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Sample records for acid chelating fiber

  1. Method of encapsulating polyaminopolycarboxylic acid chelating agents in liposomes

    DOEpatents

    Rahman, Yueh Erh

    1977-11-10

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

  2. Disaggregation ability of different chelating molecules on copper ion-triggered amyloid fibers.

    PubMed

    Zhu, Linyi; Han, Yuchun; He, Chengqian; Huang, Xu; Wang, Yilin

    2014-08-01

    Dysfunctional interaction of amyloid-β (Aβ) with excess metal ions is proved to be related to the etiology of Alzheimer's disease (AD). Using metal-binding compounds to reverse metal-triggered Aβ aggregation has become one of the potential therapies for AD. In this study, the ability of a carboxylic acid gemini surfactant (SDUC), a widely used metal chelator (EDTA), and an antifungal drug clioquinol (CQ) in reversing the Cu(2+)-triggered Aβ(1-40) fibers have been systematically studied by using turbidity essay, BCA essay, atomic force microscopy, transmission electron microscopy, and isothermal titration microcalorimetry. The results show that the binding affinity of Cu(2+) with CQ, SDUC, and EDTA is in the order of CQ > EDTA > SDUC, while the disaggregation ability to Cu(2+)-triggered Aβ(1-40) fibers is in the order of CQ > SDUC > EDTA. Therefore, the disaggregation ability of chelators to the Aβ(1-40) fibers does not only depend on the binding affinity of the chelators with Cu(2+). Strong self-assembly ability of SDUC and π-π interaction of the conjugate group of CQ also contributes toward the disaggregation of the Cu(2+)-triggered Aβ(1-40) fibers and result in the formation of mixed small aggregates. PMID:25051063

  3. Chelating polymer modified P84 nanofiltration (NF) hollow fiber membranes for high efficient heavy metal removal.

    PubMed

    Gao, Jie; Sun, Shi-Peng; Zhu, Wen-Ping; Chung, Tai-Shung

    2014-10-15

    High performance nanofiltration (NF) membranes for heavy metal removal have been molecularly designed by adsorption of chelating polymers containing negatively charged functional groups such as poly (acrylic acid-co-maleic acid) (PAM), poly (acrylic acid) (PAA) and poly (dimethylamine-co-epichlorohydrin-co-ethylenediamine) (PDMED) on the positively charged polyethyleneimine (PEI) cross-linked P84 hollow fiber substrates. Not only do these chelating polymers change the membrane surface charge and pore size, but also provide an extra mean to remove heavy metal ions through adsorption in addition to traditional steric effect and Donnan exclusion. The adsorbed membranes have comparable water permeability and superior rejections to heavy metals, for instance, Pb(NO3)2, CuSO4, NiCl2, CdCl2, ZnCl2, Na2Cr2O7 and Na2HAsO4, with rejections higher than 98%. The membranes also display excellent rejections to mixed ions with rejections more than 99%. The newly developed membranes show reasonably stability during 60-h tests as well as multiple washes. PMID:25016298

  4. Preparation and characterization of chelating fibers based on natural wool for removal of Hg(II), Cu(II) and Co(II) metal ions from aqueous solutions.

    PubMed

    Monier, M; Nawar, N; Abdel-Latif, D A

    2010-12-15

    The graft copolymerization of acrylonitrile (AN) onto natural wool fibers initiated by KMnO(4) and oxalic acid combined redox initiator system in limited aqueous medium was carried out in heterogeneous media. Moreover, modification of the grafted wool fibers was done by changing the nitrile group (-CN) into cyano-acetic acid α-amino-acrylic-hydrazide through the reaction with hydrazine hydrate followed by ethylcyanoacetate which eventually produce wool-grafted-poly(cyano-acetic acid α-amino-acrylic-hydrazide) (wool-g-PCAH) chelating fibers. The application of the modified fibers for metal ion uptake was studied using Hg(2+), Cu(2+) and Co(2+). The modified chelating fibers were characterized using FTIR spectroscopy, SEM and X-ray diffraction. PMID:20810212

  5. Ytterbium-doped large-mode-area silica fiber fabricated by using chelate precursor doping technique.

    PubMed

    Shi, Tengfei; Zhou, Zhiguang; Ni, Li; Xiao, Xusheng; Zhan, Huan; Zhang, Aidong; Lin, Aoxiang

    2014-05-20

    We reported on a highly effective chelate precursor doping technique for Yb-doped large-mode-area (LMA) fiber manufacture. By accurately controlling the evaporation temperature and flow rate of carrier gas, the chelate precursor doping technique is capable of making Yb-doped LMA silica fiber with good uniformity free of center dip, low numerical aperture of ~0.056, large preform core size of 4.46 mm, and appropriate cladding absorption of 1.17  dB/m at 976.4 nm. Based on a single-end-pump all-fiber oscillator laser setup, the laser output at 1080 nm reached 700 W with slope efficiency of 54.2%. PMID:24922203

  6. Chelation in metal intoxication. XIII. Polyaminocarboxylic acids as chelators in lead poisoning

    SciTech Connect

    Tandon, S.K.; Behari, J.R.; Singh, S.

    1983-01-01

    Diethylene-triaminepentaacetic acid (DTPA), nitrilotriacetic acid (NTA) and hydroxyethylene-diaminetriacetic acid (HEDTA) were investigated for their ability to reduce Pb body burden and to restore altered urinary and blood parameters in Pb-poisoned rats.

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

    PubMed Central

    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

  8. Adsorption of Cu(II), Hg(II), and Ni(II) ions by modified natural wool chelating fibers.

    PubMed

    Monier, M; Ayad, D M; Sarhan, A A

    2010-04-15

    The graft copolymerization of ethyl acrylate (EA) onto natural wool fibers initiated by potassium persulphate and Mohr's salt redox initiator system in limited aqueous medium was carried out in heterogeneous media. Ester groups of the grafted copolymers were partially converted into hydrazide function groups followed by hydrazone formation through reaction with isatin. Also the application of the modified fibers for metal ion uptake was studied using Cu(II), Hg(II) and Ni(II). The modified chelating fibers were characterized using FTIR spectroscopy, SEM and X-ray diffraction. PMID:19962235

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

    PubMed Central

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

    2010-01-01

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

  10. Hyperbranched chelating polymers for the polymer-assisted ultrafiltration of boric acid

    SciTech Connect

    Smith, B.M.; Todd, P.; Bowman, C.N.

    1999-07-01

    Two hyperbranched chelating polymers, glucoheptonamide derivatives of dendrimetric poly(amido amine) and poly(ethylene imine), were employed in polymer-assisted ultrafiltration and concentration of boron from aqueous feed streams. For feeds containing approximately 1 mM B (10 ppm), volume reduction factors of 20 were observed in cyclic adsorption-desorption. The concentrations of both polymers declined due to permeation through an ultrafiltration membrane with pore sizes which should have retained them. Acid-catalyzed hydrolysis of the amide linkages between the polymer backbone and the chelating side groups is implicated in this loss of polymer mass and effectiveness.

  11. Iron chelation using subcutaneous infusions of diethylene triamine penta-acetic acid (DTPA).

    PubMed

    Pippard, M J; Jackson, M J; Hoffman, K; Petrou, M; Modell, C B

    1986-05-01

    The iron chelating ability and potential toxicity of subcutaneous infusions of the calcium and zinc salts of diethylene triamine penta-acetic acid (DTPA) have been assessed in metabolic balance studies in 2 iron-loaded thalassaemic patients. Infusions of calcium DTPA were locally well tolerated and the drug was as effective as desferrioxamine in mobilising iron. However, daily infusions in the 1st patient also produced symptomatic zinc depletion which could not be controlled by simultaneous oral zinc supplements. Zinc DTPA proved ineffective as an iron chelator, but zinc balance could be maintained in the 2nd patient by combining intermittent (every 4 d) use of calcium DTPA with oral zinc supplements. Combined studies with desferrioxamine and calcium DTPA showed the drugs to have additive effects, probably as a result of the chelation of iron from different body sites. PMID:3738427

  12. Flame and acid resistant polymide fibers

    NASA Technical Reports Server (NTRS)

    Stringham, R. S.; Toy, M. S.

    1977-01-01

    Economical process improves flame resistance and resistance to acids of polyamide fibers, without modifying colors of mechanical properties. Process improves general safety of garments and other items made from polyamide fibers and makes them suitable for applications requiring exposure to oxygen-rich atmosphere or corrosive acids. Halo-olefins are added to surface of fibers by photoadditon in sealed chamber. Process could be used with films and other forms of polyamide.

  13. Benzoic acid degradation of polyacrylonitrile fibers

    NASA Technical Reports Server (NTRS)

    Varma, D. S.; Needles, H. L.; Cagliostro, D. E.

    1981-01-01

    The reactions of polyacrylonitrile (PAN) fibers in the presence of benzoic acid have been studied. Polyacrylonitrile fibers oxidize more readily in the presence of benzoic acid than in air at temperatures in the range of 170 C. The product decreased in solubility with extent of reaction. Gel permeation chromatography of the soluble fraction showed change in polydispersity. The insoluble product exhibited differences in weight loss as a function of decomposition temperature compared to PAN fibers. Infrared analyses of the fiber product showed absorption peaks similar to air-oxidized PAN. High-energy photoelectron spectral analysis showed a carbon-rich surface which contained oxygen and nitrogen. An air oxidized sample of fiber contained more oxygen at the surface than a fiber treated first with benzoic acid and then air oxidized.

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

    PubMed

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

    2014-06-01

    Given the wide application of positron emission tomography (PET), positron-emitting metal radionuclides have received much attention recently. Of these, gallium-68 has become particularly popular, as it is the only PET nuclide commercially available from radionuclide generators, therefore allowing local production of PET radiotracers independent of an on-site cyclotron. Hence, interest in optimized bifunctional chelators for the elaboration of (68) Ga-labeled bioconjugates has been rekindled as well, resulting in the development of improved triazacyclononane-triphosphinate (TRAP) ligand structures. The most remarkable features of these ligands are unparalleled selectivity for Ga(III) , rapid Ga(III) complexation kinetics, extraordinarily high thermodynamic stability, and kinetic inertness of the respective Ga(III) chelates. As a result, TRAP chelators exhibit very favorable (68) Ga-labeling properties. Based on the scaffolds NOPO (1,4,7-triazacyclononane-1,4-bis[methylene(hydroxymethyl)phosphinic acid]-7-[methylene(2-carboxyethyl)phosphinic acid]) and TRAP-Pr, tailored for convenient preparation of (68) Ga-labeled monomeric and multimeric bioconjugates, a variety of novel (68) Ga radiopharmaceuticals have been synthesized. These include bisphosphonates, somatostatin receptor ligands, prostate-specific membrane antigen (PSMA)-targeting peptides, and cyclic RGD pentapeptides, for in vivo PET imaging of bone, neuroendocrine tumors, prostate cancer, and integrin expression, respectively. Furthermore, TRAP-based (68) Ga-labeled gadolinium(III) complexes have been proposed as bimodal probes for PET/MRI, and a cyclen-based analogue of TRAP-Pr has been suggested for the elaboration of targeted radiotherapeutics comprising radiolanthanide ions. Thus, polyazacycloalkane-based polyphosphinic acid chelators are a powerful toolbox for pharmaceutical research, particularly for the development of (68) Ga radiopharmaceuticals. PMID:24700633

  15. Wet spinning of solid polyamic acid fibers

    NASA Technical Reports Server (NTRS)

    Dorogy, William E., Jr. (Inventor); St.clair, Anne K. (Inventor)

    1991-01-01

    The invention is a process for the production of solid aromatic polyamic acid and polyimide fibers from a wet gel or coagulation bath wet gel using N,N-dimethylacetamide (DMAc) solutions of the polyamic acid derived from aromatic dianhydrides such as 3,3',4,4' benzophenonetetra carboxylic dianhydride (BTDA) and aromatic diamines such as 4,4'-oxydianiline (4,4'-ODA). By utilizing the relationship among coagulation medium and concentration, resin inherent viscosity, resin percent solids, filament diameter, and fiber void content, it is possible to make improved polyamic acid fibers. Solid polyimide fibers, obtained by the thermal cyclization of the polyamic acid precursor, have increased tensile properties compared to fibers containing macropores from the same resin system.

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

    SciTech Connect

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

    1991-03-01

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

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

    PubMed

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

    1991-01-01

    A conjugate in which the steroid nucleus of cholic acid was linked to EDTA via an 11-atom spacer was obtained by reacting the succinimidyl ester of cholic acid with the amine formed by reaction of a benzyl isothiocyanate derivative of EDTA with N-(tert-butoxycarbonyl)ethylenediamine and subsequent deprotection. Potentiometric titration studies with model complexes showed that the EDTA moiety retained the ability to form 1:1 chelates of high thermodynamic stability, although formation constants were some 3-4 log K units lower for complexes of the conjugate than for the analogous chelates with underivatized EDTA. A complex formed between the cholic acid-EDTA conjugate and 111InIII was clearly rapidly into the liver when injected iv into mice, with subsequent excretion from the liver into the gastrointestinal tract being complete within 1 h of injection. Radioscintigraphic imaging studies conducted in a rabbit given the 111In-labeled conjugate also showed early liver uptake followed by rapid clearance from the liver into the intestine, with good visualization of the gallbladder in images obtained at 20-25 min postinjection. It is concluded that conjugation to cholic acid provides a useful means for the hepatobiliary delivery of EDTA chelates that otherwise exhibit predominantly extracellular distribution and renal clearance. PMID:1907855

  18. Diethylentriaminepenta acetic acid glucose conjugates as a cell permeable iron chelator

    PubMed Central

    Mosayebnia, Mona; Shafiee-Ardestani, Mehdi; Pasalar, Parvin; Mashayekhi, Mojgan; Amanlou, Massoud

    2014-01-01

    Objective: To find out whether DTPA-DG complex can enhance clearance of intracellular free iron. Materials and Methods: Diethylenetriaminepentaacetic acid-D-deoxy-glucosamine (DTPA-DG) was synthesized and examined for its activity as a cell-permeable iron chelator in human hepatocellular carcinoma (HEPG2) cell line exposed to high concentration of iron sulfate and compared with deferoxamine (DFO), a prototype iron chelator. The effect of DTPA-DG on cell viability was monitored using the 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide MTT assay as well. Results: There was a significant increase of iron level after iron overload induction in HEPG2 cell culture. DTPA-DG presented a remarkable capacity to iron burden reducing with estimated 50% inhibitory concentration value of 65.77 nM. In fact, glycosyl moiety was gained access of DTPA to intracellular iron deposits through glucose transporter systems. Conclusion: DTPA-DG, more potent than DFO to sequester deposits of free iron with no profound toxic effect. The results suggest the potential of DTPA-DG in chelating iron and permitting its excretion from primary organ storage. PMID:24554907

  19. Chelation Properties of Modified Humic Acids Toward Some Trivalent Lanthanide Ions

    SciTech Connect

    Yaghmour, Remah N.; Khalili, Fawwaz I.; Mubarak, Mohammad S.

    2007-05-09

    Three kinds of humic acids, Fluka (I), Fluka (II), and Ega-chemie (III) were modified through condensation with formaldehyde to afford polymers I, II, and III, respectively. The chelation behavior of these modified humic acids polymers towards the trivalent lanthanide metal-ions, La3+, Ce3+, Nd3+, Sm3+, and Gd3+ was studied by a batch equilibration technique at 25 deg. C as a function of contact time, pH, counter ion and counter ion concentration. The highest metal-ion uptake of the three polymers was achieved at pH 7.0 and by using perchlorate as a counter ion. Results of the study have revealed that polymer II has the highest metal-ion uptake capacity, and that the metal-ion uptake falls in the order: Gd3+ > Sm3+ > Nd3+ > La3+ {approx_equal} Ce3+.

  20. [Functionalized Metal Chelates Based on Diethylenetriaminetetraacetic Acids for Chemical Modification of Proteins and Small Biomolecules].

    PubMed

    Kuprienko, O S; Dubovskaya, L V; Shabunya, P S; Fatykhava, S A; Sviridov, O V

    2015-01-01

    Bifunctional reagents based on diethylenetriaminetetraacetic acid containing a bound metal ion and a reactive functional group for the interaction with proteins and low-molecular-weight substances have been synthesized. An Amino-derivative of a complexonate was obtained by acylation of monosubstituted diamine with diethylenetriaminepentaacetic acid dianhydride followed by deprotection ofthe amino group, purification by anion exchange chromatography and chelation of Eu3+. This metal chelate derivative was used for labeling 17α-hydroxyprogesterone 3-(O-carboxymethyl)oxime and horseradish peroxidase. The enzyme modified with the Eu3+ complexonate at the carbohydrate component and with a cortisol derivative at the polypeptide chain was used in a dissociation-enhanced lanthanide fluorescent immunoassay (DELFIA) as well as in an enzyme immunoassay of the steroid hormone. DELFIA showed that labeled 17α-hydroxyprogesterone retained the affinity for corresponding antibodies. A Eu(3+)-complexonate carboxy-derivative N-succinimide ester was obtained by acylation of the aminochelate with p-phthalic acid di-N-succinimide ester. It was used for modification of amino groups of lysine residues in polypeptide chains of human serum albumin and some immunoglobulins G. Purification of Eu3+ complexonate-protein conjugates by gel-chromatography on a Superose- 12 column allowed to separate the modified proteins from unreacted low molecular weight Eu(3+)-derivatives and to determine a degree of lanthanide inclusion into a protein. The amount of Eu3+ covalently attached to a protein was determined by measuring the fluorescence of a conjugate in the dissociative-enhancement solution. The obtained values correlated well with the results of ICP-MS determination of Eu3+ concentration in a conjugate solution. It was shown that conjugates of monoclonal antibodies obtained by the proposed method possessed the required characteristics of fluorescence intensity, signal-to-noise ratio, sensitivity

  1. Comparison of natural organic acids and synthetic chelates at enhancing phytoextraction of metals from a multi-metal contaminated soil.

    PubMed

    do Nascimento, Clístenes Williams A; Amarasiriwardena, Dula; Xing, Baoshan

    2006-03-01

    Chemically assisted phytoremediation has been developing to induce accumulation of metals by high biomass plants. Synthetic chelates have shown high effectiveness to reach such a goal, but they pose serious drawbacks in field application due to the excessive amount of metals solubilized. We compared the performance of synthetic chelates with naturally occurring low molecular weight organic acids (LMWOA) in enhancing phytoextraction of metals by Indian mustard (Brassica juncea) from multi-metal contaminated soils. Gallic and citric acids were able to induce removal of Cd, Zn, Cu, and Ni from soil without increasing the leaching risk. Net removal of these metals caused by LMWOA can be as much as synthetic chelates. A major reason for this is the lower phytotoxicity of LMWOA. Furthermore, supplying appropriate mineral nutrients increased biomass and metal removal. PMID:16125291

  2. Mugineic acid, active ingredient of wheat grass: an oral novel hexadentate iron chelator in iron overloaded diseases.

    PubMed

    Das, Priyabrata; Mukhopadhyay, Soma; Kumar Sarkar, Nirmal; Mandal, Suvra; Kar, Manoj; Mukhopadhyay, Ashis

    2016-09-01

    Iron chelation therapies are required for the treatment of iron overloaded patients; nonetheless, their side effects are also well known. We have evaluated iron-chelating activity of wheat grass extract (WHE) and its purified compound, mugineic acid in murine model with phenylhydrazine (PHZ) and dextran induced acute and chronic iron overload conditions. PHZ and dextran treatment induced acute and chronic iron overload condition in mice, respectively, as indicated by increased serum and tissue iron in both cases. Iron overload was also accompanied with haemosiderosis in tissues (liver and spleen). These PHZ and dextran -: treated mice were orally treated with either crude WHE or purified mugineic acid. The efficacy of mugineic acid and WHE was compared with the potent oral iron chelator ICL670 (Exjade). PHZ and dextran treatment followed by oral administration of WHE or mugineic acid significantly checked the rise of serum/plasma levels of iron as well as tissue iron and also, haemosiderosis in tissues. The results are highly comparable with known iron chelator ICL670. WHE and purified mugineic acid, both seem to have significant prospect to be the cheap, non-toxic, hexadentate and oral therapeutic agents to prevent or alleviate toxic iron overload in patients. PMID:27008864

  3. Degradation of ferric chelate of ethylenediaminetetraacetic acid by bacterium isolated from deep-sea stalked barnacle.

    PubMed

    Imada, Chiaki; Harada, Yohei; Kobayashi, Takeshi; Hamada-Sato, Naoko; Watanabe, Etsuo

    2005-01-01

    Twenty strains of marine bacteria that degrade ferric chelate of ethylenediaminetetraacetic acid (Fe-EDTA) were isolated from among 117 strains collected from a marine environment. Among them strain 02-N-2, which was isolated from stalked barnacle collected from the deep sea in the Indian Ocean, had the highest Fe-EDTA degradation ability and was selected for further study. The strain showed high Fe-EDTA degradation ability at different seawater concentrations. In addition, the intact cells of this strain had the ability to degrade such metal-EDTAs as Ca, Cu, and Mg. The strain was an aerobic, gram-variable, rod-shaped organism. The results of various taxonomic studies revealed that the strain had significant similarity to Bacillus jeotgali JCM 10885(T), which was isolated from a Korean traditional fermented seafood, Jeotgal. PMID:15747087

  4. Fluorescence quenching determination of metallothioneins using 8-hydroxyquinoline-5-sulphonic acid-Cd(II) chelate

    NASA Astrophysics Data System (ADS)

    Qian, Qiu-Mei; Wang, Yong-Sheng; Zhou, Bin; Xue, Jin-Hua; Li, Le; Wang, Yong-Song; Wang, Jia-Cheng; Yin, Ji-Cheng; Liu, Shan-Du; Zhao, Hui; Liu, Hui

    2014-01-01

    A novel method for the determination of metallothioneins (MTs) in urine was developed by fluorescence quenching strategy. The response signals linearly correlated with the concentration of MTs in the ranges of 3.12 × 10-8-1.23 × 10-6 mol L-1, and the limit of detection (LOD) was 9.36 × 10-9 mol L-1. The proposed method avoids the label and derivatization steps in common methods, and is reliable, inexpensive and sensitive. Furthermore, the interaction of MTs and 8-hydroxyquinoline-5-sulphonic acid (HQS)-Cd(II) chelate was investigated, and a static quenching mode was proposed to be primarily responsible for the fluorescence quenching event. It could provide a promising potential for the detection of the biomacromolecules which have no native fluorescence, and be benefit to extend the application of fluorescence strategy.

