mata, Jose A.; Poyatos, Macarena; Mas-Marza, Elena

2011-01-01

The preparation and characterization of two air-stable Rh(I) complexes bearing a chelating N-heterocyclic carbene (NHC) ligand is described. The synthesis involves the preparation of a Ag(I)-NHC complex and its use as carbene transfer agent to a Rh(I) precursor. The so obtained complex can be further reacted with carbon monoxide to give the…

A bis(3-hydroxy-4-pyridinone)-EDTA derivative as a strong chelator for M3+ hard metal ions: complexation ability and selectivity.

Science.gov (United States)

Gama, Sofia; Dron, Paul; Chaves, Silvia; Farkas, Etelka; Santos, M Amélia

2009-08-21

The study of chelating compounds is very important to solve problems related to human metal overload. 3-Hydroxy-3-pyridinones (HP), namely deferiprone, have been clinically used for chelating therapy of Fe and Al over the last decade. A multi-disciplinary search for alternative molecules led us to develop poly-(3-hydroxy-4-pyridinones) to increase metal chelation efficacy. We present herein a complexation study of a new bis-(3-hydroxy-4-pyridinone)-EDTA derivative with a set of M(3+) hard metal ions (M = Fe, Al, Ga), as well as Zn(2+), a biologically relevant metal ion. Thus a systematic aqueous solution equilibrium study was performed using potentiometric and spectroscopic techniques (UV-Vis, NMR methods). These set of results enables the establishment of specific models as well as the determination of thermodynamic stability constants and coordination modes of the metal complexes. The results indicate that this ligand has a higher affinity for chelating to these hard metal ions than deferiprone, and that the coordination occurs mostly through the HP moieties. Furthermore, it was also found that this ligand has a higher selectivity for chelating to M(3+) hard metal ions (M = Fe, Al, Ga) than Zn(2+).

Vibrational spectra of 1-hydroxy- and 1,4-dihydroxyanthraquinones and their magnesium chelate complexes. I. Isotopic effects of OH/OD and 24Mg/26Mg substitutions

International Nuclear Information System (INIS)

Kirszenbaum, Marek

1977-01-01

The vibrational spectra of 1-hydroxy- and 1,4-dihydroxyanthraquinones, their deuterated derivatives and their 24 Mg/ 26 Mg chelate complexes are examined in the spectral region 1700-250cm -1 . The study of deuteroxyanthraquinones allow an assignment of the OH/OD group vibrations and show the multiple coupling of the delta OH vibrations with the vCC and delta CH quinonic vibrations. These results lead to a modification of some spectral assignments of magnesium chelate complexe of 1-OH-AQ. The isotopic 24 Mg/ 26 Mg substitution enables the chelate ring vibrations which depend on the motions of the magnesium atom to be observed. The vC=O and vC-O vibrations frequencies of magnesium chelate complexe [Mg(1,4-O 2 -AQ)]sub(n) show an important difference of the chelate ring electronic state in comparison of those of 1,4-(OH) 2 -AQ. The discussion of the infrared and Raman spectra in the Mg-O vibrations region lead to the conclusion that the configuration of oxygens arround the magnesium is tetrahedral [fr

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

Science.gov (United States)

Raymond, K.; Xu, J.

1999-04-06

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.

Biological activity of Fe(III) aquo-complexes towards ferric chelate reductase (FCR).

Science.gov (United States)

Escudero, Rosa; Gómez-Gallego, Mar; Romano, Santiago; Fernández, Israel; Gutiérrez-Alonso, Ángel; Sierra, Miguel A; López-Rayo, Sandra; Nadal, Paloma; Lucena, Juan J

2012-03-21

In this study we have obtained experimental evidence that confirms the high activity of aquo complexes III and IV towards the enzyme FCR, responsible for the reduction of Fe(III) to Fe(II) in the process of iron acquisition by plants. The in vivo FCR assays in roots of stressed cucumber plants have shown a higher efficiency of the family of complexes III and a striking structure-activity relationship with the nature of the substituent placed in a phenyl group far away from the metal center. The results obtained in this work demonstrate that all the aquo compounds tested interact efficiently with the enzyme FCR and hence constitute a new concept of iron chelates that could be of great use in agronomy.

ChelomEx: Isotope-assisted discovery of metal chelates in complex media using high-resolution LC-MS.

Science.gov (United States)

Baars, Oliver; Morel, François M M; Perlman, David H

2014-11-18

Chelating agents can control the speciation and reactivity of trace metals in biological, environmental, and laboratory-derived media. A large number of trace metals (including Fe, Cu, Zn, Hg, and others) show characteristic isotopic fingerprints that can be exploited for the discovery of known and unknown organic metal complexes and related chelating ligands in very complex sample matrices using high-resolution liquid chromatography mass spectrometry (LC-MS). However, there is currently no free open-source software available for this purpose. We present a novel software tool, ChelomEx, which identifies isotope pattern-matched chromatographic features associated with metal complexes along with free ligands and other related adducts in high-resolution LC-MS data. High sensitivity and exclusion of false positives are achieved by evaluation of the chromatographic coherence of the isotope pattern within chromatographic features, which we demonstrate through the analysis of bacterial culture media. A built-in graphical user interface and compound library aid in identification and efficient evaluation of results. ChelomEx is implemented in MatLab. The source code, binaries for MS Windows and MAC OS X as well as test LC-MS data are available for download at SourceForge ( http://sourceforge.net/projects/chelomex ).

Crystalline hydroxyapatite coatings synthesized under hydrothermal conditions on modified titanium substrates

International Nuclear Information System (INIS)

Suchanek, Katarzyna; Bartkowiak, Amanda; Gdowik, Agnieszka; Perzanowski, Marcin; Kąc, Sławomir; Szaraniec, Barbara; Suchanek, Mateusz; Marszałek, Marta

2015-01-01

Hydroxyapatite coatings were successfully produced on modified titanium substrates via hydrothermal synthesis in a Ca(EDTA) 2− and (NH 4 ) 2 HPO 4 solution. The morphology of modified titanium substrates as well as hydroxyapatite coatings was studied using scanning electron microcopy and phase identification by X-ray diffraction, and Raman and FTIR spectroscopy. The results show that the nucleation and growth of hydroxyapatite needle-like crystals with hexagonal symmetry occurred only on titanium substrates both chemically and thermally treated. No hydroxyapatite phase was detected on only acid etched Ti metal. This finding demonstrates that only a particular titanium surface treatment can effectively induce the apatite nucleation under hydrothermal conditions. - Highlights: • Bioactivation of titanium substrate by chemical and heat treatments • Precipitation of hydroxyapatite on modified titanium plates • Hydrothermal crystallization of hydroxyapatite by chelate decomposition method

Crystalline hydroxyapatite coatings synthesized under hydrothermal conditions on modified titanium substrates

Energy Technology Data Exchange (ETDEWEB)

Suchanek, Katarzyna, E-mail: Katarzyna.Suchanek@ifj.edu.pl [The Henryk Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego Street 152, 31-342 Krakow (Poland); Bartkowiak, Amanda [The Henryk Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego Street 152, 31-342 Krakow (Poland); Gdowik, Agnieszka [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Mickiewicza 30, 30-059 Krakow (Poland); Perzanowski, Marcin [The Henryk Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego Street 152, 31-342 Krakow (Poland); Kąc, Sławomir [Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Mickiewica 30, 30-059 Krakow (Poland); Szaraniec, Barbara [Department of Biomaterials, AGH University of Science and Technology, Mickiewicza 30, 30-059 Krakow (Poland); Suchanek, Mateusz [Department of Chemistry and Physics, University of Agriculture in Krakow, Mickiewicza 21, 31-120 Krakow (Poland); Marszałek, Marta [The Henryk Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego Street 152, 31-342 Krakow (Poland)

2015-06-01

Hydroxyapatite coatings were successfully produced on modified titanium substrates via hydrothermal synthesis in a Ca(EDTA){sup 2−} and (NH{sub 4}){sub 2}HPO{sub 4} solution. The morphology of modified titanium substrates as well as hydroxyapatite coatings was studied using scanning electron microcopy and phase identification by X-ray diffraction, and Raman and FTIR spectroscopy. The results show that the nucleation and growth of hydroxyapatite needle-like crystals with hexagonal symmetry occurred only on titanium substrates both chemically and thermally treated. No hydroxyapatite phase was detected on only acid etched Ti metal. This finding demonstrates that only a particular titanium surface treatment can effectively induce the apatite nucleation under hydrothermal conditions. - Highlights: • Bioactivation of titanium substrate by chemical and heat treatments • Precipitation of hydroxyapatite on modified titanium plates • Hydrothermal crystallization of hydroxyapatite by chelate decomposition method.

Transition Metal Chelator Induces Progesterone Production in Mouse Cumulus-Oocyte Complexes and Corpora Lutea.

Science.gov (United States)

Tian, X; Anthony, K; Diaz, Francisco J

2017-04-01

Progesterone production is upregulated in granulosa cells (cumulus and mural) after the LH surge, but the intra-follicular mechanisms regulating this transition are not completely known. Recent findings show that the transition metal chelator, N,N,N',N'-tetrakis-(2-pyridylmethyl)-ethylenediamine (TPEN), impairs ovarian function. In this study, we provide evidence that chelating transition metals, including zinc, enhances progesterone production. The findings show that TPEN (transition metal chelator) increases abundance of Cyp11a1 and Star messenger RNA (mRNA) between 8- and 20-fold and progesterone production more than 3-fold in cultured cumulus-oocyte complexes (COC). Feeding a zinc-deficient diet for 10 days, but not 3 days, increased Star, Hsd3b, and prostaglandin F2 alpha receptor (Ptgfr) mRNA ~2.5-fold, suggesting that the effect of TPEN is through modulation of zinc availability. Progesterone from cumulus cells promotes oocyte developmental potential. Blocking progesterone production with epostane during maturation reduced subsequent blastocyst formation from 89 % in control to 18 % in epostane-treated complexes, but supplementation with progesterone restored blastocyst developmental potential to 94 %. Feeding a zinc-deficient diet for 5 days before ovulation did not affect the number of CL, STAR protein, or serum progesterone. However, incubating luteal tissue with TPEN increased abundance of Star, Hsd3b, and Ptgfr mRNA 2-3-fold and increased progesterone production 3-fold. TPEN is known to abolish SMAD2/3 signaling in cumulus cells. However, treatment of COC with the SMAD2/3 phosphorylation inhibitor, SB421542, did not by itself induce steroidogenic transcripts but did potentiate EGF-induced Star mRNA expression. Collectively, the results show that depletion of transition metals with TPEN acutely enhances progesterone biosynthesis in COC and luteal tissue.

Alkyne Hydroamination and Trimerization with Titanium Bis(phenolate)pyridine Complexes: Evidence for Low-Valent Titanium Intermediates and Synthesis of an Ethylene Adduct of Titanium(II)

KAUST Repository

Tonks, Ian A.

2013-06-24

A class of titanium precatalysts of the type (ONO)TiX2 (ONO = pyridine-2,6-bis(4,6-di-tert-butylphenolate); X = Bn, NMe2) has been synthesized and crystallographically characterized. The (ONO)TiX2 (X = Bn, NMe2, X2 = NPh) complexes are highly active precatalysts for the hydroamination of internal alkynes with primary arylamines and some alkylamines. A class of titanium imido/ligand adducts, (ONO)Ti(L)(NR) (L = HNMe2, py; R = Ph, tBu), have also been synthesized and characterized and provide structural analogues to intermediates on the purported catalytic cycle. Furthermore, these complexes exhibit unusual redox behavior. (ONO)TiBn2 (1) promotes the cyclotrimerization of electron-rich alkynes, likely via a catalytically active TiII species that is generated in situ from 1. Depending on reaction conditions, these TiII species are proposed to be generated through Ti benzylidene or imido intermediates. A formally TiII complex, (ONO)Ti II(η2-C2H4)(HNMe2) (7), has been prepared and structurally characterized. © 2013 American Chemical Society.

Alkyne Hydroamination and Trimerization with Titanium Bis(phenolate)pyridine Complexes: Evidence for Low-Valent Titanium Intermediates and Synthesis of an Ethylene Adduct of Titanium(II)

KAUST Repository

Tonks, Ian A.; Meier, Josef C.; Bercaw, John E.

2013-01-01

A class of titanium precatalysts of the type (ONO)TiX2 (ONO = pyridine-2,6-bis(4,6-di-tert-butylphenolate); X = Bn, NMe2) has been synthesized and crystallographically characterized. The (ONO)TiX2 (X = Bn, NMe2, X2 = NPh) complexes are highly active precatalysts for the hydroamination of internal alkynes with primary arylamines and some alkylamines. A class of titanium imido/ligand adducts, (ONO)Ti(L)(NR) (L = HNMe2, py; R = Ph, tBu), have also been synthesized and characterized and provide structural analogues to intermediates on the purported catalytic cycle. Furthermore, these complexes exhibit unusual redox behavior. (ONO)TiBn2 (1) promotes the cyclotrimerization of electron-rich alkynes, likely via a catalytically active TiII species that is generated in situ from 1. Depending on reaction conditions, these TiII species are proposed to be generated through Ti benzylidene or imido intermediates. A formally TiII complex, (ONO)Ti II(η2-C2H4)(HNMe2) (7), has been prepared and structurally characterized. © 2013 American Chemical Society.

Synthesis and crystal structures of dinuclear trichloro(tetramethylcyclopentadienyl) titanium complexes

Czech Academy of Sciences Publication Activity Database

Lukešová, Lenka; Gyepes, R.; Varga, V.; Pinkas, Jiří; Horáček, Michal; Kubišta, Jiří; Mach, Karel

2006-01-01

Roč. 71, č. 2 (2006), s. 164-178 ISSN 0010-0765 R&D Projects: GA AV ČR KJB400400602 Institutional research plan: CEZ:AV0Z40400503 Keywords : titanium * dinuclear complexes * half-sandwich titanocene * silicon bridge Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.881, year: 2006

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

International Nuclear Information System (INIS)

Gopalan, A.; Jacobs, H.; Koshti, N.; Stark, P.; Huber, V.; Dasaradhi, L.; Caswell, W.; Smith, P.; Jarvinen, G.

1995-01-01

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

Controlled synthesis of titania using water-soluble titanium complexes: A review

Science.gov (United States)

Truong, Quang Duc; Dien, Luong Xuan; Vo, Dai-Viet N.; Le, Thanh Son

2017-07-01

The development of human society has led to the increase in energy and resources consumption as well as the arising problems of environmental damage and the toxicity to the human health. The development of novel synthesis method which tolerates utilization of toxic solvents and chemicals would fulfill the demand of the society for safer, softer, and environmental friendly technologies. For the past decades, a remarkable progress has been attained in the development of new water-soluble titanium complexes (WSTC) and their use for the synthesis of nanocrystalline titanium dioxide materials by aqueous solution-based approaches. The progress of synthesis of nanocrystalline titanium dioxide using such WSTCs is reviewed in this work. The key structural features responsible for the successfully controlled synthesis of TiO2 are discussed to provide guidelines for the morphology-controlled synthesis. Finally, this review ends with a summary and some perspectives on the challenges as well as new directions in this fascinating research.

Mixed ligand chelates of rare earths in aqueous solution

International Nuclear Information System (INIS)

Lakhani, S.U.; Thakur, G.S.; Sangal, S.P.

1981-01-01

Mixed ligand chelates of the 1:1 trivalent lanthanoids-EDTA, HEDTA and NTA chelates-1, 2-Dihydroxybenzene (Pyrocatechol) have been investigated at 35degC and 0.2 M ionic strength maintained by NaC10 4 . The formation of mixed ligand chelates has been found in all cases. The formation of mixed ligand chelates with EDTA shows the coordination number of lanthanoids to be eight, while the mixed ligand chelates with HEDTA and NTA shows the coordination number to be seven and six respectively. The stability constants of mixed ligand chelates are smaller than the binary complexes. The order of stability constants with respect to primary ligands follows the order NTA>HEDTA>EDTA. With respect to metal ions the stability constants increases with the decrease in ionic radii such as Gd< Er< Yb. (author)

Nitrosothiol Formation and Protection against Fenton Chemistry by Nitric Oxide-induced Dinitrosyliron Complex Formation from Anoxia-initiated Cellular Chelatable Iron Increase*

Science.gov (United States)

Li, Qian; Li, Chuanyu; Mahtani, Harry K.; Du, Jian; Patel, Aashka R.; Lancaster, Jack R.

2014-01-01

Dinitrosyliron complexes (DNIC) have been found in a variety of pathological settings associated with •NO. However, the iron source of cellular DNIC is unknown. Previous studies on this question using prolonged •NO exposure could be misleading due to the movement of intracellular iron among different sources. We here report that brief •NO exposure results in only barely detectable DNIC, but levels increase dramatically after 1–2 h of anoxia. This increase is similar quantitatively and temporally with increases in the chelatable iron, and brief •NO treatment prevents detection of this anoxia-induced increased chelatable iron by deferoxamine. DNIC formation is so rapid that it is limited by the availability of •NO and chelatable iron. We utilize this ability to selectively manipulate cellular chelatable iron levels and provide evidence for two cellular functions of endogenous DNIC formation, protection against anoxia-induced reactive oxygen chemistry from the Fenton reaction and formation by transnitrosation of protein nitrosothiols (RSNO). The levels of RSNO under these high chelatable iron levels are comparable with DNIC levels and suggest that under these conditions, both DNIC and RSNO are the most abundant cellular adducts of •NO. PMID:24891512

Influence of structural and surface properties of whey-derived peptides on zinc-chelating capacity, and in vitro gastric stability and bioaccessibility of the zinc-peptide complexes.

Science.gov (United States)

Udechukwu, M Chinonye; Downey, Brianna; Udenigwe, Chibuike C

2018-02-01

Gastrointestinal stability of zinc-peptide complexes is essential for zinc delivery. As peptide surface charge can influence their metal complex stability, we evaluated the zinc-chelating capacity and stability of zinc complexes of whey protein hydrolysates (WPH), produced with Everlase (WPH-Ever; ζ-potential, -39mV) and papain (WPH-Pap; ζ-potential, -7mV), during simulated digestion. WPH-Ever had lower amount of zinc-binding amino acids but showed higher zinc-chelating capacity than WPH-Pap. This is attributable to the highly anionic surface charge of WPH-Ever for electrostatic interaction with zinc. Release of zinc during peptic digestion was lower for WPH-Ever-zinc, and over 50% of zinc remained bound in both peptide complexes after peptic-pancreatic digestion. Fourier transform infrared spectroscopy suggests the involvement of carboxylate ion, and sidechain carbon-oxygen of aspartate/glutamate and serine/threonine in zinc-peptide complexation. The findings indicate that strong zinc chelation can promote gastric stability and impede intestinal release, for peptides intended for use as dietary zinc carriers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Metal regeneration of iron chelates in nitric oxide scrubbing

Science.gov (United States)

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

1997-08-19

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.

Chelate chase of radiopharmaceuticals reversibly bound to monoclonal antibodies improves dosimetry

International Nuclear Information System (INIS)

Goodwin, D.A.; Smith, S.I.; Meares, C.F.; David, G.S.; McTigue, M.; Finston, R.A.

1986-01-01

One hundred micrograms of monoclonal antibody (MoAb) CHA 255 with a binding constant Kb of 4 x 10 9 was complexed with indium-111 labeled BLEDTA II, GLEDTA IV, benzyl EDTA, and an EDTA conjugate of Fab. The 24-hour tumor and organ distribution in BALB/c mice bearing KHJJ tumors was studied for each compound alone, the antibody complex, and 3 hours following a chelate chase of the antibody complex. Whole-body biological half-life was measured for 7 days with and without a chelate chase for each antibody complex. The 24-hour whole-body counts dropped 20-60% within 3 hours of administering the chelate chase. Blood concentration fell over 89% within 3 hours of administering the chase and there was a decrease in concentration in all organs, except the kidneys, of 10 to 85%. Theoretical equivalent human doses were calculated from the 24-hour organ concentrations, effective half-life, and MIRD 11 S values (absorbed dose per cumulated activity). Liver and spleen were the target organs, with the dose ranging from 0.50 to 3.91 rads per millicurie. The reduction in organ radiation dose varied up to 95% following the chelate chase. Rapid selective renal clearance of chelate labeled radiopharmaceuticals by competitive inhibition (chelate chase) of their reversible binding to monoclonal antibodies, greatly improves the radiation dosimetry of tumor imaging agents. 28 references, 5 figures, 5 tables

Interaction of chelating agents with cadmium in mice and rats

International Nuclear Information System (INIS)

Eybl, V.; Sykora, J.; Koutensky, J.; Caisova, D.; Schwartz, A.; Mertl, F.

1984-01-01

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

Phenolic aminocarboxylic acids - new chelating agents for modifying gallium-67 biodistribution

Energy Technology Data Exchange (ETDEWEB)

Hunt, F.C.; Maddalena, D.J. (Australian Atomic Energy Commission Research Establishment, Lucas Heights)

The chelating agents EDDHA and HBED were synthesised with carboxyl or sulphonyl groups in the phenolic ring to favour urinary excretion on complexing with gallium. Carboxyl EDDMA was administered to tumor-bearing rats, and its concentration in the tumours and other tissues determined by scintigraphic imaging. The chelating agents increase tumour to blood ratios by chelating gallium in vivo.

Nitrosothiol formation and protection against Fenton chemistry by nitric oxide-induced dinitrosyliron complex formation from anoxia-initiated cellular chelatable iron increase.

Science.gov (United States)

Li, Qian; Li, Chuanyu; Mahtani, Harry K; Du, Jian; Patel, Aashka R; Lancaster, Jack R

2014-07-18

Dinitrosyliron complexes (DNIC) have been found in a variety of pathological settings associated with (•)NO. However, the iron source of cellular DNIC is unknown. Previous studies on this question using prolonged (•)NO exposure could be misleading due to the movement of intracellular iron among different sources. We here report that brief (•)NO exposure results in only barely detectable DNIC, but levels increase dramatically after 1-2 h of anoxia. This increase is similar quantitatively and temporally with increases in the chelatable iron, and brief (•)NO treatment prevents detection of this anoxia-induced increased chelatable iron by deferoxamine. DNIC formation is so rapid that it is limited by the availability of (•)NO and chelatable iron. We utilize this ability to selectively manipulate cellular chelatable iron levels and provide evidence for two cellular functions of endogenous DNIC formation, protection against anoxia-induced reactive oxygen chemistry from the Fenton reaction and formation by transnitrosation of protein nitrosothiols (RSNO). The levels of RSNO under these high chelatable iron levels are comparable with DNIC levels and suggest that under these conditions, both DNIC and RSNO are the most abundant cellular adducts of (•)NO. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Chelating ion exchange with macroreticular hydroxamic acid resins

International Nuclear Information System (INIS)

Phillips, R.J.

1980-01-01

The synthesis, reactions, and analytical applications of hydroxamic acids, including chelating resins with this functional group, are reviewed. A procedure for attaching N-phenyl hydroxamic acid groups to Amberlite XAD-4 is described. The extraction of 20 metal ions from 2 M hydrochloric acid by this resin is discussed. Conditions for the quantitative extraction and back-extraction of 9 ions are reported. Results are compared with work on solvent extraction with N-phenylbenzohydroxamic acid. Procedures for attaching N-methyl and N-unsubstituted hydroxamic acid groups to Amberlite XAD-4 are described. The N-phenyl, N-methyl, and N-unsubstituted hydroxamic acid resins are compared with respect to metal-ion complexation. The scope of applications for hydroxamic acid resins is investigated by studying the extraction of 19 metal ions as a function of pH. The resins are especially suitable for the extraction of zirconium(IV), titanium(IV), and uranium(IV) from strongly acidic solution. Aluminum(III) is separated from calcium and phosphate by extraction at pH 4. The use of the resins for the purification of reagents, concentration of trace constituents, and chromatographic separation is demonstrated

Synthesis of a Bis(thiophenolate)pyridine Ligand and Its Titanium, Zirconium, and Tantalum Complexes

KAUST Repository

Lenton, Taylor N.; VanderVelde, David G.; Bercaw, John E.

2012-01-01

-membered chelate with longer metal-sulfur and carbon-sulfur bonds. Solid-state structures of tantalum complexes (SNS)Ta(NMe 2) 3 (5) and (SNS)TaCl(NEt 2) 2 (6) also display pronounced C 2 twisting of the SNS ligand. 1D and 2D NMR experiments show that 5

Moessbauer and EPR studies on iron-dihydroxybenzoic acid and iron-itoic acid chelate complexes

International Nuclear Information System (INIS)

Bagyinka, Cs.; Horvath, L.I.; Keszthelyi, L.

1984-01-01

Low molecular weight iron-dihydroxybenzoic acid and iron-itoic acid complexes were investigated by Moessbauer and EPR spectroscopy. In strong acidic medium the iron is chelated in high spin ferrous form. By varying the pH of the medium a (S=2)Fesup(2+)→(S=5/2)Fesup(3+) transition was found with a midpoint pH value of 4. From the g'-tensor anisotropy it is concluded that the metal atom is coordinated by six oxygen atoms in rhombically distorted octahedral configuration. The biological significance of these structural data is briefly discussed. (author)

Phenolic aminocarboxylic acids - new chelating agents for modifying gallium-67 biodistribution

International Nuclear Information System (INIS)

Hunt, F.C.; Maddalena, D.J.

1982-01-01

The chelating agents EDDHA and HBED were synthesised with carboxyl or sulphonyl groups in the phenolic ring to favour urinary excretion on complexing with gallium. Carboxyl EDDMA was administered to tumor-bearing rats, and its concentration in the tumours and other tissues determined by scintigraphic imaging. The chelating agents increase tumour to blood ratios by chelating gallium in vivo. (U.K.)

Interaction of chelating agents with cadmium in mice and rats.

Science.gov (United States)

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

1984-01-01

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

Evaluation of macrocyclic hydroxyisophthalamide ligands as chelators for zirconium-89.

Science.gov (United States)

Bhatt, Nikunj B; Pandya, Darpan N; Xu, Jide; Tatum, David; Magda, Darren; Wadas, Thaddeus J

2017-01-01

The development of bifunctional chelators (BFCs) for zirconium-89 immuno-PET applications is an area of active research. Herein we report the synthesis and evaluation of octadentate hydroxyisophthalamide ligands (1 and 2) as zirconium-89 chelators. While both radiometal complexes could be prepared quantitatively and with excellent specific activity, preparation of 89Zr-1 required elevated temperature and an increased reaction time. 89Zr-1 was more stable than 89Zr-2 when challenged in vitro by excess DTPA or serum proteins and in vivo during acute biodistribution studies. Differences in radiometal complex stability arise from structural changes between the two ligand systems, and suggest further ligand optimization is necessary to enhance 89Zr chelation.

Evaluation of macrocyclic hydroxyisophthalamide ligands as chelators for zirconium-89.

Directory of Open Access Journals (Sweden)

Nikunj B Bhatt

Full Text Available The development of bifunctional chelators (BFCs for zirconium-89 immuno-PET applications is an area of active research. Herein we report the synthesis and evaluation of octadentate hydroxyisophthalamide ligands (1 and 2 as zirconium-89 chelators. While both radiometal complexes could be prepared quantitatively and with excellent specific activity, preparation of 89Zr-1 required elevated temperature and an increased reaction time. 89Zr-1 was more stable than 89Zr-2 when challenged in vitro by excess DTPA or serum proteins and in vivo during acute biodistribution studies. Differences in radiometal complex stability arise from structural changes between the two ligand systems, and suggest further ligand optimization is necessary to enhance 89Zr chelation.

Chromatographic retention of molybdenum, titanium and uranium complexes for removal of some interferences in inductively-coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Jiang, S.-J.; Palmieri, M.D.; Fritz, J.S.; Houk, R.S.; Iowa State Univ., of Science and Technology, Ames

1987-01-01

Complexes of molybdenum(VI) or titanium(IV) with N-methylfurohydroxamic acid (N-MFHA) are retained on a column packed with polystyrene/divinylbenzene. At the pH values chosen, copper, zinc and cadmium are washed rapidly through the column and are detected by inductively-coupled plasma mass spectrometry without interference from metal oxide ions of titanium or molybdenum. Detection limits are 1 to 2 μg l -1 , and analyte recoveries are essentially 100%. The resin capacity for the titanium and molybdenum complexes is sufficient for several hundred injections, and the complexes can be readily washed from the column. Uranium(VI) also forms a stable complex with N-MFHA, and ionization interference caused by excess of uranium can be avoided by chromatographic removal of the uranium complex. Various other potentially interfering elements with aqueous oxidation states of +4 or higher (e.g. Sn, W, Hf or Zr) could also be separated by this technique. 33 refs.; 4 figs.; 3 tabs

Monochloro non-bridged half-metallocene-type zirconium complexes containing phosphine oxide-(thio)phenolate chelating ligands as efficient ethylene polymerization catalysts.

Science.gov (United States)

Tang, Xiao-Yan; Wang, Yong-Xia; Liu, San-Rong; Liu, Jing-Yu; Li, Yue-Sheng

2013-01-14

A series of novel monochloro half-zirconocene complexes containing phosphine oxide-(thio)phenolate chelating ligands of the type, ClCp'Zr[X-2-R(1)-4-R(2)-6-(Ph(2)P=O)C(6)H(2)](2) (Cp' = C(5)H(5), 2a: X = O, R(1) = Ph, R(2) = H; 2b: X = O, R(1) = F, R(2) = H; 2c: X = O, R(1) = (t)Bu, R(2) = H; 2d: X = O, R(1) = R(2) = (t)Bu; 2e: X = O, R(1) = SiMe(3), R(2) = H; 2f: X = S, R(1) = SiMe(3), R(2) = H; Cp' = C(5)Me(5), 2g: X = O, R(1) = SiMe(3), R(2) = H), have been synthesized in high yields. These complexes were identified by (1)H {(13)C} NMR and elemental analyses. Structures for 2b, 2c and 2f were further confirmed by X-ray crystallography. Structural characterization of these complexes reveals crowded environments around the zirconium. Complexes 2b and 2c adopt six-coordinate, distorted octahedral geometry around the zirconium center, in which the equatorial positions are occupied by three oxygen atoms of two chelating phosphine oxide-bridged phenolate ligands and a chlorine atom. The cyclopentadienyl ring and one oxygen atom of the ligand are coordinated on the axial position. Complex 2f also folds a six-coordinate, distorted octahedral geometry around the Zr center, consisting of a Cp-Zr-O (in P=O) axis [177.16°] and a distorted plane of two sulfur atoms and one oxygen atom of two chelating phosphine oxide-bridged thiophenolate ligands as well as a chlorine atom. When activated by modified methylaluminoxane (MMAO), all the complexes exhibited high activities towards ethylene polymerization at high temperature (75 °C), giving high molecular weight polymers with unimodal molecular weight distribution. The formation of 14-electron, cationic metal alkyl species might come from the Zr-O (in phenol ring) bond cleavage based on the DFT calculations study.

Effect of other metals on iron bioavailability in presence of a selective chelator

International Nuclear Information System (INIS)

Rehman, F.S.

1995-01-01

Iron (III) is generally very easily chelated by a number of chelators in the biological environment, either supplied by food or already present there. One of the these chelator is gallic acid. The stability constants of the complexes formed between gallic acid and other trace metals have been determined by a potentiometric method. The data obtained was computed with the help of computer program B est . The resulted Beta values were compared with already known values of iron gallic acid complexes. (author)

Mean-square displacement of atomic complex in titanium carbonitrides TiCxNy

International Nuclear Information System (INIS)

Khidirov, I.; Sultanova, S.Kh.; Mukhtarova, N.N.; Tokhtashev, B.

2004-01-01

Full text: The atomic mean-square displacement (MSD) is one of important characteristics of solids, and one can use it for determination of a number of other characteristics of substances. In this work the MSD of atomic complex were determined for a number of compositions of the cubic titanium carbonitrides TiC x N y using the neutron powder diffraction data. The error of MSD determination was less than 3 %. When determining intensity of diffraction maximum a correction for the thermal diffusion dispersion (TDD) was included in the neutron diffraction patterns. The contribution of TDD in the intensity of diffraction maxima was found to be less than the experiment error (no more than 1,5 %). Such small value of the TDD correction is explained by refractory of materials. The values of MSD in titanium carbonitrides for a number of compositions, determined by the neutron powder diffraction measurements, are given. It is shown, that the dependence of MSD on the concentration (C+N)/Ti has a complex character. With decrease of the total content of metalloids MSD decreases at first, reaching a minimum about concentration (C+N)/Ti≅0.80, and then increases. MSD consists of dynamic and static distortions, where the static distortions in the compounds with variable composition increase with increasing of deviation from stoichiometry. The above anomaly in the dependence of MSD on the total concentration of metalloids, apparently, point to prevalence of dynamic distortions over static ones and to complex character of concentration dependence of interatomic interactions in the titanium carbonitrides. This work was supported by the Supporting Fund for Fundamental Researches of Uzbekistan Academy of Sciences (Grant No. 6-04)

In vitro and in vivo evaluation of potential aluminum chelators.

Science.gov (United States)

Graff, L; Muller, G; Burnel, D

1995-10-01

The potential for aluminium (Al) chelation by different compounds was determined using 2 in vitro techniques. The formation of stable complexes with Al in an aqueous solution was evaluated using pulse polarography. This technique allowed the influence of temperature and calcium (Ca) to be studied for each compound. Certain compounds (EDDHA, HAES, citric acid and HBED) showed great chelation in the absence of Ca2+ at a temperature of 37 +/- 1 C. An ultrafiltration technique combined with Al determination by atomic emission spectroscopy allowed the efficiency of different substances to complex Al that were previously bound to serum proteins to be estimated. The kinetics of chelation and minimum efficient concentration have been determined for all products studied. EDDHA had chelation potential similar to DFO. The real efficacies of the compounds were studied in vivo to compare the effectiveness of repeated administrations of the best chelating agents (EDDHA, DFO, HAES and tartaric acid) on the distribution and excretion of Al after repeated i.p. administrations to rats. Intraperitoneal EDDHA significantly increased urinary metal (Al, Ca, Cu, Fe and Zn) excretion. These excretions may be correlated to a renal toxic potential property.

Toxicity of copper chelates of azomethines and amino acids for Chlorella pyrenoidosa

Energy Technology Data Exchange (ETDEWEB)

Barashkov, G.K.; Rukhadze, E.G.; Talyzenkova, G.P.

1979-01-01

The authors have attempted to assess the toxicity of copper-containing compounds from the point of view of their interrelationship with the structural characteristics of the chelate compound and the structure of the ligand. The copper chelates of the azomethines tested may be provisionally divided into three types: A - complexes with N-alkly-azomethines; B - complexes with N-aryl-azomethines; C - binuclear complexes. Consideration was also given to chelates with aromatic and heterocyclic amino acids and to heteroligand chelates in which the copper atom coordinates azomethine and an amino acid simultaneously. Toxicity was determined by the method previously described and expressed as a critical concentration (C/sub cr/, mg Cu/liter) and in relative toxicity units (T/sub c/). The compounds investigated were obtained from the interaction between a bidentant ligand of an azomethine or anamino acid and copper acetate in a water-alcohol medium at pH 6-8. Since they are not very soluble in water, true solutions were obtained by using dimethyl sulfoxide.

Uranium (VI) complexing by macrocyclic or chelating ligands in aqueous solutions stability, formation kinetics, polarographic properties

International Nuclear Information System (INIS)

Brighli, M.

1984-07-01

Stability of chelates (with EDTA,N,N ethylenediamine diacetic acid EDDA nitrilotriacetic acid NTA and iminodiacetic acid) of UO 2 2+ and UO 4 species of uranium VI is studied in aqueous solution (NaClO 4 3M at 25 deg celcius). Structure in solution are proposed and discussed for mononuclear species. Only complexing kinetics (formation and acid hydrolysis) of UO 4 with EDDA and NTA are studied by spectrophotometry (other reactions are too fast). Besides UO 2 2+ complexes are formed with crown ethers I5C5 and I8C6 in aqueous solution (TEA ClO 4 M/10 at 25 deg celcius. Complexes are probably stabilized by solvation. Results are confirmed by voltametry and reduction mechanisms of UO 2 2+ and its complexes on mercury drop are proposed. 143 refs [fr

New method for studying the efficiency of chelating agents of the polyamine acid series for internal decontamination

International Nuclear Information System (INIS)

Lafuma, J.; Nenot, J.C.; Morin, M.

1968-01-01

We followed the biological fate of a complex formed on one side with either a rare earth (cerium-144) or a transuranium element (plutonium-239), and on the other side with a chelating agent of the polyamino acid series (EDTA, BAETA, DTPA, TTHA). This method allowed to study: 1 - the in vivo stability of the various complexes and to compare them; 2 - the stability of the complexes as a function of the isotope - chelating agent weight relationships; 3 - the metabolism of the chelating agents resulting in stable complexes, i. e. DTPA and TTHA mainly. This simple method brought out the higher efficiency, of DTPA in chelating rare earths and plutonium and for therapeutic purposes. (authors) [fr

Selectivity in extraction of copper and indium with chelate extractants

International Nuclear Information System (INIS)

Zivkovic, D.

2003-01-01

Simultaneous extraction of copper and indium with chelate extractants (LIX84 and D2E11PA) was described. Stechiometry of metal-organic complexes examined using the method of equimolar ratios resulted in CuR 2 and InR 3 forms of hydrophobic extracting species. A linear correlation was obtained between logarithm of distribution coefficients and chelate agents and pH, respectively. Selectivity is generally higher with higher concentrations of chelate agents in the organic phase, and is decreased with increase of concentration of hydrogen ions in feeding phase. (Original)

Mathematical modeling of the effects of aerobic and anaerobic chelate biodegradation on actinide speciation

International Nuclear Information System (INIS)

Banaszak, J.E.; VanBriesen, J.; Rittmann, B.E.; Reed, D.T.

1998-01-01

Biodegradation of natural and anthropogenic chelating agents directly and indirectly affects the speciation, and, hence, the mobility of actinides in subsurface environments. We combined mathematical modeling with laboratory experimentation to investigate the effects of aerobic and anaerobic chelate biodegradation on actinide [Np(IV/V), Pu(IV)] speciation. Under aerobic conditions, nitrilotriacetic acid (NTA) biodegradation rates were strongly influenced by the actinide concentration. Actinide-chelate complexation reduced the relative abundance of available growth substrate in solution and actinide species present or released during chelate degradation were toxic to the organisms. Aerobic bio-utilization of the chelates as electron-donor substrates directly affected actinide speciation by releasing the radionuclides from complexed form into solution, where their fate was controlled by inorganic ligands in the system. Actinide speciation was also indirectly affected by pH changes caused by organic biodegradation. The two concurrent processes of organic biodegradation and actinide aqueous chemistry were accurately linked and described using CCBATCH, a computer model developed at Northwestern University to investigate the dynamics of coupled biological and chemical reactions in mixed waste subsurface environments. CCBATCH was then used to simulate the fate of Np during anaerobic citrate biodegradation. The modeling studies suggested that, under some conditions, chelate degradation can increase Np(IV) solubility due to carbonate complexation in closed aqueous systems

Mathematical modelling of the effects of aerobic and anaerobic chelate biodegradation on actinide speciation

International Nuclear Information System (INIS)

Banaszak, J.E.; VanBriesen, J.M.; Rittmann, B.E.; Reed, D.T.

1998-01-01

Biodegradation of natural and anthropogenic chelating agents directly and indirectly affects the speciation, and hence, the mobility of actinides in subsurface environments. We combined mathematical modelling with laboratory experimentation to investigate the effects of aerobic and anaerobic chelate biodegradation on actinide [Np(IV/V), Pu(IV)] speciation. Under aerobic conditions, nitrilotriacetic acid (NTA) biodegradation rates were strongly influenced by the actinide concentration. Actinide-chelate complexation reduced the relative abundance of available growth substrate in solution and actinide species present or released during chelate degradation were toxic to the organisms. Aerobic bioutilization of the chelates as electron-donor substrates directly affected actinide speciation by releasing the radionuclides from complexed form into solution, where their fate was controlled by inorganic ligands in the system. Actinide speciation was also indirectly affected by pH changes caused by organic biodegradation. The two concurrent processes of organic biodegradation and actinide aqueous chemistry were accurately linked and described using CCBATCH, a computer model developed at Northwestern University to investigate the dynamics of coupled biological and chemical reactions in mixed waste subsurface environments. CCBATCH was then used to simulate the fate of Np during anaerobic citrate biodegradation. The modelling studies suggested that, under some conditions, chelate degradation can increase Np(IV) solubility due to carbonate complexation in closed aqueous systems. (orig.)

Targeted Catalytic Inactivation of Angiotensin Converting Enzyme by Lisinopril-Coupled Transition Metal Chelates

Science.gov (United States)

Joyner, Jeff C.; Hocharoen, Lalintip; Cowan, J. A.

2012-01-01

A series of compounds that target reactive transition metal chelates to somatic Angiotensin Converting Enzyme (sACE-1) have been synthesized. Half maximal inhibitory concentrations (IC50) and rate constants for both inactivation and cleavage of full length sACE-1 have been determined and evaluated in terms of metal-chelate size, charge, reduction potential, coordination unsaturation, and coreactant selectivity. Ethylenediamine-tetraacetic acid (EDTA), nitrilotriacetic acid (NTA), 1,4,7,10-tetraazacyclo-dodecane-1,4,7,10-tetraacetic acid (DOTA), and tripeptide GGH were linked to the lysine sidechain of lisinopril by EDC/NHS coupling. The resulting amide-linked chelate-lisinopril (EDTA-lisinopril, NTA-lisinopril, DOTA-lisinopril, and GGH-lisinopril) conjugates were used to form coordination complexes with iron, cobalt, nickel and copper, such that lisinopril could mediate localization of the reactive metal chelates to sACE-1. ACE activity was assayed by monitoring cleavage of the fluorogenic substrate Mca-RPPGFSAFK(Dnp)-OH, a derivative of bradykinin, following pre-incubation with metal-chelate-lisinopril compounds. Concentration-dependent inhibition of sACE-1 by metal-chelate-lisinopril complexes revealed IC50 values ranging from 44 nM to 4,500 nM for Ni-NTA-lisinopril and Ni-DOTA-lisinopril, respectively, versus 1.9 nM for lisinopril. Stronger inhibition was correlated with smaller size and lower negative charge of the attached metal chelates. Time-dependent inactivation of sACE-1 by metal-chelate-lisinopril complexes revealed a remarkable range of catalytic activities, with second order rate constants as high as 150,000 M−1min−1 (Cu-GGH-lisinopril), while catalyst-mediated cleavage of sACE-1 typically occurred at much lower rates, indicating that inactivation arose primary from sidechain modification. Optimal inactivation of sACE-1 was observed when the reduction potential for the metal center was poised near 1000 mV, reflecting the difficulty of protein

Targeted catalytic inactivation of angiotensin converting enzyme by lisinopril-coupled transition-metal chelates.

Science.gov (United States)

Joyner, Jeff C; Hocharoen, Lalintip; Cowan, J A

2012-02-22

A series of compounds that target reactive transition-metal chelates to somatic angiotensin converting enzyme (sACE-1) have been synthesized. Half-maximal inhibitory concentrations (IC(50)) and rate constants for both inactivation and cleavage of full-length sACE-1 have been determined and evaluated in terms of metal chelate size, charge, reduction potential, coordination unsaturation, and coreactant selectivity. Ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), and tripeptide GGH were linked to the lysine side chain of lisinopril by 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide hydrochloride/N-hydroxysuccinimide coupling. The resulting amide-linked chelate-lisinopril (EDTA-lisinopril, NTA-lisinopril, DOTA-lisinopril, and GGH-lisinopril) conjugates were used to form coordination complexes with iron, cobalt, nickel, and copper, such that lisinopril could mediate localization of the reactive metal chelates to sACE-1. ACE activity was assayed by monitoring cleavage of the fluorogenic substrate Mca-RPPGFSAFK(Dnp)-OH, a derivative of bradykinin, following preincubation with metal chelate-lisinopril compounds. Concentration-dependent inhibition of sACE-1 by metal chelate-lisinopril complexes revealed IC(50) values ranging from 44 to 4500 nM for Ni-NTA-lisinopril and Ni-DOTA-lisinopril, respectively, versus 1.9 nM for lisinopril. Stronger inhibition was correlated with smaller size and lower negative charge of the attached metal chelates. Time-dependent inactivation of sACE-1 by metal chelate-lisinopril complexes revealed a remarkable range of catalytic activities, with second-order rate constants as high as 150,000 M(-1) min(-1) (Cu-GGH-lisinopril), while catalyst-mediated cleavage of sACE-1 typically occurred at much lower rates, indicating that inactivation arose primarily from side chain modification. Optimal inactivation of sACE-1 was observed when the reduction potential for the

The coordination and atom transfer chemistry of titanium porphyrin complexes

Energy Technology Data Exchange (ETDEWEB)

Hays, James Allen [Iowa State Univ., Ames, IA (United States)

1993-11-05

Preparation, characterization, and reactivity of (η²- alkyne)(meso-tetratolylpoprphrinato)titanium(II) complexes are described, along with inetermetal oxygen atom transfer reactions involving Ti(IV) and Ti(III) porphyrin complexes. The η²- alkyne complexes are prepared by reaction of (TTP)TiCl₂ with LiAlH₄ in presence of alkyne. Structure of (OEP)Ti(η²-Ph-C≡C-Ph) (OEP=octaethylporphryin) was determined by XRD. The compounds undergo simple substitution to displace the alkyne and produce doubly substituted complexes. Structure of (TTP)Ti(4-picoline)₂ was also determined by XRD. Reaction of (TTP)Ti=O with (OEP)Ti-Cl yields intermetal O/Cl exchange, which is a one-electron redox process mediated by O atom transfer. Also a zero-electron redox process mediated by atom transfer is observed when (TTP)TiCl₂ is reacted with (OEP)Ti=O.

Bifunctional chelating agent for the design and development of site specific radiopharmaceuticals and biomolecule conjugation strategy

Science.gov (United States)

Katti, Kattesh V.; Prabhu, Kandikere R.; Gali, Hariprasad; Pillarsetty, Nagavara Kishore; Volkert, Wynn A.

2003-10-21

There is provided a method of labeling a biomolecule with a transition metal or radiometal in a site specific manner to produce a diagnostic or therapeutic pharmaceutical compound by synthesizing a P.sub.2 N.sub.2 -bifunctional chelating agent intermediate, complexing the intermediate with a radio metal or a transition metal, and covalently linking the resulting metal-complexed bifunctional chelating agent with a biomolecule in a site specific manner. Also provided is a method of synthesizing the --PR.sub.2 containing biomolecules by synthesizing a P.sub.2 N.sub.2 -bifunctional chelating agent intermediate, complexing the intermediate with a radiometal or a transition metal, and covalently linking the resulting radio metal-complexed bifunctional chelating agent with a biomolecule in a site specific manner. There is provided a therapeutic or diagnostic agent comprising a --PR.sub.2 containing biomolecule.

Studies on chelation properties of ampicillin with trace metal ions and comparison with penicillin complexes

International Nuclear Information System (INIS)

Rehmani, F.S.; Hameed, W.

2003-01-01

The penicillin is highly effective antibiotic with extremely wide margin of safety. Ampicillin e is the penicillin group of antibiotic in which side chain is phenyl group i.e. D-amino benzyl penicillin. The side chain determines many of anti bacterial and pharmacological characteristics. They inhibit the protein synthesis in bacterial cell wall. The chelating properties of the antibiotic may be used in the metal transport across the membrane. The present investigations are helpful in drug metabolism and their effects on minerals contents of the body. The complex formation between Ampicillin and penicillin with trace metal ions such as Fe(III), Cr(III), Al(III), Mn(II), Ni(II), Co(II), Ca(II), Mg(II), Cu(III) and Zn(II) were studied by potentiometric titrations and spectrophotometric methods. Stoichiometry of these complexes were studied by mole ratio method. It was found that the Fe(III) and Cu(II) ions form most stable complexes near physiological pH and the mole ratio was 1:1. (author)

Bright electroluminescence from a chelate phosphine oxide Eu{sup III} complex with high thermal performance

Energy Technology Data Exchange (ETDEWEB)

Xu Hui [School of Chemistry and Materials, Heilongjiang University, 74 Xuefu Road, Nangang District, Harbin 150080, Heilongjiang Province (China); Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 66 Xinmofan Road, Nanjing 21003, Jiangsu Province (China); Yin Kun; Wang Lianhui [Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, 66 Xinmofan Road, Nanjing 21003, Jiangsu Province (China); Huang Wei [Institute of Advanced Materials (IAM), Fudan University, 220 Handan Road, Shanghai 200433 (China)], E-mail: wei-huang@njupt.edu.cn

2008-10-01

The chelate phosphine oxide ligand 1,8-bis(diphenylphosphino)naphthalene oxide (NaPO) was used to prepare complex 1 tris(2-thenoyltrifluoroacetonate)(1,8-bis(diphenylphosphino)naphthalene oxide)europium(III). The rigid structure of NaPO makes 1 have more compact structure resulting in a temperature of glass transition as high as 147 deg. C, which is the highest in luminescent Eu{sup III} complexes, and a higher decomposition temperature of 349 deg. C. The improvement of carrier transfer ability of NaPO was proved by Gaussian simulation. The multi-layered electroluminescent device based on 1 had a low turn-on voltage of 6.0 V, the maximum brightness of 601 cd m{sup -2} at 21.5 V and 481.4 mA cm{sup -2}, and the excellent voltage-independent spectral stability. These properties demonstrated NaPO cannot only be favorable to form the rigid and compact complex structure, and increase the thermal and morphological stability of the complex, but also reduce the formation of the exciplex.

Bowl adamanzanes--bicyclic tetraamines: syntheses and crystal structures of complexes with cobalt(III) and chelating coordinated oxo-anions.

Science.gov (United States)

Broge, Louise; Søtofte, Inger; Jensen, Kristian; Jensen, Nicolai; Pretzmann, Ulla; Springborg, Johan

2007-09-14

Seven cobalt(III) complexes of the macrobicyclic tetraamine ligand [2(4).3(1)]adamanzane ([2(4).3(1)]adz) are reported along with the crystal structure of six of these complexes. The solid state and solution structures are discussed, and a detailed assignment of the NMR spectra of the sulfato complex is provided. Four of the seven complexes contain a chelate coordinating oxo-anion (sulfate, formiate, nitrate, carbonate). Equilibration of these species with the corresponding diaqua complex is generally slow. The rates of equilibration in 5 mol dm(-3) perchloric acid at 25 degrees C have been measured, yielding half lives of 20 min, 10 min and 3 h for the sulfato, formiato and carbonato species respectively. The corresponding reaction for the nitrato complex occurs with a half life of less than 3 min. The concentration acid dissociation constant for the Co([2(4).3(1)]adz)(HCO(3))(2+) ion has been measured to K(a) = 0.33 mol dm(-3) [25 degrees C, I = 2 mol dm(-3)] and K(a) = 0.15 mol dm(-3) [25 degrees C, I = 5 mol dm(-3)]. The propensity for coordination of sulfate was found to be large enough for a quantitative conversion of the carbonato complex to the sulfato complex to occur in 3 mol dm(-3) triflic acid containing a small sulfate contamination. On this basis the decarboxylation in 5 mol dm(-3) triflic acid of the corresponding cobalt(III) carbonato complex of the larger macrobicyclic tetraamine ligand [3(5)]adz was reinvestigated and found to lead to the sulfato complex as well. The difference in exchange rate of the oxo-anion ligands for the cobalt(III) complexes of the two adamanzane ligands is discussed and attributed to fundamental differences in the molecular structure where an inverted configuration of the secondary non-bridged amine groups is seen for the complexes of the larger [3(5)]adz ligand. The high affinity for chelating coordination of oxo-anions for these two cobalt(iii)-adamanzane-moieties is rationalised on basis of the N-Co-N angles. N

Synthesis and characterization of dihexyldithiocarbamate as a chelating agent in extraction of gold(III)

Energy Technology Data Exchange (ETDEWEB)

Fatimah, Soja Siti, E-mail: soja-sf@upi.edu [Departemen Pendidikan Kimia, Universitas Pendidikan Indonesia, Jl. Dr. Setiabudhi No. 229, Bandung 40154 (Indonesia); Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jl. Raya Bandung-Sumedang, Km. 21, Jatinangor (Indonesia); Bahti, Husein H.; Hastiawan, Iwan [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jl. Raya Bandung-Sumedang, Km. 21, Jatinangor (Indonesia); Permanasari, Anna [Departemen Pendidikan Kimia, Universitas Pendidikan Indonesia, Jl. Dr. Setiabudhi No. 229, Bandung 40154 (Indonesia)

2016-02-08

The use of dialkyldithiocarbamates as chelating agents of transition metals have been developing for decades. Many chelating agents have been synthesized and used in the extraction of the metals. Studies on particular aspects of extraction of the metals, such as the effect of increasing hydrophobicity of chelating agents on the effectiveness of the extraction, have been done. However, despite the many studies on the synthesis and applications of this type of chelating agents, interests in the aspect of molecular structure of the synthesized ligands and of their complexes, have been limited. This study aimed at synthesizing and characterizing dihexylthiocarbamate, and using the ligand for the extraction of gold III). Characterization of the ligand and of its metal complex were done by using elemental analysis, DTG, and spectroscopic methods to include NMR, ({sup 1}H, and {sup 13}C), FTIR, and MS-ESI. Data on the synthesis, characterization, and the application of the ligand as a chelating agent are presented.

Synthesis and characterization of dihexyldithiocarbamate as a chelating agent in extraction of gold(III)

Science.gov (United States)

Fatimah, Soja Siti; Bahti, Husein H.; Hastiawan, Iwan; Permanasari, Anna

2016-02-01

The use of dialkyldithiocarbamates as chelating agents of transition metals have been developing for decades. Many chelating agents have been synthesized and used in the extraction of the metals. Studies on particular aspects of extraction of the metals, such as the effect of increasing hydrophobicity of chelating agents on the effectiveness of the extraction, have been done. However, despite the many studies on the synthesis and applications of this type of chelating agents, interests in the aspect of molecular structure of the synthesized ligands and of their complexes, have been limited. This study aimed at synthesizing and characterizing dihexylthiocarbamate, and using the ligand for the extraction of gold III). Characterization of the ligand and of its metal complex were done by using elemental analysis, DTG, and spectroscopic methods to include NMR, (1H, and 13C), FTIR, and MS-ESI. Data on the synthesis, characterization, and the application of the ligand as a chelating agent are presented.

Iron chelates: a challenge to chemists and Moessbauer spectroscopists

Energy Technology Data Exchange (ETDEWEB)

Homonnay, Z., E-mail: homonnay@chem.elte.hu; Szilagyi, P. A.; Vertes, A. [Eoetvoes Lorand University, Laboratory of Nuclear Chemistry, Institute of Chemistry (Hungary); Kuzmann, E. [Hungarian Academy of Sciences, Department of Nuclear Chemistry, Chemical Research Center (Hungary); Sharma, V. K. [Florida Institute of Technology (United States); Molnar, G.; Bousseksou, A. [CNRS UPR-8241, Laboratoire de Chimie de Coordination (France); Greneche, J.-M. [Universite du Maine, Laboratoire de Physique de l' Etat Condense, CNRS UMR 6087 (France); Brausam, A.; Meier, R.; Eldik, R. van [University of Erlangen-Nuernberg, Institute for Inorganic Chemistry (Germany)

2008-02-15

The speciation of iron in aqueous solutions containing Fe{sup 3+} and selected chelates such as EDTA, EDDA, CDTA and HEDTA has been studied using transmission {sup 57}Fe Moessbauer 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 Fe{sup 3+} to Fe{sup 2+} was observed in several cases. Reaction with hydrogen peroxide proved to be rather different for the four ligands, while the dihapto complex [XFe({eta}{sup 2}-O{sub 2})]{sup 3-} had surprisingly identical Moessbauer parameters for X = EDTA, CDTA or HEDTA. Paramagnetic spin relaxation observed in the Moessbauer spectra was found to be strongly influenced by the identity of the chelating ligand, despite the basically spin-spin origin of the phenomenon.

Studies on the antifungal activities of the novel synthesized chelating co-polymer emulsion lattices and their silver complexes

Directory of Open Access Journals (Sweden)

Abd-El-Ghaffar M.A.

2008-01-01

Full Text Available The novel binary chelating co-polymers of butyl acrylate with itaconic and maleic acids were prepared by emulsion polymerization process. The chelating co-polymers of butyl acrylate-co-itaconic acid (BuA/IA and butyl acrylate-co-maleic acid (BuA/MA and their silver complexes were characterized and identified using IR spectroscopy and differential scanning calorimetry (DSC measurements. The biological activities of these compounds were studied against various types of fungal species. The dose and the rate of leached silver ions were controlled by the type of the co-polymers used and the solubility in the medium. The results provided laboratory support for the concept that the polymers containing chemically bound biocide are useful for controlling microbial growth. The silver uptake by strains of different fungal species was studied to determine their difference in behavior to the antifungal activities of these compounds. The uptake strategy was examined by transmission electron microscopy (TEM.

Cobalt(III) complexes of [3(5)]adamanzane, 1,5,9,13-tetraazabicyclo[7.7.3]nonadecane. Report of an inert, chelate hydrogen carbonate ion

DEFF Research Database (Denmark)

Broge, Louise; Søtofte, Inger; Olsen, Carl Erik

2001-01-01

.H2O (3a). The coordination geometry around the cobalt(III) ion is a distorted octahedron with the inorganic ligands at cis-positions. Complex 2 is the second example of a cobalt(III) complex for which the X-ray structure,sfiows a chelate binding mode of the hydrogen carbonate entity. The pK(a) value...

Ruthenium chalcogenonitrosyl and bridged nitrido complexes containing chelating sulfur and oxygen ligands.

Science.gov (United States)

Ng, Ho-Yuen; Cheung, Wai-Man; Kwan Huang, Enrique; Wong, Kang-Long; Sung, Herman H-Y; Williams, Ian D; Leung, Wa-Hung

2015-11-14

Ruthenium thio- and seleno-nitrosyl complexes containing chelating sulfur and oxygen ligands have been synthesised and their de-chalcogenation reactions have been studied. The reaction of mer-[Ru(N)Cl3(AsPh3)2] with elemental sulfur and selenium in tetrahydrofuran at reflux afforded the chalcogenonitrosyl complexes mer-[Ru(NX)Cl3(AsPh3)2] [X = S (1), Se (2)]. Treatment of 1 with KN(R2PS)2 afforded trans-[Ru(NS)Cl{N(R2PS)2}2] [R = Ph (3), Pr(i) (4), Bu(t) (5)]. Alternatively, the thionitrosyl complex 5 was obtained from [Bu(n)4N][Ru(N)Cl4] and KN(Bu(t)2PS)2, presumably via sulfur atom transfer from [N(Bu(t)2PS)2](-) to the nitride. Reactions of 1 and 2 with NaLOEt (LOEt(-) = [Co(η(5)-C5H5){P(O)(LOEt)2}3](-)) gave [Ru(NX)LOEtCl2] (X = S (8), Se (9)). Treatment of [Bu(n)4N][Ru(N)Cl4] with KN(R2PS)2 produced Ru(IV)-Ru(IV)μ-nitrido complexes [Ru2(μ-N){N(R2PS)2}4Cl] [R = Ph (6), Pr(i) (7)]. Reactions of 3 and 9 with PPh3 afforded 6 and [Ru(NPPh3)LOEtCl2], respectively. The desulfurisation of 5 with [Ni(cod)2] (cod = 1,5-cyclooctadiene) gave the mixed valance Ru(III)-Ru(IV)μ-nitrido complex [Ru2(μ-N){N(Bu(t)2PS)2}4] (10) that was oxidised by [Cp2Fe](PF6) to give the Ru(IV)-Ru(IV) complex [Ru2(μ-N){N(Bu(t)2PS)2}4](PF6) ([10]PF6). The crystal structures of 1, 2, 3, 7, 9 and 10 have been determined.

Chelated Nitrogen-Sulphur-Codoped TiO2: Synthesis, Characterization, Mechanistic, and UV/Visible Photocatalytic Studies

Directory of Open Access Journals (Sweden)

Hayat Khan

2017-01-01

Full Text Available This study presents in detail the physicochemical, photoluminescent, and photocatalytic properties of carboxylic acid chelated nitrogen-sulphur-codoped TiO2. From the Fourier transform infrared spectroscopic study, it was revealed that the formate group formed bidentate bridging linkage while the acetate group coordinated in a bidentate chelating mode with a titanium precursor. In compliance with X-ray diffraction data, the anatase to rutile transformation temperature was extended due to carboxylic acid chelation and NS codoping. Raman analysis indicated four Raman peaks at 146, 392, 512, and 632 cm−1 for the precalcined chelated TiO2; on incorporation with NS dopants, an increase in Raman intensity for these peaks was recorded, indicating the structure stability of the anatase phase. Furthermore, X-ray photoelectron spectroscopic study revealed the presence of anionic doping of nitrogen and cationic doping of sulphur in the lattice of TiO2. When evaluating the UV-visible photodegradation rate of 4-chlorophenol, the modified TiO2 (NS0.06-TFA showed the highest photocatalytic activity. In connection with the activity tests, several scavenger agents were employed to elucidate the significance of the different reactive oxidizing species during the photocatalytic process. Moreover, the transfer pathways of photogenerated carriers and the photocatalytic reaction mechanism of modified TiO2 were also explained in detail.

