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Sample records for chelating coordinated oxo-anions

  1. 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

    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 com...

  2. 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.

  3. On flotation separation of oxo-anions of transition metals by the use of fine-emulsified solutions of cationic collector in non-polar liquids

    International Nuclear Information System (INIS)

    Experimentally shown is a principle possibility of flotation separation of oxo-anions of transition metals by the use of fine-emulsified solutions of cationic collector in non-polar liquids. Ammonium vanadate and sodium tuno.state solutions have been the objects of study. Hexadezilamine has been used as collector. The collector has been introduced in the form of hexadecylamine emulsions in n-decane, in tetrachloromethane or alcohol. Optimum pH value ranges are determined for separation processes

  4. Extraction of Tetra-oxo Anions into a Hydrophobic, Ionic Liquid-Based Solvent Without Concomitant Ion Exchange

    International Nuclear Information System (INIS)

    Hydrophobic ionic liquids (IL) have the potential to simplify certain separations by serving as both an extraction solvent and an electrolyte for subsequent electrochemical reductions. While IL-based solvents are known to be efficient media for metal ion extraction, separations employing these solvents are frequently complicated by the loss of constituent IL ions to the aqueous phase, resulting in deteriorating performance. In this study, we have examined the extraction of pertechnetate and related tetra-oxo anions from aqueous solutions into IL-based solvents incorporating tetraalkylphosphonium bis((trifluoromethyl)sulfonyl)imide and a crown ether. In contrast to various previously studied IL-based cation extraction systems, facile anion extraction without significant transfer of the IL ions to the aqueous phase has been observed. In addition, the solvents exhibit high distribution ratios (100-500 for pertechnetate), significant electrical conductivity (>100 (micro)S/cm), and a wide (∼4 V) electrochemical window. The results suggest that these solvents may provide the basis for improved approaches to the extraction and recovery of a variety of anions.

  5. 'Unconventional' coordination chemistry by metal chelating fragments in a metalloprotein active site.

    Science.gov (United States)

    Martin, David P; Blachly, Patrick G; Marts, Amy R; Woodruff, Tessa M; de Oliveira, César A F; McCammon, J Andrew; Tierney, David L; Cohen, Seth M

    2014-04-01

    The binding of three closely related chelators: 5-hydroxy-2-methyl-4H-pyran-4-thione (allothiomaltol, ATM), 3-hydroxy-2-methyl-4H-pyran-4-thione (thiomaltol, TM), and 3-hydroxy-4H-pyran-4-thione (thiopyromeconic acid, TPMA) to the active site of human carbonic anhydrase II (hCAII) has been investigated. Two of these ligands display a monodentate mode of coordination to the active site Zn(2+) ion in hCAII that is not recapitulated in model complexes of the enzyme active site. This unprecedented binding mode in the hCAII-thiomaltol complex has been characterized by both X-ray crystallography and X-ray spectroscopy. In addition, the steric restrictions of the active site force the ligands into a 'flattened' mode of coordination compared with inorganic model complexes. This change in geometry has been shown by density functional computations to significantly decrease the strength of the metal-ligand binding. Collectively, these data demonstrate that the mode of binding by small metal-binding groups can be significantly influenced by the protein active site. Diminishing the strength of the metal-ligand bond results in unconventional modes of metal coordination not found in typical coordination compounds or even carefully engineered active site models, and understanding these effects is critical to the rational design of inhibitors that target clinically relevant metalloproteins. PMID:24635441

  6. Coordination properties of a metal chelator clioquinol to Zn(2+) studied by static DFT and ab initio molecular dynamics.

    Science.gov (United States)

    Rodríguez-Santiago, Luis; Alí-Torres, Jorge; Vidossich, Pietro; Sodupe, Mariona

    2015-05-28

    Several lines of evidence supporting the role of metal ions in amyloid aggregation, one of the hallmarks of Alzheimer's disease (AD), have turned metal ion chelation into a promising therapeutic treatment. The design of efficient chelating ligands requires proper knowledge of the electronic and molecular structure of the complexes formed, including their hydration properties. Among various potential chelators, clioquinol (5-chloro-7-iodo-8-hydroxyquinoline, CQH) has been evaluated with relative success in in vitro experiments and even in phase 2 clinical trials. Clioquinol interacts with Zn(ii) to lead to a binary metal/ligand 1 : 2 stoichiometric complex in which the phenolic group of CQH is deprotonated, resulting in Zn(CQ)2 neutral complexes, to which additional water molecules may coordinate. In the present work, the coordinative properties of clioquinol in aqueous solution have been analyzed by means of static, minimal cluster based DFT calculations and explicit solvent ab initio molecular dynamics simulations. Results from static calculations accounting for solvent effects by means of polarized continuum models suggest that the preferred metal coordination environment is tetrahedral Zn(CQ)2, whereas ab initio molecular dynamics simulations point to quasi degenerate penta Zn(CQ)2(H2O) and hexa Zn(CQ)2(H2O)2 coordinated complexes. The possible reasons for these discrepant results are discussed. PMID:25939963

  7. Strongly Emissive and Photostable Four-Coordinate Organoboron N,C Chelates and Their Use in Fluorescence Microscopy.

    Science.gov (United States)

    Pais, Vânia F; Alcaide, María M; López-Rodríguez, Rocío; Collado, Daniel; Nájera, Francisco; Pérez-Inestrosa, Ezequiel; Álvarez, Eleuterio; Lassaletta, José M; Fernández, Rosario; Ros, Abel; Pischel, Uwe

    2015-10-19

    Six strongly fluorescent four-coordinate organoboron N,C chelates containing an aryl isoquinoline skeleton were prepared. Remarkably, the fluorescence quantum yields reach values of up to 0.74 in oxygen-free toluene. The strong B-N interaction was corroborated by the single-crystal X-ray analysis of two dyes. The intramolecular charge-transfer character of the fluorophores was evidenced by solvatochromism studies and time-dependent DFT calculations at the PCM(toluene)/CAM-B3LYP/6-311++G(2d,p)//PCM(toluene)/B3LYP/6-311G(2d,p) level of theory. The compounds combine high chemical stability with high photostability, especially when equipped with electron-donating substituents. The strong fluorescence and the large Stokes shifts predestine these compounds for use in confocal fluorescence microscopy. This was demonstrated for the imaging of the N13 mouse microglial cell line. Moreover, significant two-photon absorption cross sections (up to 61 GM) allow the use of excitation wavelengths in the near-infrared region (>800 nm). PMID:26332824

  8. Diamidophosphines with six-membered chelates and their coordination chemistry with group 4 metals: development of a trimethylene-methane-tethered [PN2]-type "molecular claw".

    Science.gov (United States)

    Batke, S; Kothe, T; Haas, M; Wadepohl, H; Ballmann, J

    2016-02-28

    The coordination chemistry of the phosphine-tethered diamidophosphine ligands PhP(CH2CH2CH2NHPh)2 (pr[NPN]H2) and PhP(1,2-CH2-C6H4-NHSiMe3)2 (bn[NPN]H2) featuring six-membered N–C3–P chelates was explored with group 4 metals, which allowed for the consecutive development of a new trimethylene-methane-tethered [PN2] scaffold. In the case of the propylene-linked system pr[NPN]H2, access to the sparingly soluble dibenzyl derivative pr[NPN]ZrBn2 (3-Zr) was gained, while thermally sensitive zirconium and hafnium diiodo complexes bn[NPN]MI2 (5-M, M = Zr, Hf) were isolated in the case of the benzylene-linked derivative bn[NPN]H2. Despite the related phosphine-tethered backbone architectures of both of these ligands, their group 4 complexes were found to exhibit either C1-symmetric (bn[NPN]MX2) or averaged CS-symmetric (pr[NPN]MX2) structures in solution. To restrain the overall flexibility of these systems and thereby control the properties of the resulting complexes without disrupting the six-membered chelates, the new trimethylene-methane-tethered N,N′-di-(tert-butyl)-substituted [PN2]H2 protioligand was designed. This tripodal ligand system was prepared on a gram scale and its CS-symmetric dichloro complexes [PN2]MCl2 (6-M, M = Ti, Zr, Hf) were isolated subsequently. The benzene-soluble dibenzyl derivative [PN2]ZrBn2 (7-Zr) was synthesised as well and characterised by X-ray diffraction. These results are discussed not only in conjunction with the known [NPN]-coordinated group 4 complexes incorporating five-membered chelates, but also in the context of “molecular claws” that are related to the new [PN2] tripod. PMID:26804587

  9. Structural and spectroscopic study of reactions between chelating zinc-binding groups and mimics of the matrix metalloproteinase and disintegrin metalloprotease catalytic sites: the coordination chemistry of metalloprotease inhibition.

    Science.gov (United States)

    He, Hongshan; Puerta, David T; Cohen, Seth M; Rodgers, Kenton R

    2005-10-17

    To understand the coordination chemistry of zinc-binding groups (ZBGs) with catalytic zinc centers in matrix metalloproteinases (MMPs) and disintegrin metalloproteases (ADAMs), we have undertaken a model compound study centered around tris(3,5-methylphenypyrazolyl)hydroboratozinc(II) hydroxide and aqua complexes ([Tp(Ph,Me)ZnOH] and [Tp(Ph,Me)Zn(OH2)]+, respectively, wherein (Tp(Ph,Me))- = hydrotris(3,5-methylphenylpyrazolyl)borate) and the products of their reactions with a class of chelating Schiff's base ligands. The results show that the protic ligands, HL (HL = N-propyl-1-(5-methyl-2-imidazolyl)methanimine (5-Me-4-ImHPr), N-propyl-1-(4-imidazolyl)methanimine (4-ImHPr), and N-propyl-1-(2-imidazolyl)methanimine (2-ImHPr)), react with [Tp(Ph,Me)ZnOH] and give products with the general formula [Tp(Ph,Me)ZnL], whereas reactions with neutral aprotic ligands, L' (L' = N-propyl-1-(1-methyl-2-imidazolyl)methanimine (1-Me-2-ImPr) and N-propyl-1-(2-thiazolyl)methanimine (2-TaPr)), yield the corresponding [Tp(Ph,Me)ZnL]+ complexes. Although the phenol group of N-propyl-1-(2-hydroxyphenyl)methanimine (2-HOPhPr) is protic, this ligand forms a cationic four-coordinate complex containing an intraligand hydrogen bond. The solid-state structures of these complexes were determined by single-crystal X-ray diffraction, and the results showed that the protic ligands form five-membered chelates of the Zn2+ ion. All ligands displace the aqua ligand in [Tp(Ph,Me)Zn(OH2)]+ to yield complexes having 1H NMR spectra consistent with the formation of five membered chelates. The 1H resonance frequencies of the chelating ligands typically shift upfield upon coordination to the zinc center, due to ring current effects from the pendant phenyl groups of the (Tp(Ph,Me))- ligand. Thus, the 1H NMR spectra provide a convenient and sensitive means of tracking the solution reactions by titration. The resulting series of spectra showed that the stabilities of the chelates in solution depend on the

  10. Towards the Rational Design of MRI Contrast Agents: δ-Substitution of Lanthanide(III) NB-DOTA-Tetraamide Chelates Influences but Does Not Control Coordination Geometry**

    OpenAIRE

    Carney, Christiane E.; Tran, Anh D.; Jing WANG; Schabel, Matthias C.; Sherry, A. Dean; Woods, Mark

    2011-01-01

    LnDOTA-tetraamide chelates (DOTA=1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) have received considerable recent attention as a result of their potential to act as PARACEST contrast agents for magnetic resonance imaging (MRI). Although PARACEST agents afford several advantages over conventional contrast agents they suffer from substantially higher detection limits; thus, improving the effectiveness of LnDOTA-tetraamide chelates is an important goal. In this study we investigate th...

  11. Chelated minerals for poultry

    Directory of Open Access Journals (Sweden)

    SL Vieira

    2008-06-01

    Full Text Available Organic minerals have been subject of an increasing number of investigations recently. These compounds can be considered the most significant event regarding commercial forms of minerals targeting animal supplementation in the last decades. Minerals, especially metals, are usually supplemented in poultry feeds using cheap saline sources and have never required a lot of attention in terms of quality. On the other hand, definitions of organic minerals are very broad and frequently lead to confusion when decision-making becomes necessary. Organic minerals include any mineral bound to organic compounds, regardless of the type of existing bond between mineral and organic molecules. Proteins and carbohydrates are the most frequent candidates in organic mineral combinations. Organic fraction size and bond type are not limitations in organic mineral definition; however, essential metals (Cu, Fe, Zn, and Mn can form coordinated bonds, which are stable in intestinal lumen. Metals bound to organic ligands by coordinated bonds can dissociate within animal metabolism whereas real covalent bonds cannot. Chelated minerals are molecules that have a metal bound to an organic ligand through coordinated bonds; but many organic minerals are not chelates or are not even bound through coordinated bonds. Utilization of organic minerals is largely dependent on the ligand; therefore, amino acids and other small molecules with facilitated access to the enterocyte are supposed to be better utilized by animals. Organic minerals with ligands presenting long chains may require digestion prior to absorption. After absorption, organic minerals may present physiological effects, which improve specific metabolic responses, such as the immune response. Many studies have demonstrated the benefits of metal-amino acid chelates on animal metabolism, but the detection positive effects on live performance is less consistent.

  12. Light-Induced Copper(II) Coordination by a Bicyclic Tetraaza Chelator through a Ligand-to-Metal Charge-Transfer Reaction

    DEFF Research Database (Denmark)

    Holm-Jørgensen, Jacob Rørdam; Jensen, Mikael; Bjerrum, Morten J.

    2011-01-01

    To enable utilization of the broad potential of copper isotopes in nuclear medicine, rapid and robust chelation of the copper is required. Bowl adamanzanes (bicyclic tetraaza ligands) can form kinetically stable copper complexes, but they are usually formed at low rates unless high pH values and...

  13. Solution and cross-polarization/magic angle spinning NMR investigation of intramolecular coordination Sn-N in some organotin(IV) C,N-chelates

    Czech Academy of Sciences Publication Activity Database

    Růžička, A.; Jambor, R.; Brus, Jiří; Císařová, I.; Holeček, J.

    2001-01-01

    Roč. 323, 1-2 (2001), s. 163-170. ISSN 0020-1693 R&D Projects: GA ČR GA203/00/0920 Institutional research plan: CEZ:AV0Z4050913 Keywords : C,N-chelates * NMR spectroscopy * intramolecular interaction Subject RIV: CA - Inorganic Chemistry Impact factor: 1.394, year: 2001

  14. Metal ions, Alzheimer's disease and chelation therapy.

    Science.gov (United States)

    Budimir, Ana

    2011-03-01

    In the last few years, various studies have been providing evidence that metal ions are critically involved in the pathogenesis of major neurological diseases (Alzheimer, Parkinson). Metal ion chelators have been suggested as potential therapies for diseases involving metal ion imbalance. Neurodegeneration is an excellent target for exploiting the metal chelator approach to therapeutics. In contrast to the direct chelation approach in metal ion overload disorders, in neurodegeneration the goal seems to be a better and subtle modulation of metal ion homeostasis, aimed at restoring ionic balance. Thus, moderate chelators able to coordinate deleterious metals without disturbing metal homeostasis are needed. To date, several chelating agents have been investigated for their potential to treat neurodegeneration, and a series of 8-hydroxyquinoline analogues showed the greatest potential for the treatment of neurodegenerative diseases. PMID:21406339

  15. Chelation in Metal Intoxication

    OpenAIRE

    Flora, Swaran J.S.; Vidhu Pachauri

    2010-01-01

    Chelation therapy is the preferred medical treatment for reducing the toxic effects of metals. Chelating agents are capable of binding to toxic metal ions to form complex structures which are easily excreted from the body removing them from intracellular or extracellular spaces. 2,3-Dimercaprol has long been the mainstay of chelation therapy for lead or arsenic poisoning, however its serious side effects have led researchers to develop less toxic analogues. Hydrophilic chelators like meso-2,3...

  16. Macrocyclic bifunctional chelating agents

    Science.gov (United States)

    Meares, Claude F.; DeNardo, Sally J.; Cole, William C.; Mol, Min K.

    1987-01-01

    A copper chelate conjugate which is stable in human serum. The conjugate includes the copper chelate of a cyclic tetraaza di-, tri-, or tetra-acetic acid, a linker attached at one linker end to a ring carbon of the chelate, and a biomolecule joined at the other end of the linker. The conjugate, or the linker-copper chelate compound used in forming the conjugate, are designed for use in diagnostic and therapeutic applications which involve Cu(II) localization via the systemic route.

  17. Lanthanon chelates of monoprotic tridentate schiff base

    International Nuclear Information System (INIS)

    3-(N-thiophene-2-aldimino)propanoic acid (HTP), and its lanthanon chelates were synthesised and studied by physico-chemical techniques. Irving-Rossotti method was followed to determine the dissociation constants of the ligand and formation constants of its lanthanon chelates in aqueous medium (ionic strength μ = 0.01, 0.05 and 0.1 M NaClO4) at 25 0C, 35 0C and 45 0C. Solid lanthanon chelates were characterised by molecular mass, elemental analyses, conductance, magnetic, thermal and spectral analyses and were assigned 1 : 3 (metal-ligand) stoichiometry in which the lanthanon shows nine coordination numbers. Covalent nature of metal-ligand bond was found to increase with increase in atomic number of central lanthanide ion. (author)

  18. 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...... 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...

  19. Ferrocene base metal chelates

    International Nuclear Information System (INIS)

    Review of the works, devoted to different types of ferrocene metal chelates and to a possibility of ferrocene-containing ligand modification by means of complexing, is presented. Structure, properties and spectral characteristics of transitional metal, rare earth element, Cd2+, UO22+, Th4+ etc. complexes with ferrocene diketones, ferrocene acyl derivatives based on thiosemicarbazones and hydrazones and other heterometal ferrocene-containing metal chelates, are considered. 134 refs., 1 tab

  20. 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.

  1. Comments on chelation therapy

    International Nuclear Information System (INIS)

    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 239Pu, 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 241Am from the canine, the sub-human primate, and the human liver, improved methods for removal from bone and lung are needed. DTPA can remove 241Am 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

  2. Chelation: Harnessing and Enhancing Heavy Metal Detoxification—A Review

    OpenAIRE

    Sears, Margaret E.

    2013-01-01

    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...

  3. 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...

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

    Science.gov (United States)

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

    2013-10-01

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

  5. Alkenes as Chelating Groups in Diastereoselective Additions of Organometallics to Ketones

    OpenAIRE

    Raffier, Ludovic; Gutierrez, Osvaldo; Stanton, Gretchen R.; Kozlowski, Marisa C.; Walsh, Patrick J.

    2014-01-01

    Alkenes have been discovered to be chelating groups to Zn(II), enforcing highly stereoselective additions of organozincs to β,γ-unsaturated ketones. 1H NMR studies and DFT calculations provide support for this surprising chelation mode. The results expand the range of coordinating groups for chelation-controlled carbonyl additions from heteroatom Lewis bases to simple C–C double bonds, broadening the 60 year old paradigm.

  6. Coordination chemistry of silver(I) with the nitrogen-bridged ligands (C(6)H(5))(2)PN(H)P(C(6)H(5))(2) and (C(6)H(5))(2)PN(CH(3))P(C(6)H(5))(2): the effect of alkylating the nitrogen bridge on ligand bridging versus chelating behavior.

    Science.gov (United States)

    Sekabunga, E J; Smith, Michele L; Webb, T R; Hill, W E

    2002-03-11

    The coordination chemistry of silver(I) with the nitrogen-bridged ligands (C(6)H(5))(2)PN(R)P(C(6)H(5))(2) [R = H (dppa); R = CH(3) (dppma)] has been investigated by (31)P NMR and electrospray mass spectrometry (ESMS). Species observed by (31)P NMR include Ag(2)(mu-dppa)(2+), Ag(2)(mu-dppa)(2)(2+), Ag(2)(mu-dppa)(3)(2+), Ag(2)(mu-dppma)(2+), Ag(2)(mu-dppma)(2)(2+), and Ag(eta(2)-dppma)(2)(+). Species observed by ESMS at low cone voltages were Ag(2)(dppa)(2)(2+), Ag(2)(dppa)(3)(2+), Ag(2)(dppma)(2)(2+), and Ag(dppma)(2)(+). (C(6)H(5))(2)PN(CH(3))P(C(6)H(5))(2) showed a strong tendency to chelate, while (C(6)H(5))(2)PN(H)P(C(6)H(5))(2) preferred to bridge. Differences in the bridging versus chelating behavior of the ligands are assigned to the Thorpe-Ingold effect, where the methyl group on nitrogen sterically interacts with the phenyl groups on phosphorus. The crystal structure of the three-coordinate dinuclear silver(I) complex (Ag(2)[(C(6)H(5))(2)PN(H)P(C(6)H(5))(2)](3))(BF(4))(2) has been determined. Bond distances include Ag-Ag = 2.812(1) A, Ag(1)-P(av) = 2.492(3) A, and Ag(2)-P(av) = 2.509(3) A. The compound crystallizes in the monoclinic space group Cc at 294 K, with a = 18.102(4)(o), Z = 4, V = 7261(3) A(3), R = 0.0503, and R(W) = 0.0670. PMID:11874357

  7. Crystal structure of an eight-coordinate terbium(III ion chelated by N,N′-bis(2-hydroxybenzyl-N,N′-bis(pyridin-2-ylmethylethylenediamine (bbpen2− and nitrate

    Directory of Open Access Journals (Sweden)

    Thaiane Gregório

    2015-01-01

    Full Text Available The reaction of terbium(III nitrate pentahydrate in acetonitrile with N,N′-bis(2-hydroxybenzyl-N,N′-bis(pyridin-2-ylmethylethylenediamine (H2bbpen, previously deprotonated with triethylamine, produced the mononuclear compound [N,N′-bis(2-oxidobenzyl-κO-N,N′-bis(pyridin-2-ylmethyl-κNethylenediamine-κ2N,N′](nitrato-κ2O,O′terbium(III, [Tb(C28H28N4O2(NO3]. The molecule lies on a twofold rotation axis and the TbIII ion is eight-coordinate with a slightly distorted dodecahedral coordination geometry. In the symmetry-unique part of the molecule, the pyridine and benzene rings are both essentially planar and form a dihedral angle of 61.42 (7°. In the molecular structure, the N4O4 coordination environment is defined by the hexadentate bbpen ligand and the bidentate nitrate anion. In the crystal, a weak C—H...O hydrogen bond links molecules into a two-dimensional network parallel to (001.

  8. Crystal structure of an eight-coordinate terbium(III) ion chelated by N,N'-bis-(2-hy-droxy-benz-yl)-N,N'-bis-(pyridin-2-ylmeth-yl)ethyl-enedi-amine (bbpen(2-)) and nitrate.

    Science.gov (United States)

    Gregório, Thaiane; Rüdiger, André Luis; Nunes, Giovana G; Soares, Jaísa F; Hughes, David L

    2015-01-01

    The reaction of terbium(III) nitrate penta-hydrate in aceto-nitrile with N,N'-bis-(2-hy-droxy-benz-yl)-N,N'-bis-(pyridin-2-ylmeth-yl)ethyl-enedi-amine (H2bbpen), previously deprotonated with tri-ethyl-amine, produced the mononuclear compound [N,N'-bis-(2-oxidobenzyl-κO)-N,N'-bis-(pyridin-2-ylmethyl-κN)ethylenedi-amine-κ(2) N,N'](nitrato-κ(2) O,O')terbium(III), [Tb(C28H28N4O2)(NO3)]. The mol-ecule lies on a twofold rotation axis and the Tb(III) ion is eight-coordinate with a slightly distorted dodeca-hedral coordination geometry. In the symmetry-unique part of the mol-ecule, the pyridine and benzene rings are both essentially planar and form a dihedral angle of 61.42 (7)°. In the mol-ecular structure, the N4O4 coordination environment is defined by the hexa-dentate bbpen ligand and the bidentate nitrate anion. In the crystal, a weak C-H⋯O hydrogen bond links mol-ecules into a two-dimensional network parallel to (001). PMID:25705453

  9. Some aspects of chelation chemistry

    International Nuclear Information System (INIS)

    The notions used in chelation chemistry are defined and the possibilities of the experimental recognition of complex formation are described. A review of the quantitative aspects of chelation is given, especially under biological conditions. Some rules concerning the general behaviour of the various metal ions and the organic ligands in chelation phenomena are presented and the specificity problem is discussed. The present status of the decontamination of the main fission products, e.g. rare-earth metals and strontium, with the aid of complexing agents is analysed from a chemical point of view. (author)

  10. The Scientific Basis for Chelation: Animal Studies and Lead Chelation

    OpenAIRE

    Smith, Donald; Strupp, Barbara J.

    2013-01-01

    This presentation summarizes several of the rodent and non-human studies that we have conducted to help inform the efficacy and clinical utility of succimer (meso-2,3-dimercaptosuccincinic acid) chelation treatment. We address the following questions: (1) What is the extent of body lead, and in particular brain lead reduction with chelation, and do reductions in blood lead accurately reflect reductions in brain lead? (2) Can succimer treatment alleviate the neurobehavioral impacts of lead poi...

  11. Crystal structure of an eight-coordinate terbium(III) ion chelated by N,N′-bis(2-hydroxybenzyl)-N,N′-bis(pyridin-2-ylmethyl)ethylenediamine (bbpen2−) and nitrate

    OpenAIRE

    Thaiane Gregório; André Luis Rüdiger; Nunes, Giovana G.; Soares, Jaísa F.; Hughes, David L.

    2015-01-01

    The reaction of terbium(III) nitrate pentahydrate in acetonitrile with N,N′-bis(2-hydroxybenzyl)-N,N′-bis(pyridin-2-ylmethyl)ethylenediamine (H2bbpen), previously deprotonated with triethylamine, produced the mononuclear compound [N,N′-bis(2-oxidobenzyl-κO)-N,N′-bis(pyridin-2-ylmethyl-κN)ethylenediamine-κ2N,N′](nitrato-κ2O,O′)terbium(III), [Tb(C28H28N4O2)(NO3)]. The molecule lies on a twofold rotation axis and the TbIII ion is eight-coordinate with a slightly distorted dodecahedral coordinati...

  12. Overview of current chelation practices

    OpenAIRE

    Aydinok, Y.

    2011-01-01

    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 ...

  13. Bifunctional Chelates for Metal Nuclides

    OpenAIRE

    Brechbiel, Martin W.

    2007-01-01

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

  14. Alarming use of chelation therapy

    OpenAIRE

    Crisponi, Guido; Nurchi, Valeria Marina; Lachowicz, Joanna I.; Crespo-Alonso, Miriam; Zoroddu, Maria Antonietta; Peana, Massimiliano Francesco

    2014-01-01

    Chelation therapy is a consolidated medical procedure used primarily to hinder the effects of toxic metal ions on human tissues. Its application spans a broad spectrum of disorders, ranging from acute metal intoxication to genetic metal-overload. The use of chelating agents is compromised by a number of serious side effects, mainly attributable to perturbed equilibrium of essential metal ion homeostasis and dislocation of complexed metal ions to dangerous body sites. For this reason, chelatio...

  15. New chelation strategies for the uranyl ion

    International Nuclear Information System (INIS)

    Traditional approaches to the design of metal-ion-specific complexing agents have relied to a great extent on the creation of a ligand cavity of the appropriate size and coordination number to accommodate the targeted metal ion. Oxo-metal ions, such as uranyl, cannot be dealt with as spherically symmetric charged atoms and thus present both a special challenge and offer a unique advantage for specific chelation in solution. To maximize recognition of the anisotropic UO22+ ion, new tripodal hexadentate ligands have been prepared providing three carboxyl moieties each to act as a bidentate donor group. The novel ligand design concept, ligand syntheses, and thermodynamic results related to the uranyl complex characterization are presented

  16. Studies on the chelation of aluminium for biological application

    International Nuclear Information System (INIS)

    Potentiometric determinations of the strength of chelation of aluminium(III) by citrate and 3-carboxy-1,5-pentanedioic acid have been made at 37,0 plus minus 0,1 degree Celsius and I = 150 mmol dm-3 NaCl. From these results, the citrate complex is inferred to be tridentate with coordination through the two terminal carboxyl groups and the central hydroxyl group. This structure is confirmed by 13C nuclear magnetic resonance

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

    OpenAIRE

    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-tet...

  18. Targeted Cleavage of HIV RRE RNA by Rev-Coupled Transition Metal Chelates

    OpenAIRE

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

    2011-01-01

    A series of compounds that target reactive metal-chelates to the HIV-1 Rev Response Element (RRE) mRNA have been synthesized. Dissociation constants and chemical reactivity toward HIV RRE RNA have been determined and evaluated in terms of reduction potential, coordination unsaturation, and overall charge associated with the metal-chelate-rev complex. Ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), and 1,4,7,10-tetraazacyclo-dodec...

  19. 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

  20. Iron chelation and multiple sclerosis

    Directory of Open Access Journals (Sweden)

    Kelsey J. Weigel

    2014-01-01

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

  1. Luminescent lanthanide chelates and methods of use

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-01-01

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

  2. Complexes of quinone-functionalized chelating ligands for multiple electron/proton transfer reduction reactions

    Energy Technology Data Exchange (ETDEWEB)

    Durfee, W.S.; Pierpont, C.G. (Univ. of Colorado, Boulder (United States))

    1993-03-03

    Quinone-functionalized chelating ligands may be used to effect sequential electron/proton transfer steps necessary for the reduction of substrate molecules coordinated to a complexed metal ion. The chelating ligand (NQ)[sub 2]en has been synthesized by condensing 2 equiv of 2-hydroxy-3-acetyl-1,4-naphthoquinone with ethylenediamine. Complexes of Cu(II) and Ni(II) have been prepared and characterized. Electrochemical properties of the complexes show that, in the fully reduced bis(hydroquinone) form, the ligand would be able to provide four electrons and protons to a coordinated substrate molecule at strongly negative potentials. 8 refs., 2 figs.

  3. Iron chelation and multiple sclerosis

    OpenAIRE

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

    2014-01-01

    Histochemical and MRI studies have demonstrated that MS (multiple sclerosis) patients have abnormal deposition of iron in both gray and white matter structures. Data is emerging indicating that this iron could partake in pathogenesis by various mechanisms, e.g., promoting the production of reactive oxygen species and enhancing the production of proinflammatory cytokines. Iron chelation therapy could be a viable strategy to block iron-related pathological events or it can confer cellular prote...

  4. Some Linguistic Detail on Chelation

    Science.gov (United States)

    Haworth, Daniel T.

    1998-01-01

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

  5. Lanthanides caged by the organic chelates; structural properties

    Science.gov (United States)

    Smentek, Lidia

    2011-04-01

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

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

    International Nuclear Information System (INIS)

    Two kinds of europium-β-diketone chelates, binary Eu(DBM)3 and ternary Eu(DBM)3phen were doped in poly(methyl methacrylate) (PMMA). These chelates show very different photoluminescent (PL) behaviors: the hypersensitive 5D0→7F2 emission bands of Eu(DBM)3phen 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 5D0 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 Eu3+ 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

  7. Status of chelation research: a review

    International Nuclear Information System (INIS)

    The current status of research on the removal of actinide elements from the body is reviewed. Items occurring prior to 1980 include evidence for fetal toxicity from Ca-DTPA, the FDA approval of Zn-DTPA for human therapy, the mixed ligand fiasco, and the abrupt wipeout of chelation funding. New concepts that should be explored include improvements in removing radioactivity from lung and bone, the effectiveness of DTPA inside cells, simultaneous therapy with mobilizing agents and chelating agents, prolonging the retention of chelating agents within the body, the oral administration of chelating agents, the effectiveness of LICAM and other new chelating agents, the safety of decorporation procedures, and the effectiveness of chelation therapy on reducing the risk from radionuclide-induced cancer. Some physicians give DTPA by intravenous injection, a safe procedure that should be officially sanctioned

  8. Iron Chelation Therapy in Myelodysplastic Syndromes

    OpenAIRE

    Giuseppe Saglio; Daniela Cilloni; Emanuela Messa

    2010-01-01

    Myelodysplastic syndromes (MDS) are a heterogeneous disorder of the hematopoietic stem cells, frequently characterized by anemia and transfusion dependency. In low-risk patients, transfusion dependency can be long lasting, leading to iron overload. Iron chelation therapy may be a therapeutic option for these patients, especially since the approval of oral iron chelators, which are easier to use and better accepted by the patients. The usefulness of iron chelation in MDS patients is still unde...

  9. Beliefs about chelation among thalassemia patients

    OpenAIRE

    Trachtenberg Felicia L; Mednick Lauren; Kwiatkowski Janet L; Neufeld Ellis J; Haines Dru; Pakbaz Zahra; Thompson Alexis A; Quinn Charles T; Grady Robert; Sobota Amy; Olivieri Nancy; Horne Robert; Yamashita Robert

    2012-01-01

    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 patie...

  10. Role of chelates in treatment of cancer

    Directory of Open Access Journals (Sweden)

    Tripathi Laxmi

    2007-01-01

    Full Text Available Chelates are used in cancer as cytotoxic agent, as radioactive agent in imaging studies and in radioimmunotherapy. Various chelates based on ruthenium, copper, zinc, organocobalt, gold, platinum, palladium, cobalt, nickel and iron are reported as cytotoxic agent. Monoclonal antibodies labeled with radioactive metals such as yttrium-90, indium-111 and iodine-131 are used in radioimmunotherapy. This review is an attempt to compile the use of chelates as cytotoxic drugs and in radioimmunotherapy.

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

    International Nuclear Information System (INIS)

    The environmental chemistry of the three most common aminopolycarboxylic acid chelating agents, NTA (nitrilotriacetic acid), EDTA (ethylenediaminetetraacetic acid), and DTPA (diethylenetriaminepentaacetic acid) is reviewed. This review includes information on their persistence in the environment, as well as their tendency to form complexes with actinides. Data on the sorption of chelated actinides by geologic substrates and on the uptake of chelated actinides by plants are also presented. Three different technical options for disposing chelated low-level radioactive wastes are proposed: bind the solidified chelated waste in some kind of solid matrix that has a slow leach rate and bury the waste in a ''dry'' disposal site; substitute biodegradable chelating agents in the decontamination reagent for the chelating agents that are persistent in the environment; chemically or thermally degrade the chelating agents in the waste prior to disposal. The relative advantages and disadvantages of each of these options are discussed. 81 refs

  12. Chelation behaviour of lanthanons with o-arsonodibenzoylmethanephenlylhydrazone

    International Nuclear Information System (INIS)

    The chelate formation reaction of La(III), Pr(III), Nd(III), Gd(III), Ho(III), and Er(III) with o-arsonodibenzoylmethanephenylhydrazone has been investigated potentiometrically and conductometrically in 40 % (ν/ν) aqueous ethanol, ionic strength 0,1 M. The order of stability constants was found to be La Gd 3+: L). The complexes have been isolated in solid state and have been characterized on the basis of elemental analysis and IR data. Coordination occurs through - NH of the hydrazo and - OH of the arsonic groups. (Authors)

  13. 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.

  14. Synthesis and characterization of some new lanthanide(III) chelates with 1,4-bis-(2'-hydroxyphenylazomethine) phenylene

    International Nuclear Information System (INIS)

    The chelates formed between 1,4-bis(2'-hydroxyphenylazomethine) phenylene with La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb, and Lu ions have been investigated in solution using conductometric, potentiometric, and spectrophotometric methods. The studies revealed the formation of M2L and ML complexes. The solid chelates have been characterized by elemental and thermal analysis, molar conductance, IR, 1H NMR (for La and Lu chelates), and electronic spectra. The bonding takes place through the coordination of nitrogen in the -CH=N- group and the oxygen of the hydroxyl group by proton displacement. (author)

  15. Ethyl acetoacetate ligand distribution in the course of titanium n-butoxide chelation

    International Nuclear Information System (INIS)

    Sols obtained by chelation of titanium n-butoxide with ethyl acetoacetate, Eaa, in various ratios have been subjected to FTIR, 1H and 13C NMR, HSQC and UV–Vis spectroscopy in order to provide insight in the compounds obtained, their structure and quantitative relationships. Three compounds, the bis-chelated monomer, Ti(OnBu)2(Eaa)2, bis-chelated dimer, (Ti(OnBu)3Eaa)2 and monochelated dimer, Ti2(OnBu)7Eaa have been established. As the molar ratio Eaa/Ti(OnBu)4 increases, the coordination changes from the monochelated and bis-chelated dimer to the bis-chelated monomer. Additionally, the transesterification reaction, influencing the chemical composition of the compounds was noted. The hydrolysis of the prepared sols was partial, leaving some residual butoxy and ethyl acetoacetate groups attached to titanium. Thermal treatment of the prepared amorphous gels at 350 °C yielded with the formation of nanocrystalline anatase. It was noted that high Eaa/Tnb ratio slightly retards the anatase formation. - Highlights: • Titanium n-butoxide was modified with ethyl acetoacetate in various ratios. • Among other chelate phases, previously undescribed Ti2(OnBu)7Eaa was obtained. • NMR-based mass balance procedure was introduced to obtain quantitative relationships. • The transesterification reaction has been noted. • Nanocrystalline anatase has been obtained by thermal treatment at 350 °C

  16. Uptake of oxo-anions by cements through solid-solution formation: experimental evidence and modelling

    International Nuclear Information System (INIS)

    Uptake experiments were carried out with selenate and chromate on fresh and leached Portland and high-alumina cements; and in addition with selenate and selenite on synthetic ettringite. In all experiments with cements, exceptionally high uptake could be observed under conditions where significant amounts of secondary ettringite were formed. Experimental data obtained for pure ettringite corroborated the important role of this mineral phase. However, uptake kinetics show opposite trends in these two systems, which can be viewed as end-members of the same process: Where a fast precipitation of secondary ettringite occurred, initial uptake was high, with Kd values in the range of ∼ 1-5 m3/kg for Se(VI), but decreased with time. Uptake by pre-formed (primary) ettringite initially gave lower Kd values (∼ 0.1 m3/kg), which increased with time. After prolonged equilibration times, the two systems started to approach each other. Concurrent measurements of sulphate concentrations allowed to extract a mean partition coefficient for the solid-solution formation of selenite and selenate with ettringite. Based on this simple solid-solution model, a pragmatic quantitative relation was developed that permits to estimate Kd for Se(VI) on whole cement as a function of the concentrations of sulphate in the cement and in the solution. A test against experimental data shows reasonably good agreement between measurements and calculations. This relation can also be directly applied to estimate Kd values of chromate (and perrhenate) by different cements, indicating the same uptake mechanism. The approach may be less well suited for Se(IV), whose uptake on cement appears to be related mainly to minerals other than ettringite. (orig.)

  17. Importance of iron chelation therapy

    OpenAIRE

    A. Varoğlu

    2011-01-01

    It is necessary to remember that today patients have different options of chelation treatment, as desferrioxamine, deferiprone and deferasirox are available. However, a patient has to be compliant with treatments. They have always to remember that too much iron causes different complications and could be a barrier for a definitive cure from thalassemia. 由于出现了去铁胺、去铁酮和去铁斯若等药物,病人现在可以选择不同的螯合治疗方式。 然而,病人必须适应这几种治疗方式。 他们必须时刻记住太多的铁元素会引发多种并发症,并对地中海贫血的彻底治疗造成阻碍。...

  18. Targeted cleavage of HIV RRE RNA by Rev-coupled transition metal chelates.

    Science.gov (United States)

    Joyner, Jeff C; Cowan, J A

    2011-06-29

    A series of compounds that target reactive metal chelates to the HIV-1 Rev response element (RRE) mRNA have been synthesized. Dissociation constants and chemical reactivity toward HIV RRE RNA have been determined and evaluated in terms of reduction potential, coordination unsaturation, and overall charge associated with the metal-chelate-Rev complex. Ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) were linked to a lysine side chain of a Rev-derived peptide by either EDC/NHS or isothiocyanate coupling. The resulting chelate-Rev (EDTA-Rev, DTPA-Rev, NTA-Rev, and DOTA-Rev) conjugates were used to form coordination complexes with Fe(2+), Co(2+), Ni(2+), and Cu(2+) such that the arginine-rich Rev peptide could mediate localization of the metal chelates to the Rev peptide's high-affinity mRNA binding partner, RRE stem loop IIB. Metal complexes of the extended peptides GGH-Rev and KGHK-Rev, which also contain N-terminal peptidic chelators (ATCUN motifs), were studied for comparison. A fluorescence titration assay revealed high-affinity RRE RNA binding by all 22 metal-chelate-Rev species, with K(D) values ranging from ~0.2 to 16 nM, indicating little to no loss of RNA affinity due to the coupling of the metal chelates to the Rev peptide. Dissociation constants for binding at a previously unobserved low-affinity site are also reported. Rates of RNA modification by each metal-chelate-Rev species were determined and varied from ~0.28 to 4.9 nM/min but were optimal for Cu(2+)-NTA-Rev. Metal-chelate reduction potentials were determined and varied from -228 to +1111 mV vs NHE under similar solution conditions, allowing direct comparison of reactivity with redox thermodynamics. Optimal activity was observed when the reduction potential for the metal center was poised between those of the two principal co-reagents for metal-promoted formation of

  19. Chelating agents in pharmacology, toxicology and therapeutics

    International Nuclear Information System (INIS)

    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 63Ni, 109Cd, 203Hg, 144Ce, 95Nb and the excretion of 210Po, 63Ni, 48V, 239Pu, 241Am, 54Mn; 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.)

  20. Chelation behavior of various flavonols and transfer of flavonol-chelated zinc(II) to alanylaspartic dipeptide: A PCM/DFT investigation

    Science.gov (United States)

    Yasarawan, Nuttawisit; Thipyapong, Khajadpai; Ruangpornvisuti, Vithaya

    2016-03-01

    Alanylaspartic dipeptide (AlaAsp) and zinc(II)-flavonol complex could represent a metal-binding site in proteins and a metal-ion releasing agent, respectively. Chelation of zinc(II) by either AlaAsp or flavonol ligands in aqueous solution has been examined using DFT methods with polarizable continuum model (PCM/DFT). Coordination geometry, complexation stoichiometry, coordination bond strength, preferable metal-binding site on ligands and effect of water coordination on the stability of complexes have been addressed. In several cases, the long-range corrected density functional CAM-B3LYP allows the most accurate prediction of both structural and spectroscopic data. The preferential transfer of flavonol-chelated zinc(II) to AlaAsp under solvation is attainable through the ligand-exchange reaction. The energy barrier of such reaction is significantly dependent on the degree of hydrogen bonding within the transition state. In summary, either hydroxylation or methoxylation at particular positions on the 3-hydroxyflavone backbone significantly affects the reactivity of flavonol chelates in the metal-ion transfer.

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

    OpenAIRE

    Maria D. Avila; 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% re...

  2. 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.

  3. Intracellular reduction/activation of a disulfide switch in thiosemicarbazone iron chelators

    Science.gov (United States)

    Akam, Eman A.; Chang, Tsuhen M.; Astashkin, Andrei V.

    2014-01-01

    Iron scavengers (chelators) offer therapeutic opportunities in anticancer drug design by targeting the increased demand for iron in cancer cells as compared to normal cells. Prochelation approaches are expected to avoid systemic iron depletion as chelators are liberated under specific intracellular conditions. In the strategy described herein, a disulfide linkage is employed as a redox-directed switch within the binding unit of an antiproliferative thiosemicarbazone prochelator, which is activated for iron coordination following reduction to the thiolate chelator. In glutathione redox buffer, this reduction event occurs at physiological concentrations and half-cell potentials. Consistent with concurrent reduction and activation, higher intracellular thiol concentrations increase cell susceptibility to prochelator toxicity in cultured cancer cells. The reduction of the disulfide switch and intracellular iron chelation are confirmed in cell-based assays using calcein as a fluorescent probe for paramagnetic ions. The resulting low-spin Fe(III) complex is identified in intact Jurkat cells by EPR spectroscopy measurements, which also document a decreased concentration of active ribonucleotide reductase following exposure to the prochelator. Cell viability and fluorescence-based assays show that the iron complex presents low cytotoxicity and does not participate in intracellular redox chemistry, indicating that this antiproliferative chelation strategy does not rely on the generation of reactive oxygen species. PMID:25100578

  4. Intracellular reduction/activation of a disulfide switch in thiosemicarbazone iron chelators.

    Science.gov (United States)

    Akam, Eman A; Chang, Tsuhen M; Astashkin, Andrei V; Tomat, Elisa

    2014-10-01

    Iron scavengers (chelators) offer therapeutic opportunities in anticancer drug design by targeting the increased demand for iron in cancer cells as compared to normal cells. Prochelation approaches are expected to avoid systemic iron depletion as chelators are liberated under specific intracellular conditions. In the strategy described herein, a disulfide linkage is employed as a redox-directed switch within the binding unit of an antiproliferative thiosemicarbazone prochelator, which is activated for iron coordination following reduction to the thiolate chelator. In glutathione redox buffer, this reduction event occurs at physiological concentrations and half-cell potentials. Consistent with concurrent reduction and activation, higher intracellular thiol concentrations increase cell susceptibility to prochelator toxicity in cultured cancer cells. The reduction of the disulfide switch and intracellular iron chelation are confirmed in cell-based assays using calcein as a fluorescent probe for paramagnetic ions. The resulting low-spin Fe(III) complex is identified in intact Jurkat cells by EPR spectroscopy measurements, which also document a decreased concentration of active ribonucleotide reductase following exposure to the prochelator. Cell viability and fluorescence-based assays show that the iron complex presents low cytotoxicity and does not participate in intracellular redox chemistry, indicating that this antiproliferative chelation strategy does not rely on the generation of reactive oxygen species. PMID:25100578

  5. Current Use of Chelation in American Health Care

    OpenAIRE

    Wax, Paul M.