  5. Research progress of chelate precursor doping method to fabricate Yb-doped large-mode-area silica fibers for kW-level laser

    NASA Astrophysics Data System (ADS)

    Wang, Zhen; Zhan, Huan; Ni, Li; Peng, Kun; Wang, Xiaolong; Wang, Jianjun; Jing, Feng; Lin, Aoxiang

    2015-11-01

    With continuous efforts and practical managing experiences, the chelate precursor doping method has been justified as an effective way to dope rare-earth ions into silica host materials, a key technique in making large-mode-area silica fibers for high power laser applications. It is characterized by good controllability, stability and repeatability to accomplish different refractive index profiles. Different preforms with a large core, designed refractive index profile, good symmetrical shape and homogeneous elemental distribution were successfully fabricated. The home-made standard 20/400-type double-cladding Yb-doped large-mode-area silica fiber was drawn and presented a 1.6 kW laser output at 1064 nm, the highest power record publically reported with this method. With further optimization, chelate precusor doping method has potential to manufacture high power laser fibers for the next generation.

  6. Bioactivity in silica/poly(γ-glutamic acid) sol-gel hybrids through calcium chelation.

    PubMed

    Valliant, Esther M; Romer, Frederik; Wang, Daming; McPhail, David S; Smith, Mark E; Hanna, John V; Jones, Julian R

    2013-08-01

    Bioactive glasses and inorganic/organic hybrids have great potential as biomedical implant materials. Sol-gel hybrids with interpenetrating networks of silica and biodegradable polymers can combine the bioactive properties of a glass with the toughness of a polymer. However, traditional calcium sources such as calcium nitrate and calcium chloride are unsuitable for hybrids. In this study calcium was incorporated by chelation to the polymer component. The calcium salt form of poly(γ-glutamic acid) (γCaPGA) was synthesized for use as both a calcium source and as the biodegradable toughening component of the hybrids. Hybrids of 40wt.% γCaPGA were successfully formed and had fine scale integration of Ca and Si ions, according to secondary ion mass spectrometry imaging, indicating a homogeneous distribution of organic and inorganic components. (29)Si magic angle spinning nuclear magnetic resonance data demonstrated that the network connectivity was unaltered with changing polymer molecular weight, as there was no perturbation to the overall Si speciation and silica network formation. Upon immersion in simulated body fluid a hydroxycarbonate apatite surface layer formed on the hybrids within 1week. The polymer molecular weight (Mw 30-120kDa) affected the mechanical properties of the resulting hybrids, but all hybrids had large strains to failure, >26%, and compressive strengths, in excess of 300MPa. The large strain to failure values showed that γCaPGA hybrids exhibited non-brittle behaviour whilst also incorporating calcium. Thus calcium incorporation by chelation to the polymer component is justified as a novel approach in hybrids for biomedical materials. PMID:23632373

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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.)] ...

  8. SANITARY DIPS WITH CALCIUM PROPIONATE, CALCIUM CHLORIDE, OR A CALCIUM AMINO ACID CHELATE MAINTAIN QUALITY AND SHELF STABILITY OF HONEYDEW CHUNKS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Freshly cut honeydew chunks were dipped for 30 seconds in a solution containing 100 uL/L sodium hypochlorite (ClO) without and with a 40 mM concentration of calcium (Ca) propionate, a Ca amino acid chelate formulation (Ca chelate), calcium chloride (CaCl2) or not treated. Respiration and ethylene p...

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

    PubMed

    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

  10. Synthesis of a new bifunctional chelating agent for radioimmunotherapy: Cyclohexyl fused tetraazacyclodo-decanetetraacetic acid

    SciTech Connect

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

    1996-05-01

    Preorganization of the coordinating groups within a chelating agent increases the stability of its metal-ligand complexes. For example, 1,2-diaminocyclo-hexanetetraacetic acid (CDTA) forms metal complexes with stability constants 1-3 orders of magnitude higher than the corresponding complexes of EDTA. Incorporation of a cyclohexyl group into a macrocyclic ligand produces a similar effect; stability constants of Cu complexes of tetrathiocyclotetradecanes are increased by 1.5 orders of magnitude by incorporating one cyclohexyl group into the macrocyclic ring and 3 orders of magnitude by incorporating two cyclohexyl moieties. In this study, we have synthesized cycohexyl DOTA (C-DOTA) in which the cyclohexyl group is fused to two carbons of the macrocyclic ring. Alkylation of disodium ethylene ditosylamide with trans-1,2-di(bromoacetamido)cyclohexane afforded the C{sub 8}N{sub 4} macrocycle. Reduction with lithium aluminum hydride not only reduced the amide moieties to amines but also removed the tosyl protecting groups affording the cyclohexylcyclen. Cyanomethylation followed by hydrolysis gave C-DOTA in an overall yield of 9.4%. C-DOTA is expected to offer improvements in the biodistribution of radiometal immunoconjugates for radioimmunotherapy, in particular with Sc-47, Y-90, and Sm-153 that have given encouraging results using the plain DOTA ligand.

  11. Spectrophotometric Determination and Removal of Unchelated Europium Ions from Solutions Containing Eu-Diethylenetriaminepentaacetic Acid Chelate-Peptide Conjugates1

    PubMed Central

    Dayan Elshan, N. G. R.; Patek, Renata; Vagner, Josef; Mash, Eugene A.

    2014-01-01

    Europium chelates conjugated with peptide ligands are routinely used as probes for conducting in vitro binding experiments. The presence of unchelated Eu ions in these formulations gives high background luminescence and can lead to poor results in binding assays. In our experience, the reported methods for purification of these probes do not achieve adequate removal of unchelated metal ions in a reliable manner. In this work, a xylenol orange-based assay for the quantification of unchelated metal ions was streamlined and used to determine levels of metal ion contamination, as well as the success of metal ion removal upon attempted purification. We compared the use of Empore™ chelating disks and Chelex® 100 resin for the selective removal of unchelated Eu ions from several Eu-diethylenetriaminepentaacetic acid chelate-peptide conjugates. Both purification methods gave complete and selective removal of the contaminant metal ions. However, Empore™ chelating disks were found to give much higher recoveries of the probes under the conditions utilized. Related to the issue of probe recovery, we also describe a significantly more efficient method for the synthesis of one such probe using Rink amide AM resin in place of Tentagel S resin. PMID:25058927

  12. Macrocyclic bifunctional chelating agents

    DOEpatents

    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.

  13. Chelation in Metal Intoxication

    PubMed Central

    Flora, Swaran J.S.; Pachauri, Vidhu

    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-dimercaptosuccinic acid effectively promote renal metal excretion, but their ability to access intracellular metals is weak. Newer strategies to address these drawbacks like combination therapy (use of structurally different chelating agents) or co-administration of antioxidants have been reported recently. In this review we provide an update of the existing chelating agents and the various strategies available for the treatment of heavy metals and metalloid intoxications. PMID:20717537

  14. Nitrogen-doped carbon nanofoam derived from amino acid chelate complex for supercapacitor applications

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, Prakash; Shanmugam, Sangaraju

    2016-06-01

    We report a novel strategy to fabricate the nitrogen-doped mesoporous carbon nanofoam structures (N-MCNF), derived from magnesium amino acid chelate complex (Mg-acc-complex) for its application towards high performance supercapacitor (SCs) system. A series of N-MCNF with well-connected carbon nanofoam structure have been developed by varying the synthesis temperature. The fabricated N-MCNF material possesses a high surface area (1564 m2 g-1) and pore volume (1.767 cm3 g-1) with nitrogen content of 3.42 wt%. A prototypical coin cell type symmetric N-MCNF SC device has been assembled with 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIMBF4] ionic liquid electrolyte, and evaluated for SCs studies. The N-MCNF with high textural properties delivers unprecedented SC performance, such as high specific capacitance (204 Fg-1 at 0.25 Ag-1, 25 °C), high energy density (63.4 Wh kg-1), high power density (35.9 kW kg-1) and long-term cycle life (32,500 cycles). Significantly, N-MCNF materials exhibited high power rate performance, at 500 mV-1 (115 Fg-1) and 25 Ag-1 (166 Fg-1) owing to the uniform mesopore size distribution (∼4 nm). The N-MCNF SC device delivered maximum energy densities of 83.4 and 93.3 Wh kg-1 at 60 °C and 90 °C, respectively. Such outstanding N-MCNF SC device is successfully demonstrated in solar energy harvester applications.

  15. Release of cetyl pyridinium chloride from fatty acid chelate temporary dental cement

    PubMed Central

    Hurt, Andrew; Coleman, Nichola J.; Tüzüner, Tamer; Bagis, Bora; Korkmaz, Fatih Mehmet; Nicholson, John W.

    2016-01-01

    Abstract Objective To determine whether the antimicrobial nature of a fatty acid chelate temporary dental cement can be enhanced by the addition of 5% cetyl pyridinium chloride (CPC). Materials and methods The temporary cement, Cavex Temporary was employed, and additions of CPC were made to either the base or the catalyst paste prior to mixing the cement. Release of CPC from set cement specimens was followed using reverse-phase HPLC for a period of up to 2 weeks following specimen preparation. Potential interactions between Cavex and CPC were examined by Fourier transform infrared spectroscopy (FTIR) and antimicrobial effects were determined using zone of inhibition measurements after 24 h with disc-shaped specimens in cultured Streptococcus mutans. Results FTIR showed no interaction between CPC and the components of the cement. CPC release was found to follow a diffusion mechanism for the first 6 h or so, and to equilibrate after approximately 2 weeks, with no significant differences between release profiles when the additive was incorporated into the base or the catalyst paste. Diffusion was rapid, and had a diffusion coefficient of approximately 1 × 10−9 m2 s−1 in both cases. Total release was in the range 10–12% of the CPC loading. Zones of inhibition around discs containing CPC were significantly larger than those around the control discs of CPC-free cement. Conclusions The antimicrobial character of this temporary cement can be enhanced by the addition of CPC. Such enhancement is of potential clinical value, though further in vivo work is needed to confirm this. PMID:27335898

  16. Enteric-coated tablet of risedronate sodium in combination with phytic acid, a natural chelating agent, for improved oral bioavailability.

    PubMed

    Kim, Jeong S; Jang, Sun W; Son, Miwon; Kim, Byoung M; Kang, Myung J

    2016-01-20

    The oral bioavailability (BA) of risedronate sodium (RS), an antiresorptive agent, is less than 1% due to its low membrane permeability as well as the formation of non-absorbable complexes with multivalent cations such as calcium ion (Ca(2+)) in the gastrointestinal tract. In the present study, to increase oral BA of the bisphosphonate, a novel enteric-coated tablet (ECT) dosage form of RS in combination with phytic acid (IP6), a natural chelating agent recognized as safe, was formulated. The chelating behavior of IP6 against Ca(2+), including a stability constant for complex formulation was characterized using the continuous variation method. Subsequently, in vitro dissolution profile and in vivo pharmacokinetic profile of the novel ECT were evaluated comparatively with that of the marketed product (Altevia, Sanofi, US), an ECT containing ethylenediaminetetraacetic acid (EDTA) as a chelating agent, in beagle dogs. The logarithm of stability constant for Ca(2+)-IP6 complex, an equilibrium constant approximating the strength of the interaction between two chemicals to form complex, was 19.05, which was 3.9-fold (p<0.05) and 1.7-fold (p<0.05) higher than those of Ca(2+)-RS and Ca(2+)-EDTA complexes. The release profile of RS from both enteric-coated dosage forms was equivalent, regardless of the type of chelating agent. An in vivo absorption study in beagle dogs revealed that the maximum plasma concentration and area under the curve of RS after oral administration of IP6-containing ECT were approximately 7.9- (p<0.05) and 5.0-fold (p<0.05) higher than those of the marketed product at the same dose (35mg as RS). Therefore, our study demonstrates the potential usefulness of the ECT system in combination with IP6 for an oral therapy with the bisphosphonate for improved BA. PMID:26594027

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  18. Synthesis of an Isomer of the Decalinoyltetramic Acid Methiosetin by a Stereocontrolled IMDA Reaction of a Metal-Chelated 3-Trienoyltetramate.

    PubMed

    Winterer, Markus; Kempf, Karl; Schobert, Rainer

    2016-09-01

    An isomer of the 3-decalinoyltetramic acid methiosetin was synthesized for the first time. The decalin moiety was established by a late-stage intramolecular Diels-Alder cyclization catalyzed by Me2AlCl or La(OTf)3. Its high diastereoselectivity arose from stereoinduction by a well-defined metal O,O-chelate complex of the 3-acyltetramic acid moiety. The nature of the metal and the bulkiness of the residues at the tetramic acid chelator are decisive for the stereochemical outcome. PMID:27551958

  19. Synthesis and chelation properties of a new polymeric ligand derived from 1-amino-2-naphthol-4-sulfonic Acid.

    PubMed

    Manivannan, Dhanasekaran; Biju, Valsala Madhavan Nair

    2015-01-01

    A novel chelating resin for preconcentration of heavy metals from various seawater samples has been developed by condensing 1-amino-2-hydroxy-7-[(4-hydroxyphenyl)diazenyl] naphthalene-4-sulfonic acid (AHDNS) with formaldehyde (1:2 mole ratio) in the presence of oxalic acid as the catalyst. The resin thus obtained was used as a solid sorbent for the separation of divalent metal ions present at trace levels in seawater. The functionalized phenol (AHDNS) was characterized by spectral studies. The polymeric resin AHDNS-formaldehyde (AHDNS-F) obtained by condensing the functionalized phenol and formaldehyde was characterized by IR and NMR spectral studies. The chelating property of the AHDNS-F resin towards divalent metal ions was studied as a function of pH and in the presence of electrolyte. The metal uptake properties of the resin were determined by using an atomic absorption spectrophotometer. This procedure was validated for recovery of divalent metal ions from seawater samples. The recoveries of cadmium, cobalt, copper, manganese, lead, and zinc were above 92% under the optimum preconcentration conditions. The LOD was <0.73 μg/L and the RSDs were <2%. Thus, the AHDNS-F resin can be widely used as a solid sorbent for the preconcentration of trace metals at ppm levels in seawater samples. PMID:25857896

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

    PubMed

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

    2003-08-25

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

  1. A dual chelating sol–gel synthesis of BaTiO{sub 3} nanoparticles with effective photocatalytic activity for removing humic acid from water

    SciTech Connect

    Wang, Peigong; Fan, Caimei; Wang, Yawen; Ding, Guangyue; Yuan, Peihong

    2013-02-15

    Graphical abstract: The cubic phase BaTiO{sub 3} nanoparticles can be obtained at 600 °C and changed into tetragonal phase at 900 °C by a dual chelating sol–gel method, and the photocatalytic activities of the photocatalysts calcined at different temperatures were investigated by the removal of humic acid (HA) from water under UV light irradiation. Highlights: ► The humic acid in water was firstly degradated by BaTiO{sub 3} photocatalyst. ► The cubic BaTiO{sub 3} was obtained and changed into tetragonal phase at lower temperature. ► The chelating agents had an important influence on the phase formation of BaTiO{sub 3}. ► The tetragonal phase BaTiO{sub 3} calcined at 900 °C exhibited higher photocatalytic activity under UV irradiation. -- Abstract: In this paper, a dual chelating sol–gel method was used to synthesize BaTiO{sub 3} nanoparticles by using acetylacetone and citric acid as chelating agents. The samples calcined at different temperatures were analyzed by thermogravimetric and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), scanning electron microscope (SEM) and UV–vis diffuse reflectance spectra (UV–vis). The results indicated that cubic phase BaTiO{sub 3} nanoparticles about 19.6 nm can be obtained at 600 °C and changed into tetragonal phase at 900 °C about 97.1 nm. All the BaTiO{sub 3} nanoparticles showed effective photocatalytic activities on the removal of humic acid (HA) under UV light irradiation. A comparison of single (acetylacetone or citric acid) and dual chelating (acetylacetone and citric acid) synthetic processes was also studied and the results demonstrated that the dual chelating agents indeed reduced phase transformation temperature from cubic to tetragonal BaTiO{sub 3}.

  2. Paramagnetic relaxation enhancement of membrane proteins by incorporation of the metal-chelating unnatural amino acid 2-amino-3-(8-hydroxyquinolin-3-yl) propanoic acid (HQA)

    PubMed Central

    Park, Sang Ho; Wang, Vivian; Radoicic, Jasmina; De Angelis, Anna A.; Berkamp, Sabrina; Opella, Stanley J.

    2014-01-01

    The use of paramagnetic constraints in protein NMR is an active area of research because of the benefits of long-range distance measurements (>10 Å). One of the main issues in successful execution is the incorporation of a paramagnetic metal ion into diamagnetic proteins. The most common metal ion tags are relatively long aliphatic chains attached to the side chain of a selected cysteine residue with a chelating group at the end where it can undergo substantial internal motions, decreasing the accuracy of the method. An attractive alternative approach is to incorporate an unnatural amino acid (UAA) that binds metal ions at a specific site on the protein using the methods of molecular biology. Here we describe the successful incorporation of the unnatural amino acid 2-amino-3-(8-hydroxyquinolin-3-yl) propanoic acid (HQA) into two different membrane proteins by heterologous expression in E. coli. Fluorescence and NMR experiments demonstrate complete replacement of the natural amino acid with HQA and stable metal chelation by the mutated proteins. Evidence of site-specific intra- and inter-molecular PREs by NMR in micelle solutions sets the stage for the use of HQA incorporation in solid-state NMR structure determinations of membrane proteins in phospholipid bilayers. PMID:25430059

  3. Preservation of glutamic acid-iron chelate into montmorillonite to efficiently degrade Reactive Blue 19 in a Fenton system under sunlight irradiation at neutral pH

    NASA Astrophysics Data System (ADS)

    Huang, Zhujian; Wu, Pingxiao; Gong, Beini; Yang, Shanshan; Li, Hailing; Zhu, Ziao; Cui, Lihua

    2016-05-01

    To further enhance the visible light responsive property and the chemical stability of Fe/clay mineral catalysts, glutamic acid-iron chelate intercalated montmorillonite (G-Fe-Mt) was developed. The physiochemical properties of G-Fe-Mt were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), etc. The results showed that glutamic acid-iron chelates were successfully intercalated into the gallery of montmorillonite and the intercalated glutamic acid-iron chelate molecules were well preserved. The product G-Fe-Mt displayed excellent catalytic performance in heterogeneous photo-Fenton reaction under sunlight irradiation at acidic and neutral pH values. The chelation and the visible light responsiveness of glutamic acid produce a synergistic effect leading to greatly enhanced sunlight-Fenton reaction catalyzed by the heterogeneous G-Fe-Mt under neutral pH. G-Fe-Mt is a promising catalyst for advanced oxidation processes.

  4. Kinetics of sorption of Cu(II)-ethylenediaminetetraacetic acid chelated anions on cross-linked, polyaminated chitosan beads

    SciTech Connect

    Juang, R.S.; Ju, C.Y.

    1998-08-01

    Rates of sorption of Cu(II)-ethylenediaminetetraacetic acid (EDTA) chelated anions from aqueous solutions on cross-linked, poly(ethylenimine) (PEI)-modified chitosan beads were measured in a batch stirred vessel. All experiments were carried out in an equimolar solution of Cu(II) and EDTA (0.47--3.15 mol/m{sup 3}). It was shown that the rates of sorption increased with an increase in the initial concentration of Cu(II), pH, and temperature but decreased with an increase in the molecular weight of PEI introduced in the beads. The widely used homogeneous diffusion model based on Fick`s law and the shrinking core model cannot describe the sorption process. On the contrary, the kinetic data were well fit by the Elovich equation. The apparent activation energies evaluated (3.5--8.4 kcal/mol at pH 3) indicated the combined film and particle diffusion mechanism.

  5. Recovery of nickel and cobalt from organic acid complexes: adsorption mechanisms of metal-organic complexes onto aminophosphonate chelating resin.

    PubMed

    Deepatana, A; Valix, M

    2006-09-21

    This study examined the recovery of nickel and cobalt from organic acid complexes using a chelating aminophosphonate Purolite S950 resin. These metal complexes are generated by bioleaching nickel laterite ores, a commercial nickel and cobalt mineral oxide, with heterotrophic organism and their metabolites or organic acid products. Equilibrium adsorption tests were conducted as a function of Ni and Co concentrations (15-2000 mg/L), solution pH (0.01 and 0.1 M acids) and three metabolic complexing agents (citrate, malate and lactate). It was shown that the adsorption of the various Ni- and Co-complexes on Purolite were quite low, 16-18 and 5.4-9 mg/g of resin, respectively, in comparison to the smaller nickel ions and nickel sulfate. This was attributed to the bulky organic ligands which promoted crowding effect or steric hindrance. The adsorption of these complexes was further hampered by the strong affinity of the resin to H+ ions under acidic conditions. Mechanisms of adsorption, as inferred from the fitted empirical Langmuir and Freundlich models, were correlated to the proposed steric hindrance and competitive adsorption effects. Nickel and cobalt elution from the resin were found be effective and were independent of the type of metal complexes and metal concentrations. This study demonstrated the relative challenges involved in recovering nickel and cobalt from bioleaching solutions. PMID:16698178

  6. Intestinal interaction of bile acids, phospholipids, dietary fibers, and cholestyramine.

    PubMed

    Gallaher, D; Schneeman, B O

    1986-04-01

    Binding of bile acids and phospholipids to a number of dietary fibers and cholestyramine (CH) within the small intestine was determined. The fibers used were cellulose, wheat bran, oat bran, guar gum (GG), and lignin (LG). GG, LG, and CH bound significant quantities of bile acids. However, only the CH reduced the bile acid concentration within the aqueous phase of the intestinal contents. Significant phospholipid binding was found only with CH. None of the test substances significantly reduced the quantity of solubilized lipid. Multiple regression analysis indicated that the total quantity of bile acids and phospholipids in the aqueous phase of the intestinal contents was a significant predictor of the quantity of lipid solubilized within the contents (r2 = 0.67). The failure of GG and LG to significantly decrease the amount of solubilized lipid suggests that the hypocholesterolemic effect of these fibers is due more to their bile acid binding capacity than to an effect on lipid solubilization. PMID:3008573

  7. Regeneration of Three-Way Automobile Catalysts using Biodegradable Metal Chelating Agent – S, S-Ethylenediamine Disuccinic Acid (S, S-EDDS)

    EPA Science Inventory

    Regeneration of the activity of three-way catalytic converters (TWCs) was tested for the first time using a biodegradable metal chelating agent (S, S. Ethylenediamine disuccinic acid (S, S-EDDS). The efficiency of this novel environmentally friendly solvent in removing various c...