[Complex skull defects reconstruction with САD/САМ titanium and polyetheretherketone (PEEK) implants].

Science.gov (United States)

Eolchiyan, S A

2014-01-01

Predictable and stable functional and aesthetic result is the aim of priority for the neurosurgeon dealing with the reconstruction of large cranial bone defects and complex-formed skull defects involving cranio-orbital region. the paper presents the experience with САD/САМ titanium and polyetheretherketone (PEEK) implants for complex-formed and large skull bone defects reconstruction. Between 2005 and 2013 nine patients (5 females and 4 males) underwent cranioplasty and cranio-facial reconstruction with insertion of the customized САD/САМ titanium and PEEK implants. Computer-assisted preoperative planning was undertaken by the surgeon and the engineer together in 3 cases to provide accurate implant design. Eight patients had complex-formed and large posttraumatic defects of fronto-orbital (7 cases) and parietal (one case) regions. In two of these cases one-step reconstruction surgery for posttraumatic fronto-orbital defects combined with adjacent orbital roof (one case) and orbito-zygomatic (one case) deformities was performed. One patient underwent one-step primary cranioplasty after cranio-orbital fibrous dysplasia focus resection. Titanium implants were used in 4 cases while PEEK implants - in 5 ones. The follow-up period ranged from 6 months till 8,5 years (median 4,4 years). The accuracy of the implant intraoperative fit was perfect in all cases. Postoperative wounds healed primary and there were no any complications in the series presented. Post-op clinical assessment and CT data testified to high implants precision, good functional and aesthetic outcomes in all patients. САD/САМ titanium and PEEK implants application should allow for optimal reconstruction in the challenging patients with complex-formed and large skull bone defects providing predictable good functional and aesthetic result together with surgery morbidity and duration reduction. Computer-assisted preoperative planning should be undertaken for САD/САМ implants creation in

New Chelators for Low Temperature Al(18)F-Labeling of Biomolecules.

Science.gov (United States)

Cleeren, Frederik; Lecina, Joan; Billaud, Emilie M F; Ahamed, Muneer; Verbruggen, Alfons; Bormans, Guy M

2016-03-16

The Al(18)F labeling method is a relatively new approach that allows radiofluorination of biomolecules such as peptides and proteins in a one-step procedure and in aqueous solution. However, the chelation of the {Al(18)F}(2+) core with the macrocyclic chelators NOTA or NODA requires heating to 100-120 °C. Therefore, we have developed new polydentate ligands for the complexation of {Al(18)F}(2+) with good radiochemical yields at a temperature of 40 °C. The stability of the new Al(18)F-complexes was tested in phosphate buffered saline (PBS) at pH 7.4 and in rat serum. The stability of the Al(18)F-L3 complex was found to be comparable to that of the previously reported Al(18)F-NODA complex up to 60 min in rat serum. Moreover, the biodistribution of Al(18)F-L3 in healthy mice showed the absence of in vivo defluorination since no significant bone uptake was observed, whereas the major fraction of activity at 60 min p.i. was observed in liver and intestines, indicating hepatobiliary clearance of the radiolabeled ligand. The acyclic chelator H3L3 proved to be a good lead candidate for labeling of heat-sensitive biomolecules with fluorine-18. In order to obtain a better understanding of the different factors influencing the formation and stability of the complex, we carried out more in-depth experiments with ligand H3L3. As a proof of concept, we successfully conjugated the new AlF-chelator with the urea-based PSMA inhibitor Glu-NH-CO-NH-Lys to form Glu-NH-CO-NH-Lys(Ahx)L3, and a biodistribution study in healthy mice was performed with the Al(18)F-labeled construct. This new class of AlF-chelators may have a great impact on PET radiochemical space as it will stimulate the rapid development of new fluorine-18 labeled peptides and other heat-sensitive biomolecules.

Chiral DOTA chelators as an improved platform for biomedical imaging and therapy applications.

Science.gov (United States)

Dai, Lixiong; Jones, Chloe M; Chan, Wesley Ting Kwok; Pham, Tiffany A; Ling, Xiaoxi; Gale, Eric M; Rotile, Nicholas J; Tai, William Chi-Shing; Anderson, Carolyn J; Caravan, Peter; Law, Ga-Lai

2018-02-27

Despite established clinical utilisation, there is an increasing need for safer, more inert gadolinium-based contrast agents, and for chelators that react rapidly with radiometals. Here we report the syntheses of a series of chiral DOTA chelators and their corresponding metal complexes and reveal properties that transcend the parent DOTA compound. We incorporated symmetrical chiral substituents around the tetraaza ring, imparting enhanced rigidity to the DOTA cavity, enabling control over the range of stereoisomers of the lanthanide complexes. The Gd chiral DOTA complexes are shown to be orders of magnitude more inert to Gd release than [GdDOTA] - . These compounds also exhibit very-fast water exchange rates in an optimal range for high field imaging. Radiolabeling studies with (Cu-64/Lu-177) also demonstrate faster labelling properties. These chiral DOTA chelators are alternative general platforms for the development of stable, high relaxivity contrast agents, and for radiometal complexes used for imaging and/or therapy.

Characterization of antibody-chelator conjugates: Determination of chelator content by terbium fluorescence titration

Energy Technology Data Exchange (ETDEWEB)

Brandt, K.D.; Schnobrich, K.E.; Johnson, D.K. (Abbott Laboratories, Department 90M, Abbott Park, IL (United States))

1991-01-01

Fluorescence titrations were performed by adding varying mole ratios of terbium(III) to antibody conjugates formed by benzyl isothiocyanate derivatives of three different polyaminopolycarboxylate chelators (NTA, EDTA, and DTPA) and the results compared to values for average chelator content obtained by cobalt-57 binding assays. For two different murine monoclonal antibodies, the average chelator content obtained by terbium fluorescence titration correlated closely with that measured by the cobalt-57 binding assay. It is concluded that lanthanide fluorescence titrations provide a useful alternative to radiometal binding assays for the determination of chelator content in protein-chelator conjugates.

Characterization of antibody-chelator conjugates: Determination of chelator content by terbium fluorescence titration

International Nuclear Information System (INIS)

Brandt, K.D.; Schnobrich, K.E.; Johnson, D.K.

1991-01-01

Fluorescence titrations were performed by adding varying mole ratios of terbium(III) to antibody conjugates formed by benzyl isothiocyanate derivatives of three different polyaminopolycarboxylate chelators (NTA, EDTA, and DTPA) and the results compared to values for average chelator content obtained by cobalt-57 binding assays. For two different murine monoclonal antibodies, the average chelator content obtained by terbium fluorescence titration correlated closely with that measured by the cobalt-57 binding assay. It is concluded that lanthanide fluorescence titrations provide a useful alternative to radiometal binding assays for the determination of chelator content in protein-chelator conjugates

Chelating polymeric membranes

KAUST Repository

Peinemann, Klaus-Viktor; Villalobos Vazquez de la Parra, Luis Francisco; Hilke, Roland

2015-01-01

microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

On the use of titanium hydride for powder injection moulding of titanium-based alloys

International Nuclear Information System (INIS)

Carrenoo-Morelli, E.; Bidaux, J.-E.

2009-01-01

Full text: Titanium and titanium-based alloys are excellent materials for a number of engineering applications because of their high strength, lightweight, good corrosion resistance, non magnetic characteristic and biocompatibility. The current processing steps are usually costly, and there is a growing demand for net-shape solutions for manufacturing parts of increasing complexity. Powder injection moulding is becoming a competitive alternative, thanks to the advances in production of good quality base-powders, binders and sintering facilities. Titanium hydride powders, have the attractiveness of being less reactive than fine titanium powders, easier to handle, and cheaper. This paper summarizes recent advances on PIM of titanium and titanium alloys from TiH2 powders, including shape-memory NiTi alloys. (author)

Chelation Therapy for Mercury Poisoning

Directory of Open Access Journals (Sweden)

Rong Guan

2009-01-01

Full Text Available Chelation therapy has been the major treatment for heavy metal poisoning. Various chelating agents have been developed and tested for treatment of heavy metal intoxications, including mercury poisoning. It has been clearly shown that chelating agents could rescue the toxicity caused by heavy metal intoxication, but the potential preventive role of chelating agents against heavy metal poisoning has not been explored much. Recent paper by Siddiqi and colleagues has suggested a protective role of chelating agents against mercury poisoning, which provides a promising research direction for broader application of chelation therapy in prevention and treatment of mercury poisoning.

Click-to-Chelate: Development of Technetium and Rhenium-Tricarbonyl Labeled Radiopharmaceuticals

Directory of Open Access Journals (Sweden)

Thomas L. Mindt

2013-03-01

Full Text Available 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 (biomolecules 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.

f-Element Ion Chelation in Highly Basic Media

International Nuclear Information System (INIS)

Paine, Robert T.

1999-01-01

High-level radioactive waste (HLW) generated in the DOE complex is stored in tanks at several sites, but predominantly it is found at the Hanford reservation. Much of the material has been exposed to high pHs, consequently the waste exists in a complex, poorly understood mixture of solids, gels and solutions. The final waste remediation plan may involve chemical separation of fractions and a suitable, well developed molecular chemistry basis for performing these separations is not available. Indeed, the fundamental chemical behavior of most radioactive nuclides in basic media is not known. The goal of this project is to undertake fundamental studies of the coordination chemistry of f-element species in basic aqueous solutions containing common waste treatment ions (e.g., NO3 -, CO3 2-, organic carboxylates, and EDTA), as well as new waste scrubbing chelators produced in this study. The experimental agenda includes: 1. Studies of the speciation of Sr and Ln ions in basic solutions wit h and without common counterions; 2. Preparations of new multifunctional ligands that may act as strong, ion-specific chelators for Sr and/or Ln ions in basic media; and 3. Studies of the coordination and dissolution behavior of oxide-hydroxide species, as well as in insoluble sols, gels, and precipitates in combination with new chelating ligands. It is anticipated that this coordination chemistry will facilitate the design of advanced separation schemes required for handling the complex waste matrices found at the Hanford HLW facility

Titanium. Properties, raw datum surface, physicochemical basis and fabrication technique

International Nuclear Information System (INIS)

Garmata, V.A.; Petrun'ko, A.N.; Galitskij, N.V.; Olesov, Yu.G.; Sandler, R.A.

1983-01-01

On the nowadays science and technology achievements the complex of titanium metallurgy problems comprising raw material base, physico-chemical basis and fabrication technique, properties and titanium usage fields is considered for the first time. A particular attention is given to raw material base, manufacturing titanium concentrates and titanium tetrachloride, metallothermal reduction, improvement of metal quality. Data on titanium properties are given, processes of titanium powder metallurgy, scrap and waste processing, problems of economics and complex raw material use are considered

Uranium fluorides analysis. Titanium spectrophotometric determination

International Nuclear Information System (INIS)

Anon.

Titanium determination in uranium hexafluoride in the range 0.7 to 100 microgrammes after transformation of uranium fluoride in sulfate. Titanium is separated by extraction with N-benzoylphenylhydroxylamine, reextracted by hydrochloric-hydrofluoric acid. The complex titanium-N-benzoylphenylhydroxylamine is extracted by chloroform. Spectrophotometric determination at 400 nm [fr

Room temperature synthesis of protonated layered titanate sheets using peroxo titanium carbonate complex solution.

Science.gov (United States)

Sutradhar, Narottam; Sinhamahapatra, Apurba; Pahari, Sandip Kumar; Bajaj, Hari C; Panda, Asit Baran

2011-07-21

We report the synthesis of peroxo titanium carbonate complex solution as a novel water-soluble precursor for the direct synthesis of layered protonated titanate at room temperature. The synthesized titanates showed excellent removal capacity for Pb(2+) and methylene blue. Based on experimental observations, a probable mechanism for the formation of protonated layered dititanate sheets is also discussed.

Investigation on the influence of metal ion impurities on the complexation behavior of generator produced {sup 90}Y with different bifunctional chelators

Energy Technology Data Exchange (ETDEWEB)

Pandey, Usha; Gamre, Naresh; Chakravarty, Rubel; Pillai, Maroor Raghavan Ambikalmajan; Dash, Ashutosh [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Radiopharmaceuticals Div.

2014-07-01

While the {sup 90}Sr/{sup 90}Y generator is the exclusive source of obtaining 'no carrier added' {sup 90}Y for targeted therapy, the presence of trace metals in the radiolabeling solutions poses a serious challenge owing to their ability to diminish the {sup 90}Y complexation yields with bifunctional chelators (BFCs). p-SCN-Bn-PCTA is a novel ligand having faster complexation kinetics with a number of radiometals. In this work, a systematic investigation was performed to evaluate the chelating ability of p-SCN-Bn-PCTA for {sup 90}Y and the influence of trace metal ions on it's complexation with {sup 90}Y in comparison to p-SCN-Bn-DTPA and p-SCN-Bn-DOTA using {sup 90}YCl{sub 3} obtained from an electrochemical generator. Results from our study indicate that while p-SCN-Bn-PCTA gave very good radiolabeling yields with {sup 90}Y when the reaction was carried out by heating for few minutes, it was most sensitive to the presence of trace metals, especially Fe(III). An independent and useful observation is that p-SCN-Bn-PCTA could be considered as the ligand of choice for assessing the chemical purity of generator derived {sup 90}Y.

Hepatobiliary delivery of polyaminopolycarboxylate chelates: Synthesis and characterization of a cholic acid conjugate of EDTA and biodistribution and imaging studies with its indium-111 chelate

Energy Technology Data Exchange (ETDEWEB)

Betebenner, D.A.; Carney, P.L.; Zimmer, A.M.; Kazikiewicz, J.M.; Bruecher, E.S.; Sherry, A.D.; Johnson, D.K. (Abbott Laboratories, Abbott Park, Illinois (USA))

1991-03-01

A conjugate in which the steroid nucleus of cholic acid was linked to EDTA via an 11-atom spacer was obtained by reacting the succinimidyl ester of cholic acid with the amine formed by reaction of a benzyl isothiocyanate derivative of EDTA with N-(tert-butoxycarbonyl)ethylenediamine and subsequent deprotection. Potentiometric titration studies with model complexes showed that the EDTA moiety retained the ability to form 1:1 chelates of high thermodynamic stability, although formation constants were some 3-4 log K units lower for complexes of the conjugate than for the analogous chelates with underivatized EDTA. A complex formed between the cholic acid-EDTA conjugate and 111InIII was clearly rapidly into the liver when injected iv into mice, with subsequent excretion from the liver into the gastrointestinal tract being complete within 1 h of injection. Radioscintigraphic imaging studies conducted in a rabbit given the 111In-labeled conjugate also showed early liver uptake followed by rapid clearance from the liver into the intestine, with good visualization of the gallbladder in images obtained at 20-25 min postinjection. It is concluded that conjugation to cholic acid provides a useful means for the hepatobiliary delivery of EDTA chelates that otherwise exhibit predominantly extracellular distribution and renal clearance.

Hepatobiliary delivery of polyaminopolycarboxylate chelates: Synthesis and characterization of a cholic acid conjugate of EDTA and biodistribution and imaging studies with its indium-111 chelate

International Nuclear Information System (INIS)

Betebenner, D.A.; Carney, P.L.; Zimmer, A.M.; Kazikiewicz, J.M.; Bruecher, E.S.; Sherry, A.D.; Johnson, D.K.

1991-01-01

A conjugate in which the steroid nucleus of cholic acid was linked to EDTA via an 11-atom spacer was obtained by reacting the succinimidyl ester of cholic acid with the amine formed by reaction of a benzyl isothiocyanate derivative of EDTA with N-(tert-butoxycarbonyl)ethylenediamine and subsequent deprotection. Potentiometric titration studies with model complexes showed that the EDTA moiety retained the ability to form 1:1 chelates of high thermodynamic stability, although formation constants were some 3-4 log K units lower for complexes of the conjugate than for the analogous chelates with underivatized EDTA. A complex formed between the cholic acid-EDTA conjugate and 111InIII was clearly rapidly into the liver when injected iv into mice, with subsequent excretion from the liver into the gastrointestinal tract being complete within 1 h of injection. Radioscintigraphic imaging studies conducted in a rabbit given the 111In-labeled conjugate also showed early liver uptake followed by rapid clearance from the liver into the intestine, with good visualization of the gallbladder in images obtained at 20-25 min postinjection. It is concluded that conjugation to cholic acid provides a useful means for the hepatobiliary delivery of EDTA chelates that otherwise exhibit predominantly extracellular distribution and renal clearance

Benzimidazolyl methyliminodiacetic acids: new bifunctional chelators of technetium for hepatobiliary scintigraphy

International Nuclear Information System (INIS)

Hunt, F.C.; Wilson, J.G.; Maddalena, D.J.

1979-01-01

Dimethyl- and chloro- substituted benzimidazolyl methyliminodiacetic acids have been synthesized and evaluated as new bifunctional chelators of /sup 99m/Tc. Stannous chelates of these compounds were prepared as freeze-dried kits and labeled with /sup 99m/Tc. The radiopharmaceuticals thus prepared were rapidly excreted by the hepatobiliary system of rats and rabbits with little urinary excretion. The chloro- compound had a higher biliary and lesser urinary excretion than the dimethyl- however both technetium complexes provided good scintigraphic images of the hepatobiliary system in animals. The compounds behaved similarly to the /sup 99m/Tc-lidocaine iminodiacetic acid [HIDA] complexes with respect to their biliary elimination

Selective chelation-supercritical fluid extraction of metal ions from waste materials

International Nuclear Information System (INIS)

Wai, C.N.; Laintz, K.E.; Yonker, C.R.

1993-01-01

The removal of toxic organics, metals, and radioisotopes from solids or liquids is a major concern in the treatment of industrial and nuclear wastes. For this reason, developing methods for selective separation of toxic metals and radioactive materials from solutions of complex matrix is an important problem in environmental research. Recent developments indicate supercritical fluids are good solvents for organic compounds. Many gases become supercritical fluids under moderate temperatures and pressures. For example, the critical temperature and pressure of carbon dioxide are 31 degrees C and 73 atm, respectively. The high diffusivity, low viscosity, and T-P dependence of solvent strength are some attractive properties of supercritical fluid extraction (SFE). Since CO 2 offers the additional benefits of stability and non-toxicity, the SFE technique avoids generation of organic liquid waste and exposure of personnel to toxic solvents. While direct extraction of metal ions by supercritical fluids is highly inefficient, these ions when complexed with organic ligands become quite soluble in supercritical fluids. Specific ligands can be used to achieve selective extraction of metal ions in this process. After SFE, the fluid phase can be depressurized for precipitation of the metal chelates and recycled. The ligand can also be regenerated for repeated use. The success of this selective chelation-supercritical fluid extraction (SC-SFE) process depends on a number of factors including the efficiencies of the selective chelating agents, solubilities of metal chelates in supercritical fluids, rate of extraction, ease of regeneration of the ligands, etc. In this report, the authors present recent results on the studies of the solubilities of metal chelates in supercritical CO 2 , experimental ions from aqueous solution, and the development of selective chelating agents (ionizable crown ethers) for the extraction of lanthanides and actinides

DFT study of the interaction between DOTA chelator and competitive alkali metal ions.

Science.gov (United States)

Frimpong, E; Skelton, A A; Honarparvar, B

2017-09-01

1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetracetic acid (DOTA) is an important chelator for radiolabeling of pharmaceuticals. The ability of alkali metals found in the body to complex with DOTA and compete with radio metal ions can alter the radiolabeling process. Non-covalent interactions between DOTA complexed with alkali metals Li + , Na + , K + and Rb + , are investigated with density functional theory using B3LYP and ωB97XD functionals. Conformational possibilities of DOTA were explored with a varying number of carboxylic pendant arms of DOTA in close proximity to the ions. It is found that the case in which four arms of DOTA are interacting with ions is more stable than other conformations. The objective of this study is to explore the electronic structure properties upon complexation of alkali metals Li + Na + , K + and Rb + with a DOTA chelator. Interaction energies, relaxation energies, entropies, Gibbs free energies and enthalpies show that the stability of DOTA, complexed with alkali metals decreases down the group of the periodic table. Implicit water solvation affects the complexation of DOTA-ions leading to decreases in the stability of the complexes. NBO analysis through the natural population charges and the second order perturbation theory, revealed a charge transfer between DOTA and alkali metals. Conceptual DFT-based properties such as HOMO/LUMO energies, ΔE HOMO-LUMO and chemical hardness and softness indicated a decrease in the chemical stability of DOTA-alkali metal complexes down the alkali metal series. This study serves as a guide to researchers in the field of organometallic chelators, particularly, radiopharmaceuticals in finding the efficient optimal match between chelators and various metal ions. Copyright © 2017 Elsevier Inc. All rights reserved.

Chelate forms of biometalls. Theoretical aspects of obtaining and characteristics

Directory of Open Access Journals (Sweden)

A. Kapustyan

2017-04-01

Full Text Available The problem of microelements bioavailability is highlighted and the correct ways of its solution are substantiated as a result of generalization of theoretical aspects of obtaining of the biometals chelate forms. The characteristics of the main biogenic elements, their physiological significance, electrochemical properties are presented. The main examples of the participation of biometals in various biological processes are given. The properties and the structure peculiarities of biometals coordination complexes are considered in detail. It is shown that in obtaining of biometals chelate forms, there is the mutual selectivity and the affinity of biometals and ligands. The main factors of obtaining a hard metal complex are given. Potential bioligands for obtaining bioavailable forms of microelements are detailed. Among them there are amino acids, peptides, proteins, nucleic acids, carbohydrates. The possible character of complexation depending on the nature of the bioligand is indicated. Practical examples of preparation of biometals mixed ligand complexes are given. The expediency of using metabolic products and processing of lactic acid bacteria as promising components of mixed ligand chelate complexes is substantiated. These substances contain in their composition a mass of potential donor atoms that are capable to form covalent and coordination bonds with biomethalles, and also possess high biological and immunotropic activities. The use of this system in the biocoordination compounds of the "metals of life" can provide a synergistic effect of the components, significantly to expand the range of their physiological activity and to increase the degree of assimilation by the body.

Complexation studies of actinides (U, Pu, Am) with linear polyamino-carboxylate ligands and sidero-chelates; Etudes de la chelation d'actinides (U, Pu, Am) par des ligands polyaminocarboxylate lineaires et des siderochelates d'interet environnemental

Energy Technology Data Exchange (ETDEWEB)

Nguyen, L.V.

2010-11-25

As part of our research endeavour aimed at developing and improving decontamination processes of wastewater containing alpha emitters, physico-chemical complexation studies of actinides (U, Pu, Am) with organic open-chain ligands such as poly-aminocarboxylic acids (H{sub 4}EDTA) and sidero-chelates (di-hydroxamic acids and desferrioxamine B) have been carried out. Gaining a clear understanding of the coordination properties of the targeted actinides is an essential step towards the selection of the most appropriate chelating agents that will exhibit high uptake efficiencies. EXAFS (Extended X-ray Absorption Fine Structure) measurements at the ESRF synchrotron enabled to elucidate the coordination scheme of uranium and plutonium complexes. Solution thermodynamic investigations were intended to provide valuable information about the nature and the stability of the uranium(VI) and americium(III) complexes prevailing at a given pH in solution. The set of stability constants determined from potentiometric and UV-visible spectrophotometric titrations, allowed to predict the speciation of the selected actinides in presence of the aforementioned ligands and to determine the pH range required for achieving 'ultimate' decontamination. (author) [French] Dans le cadre du developpement et de l'amelioration des procedes de decontamination d'effluents aqueux contamines par des radioelements emetteurs alpha, des etudes physico-chimiques sur la complexation des actinides (U, Pu, Am) avec des ligands organiques tels que des acides polyaminocarboxyliques lineaires (H{sub 4}EDTA) et des siderochelates (acides dihydroxamiques et desferrioxamine B) ont ete effectuees. La comprehension des proprietes de coordination est une etape essentielle pour selectionner les meilleurs agents chelatants qui se montreront efficaces dans le traitement des effluents. Les schemas de coordination des complexes d'uranium et de plutonium avec ces ligands ont ete determines a l

Chelation in metal intoxication

DEFF Research Database (Denmark)

Aaseth, Jan; Skaug, Marit Aralt; Cao, yang

2015-01-01

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 incon......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...

Synthesis and studies of novel high metal content organic aerogels obtained from a polymerizable titanium complex

International Nuclear Information System (INIS)

Cadra, S.

2010-01-01

Inertial Confinement Fusion (ICF) is a technique widely studied by the French atomic commission (CEA). Experiments will be performed within the Laser Megajoule (LMJ). They require innovative materials like organic aerogels that constitute laser targets. Such polymeric material must provide both a high porosity and a significant titanium percentage (1 atom %). Moreover, the monomers developed must be compatible with the synthesis procedure already in use. According to these specifications, a new polymerizable titanium complex was synthesized and fully characterized. This air and moisture-stable monomer provides a high metal percentage. Its free-radical cross-linked copolymerization affords several titanium-containing polymers. These gels were dried under supercritical conditions and organic aerogels were obtained. The chemical compositions of these materials were investigated by NMR, IR and elemental analysis while their structure was characterized by MEB-EDS, MET, N 2 adsorption/desorption isotherms measurements and SAXS. The data collected fit the specification requirements. Moreover, the mechanisms responsible of the foam nano-structure formation were discussed. (author) [fr

Expanding the Therapeutic Potential of the Iron Chelator Deferasirox in the Development of Aqueous Stable Ti(IV) Anticancer Complexes.

Science.gov (United States)

Loza-Rosas, Sergio A; Vázquez-Salgado, Alexandra M; Rivero, Kennett I; Negrón, Lenny J; Delgado, Yamixa; Benjamín-Rivera, Josué A; Vázquez-Maldonado, Angel L; Parks, Timothy B; Munet-Colón, Charlene; Tinoco, Arthur D

2017-07-17

The recent X-ray structure of titanium(IV)-bound human serum transferrin (STf) exhibiting citrate as a synergistic anion reveals a difference in Ti(IV) coordination versus iron(III), the metal endogenously delivered by the protein to cells. This finding enriches our bioinspired drug design strategy for Ti(IV)-based anticancer therapeutics, which applies a family of Fe(III) chelators termed chemical transferrin mimetic (cTfm) ligands to inhibit Fe bioavailability in cancer cells. Deferasirox, a drug used for iron overload disease, is a cTfm ligand that models STf coordination to Fe(III), favoring Fe(III) binding versus Ti(IV). This metal affinity preference drives deferasirox to facilitate the release of cytotoxic Ti(IV) intracellularly in exchange for Fe(III). An aqueous speciation study performed by potentiometric titration from pH 4 to 8 with micromolar levels of Ti(IV) deferasirox at a 1:2 ratio reveals exclusively Ti(deferasirox) 2 in solution. The predominant complex at pH 7.4, [Ti(deferasirox) 2 ] 2- , exhibits the one of the highest aqueous stabilities observed for a potent cytotoxic Ti(IV) species, demonstrating little dissociation even after 1 month in cell culture media. UV-vis and 1 H NMR studies show that the stability is unaffected by the presence of biomolecular Ti(IV) binders such as citrate, STf, and albumin, which have been shown to induce dissociation or regulate cellular uptake and can alter the activity of other antiproliferative Ti(IV) complexes. Kinetic studies on [Ti(deferasirox) 2 ] 2- transmetalation with Fe(III) show that a labile Fe(III) source is required to induce this process. The initial step of this process occurs on the time scale of minutes, and equilibrium for the complete transmetalation is reached on a time scale of hours to a day. This work reveals a mechanism to deliver Ti(IV) compounds into cells and trigger Ti(IV) release by a labile Fe(III) species. Cellular studies including other cTfm ligands confirm the Fe(III) depletion

Vanadium and titanium determination by resorcinalhydrazide of salicylic acid

Energy Technology Data Exchange (ETDEWEB)

Karpova, O I; Pilipenko, A T; Lukachina, V V [AN Ukrainskoj SSR, Kiev. Inst. Kolloidnoj Khimii i Khimii Vody

1979-02-01

The complexing of titanium and vanadium with resorcinalhydrazyl of salicylic acid (RHSA) in water-organic media is studied. Titanium (4) forms a complex at pH 0.8-1.8, vanadium - at pH 2.5-5.6, and at pH 7.6-9.8. The complexes are well extracted by polar and nonpolar solvents from acid solutions. The techniques are developed for the determination of titanium and vanadium by the RHSA agent in nickel alloys.

Chelation Therapy for Mercury Poisoning

OpenAIRE

Rong Guan; Han Dai

2009-01-01

Chelation therapy has been the major treatment for heavy metal poisoning. Various chelating agents have been developed and tested for treatment of heavy metal intoxications, including mercury poisoning. It has been clearly shown that chelating agents could rescue the toxicity caused by heavy metal intoxication, but the potential preventive role of chelating agents against heavy metal poisoning has not been explored much. Recent paper by Siddiqi and colleagues has suggested a protective role o...

f-Element Ion Chelation in Highly Basic Media

International Nuclear Information System (INIS)

Paine, R.T.

2000-01-01

A large body of data has been collected over the last fifty years on the chemical behavior of f-element ions. The ions undergo rapid hydrolysis reactions in neutral or basic aqueous solutions that produce poorly understood oxide-hydroxide species; therefore, most of the fundamental f-element solution chemistry has allowed synthetic and separations chemists to rationally design advanced organic chelating ligands useful for highly selective partitioning and separation of f-element ions from complex acidic solution matrices. These ligands and new examples under development allow for the safe use and treatment of solutions containing highly radioactive species. This DOE/EMSP project was undertaken to address the following fundamental objectives: (1) study the chemical speciation of Sr and lanthanide (Ln) ions in basic aqueous media containing classical counter anions found in waste matrices; (2) prepare pyridine N-oxide phosphonates and phosphonic acids that might act as selective chelators for Ln ions in model basic pH waste streams; (3) study the binding of the new chelators toward Ln ions and (4) examine the utility of the chelators as decontamination and dissolution agents under basic solution conditions. The project has been successful in attacking selected aspects of the very difficult problems associated with basic pH solution f-element waste chemistry. In particular, the project has (1) shed additional light on the initial stages of Ln ion sol-gel-precipitate formulation under basic solution conditions; (2) generated new families of pyridine phosphonic acid chelators; (3) characterized the function of the chelators and (4) examined their utility as oxide-hydroxide dissolution agents. These findings have contributed significantly to an improved understanding of the behavior of Ln ions in basic media containing anions found in typical waste sludges as well as to the development of sludge dissolution agents. The new chelating reagents are easily made and could be

Differential cytotoxicity induced by the Titanium(IV)Salan complex Tc52 in G2-phase independent of DNA damage

International Nuclear Information System (INIS)

Pesch, Theresa; Schuhwerk, Harald; Wyrsch, Philippe; Immel, Timo; Dirks, Wilhelm; Bürkle, Alexander; Huhn, Thomas; Beneke, Sascha

2016-01-01

Chemotherapy is one of the major treatment modalities for cancer. Metal-based compounds such as derivatives of cisplatin are in the front line of therapy against a subset of cancers, but their use is restricted by severe side-effects and the induction of resistance in treated tumors. Subsequent research focused on development of cytotoxic metal-complexes without cross-resistance to cisplatin and reduced side-effects. This led to the discovery of first-generation titanium(IV)salan complexes, which reached clinical trials but lacked efficacy. New-generation titanium (IV)salan-complexes show promising anti-tumor activity in mice, but their molecular mechanism of cytotoxicity is completely unknown. Four different human cell lines were analyzed in their responses to a toxic (Tc52) and a structurally highly related but non-toxic (Tc53) titanium(IV)salan complex. Viability assays were used to reveal a suitable treatment range, flow-cytometry analysis was performed to monitor the impact of dosage and treatment time on cell-cycle distribution and cell death. Potential DNA strand break induction and crosslinking was investigated by immunostaining of damage markers as well as automated fluorometric analysis of DNA unwinding. Changes in nuclear morphology were analyzed by DAPI staining. Acidic beta-galactosidase activity together with morphological changes was monitored to detect cellular senescence. Western blotting was used to analyze induction of pro-apoptotic markers such as activated caspase7 and cleavage of PARP1, and general stress kinase p38. Here we show that the titanium(IV)salan Tc52 is effective in inducing cell death in the lower micromolar range. Surprisingly, Tc52 does not target DNA contrary to expectations deduced from the reported activity of other titanium complexes. Instead, Tc52 application interferes with progression from G2-phase into mitosis and induces apoptotic cell death in tested tumor cells. Contrarily, human fibroblasts undergo senescence in a

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

Science.gov (United States)

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

2015-01-01

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

Manufacture of a four-sheet complex component from different titanium alloys by superplastic forming

Science.gov (United States)

Allazadeh, M. R.; Zuelli, N.

2017-10-01

A superplastic forming (SPF) technology process was deployed to form a complex component with eight-pocket from a four-sheet sandwich panel sheetstock. Six sheetstock packs were composed of two core sheets made of Ti-6Al-4V or Ti-5Al-4Cr-4Mo-2Sn-2Zr titanium alloy and two skin sheets made of Ti-6Al-4V or Ti-6Al-2Sn-4Zr-2Mo titanium alloy in three different combinations. The sheets were welded with two subsequent welding patterns over the core and skin sheets to meet the required component's details. The applied welding methods were intermittent and continuous resistance seam welding for bonding the core sheets to each other and the skin sheets over the core panel, respectively. The final component configuration was predicted based on the die drawings and finite element method (FEM) simulations for the sandwich panels. An SPF system set-up with two inlet gas pipe feeding facilitated the trials to deliver two pressure-time load cycles acting simultaneously which were extracted from FEM analysis for specific forming temperature and strain rate. The SPF pressure-time cycles were optimized via GOM scanning and visually inspecting some sections of the packs in order to assess the levels of core panel formation during the inflation process of the sheetstock. Two sets of GOM scan results were compared via GOM software to inspect the surface and internal features of the inflated multisheet packs. The results highlighted the capability of the tested SPF process to form complex components from a flat multisheet pack made of different titanium alloys.

Molecular engineering of lanthanide ion chelating phospholipids generating assemblies with a switched magnetic susceptibility.

Science.gov (United States)

Isabettini, Stéphane; Massabni, Sarah; Hodzic, Arnel; Durovic, Dzana; Kohlbrecher, Joachim; Ishikawa, Takashi; Fischer, Peter; Windhab, Erich J; Walde, Peter; Kuster, Simon

2017-08-09

Lanthanide ion (Ln 3+ ) chelating amphiphiles are powerful molecules for tailoring the magnetic response of polymolecular assemblies. Mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylene triaminepentaacetate (DMPE-DTPA) complexed to Ln 3+ deliver highly magnetically responsive bicelles. Their magnetic properties are readily tuned by changing the bicellar size or the magnetic susceptibility Δχ of the bilayer lipids. The former technique is intrinsically bound to the region of the phase diagram guarantying the formation of bicelles. Methods aiming towards manipulating the Δχ of the bilayer are comparatively more robust, flexible and lacking. Herein, we synthesized a new Ln 3+ chelating phospholipid using glutamic acid as a backbone: DMPE-Glu-DTPA. The chelate polyhedron was specifically engineered to alter the Δχ, whilst remaining geometrically similar to DMPE-DTPA. Planar asymmetric assemblies hundreds of nanometers in size were achieved presenting unprecedented magnetic alignments. The DMPE-Glu-DTPA/Ln 3+ complex switched the Δχ, achieving perpendicular alignment of assemblies containing Dy 3+ and parallel alignment of those containing Tm 3+ . Moreover, samples with chelated Yb 3+ were more alignable than the Tm 3+ chelating counterparts. Such a possibility has never been demonstrated for planar Ln 3+ chelating polymolecular assemblies. The physico-chemical properties of these novel assemblies were further studied by monitoring the alignment behavior at different temperatures and by including 16 mol% of cholesterol (Chol-OH) in the phospholipid bilayer. The DMPE-Glu-DTPA/Ln 3+ complex and the resulting assemblies are promising candidates for applications in numerous fields including pharmaceutical technologies, structural characterization of membrane biomolecules by NMR spectroscopy, as contrasting agents for magnetic resonance imaging, and for the development of smart optical gels.

Kinetic studies on the oxidation of oxyhemoglobin by biologically active iron thiosemicarbazone complexes: relevance to iron-chelator-induced methemoglobinemia.

Science.gov (United States)

Basha, Maram T; Rodríguez, Carlos; Richardson, Des R; Martínez, Manuel; Bernhardt, Paul V

2014-03-01

The oxidation of oxyhemoglobin to methemoglobin has been found to be facilitated by low molecular weight iron(III) thiosemicarbazone complexes. This deleterious reaction, which produces hemoglobin protein units unable to bind dioxygen and occurs during the administration of iron chelators such as the well-known 3-aminopyridine-2-pyridinecarbaldehyde thiosemicarbazone (3-AP; Triapine), has been observed in the reaction with Fe(III) complexes of some members of the 3-AP structurally-related thiosemicarbazone ligands derived from di-2-pyridyl ketone (HDpxxT series). We have studied the kinetics of this oxidation reaction in vitro using human hemoglobin and found that the reaction proceeds with two distinct time-resolved steps. These have been associated with sequential oxidation of the two different oxyheme cofactors in the α and β protein chains. Unexpected steric and hydrogen-bonding effects on the Fe(III) complexes appear to be the responsible for the observed differences in the reaction rate across the series of HDpxxT ligand complexes used in this study.

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

Science.gov (United States)

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

2014-01-01

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

Chelation of di- and trivalent iron with some polyaminopolycarboxylic acids

International Nuclear Information System (INIS)

Hafez, M.B.; Sharabi, Nahid; Patti, Francois.

1979-02-01

The chelation of di- and trivalent iron with some polyaminopolycarboxylic acids was studied. The influence of pH on the formation of the complex was investigated, the molecular ratio and the stability constants were determined [fr

Combined chelation based on glycosyl-mono- and bis-hydroxypyridinones for aluminium mobilization: solution and biodistribution studies.

Science.gov (United States)

Chaves, Sílvia; Dron, Paul I; Danalache, Florina A; Sacoto, Diana; Gano, Lurdes; Santos, M Amélia

2009-11-01

Taking into account the recognized interest of a poly-pharmacological strategy in chelation therapy, a study of aluminium combined chelation based on 3-hydroxy-4-pyridinone (3,4-HP) compounds with complementary properties, associated to different denticity, size and extrafunctionality, is presented herein. In particular, Al-chelation has been explored, using a tetradentate IDA bis-(3,4-HP) ligand, L, and two N-glycosyl mono-(3,4-HP) derivatives (A or B). Combined complexation studies with the tetradentate and the most promising bidentate ligand (A) evidenced the formation of ternary complexes with high thermodynamic stability (Al-L-A) being the predominant species at physiological pH. In vivo studies on the ability for radiotracer ((67)Ga) removal from loaded mice, as a model of aluminium accumulation in body, have shown that the simultaneous administration to (67)Ga-loaded mice of a mono- and a bis-(3,4-HP) chelator (e.g. A and L) leads to a rapid metal elimination from main organs and whole animal model. This may be rationalized by coadjuvation and eventual synergistic effects, due to complementary accessibility of the chelators to different cellular compartments.

Searching for new aluminium chelating agents: a family of hydroxypyrone ligands.

Science.gov (United States)

Toso, Leonardo; Crisponi, Guido; Nurchi, Valeria M; Crespo-Alonso, Miriam; Lachowicz, Joanna I; Mansoori, Delara; Arca, Massimiliano; Santos, M Amélia; Marques, Sérgio M; Gano, Lurdes; Niclós-Gutíerrez, Juan; González-Pérez, Josefa M; Domínguez-Martín, Alicia; Choquesillo-Lazarte, Duane; Szewczuk, Zbigniew

2014-01-01

Attention is devoted to the role of chelating agents in the treatment of aluminium related diseases. In fact, in spite of the efforts that have drastically reduced the occurrence of aluminium dialysis diseases, they so far constitute a cause of great medical concern. The use of chelating agents for iron and aluminium in different clinical applications has found increasing attention in the last thirty years. With the aim of designing new chelators, we synthesized a series of kojic acid derivatives containing two kojic units joined by different linkers. A huge advantage of these molecules is that they are cheap and easy to produce. Previous works on complex formation equilibria of a first group of these 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 aluminium(III) complex formation equilibria studied by potentiometry, electrospray ionization mass spectroscopy (ESI-MS), quantum-mechanical calculations and (1)H NMR spectroscopy are here described and discussed, and the structural characterization of one of these new ligands is presented. The in vivo studies show that these new bis-kojic derivatives induce faster clearance from main organs as compared with the monomeric analog. © 2013.

Spectroscopy, modeling and computation of metal chelate solubility in supercritical CO2. 1998 annual progress report

International Nuclear Information System (INIS)

Brennecke, J.F.; Chateauneuf, J.E.; Stadtherr, M.A.

1998-01-01

'This report summarizes work after 1 year and 8 months (9/15/96-5/14/98) of a 3 year project. Thus far, progress has been made in: (1) the measurement of the solubility of metal chelates in SC CO 2 with and without added cosolvents, (2) the spectroscopic determination of preferential solvation of metal chelates by cosolvents in SC CO 2 solutions, and (3) the development of a totally reliable computational technique for phase equilibrium computations. An important factor in the removal of metals from solid matrices with CO 2 /chelate mixtures is the equilibrium solubility of the metal chelate complex in the CO 2 .'

AAZTA: an ideal chelating agent for the development of {sup 44}Sc PET imaging agents

Energy Technology Data Exchange (ETDEWEB)

Nagy, Gabor; Szikra, Dezso; Trencsenyi, Gyoergy [Scanomed Ltd., Debrecen (Hungary); University of Debrecen, Medical Imaging Clinic (Hungary); Fekete, Aniko [University of Debrecen, Medical Imaging Clinic (Hungary); Garai, Ildiko [Scanomed Ltd., Debrecen (Hungary); Giani, Arianna M.; Negri, Roberto [Dipartimento di Scienze del Farmaco, Universita del Piemonte Orientale, Novara (Italy); Masciocchi, Norberto [Dipartimento di Scienza e Alta Tecnologia e To.Sca.Lab, Universita degli Studi dell' Insubria, Como (Italy); Maiocchi, Alessandro; Uggeri, Fulvio [Bracco Imaging spa, Bracco Research Centre, Colleretto Giacosa (Italy); Toth, Imre [Department of Inorganic and Analytical Chemistry, University of Debrecen (Hungary); Aime, Silvio [Dipartimento di Biotecnologie Molecolari e Scienze della Salute, Centro di Imaging Molecolare e Preclinico, Universita degli Studi di Torino (Italy); Giovenzana, Giovanni B. [Dipartimento di Scienze del Farmaco, Universita del Piemonte Orientale, Novara (Italy); CAGE Chemicals srl, Novara (Italy); Baranyai, Zsolt [Bracco Imaging spa, Bracco Research Centre, Colleretto Giacosa (Italy); Department of Inorganic and Analytical Chemistry, University of Debrecen (Hungary)

2017-02-13

Unprecedented fast and efficient complexation of Sc{sup III} was demonstrated with the chelating agent AAZTA (AAZTA=1,4-bis(carboxymethyl)-6-[bis(carboxymethyl)] amino-6-methylperhydro-1,4-d iazepine) under mild experimental conditions. The robustness of the {sup 44}Sc(AAZTA){sup -} chelate and conjugated biomolecules thereof is further shown by in vivo PET imaging in healthy and tumor mice models. The new results pave the way towards development of efficient Sc-based radiopharmaceuticals using the AAZTA chelator. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Stepwise Ti-Cl, Ti-CH3, and Ti-C6H5 bond dissociation enthalpies in bis(pentamethylcyclopentadienyl)titanium complexes

NARCIS (Netherlands)

Dias, Alberto R.; Salema, Margarida S.; Martinho Simões, Jose A.; Pattiasina, Johannes W.; Teuben, Jan H.

1988-01-01

Reaction-solution calorimetric studies involving the complexes Ti[η5-C5(CH3)5]2(CH3)2, Ti[η5-C5(CH3)5]2(CH3), Ti[η5-C5(CH3)5]2(C6H5), Ti[η5-C5(CH3)5]2Cl2, and Ti[η5-C5(CH3)5]2Cl, have enabled derivation of titanium-carbon and titanium-chlorine stepwise bond dissociation enthalpies in these species.

Copper and Zinc Chelation as a Treatment of Alzheimer's Disease

Science.gov (United States)

Hodak, Miroslav; Bernholc, Jerry

2014-03-01

Alzheimer's disease (AD) is a neurodegenerative disorder affecting millions of people in the U.S. The cause of the disease remains unknown, but amyloid- β (A β), a short peptide, is considered causal its pathogenesis. At cellular level, AD is characterized by deposits mainly composed of A β that also contain elevated levels of transition metals ions. Targeting metals is a promising new strategy for AD treatment, which uses moderately strong metal chelators to sequester them from A β or the environment. PBT2 is a chelating compound that has been the most promising in clinical trials. In our work, we use computer simulations to investigate complexes of a close analog of PBT2 with Cu2+ and Zn2+ ions. The calculations employ KS/FD DFT method, which combines Kohn-Sham DFT with the frozen-density DFT to achieve efficient description of explicit solvent beyond the first solvation shell. Our work is based on recent experiments and examines both 1:1 and 2:1 chelator-metal stochiometries detected experimentally. The results show that copper attaches more strongly than zinc, find that 1:1 complexes involve water in the first coordination shell and determine which one of several possible 2:1 geometries is the most preferable.

The preparation and characterization of novel human-like collagen metal chelates

Energy Technology Data Exchange (ETDEWEB)

Zhu, Chenhui; Sun, Yan [Shaanxi Key Laboratory of Degradable Biomedical Materials, School of Chemical Engineering Northwest University, Xi' an 710069 (China); Shaanxi R and D Center of Biomaterials and Fermentation Engineering, Xi' an 710069 (China); Wang, Yaoyu [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Xi' an 710069 (China); Luo, Yane, E-mail: luoyane@nwu.edu.cn [Shaanxi Key Laboratory of Degradable Biomedical Materials, School of Chemical Engineering Northwest University, Xi' an 710069 (China); Shaanxi R and D Center of Biomaterials and Fermentation Engineering, Xi' an 710069 (China); Fan, Daidi, E-mail: fandaidi@nwu.edu.cn [Shaanxi Key Laboratory of Degradable Biomedical Materials, School of Chemical Engineering Northwest University, Xi' an 710069 (China); Shaanxi R and D Center of Biomaterials and Fermentation Engineering, Xi' an 710069 (China)

2013-07-01

In order to develop the nutritional trace elements which could be absorbed and utilized effectively, protein chelates were adopted. Calcium, copper and manganese were considered based on their physiological functions, and the new chelates of HLC-Ca, HLC-Cu and HLC-Mn were formed in MOPS or MES buffer and purified by gel chromatography, and then freeze-dried. And they were detected and analyzed by atomic absorption spectrophotometry, ultraviolet–visible absorption (UV–vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, fluorescence quenching method, circular dichroism (CD) and differential scanning calorimetry (DSC). The results showed that some chemical reactions happened between HLC and the three metal ions to form new chemical compounds. The thermodynamic parameters, ∆H, ∆G and ∆S, showed that the chelation process between HLC and metal ions was performed spontaneously. Fluorescence quenching spectra of HLC indicated that the quenching mechanism was static in nature. According to the data of DSC, the new chelates were more stable than the free HLC. And HLC-metal complex was non-toxic to the BHK21 cell through MTT assay. - Highlights: ► HLC-Ca, HLC-Cu and HLC-Mn were new chemical compounds and different to free HLC. ► Possible sites for Ca{sup 2+}, Cu{sup 2+} and Mn{sup 2+} to bind with HLC were presented. ► The chelation process between HLC and metal ions was performed spontaneously. ► The thermodynamic stability of the new chelates was higher than that of free HLC.

Beliefs about chelation among thalassemia patients

Directory of Open Access Journals (Sweden)

Trachtenberg Felicia L

2012-12-01

Full Text Available Abstract 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 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

Chelating polymeric membranes

KAUST Repository

Peinemann, Klaus-Viktor

2015-01-22

The present application offers a solution to the current problems associated with recovery and recycling of precious metals from scrap material, discard articles, and other items comprising one or more precious metals. The solution is premised on a microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

Leach studies of chelating agents and influence on radionuclide leaching from simulated LLW/ILW cement waste forms

International Nuclear Information System (INIS)

Vejmelka, P.; Koester, R.; Ferrara, D.; Wacks, M.E.

1990-01-01

Leach studies were performed on cemented waste forms containing sodium nitrate, trace amounts of cesium-137, and cobalt-60, and a chelating agent (ethylene diamine tetraacetic acid (EDTA), nitrilotriacetic acid (NTA), or citric acid). Leaching of the chelates was measured in water and the effect of the chelates on the release of the Cs-137 and Co-60 was studied. The time dependence of the release rate of the chelates is comparable but the chelate concentration in solution and the released fractions are different. EDTA shows the highest release rate followed by NTA and citrate. The release of the non complex forming cesium is not affected by the presence of the chelates. Independent from the strong complex formation of cobalt with EDTA, NTA, and citrate in the alkaline region the cobalt release is also not affected by the presence of the chelates. The high calcium content of the system decreases the stability of the Co complexes in the high pH region (12-13). Experiments were performed to determine the equilibrium concentration of the chelates between liquid and solid phases. The liquid phases were deionized water, saturated sodium chloride, 24 percent magnesium chloride and Q-brine. The equilibrium studies are based on the assumption that in time a stable final condition is to be established in the near field of the waste form in which each compound is at chemical equilibrium between the dissolved and the various solid phases. The total release may be assessed from the concentration in solution and flow rate out of the near field. The fraction of EDTA released from the cement ranged from 0.2 in the Q-brine to 0.5 in the saturated sodium chloride. The concentration of EDSA in solution was dependent on the original amount in the cement sample, but the released fraction was independent of the initial loading. Indicating, EDTA concentration is not affected by solubility limits. 11 refs., 3 figs., 2 tabs

Article Commentary: Chelation Therapy for Mercury Poisoning

Directory of Open Access Journals (Sweden)

Rong Guan

2009-01-01

Full Text Available Chelation therapy has been the major treatment for heavy metal poisoning. Various chelating agents have been developed and tested for treatment of heavy metal intoxications, including mercury poisoning. It has been clearly shown that chelating agents could rescue the toxicity caused by heavy metal intoxication, but the potential preventive role of chelating agents against heavy metal poisoning has not been explored much. Recent paper by Siddiqi and colleagues has suggested a protective role of chelating agents against mercury poisoning, which provides a promising research direction for broader application of chelation therapy in prevention and treatment of mercury poisoning.

Zirconium and Titanium Propylene Polymerization Precatalysts Supported by a Fluxional C 2 -Symmetric Bis(anilide)pyridine Ligand

KAUST Repository

Tonks, Ian A.

2012-03-12

Titanium and zirconium complexes supported by a bis(anilide)pyridine ligand (NNN = pyridine-2,6-bis(N-mesitylanilide)) have been synthesized and crystallographically characterized. C 2-symmetric bis(dimethylamide) complexes were generated from aminolysis of M(NMe 2) 4 with the neutral, diprotonated NNN ligand or by salt metathesis of the dipotassium salt of NNN with M(NMe 2) 2Cl 2. In contrast to the case for previously reported pyridine bis(phenoxide) complexes, the ligand geometry of these complexes appears to be dictated by chelate ring strain rather than metal-ligand π bonding. The crystal structures of the five-coordinate dihalide complexes (NNN)MCl 2 (M = Ti, Zr) display a C 1-symmetric geometry with a stabilizing ipso interaction between the metal and the anilido ligand. Coordination of THF to (NNN)ZrCl 2 generates a six-coordinate C 2-symmetric complex. Facile antipode interconversion of the C 2 complexes, possibly via flat C 2v intermediates, has been investigated by variable-temperature 1H NMR spectroscopy for (NNN)MX 2(THF) n (M = Ti, Zr; X = NMe 2, Cl) and (NNN)Zr(CH 2Ph) 2. These complexes were tested as propylene polymerization precatalysts, with most complexes giving low to moderate activities (10 2-10 4 g/(mol h)) for the formation of stereoirregular polypropylene. © 2012 American Chemical Society.

Micronutrient metal speciation is driven by competitive organic chelation in grassland soils.

Science.gov (United States)

Boiteau, R.; Shaw, J. B.; Paša-Tolić, L.; Koppenaal, D.; Jansson, J.

2017-12-01

Many elements are scarcely soluble in aqueous conditions found in high pH environments, such as calcareous grassland soils, unless complexed to strong binding organic ligands. To overcome this limitation, some plants and microbes produce chelators that solubilize micronutrient metals such as Fe, Ni, Cu, and Zn from mineral phases. These complexes are taken up by organisms via specific membrane receptors, thereby differentially impacting the bioavailability of these metals to the plant and microbial community. Although the importance of these chelation strategies for individual organisms has been well established, little is known about which pathways coexist within rhizosphere microbiomes or how they interact and compete for metal binding. Identifying these metallo-organic species within natural ecosystems has remained a formidable analytical challenge due to the vast diversity of compounds and poorly defined metabolic processes in complex soil matrix. Herein, we employed recently developed liquid chromatography (LC) mass spectrometry (MS) methods to characterize the speciation of water-soluble dissolved trace elements (Fe, Ni, Cu, and Zn) from Kansas Prairie soil. Both plant and fungal chelators were identified, revealing compound-specific patterns of chelation to biologically essential metals. Numerous metabolites typically implicated in plant iron acquisition and homeostasis, including mugineic acids, deoxymugineic acid, nicotianamine, and hydroxynicotianamine, dominated the speciation of divalent metals such as Ni, Cu, and Zn (2-57 pmol / g soil). In contrast, the fungal siderophore ferricrocine bound comparatively more trivalent Fe (9pmol / g soil). These results define biochemical pathways that underpin the regulation of metals in the grassland rhizosphere. They also raise new questions about the competition of these compounds for metal binding and their bioavailability to different members of the rhizosphere population.

Identification of efficient chelating acids responsible for Cesium, Strontium and Barium complexes solubilization in mixed wastes

International Nuclear Information System (INIS)

Borai, E.H.

2007-01-01

The present paper is focused to characterize the available multi dentate ligand species and their metal ion complexes of cesium (Cs), strontium (Sr) and barium (Ba) formed with the parent chelators, complexing agents and its fragment products in mixed waste filtrate. The developed separation programs of different ligands by different mobile phases were based on the decrease of the effective charge of the anionic species in a differentiated way hence, the retention times on the stationary phases (AS-4A and AS-12A) are changed. Ion chromatographic (IC) analysis of the metal complexes showed that the carboxylic acids that are responsible for solubilizing Cs, Sr and Ba in the waste filtrate are NTA, Citrate and PDCA, respectively. Therefore, the predominant metal complexes in the filtrate at high ph are Cs (I)-NTA, Sr (IT)-Citrate and Ba (IT)-PDCA. Identification of the metal ion complexes responsible for solubilizing Cs, Sr and Ba was applied on the fresh and aged waste filtrates, to monitor their chemical behavior, which leads to increased control of the waste treatment process. Although, concentration measurements of both fresh and aged filtrates confirmed that the degradation process has occurred mainly due to a harsh chemical environment, the concentration of Cs(I), Sr(II) and Ba(II) increased slightly in the aged filterate compared with the fresh filtrate. This is due to the decomposition and/or degradation of their metal complexes and hence leads to free metal ion species in the filtrate. These observations indicate that the organic content of mixed waste filtrate is dynamic and need continuous analytical monitoring

Synthesis, structures, and electroluminescent properties of scandium N,O-chelated complexes toward near-white organic light-emitting diodes.

Science.gov (United States)

Katkova, Marina A; Balashova, Tatyana V; Ilichev, Vasilii A; Konev, Alexey N; Isachenkov, Nikolai A; Fukin, Georgy K; Ketkov, Sergey Yu; Bochkarev, Mikhail N

2010-06-07

Three members of a new class of electroluminescent, neutral, and monomeric scandium N,O-chelate complexes, namely, Sc(III)-tris-2-(2-benzoimidazol-2-yl)phenolate (1), Sc(III)-tris-2-(2-benzoxyazol-2-yl)phenolate (2), and Sc(III)-tris-2-(2-benzothiazol-2-yl)phenolate (3), have been prepared and X-ray characterized. DFT calculations have been performed. In contrast to the most frequently applied dual or multiple dopants in multilayer white OLED devices, all our simpler devices with the configuration of indium tin oxide/N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine/neat scandium complex/Yb exhibit close to near-white emission with a blue hue (CIE(x,y) = 0.2147, 0.2379) in the case of 1, a cyan hue (0.2702, 0.3524) in the case of 2, and a yellowish hue (0.3468; 0.4284) in the case of 3.

Lanthanide-binding peptides with two pendant aminodiacetate arms: impact of the sequence on chelation.

Science.gov (United States)

Niedźwiecka, Agnieszka; Cisnetti, Federico; Lebrun, Colette; Gateau, Christelle; Delangle, Pascale

2012-03-21

Lanthanide complexes with a series of hexapeptides-incorporating two unnatural chelating amino acids with aminodiacetate groups, Ada(1) and Ada(2)-have been examined in terms of their speciation, structure, stability and luminescence properties. Whereas Ada(2) acts as a tridentate donor in all cases, Ada(1) may act as a tetradentate donor thanks to the coordination of the amide carbonyl function assisted by the formation of a six-membered chelate ring. The position of the Ada(1) residue in the sequence is demonstrated to be critical for the lanthanide complex speciation and structure. Ada(1) promotes the coordination of the backbone amide function to afford a highly dehydrated Ln complex and an S-shape structure of the peptide backbone, only when found in position 2.

Iron chelating activity, phenol and flavonoid content of some ...

African Journals Online (AJOL)

STORAGESEVER

2008-09-17

Sep 17, 2008 ... require regular blood transfusions in order to improve both quality of ... fused red blood cells and the excess iron is deposited as ... potentiation of reactive oxygen species (ROS) and .... The percentage inhibition of ferrozine–Fe2+ complex formation was ... estimation of the chelating activity of the coexisting.

Gd (III) chelates adsorbed on TiO2 nanoparticles - promising MRI contrast agent

International Nuclear Information System (INIS)

Rehor, Ivan; Lukes, Ivan; Peters, Joop A.; Jirak, Daniel

2009-01-01

Full text: The project deals with a new contrast agent (CA) for magnetic resonance imaging (MRI). The CA consists of two main parts - diamagnetic core (TiO 2 nanoparticle) and Gd (III) chelates grafted on its surface. The presence of the nanoparticle core is responsible for significant increase of r1 millimolar relaxivity (which corresponds to the efficiency of the CA) due to the slowing down the rotation of the complex in solution. It also affects the biodistribution characteristics of the CA - the ability to penetrate through cell membranes is well known for nanoparticles, making them useful for cell labeling. The structure of the chelate is derived from DOTA ligand, whose Gd (III) complexes are commercially used as MRI CA in human medicine. The connection of the complex to the surface is realized via penylphosphonate, which is attached to the pendant arm of the ligand. Strong interaction of the phosphonate with the TiO 2 surface results in the full surface coverage. The complexation and MRI properties of Gd chelate were studied and exhibit analogy to the complexes of DOTA, The millimolar relaxivity (r1) of the Gd (III) complex significantly increases upon adsorption on the TiO 2 nanoparticles. PVA was added to the colloidal solutions of CA to stabilize them under biological conditions and such stabilized CA was utilized for MRI visualization of rat pancreatic islets (P1). The labeled islets were detected on MR images as hyperintense area and therefore our CA seems to be promising material for cellular MRI

[Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents

International Nuclear Information System (INIS)

1991-01-01

Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III)

[Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents

Energy Technology Data Exchange (ETDEWEB)

1991-12-31

Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III).

(Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents)

Energy Technology Data Exchange (ETDEWEB)

1991-01-01

Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III).

Titanium Insertion into CO Bonds in Anionic Ti-CO2 Complexes.

Science.gov (United States)

Dodson, Leah G; Thompson, Michael C; Weber, J Mathias

2018-03-22

We explore the structures of [Ti(CO 2 ) y ] - cluster anions using infrared photodissociation spectroscopy and quantum chemistry calculations. The existence of spectral signatures of metal carbonyl CO stretching modes shows that insertion of titanium atoms into C-O bonds represents an important reaction during the formation of these clusters. In addition to carbonyl groups, the infrared spectra show that the titanium center is coordinated to oxalato, carbonato, and oxo ligands, which form along with the metal carbonyls. The presence of a metal oxalato ligand promotes C-O bond insertion in these systems. These results highlight the affinity of titanium for C-O bond insertion processes.