    2013-01-01

    The National Center for Health Statistics estimates that more than 100,000 Americans receive chelation each year, although far fewer than 1 % of these cases are managed by medical toxicologists. Unfortunately, fatalities have been reported after inappropriate chelation use. There are currently 11 FDA-approved chelators available by prescription although chelation products may also be obtained through compounding pharmacies and directly over the internet. Promotion of chelation training is pro...

  6. Copper Chelation in Alzheimer's Disease Protein

    Science.gov (United States)

    Rose, Frisco; Hodak, Miroslav; Bernholc, Jerry

    2013-03-01

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

  7. Lanthanide complexes of an oxazoline-phenoxide hybrid chelate

    International Nuclear Information System (INIS)

    The synthesis of 2-(2'-hydroxy-3'-allylphenyl)-4,4-dimethyl-2-oxazoline, H-Allox (3), and lanthanide tris chelate complexes, mer-Ln(Allox)3 (Ln = La (4), Ce (5), Sm (6), Er (7), and Y (8)), derived from it are reported. A six-coordinate mer geometry without alkene coordination was confirmed in the solid state by X-ray crystallography for 5 and 7. Variable-temperature NMR experiments suggested that this is the most stable isomer in solution as well, although the inequivalent ligand environments undergo rapid averaging at room temperature for all five complexes. A mechanistic investigation indicated that this fluxional process is an intramolecular six-coordinate rearrangement, but it was not possible to distinguish between a Bailar (trigonal) or Ray-Dutt (rhombic) twist. Kinetic parameters for the fluxional process were determined by line shape analysis for 8 yielding ΔH = 24 ± 2 kJ mol-1 and ΔS = -99 ± 10 J mol-1 K-1. The structural and dynamic features of 4-8 were compared with the related In, Ga, and Al tris(2-oxazolylphenoxides). (author)

  8. Optimisation and status of chelation therapy

    International Nuclear Information System (INIS)

    The calcium trisodium salt of diethylenetriaminepentaacetic acid (Ca-DTPA) remains the chelating agent of choice for treatment of incorporated actinides. The zinc trisodium salt (Zn-DTPA) represents a less toxic alternative, when Ca-DTPA is contra-indicated as well as for prolonged chelation therapy; in acute incorporation cases it would be less effective than Ca-DTPA. Specific ion binding chelators such as desferrioxamine (DFOA) and linear tetracatechoylamides, e.g., LICAM(C) proved more effective in animals injected with Pu, Th and Np (not with Am!) but only concerning the radioactivity in the bone; that in the kidneys was substantially increased. The combinations of DFOA or LICAM(C) with Ca-DTPA exerted the best overall effects. After incorporation of soluble uranium-compounds, an infusion of sodium bicarbonate seems at present the most reasonable for enhancing the uranium-excretion and prevention of kidney damage. (author)

  9. Trypanotoxic activity of thiosemicarbazone iron chelators.

    Science.gov (United States)

    Ellis, Samuel; Sexton, Darren W; Steverding, Dietmar

    2015-03-01

    Only a few drugs are available for treating sleeping sickness and nagana disease; parasitic infections caused by protozoans of the genus Trypanosoma in sub-Saharan Africa. There is an urgent need for the development of new medicines for chemotherapy of these devastating diseases. In this study, three newly designed thiosemicarbazone iron chelators, TSC24, Dp44mT and 3-AP, were tested for in vitro activity against bloodstream forms of Trypanosoma brucei and human leukaemia HL-60 cells. In addition to their iron chelating properties, TSC24 and Dp44mT inhibit topoisomerase IIα while 3-AP inactivates ribonucleotide reductase. All three compounds exhibited anti-trypanosomal activity, with minimum inhibitory concentration (MIC) values ranging between 1 and 100 µM and 50% growth inhibition (GI50) values of around 250 nM. Although the compounds did not kill HL-60 cells (MIC values >100 µM), TSC24 and Dp44mT displayed considerable cytotoxicity based on their GI50 values. Iron supplementation partly reversed the trypanotoxic and cytotoxic activity of TSC24 and Dp44mT but not of 3-AP. This finding suggests possible synergy between the iron chelating and topoisomerase IIα inhibiting activity of the compounds. However, further investigation using separate agents, the iron chelator deferoxamine and the topoisomerase II inhibitor epirubicin, did not support any synergy for the interaction of iron chelation and topoisomerase II inhibition. Furthermore, TSC24 was shown to induce DNA degradation in bloodstream forms of T. brucei indicating that the mechanism of trypanotoxic activity of the compound is topoisomerase II independent. In conclusion, the data support further investigation of thiosemicarbazone iron chelators with dual activity as lead compounds for anti-trypanosomal drug development. PMID:25595343

  10. Ethyl acetoacetate ligand distribution in the course of titanium n-butoxide chelation

    Energy Technology Data Exchange (ETDEWEB)

    Kurajica, S., E-mail: stankok@fkit.hr; Škorić, I.; Lozić, I.; Mandić, V.

    2014-10-15

    Sols obtained by chelation of titanium n-butoxide with ethyl acetoacetate, Eaa, in various ratios have been subjected to FTIR, {sup 1}H and {sup 13}C NMR, HSQC and UV–Vis spectroscopy in order to provide insight in the compounds obtained, their structure and quantitative relationships. Three compounds, the bis-chelated monomer, Ti(O{sup n}Bu){sub 2}(Eaa){sub 2}, bis-chelated dimer, (Ti(O{sup n}Bu){sub 3}Eaa){sub 2} and monochelated dimer, Ti{sub 2}(O{sup n}Bu){sub 7}Eaa have been established. As the molar ratio Eaa/Ti(O{sup n}Bu){sub 4} increases, the coordination changes from the monochelated and bis-chelated dimer to the bis-chelated monomer. Additionally, the transesterification reaction, influencing the chemical composition of the compounds was noted. The hydrolysis of the prepared sols was partial, leaving some residual butoxy and ethyl acetoacetate groups attached to titanium. Thermal treatment of the prepared amorphous gels at 350 °C yielded with the formation of nanocrystalline anatase. It was noted that high Eaa/Tnb ratio slightly retards the anatase formation. - Highlights: • Titanium n-butoxide was modified with ethyl acetoacetate in various ratios. • Among other chelate phases, previously undescribed Ti{sub 2}(O{sup n}Bu){sub 7}Eaa was obtained. • NMR-based mass balance procedure was introduced to obtain quantitative relationships. • The transesterification reaction has been noted. • Nanocrystalline anatase has been obtained by thermal treatment at 350 °C.

  11. FTIR, magnetic, mass spectral, XRD and thermal studies of metal chelates of tenoxicam

    Science.gov (United States)

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

    2007-09-01

    Metal chelates of anti-inflammatory drug, tenoxicam (Ten), are synthesized and characterized using elemental analyses, IR, solid reflectance, magnetic, mass spectra, thermal analyses (TGA and DTA) and X-ray powder diffraction techniques. The chelates are found to have the general formulae [M(H 2L) 2(H 2O) x] (A) 2· yH 2O (where H 2L = neutral Ten, A = Cl in case of Ni(II) and Co(II) or AcO in case of Cu(II) and Zn(II) ions, x = 0-2 and y = 0-2.5) and [M(H 2L) 3](A) z· yH 2O (A = SO 4 in case of Fe(II) ion ( z = 1) or Cl in case of Fe(III) ( z = 3) and y = 0-4). IR spectra reveal that Ten behaves as a neutral bidentate ligand coordinated to the metal ions through the pyridyl- N and carbonyl- O of the amide moiety. The solid reflectance spectra and magnetic moment measurements reveal that these chelates have tetrahedral, square planar and octahedral geometrical structures. Mass spectra are also used to confirm the proposed formulae and the possible fragments resulted from fragmentation of Ten and its Zn(II) and Cu(II) chelates are suggested. The thermal behaviour of the chelates (TG/DTG, DTA) are discussed in detailed manner and revealed that water molecules of crystallization together with anions are removed in the first and second steps while the Ten molecules are removed in the subsequent steps. Different thermodynamic parameters are evaluated and the relative thermal stabilities of the complexes are discussed. X-ray powder diffraction patterns are used to indicate the polymorphic form of Ten and if the complexes have molecular similarity with respect to type of coordination.

  12. Recent developments centered on orally active iron chelators

    Directory of Open Access Journals (Sweden)

    Robert Hider

    2014-09-01

    Full Text Available Over the past twenty years there has been a growing interest in the orally active iron chelators, deferiprone and deferasirox, both have been extensively studied. The ability of these compounds to mobilize iron from the heart and endocrine tissue has presented the clinician with some advantages over desferrioxamine, the first therapeutic iron chelator. Other orally active iron chelators are currently under development. The critical features necessary for the design of therapeutically useful orally active iron chelators are presented in this review, together with recent studies devoted to the design of such chelators. This newly emerging range of iron chelators will enable clinicians to apply iron chelation methodology to other disease states and to begin to design personalized chelation regimes.

  13. Development of an upconverting chelate assay

    Science.gov (United States)

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

    2005-04-01

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

  14. Questions and Answers on Unapproved Chelation Products

    Science.gov (United States)

    ... it Email Print The U.S. Food and Drug Administration (FDA) advises consumers to be wary of so-called “chelation” products that are marketed over-the-counter (OTC) to prevent or treat diseases. Companies are marketing unapproved OTC chelation therapy products to ...

  15. Overview of chelation recommendations for thalassaemia and sickle cell disease

    OpenAIRE

    Banu Kaya

    2014-01-01

    The long term consequences of iron toxicity are mostly reversible with effective iron chelation therapy. Recommendations for use of chelation therapy in transfusion dependent thalassaemia (TDT), sickle cell disease (SCD) and non transfusion dependent thalassaemia (NTDT) continue to evolve as our knowledge and clinical experience increases. Improved chelation options including drug combinations and a better understanding of condition specific factors may help to improve efficiency of chelation...

  16. Overview of chelation recommendations for thalassaemia and sickle cell disease

    Directory of Open Access Journals (Sweden)

    Banu Kaya

    2014-12-01

    Full Text Available The long term consequences of iron toxicity are mostly reversible with effective iron chelation therapy. Recommendations for use of chelation therapy in transfusion dependent thalassaemia (TDT, sickle cell disease (SCD and non transfusion dependent thalassaemia (NTDT continue to evolve as our knowledge and clinical experience increases. Improved chelation options including drug combinations and a better understanding of condition specific factors may help to improve efficiency of chelation regimens and meet the needs of patients more effectively.

  17. COMPARATIVE STUDY OF CHELATION VALUE OF SEVENTEEN PERCENT SELF DEVELOPED AND COMMERCIALLY AVAILABLE ROOT CANAL LUBRICANTS

    OpenAIRE

    Ingale Satish Dinkarrao; Kankariya Rajendra

    2013-01-01

    The main objective of this study is to compare chelation values of 17% self developed & commercially available root canal Lubricants or dental chelating gels as well as to see whether their performance depends on the chelation value or not. The Chelating agent bounds Ca2+ ions of the smear layer & the extent of chelate formation between chelating agent and metal ion is nothing but Chelation Value. Sodium carbonate indicator method is used for determinations of chelation value. Commercially av...

  18. New method to estimate stability of chelate complexes

    CERN Document Server

    Grigoriev, F V; Romanov, A N; Kondakova, O A; Sulimov, V B

    2009-01-01

    A new method allowing calculation of the stability of chelate complexes with Mg2+ ion in water have been developed. The method is based on two-stage scheme for the complex formation. The first stage is the ligand transfer from an arbitrary point of the solution to the second solvation shell of the Mg2+ ion. At this stage the ligand is considered as a charged or neutral rigid body. The second stage takes into account disruption of coordinate bonds between Mg2+ and water molecules from the first solvation shell and formation of the bonds between the ligand and the Mg2+ ion. This effect is considered using the quantum chemical modeling. It has been revealed that the main contribution to the free energy of the complex formation is caused by the disruption/formation of the coordinate bonds between Mg2+, water molecules and the ligand. Another important contribution to the complex formation energy is change of electrostatic interactions in water solvent upon the ligand binding with Mg2+ ion. For all complexes under...

  19. Influence of Chelating Agents on Chromium Fate in Sediment

    Institute of Scientific and Technical Information of China (English)

    WANGXIAOCHANG; SUNJINHE; 等

    1996-01-01

    A laboratory investigation on reaction between chelating agents and chromium was conducted to evaluate the effect of chelating agents on the adsorption and desorption of chromium in sediment.The amount of adsorbed chromium(VI) in sediment decreased slightly by 5%-10% because of addition of chelating agents.Chelating agents inhibited the removal of Cr(Ⅲ)by sediment from solutions and the inhibiting effect was in the order:citric acid>tartaric acid>EDTA,Salicylic acid.No effect of chelating agents on desorption of chromium in sediment was observed.

  20. Modelling studies in aqueous solution of lanthanide (III) chelates designed for nuclear magnetic resonance biomedical applications

    Science.gov (United States)

    Henriques, E. S.; Geraldes, C. F. G. C.; Ramos, M. J.

    Molecular dynamics simulations and complementary modelling studies have been carried out for the [Gd(DOTA)·(H2O)]- and [Tm(DOTP)]5- chelates in aqueous media, to provide a better understanding of several structural and dynamical properties of these versatile nuclear magnetic resonance (NMR) probes, including coordination shells and corresponding water exchange mechanisms, and interactions of these complexes with alkali metal ions. This knowledge is of key importance in the areas of 1H relaxation and shift reagents for NMR applications in medical diagnosis. A new refinement of our own previously developed set of parameters for these Ln(III) chelates has been used, and is reported here. Calculations of water mean residence times suggest a reassessment of the characterization of the chelates' second coordination shell, one where the simple spherical distribution model is discarded in favour of a more detailed approach. Na+ probe interaction maps are in good agreement with the available site location predictions derived from 23Na NMR shifts.

  1. Introducing new 99m-Tc-bifunctional radiopharmaceutical containing dithiosemicarbazone chelate group

    International Nuclear Information System (INIS)

    In our attempt to develop 99m-Tc-Bifunctional Radiopharmaceuticals (BR) of biomolecules, our interest has been focussed on the di-thiosemicarbazone chelating group (DTS); its coordination moiety allows a 1:1 complex with a tetravalent TcO2+, generating a neutral chelate of great stability and compactness. For ligand containing S N coordination, satisfactory labeling has been achieved at pH 5-6, in the presence of Sn-Resin. Based on the above mentioned, the use of DTS is tested in two different modalities by selecting glucose and albumin as the biomolecules of interest. The synthesis of a glucosone-1,2-bis (thiosemicarbazone) (Glu-DTS) and upon its labelling, the 99m-Tc-Glu-DTS was tested in animals. Scintigraphic studies revealed high activity in the brain and heart. This result offered strong support for the use of DTS as a bifunctional chelating agent (BCA). DTS-COOH and DTS-NH2 were synthesized for the coupling with biomolecules. As a first trial, they were coupled with albumin and their functionality proven. The results gathered provided conclusive evidence for the remarkable characteristic of DTS as a basic structure for the development of 99m-Tc-RP

  2. Pentaarylcyclopentadiene und chirale Ruthenium-Chelat-Komplexe

    OpenAIRE

    Kanthak, Matthias

    2010-01-01

    Die Synthese von mono-ortho-funktionalisierten Pentaphenylcyclopentadienen gelang durch eine Abwandlung der klassischen Tetracyclon-Route. Durch die Umsetzung der funktionalisierten Cyclopentadiene mit Ru3(CO)12 als Metallquelle konnten entsprechende Ruthenium-Komplexe erhalten werden. Die geeignete Wahl der Substituenten an der Phenylgruppe erlaubte die Bildung von Chelat-Komplexen mit chirotopem Metallzentrum. Enantiomerenreine Oxazolin-Seitenarme führten zu diastereomerenreinen...

  3. Federal Regulation of Unapproved Chelation Products

    OpenAIRE

    Lee, Charles E.

    2013-01-01

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

  4. EDTA: the chelating agent under environmental scrutiny

    OpenAIRE

    Claudia Oviedo; Jaime Rodríguez

    2003-01-01

    The chelating agent EDTA (ethylenediaminetetraacetic acid) is a compound of massive use world wide with household and industrial applications, being one of the anthropogenic compounds with highest concentrations in inland European waters. In this review, the applications of EDTA and its behavior once it has been released into the environment are described. At a laboratory scale, degradation of EDTA has been achieved; however, in natural environments studies detect poor biodegradability. It is...

  5. Practically Coordinating

    OpenAIRE

    Durfee, Edmund H.

    1999-01-01

    To coordinate, intelligent agents might need to know something about themselves, about each other, about how others view themselves and others, about how others think others view themselves and others, and so on. Taken to an extreme, the amount of knowledge an agent might possess to coordinate its interactions with others might outstrip the agent's limited reasoning capacity (its available time, memory, and so on). Much of the work in studying and building multiagent systems has thus been dev...

  6. Conjugates of monoclonal antibodies and chelating polymers

    International Nuclear Information System (INIS)

    The primary purpose of protein modification with chelating polymers is to prepare monoclonal antibodies labeled with heavy metal isotopes (alpha-, beta-, and gamma-emitting metal and paramagnetic ions for NMR tomography). Conventional binding of metals to proteins via chelating agents directly coupled to proteins does not permit binding of a large number of metal atoms per protein molecule without causing alterations in the specific properties of the protein molecules. On the other hand, metal ion binding to proteins via intermediate chelating polymers should permit binding of several dozens of the metal atoms per protein molecule without affect the specific properties adversely. Moreover, the biodistribution and clearance rates can be regulated by varying the polymer properties. Modified antibodies may be used successfully in nuclear and NMR diagnostic applications and in radiotherapy. Possible applications of this approach shall be demonstrated with monoclonal antibody R11D10 for visualization of acute myocardial infarction. Use of this modification with other monoclonal antibodies is also discussed. The chemistry of protein modification with these polymers is presented

  7. Decorporation of metal ions by chelating agents

    International Nuclear Information System (INIS)

    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)

  8. 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

  9. Synthesis of Two New Group 13 Benzoato-Chloro Complexes: A Structural Study of Gallium and Indium Chelating Carboxylates

    Science.gov (United States)

    Duraj, Stan A.; Hepp, Aloysius F.; Woloszynek, Robert; Protasiewicz, John D.; Dequeant, Michael; Ren, Tong

    2010-01-01

    Two new heteroleptic chelated-benzoato gallium (III) and indium (III) complexes have been prepared and structurally characterized. The molecular structures of [GaCl2(4-Mepy)2(O2CPh)]4-Mepy (1) and [InCl(4-Mepy)2(O2CPh)2]4-Mepy (2) have been determined by single-crystal x-ray diffraction. The gallium compound (1) is a distorted octahedron with cis-chloride ligands co-planar with the chelating benzoate and the 4-methylpyridines trans to each other. This is the first example of a Ga(III) structure with a chelating benzoate. The indium compound (2) is a distorted pentagonal bipyramid with two chelating benzoates, one 4-methylpyridine in the plane and a chloride trans to the other 4-methylpyridine. The indium bis-benzoate is an unusual example of a seven-coordinate structure with classical ligands. Both complexes, which due to the chelates, could also be described as pseudo-trigonal bipyramidal, include a three-bladed motif with three roughly parallel aromatic rings that along with a solvent of crystallization and electron-withdrawing chloride ligand(s) stabilize the solid-state structures.

  10. sup(1)H, sup(13)C and sup(17)O NMR studies of cumene hydroperoxide coordination to Cr(AA)sub(3)

    International Nuclear Information System (INIS)

    The mechanism of the catalytic decomposition of hydroperoxides by tris-chelates of transition metals was studied by means of NMR. It was established that the outer sphere coordination of cumene hydroperoxide to tris-acetylacetonate of Cr(III) (Cr(AA)sub(3)) is due to both the formation of hydrogen bonds between hydroxyl proton and chelate oxygen atoms and the π-π-interactions between the aromatic ring and chelate π-system. (author)

  11. REGIONAL SIDEROSIS: A NEW CHALLENGE FOR IRON CHELATION THERAPY

    OpenAIRE

    ZviIoavCabantchik; ArnoldMunnich; MoussaB.Youdim; DavidDevos

    2013-01-01

    The traditional role of iron chelation therapy has been to reduce body iron burden via chelation of excess metal from organs and fluids and its excretion via biliary-fecal and/or urinary routes. In their present use for hemosiderosis, chelation regimens might not be suitable for treating disorders of iron maldistribution, as those are characterized by toxic islands of siderosis appearing in a background of normal or subnormal iron levels (e.g. sideroblastic anemias, neuro- and cardio-siderosi...

  12. Modern problems of chelate water conditions for TPPs and NPPs

    International Nuclear Information System (INIS)

    Review of investigations devoted to the application of chelate water conditions for TPPs and NPPs is given. Chelates (mainly EDTA and its salts) are used for increasing corrosion resistance of steels, operation and pre-start-up chemical purifications, correction of water conditions and coolant circuit purification under operation (without shutdown). It is stressed that under certain conditions the optimal continuous chelate water conditions are possible under water conditions are possible under which deposits are not produced

  13. Structures and Electronic Properties of Lithium Chelate-Based Ionic Liquids.

    Science.gov (United States)

    Si, Dawei; Chen, Kexian; Yao, Jia; Li, Haoran

    2016-04-28

    The conformations, electronic properties, and interaction energies of four chelate-based ionic liquids [Li(EA)][Tf2N], [Li(HDA)][Tf2N], [Li(DEA)][Tf2N], and [Li(DOBA)][Tf2N] have been theoretically explored. The reliability of the located conformers has been confirmed via the comparison between the simulated and experimental infrared spectra. Our results show that the N-Li and O-Li coordinate bonds in cation are elongated as the numbers of coordinate heteroatoms of alkanolamine ligands to Li(+) increased. Also the binding energies between Li(+) and ligands are increased and the interaction energies between cations and Tf2N anion are decreased. The cation-anion interaction energies follow the order of [Li(DOBA)][Tf2N] bond orbital analysis lie in the interaction between the lone pair (LP) of the coordinate heteroatoms in ligands or anion as donors and the vacant valence shell nonbonding orbital (LP*) of Li(+) as acceptors, which are very different from that of conventional ionic liquids. Moreover, the charges transferred from cations to anion are quite similar, and the charge of Li(+) is proposed for possibly predicting the order of the interaction energies of ionic liquids in series. The present study allows for the deeper understanding the differences between chelate-based ionic liquids and conventional ionic liquids. PMID:27070194

  14. Trypanotoxic activity of thiosemicarbazone iron chelators

    OpenAIRE

    Ellis, Samuel; Sexton, Darren; Steverding, Dietmar

    2015-01-01

    Only a few drugs are available for treating sleeping sickness and nagana disease; parasitic infections caused by protozoans of the genus Trypanosoma in sub-Saharan Africa. There is an urgent need for the development of new medicines for chemotherapy of these devastating diseases. In this study, three newly designed thiosemicarbazone iron chelators, TSC24, Dp44mT and 3-AP, were tested for in vitro activity against bloodstream forms of T. brucei and human leukaemia HL-60 cells. In addition to t...

  15. Novel Terbium Chelate Doped Fluorescent Silica Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Ning Qiaoyu; Meng Jianxin; Wang Haiming; Liu Yingliang; Man Shiqing

    2006-01-01

    Novel terbium chelate doped silica fluorescent nanoparticles were prepared and characterized.The preparation was carried out in water-in-oil (W/O) microemulsion containing monomer precursor (pAB-DTPAA-APTEOS), Triton X-100, n-hexanol, and cyclohexane by controlling copolymerization of tetraethyl orthosilicate and 3-aminopropyl-triethyloxysilane.The nanoparticles are spherical and uniform in size, about 30 nm in diameter, strongly fluorescent, and highly stable.The amino groups directly introduced to the surface of the nanoparticles using APTEOS during preparation made the surface modification and bioconjugation of the nanoparticles easier.The nanoparticles are expected as an efficient time-resolved luminescence biological label.

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

    International Nuclear Information System (INIS)

    Several La0.05Sr0.95CoO3-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

  17. Plutonium-237: comparative uptake in chelated and non-chelated form by channel catfish (Ictalurus punctatus)

    International Nuclear Information System (INIS)

    Chelation can either enhance or reduce the uptake of ingested plutonium relative to PuOH (monomer) in channel catfish. Reduced uptake of 237Pu-fulvate is due either to the molecular weight of the complex or its stability in metabolic systems. Increased uptake of 237Pu-citrate is attributable to instability of the complex in metabolic systems. (author)

  18. 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.

  19. COMPARATIVE STUDY OF CHELATION VALUE OF SEVENTEEN PERCENT SELF DEVELOPED AND COMMERCIALLY AVAILABLE ROOT CANAL LUBRICANTS

    Directory of Open Access Journals (Sweden)

    Ingale Satish Dinkarrao

    2013-06-01

    Full Text Available The main objective of this study is to compare chelation values of 17% self developed & commercially available root canal Lubricants or dental chelating gels as well as to see whether their performance depends on the chelation value or not. The Chelating agent bounds Ca2+ ions of the smear layer & the extent of chelate formation between chelating agent and metal ion is nothing but Chelation Value. Sodium carbonate indicator method is used for determinations of chelation value. Commercially available gel incorporated in this study was File Rite which has little bit higher chelation value. Self developed chelating gel or root canal lubricants have comparatively lower chelation value. Root canal lubricants having higher chelation value should perform better in shaping & cleaning of root canal better. However because of slight difference in chelation value of self developed & commercially available gel, no significant difference was found out as root canal lubricants, when applied in root canal for 5 minutes.

  20. High-performance chelation chromatography of metal ions on sorbents with grafted iminodiacetic acid

    International Nuclear Information System (INIS)

    Chromatographic behavior of some alkaline earth, transition, heavy (including uranium) and rare earth metal ions on a group of complexing sorbents, containing surface functional groups of imidodiacetic acid, was studied. Conditions, under which metal retention is determined by complexing on the sorbent surface, were defined and main principles of a new variant of liquid chromatography, i.e. high-performance chelating chromatography of metal ions (HPCCI) were formulated. It is shown that under optimal conditions metal retention correlates linearly in bilogarithmic coordinates with stability constants of the relevant metal complexes. Potentialities of HPCCI analytic application to analysis of objects featuring complex composition were considered

  1. Enhanced removal of 241Am by DTPA chelation therapy in an adult and teenage subject

    International Nuclear Information System (INIS)

    A series of Na3 (Ca-DTPA) chelation treatments were carried out on two human subjects, an adult man and a teenage boy, who have long-term body burdens of 241Am. The in vivo whole-body counting, bioassay of urine and feces, and various blood chemistry measurements were coordinated to coincide with this therapy schedule. Decreases in total body burdens for this treatment period were measured as 5 percent in the adult and 30 percent in the youth. High concentrations of zinc in urine and a corresponding decrease of activity of the zinc-dependent erythropoietic enzyme, ALAD, were also observed. (U.S.)

  2. Crystal structure of an eight-coordinate terbium(III) ion chelated by N,N′-bis­(2-hy­droxy­benz­yl)-N,N′-bis­(pyridin-2-ylmeth­yl)ethyl­enedi­amine (bbpen2−) and nitrate

    OpenAIRE

    Gregório, Thaiane; Rüdiger, André Luis; Nunes, Giovana G.; Soares, Jaísa F.; Hughes, David L.

    2015-01-01

    The reaction of terbium(III) nitrate penta­hydrate in aceto­nitrile with N,N′-bis­(2-hy­droxy­benz­yl)-N,N′-bis­(pyridin-2-ylmeth­yl)ethyl­enedi­amine (H2bbpen), previously deprotonated with tri­ethyl­amine, produced the mononuclear compound [N,N′-bis­(2-oxidobenzyl-κO)-N,N′-bis­(pyridin-2-ylmethyl-κN)ethylenedi­amine-κ2 N,N′](nitrato-κ2 O,O′)terbium(III), [Tb(C28H28N4O2)(NO3)]. The mol­ecule lies on a twofold rotation axis and the TbIII ion is eight-coordinate with a slightly distorted dodec...

  3. Synthesis and characterization of a chelating resin containing ONO donor tridentate Schiff base and its coordination compounds with copper(II), nickel(II), cobalt(II), iron(III), zinc(II), cadmium(II), manganese(II), molybdenum(VI), zirconium(IV) and uranium(VI)

    International Nuclear Information System (INIS)

    New polystyrene supported coordination compounds have been synthesized by the reaction of metal salt/metal coordination compound with the polystyrene supported Schiff base (PS-LH2) (obtained by the reaction of chloromethylated polystyrene, 3-formylsalicylic acid and ethanolamine). The compounds have the formulae: PS-LCu.DMF, PS-LNi-3DMF, PS-LCo.3DMF, PS-LFeCl.2DMF, PS-LZn.DMF, PS-LCd.DMF, PS-LMn.3DMF, PS-LMoO2.DMF, PS-LZr(OH)2.2DMF and PS-LUO2.DMF (DMF = dimethylformamide). The compounds have been characterized by elemental analyses, IR, electronic, ESR spectral and magnetic susceptibility measurements. The Cu(II), Ni(II), Co(II), Fe(III) and Mn(II) compounds are paramagnetic while the Zn(II), Cd(II), Zr(IV), Mo(VI) and U(VI) compounds are diamagnetic. The magnetic and ESR data indicate the magnetically dilute nature of the metal centres. The shifts of the v(C=N)(azomethine), v(C-O)(phenolic) and v(C-O)(alcoholic) stretches have been monitored to find out the donor sites of PS-LH2. A square planar structure for PS-LCu.DMF; a tetrahedral structure for PS-LZn.DMF and PS-LCd.DMF; an octahedral structure for PS-LNi.3DMF, PS-LCo.3DMF, PS-LFeCl.2DMF, PS-LMn.3DMF, PS-LMoO2.DMF and PS-LUO2.DMF have been suggested for the compounds. PS-LZr(OH)2.2DMF is pentagonal bipyramidal. (author)

  4. 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; Springborg, Johan

    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...

  5. Decorporation of inhaled actinides by chelation therapy

    International Nuclear Information System (INIS)

    This article describes recent work in NRPB laboratories that has identified some of the factors influencing the behaviour of plutonium, americium and curium compounds in the body after inhalation, together with a number of experimental approaches that are being developed to optimise their treatment with DTPA. It is concluded that the most effective treatment has yet to be developed, but progress must depend on a better understanding of the factors governing the transport of actinides in the body. It cannot be assumed that because the inhaled material is readily translocated to blood, that treatment regimens with Ca-DTPA based solely on previous understanding of the metabolic fate of soluble actinide complexes will be successful. In fact, depending on the nature of the material involved in the accident, inhalation alone or combined with prolonged infusion of DTPA may be more effective than the periodic intravenous injections of the chelating agent alone. For poorly transportable materials such as insoluble plutonium-239 dioxide, chelation treatment remains essentially ineffective. (U.K.)

  6. Chemical treatment of chelated metal finishing wastes.

    Science.gov (United States)

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

    2012-12-01

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

  7. TECHNICAL COORDINATION

    CERN Multimedia

    A. Ball

    Overview From a technical perspective, CMS has been in “beam operation” state since 6th November. The detector is fully closed with all components operational and the magnetic field is normally at the nominal 3.8T. The UXC cavern is normally closed with the radiation veto set. Access to UXC is now only possible during downtimes of LHC. Such accesses must be carefully planned, documented and carried out in agreement with CMS Technical Coordination, Experimental Area Management, LHC programme coordination and the CCC. Material flow in and out of UXC is now strictly controlled. Access to USC remains possible at any time, although, for safety reasons, it is necessary to register with the shift crew in the control room before going down.It is obligatory for all material leaving UXC to pass through the underground buffer zone for RP scanning, database entry and appropriate labeling for traceability. Technical coordination (notably Stephane Bally and Christoph Schaefer), the shift crew and run ...

  8. 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+). PMID:20449110

  9. 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…

  10. Macrocyclic Chelator Assembled RGD Multimers for Tumor Targeting

    OpenAIRE

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

    2011-01-01

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

  11. Inapplicability of high pressure spray injection for chelate administration

    International Nuclear Information System (INIS)

    A high-pressure spray injector was tested for use in injecting chelating agents around radionuclides in wounds. It was difficult to employ because of the force required for proper injection, and it did not improve the effectiveness of the injected chelate in removing intramuscularly injected 238Pu. (U.S.)

  12. Adsorptive separation of rare earths by using chelating chitosan

    International Nuclear Information System (INIS)

    Two kinds of chelating chitosan were prepared by chemically modifying chitosan with functional groups of EDTA or DTPA, abbreviated as EDTA- and DTPA-chitosan hereafter, respectively, to investigate the adsorption behaviour for rare earths the mutual separation of which is the most difficult among metal ions on these chelating chitosan from dilute hydrochloric or sulfuric acid solution. The plots of the distribution ratio of a series of rare earths against equilibrium pH lay on different straight lines with slope of 3 corresponding to each earth for both of two chelating chitosan, suggesting that 3 hydrogen ions are released for the adsorption of unit ion of each rare earth by chelate formation with the functional group of EDTA or DTPA and that mutual adsorptive separation between adjacent rare earth is possible with these chelating chitosan. Apparent equilibrium constants of the adsorption were evaluated from the intercepts of these straight lines with the ordinate for each rare earth and for both chelating chitosan. It was found that the equilibrium constants of adsorption on EDTA- or DTPA-chitosan are quite analogous to those of chelate formation with EDTA or DTPA themselves, suggesting that chelating characteristics of these complexones is still maintained after their immobilization on polymer matrices of chitosan. (author)

  13. 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 lysi

  14. Quantitative measurement of metal chelation by fourier transform infrared spectroscopy

    Directory of Open Access Journals (Sweden)

    Monika E. Miller

    2015-12-01

    Full Text Available Nutritionally important minerals are more readily absorbed by living systems when complexed with organic acids, resulting in higher consumer demand and premium prices for these products. These chelated metals are produced by reaction of metal oxides and acids in aqueous solution. However, unreacted dry blends are sometimes misrepresented as metal chelates, when in reality they are only simple mixtures of the reactants typically used to synthesize them. This practice has increased interest in developing analytical methods that are capable of measuring the extent of metal chelation for quality control and regulatory compliance. We describe a novel method to rapidly measure the percent chelation of citric and malic acids with calcium, magnesium, and zinc. Utilization of attenuated total reflectance (FTIR-ATR provides for the direct, rapid measurement of solid samples. The inclusion of an internal standard allows independent determination of either free or chelated acids from integrated areas in a single spectrum.

  15. Copper, dioxouranium(VI) and lanthanide chelates of carboxymethylthiosuccinic acid

    International Nuclear Information System (INIS)

    Carboxymethylthiosuccinic acid (CMTSA) has three dissociable - COOH groups with pK values 2.91, 3.91, 5.03. Assignment of these values to the different carboxylic groups is given. Cu(II) and UO22+ chelates with CMSTA have been studied potentiometrically at 30degC and μ = 0.1M. The effects of dielectric constant of the solvent medium (dioxane-water) and the ionic strength, on these chelates have been examined. The lanthanides form 1:1 and 1:2 chelates with CMTSA. The plots of log K1 and (log K1 + log K2) versus e2/2r show a break at gadolinium. The thermodynamic parameters for these chelates have been determined. Smaller values of DELTAH show the predominance of the entropy effect in the formation of these chelates. (author)

  16. Coordinated unbundling

    DEFF Research Database (Denmark)

    Timmermans, Bram; Zabala-Iturriagagoitia, Jon Mikel

    2013-01-01

    not focused on the role this policy instrument can play in the promotion of (knowledge-intensive) entrepreneurship. This paper investigates this link in more detail and introduces the concept of coordinated unbundling as a strategy that can facilitate this purpose. We also present a framework on how......Public procurement for innovation is a matter of using public demand to trigger innovation. Empirical studies have demonstrated that demand-based policy instruments can be considered to be a powerful tool in stimulating innovative processes among existing firms; however, the existing literature has...

  17. Fixation kinetics of chelated and non-chelated zinc in semi-arid alkaline soils: application to zinc management

    Science.gov (United States)

    Udeigwe, Theophilus K.; Eichmann, Madeleine; Menkiti, Matthew C.

    2016-07-01

    This study was designed to examine the fixation pattern and kinetics of zinc (Zn) in chelated (ethylenediaminetetraacetic acid, EDTA) and non-chelated mixed micronutrient systems of semi-arid alkaline soils from the Southern High Plains, USA. Soils were characterized for a suite of chemical and physical properties and data obtained from extraction experiments fitted to various kinetic models. About 30 % more plant-available Zn was fixed in the non-chelated system within the first 14 days with only about 18 % difference observed between the two systems by day 90, suggesting that the effectiveness of the chelated compounds tended to decrease over time. The strengths of the relationships of change in available Zn with respect to other micronutrients (copper, iron, and manganese) were higher and more significant in the non-chelated system (average R2 of 0.83), compared to the chelated (average R2 of 0.42). Fixation of plant-available Zn was best described by the power-function model (R2 = 0.94, SE = 0.076) in the non-chelated system, and was poorly described by all the models examined in the chelated system. Reaction rate constants and relationships generated from this study can serve as important tools for micronutrient management and for future micronutrient modeling studies on these soils and other semi-arid regions of the world.

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

    International Nuclear Information System (INIS)

    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)

  19. TECHNICAL COORDINATION

    CERN Multimedia

    A. Ball

    2010-01-01

    Operational Experience At the end of the first full-year running period of LHC, CMS is established as a reliable, robust and mature experiment. In particular common systems and infrastructure faults accounted for <0.6 % CMS downtime during LHC pp physics. Technical operation throughout the entire year was rather smooth, the main faults requiring UXC access being sub-detector power systems and rack-cooling turbines. All such problems were corrected during scheduled technical stops, in the shadow of tunnel access needed by the LHC, or in negotiated accesses or access extensions. Nevertheless, the number of necessary accesses to the UXC averaged more than one per week and the technical stops were inevitably packed with work packages, typically 30 being executed within a few days, placing a high load on the coordination and area management teams. It is an appropriate moment for CMS Technical Coordination to thank all those in many CERN departments and in the Collaboration, who were involved in CMS techni...

  20. Improved Metathesis Lifetime: Chelating Pyridinyl-Alcoholato Ligands in the Second Generation Grubbs Precatalyst

    Directory of Open Access Journals (Sweden)

    Jean I. du Toit

    2014-04-01

    Full Text Available Hemilabile ligands can release a free coordination site “on demand” of an incoming nucleophilic substrate while occupying it otherwise. This is believed to increase the thermal stability and activity of catalytic systems and therefore prevent decomposition via free coordination sites. In this investigation chelating pyridinyl-alcoholato ligands were identified as possible hemilabile ligands for incorporation into the second generation Grubbs precatalyst. The O,N-alcoholato ligands with different steric bulk could be successfully incorporated into the precatalysts. The incorporation of the sterically hindered, hemilabile O,N-ligands improved the thermal stability, activity, selectivity and lifetime of these complexes towards the metathesis of 1-octene. A decrease in the activity of the second generation Grubbs precatalyst was additionally observed after incorporating a hemilabile O,N-ligand with two phenyl groups into the system, while increasing their lifetime.

  1. X-ray spectral study of structure of metal chelate dithiocarbamate complexes in solutions

    International Nuclear Information System (INIS)

    The structure of immediate surrounding of cadmium chelate dithiocarbamate complexes Cd[(C2H5)2NCS2]2 (or CdL2) and Cd[(n-C4H9)2NCS2]2 (or CdL21) in solutions of benzene, pyridine and tributylphosphine was studied by the EXAFS spectroscopy method using synchrotron radiation. When analyzing possible structure of cadmium complexes, two models were considered: monomeric and dimeric ones. It was ascertained that in benzene solutions there exist both dimeric and monomeric forms of CdL2. In pyridine solution coordination of nitrogen atom by cadmium atom both for CdL2 and CdL21 is observed. In solution of tributylphosphine coordination to metal of one or two phosphorus atoms with four sulfur atoms of ligand L1 is possible

  2. Synergistic and antagonistic effects in systems containing electrolytes and nonionic surfactant micelles on the photometric and analytical characteristics of chrome azurol S chelates

    International Nuclear Information System (INIS)

    The effects of strong electrolytes and surfactant micelles on the complexation of Chrome Azurol S with Be, Cu, Al, Sc, and Fe(3) ions were examined by spectrophotometry. Simultaneous addition of electrolytes and surfactant micelles caused a synergistic effect exhibited in a dramatic increase in the absorption intensity and the concentration of chelates with a maximum number of coordination ligands in the solution. An increase in the molar absorption coefficients of chelates, an improvement of the sensitivity of determination, and a decrease in the detection limits of metals by a factor of 2-10 resulted from this effect

  3. Coordination Capacity

    CERN Document Server

    Cuff, Paul; Cover, Thomas

    2009-01-01

    We develop elements of a theory of cooperation and coordination in networks. Rather than considering a communication network as a means of distributing information, or of reconstructing random processes at remote nodes, we ask what dependence can be established among the nodes given the communication constraints. Specifically, in a network with communication rates between the nodes, we ask what is the set of all achievable joint distributions p(x1, ..., xm) of actions at the nodes on the network. Several networks are solved, including arbitrarily large cascade networks. Distributed cooperation can be the solution to many problems such as distributed games, distributed control, and establishing mutual information bounds on the influence of one part of a physical system on another.

  4. The Structural Basis of Action of Vanadyl (VO(2+)) Chelates in Cells.

    Science.gov (United States)

    Makinen, Marvin W; Salehitazangi, Marzieh

    2014-11-01

    Much emphasis has been given to vanadium compounds as potential therapeutic reagents for the treatment of diabetes mellitus. Thus far, no vanadium compound has proven efficacious for long-term treatment of this disease in humans. Therefore, in review of the research literature, our goal has been to identify properties of vanadium compounds that are likely to favor physiological and biochemical compatibility for further development as therapeutic reagents. We have, therefore, limited our review to those vanadium compounds that have been used in both in vivo experiments with small, laboratory animals and in in vitro studies with primary or cultured cell systems and for which pharmacokinetic and pharmacodynamics results have been reported, including vanadium tissue content, vanadium and ligand lifetime in the bloodstream, structure in solution, and interaction with serum transport proteins. Only vanadyl (VO(2+)) chelates fulfill these requirements despite the large variety of vanadium compounds of different oxidation states, ligand structure, and coordination geometry synthesized as potential therapeutic agents. Extensive review of research results obtained with use of organic VO(2+)-chelates shows that the vanadyl chelate bis(acetylacetonato)oxidovanadium(IV) [hereafter abbreviated as VO(acac)2], exhibits the greatest capacity to enhance insulin receptor kinase activity in cells compared to other organic VO(2+)-chelates, is associated with a dose-dependent capacity to lower plasma glucose in diabetic laboratory animals, and exhibits a sufficiently long lifetime in the blood stream to allow correlation of its dose-dependent action with blood vanadium content. The properties underlying this behavior appear to be its high stability and capacity to remain intact upon binding to serum albumin. We relate the capacity to remain intact upon binding to serum albumin to the requirement to undergo transcytosis through the vascular endothelium to gain access to target tissues in

  5. Selectivity in extraction of copper and indium with chelate extractants

    International Nuclear Information System (INIS)

    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 CuR2 and InR3 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)

  6. RUN COORDINATION

    CERN Multimedia

    C. Delaere

    2013-01-01

    Since the LHC ceased operations in February, a lot has been going on at Point 5, and Run Coordination continues to monitor closely the advance of maintenance and upgrade activities. In the last months, the Pixel detector was extracted and is now stored in the pixel lab in SX5; the beam pipe has been removed and ME1/1 removal has started. We regained access to the vactank and some work on the RBX of HB has started. Since mid-June, electricity and cooling are back in S1 and S2, allowing us to turn equipment back on, at least during the day. 24/7 shifts are not foreseen in the next weeks, and safety tours are mandatory to keep equipment on overnight, but re-commissioning activities are slowly being resumed. Given the (slight) delays accumulated in LS1, it was decided to merge the two global runs initially foreseen into a single exercise during the week of 4 November 2013. The aim of the global run is to check that we can run (parts of) CMS after several months switched off, with the new VME PCs installed, th...