  8. Heavy metal removal from sludge with organic chelators: Comparative study of N, N-bis(carboxymethyl) glutamic acid and citric acid.

    PubMed

    Suanon, Fidèle; Sun, Qian; Dimon, Biaou; Mama, Daouda; Yu, Chang-Ping

    2016-01-15

    The applicability and performance of a new generation of biodegradable chelator, N, N-Bis(carboxymethyl) glutamic acid (GLDA), for extracting heavy metals from sewage sludge was carried out and compared with citric acid (CA). Targeted metals included Cd, Co, Cu, Zn, Ni and Cr, and their contents in the raw sludge were 63.1, 73.4, 1103.2, 2060.3, 483.9 and 604.1 mg kg(-1) (dry sludge basis), respectively. Metals were divided into six fractions including water soluble, exchangeable, carbonates bound, Fe-Mn bound, organic matters bound and residual fraction via chemical fractionation. Washing results showed that in general GLDA exhibited better performance compared with CA, with removal efficiency of 83.9, 87.3, 81.2, 85.6, 89.3 and 90.2% for Cd, Co, Cu, Zn, Ni and Cr, respectively at equilibrium pH = 3.3. Residual metals were better stabilized in the GLAD-washed sludge than in the CA-washed sludge, and were mostly tightly bonded to the residual fraction. Furthermore, CA promoted phosphorus (P) release while GLDA had an opposite effect and tended to retain P within sludge, which could be beneficial for further application in agricultural use. Findings from this study suggested that GLDA could be a potential replacement for refractory and less environmentally-friendly chelators in the extraction of metals from sludge. PMID:26520041

  9. Iron Chelation

    MedlinePlus

    ... iron overload and need treatment. What is iron overload? Iron chelation therapy is used when you have ... may want to perform: How quickly does iron overload happen? This is different for each person. It ...

  10. Comparison of synthetic chelators and low molecular weight organic acids in enhancing phytoextraction of heavy metals by two ecotypes of Sedum alfredii Hance.

    PubMed

    Liu, Dan; Islam, Ejazul; Li, Tingqiang; Yang, Xiaoe; Jin, Xiaofen; Mahmood, Qaisar

    2008-05-01

    Lab scale and pot experiments were conducted to compare the effects of synthetic chelators and low molecular weight organic acids (LMWOA) on the phytoextraction of multi-contaminated soils by two ecotypes of Sedum alfredii Hance. Through lab scale experiments, the treatment dosage of 5 and 10 mM for synthetic chelators and LMWOA, respectively, and the treatment time of 10 days were selected for pot experiment. In pot experiment, the hyperaccumulating ecotype (HE) was found more tolerant to the metal toxicity compared with the non-hyperaccumulating ecotype (NHE). EDTA for Pb, EDDS for Cu, and DTPA for Cu and Cd were found more effective to enhance heavy metal accumulation in the shoots of S. alfredii Hance. Compared with synthetic chelators, the phytoextraction ability of LMWOA was lesser. Considering the strong post-harvest effects of synthetic chelators, it is suggested that higher dosage of LMWOA could be practiced during phytoextraction, and some additional measures could also be taken to lower the potential environmental risks of synthetic chelators in the future studies. PMID:17904736

  11. Thermal inactivation of rabies and other rhabdoviruses: stabilization by the chelating agent ethylenediaminetetraacetic acid at physiological temperatures.

    PubMed

    Michalski, F; Parks, N F; Sokol, F; Clark, H F

    1976-07-01

    Thermal inactivation of rabies and several other rhabdoviruses was studied using virus suspended in several different diluents. Rabies serogroup viruses were more stable than Kern Canyon or vesicular stomatitis viruses. Limited studies of two fish rhabdoviruses requiring low temperatures (less than 33 C) for replication indicated that they were not markedly more thermolabile than rabies virus. Bovine serum protein components in complex cell culture media stabilized virus at 56 C, but at temperatures of less than or equal to 37 C, sodium tris (hydroxymethyl)-aminomethane (NT) buffer containing ethylenediaminetetraacetic acid (EDTA) (NTE) was a much more efficient stabilizer of virus infectivity. Chelating agents EDTA and ethyleneglycol-bis-(beta-aminoethyl ether)tetraacetic acid were equally efficient in protection of rabies virus infectivity; the effect of each was lost when excess Ca2+ was added. Bovine serum in NT or NTE buffers produced a thermostabilizing effect at 37 C not provided by the same serum concentration in complex cell culture media. Bovine serum was more efficient than EDTA in stabilizing virus infectivity during repeated cycles of freezing and thawing. PMID:181323

  12. Thermal inactivation of rabies and other rhabdoviruses: stabilization by the chelating agent ethylenediaminetetraacetic acid at physiological temperatures.

    PubMed Central

    Michalski, F; Parks, N F; Sokol, F; Clark, H F

    1976-01-01

    Thermal inactivation of rabies and several other rhabdoviruses was studied using virus suspended in several different diluents. Rabies serogroup viruses were more stable than Kern Canyon or vesicular stomatitis viruses. Limited studies of two fish rhabdoviruses requiring low temperatures (less than 33 C) for replication indicated that they were not markedly more thermolabile than rabies virus. Bovine serum protein components in complex cell culture media stabilized virus at 56 C, but at temperatures of less than or equal to 37 C, sodium tris (hydroxymethyl)-aminomethane (NT) buffer containing ethylenediaminetetraacetic acid (EDTA) (NTE) was a much more efficient stabilizer of virus infectivity. Chelating agents EDTA and ethyleneglycol-bis-(beta-aminoethyl ether)tetraacetic acid were equally efficient in protection of rabies virus infectivity; the effect of each was lost when excess Ca2+ was added. Bovine serum in NT or NTE buffers produced a thermostabilizing effect at 37 C not provided by the same serum concentration in complex cell culture media. Bovine serum was more efficient than EDTA in stabilizing virus infectivity during repeated cycles of freezing and thawing. PMID:181323

  13. Biodegradable chelate enhances the phytoextraction of copper by Oenothera picensis grown in copper-contaminated acid soils.

    PubMed

    González, Isabel; Cortes, Amparo; Neaman, Alexander; Rubio, Patricio

    2011-07-01

    Oenothera picensis plants (Fragrant Evening Primrose) grow in the acid soils contaminated by copper smelting in the coastal region of central Chile. We evaluated the effects of the biodegradable chelate MGDA (methylglycinediacetic acid) on copper extraction by O. picensis and on leaching of copper through the soil profile, using an ex situ experiment with soil columns of varying heights. MGDA was applied in four rates: 0 (control), 2, 6 and 10 mmol plant(-1). MGDA application significantly increased biomass production and foliar concentration, permitting an effective increase in copper extraction, from 0.09 mg plant(-1) in the control, to 1.3mg plant(-1) in the 6 and 10 mmol plant(-1) treatments. With 10 mmol plant(-1) rate of MGDA, the copper concentration in the leachate from the 30 cm columns was 20 times higher than in the control. For the 60 cm columns, copper concentration was 2 times higher than the control. It can be concluded that at increased soil depths, copper leaching would be minimal and that MGDA applications at the studied rates would not pose a high risk for leaching into groundwater. It can thus be stated that applications of MGDA are an effective and environmentally safe way to improve copper extraction by O. picensis in these soils. PMID:21470657

  14. Production of mullite fibers

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S. (Inventor); Sparks, J. Scott (Inventor)

    1991-01-01

    Disclosed here is a process for making mullite fibers wherein a hydrolizable silicon compound and an aluminum compound in the form of a difunctional aluminum chelate are hydrolized to form sols using water and an alcohol with a catalytic amount of hydrochloric acid. The sols are mixed in a molar ratio of aluminum to silicon of 3 to 1 and, under polycondensation conditions, a fibrous gel is formed. From this gel the mullite fibers can be produced.

  15. Magnetic Resonance Imaging of Therapy-Induced Necrosis Using Gadolinium-Chelated Polyglutamic Acids

    SciTech Connect

    Jackson, Edward F.; Esparza-Coss, Emilio; Wen Xiaoxia; Ng, Chaan S.; Daniel, Sherita L.; Price, Roger E.; Rivera, Belinda; Charnsangavej, Chusilp; Gelovani, Juri G.; Li Chun . E-mail: cli@di.mdacc.tmc.edu

    2007-07-01

    Purpose: Necrosis is the most common morphologic alteration found in tumors and surrounding normal tissues after radiation therapy or chemotherapy. Accurate measurement of necrosis may provide an early indication of treatment efficacy or associated toxicity. The purpose of this report is to evaluate the selective accumulation of polymeric paramagnetic magnetic resonance (MR) contrast agents-gadolinium p-aminobenzyl-diethylenetriaminepentaacetic acid-poly(glutamic acid) (L-PG-DTPA-Gd and D-PG-DTPA-Gd)-in necrotic tissue. Methods and Materials: Two different solid tumor models, human Colo-205 xenograft and syngeneic murine OCA-1 ovarian tumors, were used in this study. Necrotic response was induced by treatment with poly(L-glutamic acid)-paclitaxel conjugate (PG-TXL). T{sub 1}-weighted spin-echo images were obtained immediately and up to 4 days after contrast injection and compared with corresponding histologic specimens. Two low-molecular-weight contrast agents, DTPA-Gd and oligomeric(L-glutamic acid)-DTPA-Gd, were used as nonspecific controls. Results: Initially, there was minimal tumor enhancement after injection of either L-PG-DTPA-Gd or D-PG-DTPA-Gd, but rapid enhancement after injection of low-molecular-weight agents. However, polymeric contrast agents, but not low-molecular-weight contrast agents, caused sustained enhancement in regions of tumor necrosis in both tumors treated with PG-TXL and untreated tumors. These data indicate that high molecular weight, rather than in vivo biodegradation, is necessary for the specific localization of polymeric MR contrast agents to necrotic tissue. Moreover, biotinylated L-PG-DTPA-Gd colocalized with macrophages in the tumor necrotic areas, suggesting that selective accumulation of L- and D-PG-DTPA-Gd in necrotic tissue was mediated through residing macrophages. Conclusions: Our data suggest that MR imaging with PG-DTPA-Gd may be a useful technique for noninvasive characterization of treatment-induced necrosis.

  16. Enhancement of 5-aminolevulinic-acid-induced photodynamic therapy using light-dose fractionation and iron-chelating agents

    NASA Astrophysics Data System (ADS)

    Curnow, Alison; Postle-Hacon, Matthew J.; MacRobert, Alexander J.; Bown, Stephen G.

    1998-05-01

    Preliminary clinical studies of 5-aminolaevulinic acid (ALA) induced photodynamic therapy (PDT) with the maximum tolerated oral dose (60 mg/kg), currently appear to only produce limited amounts of necrosis. We have studied ways of increasing this effect without increasing the drug dose. In normal, female, Wistar rats we have found it possible to increase the area of necrosis produced in the colon substantially by simply interrupting the light dose (25 J, 635 nm, 100 mW) for a short period of time, while all other variables are kept constant. It is possible to cause up to four times more necrosis with a dose of 200 mg/kg ALA i.v. by introducing a single 150 second interval which splits the light dose into two fractions after 5 J has been delivered. We have found these parameters to be optimal for this dose. Likewise, in the same model, the effect of the iron chelating agent, CP94, was also investigated and we have found it possible to produce three times the area of necrosis with the simultaneous administration of 100 mg/kg CP94 i.v. and 50 mg/kg ALA i.v. We have therefore shown, that it is possible to significantly increase the effects of ALA induced PDT without increasing the administered dose of ALA by utilizing these techniques.

  17. Protective effect of some amino acids synthesized derivatives and their chelates on Escherichia coli under X-ray irradiation.

    PubMed

    Kirakosyan, G; Torgomyan, H; Malakyan, M; Bajinyan, S; Trchounian, A

    2013-08-01

    The protective effects of novel synthesized derivatives of some amino acids--nicotinyl-L-tyrosinate and nicotinyl-L-tryptophanate schiff bases and their Cu(II) and Mn(II) chelates on growth, survival and membrane-associated ATPase activity of E. coli under X-ray irradiation were investigated. The specific growth rate and survival of E. coli were decreased at 10, 20 and 30 Gy doses. However, as 30 Gy was found to be the most effective irradiation dose, it was chosen for studying the radio-protective properties of different compounds. These compounds could increase the bacterial cell protection against X-ray irradiation in concentration-dependent manner. They had a role in stimulation of synthesis or regulation of activity of metal-dependent enzymes, required for reversing the X-ray irradiation damage. The study may prove useful for further estimation of the effectiveness of different compounds as radio-protectors on bacteria and other cells, especially mammalian cells under X-ray irradiation. PMID:24772948

  18. Rigid bifunctional chelating agents

    DOEpatents

    Sweet, Mark P.; Mease, Ronnie C.; Srivastava, Suresh C.

    1998-07-21

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

  19. Rigid bifunctional chelating agents

    DOEpatents

    Sweet, Mark P.; Mease, Ronnie C.; Srivastava, Suresh C.

    2000-02-08

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

  20. Rigid bifunctional chelating agents

    DOEpatents

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

    1998-07-21

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

  1. Microbial degradation of chelating agents used in detergents with special reference to nitrilotriacetic acid (NTA).

    PubMed

    Egli, T; Bally, M; Uetz, T

    1990-01-01

    The extensive use of phosphate-based detergents and agricultural fertilizers is one of the main causes of the world-wide eutrophication of rivers and lakes. To ameliorate such problems partial or total substitution of phosphates in laundry detergents by synthetic, non-phosphorus containing complexing agents is practiced in several countries. The physiological, biochemical and ecological aspects of the microbial degradation of the complexing agents most frequently used, such as polyphosphates, aminopolycarboxylates (especially of nitrilotriacetic acid), and phosphonates are reviewed. PMID:1368145

  2. Evaluation of 2-methyl-3-hydroxy-4-pyridinecarboxylic acid as a possible chelating agent for iron and aluminium.

    PubMed

    Dean, Annalisa; Ferlin, Maria Grazia; Brun, Paola; Castagliuolo, Ignazio; Badocco, Denis; Pastore, Paolo; Venzo, Alfonso; Bombi, G Giorgio; Di Marco, Valerio B

    2008-04-01

    In view of a possible application to Fe and Al chelation therapy, 2-methyl-3-hydroxy-4-pyridinecarboxylic acid (DT2) was synthesised, and its complex formation, electrochemical and cytotoxic properties were studied. The complexing properties of DT2 towards Fe(III) and Al(III) were investigated in aqueous 0.6 m (Na)Cl at 25 degrees C by means of potentiometric titrations, UV-vis spectrophotometry, and 1H NMR spectroscopy. DT2 is a triprotic acid (H3L+) having pKa1 = 0.47, pKa2 = 5.64 and pKa3 = 11.18. The metal-ligand complexes observed in solution and their corresponding stability constants (log beta values) are the following: FeLH (19.38), FeL (16.01), FeLH(-1) (12.28), FeL2H2 (37.29), FeL3H3 (53.41), FeL3H2 (47.99), FeL3H (41.21) and FeL3 (34.1); AlLH (17.43), AlL2H2 (33.74), AlL2H (27.6), AlL3H3 (48.72), AlL3H2 (42.67), AlL3H (35.8) and AlL3 (27.92). The complex formation between DT2 and Fe(II) was studied by UV-vis: the weak complex FeLH (log beta = 15.8) was detected. DT2 shows a lower complexation efficiency with Fe(III) and Al(III) than that of other available chelators, but higher than that of its non-methylated analogue 3-hydroxy-4-pyridinecarboxylic acid (DT0). The electrochemical behaviour of DT2 was investigated by means of cyclic voltammetry, indicating that the oxidation of the ligand proceeds through a two electron process with a CECE mechanism. Voltammetric curves suggest that the oxidation or the reduction of DT2 in vivo is unlikely. According to the thermodynamic data, also the Fe(III)-DT2 complexes do not undergo redox cycling at physiological pH. Amperometric titrations of solutions containing Fe(III) and DT2 at pH = 5 indicated the same Fe(III) : ligand stoichiometric ratio as calculated from potentiometric data. The toxicity of DT2 and of other simple hydroxypyridinecarboxylic acids was investigated in vitro and no cytotoxic activity was observed (IC50 > 0.1 mM) on cancer cell lines and also on primary human cells, following a three day

  3. Fiber

    MedlinePlus

    ... short period of time can cause intestinal gas ( flatulence ), bloating , and abdominal cramps . This problem often goes ... 213. National Research Council. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and ...

  4. Fluid extraction using carbon dioxide and organophosphorus chelating agents

    DOEpatents

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

    1998-11-24

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

  5. Fluid extraction using carbon dioxide and organophosphorus chelating agents

    DOEpatents

    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.

  6. An expanded porphyrin approach toward transactinium chelation and the development of porphyrin-coated optical fibers as potential actinide sensors

    SciTech Connect

    Klunder, G.; Silva, R.

    1994-12-01

    Characterization of the contamination at DOE waste sites and facilities is necessary during environmental restoration. Characterization of toxic waste in containers and storage tanks is needed for effective waste management. Therefore, analytical and monitoring systems are needed for real-time analysis and feedback. The development of in-situ methods to measure chemical properties by specialized instrumentation capable of real-time analysis, without sacrificing sensitivity, has been identified as an area of needed development. Absorption spectroscopy is widely used and considered to be one of the most reliable techniques available for the qualitative and quantitative determination of sample composition. With the advancements in fiber optic technology, using light for remote in-situ sensing of groundwater contaminants has become practical. Significant progress has been made in the area of fiber-optic chemical sensors as can be seen by the number of recent review articles. The objective of this work is to develop a remote sensor for real-time measurement of actinides and concentrations in environmental or process waters based on absorption spectroscopy using internal reflection spectroscopy. Porphyrin coated silica wafers were prepared and the sensitivity and selectivity to actinides was determined.

  7. Soil washing of chromium- and cadmium-contaminated sludge using acids and ethylenediaminetetra acetic acid chelating agent.

    PubMed

    Gitipour, Saeid; Ahmadi, Soheil; Madadian, Edris; Ardestani, Mojtaba

    2016-01-01

    In this research, the effect of soil washing in the removal of chromium- and cadmium-contaminated sludge samples collected from Pond 2 of the Tehran Oil Refinery was investigated. These metals are considered as hazardous substances for human health and the environment. The carcinogenicity of chromate dust has been established for a long time. Cadmium is also a potential environmental toxicant. This study was carried out by collecting sludge samples from different locations in Pond 2. Soil washing was conducted to treat the samples. Chemical agents, such as acetic acid, ethylenediaminetetra acetic acid (EDTA) and hydrochloric acid, were used as washing solutions to remove chromium and cadmium from sludge samples. The results of this study indicated that the highest removal efficiencies from the sludge samples were achieved using a 0.3 M HCl solution with 82.69% and 74.47% for chromium and cadmium, respectively. EDTA (0.1 M) in the best condition extracted 66.81% of cadmium and 72.52% of chromium from the sludges. The lowest efficiency values for the samples, however, were achieved using 3 M acetic acid with 41.7% and 46.96% removals for cadmium and chromium, respectively. The analysis of washed sludge indicated that the heavy metals removal decreased in the order of 3 M acetic acid < 0.1 M EDTA<0.3 M HCl, thus hydrochloric acid appears to offer a greater potential as a washing agent in remediating the sludge samples. PMID:26599728

  8. Succinic acid production from acid hydrolysate of corn fiber by Actinobacillus succinogenes.

    PubMed

    Chen, Kequan; Jiang, Min; Wei, Ping; Yao, Jiaming; Wu, Hao

    2010-01-01

    Dilute acid hydrolysate of corn fiber was used as carbon source for the production of succinic acid by Actinobacillus succinogenes NJ113. The optimized hydrolysis conditions were obtained by orthogonal experiments. When corn fiber particles were of 20 mesh in size and treated with 1.0% sulfuric acid at 121 degrees C for 2 h, the total sugar yield could reach 63.3%. It was found that CaCO(3) neutralization combined with activated carbon adsorption was an effective method to remove fermentation inhibitors especially furfural that presented in the acid hydrolysate of corn fiber. Only 5.2% of the total sugar was lost, while 91.9% of furfural was removed. The yield of succinic acid was higher than 72.0% with the detoxified corn fiber hydrolysate as the carbon source in anaerobic bottles or 7.5 L fermentor cultures. It was proved that the corn fiber hydrolysate could be an alternative to glucose for the production of succinic acid by A. succinogenes NJ113. PMID:18830824

  9. Methodology for detecting residual phosphoric acid in polybenzoxazole fibers.

    PubMed

    Park, Eun Su; Sieber, John; Guttman, Charles; Rice, Kirk; Flynn, Kathleen; Watson, Stephanie; Holmes, Gale

    2009-12-01

    Because of the premature failure of in-service soft-body armor containing the ballistic fiber poly[(benzo-[1,2-d:5,4-d']-benzoxazole-2,6-diyl)-1,4-phenylene] (PBO), the Office of Law Enforcement Standards (OLES) at the National Institute of Standards and Technology (NIST) initiated a research program to investigate the reasons for this failure and to develop testing methodologies and protocols to ensure that these types of failures do not reoccur. In a report that focused on the stability of the benzoxazole ring that is characteristic of PBO fibers, Holmes, G. A.; Rice, K.; Snyder, C. R. J. Mater. Sci. 2006, 41, 4105-4116, showed that the benzoxazole ring was susceptible to hydrolytic degradation under acid conditions. Because of the processing conditions for the fibers, it is suspected by many researchers that residual phosphoric acid may cause degradation of the benzoxazole ring resulting in a reduction of ballistic performance. Prior to this work, no definitive data have indicated the presence of phosphoric acid since the residual phosphorus is not easily extracted and the processed fibers are known to incorporate phosphorus containing processing aids. Methods to efficiently extract phosphorus from PBO are described in this article. Further, characterization determined that the majority of the extractable phosphorus in PBO was attributed to the octyldecyl phosphate processing aid with some phosphoric acid being detected. Analysis by matrix assisted laser desorption ionization of model PBO oligomers indicates that the nonextractable phosphorus is attached to the PBO polymer chain as a monoaryl phosphate ester. The response of model aryl phosphates to NaOH exposure indicates that monoaryl phosphate ester is stable to NaOH washes used in the manufacturing process to neutralize the phosphoric acid reaction medium and to extract residual phosphorus impurities. PMID:19899783

  10. The Effect of Surface Modification of Aligned Poly-L-Lactic Acid Electrospun Fibers on Fiber Degradation and Neurite Extension

    PubMed Central

    Schaub, Nicholas J.; Le Beux, Clémentine; Miao, Jianjun; Linhardt, Robert J.; Alauzun, Johan G.; Laurencin, Danielle; Gilbert, Ryan J.