Preparation and bioavailability of calcium-chelating peptide complex from tilapia skin hydrolysates.

Science.gov (United States)

Chen, Jun; Qiu, Xujian; Hao, Gengxin; Zhang, Meng; Weng, Wuyin

2017-11-01

With the continuous improvement in material life, the generation of fish by-products and the market demand for calcium supplements have been increasing in China. Therefore a calcium-chelating peptide complex (CPC) from tilapia skins was prepared and its effect on calcium (Ca)-deficient mice was investigated. The molecular weight distribution of CPC mainly ranged from 2000 to 180 Da, and its contents of complete amino acids and free amino acids were 85.30 and 8.67% (w/w) respectively. Scanning electron microscopy images and Fourier transform infrared data revealed that Ca crystals were bound with gelatin hydrolysates via interaction between Ca ions and NH/CN groups. When Ca-deficient mice were fed CPC and CaCO 3 respectively for 4 weeks, no significant differences in serum biochemistry or bone mineral density were found. However, the length, weight, Ca content and hydroxyproline content of the femur, Ca absorption and body weight gain of mice fed CPC were significantly higher than those of mice fed CaCO 3 . It is concluded that the prepared CPC could promote bone formation via better bioavailability of Ca and an increase in bone collagen. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

f-Element Ion Chelation in Highly Basic Media - Final Report

International Nuclear Information System (INIS)

Paine, R.T.

2000-01-01

A large body of data has been collected over the last fifty years on the chemical behavior of f-element ions. The ions undergo rapid hydrolysis reactions in neutral or basic aqueous solutions that produce poorly understood oxide-hydroxide species; therefore, most of the fundamental f-element solution chemistry has allowed synthetic and separations chemists to rationally design advanced organic chelating ligands useful for highly selective partitioning and separation of f-element ions from complex acidic solution matrices. These ligands and new examples under development allow for the safe use and treatment of solutions containing highly radioactive species. This DOE/EMSP project was undertaken to address the following fundamental objectives: (1) study the chemical speciation of Sr and lanthanide (Ln) ions in basic aqueous media containing classical counter anions found in waste matrices; (2) prepare pyridine N-oxide phosphonates and phosphonic acids that might act as selective chelator s for Ln ions in model basic pH waste streams; (3) study the binding of the new chelators toward Ln ions and (4) examine the utility of the chelators as decontamination and dissolution agents under basic solution conditions. The project has been successful in attacking selected aspects of the very difficult problems associated with basic pH solution f-element waste chemistry. In particular, the project has (1) shed additional light on the initial stages of Ln ion sol-gel-precipitate formulation under basic solution conditions; (2) generated new families of pyridine phosphonic acid chelators; (3) characterized the function of the chelators and (4) examined their utility as oxide-hydroxide dissolution agents. These findings have contributed significantly to an improved understanding of the behavior of Ln ions in basic media containing anions found in typical waste sludges as well as to the development of sludge dissolution agents. The new chelating reagents are easily made and could be

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

Science.gov (United States)

Schönherr, Jörg; Fernández, Victoria; Schreiber, Lukas

2005-06-01

Time courses of cuticular penetration of FeCl3 and Fe(III) complexes of citric acid, EDTA, EDDHA (Sequestrene 138Fe), imidodisuccinic acid (IDHA), and ligninsulfonic acid (Natrel) were studied using astomatous cuticular membranes (CMs) isolated from Populus x canescens leaves. At 100% relative humidity, the Fe(III) chelates disappeared exponentially with time from the surface of the CMs; that is, penetration was a first-order process that can be described using rate constants or half-times of penetration (t(1/2)). Half-times ranged from 20 to 30 h. At 90% humidity, penetration rates were insignificant with the exception of Natrel, for which t(1/2) amounted to 58 h. Rate constants were independent of temperature (15, 25, and 35 degrees C). Permeability decreased with increasing Fe chelate concentration (IDHA and EDTA). At 100% humidity, half-times measured with FeIDHA were 11 h (2 mmol L(-1)), 17 h (10 mmol L(-1)) and 36 h (20 mmol L(-1)), respectively. In the presence of FeEDTA, penetration of CaCl2 was slowed greatly. Half-times for penetration of CaCl2, which were 1.9 h in the absence of FeEDTA, rose to 3.12 h in the presence of an equimolar concentration of EDTA and 13.3 h when the FeEDTA concentration was doubled. Hence, Fe chelates reduced permeability of CMs to CaCl2 and to the Fe chelates themselves. It is suggested that Fe chelates reduced the size of aqueous pores. This view is supported by the fact that rate constants for calcium salts were about 5 times higher than for Fe chelates with the same molecular weights. Adding Tween 20 (5 g L(-1)) as a humectant did not increase permeability to FeIDHA at 90% humidity and below, while addition of glycine betaine did. Penetration of FeCl3 applied at 5 g L(-1) (pH 1.5) was not a first order process as rate constants decreased rapidly with time. Only 2% of the dose penetrated during the first 2 h and less than that in the subsequent 8 h. Recovery was only 70%. This was attributed to the formation of insoluble Fe

Thermodynamic stability and relaxation studies of small, triaza-macrocyclic Mn(II) chelates.

Science.gov (United States)

de Sá, Arsénio; Bonnet, Célia S; Geraldes, Carlos F G C; Tóth, Éva; Ferreira, Paula M T; André, João P

2013-04-07

Due to its favorable relaxometric properties, Mn(2+) is an appealing metal ion for magnetic resonance imaging (MRI) contrast agents. This paper reports the synthesis and characterization of three new triazadicarboxylate-type ligands and their Mn(2+) chelates (NODAHep, 1,4,7-triazacyclononane-1,4-diacetate-7-heptanil; NODABA, 1,4,7-triazacyclononane-1,4-diacetate-7-benzoic acid; and NODAHA, 1,4,7-triazacyclononane-1,4-diacetate-7-hexanoic acid). The protonation constants of the ligands and the stability constants of the chelates formed with Mn(2+) and the endogenous Zn(2+) ion have been determined by potentiometry. In overall, the thermodynamic stability of the chelates is lower than that of the corresponding NOTA analogues (NOTA = 1,4,7-triazacyclononane-1,4,7-triacetate), consistent with the decreased number of coordinating carboxylate groups. Variable temperature (1)H NMRD and (17)O NMR measurements have been performed on the paramagnetic chelates to provide information on the water exchange rates and the rotational dynamics. The values of the (17)O chemical shifts are consistent with the presence of one water molecule in the first coordination sphere of Mn(2+). The three complexes are in the slow to intermediate regime for the water exchange rate, and they all display relatively high rotational correlation times, which explain the relaxivity values between 4.7 and 5.8 mM(-1) s(-1) (20 MHz and 298 K). These relaxivities are higher than expected for Mn(2+) chelates of such size and comparable to those of small monohydrated Gd(3+) complexes. The amphiphilic [Mn(NODAHep)] forms micelles above 22 mM (its critical micellar concentration was determined by relaxometry and fluorescence), and interacts with HSA via its alkylic carbon chain providing a 60% relaxivity increase at 20 MHz due to a longer tumbling time.

Micronutrient metal speciation is controlled by competitive organic chelation in grassland soils

Energy Technology Data Exchange (ETDEWEB)

Boiteau, Rene M.; Shaw, Jared B.; Pasa Tolic, Ljiljana; Koppenaal, David W.; Jansson, Janet K.

2018-05-01

Many elements are scarcely soluble in aqueous conditions found in high pH environments, such as calcareous grassland soils, unless complexed to strong binding organic ligands. To overcome this limitation, some plants and microbes produce chelators that solubilize micronutrient metals such as Fe, Ni, Cu, and Zn from mineral phases. These complexes are taken up by organisms via specific membrane receptors, thereby differentially impacting the bioavailability of these metals to the plant and microbial community. Although the importance of these chelation strategies for individual organisms has been well established, little is known about which pathways coexist within rhizosphere microbiomes or how they interact and compete for metal binding. Identifying these metallo-organic species within natural ecosystems has remained a formidable analytical challenge due to the vast diversity of compounds and poorly defined metabolic processes in complex soil matrix. Herein, we employed recently developed liquid chromatography (LC) mass spectrometry (MS) methods to characterize the speciation of water-soluble dissolved trace elements (Fe, Ni, Cu, and Zn) from Kansas Prairie soil. Both plant and fungal chelators were identified, revealing compound-specific patterns of chelation to biologically essential metals. Numerous metabolites typically implicated in plant iron acquisition and homeostasis, including mugineic acids, deoxymugineic acid, nicotianamine, and hydroxynicotianamine, dominated the speciation of divalent metals such as Ni, Cu, and Zn (2-57 pmol / g soil). In contrast, the fungal siderophore ferricrocine bound comparatively more trivalent Fe (9pmol / g soil). These results define biochemical pathways that underpin the regulation of metals in the grassland rhizosphere. They also raise new questions about the competition of these compounds for metal binding and their bioavailability to different members of the rhizosphere population. Even small structural differences

Manganese(II) chelate contrast media

International Nuclear Information System (INIS)

Rocklage, S.M.; Quay, S.C.

1994-01-01

New chelate forming compounds for use as contrast media in NMR imaging are described. Especially mentioned are manganese(II) ion chelates of N,N' dipyridoxaldiamine, N,N' diacetic acid, and salts and esters thereof. 1 fig

Polyaminoquinoline iron chelators for vectorization of antiproliferative agents: design, synthesis, and validation.

Science.gov (United States)

Corcé, Vincent; Morin, Emmanuelle; Guihéneuf, Solène; Renault, Eric; Renaud, Stéphanie; Cannie, Isabelle; Tripier, Raphaël; Lima, Luís M P; Julienne, Karine; Gouin, Sébastien G; Loréal, Olivier; Deniaud, David; Gaboriau, François

2012-09-19

Iron chelation in tumoral cells has been reported as potentially useful during antitumoral treatment. Our aim was to develop new polyaminoquinoline iron chelators targeting tumoral cells. For this purpose, we designed, synthesized, and evaluated the biological activity of a new generation of iron chelators, which we named Quilamines, based on an 8-hydroxyquinoline (8-HQ) scaffold linked to linear polyamine vectors. These were designed to target tumor cells expressing an overactive polyamine transport system (PTS). A set of Quilamines bearing variable polyamine chains was designed and assessed for their ability to interact with iron. Quilamines were also screened for their cytostatic/cytotoxic effects and their selective uptake by the PTS in the CHO cell line. Our results show that both the 8-HQ moiety and the polyamine part participate in the iron coordination. HQ1-44, the most promising Quilamine identified, presents a homospermidine moiety and was shown to be highly taken up by the PTS and to display an efficient antiproliferative activity that occurred in the micromolar range. In addition, cytotoxicity was only observed at concentrations higher than 100 μM. We also demonstrated the high complexation capacity of HQ1-44 with iron while much weaker complexes were formed with other cations, indicative of a high selectivity. We applied the density functional theory to study the binding energy and the electronic structure of prototypical iron(III)-Quilamine complexes. On the basis of these calculations, Quilamine HQ1-44 is a strong tridentate ligand for iron(III) especially in the form of a 1:2 complex.

High-performance lithium-rich layered oxide materials: Effects of chelating agents on microstructure and electrochemical properties

International Nuclear Information System (INIS)

Li, Lingjun; Xu, Ming; Chen, Zhaoyong; Zhou, Xiang; Zhang, Qiaobao; Zhu, Huali; Wu, Chun; Zhang, Kaili

2015-01-01

The mechanisms and effects of three typical chelating agents, namely glucose, citric acid and sucrose on the sol-gel synthesis process, electrochemical degradation and structural evolution of 0.5Li 2 MnO 3 ·0.5LiNi 0.5 Co 0.2 Mn 0.3 O 2 (LLMO) materials are systematically compared for the first time. X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy analysis indicate that the sample synthesized from sucrose owns well structure, homogenous distribution, low Ni 3+ concentration and good surface structural stability during cycling, respectively. Electrochemical tests further prove that the LLMO material obtained from sucrose maintains 258.4 mAh g −1 with 94.8% capacity retention after 100 cycles at 0.2 C. The superior electrochemical performance can be ascribed to the exceptional complexing mechanism of sucrose, compared to those of the glucose and citric acid. Namely, one mole sucrose can be hydrolyzed into two different monosaccharides and further chelates three M (Li, Ni, Co and Mn) ions to form a more uniform ion-chelated matrix during sol-gel process. This discovery is an important step towards understanding the selection criterion of chelating agents for sol-gel method, that chelating agent with excellent complexing capability is beneficial to the distribution, structural stability and electrochemical properties of advanced lithium-rich layered materials

Decomposition rates of radiopharmaceutical indium chelates in serum

International Nuclear Information System (INIS)

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

1979-01-01

The rates at which six small aminopolycarboxylate chelates of trivalent 111 In and three protein-bound chelates of 111 In deliver indium to the serum protein transferrin have been studied in sterile human serum at pH 7.3, 37 deg C. Sterically hindered chelates containing a substituent on an ethylene carbon of EDTA decompose with rates in the range 0.03 to 0.11% per day - one to two orders of magnitude slower than other chelates. Only small differences are observed between rates of decomposition for low-molecular-weight chelates and for protein-bound chelates having analogous structures. (author)

Fluid extraction using carbon dioxide and organophosphorus chelating agents

Science.gov (United States)

Smart, Neil G.; Wai, Chien M.; Lin, Yuehe; Kwang, Yak Hwa

1998-01-01

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.

Isolation and identification of calcium-chelating peptides from Pacific cod skin gelatin and their binding properties with calcium.

Science.gov (United States)

Wu, Wenfei; Li, Bafang; Hou, Hu; Zhang, Hongwei; Zhao, Xue

2017-12-13

A calcium-chelating peptide is considered to have the ability to improve calcium absorption. In this study, Pacific cod skin gelatin hydrolysates treated with trypsin for 120 min exhibited higher calcium-chelating activity. Sequential chromatography, involving hydroxyapatite affinity chromatography and reversed phase high performance liquid chromatography, was used for the purification of calcium-chelating peptides. Two novel peptides with the typical characteristics of collagen were sequenced as GDKGESGEAGER and GEKGEGGHR based on LC-HRMS/MS, which showed a high affinity to calcium. Calcium-peptide complexation was further characterized by ESI-MS (MS and MS/MS) and FTIR spectroscopy. The results showed that the complexation of the two peptides with calcium was conducted mainly at the ratio of 1 : 1. The amino terminal group and the peptide bond of the peptide backbone as well as the amino group of the lysine side chain and the carboxylate of the glutamate side chain were the possible calcium binding sites for the two peptides. Meanwhile, several amino acid side chain groups, including the hydroxyl (Ser) and carboxylate (Asp) of GDKGESGEAGER and the imine (His) of GEKGEGGHR, were crucial in the complexation. The arginine residue in GEKGEGGHR also participated in the calcium coordination. Additionally, several active fragments with calcium-chelating activity were obtained using MS/MS spectra, including GDKGESGEAGE, GEAGER, GEK, EKG and KGE. This study suggests that gelatin-derived peptides have the potential to be used as a calcium-chelating ingredient to combat calcium deficiency.

Ce(III), Th(IV) and U(VI) chelates of alizarin viridine, alizarin heliotrope and alizarin maroon

International Nuclear Information System (INIS)

Idriss, K.A.; Issa, I.M.; Seleim, M.M.

1977-01-01

The complexes of 7,8-dihydroxy-1,4-di(2'-sulpho-4' methylanilino)-anthraquinone (alizarin viridine); 1,4-dihydroxy-2(2'-sulpho-4'-methylanilino)anthraquinone (alizarin heliotrope) and 3-amino-1,2-dihydroxyanthraquinone (alizarin maroon) with Ce(III), and U(VI) have been investigated using spectrophotometric and conductometric methods. The study revealed the formation of complexes having the metal: ligand ratios 1:1 and 1:2. The mean values of logβ (β being stability constant) for the different complexes are determined. The structure of the ligands in the solid chelates were studied by i.r. spectrophotmetry which showed that chelate formation takes place through the C=O and neighbouring OH group and leads to proton displacement. (author)

Titanium coordination compounds: from discrete metal complexes to metal–organic frameworks

KAUST Repository

Assi, Hala

2017-05-24

Owing to their promise in photocatalysis and optoelectronics, titanium based metal–organic frameworks (MOFs) are one of the most appealing classes of MOFs reported to date. Nevertheless, Ti-MOFs are still very scarce because of their challenging synthesis associated with a poor degree of control of their chemistry and crystallization. This review aims at giving an overview of the recent progress in this field focusing on the most relevant existing titanium coordination compounds as well as their promising photoredox properties. Not only Ti-MOFs but also Ti-oxo-clusters will be discussed and particular interest will be dedicated to highlight the different successful synthetic strategies allowing to overcome the still “unpredictable” reactivity of titanium ions, particularly to afford crystalline porous coordination polymers.

The characteristics of corrosion, radiation degradation and dissolution of titanium alloys

International Nuclear Information System (INIS)

Sung, K. W.; Na, J. W.; Choi, B. S.; Lee, D. J.; Chang, M. H.

2001-12-01

In order to establish the technical bases of water chemistry design requirement related titanium alloys, we investigated the characteristics of corrosion, activation, radiation degradation, radiation hydrogen embrittlement of titanium alloys and dissolution of titanium dioxide. Titanium alloys generally have high corrosion resistance. Corrosion product release from PT-7M and PT-3V titanium alloy surface for 18 months of operation is negligible, and the corrosion penetration for about 30 years is about 1 μm, while the corrosion rates is not higher than one third of that of austenitic steel. Titanium only converts into Sc-46 with 85 day halflife after neutron irradiation, and its radioactivity is not higher than one thousandth of that produced from nickel. Therefore, under the condition without any neutron irradiation, the radiation damage of titanium alloys would have no problem. Titanium dioxide, that protects the metals from the corrosion, has retrograde solubility in neutral solutions. It does not form any complexes with ligands such as ammonia, but Ti(IV) gets more stable by complexing with water molecules. In conclusion, it is estimated that titanium alloys such as PT-7M would be applicable to steam generator materials

From chelating precursors to La0.05Sr0.95CoO3-y oxide

International Nuclear Information System (INIS)

Hong, L.; Guo, F.; Lin, J.

1999-01-01

Several La 0.05 Sr 0.95 CoO 3-y (LSCO-95) powders were synthesized by means of a chelated complex-based precursor approach, which involved pyrolysis of chelating precursors and subsequent calcination of the resulting oxides. This paper focuses on the coordination effects of the precursors on the formation of the crystalline phases of the LSCO-95 oxide, showing that when the precursor is composed of EDTA-metal complexes, the perovskite-type oxide LSCO-95, an electronic-ionic mixed conducting ceramic material, can be achieved. In contrast, those LSCO-95 powders obtained initially from the pyrolysis of the precursors containing other coordination ligands possess only the undesirable hexagonal structure

Effects of iron(III)chelates on the solubility of heavy metals in calcareous soils

Energy Technology Data Exchange (ETDEWEB)

Ylivainio, Kari, E-mail: kari.ylivainio@mtt.f [Department of Applied Chemistry and Microbiology, FIN-00014 University of Helsinki (Finland)

2010-10-15

In this study I evaluated the effects of complexing agents on the solubility of heavy metals in an incubation experiment up to 56 days when complexing agents were applied as Fe-chelates (Fe-EDDS(S,S), Fe-EDDS(mix), Fe-EDTA and Fe-EDDHA) on calcareous soils at a level sufficient to correct Fe chlorosis (0.1 mmol kg{sup -1}). Of these ligands, EDDHA was the most efficient in keeping Fe in water-soluble form, and EDDS increased the solubility of Cu and Zn most, and only EDTA increased the solubility of Cd and Pb. EDTA increased the solubility of Ni steadily during the incubation period, equalling about 5-8% of the added EDTA concentration. [S,S]-EDDS was biodegraded within 56 days, whereas EDDS(mix) was less biodegradable. Ni-chelates were the most recalcitrant against biodegradation. The study shows that even a moderate input of chelates to soil increases the solubility of toxic heavy metals and their risk of leaching. - When correcting Fe chlorosis Fe-EDDS causes lower environmental concern than Fe-EDTA.

Effects of iron(III)chelates on the solubility of heavy metals in calcareous soils

International Nuclear Information System (INIS)

Ylivainio, Kari

2010-01-01

In this study I evaluated the effects of complexing agents on the solubility of heavy metals in an incubation experiment up to 56 days when complexing agents were applied as Fe-chelates (Fe-EDDS(S,S), Fe-EDDS(mix), Fe-EDTA and Fe-EDDHA) on calcareous soils at a level sufficient to correct Fe chlorosis (0.1 mmol kg -1 ). Of these ligands, EDDHA was the most efficient in keeping Fe in water-soluble form, and EDDS increased the solubility of Cu and Zn most, and only EDTA increased the solubility of Cd and Pb. EDTA increased the solubility of Ni steadily during the incubation period, equalling about 5-8% of the added EDTA concentration. [S,S]-EDDS was biodegraded within 56 days, whereas EDDS(mix) was less biodegradable. Ni-chelates were the most recalcitrant against biodegradation. The study shows that even a moderate input of chelates to soil increases the solubility of toxic heavy metals and their risk of leaching. - When correcting Fe chlorosis Fe-EDDS causes lower environmental concern than Fe-EDTA.

Effects of iron(III)chelates on the solubility of heavy metals in calcareous soils.

Science.gov (United States)

Ylivainio, Kari

2010-10-01

In this study I evaluated the effects of complexing agents on the solubility of heavy metals in an incubation experiment up to 56 days when complexing agents were applied as Fe-chelates (Fe-EDDS(S,S), Fe-EDDS(mix), Fe-EDTA and Fe-EDDHA) on calcareous soils at a level sufficient to correct Fe chlorosis (0.1 mmol kg(-1)). Of these ligands, EDDHA was the most efficient in keeping Fe in water-soluble form, and EDDS increased the solubility of Cu and Zn most, and only EDTA increased the solubility of Cd and Pb. EDTA increased the solubility of Ni steadily during the incubation period, equalling about 5-8% of the added EDTA concentration. [S,S]-EDDS was biodegraded within 56 days, whereas EDDS(mix) was less biodegradable. Ni-chelates were the most recalcitrant against biodegradation. The study shows that even a moderate input of chelates to soil increases the solubility of toxic heavy metals and their risk of leaching. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Solvent extraction of anionic chelate complexes of lanthanum(III), europium(III), lutetium(III), scandium(III), and indium(III) with 2-thenoyltrifluoroacetone as ion-pairs with tetrabutylammonium ions

International Nuclear Information System (INIS)

Noro, Junji; Sekine, Tatsuya.

1992-01-01

The solvent extraction of lanthanum(III), europium(III), lutetium(III), scandium(III), and indium(III) in 0.1 mol dm -3 sodium nitrate solutions with 2-thenoyltrifluoroacetone (Htta) in the absence and presence of tetrabutylammonium ions (tba + ) into carbon tetrachloride was measured. The extraction of lanthanum(III), europium(III), and lutetium(III) was greatly enhanced by the addition of tba + ; this could be explained in terms of the extraction of a ternary complex, M(tta) 4 - tba + . However, the extractions of scandium(III) and indium(III) were nearly the same when tba + was added. The data were treated on the basis of the formation equilibrium of the ternary complex from the neutral chelate, M(tta) 3 , with the extracted ion-pairs of the reagents, tta - tba + , in the organic phase. It was concluded that the degree of association of M(tta) 3 with the ion-pair, tta - tba + , is greater in the order La(tta) 3 ≅ Eu(tta) 3 > Lu(tta) 3 , or that the stability of the ternary complex in the organic phase is higher in the order La(tta) 4 - tba + ≅ Eu(tta) 4 - tba + > Lu(tta) 4 - tba + . This is similar to those of adduct metal chelates of Htta with tributylphosphate (TBP) in synergistic extraction systems. (author)

Relationship among chelator adherence, change in chelators, and quality of life in thalassemia.

Science.gov (United States)

Trachtenberg, Felicia L; Gerstenberger, Eric; Xu, Yan; Mednick, Lauren; Sobota, Amy; Ware, Hannah; Thompson, Alexis A; Neufeld, Ellis J; Yamashita, Robert

2014-10-01

Thalassemia, a chronic blood disease, necessitates life-long adherence to blood transfusions and chelation therapy to reduce iron overload. We examine stability of health-related quality of life (HRQOL) in thalassemia and adherence to chelation therapy over time, especially after changes in chelator choice. Thalassemia Longitudinal Cohort participants in the USA, UK, and Canada completed the SF-36v2 (ages 14+) and the PF-28 CHQ (parents of children health status) at baseline who made a single change in chelator, but declined among participants with multiple changes and/or high iron burden (worse health status). Mental health improved among participants with lower iron burden, but iron overload was negatively associated with social functioning. Adherence did not significantly change over follow-up except for an increase after a change from deferoxamine (DFO) infusion to oral deferasirox (p = 0.03). Predictors of lower adherence for adults/adolescents at follow-up included side effects, smoking, younger age, problems preparing DFO, increased number of days per week DFO prescribed, and lower physical quality of life . Strategies to balance medical needs with family, work, and personal life may assist in adherence.

Titanium

Science.gov (United States)

Woodruff, Laurel G.; Bedinger, George M.; Piatak, Nadine M.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

2017-12-19

Titanium is a mineral commodity that is essential to the smooth functioning of modern industrial economies. Most of the titanium produced is refined into titanium dioxide, which has a high refractive index and is thus able to impart a durable white color to paint, paper, plastic, rubber, and wallboard. Because of their high strength-to-weight ratio and corrosion resistance, titanium metal and titanium metal alloys are used in the aerospace industry as well as for welding rod coatings, biological implants, and consumer goods.Ilmenite and rutile are currently the principal titanium-bearing ore minerals, although other minerals, including anatase, perovskite, and titanomagnetite, could have economic importance in the future. Ilmenite is currently being mined from two large magmatic deposits hosted in rocks of Proterozoic-age anorthosite plutonic suites. Most rutile and nearly one-half of the ilmenite produced are from heavy-mineral alluvial, fluvial, and eolian deposits. Titanium-bearing minerals occur in diverse geologic settings, but many of the known deposits are currently subeconomic for titanium because of complications related to the mineralogy or because of the presence of trace contaminants that can compromise the pigment production process.Global production of titanium minerals is currently dominated by Australia, Canada, Norway, and South Africa; additional amounts are produced in Brazil, India, Madagascar, Mozambique, Sierra Leone, and Sri Lanka. The United States accounts for about 4 percent of the total world production of titanium minerals and is heavily dependent on imports of titanium mineral concentrates to meet its domestic needs.Titanium occurs only in silicate or oxide minerals and never in sulfide minerals. Environmental considerations for titanium mining are related to waste rock disposal and the impact of trace constituents on water quality. Because titanium is generally inert in the environment, human health risks from titanium and titanium

Synthesis and structure of the first fullerene complex of titanium Cp{sub 2}Ti({eta}{sup 2}-C{sub 60})

Energy Technology Data Exchange (ETDEWEB)

Burlakov, V.V.; Usatov, A.V.; Lyssenko, K.A.; Antipin, M.Yu.; Novikov, Yu.N.; Shur, V.B. [Russian Academy of Sciences, Moscow (Russian Federation). A.N. Nesmeyanov Inst. of Organoelement Compounds

1999-11-01

The first fullerene complex of titanium Cp{sub 2}Ti({eta}{sup 2}-C{sub 60}) has been synthesized by reaction of the bis(trimethylsilyl)-acetylene complex of titanocene Cp{sub 2}Ti({eta}{sup 2}-Me{sub 3}SiC{sub 2}SiMe{sub 3}) with an equimolar amount of fullerene-60 in toluene at room temperature under argon. An X-ray diffraction study of the complex has shown that it has the structure of a titanacyclopropane derivative. (orig.)

Investigation on the influence of metal ion impurities on the complexation behavior of generator produced {sup 90}Y with bifunctional chelators

Energy Technology Data Exchange (ETDEWEB)

Pandey, Usha; Gamre, Naresh; Dash, Ashutosh [Isotope Applications and Radiopharmaceuticals Division, Bhabha Atomic Research Centre, Mumbai (India)

2014-05-01

The {sup 90}Sr/ {sup 90}Y generator is the exclusive source of 'no carrier added' {sup 90}Y for targeted therapy. However, the concomitant presence of trace metals diminishes the complexation of {sup 90}Y with bifunctional chelators (BFCs). A systematic investigation was performed to evaluate the influence of trace metals on the complexation of {sup 90}Y (from an electrochemical generator) with BFCs such as p-SCN-Bn-PCTA, p-SCN-Bn-DTPA and p-SCN-Bn-DOTA. Our study indicates that while p-SCN-Bn-DTPA was least affected by most of the trace metals studied, p-SCN-Bn-PCTA was most sensitive to their presence and hence could be the ligand of choice for assessing the chemical purity of generator derived {sup 90}Y. (author)

Radiolysis of titanium potassium oxalate in aqueous solution. [. gamma. rays

Energy Technology Data Exchange (ETDEWEB)

Bundo, Y; Ono, I [Industrial Research Inst. of Kanagawa Prefecture, Yokohama (Japan); Ogawa, T

1975-01-01

The dissolution state of titanium potassium oxalate in aqueous solution is different according to the pH. The yellowish brown titanium complex produced by the reaction of titanium potassium oxalate and hydrogen peroxide seems to be different in its structure according to the pH. Considering these points, gamma-ray irradiation was carried out on the sample by dissolving titanium potassium oxalate in purified water under the conditions of oxygen saturation and nitrogen saturation, and the relation between irradiation dose and the production of titanium complex was determined. On the basis of the experimental result, the mechanism of forming hydrogen peroxide was presumed. The radiation source used was 2,000 Ci of /sup 60/Co. For photometric analysis, a 139 type photoelectric spectrophotometer of Hitachi Ltd. was used. From the experimental results, in neutral water, titanium potassium oxalate exists in the state that two oxalic acid ions are coordinated to titanyl ion, while in case of the pH lowered by the addition of sulfuric acid, it can exist in the state that one oxalic acid ion is coordinated to titanyl ion. The yield of hydrogen peroxide produced by irradiating titanium potassium oxalate aqueous solution with gamma-ray is the sum of the molecular product from water and the radiolysis product from titanium potassium oxalate.

Nature of the bifunctional chelating agent used for radioimmunotherapy with yttrium-88 monoclonal antibodies: critical factors in determining in vivo survival and organ toxicity

Energy Technology Data Exchange (ETDEWEB)

Kozak, R.W.; Raubitschek, A.; Mirzadeh, S.; Brechbiel, M.W.; Junghaus, R.; Gansow, O.A.; Waldmann, T.A. (Center for Biologics Evaluation and Research, FDA, Bethesda, MD (USA))

1989-05-15

One factor that is critical to the potential effectiveness of radioimmunotherapy is the design of radiometal-chelated antibodies that will be stable in vivo. Stability in vivo depends on the condition that both the chelate linkage and radiolabeling procedures not alter antibody specificity and biodistribution. In addition, synthesis and selection of the chelating agent is critical for each radiometal in order to prevent inappropriate release of the radiometal in vivo. In the present study, we compare the in vivo stability of seven radioimmunoconjugates that use different polyaminocarboxylate chelating agents to complex yttrium-88 to the mouse anti-human interleukin-2 receptor monoclonal antibody, anti-Tac. Chelate linkage and radiolabeling procedures did not alter the immunospecificity of anti-Tac. In order to assess whether yttrium was inappropriately released from the chelate-coupled antibody in vivo, iodine-131-labeled and yttrium-88 chelate-coupled antibodies were simultaneously administered to the same animals to correlate the decline in yttrium and radioiodinated antibody activity. The four stable yttrium-88 chelate-coupled antibodies studied displayed similar iodine-131 and yttrium-88 activity, indicating minimal elution of yttrium-88 from the complex. In contrast, the unstable yttrium-88 chelate-coupled antibodies had serum yttrium-88 activities that declined much more rapidly than their iodine-131 activities, suggesting loss of the radiolabel yttrium-88 from the chelate. Furthermore, high rates of yttrium-88 elution correlated with deposition in bone. Four chelating agents emerged as promising immunotherapeutic reagents: isothiocyanate benzyl DTPA and its derivatives 1B3M, MX, and 1M3B.

Comments on chelation therapy

International Nuclear Information System (INIS)

Wrenn, M.E.

1981-01-01

The primary purpose of actinide chelation is to decrease the risk from radiation-induced cancer. While occupational exposures in the past have mainly involved low specific activity 239 Pu, future exposures will increasingly involve high specific activity plutonium, americium, and curium - all of which clear more rapidly from the lung. This will tend to shift the cancer risk from lung to bone and liver. Although therapy with Ca- or Zn-DTPA rapidly removes 241 Am from the canine, the sub-human primate, and the human liver, improved methods for removal from bone and lung are needed. DTPA can remove 241 Am more easily from the growing skeleton of a child than from the mature skeleton of an adult. Investigators at Karlsruhe are developing chelation agents for oral administration and are investigating the reduction in local dose to bone resulting from chelation therapy

STUDY ON THE KINETICS OF POLYMERIZATION OF MMA BY COPPER（Ⅱ） CHELATING RESINS

Institute of Scientific and Technical Information of China (English)

WangHongzuo; JiangYuanzhang; 等

1993-01-01

The polymerization of MMA initiated by copper(Ⅱ） chelating resins/CCl4 system was studied.From the kinetic data,the kinetic equation of polymerization can be expressed as Rp=Ke-56400/RT[MMA]1.57[CCl4]m[RESIN-Cu]0.18 where m:3-4.5,when[CCl4] 0.1-6.93M.The free radical polymerization mechanism is proposed.The primary radicals are formed by the process of complexation-chlorine transformation among the copper(Ⅱ) chelating resin,CCl4 and methacrylate.

IR, UV-Vis, magnetic and thermal characterization of chelates of some catecholamines and 4-aminoantipyrine with Fe(III) and Cu(II)

Science.gov (United States)

Mohamed, Gehad G.; Zayed, M. A.; El-Dien, F. A. Nour; El-Nahas, Reham G.

2004-07-01

The dopamine derivatives participate in the regulation of wide variety of physiological functions in the human body and in medication life. Increase and/or decrease in the concentration of dopamine in human body reflect an indication for diseases such as Schizophrenia and/or Parkinson diseases. α-Methyldopa (α-MD) in tablets is used in medication of hypertension. The Fe(III) and Cu(II) chelates with coupled products of adrenaline hydrogen tartarate (AHT), levodopa (LD), α-MD and carbidopa (CD) with 4-aminoantipyrine (4-AAP) are prepared and characterized. Different physico-chemical methods like IR, magnetic and UV-Vis spectra are used to investigate the structure of these chelates. Fe(III) form 1:2 (M:catecholamines) chelates while Cu(II) form 1:1 chelates. Catecholamines behave as a bidentate mono- or dibasic ligands in binding to the metal ions. IR spectra show that the catecholamines are coordinated to the metal ions in a bidentate manner with O,O donor sites of the phenolic - OH. Magnetic moment measurements reveal the presence of Fe(III) chelates in octahedral geometry while the Cu(II) chelates are square planar. The thermal decomposition of Fe(III) and Cu(II) complexes is studied using thermogravimetric (TGA) and differential thermal analysis (DTA) techniques. The water molecules are removed in the first step followed immediately by decomposition of the ligand molecules. The activation thermodynamic parameters, such as, energy of activation, enthalpy, entropy and free energy change of the complexes are evaluated and the relative thermal stability of the complexes are discussed.

The intra-annular acylamide chelate-coordinated compound: The keto-tautomer of metal (II) milrinone complex

Science.gov (United States)

Gong, Yun; Liu, Jinzhi; Tang, Wang; Hu, Changwen

2008-03-01

In the presence of N, N'-dimethyllformamide (DMF), two isostructural metal (II)-milrinone complexes formulated as M(C 12H 8N 3O) 2 (M = Co 1 and Ni 2) have been synthesized and characterized by elemental analysis, IR, TG and single crystal X-ray diffraction. The two compounds crystallize in the tetragonal system, chiral space group P4 32 12. They exhibit similar two dimensional (2D) square grid-like framework, in which milrinone acts as a ditopic ligand with its terminal pyridine and intra-annular acylamide groups covalently bridging different metal centers. The intra-annular acylamide ligand shows a chelate-coordinated mode. Compounds 1 and 2 are stable under 200 °C. Compound 3 formulated as (C 12H 9N 3O) 4·H 2O was obtained in the presence of water, the water molecule in the structure leads to the racemization of compound 3 and it crystallizes in the monoclinic system, non-chiral space group P2 1/ c. Milrinone exhibits a keto-form in the three compounds and compounds 1- 3 exhibit different photoluminescence properties.

Opportunities in the electrowinning of molten titanium from titanium dioxide

CSIR Research Space (South Africa)

Van Vuuren, DS

2005-10-01

Full Text Available used, the following forms of titanium are produced: titanium sponge, sintered electrode sponge, powder, molten titanium, electroplated titanium, hydride powder, and vapor-phase depos- ited titanium. Comparing the economics of alter- native...-up for producing titanium via the Kroll process is approximately as follows: ilmenite ($0.27/kg titanium sponge); titanium slag ($0.75/kg titanium sponge); TiCl4 ($3.09/kg titanium sponge); titanium sponge raw materials costs ($5.50/kg titanium sponge); total...

Overview of current chelation practices

Directory of Open Access Journals (Sweden)

Y. Aydinok

2011-12-01

Full Text Available Deferoxamine (DFO is reference standard therapy for transfusional iron overload since the 1980s. Although it is a highly effective iron chelator, the compliance problem to subcutaneous administration of DFO remains as the major problem. The oral chelator Deferiprone (DFP has no marketing licence in North America, however, it has been licensed in India since 1994 and the European Union (EU granted marketing approval for DFP in 1999, specifically for patients with thalassemia major when DFO is inadequate, intolerable or unacceptable. There are still limited data available on the use of DFP in children between 6 and 10 years of age, and no data on DFP use in children under 6 years of age. Subsequently the oral chelator Deferasirox (DFX was approved by FDA and EMA for the treatment of patients with transfusional iron overload -older than 2 years of age- as first line therapy, in 2005 and 2006 respectively. The primary objective of iron chelation is to maintain body iron at safe levels at all times but once iron is accumulated, the objective of iron chelation is to reduce tissue iron to safe levels which is a slow process. The chelation regimen, dose and frequency of administration, of the chelator(s are mainly determined based on body iron burden, presence of myocardial iron and the transfusional iron loading rate. A proper monitoring of chelation is of importance for measuring the response rate to a particular regimen and providing dose adjustments to enhance chelation efficacy and to avoid toxicity. Efficacy of a chelation regimen may exhibit individual variability resulting from factors such as absorbtion and metabolism of the chelator. Tolerability and compliance are also individual variables effecting the response to chelation. Understanding of advantages and limitations of chelators, accurately determining chelation needs of patients with iron overload and designing individualized chelation regimens with less toxicity but optimum efficacy

Characterization and thermogravimetric analysis of lanthanide hexafluoroacetylacetone chelates.

Science.gov (United States)

Shahbazi, Shayan; Stratz, S Adam; Auxier, John D; Hanson, Daniel E; Marsh, Matthew L; Hall, Howard L

2017-01-01

This work reports the thermodynamic characterizations of organometallic species as a vehicle for the rapid separation of volatile nuclear fission products via gas chromatography due to differences in adsorption enthalpy. Because adsorption and sublimation thermodynamics are linearly correlated, there is considerable motivation to determine sublimation enthalpies. A method of isothermal thermogravimetric analysis, TGA-MS and melting point analysis are employed on thirteen lanthanide 1,1,1,5,5,5-hexafluoroacetylacetone complexes to determine sublimation enthalpies. An empirical correlation is used to estimate adsorption enthalpies of lanthanide complexes on a quartz column from the sublimation data. Additionally, four chelates are characterized by SC-XRD, elemental analysis, FTIR and NMR.

Spectroscopy, modeling and computation of metal chelate solubility in supercritical CO2

International Nuclear Information System (INIS)

Brennecke, J.F.; Stadtherr, M.A.

1999-01-01

The overall objectives of this project were to gain a fundamental understanding of the solubility and phase behavior of metal chelates in supercritical CO 2 . Extraction with CO 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 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 2 and CO 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 2 and CO 2 /co-contaminant mixtures. Thus, they can now design and optimize processes to extract metals from solid matrices using supercritical CO 2 , as an alternative to hazardous organic solvents that create their own environmental problems, even while helping in metals decontamination

Fluoride ion recognition by chelating and cationic boranes.

Science.gov (United States)

Hudnall, Todd W; Chiu, Ching-Wen; Gabbaï, François P

2009-02-17

Because of the ubiquity of fluoride ions and their potential toxicity at high doses, researchers would like to design receptors that selectively detect this anion. Fluoride is found in drinking water, toothpaste, and osteoporosis drugs. In addition, fluoride ions also can be detected as an indicator of uranium enrichment (via hydrolysis of UF(6)) or of the chemical warfare agent sarin, which releases the ion upon hydrolysis. However, because of its high hydration enthalpy, the fluoride anion is one of the most challenging targets for anion recognition. Among the various recognition strategies that are available, researchers have focused a great deal of attention on Lewis acidic boron compounds. These molecules typically interact with fluoride anions to form the corresponding fluoroborate species. In the case of simple triarylboranes, the fluoroborates are formed in organic solvents but not in water. To overcome this limitation, this Account examines various methods we have pursued to increase the fluoride-binding properties of boron-based receptors. We first considered the use of bifunctional boranes, which chelate the fluoride anion, such as 1,8-diborylnaphthalenes or heteronuclear 1-boryl-8-mercurio-naphthalenes. In these molecules, the neighboring Lewis acidic atoms can cooperatively interact with the anionic guest. Although the fluoride binding constants of the bifunctional compounds exceed those of neutral monofunctional boranes by several orders of magnitude, the incompatibility of these systems with aqueous media limits their utility. More recently, we have examined simple triarylboranes whose ligands are decorated by cationic ammonium or phosphonium groups. These cationic groups increase the electrophilic character of these boranes, and unlike their neutral analogs, they are able to complex fluoride in aqueous media. We have also considered cationic boranes, which form chelate complexes with fluoride anions. Our work demonstrates that Coulombic and chelate

Effect of Ionic and Chelate Assisted Hexavalent Chromium on Mung Bean Seedlings (Vigna radiata L. wilczek. var k-851 During Seedling Growth

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Mohanty, Monalisa

2013-04-01

Full Text Available The effect of Cr+6 with and without chelating agents were assessed in mung bean seedlings grown hydroponically. It was noted that the growth parameters showed a declining trend with increasing Cr+6 concentrations without chelate application. Among the seedlings grown with chelated chromium complexes, Cr+6–DTPA (10µM showed highest growth rate of roots as well as shoots. At higher concentration of Chromium i.e. Cr+6 (100µM, there exhibited high chlorophyll content in mung bean leaves where the seedlings showed stunted growth. The seedlings treated without and with chelated chromium complexes showed increased proline content as compared to control. The enzymatic study showed that, the catalase activity was maximum in shoots as compared to roots and the reverse is true in the case of peroxidase activity i.e. the roots showed higher value than that of the shoots.

Biological behaviour of some 67Ga and 64Cu chelates

International Nuclear Information System (INIS)

Leonovicova, T.; Angelis, B.; Cifka, J.; Cifkova, I.

1984-01-01

Chelates of 67 Ga and 64 Cu with iminodiacetic acid (IDA) and its two phenyl derivatives as well as with nitrilotriacetic acid (NTA) and benzylnitrilotriacetic acid (BNTA) were prepared. All the chelates were found to be negatively charged. A study of the biological distribution of these chelates in rats during time intervals of 3 to 180 min showed that the chelate of 67 Ga with IDA substituted at a phenyl by a hydrophobic substituent is excreted by the kidneys into the urine at a much higher rate than the IDA chelate of 67 Ga. The excretion of NTA and BNTA chelates of 67 Ga is the opposite. Blood clearance of 64 Cu chelates is more rapid than that of 67 Ga chelates. Chelates of 64 Cu accumulate in the liver and with the bile are slowly excreted into the intestines, urinary excretion is negligible. (author)

Preclinical evaluation of somatostatin analogs bearing two macrocyclic chelators for high specific activity labeling with radiometals

International Nuclear Information System (INIS)

Storch, D.; Schmitt, J.S.; Waldherr, C.; Maecke, H.R.; Waser, B.; Reubi, J.C.

2007-01-01

Radiometallated analogues of the regulatory peptide somatostatin are of interest in the in vivo localization and targeted radiotherapy of somatostatin receptor-overexpressing tumors. An important aspect of their use in vivo is a fast and efficient labeling (complexation) protocol for radiometals along with a high specific activity. We describe in this manuscript synthetic methods for the coupling of two chelators (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid = DOTA) to the bioactive peptide [Tyr 3 ,Thr 8 ]-octreotide (TATE) in order to increase the specific activity (radioactivity in Bq per mole peptide). The full chelator-linker-peptide conjugate was assembled on solid support using standard Fmoc chemistry. Two DOTA-chelators were linked to the peptide using lysine or N,N'-bis(3-aminopropyl)-glycine (Apg); in addition, pentasarcosine (Sar 5 ) was used as a spacer between the chelators and the peptide to probe its influence on biology and pharmacology. Complexation rates with In 3+ and Y 3+ salts and the corresponding radiometals were high, the bis-DOTA-derivatives showed higher complexation rates and gave higher specific activity than DOTA-TATE. Pharmacological and biological data of the complexed molecules did not show significant differences if compared to the parent peptide [ 111/nat In-DOTA]-TATE except for [( 111/nat In-DOTA) 2 -Apg]-TATE which showed a lower binding affinity and rate of internalization into tumor cells. The biodistribution of [( 111/nat In-DOTA)-Lys( 111/nat In-DOTA)]-TATE in the rat tumor model (AR4-2J) showed a high and specific (as shown by a blocking experiment) tracer uptake in somatostatin receptor-positive tissue but a lower tumor uptake compared to [ 111/nat In-DOTA]-TATE. (orig.)

Zinc chelates as new activators for sulphur vulcanization of acrylonitrile-butadiene elastomer

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2009-04-01

Full Text Available The goal of this work was to apply several zinc chelates as activators for sulphur vulcanization of acrylonitrilebutadiene elastomer (NBR, in order to find alternatives for the conventionally used zinc oxide. In this article, we discuss the effects of different zinc complexes on the cure characteristics, crosslinks distribution in the elastomer network and mechanical properties of acrylonitrile-butadiene rubber. Zinc chelates seem to be good substitutes for zinc oxide as activators for sulphur vulcanization of NBR rubber, without detrimental effects on the crosslinking process and physical properties of the obtained vulcanizates. Moreover, application of zinc complexes allows to reduce the amount of zinc ions in rubber compounds by 40% compared to conventionally crosslinked vulcanizates with zinc oxide. It is a very important ecological goal since zinc oxide is classified as toxic to aquatic species and its amount in rubber products must be reduced below 2.5% at least. From a technological point of view it is a very important challenge.

Synthesis, spectroscopic and catalytic properties of some new boron hybrid molecule derivatives by BF2 and BPh2 chelation

Science.gov (United States)

Kilic, Ahmet; Alcay, Ferhat; Aydemir, Murat; Durgun, Mustafa; Keles, Armagan; Baysal, Akın

2015-05-01

A new series of Schiff base ligands (L1-L3) and their corresponding fluorine/phenyl boron hybrid complexes [LnBF2] and [LnBPh2] (n = 1, 2 or 3) have been synthesized and well characterized by both analytical and spectroscopic methods. The Schiff base ligands and their corresponding fluorine/phenyl boron hybrid complexes have been characterized by NMR (1H, 13C and 19F), FT-IR, UV-Vis, LC-MS, and fluorescence spectroscopy as well as melting point and elemental analysis. The fluorescence efficiencies of phenyl chelate complexes are greatly red-shifted compared to those of the fluorine chelate analogs based on the same ligands, presumably due to the large steric hindrance and hard π → π∗ transition of the diphenyl boron chelation, which can effectively prevent molecular aggregation. The boron hybrid complexes were applied to the transfer hydrogenation of acetophenone derivatives to 1-phenylethanol derivatives in the presence of 2-propanol as the hydrogen source. The catalytic studies showed that boron hybrid complexes are good catalytic precursors for transfer hydrogenation of aromatic ketones in 0.1 M iso-PrOH solution. Also, we have found that both steric and electronic factors have a significant impact on the catalytic properties of this class of molecules.

Phosphinic acid functionalized polyazacycloalkane chelators for radiodiagnostics and radiotherapeutics: unique characteristics and applications.

Science.gov (United States)

Notni, Johannes; Šimeček, Jakub; Wester, Hans-Jürgen

2014-06-01

Given the wide application of positron emission tomography (PET), positron-emitting metal radionuclides have received much attention recently. Of these, gallium-68 has become particularly popular, as it is the only PET nuclide commercially available from radionuclide generators, therefore allowing local production of PET radiotracers independent of an on-site cyclotron. Hence, interest in optimized bifunctional chelators for the elaboration of (68) Ga-labeled bioconjugates has been rekindled as well, resulting in the development of improved triazacyclononane-triphosphinate (TRAP) ligand structures. The most remarkable features of these ligands are unparalleled selectivity for Ga(III) , rapid Ga(III) complexation kinetics, extraordinarily high thermodynamic stability, and kinetic inertness of the respective Ga(III) chelates. As a result, TRAP chelators exhibit very favorable (68) Ga-labeling properties. Based on the scaffolds NOPO (1,4,7-triazacyclononane-1,4-bis[methylene(hydroxymethyl)phosphinic acid]-7-[methylene(2-carboxyethyl)phosphinic acid]) and TRAP-Pr, tailored for convenient preparation of (68) Ga-labeled monomeric and multimeric bioconjugates, a variety of novel (68) Ga radiopharmaceuticals have been synthesized. These include bisphosphonates, somatostatin receptor ligands, prostate-specific membrane antigen (PSMA)-targeting peptides, and cyclic RGD pentapeptides, for in vivo PET imaging of bone, neuroendocrine tumors, prostate cancer, and integrin expression, respectively. Furthermore, TRAP-based (68) Ga-labeled gadolinium(III) complexes have been proposed as bimodal probes for PET/MRI, and a cyclen-based analogue of TRAP-Pr has been suggested for the elaboration of targeted radiotherapeutics comprising radiolanthanide ions. Thus, polyazacycloalkane-based polyphosphinic acid chelators are a powerful toolbox for pharmaceutical research, particularly for the development of (68) Ga radiopharmaceuticals. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chelate-assisted phytoextraction of lead from contaminated soils

Energy Technology Data Exchange (ETDEWEB)

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

1999-12-01

Phytoextraction, a remediation strategy for lead (Pb)-contaminated soils that removes soil Pb through plant uptake and harvest, may be enhanced by use of synthetic chelates. The authors evaluated Pb desorption from four contaminated soils by seven chelates (CDTA, DTPA, EDDHA, EFTA, HEDTA, HEIDA, and NTA) at three rates. The three most effective chelates (CDTA, DTPA, and HEDTA) were used in greenhouse studies with an uncontaminated soil and a Pb-contaminated soil to determine the effect of chelate type and rate on growth, Pb uptake, and plant elemental composition. Lead desorption varied with chelate and soil and increased with chelate rate, averaging 948 mg Pb kg{sup {minus}1} at the 20 mmol kg{sup {minus}1} rate vs. 28 mg Pb kg{sup {minus}1} by the control. The general ranking of chelate effectiveness, based on total Pb desorbed, was HEDTA > CDTA > DTPA > EGTA > HEIDA > EDDHA {approximately} NTA. Plant uptake of Pb from the contaminated soil was enhanced by CDTA, DTPA, and HEDTA, but with even the most effective treatment (corn, high CDTA rate), the amount of Pb extracted by plants was rather low. Lead extractable by the Toxicity Characteristic Leaching Procedure (TCLP) was increased from 9 mg L{sup {minus}1} in the control to from 47 to 174 mg L{sup {minus}1} in soils treated with 20 mmol kg{sup {minus}1} CDTA or DTPA and chelates generally caused a shift in Pb from resistant to more soluble chemical fractions.

Cell Attachment Following Instrumentation with Titanium and Plastic Instruments, Diode Laser, and Titanium Brush on Titanium, Titanium-Zirconium, and Zirconia Surfaces.

Science.gov (United States)

Lang, Melissa S; Cerutis, D Roselyn; Miyamoto, Takanari; Nunn, Martha E

2016-01-01

The aim of this study was to evaluate the surface characteristics and gingival fibroblast adhesion of disks composed of implant and abutment materials following brief and repeated instrumentation with instruments commonly used in procedures for implant maintenance, stage-two implant surgery, and periimplantitis treatment. One hundred twenty disks (40 titanium, 40 titaniumzirconium, 40 zirconia) were grouped into treatment categories of instrumentation by plastic curette, titanium curette, diode microlaser, rotary titanium brush, and no treatment. Twenty strokes were applied to half of the disks in the plastic and titanium curette treatment categories, while half of the disks received 100 strokes each to simulate implant maintenance occurring on a repetitive basis. Following analysis of the disks by optical laser profilometry, disks were cultured with human gingival fibroblasts. Cell counts were conducted from scanning electron microscopy (SEM) images. Differences in surface roughness across all instruments tested for zirconia disks were negligible, while both titanium disks and titaniumzirconium disks showed large differences in surface roughness across the spectrum of instruments tested. The rotary titanium brush and the titanium curette yielded the greatest overall mean surface roughness, while the plastic curette yielded the lowest mean surface roughness. The greatest mean cell counts for each disk type were as follows: titanium disks with plastic curettes, titanium-zirconium disks with titanium curettes, and zirconia disks with the diode microlaser. Repeated instrumentation did not result in cumulative changes in surface roughness of implant materials made of titanium, titanium-zirconium, or zirconia. Instrumentation with plastic implant curettes on titanium and zirconia surfaces appeared to be more favorable than titanium implant curettes in terms of gingival fibroblast attachment on these surfaces.

[Susceptibility of enterococci to natural and synthetic iron chelators].

Science.gov (United States)

Lisiecki, Paweł; Mikucki, Jerzy

2002-01-01

A total of 79 strains of enterococci belonging to 10 species were tested for susceptibility to natural and synthetic iron chelators. All strains produced siderophores. These enterococci were susceptible to three synthetic iron chelators only: 8-hydroxyquinoline, disodium versenate (EDTA) and o-phenanthroline. They were resistant to all other synthetic chelators: ethylenediamine-di(o-hydroxyphenylacetic acid) (EDDHA), nitrilotriacetate, 2,2'-bipiridyl, salicylic acid, 8-hydroxy-5-sulphonic acid and to all natural chelators: ovotransferrine, human apotransferrine, horse apoferritine, desferrioxamine B, ferrichrome and rhodotorulic acid. The relations between susceptibility/resistance, iron assimilation and structure and stability constants of iron chelators were discussed.

Modeling the chelation of As(III) in lewisite by dithiols using density functional theory and solvent-assisted proton exchange.

Science.gov (United States)

Harper, Lenora K; Bayse, Craig A

2015-12-01

Dithiols such as British anti-lewisite (BAL, rac-2,3-dimercaptopropanol) are an important class of antidotes for the blister agent lewisite (trans-2-chlorovinyldichloroarsine) and, more generally, are chelating agents for arsenic and other toxic metals. The reaction of the vicinal thiols of BAL with lewisite through the chelation of the As(III) center has been modeled using density functional theory (DFT) and solvent-assisted proton exchange (SAPE), a microsolvation method that uses a network of water molecules to mimic the role of bulk solvent in models of aqueous phase chemical reactions. The small activation barriers for the stepwise SN2-type nucleophilic attack of BAL on lewisite (0.7-4.9kcal/mol) are consistent with the favorable leaving group properties of the chloride and the affinity of As(III) for soft sulfur nucleophiles. Small, but insignificant, differences in activation barriers were found for the initial attack of the primary versus secondary thiol of BAL and the R vs S enantiomer. An examination of the relative stability of various dithiol-lewisite complexes shows that ethanedithiols like BAL form the most favorable chelation complexes because the angles formed in five-membered ring are most consistent with the hybridization of As(III). More obtuse S-As-S angles are required for larger chelate rings, but internal As⋯N or As⋯O interactions can enhance the stability of moderate-sized rings. The low barriers for lewisite detoxification by BAL and the greater stability of the chelation complexes of small dithiols are consistent with the rapid reversal of toxicity demonstrated in previously reported animal models. Copyright © 2015 Elsevier Inc. All rights reserved.

Chelation: Harnessing and Enhancing Heavy Metal Detoxification—A Review

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Margaret E. Sears

2013-01-01

Full Text Available 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.

Chelating agents in pharmacology, toxicology and therapeutics

International Nuclear Information System (INIS)

1988-01-01

The proceedings contain 71 abstracts of papers. Fourteen abstracts were inputted in INIS. The topics covered include: the effects of chelating agents on the retention of 63 Ni, 109 Cd, 203 Hg, 144 Ce, 95 Nb and the excretion of 210 Po, 63 Ni, 48 V, 239 Pu, 241 Am, 54 Mn; the applications of tracer techniques for studies of the efficacy of chelation therapy in patients with heart and brain disorders; and the treatment of metal poisoning with chelating agents. (J.P.)

Succinate, iron chelation, and monovalent cations affect the transformation efficiency of Acinetobacter baylyi ATCC 33305 during growth in complex media.

Science.gov (United States)

Leong, Colleen G; Boyd, Caroline M; Roush, Kaleb S; Tenente, Ricardo; Lang, Kristine M; Lostroh, C Phoebe

2017-10-01

Natural transformation is the acquisition of new genetic material via the uptake of exogenous DNA by competent bacteria. Acinetobacter baylyi is model for natural transformation. Here we focus on the natural transformation of A. baylyi ATCC 33305 grown in complex media and seek environmental conditions that appreciably affect transformation efficiency. We find that the transformation efficiency for A. baylyi is a resilient characteristic that remains high under most conditions tested. We do find several distinct conditions that alter natural transformation efficiency including addition of succinate, Fe 2+ (ferrous) iron chelation, and substitution of sodium ions with potassium ones. These distinct conditions could be useful to fine tune transformation efficiency for researchers using A. baylyi as a model organism to study natural transformation.

Extraction of bivalent vanadium as its pyridine thiocyanate complex and separation from uranium, titanium, chromium and aluminium

International Nuclear Information System (INIS)

Yatirajam, V.; Arya, S.P.

1975-01-01

A simple method is described for the extraction of V(II) as its pyridine thiocyanate complex. Vanadate is reduced to V(II) in 1 to 2 N sulphuric acid by zinc amalgam. Thiocyanate and pyridine are added, the solution is adjusted to pH 5.2 to 5.5 and the complex extracted with chloroform. The vanadium is back-extracted with peroxide solution. Zinc from the reductant accompanies the vanadium but alkali and alkaline earth metal ions, titanium, uranium, chromium and aluminium are separated, besides those ions reduced to the elements by zinc amalgam. The method takes about 20 min and is applicable to microgram as well as milligram amounts of vanadium. (author)

Role of chelates in magnetic resonance imaging studies

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Tripathi Laxmi

2009-01-01

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

Chelation of Cu(II, Zn(II, and Fe(II by Tannin Constituents of Selected Edible Nuts

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Magdalena Karamać

2009-12-01

Full Text Available The tannin fractions isolated from hazelnuts, walnuts and almonds were characterised by colorimetric assays and by an SE-HPLC technique. The complexation of Cu(II and Zn(II was determined by the reaction with tetramethylmurexide, whereas for Fe(II, ferrozine was employed. The walnut tannins exhibited a significantly weaker reaction with the vanillin/HCl reagent than hazelnut and almond tannins, but the protein precipitation capacity of the walnut fraction was high. The SE-HPLC chromatogram of the tannin fraction from hazelnuts revealed the presence of oligomers with higher molecular weights compared to that of almonds. Copper ions were most effectively chelated by the constituents of the tannin fractions of hazelnuts, walnuts and almonds. At a 0.2 mg/assay addition level, the walnut tannins complexed almost 100% Cu(II. The Fe(II complexation capacities of the tannin fractions of walnuts and hazelnuts were weaker in comparison to that of the almond tannin fraction, which at a 2.5 mg/assay addition level, bound Fe(II by ~90%. The capacity to chelate Zn(II was quite varied for the different nut tannin fractions: almond tannins bound as much as 84% Zn(II, whereas the value for walnut tannins was only 8.7%; and for hazelnut tannins, no Zn(II chelation took place at the levels tested.