  7. RUN COORDINATION

    CERN Multimedia

    Christophe Delaere

    2013-01-01

    The focus of Run Coordination during LS1 is to monitor closely the advance of maintenance and upgrade activities, to smooth interactions between subsystems and to ensure that all are ready in time to resume operations in 2015 with a fully calibrated and understood detector. After electricity and cooling were restored to all equipment, at about the time of the last CMS week, recommissioning activities were resumed for all subsystems. On 7 October, DCS shifts began 24/7 to allow subsystems to remain on to facilitate operations. That culminated with the Global Run in November (GriN), which   took place as scheduled during the week of 4 November. The GriN has been the first centrally managed operation since the beginning of LS1, and involved all subdetectors but the Pixel Tracker presently in a lab upstairs. All nights were therefore dedicated to long stable runs with as many subdetectors as possible. Among the many achievements in that week, three items may be highlighted. First, the Strip...

  8. Screening wheat genotypes in response to ordinary chelate and nano-iron chelate fertilizers in nutrient solution

    OpenAIRE

    S. Omidi Nargesi; Zahedi, M; H.R. Eshghizadeh; A.H. Khoshgoftarmanesh

    2015-01-01

    Recently, attentions have been taken on the investigations regarding the use of nano-sized compounds in different fields including agricultural sector. Due to the importance of evaluating the fate and operation of nano-particles in plant systems, in this survey, responses of 13 wheat genotypes to the effect of nano-iron chelate fertilizer in the Hoagland solution under the conditions of ordinary iron chelate and nano-iron chelate, with concentration of 22.5 mg/L, was studied. This experiment ...

  9. Effects of macromolecular chelators on intestinal cadmium absorption in mice

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, O.; Nielsen, J.B.; Bulman, R.A.

    1989-01-01

    Suppression of absorption by macromolecular chelators have been sucessful with several metals. In this paper a series of immobilized chelators ranging from DTPA to S-containing soft bases have been synthetized and investigated for ability to suppress intestinal uptake of /sup 109/Cd/sup 2+/ in mice. Dextran-O-ethyl-mercaptan, xanthates derived from polysaccharides and polyvinyl alcohol, dithiocarbamates of polyethylene imine and aminoethyl cellulose, and DTPA immobilized on aminopropyl silica were all ineffective. DTPA immobilized on aminoethyl cellulose even enhanced the intestinal uptake. The macromolecular chelators were without extensive effect on organ distribution of absorbed cadmium, except for dithiocarbamate immobilized on polyethylene imine, which enhanced the deposition of cadmium in several organs including the brain. Although the results are discouragign, they indicate that desing and synthesis of immobilized vicinal dithio compounds may represent an avenue for development of non-absorbable chelators with high affinity for cadmium.

  10. Mixed-chelate therapy of intratracheally deposited cadmium oxide

    International Nuclear Information System (INIS)

    Mixed-chelate treatment with EDTA and salicylic acid was no more effective in accelerating the removal of intratracheally instilled 109CdO, or in protecting against CdO-induced mortality, than was EDTA given alone

  11. Comparing potential copper chelation mechanisms in Parkinson's disease protein

    Science.gov (United States)

    Rose, Frisco; Hodak, Miroslav; Bernholc, Jerry

    2011-03-01

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

  12. Synthesis and initial evaluation of multidentate Me-3,2-HOPO ligands for in vivo Pu(IV) chelation

    International Nuclear Information System (INIS)

    Ligands that stably bind Pu(IV) at physiological pH are needed to enhance its excretion after accidental human contamination. Based on the similarity in coordination properties between Fe(III) and Pu(IV), a new class of multidentate hydroxypyridinone (Me-3,2-HOPO) ligands has been synthesized. Three ligands have been found to be particularly effective, with low toxicity: TREN-(Me-3,2-HOPO) and two other Me-3,2-HOPO ligands. When injected or given orally, these have proven to be highly effective for chelation of Pu in vivo. In addition, TREN-(Me-3,2-HOPO) was found to be an exceptionally good in vivo chelator of Am(III); when injected, it also reduces the body content of Np(V) and reduces kidney U(VI) content effectively

  13. F-Element ion chelation in highly basic media. Annual progress report, October 1, 1996 - July 1, 1997

    International Nuclear Information System (INIS)

    'The specific fundamental chemical objectives of this project are to: (1) study the chemical speciation of Sr and Ln ions in basic media formed in aqueous solutions with and without classical chelation agents (e.g., EDTA, polyphosphates, and organic carboxylates); (2) prepare pyridine N-oxide phosphonate and phosphonoacetate chelators of the types 1--3 and characterize their ionization properties by titrimetric techniques; (3) study the interactions of 5--7 with soluble oxide-hydroxide metallate species and higher molecular weight sols, gels and precipitates containing Sr and Ln ions, as time permits, interactions with oxide-hydroxide metallates of U, Th, Ba, Al and Fe will also be studied; (4) study the interactions of newly designed phosphonate ligands with oxide-hydroxide metallate species; (5) transfer the fundamental coordination chemistry revealed here to research groups at LANL and PNNL that will utilize the results to improve tank waste treatment protocols.'

  14. Synthetic, structural, thermal and electrical properties of some transition metal polymeric chelates of bis(mercaptoacetamido)diaminobutane

    International Nuclear Information System (INIS)

    Polymeric chelates of bis(mercaptoacetamido)-1,4-diaminobutane (BMADB) with manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) ions have been synthesized and characterized by elemental analysis, magnetic moment, infrared, electronic spectra and thermal analysis. In the present investigation the ligand BMADB exhibits bis-bidentate character and coordinates symmetrically with metal through nitrogen of amino and sulfur mercapto groups. The thermogravimetric studies indicate a two stage decomposition and the presence of water molecules. Thermal data have been analysed by Freeman-Carroll and Sharp-Wentworth methods and various kinetic and thermodynamic parameters have also be evaluated. Comparable values of parameters indicate common decomposition reaction mode of all chelates. Their d.c. electrical conductivity in pellet form over a wide range of temperatures have also been studied. (author)

  15. Chelated Ruthenium Catalysts for Z-Selective Olefin Metathesis

    OpenAIRE

    Endo, Koji; Grubbs, Robert H.

    2011-01-01

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

  16. Μethods of iron chelation therapy: a bibliographic review

    OpenAIRE

    Maria Agapiou; Elpida Georgiadi

    2012-01-01

    "Iron Chelation Therapy" is a term used to describe the procedure of removing excess iron from the body, which is applied after a total of approximately 20 blood transfusions or when serum ferritin levels rise above 1000 ng/ml. Aim: The purpose of the present paper is a retrospective search in bibliography, concerning the methods of iron chelation treatment for patients with hemochromatosis owing to their undergoing multiple blood transfusions. Method: The methology followed, included the sea...

  17. EDTA chelation therapy for cardiovascular disease: a systematic review

    OpenAIRE

    Wu Ping; Seely Dugald MR; Mills Edward J

    2005-01-01

    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 ...

  18. Clawing Back: Broadening the Notion of Metal Chelators in Medicine

    OpenAIRE

    Franz, Katherine J.

    2013-01-01

    The traditional notion of chelation therapy is the administration of a chemical agent to remove metals from the body. But formation of a metal-chelate can have biological ramifications that are much broader than metal elimination. Exploring these other possibilities could lead to pharmacological interventions that alter the concentration, distribution, or reactivity of metals in targeted ways for therapeutic benefit. This review highlights recent examples that showcase four general strategies...

  19. Antioxidant, Free Radical Scavenging and Metal Chelating Characteristics of Propolis

    OpenAIRE

    Hikmet Geckil; Burhan Ates; Gokhan Durmaz; Selim Erdogan; Ismet Yilmaz

    2005-01-01

    This study was undertaken to determine the reducing characteristics, metal chelating capability, anti-lipid peroxidative and antiradical properties of propolis compared to two widely used artificial antioxidants, Butylated Hydroxyanisole (BHA) and Butylated Hydroxytoluene (BHT). The water and ethanol extracts of propolis showed significantly a different degree of metal chelating, radical scavenging activity and reducing power. In general, ethanol extracts of propolis showed higher activity re...

  20. Hydrogen peroxide- metals- chelating agents; interactions and analytical techniques

    OpenAIRE

    Rämö, J.

    2003-01-01

    Abstract Information about interactions among metals, hydrogen peroxide and chelating agents is needed to develop environmental technology and the operating efficiency of modern elemental chlorine free and total chlorine free bleaching processes. The work presented here focused on the properties of metal chelates and corrosion of titanium in an alkaline hydrogen peroxide solution. A comparative study between three rapid analysis methods, ICP-AES, XRF and ISE, was performed in pulp matrix a...

  1. Iron chelators ICL670 and 311 inhibit HIV-1 transcription

    International Nuclear Information System (INIS)

    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

  2. Extraction of metals using supercritical fluid and chelate forming ligand

    International Nuclear Information System (INIS)

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

  3. THE STUDIES ON CHELATING FIBER V.ADSORPTION BEHAVIOR OF Au3+ ONTO CHELATING FIBER CONTAINING AMIDOXIME GROUPS

    Institute of Scientific and Technical Information of China (English)

    LINWeiping; LUYun; 等

    1992-01-01

    The adsorption behavior of ionic gold onto chelating fiber containing amidoxime groups was investigated. The chelating fiber presents high adsorption capacity for ionic gold Au3+(up to 626mg/g,when the content of amidoxime group reaches 7.59mmol/g),and possesses the ability to reduce the Au3+ into metallic gold,In the redox process,the amidoxime group is oxidized into carboxyl group.

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

    OpenAIRE

    Andersen, Ole; Aaseth, Jan

    2002-01-01

    Successful in vivo chelation treatment of metal intoxication requires that a significant fraction of the administered chelator in fact chelate the toxic metal. This depends on metal, chelator, and organism-related factors (e.g., ionic diameter, ring size and deformability, hardness/softness of electron donors and acceptors, route of administration, bioavailability, metabolism, organ and intra/extracellular compartmentalization, and excretion). In vivo chelation is not necessarily an equilibri...

  5. D-Penicillamine tripodal derivatives as efficient copper(I) chelators.

    Science.gov (United States)

    Jullien, Anne-Solène; Gateau, Christelle; Lebrun, Colette; Kieffer, Isabelle; Testemale, Denis; Delangle, Pascale

    2014-05-19

    New tripodal metal-chelating agents derived from nitrilotriacetic acid (NTA) and extended by three unnatural amino acids D-penicillamine (D-Pen) are presented. D-Pen is actually the drug most extensively used to treat copper (Cu) overload in Wilson's disease and as such is a very attractive building block for the design of chelating agents. D-Pen is also a bulkier analogue of cysteine, with the β-methylene hydrogen atoms replaced by larger methyl groups. The hindrance of the gem-dimethyl group close to the thiol functions is demonstrated to influence the speciation and stability of the metal complexes. The ligands L(4) (ester) and L(5) (amide) were obtained from NTA and commercial D-Pen synthons in four and five steps with overall yields of 14 and 24%, respectively. Their ability to bind Cu(I), thanks to their three thiolate functions, has been investigated using both spectroscopic and analytical methods. UV, CD, and NMR spectroscopy and mass spectrometry evidence the formation of two Cu(I) complexes with L(5): the mononuclear complex CuL(5) and one cluster (Cu2L(5))2. In contrast, the bulkier ethyl ester derivative L(4) cannot accommodate the mononuclear complex in solution and thus forms exclusively the cluster (Cu2L(4))2. Cu K-edge X-ray absorption spectroscopy (XAS and EXAFS) confirms that Cu(I) is bound in trigonal-planar sulfur-only environments in all of these complexes with Cu- - -S distances ranging from 2.22 to 2.23 Å. Such C3-symmetric CuS3 cores are coordination modes frequently adopted in Cu(I) proteins such as metallothioneins. These two ligands bind Cu(I) tightly and selectively, which makes them promising chelators for intracellular copper detoxification in vivo. PMID:24766067

  6. F-Element ion chelation in highly basic media. 1998 annual progress report

    International Nuclear Information System (INIS)

    'A large percentage of high-level radioactive waste (HLW) produced in the DOE complex over the last thirty years temporarily resides in storage tanks maintained at highly basic pH. The final permanent waste remediation plan will probably require that liquid and solid fractions be chemically treated in order to partition and concentrate the dominate hazardous emitters from the bulk of the waste. This is no small task. Indeed, there does not exist a well developed molecular chemistry knowledge base to guide the development of suitable separations for actinide and fission products present in the strongly basic media. The goal of this project is to undertake fundamental studies of the coordination chemistry of f-element ions and their species formed in basic aqueous solutions containing common waste treatment ions (e.g., NO3-, CO32-, organic carboxylates, and EDTA), as well as new waste scrubbing chelators produced in this study.'

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

    International Nuclear Information System (INIS)

    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 370C, 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

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

    International Nuclear Information System (INIS)

    Albumin microspheres have been synthesized eith 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 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 hr. Since labeling is by chelation, the microspheres may also be tagged with other metallic radionuclides

  9. Antioxidant, Free Radical Scavenging and Metal Chelating Characteristics of Propolis

    Directory of Open Access Journals (Sweden)

    Hikmet Geckil

    2005-01-01

    Full Text Available This study was undertaken to determine the reducing characteristics, metal chelating capability, anti-lipid peroxidative and antiradical properties of propolis compared to two widely used artificial antioxidants, Butylated Hydroxyanisole (BHA and Butylated Hydroxytoluene (BHT. The water and ethanol extracts of propolis showed significantly a different degree of metal chelating, radical scavenging activity and reducing power. In general, ethanol extracts of propolis showed higher activity regarding these parameters. Synthetic antioxidants showed better activities than both propolis extracts for antioxidant properties, utilizing a -carotene bleaching method. At higher concentrations, the reducing power of ethanol extract of propolis was similar to that of artificial antioxidants. The metal chelating activity of both water and ethanol extracts of propolis was comparable to that of EDTA and significantly higher than both BHA and BHT.

  10. Encapsulation and retention of chelated-copper inside hydrophobic nanoparticles

    DEFF Research Database (Denmark)

    Hervella, Pablo; Parra, Elisa; Needham, David

    2016-01-01

    Trioleate (Triolein) with copper using the hydrophobic chelator Octaethyl porphyrin (OEP). RESEARCH PLAN AND METHODS: The research plan for this study was to (1) Formulate nanoparticles and control nanoparticle size using a modification of the solvent injection technique, named fast ethanol injection; (2......) Chelate copper into the octaethyl porphyrin; (3) Encapsulate OEP-Cu in nanoparticles: the encapsulation efficiency of copper into liquid nanoparticles (LNP), solid nanoparticles (SNP) and phospholipid liposomes (PL) was evaluated by UV-Vis and atomic absorption spectroscopy; (4) Retain the encapsulated...... minimum value for the particle diameter of ∼30nm was measured. (2) Copper was chelated by OEP in a 1:1mol ratio with an association constant of 2.57×10(5)M(-1). (3) The diameter of the nanoparticles was not significantly affected by the presence of OEP or OEP-Cu. The percentage of encapsulation of copper...

  11. Timing of early chelating therapy for acute uranium intoxication

    International Nuclear Information System (INIS)

    Rats were treated with DTPA and H-73-10 intraperitoneal injections 15 minutes to 4 days after acute uranium intoxication. The mortality and changes in body weight, kidney weight, renal histology and histochemistry were investigated. The results show that the renal damage could be diminished significantly by chelating therapy started 15 minutes and 6 hours after urnium poisoning. Single large dose injection (1 g/kg weight) of H-73-10 yielded the best result, and daily 0.5 g/kg of H-73-10 injection for 5 days is the next, both are better than single injection of DTPA (1 g/kg body weight). One day after intoxication there was still some protective effect. On the contrary, if the chelating therapy started 2-4 days after urnium poisoning it would increase the renal damage and the mortality. This is of great value to the correct selection of timing of chelating therapy for uranium intoxication

  12. Extraction rate of metal ion by chelating agent

    International Nuclear Information System (INIS)

    In order to clarify the extraction mechanism of metal ion by a chelating agent, it is problematic to infer the mechanism on the basis of the dependence of the extraction rate upon the concentration of the agent. For this purpose, the information as follows is essential: (1) computation of physical chemistry constants of the chelating agent, (2) the reaction rate for chelate formation with the metal ion in the water phase and the mechanism, and (3) the measurement of the extraction rate by use of the apparatus for which the oil/water interface area and the interface-material transfer coefficient are known. It is then necessary to establish the design guidance of reaction field and separation field via the accumulation of the experimental results. (Mori, K.)

  13. Inositol hexa-phosphate: a potential chelating agent for uranium

    Energy Technology Data Exchange (ETDEWEB)

    Cebrian, D.; Tapia, A.; Real, A.; Morcillo, M.A. [Radiobiology Laboratory, Radiation Dosimetry Unit, Department of Environment, CIEMAT, Avda Complutense 22, 28040 Madrid (Spain)

    2007-07-01

    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)

  14. Inositol hexa-phosphate: a potential chelating agent for uranium

    International Nuclear Information System (INIS)

    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)

  15. Clinical monitoring and management of complications related to chelation therapy in patients with β-thalassemia.

    Science.gov (United States)

    Saliba, Antoine N; El Rassi, Fuad; Taher, Ali T

    2016-01-01

    Iron chelating agents - deferoxamine (DFO), deferiprone (DFP), and deferasirox (DFX) - are used to treat chronic iron overload in patients with β-thalassemia in an attempt to reduce morbidity and mortality related to siderosis. Each of the approved iron chelating agents has its own advantages over the others and also has its own risks, whether related to over-chelation or not. In this review, we briefly discuss the methods to monitor the efficacy of iron chelation therapy (ICT) and the evidence behind the use of each iron chelating agent. We also portray the risks and complications associated with each iron chelating agent and recommend strategies to manage adverse events. PMID:26613264

  16. Combinational chelation therapy abrogates lead-induced neurodegeneration in rats

    International Nuclear Information System (INIS)

    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.

  17. 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.

  18. Archetypes for actinide-specific chelating agents

    International Nuclear Information System (INIS)

    The complexes of uranium and thorium with monomeric hydroxamic acids can serve as archetypes for an optimized macrochelate designed for tetravalent actinides. The eight-coordinate complexes, Th(i-PrN(O)C(O)R)4, where R = tert-butyl or R = neopentyl, have been synthesized and their structures have been determined by x-ray diffraction. The bulky alkyl substituents impart remarkable volatility and hydrocarbon solubility to these complexes, and the steric interactions of these substituents largely determine the structures. When R = tert-butyl, the substituents occupy the corners of a tetrahedron and force the complex into a distorted cubic geometry with crystallographic S4 symmetry. Insertion of a methylene group between the carbonyl carbon and the tert-butyl group relaxes the steric requirements, and the coordination polyhedron of the neopentyl derivative is close to the mmmm isomer of the trigonal-faced dodecahedron. Uranium tetrachloride was quantitatively oxidized via an oxygen transfer reaction with two equivalents of N-phenylbenzohydroxamic acid anion (PBHA) in tetrahydrofuran (THF) to form UO2 Cl(PBHA)(THF)2 and benzanilide. The structure of the uranyl complex has been determined from x-ray diffraction data; the linear uranyl ion is surrounded by a planar pentagonal array composed of two hydroxamate oxygen atoms, a chloride ion and two THF oxygens, such that the chloride ion is opposite the hydroxamate group. That the THF and phenyl rings are twisted from this equatorial plane limits the molecular geometry to that of the C1 point group. Some aspects of the chemistry of hydroxamic acids and of their incorporation into molecules that may serve as precursors of tetravalent actinide specific sequestering agents have also been investigated

  19. Sequestering agent for uranyl chelation: new bi-naphtyl ligands

    International Nuclear Information System (INIS)

    The synthesis of phosphonate, sulfocatecholamide (CAMS) and hydroxy-pyridinone (HOPO) bi-naphtyl ligands is presented. Their binding abilities for uranyl cation were determined by UV spectrophotometry in aqueous media versus pH. These titrations showed that the efficiency of these chelating agents depends on the nature of the chelating group. Each ligand shows a more or less pronounced affinity towards uranium. While the bis-phosphonate compound did not show any affinity towards the uranyl ion, the BINHOPO derivative exhibits significant affinity at acidic and neutral pH while the BINCAMS is more efficient at basic pH. (authors)

  20. SEPARATION OF PLUTONIUM FROM LANTHANUM BY CHELATION-EXTRACTION

    Science.gov (United States)

    James, R.A.; Thompson, S.G.

    1958-12-01

    Plutonium can be separated from a mixture of plutonlum and lanthanum in which the lanthanum to plutonium molal ratio ls at least five by adding the ammonium salt of N-nitrosoarylhydroxylamine to an aqueous solution having a pH between about 3 and 0.2 and containing the plutonium in a valence state of at least +3, to form a plutonium chelate compound of N-nitrosoarylhydroxylamine. The plutonium chelate compound may be recovered from the solution by extracting with an immiscible organic solvent such as chloroform.

  1. Regularities in aluminium and indium chemisorption on chelating polymeric sorbents

    International Nuclear Information System (INIS)

    Complexation properties of synthesized polymer chelate sorbents: substituted of polystyrene-azo-pyrocatechol are investigated and correlations between pK'OH of functional groups of sorbents as well as pH50 values of chelation and constants of stability (lgKstab) are established for studying regularities of effect of structure and acid-base properties of functional groups of sorbents on the parameters of Al3+ and In3+ chemical sorption. Established correlations make it possible to predict the physicochemical parameters of sorbents and sorption of metal ions with the aim of separation and concentration of aluminium and indium micro account from the objects of different origin

  2. 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 or...

  3. Physiological response of Moringa oleifera to stigmasterol and chelated zinc

    OpenAIRE

    KARIMA GAMAL EL-DIN; IMAN MAHMOUD TALAAT; MOHAMED ABDEL-GHANY BEKHETA; ABDALLA EL-MOURSI

    2012-01-01

    El-Moursi A, Talaat IM, Bekheta MA, Gamal El-Din K. 2012. Physiological response of Moringa oleifera to stigmasterol and chelated zinc. Nusantara Bioscience 4: 118-123. Two pot experiments were carried out in the screen of the National Research Centre, Dokki, Giza, Egypt, during two successive seasons (2009/2010 and 2010/2011), respectively to study the effect of foliar spray with chelated zinc (100, 200 and 300 mg/L) and stigmasterol (50, 100 and 150 mg/L) on growth and chemical constituents...

  4. 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.

  5. Limitations of Radar Coordinates

    OpenAIRE

    Bini, Donato; Lusanna, Luca; Mashhoon, Bahram

    2004-01-01

    The construction of a radar coordinate system about the world line of an observer is discussed. Radar coordinates for a hyperbolic observer as well as a uniformly rotating observer are described in detail. The utility of the notion of radar distance and the admissibility of radar coordinates are investigated. Our results provide a critical assessment of the physical significance of radar coordinates.

  6. Chelating regularities in the series of chelating polymer sorbents and their complexes with vanadium, manganese, and chromium

    International Nuclear Information System (INIS)

    Physicochemical properties of new synthesized polymer chelation sorbents - substituted polystyrene-azo-salicylic acid are investigated. Correlations between pKCOOH of functional groups of sorbents with chelation pH50 and vanadium, manganese and chromium lgstab are established with the aim of studying interactions in the ion of element - sorbent system. Established correlations suggest physicochemical properties of the sorbents and sorption parameters of cations of metals with the aim of concentration and separation of V(5), Mn(2) and Cr(3) microamounts from natural and technical objects including environmental ones

  7. The magnesium chelation step in chlorophyll biosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Weinstein, J.D.

    1991-01-01

    The biogenesis of energy transducing membranes requires the coordinate synthesis of prosthetic groups, proteins and lipids. Two of the major prosthetic groups, chlorophyll and heme, share a common biosynthetic pathway that diverges at the point of metal insertion into protoporphyrin IX. Insertion of iron leads to heme, while insertion of magnesium leads to chlorophyll. The Mg-chelatase from intact cucumber chloroplasts has been characterized with regard to substrate specificity, regulation, ATP requirement, and a requirement for intact chloroplasts. Mg-chelatase was isolated from maize, barley and peas and characterized in order to circumvent the intact chloroplast requirement of cucumber Mg-chelatase. Pea Mg-chelatase activity is higher than cucumber Mg-chelatase activity, and lacks the requirement for intact chloroplasts. Studies on isolated pea Mg-chelatase have shown more cofactors are required for the reaction than are seen with ferrochelatase, indicating a greater opportunity for regulatory control of this pathway. Two of the cofactors are proteins, and there appears to be a requirement for a protease-sensitive component which is outside the outer envelope. We are developing a continuous spectrophotometric assay for Mg-chelatase activity, and an assay for free heme which has shown heme efflux from intact chloroplasts. 18 refs. (MHB)

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

    International Nuclear Information System (INIS)

    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)

  9. Questions and Answers: The NIH Trial of EDTA Chelation Therapy for Coronary Heart Disease

    Science.gov (United States)

    ... NIH Trial of EDTA Chelation Therapy for Coronary Heart Disease Preliminary results from the Trial to Assess Chelation ... and complete it. Study Background What is coronary heart disease? Coronary heart disease (CHD) is the most common ...

  10. Iron chelating active packaging: Influence of competing ions and pH value on effectiveness of soluble and immobilized hydroxamate chelators.

    Science.gov (United States)

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

    2016-04-01

    Many packaged foods utilize synthetic chelators (e.g. ethylenediaminetetraacetic acid, EDTA) to inhibit iron-promoted oxidation or microbial growth which would result in quality loss. To address consumer demands for all natural products, we have previously developed a non-migratory iron chelating active packaging material by covalent immobilization of polyhydroxamate and demonstrated its efficacy in delaying lipid oxidation. Herein, we demonstrate the ability of this hydroxamate-functionalized iron chelating active packaging to retain iron chelating capacity; even in the presence of competing ions common in food. Both immobilized and soluble hydroxamate chelators retained iron chelating capacity in the presence of calcium, magnesium, and sodium competing ions, although at pH 5.0 the presence of calcium reduced immobilized hydroxamate iron chelation. A strong correlation was found between colorimetric and mass spectral analysis of iron chelation by the chelating packaging material. Such chelating active packaging may support reducing additive use in product formulations, while retaining quality and shelf life. PMID:26593563

  11. MDs remain sceptical as chelation therapy goes mainstream in Saskatchewan

    OpenAIRE

    Oliver, M.

    1997-01-01

    The College of Physicians and Surgeons of Saskatchewan recently agreed to allow physicians to administer chelation therapy. Supporters, relying on anecdotal evidence, say it works wonders in overcoming heart disease, but many physicians remain profoundly sceptical. In Saskatchewan, the college decision has proved popular with patients but has drawn an angry reaction from doctors.

  12. Role of Chelation During Pregnancy in the Lead Poisoned Patient

    OpenAIRE

    Brown, Mary Jean

    2013-01-01

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

  13. Chelation And Extraction Of Metals For GC-MS Analysis

    Science.gov (United States)

    Sinha, Mahadeva P.

    1995-01-01

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

  14. Sequestration of zinc oxide by fimbrial designer chelators

    DEFF Research Database (Denmark)

    Kjærgaard, Kristian; Sørensen, Jack K; Schembri, Mark; Klemm, Per

    2000-01-01

    Type 1 fimbriae are surface organelles of Escherichia coli. By engineering a structural component of the fimbriae, FimH, to display a random peptide library, we were able to isolate metal-chelating bacteria. A library consisting of 4 x 10(7) independent clones was screened for binding to Zn...

  15. Reversal of haemochromatotic cardiomyopathy in beta thalassaemia by chelation therapy.

    OpenAIRE

    Politi, A; M. Sticca; Galli, M

    1995-01-01

    Haemochromatotic cardiomyopathy is the main cause of morbidity and mortality in patients with beta thalassaemia major. Once congestive heart failure develops most patients die in a few months. Congestive heart failure was reversed and echocardiographic findings were restored to normal in a 24 year old woman with beta thalassaemia who resumed treatment with chelation therapy (desferrioxamine).

  16. f-Element Ion Chelation in Highly Basic Media

    International Nuclear Information System (INIS)

    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

  17. Commentary on the Abuse of Metal Chelation Therapy in Patients with Autism Spectrum Disorders

    OpenAIRE

    Brent, Jeffrey

    2013-01-01

    Approximately half a million patients with autism spectrum disorders are subjected to chelation therapy in the US annually. The overwhelming majority of such cases are chelated for non-accepted medical indications. These patients may seek evaluation when a urine sample is assayed after the administration of a chelating agent and the values obtained have been improperly compared to references ranges for non-chelated urines, causing falsely elevated results. Legitimate practitioners confronted ...

  18. Chelator induced phytoextraction and in situ soil washing of Cu

    International Nuclear Information System (INIS)

    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

  19. Chelator induced phytoextraction and in situ soil washing of Cu

    Energy Technology Data Exchange (ETDEWEB)

    Kos, Bostjan; Lestan, Domen

    2004-11-01

    In a soil column experiment, we investigated the effect of 5 mmol kg{sup -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{sup -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{sup -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{sup -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.

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

    International Nuclear Information System (INIS)

    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 (H4EDTA) 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)

  1. Investigation of the chelation effect on the voltammetric behaviour of selected metals

    International Nuclear Information System (INIS)

    Iron, cadmium, aluminum and chromium could be easily determined by voltammetric methods. The chelation behaviour of chelating agents like hydroxyquinoline, NaDEDC, cupferron etc. have been investigated on the voltammetric behavior of these metals. The results were compared with the spectro fluorimetric investigation of these metal chelates and a relation between voltammetric and fluorimetric behaviour have been established. (author)

  2. EDTA Chelation Therapy, Without Added Vitamin C, Decreases Oxidative DNA Damage and Lipid Peroxidation

    Science.gov (United States)

    Chelation therapy is thought to not only remove contaminating metals, but also to decrease free radical production. However, in standard EDTA chelation therapy high doses of vitamin C with potential prooxidant effects are often added to the chelation solution. We demonstrated previously that the in...

  3. Examining the fixation kinetics of chelated and non-chelated copper micronutrient and the applications to micronutrient management in semi-arid alkaline soils

    OpenAIRE

    T. K. Udeigwe; M. B. Eichmann; Menkiti, M. C.

    2015-01-01

    The relationship between the deficiency of a nutrient in plants and its total concentration in the soil is complex. This study examined and compared the fixation and fixation kinetics of copper (Cu) in chelated (Ethylene diamine tetraacetic acid, EDTA) and non-chelated mixed systems of micronutrients in the semi-arid soils of the Southern High Plains, US using findings from Cu extraction studies and kinetic models. Approximately, 22 % more Cu was fixed in the non-chelated system with...

  4. Examining the fixation kinetics of chelated and non-chelated copper and the applications to micronutrient management in semiarid alkaline soils

    Science.gov (United States)

    Udeigwe, T. K.; Eichmann, M. B.; Menkiti, M. C.; Kusi, N. Y. O.

    2016-02-01

    This study examined and compared the fixation and fixation kinetics of copper (Cu) in chelated (ethylene diamine tetraacetic acid, EDTA) and non-chelated mixed systems of micronutrients in the semiarid soils of the Southern High Plains, USA, using findings from Cu extraction studies and kinetic models. Approximately, 22 % more Cu was fixed in the non-chelated system compared to the chelated within the first 14 days with only 7 % difference between the two systems by day 90. Findings suggest a decrease in the effectiveness of chelated micronutrients over time, highlighting the significance of timing even when chelated micronutrients are used. The strengths of the relationship of change in available Cu with respect to other micronutrients (iron (Fe), manganese (Mn), and zinc (Zn)) were higher in the non-chelated system (R2: 0.68-0.94), compared to the chelated (R2: 0.42-0.81), with slopes of 0.40 (Cu-Fe), 0.31 (Cu-Mn), and 1.04 (Cu-Zn) in the non-chelated system and 0.26 (Cu-Fe), 0.22 (Cu-Mn), and 0.90 (Cu-Zn) in the chelated system. Reduction in the amount of available Cu was best described by the power function model (R2 = 0.91, SE = 0.081) in the non-chelated system and second-order model (R2 = 0.95, SE = 0.010) in the chelated system. The applications generated from this study could be used as tools for improved micronutrient management and also provide baseline data for future work in other semiarid/arid alkaline soils of the world. Findings are also more applicable to field settings, an improvement over related previous studies.

  5. Synthesis of New Bis(3-hydroxy-4-pyridinone) Ligands as Chelating Agents for Uranyl Complexation

    OpenAIRE

    Bo Jin; Rongzong Zheng; Rufang Peng; Shijin Chu

    2016-01-01

    Five new bis(3-hydroxy-4-pyridinone) tetradentate chelators were synthesized in this study. The structures of these tetradentate chelators were characterized by 1H-NMR, 13C-NMR, FT-IR, UV-vis, and mass spectral analyses. The binding abilities of these tetradentate chelators for uranyl ion at pH 7.4 were also determined by UV spectrophotometry in aqueous media. Results showed that the efficiencies of these chelating agents are dependent on the linker length. Ligand 4b is the best chelator and ...

  6. Synthesis of New Bis(3-hydroxy-4-pyridinone) Ligands as Chelating Agents for Uranyl Complexation.

    Science.gov (United States)

    Jin, Bo; Zheng, Rongzong; Peng, Rufang; Chu, Shijin

    2016-01-01

    Five new bis(3-hydroxy-4-pyridinone) tetradentate chelators were synthesized in this study. The structures of these tetradentate chelators were characterized by ¹H-NMR, (13)C-NMR, FT-IR, UV-vis, and mass spectral analyses. The binding abilities of these tetradentate chelators for uranyl ion at pH 7.4 were also determined by UV spectrophotometry in aqueous media. Results showed that the efficiencies of these chelating agents are dependent on the linker length. Ligand 4b is the best chelator and suitable for further studies. PMID:27005598

  7. Cationic zinc (II) dimers and one dimensional coordination polymer from ionic carboxylic acid

    Indian Academy of Sciences (India)

    Paladugu Suresh; Ganesan Prabusankar

    2014-09-01

    A rare example of chelating two tetra cationic paddle-wheel zinc dimers were synthesized from the reaction between flexible imidazolium carboxylate (LH2Br2) and corresponding zinc precursors. A zinc coordination polymer was synthesised by treating in situ generation of 2 in the presence of 4,4′-bipyridine. These new molecules, dimers and polymer, were characterized by FT-IR, NMR, UV-vis, fluorescent and single crystal X-ray diffraction techniques. Zinc polymer is the first example of 1D coordination polymer constructed by tetra cationic zinc dimer as a secondary building unit in coordination polymer.

  8. Coordination and Cooperation

    OpenAIRE

    Janssen, Maarten

    2003-01-01

    textabstractThis comment makes four related points. First, explaining coordination is different from explaining cooperation. Second, solving the coordination problem is more important for the theory of games than solving the cooperation problem. Third, a version of the Principle of Coordination can be rationalized on individualistic grounds. Finally, psychological game theory should consider how players perceive their gaming situation. ---------------------------------------------------------...

  9. A Coordination Theory

    OpenAIRE

    J. Foss, Nicolai

    2009-01-01

    Important aspects of leadership behavior can be rendered intelligible through a focus on coordination games. The concept of common knowledge is shown to be particularly important to understanding leadership. Thus, leaders may establish common knowledge conditions and assist the coordination of strategies in this way, or make decisions in situations where coordination problems persist in spite of common knowledge.

  10. Quantifying linguistic coordination

    DEFF Research Database (Denmark)

    Fusaroli, Riccardo; Tylén, Kristian

    task (Bahrami et al 2010, Fusaroli et al. 2012) we extend to linguistic coordination dynamical measures of recurrence employed in the analysis of sensorimotor coordination (such as heart-rate (Konvalinka et al 2011), postural sway (Shockley 2005) and eye-movements (Dale, Richardson and Kirkham 2012...... linguistic coordination and their effects at a fine-degree....

  11. A comparison study of radiostrontium chelation with chitin, chitosan, EDTA and DTPA

    International Nuclear Information System (INIS)

    Chitin and chitosan are nontoxic natural chelators that chelate radiostrontium effectively. The purpose of this study was to compare radiostrontium chelation of chitin and chitosan with that of well known chemical chelators, namely EDTA and DTPA. The chelaton rates of chitin, chitosan, EDTA and DTPA were compared using a column chromatography method (Sephadex G-25M, Sweden). Three kinds of chitins and four kinds of chitosans were used. All of them were water soluble. Phosphated chitosan showed the highest chelation yield of 97% at pH 7. All of chitins, chitosans, EDTA and DTPA showed chelation yield of more than 90% independent of varing pH level. Chitin and chitosan have similar chelation rate as compared with EDTA and DTPA

  12. Conformational study of aromatic ketones: chemical shift reagents: uranium chelates

    International Nuclear Information System (INIS)

    A series of benzophenones, 2-benzoyl thiophenes and 2-benzoyl pyridines, all substituted at the benzene ring by an amino acid chain, have been synthesised with the object of examining to what extent the site of the aminoacid chain and the site and nature of the other substituents modify the electronic structure of the molecule and the orientation of each ring with respect to the plane of the carbonyl group. In the second part a study of paramagnetic cations, in particular of uranium, which is able to form stable chelates with beta-diketones was carried out to study their complexing power. The chelates studied are the (hexafluoropentanedionate)4U, the (heptafluorodimethyloctanedionate)4U and the (trifluorophenylbutanedionate)4U

  13. Doping of graphene nanomeshes by ion-chelation

    Science.gov (United States)

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

    2013-03-01

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

  14. Chelation studies involving decontamination of light lanthanides by polyaminopolycarboxylic

    International Nuclear Information System (INIS)

    The present thesis constitutes chelation studies involving decontamination of light lanthanides, cobalt , and uranium with 2,2-bis-acryloyliminomethylene- acid (BAETA) using the spectrophotometric method. the work carried out aimed to clear up the effectiveness of BAETA as a decontaminating agent for radioactive nuclides from human body . the thesis includes a general introduction , outlines the aim of work and contains three main chapters . the results of the work are discussed at the end of the thesis. the first chapter deals with a comprehensive survey of the relevant literature. this includes the metabolism and toxicity of cerium, uranium, cobalt and Ln+3 elements, general methodologies of internal decontamination, choice and effectiveness of chelating agents

  15. 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.

  16. Improved paramagnetic chelate for molecular imaging with MRI

    International Nuclear Information System (INIS)

    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

  17. MULTIDENTATE TEREPHTHALAMIDATE AND HYDROXYPYRIDONATE LIGANDS: TOWARDS NEW ORALLY ACTIVE CHELATORS

    Energy Technology Data Exchange (ETDEWEB)

    Abergel, Rebecca J.; Raymond, Kenneth N.

    2011-07-13

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

  18. Treatment of some radioactive wastes by using new chelating membranes

    International Nuclear Information System (INIS)

    The preparation of chelating membranes containing nitrile and carboxylic acid as functional groups was investigated. The modification of such membranes by chemical treatments to produce significant changes in their properties was studied. This modification results in a higher rate of exchange and higher capacity. The applicability of such modified membranes in the removal of Co-60 and Cs-137 from their wastes were tested. The dependence of these radioactive nuclides uptake on the time and degree of grafting for H CI-, NH2OH-and KOH-treated membranes was investigated. It was found that the adsorption rate and capacity were higher for KOH-treated membrane than those for the NH2OH and H CI treated ones. The prepared grafted membranes have a good affinity towards the adsorption or chelation with Co-60 and Cs-137. This result may make such prepared materials acceptable for practicable use in some radioactive waste treatments and recovery

  19. Multidentate Terephthalamidate And Hydroxypyridonate Ligands: Towards New Orally Active Chelators

    International Nuclear Information System (INIS)

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

  20. Pathophysiological and clinical aspects of iron chelation therapy in MDS.

    Science.gov (United States)

    Gattermann, Norbert

    2012-01-01

    The majority of patients with myelodysplastic syndromes (MDS) become transfusion-dependent during the course of disease and may thus develop transfusional iron overload. As a further contributor to iron overload there is increased absorption of dietary iron from the gut, as a consequence of ineffective erythropoiesis. Compared with thalassemia, it is less clear how frequent patients with MDS develop clinical complications of iron overload, and whether the accumulation of iron shortens their survival. This review aims to summarize our current knowledge of the detrimental effects of transfusional iron overload in MDS, point out the risks associated with iron-induced oxidative stress, describe the tools available for diagnosing iron overload, indicate the treatment options with currently available iron chelators, and discuss the measurement of labile plasma iron (LPI) as a tool to monitor the efficacy of iron chelation therapy. PMID:22571702

  1. Toxicological studies of a new chelating agent 8102

    International Nuclear Information System (INIS)

    The results of toxicological studies of a new chelating agent 8102 in different kinds of animals (mice, rats, rabbits and dogs) were reported. The results show that for mice, LD50 is 782 +- 21 mg/kg (i.v) and 3.17 +- 0.06 g/kg (i.m), and for rats, LD50 is 478 +- 15 mg/kg (i.v) and 3.04 +- 0.08 g/kg (i.m). In subacute experiments for dogs, the agent 8102 in doses of 50, 100, 150 mg(kg.day) was injected i.m. and for control group 0.9% saline was injected i.m.. Treatment was continued for 30 days. In pathological and clinical chemical analysis no essential change was observed. The experimental results suggest that the toxicity of this new chelating agent 8102 is low

  2. Meta-analysis of the safety of iron chelating agents

    OpenAIRE

    Li, Niya; 李妮婭

    2014-01-01

    Background: Thalassaemia is a genetic disorder disease, one of the most clinically relevant haemoglobinopathies in paediatric population. It interferes with the synthesis of haemoglobin chain. For the sake of maintaining the serum haemoglobin at a normal level, regular blood cell transfusion is required to the patients with thalassaemia. In general, patients with thalassaemia are often diagnosed at an early age and need to take a life-long iron chelating therapy to prevent the multi-organ...

  3. CHELATION THERAPY FOR IRON OVERLOAD: NURSING PRACTICE IMPLICATIONS

    OpenAIRE

    Eckes, Ellen J.

    2011-01-01

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

  4. Chelate-Assisted Heavy Metal Movement Through the Root Zone

    Science.gov (United States)

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

    2001-12-01

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

  5. Self-assembled polymeric chelate nanoparticles as potential theranostic agents

    Czech Academy of Sciences Publication Activity Database

    Škodová, Michaela; Černoch, Peter; Štěpánek, Petr; Chánová, Eliška; Kučka, Jan; Kálalová, Zuzana; Kaňková, Dana; Hrubý, Martin

    2012-01-01

    Roč. 13, č. 18 (2012), s. 4244-4250. ISSN 1439-4235 R&D Projects: GA ČR GPP207/10/P054; GA ČR GA202/09/2078; GA ČR GAP304/12/0950 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : chelates * nanoparticles * polymers Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.349, year: 2012

  6. Decontamination of process equipment using recyclable chelating solvent

    Energy Technology Data Exchange (ETDEWEB)

    Jevec, J.; Lenore, C.; Ulbricht, S. [Babcock & Wilcox, Co., R& DD, Alliance, OH (United States)

    1995-10-01

    The Department of Energy (DOE) is now faced with the task of meeting decontamination and decommissioning obligations at numerous facilities by the year 2019. Due to the tremendous volume of material involved, innovative decontamination technologies are being sought that can reduce the volumes of contaminated waste materials and secondary wastes requiring disposal. This report describes the results of the performance testing of chelates and solvents for the dissolution of uranium.

  7. Examining the fixation kinetics of chelated and non-chelated copper micronutrient and the applications to micronutrient management in semi-arid alkaline soils

    Science.gov (United States)

    Udeigwe, T. K.; Eichmann, M. B.; Menkiti, M. C.

    2015-10-01

    The relationship between the deficiency of a nutrient in plants and its total concentration in the soil is complex. This study examined and compared the fixation and fixation kinetics of copper (Cu) in chelated (Ethylene diamine tetraacetic acid, EDTA) and non-chelated mixed systems of micronutrients in the semi-arid soils of the Southern High Plains, US using findings from Cu extraction studies and kinetic models. Approximately, 22 % more Cu was fixed in the non-chelated system within the first 14 days with only 7 % difference between the two systems by day 90. Findings suggest a decrease in the effectiveness of chelated micronutrient over time, highlighting the significance of timing even when chelated micronutrients are applied. The strengths of the relationship of change in available Cu with respect to other micronutrients [iron (Fe), manganese (Mn), and zinc (Zn)] were higher in the non-chelated system (R2: 0.68-0.94), compared to the chelated (R2: 0.42-0.81) with slopes of 0.40 (Cu-Fe), 0.31 (Cu-Mn), and 1.04 (Cu-Zn) in the non-chelated system and 0.26 (Cu-Fe), 0.22 (Cu-Mn), and 0.90 (Cu-Zn) in the chelated. Reduction in the amount of available Cu was best described by the power function model (R2 = 0.91, SE = 0.081) in the non-chelated system and second order model (R2 = 0.95, SE = 0.010) in the chelated system. The applications generated from this study could be used as tools for improved micronutrient management and also provide baseline data for future work in other semi-arid/arid alkaline soils of the world. Findings are also more applicable to field settings, an improvement over related previous studies.