    2015-01-01

    The surface of aligned, electrospun poly-L-lactic acid (PLLA) fibers was chemically modified to determine if surface chemistry and hydrophilicity could improve neurite extension from chick dorsal root ganglia. Specifically, diethylenetriamine (DTA, for amine functionalization), 2-(2-aminoethoxy)ethanol (AEO, for alcohol functionalization), or GRGDS (cell adhesion peptide) were covalently attached to the surface of electrospun fibers. Water contact angle measurements revealed that surface modification of electrospun fibers significantly improved fiber hydrophilicity compared to unmodified fibers (p < 0.05). Scanning electron microscopy (SEM) of fibers revealed that surface modification changed fiber topography modestly, with DTA modified fibers displaying the roughest surface structure. Degradation of chemically modified fibers revealed no change in fiber diameter in any group over a period of seven days. Unexpectedly, neurites from chick DRG were longest on fibers without surface modification (1651 ± 488 μm) and fibers containing GRGDS (1560 ± 107 μm). Fibers modified with oxygen plasma (1240 ± 143 μm) or DTA (1118 ± 82 μm) produced shorter neurites than the GRGDS or unmodified fibers, but were not statistically shorter than unmodified and GRGDS modified fibers. Fibers modified with AEO (844 ± 151 μm) were significantly shorter than unmodified and GRGDS modified fibers (p<0.05). Based on these results, we conclude that fiber hydrophilic enhancement alone on electrospun PLLA fibers does not enhance neurite outgrowth. Further work must be conducted to better understand why neurite extension was not improved on more hydrophilic fibers, but the results presented here do not recommend hydrophilic surface modification for the purpose of improving neurite extension unless a bioactive ligand is used. PMID:26340351

  11. Method and apparatus for back-extracting metal chelates

    DOEpatents

    Wai, Chien M.; Smart, Neil G.; Lin, Yuehe

    1998-01-01

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

  12. Method and apparatus for back-extracting metal chelates

    DOEpatents

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

    1998-08-11

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

  13. A new morphological approach for removing acid dye from leather waste water: preparation and characterization of metal-chelated spherical particulated membranes (SPMs).

    PubMed

    Şenay, Raziye Hilal; Gökalp, Safiye Meriç; Türker, Evren; Feyzioğlu, Esra; Aslan, Ahmet; Akgöl, Sinan

    2015-03-15

    In this study, p(HEMA-GMA) poly(hydroxyethyl methacrylate-co-glycidyl methacrylate) spherical particulated membranes (SPMs) were produced by UV-photopolymerization and the synthesized SPMs were coupled with iminodiacetic acid (IDA). Finally the novel SPMs were chelated with Cr(III) ions as ligand and used for removing acid black 210 dye. Characterizations of the metal-chelated SPMs were made by SEM, FTIR and swelling test. The water absorption capacities and acid dye adsorption properties of the SPMs were investigated and the results were 245.0, 50.0, 55.0 and 51.9% for p(HEMA), p(HEMA-GMA), p(HEMA-GMA)-IDA and p(HEMA-GMA)-IDA-Cr(III) SPMs respectively. Adsorption properties of the p(HEMA-GMA)-IDA-Cr(III) SPMs were investigated under different conditions such as different initial dye concentrations and pH. The optimum pH was observed at 4.3 and the maximum adsorption capacity was determined as 885.14 mg/g at about 8000 ppm initial dye concentration. The concentrations of the dyes were determined using a UV/Vis Spectrophotometer at a wavelength of 435 nm. Reusability of p(HEMA-GMA)-IDA-Cr(III) SPMs was also shown for five adsorption-desorption cycles without considerable decrease in its adsorption capacity. Finally, the results showed that the metal-chelated p(HEMA-GMA)-IDA SPMs were effective sorbent systems removing acid dye from leather waste water. PMID:25585142

  14. Benzyl and Methyl Fatty Hydroxamic Acids Based on Palm Kernel Oil as Chelating Agent for Liquid-Liquid Iron(III) Extraction

    PubMed Central

    Haron, Md Jelas; Jahangirian, Hossein; Silong, Sidik; Yusof, Nor Azah; Kassim, Anuar; Rafiee-Moghaddam, Roshanak; Mahdavi, Behnam; Peyda, Mazyar; Abdollahi, Yadollah; Amin, Jamileh

    2012-01-01

    Liquid-liquid iron(III) extraction was investigated using benzyl fatty hydroxamic acids (BFHAs) and methyl fatty hydroxamic acids (MFHAs) as chelating agents through the formation of iron(III) methyl fatty hydroxamate (Fe-MFHs) or iron(III) benzyl fatty hydroxamate (Fe-BFHs) in the organic phase. The results obtained under optimized conditions, showed that the chelating agents in hexane extract iron(III) at pH 1.9 were realized effectively with a high percentage of extraction (97.2% and 98.1% for MFHAs and BFHAs, respectively). The presence of a large amount of Mg(II), Ni(II), Al(III), Mn(II) and Co(II) ions did affect the iron(III) extraction. Finally stripping studies for recovering iron(III) from organic phase (Fe-MFHs or Fe-BFHs dissolved in hexane) were carried out at various concentrations of HCl, HNO3 and H2SO4. The results showed that the desired acid for recovery of iron(III) was 5 M HCl and quantitative recovery of iron(III) was achieved from Fe(III)-MFHs and Fe(III)-BFHs solutions in hexane containing 5 mg/L of Fe(III). PMID:22408444

  15. Surface acid-base characteristics of fiber materials by contact angle measurements

    SciTech Connect

    Mao Youan . Dept. of Materials Science and Applied Chemistry)

    1993-11-05

    Contact angle measurements were used to study the surface acid-base characteristics of treated and untreated carbon fibers, and of treated and untreated silicon carbide fibers. It has been shown that, when untreated the surfaces of these two fibers exhibits amphoteric, but the base character is dominant. After oxidization in a liquid phase, the surface acid character of the carbon fibers changes little, whereas the base character becomes much stronger. The treatment, with boiling-concentrated HNO[sub 3] for three hours and the sintering treatment in air at 500 C. for eight hours, has little effect on the surface acid-base characteristics of the silicon carbide fibers.

  16. Effect of compost and biodegradable chelate addition on phytoextraction of copper by Oenothera picensis grown in Cu-contaminated acid soils.

    PubMed

    González, Isabel; Neaman, Alexander; Cortés, Amparo; Rubio, Patricio

    2014-01-01

    Oenothera picensis plants (Fragrant Evening Primrose) grow in the acid soils contaminated by Cu smelting in the coastal region of central Chile. We evaluated the effects of compost, at application rate of 5 kg m(-2), and biodegradable chelate MGDA (methylglycinediacetic acid), at application rate of 6 mmol plant(-1), on Cu phytoextraction by O. picensis, in field plots. No significant differences were found between treatments regarding aboveground biomass, shoot Cu concentrations and Cu phytoextraction of O. picensis. This lack of effects of the treatments was provoked by the large variability of soil properties, prior to applying of the treatments. The shoot Cu concentration in O. picensis positively and significantly correlated to exchangeable Cu concentration in the soil. Likewise, the aboveground biomass of O. picensis positively and significantly correlated to soil organic matter content. The Cu phytoextraction by O. picensis, in turn, positively and significantly correlated to both variables, i.e. exchangeable Cu concentration and organic matter content. The average Cu phytoextraction was 1.1 mg plant(-1), which is equivalent to 90 g ha(-1) at planting rate of 8 plants m(-2). In the chelate treatment, Cu phytoextraction was 2.6±2.1 mg plant(-1), which is equivalent to 212±171 g ha(-1) at planting rate of 8 plants m(-2). PMID:24034893

  17. Extremely enhanced photovoltaic properties of dye-sensitized solar cells by sintering mesoporous TiO2 photoanodes with crystalline titania chelated by acetic acid

    NASA Astrophysics Data System (ADS)

    Liu, Bo-Tau; Chou, Ya-Hui; Liu, Jin-Yan

    2016-04-01

    The study presents a significant improvement on the performance of dye-sensitized solar cells (DSSCs) through incorporating the crystalline titania chelated by acetic acid (TAc) into the mesoporous TiO2 photoanodes. The effects of TAc on the blocking layer, mesoporous TiO2 layer, and post-treatment have been investigated. The TAc blocking layer displays compact construction, revealing superior response time and resistance to suppress dark current compared to the blocking layer made from titanium(IV) isopropoxide (TTIP). The power conversion efficiency of DSSCs with the TAc treatment can reach as high as 10.49%, which is much higher than that of pristine DSSCs (5.67%) and that of DSSCs treated by TTIP (7.86%). We find that the TAc incorporation can lead to the decrease of charge transfer resistance and the increase of dye adsorption. The result may be attributed to the fact that the TAc possesses high crystallinity, exposed (101) planes, and acid groups chelated on surface, which are favorable for dye attachment and strong bonding at the FTO/TiO2 and the TiO2/TiO2 interfaces, These improvements result in the remarkable increase of photocurrent and thereby that of power conversion efficiency.

  18. Hydroxypyridonate chelating agents

    DOEpatents

    Raymond, Kenneth N.; Scarrow, Robert C.; White, David L.

    1987-01-01

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

  19. In vitro bile acid binding and short-chain fatty acid profile of flax fiber and ethanol co-products.

    PubMed

    Fodje, Adele M L; Chang, Peter R; Leterme, Pascal

    2009-10-01

    Fibers from flaxseed and co-products from ethanol production could be potential sources of dietary fiber in human diet. In vitro fermentation and bile acid binding models were used to investigate the metabolic effects of lignaMax (Bioriginal Food and Science Corp., Saskatoon, SK, Canada) flax meal, spent flax meal, soluble flax gum, wheat insoluble fiber (WIF), and rye insoluble fiber (RIF). Wheat and rye bran were used as reference samples. Bile acid binding of substrates was analysed at taurocholate ([(14)C]taurocholate) concentration of 12.5 mM. Soluble flax gum showed the highest bile acid binding (0.57 micromol/mg of fiber) (P acid binding between wheat bran (0.2 micromol/mg of fiber) and WIF (0.26 micromol/mg of fiber). RIF had higher (P acid binding (0.20 micromol/mg of fiber) than rye bran (0.13 micromol/mg of fiber). Substrates were hydrolyzed and incubated with pig fecal samples. Short-chain fatty acid (SCFA) profile and gas accumulation (G(f)) were compared. Soluble flax gum generated the highest amount of acetic and propionic acids. SCFA profiles of wheat/rye brans and WIF/RIF were similar (except for butyric acid). G(f) for soluble flax gum was greater (P < .001) than that of spent flax meal. G(f) values of the wheat samples were similar, whereas the G(f) of the rye bran was higher (P < .001) than that of RIF. Fractional degradation rate (micro(t = T/2)) (P < .001) was also recorded. The highest mu(t = T/2) was observed for the soluble flax gum. Oil-depleted flaxseed fractions and WIF/RIF (co-products from ethanol production) could be potential sources of dietary fiber in human nutrition. PMID:19857071

  20. FTIR, magnetic, 1H NMR spectral and thermal studies of some chelates of caproic acid: inhibitory effect on different kinds of bacteria.

    PubMed

    Refat, Moamen S; El-Korashy, Sabry A; Kumar, Deo Nandan; Ahmed, Ahmed S

    2008-06-01

    A convenient method for the preparation of complexes of the Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Zn2+, ZrO2+, UO2(2+), Zr4+ and Th4+ ions with caproic acid (Hcap) is reported and this has enabled 10 complexes of caproate anion to be formulated: [Cr(cap)3].5H2O, [Mn(cap)2(H2O)2], [Fe(cap)3].12H2O, [Co(cap)2(H2O)2].4H2O, [Ni(cap)2(H2O)2].3H2O, [Zn(cap)2], [ZrO(cap)2].3H2O, [UO2(cap)(NO3)], [Zr(cap)2(Cl)2] and [Th(cap)4]. These new complexes were synthesized and characterized by elemental analysis, molar conductivity, magnetic measurements, spectral methods (mid infrared, 1H NMR and UV-vis spectra) and simultaneous thermal analysis (TG and DTG) techniques. It has been found from the elemental analysis as well as thermal studies that the caproate ligand behaves as bidentate ligand and forming chelates with 1:1 (metal:ligand) stoichiometry for UO2(2+), 1:2 for (Mn2+, Co2+, Ni2+, Zn2+, ZrO2+ and Zr4+), 1:3 stoichiometry for (Cr3+ and Fe3+) and 1:4 for Th4+ caproate complexes, respectively, as bidentate chelating. The molar conductance measurements proved that the caproate complexes are non-electrolytes. The kinetic thermodynamic parameters such as: E*, DeltaH*, DeltaS* and DeltaG* are estimated from the DTG curves. The antibacterial activity of the caproic acid and their complexes was evaluated against some gram positive/negative bacteria. PMID:17766172

  1. Technical note: improved methodology for analyses of acid detergent fiber and acid detergent lignin.

    PubMed

    Raffrenato, E; Van Amburgh, M E

    2011-07-01

    The objective of this study was to evaluate the methodology of the acid detergent lignin (ADL) assay in an effort to evaluate particle loss, improve repeatability, and decrease variation within and among samples. The original ADL method relied on asbestos as a filtering aid, but that was removed in 1989 with the mandate from the Environmental Protection Agency to eliminate asbestos in the environment. Furthermore, recent work on fiber methodology indicated that pore size in the Gooch sintered glass crucible (40-60 μm) was too large to trap all of the small particles associated with neutral detergent fiber (NDF) and acid detergent fiber (ADF). Thus, any loss of ADF could potentially result in a loss of ADL. Sixty forages including conventional and brown midrib corn silages, alfalfa silages and hays, mature grasses, early vegetative grasses, and 9 feces samples, were analyzed sequentially for ADF and ADL as outlined in the 1973 procedure of Van Soest except for the use of the asbestos fiber. A glass microfiber filter with a 1.5-μm pore size was chosen as a filtering aid because it met the criteria required by the assay: glass, heat resistant, acid resistant, chemically inert, and hydrophobic. To compare with the current ADF and ADL assays, the assays were conducted with either no filter or the glass filter inserted into crucibles, rinsed with acetone, and then according to the 1973 procedure of Van Soest. The samples analyzed covered a range from 18.11 to 55.79% ADF and from 0.96 to 9.94% ADL on a dry matter (DM) basis. With the use of the filter, the mean ADF values increased 4.2% and mean ADL values increased 18.9%. Overall, both ADF and ADL values were greater with the use of the glass microfiber filter than without, indicating that as the type of sample analyzed changed, use of the Gooch crucible without the filtering aid results in particle loss. The adoption of the use of a small pore size (1.5 μm) glass microfiber filter to improve filtration and recovery

  2. Preparation and characterization of aligned carbon nanotubes/polylactic acid composite fibers

    NASA Astrophysics Data System (ADS)

    Kong, Yuxia; Yuan, Jie; Qiu, Jun

    2012-07-01

    Aligned functionalized multiwalled carbon nanotubes/polylactic acid (MWNTs-PCL/PLA) composite fibers were successfully prepared by electrospinning processing. The MWNTs bonded with the polycaprolactone chains exhibited excellent uniform dispersion in PLA solution by comparing with the acid-functionalized MWNTs and amino-functionalized MWNTs. Optical microscopy was used to study the aligned degree of the fibers and to investigate the influences of the electrodes distance on the alignment and structure of the fibers, and results showed that the best quality of aligned fibers with dense structure and high aligned degree were obtained at an electrodes distance of 3 cm. Moreover, the MWNTs embedded inside the MWNTs-PCL/PLA fibers displayed well orientation along the axes of the fibers, which was demonstrated by field emission scanning electron microscopy, transmission electron microscopy and Raman spectroscopy.

  3. Creation of highly aligned electrospun poly-L-lactic acid fibers for nerve regeneration applications

    NASA Astrophysics Data System (ADS)

    Wang, Han Bing; Mullins, Michael E.; Cregg, Jared M.; Hurtado, Andres; Oudega, Martin; Trombley, Matthew T.; Gilbert, Ryan J.

    2009-02-01

    Aligned, electrospun polymer fibers have shown considerable promise in directing regenerating axons in vitro and in vivo. However, in several studies, final electrospinning parameters are presented for producing aligned fiber scaffolds, and alignment where minimal fiber crossing occurs is not achieved. Highly aligned species are necessary for neural tissue engineering applications to ensure that axonal extension occurs through a regenerating environment efficiently. Axonal outgrowth on fibers that deviate from the natural axis of growth may delay axonal extension from one end of a scaffold to the other. Therefore, producing aligned fiber scaffolds with little fiber crossing is essential. In this study, the contributions of four electrospinning parameters (collection disk rotation speed, needle size, needle tip shape and syringe pump flow rate) were investigated thoroughly with the goal of finding parameters to obtain highly aligned electrospun fibers made from poly-L-lactic acid (PLLA). Using an 8 wt% PLLA solution in chloroform, a collection disk rotation speed of 1000 revolutions per minute (rpm), a 22 gauge, sharp-tip needle and a syringe pump rate of 2 ml h-1 produced highly aligned fiber (1.2-1.6 µm in diameter) scaffolds verified using a fast Fourier transform and a fiber alignment quantification technique. Additionally, the application of an insulating sheath around the needle tip improved the rate of fiber deposition (electrospinning efficiency). Optimized scaffolds were then evaluated in vitro using embryonic stage nine (E9) chick dorsal root ganglia (DRGs) and rat Schwann cells (SCs). To demonstrate the importance of creating highly aligned scaffolds to direct neurite outgrowth, scaffolds were created that contained crossing fibers. Neurites on these scaffolds were directed down the axis of the aligned fibers, but neurites also grew along the crossed fibers. At times, these crossed fibers even stopped further axonal extension. Highly aligned PLLA fibers

  4. Starch/fiber/poly(lactic acid) foam and compressed foam composites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Composites of starch, fiber, and poly(lactic acid) (PLA) were made using a foam substrate formed by dehydrating starch or starch/fiber gels. PLA was infiltrated into the dry foam to provide better moisture resistance. Foam composites were compressed into plastics using force ranging from 4-76MPa. Te...

  5. Magnetic bead-based enzyme-chromogenic substrate system for ultrasensitive colorimetric immunoassay accompanying cascade reaction for enzymatic formation of squaric acid-iron(III) chelate.

    PubMed

    Lai, Wenqiang; Tang, Dianping; Zhuang, Junyang; Chen, Guonan; Yang, Huanghao

    2014-05-20

    This work reports on a simple and feasible colorimetric immunoassay with signal amplification for sensitive determination of prostate-specific antigen (PSA, used as a model) at an ultralow concentration by using a new enzyme-chromogenic substrate system. We discovered that glucose oxidase (GOx), the enzyme broadly used in enzyme-linked immunosorbent assay (ELISA), has the ability to stimulate in situ formation of squaric acid (SQA)-iron(III) chelate. GOx-catalyzed oxidization of glucose leads to the formation of gluconic acid and hydrogen peroxide (H2O2). The latter can catalytically oxidize iron(II) to iron(III), which can rapidly (<1 min) coordinate with the SQA. Formation of the iron-squarate complex causes the color of the solution to change from bluish purple to bluish red accompanying the increasing absorbance with the increment of iron(III) concentration. On the basis of the SQA-iron(III) system, a new immunoassay protocol with GOx-labeled anti-PSA detection antibody can be designed for the detection of target PSA on capture antibody-functionalized magnetic immunosensing probe, monitored by recording the color or absorbance (λ = 468 nm) of the generated SQA-iron(III) chelate. The absorbance intensity shows to be dependent on the concentration of target PSA. A linear dependence between the absorbance and target PSA concentration is obtained under optimal conditions in the range from 1.0 pg mL(-1) to 30 ng mL(-1) with a detection limit (LOD) of 0.5 pg mL(-1) (0.5 ppt) estimated at the 3Sblank level. The sensitivity displays to be 3-5 orders of magnitude better than those of most commercialized human PSA ELISA kits. In addition, the developed colorimetric immunoassay was validated by assaying 12 human serum samples, receiving in good accordance with those obtained by the commercialized PSA ELISA kit. Importantly, the SQA-based immunosensing system can be further extended for the detection of other low-abundance proteins or biomarkers by controlling the target

  6. An Evaluation of the Chelating Agent EDDS for Marigold Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  7. The Effect of Fiber Bleaching Treatment on the Properties of Poly(lactic acid)/Oil Palm Empty Fruit Bunch Fiber Composites

    PubMed Central

    Rayung, Marwah; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Saad, Wan Zuhainis; Razak, Nur Inani Abdul; Chieng, Buong Woei

    2014-01-01

    In this work, biodegradable composites from poly(lactic acid) (PLA) and oil palm empty fruit bunch (OPEFB) fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of the composite. The study was extended by blending the composites with commercially available masterbatch colorant. PMID:25153628

  8. The effect of fiber bleaching treatment on the properties of poly(lactic acid)/oil palm empty fruit bunch fiber composites.

    PubMed

    Rayung, Marwah; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Saad, Wan Zuhainis; Razak, Nur Inani Abdul; Chieng, Buong Woei

    2014-01-01

    In this work, biodegradable composites from poly(lactic acid) (PLA) and oil palm empty fruit bunch (OPEFB) fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of the composite. The study was extended by blending the composites with commercially available masterbatch colorant. PMID:25153628

  9. Fiber

    MedlinePlus

    ... it can help with weight control. Fiber aids digestion and helps prevent constipation . It is sometimes used ... fiber attracts water and turns to gel during digestion. This slows digestion. Soluble fiber is found in ...

  10. Continuous microcellular foaming of polylactic acid/natural fiber composites

    NASA Astrophysics Data System (ADS)

    Diaz-Acosta, Carlos A.