Comparison of the octadentate bifunctional chelator DFO*-pPhe-NCS and the clinically used hexadentate bifunctional chelator DFO-pPhe-NCS for {sup 89}Zr-immuno-PET

Energy Technology Data Exchange (ETDEWEB)

Vugts, Danielle J.; Klaver, Chris; Sewing, Claudia; Poot, Alex J.; Adamzek, Kevin; Visser, Gerard W.M.; Dongen, Guus A.M.S. van [VU University Medical Center, Department of Radiology and Nuclear Medicine, Amsterdam (Netherlands); Huegli, Seraina; Mari, Cristina; Gasser, Gilles [University of Zurich, Department of Chemistry, Zurich (Switzerland); Valverde, Ibai E. [University of Basel Hospital, Division of Radiopharmaceutical Chemistry, Basel (Switzerland); Mindt, Thomas L. [Institute of Pharmaceutical Sciences, ETH Zurich, Zurich (Switzerland); General Hospital of Vienna, Ludwig Boltzmann Institute for Applied Diagnostics, Vienna (Austria)

2017-02-15

All clinical {sup 89}Zr-immuno-PET studies are currently performed with the chelator desferrioxamine (DFO). This chelator provides hexadentate coordination to zirconium, leaving two coordination sites available for coordination with, e.g., water molecules, which are relatively labile ligands. The unsaturated coordination of DFO to zirconium has been suggested to result in impaired stability of the complex in vivo and consequently in unwanted bone uptake of {sup 89}Zr. Aiming at clinical improvements, we report here on a bifunctional isothiocyanate variant of the octadentate chelator DFO* and the in vitro and in vivo comparison of its {sup 89}Zr-DFO*-mAb complex with {sup 89}Zr-DFO-mAb. The bifunctional chelator DFO*-pPhe-NCS was prepared from previously reported DFO* and p-phenylenediisothiocyanate. Subsequently, trastuzumab was conjugated with either DFO*-pPhe-NCS or commercial DFO-pPhe-NCS and radiolabeled with Zr-89 according to published procedures. In vitro stability experiments were carried out in saline, a histidine/sucrose buffer, and blood serum. The in vivo performance of the chelators was compared in N87 tumor-bearing mice by biodistribution studies and PET imaging. In 0.9 % NaCl {sup 89}Zr-DFO*-trastuzumab was more stable than {sup 89}Zr-DFO-trastuzumab; after 72 h incubation at 2-8 C 95 % and 58 % intact tracer were left, respectively, while in a histidine-sucrose buffer no difference was observed, both products were ≥ 92 % intact. In vivo uptake at 144 h post injection (p.i.) in tumors, blood, and most normal organs was similar for both conjugates, except for skin, liver, spleen, ileum, and bone. Tumor uptake was 32.59 ± 11.95 and 29.06 ± 8.66 % ID/g for {sup 89}Zr-DFO*-trastuzumab and {sup 89}Zr-DFO-trastuzumab, respectively. The bone uptake was significantly lower for {sup 89}Zr-DFO*-trastuzumab compared to {sup 89}Zr-DFO-trastuzumab. At 144 h p.i. for {sup 89}Zr-DFO*-trastuzumab and {sup 89}Zr-DFO-trastuzumab, the uptake in sternum was 0.92 �

Obligatory reduction of ferric chelates in iron uptake by soybeans.

Science.gov (United States)

Chaney, R L; Brown, J C; Tiffin, L O

1972-08-01

The contrasting Fe(2+) and Fe(3+) chelating properties of the synthetic chelators ethylenediaminedi (o-hydroxyphenylacetate) (EDDHA) and 4,7-di(4-phenylsulfonate)-1, 10-phenanthroline (bathophenanthrolinedisulfonate) (BPDS) were used to determine the valence form of Fe absorbed by soybean roots supplied with Fe(3+)-chelates. EDDHA binds Fe(3+) strongly, but Fe(2+) weakly; BPDS binds Fe(2+) strongly but Fe(3+) weakly. Addition of an excess of BPDS to nutrient solutions containing Fe(3+)-chelates inhibited soybean Fe uptake-translocation by 99+%; [Fe(II) (BPDS)(3)](4-) accumulated in the nutrient solution. The addition of EDDHA caused little or no inhibition. These results were observed with topped and intact soybeans. Thus, separation and absorption of Fe from Fe(3+)-chelates appear to require reduction of Fe(3+)-chelate to Fe(2+)-chelate at the root, with Fe(2+) being the principal form of Fe absorbed by soybean.

Physicochemical, antioxidant, DNA cleaving properties and antimicrobial activity of fisetin-copper chelates.

Science.gov (United States)

Łodyga-Chruscińska, Elżbieta; Pilo, Maria; Zucca, Antonio; Garribba, Eugenio; Klewicka, Elżbieta; Rowińska-Żyrek, Magdalena; Symonowicz, Marzena; Chrusciński, Longin; Cheshchevik, Vitalij T

2018-03-01

Fisetin (3,3',4',7-tetrahydroxyflavone) metal chelates are of interest as this plant polyphenol has revealed broad prospects for its use as natural medicine in the treatment of various diseases. Metal interactions may change or enhance fisetin biological properties so understanding fisetin metal chelation is important for its application not only in medicine but also as a food additive in nutritional supplements. This work was aimed to determine and characterize copper complexes formed in different pH range at applying various metal/ligand ratios. Fisetin and Cu(II)-fisetin complexes were characterized by potentiometric titrations, UV-Vis (Ultraviolet-visible spectroscopy), EPR, ESI-MS, FTIR and cyclic voltammetry. Their effects on DNA were investigated by using circular dichroism, spectrofluorimetry and gel electrophoresis methods. The copper complex with the ratio of Cu(II)/fisetin 1/2 exhibited significant DNA cleavage activity, followed by complete degradation of DNA. The influence of copper(II) ions on antioxidant activity of fisetin in vitro has been studied using DPPH, ABTS and mitochondrial assays. The results have pointed out that fisetin or copper complexes can behave both as antioxidants or pro-oxidants. Antimicrobial activity of the compounds has been investigated towards several bacteria and fungi. The copper complex of Cu(II)/fisetin 1/2 ratio showed higher antagonistic activity against bacteria comparing to the ligand and it revealed a promising antifungal activity. Copyright © 2017 Elsevier Inc. All rights reserved.

Development of iron chelators for Cooley's anemia. Final report

International Nuclear Information System (INIS)

Crosby, W.H.; Green, R.

1982-01-01

Iron chelators were screened in an iron-loaded rat model using selective radioiron probes. In all experiments, chelators D and F, in that order, induced significant loss of radioiron compared with controls. However, use of chelator D was associated with side effects, and resulted in the death of some animals. There was some evidence that chelator A also caused iron loss significantly greater than controls. Chelators B, C and E were without apparent enhancing effect on radioiron excretion. This was a blind study and the compounds used were A - 2,3-Dihydroxybenzoic acid; B - N,N1-Dimethyladipohydroxamic acid; C - DL-Phenylalanine hydroxamic acid; D - Ethylenediamine-N,N1-bis(2-hydroxphenylacetic acid); E - Propionohydroxamic acid; and F - Deferrioxamine B

Analysis of x-ray diffraction pattern and complex plane impedance plot of polypyrrole/titanium dioxide nanocomposite: A simulation study

Science.gov (United States)

Ravikiran, Y. T.; Vijaya Kumari, S. C.

2013-06-01

To innovate the properties of Polypyrrole/Titanium dioxide (PPy/TiO2) nanocomposite further, it has been synthesized by chemical polymerization technique. The nanostructure and monoclinic phase of the prepared composite have been confirmed by simulating the X-ray diffraction pattern (XRD). Also, complex plane impedance plot of the composite has been simulated to find equivalent resistance capacitance circuit (RC circuit) and numerical values of R and C have been predicted.

Production of chelating agents by Pseudomonas aeruginosa grown in the presence of thorium and uranium

International Nuclear Information System (INIS)

Premuzic, E.T.; Lin, M.; Francis, A.J.; Schubert, J.

1986-01-01

Chelating agents produced by microorganisms enhance the dissolution of iron increasing the mobility and bioavailability of the metal. Since some similarities exist in the biological behavior of ferric, thorium and uranyl ions, microorganisms resistant to these metals and which grow in their presence may produce sequestering agents of Th and U, and other metals in a manner similar to the complexation of iron by siderophores. The ability of P. aeruginosa to elaborate sequestering agents in medium containing thorium or uranium salts was tested. Uranium has a stronger inhibitory effect on growth of the organism than thorium at similar concentrations. Analyses of the culture media have shown, that relative to the control, and under the experimental conditions used, the microorganisms have produced several new chelating agents for thorium and uranium. Extracts containing these chelating agents have been tested for their decorporation potential. In vitro mouse liver bioassay and in vivo mouse toxicity tests indicate that their efficiency is comparable to DTPA and DFOA and that they are virtually non-toxic to mice. The bacterially produced compounds resemble, but are not identical to the known iron chelating siderophores isolated from microorganisms. Some of their chemical properties are also discussed. (author)

Labeling of antibodies with a 67Ga-phenolic aminocarboxylic acid chelate. Pt. 1

International Nuclear Information System (INIS)

Schuhmacher, J.; Matys, R.; Hauser, H.; Maier-Borst, W.; Matzku, S.

1986-01-01

As a chelating agent for labeling antibodies (Abs) with metallic radionuclides, a propionic acid substituted ethylenediamine N, N'-di-[(o-hydroxyphenyl) acetic acid] (P-EDDHA), which tighly complexes 67 Ga, was synthetized. The 67 Ga-P-EDDHA chelate was coupled in aqueous solution to IgG at a molar ratio of 1:1 via carbodiimide. The average coupling yield was 15%. A specific activity of 4 mCi/mg IgG could be obtained with commercially supplied 67 Ga. In vitro stability was evaluated in human serum at 37 0 C and showed a half-life of about 120 h for the release of 67 Ga from the labeled Ab during the initial phase of incubation. This in vitro halflife is similar to that measured for 111 In-DTPA labeled Abs. Because of the high stability of the 67 Ga-P-EDDHA chelate, the in vivo formation of radioactive lebeled transferrin by transchelation, as described for 111 In-DTPA labeled Abs, should, however, be reduced by this labeling technique. (orig.)

Cold Spraying of Armstrong Process Titanium Powder for Additive Manufacturing

Science.gov (United States)

MacDonald, D.; Fernández, R.; Delloro, F.; Jodoin, B.

2017-04-01

Titanium parts are ideally suited for aerospace applications due to their unique combination of high specific strength and excellent corrosion resistance. However, titanium as bulk material is expensive and challenging/costly to machine. Production of complex titanium parts through additive manufacturing looks promising, but there are still many barriers to overcome before reaching mainstream commercialization. The cold gas dynamic spraying process offers the potential for additive manufacturing of large titanium parts due to its reduced reactive environment, its simplicity to operate, and the high deposition rates it offers. A few challenges are to be addressed before the additive manufacturing potential of titanium by cold gas dynamic spraying can be reached. In particular, it is known that titanium is easy to deposit by cold gas dynamic spraying, but the deposits produced are usually porous when nitrogen is used as the carrier gas. In this work, a method to manufacture low-porosity titanium components at high deposition efficiencies is revealed. The components are produced by combining low-pressure cold spray using nitrogen as the carrier gas with low-cost titanium powder produced using the Armstrong process. The microstructure and mechanical properties of additive manufactured titanium components are investigated.

Photostability of solutions of rare earth chelates in organic solvents and polymers

International Nuclear Information System (INIS)

Karasev, V.E.; Mirochnik, A.G.; Lysun, T.V.; Vovna, V.I.

1990-01-01

Consideration is given to results of comparative study of photochemical properties of rare erath chelate complexes (adducts of rare earth β-diketonates with triphenylphosphine oxide, hexamethylphosphotriamide, phenanthroline) in organic solvents and polymers. Effect of excitation conditions, composition, solvent, nature of ligand and rare earth ion on photolysis rate was investigated. 9 refs.; 2 figs.; 4 tabs

Characterization and Sintering of Armstrong Process Titanium Powder

Science.gov (United States)

Xu, Xiaoyan; Nash, Philip; Mangabhai, Damien

2017-04-01

Titanium and titanium alloys have a high strength to weight ratio and good corrosion resistance but also need longer time and have a higher cost on machining. Powder metallurgy offers a viable approach to produce near net-shape complex components with little or no machining. The Armstrong titanium powders are produced by direct reduction of TiCl4 vapor with liquid sodium, a process which has a relatively low cost. This paper presents a systematic research on powder characterization, mechanical properties, and sintering behavior and of Armstrong process powder metallurgy, and also discusses the sodium issue, and the advantages and disadvantages of Armstrong process powders.

Synthesis and chemical characterization of the novel agronomically relevant pentadentate chelate 2-(2-((2-hydroxybenzyl)amino)ethylamino)-2-(2-hydroxyphenyl)acetic acid (DCHA).

Science.gov (United States)

López-Rayo, Sandra; Hernández, Diana; Lucena, Juan J; Escudero, Rosa; Gómez-Gallego, Mar; Sierra, Miguel A

2010-07-14

Iron chelates analogous to o,o-EDDHA/Fe(3+) are the fertilizers chosen to treat iron chlorosis in plants growing on calcareous soil. The isomer o,p-EDDHA/Fe(3+) presents less stability but faster assimilation by the plant than o,o-EDDHA/Fe(3+), because only five coordinating groups are able to complex Fe(3+). The new chelating agent 2-(2-((2-hydroxybenzyl)amino)ethylamino)-2-(2-hydroxyphenyl)acetic acid (DCHA) has been synthesized to obtain an iron fertilizer with intermediate stability between o,o-EDDHA/Fe(3+) and o,p-EDDHA/Fe(3+) and with fast assimilation. Its synthesis has been done starting from phenol, N-acetylethylendiamine, glyoxylic acid, and NaOH in a three-step sequence. The purity of the DCHA chelating agent, its protonation, and Ca(2+), Mg(2+), Fe(3+), and Cu(2+) stability constants, together with its ability to maintain iron in solution in different agronomic conditions, have been determined. The results indicate that the chelate DCHA/Fe(3+) has intermediate stability between those of o,o-EDDHA/Fe(3+) and o,p-EDDHA/Fe(3+) complexes and that it is capable of maintaining the Fe(3+) in agronomic conditions. This new chelating agent may be effective in correcting iron chlorosis in plants.

Titanium ; dream new material

International Nuclear Information System (INIS)

Lee, Yong Tae; Kim Seung Eon; Heoon, Yong Taek; Jung, Hui Won

2001-11-01

The contents of this book are history of Titanium, present situation of Titanium industry, property of Titanium alloy, types of it, development of new alloy of Titanium smelting of Titanium, cast of Titanium and heat treatment of Titanium, Titanium alloy for plane, car parts, biological health care, and sport leisure and daily life, prospect, and Titanium industrial development of Titanium in China.

Chelate-Modified Fenton Reaction for the Degradation of Trichloroethylene in Aqueous and Two-Phase Systems

Energy Technology Data Exchange (ETDEWEB)

Lewis, Scott [Univ of KY, dept of chemical and materials engineering; lynch, Andrew [Univ of KY, dept of chemical and materials engineering; Bachas, Leonidas [Univ of KY, Dept of Chemistry; hampson, Steve [Univ of KY Center for Applied Energy Research - KY Research Consortium of Energy and Environment; Ormsbee, Lindelle [Univ of KY Center for Applied Energy Research - KY Research Consortium of Energy and Environment; Bhattacharyya, Dibakar [Univ of KY, dept of chemical and materials engineering

2008-06-01

The Standard Fenton reaction has been used for In-Situ Chemical Oxidation (ISCO) of toxic organics in groundwater. However, it requires low pH operating conditions, and thus has limitations for in situ applications. In addition, hydroxyl radicals are rapidly consumed by hydroxyl scavengers found in the subsurface. These problems are alleviated through the chelate-modified Fenton (hydroxyl radical) reaction, which includes the addition of nontoxic chelate (L) such as citrate or gluconic acid. This chelate allows the reaction to take place at bear neutral pH and control hydrogen peroxide consumption by binding to Fe(II), forming an FeL complex. The chelate also binds to Fe(III), preventing its precipitation as ferric hydroxide and thus prevents problems associated with injection well plugging. The rate of TCE dechlorination in chelate-modified Fenton systems is a function of pH, H2O2 concentration, and FE:L ratio. The primary objective of this research is to model and apply this process to the destruction of trichloroethylene (TCE) present in both the aqueous and organic (in the form of droplets) phases. Experimentation proved the chelate-modified Fenton reaction effectively dechlorinates TCE in both the aqueous and organic phases at near-neutral pH. Other focuses of this work include determining the effect of [L]:[Fe] ratios on H2O2 and TCE degradation as well as reusability of the FE citrate solution under repeated H2O2 injections. Generalized models were developed to predict the concentration of TCE in the aqueous phase and TCE droplet radius as a function of time using established hydroxyl radial kinetics and mass transfer relationships.

Ultrahighly Dispersed Titanium Oxide on Silica : Effect of Precursors on the Structure and Photocatalysis

OpenAIRE

Yoshida , S.; Takenaka , S.; Tanaka , T.; Funabiki , T.

1997-01-01

The effect of precursor on the dispersion and catalytic performance of titanium oxide supported on silica has ben investigated. The catalysts were prepared by a simple impregnation method with three kinds of titanium complexes of different ligands (bis(isopropyato)-bis(pivaroylmethanato) : DPM, acetylacetonato : ACAC, tetrakis(isopropylato) : IPRO) with the aim of preparing ultrahighly dispersed titanium oxide on silica. The XAFS study revealed that titanium species in the catalyst prepared f...

Application of Box-Behnken design in the optimization of catalytic behavior of a new mixed chelate of copper (II) complex in chemiluminescence reaction of luminol

International Nuclear Information System (INIS)

Khajvand, Tahereh; Chaichi, Mohammad Javad; Nazari, OmLeila; Golchoubian, Hamid

2011-01-01

In this work, we observed an enhancement of chemiluminescence (CL) emission of luminol when a new mixed chelate of copper complex (N-(2-(2-aminoethylamino)ethyl)-1H-pyrrole-2-carboxamide-Cu(II)) was mixed with a solution containing luminol in methanol/water. The Box-Behnken design matrix and response surface methodology (RSM) have been applied to design the experiments to evaluate the interactive effects of the three most important operating variables-luminol (10 -4 -10 -2 M), fluorescein (10 -5 -10 -3 M) and hydrogen peroxide (1-3 M) concentrations on the CL emission of luminol. The total 15 experiments were conducted in the present study towards the construction of a quadratic model. Independent variables luminol and hydrogen peroxide have significant value P F less than 0.0500 indicate that model terms are significant for the CL emission of luminol. The regression equation coefficients were calculated and the data fitted to a second-order polynomial equation for CL emission of luminol. The new introduced inorganic catalyst of luminol CL reaction can be effect more than that of the common ones such as potassium hexacyanoferrate (III) and copper (II) acetate. - Research highlights: → In this study we introduce a new mixed chelate of copper complex as a catalyst of luminol chemiluminescence (CL) reaction. → The copper complex (N-(2-(2-aminoethylamino)ethyl)-1H-pyrrole-2-carboxamide-Cu(II)) catalyst luminol reaction more than that of copper acetate and potassium hexacyanoferrate (III). → The Box-Behnken design matrix and response surface methodology are used for prediction of CL intensity of luminol. → There are good correlation between experimental and expected CL intensity that predicted by the theoretical model. → Fluorescein used as a fluorescer in the luminol CL reaction in presence of the new catalyst.

Mesoporous organosilica nanotubes containing a chelating ligand in their walls

Energy Technology Data Exchange (ETDEWEB)

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

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.

Features of rare earth element (3) complexing

International Nuclear Information System (INIS)

Martynenko, L.I.

1991-01-01

Reasons for nonobeyance to the regularity of tetrad ''W'' effect of rare earth chelate complex compounds are discussed in the review. The concept of metal-ligand ionic bond in rare earth complexes is put in the basis of the consideration. From this viewpoint mutual influence of ligands in lower, higher, polynuclear and different-ligand complexes, formed by the ligands of low, medium and high denticity, is discussed. Problems of intermolecular interaction of complexes with different structure are considered in relation to problems of variation of chelate volatility and selectivity in the processes of sublimation and precipitation

New thermo-sensitive chelating surfactants for selective solvent-free extraction of uranyl nitrate

International Nuclear Information System (INIS)

Prevost, S.; Larpent, C.; Testard, F.; Coulombeau, H.; Baczko, K.; Berthon, L.; Desvaux, H.; Madic, C.; Zemb, T.

2004-01-01

Functional surfactants were synthesised by grafting a chelating group (amino-acid residue) to the tip of a poly-ethoxylated nonionic surfactant chain (C i E j : C i H 2i +1(OCH 2 CH 2 ) j OH)) or in a branched position. C i E j nonionic surfactants are known to be thermo-reversible and to exhibit a clouding phenomenon associated to phase separation of micelles. The functional surfactants retain both surface-active properties, characteristic thermo-reversible behaviour and have efficient complexing properties toward uranyl. In the presence of uranyl nitrate, small micelles are formed at ambient temperature and the de-mixing leads to a separation of the target ion trapped by the functional surfactant (cloud point extraction). Those surfactants are more efficient than mixture of classical C i E j and complexing agent solubilized in the micelles. This reveals a synergistic effect of the covalent bond between the chelating group and the nonionic surfactant C i E j . This paper presents a systematic study of the extraction and aggregation properties and the influence of the nature of the ions. (authors)

New method for studying the efficiency of chelating agents of the polyamine acid series for internal decontamination; Methode nouvelle d'etude de l'efficacite des chelateurs de la serie des acides polyamines pour la decontamination interne

Energy Technology Data Exchange (ETDEWEB)

Lafuma, J; Nenot, J C; Morin, M [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1968-07-01

We followed the biological fate of a complex formed on one side with either a rare earth (cerium-144) or a transuranium element (plutonium-239), and on the other side with a chelating agent of the polyamino acid series (EDTA, BAETA, DTPA, TTHA). This method allowed to study: 1 - the in vivo stability of the various complexes and to compare them; 2 - the stability of the complexes as a function of the isotope - chelating agent weight relationships; 3 - the metabolism of the chelating agents resulting in stable complexes, i. e. DTPA and TTHA mainly. This simple method brought out the higher efficiency, of DTPA in chelating rare earths and plutonium and for therapeutic purposes. (authors) [French] La methode consiste a suivre le devenir biologique d'un complexe forme d'une part avec une terre rare (cerium 144) ou un transuranien (plutonium 239) et d'autre part avec un chelateur de la serie des acides polyamines (EDTA, BAETA, DTPA, TTHA). Elle permet d'etudier: 1 - la stabilite in vivo des differents complexes, de les comparer; 2 - la stabilite des complexes en fonction des rapports ponderaux isotope - chelateurs; 3 - le metabolisme des chelateurs formant des complexes stables, essentiellement DTPA et TTHA. Cette methode simple degage la suprematie du DTPA en ce qui concerne la chelation des terres rares et du plutonium, et son utilisation a des fins therapeutiques. (auteurs)

Synthesis and functionalization of bifunctional chelates for 64Cu complexation for their applications by positron emission tomography (PET) imaging and radiotherapy

International Nuclear Information System (INIS)

Roux, Amandine

2014-01-01

This work aimed to develop a new family of bis-pidine-type ligands for copper(II) complexation with applications in Positron Emission Tomography (PET). Indeed, copper 64 is a radioelement whose study in PET imaging is booming. Bis-pidines have the benefit of having a rigid and pre-organized structure for complexation of a large number of transition metals. In this work we present the synthesis and optimization of new ligands whose structural and physico-chemical properties have been studied. One ligand showed very good results because it possesses all of kinetic and thermodynamic parameters which are necessary for its application to PET imaging. Different strategies of functionalization have been studied to obtain bifunctional chelates. A lysine derivative has been coupled to a maleimide function (regio-selective of cysteines), to abiotine (which displays a strong affinity for streptavidin) or to a Bodipy pattern for obtaining a bimodal probe (UV-visible and PET). Finally, we present an extension of this bis-pidine family by increasing the number of coordination functions or by synthesizing tricyclic compounds to modulate the selectivity of these molecules. (author)

Use of chelating agents as immovable phase in extraction chromatography

International Nuclear Information System (INIS)

Sebesta, F.

1978-01-01

Extraction chromatography using chelating agents is reviewed. The theory of element extraction by chelating agents and factors influencing this process (pH, extracting agent concentration in organic phase, masking agent concentration in aqueous phase) are briefly considered. The effect of kinetic factors on the extraction chromatography process is discussed. Ways of preparing columns are emphasized. Examples of using chelating reagents in various extraction chromatography systems are given. β-Diketones, oximes, hydroxamic acids, dithizon, diethyl dithiocarbamic acid are chosen as chelating agents

Chelating impact assessment of biological ad chemical chelates on metal extraction from contaminated soils

International Nuclear Information System (INIS)

Manwar, S.; Iram, S.

2014-01-01

Soil contamination is the result of uncontrolled waste dumping and poor practices by humans. Of all the pollutants heavy metals are of particular concern due to their atmospheric deposition, leaching capacity and non-biodegradability. Heavy metal containing effluent is discharged into the agricultural fields and water bodies. This results in the accumulation of heavy metals in soil and the crops grown on that soil. Studies have revealed detrimental impacts on soil fertility and the poor health of animals and humans. Phytoextraction is widely researched for remediation of heavy metal contaminated soil. To enhance the effect of phytoextraction heavy metals have to be available to the plants in soluble form. In this study the potential of different chelating agents was assessed in solubilizing the heavy metals making easy for plants to uptake them. For this purpose efficient chemical and biological chelating agent had to be identified. Along with that an optimum dose and application time for chemical chelating agent was determined. Ethylenediamine tetraacetic acid (EDTA), Diethylene triamine pentaacetic acid (DTPA), Nitriloacetic acid (NTA) were applied to the soil, containing Pb, Cr, Cu and Cd, at different concentrations and application time. Aspergillus niger and Aspergillus flavus were incubated in soil for different time periods. In correspondence with findings of the study, Pb and Cr were best solubilized by 5mM EDTA. For Cd and Cu 5mM DTPA carried out efficient chelation. NTA showed relatively inadequate solubilisation, although for Cr it performed equal to EDTA. A. niger and A. flavus instead of solubilizing adsorbed the metals in their biomass. Adsorption was mainly carried out by A. niger. (author)

Glyphosate, a chelating agent-relevant for ecological risk assessment?

Science.gov (United States)

Mertens, Martha; Höss, Sebastian; Neumann, Günter; Afzal, Joshua; Reichenbecher, Wolfram

2018-02-01

Glyphosate-based herbicides (GBHs), consisting of glyphosate and formulants, are the most frequently applied herbicides worldwide. The declared active ingredient glyphosate does not only inhibit the EPSPS but is also a chelating agent that binds macro- and micronutrients, essential for many plant processes and pathogen resistance. GBH treatment may thus impede uptake and availability of macro- and micronutrients in plants. The present study investigated whether this characteristic of glyphosate could contribute to adverse effects of GBH application in the environment and to human health. According to the results, it has not been fully elucidated whether the chelating activity of glyphosate contributes to the toxic effects on plants and potentially on plant-microorganism interactions, e.g., nitrogen fixation of leguminous plants. It is also still open whether the chelating property of glyphosate is involved in the toxic effects on organisms other than plants, described in many papers. By changing the availability of essential as well as toxic metals that are bound to soil particles, the herbicide might also impact soil life, although the occurrence of natural chelators with considerably higher chelating potentials makes an additional impact of glyphosate for most metals less likely. Further research should elucidate the role of glyphosate (and GBH) as a chelator, in particular, as this is a non-specific property potentially affecting many organisms and processes. In the process of reevaluation of glyphosate its chelating activity has hardly been discussed.

Chelation therapy to prevent diabetes-associated cardiovascular events.

Science.gov (United States)

Diaz, Denisse; Fonseca, Vivian; Aude, Yamil W; Lamas, Gervasio A

2018-05-24

For over 60 years, chelation therapy with disodium ethylene diamine tetraacetic acid (EDTA, edetate) had been used for the treatment of cardiovascular disease (CVD) despite lack of scientific evidence for efficacy and safety. The Trial to Assess Chelation Therapy (TACT) was developed and received funding from the National Institutes of Health (NIH) to ascertain the safety and efficacy of chelation therapy in patients with CVD. This pivotal trial demonstrated an improvement in outcomes in postmyocardial infarction (MI) patients. Interestingly, it also showed a particularly large reduction in CVD events and all-cause mortality in the prespecified subgroup of patients with diabetes. The TACT results may support the concept of metal chelation to reduce metal-catalyzed oxidation reactions that promote the formation of advanced glycation end products, a precursor of diabetic atherosclerosis. In this review, we summarize the epidemiological and basic evidence linking toxic metal accumulation and diabetes-related CVD, supported by the salutary effects of chelation in TACT. If the ongoing NIH-funded TACT2, in diabetic post-MI patients, proves positive, this unique therapy will enter the armamentarium of endocrinologists and cardiologists seeking to reduce the atherosclerotic risk of their diabetic patients.

Chemistry of bifunctional photoprobes. 3 -- Correlation between the efficiency of CH insertion by photolabile chelating agents and lifetimes of singlet nitrenes by flash photolysis: First example of photochemical attachment of 99mTc-complex with human serum albumin

International Nuclear Information System (INIS)

Pandurangi, R.S.; Lusiak, P.; Kuntz, R.R.; Volkert, W.A.; Rogowski, J.; Platz, M.S.

1998-01-01

Systematic functionalization of perfluoroaryl azides with chelating agents capable of complexing transition metals produces a new class of bifunctional photolabile chelating agents (BFPCAs). The strategy is shield the azide functionality from the electronic and steric influence of the electron-rich metal Pd through ester and amide bridges raised CH insertion efficiency to unprecedented levels (>92%) in a model solvent (cyclohexane). In contrast, perfluoroaryl azides attached to chelating agents via hydrazones show no significant CH insertion in cyclohexane upon photolysis. Measurements of the lifetimes of the singlet nitrenes derived from these agents by flash photolysis techniques correlate well with the efficiency of CH insertion by demonstrating longer lifetimes (10--50 times) for singlet nitrenes derived from azidotetrafluorinated esters and amides compared with the related hydrazones, which failed to yield significant CH insertion. A representative BFPCA 12 is chelated to diagnostic radionuclide 99m Tc and covalently attached to human serum albumin via photochemical activation extending the favorable bimolecular insertion characteristics of BFPCA to tracer level concentrations in buffer conditions. Flash photolysis experiments correlate singlet nitrene lifetimes with the efficiency of intermolecular insertion reactions. This work provides new photo-cross-linking technology, useful in radiodiagnostics and radiotherapy in nuclear medicine

Preparation, Spectroscopic Investigation and Biological Activity of New Mixed Ligand Chelates

International Nuclear Information System (INIS)

Alassbaly, F.S.; Ajaily, M.M.E.

2014-01-01

Preparation and investigation of new Co(II), Ni(II), Zn(II) and Cr(III) chelates with mixed ligands including Schiff base (L1) formed from the condensation of 4-dimethylaminobenzaldehyde with 2-aminophenol and anthranilic acid (L2) were studied. The obtained Schiff base and mixed ligand chelates were subjected to several physiochemical techniques, in terms of CHN elemental analyses, molar conductivity, magnetic moment measurements, infrared, proton nuclear magnetic resonance, electronic and mass spectra. The analytical data showed the formation of the Schiff base compound and the ratio of metal to ligands of the chelates are 1:1:1(M:L1:L2). The infrared spectral data exhibited that the used ligands behaving as bidentate ligands towards the metal ions. The proton nuclear magnetic resonance spectral data showed the signals of the active groups in the ligands which entered in chelation with Zn(II) metal ion. The electronic spectral results showed the existence of pie (phenyl ring) and n = pie (C=N) of the ligands and suggested the geometrical structures of the chelates. Meanwhile, the mass spectral data revealed the fragmentations of the Schiff base, anthranilic acid and their Ni(II) mixed ligand chelate has been preformed the only chelate conducted for justification. All the prepared mixed chelates were non-electrolyte in nature. The antibacterial activity of the Schiff base, anthranilic acid, metal salts and mixed ligand chelates were studied and found to be that mixed ligand chelates have the most biological activity in comparison to the free ligands and salts. (author)

Spectral, biological screening of metal chelates of chalcone based Schiff bases of N-(3-aminopropyl) imidazole.

Science.gov (United States)

Kalanithi, M; Rajarajan, M; Tharmaraj, P; Sheela, C D

2012-02-15

Tridentate chelate complexes of Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized from the chalcone based ligands 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-(phenylallyl)]phenol(HL(1)), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-p-tolylallyl]phenol(HL(2)), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-4-nitrophenylallyl]phenol(HL(3)). Microanalytical data, UV-vis spectrophotometric method, magnetic susceptibility measurements, IR, 1H NMR, Mass, and EPR techniques were used to characterize the structure of chelates. The electronic absorption spectra and magnetic susceptibility measurements suggest a distorted square planar geometry for the copper(II) ion. The other metal complexes show distorted tetrahedral geometry. The coordination of the ligands with metal(II) ions was further confirmed by solution fluorescence spectrum. The antimicrobial activity of the ligands and metal(II) complexes against the species Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albigans and Aspergillus niger has been carried out and compared. The electrochemical behavior of copper(II) complex is studied by cyclic voltammetry. Copyright © 2011 Elsevier B.V. All rights reserved.

Study of cyclization of chelating compounds using electrospray ionization mass spectrometry

International Nuclear Information System (INIS)

Shi Ying; Campbell, J.A.

2000-01-01

Electrospray ionization mass spectrometry (ESI-MS) was used for the study of cyclization of organic chelating compounds (chelators). Four chelating compounds were studied: Symmetrical ethylenediaminediacetic acid (s-EDDA), Unsymmetrical ethylenediaminediacetic acid (u-EDDA), N-(2-hydroxyethyl) ethylenediaminetriacetic acid (HEDTA), and N-(2-hydroxyethyl)iminodiacetic acid (HEIDA). The chelators were cyclized with treatments of acids and heating. The open and cyclized form of the chelators were semi-quantified by both positive and negative ion modes ESI-MS. The kinetics of chelator cyclization was studied as a function of reaction temperature and the pH of the matrix. The cyclization of s-EDDA was found to be a pseudo-first order reaction in s-EDDA and overall second order. The cyclizations of HEIDA and HEDTA are reversible reactions. Higher temperature and lower pH favors cyclization. (author)

Effects of some chelating agents on the uptake and distribution of 54Mn(II) in the brown trout (Salmo trutta)

International Nuclear Information System (INIS)

Rouleau, C.; Tjaelve, H.; Pelletier, E.; Gottofrey, J.

1994-01-01

The effects of humic acids, which are natural metal-complexing compounds, and potassium ethylxanthate, sodium diethyldithiophosphate, sodium dimethyldithicarbamate, which are sulphur-containing man-made chelating agents, on the uptake and tissue distribution of 54 Mn(II) were studied in brown trout (Salmo trutta). Fish were exposed for 7 days to 0.1 μg Mn(II)x. -2 as NmCl 2 (l μCia 54 Mnxl -1 ) with or without chelat agents. Examination of the partition of Mn between octanol and a Tris-HCl buffer in the presence of these compounds was also performed. Humic acids had only small effects on Mn uptake and distribution in trout, probably because of the low stability of Mn-humate complexes. Partition of Mn in the presence of potassium ethylxanthate, sodium diethyldithiophosphate, sodium dimethyldithiocarbamate, and sodium diethyldithiocarbamate between octanol and Tris-HCl buffer showed formation of lipophilic complex with the latter two compounds, but not with the former. However, these four chelating agents all decreased Mn uptake in the trout by 40-45%. These substances also changed the distribution of Mn within the fish, with a higher proportion of the metal being present in some visceral organs and a smaller proportion being localized in some non-parenchymateous tissues, such as skin, fins and bones. The mechanisms underlying these effects are not known. however, the interaction of chelating agents with the Mn, although weak, may have partially withdrawn the metal from the uptake process inthe gills. The redistribution of Mn in the fish may be due to the binding of the metal to complexing compounds which have reached the intestinal lumen. Previous studies with other metals have shown increased or unchanged metal levels in tissues of fish at exposure together with potasium ethylxanthate, sodium diethyldithiophosphate, sodium dimethyldithiocarbamate, and sodium diethyldithiocarbamate, but decreased metal levels have not been observed before. (au) (37 refs.)

Metal chelate process to remove pollutants from fluids

Science.gov (United States)

Chang, S.G.T.

1994-12-06

The present invention relates to improved methods using an organic iron chelate to remove pollutants from fluids, such as flue gas. Specifically, the present invention relates to a process to remove NO[sub x] and optionally SO[sub 2] from a fluid using a metal ion (Fe[sup 2+]) chelate wherein the ligand is a dimercapto compound wherein the --SH groups are attached to adjacent carbon atoms (HS--C--C--SH) or (SH--C--CCSH) and contain a polar functional group so that the ligand of DMC chelate is water soluble. Alternatively, the DMC is covalently attached to a water insoluble substrate such as a polymer or resin, e.g., polystyrene. The chelate is regenerated using electroreduction or a chemical additive. The dimercapto compound bonded to a water insoluble substrate is also useful to lower the concentration or remove hazardous metal ions from an aqueous solution. 26 figures.

New method for studying the efficiency of chelating agents of the polyamine acid series for internal decontamination; Methode nouvelle d'etude de l'efficacite des chelateurs de la serie des acides polyamines pour la decontamination interne

Energy Technology Data Exchange (ETDEWEB)

Lafuma, J.; Nenot, J.C.; Morin, M. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1968-07-01

We followed the biological fate of a complex formed on one side with either a rare earth (cerium-144) or a transuranium element (plutonium-239), and on the other side with a chelating agent of the polyamino acid series (EDTA, BAETA, DTPA, TTHA). This method allowed to study: 1 - the in vivo stability of the various complexes and to compare them; 2 - the stability of the complexes as a function of the isotope - chelating agent weight relationships; 3 - the metabolism of the chelating agents resulting in stable complexes, i. e. DTPA and TTHA mainly. This simple method brought out the higher efficiency, of DTPA in chelating rare earths and plutonium and for therapeutic purposes. (authors) [French] La methode consiste a suivre le devenir biologique d'un complexe forme d'une part avec une terre rare (cerium 144) ou un transuranien (plutonium 239) et d'autre part avec un chelateur de la serie des acides polyamines (EDTA, BAETA, DTPA, TTHA). Elle permet d'etudier: 1 - la stabilite in vivo des differents complexes, de les comparer; 2 - la stabilite des complexes en fonction des rapports ponderaux isotope - chelateurs; 3 - le metabolisme des chelateurs formant des complexes stables, essentiellement DTPA et TTHA. Cette methode simple degage la suprematie du DTPA en ce qui concerne la chelation des terres rares et du plutonium, et son utilisation a des fins therapeutiques. (auteurs)

Mesoporous organosilica nanotubes containing a chelating ligand in their walls

Directory of Open Access Journals (Sweden)

Xiao Liu

2014-11-01

Full Text Available 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.

Bifunctional chelates of Rh-105 and Au-199 as potential radiotherapeutic agents

International Nuclear Information System (INIS)

Troutner, D.E.; Schlemper, E.O.

1990-01-01

Since last year we have: continued the synthesis of pentadentate bifunctional chelating agents based on diethylene triamine; studied the chelation Rh-105, Au-198 (as model for Au-199) and Tc-99m with these agents as well as chelation of Pd-109, Cu-67, In-111, and Co-57 with some of them; synthesized a new class of potential bifunctional chelating agents based on phenylene diamine; investigated the behavior of Au-198 as a model for Au-199; begun synthesis of bifunctional chelating agents based on terpyridly and similar ligands; and continued attempts to produce tetradentate bifunctional chelates based on diaminopropane. Each of these will be addressed in this report

Diglycolic acid, the toxic metabolite of diethylene glycol, chelates calcium and produces renal mitochondrial dysfunction in vitro.

Science.gov (United States)

Conrad, Taylor; Landry, Greg M; Aw, Tak Yee; Nichols, Royce; McMartin, Kenneth E

2016-07-01

Diethylene glycol (DEG) has caused many cases of acute kidney injury and deaths worldwide. Diglycolic acid (DGA) is the metabolite responsible for the renal toxicity, but its toxic mechanism remains unclear. To characterize the mitochondrial dysfunction produced from DGA by examining several mitochondrial processes potentially contributing to renal cell toxicity. The effect of DGA on mitochondrial membrane potential was examined in normal human proximal tubule (HPT) cells. Isolated rat kidney mitochondria were used to assess the effects of DGA on mitochondrial function, including respiratory parameters (States 3 and 4), electron transport chain complex activities and calcium-induced opening of the mitochondrial permeability transition pore. DGA was compared with ethylene glycol tetraacetic acid (EGTA) to determine calcium chelating ability. DGA cytotoxicity was assessed using lactate dehydrogenase leakage from cultured proximal tubule cells. DGA decreased the mitochondrial membrane potential in HPT cells. In rat kidney mitochondria, DGA decreased State 3 respiration, but did not affect State 4 respiration or the ADP/O ratio. DGA reduced glutamate/malate respiration at lower DGA concentrations (0.5 mmol/L) than succinate respiration (100 mmol/L). DGA inhibited Complex II activity without altering Complex I, III or IV activities. DGA blocked calcium-induced mitochondrial swelling, indicating inhibition of the calcium-dependent mitochondrial permeability transition. DGA and EGTA reduced the free calcium concentration in solution in an equimolar manner. DGA toxicity and mitochondrial dysfunction occurred as similar concentrations. DGA inhibited mitochondrial respiration, but without uncoupling oxidative phosphorylation. The more potent effect of DGA on glutamate/malate respiration and the inhibition of mitochondrial swelling was likely due to its chelation of calcium. These results indicate that DGA produces mitochondrial dysfunction by chelating calcium to

Synthesis and characterisation of 8-hydroxyquinoline-bovine serum albumin conjugates as metal ion chelating proteins

International Nuclear Information System (INIS)

Giraudi, G.; Baggiani, C.; Giovannoli, C.; Marletto, C.; Vanni, A.

1999-01-01

A derivative of 8-hydroxyquinoline (8-quinolinol, oxine) with a linking bridge containing a carboxylic group was covalently coupled to bovine serum albumin by the N-hydroxysuccinimide method to obtain stable monomeric conjugates with oxine to protein mole ratios up to 37. These conjugates were characterised spectrophotometrically and their complexation properties were confirmed by spectral analysis with and without the addition of Al(III), Cd(II), Co(II), Cu(II), Hg(II), Mn(II), Ni(II), Pb(II), V(IV), U(VI) and Zn(II) ions added. The maximum number of ions bound by these chelating proteins was determined spectrophotometrically by titration with metal ions at pH 6.0. The conjugates with a substitution ratio (moles of 8-hydroxyquinoline bound/mole of albumin) less than about 8 showed 1:1 binding with metal ions, while conjugates with higher substitution ratios were able to complex with 2:1 ratio of 8-hydroxyquinoline to metal ion. Association and dissociation kinetics of complexation with copper(II) ions showed a complex mechanism. The spectral and binding properties of these metal ion-binding proteins confirm that the coupling of the 8-hydroxyquinoline derivative to bovine serum albumin gives stable, water soluble, macromolecular chelating agents that retain the complexing ability of the original ligand. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

Synthesis of Copper-Chelates Derived from Amino Acids and Evaluation of Their Efficacy as Copper Source and Growth Stimulator for Lactuca sativa in Nutrient Solution Culture.

Science.gov (United States)

Kaewchangwat, Narongpol; Dueansawang, Sattawat; Tumcharern, Gamolwan; Suttisintong, Khomson

2017-11-15

Five tetradentate ligands were synthesized from l-amino acids and utilized for the synthesis of Cu(II)-chelates 1-5. The efficacy of Cu(II)-chelates as copper (Cu) source and growth stimulator in hydroponic cultivation was evaluated with Lactuca sativa. Their stability test was performed at pH 4-10. The results suggested that Cu(II)-chelate 3 is the most pH tolerant complex. Levels of Cu, Zn, and Fe accumulated in plants supplied with Cu(II)-chelates were compared with those supplied with CuSO 4 at the same Cu concentration of 8.0 μM. The results showed that Cu(II)-chelate 3 significantly enhanced Cu, Zn, and Fe content in shoot by 35, 15, and 48%, respectively. Application of Cu(II)-chelate 3 also improved plant dry matter yield by 54%. According to the results, Cu(II)-chelate 3 demonstrated the highest stimulating effect on plant growth and plant mineral accumulation so that it can be used as an alternative to CuSO 4 for supplying Cu in nutrient solutions and enhancing the plant growth.

Laccase Immobilization by Chelated Metal Ion Coordination Chemistry

Directory of Open Access Journals (Sweden)

Qingqing Wang

2014-09-01

Full Text Available In this work, amidoxime polyacrylonitrile (AOPAN nanofibrous membrane was prepared by a reaction between PAN nanofibers and hydroxylamine hydrochloride. The AOPAN nanofibrous membranes were used for four metal ions (Fe3+, Cu2+, Ni2+, Cd2+ chelation under different conditions. Further, the competition of different metal ions coordinating with AOPAN nanofibrous membrane was also studied. The AOPAN chelated with individual metal ion (Fe3+, Cu2+, Ni2+, Cd2+ and also the four mixed metal ions were further used for laccase (Lac immobilization. Compared with free laccase, the immobilized laccase showed better resistance to pH and temperature changes as well as improved storage stability. Among the four individual metal ion chelated membranes, the stability of the immobilized enzymes generally followed the order as Fe–AOPAN–Lac > Cu–AOPAN–Lac > Ni–AOPAN–Lac > Cd–AOPAN–Lac. In addition, the immobilized enzyme on the carrier of AOPAN chelated with four mixed metal ions showed the best properties.

Synthesis of a Bis(thiophenolate)pyridine Ligand and Its Titanium, Zirconium, and Tantalum Complexes

KAUST Repository

Lenton, Taylor N.

2012-11-12

A precursor to a new tridentate LX 2 type ligand, bis(thiophenol)pyridine ((SNS)H 2 = (2-C 6H 4SH) 2-2,6-C 5H 3N), was prepared. Bis(thiophenolate)pyridine complexes of Ti, Zr, and Ta having dialkylamido coligands were synthesized and structurally characterized. The zirconium complex (SNS)Zr(NMe 2) 2 (4) displays C 2 symmetry in the solid state, unlike a related bis(phenolate)pyridine compound, C s-symmetric (ONO)Ti(NMe 2) 2. This change is likely the result of strain about the sulfur atom in the six-membered chelate with longer metal-sulfur and carbon-sulfur bonds. Solid-state structures of tantalum complexes (SNS)Ta(NMe 2) 3 (5) and (SNS)TaCl(NEt 2) 2 (6) also display pronounced C 2 twisting of the SNS ligand. 1D and 2D NMR experiments show that 5 is fluxional, with rotation about the Ta-N(amide) bonds occurring on the NMR time scale that interchange the equatorial amide methyl groups (ΔG ‡ 393 = 25.0(3) kcal/mol). The fluxional behavior of 6 in solution was also studied by variable-temperature 1H NMR. Observation of separate signals for the diastereotopic protons of the methylene unit of the diethylamide indicates that the complex remains locked on the NMR time scale in one diastereomeric conformation at temperatures below -50 °C, fast rotation about the equatorial amide Ta-N bonds occurs at higher temperature (ΔG ‡ 393 = 13.4(3) kcal/mol), and exchange of diastereomeric methylene protons occurs via inversion at Ta that interconverts antipodes (ΔG ‡ 393 ≈ 14(1) kcal/mol). © 2012 American Chemical Society.

Chelating agents as stationary phase in extraction chromatography, ch. 11

International Nuclear Information System (INIS)

Sebesta, F.

1975-01-01

Chelating agents have been used largely in extraction chromatography for separations related to activation analysis, for concentration of metals from dilute solutions, and for preparation of radiochemically pure or carrier-free radionuclides. This review deals with the theory of extraction by chelating agents, the experimental technique, and the chelating agents and systems used (β-diketones, oximes, hydroxamic acid, dithizone and diethyldithiocarbamic acid)

Sealing glasses for titanium and titanium alloys

Science.gov (United States)

Brow, Richard K.; McCollister, Howard L.; Phifer, Carol C.; Day, Delbert E.

1997-01-01

Barium lanthanoborate sealing-glass compositions are provided comprising various combinations (in terms of mole-%) of boron oxide (B.sub.2 O.sub.3), barium oxide (BaO), lanthanum oxide (La.sub.2 O.sub.3), and at least one other oxide selected from the group consisting of aluminum oxide (Al.sub.2 O.sub.3), calcium oxide (CaO), lithium oxide (Li.sub.2 O), sodium oxide (Na.sub.2 O), silicon dioxide (SiO.sub.2), or titanium dioxide (TiO.sub.2). These sealing-glass compositions are useful for forming hermetic glass-to-metal seals with titanium and titanium alloys having an improved aqueous durability and favorable sealing characteristics. Examples of the sealing-glass compositions are provided having coefficients of thermal expansion about that of titanium or titanium alloys, and with sealing temperatures less than about 900.degree. C., and generally about 700.degree.-800.degree. C. The barium lanthanoborate sealing-glass compositions are useful for components and devices requiring prolonged exposure to moisture or water, and for implanted biomedical devices (e.g. batteries, pacemakers, defibrillators, pumps).

Isolation and characterization of iron chelators from turmeric (Curcuma longa): selective metal binding by curcuminoids.

Science.gov (United States)

Messner, Donald J; Surrago, Christine; Fiordalisi, Celia; Chung, Wing Yin; Kowdley, Kris V

2017-10-01

Iron overload disorders may be treated by chelation therapy. This study describes a novel method for isolating iron chelators from complex mixtures including plant extracts. We demonstrate the one-step isolation of curcuminoids from turmeric, the medicinal food spice derived from Curcuma longa. The method uses iron-nitrilotriacetic acid (NTA)-agarose, to which curcumin binds rapidly, specifically, and reversibly. Curcumin, demethoxycurcumin, and bisdemethoxycurcumin each bound iron-NTA-agarose with comparable affinities and a stoichiometry near 1. Analyses of binding efficiencies and purity demonstrated that curcuminoids comprise the primary iron binding compounds recovered from a crude turmeric extract. Competition of curcuminoid binding to the iron resin was used to characterize the metal binding site on curcumin and to detect iron binding by added chelators. Curcumin-Iron-NTA-agarose binding was inhibited by other metals with relative potency: (>90% inhibition) Cu 2+  ~ Al 3+  > Zn 2+  ≥ Ca 2+  ~ Mg 2+  ~ Mn 2+ (80% by addition of iron to the media; uptake was completely restored by desferoxamine. Ranking of metals by relative potencies for blocking curcumin uptake agreed with their relative potencies in blocking curcumin binding to iron-NTA-agarose. We conclude that curcumin can selectively bind toxic metals including iron in a physiological setting, and propose inhibition of curcumin binding to iron-NTA-agarose for iron chelator screening.

New insights into the complex photoluminescence behaviour of titanium white pigments

NARCIS (Netherlands)

van Driel, B.A.; Artesani, A.; van den Berg, Klaas Jan; Dik, J.; Mosca, S.; Rossenaar, B.; Hoekstra, J.; Davies, A.; Nevin, A.; Valentini, G.; Comelli, D.

2018-01-01

This work reports the analysis of the time-resolved photoluminescence behaviour on the nanosecond and microsecond time scale of fourteen historical and contemporary titanium white pigments. The pigments were produced with different production methods and post-production treatments, giving rise to

Surface modification of titanium and titanium alloys by ion implantation.

Science.gov (United States)

Rautray, Tapash R; Narayanan, R; Kwon, Tae-Yub; Kim, Kyo-Han

2010-05-01

Titanium and titanium alloys are widely used in biomedical devices and components, especially as hard tissue replacements as well as in cardiac and cardiovascular applications, because of their desirable properties, such as relatively low modulus, good fatigue strength, formability, machinability, corrosion resistance, and biocompatibility. However, titanium and its alloys cannot meet all of the clinical requirements. Therefore, to improve the biological, chemical, and mechanical properties, surface modification is often performed. In view of this, the current review casts new light on surface modification of titanium and titanium alloys by ion beam implantation. (c) 2010 Wiley Periodicals, Inc.

Gentamicin-Eluting Titanium Dioxide Nanotubes Grown on the Ultrafine-Grained Titanium.

Science.gov (United States)

Nemati, Sima Hashemi; Hadjizadeh, Afra

2017-08-01

Titanium (Ti)-based materials is the most appropriate choices for the applications as orthopedic and dental implants. In this regard, ultrafine-grained (UFG) titanium with an enhanced mechanical properties and surface energy has attracted more attention. Titanium dioxide (TiO 2 ) nanotubes grown on the titanium could enhance bone bonding, cellular response and are good reservoirs for loading drugs and antibacterial agents. This article investigates gentamicin loading into and release from the TiO 2 nanotubes, grown on the UFG compared to coarse-grained (CG) titanium substrate surfaces. Equal Channel Angular Pressing (ECAP) was employed to produce the UFG structure titanium. TiO 2 nanotubes were grown by the anodizing technique on both UFG and CG titanium substrate surfaces. Scanning electron microscopy (SEM) imaging confirmed TiO 2 nanotube growth on the surface. The UV-vis spectroscopy analysis results show that the amount of gentamicin load-release in the anodized UFG titanium sample is higher than that of CG one which can be explained in terms of thicker TiO 2 nanotube arrays layer formed on UFG sample. Moreover, the anodized UFG titanium samples released the drug in a longer time than CG (1 day for the UFG titanium vs. 3 h for the CG one). Regarding wettability analysis, anodized UFG titanium sample showed more enhanced hydrophilicity than CG counterpart. Therefore, the significantly smaller grain size of pure titanium provided by the ECAP technique coupled with appropriate subsequent anodization treatment not only offers a good combination of biocompatibility and adequate mechanical properties but also it provides a delayed release condition for gentamicin.

The adsorption of chelating reagents on oxide minerals

International Nuclear Information System (INIS)

Bryson, M.A.W.

1984-06-01

This work constitutes a fundamental study of the interaction between chelating reagents and oxide minerals. The adsorption mechanisms have been elucidated for most of the systems generated by the oxides of copper(II) or iron(III) and chelating reagents octyl hydroxamate, N-phenylbenzohydroxamate, salicylaldoxime, 5-nitro-salicylaldoxime or 8-hydroxyquinoline. In order to better understand the adsorption process associated with copper(II) oxide, the oxide was recrystallized to produce a coarser material with a more uniform surface. This allowed the oxide surface to be viewed under the scanning electron microscope. A detailed investigation of the effect of the system variables; pH, conditioning period, concentration, temperature, surface area and dispersing reagent on the rate of precipitation of the copper chelate species of general form, Cu(chel) 2 , was made. In addition the chemical nature of the adsorbed species and the structural form of the precipitates were determined with the aid of infra-red spectroscopy and the scanning electron microscope. On the basis of these results a model has been formulated for the adsorption processes. The precipitation process was examined in more detail by the study of the adsorption of chelate on copper metal. Contact angle measurements of air bubbles on copper metal conditioned with chelate were related to the adsorption results in an attempt to isolate the optimum conditions for flotation of oxide minerals

Microreactor and method for preparing a radiolabeled complex or a biomolecule conjugate

Energy Technology Data Exchange (ETDEWEB)

Reichert, David E; Kenis, Paul J. A.; Wheeler, Tobias D; Desai, Amit V; Zeng, Dexing; Onal, Birce C

2015-03-17

A microreactor for preparing a radiolabeled complex or a biomolecule conjugate comprises a microchannel for fluid flow, where the microchannel comprises a mixing portion comprising one or more passive mixing elements, and a reservoir for incubating a mixed fluid. The reservoir is in fluid communication with the microchannel and is disposed downstream of the mixing portion. A method of preparing a radiolabeled complex includes flowing a radiometal solution comprising a metallic radionuclide through a downstream mixing portion of a microchannel, where the downstream mixing portion includes one or more passive mixing elements, and flowing a ligand solution comprising a bifunctional chelator through the downstream mixing portion. The ligand solution and the radiometal solution are passively mixed while in the downstream mixing portion to initiate a chelation reaction between the metallic radionuclide and the bifunctional chelator. The chelation reaction is completed to form a radiolabeled complex.

Effect of Chelating Agents on the Stability of Nano-TiO2 Sol Particles for Sol-Gel Coating.

Science.gov (United States)

Maeng, Wan Young; Yoo, Mi

2015-11-01

Agglomeration of sol particles in a titanium alkoxide (tetrabutyl orthotitanate (TBOT), > 97%) solution during the hydrolysis and condensation steps makes the sol solution difficult to use for synthesizing homogeneous sol-gel coating. Here, we have investigated the effect of stabilizing agents (acetic acid and ethyl acetoacetate (EAcAc)) on the agglomeration of Ti alkoxide particles during hydrolysis and condensation in order to determine the optimized conditions for controlling the precipitation of TiO2 particles. The study was conducted at R(AC) ([acetic acid]/[TBOT]) = 0.1-5 and R(EAcAc)([EAcAc]/[TBOT]) = 0.05-0.65. We also studied the effects of a basic catalyst ethanolamine (ETA), water, and HCl on sol stability. The chelating ligands in the precursor sol were analyzed with FT-IR. The coating properties were examined by focused ion beam. The stabilizing agents (acetic acid and EAcAc) significantly influenced the agglomeration and precipitation of TBOT precursor particles during hydrolysis. As R(AC) and R(EAcAc) increased, the agglomeration remarkably decreased. The stability of the sol with acetic acid and EAcAc arises from the coordination of the chelating ligand to TBOT that hinders hydrolysis and condensation. A uniform fine coating (thickness: 30 nm) on stainless steel was obtained by using an optimized sol with R(AC) = 0.5 and R(EAcAc) = 0.65.

Labelling of bacteria with indium chelates

International Nuclear Information System (INIS)

Kleinert, P.; Pfister, W.; Endert, G.; Sproessig, M.

1985-01-01

The indium chelates were prepared by reaction of radioactive indiumchloride with 10 μg oxine, 15 μg tropolone and 3 mg acetylacetone, resp. The formed chelates have been incubated with 10 9 germs/ml for 5 minutes, with labelling outputs from 90 to 95%. Both gram-positive (Streptococcus, Staphylococcus) and gram-negative bacteria (Escherichia coli) can be labelled. The reproductive capacity of the bacteria was not impaired. The application of indium labelled bacteria allows to show the distribution of microorganisms within the living organism and to investigate problems of bacterial adherence. (author)

Reducing the potential for migration of radioactive waste: Aqueous thermal degradation of the chelating agent disodium EDTA

International Nuclear Information System (INIS)

Boles, J.S.; Ritchie, K.; Crerar, D.A.

1987-01-01

Ethylenediaminetetraacetic acid (EDTA), a common component of cleaning solutions used for decontamination of radioactive equipment, has been associated with increased migration of radionuclides into local groundwaters at some radwaste disposal sites. It has been proposed that predisposal thermal degradation of EDTA-containing aqueous solutions may reduce the potential for chelate-enhanced mobilization of radionuclides at these sites. Aqueous thermal degradation experiments with disodium EDTA have shown that the compound degrades rapidly at 200 0 C with an activation energy of 114.3 +- 7.87 kJ/mol, and forms the decomposition product methyliminodiacetic acid (MIDA). A comparison of the values for stability constants of transition metal and actinide complexes with EDTA, MIDA, and two other reported degradation products, indicates that the chelating efficiency of the degradation products is 6 to 22 orders of magnitude lower than that of EDTA at 25 0 C. It is concluded that aqueous thermal degradation should significantly reduce the overall chelating efficiency of EDTA-containing solutions

Electrodeposition of amine-terminatedpoly(ethylene glycol) to titanium surface

International Nuclear Information System (INIS)

Tanaka, Yuta; Doi, Hisashi; Iwasaki, Yasuhiko; Hiromoto, Sachiko; Yoneyama, Takayuki; Asami, Katsuhiko; Imai, Hachiro; Hanawa, Takao

2007-01-01

The immobilization of poly(ethylene glycol), PEG, to a solid surface is useful to functionalize the surface, e.g., to prevent the adsorption of proteins. No successful one-stage technique for the immobilization of PEG to base metals has ever been developed. In this study, PEG in which both terminals or one terminal had been modified with amine bases was immobilized onto a titanium surface using electrodeposition. PEG was dissolved in a NaCl solution, and electrodeposition was carried out at 310 K with - 5 V for 300 min. The thickness of the deposited PEG layer was evaluated using ellipsometry, and the bonding manner of PEG to the titanium surface was characterized using X-ray photoelectron spectroscopy after electrodeposition. The results indicated that a certain amount of PEG was adsorbed on titanium through both electrodeposition and immersion when PEG was terminated by amine. However, terminated amines existed at the surface of titanium and were combined with titanium oxide as N-HO by electrodeposition, while amines randomly existed in the molecule and showed an ionic bond with titanium oxide by immersion. The electrodeposition of PEG was effective for the inhibition of albumin adsorption. This process is useful for materials that have electroconductivity and a complex morphology

Chelating agent-free, vapor-assisted crystallization method to synthesize hierarchical microporous/mesoporous MIL-125 (Ti).