  8. Adventures in Coordinate Space

    Science.gov (United States)

    Chambers, J. E.

    2003-08-01

    A variety of coordinate systems have been used to study the N-body problem for cases involving a dominant central mass. These include the traditional Keplerian orbital elements and the canonical Delaunay variables, which both incorporate conserved quantities of the two-body problem. Recently, Cartesian coordinate systems have returned to favour with the rise of mixed-variable symplectic integrators, since these coordinates prove to be more efficient than using orbital elements. Three sets of canonical Cartesian coordinates are well known, each with its own advantages and disadvantages. Inertial coordinates (which include barycentric coordinates as a special case) are the simplest and easiest to implement. However, they suffer from the disadvantage that the motion of the central body must be calculated explicitly, leading to relatively large errors in general. Jacobi coordinates overcome this problem by replacing the coordinates and momenta of the central body with those of the system as a whole, so that momentum is conserved exactly. This leads to substantial improvements in accuracy, but has the disadvantage that every object is treated differently, and interactions between each pair of bodies are now expressed in a complicated manner involving the coordinates of many bodies. Canonical heliocentric coordinates (also known as democratic heliocentric coordinates) treat all bodies equally, and conserve the centre of mass motion, but at the cost of introducing momentum cross terms into the kinetic energy. This complicates the development of higher order symplectic integrators and symplectic correctors, as well as the development of methods used to resolve close encounters with the central body. Here I will re-examine the set of possible canonical Cartesian coordinate systems to determine if it is possible to (a) conserve the centre of mass motion, (b) treat all bodies equally, and (c) eliminate the momentum cross terms. I will demonstrate that this is indeed possible

  9. Tumor targeting of radiolabeled antibodies using HYNIC chelate

    International Nuclear Information System (INIS)

    There is an increasing interest in the use of labeled antibodies for diagnosis of cancers as well as for therapy. Various radiolabeling methods have been used in order to obtain better tumor specific targeting for detection and therapy. It was generally used to tumor targeted immunotherapy and immunodetection that lym-1, mouse monoclonal antibody, was specific binding to surface antigen of Raji. The 3E8 antibody was produced from humanized anti-TAG-72 monoclonal antibody (AKA) by amino acid change in 95-99 residues of heavy chain complementary determinant regions (HCDRs) 3 using phage displayed library technology. In this study, we are investigating the usefulness of HYNIC chelate as a bifunctional chelating agent in radioimmunodetecton of tumor. Two types of antibodies, Lym-1 and 3E8, were used for the conjugation with HYNIC chelate. Lym-1 and 3E8 are specific antibodies to surface antigen of Non-Hogkin's lymphoma and TAG-72 antigen of colorectal carcinoma, respectively. We prepare HYNIC-antibody conjugates, determine radiolabeling yield with 99mTc and evaluate tumor targeting in tumor bearing nude mice model

  10. Effectiveness of chelation therapy with time after acute uranium intoxication

    International Nuclear Information System (INIS)

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

  11. High precision isotopic ratio analysis of volatile metal chelates

    International Nuclear Information System (INIS)

    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 50Cr, 60Ni, and 65Cu isotopes covering the range 0.1-1010.7 at. % excess. A separate multiple isotope calibration curve was similarly prepared using enriched 60Ni (0.02-2.15 at. % excess) and 62Ni (0.23-18.5 at. % excess). The samples were analyzed by GC/CI/MS. Human plasma, containing enriched 26Mg and 44Ca, was analyzed by EI/MS. 1 figure, 5 tables

  12. In vitro test system for evaluating the effectiveness of chelators

    International Nuclear Information System (INIS)

    A procedure has been devised to test in vitro the relative effectiveness of chelating agents for the elimination of radiotoxins from specified, in vivo labeled endogenous ligands. The report describes the elimination of 239Pu from liver homogenates by various chelating agents. The effectivity of a homologous series of polyaminocarboxylic acids (PACA's) was compared to that of certain derivatives containing a straight alkyl group. The effectiveness of these lipophilic PACA's appears to depend on the chain length of the substituent. Lipophilic chelons were more effective in chelating 239Pu than unsubstituted PACA's. Combination of EDTA or DTPA with a number of oligodentate complexing agents were also tested. With EDTA, the removal of Pu was enhanced by p-aminosalicylic acid (PAS), Desferioxamine B (DFOA) and strongly enhanced by 4,5-Dihydroxy-m-benzenedisulfonic acid (Tiron). Only DFOA showed enhanced removal with DTPA. The different behavior of the mixed ligand treatments can be explained by either formation of binary complexes or action on different biological Pu-pools

  13. Hydroxyurea could be a good clinically relevant iron chelator.

    Directory of Open Access Journals (Sweden)

    Khushnooma Italia

    Full Text Available Our previous study showed a reduction in serum ferritin of β-thalassemia patients on hydroxyurea therapy. Here we aimed to evaluate the efficacy of hydroxyurea alone and in combination with most widely used iron chelators like deferiprone and deferasirox for reducing iron from experimentally iron overloaded mice. 70 BALB/c mice received intraperitonial injections of iron-sucrose. The mice were then divided into 8 groups and were orally given hydroxyurea, deferiprone or deferasirox alone and their combinations for 4 months. CBC, serum-ferritin, TBARS, sTfr and hepcidin were evaluated before and after iron overload and subsequently after 4 months of drug therapy. All animals were then killed. Iron staining of the heart and liver tissue was done using Perl's Prussian Blue stain. Dry weight of iron in the heart and liver was determined by atomic absorption spectrometry. Increased serum-ferritin, TBARS, hepcidin and dry weight of iron in the liver and heart showed a significant reduction in groups treated with iron chelators with maximum reduction in the group treated with a combination of deferiprone, deferasirox and hydroxyurea. Thus hydroxyurea proves its role in reducing iron from iron overloaded mice. The iron chelating effect of these drugs can also be increased if given in combination.

  14. Relationship between Coordination Structure and Biological Activity of Copper(Ⅱ) Nicotinate

    Institute of Scientific and Technical Information of China (English)

    CHEN Qiang; LI Qing-Lu; HUANG Zhi-Jian; LI Jian-Sheng; LI Ru

    2006-01-01

    The copper(Ⅱ) complexes of pyridine-3-carboxylic acid (nicotinic acid) and pyridine-2-carboxylic acid (isonicotinic acid) were synthesized, and their structures were characterized by elemental analysis, infrared spectrum, powder X-ray diffraction and so on. The results show that under experimental conditions, the ligands of synthesized copper nicotinate and copper isonicotinate are coordinated simultaneity with copper(Ⅱ) via the nitrogen of pyridine group and an oxygen of carboxylic acid group to form bidentate chelates. The crystal of copper nicotinate with two six-membered chelate rings belongs to monoclinic system, while that of copper isonicotinate having two five-membered chelate rings is of triclinic system. The tests show that the biological activities, such as the improvement of feed utilization, growth, anti-oxidation ability of organism and disease-resistant power, are different when copper nicotinate, copper inicotinate, copper-lysine chelate, copper-methionine chelate and copper sulphate are added in pig's feed, respectively. Due to its higher biological activity, less pollution and lower toxicity,copper nicotinate has wide potential applications as a feed additive.

  15. Stereoselective analysis of D and L dansyl amino acids as the mixed chelate copper(II) complexes by HPLC.

    Science.gov (United States)

    Lam, S

    1984-09-01

    This paper reviews the mixed chelation approach to resolution of the optical isomers of D and L dansyl amino acids by high performance liquid chromatography. The use of eluants containing Cu(II) complexes of L-proline, L-arginine, L-histidine, and L-histidine methyl ester effected the separation of many D and L amino acids, including those with aliphatic, polar, and aromatic substituents. The mechanism of separation, which is based on the preferential ternary complex formation of the analyte amino acid and the chiral chelate with Cu(II) in the mobile phase, is discussed. The stereoselectivity depends mainly on the different steric interactions between the alkyl side chains of the amino acid analytes and the chiral ligands coordinating around Cu(II), although such parameters as pH, temperature, organic modifier, and concentration of the chiral additive also affect the chromatographic separation. Among the chiral ligands studied, L-histidine methyl ester is unique in that it possesses both achiral selectivity for the dansyl amino acids and chiral selectivity for the respective D and L enantiomers. With a mobile phase gradient of acetonitrile in a buffer containing Cu(II) L-histidine methyl ester complex, a stereoselective procedure was devised for the analysis of D and L amino acid enantiomers, achieving the separation that the current amino acid analyzer could not perform. Finally, the use of the mixed chelation approach in two biomedical studies is described. In the first application, the histidine methyl ester gradient was adapted for analyzing amino acids in cerebrospinal fluid; in the second, an L-aspartame Cu(II) complex eluant was developed for measuring the urine concentration of D and L pipecolic acid (piperidine-2-carboxylic acid), a metabolite of lysine. PMID:6490790

  16. Mapping brains without coordinates

    OpenAIRE

    Kötter, Rolf; Wanke, Egon

    2005-01-01

    Brain mapping has evolved considerably over the last century. While most emphasis has been placed on coordinate-based spatial atlases, coordinate-independent parcellation-based mapping is an important technique for accessing the multitude of structural and functional data that have been reported from invasive experiments, and provides for flexible and efficient representations of information. Here, we provide an introduction to motivations, concepts, techniques and implications of coordinate-...

  17. Adaptive Coordinate Descent

    OpenAIRE

    Loshchilov, Ilya; Schoenauer, Marc; Sebag, Michèle

    2011-01-01

    Independence from the coordinate system is one source of efficiency and robustness for the Covariance Matrix Adaptation Evolution Strategy (CMA-ES). The recently proposed Adaptive Encoding (AE) procedure generalizes CMA-ES adaptive mechanism, and can be used together with any optimization algorithm. Adaptive Encoding gradually builds a transformation of the coordinate system such that the new coordinates are as decorrelated as possible with respect to the objective function. But any optimizat...

  18. 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. PMID:26726529

  19. Synthesis and evaluation of two new bifunctional carboxymethylated tetraazamacrocyclic chelating agents for protein labeling with indium-111

    Energy Technology Data Exchange (ETDEWEB)

    Ruser, G.; Ritter, W.; Maecke, H.R. (Univ. Hospital Basel (Switzerland))

    1990-09-01

    The synthesis of two new N- and C-functionalized tetraazamacrocyclic ligands intended to be covalently linked to biomolecules like monoclonal antibodies and to bind the gamma-emitting isotope indium-111 in a thermodynamically and/or kinetically inert way is described. 12-(p-Nitrobenzyl)-1,4,7,10-tetraazacyclotridecane-1,4,7,10-tetraa cetic acid (L1) was synthesized by means of bimolecular cyclization with the appropriate malonic acid diethyl ester and triethylenetetraamine, followed by reduction with diborane and alkylation of the cyclic tetraamine with bromoacetic acid. The corresponding triscarboxymethylated ligand L2 was made by statistical alkylation of the tetraamine. Both ligands fulfill the criteria for antibody labeling using the bifunctional chelate approach, namely fast chelate formation, high radiochemical yield, and high stability under physiological conditions. Surprisingly the heptadentate ligand L2 confers higher stability to In3+ and exhibits faster complex formation than octadentate L1. 13C NMR spectra in solution indicate that the difference in stability is not due to incomplete coordination of all four carboxylate groups in In-L1.

  20. IVS Technology Coordinator Report

    Science.gov (United States)

    Whitney, Alan

    2013-01-01

    This report of the Technology Coordinator includes the following: 1) continued work to implement the new VLBI2010 system, 2) the 1st International VLBI Technology Workshop, 3) a VLBI Digital- Backend Intercomparison Workshop, 4) DiFX software correlator development for geodetic VLBI, 5) a review of progress towards global VLBI standards, and 6) a welcome to new IVS Technology Coordinator Bill Petrachenko.

  1. Coordinate measuring machines

    DEFF Research Database (Denmark)

    De Chiffre, Leonardo

    This document is used in connection with three exercises of 2 hours duration as a part of the course GEOMETRICAL METROLOGY AND MACHINE TESTING. The exercises concern three aspects of coordinate measuring: 1) Measuring and verification of tolerances on coordinate measuring machines, 2) Traceabilit...

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

    OpenAIRE

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

    2013-01-01

    In the absence of an iron chelating agent, patients with beta-thalassemia on regular transfusions present complications of transfusion-related iron overload. Without iron chelation therapy, heart disease is the major cause of death; however, hepatic and endocrine complications also occur. Currently there are three iron chelating agents available for continuous use in patients with thalassemia on regular transfusions (desferrioxamine, deferiprone, and deferasirox) providing good results in red...

  3. The Role of Chelation in the Treatment of Other Metal Poisonings

    OpenAIRE

    Smith, Silas W.

    2013-01-01

    These proceedings will review the role of chelation in five metals—aluminum, cadmium, chromium, cobalt, and uranium—in order to illustrate various chelation concepts. The process of “chelation” can often be oversimplified, leading to incorrect assumptions and risking patient harm. For chelation to be effective, two critical assumptions must be fulfilled: the presumed “metal toxicity” must correlate with a given body or a particular compartment burden, and reducing this compartmental or the bo...

  4. Red Blood Cell Transfusion Independence Following the Initiation of Iron Chelation Therapy in Myelodysplastic Syndrome

    OpenAIRE

    Leitch, Heather A.; Vickars, Linda M.; Chase, Jocelyn M.; Badawi, Maha A.

    2010-01-01

    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 ...

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

    OpenAIRE

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

    2013-01-01

    Many Korean patients with transfusion-induced iron overload experience serious clinical sequelae, including organ damage, and require lifelong chelation therapy. However, due to a lack of compliance and/or unavailability of an appropriate chelator, most patients have not been treated effectively. Deferasirox (DFX), a once-daily oral iron chelator for both adult and pediatric patients with transfusion-induced iron overload, is now available in Korea. The effectiveness of deferasirox in reducin...

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

    OpenAIRE

    Toso, Leonardo

    2014-01-01

    Chelation therapy is widely used for metal-unbalance related diseases, namely those due to disorders on metal metabolism, such as beta-thalassemia, hemochromatosis (Fe), and neurodegenerative diseases (Cu, Fe, Zn and Al). The study of metal chelators for clinical applications, either as chelating therapeutics able to target specific metal ions in the body, or as metal-carriers for therapeutic or imaging purposes, is a topical research area which faces up to urgent medical problems. Meta...

  7. Chelate-modified polymers for atmospheric gas chromatography

    Science.gov (United States)

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

    1980-01-01

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

  8. New Regeneration process of heavy metals loaded chelating resin

    OpenAIRE

    Menoud, P.; Cavin, L.; Renken, A.

    2000-01-01

    An alternative to the classical acid-base regeneration of chelating resins loaded with heavy metals is investigated. The new process consists in recovering the heavy metals with recyclable soluble complexing agents. The semiclosed reactor includes a fixed bed and a stirred tank. A three-parameter model, which implies a double equilibrium in series, is introduced. When less than 10 % of the metal is still fixed on the resin at the end of the desorption, a simplified form of the model with two ...

  9. On Reaction Coordinate Optimality.

    Science.gov (United States)

    Krivov, Sergei V

    2013-01-01

    The following question is addressed: how to establish that a constructed reaction coordinate is optimal, i.e., that it provides an accurate description of dynamics. It is shown that the reaction coordinate is optimal if its cut free energy profile, determined using length-weighted transitions, is constant, i.e., it is position and sampling interval independent. The observation leads to a number of interesting results. In particular, the equilibrium flux between two boundary states can be computed exactly as diffusion on a free energy profile associated with the coordinate. The mean square displacement, for the trajectory projected onto the coordinate, grows linear with time. That for the same trajectory projected onto a suboptimal coordinate grows slower than linear with time. The results are illustrated on a number of model systems, Sierpinski gasket, FIP35 protein, and beta3s peptide. PMID:26589017

  10. Volatile Metals Coordination Compounds as Precursors for Functional Materials Synthesis by CVD-Method

    OpenAIRE

    Mazurenko, E.; Gerasimchuk, A.

    1995-01-01

    The applications of such coordination compounds (chelates) as metal β-diketonates in different CVD techniques were examined. It was shown that high chemical and physical characteristics of these compounds allow their favourable use comparatively with other volatile compounds. The general rules in volatility and thermal stability of β-diketonates and their fluorine derivatives were discussed. The ways of preparation of various functional materials with specific properties were determined.

  11. New 111In labeling of IgG: 111In-oxine mediated chelation

    International Nuclear Information System (INIS)

    Current methods of 111In chelate conjugation labeling of antibodies expose the protein to pH 5-6 during 111In chelation. These conditions could be detrimental if the antibody is acid labile. We have successfully labeled human IgG via the cyclic anhydride of DPTA and 111In-oxyquinoline(oxine). Chelation was achieved at pH 6.9-8.4 and was complete within 1 min at room temperature. The chelation was sensitive to trace metal contamination on labware and in some reagents (including commercial 111In-oxine). (author)

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

    International Nuclear Information System (INIS)

    '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 CO2 with and without added cosolvents, (2) the spectroscopic determination of preferential solvation of metal chelates by cosolvents in SC CO2 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 CO2/chelate mixtures is the equilibrium solubility of the metal chelate complex in the CO2.'

  13. 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...

  14. Synthesis of amidoxime chelating fiber and its adsorption properties for Cu(II) ion

    International Nuclear Information System (INIS)

    In order to obtain the chelating fiber for adsorbing metal ions in apple juice, the effect of different conditions on adsorption properties of chelating fiber for Cu(II) ion were discussed, such as pH and the time of ad- sorption. The isotherm of adsorption has bee confirmed. The desorption and its regeneration were simply discussed, too. The results showed that the chelating fiber had good kinetic property and the adsorbed equilibrium completed almost within 20-30 min. The adsorption properties was affected by the temperature and pH. The adsorption process fits the isothermal equation of Freundlich. The chelating fiber could be used repeatedly. (authors)

  15. Bioinspired Immobilization of Glycerol Dehydrogenase by Metal Ion-Chelated Polyethyleneimines as Artificial Polypeptides

    Science.gov (United States)

    Zhang, Yonghui; Ren, Hong; Wang, Yali; Chen, Kainan; Fang, Baishan; Wang, Shizhen

    2016-01-01

    In this study, a novel, simple and generally applicable strategy for multimeric oxidoreductase immobilization with multi-levels interactions was developed and involved activity and stability enhancements. Linear polyethyleneimines (PEIs) are flexible cationic polymers with molecular weights that span a wide range and are suitable biomimic polypeptides for biocompatible frameworks for enzyme immobilization. Metal ion-chelated linear PEIs were applied as a heterofunctional framework for glycerol dehydrogenase (GDH) immobilization by hydrogen bonds, electrostatic forces and coordination bonds interactions. Nanoparticles with diameters from 250–650 nm were prepared that exhibited a 1.4-fold enhancement catalytic efficiency. Importantly, the half-life of the immobilized GDH was enhanced by 5.6-folds in aqueous phase at 85 °C. A mechanistic illustration of the formation of multi-level interactions in the PEI-metal-GDH complex was proposed based on morphological and functional studies of the immobilized enzyme. This generally applicable strategy offers a potential technique for multimeric enzyme immobilization with the advantages of low cost, easy operation, high activity reservation and high stability. PMID:27053034

  16. Discovery of Metal Ions Chelator Quercetin Derivatives with Potent Anti-HCV Activities

    Directory of Open Access Journals (Sweden)

    Dongwei Zhong

    2015-04-01

    Full Text Available Analogues or isosteres of α,γ-diketoacid (DKA 1a show potent inhibition of hepatitis C virus (HCV NS5B polymerase through chelation of the two magnesium ions at the active site. The anti-HCV activity of the flavonoid quercetin (2 could partly be attributed to it being a structural mimic of DKAs. In order to delineate the structural features required for the inhibitory effect and improve the anti-HCV potency, two novel types of quercetin analogues, 7-O-arylmethylquercetins and quercetin-3-O-benzoic acid esters, were designed, synthesized and evaluated for their anti-HCV properties in cell-based assays. Among the 38 newly synthesized compounds, 7-O-substituted derivative 3i and 3-O-substituted derivative 4f were found to be the most active in the corresponding series (EC50 = 3.8 μM and 9.0 μΜ, respectively. Docking studies suggested that the quercetin analogues are capable of establishing key coordination with the two magnesium ions as well as interactions with residues at the active site of HCV NS5B.

  17. Coordination failure caused by sunspots

    DEFF Research Database (Denmark)

    Beugnot, Julie; Gürgüç, Zeynep; Øvlisen, Frederik Roose; Roos, Michael M. W.

    2012-01-01

    In a coordination game with Pareto-ranked equilibria, we study whether a sunspot can lead to either coordination on an inferior equilibrium (mis-coordination) or to out-of equilibrium behavior (dis-coordination). While much of the literature searches for mechanisms to attain coordination on the e......-dominant equilibrium, but in the sunspot treatment, dis-coordination is frequent. Sunspots lead to significant inefficiency, and we conclude that sunspots can indeed cause coordination failure....

  18. Synthesis of LaNiO3 perovskite type by chelating precursor method using EDTA: optimization of chelating content

    International Nuclear Information System (INIS)

    The perovskites are strategic materials due their catalytic, electronic and magnetic properties. These properties are influenced by the calcination and synthesis conditions. In this work was carried out the synthesis of LaNiO3 perovskite type by chelating precursor method using EDTA and also was studied the optimization of the EDTA content in the synthesis. The synthesized materials were characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TG) and Infrared Spectroscopy (FTIR). In the optimization of the EDTA content the lowest ratio of metal / EDTA used was 1.0 / 0.1, where it was possible to obtain monophasic perovskite. (author)

  19. Detoxication and removal of uranium by phenolic chelating agents

    International Nuclear Information System (INIS)

    The use of phenolic chelating agents for detoxication and removal of uranyl nitrate in mice and rats is reported. Antidotal test: 8102, 7601 and 811 were given 2 mM/kg subcutaneously to mice and 1 mM/kg intramuscularly to rats when the animals were injected i.p. with different doses (100-500 mg/kg) of uranyl nitrate. The results showed that the antidotal effects of 8102 and 7601 were better than 811 in augmenting survival, survival time (day) and renal factor (kidney weight/body weight x100). 8102 was superior to 7601 against higher dose of uranyl nitrate intoxication. Removal test: five phenolic chelating agents (8102, 7601, 811, 7603 and 8307) were studied in rats. The results obtained demonstrated that 8102 and 7601 were better than 811, 7603 and 8307 in increasing U excretion in the urine after acute uranyl nitrate intoxication. The effects of different doses (300-1000 μM/kg) of 8102 was superior to 7601 in increasing U excretion in the urine and decreasing U deposition in the tissues. The toxicity and dose of 8102 in treating uranium intoxication are discussed

  20. Capillary gas chromatography of metal chelates of diethyl dithiocarbamates

    Energy Technology Data Exchange (ETDEWEB)

    Arain, M.A.; Bhanger, M.I. [Center of Excellence in Analytical Chemistry (Pakistan); Khuhawar, M.Y. [M.A. Kazi Inst. of Chemistry, Univ. of Sindh, Jamshoro (Pakistan)

    2002-03-01

    Capillary GC of metal chelates of diethyl dithiocarbamate (DDTC) was examined on a methylsilicone DB-1 column, (25 meter, 0.2 mm. i.d) with a film thickness of 0.25 {mu}m. Elution was carried out at the initial column temperature of 180 C and programmed at 5 C min{sup -1} to 260 C. Detection was by FID or ECD. Symmetrical peaks with bse line separation were obtained with the metal chelates of copper(II), nickel(II), cobalt(III), manganese(II) and chromium(III). The ECD gave better sensitivity than the FID with a linear calibration range of 5 - 50 {mu}g mL{sup -1} and detection limits 2.0 - 6.0 {mu}g mL{sup -1}, corresponding to 111 - 333 pg of metal ion reaching the detector. The method was applied to the determination of metal ions in water and pharmaceutical preparations with a coefficient of variation (CV) within 4.0%. When compared with a standard flame AAS method the results revealed no significant difference. (orig.)

  1. Separation of human IgG fragments using copper, nickel, zinc, and cobalt chelated to CM-Asp-agarose by positive and negative chromatography.

    Science.gov (United States)

    Mourão, Cecília Alves; Carmignotto, Gabriela Pannunzio; Bueno, Sonia Maria Alves

    2016-04-01

    This study evaluated the feasibility of using immobilized metal-ion affinity chromatography (IMAC) for separation of human Fab fragments using four different transition metal ions copper, nickel, zinc, and cobalt chelated to CM-Asp (carboxymethylaspartate) immobilized on the agarose gel. The Fab and Fc fragments (from human IgG digested with papain) interacted differently with the chelates studied, depending on the adsorption buffer system. The interaction between chelate and Fc fragment is predominantly based on the coordination bonds using adsorption buffer containing NaCl. Negative chromatography was performed on Cu(II)-CM-Asp-agarose obtaining 2.9mg of Fab per mL of adsorbent in nonretained fractions (Fc fragment-free without uncleaved IgG). The adsorption of Fab fragments is governed by electrostatic forces in the absence of NaCl in the adsorption buffer. High selectivity was achieved on Co(II)-CM-Asp-agarose and 5.7mg of Fab per mL of adsorbent was obtained in eluted fractions without Fc fragments, although having uncleaved IgG. The results showed that chromatography on transition metal ions chetated to CM-Asp-agarose is a promising approach to separation of Fab fragments from papain-digested human IgG solution. PMID:26974869

  2. The Mechanism of Sol-Gel Synthesis of Normal Spinel LiMn2O4 with Chelation of Citric Acid

    Institute of Scientific and Technical Information of China (English)

    WU Hui; LEI Jia-heng; CHEN Yong-xi; SUN Yu-bin; YUAN Qi-hua

    2002-01-01

    The sol-gel process of citric acid chelating with metal cations for the synthesis of normal spinel LiMn2O4 and the reaction mechanism were investigated by means of XRD, IR, TG-DTA, and SEM. The results show that at the beginning lithium citrate and chelate compound of citric acid with manganese ions formed, and then with heating the esterification and condensation reactions occured between them and glycol. The products obtained are polymers in which metal cations are distributed homogeneously on atomic scale that ensure high reactivity to cations of Li + and Mn2 + . Firing the gel prepared by this process, the lattice diffusions of solid reactant ions caused by non-homogeneity of reactants are eliminated and avoided. At 400℃ phase-pure LiMn2 O4 with nanometer scale crystallization having precise stoichiometry and perfect crystallization can be obtained. The model of chelate coordinate of double-molecule between citric acid and Mn2 + in the gel network is proposed. It is important for explaining the dispersion state of Mn2 + and the formation process of gel by this model.

  3. SYNTHESES ET ÉTUDES STRUCTURALES DE COMPLEXES À OXO-ANION DE L'IODE (V) : VERS DE NOUVEAUX MATERIAUX POUR L'OPTIQUE NON LINEAIRE QUADRATIQUE

    OpenAIRE

    Suffren, Yan

    2010-01-01

    Le sujet de thèse a porté sur l'élaboration de iodates métalliques, matériaux pour l'ONL quadratique, qui permettraient de développer des dispositifs optiques à large bande de transparence du visible à l'IR lointain, couvrant les fenêtres de transparence II et III de l'atmosphère. La découverte de NaI3O8 présentant les principales caractéristiques des iodates a ouvert la voie à la recherche et caractérisation de nouvelles phases contenant le nouvel oxoanion [I3O8]- de l'iode (V). Des calculs ...

  4. The crystal chemistry of novel thorium and uranium compounds with oxo-anions from group VI of periodic table (S, Se, Te, Cr, Mo and W)

    OpenAIRE

    Xiao, Bin

    2016-01-01

    This dissertation focus on the synthesis, phase studies and physicochemical properties of novel thorium and uranium compounds with the Group VI (S, Se, Te, Cr, Mo, W) of the Periodic Table. All the studied compounds are listed in Table 2.2 from the page 15. I subdivided all the newly synthesized compounds into several chapters according to their structural and topological differences.First, for thorium molybdates and tungstates, almost all of these compounds are based on corner-sharing of ThO...

  5. Supercritical Airfoil Coordinates

    Data.gov (United States)

    National Aeronautics and Space Administration — Rectangular Supercritical Wing (Ricketts) - design and measured locations are provided in an Excel file RSW_airfoil_coordinates_ricketts.xls . One sheet is with Non...

  6. Movement and Coordination

    Science.gov (United States)

    ... in Action Medical Editor & Editorial Advisory Board Sponsors Sponsorship Opporunities Spread the Word Shop AAP Find a Pediatrician ... Movement and Coordination Page Content Article Body At this age, your child will seem to be continually on the go— ...

  7. Coordination and Policy Traps

    OpenAIRE

    Angeletos, George-Marios; Hellwig, Christian; Pavan, Alessandro

    2003-01-01

    This paper examines the ability of a policy maker to control equilibrium outcomes in an environment where market participants play a coordination game with information heterogeneity. We consider defense policies against speculative currency attacks in a model where speculators observe the fundamentals with idiosyncratic noise. The policy maker is willing to take a costly policy action only for moderate fundamentals. Market participants can use this information to coordinate on di.erent respon...

  8. Attribute coordination in organizations

    OpenAIRE

    Yingyi Qian; Gerard Roland; Chenggang Xu

    2001-01-01

    We study coordination in organizations with a variety of organizational forms. Coordination in organization is modeled as the adjustment of attributes and capacities of tasks when facing external shocks. An M-form (U-form) organization groups complementary (substitutable) tasks together in one unit. In the presence of only attribute shocks, particularly when gains from specialization are small, communication is poor, or shocks are more likely, the expected payoff of the decentralized M-form i...

  9. Continuous parallel coordinates.

    Science.gov (United States)

    Heinrich, Julian; Weiskopf, Daniel

    2009-01-01

    Typical scientific data is represented on a grid with appropriate interpolation or approximation schemes,defined on a continuous domain. The visualization of such data in parallel coordinates may reveal patterns latently contained in the data and thus can improve the understanding of multidimensional relations. In this paper, we adopt the concept of continuous scatterplots for the visualization of spatially continuous input data to derive a density model for parallel coordinates. Based on the point-line duality between scatterplots and parallel coordinates, we propose a mathematical model that maps density from a continuous scatterplot to parallel coordinates and present different algorithms for both numerical and analytical computation of the resulting density field. In addition, we show how the 2-D model can be used to successively construct continuous parallel coordinates with an arbitrary number of dimensions. Since continuous parallel coordinates interpolate data values within grid cells, a scalable and dense visualization is achieved, which will be demonstrated for typical multi-variate scientific data. PMID:19834230

  10. Magnetic Coordinate Systems

    Science.gov (United States)

    Laundal, K. M.; Richmond, A. D.

    2016-07-01

    Geospace phenomena such as the aurora, plasma motion, ionospheric currents and associated magnetic field disturbances are highly organized by Earth's main magnetic field. This is due to the fact that the charged particles that comprise space plasma can move almost freely along magnetic field lines, but not across them. For this reason it is sensible to present such phenomena relative to Earth's magnetic field. A large variety of magnetic coordinate systems exist, designed for different purposes and regions, ranging from the magnetopause to the ionosphere. In this paper we review the most common magnetic coordinate systems and describe how they are defined, where they are used, and how to convert between them. The definitions are presented based on the spherical harmonic expansion coefficients of the International Geomagnetic Reference Field (IGRF) and, in some of the coordinate systems, the position of the Sun which we show how to calculate from the time and date. The most detailed coordinate systems take the full IGRF into account and define magnetic latitude and longitude such that they are constant along field lines. These coordinate systems, which are useful at ionospheric altitudes, are non-orthogonal. We show how to handle vectors and vector calculus in such coordinates, and discuss how systematic errors may appear if this is not done correctly.

  11. Influence of chelation therapy (DTPA) on 141Ce retention in rats

    International Nuclear Information System (INIS)

    We investigated the influence of oral and parenteral administration of chelation therapy on the retention of 141Ce in young rats. Opposite to results obtained in adult rats present results show high efficacy of oral chelation therapy in reducing radiocerium retention in the whole body and organs of suckling rats. (author) 3 refs

  12. Samarium-153 and lutetium-177 chelation properties of selected macrocyclic and acyclic ligands

    International Nuclear Information System (INIS)

    We describe a simple in vitro characterization of chelation that is useful when choosing an appropriate ligand-metal combination for clinical applications. These properties include the effect of concentration on chelation efficiency, time to maximum chelation, and stability in acidic and serum environments. The macrocyclic ligands nitro-DOTA and nitro-PADOTA, the acyclic ligands nitro-CHX-A-DTPA, nitro-MX-DTPA, DTPA, and a novel terpyridine ligand, TMT-amine, were evaluated as chelate complexes of both intermediate energy β-emitting lanthanides lutetium-177 and samarium-153. The data were compared to results obtained in a previously published study with yttrium-90. Acid lability, time to achieve maximum chelation, and stability in human serum are properties unique to each ligand-metal combination and should be evaluated prior to choosing an appropriate combination for therapeutic applications. Concentration dependence and duration of chelation are general properties of lanthanide and yttrium chelation that can be applied to an appropriate ligand-metal combination to achieve optimum chelation efficiencies

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

    Science.gov (United States)

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

    2012-01-01

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

  14. Effects of chelating agents on protein, oil, fatty acid amd seed mineral concentrations in soybean

    Science.gov (United States)

    Soybean seed is a major source of protein and oil for human diet. Since not much information is available on the effects of chelating agents on soybean seed composition constituents, the current study aimed to investigate the effects of various chelating agents on soybean [(Glycine max (L.) Merr.)] ...

  15. Inhibitor Ranking Through QM based Chelation Calculations for Virtual Screening of HIV-1 RNase H inhibition

    DEFF Research Database (Denmark)

    Poongavanam, Vasanthanathan; Svendsen, Casper Steinmann; Kongsted, Jacob

    2014-01-01

    of the methods based on the use of a training set of molecules, QM based chelation calculations were used as filter in virtual screening of compounds in the ZINC database. By this, we find, compared to regular docking, QM based chelation calculations to significantly reduce the large number of false...

  16. Production and chelation properties of Lu-177, the isotope suitable for nuclear medicine applications

    International Nuclear Information System (INIS)

    Lutetium-177 is one of the most favoured radionuclides for radiotherapeutic applications due to its suitable nuclear characteristics. It has been mainly used in three areas: labelling of biomolecules (i.e., somatostatine analogues and monoclonal antibodies), palliative therapy of bone skeletal metastases, and radiation synovectomy. At present, Lu- labelled chelates with aminocarboxylates, like a DOTA or DTPA have been deeply investigated from the point of view of chelation properties. This research has been targeted on finding the optimal conditions of chelation to obtain high yields of chelates and on monitoring their kinetic stability, depending on particular factors (i.e., pH, molar ratios metal: ligand or duration of the reaction). The Lu-DTPA and Lu-DOTA chelates were prepared and detected radiochromatographically by TLC. For this purpose ITLC SG plates were used as a solid phase, and a mixture of hydroxylamine:methanol:water (0.2:2:4) was used as a liquid phase. (author)

  17. Red Blood Cell Transfusion Independence Following the Initiation of Iron Chelation Therapy in Myelodysplastic Syndrome

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    Monica Pinheiro de Almeida Verissimo

    2013-01-01

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

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-01-01

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

  1. 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.

  2. Incorporation of 241Am: effectiveness of late DTPA chelation therapy

    International Nuclear Information System (INIS)

    In four persons who had incorporated 241Am probably by inhalation, a DTPA chelation therapy was initiated several months after incorporation. Excretion measurements and in vivo measurements were performed in order to quantify the enhancement of 241Am excretion and the activity distribution in the body. DTPA was administered 4-11 times as an infusion of 1 g DTPA. Daily excretion rates were raised essentially, up to factors of 65-140 (urine) and 30-50 (faeces) after the first administration. Dose calculations performed on the basis of a modified ICRP 30, Part 4 model yielded dose reductions (e.g. for subject A) of 90%, 28%, 28% and 26% for liver, bone surfaces, red bone marrow and lungs, respectively, corresponding to a reduction of the effective dose equivalent of approximately 40%. (author)

  3. Economically dissolving barium sulfate scale with a chelating agent

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, E.A.; Scheuerman, R.E.

    1977-06-21

    A composition is described for dissolving a barium sulfate scale from a subterranean or other relatively remote location into which fluid can be flowed. Fluid is flow-flowed into the remote location so that a stream of fluid contacts and flows along the surface of the scale. The composition and flow rate of the fluid are adjusted so that (1) the scale is contacted by a stream of aqueous solution in which each portion contains enough dissolved aminopolyacetic acid salt chelating agent to dissolve barium sulfate, and (2) substantially all upstream portions of the scale are contacted by a succession of portions of the aqueous liquid which are substantially unsaturated with respect to dissolved barium-chelant complex. (5 claims)

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

    International Nuclear Information System (INIS)

    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)

  5. Effects of Zinc Chelators on Aflatoxin Production in Aspergillus parasiticus

    Science.gov (United States)

    Wee, Josephine; Day, Devin M.; Linz, John E.

    2016-01-01

    Zinc concentrations strongly influence aflatoxin accumulation in laboratory media and in food and feed crops. The presence of zinc stimulates aflatoxin production, and the absence of zinc impedes toxin production. Initial studies that suggested a link between zinc and aflatoxin biosynthesis were presented in the 1970s. In the present study, we utilized two zinc chelators, N,N,N′,N′-tetrakis (2-pyridylmethyl) ethane-1,2-diamine (TPEN) and 2,3-dimercapto-1-propanesulfonic acid (DMPS) to explore the effect of zinc limitation on aflatoxin synthesis in Aspergillus parasiticus. TPEN but not DMPS decreased aflatoxin biosynthesis up to six-fold depending on whether A. parasiticus was grown on rich or minimal medium. Although we observed significant inhibition of aflatoxin production by TPEN, no detectable changes were observed in expression levels of the aflatoxin pathway gene ver-1 and the zinc binuclear cluster transcription factor, AflR. Treatment of growing A. parasiticus solid culture with a fluorescent zinc probe demonstrated an increase in intracellular zinc levels assessed by increases in fluorescent intensity of cultures treated with TPEN compared to controls. These data suggest that TPEN binds to cytoplasmic zinc therefore limiting fungal access to zinc. To investigate the efficacy of TPEN on food and feed crops, we found that TPEN effectively decreases aflatoxin accumulation on peanut medium but not in a sunflower seeds-derived medium. From an application perspective, these data provide the basis for biological differences that exist in the efficacy of different zinc chelators in various food and feed crops frequently contaminated by aflatoxin. PMID:27271668

  6. Effects of Zinc Chelators on Aflatoxin Production in Aspergillus parasiticus.

    Science.gov (United States)

    Wee, Josephine; Day, Devin M; Linz, John E

    2016-01-01

    Zinc concentrations strongly influence aflatoxin accumulation in laboratory media and in food and feed crops. The presence of zinc stimulates aflatoxin production, and the absence of zinc impedes toxin production. Initial studies that suggested a link between zinc and aflatoxin biosynthesis were presented in the 1970s. In the present study, we utilized two zinc chelators, N,N,N',N'-tetrakis (2-pyridylmethyl) ethane-1,2-diamine (TPEN) and 2,3-dimercapto-1-propanesulfonic acid (DMPS) to explore the effect of zinc limitation on aflatoxin synthesis in Aspergillus parasiticus. TPEN but not DMPS decreased aflatoxin biosynthesis up to six-fold depending on whether A. parasiticus was grown on rich or minimal medium. Although we observed significant inhibition of aflatoxin production by TPEN, no detectable changes were observed in expression levels of the aflatoxin pathway gene ver-1 and the zinc binuclear cluster transcription factor, AflR. Treatment of growing A. parasiticus solid culture with a fluorescent zinc probe demonstrated an increase in intracellular zinc levels assessed by increases in fluorescent intensity of cultures treated with TPEN compared to controls. These data suggest that TPEN binds to cytoplasmic zinc therefore limiting fungal access to zinc. To investigate the efficacy of TPEN on food and feed crops, we found that TPEN effectively decreases aflatoxin accumulation on peanut medium but not in a sunflower seeds-derived medium. From an application perspective, these data provide the basis for biological differences that exist in the efficacy of different zinc chelators in various food and feed crops frequently contaminated by aflatoxin. PMID:27271668

  7. Removal of iron by chelation with molecularly imprinted supermacroporous cryogel.

    Science.gov (United States)

    Çimen, Duygu; Göktürk, Ilgım; Yılmaz, Fatma

    2016-06-01

    Iron chelation therapy can be used for the selective removal of Fe(3+) ions from spiked human plasma by ion imprinting. N-Methacryloyl-(L)-glutamic acid (MAGA) was chosen as the chelating monomer. In the first step, MAGA was complexed with the Fe(3+) ions to prepare the precomplex, and then the ion-imprinted poly(hydroxyethyl methacrylate-N-methacryloyl-(L)-glutamic acid) [PHEMAGA-Fe(3+)] cryogel column was prepared by cryo-polymerization under a semi-frozen temperature of - 12°C for 24 h. Subsequently, the template, of Fe(3+) ions was removed from the matrix by using 0.1 M EDTA solution. The values for the specific surface area of the imprinted PHEMAGA-Fe(3+) and non-imprinted PHEMAGA cryogel were 45.74 and 7.52 m(2)/g respectively, with a pore size in the range of 50-200 μm in diameter. The maximum Fe(3+) adsorption capacity was 19.8 μmol Fe(3+)/g cryogel from aqueous solutions and 12.28 μmol Fe(3+)/g cryogel from spiked human plasma. The relative selectivity coefficients of ion-imprinted cryogel for Fe(3+)/Ni(2+) and Fe(3+)/Cd(2+) were 1.6 and 4.2-fold greater than the non-imprinted matrix, respectively. It means that the PHEMAGA-Fe(3+) cryogel possesses high selectivity to Fe(3+) ions, and could be used many times without significantly decreasing the adsorption capacity. PMID:25727711

  8. Thiosemicarbazone complexes of the platinum metals. A story of variable coordination modes

    Indian Academy of Sciences (India)

    Indrani Pal; Falguni Basuli; Samaresh Bhattacharya

    2002-08-01

    Salicylaldehyde thiosemicarbazone (H2saltsc) reacts with [M(PPh3)3X2] (M = Ru, Os; X = Cl, Br) to afford complexes of type [M(PPh3)2(Hsaltsc)2], in which the salicylaldehyde thiosemicarbazone ligand is coordinated to the metal as a bidentate N,S-donor forming a four-membered chelate ring. Reaction of benzaldehyde thiosemicarbazones (Hbztsc-R) with [M(PPh3)3X2] also affords complexes of similar type, viz. [M(PPh3)2(bztsc-R)2], in which the benzaldehyde thiosemicarbazones have also been found to coordinate the metal as a bidentate N,S-donor forming a fourmembered chelate ring as before. Reaction of the Hbztsc-R ligands has also been carried out with [M(bpy)2X2] (M = Ru, Os; X = Cl, Br), which has afforded complexes of type [M(bpy)2(bztsc-R)]+, which have been isolated as perchlorate salts. Coordination mode of bztsc-R has been found to be the same as before. Structure of the Hbztsc-OMe ligand has been determined and some molecular modelling studies have been carried out determine the reason for the observed mode of coordination. Reaction of acetone thiosemicarbazone (Hactsc) has then been carried out with [M(bpy)2X2] to afford the [M(bpy)2(actsc)]ClO4 complexes, in which the actsc ligand coordinates the metal as a bidentate N,S-donor forming a five-membered chelate ring. Reaction of H2saltsc has been carried out with [Ru(bpy)2Cl2] to prepare the [Ru(bpy)2(Hsaltsc)]ClO4 complex, which has then been reacted with one equivalent of nickel perchlorate to afford an octanuclear complex of type [{Ru(bpy)2(saltsc-H)}4Ni4](ClO4)4.

  9. Generator Coordinate Truncations

    CERN Document Server

    Hagino, K; Reinhard, P G

    2003-01-01

    We investigate the accuracy of several schemes to calculate ground-state correlation energies using the generator coordinate technique. Our test-bed for the study is the $sd$ interacting boson model, equivalent to a 6-level Lipkin-type model. We find that the simplified projection of a triaxial generator coordinate state using the $S_3$ subgroup of the rotation group is not very accurate in the parameter space of the Hamiltonian of interest. On the other hand, a full rotational projection of an axial generator coordinate state gives remarkable accuracy. We also discuss the validity of the simplified treatment using the extended Gaussian overlap approximation (top-GOA), and show that it works reasonably well when the number of boson is four or larger.