    Poly(lactic acid) (PLA), a biodegradable thermoplastic derived from renewable resources, stands out as a substitute to petroleum-based plastics. In spite of its excellent properties, commercial applications are limited because PLA is more expensive and more brittle than traditional petroleum-based resins. PLA can be blended with cellulosic fibers to reduce material cost. However, the lowered cost comes at the expense of flexibility and impact strength, which can be enhanced through the production of microcellular structures in the composite. Microcellular foaming uses inert gases (e.g., carbon dioxide) as physical blowing agents to make cellular structures with bubble sizes of less than 10 microm and cell-population densities (number of bubbles per unit volume) greater than 109 cells/cm³. These unique characteristics result in a significant increase in toughness and elongation at break (ductility) compared with unfoamed parts because the presence of small bubbles can blunt the crack-tips increasing the energy needed to propagate the crack. Microcellular foams have been produced through a two step batch process. First, large amounts of gas are dissolved in the solid plastic under high pressure (sorption process) to form a single-phase solution. Second, a thermodynamic instability (sudden drop in solubility) triggers cell nucleation and growth as the gas diffuses out of the plastic. Batch production of microcellular PLA has addressed some of the drawbacks of PLA. Unfortunately, the batch foaming process is not likely to be implemented in the industrial production of foams because it is not cost-effective. This study investigated the continuous microcellular foaming process of PLA and PLA/wood-fiber composites. The effects of the processing temperature and material compositions on the melt viscosity, pressure drop rate, and cell-population density were examined in order to understand the nucleation mechanisms in neat and filled PLA foams. The results indicated that

  11. Intestinal fuels: glutamine, short-chain fatty acids, and dietary fiber.

    PubMed

    Evans, M A; Shronts, E P

    1992-10-01

    In recent years, considerable research has focused on the physiologic effects and clinical uses of three dietary constituents thought to be trophic to the intestinal tract in human beings: glutamine, short-chain fatty acids (SCFAs), and dietary fiber. Glutamine is an important nitrogen-carrying amino acid that may be "conditionally essential" in certain disease states to support the gut barrier and immune function and overall protein use. Colonic irrigations with SCFA preparations have demonstrated enhanced healing of bowel tissue in animals and human beings. Dietary fiber supports bacterial SCFA production, normal stool output, and the gut barrier and immune function. However, optimal fiber doses for various medical conditions are not known, and the risk for gastrointestinal (GI) obstruction, diarrhea, gas, and bloating necessitates careful selection of patients and daily monitoring of fiber tolerance. A review of the current literature indicates that widespread use of glutamine and SCFA additives parenterally and enterally awaits further evidence of safety and efficacy in human beings, establishment of appropriate doses, and advances in formulation technology. Administration of dietary fiber to enhance bowel motility should be considered in long-term tube-fed patients with intact GI function and sufficient fluid tolerance to permit hydration of fiber. Industrywide agreement on fiber analysis methods and labeling standards (eg, fiber fermentability vs solubility) would facilitate selection of enteral products. To streamline studies and optimize research efforts in future clinical trials, standard criteria for evaluating GI function, diarrheagenic factors, and intestinal outcome variables should be established. PMID:1328345

  12. STRUCTURAL IDENTIFICATION OF DEHYDROTRIFERULIC AND DEHYDROTETRAFERULIC ACIDS ISOLATED FROM INSOLUBLE MAIZE FIBER

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two new dehydrotriferulic acids and two dehydrotetraferulic acids were isolated from saponified maize bran insoluble fiber using size exclusion chromatography on BioBeads S-X3 followed by Sephadex LH-20 chromatography and semi-preparative Phenyl-Hexyl-RP-HPLC. Based on UV-spectroscopy, mass spectros...

  13. The Chelate Effect Redefined.

    ERIC Educational Resources Information Center

    da Silva, J. J. R. Frausto

    1983-01-01

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

  14. Morphology dependent field emission of acid-spun carbon nanotube fibers.

    PubMed

    Fairchild, S B; Boeckl, J; Back, T C; Ferguson, J B; Koerner, H; Murray, P T; Maruyama, B; Lange, M A; Cahay, M M; Behabtu, N; Young, C C; Pasquali, M; Lockwood, N P; Averett, K L; Gruen, G; Tsentalovich, D E

    2015-03-13

    Acid spun carbon nanotube (CNT) fibers were investigated for their field emission properties and performance was determined to be dependent on fiber morphology. The fibers were fabricated by wet-spinning of pre-made CNTs. Fiber morphology was controlled by a fabrication method and processing conditions, as well as purity, size, and type of the CNT starting material. The internal fiber structure consisted of CNT fibrils held together by van der Waals forces. Alignment and packing density of the CNTs affects the fiber's electrical and thermal conductivity. Fibers with similar diameters and differing morphology were compared, and those composed of the most densely packed and well aligned CNTs were the best field emitters as exhibited by a lower turn-on voltage and a larger field enhancement factor. Fibers with higher electrical and thermal conductivity demonstrated higher maximum current before failure and longer lifetimes. A stable emission current at 3 mA was obtained for 10 h at a field strength of <1 V μm(-1). This stable high current operation makes these CNT fibers excellent candidates for use as low voltage electron sources for vacuum electronic devices. PMID:25694166

  15. Chiral sensing of amino acids and proteins chelating with Eu(III) complexes by Raman optical activity spectroscopy.

    PubMed

    Wu, Tao; Kessler, Jiří; Bouř, Petr

    2016-09-14

    Chiroptical spectroscopy of lanthanides sensitively reflects their environment and finds various applications including probing protein structures. However, the measurement is often hampered by instrumental detection limits. In the present study circularly polarized luminescence (CPL) of a europium complex induced by amino acids is monitored by Raman optical activity (ROA) spectroscopy, which enables us to detect weak CPL bands invisible to conventional CPL spectrometers. In detail, the spectroscopic response to the protonation state could be studied, e.g. histidine at pH = 2 showed an opposite sign of the strongest CPL band in contrast to that at pH = 7. The spectra were interpreted qualitatively on the basis of the ligand-field theory and related to CPL induced by an external magnetic field. Free energy profiles obtained by molecular dynamic simulations for differently charged alanine and histidine forms are in qualitative agreement with the spectroscopic data. The sensitivity and specificity of the detection promise future applications in probing peptide and protein side chains, chemical imaging and medical diagnosis. This potential is observed for human milk and hen egg-white lysozymes; these proteins have a similar structure, but very different induced CPL spectra. PMID:27523964

  16. Novel graphene flowers modified carbon fibers for simultaneous determination of ascorbic acid, dopamine and uric acid.

    PubMed

    Du, Jiao; Yue, Ruirui; Ren, Fangfang; Yao, Zhangquan; Jiang, Fengxing; Yang, Ping; Du, Yukou

    2014-03-15

    A novel and sensitive carbon fiber electrode (CFE) modified by graphene flowers was prepared and used to simultaneously determine ascorbic acid (AA), dopamine (DA) and uric acid (UA). SEM images showed that beautiful and layer-petal graphene flowers homogeneously bloomed on the surface of CFE. Moreover, sharp and obvious oxidation peaks were found at the obtained electrode when compared with CFE and glassy carbon electrode (GCE) for the oxidation of AA, DA and UA. Also, the linear calibration plots for AA, DA and UA were observed, respectively, in the ranges of 45.4-1489.23 μM, 0.7-45.21 μM and 3.78-183.87 μM in the individual detection of each component. By simultaneously changing the concentrations of AA, DA and UA, their oxidation peaks appeared at -0.05 V, 0.16 V and 2.6 V, and the good linear responses ranges were 73.52-2305.53 μM, 1.36-125.69 μM and 3.98-371.49 μM, respectively. In addition, the obtained electrode showed satisfactory results when applied to the determination of AA, DA and UA in urine and serum samples. PMID:24140872

  17. Degradation of hyaluronic acid by photosensitized riboflavin in vitro. Modulation of the effect by transition metals, radical quenchers, and metal chelators.

    PubMed

    Frati, E; Khatib, A M; Front, P; Panasyuk, A; Aprile, F; Mitrovic, D R

    1997-01-01

    The effect of photoexcited riboflavin (RF) on the viscosity of hyaluronic acid (HA) solutions has been investigated. UV irradiation of RF causes under aerobic conditions fragmentation of HA and a decrease in the viscosity of its solutions. A decrease of HA viscosity occurs in PO(4)-buffered solutions and is accelerated by high pH, Fe2+ (but much less so by Fe3+), certain metal chelators, and horseradish peroxidase (HRP); it is partially inhibited by catalase and less so by superoxide dismutase (SOD). The reactivity of the system was completely blocked by Tris, ethanol, aspirin, d-manitol, dimethylthiourea (DMTU), dimethylsulfoxide (DMSO), and sodium azide. These results indicate that the most likely chemical species involved in the reaction is the hydroxyl radical. Singlet oxygen ((1)O(2)) generation is suggested by the ability of NaN3 and DMSO to completely inhibit the reactivity of the system. These two agents, however, may also interact with OH. radical, as well and suppress the reactivity of the system. H(2)O(2) and O(2).- seem also to be produced in significant amounts, because catalase and SOD partially block the reactivity of the system. The effect of HRP may be due to hydrogen subtraction from HA and H(2)O(2) reduction to water. Photoexcitation of RF may potentially occur in vitro and in vivo in the organs and tissues that are permeable to light, such as the eye or skin, and damage HA and other cell-matrix components causing inflammation and accelerating aging. PMID:9098086

  18. Comparative Transcriptomics Reveals Jasmonic Acid-Associated Metabolism Related to Cotton Fiber Initiation.

    PubMed

    Wang, Liman; Zhu, Youmin; Hu, Wenjing; Zhang, Xueying; Cai, Caiping; Guo, Wangzhen

    2015-01-01

    Analysis of mutants and gene expression patterns provides a powerful approach for investigating genes involved in key stages of plant fiber development. In this study, lintless-fuzzless XinWX and linted-fuzzless XinFLM with a single genetic locus difference for lint were used to identify differentially expressed genes. Scanning electron microscopy showed fiber initiation in XinFLM at 0 days post anthesis (DPA). Fiber transcriptional profiling of the lines at three initiation developmental stages (-1, 0, 1 DPA) was performed using an oligonucleotide microarray. Loop comparisons of the differentially expressed genes within and between the lines was carried out, and functional classification and enrichment analysis showed that gene expression patterns during fiber initiation were heavily associated with hormone metabolism, transcription factor regulation, lipid transport, and asparagine biosynthetic processes, as previously reported. Further, four members of the allene-oxide cyclase (AOC) family that function in jasmonate biosynthesis were parallel up-regulation in fiber initiation, especially at -1 DPA, compared to other tissues and organs in linted-fuzzed TM-1. Real time-quantitative PCR (RT-qPCR) analysis in different fiber mutant lines revealed that AOCs were up-regulated higher at -1 DPA in lintless-fuzzless than that in linted-fuzzless and linted-fuzzed materials, and transcription of the AOCs was increased under jasmonic acid (JA) treatment. Expression analysis of JA biosynthesis-associated genes between XinWX and XinFLM showed that they were up-regulated during fiber initiation in the fuzzless-lintless mutant. Taken together, jasmonic acid-associated metabolism was related to cotton fiber initiation. Parallel up-regulation of AOCs expression may be important for normal fiber initiation development, while overproduction of AOCs might disrupt normal fiber development. PMID:26079621

  19. Comparative Transcriptomics Reveals Jasmonic Acid-Associated Metabolism Related to Cotton Fiber Initiation

    PubMed Central

    Wang, Liman; Zhu, Youmin; Hu, Wenjing; Zhang, Xueying; Cai, Caiping; Guo, Wangzhen

    2015-01-01

    Analysis of mutants and gene expression patterns provides a powerful approach for investigating genes involved in key stages of plant fiber development. In this study, lintless-fuzzless XinWX and linted-fuzzless XinFLM with a single genetic locus difference for lint were used to identify differentially expressed genes. Scanning electron microscopy showed fiber initiation in XinFLM at 0 days post anthesis (DPA). Fiber transcriptional profiling of the lines at three initiation developmental stages (-1, 0, 1 DPA) was performed using an oligonucleotide microarray. Loop comparisons of the differentially expressed genes within and between the lines was carried out, and functional classification and enrichment analysis showed that gene expression patterns during fiber initiation were heavily associated with hormone metabolism, transcription factor regulation, lipid transport, and asparagine biosynthetic processes, as previously reported. Further, four members of the allene-oxide cyclase (AOC) family that function in jasmonate biosynthesis were parallel up-regulation in fiber initiation, especially at -1 DPA, compared to other tissues and organs in linted-fuzzed TM-1. Real time-quantitative PCR (RT-qPCR) analysis in different fiber mutant lines revealed that AOCs were up-regulated higher at -1 DPA in lintless-fuzzless than that in linted-fuzzless and linted-fuzzed materials, and transcription of the AOCs was increased under jasmonic acid (JA) treatment. Expression analysis of JA biosynthesis-associated genes between XinWX and XinFLM showed that they were up-regulated during fiber initiation in the fuzzless-lintless mutant. Taken together, jasmonic acid-associated metabolism was related to cotton fiber initiation. Parallel up-regulation of AOCs expression may be important for normal fiber initiation development, while overproduction of AOCs might disrupt normal fiber development. PMID:26079621

  20. Separator for starved electrolyte lead/acid battery. [perlite and glass fiber mixture

    SciTech Connect

    Bilawsky, P.D.; Cain, C.W.; Gross, S.E.; Scheffel, N.B.

    1980-11-11

    Compositions and papers made therefrom useful as separator materials in starved electrolyte lead/acid batteries are described. The compositions comprise a mixture of 30% to 80% by weight of perlite and 20% to 70% by weight of glass fibers. The glass fibers have diameters in the range of from 0.3 to 1.0 micrometers while the perlite has particle sizes in the range of from about 3 to about 100 micrometers.

  1. A novel basalt fiber-reinforced polylactic acid composite for hard tissue repair.

    PubMed

    Chen, Xi; Li, Yan; Gu, Ning

    2010-08-01

    A basalt fiber (BF) was, for the first time, introduced into a poly(l-lactic acid) (PLLA) matrix as innovative reinforcement to fabricate composite materials for hard tissue repair. Firstly, BF/PLLA composites and pure PLLA were produced by the methods of solution blending and freeze drying. The results showed that basalt fibers can be uniformly dispersed in the PLLA matrix and significantly improve the mechanical properties and hydrophilicity of the PLLA matrix. The presence of basalt fibers may retard the polymer degradation rate and neutralize the acid degradation from PLLA. Osteoblasts were cultured in vitro to evaluate the cytocompatibility of the composite. An MTT assay revealed that osteoblasts proliferated well for 7 days and there was little difference found in their viability on both PLLA and BF/PLLA films, which was consistent with the alkaline phosphatase (ALP) activity results. A fluorescent staining observation showed that osteoblasts grew well on the composites. SEM images displayed that osteoblasts tended to grow along the fiber axis. The formation of mineralized nodules was observed on the films by Alizarin red S staining. These results suggest that the presence of basalt fibers does not noticeably affect osteoblastic behavior and the designed composites are osteoblast compatible. It is concluded that basalt fibers, as reinforcing fibers, may have promising applications in hard tissue repair. PMID:20683132

  2. Chelation-assisted Pd-catalysed ortho-selective oxidative C-H/C-H cross-coupling of aromatic carboxylic acids with arenes and intramolecular Friedel-Crafts acylation: one-pot formation of fluorenones.

    PubMed

    Sun, Denan; Li, Bijin; Lan, Jingbo; Huang, Quan; You, Jingsong

    2016-03-01

    Pd-Catalysed ortho-selective oxidative C-H/C-H cross-coupling of aromatic carboxylic acids with arenes and subsequent intramolecular Friedel-Crafts acylation has been accomplished for the first time through a chelation-assisted C-H activation strategy. Starting from the readily available substrates, a variety of fluorenone derivatives are obtained in one pot. The direct use of naturally occurring carboxylic acid functionalities as directing groups avoids unnecessary steps for installation and removal of an extra directing group. PMID:26861768

  3. Morphology dependent field emission of acid-spun carbon nanotube fibers

    NASA Astrophysics Data System (ADS)

    Fairchild, S. B.; Boeckl, J.; Back, T. C.; Ferguson, J. B.; Koerner, H.; Murray, P. T.; Maruyama, B.; Lange, M. A.; Cahay, M. M.; Behabtu, N.; Young, C. C.; Pasquali, M.; Lockwood, N. P.; Averett, K. L.; Gruen, G.; Tsentalovich, D. E.

    2015-03-01

    Acid spun carbon nanotube (CNT) fibers were investigated for their field emission properties and performance was determined to be dependent on fiber morphology. The fibers were fabricated by wet-spinning of pre-made CNTs. Fiber morphology was controlled by a fabrication method and processing conditions, as well as purity, size, and type of the CNT starting material. The internal fiber structure consisted of CNT fibrils held together by van der Waals forces. Alignment and packing density of the CNTs affects the fiber’s electrical and thermal conductivity. Fibers with similar diameters and differing morphology were compared, and those composed of the most densely packed and well aligned CNTs were the best field emitters as exhibited by a lower turn-on voltage and a larger field enhancement factor. Fibers with higher electrical and thermal conductivity demonstrated higher maximum current before failure and longer lifetimes. A stable emission current at 3 mA was obtained for 10 h at a field strength of <1 V μm-1. This stable high current operation makes these CNT fibers excellent candidates for use as low voltage electron sources for vacuum electronic devices.

  4. Effect of Sterilization Methods on Electrospun Poly(lactic acid) (PLA) Fiber Alignment for Biomedical Applications.

    PubMed

    Valente, T A M; Silva, D M; Gomes, P S; Fernandes, M H; Santos, J D; Sencadas, V

    2016-02-10

    Medically approved sterility methods should be a major concern when developing a polymeric scaffold, mainly when commercialization is envisaged. In the present work, poly(lactic acid) (PLA) fiber membranes were processed by electrospinning with random and aligned fiber alignment and sterilized under UV, ethylene oxide (EO), and γ-radiation, the most common ones for clinical applications. It was observed that UV light and γ-radiation do not influence fiber morphology or alignment, while electrospun samples treated with EO lead to fiber orientation loss and morphology changing from cylindrical fibers to ribbon-like structures, accompanied to an increase of polymer crystallinity up to 28%. UV light and γ-radiation sterilization methods showed to be less harmful to polymer morphology, without significant changes in polymer thermal and mechanical properties, but a slight increase of polymer wettability was detected, especially for the samples treated with UV radiation. In vitro results indicate that both UV and γ-radiation treatments of PLA membranes allow the adhesion and proliferation of MG 63 osteoblastic cells in a close interaction with the fiber meshes and with a growth pattern highly sensitive to the underlying random or aligned fiber orientation. These results are suggestive of the potential of both γ-radiation sterilized PLA membranes for clinical applications in regenerative medicine, especially those where customized membrane morphology and fiber alignment is an important issue. PMID:26756809

  5. Novel double prodrugs of the iron chelator N,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED): Synthesis, characterization, and investigation of activation by chemical hydrolysis and oxidation.

    PubMed

    Thiele, Nikki A; Abboud, Khalil A; Sloan, Kenneth B

    2016-08-01

    The development of iron chelators suitable for the chronic treatment of diseases where iron accumulation and subsequent oxidative stress are implicated in disease pathogenesis is an active area of research. The clinical use of the strong chelator N,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED) and its alkyl ester prodrugs has been hindered by poor oral bioavailability and lack of conversion to the parent chelator, respectively. Here, we present novel double prodrugs of HBED that have the carboxylate and phenolate donors of HBED masked with carboxylate esters and boronic acids/esters, respectively. These double prodrugs were successfully synthesized as free bases (7a-f) or as dimesylate salts (8a-c,e), and were characterized by (1)H, (13)C, and (11)B NMR; MP; MS; and elemental analysis. The crystal structure of 8a was solved. Three of the double prodrugs (8a-c) were selected for further investigation into their abilities to convert to HBED by stepwise hydrolysis and H2O2 oxidation. The serial hydrolysis of the pinacol and methyl esters of N,N'-bis(2-boronic acid pinacol ester benzyl)ethylenediamine-N,N'-diacetic acid methyl ester dimesylate (8a) was verified by LC-MS. The macro half-lives for the hydrolyses of 8a-c, measured by UV, ranged from 3.8 to 26.3 h at 37 °C in pH 7.5 phosphate buffer containing 50% MeOH. 9, the product of hydrolysis of 8a-c and the intermediate in the conversion pathway, showed little-to-no affinity for iron or copper in UV competition experiments. 9 underwent a serial oxidative deboronation by H2O2 in N-methylmorpholine buffer to generate HBED (k = 10.3 M(-1) min(-1)). The requirement of this second step, oxidation, before conversion to the active chelator is complete may confer site specificity when only localized iron chelation is needed. Overall, these results provide proof of principle for the activation of the double prodrugs by chemical hydrolysis and H2O2 oxidation, and merit further investigation into the

  6. Improved fiber optic device for in situ determination of electrolyte stratification in lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Gajdátsy, G.; Benedek, F.; Kokavecz, J.; Szabó, G.; Kornis, J.

    2009-12-01

    A three-channel, highly sensitive, fiber optic device is presented to measure acid concentration in lead-acid batteries during their operation. The refractive index and thereby the concentration of sulfuric acid is measured by a bent, silica glass fiber tip, stripped off its cladding. Sensor heads of the device are small enough to be inserted at different positions in the cell of an ordinary, flooded lead-acid battery. Measuring the concentration of the electrolyte at different depths of the battery cell, acid stratification can be accurately determined. During the test of the instrument, about 0.3 Hz temporal and 0.05 wt % concentration resolutions were achieved while the temperature drift was found to be -0.25 wt %/°C.