Science.gov (United States)

McNamara, Nicholas D; Hicks, Jason C

2015-03-11

Titanium-based microporous heterogeneous catalysts are widely studied but are often limited by the accessibility of reactants to active sites. Metal-organic frameworks (MOFs), such as MIL-125 (Ti), exhibit enhanced surface areas due to their high intrinsic microporosity, but the pore diameters of most microporous MOFs are often too small to allow for the diffusion of larger reactants (>7 Å) relevant to petroleum and biomass upgrading. In this work, hierarchical microporous MIL-125 exhibiting significantly enhanced interparticle mesoporosity was synthesized using a chelating-free, vapor-assisted crystallization method. The resulting hierarchical MOF was examined as an active catalyst for the oxidation of dibenzothiophene (DBT) with tert-butyl hydroperoxide and outperformed the solely microporous analogue. This was attributed to greater access of the substrate to surface active sites, as the pores in the microporous analogues were of inadequate size to accommodate DBT. Moreover, thiophene adsorption studies suggested the mesoporous MOF contained larger amounts of unsaturated metal sites that could enhance the observed catalytic activity.

Review of actinide decorporation with chelating agents

Energy Technology Data Exchange (ETDEWEB)

Ansoborlo, E. [CEA Valrho, Dir. de l' Energie Nucleaire (DEN/DRCP/CETAMA), 30 - Marcoule (France); Amekraz, B.; Moulin, Ch. [CEA Saclay, Dept. de Physico-Chimie (DEN/DPC/SECR), 91 - Gif sur Yvette (France); Moulin, V. [CEA Saclay, Dir. du Developpement et de l' Innovation Nucleares (DEN/DDIN/MR), 91 - Gif Sur Yvette (France); Taran, F. [CEA Saclay (DSV/DBJC/SMMCB), 91 - Gif-sur-Yvette (France); Bailly, Th.; Burgada, R. [Centre National de la Recherche Scientifique (CNRS/LCSB/UMR 7033), 93 - Bobigny (France); Henge-Napoli, M.H. [CEA Valrho, Site de Marcoule (INSTN), 30 (France); Jeanson, A.; Den Auwer, Ch.; Bonin, L.; Moisy, Ph. [CEA Valrho, Dir. de l' Energie Nucleaire (DEN/DRCP/SCPS), 30 - Marcoule (France)

2007-10-15

In case of accidental release of radionuclides in a nuclear facility or in the environment, internal contamination (inhalation, ingestion or wound) with actinides represents a severe health risk to human beings. It is therefore important to provide effective chelation therapy or decorporation to reduce acute radiation damage, chemical toxicity, and late radiation effects. Speciation governs bioavailability and toxicity of elements and it is a prerequisite tool for the design and success of new ligands or chelating agents. The purpose of this review is to present the state-of-the-art of actinide decorporation within biological media, to recall briefly actinide metabolism, to list the basic constraints of actinide-ligand for development, to describe main tools developed and used for decorporation studies, to review mainly the chelating agents tested for actinides, and finally to conclude on the future trends in this field. (authors)

An efficient hybrid, nanostructured, epoxidation catalyst: titanium silsesquioxane-polystyrene copolymer supported on SBA-15

NARCIS (Netherlands)

Santen, van R.A.; Zhang, Lei; Abbenhuis, H.C.L.; Gerritsen, G.; Ní Bhriain, N.M.; Magusin, P.C.M.M.; Mezari, B.; Han, W.; Yang, Q.; Li, Can

2007-01-01

A novel interfacial hybrid epoxidation catalyst was designed with a new immobilization method for homogeneous catalysts by coating an inorganic support with an organic polymer film containing active sites. The titanium silsesquioxane (TiPOSS) complex, which contains a single-site titanium active

Radiopharmaceutical chelates and method of external imaging

International Nuclear Information System (INIS)

1976-01-01

The preparation of the following chemicals is described: chelates of technetium-99m, cobalt-57, gallium-67, gallium-68, indium-111 or indium-113m and a substituted iminodiacetic acid or an 8-hydroxyquinoline useful as a radiopharmaceutical external imaging agent. The compounds described are suitable for intravenous injection, have an excellent in vivo stability and are good organ seekers. Tin(II) choride or other tin(II) compounds are used as chelating agents

Csbnd H⋯Ni and Csbnd H⋯π(chelate) interactions in nickel(II) complexes involving functionalized dithiocarbamates and triphenylphosphine

Science.gov (United States)

Sathiyaraj, E.; Thirumaran, S.; Selvanayagam, S.; Sridhar, B.; Ciattini, Samuele

2018-05-01

New bis(N-benzyl-N-substituted benzyldithiocarbamato-S,S‧)nickel(II) (1-3) and (N-benzyl-N-substituted benzyldithiocarbamato-S,S‧)(isothiocyanato-N)- (triphenylphosphane)nickel(II) (4-6) [where substituted benzyl = 2-HOsbnd C6H4sbnd CH2sbnd (1,4), 3-HOsbnd C6H4sbnd CH2sbnd (2,5), 4-Fsbnd C6H4sbnd CH2sbnd (3,6)] were synthesized and characterized using IR, electronic, and NMR (1H and 13C) spectra. X-ray structural analysis of homoleptic complex (1) and heteroleptic complexes (5 and 6) confirmed the presence of four coordinated nickel in a distorted square planar arrangement with NiS4 and NiS2PN chromophores, respectively. The νC-S stretching vibrations are observed around 990 cm-1 without any splitting supporting the bidentate coordination of the dithiocarbamate ligand. Electronic spectral studies of all the complexes (1-6) indicate that the geometry of the nickel atom is probably square planar. NMR spectra of all homoleptic and heteroleptic complexes (1-6) reveal a weak signal associated with the backbone carbon (N13CS2) in the region 204.0-210.0 ppm with a weak intensity characteristic of the quaternary carbon signals. The greater trans influence of triphenylphosphine in complexes 5 and 6 is supported by the long Nisbnd S distance compared to other Nisbnd S distance which is opposite to the NCS- ligand. In the structure of complex 5, C-H⋯π(chelate) interactions results in polymeric chain. Both structures show intramolecular Ni⋯H interactions but that on 6 is the strongest. C-H⋯π interactions are also found in 1, 5 and 6. Hirshfeld surface analysis and the associated 2D fingerprint plots of 1, 5 and 6 have been studied to evaluate intermolecular interactions. The molecular geometries of complexes 1, 5 and 6 have been optimized by abinitio HF method using LANL2DZ program.

CARDIAC FUNCTION AND IRON CHELATION IN THALASSEMIA MAJOR AND INTERMEDIA: A REVIEW OF THE UNDERLYING PATHOPHYSIOLOGY AND APPROACH TO CHELATION MANAGEMENT

Directory of Open Access Journals (Sweden)

Athanasios Aessopos

2009-07-01

Full Text Available Heart disease is the leading cause of mortality and one of the main causes of morbidity in beta-thalassemia. Patients with homozygous thalassemia may have either a severe phenotype which is usually transfusion dependent or a milder form that is thalassemia intermedia.  The two main factors that determine cardiac disease in homozygous β thalassemia are the high output state that results from chronic tissue hypoxia, hypoxia-induced compensatory reactions and iron overload.  The high output state playing a major role in thalassaemia intermedia and the iron load being more significant in the major form. Arrhythmias, vascular involvement that leads to an increased pulmonary vascular resistance and an increased systemic vascular stiffness and valvular abnormalities also contribute to the cardiac dysfunction in varying degrees according to the severity of the phenotype.  Endocrine abnormalities, infections, renal function and medications can also play a role in the overall cardiac function.  For thalassaemia major, regular and adequate blood transfusions and iron chelation therapy are the mainstays of management. The approach to thalassaemia intermedia, today, is aimed at monitoring for complications and initiating, timely, regular transfusions and/or iron chelation therapy.  Once the patients are on transfusions, then they should be managed in the same way as the thalassaemia major patients.  If cardiac manifestations of dysfunction are present in either form of thalassaemia, high pre transfusion Hb levels need to be maintained in order to reduce cardiac output and appropriate intensive chelation therapy needs to be instituted.  In general recommendations on chelation, today, are usually made according to the Cardiac Magnetic Resonance findings, if available.  With the advances in the latter technology and the ability to tailor chelation therapy according to the MRI findings as well as the availability of three iron chelators, together with

Combinational chelation therapy abrogates lead-induced neurodegeneration in rats

International Nuclear Information System (INIS)

Pachauri, Vidhu; Saxena, Geetu; Mehta, Ashish; Mishra, Deepshikha; Flora, Swaran J.S.

2009-01-01

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

Iminodiacetic acid functionalised organopolymer monoliths: application to the separation of metal cations by capillary high-performance chelation ion chromatography.

Science.gov (United States)

Moyna, Áine; Connolly, Damian; Nesterenko, Ekaterina; Nesterenko, Pavel N; Paull, Brett

2013-03-01

Lauryl methacrylate-co-ethylene dimethacrylate monoliths were polymerised within fused silica capillaries and subsequently photo-grafted with varying amounts of glycidyl methacrylate (GMA). The grafted monoliths were then further modified with iminodiacetic acid (IDA), resulting in a range of chelating ion-exchange monoliths of increasing capacity. The IDA functional groups were attached via ring opening of the epoxy group on the poly(GMA) structure. Increasing the amount of attached poly(GMA), via photo-grafting with increasing concentrations of GMA, from 15 to 35%, resulted in a proportional and controlled increase in the complexation capacity of the chelating monoliths. Scanning capacitively coupled contactless conductivity detection (sC(4)D) was used to characterise and verify homogenous distribution of the chelating ligand along the length of the capillaries non-invasively. Chelation ion chromatographic separations of selected transition and heavy metals were carried out, with retention factor data proportional to the concentration of grafted poly(GMA). Average peak efficiencies of close to 5,000 N/m were achieved, with the isocratic separation of Na, Mg(II), Mn(II), Co(II), Cd(II) and Zn(II) possible on a 250-mm-long monolith. Multiple monolithic columns produced to the same recipes gave RSD data for retention factors of ions). The monolithic chelating ion-exchanger was applied to the separation of alkaline earth and transition metal ions spiked in natural and potable waters.

Potentials and drawbacks of chelate-enhanced phytoremediation of soils

NARCIS (Netherlands)

Römkens, P.F.A.M.; Bouwman, L.A.; Japenga, J.; Draaisma, C.

2002-01-01

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

Mixed and chelated waste test programs with bitumen solidification

International Nuclear Information System (INIS)

Simpson, S.I.; Morris, M.; Vidal, H.

1988-01-01

This paper presents the results of bitumen solidification tests on mixed wastes and chelated wastes. The French Atomic Energy Commission (CEA) performed demonstration tests on radioactive wastes contaminated with chelating agents for Associated Technologies, Inc. (ATI). The chelated wastes were produced and concentrated by Commonwealth Edison Co. as a result of reactor decontamination at Dresden Nuclear Station, Unit 1. Law Engineering in Charlotte, N. C. produced samples and performed tests on simulated heavy metal laden radioactive waste (mixed) to demonstrate the quality of the bituminous product. The simulation is intended to represent waste produced at Oak Ridge National Labs operated by Martin-Marietta

Feasibility of tetracycline, a common antibiotic, as chelating agent for spectrophotometric determination of UO22+ after cloud point extraction

International Nuclear Information System (INIS)

Esra Bagda; Ebru Yabas; Nihat Karakus

2014-01-01

A cloud point extraction (CPE) procedure was presented for the preconcentration of UO 2 2+ ion in different water samples. Tetracycline (TC) is the second most widely used antibiotics in the world and is used as chelating agent. To the best of our knowledge, this is the first work that an antibiotic is used as a chelating agent for CPE of UO 2 2+ . Besides, the use of TC as complexing agent provides excellent chelating features. TC molecule has large numbers of functional groups (adjacent hydroxyl oxygen atoms and cyclohexanone oxygen atoms, amide groups) which can form stable complex with UO 2 2+ . After complexation with TC, UO 2 2+ ions were quantitatively recovered in Triton X-100 after cooling in the ice bath. 3.0 mL of acetate buffer was added to the surfactant-rich phase prior to its analysis by UV-Vis spectrophotometer. The influence of analytical parameters including pH, buffer volume, TC, Triton X-100 concentrations, bath temperature, incubation time were optimized. The effect of the matrix ions on the recovery of UO 2 2+ ions was investigated. The limit of detection was 0.0746 μg mL -1 along with enrichment factor of 14.3 with a R.S.D. of 3.6 %. The proposed procedure was applied to the analysis of various environmental water samples. On the other hand, the electronic distribution of TC molecule is investigated with their frontier molecular orbital density distributions. (author)

Screening of chelating ligands to enhance mercury accumulation from historically mercury-contaminated soils for phytoextraction.

Science.gov (United States)

Wang, Jianxu; Xia, Jicheng; Feng, Xinbin

2017-01-15

Screening of optimal chelating ligands which not only have high capacities to enhance plant uptake of mercury (Hg) from soil but also can decrease bioavailable Hg concentration in soil is necessary to establish a viable chemically-assisted phytoextraction. Therefore, Brassica juncea was exposed to historically Hg-contaminated soil (total Hg, 90 mg kg -1 ) to investigate the efficiency of seven chelating agents [ammonium thiosulphate, sodium thiosulphate, ammonium sulfate, ammonium chloride, sodium nitrate, ethylenediaminetetraacetic acid (EDTA), and sodium sulfite] at enhancing Hg phytoextraction; the leaching of bioavailable Hg caused by these chelating agents was also investigated. The Hg concentration in control (treated with double-distilled water) plant tissues was below 1 mg kg -1 . The remarkably higher Hg concentration was found in plants receiving ammonium thiosulphate and sodium sulfite treatments. The bioaccumulation factors and translocation factors of ammonium thiosulphate and sodium sulfite treatments were significantly higher than those of the other treatments. The more efficient uptake of Hg by plants upon treatment with ammonium thiosulphate and sodium sulfite compared to the other treatments might be explained by the formation of special Hg-thiosulphate complexes that could be preferentially taken up by the roots and transported in plant tissues. The application of sulfite significantly increased bioavailable Hg concentration in soil compared with that in initial soil and control soil, whereas ammonium thiosulphate significantly decreased bioavailable Hg concentration. The apparent decrease of bioavailable Hg in ammonium thiosulphate-treated soil compared with that in sodium sulfite-treated soil might be attributable to the unstable Hg-thiosulphate complexes formed between thiosulphate and Hg; they could react to produce less bioavailable Hg in the soil. The results of this study indicate that ammonium thiosulphate may be an optimal chelating

Different photoluminescent properties of binary and ternary europium chelates doped in PMMA

International Nuclear Information System (INIS)

Liu Hongguo; Park, Seongtae; Jang, Kiwan; Zhang Wansong; Seo, Hyo-Jin; Lee, Yong-Ill

2003-01-01

Two kinds of europium-β-diketone chelates, binary Eu(DBM) 3 and ternary Eu(DBM) 3 phen were doped in poly(methyl methacrylate) (PMMA). These chelates show very different photoluminescent (PL) behaviors: the hypersensitive 5 D 0 → 7 F 2 emission bands of Eu(DBM) 3 phen change slightly with the molar ratios, while those of Eu(DBM) 3 change obviously and regularly with the molar ratios. The results of the luminescent lifetimes of 5 D 0 levels show that the binary chelate exists as two kinds of species in the doped systems, and the lifetimes and contents of each species change with the molar ratios, while the ternary chelate exists as one kind of species in the doped systems. X-ray diffraction (XRD) patterns of the binary chelate doped systems give some diffraction peaks that are different from those of pure chelate and change with the molar ratios, indicating new kinds of crystal structures formed, and consequently, the first coordination sphere of Eu 3+ ion changes; while those of the ternary chelate doped systems just show amorphous diffraction halos of the host, indicating that the ternary chelate exist in an amorphous state and disperse well in the host. The FTIR spectra of PMMA also change gradually with increasing the molar ratios of the doped two kinds of chelates, and the XRD patterns show that the amorphous halos of PMMA in the doped systems are different from those of pure PMMA and change with the molar ratios, too, suggesting the interaction between the guest and the host

Chelating water-soluble polymers for waste minimization

International Nuclear Information System (INIS)

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

1996-01-01

Within the DOE complex and in industry there is a tremendous need for advanced metal ion recovery and waste minimization techniques. This project sought to employ capabilities for ligand-design and separations chemistry in which one can develop and evaluate water- soluble chelating polymers for recovering actinides and toxic metals from various process streams. Focus of this work was (1) to develop and select a set of water-soluble polymers suitable for a selected waste stream and (2) demonstrate this technology in 2 areas: removal of (a) actinides and toxic RCRA metals from waste water and (b) recovery of Cu and other precious metals from industrial process streams including from solid catalysts and aqueous waste streams. The R ampersand D was done in 4 phases for each of the 2 target areas: polymer synthesis for scaleup, equipment assembly, process demonstration at a DOE or industrial site, and advanced ligand/polymer synthesis. The TA- 50 site at Los Alamos was thought to be appropriate due to logistics and to its being representative of similar problems throughout the DOE complex

Low-temperature atmospheric oxidation of mixtures of titanium and carbon black or brown

International Nuclear Information System (INIS)

Elizarova, V.A.; Babaitsev, I.V.; Barzykin, V.V.; Gerusova, V.P.; Rozenband, V.I.

1984-01-01

This article reports on the thermogravimetric investigation of mixtures of titanium no. 2 and carbon black with various mass carbon contents. Adding carbon black (as opposed to boron) to titanium leads to an increase in the rate of heat release of the oxidation reaction. An attempt is made to clarify the low-temperature oxidation mechanism of titanium mixtures in air. An x-ray phase and chemical (for bound carbon) analysis of specimens of a stoichiometric Ti + C mixture after heating in air to a temperature of 650 0 C at the rate of 10 0 /min was conducted. The results indicate that the oxidation of the titanium-carbon mixture probably proceeds according to a more complex mechanism associated with the transport of the gaseous carbon oxidation products and their participation in the titanium oxidation

Antioxidant, Iron-chelating and Anti-glucosidase Activities of Typha ...

African Journals Online (AJOL)

Iron chelating activity was assessed using a ferrozine-based assay. Anti- glucosidase activity was determined using 4-nitrophenyl ... flavonoid (TF) content was determined based an aluminum chloride colorimetric assay [6]. TF content was ..... Dietary iron restriction or iron chelation protects from diabetes and loss of β-cell.

Olivine-type cathode for rechargeable batteries: Role of chelating agents

International Nuclear Information System (INIS)

Kandhasamy, Sathiyaraj; Singh, Pritam; Thurgate, Stephen; Ionescu, Mihail; Appadoo, Dominique; Minakshi, Manickam

2012-01-01

Highlights: ► Olivine powder was synthesized by sol–gel method using a range of chelating agents. ► Role of chelating agents in olivine cathode was investigated for battery application. ► Battery was fabricated with olivine cathode, Zn anode and aqueous electrolyte. ► Synergetic effect of additives (CA + TEA + PVP) led to improved storage capacity. - Abstract: Olivine (LiCo 1/3 Mn 1/3 Ni 1/3 PO 4 ) powders were synthesized at 550–600 °C for 6 h in air by a sol–gel method using multiple chelating agents and used as a cathode material for rechargeable batteries. Range of chelating agents like a weak organic acid (citric acid – CA), emulsifier (triethanolamine – TEA) and non-ionic surfactant (polyvinylpyrrolidone – PVP) in sol–gel wet chemical synthesis were used. The dependence of the physicochemical properties of the olivine powders such as particle size, morphology, structural bonding and crystallinity on the chelating agent was extensively investigated. Among the chelating agents used, unique cycling behavior (75 mAh/g after 25 cycles) is observed for the PVP assisted olivine. This is due to volumetric change in trapped organic layer for first few cycles. The trapped organic species in the electrode–electrolyte interface enhances the rate of lithium ion diffusion with better capacity retention. In contrast, CA and TEA showed a gradual capacity fade of 30 and 38 mAh/g respectively after multiple cycles. The combination of all the three mixed chelating agents showed an excellent electrochemical behavior of 100 mAh/g after multiple cycles and the synergistic effect of these agents are discussed.

Thermogravimetric investigations of vanadium complexes

International Nuclear Information System (INIS)

Bechmann, W.; Uhlemann, E.; Ludwig, W.

1987-01-01

Extensive studies on oxovanadium(IV) and (V) complexes with bidentate chelating ligands include thermogravimetric investigations. TG, DTG, and DTA data provide additional facts to redox behaviour and stability of the complexes. These data also allow a critical appreciation of the given melting temperatures. (author)

Synthesis, characterization and ion- exchange study of poly[(2,4-dihydroxy benzophenone)butylene] resin and its poly chelates with transition metals

International Nuclear Information System (INIS)

Joshi, J. D.; Patel, N.B.; Patel, S. D.

2006-01-01

The polymeric ligand poly[(2,4-dihydroxy benzophenone)butylene] H(DHBP-BD) forms 1 :2 metal-ligand complexes with Ni(ll), Co(ll), Cu(ll) and Zn(ll). The polymeric ligand and its poly chelates were characterized on the basis of elemental analyses, magnetic susceptibilities, IR-spectroscopy, UV-visible spectra, NMR, thermogravimetric analyses. The molecular weight of resin was determined using number average molecular weight (M n ) by vapour pressure osmometry method. The stereochemistry in case of the Cu(ll) poly chelate is square-planar, tetrahedral for Zn(ll) and octahedral for Ni(ll) and Co(ll). The stereochemistry in each chelate is proposed on the basis of magnetic susceptibilities and electronic spectra. The IR spectra show that the bidentate ligand coordinates through the oxygen atom of the carbonyl and phenolic group with replacement of hydrogen by metal ions, respectively. All the chelates are paramagnetic in nature except the Zn(ll) chelate which is diamagnetic. The ion-exchange study of the prepared resin was checked by batch equilibration method with selected metal ions [Cu(ll), Ni(ll), Fe(lll) and UO 2 2+( VI)] at varying electrolyte concentration, pH and time. It is found that, resin can be used as an ion-exchanger

Titanium metal: extraction to application

Energy Technology Data Exchange (ETDEWEB)

Gambogi, Joseph (USGS, Reston, VA); Gerdemann, Stephen J.

2002-09-01

In 1998, approximately 57,000 tons of titanium metal was consumed in the form of mill products (1). Only about 5% of the 4 million tons of titanium minerals consumed each year is used to produce titanium metal, with the remainder primarily used to produce titanium dioxide pigment. Titanium metal production is primarily based on the direct chlorination of rutile to produce titanium tetrachloride, which is then reduced to metal using the Kroll magnesium reduction process. The use of titanium is tied to its high strength-to-weight ratio and corrosion resistance. Aerospace is the largest application for titanium. In this paper, we discuss all aspects of the titanium industry from ore deposits through extraction to present and future applications. The methods of both primary (mining of ore, extraction, and purification) and secondary (forming and machining) operations will be analyzed. The chemical and physical properties of titanium metal will be briefly examined. Present and future applications for titanium will be discussed. Finally, the economics of titanium metal production also are analyzed as well as the advantages and disadvantages of various alternative extraction methods.

Mixed ligand chelate therapy for plutonium and toxic metals from energy power production. Final report, April 15, 1977-October 14, 1980

International Nuclear Information System (INIS)

Schubert, J.

1980-01-01

The results of experiments are summarized on the ability of combinations of chelating agents to modify the genotoxicity or tissue distributions. The mutagenicities of Cr and of chelating agents were determined. The metals described in the report are Pu(IV), Cd(II), Cr(III), and Cr(VI). Accurate measurements were made of the ability of CaNa 2 EDTA, CaNa 3 DTPA, and DMPS to reduce mortality in mice given doses (i.p.) of CdCl 2 well above the 100% lethal level. The efficacy in terms of the mmoles/kg needed to reduce the mortality was: DTPA > EDTA > DMPS. The combination of DTPA + DMPS proved most promising though little evidence for mixed complex formation was noted. Potentiometric titration studies the case of Pu(IV) a few combinations proved effective, but only when given shortly after Pu administration and then only in the liver but not the skeleton. It is recommended that metabolically stable chelating agents be used in combinations, especially for those combinations which may form very stable mixed ligand chelates

Metal-chelating active packaging film enhances lysozyme inhibition of Listeria monocytogenes.

Science.gov (United States)

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

2014-07-01

Several studies have demonstrated that metal chelators enhance the antimicrobial activity of lysozyme. This study examined the effect of metal-chelating active packaging film on the antimicrobial activity of lysozyme against Listeria monocytogenes. Polypropylene films were surface modified by photoinitiated graft polymerization of acrylic acid (PP-g-PAA) from the food contact surface of the films to impart chelating activity based on electrostatic interactions. PP-g-PAA exhibited a carboxylic acid density of 113 ± 5.4 nmol cm(-2) and an iron chelating activity of 53.7 ± 9.8 nmol cm(-2). The antimicrobial interaction of lysozyme and PP-g-PAA depended on growth media composition. PP-g-PAA hindered lysozyme activity at low ionic strength (2.48-log increase at 64.4 mM total ionic strength) and enhanced lysozyme activity at moderate ionic strength (5.22-log reduction at 120 mM total ionic strength). These data support the hypothesis that at neutral pH, synergy between carboxylate metal-chelating films (pKa(bulk) 6.45) and lysozyme (pI 11.35) is optimal in solutions of moderate to high ionic strength to minimize undesirable charge interactions, such as lysozyme absorption onto film. These findings suggest that active packaging, which chelates metal ions based on ligand-specific interactions, in contrast to electrostatic interactions, may improve antimicrobial synergy. This work demonstrates the potential application of metal-chelating active packaging films to enhance the antimicrobial activity of membrane-disrupting antimicrobials, such as lysozyme.

Titanium disilicide formation by sputtering of titanium on heated silicon substrate

Science.gov (United States)

Tanielian, M.; Blackstone, S.

1984-09-01

We have sputter deposited titanium on bare silicon substrates at elevated temperatures. We find that at a substrate temperature of about 515 °C titanium silicide is formed due to the reaction of the titanium with the Si. The resistivity of the silicide is about 15 μΩ cm and it is not etchable in a selective titanium etch. This process can have applications in low-temperature, metal-oxide-semiconductor self-aligned silicide formation for very large scale integrated

The influence of functional groups on the permeation and distribution of antimycobacterial rhodamine chelators.

Science.gov (United States)

Moniz, T; Leite, A; Silva, T; Gameiro, P; Gomes, M S; de Castro, B; Rangel, M

2017-10-01

We formerly hypothesized a mechanism whereby the antimycobacterial efficiency of a set of rhodamine labelled iron chelators is improved via the rhodamine fluorophore which enhances the chelators' permeation properties through membranes. To validate our hypothesis in a cellular context and to understand the influence of the structure of the fluorophore on the chelator's uptake and distribution within macrophages we now report comparative confocal microscopy studies performed with a set of rhodamine labelled chelators. We identify the functional groups of the chelator's framework that favor uptake by macrophages and conclude that the antimycobacterial effect is strongly related with the capacity of the chelator to distribute within the host cell and its compartments, a property that is closely related with the chelators' ability to interact with membranes. The quantification of the chelators' interaction with membranes was assessed through measurement of the corresponding partition constants in liposomes. The overall results support that the compounds which are preferentially taken up are the most efficient antimycobacterial chelators and for that reason we infer that the biological activity is modulated by the structural features of the fluorophore. Copyright © 2017 Elsevier Inc. All rights reserved.

Iron chelators ICL670 and 311 inhibit HIV-1 transcription

International Nuclear Information System (INIS)

Debebe, Zufan; Ammosova, Tatyana; Jerebtsova, Marina; Kurantsin-Mills, Joseph; Niu, Xiaomei; Charles, Sharroya; Richardson, Des R.; Ray, Patricio E.; Gordeuk, Victor R.; Nekhai, Sergei

2007-01-01

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

Bone marrow and chelatable iron in patients with protein energy ...

African Journals Online (AJOL)

chelatable iron is present and is excreted in the urine of children with kwashiorkor ... venous blood sample was drawn for routine biochemical and haematological .... storage.l.1:m In response to chelation, the kwashiorkor children excrete large ...

Pyclen Tri-n-butylphosphonate Ester as Potential Chelator for Targeted Radiotherapy: From Yttrium(III) Complexation to (90)Y Radiolabeling.

Science.gov (United States)

Le Fur, Mariane; Beyler, Maryline; Lepareur, Nicolas; Fougère, Olivier; Platas-Iglesias, Carlos; Rousseaux, Olivier; Tripier, Raphaël

2016-08-15

The Y(3+) complex of PCTMB, the tri-n-butyl phosphonate ester of pyclen (3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene), was synthesized as well as its Ho(3+) and Lu(3+) analogues. X-ray diffraction analyses revealed isomorphous dimeric M2(PCTMB)2·9H2O (M = Y, Ho, Lu) structures that crystallize in the centrosymmetric P1̅ triclinic space group. (1)H NMR and UV studies in aqueous solutions indicated that Y(3+) complexation is fast, being quantitative in 167 min at pH 3.8 and in 13 min at pH 5.5 (25 °C, acetate buffer, I = 0.150 M, [Y(3+)] = [PCTMB] = 0.2 mM). (1)H NMR DOSY and photon correlation spectroscopy experiments evidenced the formation of aggregates in chloroform with a bimodal distribution that changes slightly with concentration (11-24 and 240-258 nm). The behavior of the acid-assisted dissociation of the complex of Y(3+) with PCTMB was studied under pseudo-first-order conditions, and the half-life of the [Y(PCTMB)] complex in 0.5 M HCl at 25 °C was found to be 37 min, a value that decreases to 2.6 min in 5 M HCl. The Y(3+) complex of PCTMB is thermodynamically very stable, with a stability constant of log KY-PCTMB = 19.49 and pY = 16.7 measured by potentiometry. (90)Y complexation studies revealed fast radiolabeling kinetics; optimal radiolabeling conditions were obtained for (90)Y in acetate medium, PCTMB at 10(-4) to 10(-2) M in acetate buffer pH = 4.75, 15 min at 45-60 °C. In vitro stability studies in human serum showed that [(90)Y(PCTMB)] is quite stable, with about 90% of the activity still in the form of the radiotracer at 24 h and 80% from 48 h to 72 h. A comparison with other ligands such as PCTA, DOTA, and DTPA already used for in vivo application shows that [(90)Y(PCTMB)] is an interesting lipophilic and neutral analogue of these reference chelates for therapeutic applications in aqueous and nonaqueous media.

ELECTED PROBLEMS RELATED TO ENVIRONMENTAL HEAVY METALS EXPOSURE AND CHELATION THERAPY

Directory of Open Access Journals (Sweden)

Anna Skoczyńska

2010-09-01

Full Text Available Background: Exposure to heavy metals leads to functional and metabolic disturbances and many of them are included in pathogenesis of common diseases (arterial hypertension, atherosclerosis, neurodegenerative processes. In this context new therapeutic and prophylactic strategies are necessary. Patients diagnosed with chronic heavy metals intoxication usually require chelation to increase mobilisation of metals from tissues and elimination of them via urine. Acute poisoning with toxic metal may be difficult to diagnosis, especially in case of accidental intoxication or suicidal intention. Patients also require chelation after causative factor is identified. Objectives: To describe some problems connected with toxicity of metals poisoning and to review pharmacologic therapies that could have a role in poisoning with metals. Methods: A review of the literature was carried out and expert opinion expressed. Results/conclusion: Chelation is a common therapy in case of poisoning with toxic metals but it is satisfied only partially. A combined therapy with structurally different chelators or long-term acting chelators could become viable alternatives in the future. A combined therapy with an antioxidant plus chelator may be a good choice in patients chronically poisoned with metals. Exposure to lead should be taken into account during estimation of global cardiovascular risk.

Investment casting of beta titanium alloys for aerospace applications

International Nuclear Information System (INIS)

Wheeler, D.A.; Cianci, M.S.; Vogt, R.G.

1993-01-01

The process of investment casting offers the ability to produce complex titanium components with minimal finish machining, thereby reducing their overall manufacturing cost. While aerospace applications for cast titanium have focused primarily on alpha+beta alloys, recent interest in higher strength beta alloys has prompted an examination of their suitability for investment casting. In this paper, the processing characteristics and mechanical proper-ties of Ti-1 5V-3Cr-3Al-3Sn, Ti-3Al-8V-6Cr-4Mo-4Zr, and Ti-15Mo-3Nb-3Al-0.2Si (wt.%) will be discussed. It will be shown that all three alloy compositions are readily processed using only slight modifications from current Ti-6Al-4V (wt.%) production operations. In addition, the mechanical properties of the cast product form can be manipulated through heat treatment and compare quite favorably with typical properties obtained in wrought beta titanium products. Finally, several demonstration castings are reviewed which illustrate the shape-making capabilities of the investment casting approach for beta titanium alloys

N-acetylcysteine protects rats with chronic renal failure from gadolinium-chelate nephrotoxicity.

Directory of Open Access Journals (Sweden)

Leonardo Victor Barbosa Pereira

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

EDTA chelation therapy for cardiovascular disease: a systematic review

Directory of Open Access Journals (Sweden)

Wu Ping

2005-11-01

Full Text Available Abstract Background Numerous practitioners of both conventional and complementary and alternative medicine throughout North America and Europe claim that chelation therapy with EDTA is an effective means to both control and treat cardiovascular disease. These claims are controversial, and several randomized controlled trials have been completed dealing with this topic. To address this issue we conducted a systematic review to evaluate the best available evidence for the use of EDTA chelation therapy in the treatment of cardiovascular disease. Methods We conducted a systematic review of 7 databases from inception to May 2005. Hand searches were conducted in review articles and in any of the trials found. Experts in the field were contacted and registries of clinical trials were searched for unpublished data. To be included in the final systematic review, the studies had to be randomized controlled clinical trials. Results A total of seven articles were found assessing EDTA chelation for the treatment of cardiovascular disease. Two of these articles were subgroup analyses of one RCT that looked at different clinical outcomes. Of the remaining five studies, two smaller studies found a beneficial effect whereas the other three exhibited no benefit for cardiovascular disease from the use of EDTA chelation therapy. Adverse effects were rare but those of note included a few cases of hypocalcemia and a single case of increased creatinine in a patient on the EDTA intervention. Conclusion The best available evidence does not support the therapeutic use of EDTA chelation therapy in the treatment of cardiovascular disease. Although not considered to be a highly invasive or harmful therapy, it is possible that the use of EDTA chelation therapy in lieu of proven therapy may result in causing indirect harm to the patient.

Chelation Treatment for Autism Spectrum Disorders: A Systematic Review

Science.gov (United States)

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

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…

Copper chelators: chemical properties and bio-medical applications.

Science.gov (United States)

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

2014-01-01

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.

Leaching of Titanium and Silicon from Low-Grade Titanium Slag Using Hydrochloric Acid Leaching

Science.gov (United States)

Zhao, Longsheng; Wang, Lina; Qi, Tao; Chen, Desheng; Zhao, Hongxin; Liu, Yahui; Wang, Weijing

2018-05-01

Acid-leaching behaviors of the titanium slag obtained by selective reduction of vanadium-bearing titanomagnetite concentrates were investigated. It was found that the optimal leaching of titanium and silicon were 0.7% and 1.5%, respectively. The titanium and silicon in the titanium slag were firstly dissolved in the acidic solution to form TiO2+ and silica sol, and then rapidly reprecipitated, forming hydrochloric acid (HCl) leach residue. Most of the silicon presented in the HCl leach residue as floccules-like silica gel, while most of the titanium was distributed in the nano-sized rod-like clusters with crystallite refinement and intracrystalline defects, and, as such, 94.3% of the silicon was leached from the HCl leach residue by alkaline desilication, and 96.5% of the titanium in the titanium-rich material with some rutile structure was then digested by the concentrated sulfuric acid. This provides an alternative route for the comprehensive utilization of titanium and silicon in titanium slag.

Mixed-ligand complexes of zirconium (IV) and uranium with salicylaldehyde and some heterocyclic azopyrazolones

International Nuclear Information System (INIS)

Amrallahi, A.H.

1994-01-01

Mixed-ligand complexes of Zr(IV) and U(IV) with salicylaldehyde (SA) and some heterocyclic azopyrazolenes have been studied spectrophotometrically. All formed chelates have ratio 1:1:1. The stoichiometry and stability of the binary mixed chelates been evaluated. Elemental analysis, molar conductance and IR spectra have been used for identification of solid mixed complexes. (author)

3,4,5-trihydroxybenzoic acid as chelating agent

International Nuclear Information System (INIS)

Agrawal, M.D.; Bhandari, C.S.; Dixit, M.K.; Sogani, N.C.

1976-01-01

Stability constants of praseodymium chelates of 3,4,5-trihydroxy sodium benzoate are determined by using Bjerrum-Calvin pH titration techniques at constant ionic strength 0.1M-sodium perchlorate and at 28+-0.1 0 C. Values calculated by different methods are in good agreement. The study reveals that during complexation only one proton of the ligand molecule is replaced by the metal and oxygen of adjacent phenolic group acts as a coordinating atom. IR and NMR spectral studies of the ligand reveal that one of the OH groups (in meta position to carboxylic group) remains free while two other phenolic groups are involved in intramolecular hydrogen bonding. One water molecule is found attached in crystalline gallic acid. (author)

Spectroscopic studies on Titanium ion binding to the apo lactoferrin

International Nuclear Information System (INIS)

Moshtaghie, A.A.; Ani, M.; Arabi, M.H.

2006-01-01

Titanium is a relatively abundant element that has found growing applications in medical science and recently some of Titanium compounds are introduced as anticancer drugs. In spite of very limited data which exist on the Titanium metabolism, some proteins might be involved in the mechanism of action of Titanium up to our knowledge, there is not any report in the literature concerning binding of Titanium to apo lactoferrin. Binding of apo lactoferrin with Ti(IV)-citrate was studied by spectroflourimeterey and spectrophotometery techniques under physiological conditions. The spectroflourimeteric studies revealed a significant fluorescence quenching, that indicated binding of apo lactoferrin with Ti(IV). The same reaction was monitored through spectrophotometry technique; this represents a characteristic UV difference band at 267 nm, which is different from lac-Fe (III). Titration studies how that lactoferrin specifically binds two moles Ti(IV) as complex with citrate per mol protein. Spectroflourimeterey and spectrophotometery techniques indicated that Ti(IV) ions cause a reduction (13%-14%) in binding of Fe(III) to lactoferrin. In overall, we may come to this conclusion that this element might be involved in the iron metabolism

Titanium and titanium alloys: fundamentals and applications

National Research Council Canada - National Science Library

Leyens, C; Peters, M

2003-01-01

... number of titanium alloys have paved the way for light metals to vastly expand into many industrial applications. Titanium and its alloys stand out primarily due to their high specific strength and excellent corrosion resistance, at just half the weight of steels and Ni-based superalloys. This explains their early success in the aerospace and the...

A review of pitfalls and progress in chelation treatment of metal poisonings.

Science.gov (United States)

Andersen, Ole; Aaseth, Jan

2016-12-01

Most acute and chronic human metal poisonings are due to oral or inhalation exposure. Almost 80% of published animal experiments on chelation in metal poisoning used single or repeated intraperitoneal, intramuscular or intravenous administration of metal and chelator, impeding extrapolation to clinical settings. Intramuscular administration of dimercaptopropanol (BAL) has until now been used in acute arsenic, lead, and mercury poisonings, but repeated BAL administration increased the brain uptake of As, Pb and Hg in experimental animals. Also, diethyl dithiocarbamate (DDC) has been used as antidote in acute experimental animal parenteral Cd poisoning, and both DDC and tetraethylthiuram disulfide (TTD, disulfiram, Antabuse) have been used in nickel allergic patients. However, even one dose of DDC given immediately after oral Cd or Ni increased their brain uptake considerably. The calcium salt of ethylenediamminetetraacetic acid (CaEDTA) but not dimercaptosuccinic acid (DMSA) increased the brain uptake of Pb. In oral Cd or Hg poisoning, early oral administration of DMSA or dimercaptopropane sulfonate (DMPS) increased survival and reduced intestinal metal uptake. Oral administration of Prussian Blue or resins with fixed chelating groups that are not absorbed offer chelation approaches for decorporation after oral exposure to various metals. Diethylenetriaminepentaacetic acid (DTPA) nebulizers for pulmonary chelation after inhalation exposure need further development. Also, combined chelation with more than one compound may offer extensive advances. Solid knowledge on the chemistry of metal chelates together with relevant animal experiments should guide development of chelation procedures to alleviate and not aggravate the clinical status of poisoned patients. Copyright © 2016 Elsevier GmbH. All rights reserved.

Solvent extraction studies of indium-mixed chelates with β-diketones in benzene media

International Nuclear Information System (INIS)

Sudersanan, M.; Sundaram, A.K.

1975-01-01

Mixed chelate formation of indium with several β-diketones has been studied in benzene media. The extraction of indium by benzoyltrifluoroacetone (BFA) and furoyltrifluoroacetone (FFA) has been carried out as a function of pH and concentration of the ligand to ascertain the nature of the complexes. The extraction of indium by a mixture of β-diketones, viz., BFA-benzoylacetone(BA), BFA-dibenzoylmethene (DBM), FFA-BA, FFA-DBM, FFA-BFA and DBM-BA has also been studied as a function of the solution parameters. The nature of the mixed complexes formed as well as their equilibrium constants, statistical and stabilisation constants have been evaluated. (author)

Potentiometric studies on mixed-ligand chelates of uranyl ion with carboxylic acid phenolic acids

International Nuclear Information System (INIS)

Bandiwadekar, S.P.; Chavar, A.M.

1988-01-01

Mixed ligand complexes of UO 2 2+ with bidentate carboxylic and phenolic acids have been studied potentiometrically at 30 ± 0.1degC and μ=0.2M (NaClO 4 ). 1:1 and 1:2 complexes of UO 2 2+ with phthalic acid (PTHA), maleic acid (MAE), malonic acid (MAL), quinolinic acid (QA), 5-sulphosalicylic acid (5-SSA), salicylic acid (SA), and only 1:1 complexes in the case of mandelic acid (MAD) have been detected. The formation of 1:1:1 mixed ligand complexes has been inferred from simultaneous equilibria in the present study. The values of ΔlogK, Ksub(DAL), Ksub(2LA) or Ksub(2AL) for the ternary complexes have been calculated. The stabilities of mixed ligand complexes depend on the size of the chelate ring and the stabilities of the binary complexes. (author). 15 refs

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

Directory of Open Access Journals (Sweden)

Gloria Miller

2008-12-01

Full Text Available 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 μm filter and quantified by inductively coupled plasma-optical emission spectrometry (ICP-OES to determine soluble Pb concentrations. Results revealed that EDTA was the most effective in bringing Pb into solution, and that maximum solubility was reached 6 days after chelate amendment. Additionally, a greenhouse experiment was conducted by planting Sesbania seeds in plastic tubes containing top soil and peat (2:1, v:v spiked with various levels (0, 1000, 2000 mg Pb/kg dry soil of lead nitrate. At six weeks after emergence, aqueous solutions of EDTA and/or HAc (in a 1:1 ratio

Inhibitors for the corrosion of reactive metals: titanium and zirconium and their alloys in acid media

International Nuclear Information System (INIS)

Petit, J.A.; Chatainier, G.; Dabosi, F.

1981-01-01

The search for effective corrosion inhibitors for titanium and zirconium in acid media is growing because of the considerable increase in the use of these materials in chemical process equipment. It still remains limited, as appears from this review, because of the exceptionally high corrosion resistance of the metals. Titanium has received the greater attention. Its corrosion rate can be lowered by introduction in the medium of multivalent ions, inorganic and organic oxidants. Care should be taken to hold the concentration at a level exceeding some critical value, otherwise the corrosion rate increases. Complexing organic agents do not show such hazardous behaviour. The very rapid corrosion of titanium and zirconium in fluoride media may be lessened by complexing the fluoride ions. Though rarely encountered, localized corrosion may be avoided by using inhibitors. In some cases good corrosion inhibitors for titanium are dissolution accelerators for zirconium. (author)

Synthesis of Titanium Oxycarbide from Titanium Slag by Methane-Containing Gas

Science.gov (United States)

Dang, Jie; Fatollahi-Fard, Farzin; Pistorius, Petrus Christiaan; Chou, Kuo-Chih

2018-02-01

In this study, reaction steps of a process for synthesis of titanium oxycarbide from titanium slag were demonstrated. This process involves the reduction of titanium slag by a methane-hydrogen-argon mixture at 1473 K (1200 °C) and the leaching of the reduced products by hydrofluoric acid near room temperature to remove the main impurity (Fe3Si). Some iron was formed by disproportionation of the main M3O5 phase before gaseous reduction started. Upon reduction, more iron formed first, followed by reduction of titanium dioxide to suboxides and eventually oxycarbide.

Bis-phosphonate sequestering agents. Synthesis and preliminary evaluation for in vitro and in vivo uranium(VI) chelation

Energy Technology Data Exchange (ETDEWEB)

Sawicki, M.; Lecercle, D.; Taran, F. [CEA Saclay, IBiTecS, Serv Chim Bioorgan et Marquage, F-91191 Gif Sur Yvette (France); Grillon, G.; Le Gall, B.; Serandour, A.L.; Poncy, J.L. [CEA, DSV, DRR, Lab Radiotoxicol, F-91680 Bruyeres Le Chatel (France); Bailly, T.; Burgada, R.; Lecouvey, M.; Challeix, V. [CNRS, Lab Chim Struct Biomol, UMR 7033, F-93017 Bobigny (France); Leydier, A.; Pellet-Rostaing, S. [Univ Lyon 1, ICBMS, UMR 5246, Lab Catalyse et Synth Organ, F-69622 Villeurbanne (France); Ansoborlo, E. [CEA, DEN, DRCP, CETAMA, VRH Marcoule, F-30207 Bagnols Sur Ceze (France)

2008-07-01

A library of bis-phosphonate-based ligands was prepared using solution-phase parallel synthesis and tested for its uranium-binding properties. With the help of a screening method, based on a chromo-phoric complex displacement procedure, 23 dipodal and tripodal chelates bearing bis-phosphonate chelating functions were found to display very high affinity for the uranyl ion and were selected for evaluation of their in vivo uranyl-removal efficacy. Among them, 11 ligands induced a huge modification of the uranyl biodistribution by deviating the metal from kidney and bones to liver. Among the other ligands, the most potent was the dipodal bis-phosphonate 3C which reduced the retention of uranyl and increased its excretion by around 10% of the injected metal. (authors)

Pulse-radiolytic investigation of the reduction of titanium(III) ions in aqueous solutions

International Nuclear Information System (INIS)

Micic, O.I.; Nenadovic, M.T.

1979-01-01

The absorption spectrum and decay kinetics of intermediates formed by the reaction of titanium(III) ions with H atoms, hydrated electrons, and carboxyl radicals have been studied in aqueous solution using the pulse-radiolysis technique. The product of the reaction with H atoms in acid solution is a Ti 3+ -H hydride intermediate which decomposes by a first-order process with a half-life of ca. 3 s. Titanium(II) is formed by reaction with hydrated electrons and CO 2 H radicals. The absorption spectrum of titanium(II) and the kinetics of its reactions are reported and discussed. The formation of molecular hydrogen by reaction of Ti 2+ with water is suppressed by the other solutes in the solutions. Titanium(III) reacts with CO 2 H, CH 2 CO 2 H, and CH(CO 2 H) 2 radicals to give titanium-radical complexes. (author)

Carbonate effects on hexavalent uranium removal from water by nanocrystalline titanium dioxide

International Nuclear Information System (INIS)

Wazne, Mahmoud; Meng, Xiaoguang; Korfiatis, George P.; Christodoulatos, Christos

2006-01-01

A novel nanocrystalline titanium dioxide was used to treat depleted uranium (DU)-contaminated water under neutral and alkaline conditions. The novel material had a total surface area of 329 m 2 /g, total surface site density of 11.0 sites/nm 2 , total pore volume of 0.415 cm 3 /g and crystallite size of 6.0 nm. It was used in batch tests to remove U(VI) from synthetic solutions and contaminated water. However, the capacity of the nanocrystalline titanium dioxide to remove U(VI) from water decreased in the presence of inorganic carbonate at pH > 6.0. Adsorption isotherms, Fourier transform infrared (FTIR) spectroscopy, and surface charge measurements were used to investigate the causes of the reduced capacity. The surface charge and the FTIR measurements suggested that the adsorbed U(VI) species was not complexed with carbonate at neutral pH values. The decreased capacity of titanium dioxide to remove U(VI) from water in the presence of carbonate at neutral to alkaline pH values was attributed to the aqueous complexation of U(VI) by inorganic carbonate. The nanocrystalline titanium dioxide had four times the capacity of commercially available titanium dixoide (Degussa P-25) to adsorb U(VI) from water at pH 6 and total inorganic carbonate concentration of 0.01 M. Consequently, the novel material was used to treat DU-contaminated water at a Department of Defense (DOD) site

Surface-Induced Hybridization between Graphene and Titanium

Energy Technology Data Exchange (ETDEWEB)

Hsu, Allen L. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States).; Koch, Roland J. [Technische Universitat, Chemnitz (Germany); Ong, Mitchell T. [Stanford Univ., CA (United States); Fang, Wenjing [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Hofmann, Mario [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Kim, Ki Kang [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States).; Seyller, Thomas [Technische Universitat, Chemnitz (Germany); Dresselhaus, Mildred S. [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Reed, Evan J. [Stanford Univ., CA (United States); Kong, Jing [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States); Palacios, Tomás [MIT (Massachusetts Inst. of Technology), Cambridge, MA (United States)

2014-08-26

Carbon-based materials such as graphene sheets and carbon nanotubes have inspired a broad range of applications ranging from high-speed flexible electronics all the way to ultrastrong membranes. However, many of these applications are limited by the complex interactions between carbon-based materials and metals. In this work, we experimentally investigate the structural interactions between graphene and transition metals such as palladium (Pd) and titanium (Ti), which have been confirmed by density functional simulations. We find that the adsorption of titanium on graphene is more energetically favorable than in the case of most metals, and density functional theory shows that a surface induced p-d hybridization occurs between atomic carbon and titanium orbitals. This strong affinity between the two materials results in a short-range ordered crystalline deposition on top of graphene as well as chemical modifications to graphene as seen by Raman and X-ray photoemission spectroscopy (XPS). This induced hybridization is interface-specific and has major consequences for contacting graphene nanoelectronic devices as well as applications toward metal-induced chemical functionalization of graphene.

Titanium by design: TRIP titanium alloy

Science.gov (United States)

Tran, Jamie

Motivated by the prospect of lower cost Ti production processes, new directions in Ti alloy design were explored for naval and automotive applications. Building on the experience of the Steel Research Group at Northwestern University, an analogous design process was taken with titanium. As a new project, essential kinetic databases and models were developed for the design process and used to create a prototype design. Diffusion kinetic models were developed to predict the change in phase compositions and microstructure during heat treatment. Combining a mobility database created in this research with a licensed thermodynamic database, ThermoCalc and DICTRA software was used to model kinetic compositional changes in titanium alloys. Experimental diffusion couples were created and compared to DICTRA simulations to refine mobility parameters in the titanium mobility database. The software and database were able to predict homogenization times and the beta→alpha plate thickening kinetics during cooling in the near-alpha Ti5111 alloy. The results of these models were compared to LEAP microanalysis and found to be in reasonable agreement. Powder metallurgy was explored using SPS at GM R&D to reduce the cost of titanium alloys. Fully dense Ti5111 alloys were produced and achieved similar microstructures to wrought Ti5111. High levels of oxygen in these alloys increased the strength while reducing the ductility. Preliminary Ti5111+Y alloys were created, where yttrium additions successfully gettered excess oxygen to create oxides. However, undesirable large oxides formed, indicating more research is needed into the homogeneous distribution of the yttrium powder to create finer oxides. Principles established in steels were used to optimize the beta phase transformation stability for martensite transformation toughening in titanium alloys. The Olson-Cohen kinetic model is calibrated to shear strains in titanium. A frictional work database is established for common alloying

Chelating capture and magnetic removal of non-magnetic heavy metal substances from soil

OpenAIRE

Liren Fan; Jiqing Song; Wenbo Bai; Shengping Wang; Ming Zeng; Xiaoming Li; Yang Zhou; Haifeng Li; Haiwei Lu

2016-01-01

A soil remediation method based on magnetic beneficiation is reported. A new magnetic solid chelator powder, FS@IDA (core-shell Fe3O4@SiO2 nanoparticles coated with iminodiacetic acid chelators), was used as a reactive magnetic carrier to selectively capture non-magnetic heavy metals in soil by chelation and removal by magnetic separation. FS@IDA was prepared via inorganic-organic and organic synthesis reactions that generated chelating groups on the surface of magnetic, multi-core, core-shel...

Novel synergism by complex ligands in solvent extraction of rare earth metals(III) with β-diketones

International Nuclear Information System (INIS)

Imura, H.; Ebisawa, M.; Kato, M.; Ohashi, K.

2006-01-01

The extraction of rare earth metals(III) (RE) with hexafluoroacetylacetone (Hhfa) and 2-thenoyltrifluoroacetone (Htta) was studied in the presence of some cobalt(III) chelates such as tris(acetylacetonato)cobalt(III), tris(4-isopropyltropolonato)cobalt(III), tris(8-quinolinolato)cobalt(III), tris(8-quinolinethiolato)cobalt(III), and tris(diethyldithiocarbamato)cobalt(III) in benzene or toluene. The synergistic enhancement of the extraction of RE, especially of lanthanum(III) was found in all the systems. Therefore, those cobalt(III) chelates act as synergists or complex ligands. The equilibrium analysis and IR spectroscopic study were performed to evaluate the present synergistic mechanism. It was found that the RE-β-diketone chelates form 1:1 adducts, i.e., binuclear complexes, with the cobalt(III) chelates in the organic phase. The formation constants (β s,1 ) were determined and compared with those reported previously. The spectroscopic studies demonstrated that adducts have two different structures with inner- and outer-sphere coordination. In the former the cobalt(III) chelate directly coordinated to the RE ion and displaced the coordinated water molecules. In the latter the hydrogen-bonding was formed between the coordinating oxygen or sulfur atoms of cobalt(III) chelate and hydrogen atoms of the coordinated water molecules in the RE-β-diketone chelate. The types of the adducts are mainly due to the steric factors of the RE-β-diketone chelates and the cobalt(III) chelates

Titanium Analysis of Ilmenite Bangka by Spectrophotometric Method Using Perhidrol

International Nuclear Information System (INIS)

Rusydi-S

2004-01-01

Determination of titanium by spectrofotometric method using perhydrol has been done. The purpose of experiment is to find out the condition of titanium analysis of ilmenite by spectrophotometric method. The experiment parameter e c. analysis condition include the Ti-perhydrol complex spectrum, acidity of complex, perhydrol concentration, linearity, influence of anion, limit detection, interfere elements, application of the method using 40 SRM Standard and analysis for ilmenite samples. Result of experiments are spectrum of Ti-perhydrol complex at 410 nm, acidity of complex is the H 2 SO 4 2 M, perhydrol concentration is 0,24 %, the curve calibration is linier at 1-80 ppm, anion of PO 4 , NO 3 , Cl, CO 3 not be influence until 2000 ppm, limit detection is 0,30 ppm and Mo, V is interfere. The method which was aplicated to 40 SRM standard, shown that the content of Ti is 1580 ppm while the standard is 1600 ppm, and the content of Ti from ilmenite high grade samples is 31,46 % and low grade is 13,55 %. (author)

sup(113m)In chelate complexes

International Nuclear Information System (INIS)

Abram, S.; Abram, U.; Spies, H.; Muenze, R.

1985-01-01

A series of 7 indiumdialkyldithiocarbamates (R=ethyl, n-propyl, i-propyl, n-butyl, i-butyl, -(CH 2 ) 5 -, -(CH 2 ) 2 -O-(CH 2 ) 2 -) has been prepared by reacting InCl 3 with aqueous solutions of the ligands. The products have been investigated at various concentration levels. The properties of the products at the lower concentration levels have been studied by thin-layer chromatography, electrophoresis and by determination of the octanol/water partition. A comparison of the results with the behaviour of the well-characterized tris(dialkyldithiocarbamato)indium(III) complexes is given. (author)

Synergy and antagonism between iron chelators and antifungal drugs in Cryptococcus.

Science.gov (United States)

Lai, Yu-Wen; Campbell, Leona T; Wilkins, Marc R; Pang, Chi Nam Ignatius; Chen, Sharon; Carter, Dee A

2016-10-01

Fungal infections remain very difficult to treat, and developing new antifungal drugs is difficult and expensive. Recent approaches therefore seek to augment existing antifungals with synergistic agents that can lower the therapeutic dose, increase efficacy and prevent resistance from developing. Iron limitation can inhibit microbial growth, and iron chelators have been employed to treat fungal infections. In this study, chequerboard testing was used to explore combinations of iron chelators with antifungal agents against pathogenic Cryptococcus spp. with the aim of determining how disruption to iron homeostasis affects antifungal susceptibility. The iron chelators ethylenediaminetetraacetic acid (EDTA), deferoxamine (DFO), deferiprone (DFP), deferasirox (DSX), ciclopirox olamine and lactoferrin (LF) were paired with the antifungal agents amphotericin B (AmB), fluconazole, itraconazole, voriconazole and caspofungin. All chelators except for DFO increased the efficacy of AmB, and significant synergy was seen between AmB and LF for all Cryptococcus strains. Addition of exogenous iron rescued cells from the antifungal effect of LF alone but could not prevent inhibition by AmB + LF, indicating that synergy was not due primarily to iron chelation but to other properties of LF that were potentiated in the presence of AmB. Significant synergy was not seen consistently for other antifungal-chelator combinations, and EDTA, DSX and DFP antagonised the activity of azole drugs in strains of Cryptococcus neoformans var. grubii. This study highlights the range of interactions that can be induced by chelators and indicates that most antifungal drugs are not enhanced by iron limitation in Cryptococcus. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Labeling of monoclonal antibodies with a 67Ga-phenolic aminocarboxylic acid chelate. Part I. Chemistry and labeling technique.

Science.gov (United States)

Schuhmacher, J; Matys, R; Hauser, H; Maier-Borst, W; Matzku, S

1986-01-01

As a chelating agent for labeling antibodies (Abs) with metallic radionuclides, a propionic acid substituted ethylenediamine N,N'-di-[(o-hydroxyphenyl) acetic acid] (P-EDDHA), which tightly complexes 67Ga, was synthesized. The 67Ga-P-EDDHA chelate was coupled in aqueous solution to IgG at a molar ratio of 1:1 via carbodiimide. The average coupling yield was 15%. A specific activity of 4 mCi/mg IgG could be obtained with commercially supplied 67Ga. In vitro stability was evaluated in human serum at 37 degrees C and showed a half-life of about 120 h for the release of 67Ga from the labeled Ab during the initial phase of incubation. This in vitro halflife is similar to that measured for 111In-DTPA labeled Abs. Because of the high stability of the 67Ga-P-EDDHA chelate, the in vivo formation of radioactive labeled transferrin by transchelation, as described for 111In-DTPA labeled Abs, should, however, be reduced by this labeling technique.

Labeling of antibodies with a /sup 67/Ga-phenolic aminocarboxylic acid chelate. Pt. 1. Chemistry and labeling technique

Energy Technology Data Exchange (ETDEWEB)

Schuhmacher, J.; Matys, R.; Hauser, H.; Maier-Borst, W.; Matzku, S.

1986-11-01

As a chelating agent for labeling antibodies (Abs) with metallic radionuclides, a propionic acid substituted ethylenediamine N, N'-di-((o-hydroxyphenyl) acetic acid) (P-EDDHA), which tighly complexes /sup 67/Ga, was synthetized. The /sup 67/Ga-P-EDDHA chelate was coupled in aqueous solution to IgG at a molar ratio of 1:1 via carbodiimide. The average coupling yield was 15%. A specific activity of 4 mCi/mg IgG could be obtained with commercially supplied /sup 67/Ga. In vitro stability was evaluated in human serum at 37/sup 0/C and showed a half-life of about 120 h for the release of /sup 67/Ga from the labeled Ab during the initial phase of incubation. This in vitro halflife is similar to that measured for /sup 111/In-DTPA labeled Abs. Because of the high stability of the /sup 67/Ga-P-EDDHA chelate, the in vivo formation of radioactive lebeled transferrin by transchelation, as described for /sup 111/In-DTPA labeled Abs, should, however, be reduced by this labeling technique.