  10. MR imaging of lung ventilation with aerosolized Gadolinium-chelates; MR-Bildgebung der Lungenventilation mittels aerosolierter Gadolinium-Chelate

    Energy Technology Data Exchange (ETDEWEB)

    Haage, P.; Karaagac, S.; Spuentrup, E.; Guenther, R.W. [RWTH Aachen (Germany). Klinik fuer Radiologische Diagnostik; Adam, G. [Universitaetsklinikum Hamburg-Eppendorf (Germany). Abt. fuer Diagnostische und Interventionelle Radiologie

    2003-02-01

    Purpose: To evaluate the feasibility of magnetic resonance assessment of human lung ventilation with aerosolized Gd-chelates in healthy volunteers. Materials and Methods: Five healthy adults (mean age 37 years) were studied with a 1.5 T unit. The volunteers were instructed to inhale the aerosol through an airtight facial mask for 10 minutes. The aerosol was generated with a jet-type small particle nebulizer with attached heater. Ventilation imaging was performed using a respiration-gated dynamic T{sub 1}-weighted turbo spin echo sequence (T{sub R}=199 ms, T{sub E}=8.5 ms, 12 signal averages, slice thickness 10 mm). Pulmonary signal intensity changes were calculated before and after nebulization. Results: The investigation was successfully carried out in all volunteers. An acute or delayed allergic reaction to the aerosolized contrast medium was not observed. In 4 of 5 experiments (80%), a homogeneous signal intensity increase was readily visualized with an average signal increase of 35% after 10 minutes; in one experiment, the aerosol distribution was slightly heterogeneous. (orig.) [German] Ziel: Bestimmung der Durchfuehrbarkeit einer kernspintomographischen Darstellung der Lungenventilation mittels aerosolierter Gd-Chelate bei gesunden Probanden. Methoden: 5 Probanden (Durchschnittsalter 37 Jahre) wurden in einem 1,5T System untersucht. Die Probanden atmeten spontan aerosoliertes Gd-DTPA ueber eine Atemmaske fuer eine Dauer von 10 Minuten. Das Kontrastmittel-Aerosol wurde ueber einen leistungsfaehigen druckluftbetriebenen Vernebler generiert. Die Illustration der Ventilation erfolgte mit einer atemgegateten dynamischen T{sub 1}-gewichteten Turbo-Spin-Echosequenz. Zur Quantitifizerung der Lungenventilation wurden die Signalintensitaeten im Lungengewebe vor und nach Verneblung berechnet. Ergebnisse: Alle Untersuchungen wurden komplikationslos durchgefuehrt und beendet. Eine akute oder verzoegerte Kontrastmittelreaktion wurde nicht beobachtet. In 4 von 5

  11. Coordination and citizen participation.

    Science.gov (United States)

    Tucker, D J

    1980-03-01

    This study investigates the validity of the assumption that coordination and citizen participation are related inversely and, thus, are incompatible as features in the same social service reform strategy. Seventeen social service organizations situated in the same urban area were studied. Data were obtained by structured interview. The concepts of coordination and citizen participation were operationalized by means of scales. The findings support the validity of the assumption noted above. Although interpretations of the findings can be provided, they are post-factum. This implies a need for explanatory research which might be guided by theories of community power structure and of organizational behavior. PMID:10246483

  12. Introduction to Coordination Chemistry

    CERN Document Server

    Lawrance, Geoffrey Alan

    2010-01-01

    Introduction to Coordination Chemistry examines and explains how metals and molecules that bind as ligands interact, and the consequences of this assembly process. This book describes the chemical and physical properties and behavior of the complex assemblies that form, and applications that may arise as a result of these properties. Coordination complexes are an important but often hidden part of our world?even part of us?and what they do is probed in this book. This book distills the essence of this topic for undergraduate students and for research scientists.

  13. Generation, Fractionation, and Characterization of Iron-Chelating Protein Hydrolysate from Palm Kernel Cake Proteins.

    Science.gov (United States)

    Zarei, Mohammad; Ghanbari, Rahele; Tajabadi, Naser; Abdul-Hamid, Azizah; Bakar, Fatimah Abu; Saari, Nazamid

    2016-02-01

    Palm kernel cake protein was hydrolyzed with different proteases namely papain, bromelain, subtilisin, flavourzyme, trypsin, chymotrypsin, and pepsin to generate different protein hydrolysates. Peptide content and iron-chelating activity of each hydrolysate were evaluated using O-phthaldialdehyde-based spectrophotometric method and ferrozine-based colorimetric assay, respectively. The results revealed a positive correlation between peptide contents and iron-chelating activities of the protein hydrolysates. Protein hydrolysate generated by papain exhibited the highest peptide content of 10.5 mM and highest iron-chelating activity of 64.8% compared with the other hydrolysates. Profiling of the papain-generated hydrolysate by reverse phase high performance liquid chromatography fractionation indicated a direct association between peptide content and iron-chelating activity in most of the fractions. Further fractionation using isoelectric focusing also revealed that protein hydrolysate with basic and neutral isoelectric point (pI) had the highest iron-chelating activity, although a few fractions in the acidic range also exhibited good metal chelating potential. After identification and synthesis of papain-generated peptides, GGIF and YLLLK showed among the highest iron-chelating activities of 56% and 53%, whereas their IC50 were 1.4 and 0.2 μM, respectively. PMID:26720491

  14. Effects of calcium chelators on calcium distribution and protein solubility in rennet casein dispersions.

    Science.gov (United States)

    McIntyre, Irene; O' Sullivan, Michael; O' Riordan, Dolores

    2016-04-15

    This study investigated the effects of calcium chelating salts on calcium-ion activity (ACa(++)), calcium distribution, and protein solubility in model CaCl2 solutions (50 mmol L(-1)) or rennet casein dispersions (15 g/100 g). Disodium phosphate and trisodium citrate at concentrations of 10 and 30 mmol L(-1) and at ratios of 1:0, 2:1, 1:1, 1:2 and 0:1 were added to both systems. The CaCl2 system, despite its simplicity, was a good indicator of chelating salt-calcium interactions in rennet casein dispersions. Adding trisodium citrate either alone or as part of a mixed chelating salt system resulted in high levels of dispersed "chelated" calcium; conversely, disodium phosphate addition resulted in lower levels, while the ACa(++) decreased with increasing concentration of both chelating salts. Neither chelating salt produced high levels of soluble protein. Thus calcium chelating salts may play a more subtle role in modulating hydration during manufacture of casein-based matrices than simply solubilising calcium or protein. PMID:26616945

  15. MRI marrow observations in thalassemia: the effects of the primary disease, transfusional therapy, and chelation

    International Nuclear Information System (INIS)

    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

  16. 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. PMID:12475278

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

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

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

  18. Preparation of chitosan-EDTA nanoparticles and the chelating effect of radioactive strontium in vivo

    International Nuclear Information System (INIS)

    Objective: To obtain the CTS-EDTA nanoparticles and investigate their effects of chelating 89Sr2+ in vivo. Method: The CTS-EDTA nanoparticles were prepared by cross-linking CTS-EDTA with polyanion sodium tripolyphosphate ( TPP). And the zwitterionic chelate of the CTS-EDTA nanoparticles was used for promoting the radionuclides excreted in vivo. Results: The CTS-EDTA nanoparticles showed that particle size was uniformity of the spherical nano-particles by TEM, and the average particle size of 10.18 nm by Laser Particle Sizer. we found that CEC-Nano and the CEC had a good chelating effect of radioactive strontium in vivo, after 30 min and 2 h in the medication and the chelating efficiency of radioactive strontium excretion in the femur was significantly higher than the EDTA-Na2. At multiple doses,the chelating efficiency of CEC-Nano and the CEC through the urinary excretion and feces were better than traditional medicines EDTA-Na2. Conclusion: By this experimental method, we can be prepare nanodrugs of chelating radionuclide, it provides a basis for studying the broad-spectrum of radionuclide contamination chelating agents. (authors)

  19. 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.

  20. Synthesis and Crystal Structure of a New Cadmium(Ⅱ) Supramolecular Network Containing Chelating Imidazole-4-carboxylate Ligand

    Institute of Scientific and Technical Information of China (English)

    YIN Wei-Ping; LI Yan-Ge; MEI Xue-Lan; YAO Jing-Cai

    2009-01-01

    A new complex, [Cd(Himc)2(H2O)2] 1, obtained from imidazole-4-carboxylatic acid (H2imc) and Cd(ClO4)2·6H2O, has been synthesized. The crystal structure was determined by X-ray diffraction. The title compound crystallizes in the orthorhombic system, space group Pccn, with a = 7.4886(11), b = 11.9667(18), c = 13.550(2) A, V= 1214.3(3) A3, Z = 4, Mr= 370.60, Dc = 2.027 mg/m3, F(000) = 728,μ (MoKα) = 1.829 mm-1, the final R = 0.0243 and wR = 0.0591 for 1150 unique reflections with I > 2σ(I). The cadmium(Ⅱ) center in the title complex is coordinated with two oxygen and two nitrogen atoms from two bidentate chelated imidazole-4-carboxlate ligands together with two water molecules, giving a distorted octahedral coordination geometry. A one-dimensional hydrogen bonding chain is formed via intermolecular O--H…O hydrogen bonds, and such adjacent chains are further stacked through intermolecular π-π and hydrogen bonding interactions to form a 3D supramolecular framework. Complex 1 exhibits a fluorescent emission band at 290 nm (λex = 236 nm) in the solid state.

  1. Physicochemical properties of skim milk powders prepared with the addition of mineral chelators.

    Science.gov (United States)

    Sikand, V; Tong, P S; Vink, Sean; Roy, Soma

    2016-06-01

    The objective of this study was to determine the effect of mineral chelator addition during skim milk powder (SMP) manufacture on the solubility, turbidity, soluble protein, and heat stability (HS). Three chelators (sodium citrate dihydrate, sodium polyphosphate, and disodium EDTA) at 3 different concentrations (5, 15, and 25mM) were added to skim milk concentrate (30% total solids), and the pH was adjusted to 6.65 before spray drying to produce SMP. Spray-dried SMP samples were tested for solubility index (SI). Additionally, samples were reconstituted to contain 9% total solids, adjusted to pH 7.0, and tested for turbidity, protein content from supernatants of ultracentrifuged samples, and HS. Lower SI values were observed for samples treated with 5mM disodium EDTA and sodium polyphosphate than control samples or samples with 5mM sodium citrate dihydrate. Furthermore, lower SI values were observed with an increased level of chelating agents regardless of chelator type. A decreased turbidity value was found with increasing levels of mineral chelating salt treatment. Low turbidity with increasing levels of added chelators may be associated with the dissociation of caseins from micelles. Furthermore, higher protein content was observed in supernatants of ultracentrifuged samples treated with increased level of chelators as compared with the control sample. Higher HS was observed in samples treated with 5mM compared with samples treated with 25mM mineral chelator. The results suggest improved solubility and HS upon addition of mineral chelators to SMP during its manufacture. PMID:27040785

  2. Recursive Advice for Coordination

    DEFF Research Database (Denmark)

    Terepeta, Michal Tomasz; Nielson, Hanne Riis; Nielson, Flemming

    Aspect-oriented programming is a programming paradigm that is often praised for the ability to create modular software and separate cross-cutting concerns. Recently aspects have been also considered in the context of coordination languages, offering similar advantages. However, introducing aspect...... systems. Even though primarily used for analysis of recursive programs, we are able to adapt them to fit this new context....

  3. Coordination of mobile labor

    Czech Academy of Sciences Publication Activity Database

    Steiner, Jakub

    2008-01-01

    Roč. 139, č. 1 (2008), s. 25-46. ISSN 0022-0531 R&D Projects: GA MŠk LC542 Institutional research plan: CEZ:AV0Z70850503 Keywords : coordination * general equilibrium * global game s Subject RIV: AH - Economics Impact factor: 1.224, year: 2008

  4. Facets of coordination chemistry

    CERN Document Server

    Agarwala, BV

    1993-01-01

    A concise account of coordination chemistry since its inception is given here together with some of the newer significant facets. This book covers a broad spectrum of various topics on Environment, Cyclic Voltammetry, Chromatography, Metal Complexes of biological interest, Alkoxides, NMR spectroscopy and others. These are useful to the scientific community engaged in the field of Inorganic Chemistry and Analytical Chemistry.

  5. Coordinating Work with Groupware

    DEFF Research Database (Denmark)

    Pors, Jens Kaaber; Simonsen, Jesper

    One important goal of employing groupware is to make possible complex collaboration between geographically distributed groups. This requires a dual transformation of both technology and work practice. The challenge is to re­duce the complexity of the coordination work by successfully inte­grating...

  6. Highly Diastereoselective Chelation-controlled Additions to α-Silyloxy Ketones

    OpenAIRE

    Stanton, Gretchen R.; KOZ, Gamze; Walsh, Patrick J.

    2011-01-01

    The polar Felkin-Anh, Cornforth, and Cram-chelation models predict that the addition of organometallic reagents to silyl–protected α–hydroxy ketones proceeds via a non-chelation pathway to give anti-diol addition products. This prediction has held true for the vast majority of additions reported in the literature and few methods for chelation-controlled additions of organometallic reagents to silyl–protected α–hydroxy ketones have been introduced. Herein, we present a general and highly diast...

  7. Thermodynamic study of chelation of rare earth(III) ions with 2,3-dihydroxynaphthalene (DON)

    International Nuclear Information System (INIS)

    The chelation of 2,3-dihydroxynaphthalene with trivalent La, Pr, Nd, Sm, Gd, Tb, Dy, Ho and Y has been studied pH-metrically at 30deg +- 0.5deg in aqueous ethanol (10% v/v) at different ionic concentrations (0.05, 01, 0.15 and 0.2M KNO3). Formation of 1:1 chelates are indicated. The order of stability is found to be Ho > Dy > Tb > Y> Gd > Sm > Nd > Pr > La. The thermodynamic stability constants and free energies of chelation have been reported. (author)

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

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

    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

  10. [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).

  11. (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).

  12. Guidelines on iron chelation therapy in patients with myelodysplastic syndromes and transfusional iron overload.

    Science.gov (United States)

    Gattermann, Norbert

    2007-12-01

    Experts believe that iron overload is an important problem which could be avoided with suitable treatment. Guidelines on treating myelodysplastic syndromes (MDS) include sections on using iron chelation therapy to prevent or ameliorate transfusional iron overload. The proportion of MDS patients who may benefit from iron chelation therapy is 35-55%, depending on the length of survival necessary for iron to accumulate to a detrimental level. Candidates for iron chelation are mainly patients with dyserythropoietic and cytopenic subtypes of disease, which fall into the International Prognostic Scoring System (IPSS) Low-risk or Intermediate-1-risk categories, with median survival of 3-6 years. PMID:18037413

  13. Synthesis, crystal structure and Thermogravimetry of ortho-phthalic acid bridged coordination polymer of Copper(II)

    Indian Academy of Sciences (India)

    BABITA SARMA; SAURAV BHARALI; DIGANTA KUMAR DAS

    2016-06-01

    Coordination polymer of Cu(II) bridged by o-phthalic acid alone is not known. The reaction of$CuCl_{2}.2H_{2}O$ with (2-butoxycarbonyl)benzoic acid yielded three dimensional coordination polymer bridged byo-phthalic acid. X-ray crystal structure shows structure with monoclinic P21/c space group. o-Phthalic acidmolecules act as bridge between two Cu(II), one carboxylate binds to one Cu(II) as bidentate while the othercarboxylate binds to another Cu(II) as monodentate. The four planar co-ordination positions of Cu(II) aresatisfied by two chelated carboxylates while fifth and sixth co-ordination positions are satisfied by monodentatecarboxylates. EPR and TGA of the coordination polymer are also reported.

  14. Imino sulfinamidines: synthesis and coordination chemistry of a novel class of chiral bidentate ligands.

    Science.gov (United States)

    Barrett, Anthony G M; Gray, Andrew A; Hill, Michael S; Hitchcock, Peter B; Procopiou, Panayiotis A; White, Andrew J P

    2006-04-17

    The new imino sulfinamidine ligand PhS(NHt-Bu)=NC(Me)=N(C6H3-2,6-iPr2), LH (11) was synthesized from N-(2,6-diisopropylphenyl)acetamidine (9) and N-tert-butyl phenylsulfinimidoyl chloride (10). Reaction of LH (11) with ZnEt2 or AlMe3 gave the complexes LZnEt (12) and LAlMe2 (13), respectively. The structures of 12 and 13 were determined by X-ray diffraction and were shown to contain L as a kappa2-N1,N5 bidentate ligand in a six-membered chelate. Formation of the magnesium complex (LMgN(TMS)2 x L2Mg) (14) from 11, MgI2, and KN(SiMe3)2 highlighted a secondary coordination mode of L, binding through the sulfinamidine nitrogens in a four-membered chelate. PMID:16602794

  15. Radioactive europium-chelate-based silica nanoparticles as a probe for stability, incorporation efficiency and trace analysis

    International Nuclear Information System (INIS)

    Two luminescent terbium and europium lanthanide chelates were efficiently embedded into silica nanoparticles by using a reverse microemulsion process. The incorporation was achieved without covalent bonding between the lanthanide chelates and the silica matrix. To investigate the efficiency of the incorporation process and the stability of the silica encapsulated lanthanide complex, a method based on a radioactive probe was developed; γ-emitting europium (152) chelates were synthesized and incorporated into silica nano-particles. Measurements of the γ activity through the entire synthesis allowed the accurate characterization of the incorporation efficiency of the used chelates. A clear correlation was established between the physicochemical properties of the different chelates and the measured incorporation efficiencies. A very efficient noncovalent incorporation of lanthanide chelates in highly stable nanoparticles was achieved by tuning the chelate properties, thus rendering the development of lanthanide-based fluorescent nanoparticles easier. (authors)

  16. Chelating water-soluble polymers for waste minimization

    International Nuclear Information System (INIS)

    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

  17. Chelation therapy of thorium deposited in rat lung

    International Nuclear Information System (INIS)

    The effect of calcium diethylenetriaminepentaacetate (CaDTPA) and a siderophore analogue 3,4,3-LI(1,2-HOPO) on decorporation of small and large thorium masses (234Th 46 ng, 234Th 46 ng + 232Th 5 μg per rat) instilled into the lungs was studied. Along with repeated injections, chelating agents were administered continuously by mini-osmotic pumps over 14 d. Treatment with CaDTPA alone was partly successful in the decorporation of both thorium masses. Greater decorporation was achieved with 3,4,3-LI(1,2-HOPO) in pumps and CaDTPA in injections. In the whole body, lungs and skeleton, 23%, 24% and 24% of control radioactivity was found, respectively, for the small mass of thorium. When the large mass of thorium was instilled, only continuous infusion of 3,4,3-LI(1,2-HOPO) at low concentration efficiently prevented transfer of thorium to the skeleton (reduced to 9% of control). Both the whole body and lungs retained 50% of control radioactivity. (author)

  18. The phospholipid vesicles coating on metal chelated inorganic surfaces

    International Nuclear Information System (INIS)

    This work showed the formation of phospholipid vesicle coating on inorganic sericite surface with characterization by combining electron microscopy of FE-SEM, TEM, AFM, and qualitatively evaluated the coated phospholipid vesicle by XPS as a function of etching time. The possibility of phospholipid vesicle mobility on the surface was restrained by the chelation effect of magnesium cation. The stabilization properties of phospholipid vesicles on sericite surface were demonstrated by the various concentration of magnesium cation. The presence of magnesium was found to have a much more pronounced influence on the lipid deposition process. The Mg cation plays an important role for attaching the phospholipids with optimum concentration of 7 mM. Totally, the phospholipid vesicles coating on inorganic powder could be useful for bio-related fields such as cosmetics and drug delivery system as the key functional compounds. We hope this basic result lead to a general and simple approach to prepare a wide a range of controlled releasing materials including an encapsulation with cosmetics or drugs

  19. The iron chelator desferrioxamine attenuates postischemic ventricular dysfunction

    International Nuclear Information System (INIS)

    Recent evidence suggests that postischemic myocardial dysfunction (stunning) may be mediated by oxygen free radicals, but the mechanism by which they produce myocellular damage remains unknown. Since iron catalyzes formation of hydroxyl radicals (HO·) as well as HO·-initiated lipid peroxidation, the authors explored the potential role of this metal in the pathogenesis of myocardial stunning. Open-chest dogs undergoing a 15-min occlusion of the left anterior descending coronary artery (LAD) followed by 4 h of reperfusion (REP) received the iron chelator desferrioxamine intravenously or normal saline. Regional myocardial function was assessed by measuring systolic wall thickening with an epicardial Doppler probe. The two groups exhibited comparable systolic thickening under base-line conditions and similar degrees of dyskinesis during ischemia. After REP, however, recovery of contractile function as considerably greater in desferrioxamine-treated compared with control dogs. These differences could not be ascribed to hemodynamic factors. The results suggest that iron-catalyzed reactions (possibly HO· generation) play a significant role in myocardial stunning after a brief episode of reversible regional ischemia

  20. Multidentate dipyridyl derivatives as chelates for rhenium (V)

    International Nuclear Information System (INIS)

    Rhenium (V) complexes with the following multidentate dipyridyl ligands were prepared: 2,2'-dipyridylamine (DPA), 1,2-bis(2-pyridyl)ethylene (DPE) and di-(2-picolyl)amine (HDIPA). Reactions of a twofold molar excess of the potentially NN donor ligand DPA with trans-[ReO (OEt)Cl2(PPh3)2] in ethanol led to isolation of a monomer [ReOCl2(OEt)(DPA)] (1). Treatments of trans-[ReOCl3(PPh3)2] with a tenfold molar excess of DPA in ethanol at reflux yielded [ReO2(dpa)2]Cl (2), but with a twofold molar excess a dimer (μ-O)[{ReOCl2(dpa)}2] (3a) was isolated. The latter reaction with (n-Bu4N)[ReOCl4] as starting material in ethanol at room temperature led to a dark green product, also with the formulation (μ-O)[{ReOCl2(dpa)}2] (3b). Reacting equimolar quantities of (n-Bu4N)[ReOCl4] and HDIPA in acetone led to [ReOCl(OH2)(DIPA)Cl (4) in which HDIPA acted as a monoanionic terdentate chelate. The reaction of trans-[ReOCl3(PPh3)2] with DPE, in which DPE undergoes a metal-promoted nucleophilic attack by a water molecule, produces a complex with a general formula [ReO(DPE.OH)Cl2] (5). (author)

  1. MR imaging of lung ventilation with aerosolized Gadolinium-chelates

    International Nuclear Information System (INIS)

    Purpose: To evaluate the feasibility of magnetic resonance assessment of human lung ventilation with aerosolized Gd-chelates in healthy volunteers. Materials and Methods: Five healthy adults (mean age 37 years) were studied with a 1.5 T unit. The volunteers were instructed to inhale the aerosol through an airtight facial mask for 10 minutes. The aerosol was generated with a jet-type small particle nebulizer with attached heater. Ventilation imaging was performed using a respiration-gated dynamic T1-weighted turbo spin echo sequence (TR=199 ms, TE=8.5 ms, 12 signal averages, slice thickness 10 mm). Pulmonary signal intensity changes were calculated before and after nebulization. Results: The investigation was successfully carried out in all volunteers. An acute or delayed allergic reaction to the aerosolized contrast medium was not observed. In 4 of 5 experiments (80%), a homogeneous signal intensity increase was readily visualized with an average signal increase of 35% after 10 minutes; in one experiment, the aerosol distribution was slightly heterogeneous. (orig.)

  2. Removal of Some Chelators from Aqueous Solutions Using Polymeric Ingredients

    International Nuclear Information System (INIS)

    This work tries to throw a light on the removal of thenoyl trifluoroacetone (TTA) and ethylene diamine tetraacetic acid (EDTA), extractants extensively used in many nuclear facilities, from aqueous solutions under different experimental conditions using Amberlite XAD resins. The applied resins exhibit high retention ability for the studied chelators with a maximum sorption capacity has the values of 23.9 and 38.0 mgg-1 for sorption of TTA and EDTA on Amberlite XAD4 and 18.6 and 21.2 mgg-1 for their sorption of on Amberlite XAD7. Factors affecting the resin retention ability such as ph value of aqueous solution and presence of co solvent have been studied. The kinetics of sorption behavior, in the applied system, indicate the process to be controlled by more than one diffusion mechanism. Therefore, two diffusion models were utilized to understand and verify the mechanism of sorption processes; they are the film mass transfer model and the interparticle diffusion model. The first model, based on film resistance, gave a successful depiction for sorption of TTA onto Amberlite XAD4 and XAD7 and the second one displayed an acceptable prediction for sorption of EDTA onto Amberlite XAD4

  3. Mechanisms of oxide dissolution by acid chelating agents

    International Nuclear Information System (INIS)

    In this paper, the different possible rate controlling processes in the dissolution of metallic oxides are examined. In particular, the following situations are assessed: mass-transfer control; coupling of mass-transfer and reactions at the interface; interface equilibration with the solution; various interface disruption and reconstruction phenomena. For each of the above mentioned cases, the influence of variables such as reagent concentration, temperature, pH, fluid hydrodynamics and general and specific catalysts is discussed. Depending upon the particular situation it is found that a more rational basis for the development of reagent is given by these considerations. The influence of chelating agents on both the thermodynamics and kinetics of the process is discussed, and the results of experimental studies in batch on magnetite and various ferrites are presented and discussed. For this purpose, several reagents were studied, including some very effective ones like thioglycolic acid, and others commonly used in actual decontamination, like ethylenediaminetetraacetic acid and oxalic acid. The relation to other (reductive) chemical decontamination procedures is discussed. The relevance of these studies to decontamination of metallic surfaces is discussed

  4. Conformal Fermi Coordinates

    CERN Document Server

    Dai, Liang; Schmidt, Fabian

    2015-01-01

    Fermi Normal Coordinates (FNC) are a useful frame for isolating the locally observable, physical effects of a long-wavelength spacetime perturbation. Their cosmological application, however, is hampered by the fact that they are only valid on scales much smaller than the horizon. We introduce a generalization that we call Conformal Fermi Coordinates (CFC). CFC preserve all the advantages of FNC, but in addition are valid outside the horizon. They allow us to calculate the coupling of long- and short-wavelength modes on all scales larger than the sound horizon of the cosmological fluid, starting from the epoch of inflation until today, by removing the complications of the second order Einstein equations to a large extent, and eliminating all gauge ambiguities. As an application, we present a calculation of the effect of long-wavelength tensor modes on small scale density fluctuations. We recover previous results, but clarify the physical content of the individual contributions in terms of locally measurable ef...

  5. Principles of Coordination Polymerisation

    Science.gov (United States)

    Kuran, Witold

    2001-11-01

    The first all-inclusive text covering coordination polymerisation, including important classes of non-hydrocarbon monomers. Charting the achievements and progress in the field, in terms of both basic and industrial research, this book offers a unified and complete overview of coordination polymerisation. Provides detailed description of the historical development of the subject Presents a unified view of catalysis, mechanisms, structures and utility Encourages learning through a step-by-step progression from basic to in-depth text Features end-of-chapter exercises to reinforce understanding Offers a full bibliography and comprehensive literature review Requisite reading for research students studying introductory and advanced courses in; polymer science, catalysis and polymerisation catalysis, and valuable reference for researchers and technicians in industry.

  6. Thiophene-based ligands as potential new metal ion chelation units in nuclear medicine

    International Nuclear Information System (INIS)

    An effort to explore new metal chelation units for radiopharmaceutical metal ion chelation applications has led us to the 2,5-dialkylamide-3,4-dihydroxythiophene type chelators. The ligand synthesis allows for facile asymmetric substitution that produces the amide-ester. Also, the monobenzyl derivative was obtained and structurally characterized in the P-1 space group with unit cell dimensions a = 10.111(3) A, b 11.761(3) A, c = 12.014(3) A , α = 72.987(5) .deg., β = 88.576(5) .deg., γ = 71.441(5) .deg., V = 1291.3(6) A3, Z = 2. The asymmetric hydrogen bonding pattern suggests the alternative salicylate-type metal chelation is accessible

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

  9. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Droege, P.

    1997-03-01

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

  11. Study of chelating agent as a surface modifier for retarding corrosion attack on ferrous metal

    International Nuclear Information System (INIS)

    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)

  12. Serum stability of 67Cu chelates: comparison with 111In and 57Co

    International Nuclear Information System (INIS)

    Simple chelates and chelate conjugated monoclonal antibodies labeled with 111In, 57Co and 67Cu demonstrate marked differences in stability when exposed to a serum environment. Among these radiometals, on DTPA, the order of stability is 111In > 57Co >> 67Cu. On benzyl-EDTA, the order of stability is 111In approx. 57Co >> 67Cu. Among those investigated, the only serum stable 67Cu chelate found was 67>Cu-TETA. The order of stability observed for 57Co vs 67Cu is contrary to published equilibrium constants. These in vitro studies suggest that the in vivo behavior of metal chelates exposed to a complex molecular environment may not be predicted by classically determined equilibrium constants. (author)

  13. Effect of chelating agents on the distribution of monoclonal antibodies in mice

    International Nuclear Information System (INIS)

    The potential for altering the biodistribution of radiolabel from gallium- and indium-labeled mouse monoclonal antibodies was investigated in mice using metal chelating agents. The chelating agents used were desferrioxamine (DFO), diethylenetriaminepentaacetic acid (DTPA), ethylenediamine-di (O-hydroxyphenylacetic acid) (EDHPA), and 2,2' dipyridyl (DIPY). The mouse monoclonal antibody LICR-LON-M8 was labeled with 111In after conjugation to DTPA, and with 67Ga after conjugation to DFO. All the chelating agents except DIPY altered the biodistribution of [67Ga]citrate and [111In]citrate but did not affect the 48-hr tissue uptake of label from [111In]DTPA-M8 or [67Ga]DFO-M8, confirming the in vivo stability of the antibody conjugates. Label fixed in the tissues was inaccessible to the chelating agents, indicating that they will not be suitable for reducing the high background liver radioactivity in patients undergoing scanning with indium-labeled antibodies

  14. Effect of chelating agents on the transport of radioactive solutes in subsurface porous media

    International Nuclear Information System (INIS)

    The effect of chelating agents on the transport of radioactive solutes in subsurface porous media is analyzed by formulating an advective-dispersive transport model which incorporates chelate formation, adsorption, decay, and degradation of transporting radioactive solutes. The governing equations are formulated by introducing the concept of a tenad. Particularly the governing equation for the tenad of a radioactive solute, is presented as a linear partial differential form and solved analytically by introducing an extended concept of distribution coefficient, KD. The calculated results from the model show that the transport rate of the tenad of a chelating agent, is much greater than that of the tenad. This faster transport of may be due to the low retardation factor of comparing to that of. Therefore, it is concluded that presence of chelating agents even in a small amount greatly accelerates the transport of radioactive wastes from a geologic radioactive waste repository

  15. The Management of Iron Chelation Therapy: Preliminary Data from a National Registry of Thalassaemic Patients

    Directory of Open Access Journals (Sweden)

    Adriana Ceci

    2011-01-01

    Full Text Available Thalassaemia and other haemoglobinopathies constitute an important health problem in Mediterranean countries, placing a tremendous emotional, psychological, and economic burden on their National Health systems. The development of new chelators in the most recent years had a major impact on the treatment of thalassaemia and on the quality of life of thalassaemic patients. A new initiative was promoted by the Italian Ministry of Health, establishing a Registry for thalassaemic patients to serve as a tool for the development of cost-effective diagnostic and therapeutic approaches and for the definition of guidelines supporting the most appropriate management of the iron-chelating therapy and a correct use of the available iron-chelating agents. This study represents the analysis of the preliminary data collected for the evaluation of current status of the iron chelation practice in the Italian thalassaemic population and describes how therapeutic interventions can widely differ in the different patients' age groups.

  16. Diagnostic compositions containing a chelate of radioactive indium and 8-hydroxyquinoline

    International Nuclear Information System (INIS)

    There are disclosed aqueous, radioassaying solutions of a chelate of radioactive indium and an 8-hydroxyquinoline, having an essential absence of an organic solvent, e.g., alcohol or chloroform. The solutions are useful in radioassaying warmblooded animals. (author)

  17. Simultaneous measurement of NK cell cytotoxicity against two target cell lines labelled with fluorescent lanthanide chelates.

    Science.gov (United States)

    Lövgren, J; Blomberg, K

    1994-07-12

    We describe a cytotoxicity assay which permits the simultaneous measurement of natural killer cell activity against two different cell lines. The target cell lines are labelled either with a fluorescent europium chelate or with a fluorescent terbium chelate and cell death is quantified by measuring the chelate release. K-562, Molt4 and Daudi cell lines have been used as targets. The release of the two chelates from the target cells can be detected with the help of time resolved fluorometry. As the measurements are made after background fluorescence has decayed no additional steps are needed to correct for the background from the medium. The assay procedure used for measurement of cytotoxicity against two target cell lines is very similar to the widely used 51Cr release assay. PMID:8034979

  18. 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.

  19. CATALYTIC HYDROGENATION OF ACRYLATE ASMMETRIC Dd(Ⅱ)—CHELATING RESINS CONTAINING AMINO ACID LIGANDS

    Institute of Scientific and Technical Information of China (English)

    Wangying; WangHongzuo; 等

    1995-01-01

    The catalytic hydrogenation of palladium chelating resins containing chiral amino acid ligands based on lower crosslinked poly(chloroethyl acrylate) and some effects on the rate of hydrogenation were studied.

  20. Communication and interference coordination

    OpenAIRE

    Blasco-Serrano, Ricardo; Thobaben, Ragnar; Skoglund, Mikael

    2014-01-01

    We study the problem of controlling the interference created to an external observer by a communication processes. We model the interference in terms of its type (empirical distribution), and we analyze the consequences of placing constraints on the admissible type. Considering a single interfering link, we characterize the communication-interference capacity region. Then, we look at a scenario where the interference is jointly created by two users allowed to coordinate their actions prior to...

  1. Advertising and Coordination

    OpenAIRE

    1990-01-01

    We show that when relevant market information such as price is difficult to communicate, advertising plays a key role in bringing about optimal coordination of purchase behavior: an efficient firm uses advertising expenditures in place of price to inform sophisticated consumers that it offers a better deal. This provides a theoretical explanation for Benham's (1972) empirical association of the ability to advertise with lower prices and larger scale. We find that advertising improves welfare ...

  2. Chelation in metal intoxication X: influence of different polyaminocarboxylic acids and thiol chelators in the excretion and tissue distribution of 54Mn in rat

    International Nuclear Information System (INIS)

    The influence of some selected polyaminocarboxylic acids and thiol metal binding agents on the urinary and faecal excretions of 54Mn and on the tissue distribution of 54Mn in 54MnC12 administered rats was studied to find a suitable chelating drug for Mn poisoning. HEDTA, CDTA, DTPA and TTHA were highly successful in enhancing the excretion of 54Mn and reducing the tissue levels of 54Mn in rats. The thiol chelators viz. D L-penicillamine, N-acetyl D L-penicillamine and DMS could neither influence the excretion nor the tissue distribution of 54Mn suggesting poor affinity of the metal towards sulfhydryl groups

  3. Global coordination: weighted voting

    Directory of Open Access Journals (Sweden)

    Jan-Erik Lane

    2014-03-01

    Full Text Available In order to halt the depletion of global ecological capital, a number of different kinds of meetings between Governments of countries in the world has been scheduled. The need for global coordination of environmental policies has become ever more obvious, supported by more and more evidence of the running down of ecological capital. But there are no formal or binding arrangements in sight, as global environmental coordination suffers from high transaction costs (qualitative voting. The CO2 equivalent emissions, resulting in global warming, are driven by the unstoppable economic expansion in the global market economy, employing mainly fossil fuel generated energy, although at the same time lifting sharply the GDP per capita of several emerging countries. Only global environmental coordination on the successful model of the World Band and the IMF (quantitative voting can stem the rising emissions numbers and stop further environmental degradation. However, the system of weighted voting in the WB and the IMF must be reformed by reducing the excessive voting power disparities, for instance by reducing all member country votes by the cube root expression.

  4. Improving Project Manufacturing Coordination

    Directory of Open Access Journals (Sweden)

    Korpivaara Ville

    2014-09-01

    Full Text Available The objective of this research is to develop firms’ project manufacturing coordination. The development will be made by centralizing the manufacturing information flows in one system. To be able to centralize information, a deep user need assessment is required. After user needs have been identified, the existing system will be developed to match these needs. The theoretical background is achieved through exploring the literature of project manufacturing, development project success factors and different frameworks and tools for development project execution. The focus of this research is rather in customer need assessment than in system’s technical expertise. To ensure the deep understanding of customer needs this study is executed by action research method. As a result of this research the information system for project manufacturing coordination was developed to respond revealed needs of the stakeholders. The new system improves the quality of the manufacturing information, eliminates waste in manufacturing coordination processes and offers a better visibility to the project manufacturing. Hence it provides a solid base for the further development of project manufacturing.

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

    OpenAIRE

    Evangeli, M.; Mughal, K.; Porter, J. B.

    2010-01-01

    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 be...

  6. Zn2+ chelation improves recovery by delaying spreading depression-like events

    OpenAIRE

    Carter, Russell E.; Weiss, John H; Shuttleworth, C. William

    2010-01-01

    We previously reported Zn2+ chelation improved recovery of synaptic potentials after transient oxygen and glucose deprivation in brain slices. Such an effect could be due to reduced accumulation of Zn2+ in postsynaptic neurons, or could also be due to prevention of the onset of spreading depression-like events. A combination of optical and electrical recording was used here to demonstrate that Zn2+ chelation is effective because it delays spreading depression-like events. If the duration of o...

  7. Diagnostic chelation challenge with DMSA: a biomarker of long-term mercury exposure?

    OpenAIRE

    Frumkin, H; Manning, C C; Williams, P. L.; Sanders, A; Taylor, B.B.; Pierce, M; Elon, L; Hertzberg, V S

    2001-01-01

    Chelation challenge testing has been used to assess the body burden of various metals. The best-known example is EDTA challenge in lead-exposed individuals. This study assessed diagnostic chelation challenge with dimercaptosuccinic acid (DMSA) as a measure of mercury body burden among mercury-exposed workers. Former employees at a chloralkali plant, for whom detailed exposure histories were available (n = 119), and unexposed controls (n = 101) completed 24-hr urine collections before and afte...

  8. Role of chelating agent in chemical and fluorescent properties of SnO2 nanoparticles

    Science.gov (United States)

    He, Shao-Bo; Wang, Shi-Fa; Ding, Qing-Ping; Yuan, Xiao-Dong; Zheng, Wan-Guo; Xiang, Xia; Li, Zhi-Jie; Zu, Xiao-Tao

    2013-05-01

    A modified Polyacrylamide gel route is applied to synthesize SnO2 nanoparticles. High-quality SnO2 nanoparticles with a uniform size are prepared using different chelating agents. The average particle size of the samples is found to depend on the choice of the chelating agent. The photoluminescence spectrum detected at λex = 230 nm shows a new peak located at 740 nm due to the surface defect level distributed at the nanoparticle boundaries.

  9. Metal Extraction From Soil Samples By chelation in a Microwave System

    OpenAIRE

    Chatreewongsin, Urai

    2000-01-01

    This work involves the combination of chelation and microwave extraction as a technique for extracting adsorbed metals in soil. It has been termed in this work, Chelate Assisted Microwave Extraction (CAME). Unlike other extraction methods, CAME is able to differentiate between anthropological and geological trace metals. The method has been applied to major sample matrices included three types of soils (Bertie Sandy Loam, Davidson Silty Clay, and Davidson Clayey Loam) as well as se...

  10. The Role of Chelation in the Treatment of Arsenic and Mercury Poisoning

    OpenAIRE

    Kosnett, Michael J

    2013-01-01

    Chelation for heavy metal intoxication began more than 70 years ago with the development of British anti-lewisite (BAL; dimercaprol) in wartime Britain as a potential antidote the arsenical warfare agent lewisite (dichloro[2-chlorovinyl]arsine). DMPS (unithiol) and DMSA (succimer), dithiol water-soluble analogs of BAL, were developed in the Soviet Union and China in the late 1950s. These three agents have remained the mainstay of chelation treatment of arsenic and mercury intoxication for mor...

  11. Production of siderophore type chelates in Atlantic Ocean waters enriched with different carbon and nitrogen sources

    OpenAIRE

    Mawji, Edward; Gledhill, M.; Milton, J.A.; M. V. Zubkov; Thompson, Anu; Wolff, George A.; Achterberg, Eric P.

    2011-01-01

    Siderophore type chelates were detected in nutrient enriched, incubated seawater collected from different biogeographical regions of the Atlantic Ocean. Seawater was enriched with glucose and ammonium, glycine (as a source of carbon and nitrogen) or chitin and ammonium at different concentrations and incubated for up to 3 – 4 days in the dark. Siderophore type chelates were detected using high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-...

  12. ORGANIC CHELATING REAGENT ON REDOX ADSORPTION OF ACTIVATED CARBON FIBER TOWARDS Au3+

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Organic chelating reagent influences upon the redox adsorption of activated carbon fibertowards Au3- were systematically investigated. The experimental results indicated that the presenceof organic chelating reagent on activated carbon fiber strongly affects adsorption capacity ofactivated carbon fiber towards Au3+. The reduction-adsorption amount of Au3+ increased three timesby the presence of 8-quinolinol. Furthermore, The reduction-adsorption amount of Au3+ depended onthe pH value of adsorption and temperature.

  13. Intracellular reduction/activation of a disulfide switch in thiosemicarbazone iron chelators

    OpenAIRE

    Akam, Eman A.; Chang, Tsuhen M.; Astashkin, Andrei V.; Tomat, Elisa

    2014-01-01

    Iron scavengers (chelators) offer therapeutic opportunities in anticancer drug design by targeting the increased demand for iron in cancer cells as compared to normal cells. Prochelation approaches are expected to avoid systemic iron depletion as chelators are liberated under specific intracellular conditions. In the strategy described herein, a disulfide linkage is employed as a redox-directed switch within the binding unit of an antiproliferative thiosemicarbazone prochelator, which is acti...

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

    International Nuclear Information System (INIS)

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

  15. Curcumin, a cancer chemopreventive and chemotherapeutic agent, is a biologically active iron chelator

    OpenAIRE

    Jiao, Yan; Wilkinson, John; Di, Xiumin; Wang, Wei; Hatcher, Heather; Kock, Nancy D.; D'Agostino, Ralph; Knovich, Mary Ann; Torti, Frank M; Suzy V Torti

    2009-01-01

    Curcumin is a natural product currently in human clinical trials for a variety of neoplastic, preneoplastic, and inflammatory conditions. We previously observed that, in cultured cells, curcumin exhibits properties of an iron chelator. To test whether the chelator activity of curcumin is sufficient to induce iron deficiency in vivo, mice were placed on diets containing graded concentrations of both iron and curcumin for 26 weeks. Mice receiving the lowest level of dietary iron exhibited borde...

  16. Thermolysis preparation of ZnS nanoparticles from a nano-structure bithiazole zinc(II) coordination compound

    Science.gov (United States)

    Hosseinian, Akram; Rahimipour, Hamid Reza; Haddadi, Hedayat; Ashkarran, Ali Akbar; Mahjoub, Ali Reza

    2014-09-01

    Nano-scale and single crystals of a new tris-chelate Zn(II) compound, {[Zn(DADMBTZ)3](SCN)2ṡ4H2O}n, (1), {DADMBTZ = 2,2‧-diamino-5,5‧-dimethyl-4,4‧-bithiazole} have been synthesized by the reaction of zinc(II) sulfate, ammonium thiocyanate and DADMBTZ using sonochemical and branched tube methods, respectively. The new nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and FT-IR spectroscopy. Compound (1) was structurally characterized by single crystal X-ray diffraction. Compound (1) form a tris-chelate complex with nearly C3 symmetry. The coordination number of zinc atom in the compound is six with coordinated environments of distorted octahedral, ZnN6. In reaction with DADMBTZ, the ligand DADMBTZ acts as bidentate in compound to form five-membered chelate rings with the same internal angles in coordination polyhedron. The crystal packing is mainly stabilized by N-H- - - -N hydrogen bonding interactions. The thermal stability of compound (1) was studied by thermal gravimetric (TG) and differential thermal analyses (DTA). ZnS nanostructures were obtained by direct thermolyses of compound (1) at 400 °C under argon atmosphere. The ZnS nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy.