  7. Improved fiber optic device for in situ determination of electrolyte stratification in lead-acid batteries.

    PubMed

    Gajdátsy, G; Benedek, F; Kokavecz, J; Szabó, G; Kornis, J

    2009-12-01

    A three-channel, highly sensitive, fiber optic device is presented to measure acid concentration in lead-acid batteries during their operation. The refractive index and thereby the concentration of sulfuric acid is measured by a bent, silica glass fiber tip, stripped off its cladding. Sensor heads of the device are small enough to be inserted at different positions in the cell of an ordinary, flooded lead-acid battery. Measuring the concentration of the electrolyte at different depths of the battery cell, acid stratification can be accurately determined. During the test of the instrument, about 0.3 Hz temporal and 0.05 wt % concentration resolutions were achieved while the temperature drift was found to be -0.25 wt %/degrees C. PMID:20059171

  8. Florets of sunflower (Helianthus annuus L.): potential new sources of dietary fiber and phenolic acids.

    PubMed

    Liang, Qiang; Cui, Jun; Li, Hang; Liu, Jia; Zhao, Guohua

    2013-04-10

    Ray florets (Rf) and disc florets (Df) are agricultural byproducts of sunflower seeds. Their nutrition-related compounds were determined. The dietary fiber contents in Rf and Df were 42.90 mg/100 g and 58.97 mg/100 g. In both florets, palmitic, linoleic, and linolenic acids were identified as the three most abundant fatty acids, and the saturated ones constitute approximately two-thirds (w/w) of the total fatty acids. Lysine was the limiting amino acid in both florets by World Health Organization standards. Sixteen phenolic compounds, nine free and eight bound, mainly depsides, were identified in florets by RP-HPLC-DAD/ESI-TOF-MS. The free and bound phenolic compounds in Df were higher than in Rf. 1,5-di-O-caffeoylquinic acid was the predominant free phenolic compound in both florets. The present study revealed that the florets of sunflower are rich sources of dietary fiber, Fe, and phenols. PMID:23510166

  9. Cell proliferation on PVA/sodium alginate and PVA/poly(γ-glutamic acid) electrospun fiber.

    PubMed

    Yang, Jen Ming; Yang, Jhe Hao; Tsou, Shu Chun; Ding, Chian Hua; Hsu, Chih Chin; Yang, Kai Chiang; Yang, Chun Chen; Chen, Ko Shao; Chen, Szi Wen; Wang, Jong Shyan

    2016-09-01

    To overcome the obstacles of easy dissolution of PVA nanofibers without crosslinking treatment and the poor electrospinnability of the PVA cross-linked nanofibers via electrospinning process, the PVA based electrospun hydrogel nanofibers are prepared with post-crosslinking method. To expect the electrospun hydrogel fibers might be a promising scaffold for cell culture and tissue engineering applications, the evaluation of cell proliferation on the post-crosslinking electrospun fibers is conducted in this study. At beginning, poly(vinyl alcohol) (PVA), PVA/sodium alginate (PVASA) and PVA/poly(γ-glutamic acid) (PVAPGA) electrospun fibers were prepared by electrospinning method. The electrospun PVA, PVASA and PVAPGA nanofibers were treated with post-cross-linking method with glutaraldehyde (Glu) as crosslinking agent. These electrospun fibers were characterized with thermogravimetry analysis (TGA) and their morphologies were observed with a scanning electron microscope (SEM). To support the evaluation and explanation of cell growth on the fiber, the study of 3T3 mouse fibroblast cell growth on the surface of pure PVA, SA, and PGA thin films is conducted. The proliferation of 3T3 on the electrospun fiber surface of PVA, PVASA, and PVAPGA was evaluated by seeding 3T3 fibroblast cells on these crosslinked electrospun fibers. The cell viability on electrospun fibers was conducted with water-soluble tetrazolium salt-1 assay (Cell Proliferation Reagent WST-1). The morphology of the cells on the fibers was also observed with SEM. The results of WST-1 assay revealed that 3T3 cells cultured on different electrospun fibers had similar viability, and the cell viability increased with time for all electrospun fibers. From the morphology of the cells on electrospun fibers, it is found that 3T3 cells attached on all electrospun fiber after 1day seeded. Cell-cell communication was noticed on day 3 for all electrospun fibers. Extracellular matrix (ECM) productions were found and

  10. Monohydroxamic acids and bridging dihydroxamic acids as chelators to ruthenium(III) and as nitric oxide donors: syntheses, speciation studies and nitric oxide releasing investigations.

    PubMed

    Griffith, Darren; Krot, Krystyna; Comiskey, Jedd; Nolan, Kevin B; Marmion, Celine J

    2008-01-01

    The synthesis and spectroscopic characterisation of novel mononuclear Ru(III)(edta)(hydroxamato) complexes of general formula [Ru(H2edta)(monoha)] (where monoha = 3- or 4-NH2, 2-, 3- or 4-C1 and 3-Me-phenylhydroxamato), as well as the first example of a Ru(III)-N-aryl aromatic hydroxamate, [Ru(H2edta)(N-Me-bha)].H2O (N-Me-bha = N-methylbenzohydroxamato) are reported. Three dinuclear Ru(III) complexes with bridging dihydroxamato ligands of general formula [{Ru(H2edta)}2(mu-diha)] where diha = 2,6-pyridinedihydroxamato and 1,3- or 1,4-benzodihydroxamato, the first of their kind with Ru(III), are also described. The speciation of all of these systems (with the exception of the Ru-1,4-benzodihydroxamic acid and Ru-N-methylbenzohydroxamic systems) in aqueous solution was investigated. We previously proposed that nitrosyl abstraction from hydroxamic acids by Ru(III) involves initial formation of Ru(III)-hydroxamates. Yet, until now, no data on the rate of nitric oxide (NO) release from hydroxamic acids has been published. We now describe a UV-VIS spectroscopic study, where we monitored the decrease in the ligand-to-metal charge-transfer band of a series of Ru(III)-monohydroxamates with time, with a view to gaining an insight into the NO-releasing properties of hydroxamic acids. PMID:18399240

  11. Proton dynamics in the strong chelate hydrogen bond of crystalline picolinic acid N-oxide. A new computational approach and infrared, raman and INS study.

    PubMed

    Stare, Jernej; Panek, Jarosław; Eckert, Juergen; Grdadolnik, Joze; Mavri, Janez; Hadzi, Dusan

    2008-02-21

    Infrared, Raman and INS spectra of picolinic acid N-oxide (PANO) were recorded and examined for the location of the hydronic modes, particularly O-H stretching and COH bending. PANO is representative of strong chelate hydrogen bonds (H-bonds) with its short O...O distance (2.425 A). H-bonding is possibly well-characterized by diffraction, NMR and NQR data and calculated potential energy functions. The analysis of the spectra is assisted by DFT frequency calculations both in the gas phase and in the solid state. The Car-Parrinello quantum mechanical solid-state method is also used for the proton dynamics simulation; it shows the hydron to be located about 99% of time in the energy minimum near the carboxylic oxygen; jumps to the N-O acceptor are rare. The infrared spectrum excels by an extended absorption (Zundel's continuum) interrupted by numerous Evans transmissions. The model proton potential functions on which the theories of continuum formation are based do not correspond to the experimental and computed characteristics of the hydrogen bond in PANO, therefore a novel approach has been developed; it is based on crystal dynamics driven hydronium potential fluctuation. The envelope of one hundred 0 --> 1 OH stretching transitions generated by molecular dynamics simulation exhibits a maximum at 1400 cm-1 and a minor hump at approximately 1600 cm-1. These positions square well with ones predicted for the COH bending and OH stretching frequencies derived from various one- and two-dimensional model potentials. The coincidences with experimental features have to be considered with caution because the CPMD transition envelope is based solely on the OH stretching coordinate while the observed infrared bands correspond to heavily mixed modes as was previously shown by the normal coordinate analysis of the IR spectrum of argon matrix isolated PANO, the present CPMD frequency calculation and the empirical analysis of spectra. The experimental infrared spectra show some

  12. Reusable chelating resins concentrate metal ions from highly dilute solutions

    NASA Technical Reports Server (NTRS)

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

    1966-01-01

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

  13. Actuation Behavior of Polylactic Acid Fiber Films Prepared by Electrospinning.

    PubMed

    Nobeshima, Taiki; Ishii, Yuya; Sakai, Heisuke; Uemura, Sei; Yoshida, Manabu

    2016-04-01

    A poly-DL-lactide (PLA) fiber film was prepared using the electrospinning method. This film consisted of randomly oriented PLA nanofibers. Consequently, it had sponge-like structure and was quite soft compared to PLA films prepared by spin coating. The average diameter of the fibers and the density of the film were 730 nm and 20%, respectively. By applying a voltage, the PLA film was subjected to electric-field-induced strain: expansion and compression in the thickness direction. When a voltage of -200 V was applied to the film, its thickness shrank from 13.5 µm to 10.0 µm (a 26% reduction). Electric-field-induced strain can occur via two different mechanisms: The first is electrostrictive behavior. That. is, in a highly electric field region, a change of film thickness occurs (compression only) from the electrostatic force between electrodes. The second mechanism is piezoelectric-like behavior that occurs in racemic PLA, wherein a PLA nanofiber is expanded and compressed by applying positive and negative voltage. Such piezoelectric-like behavior was not observed in spin-coated PLA films. PMID:27451629

  14. Modification of the cellulosic component of hemp fibers using sulfonic acid derivatives: Surface and thermal characterization.

    PubMed

    George, Michael; Mussone, Paolo G; Bressler, David C

    2015-12-10

    The aim of this study was to characterize the surface, morphological, and thermal properties of hemp fibers treated with two commercially available, inexpensive, and water soluble sulfonic acid derivatives. Specifically, the cellulosic component of the fibers were targeted, because cellulose is not easily removed during chemical treatment. These acids have the potential to selectively transform the surfaces of natural fibers for composite applications. The proposed method proceeds in the absence of conventional organic solvents and high reaction temperatures. Surface chemical composition and signature were measured using gravimetric analysis, X-ray photoelectron spectroscopy (XPS) and Fourier transform infra-red spectroscopy (FTIR). XPS data from the treated hemp fibers were characterized by measuring the reduction in O/C ratio and an increase in abundance of the C-C-O signature. FTIR confirmed the reaction with the emergence of peaks characteristic of disubstituted benzene and amino groups. Grafting of the sulfonic derivatives resulted in lower surface polarity. Thermogravimetric analysis revealed that treated fibers were characterized by lower percent degradation between 200 and 300 °C, and a higher initial degradation temperature. PMID:26428120

  15. Dietary fiber, organic acids and minerals in selected wild edible fruits of Mozambique.

    PubMed

    Magaia, Telma; Uamusse, Amália; Sjöholm, Ingegerd; Skog, Kerstin

    2013-12-01

    The harvesting, utilization and marketing of indigenous fruits and nuts have been central to the livelihoods of the majority of rural communities in African countries. In this study we report on the content of dietary fiber, minerals and selected organic acids in the pulps and kernels of the wild fruits most commonly consumed in southern Mozambique. The content of soluble fiber in the pulps ranged from 4.3 to 65.6 g/100 g and insoluble fiber from 2.6 to 45.8 g/100 g. In the kernels the content of soluble fiber ranged from 8.4 to 42.6 g/100 g and insoluble fiber from 14.7 to 20.9 g/100 g. Citric acid was found in all fruits up to 25.7 g/kg. The kernels of Adansonia digitata and Sclerocarya birrea were shown to be rich in calcium, iron, magnesium and zinc. The data may be useful in selecting wild fruit species appropriate for incorporation into diets. PMID:23539474

  16. Tin-117m-labeled stannic (Sn/sup 4 +/) chelate of diethylenetriamine pentaacetic acid (DTPA) for application in diagnosis and therapy

    DOEpatents

    Srivastava, S.C.; Meinken, G.E.; Richards, P.

    1983-08-25

    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.

  17. Cannabidiolic-acid synthase, the chemotype-determining enzyme in the fiber-type Cannabis sativa.

    PubMed

    Taura, Futoshi; Sirikantaramas, Supaart; Shoyama, Yoshinari; Yoshikai, Kazuyoshi; Shoyama, Yukihiro; Morimoto, Satoshi

    2007-06-26

    Cannabidiolic-acid (CBDA) synthase is the enzyme that catalyzes oxidative cyclization of cannabigerolic-acid into CBDA, the dominant cannabinoid constituent of the fiber-type Cannabis sativa. We cloned a novel cDNA encoding CBDA synthase by reverse transcription and polymerase chain reactions with degenerate and gene-specific primers. Biochemical characterization of the recombinant enzyme demonstrated that CBDA synthase is a covalently flavinylated oxidase. The structural and functional properties of CBDA synthase are quite similar to those of tetrahydrocannabinolic-acid (THCA) synthase, which is responsible for the biosynthesis of THCA, the major cannabinoid in drug-type Cannabis plants. PMID:17544411

  18. Intraluminal acid activates esophageal nodose C fibers after mast cell activation.

    PubMed

    Zhang, Shizhong; Liu, Zhenyu; Heldsinger, Andrea; Owyang, Chung; Yu, Shaoyong

    2014-02-01

    Acid reflux in the esophagus can induce esophageal painful sensations such as heartburn and noncardiac chest pain. The mechanisms underlying acid-induced esophageal nociception are not clearly understood. In our previous studies, we characterized esophageal vagal nociceptive afferents and defined their responses to noxious mechanical and chemical stimulation. In the present study, we aim to determine their responses to intraluminal acid infusion. Extracellular single-unit recordings were performed in nodose ganglion neurons with intact nerve endings in the esophagus using ex vivo esophageal-vagal preparations. Action potentials evoked by esophageal intraluminal acid perfusion were compared in naive and ovalbumin (OVA)-challenged animals, followed by measurements of transepithelial electrical resistance (TEER) and the expression of tight junction proteins (zona occludens-1 and occludin). In naive guinea pigs, intraluminal infusion with either acid (pH = 2-3) or capsaicin did not evoke an action potential discharge in esophageal nodose C fibers. In OVA-sensitized animals, following esophageal mast cell activation by in vivo OVA inhalation, intraluminal acid infusion for about 20 min started to evoke action potential discharges. This effect is further confirmed by selective mast cell activation using in vitro tissue OVA challenge in esophageal-vagal preparations. OVA inhalation leads to decreased TEER and zona occludens-1 expression, suggesting an impaired esophageal epithelial barrier function after mast cell activation. These data for the first time provide direct evidence of intraluminal acid-induced activation of esophageal nociceptive C fibers and suggest that mast cell activation may make esophageal epithelium more permeable to acid, which subsequently may increase esophageal vagal nociceptive C fiber activation. PMID:24264049

  19. Radiation grafting of acrylic and methacrylic acid to cellulose fibers to impart high water sorbency

    SciTech Connect

    Zahran, A.H.; Williams, J.L.; Stannett, V.T.

    1980-04-01

    Acrylic and methacrylic acids have been directly grafted to rayon and cotton using the preirradiation technique with /sup 60/ Co gamma rays. The rate of grafting increased with increasing temperature and monomer concentration, as did the final degree of grafting. The amount and rate of grafting also increased with the total irradiation dose but tended to level off at higher doses, in agreement with the leveling off of the radical content reported previously. Methacrylic acid grafted more and faster than acrylic acid to both rayon and cotton. Methacrylic acid grafted more with rayon than cotton, but acrylic acid gave somewhat similar yields with both fibers. The water abosrbency of the grafted fibers depended strongly on their posttreatment. Decrystallizing with 70% zinc chloride or with hot sodium hydroxidy developed supersorbency. The two treatments in succession, respectively, gave the highest values. Metacrylic acid brought about less sorbency than the corrsponding acrylic acid grafts. Useful levels of grafting and supersorbency could be readily and practically achieved by the methods described.

  20. Fabrication and Protein Conjugation of Aligned Polypyrrole-Poly(L-lactic acid) Fibers Film with the Conductivity and Stability.

    PubMed

    Qin, Jiabang; Huang, Zhongbing; Yin, Guangfu; Yang, Anneng; Han, Wei

    2016-03-01

    The conducting composite scaffold, including fiber-cores of aligned poly(L-lactic acid) (PLLA) and shell-layer of polypyrrole (PPy), was fabricated, and then bovine serum albumin (BSA) was conjugated on the PPy shell-layer. Aligned PLLA fibers (about 300 nm diameter) were obtained by electrospinning and rotating drum collection, and then coated by PPy nanoparticles (NPs, about 50 nm diameter) via chemical oxidation. The surface resistivity of PPy-PLLA fibers film were 0.971, 0.874 kΩ. cm at the fiber's vertical and parallel directions, respectively. The results of PPy-PLLA fibers film immersed in phosphate buffer saline for 8 d indicated that the fibers morphology and the film conductivity were not significantly changed, and the fluorescent images showed that FITC-labeled BSA (FITC-BSA) were successfully conjugated in the fibers film with carbodiimide chemistry, and the largest amount of FITC-BSA conjugated in the fibers film from 100 μg/mL proteins solution was 31.31 μg/cm2 due to lots of poly(glutamic acid) in surface-nanogrooves of the fibers surface. Under electrical stimulation of 100 mV, the fibers film was accompanied the release of all conjugated FITC-BSA with the detachment of some PPy NPs. These results suggested that PPy-PLLA fibers film would be potentially applied in the construction of degradable tissue engineering scaffold with protein factors, especially neurotrophic factors for nerve tissue repair. PMID:27455643

  1. Liposome encapsulation of chelating agents

    DOEpatents

    Rahman, Yueh Erh

    1976-01-13

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

  2. Fiber

    MedlinePlus

    ... broccoli, spinach, and artichokes legumes (split peas, soy, lentils, etc.) almonds Look for the fiber content of ... salsa, taco sauce, and cheese for dinner. Add lentils or whole-grain barley to your favorite soups. ...

  3. Fibers from fruit by-products enhance probiotic viability and fatty acid profile and increase CLA content in yoghurts.

    PubMed

    do Espírito Santo, Ana Paula; Cartolano, Nathalie S; Silva, Thaiane F; Soares, Fabiana A S M; Gioielli, Luiz A; Perego, Patrizia; Converti, Attilio; Oliveira, Maricê N

    2012-03-15

    This study evaluated the effect of the supplementation of total dietary fiber from apple, banana or passion fruit processing by-products on the post-acidification, total titratable acidity, bacteria counts and fatty acid profiles in skim milk yoghurts co-fermented by four different probiotics strains: Lactobacillus acidophilus L10 and Bifidobacterium animalis subsp. lactis BL04, HN019 and B94. Apple and banana fibers increased the probiotic viability during shelf-life. All the fibers were able to increase the short chain and polyunsaturated fatty acid contents of yoghurts compared to their respective controls. A synergistic effect between the type of fiber and the probiotic strain on the conjugated linoleic acid content was observed, and the amount of α-linolenic acid was increased by banana fiber. The results of this study demonstrate, for the first time, that fruit fibers can improve the fatty acid profile of probiotic yoghurts and point out the suitability of using fibers from fruit processing the by-products to develop new high value-added fermented dairy products. PMID:22264421

  4. Poly(lactic acid)/Carbon Nanotube Fibers as Novel Platforms for Glucose Biosensors.

    PubMed

    Oliveira, Juliano Elvis; Mattoso, Luiz Henrique Capparelli; Medeiros, Eliton Souto; Zucolotto, Valtencir

    2012-01-01

    The focus of this paper is the development and investigation of properties of new nanostructured architecture for biosensors applications. Highly porous nanocomposite fibers were developed for use as active materials in biosensors. The nanocomposites comprised poly(lactic acid)(PLA)/multi-walled carbon nanotube (MWCNT) fibers obtained via solution-blow spinning onto indium tin oxide (ITO) electrodes. The electrocatalytic properties of nanocomposite-modified ITO electrodes were investigated toward hydrogen peroxide (H2O2) detection. We investigated the effect of carbon nanotube concentration and the time deposition of fibers on the sensors properties, viz., sensitivity and limit of detection. Cyclic voltammetry experiments revealed that the nanocomposite-modified electrodes displayed enhanced activity in the electrochemical reduction of H2O2, which offers a number of attractive features to be explored in development of an amperometric biosensor. Glucose oxidase (GOD) was further immobilized by drop coating on an optimized ITO electrode covered by poly(lactic acid)/carbon nanotube nanofibrous mats. The optimum biosensor response was linear up to 800 mM of glucose with a sensitivity of 358 nA·mM-1 and a Michaelis-Menten constant (KM) of 4.3 mM. These results demonstrate that the solution blow spun nanocomposite fibers have great potential for application as amperometric biosensors due to their high surface to volume ratio, high porosity and permeability of the substrate. The latter features may significantly enhance the field of glucose biosensors. PMID:25585633

  5. Miniaturized ascorbic acid fuel cells with flexible electrodes made of graphene-coated carbon fiber cloth

    NASA Astrophysics Data System (ADS)

    Hoshi, Kazuki; Muramatsu, Kazuo; Sumi, Hisato; Nishioka, Yasushiro

    2016-04-01

    Ascorbic acid (AA) is a biologically friendly compound and exists in many products such as sports drinks, fruit, and even in human blood. Thus, a miniaturized and flexible ascorbic acid fuel cell (AAFC) is expected be a power source for portable or implantable electric devices. In this study, we fabricated an AAFC with anode and cathode dimensions of 3 × 10 mm2 made of a graphene-coated carbon fiber cloth (GCFC) and found that GCFC electrodes significantly improve the power generated by the AAFC. This is because the GCFC has more than two times the effective surface area of a conventional carbon fiber cloth and it can contain more enzymes. The power density of the AAFC in a phosphate buffer solution containing 100 mM AA at room temperature was 34.1 µW/cm2 at 0.46 V. Technical issues in applying the AAFC to portable devices are also discussed.

  6. Properties of electrospun pollock gelatin/poly(vinyl alcohol) and pollock gelatin/poly(lactic acid) fibers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pollock gelatin/poly(vinyl alcohol) (PVA) fibers were electrospun using deionized water as the solvent and pollock gelatin/poly(lactic acid) (PLA) fibers were electrospun using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the solvent. The chemical, thermal, and thermal stability properties were exami...

  7. Antibacterial poly(lactic acid) (PLA) films grafting electrospun PLA/Ally isothioscyanate (AITC) fibers for food packaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poly(lactic acid) (PLA) fibers of submicron sizes encapsulating allyl isothiocyanate (AITC) (PfA) were made and electrospun onto the surfaces of PLA films (PfA-g-film). SEM examination confirmed that the fibers were grafted to the PLA film after the (PfA-g-film) underwent air blowing and water washi...

  8. Thermal Stability of Chelated Indium Activable Tracers

    SciTech Connect

    Chrysikopoulos, Costas; Kruger, Paul

    1986-01-21

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

  9. Preparation and optical performance detection of acid-leaching optical fiber image bundle

    NASA Astrophysics Data System (ADS)

    Zhou, Dechun; Yu, Fengxia; Tan, Fang; Lu, Jingjuan

    2009-05-01

    This article determines three kinds of materials: core and clad glass,cladding glass,acid-leaching glass and the match ability of physical and chemical performances of these materials is described.. The quantitative relationship between concentration, temperature, acid type and resolution time are studied to determine a series of suitable technical parameters. Many effective methods are identified to improve optical properties through a lager number of detecting and analyzing the properties of fiber image bundle, which lays a good foundation for wider application.

  10. Dietary fiber and short-chain fatty acids affect cell proliferation and protein synthesis in isolated rat colonocytes.