Corrosion of titanium and titanium alloys in spent fuel repository conditions - literature review

International Nuclear Information System (INIS)

Aho-Mantila, I.; Haenninen, H.; Aaltonen, P.; Taehtinen, S.

1985-03-01

The spent nuclear fuel is planned to be disposed in Finnish bedrock. The canister of spent fuel in waste repository is one barrier to the release of radionuclides. It is possible to choose a canister material with a known, measurable corrosion rate and to make it with thickness allowing corrosion to occur. The other possibility is to use a material which is nearly immune to general corrosion. In this second category there are titanium and titanium alloys which exhibit a very high degree of resistance to general corrosion. In this literature study the corrosion properties of unalloyed titanium, titanium alloyed with palladium and titanium alloyed with molybdenum and nickel are reviewed. The two titanium alloys own in addition to the excellent general corrosion properties outstanding properties against localized corrosion like pitting or crevice corrosion. Stress corrosion cracking and corrosion fatique of titanium seem not to be a problem in the repository conditions, but the possibilities of delayed cracking caused by hydrogen should be carefully appreciated. (author)

Synthesis of titanium oxide nanoparticles using DNA-complex as template for solution-processable hybrid dielectric composites

Energy Technology Data Exchange (ETDEWEB)

Ramos, J.C. [Center for Sustainable Materials Chemistry, 153 Gilbert Hall, Oregon State University, Corvallis, OR (United States); Mejia, I.; Murphy, J.; Quevedo, M. [Department of Materials Science and Engineering, University of Texas at Dallas, Dallas, TX (United States); Garcia, P.; Martinez, C.A. [Engineering and Technology Institute, Autonomous University of Ciudad Juarez, Ciudad Juarez, Chihuahua (Mexico)

2015-09-15

Highlights: • We developed a synthesis method to produce TiO{sub 2} nanoparticles using a DNA complex. • The nanoparticles were anatase phase (~6 nm diameter), and stable in alcohols. • Composites showed a k of 13.4, 4.6 times larger than the k of polycarbonate. • Maximum processing temperature was 90 °C. • Low temperature enables their use in low-voltage, low-cost, flexible electronics. - Abstract: We report the synthesis of TiO{sub 2} nanoparticles prepared by the hydrolysis of titanium isopropoxide (TTIP) in the presence of a DNA complex for solution processable dielectric composites. The nanoparticles were incorporated as fillers in polycarbonate at low concentrations (1.5, 5 and 7 wt%) to produce hybrid dielectric films with dielectric constant higher than thermally grown silicon oxide. It was found that the DNA complex plays an important role as capping agent in the formation and suspension stability of nanocrystalline anatase phase TiO{sub 2} at room temperature with uniform size (∼6 nm) and narrow distribution. The effective dielectric constant of spin-cast polycarbonate thin-films increased from 2.84 to 13.43 with the incorporation of TiO{sub 2} nanoparticles into the polymer host. These composites can be solution processed with a maximum temperature of 90 °C and could be potential candidates for its application in low-cost macro-electronics.

Femtomolar Ln(III) affinity in peptide-based ligands containing unnatural chelating amino acids.

Science.gov (United States)

Niedźwiecka, Agnieszka; Cisnetti, Federico; Lebrun, Colette; Delangle, Pascale

2012-05-07

The incorporation of unnatural chelating amino acids in short peptide sequences leads to lanthanide-binding peptides with a higher stability than sequences built exclusively from natural residues. In particular, the hexadentate peptide P(22), which incorporates two unnatural amino acids Ada(2) with aminodiacetate chelating arms, showed picomolar affinity for Tb(3+). To design peptides with higher denticity, expected to show higher affinity for Ln(3+), we synthesized the novel unnatural amino acid Ed3a(2) which carries an ethylenediamine triacetate side-chain and affords a pentadentate coordination site. The synthesis of the derivative Fmoc-Ed3a(2)(tBu)(3)-OH, with appropriate protecting groups for direct use in the solid phase peptide synthesis (Fmoc strategy), is described. The two high denticity peptides P(HD2) (Ac-Trp-Ed3a(2)-Pro-Gly-Ada(2)-Gly-NH(2)) and P(HD5) (Ac-Trp-Ada(2)-Pro-Gly-Ed3a(2)-Gly-NH(2)) led to octadentate Tb(3+) complexes with femtomolar stability in water. The position of the high denticity amino acid Ed3a(2) in the hexapeptide sequence appears to be critical for the control of the metal complex speciation. Whereas P(HD5) promotes the formation of polymetallic species in excess of Ln(3+), P(HD2) forms exclusively the mononuclear complex. The octadentate coordination of Tb(3+) by both P(HD) leads to total dehydration of the metal ion in the mononuclear complexes with long luminescence lifetimes (>2 ms). Hence, we demonstrated that unnatural amino acids carrying polyaminocarboxylate side-chains are interesting building blocks to design high affinity Ln-binding peptides. In particular the novel peptide P(HD2) forms a unique octadentate Tb(3+) complex with femtomolar stability in water and an improvement of the luminescence properties with respect to the trisaquo TbP(22) complex by a factor of 4.

Protracted chelate therapy after incorporation of plutonium 239 in rats

International Nuclear Information System (INIS)

Gemenetzis, E.

1976-01-01

The author has tested in how far 239 Pu can be mobilized by Ca and Zn, Desfenioxamin B(DFDA) and by combined doses of Ca-DTPA and DFDA. The pre-experiment covered the 239 Pu-metabolism in untreated male and female rats and the distribution in dependence of the way of application. If treatment is started immediately by multiple chelate doses, the first two injections play the main part in the decorporation of 239 Pu. The combination Ca-DTPA30 + DFDA30 μMol x kg -1 is proved to be the best means of decorporation for the whole body. The efficiency of another therapy depends essentially on the treatment used, a daily treatment showing the best effects. If treatment is started later with multiple chelate doses, the total decorporation efficiency is of less value, especially in the skeleton. Aequimolar doses of Ca-DTPA and Zn-DTPA have the same degree of efficiency. This indicates that during protracted chelate treatment starting later, Ca-DTPA could be substituted by the less toxic Zn-DTPA after incorporation of 239 Pu. These results show that intermittant administration of the week's dose is more efficient than a single chelate administration of the whole week's dose at once. Permanent chelate infusion does not seem necessary in any case since it has the same effect as 3 to 5 injections per week and is difficult to carry out in medical practice. Thus, it seems advisable to divide up the weekly dose into 3-5 injections. In case of a wound contamination, the efficiency of immediate intensive treatment depends on the 239 Pu compound used, on the chelate used, and on its dosage. (orig.) [de

Thermodynamic stability and kinetic inertness of a Gd-DTPA bisamide complex grafted onto gold nanoparticles.

Science.gov (United States)

Mogilireddy, Vijetha; Déchamps-Olivier, Isabelle; Alric, Christophe; Laurent, Gautier; Laurent, Sophie; Vander Elst, Luce; Muller, Robert; Bazzi, Rana; Roux, Stéphane; Tillement, Olivier; Chuburu, Françoise

2015-01-01

Gold nanoparticles coated by gadolinium (III) chelates (Au@DTDTPA) where DTDTPA is a dithiolated bisamide derivative of diethylenetriamine-N,N,N',N'',N''-pentaacetic acid (DTPA), constituted contrast agents for both X-ray computed tomography and magnetic resonance imaging. In an MRI context, highly stable Gd(3+) complexes are needed for in vivo applications. Thus, knowledge of the thermodynamic stability and kinetic inertness of these chelates, when grafted onto gold nanoparticles, is crucial since bisamide DTPA chelates are usually less suited for Gd(3+) coordination than DTPA. Therefore, these parameters were evaluated by means of potentiometric titrations and relaxivity measurements. The results showed that, when the chelates were grafted onto the nanoparticle, not only their thermodynamic stability but also their kinetic inertness were improved. These positive effects were correlated to the chelate packing at the nanoparticle surface that stabilized the corresponding Gd(3+) complexes and greatly enhanced their kinetic inertness. Copyright © 2014 John Wiley & Sons, Ltd.

Chelating capture and magnetic removal of non-magnetic heavy metal substances from soil

Science.gov (United States)

Fan, Liren; Song, Jiqing; Bai, Wenbo; Wang, Shengping; Zeng, Ming; Li, Xiaoming; Zhou, Yang; Li, Haifeng; Lu, Haiwei

2016-02-01

A soil remediation method based on magnetic beneficiation is reported. A new magnetic solid chelator powder, FS@IDA (core-shell Fe3O4@SiO2 nanoparticles coated with iminodiacetic acid chelators), was used as a reactive magnetic carrier to selectively capture non-magnetic heavy metals in soil by chelation and removal by magnetic separation. FS@IDA was prepared via inorganic-organic and organic synthesis reactions that generated chelating groups on the surface of magnetic, multi-core, core-shell Fe3O4@SiO2 (FS) nanoparticles. These reactions used a silane coupling agent and sodium chloroacetate. The results show that FS@IDA could chelate the heavy metal component of Cd, Zn, Pb, Cu and Ni carbonates, lead sulfate and lead chloride in water-insoluble salt systems. The resulting FS@IDA-Cd and FS@IDA-Pb chelates could be magnetically separated, resulting in removal rates of approximately 84.9% and 72.2% for Cd and Pb, respectively. FS@IDA could not remove the residual heavy metals and those bound to organic matter in the soil. FS@IDA did not significantly alter the chemical composition of the soil, and it allowed for fast chelating capture, simple magnetic separation and facilitated heavy metal elution. FS@IDA could also be easily prepared and reprocessed.

Chelating agents related to ethylenediamine bis(2-hydroxyphenyl)acetic acid (EDDHA): synthesis, characterization, and equilibrium studies of the free ligands and their Mg2+, Ca2+, Cu2+, and Fe3+ chelates.

Science.gov (United States)

Yunta, Felipe; García-Marco, Sonia; Lucena, Juan J; Gómez-Gallego, Mar; Alcázar, Roberto; Sierra, Miguel A

2003-08-25

Iron chelates such as ethylenediamine-N,N'-bis(2-hydroxyphenyl)acetic acid (EDDHA) and their analogues are the most efficient soil fertilizers to treat iron chlorosis in plants growing in calcareous soils. EDDHA, EDDH4MA (ethylenediamine-N,N'-bis(2-hydroxy-4-methylphenyl)acetic acid), and EDDCHA (ethylenediamine-N,N'-bis(2-hydroxy-5-carboxyphenyl)acetic acid) are allowed by the European directive, but also EDDHSA (ethylenediamine-N,N'-bis(2-hydroxy-5-sulfonylphenyl)acetic acid) and EDDH5MA (ethylenediamine-N,N'-bis(2-hydroxy-5-methylphenyl)acetic acid) are present in several commercial iron chelates. In this study, these chelating agents as well as p,p-EDDHA (ethylenediamine-N,N'-bis(4-hydroxyphenyl)acetic acid) and EDDMtxA (ethylenediamine-N,N'-bis(2-metoxyphenyl)acetic acid) have been obtained following a new synthetic pathway. Their chemical behavior has been studied to predict the effect of the substituents in the benzene ring on their efficacy as iron fertilizers for soils above pH 7. The purity of the chelating agents has been determined using a novel methodology through spectrophotometric titration at 480 nm with Fe(3+) as titrant to evaluate the inorganic impurities. The protonation constants were determined by both spectrophotometric and potentiometric methods, and Ca(2+) and Mg(2+) stability constants were determined from potentiometric titrations. To establish the Fe(3+) and Cu(2+) stability constants, a new spectrophotometric method has been developed, and the results were compared with those reported in the literature for EDDHA and EDDHMA and their meso- and rac-isomers. pM values have been also determined to provide a comparable basis to establish the relative chelating ability of these ligands. The purity obtained for the ligands is higher than 87% in all cases and is comparable with that obtained by (1)H NMR. No significant differences have been found among ligands when their protonation and stability constants were compared. As expected, no Fe(3

Heavy metal displacement in chelate-irrigated soil during phytoremediation

Science.gov (United States)

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

2003-03-01

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.

A study on complex formation of cadmium (II) ions, 9

International Nuclear Information System (INIS)

Matsui, Haruo

1984-01-01

Formation constants of cadmium (11) complexes with dicarboxylic acids such as oxalic, malonic, methylmalonic, succinic, and glutaric acids were determined in aqueous solutions containing 3 mol.dm -3 LiClO 4 as a constan ionic medium at 25 0 C by potentiometric titrations. It was reported in the previous works that cadmium (11)- aspartic acid complexes contained two chelate rings. However, a problem remained whether the second chelate ring could be formed by six membered-ring containing -O-Cd-N- bond or by seven membered-ring containing -O-Cd-O- bond. The results of the present work suggested that it would be formed by a six membered ring. Cadmium (11) ions were coordinated with a carboxylic group of the dicarboxylic acids studied, and formed no chelate ring within the complexes. The white precipitate appeared in the solution containing cadmium (11) ion and oxalic acid, in the pH range below 3.0, therefore, the chelate formation was not ascertained in this case. The formation constants, log βsub(pr)= log([Cdsub(p)Lsub(r)sup((2p-2r)+)]/([Cd 2+ ]sup(p)[L 2- ]sup(r))), of the complexes were: log β 11 = 1.98, log β 12 = 3.05 for cadmium (11)-malonic acid; log β 11 = 2.28, log β 12 = 3.06 for cadmium (11)-methylmalonic acid; log β 11 = 1.78, log β 12 = 3.08 for cadmium (11)-succinic acid; log β 11 = 1.85, log β 12 = 3.28 for cadmium (11)-glutaric acid complexes. (author)

Characterization of commercial iron chelates and their behavior in an alkaline and calcareous soil.

Science.gov (United States)

Cantera, Rodrigo G; Zamarreño, Angel M; García-Mina, José M

2002-12-18

Iron deficiency is a common problem for many plants grown in alkaline and calcareous soils. To correct this problem, iron is supplied to plants as chelates. Several iron chelates are sold under diverse trademarks with different characteristics. This work evaluated 18 commercial products containing the most representative chelated iron sources used in agricultural practice in Spain when the study was done, namely the ferric chelates of EDDHA, EDDHMA, EDDCHA, EDDHSA, EDTA, and DTPA. The chelates were comprehensively characterized and quantitated by several techniques, including several chromatographic methods. Iron and chelate dynamics in soil were also studied in a model alkaline and calcareous soil. Results indicate that, in this model soil, among the different iron compounds studied only FeEDDHA and analogues have the capacity to maintain soluble iron in soil solution over time. These results are in agreement with general experience under field conditions. Furthermore, among the different ortho-ortho isomers of FeEDDHA's, FeEDDHSA and FeEDDCHA showed greater capacity than FeEDDHA and FeEDDHMA to maintain the chelated iron in soil solution over time.

Chelation therapy and cardiovascular disease: connecting scientific silos to benefit cardiac patients.

Science.gov (United States)

Peguero, Julio G; Arenas, Ivan; Lamas, Gervasio A

2014-08-01

Medical practitioners have treated atherosclerotic disease with chelation therapy for over 50 years. Lack of strong of evidence led conventional practitioners to abandon its use in the 1960s and 1970s. This relegated chelation therapy to complementary and alternative medicine practitioners, who reported good anecdotal results. Concurrently, the epidemiologic evidence linking xenobiotic metals with cardiovascular disease and mortality gradually accumulated, suggesting a plausible role for chelation therapy. On the basis of the continued use of chelation therapy without an evidence base, the National Institutes of Health released a Request for Applications for a definitive trial of chelation therapy. The Trial to Assess Chelation Therapy (TACT) was formulated as a 2 × 2 factorial randomized controlled trial of intravenous EDTA-based chelation vs. placebo and high-dose oral multivitamins and multiminerals vs. oral placebo. The composite primary endpoint was death, reinfarction, stroke, coronary revascularization, or hospitalization for angina. A total of 1708 post-MI patients who were 50 years or older with a creatinine of 2.0 or less were enrolled and received 55,222 infusions of disodium EDTA or placebo with a median follow-up of 55 months. Patients were on evidence-based post-MI medications including statins. EDTA proved to be safe. EDTA chelation therapy reduced cardiovascular events by 18%, with a 5-year number needed to treat (NNT) of 18. Prespecified subgroup analysis revealed a robust benefit in patients with diabetes mellitus with a 41% reduction in the primary endpoint (5-year NNT = 6.5), and a 43% 5-year relative risk reduction in all-cause mortality (5-year NNT = 12). The magnitude of benefit is such that it suggests urgency in replication and implementation, which could, due to the excellent safety record, occur simultaneously. Copyright © 2014 Elsevier Inc. All rights reserved.

Engineering an antibody with picomolar affinity to DOTA chelates of multiple radionuclides for pretargeted radioimmunotherapy and imaging

Energy Technology Data Exchange (ETDEWEB)

Orcutt, Kelly Davis; Slusarczyk, Adrian L. [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Cieslewicz, Maryelise [Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Ruiz-Yi, Benjamin [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Bhushan, Kumar R. [Division of Hematology/Oncology, Beth Israel Deaconess Medical Center, Boston, MA 02215 (United States); Frangioni, John V. [Division of Hematology/Oncology, Beth Israel Deaconess Medical Center, Boston, MA 02215 (United States); Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA 02215 (United States); Wittrup, K. Dane, E-mail: wittrup@mit.ed [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

2011-02-15

Introduction: In pretargeted radioimmunotherapy (PRIT), a bifunctional antibody is administered and allowed to pre-localize to tumor cells. Subsequently, a chelated radionuclide is administered and captured by cell-bound antibody while unbound hapten clears rapidly from the body. We aim to engineer high-affinity binders to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) chelates for use in PRIT applications. Methods: We mathematically modeled antibody and hapten pharmacokinetics to analyze hapten tumor retention as a function of hapten binding affinity. Motivated by model predictions, we used directed evolution and yeast surface display to affinity mature the 2D12.5 antibody to DOTA, reformatted as a single chain variable fragment (scFv). Results: Modeling predicts that for high antigen density and saturating bsAb dose, a hapten-binding affinity of 100 pM is needed for near-maximal hapten retention. We affinity matured 2D12.5 with an initial binding constant of about 10 nM to DOTA-yttrium chelates. Affinity maturation resulted in a 1000-fold affinity improvement to biotinylated DOTA-yttrium, yielding an 8.2{+-}1.9 picomolar binder. The high-affinity scFv binds DOTA complexes of lutetium and gadolinium with similar picomolar affinity and indium chelates with low nanomolar affinity. When engineered into a bispecific antibody construct targeting carcinoembryonic antigen, pretargeted high-affinity scFv results in significantly higher tumor retention of a {sup 111}In-DOTA hapten compared to pretargeted wild-type scFv in a xenograft mouse model. Conclusions: We have engineered a versatile, high-affinity, DOTA-chelate-binding scFv. We anticipate it will prove useful in developing pretargeted imaging and therapy protocols to exploit the potential of a variety of radiometals.

Chitosan patterning on titanium alloys

OpenAIRE

Gilabert Chirivella, Eduardo; Pérez Feito, Ricardo; Ribeiro, Clarisse; Ribeiro, Sylvie; Correia, Daniela; González Martin, María Luisa; Manero Planella, José María; Lanceros Méndez, Senentxu; Gallego Ferrer, Gloria; Gómez Ribelles, José Luis

2017-01-01

Titanium and its alloys are widely used in medical implants because of their excellent properties. However, bacterial infection is a frequent cause of titanium-based implant failure and also compromises its osseointegration. In this study, we report a new simple method of providing titanium surfaces with antibacterial properties by alternating antibacterial chitosan domains with titanium domains in the micrometric scale. Surface microgrooves were etched on pure titanium disks at i...

Controlling lipid oxidation via a biomimetic iron chelating active packaging material.

Science.gov (United States)

Tian, Fang; Decker, Eric A; Goddard, Julie M

2013-12-18

Previously, a siderophore-mimetic metal chelating active packaging film was developed by grafting poly(hydroxamic acid) (PHA) from the surface of polypropylene (PP) films. The objective of the current work was to demonstrate the potential applicability of this PP-g-PHA film to control iron-promoted lipid oxidation in food emulsions. The iron chelating activity of this film was investigated, and the surface chemistry and color intensity of films were also analyzed after iron chelation. In comparison to the iron chelating activity in the free Fe(3+) solution, the PP-g-PHA film retained approximately 50 and 30% of its activity in nitrilotriacetic acid (NTA)/Fe(3+) and citric acid/Fe(3+) solutions, respectively (pH 5.0), indicating a strong chelating strength for iron. The ability of PP-g-PHA films to control lipid oxidation was demonstrated in a model emulsion system (pH 3.0). PP-g-PHA films performed even better than ethylenediaminetetraacetic acid (EDTA) in preventing the formation of volatile oxidation products. The particle size and ζ potential results of emulsions indicated that PP-g-PHA films had no adverse effects on the stability of the emulsion system. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis suggested a non-migratory nature of the PP-g-PHA film surface. These results suggest that such biomimetic, non-migratory metal chelating active packaging films have commercial potential in protecting foods against iron-promoted lipid oxidation.

IRON CHELATION THERAPY IN THALASSEMIA SYNDROMES

Directory of Open Access Journals (Sweden)

Paolo Cianciulli

2009-06-01

Full Text Available Transfusional hemosiderosis is a frequent complication in patients with transfusion dependent chronic diseases such as  thalassemias and severe type of sickle cell diseases. As there are no physiological mechanisms to excrete the iron contained in transfused red cells (1 unit of blood contains approximately 200 mg of iron the excess of iron is stored in various organs. Cardiomyopathy is the most severe complication covering more than 70% of the causes of death of thalassemic patients. Although the current reference standard iron chelator deferoxamine (DFO has been used clinically for over four decades, its effectiveness is limited by a demanding therapeutic regimen that leads to poor compliance. Despite poor compliance, because of the inconvenience of subcutaneous infusion, DFO improved considerably the survival and quality of life of patients with thalassemia. Deferiprone since 1998 and Deferasirox since 2005 were licensed for clinical use. The oral chelators have a better compliance because of oral use, a comparable efficacy to DFO in iron excretion and probably a better penetration to myocardial cells. Considerable increase in iron excretion was documented with combination therapy of DFO and Deferiprone. The proper use of the three chelators will improve the prevention and treatment of iron overload, it will reduce  complications, and improve survival and quality of life of transfused patients

Chelation therapy to treat atherosclerosis, particularly in diabetes: is it time to reconsider?

Science.gov (United States)

Lamas, Gervasio A; Ergui, Ian

2016-08-01

Case reports and case series have suggested a possible beneficial effect of chelation therapy in patients with atherosclerotic disease. Small randomized trials conducted in patients with angina or peripheral artery disease, however, were not sufficiently powered to provide conclusive evidence on clinical outcomes. The Trial to Assess Chelation Therapy (TACT) was the first randomized trial adequately powered to detect the effects of chelation therapy on clinical endpoints. We discuss results and future research. Expert commentary: Chelation reduced adverse cardiovascular events in a post myocardial infarction (MI) population. Patients with diabetes demonstrated even greater benefit, with a number needed to treat of 6.5 patients to prevent a cardiac event over 5 years, with a 41% relative reduction in risk of a cardiac event (p = 0.0002). These results led to the revision of the ACC/AHA guideline recommendations for chelation therapy, changing its classification from class III to class IIb. TACT2, a replicative trial, will assess the effects of chelation therapy on cardiovascular outcomes in diabetic patients with a prior myocardial infarction. We are seeking participating sites for TACT2.

Macrocyclic chelator-coupled gastrin-based radiopharmaceuticals for targeting of gastrin receptor-expressing tumours

Energy Technology Data Exchange (ETDEWEB)

Good, Stephan; Wang, Xuejuan; Maecke, Helmut R. [University Hospital Basel, Division of Radiological Chemistry, Basel (Switzerland); Walter, Martin A.; Mueller-Brand, Jan [University Hospital, Institute of Nuclear Medicine, Basel (Switzerland); Waser, Beatrice; Reubi, Jean-Claude [University of Berne, Department of Pathology, Bern (Switzerland); Behe, Martin P. [Philipps-University of Marburg, Department of Nuclear Medicine, Marburg (Germany)

2008-10-15

Diethylenetriamine-pentaacetic acid (DTPA)-coupled minigastrins are unsuitable for therapeutic application with the available {beta}-emitting radiometals due to low complex stability. Low tumour-to-kidney ratio of the known radiopharmaceuticals is further limiting their potency. We used macrocyclic chelators for coupling to increase complex stability, modified the peptide sequence to enhance radiolytic stability and studied tumour-to-kidney ratio and metabolic stability using {sup 111}In-labelled derivatives. Gastrin derivatives with decreasing numbers of glutamic acids were synthesised using {sup 111}In as surrogate for therapeutic radiometals for in vitro and in vivo studies. Gastrin receptor affinities of the {sup nat}In-metallated compounds were determined by receptor autoradiography using {sup 125}I-CCK as radioligand. Internalisation was evaluated in AR4-2J cells. Enzymatic stability was determined by incubating the {sup 111}In-labelled peptides in human serum. Biodistribution was performed in AR4-2J-bearing Lewis rats. IC{sub 50} values of the {sup nat}In-metallated gastrin derivatives vary between 1.2 and 4.8 nmol/L for all methionine-containing derivatives. Replacement of methionine by norleucine, isoleucine, methionine-sulfoxide and methionine-sulfone resulted in significant decrease of receptor affinity (IC{sub 50} between 9.9 and 1,195 nmol/L). All cholecystokinin receptor affinities were >100 nmol/L. All {sup 111}In-labelled radiopeptides showed receptor-specific internalisation. Serum mean-life times varied between 2.0 and 72.6 h, positively correlating with the number of Glu residues. All {sup 111}In-labelled macrocyclic chelator conjugates showed higher tumour-to-kidney ratios after 24 h (0.37-0.99) compared to {sup 111}In-DTPA-minigastrin 0(0.05). Tumour wash out between 4 and 24 h was low. Imaging studies confirmed receptor-specific blocking of the tumour uptake. Reducing the number of glutamates increased tumour-to-kidney ratio but resulted in

Macrocyclic chelator-coupled gastrin-based radiopharmaceuticals for targeting of gastrin receptor-expressing tumours

International Nuclear Information System (INIS)

Good, Stephan; Wang, Xuejuan; Maecke, Helmut R.; Walter, Martin A.; Mueller-Brand, Jan; Waser, Beatrice; Reubi, Jean-Claude; Behe, Martin P.

2008-01-01

Diethylenetriamine-pentaacetic acid (DTPA)-coupled minigastrins are unsuitable for therapeutic application with the available β-emitting radiometals due to low complex stability. Low tumour-to-kidney ratio of the known radiopharmaceuticals is further limiting their potency. We used macrocyclic chelators for coupling to increase complex stability, modified the peptide sequence to enhance radiolytic stability and studied tumour-to-kidney ratio and metabolic stability using 111 In-labelled derivatives. Gastrin derivatives with decreasing numbers of glutamic acids were synthesised using 111 In as surrogate for therapeutic radiometals for in vitro and in vivo studies. Gastrin receptor affinities of the nat In-metallated compounds were determined by receptor autoradiography using 125 I-CCK as radioligand. Internalisation was evaluated in AR4-2J cells. Enzymatic stability was determined by incubating the 111 In-labelled peptides in human serum. Biodistribution was performed in AR4-2J-bearing Lewis rats. IC 50 values of the nat In-metallated gastrin derivatives vary between 1.2 and 4.8 nmol/L for all methionine-containing derivatives. Replacement of methionine by norleucine, isoleucine, methionine-sulfoxide and methionine-sulfone resulted in significant decrease of receptor affinity (IC 50 between 9.9 and 1,195 nmol/L). All cholecystokinin receptor affinities were >100 nmol/L. All 111 In-labelled radiopeptides showed receptor-specific internalisation. Serum mean-life times varied between 2.0 and 72.6 h, positively correlating with the number of Glu residues. All 111 In-labelled macrocyclic chelator conjugates showed higher tumour-to-kidney ratios after 24 h (0.37-0.99) compared to 111 In-DTPA-minigastrin 0(0.05). Tumour wash out between 4 and 24 h was low. Imaging studies confirmed receptor-specific blocking of the tumour uptake. Reducing the number of glutamates increased tumour-to-kidney ratio but resulted in lower metabolic stability. The properties of the macrocyclic

Decorporation of metal ions by chelating agents

International Nuclear Information System (INIS)

Koenig, T.

1978-01-01

Simple model designs to simulate the effect of therapeutical chelating agents on the behaviour of metals in mammal organisms with and without excretion have been derived and analytical solutions given for the corresponding differential equations. The possibilities of these models in the short-term description of plasma kinetics of various metals, the competition of the therapeutical ligands with proteins for the metal and of the metabolism of chelating agents were tested and the properties applying extreme conceivable parameters were analyzed. The simple models were successsively expanded in logical sequence, so that it was possible to qualitatively well describe over a long period of time, the metallic kinetics in plasma, organs and urine, the retention of the ligands and their effect on the metal excretion. Two suggestions were given to describe the so-called after-effect, an increased excretion of the metal at times when the ligand is almost completely excreted and their different behaviour after injecting the metal chelate is given. Calculations on the therapy with several ligand data as well as on dose fractionation are described resting on the ratios in the plutonium-239 chosen model parameters and the determining mechanisms analyzed. (orig./MG) [de

Classification of titanium dioxide

International Nuclear Information System (INIS)

Macias B, L.R.; Garcia C, R.M.; Maya M, M.E.; Ita T, A. De; Palacios G, J.

2002-01-01

In this work the X-ray diffraction (XRD), Scanning Electron Microscopy (Sem) and the X-ray Dispersive Energy Spectroscopy techniques are used with the purpose to achieve a complete identification of phases and mixture of phases of a crystalline material as titanium dioxide. The problem for solving consists of being able to distinguish a sample of titanium dioxide being different than a titanium dioxide pigment. A standard sample of titanium dioxide with NIST certificate is used, which indicates a purity of 99.74% for the TiO 2 . The following way is recommended to proceed: a)To make an analysis by means of X-ray diffraction technique to the sample of titanium dioxide pigment and on the standard of titanium dioxide waiting not find differences. b) To make a chemical analysis by the X-ray Dispersive Energy Spectroscopy via in a microscope, taking advantage of the high vacuum since it is oxygen which is analysed and if it is concluded that the aluminium oxide appears in a greater proportion to 1% it is established that is a titanium dioxide pigment, but if it is lesser then it will be only titanium dioxide. This type of analysis is an application of the nuclear techniques useful for the tariff classification of merchandise which is considered as of difficult recognition. (Author)

Studies of the competition for thorium ion between chelating agents and bovine serum albumin

International Nuclear Information System (INIS)

Luo Meichu; Zhang Meizhen; Sun Meizhen; Chen Shijie

1995-01-01

Fourteen chelation agents (polyaminopolcarboxylate type--TTHA, DTPA, EDTA; phenolicpolycarboxylate type--811, 8102, 7601, 7602, 7603, 7616, 7711, 7724, 7803, 7804, 8307) were studied their competitive ability to mobilize the thorium with bovine serum albumin (BSA). The experimental results showed that the competitive ability of TTHA, 8102, 811 to chelate Thorium with BSA were the strongest, and EDTA was the worst in all chelating agents. The measured order of the competitive ability of chelators is basically consistent with animal experimental results in vivo. The parameter F is defined as the competitive ability of chelators. F is taken as a screening criterion for de-corporate thorium which is simple, quick and effective method in vitro

[Influences of the mobile phase constitution, salt concentration and pH value on retention characters of proteins on the metal chelate column].

Science.gov (United States)

Li, R; Di, Z M; Chen, G L

2001-09-01

The effects of the nature and concentration of salts, pH value and competitive eluent in the mobile phase on the protein retention have been systematically investigated. A mathematical expression describing the protein retention in metal chelate chromatography has been derived. It is proposed that the eluting power of the salt solution can be expressed by the eluent strength exponent epsilon. According to the retention characters of protein under different chromatographic conditions, the interaction between the various metal chelate ligands and proteins is discussed. The protein retention on the metal chelate column is a cooperative interactions of coordination, electrostatic and hydrophobic interaction. For the strong combined metal column with proteins such as IDA-Cu, the coordination is the most important, and the electrostatic interaction is secondary in chromatographic process. However, for the weak combined metal columns with proteins such as IDA-Ni, IDA-Co and IDA-Zn, the electrostatic interaction between the metal chelate ligands and proteins is the chief one, while the coordination is the next in importance. When the mobile phase contains high concentration of salt which can't form complex with the immobilized metal, the hydrophobic interaction between the protein and stationary phase will be increased. As the interaction between the metal chelate ligand and proteins relates to chromatographic operating conditions closely, different elution processes may be selected for different metal chelate columns. The gradient elution is generally performed by the low concentration of salt or different pH for weakly combined columns with proteins, however the competitive elution procedure is commonly utilized for strongly combined column. The experiment showed that NH3 is an excellent competitive eluent. It isn't only give the efficient separation of proteins, but also has the advantages of cheapness, less bleeding of the immobilized metals and ease of controlling NH3

Effect of Soil Parameters on the Kinetics of the Displacement of Fe from FeEDDHA Chelates by Cu

NARCIS (Netherlands)

Schenkeveld, W.D.C.; Reichwein, A.M.; Temminghoff, E.J.M.; Riemsdijk, van W.H.

2012-01-01

In soil application, o,o-FeEDDHA (iron (3+) ethylene diamine-N,N'-bis(2-hydroxy phenyl acetic acid) complex) is the active ingredient of FeEDDHA chelate-based Fe fertilizers. The effectiveness of o,o-FeEDDHA is potentially compromised by the displacement of Fe from FeEDDHA by Cu. The actual impact

Corrosion behaviour and galvanic coupling of titanium and welded titanium in LiBr solutions

International Nuclear Information System (INIS)

Blasco-Tamarit, E.; Igual-Munoz, A.; Garcia Anton, J.; Garcia-Garcia, D.

2007-01-01

Corrosion resistance and galvanic coupling of Grade 2 commercially pure titanium in its welded and non-welded condition were systematically analyzed in LiBr solutions. Galvanic corrosion was evaluated through two different methods: anodic polarization (according to the Mixed Potential Theory) and electrochemical noise (using a zero-resistance ammeter). Samples have been etched to study the microstructure. The action of lithium chromate as corrosion inhibitor has been evaluated. Titanium and welded titanium showed extremely low corrosion current densities and elevated pitting potential values (higher than 1 V). The results of both methods, anodic polarization and electrochemical noise, showed that the welded titanium was always the anodic element of the pair titanium-welded titanium, so that its corrosion resistance decreases due to the galvanic effect

Organic analyses of an actual and simulated mixed waste. Hanford's organic complexant waste revisited

International Nuclear Information System (INIS)

Toste, A.P.; Osborn, B.C.; Polach, K.J.; Lechner-Fish, T.J.

1995-01-01

Reanalysis of the organics in a mixed waste, an organic complexant waste, from the U.S. Department of Energy's Hanford Site, has yielded an 80.4% accounting of the waste's total organic content. In addition to several complexing and chelating agents (citrate, EDTA, HEDTA and NTA), 38 chelator/complexor fragments have been identified, compared to only 11 in the original analysis, all presumably formed via organic degradation. Moreover, a mis identification, methanetricarboxylic acid, has been re-identified as the chelator fragment N-(methylamine)imino-diacetic acid (MAIDA). A nonradioactive simulant of the actual waste, containing the parent organics (citrate, EDTA, HEDTA and NTA), was formulated and stored in the dark at ambient temperature for 90 days. Twenty chelator and complexor fragments were identified in the simulant, along with several carboxylic acids, confirming that myriad chelator and complexor fragments are formed via degradation of the parent organics. Moreover, their abundance in the simulant (60.9% of the organics identified) argues that the harsh chemistries of mixed wastes like Hanford's organic degradation, even in the absence of radiation. (author). 26 refs., 2 tabs

Synthesis and thermal characterization of new ternary chelates of piroxicam and tenoxicam with glycine and DL-phenylalanine and some transition metals

Science.gov (United States)

Zayed, M. A.; El-Dien, F. A. Nour; Mohamed, Gehad G.; El-Gamel, Nadia E. A.

2006-05-01

The ternary chelates of piroxicam (Pir) and tenoxicam (Ten) with Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) in the presence of various amino acids such as glycine (Gly) or DL-phenylalanine (PhA) were prepared and characterized with different physicochemical methods. IR spectra confirm that Pir and Ten behave as a neutral bidentate ligand coordinated to the metal ions via the pyridine- N and carbonyl group of the amide moiety. Gly molecule acted as a uninegatively monodentate ligand and coordinate to the metal ions through its deprotonated carboxylic group. In addition, PhA acted as a uninegatively bidentate ligand and coordinate to the metal ions through its deprotonated carboxylic and amino groups. The solid reflectance spectra and magnetic moment measurements confirm that all the chelates have octahedral geometrical structures while Cu(II)- and Zn(II)-ternary chelates with PhA have square planar geometrical structures. Thermal behaviour of the complexes is extensively studied using TG and DTA techniques. TG results show that water molecules (hydrated and coordinated) and anions are removed in the first and second steps while Gly, PhA, Pir and Ten are decomposed in the next and subsequent steps. The pyrolyses of the chelates into different gases are observed in the DTA curves as exo- or endothermic peaks. Also, phase transition states are observed in some chelates. Different thermodynamic parameters are calculated using Coats-Redfern method and the results are interpreted.

Electrowinning molten titanium from titanium dioxide

CSIR Research Space (South Africa)

Van Vuuren, DS

2005-10-01

Full Text Available the Manufacturing and Materials Industry in it quest for global competitiveness CSIR Manufacturing and Materials Technology 3 Rationale – Titanium Cost Build-up Material Cost Ilmenite $0.27/kg Ti sponge Titanium slag $0.75/kg Ti Sponge TiCl4 and TiO2 $3....10/kg Ti Sponge Ti Sponge raw materials costs $5.50/kg Ti Sponge Total Ti Sponge cost $9-$11/kg Ti Sponge Ti ingot $15-17/kg Ti Aluminium $1.7/kg Al Supporting the Manufacturing and Materials Industry in its quest for global competitivenessorting...

Trojan-Like Internalization of Anatase Titanium Dioxide Nanoparticles by Human Osteoblast Cells.

Science.gov (United States)

Ribeiro, A R; Gemini-Piperni, S; Travassos, R; Lemgruber, L; Silva, R C; Rossi, A L; Farina, M; Anselme, K; Shokuhfar, T; Shahbazian-Yassar, R; Borojevic, R; Rocha, L A; Werckmann, J; Granjeiro, J M

2016-03-29

Dentistry and orthopedics are undergoing a revolution in order to provide more reliable, comfortable and long-lasting implants to patients. Titanium (Ti) and titanium alloys have been used in dental implants and total hip arthroplasty due to their excellent biocompatibility. However, Ti-based implants in human body suffer surface degradation (corrosion and wear) resulting in the release of metallic ions and solid wear debris (mainly titanium dioxide) leading to peri-implant inflammatory reactions. Unfortunately, our current understanding of the biological interactions with titanium dioxide nanoparticles is still very limited. Taking this into consideration, this study focuses on the internalization of titanium dioxide nanoparticles on primary bone cells, exploring the events occurring at the nano-bio interface. For the first time, we report the selective binding of calcium (Ca), phosphorous (P) and proteins from cell culture medium to anatase nanoparticles that are extremely important for nanoparticle internalization and bone cells survival. In the intricate biological environment, anatase nanoparticles form bio-complexes (mixture of proteins and ions) which act as a kind of 'Trojan-horse' internalization by cells. Furthermore, anatase nanoparticles-induced modifications on cell behavior (viability and internalization) could be understand in detail. The results presented in this report can inspire new strategies for the use of titanium dioxide nanoparticles in several regeneration therapies.

Ductile and brittle transition behavior of titanium alloys in ultra-precision machining.

Science.gov (United States)

Yip, W S; To, S

2018-03-02

Titanium alloys are extensively applied in biomedical industries due to their excellent material properties. However, they are recognized as difficult to cut materials due to their low thermal conductivity, which induces a complexity to their deformation mechanisms and restricts precise productions. This paper presents a new observation about the removal regime of titanium alloys. The experimental results, including the chip formation, thrust force signal and surface profile, showed that there was a critical cutting distance to achieve better surface integrity of machined surface. The machined areas with better surface roughness were located before the clear transition point, defining as the ductile to brittle transition. The machined area at the brittle region displayed the fracture deformation which showed cracks on the surface edge. The relationship between depth of cut and the ductile to brittle transaction behavior of titanium alloys in ultra-precision machining(UPM) was also revealed in this study, it showed that the ductile to brittle transaction behavior of titanium alloys occurred mainly at relatively small depth of cut. The study firstly defines the ductile to brittle transition behavior of titanium alloys in UPM, contributing the information of ductile machining as an optimal machining condition for precise productions of titanium alloys.

Characterization of the titanium Kβ spectral profile

International Nuclear Information System (INIS)

Chantler, C T; Smale, L F; Kinnane, M N; Illig, A J; Kimpton, J A; Crosby, D N

2013-01-01

Transition metals have Kα and Kβ characteristic radiation possessing complex asymmetric spectral profiles. Instrumental broadening normally encountered in x-ray experiments shifts features of profiles used for calibration, such as peak energy, by many times the quoted accuracies. We measure and characterize the titanium Kβ spectral profile. The peak energy of the titanium Kβ spectral profile is found to be 4931.966 ± 0.022 eV prior to instrumental broadening. This 4.5 ppm result decreases the uncertainty over the past literature by a factor of 2.6 and is 2.4 standard deviations from the previous standard. The spectrum is analysed and the resolution-free lineshape is extracted and listed for use in other experiments. We also incorporate improvement in analysis applied to earlier results for V Kβ. (paper)

OSTEOCALCIN DINAMIC OF DISTROPHICAL BONE KISTS BY TITANIUM NIKELID POROUS MATERIALS IMPLANTATION IN CHILDREN

OpenAIRE

I. I. Kuzhelivsky; M. A. Akselrov; L. A. Sitko

2015-01-01

The article presents results of bone kists treatment by porous granular titanium nikelid materials and dynamic of osteokalcin. A comparative examination with standard treatment technology group demonstrated high efficiency of a proposed method. Porous granular titanium nikelid materials possess mechanical strength, optimization of regeneration at the expense of osteoinductivity by osteokalcin and allow you to effectively fill the cavity with a complex anatomical structure. 

Chelates for Micronutrient Nutrition among Crops

Indian Academy of Sciences (India)

years, it has been recognised that compounds containing che- lated metals could .... when using small amounts and no build up of harmful levels. ... degradation of iron chelates. .... down by soil microorganisms into much smaller units for ab-.

Oxochloroalkoxide of the Cerium (IV and Titanium (IV as oxides precursor

Directory of Open Access Journals (Sweden)

Machado Luiz Carlos

2002-01-01

Full Text Available The Cerium (IV and Titanium (IV oxides mixture (CeO2-3TiO2 was prepared by thermal treatment of the oxochloroisopropoxide of Cerium (IV and Titanium (IV. The chemical route utilizing the Cerium (III chloride alcoholic complex and Titanium (IV isopropoxide is presented. The compound Ce5Ti15Cl16O30 (iOPr4(OH-Et15 was characterized by elemental analysis, FTIR and TG/DTG. The X-ray diffraction patterns of the oxides resulting from the thermal decomposition of the precursor at 1000 degreesC for 36 h indicated the formation of cubic cerianite (a = 5.417Å and tetragonal rutile (a = 4.592Å and (c = 2.962 Å, with apparent crystallite sizes around 38 and 55nm, respectively.

Metal chelate conjugated monoclonal antibodies, wherein the metal is an α emitter

International Nuclear Information System (INIS)

Gansow, O.A.; Strand, M.

1984-01-01

Methods of manufacturing and purifying metal chelate conjugated monoclonal antibodies are described, wherein the chelated metal emits alpha radiation. The conjugates are suited for therapeutic uses being substantially free of nonchelated radiometal. (author)

Study of Anti-Fatigue Effect in Rats of Ferrous Chelates Including Hairtail Protein Hydrolysates

Directory of Open Access Journals (Sweden)

Saibo Huang

2015-12-01

Full Text Available The ability of ferrous chelates including hairtail protein hydrolysates to prevent and reduce fatigue was studied in rats. After hydrolysis of hairtail surimi with papain, the hairtail protein hydrolysates (HPH were separated into three groups by range of relative molecular weight using ultrafiltration membrane separation. Hairtail proteins were then chelated with ferrous ions, and the antioxidant activity, the amino acid composition and chelation rate of the three kinds of ferrous chelates including hairtail protein hydrolysates (Fe-HPH were determined. Among the three groups, the Fe-HPH chelate showing the best conditions was selected for the anti-fatigue animal experiment. For it, experimental rats were randomly divided into seven groups. Group A was designated as the negative control group given distilled water. Group B, the positive control group, was given glutathione. Groups C, D and E were designated as the Fe-HPH chelate treatment groups and given low, medium, and high doses, respectively. Group F was designated as HPH hydrolysate treatment group, and Group G was designated as FeCl2 treatment group. The different diets were orally administered to rats for 20 days. After that time, rats were subjected to forced swimming training after 1 h of gavage. Rats given Fe-FPH chelate had higher haemoglobin regeneration efficiency (HRE, longer exhaustive swimming time and higher SOD activity. Additionally, Fe-FPH chelate was found to significantly decrease the malondialdehyde content, visibly enhance the GSH-Px activity in liver and reduce blood lactic acid of rats. Fe-HPH chelate revealed an anti-fatigue effect, similar to or better than the positive control substance and superior to HPH or Fe when provided alone.

Assessment of potential aluminum chelators in an octanol/aqueous system and in the aluminum-loaded rabbit.

Science.gov (United States)

Yokel, R A; Kostenbauder, H B

1987-11-01

Aluminum (Al) solubilization from Al borate and its distribution in an octanol/aqueous system (Do/w) were determined in the absence and presence of 12 potential Al chelators. Citrate, N,N'-bis-(2-hydroxybenzyl)ethylenediamine- N,N'-diacetic acid (HBED), cyclohexane-1,2-diaminotetraacetic acid (CDTA), diethylenetriaminepentaacetic acid (DTPA), nitrilotriacetic acid (NTA), desferrioxamine, and ethylenediamine-N,N'-bis(2-dihydroxyphenylacetic acid) (EDDHA) were 55 to over 100% efficient in solubilizing equimolar amounts of Al. Tetracycline, EDTA, and 2,3-dihydroxybenzoic acid (DHBA) were less than 20% efficient. 1,4-Dioxane and fluoride were ineffective. The Do/w of Al averaged 0.005. The Do/w of the Al.chelator complex was generally less than that of Al, except for HBED and tetracycline (0.04 and 0.96, respectively). The Do/w of DHBA, desferrioxamine, EDDHA, and HBED were not influenced by Al, but tetracycline became more lipophilic. These compounds were tested for their ability to increase urinary Al excretion in Al-loaded rabbits. Chelators were given po weekly beginning 2 weeks after Al loading. Urine was obtained hourly from 3 hr prior to 6 hr after chelator administration and analyzed for Al. Fluoride and tetracycline (450 and 4500 mumol/kg) and citrate, NTA, EDTA, CDTA, DTPA, DHBA, HBED, and 1,4-dioxane (150 and 1500 mumol/kg) were ineffective. Following HBED administration, some of the Al-loaded rabbits died, presumably due to redistribution of Al within the rabbit. Following DTPA administration, some of the Al-loaded rabbits died, presumably due to DTPA. Oral EDDHA (1500 mumol/kg) significantly increased urinary Al excretion. EDDHA and desferrioxamine (150 mumol/kg) were administered by po, sc, and iv routes and were found to have comparable potency. The in vitro results may explain some of the in vivo findings. The in vitro methods may be useful to screen out compounds with no chelation potential. EDDHA-like compounds may have potential as alternatives to

Enhanced in vitro activity of tigecycline in the presence of chelating agents.

Science.gov (United States)

Deitchman, Amelia N; Singh, Ravi Shankar Prasad; Rand, Kenneth H; Derendorf, Hartmut

2018-05-01

The lack of availability of novel antibiotic agents and the rise of resistance to existing therapies has led clinicians to utilise combination therapy to adequately treat bacterial infections. Here we examined how chelators may impact the in vitro activity of tigecycline (TIG) against Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae. Minimum inhibitory concentrations (MICs) were determined by broth dilution with and without various combinations of chelators (EDTA and other tetracyclines) and metal ions (i.e. calcium, magnesium). Trimethoprim (TMP) was used as a non-chelating control. Addition of metal ions led to increases in MICs, whilst addition of EDTA led to decreases in MICs. The chelating effects of EDTA were reversed by addition of magnesium and most profoundly calcium. Similar effects of EDTA and calcium were observed for tetracycline (TET) and TMP. When other tetracyclines (TET, oxytetracycline (OXY) and chlortetracycline (CHL)) were used as chelators at concentrations below their MICs, TIG MICs decreased for P. aeruginosa but not for E. coli. Some decreases in TIG MICs were observed for K. pneumoniae when TET and CHL were added. A dose-dependent decrease in TIG MIC was observed for TET and was reversed by the addition of calcium. The presence of effects of EDTA and calcium on TMP MICs indicates that mechanisms outside of TIG chelation likely play a role in enhanced activity. Full characterisation of an unexpected interaction such as TIG-TET with different microorganisms could provide valuable insights into the underlying mechanisms and design of physiologically viable chelators as candidates for future combinations regimens. Copyright © 2018 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

The use of titanium dioxide micro-columns to selectively isolate phosphopeptides from proteolytic digests

DEFF Research Database (Denmark)

Thingholm, Tine E; Larsen, Martin R

2009-01-01

Titanium dioxide has very high affinity for phosphopeptides and it has become an efficient alternative to already existing methods for phosphopeptide enrichment from complex samples. Peptide loading in a highly acidic environment in the presence of 2,5-dihydroxybenzoic acid (DHB), phthalic acid......, or glycolic acid has been shown to improve selectivity significantly by reducing unspecific binding from nonphosphorylated peptides. The enriched phosphopeptides bound to the titanium dioxide are subsequently eluted from the micro-column using an alkaline buffer. Titanium dioxide chromatography is extremely...... tolerant towards most buffers used in biological experiments. It is highly robust and as such it has become one of the methods of choice in large-scale phospho-proteomics. Here we describe the protocol for phosphopeptide enrichment using titanium dioxide chromatography followed by desalting...

Development of a database system for operational use in the selection of titanium alloys

Science.gov (United States)

Han, Yuan-Fei; Zeng, Wei-Dong; Sun, Yu; Zhao, Yong-Qing

2011-08-01

The selection of titanium alloys has become a complex decision-making task due to the growing number of creation and utilization for titanium alloys, with each having its own characteristics, advantages, and limitations. In choosing the most appropriate titanium alloys, it is very essential to offer a reasonable and intelligent service for technical engineers. One possible solution of this problem is to develop a database system (DS) to help retrieve rational proposals from different databases and information sources and analyze them to provide useful and explicit information. For this purpose, a design strategy of the fuzzy set theory is proposed, and a distributed database system is developed. Through ranking of the candidate titanium alloys, the most suitable material is determined. It is found that the selection results are in good agreement with the practical situation.

Rhenium(V) and technetium(V) complexes of bis(o-hydroxyphenyl)phenylphosphine (PO22-) and (o-hydroxyphenyl)diphenylphosphine (PO-) ligands

International Nuclear Information System (INIS)

Luo, Hongyan; Setyawati, Ika; Rettig, S.J.; Orvig, C.

1995-01-01

The synthesis of several phosphine-based chelating compounds and chelates formed between these compounds and rhenium or technetium is discussed. Four categories of products result, (i) bis-(o-hydroxyphenyl) diphenylphosphine (PO) complexes, (ii) mono- (PO) complexes, (iii) bis-bis(o-hydroxyphenyl)-phenylphosphine (PO 2 ) complexes, and mixed-(PO) and (PO 2 ) complexes. Molecular structures of these compounds (including isomers) were probed by NMR, MS, and IR spectroscopies and by X-ray crystallography

Plasmonic Titanium Nitride Nanostructures via Nitridation of Nanopatterned Titanium Dioxide

DEFF Research Database (Denmark)

Guler, Urcan; Zemlyanov, Dmitry; Kim, Jongbum

2017-01-01

Plasmonic titanium nitride nanostructures are obtained via nitridation of titanium dioxide. Nanoparticles acquired a cubic shape with sharper edges following the rock-salt crystalline structure of TiN. Lattice constant of the resulting TiN nanoparticles matched well with the tabulated data. Energy...

Ligand-tailored single-site silica supported titanium catalysts: Synthesis, characterization and towards cyanosilylation reaction

International Nuclear Information System (INIS)

Xu, Wei; Li, Yani; Yu, Bo; Yang, Jindou; Zhang, Ying; Chen, Xi; Zhang, Guofang; Gao, Ziwei

2015-01-01

A successive anchoring of Ti(NMe 2 ) 4 , cyclopentadiene and a O-donor ligand, 1-hydroxyethylbenzene (PEA), 1,1′-bi-2-naphthol (Binol) or 2,3-dihydroxybutanedioic acid diethyl ester (Tartrate), on silica was conducted by SOMC strategy in moderate conditions. The silica, monitored by in-situ Fourier transform infrared spectroscopy (in-situ FT-IR), was pretreated at different temperatures (200, 500 and 800 °C). The ligand tailored silica-supported titanium complexes were characterized by in-situ FT-IR, 13 C CP MAS-NMR, X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES) and elemental analysis in detail, verifying that the surface titanium species are single sited. The catalytic activity of the ligand tailored single-site silica supported titanium complexes was evaluated by a cyanosilylation of benzaldehyde. The results showed that the catalytic activity is dependent strongly on the dehydroxylation temperatures of silica and the configuration of the ligands. - Graphical abstract: The ligand-tailored silica supported “single site” titanium complexes were synthesized by SOMC strategy and fully characterized. Their catalytic activity were evaluated by benzaldehyde silylcyanation. - Highlights: • Single-site silica supported Ti active species was prepared by SOMC technique. • O-donor ligand tailored Ti surface species was synthesized. • The surface species was characterized by XPS, 13 C CP-MAS NMR, XANES etc. • Catalytic activity of the Ti active species in silylcyanation reaction was evaluated

Ligand-tailored single-site silica supported titanium catalysts: Synthesis, characterization and towards cyanosilylation reaction

Energy Technology Data Exchange (ETDEWEB)

Xu, Wei; Li, Yani; Yu, Bo; Yang, Jindou; Zhang, Ying; Chen, Xi; Zhang, Guofang, E-mail: gfzhang@snnu.edu.cn; Gao, Ziwei, E-mail: zwgao@snnu.edu.cn

2015-01-15

A successive anchoring of Ti(NMe{sub 2}){sub 4}, cyclopentadiene and a O-donor ligand, 1-hydroxyethylbenzene (PEA), 1,1′-bi-2-naphthol (Binol) or 2,3-dihydroxybutanedioic acid diethyl ester (Tartrate), on silica was conducted by SOMC strategy in moderate conditions. The silica, monitored by in-situ Fourier transform infrared spectroscopy (in-situ FT-IR), was pretreated at different temperatures (200, 500 and 800 °C). The ligand tailored silica-supported titanium complexes were characterized by in-situ FT-IR, {sup 13}C CP MAS-NMR, X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES) and elemental analysis in detail, verifying that the surface titanium species are single sited. The catalytic activity of the ligand tailored single-site silica supported titanium complexes was evaluated by a cyanosilylation of benzaldehyde. The results showed that the catalytic activity is dependent strongly on the dehydroxylation temperatures of silica and the configuration of the ligands. - Graphical abstract: The ligand-tailored silica supported “single site” titanium complexes were synthesized by SOMC strategy and fully characterized. Their catalytic activity were evaluated by benzaldehyde silylcyanation. - Highlights: • Single-site silica supported Ti active species was prepared by SOMC technique. • O-donor ligand tailored Ti surface species was synthesized. • The surface species was characterized by XPS, {sup 13}C CP-MAS NMR, XANES etc. • Catalytic activity of the Ti active species in silylcyanation reaction was evaluated.

Inositol hexa-phosphate: a potential chelating agent for uranium

International Nuclear Information System (INIS)

Cebrian, D.; Tapia, A.; Real, A.; Morcillo, M.A.

2007-01-01

Chelation therapy is an optimal method to reduce the radionuclide-related risks. In the case of uranium incorporation, the treatment of choice is so far i.v infusion of a 1.4% sodium bicarbonate solution, but the efficacy has been proved to be not very high. In this study, we examine the efficacy of some substances: bicarbonate, citrate, diethylenetriamine pentaacetic acid (DTPA), ethidronate (EHBP) and inositol hexa-phosphate (phytic acid) to chelate uranium using a test developed by Braun et al. Different concentrations of phytic acid, an abundant component of plant seeds that is widely distributed in animal cells and tissues in substantial levels, were tested and compared to the same concentrations of sodium citrate, bicarbonate, EHBP and DTPA. The results showed a strong affinity of inositol hexa-phosphate for uranium, suggesting that it could be an effective chelating agent for uranium in vivo. (authors)

Ligand-tailored single-site silica supported titanium catalysts: Synthesis, characterization and towards cyanosilylation reaction

Science.gov (United States)

Xu, Wei; Li, Yani; Yu, Bo; Yang, Jindou; Zhang, Ying; Chen, Xi; Zhang, Guofang; Gao, Ziwei

2015-01-01

A successive anchoring of Ti(NMe2)4, cyclopentadiene and a O-donor ligand, 1-hydroxyethylbenzene (PEA), 1,1‧-bi-2-naphthol (Binol) or 2,3-dihydroxybutanedioic acid diethyl ester (Tartrate), on silica was conducted by SOMC strategy in moderate conditions. The silica, monitored by in-situ Fourier transform infrared spectroscopy (in-situ FT-IR), was pretreated at different temperatures (200, 500 and 800 °C). The ligand tailored silica-supported titanium complexes were characterized by in-situ FT-IR, 13C CP MAS-NMR, X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES) and elemental analysis in detail, verifying that the surface titanium species are single sited. The catalytic activity of the ligand tailored single-site silica supported titanium complexes was evaluated by a cyanosilylation of benzaldehyde. The results showed that the catalytic activity is dependent strongly on the dehydroxylation temperatures of silica and the configuration of the ligands.

On-load chelating agent treatments for conventional and nuclear power stations

International Nuclear Information System (INIS)

Turner, D.J.

1978-01-01

The paper is concerned with the application of on-load chelating agent treatments to those types of water circuit for which they are not currently available: high pressure drum boilers, sub-critical once-through boilers and water reactors. An attempt was made to see whether the most thermally stable types of chelating agent are likely to be sufficiently strong chelating agents either to dissolve established Fe 3 O 4 deposits or to prevent their precipitation from solution. It seems likely that they are strong enough to prevent Fe 3 O 4 depositing in a once-through boiler, through some may require that mildly reducing conditions are maintained. They would not be effective in a high pressure drum boiler (at 350 0 C) unless much more strongly reducing conditions could be maintained. For such boilers it would probably be better to seek multidentate ligands of less than maximum thermal stability. There are some indications that chelating agents based on carbon chains are more stable than NTA or EDTA so that citric acid or some of the unidentified chelating agents recently found to be produced radiolytically may have potential in the treatment of high pressure drum boilers. The prospects for periodic full-load cleaning seem less good for both types of boiler. There may also be a role for radiolytically produced chelating agents in alleviating some of the problems caused by the deposition of radioactive corrosion products in water reactor circuits. The chances for successful development fall from quite good to very low down the series SGHWR moderator circuit, PWR primary circuit, ammonia dosed BWR, neutral chemistry BWR (including SGHWR). (author)

Artefacts in multimodal imaging of titanium, zirconium and binary titanium-zirconium alloy dental implants: an in vitro study.

Science.gov (United States)

Smeets, Ralf; Schöllchen, Maximilian; Gauer, Tobias; Aarabi, Ghazal; Assaf, Alexandre T; Rendenbach, Carsten; Beck-Broichsitter, Benedicta; Semmusch, Jan; Sedlacik, Jan; Heiland, Max; Fiehler, Jens; Siemonsen, Susanne

2017-02-01

To analyze and evaluate imaging artefacts induced by zirconium, titanium and titanium-zirconium alloy dental implants. Zirconium, titanium and titanium-zirconium alloy implants were embedded in gelatin and MRI, CT and CBCT were performed. Standard protocols were used for each modality. For MRI, line-distance profiles were plotted to quantify the accuracy of size determination. For CT and CBCT, six shells surrounding the implant were defined every 0.5 cm from the implant surface and histogram parameters were determined for each shell. While titanium and titanium-zirconium alloy induced extensive signal voids in MRI owing to strong susceptibility, zirconium implants were clearly definable with only minor distortion artefacts. For titanium and titanium-zirconium alloy, the MR signal was attenuated up to 14.1 mm from the implant. In CT, titanium and titanium-zirconium alloy resulted in less streak artefacts in comparison with zirconium. In CBCT, titanium-zirconium alloy induced more severe artefacts than zirconium and titanium. MRI allows for an excellent image contrast and limited artefacts in patients with zirconium implants. CT and CBCT examinations are less affected by artefacts from titanium and titanium-zirconium alloy implants compared with MRI. The knowledge about differences of artefacts through different implant materials and image modalities might help support clinical decisions for the choice of implant material or imaging device in the clinical setting.