  17. Synthesis and Characterization of polyacrylamide Chelating Resin with Thenoyltrifluoroacetone for Separation of Thorium from Uranium

    International Nuclear Information System (INIS)

    New effective chelating resin is synthesized by immobilization of Thenoyltrifluoroacetone (HTTA) on cross linked polyacrylamide. The chelating exchanger is used for separation of uranium (UO22+) and thorium(Th4+). The analyzed metal ions were quantitatively measured by ion chromatographic technique coupled with UV/V is detector and derivatization reaction of Arsenazo(III) at wavelength 660 nm. Different factors affecting the metal ions uptake and hence the separation efficient c y of the chelating polyacrylamide resin were investigated. Optimization of conditions showed that maximum uptake of UO22+ and Th4+ are at ph 4.0 and 3.0 respectively. Isothermal capacity shows a relatively high capacity of the chelating resin towards divalent uranium more than that of tetravalent thorium. The capacity of the chelating resin for UO22+ and Th4+ was found to be 0.05 and 0.034 mmol/gm, respectively. Separation of UO22+ and Th4+ was successively performed using column chromatographic technique loaded with the chelating resin. The retained metal ions were sequentially separated by i socratic elution using 0.1 M HNO3

  18. The antibody-linked chelating polymers for nuclear therapy and diagnostics

    International Nuclear Information System (INIS)

    This review deals with the problem of protein modification with chelating polymers. The main purpose of this approach is the preparation of monoclonal antibodies labeled with heavy metal isotopes (α-, β-, and δ-emitting metals and metals used for NMR-tomography). Traditional binding of metals with proteins via chelating agents directly coupled to protein molecule does not allow binding a high number of metal atoms per single protein molecule and can also alter protein specific properties. At the same time, metal-to-protein binding via intermediate chelating polymer makes possible the binding of several dozen metal atoms per single protein without affecting its specific properties. Moreover, the variations in polymer properties and molecular weight allow controlled modified antibody biodistribution and clearance rate. Modified antibodies can be used successfully for nuclear and NMR diagnostics and for nuclear therapy. The following problems are discussed: the chemistry of the coupling of chelating groups to polymer backbone; the binding of chelating polymers to proteins, including monoclonal antibodies; the ability of chelating polymer-to-protein conjugates to bind heavy metals; the influence of the modification on protein conformation and specific properties; the behavior of metal-containing conjugates in vivo; the practical use of conjugates obtained for radioimmunoimaging, radioimmunotherapy, NMR-tomography, and in vitro immunoassays. Future prospects of the approach are also discussed.101 references

  19. Chelate chase of radiopharmaceuticals reversibly bound to monoclonal antibodies improves dosimetry

    International Nuclear Information System (INIS)

    One hundred micrograms of monoclonal antibody (MoAb) CHA 255 with a binding constant Kb of 4 x 109 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

  20. Wood impregnated with metal chelates dissolved in organic media tested for termite resistance

    Directory of Open Access Journals (Sweden)

    Lara Maistrello

    2011-08-01

    Full Text Available Wood manufactured products are subjected to biological decay due to fungi and insects. The use of copper chelates as biocides was proposed, due to their high stability which minimizes copper leaching into the environment. Considering the remarkable effectiveness showed by copper chelates on brown rot fungi, zinc and copper salicylate complexes were prepared in order to have metal chelates soluble in organic media available. The present study aimed at evaluating these metal chelates complexes as preservative agents for wood treatment against termites. Trials were performed on Reticulitermes lucifugus (Rossi and Kalotermes flavicollis (Fabricius. Results showed that in both termite species wood consumption was significantly lower on Cu-chelates treated samples compared to untreated wood, whereas the wood slices impregnated with Zn-chelates and the organic media alone gave an intermediate response. Interestingly, in one case solvent-impregnated wood was significantly more attractive than untreated wood for both species and further investigations are being carried out to clarify this behaviour.

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

    International Nuclear Information System (INIS)

    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

  2. Translational downregulation of HSP90 expression by iron chelators in neuroblastoma cells.

    Science.gov (United States)

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

    2015-01-01

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

  3. Optimization of chelators to enhance uranium uptake from tailings for phytoremediation.

    Science.gov (United States)

    Jagetiya, Bhagawatilal; Sharma, Anubha

    2013-04-01

    A greenhouse experiment was set up to investigate the ability of citric acid (CA), oxalic acid (OA), nitrilotriacetic acid (NTA) and EDTA for phytoremediation of uranium tailings by Indian mustard [Brassica juncea (L.) Czern. et Coss]. Uranium tailings were collected from Umra mining region and mixed with 75% of garden soil which yielded a 25:75 mixture. Prepared pots were divided into four sets and treated with following different concentrations - 0.1, 0.5, 2.5 and 12.5 mmol kg(-1) soil additions for each of the four chelators. Control pots which were not treated with chelators. Experiments were conducted in completely randomized block design with triplicates. The optimum concentrations of these chelators were found on the basis of biomass production, tolerance and accumulation potential. The data collected were expressed statistically. EDTA produced maximum growth depression whereas, minimum occurred in the case of NTA. Maximum U uptake (3.5-fold) in the roots occurred at 2.5 mmol of CA, while NTA proved to be the weakest for the same purpose. Severe toxicity in the form of reduced growth and plant death was recorded at 12.5 mmol of each chelator. Minimum growth inhibition produced by chelators occurred in NTA which was followed by OA, moderate in CA and maximum was traced in EDTA applications. Chelator strengthened U uptake in the present study follows the order: CA>EDTA>OA>NTA. PMID:23267730

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

    International Nuclear Information System (INIS)

    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.)

  5. Emission properties of Sm(III) complex having ten-coordination structure

    International Nuclear Information System (INIS)

    Sammarium(III) complex having ten-coordination structure, bis-(1,10-phenanthroline)tris-(hexafluoroacetylacetonato)samarium(III) (Sm(hfa)3(phen)2) was prepared by chelation of tris-(hexafluoroacetylacetonato) samarium(III) (Sm(hfa)3(H2O)2) with 1,10-phenantroline (phen). The characteristic ten-coordination structure of Sm(hfa)3(phen)2 was determined by 1H NMR and elemental analyses. Strong deep-red emission (λmax=643 nm) and narrow emission band (FWHM=5 nm) of Sm(hfa)3(phen)2 originated from electronic allowed transition from characteristics ten coordinate structure. The emission quantum yields Sm(hfa)3(phen)2 excited at absorption bands of ligands and Sm(III) ion were found to be 0.36 and 1.4%, respectively

  6. Coordination chemistry in the solid: evidence for coordination modes within hybrid materials different from those in solution.

    Science.gov (United States)

    Corriu, Robert J P; Embert, Frank; Guari, Yannick; Reyé, Catherine; Guilard, Roger

    2002-12-16

    Two routes of incorporation of europium(III) salts into cyclam-containing hybrid materials have been explored, to elucidate the coordination mode of EuIII in cyclam-containing hybrid materials in a study of the arrangement of cyclam moieties during the solgel process. They were 1) complexation of europium salts by N-tetrasubstituted 1,4,8,11-tetraazacyclotetradecane (cyclam) derivatives bearing four hydrolysable Si(OEt)3 groups, followed by hydrolysis and polycondensation of these complexes; and 2) hydrolysis and polycondensation of N-tetrasubstituted silylated cyclam derivatives, then incorporation of europium salts directly into the hybrid materials. The coordination mode of europium salts within solids is not the same as in solution. In solution, the complexation of EuIII with cyclam is not possible; it requires cyclam derivatives containing N-chelating substituents such as amido groups in an appropriate geometry. In contrast, the incorporation of EuIII into hybrid materials is always possible, whatever the nature of the arms of the cyclam moieties. Thus, EuIII uptake is one EuIII/two macrocycles with cyclam moieties containing N-alkyl substituents. This constitutes the first example of 4N + 4N lanthanide coordination. PMID:12693055

  7. Communication, leadership and coordination failure

    OpenAIRE

    Dong, Lu; Montero, Maria; Possajennikov, Alex

    2015-01-01

    Using experimental methods, this paper investigates the limits of communication and leadership in aiding group coordination in a minimum effort game. Choosing the highest effort is the payoff dominant Nash equilibrium in this game, and communication and leadership are expected to help in coordinating on such an equilibrium. We consider an environment in which the benefits of coordination are low compared to the cost of mis-coordination. In this environment, players converge to the most ineffi...

  8. Communication, Leadership and Coordination Failure

    OpenAIRE

    Lu Dong; Maria Montero; Alex Possajennikov

    2015-01-01

    Using experimental methods, this paper investigates the limits of communication and leadership in aiding group coordination in a minimum effort game. Choosing the highest effort is the payoff dominant Nash equilibrium in this game, and communication and leadership are expected to help in coordinating on such an equilibrium. We consider an environment in which the benefits of coordination are low compared to the cost of mis-coordination. In this environment, players converge to the most ineffi...

  9. Chelation of intracellular calcium blocks insulin action in the adipocyte

    Energy Technology Data Exchange (ETDEWEB)

    Pershadsingh, H.A.; Shade, D.L.; Delfert, D.M.; McDonald, J.M.

    1987-02-01

    The hypothesis that intracellular Ca/sup 2 +/ is an essential component of the intracellular mechanism of insulin action in the adipocyte was evaluated. Cells were loaded with the Ca/sup 2 +/ chelator quin-2, by preincubating them with quin-2 AM, the tetrakis(acetoxymethyl) ester of quin-2. Quin-2 loading inhibited insulin-stimulated glucose transport without affecting basal activity. The ability of insulin to stimulate glucose uptake in quin-2-loaded cells could be partially restored by preincubating cells with buffer supplemented with 1.2 mM CaCl/sub 2/ and the Ca/sup 2 +/ ionophore A23187. These conditions had no effect on basal activity and omission of CaCl/sub 2/ from the buffer prevented the restoration of insulin-stimulated glucose uptake by A23187. Quin-2 loading also inhibited insulin-stimulated glucose oxidation and the ability of insulin to inhibit cAMP-stimulated lipolysis without affecting their basal activities. Incubation of cells with 100 ..mu..M quin-2 or quin-2 AM had no effect on intracellular ATP concentration or the specific binding of /sup 125/I=labeled insulin to adipocytes. These findings suggest that intracellular Ca/sup 2 +/ is an essential component in the coupling of the insulin-activated receptor complex to cellular physiological/metabolic machinery. Furthermore, differing quin-2 AM dose-response profiles suggest the presence of dual Ca/sup 2 +/-dependent pathways in the adipocyte. One involves insulin stimulation of glucose transport and oxidation, whereas the other involves the antilipolytic action of insulin.

  10. Chelation of intracellular calcium blocks insulin action in the adipocyte

    International Nuclear Information System (INIS)

    The hypothesis that intracellular Ca2+ is an essential component of the intracellular mechanism of insulin action in the adipocyte was evaluated. Cells were loaded with the Ca2+ chelator quin-2, by preincubating them with quin-2 AM, the tetrakis(acetoxymethyl) ester of quin-2. Quin-2 loading inhibited insulin-stimulated glucose transport without affecting basal activity. The ability of insulin to stimulate glucose uptake in quin-2-loaded cells could be partially restored by preincubating cells with buffer supplemented with 1.2 mM CaCl2 and the Ca2+ ionophore A23187. These conditions had no effect on basal activity and omission of CaCl2 from the buffer prevented the restoration of insulin-stimulated glucose uptake by A23187. Quin-2 loading also inhibited insulin-stimulated glucose oxidation and the ability of insulin to inhibit cAMP-stimulated lipolysis without affecting their basal activities. Incubation of cells with 100 μM quin-2 or quin-2 AM had no effect on intracellular ATP concentration or the specific binding of 125I=labeled insulin to adipocytes. These findings suggest that intracellular Ca2+ is an essential component in the coupling of the insulin-activated receptor complex to cellular physiological/metabolic machinery. Furthermore, differing quin-2 AM dose-response profiles suggest the presence of dual Ca2+-dependent pathways in the adipocyte. One involves insulin stimulation of glucose transport and oxidation, whereas the other involves the antilipolytic action of insulin

  11. Development of chelate tagging method of protein at low temperature

    International Nuclear Information System (INIS)

    This study aimed at development of a protein labelling method at a low temperature, available for functional proteins, such as antibodies and enzymes mostly unstable at high temperatures. A solution of anti-mouse IgG antibody added with EDTA was incubated with 51CrCl3 at 4degC for 24 hours. After stopping the reaction with 100-fold amount of EDTA-2Na, the solution was fractionated into antibody fraction and metal fraction by HPLC. After incubation, non-specific Cr adsorption on the antibody in no relation to the chelate reagent was chased with 10-fold amount of CrCl3. To remove free Cr, the sample solution was incubated with 10 to 50-fold ICB-EDTA solution containing N,N-dimethyl-formamide. Then, the amount of Cr-labelling on the antibody was determined. In Western-blotting, chick actin was applied onto SDS-polyacrylamide gel electrophoresis. One part of the lane was stained with brilliant-blue and the other was transferred on nitrocellulose membrane by semi-dry method and stained with panceau-S. Anti-actin monoclonal antibody and anti-mouse IgG antibody were used as the first antibody and the second one, respectively. When incubated with ICB-EDTA for 3 days, labelling reached the maximum level. Although labelling of the second antibody was performed with maleimido-C3-benzyl EDTA and 45Ca as a substitute for 51Cr, the rate of labelling was lower than the rate for a combination of ICB-EDTA and 51Cr. Autoradiography of the anti-mouse IgG preparation after SDS-acrylamide gel electrophoresis revealed that radioactivity was detected on the site of H-chain but not L-chain. This indicates that 51Cr labelling of protein is stable even under the conditions of SDS denaturation. (M.N.)

  12. Resinas quelantes amidoxímicas Amidoxime chelating resins

    Directory of Open Access Journals (Sweden)

    Fernanda M. B. Coutinho

    1999-12-01

    Full Text Available Resinas quelantes com grupos amidoxima foram sintetizadas por copolimerização em suspensão de acrilonitrila (AN e divinilbenzeno (DVB e subsequente modificação química dos grupos ciano por reação com hidroxilamina. Na copolimerização, a proporção de divinilbenzeno e o grau de diluição foram variados. Gelatina e carbonato de cálcio foram usados como estabilizadores de suspensão e sulfato de sódio foi adicionado para reduzir a solubilidade da acrilonitrila em água, por meio do efeito salting out. Os copolímeros de AN/DVB e as resinas amidoxímicas obtidos foram caracterizados por meio de densidade aparente, área específica, volume de poros e teor de nitrogênio. As resinas amidoxímicas foram também avaliadas em relação a capacidade de complexação de íons cobre.Chelating resins with amidoxime groups were synthesized by suspension copolymerization of acrylonitrile (AN and divinylbenzene (DVB and subsequent chemical modification of cyano groups by reaction with hydroxylamine. In the copolymerization, the proportion of divinylbenzene and the dilution degree were varied. Gelatin and calcium carbonate were used as suspension stabilizers and sodium sulphate was added in order to reduce acrylonitrile solubility in water, by salting out effect. The AN/DVB copolymers and amidoxime resins obtained were characterized by apparent density, surface area, pore volume and by the content of nitrogen. The amidoxime resins were also evaluated in relation to the complexation capacity of copper ion.

  13. Modeling Students' Units Coordinating Activity

    OpenAIRE

    Boyce, Steven James

    2014-01-01

    Primarily via constructivist teaching experiment methodology, units coordination (Steffe, 1992) has emerged as a useful construct for modeling students' psychological constructions pertaining to several mathematical domains, including counting sequences, whole number multiplicative conceptions, and fractions schemes. I describe how consideration of units coordination as a Piagetian (1970b) structure is useful for modeling units coordination across contexts. In this study, I extend teaching ...

  14. Pt(II) Phosphors Featuring Both Dicarbene and Functional Biazolate Chelates: Synthesis, Luminescent Properties, and Applications in Organic Light-Emitting Diodes.

    Science.gov (United States)

    Liao, Jia-Ling; Chi, Yun; Wang, Jin-Yun; Chen, Zhong-Ning; Tsai, Zheng-Hua; Hung, Wen-Yi; Tseng, Meu-Rurng; Lee, Gene-Hsiang

    2016-07-01

    Pt(II) metal complexes [Pt(C^C)(X^X)] comprising three functional dianionic azolate chelates (X^XH2: bipzH2 = 5,5'-di(trifluoromethyl)-3,3'-bipyrazole, bitzH2 = 5,5'-di(trifluoromethyl)-3,3'-bi-1,2,4-triazole, and phpzH2 = 3-(trifluoromethyl)-5-(4-(trifluoromethyl)phenyl)-1H-pyrazole), together with three different charge-neutral dicarbene chelates (i.e., C^C = 1,1'-methylene bis(3-methyl-imidazol-2-ylidene), 1,1'-methylene bis(3-isopropyl-imidazol-2-ylidene), and 1,1'-(propane-1,3-diyl) bis(3-isopropyl-imidazol-2-ylidene), were synthesized and found to show bright solid-state emission depending on the associated X^X and C^C chelates. Pt(II) complexes 1a, 2, and 6 were examined by X-ray diffraction studies, confirming the square-planar skeleton. These Pt(II) metal complexes are found to be nonemissive in degassed solution at RT. The photophysical measurements as neat powder reveals emission maxima ranging from purple to sky blue emission and with high quantum yields for the majority of them. (Time-dependent) density functional theory (DFT/TD-DFT) calculations were executed to elucidate the emission process that was predominated by the combined3LLCT/(3)LMCT/(3)IL character, where LLCT and LMCT and IL stand for ligand-to-ligand charge transfer, ligand-to-metal charge transfer, and intraligand ππ* transition processes. Organic light-emitting devices comprising complex 5a achieved high efficiency (8.9%, 19.4 cd·A(-1), 22.5 lm·W(-1)) with a sky blue emission showing CIEx,y coordinates of (0.18, 0.32). PMID:27302056

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

    Science.gov (United States)

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

    2007-12-01

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

  16. 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

  17. Coordination Processes in International Organisations

    DEFF Research Database (Denmark)

    Nedergaard, Peter

    2008-01-01

    The EU is not a member of the International Labour Organisation (ILO), but relatively elaborate EU coordination takes place anyway. This paper addresses two research questions: 1) How is it possible to evaluate the coordination of the EU in its specific observable configuration in the ILO?, and 2......) To what outcome does this coordination lead and why? Based on an analysis of EU coordination before and during the International Labour Conference in 2005, and on a comparison with coordination processes of the IMEC group, it is found that the Commission and the Presidency act as twin-agents vis...

  18. Action of chelators on solid iron in phosphate-containing aqueous solutions

    International Nuclear Information System (INIS)

    To study the effect of strong iron-ligands on steel corrosion, mild steel electrodes were immersed in solutions containing 20 mM phosphate buffer (pH=7.2) and between 0.01 mM and 1 M of either the iron(II)-chelators 2,2'-bipyridine or FerroZine, or the iron(III)-chelators citrate or acetylacetonate. Resulting surface reactions were investigated by quantifying the electrochemical potential (E), the electrochemical polarization resistance (Rp), the corrosion current (Icorr) and the release of iron into solution. The surface was further analyzed by scanning electron microscopy (SEM/SEM-EDAX) and atomic force microscopy. Concentrations of 0.1 mM of any of the chelators led to slight, temporary changes in E, Icorr and Rp. Concentrations of 10 mM resulted in characteristic changes of E, which were the same for all chelators and in the precipitation of FePO4 in the case of citrate and acetylacetonate, or vivianite [Fe3(PO4)2 · 8H2O] in the case of bipyridine and FerroZine. Concentrations of 1 mM of both iron(III)-chelators led to a temporary drop of E similar to that found with 0.1 mM chelator. With iron(II)-chelators, E dropped to about -500 mV before oscillating for several days. The amplitudes of the oscillations were up to 200 mV with periods of 30 and 20-25 min for bipyridine and FerroZine, respectively

  19. Spontaneous Double Hydrometallation Induced by N→M Coordination in Organometallic Hydrides of Group 14 Elements.

    Science.gov (United States)

    Novák, Miroslav; Dostál, Libor; Turek, Jan; Alonso, Mercedes; De Proft, Frank; Růžička, Aleš; Jambor, Roman

    2016-04-11

    Our attempts to synthesise N→M intramolecularly coordinated diorganometallic hydrides L2 MH2 [M=Si (4), Ge (5), Sn (6)] containing the CH=N imine group (in which L is C,N-chelating ligand {2-[(2,6-iPr2 C6 H3 )N=CH]C6 H4 }(-) ) yielded 1,1'-bis(2,6-diisopropylphenyl)-2,2'-spriobi[benzo[c][1,2]azasilole] (7), 1,1'-bis(2,6-diisopropylphenyl)-2,2'-spriobi[benzo[c][1,2]azagermole] (8) and C,N-chelated homoleptic stannylene L2 Sn (10), respectively. Compounds 7 and 8 are an outcome of a spontaneous double hydrometallation of the two CH=N imine moieties induced by N→M intramolecular coordination (M=Si, Ge) in the absence of any catalyst. In contrast, the diorganotin hydride L2 SnH2 (6) is redox-unstable and the reduction of the tin centre with the elimination of H2 provided the C,N-chelated homoleptic stannylene L2 Sn (10). Compounds 7 and 8 were characterised by NMR spectroscopy and X-ray diffraction analysis. Because the proposed N→M intramolecularly coordinated diorganometallic hydrides L2 MH2 [M=Si (4), Ge (5), Sn (6)] revealed two different types of reduction reactions, DFT calculations were performed to gain an insight into the structures and bonding of the non-isolable diorganometallic hydrides as well as the products of their subsequent reactions. Furthermore, the thermodynamic profiles of the different reaction pathways with respect to the central metal atom were also investigated. PMID:26934563

  20. Monosaccharides as silicon chelators: pentacoordinate bis(diolato)(phenyl)silicates with the cis-furanose isomers of common pentoses and hexoses.

    Science.gov (United States)

    Klüfers, Peter; Kopp, Florian; Vogt, Martin

    2004-09-20

    Five-coordinate phenylsilicates are formed from the reaction of trimethoxy(phenyl)silane with monosaccharides in methanol in the presence of a stoichiometric amount of base. Five complexes have been isolated and characterized with two ketoses and three aldopentoses. The silicon central atom in [K([18]crown-6)][PhSi(beta-D-Fruf 2,3H-2)2].MeOH (1, Fru=fructose) is part of two chelate rings, with the ligands being beta-D-fructofuranose-O2,O3 dianions. The beta-furanose isomer is best suited for silicon ligation because it exhibits a torsion angle close to 0 degrees for the most acidic diol function, thus assuring a flat chelate ring. The same structural principles are also found in [K([18]crown-6)][PhSi(beta-D-Araf1,2H-2)2].2 MeOH (2, Ara=arabinose), [K([18]crown-6)][PhSi(alpha-D-Ribf1,2H-2)2] (3, Rib=ribose), [K([18]crown-6)][PhSi(alpha-D-Xylf1,2H-2)2]. acetone (4, Xyl=xylose), and [K([18]crown-6)][PhSi(alpha-D-Rulf2,3H-2)2] (5, Rul=ribulose). PMID:15378633

  1. A Novel and Simple Molecular Probe Sensing Hg(II) in Living Cells by Chelation-enhanced Fluorescence%A Novel and Simple Molecular Probe Sensing Hg(II) in Living Cells by Chelation-enhanced Fluorescence

    Institute of Scientific and Technical Information of China (English)

    Meng, Qinghua; Cheng, Sen; Lan, Minbo; Wei, Gang

    2012-01-01

    Mercury is currently widely used in industries which leads to various means of Hg(II) waste exposure and its accumulation in organisms will cause neurological damages. Thus, there is a great need for the design of probes or sensors with high sensitivity and selectivity for detecting and monitoring Hg(II) at physiological pH. Thus a novel and simple molecular probe P1 was prepared from 1,1'-(1,3-phenylene)-bis(2,4-pentanedionato) for sensing Hg(II) via chelation-enhanced fluorescence (CHEF) mechanism. The probe indicated a selectively fluorescent response to Hg(II) in aqueous media excited by the ultraviolet light of 254 nm. The recognition mechanism was further studied by semi-empirical AM1 and molecular mechanics MM+ methods in HyperChem 8.0. The calculation indicated a tetrahedron coordination geometry for Hg(II) and a chair-like configuration for the total molecule. The fluorescent images sensing Hg(II) in living mouse fibroblast cells by the probe were obtained by fluorescence microscope.

  2. Comparison of bifunctional chelates for {sup 64}Cu antibody imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Cara L.; Crisp, Sarah; Bensimon, Corinne [MDS Nordion, Vancouver, BC (Canada); Yapp, Donald T.T.; Ng, Sylvia S.W. [British Columbia Cancer Agency Research Centre, Vancouver, BC (Canada); University of British Columba, The Faculty of Pharmaceutical Sciences, Vancouver, BC (Canada); Sutherland, Brent W. [British Columbia Cancer Agency Research Centre, Vancouver, BC (Canada); Gleave, Martin [Prostate Centre at Vancouver General Hospital, Vancouver, BC (Canada); Jurek, Paul; Kiefer, Garry E. [Macrocyclics Inc., Dallas, TX (United States)

    2010-11-15

    Improved bifunctional chelates (BFCs) are needed to facilitate efficient {sup 64}Cu radiolabeling of monoclonal antibodies (mAbs) under mild conditions and to yield stable, target-specific agents. The utility of two novel BFCs, 1-Oxa-4,7,10-triazacyclododecane-5-S-(4-isothiocyanatobenzyl)-4,7,10-triacetic acid (p-SCN-Bn-Oxo-DO3A) and 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-4-S-(4-isothiocyanatobenzyl)-3,6,9-triacetic acid (p-SCN-Bn-PCTA), for mAb imaging with {sup 64}Cu were compared to the commonly used S-2-(4-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-tetraacetic acid (p-SCN-Bn-DOTA). The BFCs were conjugated to trastuzumab, which targets the HER2/neu receptor. {sup 64}Cu radiolabeling of the conjugates was optimized. Receptor binding was analyzed using flow cytometry and radioassays. Finally, PET imaging and biodistribution studies were done in mice bearing either HER2/neu-positive or HER2/neu-negative tumors. {sup 64}Cu-Oxo-DO3A- and PCTA-trastuzumab were prepared at room temperature in >95% radiochemical yield (RCY) in <30 min, compared to only 88% RCY after 2 h for the preparation of {sup 64}Cu-DOTA-trastuzumab under the same conditions. Cell studies confirmed that the immunoreactivity of the mAb was retained for each of the bioconjugates. In vivo studies showed that {sup 64}Cu-Oxo-DO3A- and PCTA-trastuzumab had higher uptake than the {sup 64}Cu-DOTA-trastuzumab at 24 h in HER2/neu-positive tumors, resulting in higher tumor to background ratios and better tumor images. By 40 h all three of the {sup 64}Cu-BFC-trastuzumab conjugates allowed for clear visualization of the HER2/neu-positive tumors but not the negative control tumor. The antibody conjugates of PCTA and Oxo-DO3A were shown to have superior {sup 64}Cu radiolabeling efficiency and stability compared to the analogous DOTA conjugate. In addition, {sup 64}Cu-PCTA and Oxo-DO3A antibody conjugates may facilitate earlier imaging with greater target to background ratios than

  3. Chelation: A Fundamental Mechanism of Action of AGE Inhibitors, AGE Breakers, and Other Inhibitors of Diabetes Complications

    OpenAIRE

    Nagai, Ryoji; Murray, David B.; Metz, Thomas O.; Baynes, John W.

    2012-01-01

    This article outlines evidence that advanced glycation end product (AGE) inhibitors and breakers act primarily as chelators, inhibiting metal-catalyzed oxidation reactions that catalyze AGE formation. We then present evidence that chelation is the most likely mechanism by which ACE inhibitors, angiotensin receptor blockers, and aldose reductase inhibitors inhibit AGE formation in diabetes. Finally, we note several recent studies demonstrating therapeutic benefits of chelators for diabetic car...

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

    OpenAIRE

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

    2010-01-01

    According to the Felkin-Anh and Cram-chelation models, nucleophilic additions to α-silyloxy aldehydes procees through a non-chelation pathway due to the steric and electronic properties of the silyl group, giving rise to Felkin addition products. Herein we describe a general method to promote chelation-control in additions to α-silyloxy aldehydes. Dialkylzincs, functionalized dialkylzincs, and (E)-disubstituted, (E)-trisubstituted, and (Z)-disubstituted vinylzinc reagents add to silyl-protect...

  5. Correlation of acid-base properties of polymeric chelate sorbents and pH50 of gallium and indium sorption

    International Nuclear Information System (INIS)

    Complexing properties of synthesized polymeric chelate-forming sorbents - substituents of polystyrene-azo-pyrocatechol - are investigated and quantitative correlations between pKOH of functional analytical group and pH50 of chelate formation are determined to investigate regularities of interactions in element - sorbent system. Correlations obtained make it possible to realize special forecast on choice and usage of chelate sorbents for separation and concentrating of gallium and indium microquantities from objects of different nature

  6. Development of new metal chelates for animal nutrition and of analytical methods for their quantitative determination and quality control

    OpenAIRE

    Beltrami, Diego

    2009-01-01

    The growing interest for mineral integration to increase mineral bioavalability brought researchers to re-examine accurately the impact that complexes and chelates can have for food industry. In fact, the so-called organic or chelate mineral forms, in particular those associated with amino acids, peptides or other organic molecules, afforded encouraging results in different in vivo tests on animals of economic interest fed with fodder containing minerals in the form of chelates. Moreover, it ...

  7. High-Relaxivity MRI Contrast Agents: Where Coordination Chemistry Meets Medical Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Werner, Eric J.; Datta, Ankona; Jocher, Christoph J.; Raymond, Kenneth N.

    2008-01-15

    The desire to improve and expand the scope of clinical magnetic resonance imaging (MRI) has prompted the search for contrast agents of higher efficiency. The development of better agents requires consideration of the fundamental coordination chemistry of the gadolinium(III) ion and the parameters that affect its efficacy as a proton relaxation agent. In optimizing each parameter, other practical issues such as solubility and in vivo toxicity must also be addressed, making the attainment of safe, high-relaxivity agents a challenging goal. Here we present recent advances in the field, with an emphasis on the hydroxypyridinone family of Gd{sup III} chelates.

  8. Network Coordinator Report

    Science.gov (United States)

    Himwich, Ed; Strand, Richard

    2013-01-01

    This report includes an assessment of the network performance in terms of lost observing time for the 2012 calendar year. Overall, the observing time loss was about 12.3%, which is in-line with previous years. A table of relative incidence of problems with various subsystems is presented. The most significant identified causes of loss were electronics rack problems (accounting for about 21.8% of losses), antenna reliability (18.1%), RFI (11.8%), and receiver problems (11.7%). About 14.2% of the losses occurred for unknown reasons. New antennas are under development in the USA, Germany, and Spain. There are plans for new telescopes in Norway and Sweden. Other activities of the Network Coordinator are summarized.

  9. Coordination using Implicit Communication

    CERN Document Server

    Cuff, Paul

    2011-01-01

    We explore a basic noise-free signaling scenario where coordination and communication are naturally merged. A random signal X_1,...,X_n is processed to produce a control signal or action sequence A_1,...,A_n, which is observed and further processed (without access to X_1,...,X_n) to produce a third sequence B_1,...,B_n. The object of interest is the set of empirical joint distributions p(x,a,b) that can be achieved in this setting. We show that H(A) >= I(X;A,B) is the necessary and sufficient condition for achieving p(x,a,b) when no causality constraints are enforced on the encoders. We also give results for various causality constraints. This setting sheds light on the embedding of digital information in analog signals, a concept that is exploited in digital watermarking, steganography, cooperative communication, and strategic play in team games such as bridge.

  10. Coordinating Group report

    International Nuclear Information System (INIS)

    In December 1992, western governors and four federal agencies established a Federal Advisory Committee to Develop On-site Innovative Technologies for Environmental Restoration and Waste Management (the DOIT Committee). The purpose of the Committee is to advise the federal government on ways to improve waste cleanup technology development and the cleanup of federal sites in the West. The Committee directed in January 1993 that information be collected from a wide range of potential stakeholders and that innovative technology candidate projects be identified, organized, set in motion, and evaluated to test new partnerships, regulatory approaches, and technologies which will lead to improve site cleanup. Five working groups were organized, one to develop broad project selection and evaluation criteria and four to focus on specific contaminant problems. A Coordinating Group comprised of working group spokesmen and federal and state representatives, was set up to plan and organize the routine functioning of these working groups. The working groups were charged with defining particular contaminant problems; identifying shortcomings in technology development, stakeholder involvement, regulatory review, and commercialization which impede the resolution of these problems; and identifying candidate sites or technologies which could serve as regional innovative demonstration projects to test new approaches to overcome the shortcomings. This report from the Coordinating Group to the DOIT Committee highlights the key findings and opportunities uncovered by these fact-finding working groups. It provides a basis from which recommendations from the DOIT Committee to the federal government can be made. It also includes observations from two public roundtables, one on commercialization and another on regulatory and institutional barriers impeding technology development and cleanup

  11. Coordinating distributed work: Exploring situated coordination with gaming-simulation

    OpenAIRE

    van Laere, J.

    2003-01-01

    Organizational work has become more and more distributed nowadays. Information and communication technologies (ICT) provide opportunities to improve coordination of distributed work, but in practice many organizations struggle with integrating new organizational structures, new work practices and ICT. In this dissertation we present a design approach for improving the coordination of distributed work. First we develop an integrated view on coordination, based on observations of current coordi...

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

    Science.gov (United States)

    Hart, J. Roger

    1984-01-01

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

  13. Synthesis, characterization and in vitro anticancer evaluations of two novel derivatives of deferasirox iron chelator.

    Science.gov (United States)

    Salehi, Samie; Saljooghi, Amir Sh; Shiri, Ali

    2016-06-15

    Iron (Fe) chelation therapy was initially designed to alleviate the toxic effects of excess Fe evident in Fe-overload diseases. However, the novel toxicological properties of some Fe chelator-metal complexes have shifted significant attention to their application in cancer chemotherapy. The present study investigates the new role of deferasirox as an anticancer agent due to its ability to chelate with iron. Because of aminoacids antioxidant effect, deferasirox and its two novel amino acid derivatives have been synthesized through the treatment of deferasirox with DCC as well as glycine or phenylalanine methyl ester. All new compounds have been characterized by elemental analysis, FT-IR NMR and mass spectrometry. Therefore, the cytotoxicity of these compounds was screened for antitumor activity against some cell lines using cisplatin as a comparative standard by MTT assay and Flow cytometry. The impact of iron in the intracellular generation of reactive oxygen species was assessed on HT29 and MDA-MB-231 cells. The potential of the synthesized iron chelators for their efficacy to protect cells against model oxidative injury induced was compared. The reactive oxygen species intracellular fluorescence intensity were measured and the result showed that the reactive oxygen species intensity after iron incubation increased while after chelators incubation the reactive oxygen species intensity were decreased significantly. Besides, the effect of the synthesized compounds on mouse fibroblast cell line (L929) was simultaneously evaluated as control. The pharmacological results showed that deferasirox and its two novel aminoacid derivatives were potent anticancer agents. PMID:27090924

  14. Synthesis characterization and structural investigations on lanthanon(III) chelates of tridentate Schiff bases

    International Nuclear Information System (INIS)

    The dissociation constants of O-(N-pyrrole-2-methyl imino) propanoic acid [H2PP] and O-(N-furan-2-chloroimino)ethane thiol [HFT], stability constants and thermodynamic parameters of their chelates with La(II), Ce(III), Nd(III), Sm(III), Gd(III), Tb(III), Dy(III), Ho(III) and Er(III) have been determined by Calvin-Bjerrum pH-titration techniques as modified by Irving and Rossotti in 30% (v/v) alcohol-water medium (μ=0.01 M, 0.05 M and 0.1 M NaClO4) at 25, 35 and 45degC. Solid Ln(III) chelates were characterized by molecular mass, elemental analysis, magnetic moment, conductance, 1H NMR, electronic and IR spectra. HFT-Ln(III)-chelates show 1:3 metal-ligand stoichiometry whereas H2PP-Ln(III)-chelates show 1:2 stoichiometry. Physico-chemical studies such as magnetic, IR, NMR etc. also support these geometries. HFT and H2PP are respectively monoprotic and biprotic tridentates. In view of the above facts a trigonal tricapped pyramidal and octahedral geometries can be assigned to the HFT-Ln(III) and H2PP-Ln(III) chelates respectively. (author). 15 refs., 4 tabs., 1 fig

  15. A study of intracellular iron metabolism using pyridoxal isonicotinoyl hydrazone and other synthetic chelating agents

    International Nuclear Information System (INIS)

    Rabbit reticulocytes with a high level of non-heme radioiron induced by preincubation with isonicotinic acid hydrazide and transferrin-bound 59Fe, were reincubated with various synthetic chelating agents and the amount of radioiron released from the cells was determined. Some substances, especially derivatives of pyridoxal or 2-hydroxybenzaldehyde and isonicotinic acid hydrazide or benzhydrazide, were found to mobilize significantly iron from 59Fe-labelled reticulocytes. Iron mobilizaiton from reticulocytes by pyridoxal isonicotinoyl hydrazone requires ATP to be produced by cells and is completely blocked by low temperatute (40C). Although the effect of desferrioxamine is also prevented by low temperature, modest iron mobilization due to this chelator seems to occur independently of ATP production in reticulocytes. Pyridoxal isonicotinoyl hydrazone mobilized iron mainly from mitochondria and in part also from ferritin. Although 2,2'-bipyridine seems to enter reticulocyte mitochondria and bind iron there, this chelator is not able to relaease iron either from mitochondria or from the cells. Reticulocytes with a high level of non-heme radioiron are envisaged as a useful system for testing biological effectiveness of various iron chelators. Pyridoxal isonicotinoyl hydrazone was shown to be an effective in vivo chelator since its adminstration to mice decreased 59Fe radioactivity in liver, spleen and kidney. (Auth.)

  16. 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. PMID:26856546

  17. Bis(thiosemicarbazonato) chelates of Co(II), Ni(II), Cu(II), Pd(II) and Pt(II)

    Science.gov (United States)

    Chandra, Sulekh; Singh, R.

    1985-01-01

    Bis chelates of Co(II), Ni(II), Cu(II), Pd(II) and Pt(II) with the enolic form of diethyl ketone and methyl n-propyl thiosemicarbazones were synthesized and characterized by elemental analyses, magnetic moments, i.r. and electronic and electron spin resonance spectral studies. All the complexes were found to have the composition ML 2 [where M = Co(II), Ni(II), Cu(II), Pd(ii) and Pt(II) and L = thiosemicarbazones of diethyl ketone and methyl n-propyl ketone]. Co(II) and Cu(II) complexes are paramagnetic and may have polymeric six-coordinate octahedral and square planar geometries, respectively. The Ni(II), Pd(II) and Pt(II) complexes are diamagnetic and may have square planar geometries. Pyridine adducts (ML 2·2Py) of Ni(II) and Cu(II) complexes were also prepared and characterized.

  18. 78 FR 73819 - Forest Resource Coordinating Committee

    Science.gov (United States)

    2013-12-09

    ... Forest Service Forest Resource Coordinating Committee AGENCY: Forest Service, USDA. ACTION: Notice of...-18, 2013 meeting of the Forest Resource Coordinating Committee due to the Government partial shutdown... INFORMATION CONTACT: Maya Solomon, Forest Resource Coordinating Committee Program Coordinator; by phone...

  19. Solution thermodynamic evaluation of hydroxypyridinonate chelators 3,4,3-LI(1,2-HOPO) and 5-LIO(Me-3,2-HOPO) for UO{sub 2}(VI) and Th(IV) decorporation

    Energy Technology Data Exchange (ETDEWEB)

    Sturzbecher-Hoehne, M.; Deblonde, G.J.P.; Abergel, R.J. [Lawrence Berkeley National Laboratory, CA (United States). Chemical Sciences Div.

    2013-08-01

    Solution thermodynamic studies were performed to characterize the coordination of U(VI) and Th(IV) by the multidentate hydroxypyridinonate chelating agents 3,4,3-LI(1,2-HOPO) and 5-LIO(Me-3,2-HOPO). Species distribution and conditional stability pM profiles were calculated based on the determined formation constants, showing that both ligands form extremely stable uranyl and thorium complexes in solution. At physiological pH, the formation of 1:1 ligand:uranyl complexes is favored for both ligands, while a 2:1 ligand:thorium complex is predominant with the tetradentate 5-LIO(Me-3,2-HOPO). Comparisons with functionally similar bidentate ligands as well as with the common actinide chelator diethylenetriamine pentaacetic acid emphasized the superior affinity for U(VI) and Th(IV) of both experimental compounds over a wide pH range. These analytical results corroborate the in vivo chelation efficacy of 3,4,3-LI(1,2-HOPO) and 5-LIO(Me-3,2-HOPO) and validate their selection for further development as therapeutic actinide decorporation agents. (orig.)

  20. Coordinate transformations in quaternion spaces

    OpenAIRE

    Weng, Zihua

    2008-01-01

    The quaternion spaces can be used to describe the property of electromagnetic field and gravitational field. In the quaternion space, some coordinate transformations can be deduced from the feature of quaternions, including Lorentz transformation and Galilean transformation etc., when the coordinate system is transformed into others. And some coordinate transformations with variable speed of light can be obtained in the electromagnetic field and gravitational field.

  1. Enterprise Coordination on the Internet

    OpenAIRE

    Charles Petrie

    2011-01-01

    Enterprises are now connected internally and externally to other Enterprises via the Internet in ways that are increasingly difficult to manage, especially as these interconnections become more dynamic. Current methods of coordinating the effects of change as they propagate through these networks of connections are not likely to scale. What is needed is a new paradigm for how the Internet supports such coordination. Indeed, the Internet should and could provide fundamental coordination functi...

  2. Child Labor and Coordination Failures

    OpenAIRE

    Sylvain Dessy; Stephane Pallage

    2000-01-01

    In this paper, we show how coordination failures may explain the prevalence of child labor in developing countries. We do so within a simple game-theoretic setup. Child labor arises in our environment because of the lack of a coordination mechanism between parental decisions to invest in the human capital of their children and firm's decisions to invest in skill-intensive technology. Governmental policies that help coordinate expectations lead to the disappearance of child labor.

  3. Fluorescence enhancement by chelation of Eu3+ and Tb3+ ions in sol-gels

    International Nuclear Information System (INIS)

    Chelation of rare-earth (RE) ions is investigated as a means of enhancing the optical properties of RE-doped silica sol-gels. Two chelating agents--2,6-pyridine-dicarboxylic acid (PDC) and 3-pyridinepropionic acid (PPA) and two different synthesis techniques are studied. Eu(PDC) gels exhibit intense 5D0→7F2 fluorescence in the red under UV excitation and long fluorescence lifetimes compared to Eu(PPA) gels and to gels without a chelating agent. This behavior indicates that the PDC molecule remains associated with the Eu after incorporation into the gel. Similar behavior is seen for 5D4→7F5 green fluorescence in Tb(PDC)

  4. Mixed Intramolecular Hydrogen Bonding in Dihydroxythiophene-based Units and Boron and Technetium Chelation

    International Nuclear Information System (INIS)

    Three novel potential metal ion chelating units have been synthesized and characterized: 5-hexylcarbamoyl- 3,4-dihydroxythiophene-2-carboxylic acid methyl ester (5), 3-benzyloxy-4-hydroxythiophene-2,5-dicarboxylic acid bis-hexylamide (6), and 3,4-dihydroxythiophene-2,5-dicarboxylic acid bis-hexylamide (7). The crystal structure of 6 was obtained and suggests the presence of three distinct intramolecular hydrogen bonds, namely [Namide-H···O] [O-H···Oamide] and [Namide-H···S]. Boron chelation with 5, 6 and 7 through the use of BF3, B(OH)3 or B(OMe)3 was probed by 1H, 11B, and 13C NMR spectroscopy. Technetium (I) chelation with 5, 6 and 7 was also studied via HPLC elutions using [99mTc(CO)3(OH2)3]+

  5. 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.

  6. High-throughput assay comparison and standardization for metal chelating capacity screening: A proposal and application.

    Science.gov (United States)

    Santos, Jânio Sousa; Alvarenga Brizola, Vitor Rafael; Granato, Daniel

    2017-01-01

    Aiming to standardize the experimental protocols to assess the ability to chelate Fe(2+) and Cu(2+) using 96-well microplates, we analyzed Brazilian coffees (n=20) as a study-case in relation to their antioxidant activity using conventional methods (DPPH and FRAP assays) and correlated the results with the total phenolic content (TPC) using bivariate and multivariate statistical approaches. Complementarily, we assessed the repeatability, reproducibility, recovery, and linearity of both methods. Data showed that the proposed assays presented a good repeatability and reproducibility (assays, respectively. Both methods were linear in the range of 0-100mg EDTA equivalents/L. Cu(2+)-chelating ability was significantly correlated to FRAP, DPPH, and TPC, while sparse (passays can be used to assess the ability of plant-based extracts to chelate Fe(2+) and Cu(2+)in vitro. PMID:27507505

  7. Overview of guidelines on iron chelation therapy in patients with myelodysplastic syndromes and transfusional iron overload.