    PubMed

    Marsman, K E; McBurney, M I

    1996-05-01

    Colonic metabolism may be affected by dietary fiber and short-chain fatty acids, the products of fiber fermentation. The aim of this study was to assess the effects of fiber supplementation (150 g/kg diet) on dynamic measurements of metabolism in isolated rat colonic epithelial cells. Additionally, we investigated the effect of in vitro short-chain fatty acid and glutamine concentrations and media osmolarity on oxygen uptake, protein synthesis, cell proliferation and anaplerotic flux. Colonocyte oxygen consumption did not differ due to fiber supplementation or the inclusion of short -chain fatty acids in incubation media. Cell proliferation (3H-thymidine uptake) was increased by fiber consumption (P acids in vitro (P fiber supplementation but was decreased when short-chain fatty acids were present in incubation media (P fiber supplementation increases in vitro colonocyte proliferation, the unchanged oxygen uptake rate indicates that there was no concurrent increase in energy expenditure. PMID:8618140

  11. An Aqueous Thermodynamic Model for the Complexation of Sodium and Strontium with Organic Chelators valid to High Ionic Strength. II. N-(2-hydroxyethyl)ethylenedinitrilotriacetic acid (HEDTA)

    SciTech Connect

    Felmy, Andrew R.; Mason, Marvin J.; Qafoku, Odeta

    2003-04-01

    This is the second paper in a two part series on the development of aqueous thermodynamic models for the complexation of Na+ and Sr2+ with organic chelators. In this paper the development of an aqueous thermodynamic model describing the effects of ionic strength, carbonate concentration, and temperature on the complexation of Sr2+ by HEDTA under basic conditions is presented. The thermodynamic model describing the Na+ interactions with the HEDTA3- chelate relies solely on the use of Pitzer ion-interaction parameters. The exclusive use of Pitzer ion-interaction parameters differs significantly from our previous model for EDTA, which required the introduction of a NaEDTA3- ion pair. Estimation of the Pitzer ion-interaction parameters for HEDTA3- and SrHEDTA- with Na+ allows the extrapolation of a standard state equilibrium constant for the SrHEDTA- species which is one order of magnitude greater than the 0.1M reference state value available in the literature. The overall model is developed from data available in the literature on apparent equilibrium constants for HEDTA protonation, the solubility of salts in concentrated HEDTA solutions, and from new data on the solubility of SrCO3(c) obtained as part of this study. The predictions of the final thermodynamic model for the Na-Sr-OH-CO3-NO3-HEDTA-H2O system are tested by application to chemical systems containing competing metal ions (i.e., Ca2+).

  12. Hollow fiber gas-liquid membrane contactors for acid gas capture: a review.

    PubMed

    Mansourizadeh, A; Ismail, A F

    2009-11-15

    Membrane contactors using microporous membranes for acid gas removal have been extensively reviewed and discussed. The microporous membrane acts as a fixed interface between the gas and the liquid phase without dispersing one phase into another that offers a flexible modular and energy efficient device. The gas absorption process can offer a high selectivity and a high driving force for transport even at low concentrations. Using hollow fiber gas-liquid membrane contactors is a promising alternative to conventional gas absorption systems for acid gas capture from gas streams. Important aspects of membrane contactor as an efficient energy devise for acid gas removal including liquid absorbents, membrane characteristics, combination of membrane and absorbent, mass transfer, membrane modules, model development, advantages and disadvantages were critically discussed. In addition, current status and future potential in research and development of gas-liquid membrane contactors for acid gas removal were also briefly discussed. PMID:19616376

  13. Topical metal chelation therapy ameliorates oxidation-induced toxicity in diabetic cataract.

    PubMed

    Zhang, Min; Shoeb, Mohammad; Liu, Ping; Xiao, Tianlin; Hogan, Dale; Wong, Ira G; Campbell, Gerald A; Ansari, Naseem H

    2011-01-01

    Oxidative stress plays a critical role in cataractogenesis, the leading cause of blindness worldwide. Since transition metals generate reactive oxygen species (ROS) formation, metal chelation therapy has been proposed for treatment of cataracts. However, the effectiveness of most chelators is limited by low tissue penetrability. This study is the first to demonstrate that the topically applied divalent metal chelator ethylenediamine tetraacetic acid (EDTA) combined with the carrier and permeability enhancer methyl sulfonyl methane (MSM) ameliorates both oxidation-induced lens opacification and the associated toxic accumulation of protein-4-hydroxynonenal (HNE) adducts. Both in vitro (rat lens culture) and in vivo (diabetic rats), EDTA-MSM (1) significantly reduced lens opacification by about 40-50%, (2) significantly diminished lens epithelial cell proliferation and fiber cell swelling in early stages of cataract formation in vivo, and (3) notably decreased the levels of protein-HNE adducts. These findings have important implications specifically for the treatment of cataract and generally for other diseases in which oxidative stress plays a key pathogenic role. PMID:21271438

  14. Incorporation of Deoxyribonucleic Acid Precursors by T4 Deoxyribonucleic Acid-Protein Complexes Retained on Glass Fiber Filters

    PubMed Central

    Miller, Robert C.; Kozinski, Andrzej W.

    1970-01-01

    Bacteriophage T4 deoxyribonucleic acid (DNA)-protein complexes were retained preferentially on glass fiber filters. DNA polymerase activity in the complex was detected through the incorporation of 3H-labeled DNA precursors. The primer-product DNA hybridized with both phage and Escherichia coli DNA. Density labeling experiments showed that about 30% of incorporated 3H-deoxyadenosine triphosphate was found in DNA which hybridized with phage DNA; this DNA was found to be covalently attached to the primer DNA. PMID:5497903

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

    NASA Astrophysics Data System (ADS)

    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.

  16. Metal Chelating Crosslinkers Form Nanogels with High Chelation Stability.

    PubMed

    Lux, Jacques; Chan, Minnie; Elst, Luce Vander; Schopf, Eric; Mahmoud, Enas; Laurent, Sophie; Almutairi, Adah

    2013-12-14

    We present a series of hydrogel nanoparticles (nanogels) incorporating either acyclic or cyclic metal chelates as crosslinkers. These crosslinkers are used to formulate polyacrylamide-based nanogels (diameter 50 to 85 nm) yielding contrast agents with enhanced relaxivities (up to 6-fold greater than Dotarem®), because this nanogel structure slows the chelator's tumbling frequency and allows fast water exchange. Importantly, these nanogels also stabilize Gd(3+) within the chelator thermodynamically and kinetically against metal displacement through transmetallation, which should reduce toxicity associated with release of free Gd(3+). This chelation stability suggests that the chelate crosslinker strategy may prove useful for other applications of metal-chelating nanoparticles in medicine, including other imaging modalities and radiotherapy. PMID:24505553

  17. Metal Chelating Crosslinkers Form Nanogels with High Chelation Stability

    PubMed Central

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

    2013-01-01

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

  18. Sequential acid-/alkali-pretreatment of empty palm fruit bunch fiber.

    PubMed

    Kim, Seonghun; Park, Jang Min; Seo, Jeong-Woo; Kim, Chul Ho

    2012-04-01

    Pretreatment processes are key technologies for generating fermentable sugars based on lignocellulosic biomass. In this study, we developed a novel method for empty palm fruit bunch fiber (EPFBF) using sequential pretreatment with dilute acid and then alkali. Dilute sulfuric acid was used in the first step, which removed 90% of the hemicellulose and 32% of the lignin, but left most of the cellulose under the optimum pretreatment condition. Sodium hydroxide was then applied in the second step, which extracted lignin effectively with a 70% delignification yield, partially disrupting the ordered fibrils of the EPFBF and thus enhancing the enzyme digestibility of the cellulose. The sequentially pretreated biomass consisted of 82% cellulose, less than 1% hemicellulose, and 30% lignin content afterward. The pretreated biomasses morphologically revealed rough, porous, and irregularly ordered surfaces for enhancing enzyme digestibility. These results indicate that the sequentially acid/alkali-pretreated EPFBF could be broadly useful as a novel biomass. PMID:22306078

  19. [Determination of isophthalic acid in polyethylene glycol terephthalate fiber by high performance liquid chromatography].

    PubMed

    Wang, R; Wang, X Y; Tang, C J; Li, L P

    2001-07-01

    The isophthalic acid(IPA) is present in polyethylene glycol terephthalate(PET) at small level, but plays an important role for the properties of polyester fiber. Thus the PET sample was hydrolysated by 100 g/L of sodium hydrate in methanol at 70 degrees C during 10 h and finally assayed by HPLC. A reversed-phase high performance liquid chromatographic method for the separation of isophthalic acid from terephthalic acid(TPA) has been developed. The operating conditions were Novapak C18 column, methanol-water(15:85, V/V)(pH3) as mobile phase with the flow rate of 1.0 mL/min and UV detection wavelength at 254 nm. PMID:12545507

  20. Relationships among dietary fiber components and the digestibility of energy, dietary fiber, and amino acids, and energy content of 9 corn co-products fed to growing pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An experiment was conducted to determine the best fitting dietary fiber (DF) assay to predict digestibility of energy, DF, and amnio acids, and energy value of 9 corn co-products: conventional corn bran (CB-NS; 37.0% total non-starch polysaccharides (NSP)), corn bran with solubles (CBS; 17.1% NSP), ...

  1. Natural chelates for radionuclide decorporation

    DOEpatents

    Premuzic, E.T.

    1983-08-25

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

  2. Electrospinning of Polyaniline/Poly(Lactic Acid) Ultrathin Fibers: Process and Statistical Modeling using a Non-Gaussian Approach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fibers of poly(lactic acid) (PLA) blended with p-toluenesulfonic acid-doped polyaniline, PAni.TSA, were obtained by lectrospinning, following a factorial design which was used mainly to study the effect of four process parameters (PLA solution concentration, PAni solution concentration, applied volt...

  3. Lipid production by Cryptococcus curvatus on hydrolysates derived from corn fiber and sweet sorghum bagasse following dilute acid pretreatment.

    PubMed

    Liang, Yanna; Jarosz, Kimberly; Wardlow, Ashley T; Zhang, Ji; Cui, Yi

    2014-08-01

    Corn fiber and sweet sorghum bagasse (SSB) are both pre-processed lignocellulosic materials that can be used to produce liquid biofuels. Pretreatment using dilute sulfuric acid at a severity factor of 1.06 and 1.02 released 83.2 and 86.5 % of theoretically available sugars out of corn fiber and SSB, respectively. The resulting hydrolysates derived from pretreatment of SSB at SF of 1.02 supported growth of Cryptococcus curvatus well. In 6 days, the dry cell density reached 10.8 g/l with a lipid content of 40 % (w/w). Hydrolysates from corn fiber, however, did not lead to any significant cell growth even with addition of nutrients. In addition to consuming glucose, xylose, and arabinose, C. curvatus also utilized formic acid, acetic acid, 4-hydroxymethylfurfural, and levulinic acid for growth. Thus, C. curvatus appeared to be an excellent yeast strain for producing lipids from hydrolysates developed from lignocellulosic feedstocks. PMID:24928546

  4. Extraction of metals using supercritical fluid and chelate forming legand

    DOEpatents

    Wai, Chien M.; Laintz, Kenneth E.

    1998-01-01

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

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

    DOEpatents

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

    1998-03-24

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

  6. Fabrication of conductive NGF-conjugated polypyrrole-poly(l-lactic acid) fibers and their effect on neurite outgrowth.

    PubMed

    Zeng, Jingwen; Huang, Zhongbing; Yin, Guangfu; Qin, Jiabang; Chen, Xianchun; Gu, Jianwen

    2013-10-01

    In order to fabricate a tissue scaffold with the neurotrophic and electrical activities, conductive nerve growth factor (NGF)-conjugated polypyrrole-poly(l-lactic acid) (PPy-PLLA) composite fibers were prepared by oxidation polymerization and EDC chemistry with poly-l-lysine. PPy nanoparticles (∼70nm diameter) accumulated on PLLA fiber surface to form a rough thick shell (∼200nm thickness). These NGF-conjugated PPy-PLLA fibers could support PC12 neurite outgrowth and extension. Especially, 40% and 74% increase in PC12 neurite outgrowth and extension, respectively, could be obtained under electrical stimulation of 100mV/cm voltages through the composite fibers. A mechanism for the interaction between neurite extension and the NGF-conjugated PPy-PLLA fibers under electro-stimulation was proposed, to explain the synergistic effect of the rough PPy shell, conjugated NGF and electricity on neurite outgrowth and elongation. PMID:23759386

  7. Inhibitory activity of chelating agent against bacteria associated with poultry processing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ethylenediaminetetraacetic acid (EDTA) and ethylenediamine-N, N’-disuccinic acid (EDDS) are chelating agents that can bind minerals that produce water hardness. By sequestering minerals in hard water, chelators reduce water hardness and increase the ability of cleansers to remove dirt and debris dur...

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

    PubMed

    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

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

    SciTech Connect

    Tandon, S.K.; Srivastava, L.

    1985-01-01

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

  10. Silybin, a new iron-chelating agent.

    PubMed

    Borsari, M; Gabbi, C; Ghelfi, F; Grandi, R; Saladini, M; Severi, S; Borella, F

    2001-06-01

    Silybin, a natural occurring flavolignan isolated from the fruits of Silibum marianum, has been reported to exert antioxidant and free radical scavenging abilities. It was suggested to act also as an iron chelator. The complexation and protonation equilibria of the ferric complex of this compound have been studied by potentiometric, spectrophotometric and electrochemical techniques. The formation of the complex silybin-Ga(III) in anhydrous DMSO-d6 has been studied by 1H NMR spectroscopy. Mass spectrometry and infrared spectroscopy on silybin-Fe(III) complex confirm all data obtained by 1H NMR spectroscopy. The experimental results show that silybin binds Fe(III) even at acidic pH. Different ternary complexes were observed at increasing methoxide ion concentration and their stability constants have been calculated. The results show the possible role of silybin in relation to the chelation therapy of chronic iron overload, as occurs in the treatment of Cooley's anemia. PMID:11410232

  11. Polycatecholamide chelating agents

    DOEpatents

    Weitl, Frederick L.; Raymond, Kenneth N.

    1984-01-01

    Novel polybenzamide compounds useful for in vitro or in vivo chelation are described. The compounds have the formula ##STR1## Polyamines are reacted with 2,3-dimethoxy benzoyl chloride unsubstituted or substituted with SO.sub.3 H, SO.sub.3 M, NO.sub.2, CO.sub.2 H or CO.sub.2 M as desired is reacted with a polyamine in an inert solvent then demethylated with BBr.sub.3 or BCl.sub.3 in an inert solvent. Where compounds symmetrically substituted on the terminal N's are desired, the polyamine is first reductively alkylated by reaction with an aldehyde or ketone and the resulting Schiff base is hydrogenated.

  12. Polycatecholamide chelating agents

    DOEpatents

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

    1984-04-10

    Novel polybenzamide compounds useful for in vitro or in vivo chelation are described. The compounds have the formula given in patent. Polyamines are reacted with 2,3-dimethoxy benzoyl chloride unsubstituted or substituted with SO[sub 3]H, SO[sub 3]M, NO[sub 2], CO[sub 2]H or CO[sub 2]M as desired is reacted with a polyamine in an inert solvent then demethylated with BBr[sub 3] or BCl[sub 3] in an inert solvent. Where compounds symmetrically substituted on the terminal N's are desired, the polyamine is first reductively alkylated by reaction with an aldehyde or ketone and the resulting Schiff base is hydrogenated. No Drawings

  13. Novel polycatecholamide chelating agents

    DOEpatents

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

    1981-08-24

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

  14. Evaluation of microwave acid digestion for determination of fiber-volume contents in carbon-epoxy composites

    SciTech Connect

    Siegel, M.C.; McLaughlin, V.N.; El-Amin, L.; Ilias, S.

    1995-06-01

    The analysis of carbon-epoxy composites for fiber-volume contents is significant in determining the quality and strength of a given composite. The method commonly being used is acid digestion in a hot water bath, which takes about 2.5 hours for digestion alone. A study has been done using a new technique, what is known as Microwave Acid Digestion (MAD) for quick determination of fiber-volume contents of carbon-epoxy composites. This technique uses a specially designed teflon bomb for digestion. The bomb allows for temperatures up to 250 C and pressures up to 1,200 psi. Under such operating conditions, the MAD technique reduces digestion time to about 70 seconds. The study demonstrated that the microwave acid digestion (MAD) is an efficient means for determination of fiber-volume contents of carbon-epoxy composites.

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

    PubMed

    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

  16. 3-hydroxy-2(1H)-pyridinone chelating agents

    DOEpatents

    Raymond, Kenneth; Xu, Jide

    1999-01-01

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

  17. An efficient chelator for complexation of thorium-227.

    PubMed

    Ramdahl, Thomas; Bonge-Hansen, Hanne T; Ryan, Olav B; Larsen, Smund; Herstad, Gunnar; Sandberg, Marcel; Bjerke, Roger M; Grant, Derek; Brevik, Ellen M; Cuthbertson, Alan S

    2016-09-01

    We present the synthesis and characterization of a highly efficient thorium chelator, derived from the octadentate hydroxypyridinone class of compounds. The chelator forms extremely stable complexes with fast formation rates in the presence of Th-227 (ambient temperature, 20min). In addition, mouse biodistribution data are provided which indicate rapid hepatobiliary excretion route of the chelator which, together with low bone uptake, supports the stability of the complex in vivo. The carboxylic acid group may be readily activated for conjugation through the ɛ-amino groups of lysine residues in biomolecules such as antibodies. This chelator is a critical component of a new class of Targeted Thorium Conjugates (TTCs) currently under development in the field of oncology. PMID:27476138

  18. 3-hydroxy-2(1H)-pyridinone chelating agents

    DOEpatents

    Raymond, K.; Xu, J.

    1999-04-06

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

  19. Description of 3,180 Courses of Chelation with Dimercaptosuccinic Acid in Children ≤5 y with Severe Lead Poisoning in Zamfara, Northern Nigeria: A Retrospective Analysis of Programme Data

    PubMed Central

    Thurtle, Natalie; Greig, Jane; Cooney, Lauren; Amitai, Yona; Ariti, Cono; Brown, Mary Jean; Kosnett, Michael J.; Moussally, Krystel; Sani-Gwarzo, Nasir; Akpan, Henry; Shanks, Leslie; Dargan, Paul I.

    2014-01-01

    Background In 2010, Médecins Sans Frontières (MSF) discovered extensive lead poisoning impacting several thousand children in rural northern Nigeria. An estimated 400 fatalities had occurred over 3 mo. The US Centers for Disease Control and Prevention (CDC) confirmed widespread contamination from lead-rich ore being processed for gold, and environmental management was begun. MSF commenced a medical management programme that included treatment with the oral chelating agent 2,3-dimercaptosuccinic acid (DMSA, succimer). Here we describe and evaluate the changes in venous blood lead level (VBLL) associated with DMSA treatment in the largest cohort of children ≤5 y of age with severe paediatric lead intoxication reported to date to our knowledge. Methods and Findings In a retrospective analysis of programme data, we describe change in VBLL after DMSA treatment courses in a cohort of 1,156 children ≤5 y of age who underwent between one and 15 courses of chelation treatment. Courses of DMSA of 19 or 28 d duration administered to children with VBLL ≥ 45 µg/dl were included. Impact of DMSA was calculated as end-course VBLL as a percentage of pre-course VBLL (ECP). Mixed model regression with nested random effects was used to evaluate the relative associations of covariates with ECP. Of 3,180 treatment courses administered, 36% and 6% of courses commenced with VBLL ≥ 80 µg/dl and ≥ 120 µg/dl, respectively. Overall mean ECP was 74.5% (95% CI 69.7%–79.7%); among 159 inpatient courses, ECP was 47.7% (95% CI 39.7%–57.3%). ECP after 19-d courses (n = 2,262) was lower in older children, first-ever courses, courses with a longer interval since a previous course, courses with more directly observed doses, and courses with higher pre-course VBLLs. Low haemoglobin was associated with higher ECP. Twenty children aged ≤5 y who commenced chelation died during the period studied, with lead poisoning a primary factor in six deaths. Monitoring of alanine

  20. Reactive airways dysfunction syndrome: occurrence after exposure to a refractory ceramic fiber-phosphoric acid binder mixture.

    PubMed

    Forrester, B G

    1997-04-01

    A previously healthy, 47-year-old millwright was exposed to high airborne levels of a refractory ceramic fiber-phosphoric acid binder mixture; after acute bronchospasm, he required hospitalization. During the next 4 years, he had recurrent acute bronchospasm requiring emergency department visits and three hospitalizations. Review of the patient's medical and occupational history and extensive clinical investigation failed to provide alternate explanations for this hyperresponsive airways disease. This is believed to be the first reported case of reactive airways dysfunction syndrome (RADS) after exposure to a refractory ceramic fiber-phosphoric acid binder mixture. Physicians should be aware of this possibility when examining patients exposed to such materials. PMID:9114842

  1. Effect of insoluble-low fermentable fiber from corn on energy, fiber, and amino acid digestibility, and on hindgut degradability of fiber and growth performance of pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extensive use of corn co-products in swine diets increases the concentration of dietary fiber, raising concerns about energy and nutrient digestibility, and ultimately on pig performance. A metabolism trial was conducted to determine the effect of increasing levels of insoluble-low fermentable fiber...