Synthesis and evaluation of hydroxamamide-based tetradentate ligands as a new class of thiol-free chelating molecules for 99mTc radiopharmaceuticals.

Science.gov (United States)

Xu, L C; Nakayama, M; Harada, K; Nakayama, H; Tomiguchi, S; Kojima, A; Takahashi, M; Arano, Y

1998-04-01

Both N,N'-ethylene bis(benzohydroxamamide) [(C2(BHam)2)] and N,N'-propylene bis(benzohydroxamamide) [(C3(BHam)2)] were designed as new thiol-free chelating molecules for 99mTc radiopharmaceuticals. Synthetic procedures using oxadiazoline intermediates were developed for C2(BHam)2 and C3(BHam)2. Both C2(BHam)2 and C3(BHam)2 formed 99mTc complexes with high yields over a wide pH range (pH 3-12) at room temperature. Complexation yields of over 95% were achieved at ligand concentrations as low as 2.5 x 10(-6) M. Reversed-phase HPLC analyses indicated that both C2(BHam)2 and C3(BHam)2 formed 99mTc complexes as single species with stabilities much higher than those of 99mTc-BHam. Selective complex formation of 99mTc with the two ligands was observed in the presence of human IgG. No decomposition with low protein binding were demonstrated when the two 99mTc complexes were incubated in murine plasma. Although further structural studies are required, these findings implied that the Ham-based tetradentate ligands would serve as new chelating molecules for 99mTc radiopharmaceuticals.

Synthesis and evaluation of hydroxamamide-based tetradentate ligands as a new class of thiol-free chelating molecules for 99mTc radiopharmaceuticals

International Nuclear Information System (INIS)

Xu Lecun; Nakayama, Morio; Harada, Kumiko; Nakayama, Hitoshi; Tomiguchi, Seiji; Kojima, Akihiro; Takahashi, Mutsumasa; Arano, Yasushi

1998-01-01

Both N,N'-ethylene bis(benzohydroxamamide) [(C 2 (BHam) 2 )] and N,N'-propylene bis(benzohydroxamamide) [(C 3 (BHam) 2 )] were designed as new thiol-free chelating molecules for 99m Tc radiopharmaceuticals. Synthetic procedures using oxadiazoline intermediates were developed for C 2 (BHam) 2 and C 3 (BHam) 2 . Both C 2 (BHam) 2 and C 3 (BHam) 2 formed 99m Tc complexes with high yields over a wide pH range (pH 3-12) at room temperature. Complexation yields of over 95% were achieved at ligand concentrations as low as 2.5 x 10 -6 M. Reversed-phase HPLC analyses indicated that both C 2 (BHam) 2 and C 3 (BHam) 2 formed 99m Tc complexes as single species with stabilities much higher than those of 99m Tc-BHam. Selective complex formation of 99m Tc with the two ligands was observed in the presence of human IgG. No decomposition with low protein binding were demonstrated when the two 99m Tc complexes were incubated in murine plasma. Although further structural studies are required, these findings implied that the Ham-based tetradentate ligands would serve as new chelating molecules for 99m Tc radiopharmaceuticals

OSTEOCALCIN DINAMIC OF DISTROPHICAL BONE KISTS BY TITANIUM NIKELID POROUS MATERIALS IMPLANTATION IN CHILDREN

Directory of Open Access Journals (Sweden)

I. I. Kuzhelivsky

2015-01-01

Full Text Available The article presents results of bone kists treatment by porous granular titanium nikelid materials and dynamic of osteokalcin. A comparative examination with standard treatment technology group demonstrated high efficiency of a proposed method. Porous granular titanium nikelid materials possess mechanical strength, optimization of regeneration at the expense of osteoinductivity by osteokalcin and allow you to effectively fill the cavity with a complex anatomical structure. 

Improved paramagnetic chelate for molecular imaging with MRI

International Nuclear Information System (INIS)

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

2005-01-01

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

Improved paramagnetic chelate for molecular imaging with MRI

Science.gov (United States)

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

2005-05-01

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.

Physicochemical impact studies of gamma rays on "aspirin" analgesics drug and its metal complexes in solid form: Synthesis, spectroscopic and biological assessment of Ca(II), Mg(II), Sr(II) and Ba(II) aspirinate complexes

Science.gov (United States)

Refat, Moamen S.; Sharshar, T.; Elsabawy, Khaled M.; Heiba, Zein K.

2013-09-01

Metal aspirinate complexes, M2(Asp)4, where M is Mg(II), Ca(II), Sr(II) or Ba(II) are formed by refluxed of aspirin (Asp) with divalent non-transition metal ions of group (II) and characterized by elemental analysis and spectroscopic measurements (infrared, electronic, 1H NMR, Raman, X-ray powder diffraction and scanning electron microscopy). Elemental analysis of the chelates suggests the stoichiometry is 1:2 (metal:ligand). Infrared spectra of the complexes agree with the coordination to the central metal atom through three donation sites of two oxygen atoms of bridge bidentate carboxylate group and oxygen atom of sbnd Cdbnd O of acetyl group. Infrared spectra coupled with the results of elemental analyzes suggested a distorted octahedral structure for the M(II) aspirinate complexes. Gamma irradiation was tested as a method for stabilization of aspirin as well as their complexes. The effect of gamma irradiation, with dose of 80 Gy, on the properties of aspirinate complexes was studied. The aspirinate chelates have been screened for their in vitro antibacterial activity against four bacteria, gram-positive (Bacillus subtilis and Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) and two strains of fungus (Aspergillus flavus and Candida albicans). The metal chelates were shown to possess more antibacterial activity than the free aspirin chelate.

Chelator induced phytoextraction and in situ soil washing of Cu

International Nuclear Information System (INIS)

Kos, Bostjan; Lestan, Domen

2004-01-01

In a soil column experiment, we investigated the effect of 5 mmol kg -1 soil addition of citric acid, ethylenediamine tetraacetate (EDTA), diethylenetriamine-pentaacetate (DTPA) and [S,S]-stereoisomer of ethylenediamine-disuccinate (EDDS) on phytoextraction of Cu from a vineyard soil with 162.6 mg kg -1 Cu, into the test plant Brassica rapa var. pekinensis. We also examined the use of a horizontal permeable barrier, composed of layers of nutrient enriched sawdust and apatite, for reduction of chelator induced Cu leaching. The addition of all chelators, except citric acid, enhanced Cu mobility and caused leaching of 19.5-23% of initial total Cu from the soil column. However, Cu plant uptake did not increase accordingly; the most effective was the EDDS treatment, in which plant Cu concentration reached 37.8±1.3 mg kg -1 Cu and increased by 3.3-times over the control treatment. The addition of none of the chelators in the concentration range from 5 to 15 mmol kg -1 exerted any toxic effect on respiratory soil microorganisms. When EDDS was applied into the columns with horizontal permeable barriers, only 0.53±0.32% of the initial total Cu was leached. Cu (36.7%) was washed from the 18 cm soil layer above the barrier and accumulated in the barrier. Our results indicate that rather than for a reduction of Cu leaching during rather ineffective chelate induced Cu phytoextraction, horizontal permeable barriers could be more effective in a new remediation technique of controlled in situ soil washing of Cu with biodegradable chelates

Photo-Curable Metal-Chelating Coatings Offer a Scalable Approach to Production of Antioxidant Active Packaging.

Science.gov (United States)

Lin, Zhuangsheng; Goddard, Julie

2018-02-01

Synthetic metal chelators (for example, ethylenediaminetetraacetic acid, EDTA) are widely used as additives to control trace transition metal induced oxidation in consumer products. To enable removal of synthetic chelators in response to increasing consumer demand for clean label products, metal-chelating active food packaging technologies have been developed with demonstrated antioxidant efficacy in simulated food systems. However, prior work in fabrication of metal-chelating materials leveraged batch chemical reactions to tether metal-chelating ligands, a process with limited industrial translatability for large-scale fabrication. To improve the industrial translatability, we have designed a 2-step laminated photo-grafting process to introduce metal chelating functionality onto common polymeric packaging materials. Iminodiacetic acid (IDA) functionalized materials were fabricated by photo-grafting poly(acrylic acid) onto polypropylene (PP) films, followed by a second photo-grafting process to graft-polymerize an IDA functionalized vinyl monomer (GMA-IDA). The photo-grafting was conducted under atmospheric conditions and was completed in 2 min. The resulting IDA functionalized metal-chelating material was able to chelate iron and copper, and showed antioxidant efficacy against ascorbic acid degradation, supporting its potential to be used synergistically with natural antioxidants for preservation of food and beverage products. The 2-step photo-grafting process improves the throughput of active packaging coatings, enabling potential roll-to-roll fabrication of metal-chelating active packaging materials for antioxidant food packaging applications. To address consumer and retail demands for "clean label" foods and beverages without a corresponding loss in product quality and shelf life, producers are seeking next generation technologies such as active packaging. In this work, we will report the synthesis of metal-chelating active packaging films, which enable removal

Copper complexes as chemical nucleases

Indian Academy of Sciences (India)

Unknown

anticancer drug famotidine has been shown as a better catalyst than CuCl2 for sulfite ... Effect of addition of bis-chelate copper(II) complexes (dpq, •; phen, ; ..... Reproduction, Development & Genetics for their help in the DNA cleavage studies ...

Mixed metal complexes of isoniazid and ascorbic acid: chelation ...

African Journals Online (AJOL)

Novel mixed complexes of isoniazid and ascorbic acid have been synthesized and characterized using infrared, electronic absorption data, elemental analysis, molar conductivity, melting point, thin layer chromatography and solubility. The metal ions involved in the complex formation are Cu2+, Zn2+ and Cd2+. The melting ...

Mixed Metal Complexes of Isoniazid and Ascorbic Acid: Chelation ...

African Journals Online (AJOL)

HP

these ligands and their metal complexes have revealed the bi-dentate coordination of isoniazid ligand to ... of the drugs on coordination with a metal is enhanced ..... James, O.O., Nwinyi, C.O. and. Allensela, M.A. (2008). Cobalt(II) complexes of mixed antibiotics: Synthesis,. Characterization, antimicrobial potential and their.

Growth Performance, Mineral Digestibility, and Blood Characteristics of Ostriches Receiving Drinking Water Supplemented with Varying Levels of Chelated Trace Mineral Complex.

Science.gov (United States)

Seyfori, Hossein; Ghasemi, Hossein Ali; Hajkhodadadi, Iman; Nazaran, Mohammad Hassan; Hafizi, Maryam

2018-05-01

The effects of water supplementation of chelated trace minerals (CTM, which is named Bonzaplex designed with chelate compounds technology) on growth performance, apparent total tract digestibility (ATTD) of minerals, and some blood metabolites, TM, and antioxidant enzyme values in African ostriches were investigated from 8 to 12 months of age. A total of 20 8-month-old ostriches (five birds in five replicate pens) was randomly allocated into one of the following four treatments: (1) control (basal diet + tap water), (2) low CTM (basal diet +100 mg/bird/day CTM powder in tap water), (3) medium CTM (basal diet +1 g/bird/day CTM powder in tap water), and (4) high CTM (basal diet +2 g/bird/day CTM powder in tap water). Compared with control, medium CTM improved (P water can be recommended for improving growth performance, mineral absorption, and antioxidant status of ostriches fed diets containing the recommended levels of inorganic TM.

Determination of quercetin using a photo-electrochemical sensor modified with titanium dioxide and a platinum(II)-porphyrin complex

International Nuclear Information System (INIS)

Tian, Li; Wang, Binbin; Chen, Ruizhan; Gao, Ye; Chen, Yanling; Li, Tianjiao

2015-01-01

A glassy carbon electrode (GCE) was modified with a film containing titanium dioxide and a Pt(II)-porphyrin complex, and its response to quercetin was investigated employing cyclic voltammetry and chronoamperometry. The oxidation current caused by quercetin is largely enhanced under UV illumination. The effects of pH value, mass of TiO 2 in the film, UV illumination time and applied potential were studied. Under optimized conditions, the peak current at a typically applied voltage of +0.4 V depends linearly on the concentration of quercetin in the 0.002 to 50 mg L −1 range. The detection limit (at an SNR of 3) is 0.8 μg L −1 . The method was successfully applied to the determination of quercetin in (spiked) samples of tea and apple juice. (author)

Albumin microspheres labeled with Ga-67 by chelation: concise communication

International Nuclear Information System (INIS)

Hnatowich, D.J.; Schlegel, P.

1981-01-01

Albumin microspheres have been synthesized with EDTA and DTPA chelating groups covalently bound to their surface. The microspheres may be labeled with Ga-67 at high yield (97 +- 2%) by transcomplexation from a 0.1 M Ga-67 acetate solution. With EDTA microspheres the resulting label dissociates only slightly after 24 hr in 50% plasma at 37 0 C, whereas with DTPA microspheres the label shows no detectable dissociation over this period. By contrast, microspheres without chelating groups lose their label virtually completely under these conditions. Following intravenous administration of sized Ga-67 DTPA microspheres in mice, about (84 +- 16)% of the activity localizes in the lungs at 5 min, with (60 +- 7)% remaining after 2 h. Since labeling is by chelation, the microspheres may also be tagged with other metallic radionuclides

Rough surfaces of titanium and titanium alloys for implants and prostheses

International Nuclear Information System (INIS)

Conforto, E.; Aronsson, B.-O.; Salito, A.; Crestou, C.; Caillard, D.

2004-01-01

Titanium and titanium alloys for dental implants and hip prostheses were surface-treated and/or covered by metallic or ceramic rough layers after being submitted to sand blasting. The goal of these treatments is to improve the surface roughness and consequently the osteointegration, the fixation, and the stability of the implant. The microstructure of titanium and titanium alloys submitted to these treatments has been studied and correlated to their mechanical behavior. As-treated/covered and mechanically tested surfaces were characterized by scanning electron microscopy (SEM). Structural analyses performed by transmission electron microscopy (TEM), mainly in cross-section, reveal the degree of adherence and cohesion between the surface layer and the substrate (implant). We observed that, although the same convenient surface roughness was obtained with the two types of process, many characteristics as structural properties and mechanical behavior are very different

Impact of electronic modification of the chelating benzylidene ligand in cis-dichloro-configured second-generation olefin metathesis catalysts on their activity

KAUST Repository

Pump, Eva; Poater, Albert; Zirngast, Michaela; Torvisco, Ana; Fischer, Roland C.; Cavallo, Luigi; Slugovc, Christian

2014-01-01

A series of electronically modified second-generation cis-dichloro ruthenium ester chelating benzylidene complexes was prepared, characterized, and benchmarked in a typical ring-opening metathesis polymerization (ROMP) experiment. The electronic tuning of the parent chelating benzylidene ligand (2-ethyl ester benzylidene) was achieved by substitution at the 4- and 5-positions with electron-withdrawing nitro or electron-donating methoxy groups. The effect of the electronic tuning on the cis-trans isomerization process was studied experimentally and theoretically. Density functional theory calculations clearly revealed the influence of electronic modification on the relative stability between the cis and trans isomers, which is decisive for the activity of the studied compounds as initiators in ROMP. © 2014 American Chemical Society.

Impact of electronic modification of the chelating benzylidene ligand in cis-dichloro-configured second-generation olefin metathesis catalysts on their activity

KAUST Repository

Pump, Eva

2014-06-09

A series of electronically modified second-generation cis-dichloro ruthenium ester chelating benzylidene complexes was prepared, characterized, and benchmarked in a typical ring-opening metathesis polymerization (ROMP) experiment. The electronic tuning of the parent chelating benzylidene ligand (2-ethyl ester benzylidene) was achieved by substitution at the 4- and 5-positions with electron-withdrawing nitro or electron-donating methoxy groups. The effect of the electronic tuning on the cis-trans isomerization process was studied experimentally and theoretically. Density functional theory calculations clearly revealed the influence of electronic modification on the relative stability between the cis and trans isomers, which is decisive for the activity of the studied compounds as initiators in ROMP. © 2014 American Chemical Society.

Rapid PMR determination of hydrogen in titanium hydride and dehydrogenated titanium powders

International Nuclear Information System (INIS)

Il'enko, V.S.; Demidenko, L.M.

1987-01-01

Proton magnetic resonance (PMR) enables determining hydrogen quantitatively in titanium hydride and dehydrogenated titanium powders without destroying the specimen and is also more informative than high-temperature extraction methods. PMR provides data on the electron-nuclear interactions and the activation energies for hydrogen diffusion while also providing conclusions on the forms and positives of the hydrogen in the lattice and the binding to the metal atoms. The authors have developed a rapid method for determining hydrogen in titanium hydride and dehydrogenated titanium powders which reduces the analysis time and improves the metrological characteristics. The authors use a YaMR-5535 spectrometer working at 40 MHz upgraded for use with hydrogen in solids. The authors used specimens of mass about 2 g ground to 0.1 mm powder

Synthesis of a novel 'smart' bifunctional chelating agent 1-(2-[beta,D-galactopyranosyloxy]ethyl)-7-(1-carboxy-3-[4-aminophenyl]propyl)-4,10-bis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (Gal-PA-DO3A-NH2) and its Gd(III) complex.

Science.gov (United States)

Wardle, Nick J; Herlihy, Amy H; So, Po-Wah; Bell, Jimmy D; Bligh, S W Annie

2007-07-15

A new synthetic pathway to 1-(2-[beta,D-galactopyranosyloxy]ethyl)-7-(1-carboxy-3-[4-aminophenyl]propyl)-4,10-bis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (Gal-PA-DO3A-NH2) and 1-(2-[beta,D-galactopyranosyloxy]ethyl)-4,7,10-tris(carboxymethyl)-1, 4,7,10-tetraazacyclododecane (Gal-DO3A) chelating agents was developed involving full hydroxyl- and carboxyl-group protection in precursors to product. Two sequences of cyclen-N-functionalisation were subsequently investigated, one successfully, towards synthesis of the novel 'smart' bifunctional Gal-PA-DO3A-NH2 chelate. The longitudinal proton relaxivities of the neutral [Gd-(Gal-PA-DO3A-NH2)] and [Gd-(Gal-DO3A)] complexes were increased by 28% and 37% in the presence of beta-galactosidase, respectively.

Synergistic responses of superficial chemistry and micro topography of titanium created by wire-type electric discharge machining.

Science.gov (United States)

Kataoka, Yu; Tamaki, Yukimichi; Miyazaki, Takashi

2011-01-01

Wire-type electric discharge machining has been applied to the manufacture of endosseous titanium implants as this computer associated technique allows extremely accurate complex sample shaping with an optimal micro textured surface during the processing. Since the titanium oxide layer is sensitively altered by each processing, the authors hypothesized that this technique also up-regulates biological responses through the synergistic effects of the superficial chemistry and micro topography. To evaluate the respective in vitro cellular responses on the superficial chemistry and micro topography of titanium surface processed by wire-type electric discharge, we used titanium-coated epoxy resin replica of the surface. An oxide layer on the titanium surface processed by wire-type electric discharge activated the initial responses of osteoblastic cells through an integrin-mediated mechanism. Since the mRNA expression of ALP on those replicas was up-regulated compared to smooth titanium samples, the micro topography of a titanium surface processed by wire-type electric discharge promotes the osteogenic potential of cells. The synergistic response of the superficial chemistry and micro topography of titanium processed by wire-type electric discharge was demonstrated in this study.

Which psychosocial factors are related to chelation adherence in thalassemia? A systematic review.

Science.gov (United States)

Evangeli, Michael; Mughal, Kulsoom; Porter, John B

2010-06-01

Good adherence to iron chelation therapy in thalassemia is crucial. Although there is evidence that adherence is related to regimen factors, there has been less emphasis on the relationship between psychosocial (psychological, demographic and social) factors and adherence. We present a systematic review of psychosocial correlates of chelation adherence in thalassemia. Nine studies met the inclusion criteria. Information was extracted regarding the study characteristics and the relationship between psychosocial factors and chelation adherence. Methodological quality was rated. The studies took place in a range of countries, were mostly cross sectional in design, and examined adherence to deferoxamine (DFO) only. Sample sizes ranged from 15 to 1573. A variety of psychosocial variables were examined. Definitions of adherence varied between studies and non adherence rates were also variable (9 to 66%). Older age was consistently associated with lower levels of chelation adherence. There were few other consistent findings. The methodological quality of studies was variable. There is a need for more methodologically sophisticated and theoretically informed studies on psychosocial correlates of chelation adherence. We offer specific suggestions.

Deaths associated with hypocalcemia from chelation therapy--Texas, Pennsylvania, and Oregon, 2003-2005.

Science.gov (United States)

2006-03-03

Chelating agents bind lead in soft tissues and are used in the treatment of lead poisoning to enhance urinary and biliary excretion of lead, thus decreasing total lead levels in the body. During the past 30 years, environmental and dietary exposures to lead have decreased substantially, resulting in a considerable decrease in population blood lead levels (BLLs) and a corresponding decrease in the number of patients requiring chelation therapy. Chelating agents also increase excretion of other heavy metals and minerals, such as zinc and, in certain cases, calcium. This report describes three deaths associated with chelation-therapy--related hypocalcemia that resulted in cardiac arrest. Several drugs are used in the treatment of lead poisoning, including edetate disodium calcium (CaEDTA), dimercaperol (British anti-Lewisite), D-penicillamine, and meso-2,3-dimercaptosuccinic acid (succimer). Health-care providers who are unfamiliar with chelating agents and are considering this treatment for lead poisoning should consult an expert in the chemotherapy of lead poisoning. Hospital pharmacies should evaluate whether continued stocking of Na2EDTA is necessary, given the established risk for hypocalcemia, the availability of less toxic alternatives, and an ongoing safety review by the Food and Drug Administration (FDA). Health-care providers and pharmacists should ensure that Na2EDTA is not administered to children during chelation therapy.

A study on the adsorption and subsurface transport of radioactive solutes in the presence of chelating agents

International Nuclear Information System (INIS)

Baik, Min Hoon

1994-02-01

In this study, adsorption and transport models were developed to analyze the effect of chelating agents on the adsorption and subsurface transport of radioactive solutes. The effect of chelating agents on the adsorption of radioactive solutes was analyzed by developing an adsorption model based upon the extended concept of distribution coefficient reflecting the presence of chelating agents. Also, a batch adsorption experiment was conducted in order to validate the developed adsorption model and to investigate the effect of chelating agent on the adsorption of radioactive metal solutes. In this experiment, a Cobalt(II)/EDTA/Bentonite system was considered as a representative chelation/adsorption system. It was found from the results that the presence of chelating agents significantly reduced the adsorbing capacity of geologic media such as clay minerals and soils. Thus it was concluded that the presence of chelating agents even in a small amount could contribute to the mobilization of radioactive solutes from radioactive waste burial sites by reducing the adsorbing capacity of geologic media. The effect of chelating agents on the transport of radioactive solutes in subsurface porous media was analyzed by formulating an advective-dispersive transport model which incorporated chelate formation, adsorption, decay, and degradations and by introducing the concept of a tenad. Particularly the governing equation for the tenad of radioactive solutes, M, was presented as a linear partial differential form by introducing the extended distribution coefficient, K D . The calculated results from the model showed that the transport rate of the chelated radionuclides was much greater than that of the free ionic radionuclides. This much faster transport of the chelated radionuclides was found to be due to the lower retardation factor of the chelated radionuclides than the free ionic radionuclides. The effect of parameters on the transport of radioactive solutes was also analyzed

Synthesis of o,p-EDDHA and its detection as the main impurity in o,o-EDDHA commercial iron chelates.

Science.gov (United States)

Gómez-Gallego, Mar; Sierra, Miguel A; Alcázar, Roberto; Ramírez, Pedro; Piñar, Carmen; Mancheño, María José; García-Marco, Sonia; Yunta, Felipe; Lucena, Juan José

2002-10-23

Ethylenediamine-N,N'bis(o-hydroxyphenyl)acetic acid (o,o-EDDHA) is one of the most efficient iron chelates employed to relieve iron chlorosis in plants. However, the presence of positional isomers of EDDHA in commercial iron chelates has been recently demonstrated, and among them, it has been claimed that ethylenediamine-N(o-hydroxyphenylacetic)-N'(p-hydroxyphenylacetic) acid (o,p-EDDHA) is the main impurity present in EDDHA fertilizers. Here we report the preparation of o,p-EDDHA, a compound whose synthesis had not been previously reported. The synthetic o,p-EDDHA is able to form ferric complexes, and it has been used as a standard in the analysis of the impurities of commercial iron fertilizers. The presence of o,p-EDDHA/Fe(3+) in commercial samples has been unambiguously demonstrated by HPLC.

Studies on effect of Microbial Iron Chelators on Candida Albican

International Nuclear Information System (INIS)

Rehmani, Fouzia S.; Milicent, S.; Zaheer-Uddin

2005-01-01

Iron is an essential for the life of all microbe cells. It generally exists in the oxidized form Fe(III). Even under anaerobic reducing condition the metal appear to be taken up as Fe(III). Thus free-living microorganisms require specific and effective ferric ion transport system to cope with low availability of the metal. In iron deficient environment they produce a low molecular weight specific chelators called siderphores or microbial iron chelators. Siderphores compete for limited supplied of iron. These compounds came out of the cell but can not re-enter without iron due to high affinity of these siderphores often have more than one catechol/hydroxamate functions and are multidentate (usually hexadentate ligands). The aim of the present research is to check the effect of iron chelators, namely gallic acid and salisyl hydroxamate on the growth of Candida albican in vitro. C. albican is the opportunistic paltogen present as the normal flora inside human body. In vivo the growth of C. albican is distributed by the use of antibiotics and immuno suppressers. In cases of iron over-dosage in human being, the patients are treated with certain a-iron chelators. Hence an attempt is made to notice the effect that might be inhibition or enhancement of the organism in vitro. (author)

Chelation of thallium by combining deferasirox and desferrioxamine in rats.

Science.gov (United States)

Saljooghi, Amir Shokooh; Babaie, Maryam; Mendi, Fatemeh Delavar; Zahmati, Maliheh; Saljooghi, Zoheir Shokouh

2016-01-01

The hypothesis that two known chelators deferasirox (4-[3,5-bis(2-hydroxyphenyl)-1,2,4-triazol-1-yl]-benzoic acid) and desferrioxamine (DFO) might be more efficient as combined treatment than as monotherapies in removing thallium from the body was tested in a new acute rat model. 7-week-old male Wistar rats received chelators: deferasirox (orally), DFO (intraperitoneal; i.p.), or deferasirox + DFO as 75 or 150 mg/kg dose half an hour after a single i.p. administration of 8 mg thallium/kg body weight in the form of chloride. Serum thallium concentration, urinary thallium, and iron excretions were determined by graphite furnace atomic absorption spectrometry. Both chelators were effective only at the higher dose level, while DFO was more effective than deferasirox in enhancing urinary thallium excretion, deferasirox was more effective than DFO in enhancing urinary iron excretion. In the combined treatment group, deferasirox did not increase the DFO effect on thallium and DFO did not increase the effect of deferasirox on iron elimination. Our results support the usefulness of this animal model for preliminary in vivo testing of thallium chelators. Urinary values were more useful because of the high variability of serum results. © The Author(s) 2013.

A general access to organogold(iii) complexes by oxidative addition of diazonium salts.

Science.gov (United States)

Huang, Long; Rominger, Frank; Rudolph, Matthias; Hashmi, A Stephen K

2016-05-11

At room temperature under mild photochemical conditions, namely irradiation with a simple blue light LED, gold(i) chloro complexes of both phosphane and carbene ligands in combination with aryldiazonium salts afford arylgold(iii) complexes. With chelating P,N-ligands cationic six- or five-membered chelate complexes were isolated in the form of salts with weakly coordinating counter anions that were brought in from the diazonium salt. With monodentate P ligands or N-heterocyclic carbene ligands and diazonium chlorides neutral arylgold(iii) dichloro complexes were obtained. The coordination geometry was determined by X-ray crystal structure analyses of representative compounds, a cis arrangement of the aryl and the phosphane ligand at the square planar gold(iii) center is observed.

Effect of the ultrasound-Fenton oxidation process with the addition of a chelating agent on the removal of petroleum-based contaminants from soil.

Science.gov (United States)

Li, Ying; Li, Fangmin; Li, Fanxiu; Yuan, Fuqian; Wei, Pingfang

2015-12-01

The effects of ultrasonic irradiation, the chelating agent modified Fenton reaction, and a combination of ultrasound and the Fenton method in removing petroleum contaminants from a soil were studied. The results showed that the contaminant removal rate of the Fenton treatment combined with an oxalic acid chelating agent was 55.6% higher than that without a chelating agent. The average removal rate of the contaminants using the ultrasound-Fenton treatment was 59.0% higher than that without ultrasonic treatment. A combination of ultrasound and an Fe(2+)/Fe(3+)-oxalate complex-modified Fenton reagent resulted in significantly higher removal rates of n-alkanes (C(n)H(2n+2), n Fenton method. The Fenton reaction and the ultrasound-Fenton treatment can unselectively remove multiple components of residual hydrocarbons and a number of benzene rings in polycyclic aromatic hydrocarbons. The chemistry of the heterocyclic compounds and the position and number of substituents can affect the degradation process.

Metallomics for Alzheimer's disease treatment: Use of new generation of chelators combining metal-cation binding and transport properties.

Science.gov (United States)

D'Acunto, Cosimo Walter; Kaplánek, Robert; Gbelcová, Helena; Kejík, Zdeněk; Bříza, Tomáš; Vasina, Liudmila; Havlík, Martin; Ruml, Tomáš; Král, Vladimír

2018-04-25

Alzheimer's disease (AD) is a progressive neurodegenerative disorder affecting tens of million people. Currently marketed drugs have limited therapeutic efficacy and only slowing down the neurodegenerative process. Interestingly, it has been suggested that biometal cations in the amyloid beta (Aβ) aggregate deposits contribute to neurotoxicity and degenerative changes in AD. Thus, chelation therapy could represent novel mode of therapeutic intervention. Here we describe the features of chelators with therapeutically relevant mechanism of action. We have found that the tested compounds effectively reduce the toxicity of exogenous Aβ and suppress its endogenous production as well as decrease oxidative stress. Cholyl hydrazones were found to be the most active compounds. In summary, our data show that cation complexation, together with improving transport efficacy may represent basis for eventual treatment strategy in AD. Copyright © 2018. Published by Elsevier Masson SAS.

Synthesis of novel bifunctional chelators and their use in preparing monoclonal antibody conjugates for tumor targeting

International Nuclear Information System (INIS)

Westerberg, D.A.; Carney, P.L.; Rogers, P.E.; Kline, S.J.; Johnson, D.K.

1989-01-01

Bifunctional derivatives of the chelating agents ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, in which a p-isothiocyanatobenzyl moiety is attached at the methylene carbon atom of one carboxymethyl arm, was synthesized by reductive alkylation of the relevant polyamine with (p-nitrophenyl)pyruvic acid followed by carboxymethylation, reduction of the nitro group, and reaction with thiophosgene. The resulting isothiocyanate derivatives reacted with monoclonal antibody B72.3 to give antibody-chelator conjugates containing 3 mol of chelator per mole of immunoglobulin, without significant loss of immunological activity. Such conjugates, labeled with the radioisotopic metal indium-111, selectively bound a human colorectal carcinoma implanted in nude mice when given intravenously. Uptake into normal tissues was comparable to or lower than that reported for analogous conjugates with known bifunctional chelators. It is concluded that substitution with a protein reactive group at this position in polyaminopolycarboxylate chelators does not alter the chelating properties of these molecules to a sufficient extent to adversely affect biodistribution and thus provides a general method for the synthesis of such chelators

Metal-chelating compounds produced by ectomycorrhizal fungi collected from pine plantations.

Science.gov (United States)

Machuca, A; Pereira, G; Aguiar, A; Milagres, A M F

2007-01-01

To investigate the in vitro production of metal-chelating compounds by ectomycorrhizal fungi collected from pine plantations in southern Chile. Scleroderma verrucosum, Suillus luteus and two isolates of Rhizopogon luteolus were grown in solid and liquid modified Melin-Norkans (MMN) media with and without iron addition and the production of iron-chelating compounds was determined by Chrome Azurol S (CAS) assay. The presence of hydroxamate and catecholate-type compounds and organic acids was also investigated in liquid medium. All isolates produced iron-chelating compounds as detected by CAS assay, and catecholates, hydroxamates as well as oxalic, citric and succinic acids were also detected in all fungal cultures. Scleroderma verrucosum produced the greatest amounts of catecholates and hydroxamates whereas the highest amounts of organic acids were detected in S. luteus. Nevertheless, the highest catecholate, hydroxamate and organic acid concentrations did not correlate with the highest CAS reaction which was observed in R. luteolus (Yum isolate). Ectomycorrhizal fungi produced a variety of metal-chelating compounds when grown in liquid MMN medium. However, the addition of iron to all fungi cultures reduced the CAS reaction, hydroxamate and organic acid concentrations. Catecholate production was affected differently by iron, depending on the fungal isolate. The ectomycorrhizal fungi described in this study have never been reported to produce metal-chelating compound production. Moreover, apart from some wood-rotting fungi, this is the first evidence of the presence of catecholates in R. luteolus, S. luteus and S. verrucosum cultures.

Modelling thermodynamic properties of lanthanide (LnL)3+ and actinide (AnL)3+ complexes with tridentate planar nitrogen ligands (L)

International Nuclear Information System (INIS)

Ionova, G.; Rabbe, C.; Charbonnel, M.C.; Hill, C.; Guillaumont, D.; Guillaumont, R.; Ionov, S.; Madic, C.

2004-01-01

We report here the results obtained from a systematic theoretical study on the thermodynamic properties of trivalent lanthanide (Ln) and actinide (An) complexes with chelating nitrogen tridentate ligands. The mechanism of chelation has been investigated and the role of cation dissolution is investigated through a comparison of the thermodynamic properties of solvated cations and complexes. The difference in thermodynamic properties of LnL and AnL complexes is analyzed. (authors)

Chelation therapy in intoxications with mercury, lead and copper

DEFF Research Database (Denmark)

Cao, yang; Skaug, Marit Aralt; Andersen, Ole

2015-01-01

In the present review we provide an update of the appropriate use of chelating agents in the treatment of intoxications with compounds of mercury, lead and copper. The relatively new chelators meso-2,3-dimercaptosuccinic acid (DMSA) and 2,3-dimercapto-propanesulphonate (DMPS) can effectively...... mobilize deposits of mercury as well as of lead into the urine. These drugs can be administered orally and have relatively low toxicity compared to the classical antidote dimercaptopropanol (BAL). d-Penicillamine has been widely used in copper overload, although 2,3-dimercaptosuccinic acid...

Electrochemistry of chromium(0)-aminocarbene complexes

International Nuclear Information System (INIS)

Hoskovcova, Irena; Rohacova, Jana; Meca, Ludek; Tobrman, Tomas; Dvorak, Dalimil; Ludvik, Jiri

2005-01-01

Two series of chromium(0)-(aryl)aminocarbene complexes substituted on the ligand phenyl ring were prepared and electrochemically investigated: pentacarbonyl((N,N-dimethylamino)(phenyl)carbene(chromium(0) (Ia-e) and chelated tetracarbonyl((η 2 -N-allyl-N-allylamino)(phenyl)carbene(chromium(0) (IIa, c-e). For comparison, a tungsten analogue of IIc (III) and a chromium chelate bearing a methyl substituent instead of the phenyl group IV were taken into the study. The intramolecular interactions of p-substituents on the ligand phenyl ring with the reduction and oxidation centres of the molecule of complex (followed electrochemically using LFER [P. Zuman, Substituent Effects in Organic Polarography, Plenum Press, New York, 1967]) enabled to localize the corresponding electron transfer. The influence of the type of coordination, the substituent on the ligand phenyl ring and the central metal atom on oxidation and reduction potentials is discussed

Silica-supported, single-site titanium catalysts for olefin epoxidation. A molecular precursor strategy for control of catalyst structure.

Science.gov (United States)

Jarupatrakorn, Jonggol; Don Tilley, T

2002-07-17

A molecular precursor approach involving simple grafting procedures was used to produce site-isolated titanium-supported epoxidation catalysts of high activity and selectivity. The tris(tert-butoxy)siloxy titanium complexes Ti[OSi(O(t)Bu)(3)](4) (TiSi4), ((i)PrO)Ti[OSi(O(t)Bu)(3)](3) (TiSi3), and ((t)BuO)(3)TiOSi(O(t)Bu)(3) (TiSi) react with the hydroxyl groups of amorphous Aerosil, mesoporous MCM-41, and SBA-15 via loss of HO(t)Bu and/or HOSi(O(t)Bu)(3) and introduction of titanium species onto the silica surface. Powder X-ray diffraction, nitrogen adsorption/desorption, infrared, and diffuse reflectance ultraviolet spectroscopies were used to investigate the structures and chemical natures of the surface-bound titanium species. The titanium species exist mainly in isolated, tetrahedral coordination environments. Increasing the number of siloxide ligands in the molecular precursor decreases the amount of titanium that can be introduced this way, but also enhances the catalytic activity and selectivity for the epoxidation of cyclohexene with cumene hydroperoxide as oxidant. In addition, the high surface area mesoporous silicas (MCM-41 and SBA-15) are more effective than amorphous silica as supports for these catalysts. Supporting TiSi3 on the SBA-15 affords highly active cyclohexene epoxidation catalysts (0.25-1.77 wt % Ti loading) that provide turnover frequencies (TOFs) of 500-1500 h(-1) after 1 h (TOFs are reduced by about half after calcination). These results demonstrate that oxygen-rich siloxide complexes of titanium are useful as precursors to supported epoxidation catalysts.

Influence of titanium precursor on photoluminescent emission of micro-cube-shaped CaTiO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Mazzo, Tatiana Martelli, E-mail: tatimazzo@gmail.com [Departamento de Ciências do Mar, Universidade Federal de São Paulo, Avenida Almameda Saldanha da Gama, 89, Ponta da Praia, CEP 11030-400 Santos, SP (Brazil); Santilli do Nascimento Libanori, Gabriela [Departamento de Ciências do Mar, Universidade Federal de São Paulo, Avenida Almameda Saldanha da Gama, 89, Ponta da Praia, CEP 11030-400 Santos, SP (Brazil); Moreira, Mario Lucio [Instituto de Física e Matemática, Universidade Federal de Pelotas, P.O. Box 354, Campus do Capão do Leão, 96001-970 Pelotas, RS (Brazil); Avansi Jr, Waldir [Departamento de Física, Universidade Federal de São Carlos, Jardim Guanabara, 13565-905 São Carlos, SP (Brazil); Mastelaro, Valmor Roberto [Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador São Carlense, 400, Arnold Schimidt, 13566-590 São Carlos, SP (Brazil); Varela, José Arana; Longo, Elson [INCTMN/LIEC, Instituto de Química, Universidade Estadual Paulista, P.O. Box 355, R. Francisco Degni, 55, Bairro Quitandinha, 14801-907 Araraquara, SP (Brazil)

2015-09-15

For this research, we studied the influence of titanium tetrachloride (TC) and titanium tetraisopropoxide (TTP) precursors on CaTiO{sub 3} (CTO) synthesis by employing a microwave-assisted hydrothermal (MAH) method regarding their respective short-, medium- and long-range features to determine if the use of different titanium precursors enhances the structural evolution of the material. The growth mechanism for the formation of the micro-cube-shaped CTO is proposed to obtain nanoparticle aggregation of self-assembly nanoplates. The disorder coupled to the oxygen vacancies of [TiO{sub 5}]–[TiO{sub 6}] in complex clusters in the CTO 1 powder and twists in bonding between the [TiO{sub 6}]–[TiO{sub 6}] complex clusters in the CTO 2 powder were mainly responsible for photoluminescent (PL) emission. - Highlights: • Different titanium precursors enhance the structural evolution of the material. • [TiO{sub 5}]–[TiO{sub 6}] and twists in bonding [TiO{sub 6}]–[TiO{sub 6}] were responsible for PL emission. • Micro-cube shaped was formed by nanoparticle aggregation of self-assembly nanoplates.

Macrocyclic complexes of radionuclides in nuclear medicine

International Nuclear Information System (INIS)

Majkowska, A.; Bilewicz, A.

2008-01-01

The use of radiometal-labeled small complexes and biomolecules as diagnostic and therapeutic agents is a relatively new area of medical research. Radiopharmaceuticals are radiolabeled molecules designed to deliver ionizing radiation doses to specific disease sites. Between the targeting biomolecule and a radionuclide a bifunctional ligand is inserted, one end of which is covalently attached to the targeting molecule either directly or through a linker whereas the other strongly coordinates a metallic radionuclide. Selection of a bifunctional ligand is largely determined by the nature and oxidation state of a metal ion. The metal chelate can significantly affect the tumor uptake and biodistribution of radiopharmaceuticals based on small biomolecules. This is because in many cases the metal chelate contributes greatly to the overall size and lipophilicity of the radiopharmaceutical. Therefore, the design and selection of the ligand is very important for the development of a clinically useful therapeutic agent. The requirement for high thermodynamic and kinetic stability of the metal complex is often achieved through the use of macrocyclic ligands with a functionalized arm for covalent bonding to the biomolecule. In this review synthesis of bifunctional macrocyclic ligands and properties of radionuclide macrocyclic complexes used in nuclear medicine are presented. We describe results in two areas: substituted macrocyclic aza ligands for chelation of hard metal cations, and macrocycles containing sulphur for complexation of soft metal cations. Special attention was paid to stability of the complexes as well as to their lipophilicity, which affect biological properties of the formed radiopharmaceuticals. We also include a forecast of the near-term opportunities that are likely to determine practice in the next few years. (authors)

Chemical changes of titanium and titanium dioxide under electron bombardment

Directory of Open Access Journals (Sweden)

Romins Brasca

2007-09-01

Full Text Available The electron induced effect on the first stages of the titanium (Ti0 oxidation and titanium dioxide (Ti4+ chemical reduction processes has been studied by means of Auger electron spectroscopy. Using factor analysis we found that both processes are characterized by the appearance of an intermediate Ti oxidation state, Ti2O3 (Ti3+.

Complex hydrides for hydrogen storage

Science.gov (United States)

Zidan, Ragaiy

2006-08-22

A hydrogen storage material and process of forming the material is provided in which complex hydrides are combined under conditions of elevated temperatures and/or elevated temperature and pressure with a titanium metal such as titanium butoxide. The resulting fused product exhibits hydrogen desorption kinetics having a first hydrogen release point which occurs at normal atmospheres and at a temperature between 50.degree. C. and 90.degree. C.

Osseointegration is improved by coating titanium implants with a nanostructured thin film with titanium carbide and titanium oxides clustered around graphitic carbon

International Nuclear Information System (INIS)

Veronesi, Francesca; Giavaresi, Gianluca; Fini, Milena; Longo, Giovanni; Ioannidu, Caterina Alexandra; Scotto d'Abusco, Anna; Superti, Fabiana; Panzini, Gianluca; Misiano, Carlo; Palattella, Alberto; Selleri, Paolo; Di Girolamo, Nicola; Garbarino, Viola; Politi, Laura; Scandurra, Roberto

2017-01-01

Titanium implants coated with a 500 nm nanostructured layer, deposited by the Ion Plating Plasma Assisted (IPPA) technology, composed of 60% graphitic carbon, 25% titanium oxides and 15% titanium carbide were implanted into rabbit femurs whilst into the controlateral femurs uncoated titanium implants were inserted as control. At four time points the animals were injected with calcein green, xylenol orange, oxytetracycline and alizarin. After 2, 4 and 8 weeks femurs were removed and processed for histology and static and dynamic histomorphometry for undecalcified bone processing into methylmethacrylate, sectioned, thinned, polished and stained with Toluidine blue and Fast green. The overall bone-implant contacts rate (percentage of bone-implant contacts/weeks) of the TiC coated implant was 1.6 fold than that of the uncoated titanium implant. The histomorphometric analyses confirmed the histological evaluations. More precisely, higher Mineral Apposition Rate (MAR, μm/day) (p < 0.005) and Bone Formation Rate (BFR, μm 2 /μm/day) (p < 0.0005) as well as Bone Implant Contact (Bic) and Bone Ingrowth values (p < 0.0005) were observed for the TiC coated implants compared to uncoated implants. In conclusion the hard nanostructured TiC layer protects the bulk titanium implant against the harsh conditions of biological tissues and in the same time, stimulating adhesion, proliferation and activity of osteoblasts, induces a better bone-implant contacts of the implant compared to the uncoated titanium implant. - Highlights: • Ti implants were coated with a nanostructured film composed of C gr , TiC and TiO x . • The TiC layer stimulates adhesion, proliferation and activity of osteoblasts. • Uncoated and TiC coated titanium implants were implanted in rabbit femurs. • Bone-implant contacts of TiC coated implants were higher than that of uncoated. • Mineral Apposition Rate of TiC coated implants were higher than that of uncoated.

Titanium fasteners. [for aircraft industry

Science.gov (United States)

Phillips, J. L.

1972-01-01

Titanium fasteners are used in large quantities throughout the aircraft industry. Most of this usage is in aluminum structure; where titanium structure exists, titanium fasteners are logically used as well. Titanium fasteners offer potential weight savings to the designer at a cost of approximately $30 per pound of weight saved. Proper and least cost usage must take into consideration type of fastener per application, galvanic couples and installation characteristics of protective coatings, cosmetic appearance, paint adhesion, installation forces and methods available and fatigue performance required.

Chelation-Assisted Substrate-Controlled Asymmetric Lithiation-Allylboration of Chiral Carbamate 1,2,4-Butanetriol Acetonide

Directory of Open Access Journals (Sweden)

Adeem Mahmood

2015-05-01

Full Text Available The lithiation of 2-(2,2-dimethyl-1,3-dioxolan-4-ylethyl diisopropylcarbamate (1 is achieved freely by sec-butyllithium in diethylether with high lk-diastereoselectivity: the bicyclic chelate complexes 3a and 3b are reacted with electrophiles to form optically active precursors 4a and 4b with >95% diastereoselectivity. In addition, tertiary diamines can undergo an external complexation in contest with the internal oxygen ligand, leading to improved stereoselectivities. The further reactions of lithiated carbamates with trans alkenyl-9-BBN derivatives after 1,2 metallate rearrangements, gave the key intermediate α-substituted allylic boranes 7. Subsequent allylboration of aldehydes gave (Z-anti-homoallylic alcohols 8 in good yield and excellent d.r.

Titanium for salt water service

International Nuclear Information System (INIS)

Gadiyar, H.S.; Shibad, P.R.

1980-01-01

Titanium has potential as major material of construction in desalination plants, in condensers and heat exchangers, in view of its excellent corrosion resistance to salt water upto at least 120deg C. The advantages of titanium in such applications are brought out. The various specific problems such as pitting, crevice and galvanic corrosion and the preventive methods, for adopting titanium have been discussed. The hydriding problem can be overcome by suitably controlling the operating parameters such as temperature and surface preparation. A case has been made to prove the economic viability of titanium in comparison to Al-brass and Cu-Ni alloy. The future of titanium seems to be very promising in view of the negligible tube failures and outages. (auth.)

Chelating extractants of improved selectivity. Progress report, September 1, 1976--October 31, 1977

International Nuclear Information System (INIS)

Freiser, H.

1977-07-01

New means of characterizing metal chelating reagent selectivity have been developed and incorporated into a theoretical factor analysis of the chelate stability constants of 24 metal ions with 14 ligands of the EDTA family. The factor analysis will be extended to extracting ligand families. A computer-controlled automated metal chelate stability constant apparatus has been assembled and successfully tested. A high performance liquid chromatograph has been set up and preliminary examination of comparison of reversed phase chromatographic separation of metal ions with their solvent extraction behavior begun

[The surface roughness analysis of the titanium casting founding by a new titanium casting investment material].

Science.gov (United States)

Liang, Qin-ye; Wu, Xia-yi; Lin, Xue-feng

2012-04-01

To investigate the surface roughness property of the titanium castings cast in a new investment for titanium casting. Six wax patterns (20 mm × 20 mm × 0.5 mm) were invested using two investments: three in a new titanium investment material and three in the control material (Rematitan Plus). Six titanium specimens were obtained by conventional casting. After casting, surface roughness of the specimens were evaluated with a surface profilometer. The surface roughness of the specimens cast in new titanium investment material was (1.72 ± 0.08) µm, which was much smaller than that from Rematitan Plus [(1.91 ± 0.15) µm, P cast using these two investment materials are both smooth enough to fulfill the demand of the titanium precision-casting for prosthodontic clinical use.

Bright, Multi-responsive, Sky-Blue Platinum(II) Phosphors Based on a Tetradentate Chelating Framework.

Science.gov (United States)

Liu, Lijie; Wang, Xiang; Wang, Nan; Peng, Tai; Wang, Suning

2017-07-24

A new class of highly efficient and stable, blue-phosphorescent Pt II complexes based on a tetradentate chelating framework has been found to exhibit highly sensitive and reversible responses to multiple external stimuli including temperature, pressure, and UV irradiation with distinct phosphorescent color switching-from blue to red or white. Intermolecular excimer formation is the main origin of this intriguing multi-response phenomenon. Highly efficient singlet-oxygen sensitization by the Pt II compounds yields UV-light-induced phosphorescence enhancement and color switching. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Heterolytic activation of dihydrogen by platinum and palladium complexes

NARCIS (Netherlands)

Almeida Leñero, K.Q.; Guari, Y.; Kramer, P.C.J.; van Leeuwen, P.W.N.M.; Donnadieu, B.; Sabo-Etienne, S.; Chaudret, B.; Lutz, M.; Spek, A.L.

2013-01-01

Wide bite angle diphosphine ligands were used to prepare [(diphosphine)M(2-(diphenylphosphino)pyridine)]2+ complexes (M = Pd, Pt). Except for the ligand with the largest bite angle, 2-(diphenylphosphino)pyridine coordinates in a bidentate mode leading to bis-chelate complexes. In the case of

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

Science.gov (United States)

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

2013-08-05

The influence of dynamics on solution state structure is a widely overlooked consideration in chemistry. Variations in Gd(3+) chelate hydration with changing coordination geometry and dissociative water exchange kinetics substantially impact the effectiveness (or relaxivity) of monohydrated Gd(3+) chelates as T1-shortening contrast agents for MRI. Theory shows that relaxivity is highly dependent upon the Gd(3+)-water proton distance (rGdH), and yet this distance is almost never considered as a variable in assessing the relaxivity of a Gd(3+) chelate as a potential contrast agent. The consequence of this omission can be seen when considering the relaxivity of isomeric Gd(3+) 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 "suboptimal" 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 "suboptimally" exchanging isomer. The difference between the chelates arises from a non-field-dependent parameter: either the hydration number (q) or rGdH. For solution state Gd(3+) 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/rGdH(6)) 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 Gd(3+) chelates. The data presented herein indicate that the changes in the hydration parameter (q/rGdH(6)) associated with changing dissociative

Spectrophotometric study of the complexes of cerium and uranides with diethylenetetraaminepentaacetic acid (DTPA); Contribution a l'etude de la complexation du cerium et des uranides par l'acide diethylenetetraminepentaacetique (DTPA)

Energy Technology Data Exchange (ETDEWEB)

Hafez, M B [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1968-03-01

A spectrophotometric determination was made of the complexes of cerium and uranides in their different degrees of oxidation with diethylenetriaminepentaacetic acid (DTPA). Two physico-chemical states, the ionic and hydrolysis ones, were considered. In the former case, we studied the influence of the pH on the formation of the complex, and whenever the complexes were stable, we determined the molecular ratio and calculated their stability constants. In the latter case, we studied the conditions of solubilization of the precipitate by formation of complexes soluble in water as a function of pH, age of the precipitate and time of precipitate-chelate contact. (authors) [French] Etude spectrophotometrique de la complexation du cerium et des uranides (uranium, neptunium, plutonium et americium) dans leurs differents etats d'oxydation par l'acide diethylenetriaminepentaacetique (DTPA). Deux etats physicochimiques ont retenu notre attention, l'etat ionique et l'etat precipite d'hydrolyse. Dans le premier cas, nous avons etudie l'influence du pH sur la formation du complexe, et dans tous les cas ou le complexe est stable, nous avons determine le rapport moleculaire (5) [element]/[chelatant] du complexe forme et nous avons calcule leurs constantes de stabilite. Dans le deuxieme cas, l'etat de precipite d'hydrolyse, nous avons etudie les conditions de solubilisation du precipite, par formation du complexe, en fonction du pH, de l'age du precipite et du temps de contact precipite - chelatant. (auteurs)

Chelating extractants of improved selectivity. Progress report, 1 August 1979-31 July 1980

International Nuclear Information System (INIS)

1980-01-01

During the current contract year, mixed ligand chelate extraction systems for separating lanthanides was extended to elucidating the underlying reasons for the observed enhancement by quaternary ammonium salts. Equilibrium studies reveal the formation of anionic complexes (LnL 4 .HL - ) (where HL is 8-quinolinol) that was extracted when paired with a quaternary ammonium ion. Lathanum, as a lone exception was extracted as R 4 N + , LaL 4 - . Work is underway in the application of similar extractants, 5,7-dibromo-8-quinolinol and Kelex 100 (a 7-alkenyl-8-quinolinol) to the separation of lanthanides

Oxidative degradation stability and hydrogen sulfide removal performance of dual-ligand iron chelate of Fe-EDTA/CA.

Science.gov (United States)

Miao, Xinmei; Ma, Yiwen; Chen, Zezhi; Gong, Huijuan

2017-09-05

Catalytic oxidation desulfurization using chelated iron catalyst is an effective method to remove H 2 S from various gas streams including biogas. However, the ligand of ethylenediaminetetraacetic acid (EDTA), which is usually adopted to prepare chelated iron catalyst, is liable to be oxidative degraded, and leads to the loss of desulfurization performance. In order to improve the degradation stability of the iron chelate, a series of iron chelates composed of two ligands including citric acid (CA) and EDTA were prepared and the oxidative degradation stability as well as desulfurization performance of these chelated iron catalysts were studied. Results show that the iron chelate of Fe-CA is more stable than Fe-EDTA, while for the desulfurization performance, the situation is converse. For the dual-ligand iron chelates of Fe-EDTA/CA, with the increase of mol ratio of CA to EDTA in the iron chelate solution, the oxidative degradation stability increased while the desulfurization performance decreased. The results of this work showed that Fe-EDTA/CA with a mol ratio of CA:EDTA = 1:1 presents a relative high oxidative degradation stability and an acceptable desulfurization performance with over 90% of H 2 S removal efficiency.

High precision isotopic ratio analysis of volatile metal chelates

International Nuclear Information System (INIS)

Hachey, D.L.; Blais, J.C.; Klein, P.D.

1980-01-01

High precision isotope ratio measurements have been made for a series of volatile alkaline earth and transition metal chelates using conventional GC/MS instrumentation. Electron ionization was used for alkaline earth chelates, whereas isobutane chemical ionization was used for transition metal studies. Natural isotopic abundances were determined for a series of Mg, Ca, Cr, Fe, Ni, Cu, Cd, and Zn chelates. Absolute accuracy ranged between 0.01 and 1.19 at. %. Absolute precision ranged between +-0.01-0.27 at. % (RSD +- 0.07-10.26%) for elements that contained as many as eight natural isotopes. Calibration curves were prepared using natural abundance metals and their enriched 50 Cr, 60 Ni, and 65 Cu isotopes covering the range 0.1-1010.7 at. % excess. A separate multiple isotope calibration curve was similarly prepared using enriched 60 Ni (0.02-2.15 at. % excess) and 62 Ni (0.23-18.5 at. % excess). The samples were analyzed by GC/CI/MS. Human plasma, containing enriched 26 Mg and 44 Ca, was analyzed by EI/MS. 1 figure, 5 tables

Numerical assessment of bone remodeling around conventionally and early loaded titanium and titanium-zirconium alloy dental implants.

Science.gov (United States)

Akça, Kıvanç; Eser, Atılım; Çavuşoğlu, Yeliz; Sağırkaya, Elçin; Çehreli, Murat Cavit

2015-05-01

The aim of this study was to investigate conventionally and early loaded titanium and titanium-zirconium alloy implants by three-dimensional finite element stress analysis. Three-dimensional model of a dental implant was created and a thread area was established as a region of interest in trabecular bone to study a localized part of the global model with a refined mesh. The peri-implant tissues around conventionally loaded (model 1) and early loaded (model 2) implants were implemented and were used to explore principal stresses, displacement values, and equivalent strains in the peri-implant region of titanium and titanium-zirconium implants under static load of 300 N with or without 30° inclination applied on top of the abutment surface. Under axial loading, principal stresses in both models were comparable for both implants and models. Under oblique loading, principal stresses around titanium-zirconium implants were slightly higher in both models. Comparable stress magnitudes were observed in both models. The displacement values and equivalent strain amplitudes around both implants and models were similar. Peri-implant bone around titanium and titanium-zirconium implants experiences similar stress magnitudes coupled with intraosseous implant displacement values under conventional loading and early loading simulations. Titanium-zirconium implants have biomechanical outcome comparable to conventional titanium implants under conventional loading and early loading.

Red Blood Cell Transfusion Independence Following the Initiation of Iron Chelation Therapy in Myelodysplastic Syndrome

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Maha A. Badawi

2010-01-01

Full Text Available Iron chelation therapy is often used to treat iron overload in patients requiring transfusion of red blood cells (RBC. A 76-year-old man with MDS type refractory cytopenia with multilineage dysplasia, intermediate-1 IPSS risk, was referred when he became transfusion dependent. He declined infusional chelation but subsequently accepted oral therapy. Following the initiation of chelation, RBC transfusion requirement ceased and he remained transfusion independent over 40 months later. Over the same time course, ferritin levels decreased but did not normalize. There have been eighteen other MDS patients reported showing improvement in hemoglobin level with iron chelation; nine became transfusion independent, nine had decreased transfusion requirements, and some showed improved trilineage myelopoiesis. The clinical features of these patients are summarized and possible mechanisms for such an effect of iron chelation on cytopenias are discussed.

Hydrogen storage via polyhydride complexes

Energy Technology Data Exchange (ETDEWEB)

Jensen, C.M.; Zidan, R.A. [Univ. of Hawaii, Honolulu, HI (United States)

1998-08-01

The reversible dehydrogenation of NaAlH{sub 4} is catalyzed in toluene slurries of the NaAlH{sub 4} containing the pincer complex, IrH{sub 4} {l_brace}C{sub 6}H{sub 3}-2,6-(CH{sub 2}PBu{sup t}{sub 2}){sub 2}{r_brace}. The rates of the pincer complex catalyzed dehydrogenation are about five times greater those previously found for NaAlH{sub 4} that was doped with titanium through a wet chemistry method. Homogenization of NaAlH{sub 4} with 2 mole % Ti(OBu{sup n}){sub 4} under an atmosphere of argon produces a novel titanium containing material. TPD measurements show that the dehydrogenation of this material occurs about 30 C lower than that previously found for wet titanium doped NaAlH{sub 4}. In further contrast to wet doped NaAlH{sub 4}, the dehydrogenation kinetics and hydrogen capacity of the novel material are undiminished over several dehydriding/hydriding cycles. Rehydrogenation of the titanium doped material occurs readily at 170 C under 150 atm of hydrogen. TPD measurements show that about 80% of the original hydrogen content (4.2 wt%) can be restored under these conditions.

Reaction of gadolinium chelates with ozone and hydroxyl radicals.

Science.gov (United States)

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

2013-09-03

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

Anodic growth of titanium dioxide nanostructures

DEFF Research Database (Denmark)

2010-01-01

Disclosed is a method of producing nanostructures of titanium dioxide (TiO 2 ) by anodisation of titanium (Ti) in an electrochemical cell, comprising the steps of: immersing a non-conducting substrate coated with a layer of titanium, defined as the anode, in an electrolyte solution...... an electrical contact to the layer of titanium on the anode, where the electrical contact is made in the electrolyte solution...