    Science.gov (United States)

    Gattermann, Norbert

    2008-07-01

    Between 2002 and 2008, a number of consensus statements and guidelines were developed by various groups around the world to educate healthcare professionals on the treatment of myelodysplastic syndromes (MDS), including the management of transfusional iron overload with iron chelation therapy. Guidelines have been developed by The Italian Society of Hematology, The UK MDS Guidelines Group, The Nagasaki Group, The National Comprehensive Cancer Network, and The MDS Foundation. These guidelines show that the approaches to managing iron overload in patients with MDS are region specific, differing in their recommendations for when iron chelation therapy should be initiated and strategies for the ongoing management of iron overload. The guidelines all agree that red blood cell transfusions are clinically beneficial to treat the symptomatic anemia in MDS, and that patients with low-risk MDS receiving transfusions are the most likely to benefit from iron chelation therapy. PMID:18581200

  8. Heavy metal induced oxidative stress & its possible reversal by chelation therapy.

    Science.gov (United States)

    Flora, S J S; Mittal, Megha; Mehta, Ashish

    2008-10-01

    Exposure to heavy metals is a common phenomenon due to their environmental pervasiveness. Metal intoxication particularly neurotoxicity, genotoxicity, or carcinogenicity is widely known. This review summarizes our current understanding about the mechanism by which metalloids or heavy metals (particularly arsenic, lead, cadmium and mercury) induce their toxic effects. The unifying factor in determining toxicity and carcinogenicity for all these metals is the generation of reactive oxygen and nitrogen species. The toxic manifestations of these metals are caused primarily due to imbalance between pro-oxidant and antioxidant homeostasis which is termed as oxidative stress. Besides these metals have high affinity for thiol groups containing enzymes and proteins, which are responsible for normal cellular defense mechanism. Long term exposure to these metals could lead to apoptosis. Signaling components affected by metals include growth factor receptors, G-proteins, MAP kinases and transcription factors. Chelation therapy with chelating agents like calcium disodium ethylenediamine tetra acetic acid (CaNa(2)EDTA), British Anti Lewisite (BAL), sodium 2,3-dimercaptopropane 1-sulfonate (DMPS), meso 2,3-dimercaptosuccinic acid (DMSA) etc., is considered to be the best known treatment against metal poisoning. Despite many years of research we are still far away from effective treatment against toxicity caused due to exposure to heavy metals/metalloids. The treatment with these chelating agents is compromised with number of serious side-effects. Studies show that supplementation of antioxidants along-with a chelating agent prove to be a better treatment regimen than monotherapy with chelating agents. This review attempts a comprehensive account of recent developments in the research on heavy metal poisoning particularly the role of oxidative stress/free radicals in the toxic manifestation, an update about the recent strategies for the treatment with chelating agents and a

  9. Novel "hybrid" iron chelators derived from aroylhydrazones and thiosemicarbazones demonstrate selective antiproliferative activity against tumor cells.

    Science.gov (United States)

    Lovejoy, David B; Richardson, Des R

    2002-07-15

    We previously demonstrated that 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone (311) and other aroylhydrazone chelators possess potent antineoplastic activity because of their ability to bind iron (Fe). From these studies, we identified structural components of the hydrazones that provide antineoplastic activity, namely the salicylaldehyde and 2-hydroxy-1-naphthylaldehyde moieties. A related group of chelators known as the thiosemicarbazones also show pronounced antitumor activity because of their ability to inhibit ribonucleotide reductase. Considering this, we designed a new series of "hybrid ligands" by condensation of the aldehydes described above with a range of thiosemicarbazides. The parent compound of these ligands is 2-hydroxy-1-naphthylaldehyde thiosemicarbazone (NT). Of 8 NT analogues, 3 chelators, namely NT, N4mT (2-hydroxy-1-naphthylaldehyde-4-methyl-3-thiosemicarbazone), and N44mT (2-hydroxy-1-naphthylaldehyde-4,4-dimethyl-3-thiosemicarbazone), showed high antiproliferative activity against SK-N-MC neuroepithelioma cells (50% inhibitory concentration [IC(50)] = 0.5-1.5 microM). Indeed, their activity was significantly (P <.0001) greater than that of desferrioxamine (DFO) (IC(50) = 22 microM). We demonstrate that 311, a 311 analogue (311m), and several NT-series chelators have significantly (P <.001) greater antiproliferative activity against tumor cells than against a range of normal cell types. For example, the IC(50) values of NT and N4mT in SK-N-MC neuroepithelioma cells were 0.5 microM, whereas for fibroblasts the IC(50) values were greater than 25 microM. Further, the effect of one of the most potent chelators (311m) on preventing the growth of bone marrow stem cell cultures was far less than that of doxorubicin and similar to that of cisplatin. These studies support the further development of these chelators as antiproliferative agents. PMID:12091363

  10. 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.

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

    International Nuclear Information System (INIS)

    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 Ca2+, Cu2+ and Mn2+ 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

  12. On Coordinating Collaborative Objects

    Directory of Open Access Journals (Sweden)

    Abdessamad Imine

    2010-07-01

    Full Text Available A collaborative object represents a data type (such as a text document designed to be shared by a group of dispersed users. The Operational Transformation (OT is a coordination approach used for supporting optimistic replication for these objects. It allows the users to concurrently update the shared data and exchange their updates in any order since the convergence of all replicas, i.e. the fact that all users view the same data, is ensured in all cases. However, designing algorithms for achieving convergence with the OT approach is a critical and challenging issue. In this paper, we propose a formal compositional method for specifying complex collaborative objects. The most important feature of our method is that designing an OT algorithm for the composed collaborative object can be done by reusing the OT algorithms of component collaborative objects. By using our method, we can start from correct small collaborative objects which are relatively easy to handle and incrementally combine them to build more complex collaborative objects.

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

    OpenAIRE

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

    2007-01-01

    The final step in heme biosynthesis, insertion of ferrous iron into protoporphyrin IX, is catalyzed by protoporphyrin IX ferrochelatase (E.C. 4.99.1.1). It is demonstrated that the pre-steady state human ferrochelatase (R115L) shows a stoichiometric burst of product formation and substrate consumption, consistent with a rate determining step following metal-ion chelation. Detailed analysis shows that chelation requires at least two steps, rapid binding followed by a slower (k ca. 1 s−1) irrev...

  14. Chelation of Schiff bases with rare earth metal ions - thermodynamic study

    International Nuclear Information System (INIS)

    Chelating tendencies of 5-chloro-orthohydroxy acetophenone-p-chloro phenyl anil and 5-chloro-orthohydroxy acetophenone-p-bromo phenyl anil towards the f-block metal ions have been investigated potentiometrically at various temperatures in 60:40 ethanol-water medium and 0.1M (NaClO4) ionic strength. Formation of 1:1 and 1:2 chelates was detected. Thermodynamic parameters for metal-ligand stability constants have been obtained by the temperature coefficie nt method. (author). 7 refs

  15. The development of diabetes mellitus and chronic liver disease in long term chelated beta thalassaemic patients.

    OpenAIRE

    De Sanctis, V.; D'Ascola, G; Wonke, B

    1986-01-01

    We studied 29 patients with thalassaemia major who had received intensive chelation for between 6.2 and 8.8 years. All patients had normal oral glucose tolerance tests before subcutaneous chelation therapy was introduced and 22 of 29 patients had normal liver function tests. At the end of the period of study 12 patients still had normal oral glucose tolerance (7 with normal liver function tests and 5 with chronic active hepatitis). On the other hand, 11 patients had developed impaired glucose...

  16. Studies of inclusion complexes between cyclodextrins and polyazamacrocyclic chelates of lanthanide (III) ions

    OpenAIRE

    Henriques, Elsa S.; Bastos, Margarida; Geraldes, Carlos F. G. C.; Ramos, Maria João

    2003-01-01

    The complexes between [gamma]-cyclodextrin and lanthanide (III) chelates of the polyazamacrocycles DOTA (DOTA [reverse not equivalent] 1,4,7,10-tertraazacyclododecane-1,4,7,10-tetraacetate) and DOTP (DOTP [reverse not equivalent] 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylenephosphonate) have been thought out to enhance the potential of such chelates as contrast agents for MRI. Given the actual demand for the design of new contrast agents, we thought it worthwhile to confirm previous ...

  17. Synthesis, characterization and biological studies of 1,7- dinaphthyl heptanoids and their metal chelates

    OpenAIRE

    S. Sindhu; Seena Thomachan; V D John

    2015-01-01

    The present investigation includes the synthesis, characterization, antitumour and antimicrobial activities of three new curcuminoid analogues and their metal chelates. Curcuminoid analogues and their metal chelates have great ability to act as antitumour and antimicrobial agents which motivated us and lead to this present work. The new curcuminoid analogues namely 1,7-di(1-naphthyl)-1,6-heptadiene-3,5-dione (1a), 1,7-di(2-methoxy 1-naphthyl)-1,6-heptadiene-3,5-dione (1b), 1,7-di(2-hydroxy ...

  18. Analysis of hydrosoluble organic chelating agents. Potentialities of capillary electrophoresis and ionic chromatography

    International Nuclear Information System (INIS)

    Capillary electrophoresis and ion exchange chromatography are good techniques for the determination of organic chelating agents as mono or poly-carboxylates. Ion exchange chromatography allows to obtain very high sensitivities (a few μg/L). Capillary electrophoresis generates practically none analytical waste; this technique is then very interesting for nuclear industry. This microanalysis technique has been here carried out for the determination of organic chelating agents in leaching water of an old waste for which an important release rate of radio-toxic metals had been found. Thus, formate and especially acetate ions have been correlated with this unusual behaviour

  19. DCCP and DICP: Construction and Analyses of Databases for Copper- and Iron-Chelating Proteins

    Institute of Scientific and Technical Information of China (English)

    Hao Wu; Yan Yang; Sheng-Juan Jiang; Ling-Ling Chen; Hai-Xia Gao; Qing-Shan Fu; Feng Li; Bin-Guang Ma; Hong-Yu Zhang

    2005-01-01

    Copper and iron play important roles in a variety of biological processes, especially when being chelated with proteins. The proteins involved in the metal binding,transporting and metabolism have aroused much interest. To facilitate the study on this topic, we constructed two databases (DCCP and DICP) containing the known copper- and iron-chelating proteins, which are freely available from the website http:∥sdbi.sdut.edu.cn/en. Users can conveniently search and browse all of the entries in the databases. Based on the two databases, bioinformatic analyses were performed, which provided some novel insights into metalloproteins.

  20. Removal of cobalt- and mercury-EDTA chelates from aqueous solutions with a macroporous char

    International Nuclear Information System (INIS)

    A bench-scale method was developed to remove cobalt- and mercury-EDTA chelates from water onto macroporous char. Experimental parameters included variations on solution pH, char pre-treatment, cobalt oxidation state, and apparatus configuration. The use of 60Co and 203Hg radiotracers allowed for total accountability of the metals in the char and effluents. Overall experimental results demonstrate the applicability of treated macroporous chars for the effective removal of both cobalt and mercury EDTA chelates from aqueous solutions. The char system was optimized to sequester 97.5% and 99.8% of the cobalt- and mercury-EDTA from 20 ppm solutions, respectively. (author)

  1. The synthesis of macroreticular chelating resins containing amidoxime groups and their properties of recovery of uranium

    International Nuclear Information System (INIS)

    Macroreticular chelating resins containing amidoxime groups were successfully synthesized with divinyl benzene (DVB) cross-linking acrylonitrile (AN) copolymer beads as skeleton by suspension polymerization. Influence factors of DVB-AN beads' amidoxime reaction, such as reaction medium, reaction ratio, reaction temperature and time etc. were studied in detail. Copolymer and chelating resins with amidoxime groups having different physical properties and monomer composition were prepared successfully. The factors affecting resin chemical adsorption capacity, such as cross-linking agent, reticulating agent and polar monomer etc. were also explored. The resins had chemical adsorption capacity over 4.0 mmol/g (dry), and ideal results of recovered uranium under the conditions as described

  2. Synthesis and Analytical Study of New Chelating Resin Containing Sulfadiazine Drug

    OpenAIRE

    Madher N. Abdulla

    2010-01-01

    A new chelating resin was prepared by mixing sulfadiazine drug and TMP (trimethylolphenol). It was polymerized by heating to 90 °C then it was post cured to 100 °C after that it was grinded. The chelating behavior was examined against Cu2+, Ni2+ using patch method in deferent conditions like treatment time and pH at room temperature. The resin show a good loading capacity toward Cu2+ (in treatment time = 3 h & pH=4) = 0.2174 mg ion / 100 mg resin and it show good loading capacity toward Ni2+ ...

  3. 75 FR 55947 - Coordinated Communications

    Science.gov (United States)

    2010-09-15

    ... Proposed Rulemaking on Coordinated Communications, 75 FR 6590 (Feb. 10, 2010). The SNPRM invited comments..., 68 FR at 427. The first content standard was satisfied if the communication was an electioneering... Proposed Rulemaking on Coordinated ] Communications, 70 FR 73946 (Dec. 14, 2005) (``2005 NPRM'')....

  4. Coordinated Transportation: Problems and Promise?

    Science.gov (United States)

    Fickes, Michael

    1998-01-01

    Examines the legal, administrative, and logistical barriers that have prevented the wide acceptance of coordinating community and school transportation services and why these barriers may be breaking down. Two examples of successful implementation of coordinated transportation are examined: employing a single system to serve all transportation…

  5. Coordinate-Free Rotation Operator.

    Science.gov (United States)

    Leubner, C.

    1979-01-01

    Suggests the use of a coordinate-free rotation operator for the teaching of rotations in Euclidean three space because of its twofold didactic advantage. Illustrates the potentialities of the coordinate-free rotation operator approach by a number of examples. (Author/GA)

  6. Coordination of Conditional Poisson Samples

    Directory of Open Access Journals (Sweden)

    Grafström Anton

    2015-12-01

    Full Text Available Sample coordination seeks to maximize or to minimize the overlap of two or more samples. The former is known as positive coordination, and the latter as negative coordination. Positive coordination is mainly used for estimation purposes and to reduce data collection costs. Negative coordination is mainly performed to diminish the response burden of the sampled units. Poisson sampling design with permanent random numbers provides an optimum coordination degree of two or more samples. The size of a Poisson sample is, however, random. Conditional Poisson (CP sampling is a modification of the classical Poisson sampling that produces a fixed-size πps sample. We introduce two methods to coordinate Conditional Poisson samples over time or simultaneously. The first one uses permanent random numbers and the list-sequential implementation of CP sampling. The second method uses a CP sample in the first selection and provides an approximate one in the second selection because the prescribed inclusion probabilities are not respected exactly. The methods are evaluated using the size of the expected sample overlap, and are compared with their competitors using Monte Carlo simulation. The new methods provide a good coordination degree of two samples, close to the performance of Poisson sampling with permanent random numbers.

  7. Characterization of radionuclide-chelating agent complexes found in low-level radioactive decontamination waste. Literature review

    International Nuclear Information System (INIS)

    The US Nuclear Regulatory Commission is responsible for regulating the safe land disposal of low-level radioactive wastes that may contain organic chelating agents. Such agents include ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), picolinic acid, oxalic acid, and citric acid, and can form radionuclide-chelate complexes that may enhance the migration of radionuclides from disposal sites. Data from the available literature indicate that chelates can leach from solidified decontamination wastes in moderate concentration (1--100 ppm) and can potentially complex certain radionuclides in the leachates. In general it appears that both EDTA and DTPA have the potential to mobilize radionuclides from waste disposal sites because such chelates can leach in moderate concentration, form strong radionuclide-chelate complexes, and can be recalcitrant to biodegradation. It also appears that oxalic acid and citric acid will not greatly enhance the mobility of radionuclides from waste disposal sites because these chelates do not appear to leach in high concentration, tend to form relatively weak radionuclide-chelate complexes, and can be readily biodegraded. In the case of picolinic acid, insufficient data are available on adsorption, complexation of key radionuclides (such as the actinides), and biodegradation to make definitive predictions, although the available data indicate that picolinic acid can chelate certain radionuclides in the leachates

  8. High-performance liquid chromatography method for ferric iron chelators using a post-column reaction with Calcein Blue.

    Science.gov (United States)

    Ariga, Tomoko; Ito, Kyoko; Imura, Yuki; Yoshimura, Etsuro

    2015-03-15

    Iron (Fe) is an essential element for higher plants, which take it up from the soil at the root surface and transport it to shoots through the xylem. Fe(III) chelators, such as organic acids and phytosiderophores, play important roles in the acquisition and transportation of Fe(III). Therefore, a selective and sensitive method for analyzing Fe(III) chelators is required to study the many Fe-related physiological mechanisms in plants. A novel analytical approach employing a high-performance liquid chromatography post-column method with fluorescence detection was developed to separate and detect Fe(III) chelators. This method takes advantage of the quenching of the fluorescence of Calcein Blue (CB) that occurs with the formation of an Fe(III)-CB complex and the dequenching that occurs with the release of CB as a result of competition for Fe(III) between CB and an Fe(III) chelator. This simple experimental method does not require complicated pretreatments and can selectively detect Fe(III) chelators according to their Fe(III)-chelating ability. The detection limit for citric acid using this method was 72pmol. Furthermore, this method can also detect unknown Fe(III) chelators that exhibit a high affinity for Fe(III). The method was evaluated with xylem sap of barley, which was shown to contain several Fe(III) chelators. PMID:25658515

  9. Synergistic Activities of an Efflux Pump Inhibitor and Iron Chelators against Pseudomonas aeruginosa Growth and Biofilm Formation

    DEFF Research Database (Denmark)

    Liu, Yang; Yang, Liang; Molin, Søren

    2010-01-01

    The efflux pump inhibitor phenyl-arginine-beta-naphthylamide (PA beta N) was paired with iron chelators 2,2'-dipyridyl, acetohydroxamic acid, and EDTA to assess synergistic activities against Pseudomonas aeruginosa growth and biofilm formation. All of the tested iron chelators synergistically...

  10. Characterization of radionuclide-chelating agent complexes found in low-level radioactive decontamination waste. Literature review

    Energy Technology Data Exchange (ETDEWEB)

    Serne, R.J.; Felmy, A.R.; Cantrell, K.J.; Krupka, K.M.; Campbell, J.A.; Bolton, H. Jr.; Fredrickson, J.K. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-03-01

    The US Nuclear Regulatory Commission is responsible for regulating the safe land disposal of low-level radioactive wastes that may contain organic chelating agents. Such agents include ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), picolinic acid, oxalic acid, and citric acid, and can form radionuclide-chelate complexes that may enhance the migration of radionuclides from disposal sites. Data from the available literature indicate that chelates can leach from solidified decontamination wastes in moderate concentration (1--100 ppm) and can potentially complex certain radionuclides in the leachates. In general it appears that both EDTA and DTPA have the potential to mobilize radionuclides from waste disposal sites because such chelates can leach in moderate concentration, form strong radionuclide-chelate complexes, and can be recalcitrant to biodegradation. It also appears that oxalic acid and citric acid will not greatly enhance the mobility of radionuclides from waste disposal sites because these chelates do not appear to leach in high concentration, tend to form relatively weak radionuclide-chelate complexes, and can be readily biodegraded. In the case of picolinic acid, insufficient data are available on adsorption, complexation of key radionuclides (such as the actinides), and biodegradation to make definitive predictions, although the available data indicate that picolinic acid can chelate certain radionuclides in the leachates.

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    Iron chelation is essential to patients on chronic blood transfusions to prevent toxicity from iron overload and remove excess iron. Deferasirox (DFX) is the most commonly used iron chelator in the United States; however, some patients are relatively refractory to DFX therapy. We postulated that ...

  12. The fabrication and study of metal chelating stationary phases for the high performance separation of metal ions

    International Nuclear Information System (INIS)

    The preparation and characterisation of chelating sorbents suitable for the high efficiency separation of trace metals in complex samples, using a single column and isocratic elution, is described. Hydrophobic, neutral polystyrene divinylbenzene resins were either impregnated with chelating dyes or dynamically modified with heterocyclic organic acids, using physical adsorption and chemisorption processes respectively. A hydrophilic silica substrate was covalently bonded with a chelating aminomethylphosphonic acid group, to assess the chelating potential of this molecule. These substrates were characterised in terms of metal retention capability (selectivity coefficients and capacity factors), separation performance, column efficiency and suitability for analytical applications. Chelating molecules with different ligand groups were found to have unique selectivity patterns dependant upon the conditional stability constants of the chelate. Other factors, including mobile phase constituents - complexing agents, ionic strength and pH, column length and column capacity were additionally investigated to examine their effect upon the separation profiles achieved. The promising metal separation abilities illustrated by a number of these chelating columns were exploited for the determination of trace toxic metals in complex sample matrices using High Performance Chelation Ion Chromatography (HPCIC). This included the determination of beryllium in a certified stream sediment, uranium in seawater and a certified stream sediment, and cadmium, lead and copper in a certified rice flour. The results for each analysis fell within the certified limits, and reproducibility was good. The optimisation of post column detection systems using chromogenic ligands additionally gave good detection limits for the metals in each separation system. (author)

  13. Archimedes' principle in general coordinates

    International Nuclear Information System (INIS)

    Archimedes' principle is well known to state that a body submerged in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the body. Herein, Archimedes' principle is derived from first principles by using conservation of the stress-energy-momentum tensor in general coordinates. The resulting expression for the force is applied in Schwarzschild coordinates and in rotating coordinates. Using Schwarzschild coordinates for the case of a spherical mass suspended within a perfect fluid leads to the familiar expression of Archimedes' principle. Using rotating coordinates produces an expression for a centrifugal buoyancy force that agrees with accepted theory. It is then argued that Archimedes' principle ought to be applicable to non-gravitational phenomena, as well. Conservation of the energy-momentum tensor is then applied to electromagnetic phenomena. It is shown that a charged body submerged in a charged medium experiences a buoyancy force in accordance with an electromagnetic analogue of Archimedes' principle.

  14. Modelling chelate-Induced phytoextraction: functional models predicting bioavailability of metals in soil, metal uptake and shoot biomass

    Directory of Open Access Journals (Sweden)

    Pasqualina Sacco

    Full Text Available Chelate-induced phytoextraction of heavy metals from contaminated soils requires special care to determine, a priori, the best method of chelate application, in terms of both dose and timing. In fact, the chelate dose must assure the bioavailability of the metal to the plant without increasing leaching risk and giving toxic effects. Three mathematical models are here proposed for usefully interpreting the processes taking place: a increased soil bioavailability of metals by chelants; b metal uptake by plants; c variation in plant biomass. The models are implemented and validated using data from pot and lysimeter trials. Both the chelate dose and the time elapsed since its application affected metal bioavailability and plant response. Contrariwise, the distribution strategy (single vs. split application seems to produce significant differences both in plant growth and metal uptake, but not in soil metal bioavailability. The proposed models may help to understand and predict the chelate dose – effect relationship with less experimental work.

  15. Spectral, magnetic and antifungal activities of some novel lanthanon chelates of Schiff bases containing oxygen and nitrogen donor atoms

    International Nuclear Information System (INIS)

    Lanthanon chelates of the type (LnL2) and (LnL3) where Ln = La(III), Pr(III), Nd(III), Sm(III), Ho(III) and Er(III) and L = acetylacetonethiosemicarbazide (AAS) and L' = benzoylacetonethiosemicarbazide (BAS) have been isolated in solid state and are characterized by their spectral, magnetic and antifungal activities. The electronic spectra of these chelates have been analyzed in the light of LSJ terms and involving characteristic f - f transitions. The ligands and their resulting chelates have been shown to be toxic against the two pathogenic fungi, viz., Aspargillus niger and Draschelara australiensis and the results revealed that the toxicity decreases on chelation or metallation. Overall, the benzoylacetonesemicarbazide lanthanon chelates are more toxic to fungi than the corresponding lanthanon derivatives of acetylacetonesemicarbazide. (author)

  16. A Comparison of Methods Used to Evaluate Intakes of Transuranics Influenced by Chelation Therapy

    International Nuclear Information System (INIS)

    A comparison of methods is used to evaluate the intake of transuranics influenced by chelation therapy. The purpose of this paper is to introduce the mechanistic method by using it to validate Hall's method and Jech's method. This is accomplished by using the mechanistic method to generate a known set of data suitable for benchmarking all three methods

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

    International Nuclear Information System (INIS)

    The overall objectives of this project were to gain a fundamental understanding of the solubility and phase behavior of metal chelates in supercritical CO2. Extraction with CO2 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 CO2 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 CO2 and CO2/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 CO2 and CO2/co-contaminant mixtures. Thus, they can now design and optimize processes to extract metals from solid matrices using supercritical CO2, as an alternative to hazardous organic solvents that create their own environmental problems, even while helping in metals decontamination

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

    International Nuclear Information System (INIS)

    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)

  19. [Remediation of Cu-Pb-contaminated loess soil by leaching with chelating agent and biosurfactant].

    Science.gov (United States)

    Liu, Xia; Wang, Jian-Tao; Zhang, Meng; Wang, Li; Yang, Ya-Ti

    2013-04-01

    Because of its strong chelation, solubilization characteristics, the chelating agents and biosurfactant are widely used in remediation of heavy metals and organic contaminated soils. Ethylenediamine tetraacetic acid (EDTA), citric acid (CIT) and dirhamnolipid (RL2) were selected as the eluent. Batch experiments and column experiments were conducted to investigate the leaching effect of the three kinds of eluent, as well as the mixture of biosurfactant and chelating agent for Cu, Pb contaminated loess soil. The results showed that the leaching efficiencies of different eluent on Cu, Pb contaminated loess soil followed the sequence of EDTA > CIT > RL2. At an eluent concentration of 0.02 mol x L(-1), the Cu leaching efficiency was 62.74% (EDTA), 52.28% (CIT) and 15.35% (RL2), respectively; the Pb leaching efficiency was 96.10% (EDTA), 23.08% (CIT) and 14.42% (RL2), respectively. When the concentration of RL2 was 100 CMC, it had synergistic effects on the other two kinds of chelating agent in Cu leaching, and when the concentration of RL2 was 200 CMC, it had antagonism effects. The effect of RL2 on EDTA in Pb leaching was similar to that in Cu leaching. Pb leaching by CIT was inhibited in the presence of RL2. EDTA and CIT could effectively remove Cu and Pb in exchangeable states, adsorption states, carbonate salts and organic bound forms; RL2 could effectively remove Cu and Pb in exchangeable and adsorbed states. PMID:23798147

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

    Science.gov (United States)

    Downey, D. M.; And Others

    1984-01-01

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

  1. Metal Ions Extraction with Glucose Derivatives as Chelating Reagents in Supercritical Carbon Dioxide

    Institute of Scientific and Technical Information of China (English)

    Guo Chen YANG; Hai Jian YANG

    2006-01-01

    A series of glucose derivatives have been used as chelating reagents to extract metal ions in supercritical carbon dioxide. With perfluoro-1-octanesulfonic acid tetraethylammonium salt as additive, glucose derivatives were selective for Sr2+ and Pb2+ extraction in supercritical carbon dioxide.

  2. The Mechanism of Cumene Peroxidation Catalyzed by Cobalt(Ⅱ)-Chelated Copolymer

    Institute of Scientific and Technical Information of China (English)

    Cheng-Chien Wang; Hui-Chun Chen; Chuh-Yean Chen; Chuh-Yung Chen

    2005-01-01

    @@ 1Introduction The functionalised polymers, especially for chelating polymer, have been employed to considerable effects in organic synthesis for several decades. The use of polymer groups as ligands permits the ligand surroundings to be varied and regulation of the catalytic properties of the complexes because of the flexibility of the polymer chains, their ability to adopt various conformations, and the possibility of creating various spatial distributions of metal centers immobilized on the polymer chains[1,2]. In our recently studies[3-5], the chelating copolymer with imino-diacetic acid chelating group in the polymer side chain was manufactured, and which can increase effectively amount of the chelating group within the polymer. Meanwhile, the high catalysis performance in organic synthesis had also been proved via benzaldehyde and cumene peroxidation. For cumene peroxidation,it is hardly to find such a simple catalyst with high conversion and selectivity due to hydroperoxide decomposition by a radical mechanism. The cumene peroxidation by catalyst system and its reaction mechanism as well as the kinetic study are popularly investigated object for many researchers[6-9]. However, the reaction mechanism still does not clear owing to the by-products will be produced following the different catalysts used.

  3. Modern Chemistry Techniques Applied to Metal Behavior and Chelation in Medical and Environmental Systems ? Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Sutton, M; Andresen, B; Burastero, S R; Chiarappa-Zucca, M L; Chinn, S C; Coronado, P R; Gash, A E; Perkins, J; Sawvel, A M; Szechenyi, S C

    2005-02-03

    This report details the research and findings generated over the course of a 3-year research project funded by Lawrence Livermore National Laboratory (LLNL) Laboratory Directed Research and Development (LDRD). Originally tasked with studying beryllium chemistry and chelation for the treatment of Chronic Beryllium Disease and environmental remediation of beryllium-contaminated environments, this work has yielded results in beryllium and uranium solubility and speciation associated with toxicology; specific and effective chelation agents for beryllium, capable of lowering beryllium tissue burden and increasing urinary excretion in mice, and dissolution of beryllium contamination at LLNL Site 300; {sup 9}Be NMR studies previously unstudied at LLNL; secondary ionization mass spec (SIMS) imaging of beryllium in spleen and lung tissue; beryllium interactions with aerogel/GAC material for environmental cleanup. The results show that chelator development using modern chemical techniques such as chemical thermodynamic modeling, was successful in identifying and utilizing tried and tested beryllium chelators for use in medical and environmental scenarios. Additionally, a study of uranium speciation in simulated biological fluids identified uranium species present in urine, gastric juice, pancreatic fluid, airway surface fluid, simulated lung fluid, bile, saliva, plasma, interstitial fluid and intracellular fluid.

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

    Energy Technology Data Exchange (ETDEWEB)

    J. F. Brennecke; M. A. Stadtherr

    1999-12-10

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

  5. Isolation and Utilization of Corn Cobs Hemisellulose as Chelating Agent for Lead Ions

    International Nuclear Information System (INIS)

    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 % H2O2, 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)

  6. Quenching of the triplet state of benzophenone by lanthanide 1,3-diketonate chelates in solutions

    International Nuclear Information System (INIS)

    The phosphorescence of benzophenone in benzene and acetonitrile was quenched by several lanthanide (Sm, Eu, Gd, Tb and Dy) acetylacetonate chelates. The results of Stern-Volmer analysis including the quenching of benzophenone triplet and sensitization of lanthanide emission indicate that the quenching process occurs by the energy transfer mechanism via the excited triplet state of the ligand. (Author)

  7. Organic acids rather than histidine predominate in Ni chelation in Alyssum hyperaccumulator xylem exudate

    Science.gov (United States)

    A better understanding of Ni uptake mechanisms by hyperaccumulator plants is necessary to improve Ni uptake efficiency for phytoremediation technologies i.e. phytomining. It is known that an important aspect of Ni translocation involves Ni chelation with organic ligands. However, it is still not cle...

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

    Science.gov (United States)

    Wuguo, Deng; Xingwang, Fang; Jilan, Wu

    1997-09-01

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

  9. Value of 1.0-M gadolinium chelates: review of preclinical and clinical data on gadobutrol

    International Nuclear Information System (INIS)

    Several preclinical and clinical studies with the first commercially available highly concentrated Gd-chelate gadobutrol (1 mol/l) are reviewed. Physicochemical, pharmacological, and pharmacokinetic properties, safety analysis, as well as experimental and clinical efficacy studies are highlighted in comparison with 0.5-M Gd-chelates. The 1-mol gadobutrol has been proven to be safe in an examined dose range from 0.04 up to 0.5 mmol/kg body weight (b.w.). Even in patients with chronic renal impairment, including hemodialysis, gadobutrol can safely be applied at doses up to 0.3 mmol/kg b.w. For contrast-enhanced MRI in the equilibrium phase, efficacy data analysis shows comparable results to other commercially available extracellular Gd-chelates with lower Gd-concentrations (0.5 M). Studies focused on the potential benefit of a tighter bolus, such as brain perfusion imaging using T2*-effects, document the superiority of a highly concentrated Gd contrast agent. For contrast-enhanced MRA, clinical studies are still ongoing; therefore, the ultimate potential of a more compact bolus, using 1-M Gd-chelates, for contrast-enhanced MRI, has still to be analyzed, especially for time-resolved magnetic resonance angiography. (orig.)

  10. Use of organometallic chelates in broiler diet: effect on the performance and bone structure. Preliminary results

    Directory of Open Access Journals (Sweden)

    Biagina Chiofalo

    2010-01-01

    Full Text Available On 26,000 Ross 508 broiler chickens (two groups of 13,000 per pen the effect of dietary substitution with in organic trace minerals or organometallic chelates on performances and bones tructure c trace minerals or organometallic chelates on performances and bone structure was studied. Treatments consisted of a commercial diet integrated with 0.5% of a vitamin-mineral premix containing inorganic trace minerals (CTR or organometallic chelates (MHA using Methionine Hydroxy Analog. Production performance was measured during the 52 d trial period and bone structure was evalu- ated at the slaughter (52 d. Significant (P=0.038 higher values were observed in the finishing period (41 to 52 d for the body weight of the treated group (3560 g vs. 3358 g. The same trend was observed for the ADG (MHA 87.6 g/d vs. CTR 71 g/d; P<0.05. Concerning ash percentage significant higher values were observed in the CTR group for femur (49.01% vs. 51.45%; P<0.01 and tibia (53.87% vs. 49.79%; P<0.001; femur showed also higher values for bone radiopacity (MHA 0.21 px vs. CTR 0.26 px; P=0.035. MHA group showed significant higher value for morphometric measures of the femur and tibia. Results suggest that organometallic chelates can be included in the diet without compromising broiler performance.

  11. Kinetic Studies on Forming Iso-nuclear -type Chelates of Rare Earths with p-Sulphoaminobromophosphonazo

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The kinetic behavior of forming the iso-nuclear b -type chelates of rare earth ions (RE3+) with p-sulphoaminobromophosphonazo (BPA-pSN) in ClCH2COOH-CH3COONa buffer solutions were studied by a spectrophotometric method.

  12. Synergic effect of chelating agent and oxidant on chemical mechanical planarization

    International Nuclear Information System (INIS)

    Chemically dominant alkaline slurry, which is free of BTA (benzotriazole) and other inhibitors, was investigated. The synergic effect of the chelating agent and oxidant on the chemical mechanical planarization (CMP) was taken into consideration. Copper CMP slurry is mainly composed of an oxidizer, nonionic surfactant, chelating agent and abrasive particles. The effect of different synergic ratios of oxidant with chelating agent on the polishing removal rate, static etch rate and planarization were detected. The planarization results reveal that with the increase of oxidant concentration, the dishing value firstly diminished and then increased again. When the synergic ratios is 3, the dishing increases the least. A theoretical model combined with chemical-mechanical kinetics process was proposed in the investigation, which can explain this phenomenon. Based on the theoretical model, the effect of synergic ratios of oxidant with chelating agent on velocity D-value (convex removal rate minus recessed removal rate) was analyzed. The results illustrate that when the synergic ratio is between 2.5–3.5, the velocity D-value is relatively higher, thereby good planarization can be achieved in this interval. This investigation provides a new guide to analyze and study copper line corrosion in the recessed region during copper clearing polishing. (semiconductor technology)

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Paine, R.T.

    2000-12-12

    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

  15. Keep Meaning in Conversational Coordination

    Directory of Open Access Journals (Sweden)

    Elena Clare Cuffari

    2014-12-01

    Full Text Available Coordination is a widely employed term across recent quantitative and qualitative approaches to intersubjectivity, particularly approaches that give embodiment and enaction central explanatory roles. With a focus on linguistic and bodily coordination in conversational contexts, I review the operational meaning of coordination in recent empirical research and related theorizing of embodied intersubjectivity. This discussion articulates what must be involved in treating linguistic meaning as dynamic processes of coordination. The coordination approach presents languaging as a set of dynamic self-organizing processes and actions on multiple timescales and across multiple modalities that come about and work in certain domains (those jointly constructed in social, interactive, high-order sense-making. These processes go beyond meaning at the level that is available to first-person experience. I take one crucial consequence of this to be the ubiquitously moral nature of languaging with others. Languaging coordinates experience, among other levels of behavior and event. Ethical effort is called for by the automatic autonomy-influencing forces of languaging as coordination.

  16. Coordinating distributed work: Exploring situated coordination with gaming-simulation

    NARCIS (Netherlands)

    van Laere, J.

    2003-01-01

    Organizational work has become more and more distributed nowadays. Information and communication technologies (ICT) provide opportunities to improve coordination of distributed work, but in practice many organizations struggle with integrating new organizational structures, new work practices and IC

  17. Compositional analysis of metal chelating materials using near-field photothermal Fourier transform infrared microspectroscopy.

    Science.gov (United States)

    Moffat, Jonathan G; Mayes, Andrew G; Belton, Peter S; Craig, Duncan Q M; Reading, Mike

    2010-01-01

    Photothermal-Fourier transform-infrared (PT-FT-IR) microspectroscopy employs a thermal probe mounted in a scanning probe microscope (SPM). By placement of the tip of the probe on the surface of a solid sample, it can obtain localized IR spectra of a wide range of samples. A second mode of analysis is also available; a sample can be taken from the selected location using a technique called thermally assisted nanosampling (TAN), then a spectrum can be obtained of the nanosample while the probe is remote from the surface. We report a novel method of local compositional analysis that combines both of these types of measurement; a reagent is attached to the tip using TAN, then the reagent is placed in contact with analyte. IR spectroscopy can then be used to analyze any interaction between the reagent and surface it is placed in contact with. All of these modes of analysis were illustrated using a metal chelating agent. In the surface mode, changes to a solid bead of a chelating resin were measured using standard PT-FT-IR. In the nanosampling mode of analysis, a particle of a chelating polymer was attached to the tip of the probe using TAN and this was placed in contact with a concentrated calcium solution. Strong spectral changes were observed that mirrored those found when exposing the surface bound chelating resin bead to a solution of the same ion. A semiquantitative simulation of the PT spectrum for a chelating resin bead was achieved using a thermal diffusion model derived from photoacoustic spectroscopy indicating that semiquantitative or quantitative measurements will be possible in such a system. PMID:19957959

  18. The coordinate transforming in geography information system

    International Nuclear Information System (INIS)

    The coordinate transforming of geography information system includes two kinds of transforming, map projection and coordinate-transforming. This paper proposed a arithmetic of coordinate-transforming, it implement the transforming between the longitude-latitude coordinate and the screen coordinate and apply it in the GIS. The preferable effect was made. (authors)

  19. Crystal structure of a mixed-ligand terbium(III) coordination polymer containing oxalate and formate ligands, having a three-dimensional fcu topology

    OpenAIRE

    Chainok Kittipong; Phailyn Khemthong; Filip Kielar; Yan Zhou

    2016-01-01

    The title compound, poly[(μ 3-formato)(μ 4-oxalato)terbium(III)], [Tb(CHO2)(C2O4)] n , is a three-dimensional coordination polymer, and is isotypic with the LaIII, CeIII and SmIII analogues. The asymmetric unit contains one TbIII ion, one formate anion (CHO2 −) and half of an oxalate anion (C2O4 2−), the latter being completed by application of inversion symmetry. The TbIII ion is nine-coordinated in a distorted tricapped trigonal–prismatic manner by two chelating carboxyl­ate groups from two...

  20. Evaluating the Relational Coordination instrument

    DEFF Research Database (Denmark)

    Edwards, Kasper; Lundstrøm, Sanne Lykke

    2014-01-01

    and surgical performance. This has prompted the attention of both practitioners and politicians some of who perceive relational coordination as a means to attain better performance. The relational coordination instrument has been validated as a measure of teamwork from the following perspectives......: internal consistency, interrater agreement and reliability, structural validity, content validity. However as relational coordination is being used as a diagnostics tool it is important to examine further if the instrument can measure changes. Indeed we need to know how precise and sensitive the instrument...... the change using the relational coordination instrument. Managers were interviewed before the projects and a chronicle workshop (structured group interview) were performed after the project. This design allows us to compare the qualitative descriptions of change in the wards, with the measured change...

  1. Coordination Games on Dynamical Networks

    Directory of Open Access Journals (Sweden)

    Enea Pestelacci

    2010-07-01

    Full Text Available We propose a model in which agents of a population interacting according to a network of contacts play games of coordination with each other and can also dynamically break and redirect links to neighbors if they are unsatisfied. As a result, there is co-evolution of strategies in the population and of the graph that represents the network of contacts. We apply the model to the class of pure and general coordination games. For pure coordination games, the networks co-evolve towards the polarization of different strategies. In the case of general coordination games our results show that the possibility of refusing neighbors and choosing different partners increases the success rate of the Pareto-dominant equilibrium.

  2. Who matters in coordination problems?

    Czech Academy of Sciences Publication Activity Database

    Sákovics, J.; Steiner, Jakub

    2012-01-01

    Roč. 102, č. 7 (2012), s. 3439-3461. ISSN 0002-8282 Institutional support: RVO:67985998 Keywords : coordination problems * heterogeneous agents Subject RIV: AH - Economics Impact factor: 2.792, year: 2012

  3. Markov Tracking for Agent Coordination

    Science.gov (United States)

    Washington, Richard; Lau, Sonie (Technical Monitor)

    1998-01-01

    Partially observable Markov decision processes (POMDPs) axe an attractive representation for representing agent behavior, since they capture uncertainty in both the agent's state and its actions. However, finding an optimal policy for POMDPs in general is computationally difficult. In this paper we present Markov Tracking, a restricted problem of coordinating actions with an agent or process represented as a POMDP Because the actions coordinate with the agent rather than influence its behavior, the optimal solution to this problem can be computed locally and quickly. We also demonstrate the use of the technique on sequential POMDPs, which can be used to model a behavior that follows a linear, acyclic trajectory through a series of states. By imposing a "windowing" restriction that restricts the number of possible alternatives considered at any moment to a fixed size, a coordinating action can be calculated in constant time, making this amenable to coordination with complex agents.

  4. Kaluza's theory in generalized coordinates

    CERN Document Server

    García-Perciante, A L; García-Colin, L S; Garcia-Perciante, Ana Laura; Sandoval-Villalbazo, Alfredo

    2001-01-01

    Maxwell's equations can be obtained in generalized coordinates by considering the electromagnetic field as an external agent. The work here presented shows how to obtain the electrodynamics for a charged particle in generalized coordinates eliminating the concept of external force. Based on Kaluza's formalism, the one here presented extends the 5x5 metric into a 6x6 space-time giving enough room to include magnetic monopoles in a very natural way.

  5. Coordinated Design In Urban Environments

    OpenAIRE

    KAMALI, Fereshteh Pashaei; RAZMGIR, Akramalsadat; KHOBRO, Babaksimintan; BARADARAN, Alireza Ghandriz

    2015-01-01

    Abstract. In a society in which accepting sociability, consensus and collective product are emphasized, new buildings try to coordinate themselves with the existing patterns. Edmund Bacon (1979) has searched the formation of urban landscape coordinated with manner of relation in which architects have worked in one place but in different times and by stating,the second person’s theory, emphasized that the second designer determines that whether the first architectural work is valuable or recog...

  6. Currency Areas and Monetary Coordination

    OpenAIRE

    Qing Liu; Shouyong Shi

    2006-01-01

    In this paper we integrate the recent development in monetary theory with international finance, in order to examine the coordination between two currency areas in setting long-run inflation. The model determines the value of each currency and the size of each currency area without requiring buyers to use a particular currency to buy a country's goods. We show that the two countries inflate above the Friedman rule in a non-cooperative game. Coordination between the two areas reduces inflation...

  7. Coordination Demands of International Strategies

    OpenAIRE

    Jon I Martinez; J Carlos Jarillo

    1991-01-01

    A study of fifty subsidiaries of Multinational Corporations shows a connection between their strategy and their use of different mechanisms of coordination. The main finding is that subsidiaries pursuing strategies with a high degree of integration with their corporate parent make a much more extensive use of both “formal” and “subtle” coordination mechanisms than other firms in the sample. These results are borne out in both static and dynamic tests. They confirm previous literature on coord...

  8. Consumption externalities, coordination and advertising

    OpenAIRE

    Pastine, Tuvana; Pastine, Ivan

    2001-01-01

    The aim of this Paper is to demonstrate that advertising can have an important function in markets with consumption externalities, apart from its persuasive and informative roles. We show that advertising may function as a device to coordinate consumer expectations of the purchasing decisions of other consumers in markets with consumption externalities. The implications of advertising as a coordinating device are examined in the pricing and advertising decisions of firms interacting strategic...

  9. Comsumption Externalities, Coordination, and Advertising

    OpenAIRE

    Ivan Pastine; Tuvana Pastine

    2002-01-01

    The aim of this article is to demonstrate that advertising can have an important function in markets with consumption externalities apart from its persuasive and informative roles. We show that advertising may function as a device to coordinate consumer expectations of the purchasing decisions of other consumers in markets with consumption externalities. The implications of advertising as a coordinating device are examined in the pricing and advertising decisions of firms interacting strategi...

  10. Co-ordination and specialisation

    OpenAIRE

    Egidi, Massimo; Ricottilli, Massimo

    1997-01-01

    This paper addresses the problem of division of labour as an evolutionary process in which co-ordinated agents attempt problem-solving as a search in problem space. Co-ordination stress and learning trigger adaptation but as complexity rises radical solutions are sought prompting radical organisational as well as technological change. The analytical issues involved are further explored by resorting to the so-called NKC model of evolution and co-evolution.

  11. Dynamic coordination via organizational routines

    OpenAIRE

    Blume, Andreas; April M. Franco; Heidhues, Paul

    2011-01-01

    We investigate dynamic coordination among members of a problem solving team who receive private signals about which of their actions are required for a (static) coordinated solution and who have repeated opportunities to explore different action combinations. In this environment ordinal equilibria, in which agents condition only on how their signals rank their actions and not on signal strength, lead to simple patterns of behavior that have a natural interpretation as routines. These routine ...

  12. DEVELOPMENTAL COORDINATION DISORDER IN CHILDREN

    OpenAIRE

    Saeideh MIRAFKHAMI; Seyyed Hossein FAKHRAEE; Sina MIRAFKHAMI; Mojtaba YOUSEFI; Mona VARZANDEH FAR

    2010-01-01

    ObjectiveIn this article, a motor skill disorder called developmental coordination disorder (DCD), that is usually first diagnosed during childhood, is explained and discussed. In the year 1987, DCD was formally recognized as a distinct disorder in children by the American Psychiatric Association  (APA). DCD is a generalized term for the children who have some degrees of impairment in the development of motor coordination and therefore have difficulties with physical skills which significantl...

  13. Iron Chelators and Antioxidants Regenerate Neuritic Tree and Nigrostriatal Fibers of MPP+/MPTP-Lesioned Dopaminergic Neurons

    Science.gov (United States)

    Aguirre, Pabla; Mena, Natalia P.; Carrasco, Carlos M.; Muñoz, Yorka; Pérez-Henríquez, Patricio; Morales, Rodrigo A.; Cassels, Bruce K.; Méndez-Gálvez, Carolina; García-Beltrán, Olimpo; González-Billault, Christian; Núñez, Marco T.

    2015-01-01

    Neuronal death in Parkinson’s disease (PD) is often preceded by axodendritic tree retraction and loss of neuronal functionality. The presence of non-functional but live neurons opens therapeutic possibilities to recover functionality before clinical symptoms develop. Considering that iron accumulation and oxidative damage are conditions commonly found in PD, we tested the possible neuritogenic effects of iron chelators and antioxidant agents. We used three commercial chelators: DFO, deferiprone and 2.2’-dypyridyl, and three 8-hydroxyquinoline-based iron chelators: M30, 7MH and 7DH, and we evaluated their effects in vitro using a mesencephalic cell culture treated with the Parkinsonian toxin MPP+ and in vivo using the MPTP mouse model. All chelators tested promoted the emergence of new tyrosine hydroxylase (TH)-positive processes, increased axodendritic tree length and protected cells against lipoperoxidation. Chelator treatment resulted in the generation of processes containing the presynaptic marker synaptophysin. The antioxidants N-acetylcysteine and dymetylthiourea also enhanced axodendritic tree recovery in vitro, an indication that reducing oxidative tone fosters neuritogenesis in MPP+-damaged neurons. Oral administration to mice of the M30 chelator for 14 days after MPTP treatment resulted in increased TH- and GIRK2-positive nigra cells and nigrostriatal fibers. Our results support a role for oral iron chelators as good candidates for the early treatment of PD, at stages of the disease where there is axodendritic tree retraction without neuronal death. PMID:26658949

  14. Chelating Properties of Peptides from Red Seaweed Pyropia columbina and Its Effect on Iron Bio-Accessibility.

    Science.gov (United States)

    Cian, Raúl E; Garzón, Antonela G; Ancona, David Betancur; Guerrero, Luis Chel; Drago, Silvina R

    2016-03-01

    The aim of this work was to evaluate copper-chelating, iron-chelating and anticariogenic activity of peptides obtained by enzymatic hydrolysis of P. columbina protein concentrate and to study the effects of chelating peptides on iron bio-accessibility. Two hydrolyzates were obtained from P. columbina protein concentrate (PC) using two hydrolysis systems: alkaline protease (A) and alkaline protease + Flavourzyme (AF). FPLC gel filtration profile of PC shows a peak having molecular weight (MW) higher than 7000 Da (proteins). A and AF hydrolyzates had peptides with medium and low MW (1013 and 270 Da), respectively. Additionally, AF presented free amino acids with MW around 82 Da and higher content of His and Ser. Peptides from AF showed the highest chelating properties measured as copper-chelating activity (the lowest β-carotene oxidation rate: R o ; 0.7 min(-1)), iron-chelating activity (33 %), and phosphorous and Ca(2+) release inhibition (87 and 81 %, respectively). These properties could indicate antioxidant properties, promotion of iron absorption and anticariogenic activity, respectively. In fact, hydrolyzates promoted iron dialyzability (≈16 %), values being higher than that found for P. columbina seaweed. Chelating peptides from both hydrolyzates can maintain the iron in a soluble and bio-accessible form after gastrointestinal digestion. PMID:26860526

  15. 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

  16. 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.

  17. 78 FR 44519 - Forest Resource Coordinating Committee

    Science.gov (United States)

    2013-07-24

    ... Office of the Secretary Forest Resource Coordinating Committee AGENCY: Forest Service, USDA. ACTION: Notice; Re-establishment of the Forest Resource Coordinating Committee and call for nominations. SUMMARY: The Department of Agriculture re-established the Forest Resource Coordinating Committee...

  18. 78 FR 34035 - Forest Resource Coordinating Committee

    Science.gov (United States)

    2013-06-06

    ... Forest Service Forest Resource Coordinating Committee AGENCY: Forest Service, USDA. ACTION: Notice of meeting. SUMMARY: The Forest Resource Coordinating Committee will meet via teleconference every month on... conference call will be posted to the Forest Resource Coordinating Committee Web site,...

  19. Synthesis, Characterization, and Application of Metal-Chelating Polymers for Mass Cytometric Bioassays

    Science.gov (United States)

    Majonis, Daniel

    This thesis describes the synthesis, characterization, and application of metal-chelating polymers for mass-cytometric bioassays. Mass cytometry is a cell characterization technique in which cells are injected individually into an ICP-MS detector. Signal is provided by staining cell-surface or intracellular antigens with metal-labeled antibodies (Abs). These Abs are labeled through the covalent attachment of metal-chelating polymers which carry multiple copies of a lanthanide isotope. In this work, my first goal was to develop a facile, straightforward synthesis of a new generation of metal-chelating polymers. The synthesis began with reversible addition-fragmentation chain transfer polymerization, and was followed by numerous post-polymerization pendant group transformations to introduce DTPA lanthanide chelators to every repeat unit, and a maleimide at the end of the chain. The second goal was to apply these metal-chelating polymers in bioassay experiments. The DTPA groups were loaded with lanthanide ions, and the maleimide group was used to covalently attach the polymer to an Ab. This goat anti-mouse conjugate was found to carry an average of 2.4 +/- 0.3 polymer chains. Then, primary Ab conjugates were prepared and used in an 11-plex mass cytometry assay in the characterization of umbilical cord blood cells. The third goal was to expand the multiplexity of the assay. In current technology, the number of Abs that can be monitored simultaneously is limited to the 31 commercially available, stable lanthanide isotopes. Thus, I had an interest in preparing metal-chelating polymers that could carry other metals in the 100-220 amu range. I synthesized polymers with four different polyaminocarboxylate ligands, and investigated the loading of palladium and platinum ions into these polymers. Polymer-Ab conjugates prepared with palladium- and platinum-loaded polymers gave curious results, in that only dead cells were recognized. The fourth goal was to create dual

  20. Targeted cellular ionic calcium chelation by oxalates: Implications for the treatment of tumor cells

    Directory of Open Access Journals (Sweden)

    Embi Abraham

    2012-12-01

    Full Text Available Abstract Background In malignant melanoma, it has been published that up to 40% of cancer patients will suffer from brain metastasis. The prognosis for these patients is poor, with a life expectancy of 4 to 6 months. Calcium exchange is involved in numerous cell functions. Recently, three types of cellular calcium sequestration have been reported in the medical literature. The first describes a transgenic mouse model in which an increase of aberrant calcium channels triggers hypertrophy and apoptosis. The second provides a protective mechanism whereby astrocytes in the brain inhibit apoptosis of tumor cells by moving ionic calcium out of the tumor cells thru gap junctions. The third is via calcium chelation, which causes cell apoptosis by converting ionic calcium into a calcium salt. This process has been shown to operate in atrial myocardial cells, thus not allowing the intracellular calcium stores to flow through the myocytes intercalated discs. Ideally chemotherapeutic agents would be those that initiate apoptosis in tumor cells. Presentation of the Hypothesis We hypothesize that the recent reported intracellular calcium sequestration by oxalate chelation, due to its chemical process of converting ionic calcium into a calcium salt, may inhibit the protective effect of astrocytes on brain tumor metastasized melanoma cells by not allowing free calcium to leave the metastatic cells, simultaneously apoptosis of tumor and some healthy adjacent cells could occur. This hypothesis could be extended to include other cancerous tumors such as skin cancers amongst others. Testing the hypothesis Using the experimental model showing the protective mechanism of co-cultured reactive astrocytes and tumor cells treated with oxalates could be used to test this hypothesis in vitro. The calcium specific von Kossa technique could be used to confirm the presence of chelated intracellular calcium architecture of the metastatic cells (which is a sign of apoptosis

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

    Directory of Open Access Journals (Sweden)

    Singh Rakesh K

    2010-02-01

    Full Text Available Abstract Background Metal chelators have gained much attention as potential anti-cancer agents. However, the effects of chelators are often linked solely to their capacity to bind iron while the potential complexation of other trace metals has not been fully investigated. In present study, we evaluated the effects of various lipophilic aroylhydrazone chelators (AHC, including novel compound HNTMB, on various ovarian cancer cell lines (SKOV-3, OVCAR-3, NUTU-19. Methods Cell viability was analyzed via MTS cytotoxicity assays and NCI60 cancer cell growth screens. Apoptotic events were monitored via Western Blot analysis, fluorescence microscopy and TUNEL assay. FACS analysis was carried out to study Cell Cycle regulation and detection of intracellular Reactive Oxygen Species (ROS Results HNTMB displayed high cytotoxicity (IC50 200-400 nM compared to previously developed AHC (oVtBBH, HNtBBH, StBBH/206, HNTh2H/315, HNI/311; IC50 0.8-6 μM or cancer drug Deferoxamine, a hexadentate iron-chelator (IC50 12-25 μM. In a NCI60 cancer cell line screen HNTMB exhibited growth inhibitory effects with remarkable differences in specificity depending on the cell line studied (GI50 10 nM-2.4 μM. In SKOV-3 ovarian cancer cells HNTMB treatment led to chromatin fragmentation and activation of the extrinsic and intrinsic pathways of apoptosis with specific down-regulation of Bcl-2. HNTMB caused delayed cell cycle progression of SKOV-3 through G2/M phase arrest. HNTMB can chelate iron and copper of different oxidation states. Complexation with copper lead to high cytotoxicity via generation of reactive oxygen species (ROS while treatment with iron complexes of the drug caused neither cytotoxicity nor increased ROS levels. Conclusions The present report suggests that both, non-complexed HNTMB as a chelator of intracellular trace-metals as well as a cytotoxic HNTMB/copper complex may be developed as potential therapeutic drugs in the treatment of ovarian and other

  2. DESORPTION OF METAL IONS FROM KRAFT PULPS. PART 1. CHELATION OF HARDWOOD AND SOFTWOOD KRAFT PULP WITH EDTA

    OpenAIRE

    Kim Granholm; Leo Harju; Ari Ivaska

    2010-01-01

    Chelation of unbleached and oxygen bleached hardwood and softwood kraft pulps with EDTA was studied. The main focus was on the desorption of magnesium, manganese, and iron due to their impact in TCF-bleaching. Desorption of other metal ions present were also studied in order to get an over-all estimation of the metal ion concentrations and their desorption during chelation. By using the concept of side reaction coefficients, an estimation of the chelating strength of EDTA at different pH can ...

  3. The Influence of the Combination of Carboxylate and Phosphinate Pendant Arms in 1,4,7-Triazacyclononane-Based Chelators on Their 68Ga Labelling Properties

    Directory of Open Access Journals (Sweden)

    Gábor Máté

    2015-07-01

    Full Text Available In order to compare the coordination properties of 1,4,7-triazacyclononane (tacn derivatives bearing varying numbers of phosphinic/carboxylic acid pendant groups towards 68Ga, 1,4,7-triazacyclononane-7-acetic-1,4-bis(methylenephosphinic acid (NOPA and 1,4,7- triazacyclononane-4,7-diacetic-1-[methylene(2-carboxyethylphosphinic] acid (NO2AP were synthesized using Mannich reactions with trivalent or pentavalent forms of H-phosphinic acids as phosphorus components. Stepwise protonation constants logK1–3 12.06, 3.90 and 1.95, and stability constants with GaIII and CuII, logKGaL 24.01 and logKCuL 16.66, were potentiometrically determined for NOPA. Both ligands were labelled with 68Ga and compared with NOTA (tacn-N,N′,N″-triacetic acid and NOPO, a TRAP-type [tacn-N,N′,N″- tris(methylenephosphinic acid] chelator. At pH 3, NOPO and NOPA showed higher labelling efficiency (binding with lower ligand excess at both room temperature and 95 °C, compared to NO2AP and NOTA. Labelling efficiency at pH = 0–3 correlated with a number of phosphinic acid pendants: NOPO >> NOPA > NO2AP >> NOTA; however, it was more apparent at 95 °C than at room temperature. By contrast, NOTA was found to be labelled more efficiently at pH > 4 compared to the ligands with phosphinic acids. Overall, replacement of a single phosphinate donor with a carboxylate does not challenge 68Ga labelling of TRAP-type chelators. However, the presence of carboxylates facilitates labelling at neutral or weakly acidic pH.

  4. Unusual Reactivity of N,N,N ,N -Tetramethylethylenediamine-Coordinated Neutral Ni(II) Polymerization Catalysts

    OpenAIRE

    Berkefeld, Andreas; Möller, Heiko M.; Mecking, Stefan

    2009-01-01

    Tmeda-coordinated species [(N,O)NiCH3(tmeda)] (tmeda = N,N,N′,N′-tetramethylethylenediamine), obtained by reaction of [(tmeda)NiMe2] with salicylaldimines, (O)H, are reactive and versatile intermediates for olefin polymerization catalysis. Solution NMR spectroscopic studies of 1-tmeda (N,O= 2,6-(3,5-(F3C)2C6H3)2C6H3-N═CH-(3,5-I2-2-OC6H2)) revealed two major binding modes of the tmeda ligand, open κ1- and, unexpectedly, chelating κ2-fashion, which interconvert slowly on the NMR chemical shift ...

  5. Immunoreactivity and Radioimmunoscintigraphy of 4-Lysine Single Chain (Fv) Lym-1 Antibody for the Radiometal Chelation

    International Nuclear Information System (INIS)

    Small size of recombinant scFv, composed of VH and VL region of IgG, has many advantages such as faster blood clearance, improved tumor localization and reduced human anti-mouse antibody (HAMA) response. On the other hand, owing to small size, number of amino group, which was not involved in binding site, of ScFv lym-1 was insufficient in conjugation with CITC-DTPA chelator for radio metal labeling. The goal of this study is to introduce 4-lysine tag to the end of ScFv lym-1 sequence for radio metal conjugation and to evaluate the immunoreactivity and radioimmunoscintigraphy of chelator conjugated 4-lysine taq scFv lym-1 (4-lys scFv)

  6. Biological activity of ellagitannins: Effects as anti-oxidants, pro-oxidants and metal chelators.

    Science.gov (United States)

    Moilanen, Johanna; Karonen, Maarit; Tähtinen, Petri; Jacquet, Rémi; Quideau, Stéphane; Salminen, Juha-Pekka

    2016-05-01

    Ellagitannins are a subclass of hydrolysable tannins that have been suggested to function as defensive compounds of plants against herbivores. However, it is known that the conditions in the digestive tracts of different herbivores are variable, so it seems reasonable to anticipate that the reactivities and modes of actions of these ingested defensive compounds would also be different. A previous study on a few ellagitannins has shown that these polyphenolic compounds are highly oxidizable at high pH and that their bioactivity can be attributed to certain structural features. Herein, the activities of 13 ellagitannins using the deoxyribose assay were measured. The results provided information about the anti-oxidant, pro-oxidant and metal chelating properties of ellagitannins. Surprisingly, many of the tested ellagitannins exhibited pro-oxidant activities even at neutral pH and only moderate to low radical scavenging activities, although the metal chelating capacities of all tested ellagitannins were relatively high. PMID:26899362

  7. Studies on the Chelation Behaviour of Phenanthrenequinone Monosemicarbazone with Rare Earth Elements

    International Nuclear Information System (INIS)

    Interaction between phenanthrenequinone monosemicarbazone (PQS) and trivalent rare earth La, Pr, Nd, Sm, Tb, Dy and Ho has been investigated potentiometrically. The stability constants of the PQS chelates have been evaluated at temperatures 300C, 400C and 500C at constant ionic strength. The effect of variation of ionic strength was studied by taking four ionic strengths at 250C. The stability constants have been calculated on IBM 360 Fortran-IV computer using weighted least squares method. Thermodynamic parameters such as enthalpy, entropy and Gibbs energy changes characterizing the formation of normal chelates have been evaluated at 300C. The order of stabilities of rare earths with phenanthrenequinone monosemicarbazone was found to be Ho>Dy>Tb>Sm>Nd>Pr>La

  8. The Ca(2+)-EDTA chelation as standard reaction to validate Isothermal Titration Calorimeter measurements (ITC).

    Science.gov (United States)

    Ràfols, Clara; Bosch, Elisabeth; Barbas, Rafael; Prohens, Rafel

    2016-07-01

    A study about the suitability of the chelation reaction of Ca(2+)with ethylenediaminetetraacetic acid (EDTA) as a validation standard for Isothermal Titration Calorimeter measurements has been performed exploring the common experimental variables (buffer, pH, ionic strength and temperature). Results obtained in a variety of experimental conditions have been amended according to the side reactions involved in the main process and to the experimental ionic strength and, finally, validated by contrast with the potentiometric reference values. It is demonstrated that the chelation reaction performed in acetate buffer 0.1M and 25°C shows accurate and precise results and it is robust enough to be adopted as a standard calibration process. PMID:27154686

  9. Chelate complexes of iodine (5) fluorides with glycerin and its analogs

    International Nuclear Information System (INIS)

    Interaction of IF5 with glycerin, α-thioglycerin and guaiacol-glycerin ether in solution of acetonitrite is studied using the NMR 19F method. It is shown that as a result of the reaction chelate isomers IF3(OCH2CHOCH2OH), IF3(OCH2CHOCH2SH) and IF3(OCH2CHOCH2OC6H5OMe) are formed, in which the ligands are bonded with iodine atom through oxygen atoms of neighbouring hydroxyl groups. In the reaction of IF5 with glycerin formation of the bicyclic chelate complex IF2(OCH2CHOCH2O) is also detected, in which all oxygen atoms are bonded with iodine atom

  10. Tin-117m-labeled stannic (Sn.sup.4+) chelates

    Science.gov (United States)

    Srivastava, Suresh C.; Meinken, George E.; Richards, Powell

    1985-01-01

    The radiopharmaceutical reagents of this invention and the class of Tin-117m radiopharmaceuticals are therapeutic and diagnostic agents that incorporate gamma-emitting nuclides that localize in bone after intravenous injection in mammals (mice, rats, dogs, and rabbits). Images reflecting bone structure or function can then be obtained by a scintillation camera that detects the distribution of ionizing radiation emitted by the radioactive agent. Tin-117m-labeled chelates of stannic tin localize almost exclusively in cortical bone. Upon intravenous injection of the reagent, the preferred chelates are phosphonate compounds, preferable, PYP, MDP, EHDP, and DTPA. This class of reagents is therapeutically and diagnostically useful in skeletal scintigraphy and for the radiotherapy of bone tumors and other disorders.

  11. Solution-processed Al-chelated gelatin for highly transparent non-volatile memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yu-Chi; Wang, Yeong-Her, E-mail: yhw@ee.ncku.edu.tw [Institute of Microelectronics and Department of Electrical Engineering, Advanced Optoelectronic Technology Center, National Cheng-Kung University, Tainan 701 Taiwan (China)

    2015-03-23

    Using the biomaterial of Al-chelated gelatin (ACG) prepared by sol-gel method in the ITO/ACG/ITO structure, a highly transparent resistive random access memory (RRAM) was obtained. The transmittance of the fabricated device is approximately 83% at 550 nm while that of Al/gelatin/ITO is opaque. As to the ITO/gelatin/ITO RRAM, no resistive switching behavior can be seen. The ITO/ACG/ITO RRAM shows high ON/OFF current ratio (>10{sup 5}), low operation voltage, good uniformity, and retention characteristics at room temperature and 85 °C. The mechanism of the ACG-based memory devices is presented. The enhancement of these electrical properties can be attributed to the chelate effect of Al ions with gelatin. Results show that transparent ACG-based memory devices possess the potential for next-generation resistive memories and bio-electronic applications.

  12. Solution-processed Al-chelated gelatin for highly transparent non-volatile memory applications

    International Nuclear Information System (INIS)

    Using the biomaterial of Al-chelated gelatin (ACG) prepared by sol-gel method in the ITO/ACG/ITO structure, a highly transparent resistive random access memory (RRAM) was obtained. The transmittance of the fabricated device is approximately 83% at 550 nm while that of Al/gelatin/ITO is opaque. As to the ITO/gelatin/ITO RRAM, no resistive switching behavior can be seen. The ITO/ACG/ITO RRAM shows high ON/OFF current ratio (>105), low operation voltage, good uniformity, and retention characteristics at room temperature and 85 °C. The mechanism of the ACG-based memory devices is presented. The enhancement of these electrical properties can be attributed to the chelate effect of Al ions with gelatin. Results show that transparent ACG-based memory devices possess the potential for next-generation resistive memories and bio-electronic applications

  13. Comparative analysis of the cytotoxicity of substituted (phenylglyoxal bis(4-methyl-3-thiosemicarbazone)) copper (II) chelates.

    Science.gov (United States)

    Coats, E A; Milstein, S R; Holbein, G; McDonald, J; Reed, R; Petering, H G

    1976-01-01

    Seven para-substituted [phenylglyoxal bis(4-methyl-3-thiosemicarbazone)]copper (II) chelates (12-18) have been designed, synthesized, and tested for their ability to inhibit the respiration of rat liver slices as a normal cell model and Ehrlich ascites cells as a tumor cell model. Relationships between chemical structure and respiratory inhibition are described on a quantitative basis using substituent contants (pi, Es, and sigmap) by computerized multiparameter regression analyses. The correlations indicate that changes in Es have the largest effect on liver slice toxicity of chelates while pi and sigmap account for most of the variation in toxicity to ascites cells. A comparative analysis strongly suggests that electron-donating substituents with greater water solubility should increase cytotoxicity to ascites cells at the expense of cytotoxicity to the rat liver cells. The predictions of the equations were checked by synthesizing and testing an additional derivative. The results strengthen the initial predictions. PMID:1246035

  14. Efficacy of chelating agents for treatment of acute uranium intoxication in rats

    International Nuclear Information System (INIS)

    Chelating agents (8102, 7601, 811, 7603, 8307, DTPA) were tested for treatment of acute uranium intoxication in rats. All phenolic chelating agents distinctively increased removal of uranium when they were injected immediately after intoxication of uranyl nitrate. 8102 was the best of them on removing uranium. After a single i.m. injection of 8102 at dose of 500 mg/kg, the excretion of uranium in the urine was 2.9 times higher than that for control, and the retention of uranium in kidneys was their 29%. When 8102 was administered 1 h before and up to 4 h after intoxication, it markedly increased the removal of uranium. When 8102 was administered to rats 1 h before intoxication, the histological lesion in kidneys was only a slight hydropic degeneration of the tubule epithelial cells. On the contrary, there wa a severe necrosis of the tubule epithelial cells in kidneys for controls

  15. Solution mining dawsonite from hydrocarbon containing formations with a chelating agent

    Science.gov (United States)

    Vinegar, Harold J.

    2009-07-07

    A method for treating an oil shale formation comprising dawsonite includes providing heat from one or more heaters to the formation to heat the formation. Hydrocarbon fluids are produced from the formation. At least some dawsonite in the formation is decomposed with the provided heat. A chelating agent is provided to the formation to dissolve at least some dawsonite decomposition products. The dissolved dawsonite decomposition products are produced from the formation.

  16. Quantification of thorium in uranium matrix by chelation ion chromatography (CIC)

    International Nuclear Information System (INIS)

    The present work describes an optimized procedure for the determination of thorium in uranium oxide by chelation ion chromatography technique. The method involves a two stage separation of matrix element by employing solvent extraction and ion exchange. Chromatographically thorium has been separated from the traces of other metallic impurities and the matrix element which is expected to be present in trace quantity even after employing prior separations. (author)

  17. Iron chelation therapy in transfusion-dependent thalassemia patients: current strategies and future directions

    OpenAIRE

    Saliba AN; Harb AR; Taher AT

    2015-01-01

    Antoine N Saliba, Afif R Harb, Ali T Taher Department of Internal Medicine, Division of Hematology/Oncology, American University of Beirut, Beirut, Lebanon Abstract: Transfusional iron overload is a major target in the care of patients with transfusion-dependent thalassemia (TDT) and other refractory anemias. Iron accumulates in the liver, heart, and endocrine organs leading to a wide array of complications. In this review, we summarize the characteristics of the approved iron chelators, def...

  18. Selective Chemical Labeling of Proteins with Small Fluorescent Molecules Based on Metal-Chelation Methodology

    OpenAIRE

    Nobuaki Soh

    2008-01-01

    Site-specific chemical labeling utilizing small fluorescent molecules is a powerful and attractive technique for in vivo and in vitro analysis of cellular proteins, which can circumvent some problems in genetic encoding labeling by large fluorescent proteins. In particular, affinity labeling based on metal-chelation, advantageous due to the high selectivity/simplicity and the small tag-size, is promising, as well as enzymatic covalent labeling, thereby a variety of novel methods have been stu...

  19. Switch from antagonist to agonist after addition of a DOTA chelator to a somatostatin analog

    Energy Technology Data Exchange (ETDEWEB)

    Reubi, Jean Claude; Cescato, Renzo; Waser, Beatrice [University of Berne, Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, PO Box 62, Berne (Switzerland); Erchegyi, Judit; Rivier, Jean E. [The Salk Institute for Biological Studies, The Clayton Foundation Laboratories for Peptide Biology, La Jolla, CA (United States)

    2010-08-15

    Peptide receptor targeting has become an increasingly attractive method to target tumors diagnostically and radiotherapeutically. Peptides linked to a variety of chelators have been developed for this purpose. They have, however, rarely been tested for their agonistic or antagonistic properties. We report here on a somatostatin antagonist that switched to an agonist upon coupling to a DOTA chelator. Two novel somatostatin analogs, 406-040-15 and its DOTA-coupled counterpart 406-051-20, with and without cold Indium labeling, were tested for their somatostatin receptor subtypes 1-5 (sst{sub 1}-sst{sub 5}) binding affinity using receptor autoradiography. Moreover, they were tested functionally for their ability to affect sst{sub 2} and sst{sub 3} internalization in vitro in HEK293 cells stably expressing the human sst{sub 2} or sst{sub 3} receptor, using an immunofluorescence microscopy-based internalization assay. All three compounds were characterized as pan-somatostatin analogs having a high affinity for all five sst. In the sst{sub 2} internalization assay, all three compounds showed an identical behavior, namely, a weak agonistic effect complemented by a weak antagonistic effect, compatible with the behavior of a partial agonist. Conversely, in the sst{sub 3} internalization assay, 406-040-15 was a full antagonist whereas its DOTA-coupled counterpart, 406-051-20, with and without Indium labeling, switched to a full agonist. Adding the DOTA chelator to the somatostatin analog 406-040-15 triggers a switch at sst{sub 3} receptor from an antagonist to an agonist. This indicates that potential radioligands for tumor targeting should always be tested functionally before further development, in particular if a chelator is added. (orig.)

  20. Theoretical study, and infrared and Raman spectra of copper(II) chelated complex with dibenzoylmethane

    DEFF Research Database (Denmark)

    Nekoei, A.-R.; Vakili, M.; Hakimi-Tabar, M.;

    2014-01-01

    There are some discrepancies in both the vibrational assignments and in the metal-ligand (M-L) bond strengths predicted in the previous studies on the copper (II) chelated complex of dibenzoylmethane, Cu(dbm)2. Also, there is a lack of theoretical structure, Raman spectrum and full vibrational as...... in Cu(dbm)2 are concluded to be higher than those in Cu(acac)2. The calculated geometries and vibrational results are in good agreement with the experimental data....

  1. Curcumin Inhibits Growth of Saccharomyces cerevisiae through Iron Chelation ▿ ††

    OpenAIRE

    Minear, Steven; O'Donnell, Allyson F.; Ballew, Anna; Giaever, Guri; Nislow, Corey; Stearns, Tim; Martha S Cyert

    2011-01-01

    Curcumin, a polyphenol derived from turmeric, is an ancient therapeutic used in India for centuries to treat a wide array of ailments. Interest in curcumin has increased recently, with ongoing clinical trials exploring curcumin as an anticancer therapy and as a protectant against neurodegenerative diseases. In vitro, curcumin chelates metal ions. However, although diverse physiological effects have been documented for this compound, curcumin's mechanism of action on mammalian cells remains un...

  2. Molecular Docking Assessment of Efficacy of Different Clinically Used Arsenic Chelator Drugs

    OpenAIRE

    Durjoy Majumder; Sayan Mukherjee

    2013-01-01

    Arsenic contamination of ground water has become a global problem affecting specially, south-east Asian countries like Bangladesh and eastern parts of India. It also affects South America and some parts of the US. Different organs of the physiological system are affected due to contamination of inorganic arsenic in water. Animal studies with different chelators are not very conclusive as far as the multi/differential organ effect(s) of arsenic is concerned. Our docking study establishes the m...

  3. The Management of Iron Chelation Therapy: Preliminary Data from a National Registry of Thalassaemic Patients

    OpenAIRE

    Adriana Ceci; Laura Mangiarini; Mariagrazia Felisi; Franco Bartoloni; Angela Ciancio; Marcello Capra; Domenico D'Ascola; Paolo Cianciulli; Aldo Filosa

    2011-01-01

    Thalassaemia and other haemoglobinopathies constitute an important health problem in Mediterranean countries, placing a tremendous emotional, psychological, and economic burden on their National Health systems. The development of new chelators in the most recent years had a major impact on the treatment of thalassaemia and on the quality of life of thalassaemic patients. A new initiative was promoted by the Italian Ministry of Health, establishing a Registry for thalassaemic patients to serve...

  4. Chelators influenced synthesis of chitosan-carboxymethyl cellulose microparticles for controlled drug delivery

    Science.gov (United States)

    Samrot, Antony V.; Akanksha; Jahnavi, Tatipamula; Padmanaban, S.; Philip, Sheryl-Ann; Burman, Ujjala; Rabel, Arul Maximus

    2016-07-01

    In this study, polyphenolic curcumin is entrapped within microcomposites made of biopolymers chitosan (CS) and carboxymethyl cellulose (CMC) formulated by ionic gelation method. Here, different concentrations of two chelating agents, barium chloride and sodium tripolyphosphate, are used to make microcomposites. Thus, the synthesized microparticles were characterized by FTIR, and their surface morphology was studied by SEM. Drug encapsulation efficiency and the drug release kinetics of CS-CMC composites are also studied. The produced microcomposites were used to study antibacterial activity in vitro.

  5. Chelating polymeric beads as potential therapeutics for Wilson’s disease

    Czech Academy of Sciences Publication Activity Database

    Mattová, J.; Poučková, P.; Kučka, Jan; Škodová, Michaela; Vetrík, Miroslav; Štěpánek, Petr; Urbánek, P.; Petřík, M.; Nový, Z.; Hrubý, Martin

    2014-01-01

    Roč. 62, 1 October (2014), s. 1-7. ISSN 0928-0987 R&D Projects: GA ČR GAP304/12/0950; GA ČR GA13-08336S; GA MPO FR-TI4/625 Institutional support: RVO:61389013 Keywords : Wilson’s disease * polymer beads * chelators Subject RIV: CA - Inorganic Chemistry Impact factor: 3.350, year: 2014

  6. Lutetium-177 and iodine-131 loaded chelating polymer microparticles intended for radioembolization of liver malignancies

    Czech Academy of Sciences Publication Activity Database

    Hrubý, Martin; Škodová, Michaela; Macková, Hana; Skopal, Jan; Tomeš, Marek; Kropáček, Martin; Zimová, Jana; Kučka, Jan

    2011-01-01

    Roč. 71, č. 12 (2011), s. 1155-1159. ISSN 1381-5148 R&D Projects: GA ČR GPP207/10/P054; GA MŠk 1M0505 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z10480505 Keywords : macroporous chelating beads * radioembolization * quinoline-8-ol Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.479, year: 2011

  7. Neurotensin(8-13) analogue: radiolabeling and biological evaluation using different chelators

    International Nuclear Information System (INIS)

    Introduction: Several strategies on the development of radiopharmaceuticals have been employed. Bifunctional chelators seem to be a promising approach since high radiochemical yields as well as good in vitro and in vivo stability have been achieved. To date, neurotensin analogs have been radiolabeled using the 99mTc-carbonyl approach and none was described employing the bifunctional chelating agent technique. Aim: The purpose of this study was to evaluate the radiochemical and biological behaviour of NT(8-13) analogue radiolabeled with 99mTc, using HYNIC and NHS-S-acetyl-MAG3 as chelator agents. Methods: Radiolabeling, in vitro stability toward cysteine and glutathione, partition coefficient and plasma protein binding were assessed for both radioconjugates. Biodistribution in healthy Swiss mice were carried out in order to evaluate the biological behaviour of the radiocomplexes. Results: Radiochemical yields were higher than 97% and no apparent instability toward transchelant agents was observed for both radioconjugates. A higher lipophilic character was observed for the radioconjugate labeled via MAG3. The chelators seem to have no effect on the percentage of the radioconjugate bound to plasma proteins. A similar biological pattern was observed for both radioconjugates. Total blood, bone and muscle values revealed a slightly slower clearance for the radiocomplex labeled via MAG3. Moreover, a remarkable liver and intestinal uptake was observed for the radiocomplex labeled via MAG3 even at the later time points studied. Conclusion: The high radiochemical yields achieved and the similar in vivo pattern found for both radioconjugates make them potential candidates for imaging tumors using nuclear medicine techniques.

  8. Bioavailability assessment of metals chelated as proteinates using the Ussing Chamber Model

    OpenAIRE

    Piva, G.; G. Cavanna; G. Casadei; A. Piva

    2011-01-01

    Preparation of proteinates by hydrolysis of organic matter produces a blend of different proteins, and may likely result in the chelation of trace elements. Often this process results in an increased bioavailability of minerals, leading to a higher absorption rate than inorganic salts (Cao et al., 2000; Uchida et al., 2001; Bailey et al., 2001; Guo et al., 2001). Usually trace elements uptake takes place along the small intestine, mainly jejunum (Tapia et al., 1996; Arredondo et al., 2000), e...

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Wuguo Deng; Xingwang Fang; Jilan Wu [Peking Univ., Technical Physics Dept., Beijing (China)

    1997-09-01

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

  11. CoMo/ZrO2 Hydrodesulfurization Catalysts Prepared by Chelating Agent Assisted Spreading

    OpenAIRE

    Kaluža, L. (Luděk); Gulková, D. (Daniela); Vít, Z. (Zdeněk); Zdražil, M. (Miroslav)

    2012-01-01

    The novel Mo/ZrO2 and CoMo/ZrO2 catalysts were prepared by impregnation of the monoclinic ZrO2 by the chelating agent nitrilotriacetic acid (NTA) assisted spreading of MoO3 with CoCO3 xH2O and compared with samples prepared conventionally. The application of NTA during the catalysts preparation systematically increased the activity in benzothiophene HDS by the factor 1.2–1.7.

  12. Overview of guidelines on iron chelation therapy in patients with myelodysplastic syndromes and transfusional iron overload

    OpenAIRE

    Gattermann, Norbert

    2008-01-01

    Between 2002 and 2008, a number of consensus statements and guidelines were developed by various groups around the world to educate healthcare professionals on the treatment of myelodysplastic syndromes (MDS), including the management of transfusional iron overload with iron chelation therapy. Guidelines have been developed by The Italian Society of Hematology, The UK MDS Guidelines Group, The Nagasaki Group, The National Comprehensive Cancer Network, and The MDS Foundation. These guidelines ...

  13. Chelator-Induced Dispersal and Killing of Pseudomonas aeruginosa Cells in a Biofilm†

    OpenAIRE

    Banin, Ehud; Brady, Keith M.; Greenberg, E. Peter

    2006-01-01

    Biofilms consist of groups of bacteria attached to surfaces and encased in a hydrated polymeric matrix. Bacteria in biofilms are more resistant to the immune system and to antibiotics than their free-living planktonic counterparts. Thus, biofilm-related infections are persistent and often show recurrent symptoms. The metal chelator EDTA is known to have activity against biofilms of gram-positive bacteria such as Staphylococcus aureus. EDTA can also kill planktonic cells of Proteobacteria like...

  14. Degradation of the Ferric Chelate of EDTA by a Pure Culture of an Agrobacterium sp

    OpenAIRE

    Lauff, John J.; Steele, D. Bernie; Coogan, Louise A.; Breitfeller, James M.

    1990-01-01

    A pure culture of an Agrobacterium sp. (deposited as ATCC 55002) that mineralizes the ferric chelate of EDTA (ferric-EDTA) was isolated by selective enrichment from a treatment facility receiving industrial waste containing ferric-EDTA. The isolate grew on ferric-EDTA as the sole carbon source at concentrations exceeding 100 mM. As the degradation proceeded, carbon dioxide, ammonia, and an unidentified metabolite(s) were produced; the pH increased, and iron was precipitated from solution. The...

  15. Effects of Iron Chelators on the Formation and Development of Aspergillus fumigatus Biofilm.

    Science.gov (United States)

    Nazik, Hasan; Penner, John C; Ferreira, Jose A; Haagensen, Janus A J; Cohen, Kevin; Spormann, Alfred M; Martinez, Marife; Chen, Vicky; Hsu, Joe L; Clemons, Karl V; Stevens, David A

    2015-10-01

    Iron acquisition is crucial for the growth of Aspergillus fumigatus. A. fumigatus biofilm formation occurs in vitro and in vivo and is associated with physiological changes. In this study, we assessed the effects of Fe chelators on biofilm formation and development. Deferiprone (DFP), deferasirox (DFS), and deferoxamine (DFM) were tested for MIC against a reference isolate via a broth macrodilution method. The metabolic effects (assessed by XTT [2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide inner salt]) on biofilm formation by conidia were studied upon exposure to DFP, DFM, DFP plus FeCl3, or FeCl3 alone. A preformed biofilm was exposed to DFP with or without FeCl3. The DFP and DFS MIC50 against planktonic A. fumigatus was 1,250 μM, and XTT gave the same result. DFM showed no planktonic inhibition at concentrations of ≤2,500 μM. By XTT testing, DFM concentrations of biofilms forming in A. fumigatus or preformed biofilms (P biofilm formation (P Biofilm formation with 625 μM DFP plus any concentration of FeCl3 was lower than that in the controls (P biofilms, DFP in the range of ≥625 to 1,250 μM was inhibitory compared to the controls (P biofilm formation (P biofilm increased with 2,500 μM FeCl3 only (P biofilms of A. fumigatus clinical isolates to DFP were noted. In conclusion, iron stimulates biofilm formation and preformed biofilms. Chelators can inhibit or enhance biofilms. Chelation may be a potential therapy for A. fumigatus, but we show here that chelators must be chosen carefully. Individual isolate susceptibility assessments may be needed. PMID:26239975

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

    International Nuclear Information System (INIS)

    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 [Tyr3,Thr8]-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 (Sar5) was used as a spacer between the chelators and the peptide to probe its influence on biology and pharmacology. Complexation rates with In3+ and Y3+ 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/natIn-DOTA]-TATE except for [(111/natIn-DOTA)2-Apg]-TATE which showed a lower binding affinity and rate of internalization into tumor cells. The biodistribution of [(111/natIn-DOTA)-Lys(111/natIn-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/natIn-DOTA]-TATE. (orig.)

  17. Protection against SR 4233 (tirapazamine) aerobic cytotoxicity by the metal chelators desferrioxamine and tiron

    International Nuclear Information System (INIS)

    Metal chelating agents and antioxidants were evaluated as potential protectors against aerobic SR 4233 cytotoxicity in Chinese hamster V79 cells. The differential protection of aerobic and hypoxic cells by two metal chelators, desferrrioxamine and Tiron, is discussed in the context of their potential use in the on-going clinical trials with SR 4233. Cytotoxicity was evaluated using clonogenic assay. SR 4233 exposure was done in glass flasks as a function of time either alone or in the presence of the following agents: superoxide dismutase, catalase, 5,5-dimethyl-1-pyrroline, Trolox, ICRF-187, desferrioxamine, Tiron (1,2-dihydroxybenzene-3,5-disulfonate), and ascorbic acid. Experiments done under hypoxic conditions were carried out in specially designed glass flasks that were gassed with humidified nitrogen/carbon dioxide mixture and with a side-arm reservoir from which SR 4233 was added to cell media after hypoxia was obtained. Electron paramagnetic resonance studies were also performed. Electron paramagnetic resonance and spectrophotometry experiments suggest that under aerobic conditions SR 4233 undergoes futile redox cycling to produce superoxide. Treatment of cells during aerobic exposure to SR 4233 with the enzymes superoxide dismutase and catalase, the spin trapping agent DMPO, the water-soluble vitamin E analog Trolox, and the metal chelator ICRF-187 provided little or no protection against aerobic SR 4233 cytotoxicity. However, two other metal chelators, desferrioxamine and Tiron afforded significant protection against minimal protection to hypoxic cells treated with SR 4233. One potential mechanism of aerobic cytotoxicity is redox cycling of SR 4233 with molecular oxygen resulting in several potentially toxic oxidative species that overburden the intrinsic intracellular detoxification systems such as superoxide dismutase, catalase, and glutathione peroxidase. 23 refs., 4 figs., 1 tab

  18. Switch from antagonist to agonist after addition of a DOTA chelator to a somatostatin analog

    International Nuclear Information System (INIS)

    Peptide receptor targeting has become an increasingly attractive method to target tumors diagnostically and radiotherapeutically. Peptides linked to a variety of chelators have been developed for this purpose. They have, however, rarely been tested for their agonistic or antagonistic properties. We report here on a somatostatin antagonist that switched to an agonist upon coupling to a DOTA chelator. Two novel somatostatin analogs, 406-040-15 and its DOTA-coupled counterpart 406-051-20, with and without cold Indium labeling, were tested for their somatostatin receptor subtypes 1-5 (sst1-sst5) binding affinity using receptor autoradiography. Moreover, they were tested functionally for their ability to affect sst2 and sst3 internalization in vitro in HEK293 cells stably expressing the human sst2 or sst3 receptor, using an immunofluorescence microscopy-based internalization assay. All three compounds were characterized as pan-somatostatin analogs having a high affinity for all five sst. In the sst2 internalization assay, all three compounds showed an identical behavior, namely, a weak agonistic effect complemented by a weak antagonistic effect, compatible with the behavior of a partial agonist. Conversely, in the sst3 internalization assay, 406-040-15 was a full antagonist whereas its DOTA-coupled counterpart, 406-051-20, with and without Indium labeling, switched to a full agonist. Adding the DOTA chelator to the somatostatin analog 406-040-15 triggers a switch at sst3 receptor from an antagonist to an agonist. This indicates that potential radioligands for tumor targeting should always be tested functionally before further development, in particular if a chelator is added. (orig.)

  19. Synthesis of a Functional Metal-Chelating Polymer and Steps towards Quantitative Mass Cytometry Bioassays

    OpenAIRE

    Majonis, Daniel; Herrera, Isaac; Ornatsky, Olga; Schulze, Maren; Lou, Xudong; Soleimani, Mohsen; Nitz, Mark; Mitchell A. Winnik

    2010-01-01

    We describe the synthesis and characterization of metal-chelating polymers with a degree of polymerization of 67 and 79, high DTPA functionality, Mw/Mn ≤ 1.17, and a maleimide as an orthogonal functional group for conjugation to antibodies. The polymeric disulfide form of the DPn = 79 DTPA polymer was analyzed by thermogravimetric analysis to determine moisture and sodium-ion content, and by isothermal titration calorimetry (ITC) to determine the Gd3+ binding capacity. These results showed ea...

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

    International Nuclear Information System (INIS)

    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)