Antimicrobial Properties of Copper Nanoparticles and Amino Acid Chelated Copper Nanoparticles Produced by Using a Soya Extract

Science.gov (United States)

DeAlba-Montero, I.; Morales-Sánchez, Elpidio; Araujo-Martínez, Rene

2017-01-01

This paper reports a comparison of the antibacterial properties of copper-amino acids chelates and copper nanoparticles against Escherichia coli, Staphylococcus aureus, and Enterococcus faecalis. These copper-amino acids chelates were synthesized by using a soybean aqueous extract and copper nanoparticles were produced using as a starting material the copper-amino acids chelates species. The antibacterial activity of the samples was evaluated by using the standard microdilution method (CLSI M100-S25 January 2015). In the antibacterial activity assays copper ions and copper-EDTA chelates were included as references, so that copper-amino acids chelates can be particularly suitable for acting as an antibacterial agent, so they are excellent candidates for specific applications. Additionally, to confirm the antimicrobial mechanism on bacterial cells, MTT assay (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) was carried out. A significant enhanced antimicrobial activity and a specific strain were found for copper chelates over E. faecalis. Its results would eventually lead to better utilization of copper-amino acids chelate for specific application where copper nanoparticles can be not used. PMID:28286459

REVIEW ARTICLE:Future of Lead Chelation – Distribution and Treatment

Directory of Open Access Journals (Sweden)

Venkatesh Thuppil

2012-01-01

Full Text Available Lead is the major environmental toxin resulting in the ill health and deleterious effect on almost all organs in the human body in a slow and effective manner. The best treatment for lead poisoning is chelation therapy which is next only to prevention. The authors describe the disruption of homeostasis of the human body by lead in various tissues like blood, bones, liver, kidneys and brain; and the ability of lead to enter the cell using calcium channels and calcium receptors like Ca++ dependant K+ ion channels, transient receptor potential channels, T-tubules, calmodulin receptors, inositol trisphosphate receptors and ryanodine receptors. We report a few novel chelating agents like ionophores, decadentate ligands, picolinate ligands, octadentate ligand, allicin, thiamine, that show good potential for being used in chelation therapy. Future of leadpoisoning is a challenge to all and it needs to be meticulously studies to have an economic and health approach.

Isotopic measurement of uranium using NP-type chelate resin beads

International Nuclear Information System (INIS)

Wu Lanbi; Chen Wenpo; Wang Shijun

1994-08-01

NP-type chelate resin beads is used as a carrier of samples in the isotopic measurements of uranium by mass spectrometry. The results show that its absorption efficiency for uranium can be greater than 50%. It is one order magnitude higher than that strong basic anion resin, however, the ionization efficiencies of both are almost the same. Therefore, the amount of uranium required for isotopic analysis can be reduced one order of magnitude. This method has been used for isotopic analysis of uranium in NP-type chelate resin beads contained 10 -9 ∼ 10 -7 g uranium. For standard sample UTB-500, the external precision of measurements are within +-0.2%, for natural uranium samples are within +- 0.5%. The application of NP-type chelate resin beads in the isotopic measurement of uranium is a new creative achievement. It has been used in the depletion test of uranium-atomic vapor laser isotope separation

Radiopharmaceutical chelates and method of external imaging

International Nuclear Information System (INIS)

Loberg, M.D.; Callery, P.S.; Cooper, M.

1977-01-01

A chelate of technetium-99m, cobalt-57, gallium-67, gallium-68, indium-111 or indium-113m and a substituted iminodiacetic acid or an 8-hydroxyquinoline useful as a radiopharmaceutical external imaging agent. The invention also includes preparative methods therefor

Complexes formed by cadmium and chelating agents in plants

International Nuclear Information System (INIS)

Strasdeit, H.; Duhme, A.K.; Johanning, J.

1993-01-01

Measurements of X-ray absorption spectrums and potentiometric titrations yield some information on the basic complexforming properties of phytochelates. Cadmium-phytochelate complexes are extremely variable as regards composition and structure. This is evident from the fact that the metal's coordination environment (sulphur or oxygen coordination) is dependent uopn pH values. At pH values of about 7 it is normal to find Cd(SCys) 4 units. Given the availability of an adequate number of ligands, these are seen to occur as solitary units even in multinucleate complexes. (orig.) [de

Preparation of Ga-67 labeled monoclonal antibodies using deferoxamine as a bifunctional chelating agent

International Nuclear Information System (INIS)

Endo, K.; Furukawa, T.; Ohmomo, Y.

1984-01-01

Ga-67 labeled monoclonal IgG or F(ab')/sub 2/ fragments against α-fetoprotein and β-subunit of human choriogonadotropin (HCG), were prepared using Deferoxamine (DFO) as a bifunctional chelating agent. DFO, a well-known iron chelating agent, was conjugated with monoclonal antibodies (Ab) by a glutaraldehyde two step method and the effect of conjugation on the Ab activities was examined by RIA and Scatchard plot analysis. In both monoclonal Ab preparations, the conjugation reaction was favored as the pH increased. However, Ab-binding activities decreased as the molecular ratios of DFO to Ab increased. Preserved Ab activities were observed when Ab contained DFO per Ab molecule less than 2.1. At a ratio of over 3.3 DFO molecules per Ab, the maximal binding capacity rather than the affinity constant decreased. The inter-molecular cross linkage seemed to be responsible for the deactivation of binding activities. The obtained DFO-Ab conjugates, were then easily labeled with high efficiency and reproducibility and Ga-67 DFO-Ab complexes were highly stable both in vitro and in vivo. Thus, biodistribution of Ga-67 labeled F(ab')/sub 2/ fragments of monoclonal Ab to HCG β-subunit was attempted in nude mice transplanted with HCG-producing human teratocarcinoma. Tumor could be visualized, in spite of relatively high background imaging of liver, kidney and spleen. The use of DFO as a bifunctional chelating agent provided good evidence for its applicability to labeling monoclonal Ab with almost full retention of Ab activities. Further, availability of Ga-68 will make Ga-68 DFO-monoclonal Ab a very useful tool for positron tomography imaging of various tumors

Osseointegration is improved by coating titanium implants with a nanostructured thin film with titanium carbide and titanium oxides clustered around graphitic carbon

Energy Technology Data Exchange (ETDEWEB)

Veronesi, Francesca [Laboratory of Preclinical and Surgical Studies, Rizzoli Orthopedic Institute, Via Di Barbiano 1/10, Bologna 40136 (Italy); Giavaresi, Gianluca; Fini, Milena [Laboratory of Preclinical and Surgical Studies, Rizzoli Orthopedic Institute, Via Di Barbiano 1/10, Bologna 40136 (Italy); Laboratory of Biocompatibility, Innovative Technologies and Advanced Therapies, Department Rizzoli RIT, Via Di Barbiano 1/10, Bologna 40136 (Italy); Longo, Giovanni [CNR Istituto di Struttura della Materia, CNR, Via del Fosso del Cavaliere 100, 00133 Roma (Italy); Ioannidu, Caterina Alexandra; Scotto d' Abusco, Anna [Dept. of Biochemical Sciences, Sapienza University of Roma, Ple A. Moro 5, 00185 Roma (Italy); Superti, Fabiana; Panzini, Gianluca [Dept. of Technologies and Health, Istituto Superiore di Sanità, Viale Regina Elena, 299 Roma (Italy); Misiano, Carlo [Romana Film Sottili, Anzio, Roma (Italy); Palattella, Alberto [Dept. of Clinical Sciences and Translational Medicine, Tor Vergata University, Via Montpellier 1, 00133 Roma (Italy); Selleri, Paolo; Di Girolamo, Nicola [Exotic Animals Clinic, Via S. Giovannini 53, 00137 Roma (Italy); Garbarino, Viola [Dept. of Radiology, S.M. Goretti Hospital, Via G. Reni 2, 04100 Latina (Italy); Politi, Laura [Dept. of Biochemical Sciences, Sapienza University of Roma, Ple A. Moro 5, 00185 Roma (Italy); Scandurra, Roberto, E-mail: roberto.scandurra@uniroma1.it [Dept. of Biochemical Sciences, Sapienza University of Roma, Ple A. Moro 5, 00185 Roma (Italy)

2017-01-01

Titanium implants coated with a 500 nm nanostructured layer, deposited by the Ion Plating Plasma Assisted (IPPA) technology, composed of 60% graphitic carbon, 25% titanium oxides and 15% titanium carbide were implanted into rabbit femurs whilst into the controlateral femurs uncoated titanium implants were inserted as control. At four time points the animals were injected with calcein green, xylenol orange, oxytetracycline and alizarin. After 2, 4 and 8 weeks femurs were removed and processed for histology and static and dynamic histomorphometry for undecalcified bone processing into methylmethacrylate, sectioned, thinned, polished and stained with Toluidine blue and Fast green. The overall bone-implant contacts rate (percentage of bone-implant contacts/weeks) of the TiC coated implant was 1.6 fold than that of the uncoated titanium implant. The histomorphometric analyses confirmed the histological evaluations. More precisely, higher Mineral Apposition Rate (MAR, μm/day) (p < 0.005) and Bone Formation Rate (BFR, μm{sup 2}/μm/day) (p < 0.0005) as well as Bone Implant Contact (Bic) and Bone Ingrowth values (p < 0.0005) were observed for the TiC coated implants compared to uncoated implants. In conclusion the hard nanostructured TiC layer protects the bulk titanium implant against the harsh conditions of biological tissues and in the same time, stimulating adhesion, proliferation and activity of osteoblasts, induces a better bone-implant contacts of the implant compared to the uncoated titanium implant. - Highlights: • Ti implants were coated with a nanostructured film composed of C{sub gr}, TiC and TiO{sub x}. • The TiC layer stimulates adhesion, proliferation and activity of osteoblasts. • Uncoated and TiC coated titanium implants were implanted in rabbit femurs. • Bone-implant contacts of TiC coated implants were higher than that of uncoated. • Mineral Apposition Rate of TiC coated implants were higher than that of uncoated.

Preparation and Properties of the Chitosan/PVA Blend for Heavy Metals Chelation

Directory of Open Access Journals (Sweden)

Zuhair Jabbar Abdul Ameer

2016-09-01

Full Text Available Current research based on the use of extracted chitosan mixed with Polyvinyl alcohol to manufacture blend that can been used in water purification from heavy metals such as copper, this due to chitosan properties and its ability to chelation these metals because of the presence of the functional groups in their structure. The blend has been treated with borax to increase the viscosity, and then high density polyethylene granulated coated with polymer solution to increase the surface area for chelation. The ultraviolet test showed the efficiency of blend to chelation of copper ions through lower the copper ions absorbance peak after each stage where the solution of copper ions pass on the polymer blend containing chitosan.

Thermodynamics of the complex formation between thorium(IV) and some polydentate ligands in aqueous solution

International Nuclear Information System (INIS)

Di Bernado, P.; Cassol, A.; Tomat, G.; Bismondo, A.; Magon, L.

1983-01-01

The changes in free energy, enthalpy, and entropy for the formation of thorium(IV)-oxydiacetate, -iminodiacetate, -thiodiacetate, and -succinate complexes have been determined by potentiometric and calorimetric titrations at 25 deg C in aqueous 1 mol dm - 3 sodium perchlorate. All the ligands form 1:1 chelate complexes with the thorium(IV) ion the stability of which is dependent on both the chelate ring dimensions and the nature of the donor group in the chain. The order of the relative stabilities (iminodiacetate > oxydiacetate > thiodiacetate > succinate) is mainly dependent on the reaction enthalpies, since the δS values are close to each other. In the thorium(IV)-oxydiacetate system the maximum number of three ligands for every metal ion was reached. Because of precipitation of solid compounds in the other systems, it was only possible to define complexes with a lower number of co-ordinated ligands: two for succinate and thiodiacetate, and one for iminodiacetate. Owing to the lower stability of the chelate ring of thiodiacetate and succinate complexes and the high basicity of the amino-group of iminodiacetate, these ligands form also unchelated protonated complexes. (author)

The vapour phase deposition of boron on titanium by the reaction between gaseous boron trichloride and titanium metal. Final report

International Nuclear Information System (INIS)

Cameron, D.J.; Shelton, R.A.J.

1965-03-01

The reaction, between boron trichloride vapour and titanium has been investigated in the temperature range 200 - 1350 deg. C. It has been found that an initial reaction leads to the formation of titanium tetrachloride and the deposition of boron on titanium, but that except for reactions between 900 and 1000 deg. C, the system is complicated by the formation of lower titanium chlorides due to secondary reactions between the titanium and titanium tetrachloride

Linear Dimerization of Terminal Alkynes by Bis( tetramethylphenylcyclopentadienyl) Titanium-Magnesium Hydride and Acetylide Complexes

Czech Academy of Sciences Publication Activity Database

Mach, Karel; Gyepes, R.; Horáček, Michal; Petrusová, Lidmila; Kubišta, Jiří

2003-01-01

Roč. 68, č. 10 (2003), s. 1877-1896 ISSN 0010-0765 R&D Projects: GA ČR GA203/02/0774; GA ČR GA203/02/0436 Institutional research plan: CEZ:AV0Z4040901 Keywords : titanium * alkynes * hydrides Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.041, year: 2003

MRI marrow observations in thalassemia: the effects of the primary disease, transfusional therapy, and chelation

International Nuclear Information System (INIS)

Levin, T.L.; Sheth, S.S.; Ruzal-Shapiro, C.; Abramson, S.; Piomelli, S.; Berdon, W.E.

1995-01-01

The magnetic resonance bone marrow patterns in thalassemia were evaluated to determine changes produced by transfusion and chelation therapy. Thirteen patients had T1- and T2-weighted images of the spine, pelvis and femurs. Three received no therapy (age range 2.5-3 years). Three were ''hypertransfused'' (transfused to maintain a hemoglobin greater than 10 g/dl) and not chelated because of age (age range 6 months-8 years). Seven were ''hypertransfused'' and chelated (age range 12-35 years). Signal characteristics of marrow were compared with those of surrounding muscle and fat. Fatty marrow (isointense with subcutaneous fat) was compared with red marrow (hypointense to fat and slightly hyperintense to muscle). Marrow hypointense to muscle was identified as iron deposition within red marrow. The untreated group demonstrated signal consistent with red marrow throughout the central and peripheral skeleton. Hypertransfused but not chelated patients demonstrated marked iron deposition in the central and peripheral skeleton. Hypertransfused and chelated patients demonstrated iron deposition in the central skeleton and a mixed appearance of marrow in the peripheral skeleton. The MR appearance of marrow in thalassemia is a reflection of the patient's transfusion and chelation therapy. Iron deposition occurs despite chelation therapy in sites of active red marrow. As red marrow retreats centrally with age, so does the pattern of iron deposition. The long-term biological effects of this iron deposition are unknown. (orig.). With 8 figs., 1 tab

Synthesis and evaluation of novel bifunctional chelating agents based on 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid for radiolabeling proteins

International Nuclear Information System (INIS)

Chappell, L.L.; Ma, D.; Milenic, D.E.; Garmestani, K.; Venditto, V.; Beitzel, M.P.; Brechbiel, M.W.

2003-01-01

Detailed synthesis of the bifunctional chelating agents 2-methyl-6-(p-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10 -tetraacetic acid (1B4M-DOTA) and 2-(p-isothiocyanatobenzyl)-5, 6-cyclohexano-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetate (CHX-DOTA) are reported. These chelating agents were compared to 2-(p-isothiocyanatobenzyl)-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (C-DOTA) and 1, 4, 7, 10-Tetraaza-N-(1-carboxy-3-(4-nitrophenyl)propyl)-N', N'', N'''-tris(acetic acid) cyclododecane (PA-DOTA) as their 177 Lu radiolabeled conjugates with Herceptin TM . In vitro stability of the immunoconjugates radiolabeled with 177 Lu was assessed by serum stability studies. The in vivo stability of the radiolabeled immunoconjugates and their targeting characteristics were determined by biodistribution studies in LS-174T xenograft tumor-bearing mice. Relative radiolabeling rates and efficiencies were determined for all four immunoconjugates. Insertion of the 1B4M moiety into the DOTA backbone increases radiometal chelation rate and provides complex stability comparable to C-DOTA and PA-DOTA while the CHX-DOTA appears to not form as stable a 177 Lu complex while exhibiting a substantial increase in formation rate. The 1B4M-DOTAmay have potential for radioimmunotherapy applications. Published by Elsevier Inc. All rights reserved

Potentiometric study of Nd3+ chelates of substituted salicylhydroxamic acids

International Nuclear Information System (INIS)

Deshpande, R.G.; Jahagirdar, D.V.

1976-01-01

The interaction of Nd 3+ ion with salicylhydroxamic acid and 5-methyl, 5-chloro, 5-bromo, 5-nitro, 4-chloro, 4-bromo and 3-chloro salicylhydroxamic acids is investigated potentiometrically by Calvin-Bjerrum titration technique at 30 0 +- 0.1 0 and ionic strength μ=0.1 M(NaClO 4 ) in 50% v/v dioxane-water mixtures. Nd 3+ forms only 1:1 chelates with these ligands. The validity of the log K= apk + b relationship is examined for these chelates. (author)

Self-diffusion coefficient of iron as affected by chelating agents using tracer technique

International Nuclear Information System (INIS)

Massoud, M.A.; Abd-El-Sabour, M.F.; Omar, M.A.

1983-01-01

The effect of Fe 2 (So 4 ) 3 , Fe-DTPA, and Fe-EDDHA on the self-diffusion coefficient of Fe in some soils of Egypt was studied. The effect of chelating compounds on the ratio between solid phase fraction of the labile Fe and its concentration in the soil solution (capacity factor) was also studied. The data reveals the following items of more interesting: 1) The use of chelating agents, i.e., DTPA and EDDHA increased the amount of Fe in soil solution, hence the capacity factor was decreased using these compounds. It seems that as the addition of Fe was in the chelated form in soil solution, the slight loss of 59Fe from solution when 59Fe - chelate was used could be attributed to the isotopic exchange with soil Fe. 2) It was found that the addition of either Fe-DTPA or Fe-EDDHA significantly increased the self-diffusion of Fe in soil as compared with Fe 2 (So 4 ) 3 . It was also noticed that the self-diffusion for Fe in the alluvial soil was greater than in the calcareous one due to the instance competition between Ca and Fe for the chelating ligands in the calcareous soil. It was also seen that soil texture affects Fe self-diffusion

Enhanced human bone marrow mesenchymal stem cell functions on cathodic arc plasma-treated titanium

Directory of Open Access Journals (Sweden)

Zhu W

2015-12-01

Full Text Available Wei Zhu,1 George Teel,1 Christopher M O’Brien,1 Taisen Zhuang,1 Michael Keidar,1 Lijie Grace Zhang1–3 1Department of Mechanical and Aerospace Engineering, 2Department of Biomedical Engineering, 3Department of Medicine, The George Washington University, Washington, DC, USA Abstract: Surface modification of titanium for use in orthopedics has been explored for years; however, an ideal method of integrating titanium with native bone is still required to this day. Since human bone cells directly interact with nanostructured extracellular matrices, one of the most promising methods of improving titanium’s osseointegration involves inducing biomimetic nanotopography to enhance cell–implant interaction. In this regard, we explored an approach to functionalize the surface of titanium by depositing a thin film of textured titanium nanoparticles via a cathodic arc discharge plasma. The aim is to improve human bone marrow mesenchymal stem cell (MSC attachment and differentiation and to reduce deleterious effects of more complex surface modification methods. Surface functionalization was analyzed by scanning electron microscopy, atomic force microscopy, contact angle testing, and specific protein adsorption. Scanning electron microscopy and atomic force microscopy examination demonstrate the deposition of titanium nanoparticles and the surface roughness change after coating. The specific fibronectin adsorption was enhanced on the modified titanium surface that associates with the improved hydrophilicity. MSC adhesion and proliferation were significantly promoted on the nanocoated surface. More importantly, compared to bare titanium, greater production of total protein, deposition of calcium mineral, and synthesis of alkaline phosphatase were observed from MSCs on nanocoated titanium after 21 days. The method described herein presents a promising alternative method for inducing more cell favorable nanosurface for improved orthopedic applications

Nanostructured composite TiO{sub 2}/carbon catalysts of high activity for dehydration of n-butanol

Energy Technology Data Exchange (ETDEWEB)

Cyganiuk, Aleksandra [Faculty of Chemistry, Nicolaus Copernicus University, 87-100 Torun (Poland); Klimkiewicz, Roman [Institute of Low Temperature and Structure Research PAN, 50-422 Wroclaw (Poland); Bumajdad, Ali [Faculty of Science, Kuwait University, PO Box 5969 Safat, Kuwait 13060 (Kuwait); Ilnicka, Anna [Faculty of Chemistry, Nicolaus Copernicus University, 87-100 Torun (Poland); Lukaszewicz, Jerzy P., E-mail: jerzy_lukaszewicz@o2.pl [Faculty of Chemistry, Nicolaus Copernicus University, 87-100 Torun (Poland)

2015-08-15

Highlights: • New biotechnological method for fabrication of composite catalysts. • In situ synthesis of nanosized TiO{sub 2} clusters in the carbon matrix. • High dispersion of TiO{sub 2} in carbon matrix. • High catalytic activity achieved for very low active phase content. • Efficient dehydration of n-butanol to butane-1. - Abstract: A novel method of wood impregnation with titanium ions is presented. Titanium(IV) ions were complexed to peroxo/hydroxo complexes which were obtained by treating a TiCl{sub 4} water solution with H{sub 2}O{sub 2}. The solution of chelated titanium ions was used for the impregnation of living stems of Salix viminalis wood. Saturated stems were carbonized at 600–800 °C, yielding a microporous carbon matrix, in which nanoparticles of TiO{sub 2} were uniformly distributed. A series of composite TiO{sub 2}–carbon catalysts was manufactured and tested in the process of n-butanol conversion to butane-1. The composite catalysts exhibited very high selectivity (ca. 80%) and yield (ca. 30%) despite a low content of titanium (ca. 0.5% atomic). The research proved that the proposed functionalization led to high dispersion of the catalytic phase (TiO{sub 2}), which played a crucial role in the catalyst performance. High dispersion of TiO{sub 2} was achieved due to a natural transport of complexed titanium ions in living plant stems.

Determination of Mg(2+) Speciation in a TFSI(-)-Based Ionic Liquid With and Without Chelating Ethers Using Raman Spectroscopy.

Science.gov (United States)

Watkins, Tylan; Buttry, Daniel A

2015-06-11

Raman spectroscopy was employed to assess the complex environment of magnesium salts in the n-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPyrTFSI) room-temperature ionic liquid (RTIL). At room temperature, Mg(TFSI)2 was miscible with BMPyrTFSI and formulated by [Mg(TFSI)2](x)[BMPyrTFSI](1-x) (x ≤ 0.55). Results suggest that at low concentrations of Mg(TFSI)2, anionic complexes in which Mg(2+) is surrounded by at least four TFSI(-) were formed. Above x = 0.2 an average of three TFSI(-) surround each Mg(2+). Below x = 0.12, there is a greater number of monodentate interactions between TFSI(-) oxygens and Mg(2+) cations, whereas above x = 0.12 bidentate ligands dominate. The fraction of TFSI(-) existing in the cis conformation increased with increasing Mg(2+) concentration. Mg(ClO4)2 was also studied as a Mg(2+) source. At equivalent mole fractions to those of the Mg(TFSI)2 salt, Mg(2+) from Mg(ClO4)2 was surrounded by only two TFSI(-) anions as ClO4(-) appeared to compete with TFSI(-) for coordination with Mg(2+). Similar behavior was also observed for the less soluble halide salts MgX2 (X = Cl, Br, I). Additions of chelating ligands were shown to effectively reduce the average number of TFSI(-) around Mg(2+) in a manner consistent with maintaining a sixfold oxygen coordination number around Mg(2+). Furthermore, an alternative class of ionic liquids, known as "solvate" ionic liquids, were produced. In this case glymes (Gm, m + 1 ether oxygens) were mixed with Mg(TFSI)2 so that glymes chelated Mg(2+), creating Mg(Gm)(y)(2+) complexes. The general formula was given by Mg(Gm)(y)(TFSI)2. These solvate ILs melt between 40 and 80 °C. Raman spectra clearly showed the glyme chelating ability and stronger coordination with Mg(2+) with respect to TFSI(-). Finally, linear sweep voltammograms showed the anodic stability of the glymes to improve due to coordination with Mg(2+).

Investigation of a potential macromolecular MRI contrast agent prepared from PPI (G = 2, polypropyleneimine, generation 2) dendrimer bifunctional chelates

Science.gov (United States)

Wang, Jianxin Steven

The long-term objective is to develop magnetic resonance (MR) contrast agents that actively and passively target tumors for diagnosis and therapy. Many diagnostic imaging techniques for cancer lack specificity. A dendrimer based magnetic resonance imaging contrast agent has been developed with large proton relaxation enhancements and high molecular relaxivities. A new type of linear dendrimer based MRI contrast agent that is built from the polypropyleneimine and polyamidoamine dendrimers in which free amines have been conjugated to the chelate DTPA, which further formed the complex with Gadolinium (Gd) was studied. The specific research goals were to test the hypothesis that a linear chelate with macromolecular agents can be used in vitro and in vivo. This work successfully examined the adequacy and viability of the application for this agent in vitro and in vivo. A small animal whole body counter was designed and constructed to allow us to monitor biodistribution and kinetic mechanisms using a radioisotope labeled complex. The procedures of metal labeling, separation and purification have been established from this work. A biodistribution study has been performed using radioisotope induced organ/tissue counting and gamma camera imaging. The ratio of percentage of injected dose per gram organ/tissue for kidney and liver is 3.71 from whole body counter and 3.77 from the gamma camera. The results suggested that retention of Gd (III) is too high and a more kinetically stable chelate should be developed. The pharmacokinetic was evaluated in the whole animal model with the whole body clearance, and a kinetics model was developed. The pharmacokinetic results showed a bi-exponential decay in the animal model with two component excretion constants 1.43e(-5) and 0.0038511, which give half-lives of 3 hours and 33.6 days, respectively. Magnetic resonance imaging of this complex resulted in a 52% contrast enhancement in the rat kidney following the agents' administration in

Preparation, characterization, magnetic and thermal studies of some chelate polymers of first series transition metal ions

International Nuclear Information System (INIS)

Ukey, Vaishali V.; Juneja, H.D.; Borkar, S.D.; Ghubde, R.S.; Naz, S.

2006-01-01

Azelaoyl-bis-hydroxamic acid used as bis ligand for the preparation of chelate polymers of Mn(II), Co(II), Ni(II) and Zn(II). These chelate polymers have been synthesized by refluxing the metal acetate and bis ligand as 1:1 stoichiometry. In the present work, structural determination of these newly synthesized chelate polymers has been studied on the basis of elemental analyses, infrared and reflectance spectral, magnetic and thermal studies. The decomposition temperature and the order of reaction have been determined by TGA analysis. On the basis of these studies, the Zn(II) chelate polymer has tetrahedral geometry, whereas Mn(II), Co(II) and Ni(II) chelate polymers have octahedral geometry and have the thermal stability in the order Ni(II) > Mn(II) > Zn(II) > Co(II)

Organo-gallium and indium complexes with dithiolate and oxo ligands

Indian Academy of Sciences (India)

Page 1 ... of several of these com- plexes have been established by single crystal X-ray diffraction analyses. Complexes derived from oxo ligands ... diode) applications.8. Organometallic complexes derived from chelating ligands, such as substituted. 8-hydroxyqunoline and azomethine linkages, are emerging as potential ...

Titanium minerals of placer deposits as a source for new materials

Science.gov (United States)

Kotova, Olga; Ponaryadov, Alexey

2015-04-01

Heavy mineral deposits are a source of the economic important element titanium, which is contained in ilmenite and leucoxene. The mineral composition of placer titanium ore and localization pattern of ore minerals determine their processing and enriching technologies. New data on the mineralogy of titanium ores from modern coastal-marine placer in Stradbroke Island, Eastern Australia, and Pizhma paleoplacer in Middle Timan, Russia, and materials on their basis are presented. The samples were studied by the following methods: optical-mineralogical (stereomicroscope MBS-10, polarizing microscope POLAM L-311), semiquantitative x-ray phase analysis (x-ray difractometer X'Pert PRO MPD). Besides microprobe (VEGA 3 TESCAN) and x-ray fluorescent analysis (XRF-1800 Shimadzu) were used. By the mineralogical composition ores of the both deposits are complex: enriched by valuable minerals. Apart from main ore concentrates it is possible to obtain accompanying nonmetallic products. This will increase the efficiency of deposit exploitation. Ilmenite dominates in ore sands of Stradbroke Island, and leucoxene dominates in the ores of the Pizhma titanium deposit. Australian ilmenite and its altered varieties are mainly characterized by a very high MnO content (from 5.24 to 11.08 %). The irregular distribution of iron oxides, titanium and manganese in the altered ilmenite was shown in the paper. E.g., in the areas of substitution of ilmenite by pseudorutile the concentrations of the given elements are greatly various due to various ratios of basic components in each grain. Their ratios are equal in the area of rutile evolution. Moreover, the high content of gold, diamonds and also rare earth elements (REE) and rare metals (their forms are not determined) were studied. We found native copper on the surface of minerals composing titanium-bearing sandstones of the Pizhma placer. According to the technological features of rocks (density and magnetic) studied placers are close. The

Thermodynamic analysis of salt corrosion of titanium alloys

International Nuclear Information System (INIS)

Travkin, V.V.; Pshirkov, V.F.; Kolachev, B.A.

1979-01-01

About 200 possible chemical reactions of metals, salts and oxides (in a solid state) with water (in a vapour state), and with gases (O 2 , Cl 2 , HCl) were studied by the thermodynamic analysis to elucidate a chemical nature of processes taking place at salt corrosion of titanium alloys (VT22, VT6 and VT16). Temperature dependences of isobaric-isothermic potential were considered to reveal a possibility of spontaneous course and direction of reactions as well as to obtain a comparative estimate of the probability of their pro-cedure. Thermodynamically possible schemes of the chemism of titanium alloy salt corrosion are proposed. Complex che-mical reactions take place in the presence of salt, moisture and oxygen of air on the surface of the alloys. The reactions proceed with the formation of titanium and alloying component chlorides, free chlorine and hydrogen. The free chlorine or HCl are released during pyrohydrolysis and oxidation of chlo-rides. The former ones interact with the alloy with the formation of salts, and hydrogen may be absorbed by the metal and cause embrittlement. Chlorides on the metal surface accelerate the chlorination process. NaCl acts as a cata-lyst. The determination of salt corrosion products has confirmed the process mechanism proposed

CaNa2EDTA chelation attenuates cell damage in workers exposed to lead--a pilot study.

Science.gov (United States)

Čabarkapa, A; Borozan, S; Živković, L; Stojanović, S; Milanović-Čabarkapa, M; Bajić, V; Spremo-Potparević, B

2015-12-05

Lead induced oxidative cellular damage and long-term persistence of associated adverse effects increases risk of late-onset diseases. CaNa2EDTA chelation is known to remove contaminating metals and to reduce free radical production. The objective was to investigate the impact of chelation therapy on modulation of lead induced cellular damage, restoration of altered enzyme activities and lipid homeostasis in peripheral blood of workers exposed to lead, by comparing the selected biomarkers obtained prior and after five-day CaNa2EDTA chelation intervention. The group of smelting factory workers diagnosed with lead intoxication and current lead exposure 5.8 ± 1.2 years were administered five-day CaNa2EDTA chelation. Elevated baseline activity of antioxidant enzymes Cu, Zn-SOD and CAT as well as depleted thiols and increased protein degradation products-carbonyl groups and nitrites, pointing to Pb induced oxidative damage, were restored toward normal values following the treatment. Lead showed inhibitor potency on both RBC AChE and BChE in exposed workers, and chelation re-established the activity of BChE, while RBC AChE remained unaffected. Also, genotoxic effect of lead detected in peripheral blood lymphocytes was significantly decreased after therapy, exhibiting 18.9% DNA damage reduction. Administration of chelation reversed the depressed activity of serum PON 1 and significantly decreased lipid peroxidation detected by the post-chelation reduction of MDA levels. Lactate dehydrogenase LDH1-5 isoenzymes levels showed evident but no significant trend of restoring toward normal control values following chelation. CaNa2EDTA chelation ameliorates the alterations linked with Pb mediated oxidative stress, indicating possible benefits in reducing health risks associated with increased oxidative damage in lead exposed populations. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Preparation and examination of properties of samarium-153-EDTMP complex

International Nuclear Information System (INIS)

Nowak, M.; Garnuszek, P.; Lukasiewicz, A.; Wozniak, I.; Zulczyk, W.; Licinska, I.

1995-01-01

Preparation and properties of ethylenediaminetetramethylenephosphonic acid (EDTMP) as well as some properties of 153 Sm-EDTMP chelate have been examined. The chelate formed by samarium-153 (46.3 h, β - -decay) with EDTMP exhibits high bone uptake and can be used for treatment of disseminated, painful skeletal metastases. The purity and stability of solutions of 153 Sm-EDTMP chelate were examined in a broad range of samarium concentration and 153 Sm specific activity. The complex under study was examined by radio-TLC, -electrophoresis and radio-HPLC. The results obtained suggest the small size of molecules of 153 Sm-EDTMP chelate as compared with molecules of ''free''EDTMP. The results of biodistribution of 153 Sm-EDTMP determined in rats indicate the quick blood clearance, high deposition of radioactivity in bone and quick excretion of radioactivity into urine. No specific uptake of 153 Sm-EDTMP in extra-skeletal organs was found. (author). 42 refs, 13 figs, 22 tabs

Isolation and Utilization of Corn Cobs Hemisellulose as Chelating Agent for Lead Ions

International Nuclear Information System (INIS)

Muchlisyam; Harahap, U; Silalahi, J.; Zul Alfian

2013-01-01

Corn cobs is an agricultural byproduct containing polysaccharide composed of cellulose, hemicelluloses and lignin. Hemicelluloses has a hydroxyl and carbonyl functional groups which can be used as chelating agent for metal ions. The purpose of this study was to isolate and evaluate corncobs hemicelluloses as a chelating agent toward lead ion. Graphite furnace spectrophotometry at 283.3 nm was used to determine the residual lead ion in solution. The research's result showed that the highest yield of hemicelluloses (12.04 %) was obtained from delignication with 0,03 M NaOH in 60 % ethanol and 3 % H 2 O 2 , hemicelluloses isolation with 500 ml of 0.2 M NaOH, and precipitation with 1:4 ratio of 10 % acetic acid in 95 % ethanol. The 300 mg corn cobs hemicelluloses has chelating effect for 40 mg lead solution at (39.52±0.1350) mg or 98.80 %, that the corn cobs hemicelluloses can be used as a chelating agent for lead. (author)

Process for making a titanium diboride-chromium diboride-yttrium titanium oxide ceramic composition

Science.gov (United States)

Holcombe, C.E.; Dykes, N.L.

1992-04-28

A ceramic composition is described. The ceramic composition consists essentially of from about 84 to 96 w/o titanium diboride, from about 1 to 9 w/o chromium diboride, and from about 3 to about 15 w/o yttrium-titanium-oxide. A method of making the ceramic composition is also described. The method of making the ceramic composition comprises the following steps: Step 1--A consolidated body containing stoichiometric quantities of titanium diboride and chromium diboride is provided. Step 2--The consolidated body is enclosed in and in contact with a thermally insulated package of yttria granules having a thickness of at least 0.5 inches. Step 3--The consolidated body enclosed in the thermally insulated package of yttria granules is heated in a microwave oven with microwave energy to a temperature equal to or greater than 1,900 degrees centigrade to sinter and uniformly disperse yttria particles having a size range from about 1 to about 12 microns throughout the consolidated body forming a densified body consisting essentially of titanium diboride, chromium diboride, and yttrium-titanium-oxide. The resulting densified body has enhanced fracture toughness and hardness. No Drawings

Study of chelating agent as a surface modifier for retarding corrosion attack on ferrous metal

International Nuclear Information System (INIS)

Nur Ubaidah Saidin; Muhamad Daud; Siti Radiah Mohd Kamarudin; Zaifol Samsu; Azali Muhamad; Rusni Rejab; Mohd Saari Ripin; Mohd Shariff Sattar

2010-01-01

A different concentration of chelating agents in electrolyte of 3.5 % NaCl was applied to bare ferrous metal and tested for their effectiveness as a corrosion retardant. The performance of the samples was measured using corrosion measurement system. The results indicated that the contribution of chelating agent was expediting the reduction of the passive film. The anodic behavior was clearly found to be influenced by the concentration of the chelating agent. It was also found that some of the corrosion was apparently converted to protective layer over a period of time. Excessive moisture caused breakdown of film by removing the unreacted chelating agent and causing regrowth of the existing rust. (author)

Colour interceptions, thermal stability and surface morphology of polyester metal complexes

International Nuclear Information System (INIS)

Zohdy, M.H.

2005-01-01

Chelating copolymers via grafting of acrylic acid (AAc) and acrylamide (AAm/AAc) comonomer mixture onto polyester micro fiber fabrics (PETMF) using gamma-radiation technique were prepared. The prepared graft chains (PETMF-g-AAc) and (PETMF-g-PAAc/PAAm) acted as chelating sites for some selected transition metal ions. The prepared graft copolymers and their metal complexes were characterized using thermogravimetric analysis (TGA), colour parameters and surface morphology measurements. The colour interception and strength measurements showed that the metal complexation is homogeneously distributed. The results showed that the thermal stability of PETMF was improved after graft copolymerization and metal complexes. Moreover, the degree of grafting enhanced the thermal stability values of the grafted and complexed copolymers up to 25% of magnitude, on the other hand the activation energy of the grafted-copolymer with acrylic acid increased up to 80%. The SEM observation gives further supports to the homogenous distribution of grafting and metal complexation

Chelation and stabilization of berkelium in oxidation state +IV

Science.gov (United States)

Deblonde, Gauthier J.-P.; Sturzbecher-Hoehne, Manuel; Rupert, Peter B.; An, Dahlia D.; Illy, Marie-Claire; Ralston, Corie Y.; Brabec, Jiri; de Jong, Wibe A.; Strong, Roland K.; Abergel, Rebecca J.

2017-09-01

Berkelium (Bk) has been predicted to be the only transplutonium element able to exhibit both +III and +IV oxidation states in solution, but evidence of a stable oxidized Bk chelate has so far remained elusive. Here we describe the stabilization of the heaviest 4+ ion of the periodic table, under mild aqueous conditions, using a siderophore derivative. The resulting Bk(IV) complex exhibits luminescence via sensitization through an intramolecular antenna effect. This neutral Bk(IV) coordination compound is not sequestered by the protein siderocalin—a mammalian metal transporter—in contrast to the negatively charged species obtained with neighbouring trivalent actinides americium, curium and californium (Cf). The corresponding Cf(III)-ligand-protein ternary adduct was characterized by X-ray diffraction analysis. Combined with theoretical predictions, these data add significant insight to the field of transplutonium chemistry, and may lead to innovative Bk separation and purification processes.

DNA-protein complexes induced by chromate and other carcinogens

International Nuclear Information System (INIS)

Costa, M.

1991-01-01

DNA-protein complexes induced in intact Chinese hamster ovary cells by chromate have been isolated, analyzed, and compared with those induced by cis-platinum, ultraviolet light, and formaldehyde. Actin has been identified as one of the major proteins complexed to DNA by chromate based upon its molecular weight, isoelectric point, positive reaction with an actin polyclonal antibody, and proteolytic mapping. Chromate and cis-platinum both complex proteins of similar molecular weight and isoelectric point, positive reaction with an actin polyclonal antibody, and proteolytic mapping. Chromate and cis-platinum both complex proteins of similar molecular weight and isoelectric points, and these complexes can be disrupted by chelating agents and sulfhydryl reducing agents, suggesting that the metal itself is participating in binding rather than having a catalytic or indirect role (i.e., oxygen radicals). In contrast, formaldehyde complexed histones to the DNA, and these complexes were not disrupted by chelating or reducing agents. An antiserum raised to chromate-induced DNA-protein complexes reacted primarily with 97,000 kDa protein that did not silver stain. Slot blots, as well as Western blots, were used to detect formation of p97 DNA crosslinks. This protein was complexed to the DNA by all four agents studied

Mechanisms of Fe biofortification and mitigation of Cd accumulation in rice (Oryza sativa L.) grown hydroponically with Fe chelate fertilization.

Science.gov (United States)

Chen, Zhe; Tang, Ye-Tao; Zhou, Can; Xie, Shu-Ting; Xiao, Shi; Baker, Alan J M; Qiu, Rong-Liang

2017-05-01

Cadmium contaminated rice from China has become a global food safety issue. Some research has suggested that chelate addition to substrates can affect metal speciation and plant metal content. We investigated the mitigation of Cd accumulation in hydroponically-grown rice supplied with EDTANa 2 Fe(II) or EDDHAFe(III). A japonica rice variety (Nipponbare) was grown in modified Kimura B solution containing three concentrations (0, 10, 100 μΜ) of the iron chelates EDTANa 2 Fe(II) or EDDHAFe(III) and 1 μΜ Cd. Metal speciation in solution was simulated by Geochem-EZ; growth and photosynthetic efficiency of rice were evaluated, and accumulation of Cd and Fe in plant parts was determined. Net Cd fluxes in the meristematic zone, growth zone, and maturation zone of roots were monitored by a non-invasive micro-test technology. Expression of Fe- and Cd-related genes in Fe-sufficient or Fe-deficient roots and leaves were studied by QRT-PCR. Compared to Fe deficiency, a sufficient or excess supply of Fe chelates significantly enhanced rice growth by elevating photosynthetic efficiency. Both Fe chelates increased the Fe content and decreased the Cd content of rice organs, except for the Cd content of roots treated with excess EDDHAFe(III). Compared to EDDHAFe(III), EDTANa 2 Fe(II) exhibited better mitigation of Cd accumulation in rice by generating the EDTANa 2 Cd complex in solution, decreasing net Cd influx and increasing net Cd efflux in root micro-zones. Application of EDTANa 2 Fe(II) and EDDHAFe(III) also reduced Cd accumulation in rice by inhibiting expression of genes involved in transport of Fe and Cd in the xylem and phloem. The 'win-win' situation of Fe biofortification and Cd mitigation in rice was achieved by application of Fe chelates. Root-to-stem xylem transport of Cd and redistribution of Cd in leaves by phloem transport can be regulated in rice through the use of Fe chelates that influence Fe availability and Fe-related gene expression. Fe fertilization

40 CFR 180.1195 - Titanium dioxide.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Titanium dioxide. 180.1195 Section 180.1195 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS... Titanium dioxide. Titanium dioxide is exempted from the requirement of a tolerance for residues in or on...

Advances in cost effective processing of titanium

International Nuclear Information System (INIS)

Nelson, O.E.

1993-01-01

Recently an industry expert pointed out that one of the greatest hindrances to the growth of titanium usage has been the low percentage of material usable in the final product. Due to the extensive processing, forming, and machining operations typically performed on titanium, yield losses are high. This is especially true in aerospace applications where most titanium is used. In engine components, the start to finish ratio, known as the buy to fly ratio, is often as high as 7 to 1. This can be illustrated by looking at the use of titanium in Pratt and Whitney engines. In the JT-8D-217 used on Boeing's 737-200, the titanium buyweight is 5,385 pounds, whereas the finished titanium, flyweight is just 758 pounds. This start to finish ratio is 7.1:1, giving titanium 17.0% of total engine weight. (orig.)

Mechanism and efficiency of cell death of type II photosensitizers: effect of zinc chelation.

Science.gov (United States)

Pavani, Christiane; Iamamoto, Yassuko; Baptista, Maurício S

2012-01-01

A series of meso-substituted tetra-cationic porphyrins, which have methyl and octyl substituents, was studied in order to understand the effect of zinc chelation and photosensitizer subcellular localization in the mechanism of cell death. Zinc chelation does not change the photophysical properties of the photosensitizers (all molecules studied are type II photosensitizers) but affects considerably the interaction of the porphyrins with membranes, reducing mitochondrial accumulation. The total amount of intracellular reactive species induced by treating cells with photosensitizer and light is similar for zinc-chelated and free-base porphyrins that have the same alkyl substituent. Zinc-chelated porphyrins, which are poorly accumulated in mitochondria, show higher efficiency of cell death with features of apoptosis (higher MTT response compared with trypan blue staining, specific acridine orange/ethidium bromide staining, loss of mitochondrial transmembrane potential, stronger cytochrome c release and larger sub-G1 cell population), whereas nonchelated porphyrins, which are considerably more concentrated in mitochondria, triggered mainly necrotic cell death. We hypothesized that zinc-chelation protects the photoinduced properties of the porphyrins in the mitochondrial environment. © 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.

Effect of the chelation of metal cation on the antioxidant activity of chondroitin sulfates.

Science.gov (United States)

Ajisaka, Katsumi; Oyanagi, Yutaka; Miyazaki, Tatsuo; Suzuki, Yasuhiro

2016-06-01

The antioxidant potencies of chondroitin sulfates (CSs) from shark cartilage, salmon cartilage, bovine trachea, and porcine intestinal mucosa were compared by three representative methods for the measurement of the antioxidant activity; DPPH radical scavenging activity, superoxide radical scavenging activity, and hydroxyl radical scavenging activity. CSs from salmon cartilage and bovine trachea showed higher potency in comparison with CSs from shark cartilage and porcine intestinal mucosa. Next, CS from salmon cartilage chelating with Ca(2+), Mg(2+), Mn(2+), or Zn(2+) were prepared, and their antioxidant potencies were compared. CS chelating with Ca(2+) or Mg(2+) ions showed rather decreased DPPH radical scavenging activity in comparison with CS of H(+) form. In contrast, CS chelating with Ca(2+) or Mg(2+) ion showed remarkably enhanced superoxide radical scavenging activity than CS of H(+) or Na(+) form. Moreover, CS chelating with divalent metal ions, Ca(2+), Mg(2+), Mn(2+), or Zn(2+), showed noticeably higher hydroxyl radical scavenging activity than CS of H(+) or Na(+) form. The present results revealed that the scavenging activities of, at least, superoxide radical and hydroxyl radical were enhanced by the chelation with divalent metal ions.

Electron beam melting of sponge titanium

International Nuclear Information System (INIS)

Kanayama, Hiroshi; Kusamichi, Tatsuhiko; Muraoka, Tetsuhiro; Onouye, Toshio; Nishimura, Takashi

1991-01-01

Fundamental investigations were done on electron beam (EB) melting of sponge titanium by using 80 kW EB melting furnace. Results obtained are as follows: (1) To increase the melting yield of titanium in EB melting of sponge titanium, it is important to recover splashed metal by installation of water-cooled copper wall around the hearth and to decrease evaporation loss of titanium by keeping the surface temperature of molten metal just above the melting temperature of titanium without local heating. (2) Specific power consumption of drip melting of pressed sponge titanium bar and hearth melting of sponge titanium are approximately 0.9 kWh/kg-Ti and 0.5-0.7 kWh/kg-Ti, respectively. (3) Ratios of the heat conducted to water-cooled mould in the drip melting and to water-cooled hearth in the hearth melting to the electron beam input power are 50-65% and 60-65%, respectively. (4) Surface defects of EB-melted ingots include rap which occurs when the EB output is excessively great, and transverse cracks when the EB output is excessively small. To prevent surface defects, the up-down withdrawal method is effective. (author)

Positron annihilation in hydrogenated and electron-irradiated titanium alloys

International Nuclear Information System (INIS)

Mukashev, K.M.; Zaikin, Yu.A.

2002-01-01

Important information on hydrogen behavior in titanium can be obtained from studies of radiation damage in previously hydrogenated metal. For this purpose annealed titanium samples were hydrogenated at the temperature 500 deg. C during 1 hour. Then both the original annealed samples and hydrogenated samples were irradiated by 4 MeV electrons in the fluence range 3·10 7 -1·10 19 cm - 2 at the temperature 60 deg. C. It is known that electron irradiation in these conditions predominantly creates vacancy-type defects with an average radius R ν =0.81 Angstrom. It was stated that annihilation probability after electron irradiation of previously hydrogenated titanium samples always has some intermediate values between those characteristic for hydrogenated and irradiated states of previously annealed metal. This is a reason to suppose that radiation defects of the vacancy type in previously hydrogenated titanium combine with hydrogen atoms in favorable conditions of their partial ionization. The estimated value of the average radius for such a complex is R ν =1.1 Angstrom, that is higher than vacancy size but lower than an atom radius. No dose dependence of hydrogen interaction with radiation defects was observed in our experiments.The results of isochrone annealing of the materials under study have shown that the single annealing recovery stage with activation energy E a equal to 1.22 eV is observed in electron irradiated but not previously hydrogenated titanium in the temperature range 170-240 deg. C. Electron irradiation of the previously hydrogenated metal shifts beginning of the first recovery stage to the temperature about 225-230 deg. C and finishes near the temperature 330 deg. C. Therefore, the bound state vacancy-hydrogen in titanium is characterized by higher temperature range of dissociation and annealing with activation energy equal to 1.38 eV. However, subsequent measurements, of the angular distribution of annihilation photons (ADAP) have demonstrated

Production of titanium tetrachloride

International Nuclear Information System (INIS)

Perillo, P.M.; Botbol, O.

1990-01-01

This report presents a summary of results from theoperation of a laboratory scale for the production in batches of approximately 100 gs of titanium tetrachloride by chlorination with chloroform and carbon tetrachloride between 340 deg C and 540 deg C. Chlorination agent vapors were passed through a quartz column reacting with titanium oxide powder agglomerated in little spheres. Obtained titanium tetrachloride was condensed in a condenser, taken in a ballon and then purified by fractional distillation. Optimun temperature for chloroform was 400 deg C with 74 % yield and for carbon tetrachloride was 500 deg C with 69 % yield. (Author) [es

Studies on the promotion of nickel—alumina coprecipitated catalysts: I. Titanium oxide

NARCIS (Netherlands)

Lansink Rotgerink, H.G.J.; Mercera, P.D.L.; van Ommen, J.G.; Ross, J.R.H.

1988-01-01

A series of TiO2-promoted nickel—alumina catalysts has been prepared and characterized. The promoter was added in various proportions to a calcined coprecipitated nickel—alumina material by adsorption of the acetylacetonate complex of titanium, followed by further calcination and reduction. The

Polymer complexes.. XXXX. Supramolecular assembly on coordination models of mixed-valence-ligand poly[1-acrylamido-2-(2-pyridyl)ethane] complexes

Science.gov (United States)

El-Sonbati, A. Z.; El-Bindary, A. A.; Diab, M. A.

2003-02-01

The build-up of polymer metallic supramolecules based on homopolymer (1-acrylamido-2-(2-pyridyl)ethane (AEPH)) and ruthenium, rhodium, palladium as well as platinum complexes has been pursued with great interest. The homopolymer shows three types of coordination behaviour. In the mixed valence paramagnetic trinuclear polymer complexes [( 11)+( 12)] in the paper and in mononuclear polymer complexes ( 1)-( 5) it acts as a neutral bidentate ligand coordinating through the N-pyridine and NH-imino atoms, while in the mixed ligand diamagnetic poly-chelates, which are obtained from the reaction of AEPH with PdX 2 and KPtCl 4 in the presence of N-heterocyclic base consisting of polymer complexes ( 9)+( 10), and in monouclear compounds ( 6)-( 8), it behaves as a monobasic bidentate ligand coordinating through the same donor atoms. In mononuclear compounds ( 13)+( 14) it acts as a monobasic and neutral bidentate ligand coordinating only through the same donor atoms. Monomeric distorted octahedral or trimeric chlorine-bridged, approximately octahedral structures are proposed for these polymer complexes. The poly-chelates are of 1:1, 1:2 and 3:2 (metal-homopolymer) stoichiometry and exhibit six coordination. The values of ligand field parameters were calculated. The homopolymer and their polymer complexes have been characterized physicochemically.

Enhancement of 67Ga tumor-to-blood ratios by chelating agent

International Nuclear Information System (INIS)

Saji, Hideo; Yokoyama, Akira; Hata, Naotaka; Misaki, Atsushi; Tanaka, Hisashi.

1980-01-01

Chelating agent, such as, CaEDTA, CaDTPA, D-penicillamine, DMSA, desferoxamine, NTA, cysteine ethyl ester, BAL, α-MPG, phthalein complexone, were tested as a possible contrast enhancing agent for tumor imaging with 67 Ga-citrate. The intravenous administration of a chelating agent to Ehrlich's tumor bearing mice, one hour after the injection of 67 Ga-citrate, accelerated the blood clearance with only a very slight change of activity in the target, increasing the tumor-to-blood ratio, and consequently achieving a better visualization. Among the tested chelating agents, D-penicillamine showed the highest target-to-nontarget ratio at a shorter time: a good tumor-to-blood ratio, performed after 24 hr with non-treated animals, was achieved in only 1-3 hr with post-treated animals. Thus, D-penicillamine hold a considerable promise as a contrast enhancing agent for future clinical use. (author)

Self-diffusion coefficient of iron as affected by chelating agents using tracer technique

Energy Technology Data Exchange (ETDEWEB)

Massoud, M.A.; Abd-El-Sabour, M.F. (Agriculture Dept. for Soil and Water Research, Nuclear Research Centre, A.E.A., Cairo (Egypt)); Omar, M.A. (Ain Shams Univ., Cairo (Egypt). Faculty of Agriculture)

1983-01-01

The effect of Fe/sub 2/(So/sub 4/)/sub 3/, Fe-DTPA, and Fe-EDDHA on the self-diffusion coefficient of Fe in some soils of Egypt was studied. The effect of chelating compounds on the ratio between solid phase fraction of the labile Fe and its concentration in the soil solution (capacity factor) was also studied. The data reveals the following items of more interesting: 1) The use of chelating agents, i.e., DTPA and EDDHA increased the amount of Fe in soil solution, hence the capacity factor was decreased using these compounds. It seems that as the addition of Fe was in the chelated form in soil solution, the slight loss of 59Fe from solution when 59Fe - chelate was used could be attributed to the isotopic exchange with soil Fe. 2) It was found that the addition of either Fe-DTPA or Fe-EDDHA significantly increased the self-diffusion of Fe in soil as compared with Fe/sub 2/(So/sub 4/)/sub 3/. It was also noticed that the self-diffusion for Fe in the alluvial soil was greater than in the calcareous one due to the instance competition between Ca and Fe for the chelating ligands in the calcareous soil. It was also seen that soil texture affects Fe self-diffusion.

21 CFR 73.2575 - Titanium dioxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Titanium dioxide. 73.2575 Section 73.2575 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2575 Titanium dioxide. (a) Identity and specifications. The color additive titanium dioxide shall conform in identity and specifications to the requirements...

Comparison of DOTA and NODAGA as chelators for (64)Cu-labeled immunoconjugates.

Science.gov (United States)

Ghosh, Sukhen C; Pinkston, Kenneth L; Robinson, Holly; Harvey, Barrett R; Wilganowski, Nathaniel; Gore, Karen; Sevick-Muraca, Eva M; Azhdarinia, Ali

2015-02-01

Bifunctional chelators have been shown to impact the biodistribution of monoclonal antibody (mAb)-based imaging agents. Recently, radiolabeled 1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid (NODAGA)-peptide complexes have demonstrated improved in vivo stability and performance compared to their 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) counterparts. Here, we investigated if similar utility could be achieved with mAbs and compared (64)Cu-labeled DOTA and NODAGA-immunoconjugates for the detection of epithelial cell adhesion molecule (EpCAM) in a prostate cancer model. DOTA and NODAGA-immunoconjugates of an EpCAM targeting mAb (mAb7) were synthesized and radiolabeled with (64)Cu (DOTA: 40°C for 1hr; NODAGA: 25°C for 1hr). The average number of chelators per mAb was quantified by isotopic dilution, and the biological activity of the immunoconjugates was evaluated by flow cytometry and ELISA. Radioligand assays were performed to compare cellular uptake and determine the dissociation constant (Kd) and maximum number of binding sites (Bmax) for the immunoconjugates using DsRed-transfected PC3-cells. A PC3-DsRed xenograft tumor model was established in nude mice and used to perform biodistribution studies to compare organ uptake and pharmacokinetics. (64)Cu-DOTA-mAb7 and (64)Cu-NODAGA-mAb7 were prepared with chelator/protein ratios of 2-3 and obtained in comparable radiochemical yields ranging from 59 to 71%. Similar immunoreactivity was observed with both agents, and mock labeling studies indicated that incubation at room temperature or 40°C did not affect potency. (64)Cu-NODAGA-mAb7 demonstrated higher in vitro cellular uptake while (64)Cu-DOTA-mAb7 had higher Kd and Bmax values. From the biodistribution data, we found similar tumor uptake (13.44±1.21%ID/g and 13.24±4.86%ID/g for (64)Cu-DOTA-mAb7 and (64)Cu-NODAGA-mAb7, respectively) for both agents at 24hr, although normal prostate tissue was significantly lower for (64)Cu-NODAGA-mAb7

Development of Iron-Chelating Poly(ethylene terephthalate) Packaging for Inhibiting Lipid Oxidation in Oil-in-Water Emulsions.

Science.gov (United States)

Johnson, David R; Tian, Fang; Roman, Maxine J; Decker, Eric A; Goddard, Julie M

2015-05-27

Foods such as bulk oils, salad dressings, and nutritionally fortified beverages that are susceptible to oxidative degradation are often packaged in poly(ethylene terephthalate) (PET) bottles with metal chelators added to the food to maintain product quality. In the present work, a metal-chelating active packaging material is designed and characterized, in which poly(hydroxamic acid) (PHA) metal-chelating moieties were grafted from the surface of PET. Biomimetic PHA groups were grafted in a two-step UV-initiated process without the use of a photoinitiator. Surface characterization of the films by attenuated total reflective Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM) suggested successful grafting and conversion of poly(hydroxyethyl acrylate) (PHEA) to PHA chelating moieties from the surface of PET. Colorimetric (ferrozine) and inductively coupled plasma mass spectroscopy (ICP-MS) assays demonstrated the ability of PET-g-PHA to chelate iron in a low-pH (3.0) environment containing a competitive metal chelator (citric acid). Lipid oxidation studies demonstrated the antioxidant activity of PET-g-PHA films in inhibiting iron-promoted oxidation in an acidified oil-in-water (O/W) emulsion model system (pH 3.0). Particle size and ζ-potential analysis indicated that the addition of PET-g-PHA films did not affect the physical stability of the emulsion system. This work suggests that biomimetic chelating moieties can be grafted from PET and effectively inhibit iron-promoted degradation reactions, enabling removal of metal-chelating additives from product formulations.

Antibacterial Behavior of Additively Manufactured Porous Titanium with Nanotubular Surfaces Releasing Silver Ions

NARCIS (Netherlands)

Amin Yavari, S.; Loozen, L.; Paganelli, F. L.; Bakhshandeh, S.; Lietaert, K.; Groot, J. A.; Fluit, A. C.; Boel, C. H E; Alblas, J.; Vogely, H. C.; Weinans, H.; Zadpoor, A. A.

2016-01-01

Additive manufacturing (3D printing) has enabled fabrication of geometrically complex and fully interconnected porous biomaterials with huge surface areas that could be used for biofunctionalization to achieve multifunctional biomaterials. Covering the huge surface area of such porous titanium with

Chelators for investigating zinc metalloneurochemistry

OpenAIRE

Radford, Robert John; Lippard, Stephen J.

2013-01-01

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

Titanium oxide nanocoating on a titanium thin film deposited on a glass substrate

Energy Technology Data Exchange (ETDEWEB)

Kotsedi, L., E-mail: kotsedi@tlabs.ac.za [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS, National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape (South Africa); Nuru, Z.Y. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS, National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape (South Africa); Eaton, S.M. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Cummings, F.R. [University of the Western Cape, Electron Microscopy Unit, Physics Department, Bellville 7535, Cape Town (South Africa); Turco, S. Lo; Ntwaeaborwa, O.M. [Center for Nano Science and Technology, Istituto Italiano di Tecnologia, Milano, Italy Via Giovanni Pascoli, 70/3, 20133 Milano (Italy); Ramponi, R. [Institute for Photonics and Nanotechnologies (IFN)-CNR, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Maaza, M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS, National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape (South Africa)

2016-03-31

Thin films of titanium were deposited on a glass substrate using electron beam evaporator. Femtosecond laser pulses were focused on the surface of the films, and the samples were scanned while mounted on the motorized computer-controlled motion stage to produce an areal modification of the films. X-ray diffraction of the laser-patterned samples showed evidence of the formation of a γ-Ti{sub 3}O{sub 5} with a monoclinic phase. Rutherford backscattering spectrometry simulation showed that there is an increase in the oxygen concentration as the average laser fluence is increased. Time of flight secondary ions mass spectrometry analysis showed an even distribution of the titanium and oxygen ions on the sample and also ionized molecules of the oxides of titanium were observed. The formation of the oxide of titanium was further supported using the UV–Vis-NIR spectroscopy, which showed that for 0.1 J/cm{sup 2} fluence, the laser-exposed film showed the electron transfer band and the d–d transition peak of titanium was observed at lower wavelengths. - Highlights: • γ-Ti{sub 3}O{sub 5} formed using femtosecond laser. • Fluence and oxygen relation were studied. • Nanoflakes of γ-Ti{sub 3}O{sub 5} were observed under HRSEM.