  2. Dissociation of gadolinium chelates in mice: relationship to chemical characteristics.

    PubMed

    Wedeking, P; Kumar, K; Tweedle, M F

    1992-01-01

    Tissue distributions of seven 153Gd-labeled Gd chelates were determined at five residence intervals (5 min to 14 days) following intravenous administration of 0.4 mmol/kg to mice. Relationships were sought among physicochemical parameters: thermodynamic and conditional (pH 7.4) equilibrium stability constants (log K and log K'), acid dissociation rate constants (k(obs)), lipophilicity (log P), overall charge, and size (molecular weight). Size and lipophilicity did not correlate with tissue distributions. There were possible correlations between anionic charge and rapid, early renal excretion and between stability constants and long-term residual Gd deposition. Strong correlations (r greater than 0.99) were found between acid dissociation rates and long-term deposition of Gd in the whole body, liver, and femur. This is attributed to dissociation of Gd from the chelates in vivo. Acid dissociation rates may be useful in predicting dissociation of Gd from chelates in vivo. PMID:1501535

  3. Retention of mechanical properties and cytocompatibility of a phosphate-based glass fiber/polylactic acid composite.

    PubMed

    Ahmed, I; Cronin, P S; Abou Neel, E A; Parsons, A J; Knowles, J C; Rudd, C D

    2009-04-01

    Polymers prepared from polylactic acid (PLA) have found a multitude of uses as medical devices. The main advantage of having a material that degrades is so that an implant would not necessitate a second surgical event for removal. In addition, the biodegradation may offer other advantages. In this study, fibers produced from a quaternary phosphate-based glass (PBG) in the system 50P(2)O(5)-40CaO-5Na(2)O-5Fe(2)O(3) (nontreated and heat-treated) were used to reinforce the biodegradable polymer, PLA. Fiber properties were investigated, along with the mechanical and degradation properties and cytocompatibility of the composites produced. Retention of mechanical properties overtime was also evaluated. The mean fiber strength for the phosphate glass fibers was 456 MPa with a modulus value of 51.5 GPa. Weibull analysis revealed a shape and scale parameter value of 3.37 and 508, respectively. The flexural strength of the composites matched that for cortical bone; however, the modulus values were lower than those required for cortical bone. After 6 weeks of degradation in deionized water, 50% of the strength values obtained was maintained. The composite degradation properties revealed a 14% mass loss for the nontreated and a 10% mass loss for the heat-treated fiber composites. It was also seen that by heat-treating the fibers, chemical and physical degradation occurred much slower. The pH profiles also revealed that nontreated fibers degraded quicker, thus correlating well with the degradation profiles. The in vitro cell culture experiments revealed both PLA (alone) and the heat-treated fiber composites maintained higher cell viability as compared to the nontreated fiber composites. This was attributed to the slower degradation release profiles of the heat-treated composites as compared to the nontreated fiber composites. SEM analyses revealed a porous structure after degradation, and it is clear that there are possibilities here to tailor the distribution of porosity

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

    SciTech Connect

    Not Available

    1986-09-01

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

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

    DOEpatents

    Wai, Chien M.; Smart, Neil G.; Phelps, Cindy

    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.

  6. Effect of Wheat Dietary Fiber Particle Size during Digestion In Vitro on Bile Acid, Faecal Bacteria and Short-Chain Fatty Acid Content.

    PubMed

    Dziedzic, Krzysztof; Szwengiel, Artur; Górecka, Danuta; Gujska, Elżbieta; Kaczkowska, Joanna; Drożdżyńska, Agnieszka; Walkowiak, Jarosław

    2016-06-01

    The influence of bile acid concentration on the growth of Bifidobacterium spp. and Lactobacillus spp. bacteria was demonstrated. Exposing these bacteria to the environment containing bile acid salts, and very poor in nutrients, leads to the disappearance of these microorganisms due to the toxic effect of bile acids. A multidimensional analysis of data in the form of principal component analysis indicated that lactic acid bacteria bind bile acids and show antagonistic effect on E. coli spp. bacteria. The growth in E. coli spp. population was accompanied by a decline in the population of Bifidobacterium spp. and Lactobacillus spp. with a simultaneous reduction in the concentration of bile acids. This is direct proof of acid binding ability of the tested lactic acid bacteria with respect to cholic acid, lithocholic acid and deoxycholic acid. This research demonstrated that the degree of fineness of wheat dietary fibre does not affect the sorption of bile acids and growth of some bacteria species; however, it has an impact on the profile of synthesized short-chained fatty acids. During the digestion of a very fine wheat fibre fraction (WF 90), an increase in the concentration of propionic and butyric acids, as compared with the wheat fiber fraction of larger particles - WF 500, was observed. Our study suggested that wheat fibre did not affect faecal bacteria growth, however, we observed binding of bile acids by Bifidobacterium spp. and Lactobacillus spp. PMID:26924312

  7. Metal chelate catalysts for fuel cells

    NASA Astrophysics Data System (ADS)

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

    1981-07-01

    A variety of metal chelates were synthesized and evaluated for their activity as oxygen cathode electrocatalysts in strong acidic electrolytes. It was found that Cobalt tetraazaanulene (CoTAA) and iron phthalocyanine (FePc) exhibit the best activity of all the metal chelates synthesized, but have very limited stability. The proposed solution to this problem is the synthesis of polymeric forms of these chelates, with comparable active and considerably greater stability than the monomers. Three methods for stability testing were developed: (1) Potentiostatic, with periodic measurement of the current potential characteristic; (2) potentiostatic, with continuous monitoring of the current, and; (3) galvanostatic, with continuous monitoring of potential. Each method provides a good evaluation of activity versus time, and the method to be used depends upon the objective of the test. A polymeric form of Co(TAA) was synthesized by means of an acetylene terminated monomer, which in turn was made via a Co(TAA)Br2 intermediate. The activity of the polymer was found to be comparable to that of Co(TAA) monomer, and significantly greater than that of either the stacked or sheet polymeric forms of Cobalt tetraphenylporphrine (CoTPP) previously synthesized and tested.

  8. Metal based pharmacologically active agents: Synthesis, structural characterization, molecular modeling, CT-DNA binding studies and in vitro antimicrobial screening of iron(II) bromosalicylidene amino acid chelates

    NASA Astrophysics Data System (ADS)

    Abdel-Rahman, Laila H.; El-Khatib, Rafat M.; Nassr, Lobna A. E.; Abu-Dief, Ahmed M.; Ismael, Mohamed; Seleem, Amin Abdou

    2014-01-01

    In recent years, great interest has been focused on Fe(II) Schiff base amino acid complexes as cytotoxic and antitumor drugs. Thus a series of new iron(II) complexes based on Schiff bases amino acids ligands have been designed and synthesized from condensation of 5-bromosalicylaldehyde (bs) and α-amino acids (L-alanine (ala), L-phenylalanine (phala), L-aspartic acid (aspa), L-histidine (his) and L-arginine (arg)). The structure of the investigated iron(II) complexes was elucidated using elemental analyses, infrared, ultraviolet-visible, thermogravimetric analysis, as well as conductivity and magnetic susceptibility measurements. Moreover, the stoichiometry and the stability constants of the prepared complexes have been determined spectrophotometrically. The results suggest that 5-bromosalicylaldehyde amino acid Schiff bases (bs:aa) behave as dibasic tridentate ONO ligands and coordinate to Fe(II) in octahedral geometry according to the general formula [Fe(bs:aa)2]ṡnH2O. The conductivity values between 37 and 64 ohm-1 mol-1 cm2 in ethanol imply the presence of nonelectrolyte species. The structure of the complexes was validated using quantum mechanics calculations based on accurate DFT methods. Geometry optimization of the Fe-Schiff base amino acid complexes showed that all complexes had octahedral coordination. In addition, the interaction of these complexes with (CT-DNA) was investigated at pH = 7.2, by using UV-vis absorption, viscosity and agarose gel electrophoresis measurements. Results indicated that the investigated complexes strongly bind to calf thymus DNA via intercalative mode and showed a different DNA binding according to the sequence: bsari > bshi > bsali > bsasi > bsphali. Moreover, the prepared compounds are screened for their in vitro antibacterial and antifungal activity against three types of bacteria, Escherichia coli, Pseudomonas aeruginosa and Bacillus cereus and three types of anti fungal cultures, Penicillium purpurogenium, Aspergillus

  9. Low pressure process for continuous fiber reinforced polyamic acid resin matrix composite laminates

    NASA Technical Reports Server (NTRS)

    Druyun, Darleen A. (Inventor); Hou, Tan-Hung (Inventor); Kidder, Paul W. (Inventor); Reddy, Rakasi M. (Inventor); Baucom, Robert M. (Inventor)

    1994-01-01

    A low pressure processor was developed for preparing a well-consolidated polyimide composite laminate. Prepreg plies were formed from unidirectional fibers and a polyamic acid resin solution. Molding stops were placed at the sides of a matched metal die mold. The prepreg plies were cut shorter than the length of the mold in the in-plane lateral direction and were stacked between the molding stops to a height which was higher than the molding stops. The plies were then compressed to the height of the stops and heated to allow the volatiles to escape and to start the imidization reaction. After removing the stops from the mold, the heat was increased and 0 - 500 psi was applied to complete the imidization reaction. The heat and pressure were further increased to form a consolidated polyimide composite laminate.

  10. Synthesis, structure elucidation, biological screening, molecular modeling and DNA binding of some Cu(II) chelates incorporating imines derived from amino acids

    NASA Astrophysics Data System (ADS)

    Abdel-Rahman, Laila H.; Abu-Dief, Ahmed M.; Ismael, Mohammed; Mohamed, Mounir A. A.; Hashem, Nahla Ali

    2016-01-01

    Three tridentate Schiff bases amino acids were prepared by direct condensation of 3-methoxysalicylaldehyde (MS) or 4-diethylaminosalicylaldehyde (DS) with α-amino acid ligands [L-phenylalanine (P), L-histidine (H) and DL-tryptophan (T)]. The prepared Schiff bases amino acids were investigated by melting points, elemental analysis, 1HNMR and 13CNMR, IR, UV-Vis spectra, conductivity and magnetic measurements analyses. Subsequently, copper was introduced and Cu(II) complexes formed. These complexes were analyzed by thermal and elemental analyses and further investigated by FT-IR and UV/Vis spectroscopies. The experimental results indicating that all Cu(II) complexes contain hydrated water molecules (except DSPCu complex) and don't contain coordinated water molecules. The kinetic and thermal parameters were extracted from the thermal data using Coast and Redfern method. The molar conductance values of the Schiff base amino acid ligands and their Cu(II) complexes were relatively low, showing that these compounds have non-electrolytic nature. Magnetic susceptibility measurements showed the diamagnetic nature of the Schiff base amino acid ligands and paramagnetic nature of their complexes. Additionally, a spectrophotometric method was determined to extract their stability constants. It was found that the complexes possess 1:2 (M:L) stoichiometry. The results suggested that 3-methoxysalicylaldehyde and 4-diethylaminosalicylaldehyde amino acid Schiff bases behave as monobasic tridentate ONO ligands and coordinate Cu(II) ions in octahedral geometry according to the general formula [Cu(HL)2]·nH2O. To further understanding the structural and electronic properties of these complexes, Density Functional Theory (DFT) calculations were employed and provided a satisfactory description. The optimized structures of MST Schiff base ligand and its complex were calculated using DFT. The antimicrobial activity of the Schiff base ligands and their complexes were screened against some

  11. Short-fiber protein of ad40 confers enteric tropism and protection against acidic gastrointestinal conditions.

    PubMed

    Rodríguez, Ester; Romero, Carolina; Río, Adolfo; Miralles, Marta; Raventós, Aida; Planells, Laura; Burgueño, Joan F; Hamada, Hirofumi; Perales, Jose Carlos; Bosch, Assumpció; Gassull, Miguel Angel; Fernández, Ester; Chillon, Miguel

    2013-08-01

    The lack of vectors for selective gene delivery to the intestine has hampered the development of gene therapy strategies for intestinal diseases. We hypothesized that chimeric adenoviruses of Ad5 (species C) displaying proteins of the naturally enteric Ad40 (species F) might hold the intestinal tropism of the species F and thus be useful for gene delivery to the intestine. As oral-fecal dissemination of enteric adenovirus must withstand the conditions encountered in the gastrointestinal tract, we studied the resistance of chimeric Ad5 carrying the short-fiber protein of Ad40 to acid milieu and proteases and found that the Ad40 short fiber confers resistance to inactivation in acidic conditions and that AdF/40S was further activated upon exposure to low pH. In contrast, the chimeric AdF/40S exhibited only a slightly higher protease resistance compared with Ad5 to proteases present in simulated gastric juice. Then, the biodistribution of different chimeric adenoviruses by oral, rectal, and intravenous routes was tested. Expression of reporter β-galactosidase was measured in extracts of 15 different organs 3 days after administration. Our results indicate that among the chimeric viruses, only intrarectally given AdF/40S infected the colon (preferentially enteroendocrine cells and macrophages) and to a lesser extent, the small intestine, whereas Ad5 infectivity was very poor in all tissues. Additional in vitro experiments showed improved infectivity of AdF/40S also in different human epithelial cell lines. Therefore, our results point at the chimeric adenovirus AdF/40S as an interesting vector for selective gene delivery to treat intestinal diseases. PMID:23746215

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

    SciTech Connect

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

    2007-10-25

    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.

  13. Hydroxypyridonate chelating agents and synthesis thereof

    DOEpatents

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

    1985-11-12

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

  14. Electrospining of polyaniline/poly(lactic acid) ultrathin fibers: process and statistical modeling using a non-gaussian approach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cover: The electrospinning technique was employed to obtain conducting nanofibers based on polyaniline and poly(lactic acid). A statistical model was employed to describe how the process factors (solution concentration, applied voltage, and flow rate) govern the fiber dimensions. Nanofibers down to ...

  15. Oxidation of calprotectin by hypochlorous acid prevents chelation of essential metal ions and allows bacterial growth: Relevance to infections in cystic fibrosis.

    PubMed

    Magon, Nicholas J; Turner, Rufus; Gearry, Richard B; Hampton, Mark B; Sly, Peter D; Kettle, Anthony J

    2015-09-01

    Calprotectin provides nutritional immunity by sequestering manganese and zinc ions. It is abundant in the lungs of patients with cystic fibrosis but fails to prevent their recurrent infections. Calprotectin is a major protein of neutrophils and composed of two monomers, S100A8 and S100A9. We show that the ability of calprotectin to limit growth of Staphylococcus aureus and Pseudomonas aeruginosa is exquisitely sensitive to oxidation by hypochlorous acid. The N-terminal cysteine residue on S100A9 was highly susceptible to oxidation which resulted in cross-linking of the protein monomers. The N-terminal methionine of S100A8 was also readily oxidized by hypochlorous acid, forming both the methionine sulfoxide and the unique product dehydromethionine. Isolated human neutrophils formed these modifications on calprotectin when their myeloperoxidase generated hypochlorous acid. Up to 90% of the N-terminal amine on S100A8 in bronchoalveolar lavage fluid from young children with cystic fibrosis was oxidized. Oxidized calprotectin was higher in children with cystic fibrosis compared to disease controls, and further elevated in those patients with infections. Our data suggest that oxidative stress associated with inflammation in cystic fibrosis will stop metal sequestration by calprotectin. Consequently, strategies aimed at blocking extracellular myeloperoxidase activity should enable calprotectin to provide nutritional immunity within the airways. PMID:26006104

  16. Flame Atomic Absorption Spectrometric Determination of Trace Metal Ions in Environmental and Biological Samples After Preconcentration on a Newly Developed Amberlite XAD-16 Chelating Resin Containing p-Aminobenzene Sulfonic Acid.

    PubMed

    Islam, Aminul; Ahmad, Akil; Laskar, Mohammad Asaduddin

    2015-01-01

    Amberlite® XAD-16 was functionalized with p-aminobenzene sulfonic acid via an azo spacer in order to prepare a new chelating resin, which was then characterized by water regain value, hydrogen ion capacity, elemental analyses, and IR spectral and thermal studies. The maximum uptake of Cu(II), Ni(II), Zn(II), Co(II), Cr(III), Fe(III), and Pb(II) ions was observed in the pH range 4.0-6.0 with the corresponding half-loading times of 6.5, 7.0, 8.0, 9.0, 11.0, 8.5, and 16.5 min. The sorption data followed Langmuir isotherms and a pseudo-second-order model. Thermodynamic quantities, ΔH and ΔS, based on the variation of the distribution coefficient with temperature were also evaluated. High preconcentration factors of 60-100 up to a low preconcentration limit of 4.0-6.6 μg/L have been achieved for the metal ions. The validity of the method was checked by analyzing standard reference materials and recoveries of trace metals after spiking. The analytical applications of the method were explored by analyzing natural water, mango pulp, mint leaves, and fish. PMID:25857893

  17. Quercetin glycosides and chlorogenic acid in highbush blueberry leaf decoction prevent cataractogenesis in vivo and in vitro: Investigation of the effect on calpains, antioxidant and metal chelating properties.

    PubMed

    Ferlemi, Anastasia-Varvara; Makri, Olga E; Mermigki, Penelope G; Lamari, Fotini N; Georgakopoulos, Constantinos D

    2016-04-01

    The present study investigates whether highbush blueberry leaf polyphenols prevent cataractogenesis and the underlying mechanisms. Chlorogenic acid, quercetin, rutin, isoquercetin and hyperoside were quantified in Vaccinium corymbosum leaf decoction (BBL) using HPLC-DAD. Wistar rats were injected subcutaneously with 20 μmol selenite (Na2SeO3)/kg body weight on postnatal (PN) day 10 (Se, n = 8-10/group) only or also intraperitoneally with 100 mg dry BBL/kg body weight on PN days 11 and 12 (SeBBL group, n = 10). Control group received only normal saline (C). Cataract evaluation revealed that BBL significantly prevented lens opacification. It, also, protected lens from selenite oxidative attack and prevented calpain activation, as well as protein loss and aggregation. In vitro studies showed that quercetin attenuated porcine lens turbidity caused by [Formula: see text] or Ca(2+) and interacted efficiently with those ions according to UV-Vis titration experiments. Finally, rutin, isoquercetin and hyperoside moderately inhibited pure human μ-calpain. Conclusively, blueberry leaf extract, a rich source of bioactive polyphenols, prevents cataractogenesis by their strong antioxidant, chelating properties and through direct/indirect inhibition of lens calpains. PMID:26808488

  18. Hyaluronic acid/poly(lactic-co-glycolic acid) core/shell fiber meshes loaded with epigallocatechin-3-O-gallate as skin tissue engineering scaffolds.

    PubMed

    Lee, Eun Ji; Lee, Jong Ho; Jin, Linhua; Jin, Oh Seong; Shin, Yong Cheol; Sang, Jin Oh; Lee, Jaebeom; Hyon, Suong-Hyu; Han, Dong-Wook

    2014-11-01

    In this study, hyaluronic acid (HA)/poly(lactic-co-glycolic acid, PLGA) core/shell fiber meshes loaded with epigallocatechin-3-O-gallate (EGCG) (HA/PLGA-E) for application to tissue engineering scaffolds for skin regeneration were prepared via coaxial electrospinning. Physicochemical properties of HA/PLGA-E core/shell fiber meshes were characterized by SEM, Raman spectroscopy, contact angle, EGCG release profiling and in vitro degradation. Biomechanical properties of HA/PLGA-E meshes were also investigated by a tensile strength test. SEM images showed that HA/PLGA-E fiber meshes had a three-dimensional interconnected pore structure with an average fiber diameter of about 1270 nm. Raman spectra revealed that EGCG was uniformly dispersed in the PLGA shell of meshes. HA/PLGA-E meshes showed sustained EGCG release patterns by controlled diffusion and PLGA degradation over 4 weeks. EGCG loading did not adversely affect the tensile strength and elastic modulus of HA/PLGA meshes, while increased their hydrophilicity and surface energy. Attachment of human dermal fibroblasts on HA/PLGA-E meshes was appreciably increased and their proliferation was steadily retained during the culture period. These results suggest that HA/PLGA-E core/shell fiber meshes can be potentially used as scaffolds supporting skin regeneration. PMID:25958546

  19. Modifications of boronic ester pro-chelators triggered by hydrogen peroxide tune reactivity to inhibit metal-promoted oxidative stress.

    PubMed

    Charkoudian, Louise K; Pham, David M; Kwon, Ashley M; Vangeloff, Abbey D; Franz, Katherine J

    2007-11-21

    Several new analogs of salicylaldehyde isonicotinoyl hydrazone (SIH) and salicylaldehyde benzoyl hydrazone (SBH) that contain an aryl boronic ester (BSIH, BSBH) or acid (BASIH) in place of an aryl hydroxide have been synthesized and characterized as masked metal ion chelators. These pro-chelators show negligible interaction with iron(III), although the boronic acid versions exhibit some interaction with copper(II), zinc(II) and nickel(II). Hydrogen peroxide oxidizes the aryl boronate to phenol, thus converting the pro-chelators to tridentate ligands with high affinity metal binding properties. An X-ray crystal structure of a bis-ligated iron(III) complex, [Fe(SBH(m-OMe)(3))(2)]NO(3), confirms the meridonal binding mode of these ligands. Modifications of the aroyl ring of the chelators tune their iron affinity, whereas modifications on the boron-containing ring of the pro-chelators attenuate their reaction rates with hydrogen peroxide. Thus, the methoxy derivative pro-chelator (p-OMe)BASIH reacts with hydrogen peroxide nearly 5 times faster than the chloro derivative (m-Cl)BASIH. Both the rate of pro-chelator to chelator conversion as well as the metal binding affinity of the chelator influence the overall ability of these molecules to inhibit hydroxyl radical formation catalyzed by iron or copper in the presence of hydrogen peroxide and ascorbic acid. This pro-chelator strategy has the potential to improve the efficacy of medicinal chelators for inhibiting metal-promoted oxidative stress. PMID:17992288

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

    SciTech Connect

    Wu, F.C.; Tseng, R.L.; Juang, R.S.

    1999-01-01

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

  1. Quantitative analysis of mechanical and electrostatic properties of poly(lactic) acid fibers and poly(lactic) acid-carbon nanotube composites using atomic force microscopy.

    PubMed

    Iqbal, Qais; Bernstein, Peter; Zhu, Yazhe; Rahamim, Joseph; Cebe, Peggy; Staii, Cristian

    2015-03-13

    We use atomic force microscopy (AFM) to perform a systematic quantitative characterization of the elastic modulus and dielectric constant of poly(L-lactic acid) electrospun nanofibers (PLLA), as well as composites of PLLA fibers with 1.0 wt% embedded multiwall carbon nanotubes (MWCNTs-PLLA). The elastic moduli are measured in the fiber skin region via AFM nanoindentation, and the dielectric constants are determined by measuring the phase shifts obtained via electrostatic force microscopy (EFM). We find that the average value for the elastic modulus for PLLA fibers is (9.8 ± 0.9) GPa, which is a factor of 2 larger than the measured average elastic modulus for MWCNT-PLLA composites (4.1 ± 0.7) GPa. We also use EFM to measure dielectric constants for both types of fibers. These measurements show that the dielectric constants of the MWCNT-PLLA fibers are significantly larger than the corresponding values obtained for PLLA fiber. This result is consistent with the higher polarizability of the MWCNT-PLLA composites. The measurement methods presented are general, and can be applied to determine the mechanical and electrical properties of other polymers and polymer nanocomposites. PMID:25683087

  2. Preparation and characterization of chitosan-grafted-poly(2-amino-4,5-pentamethylene-thiophene-3-carboxylic acid N'-acryloyl-hydrazide) chelating resin for removal of Cu(II), Co(II) and Ni(II) metal ions from aqueous solutions.

    PubMed

    Bekheit, M M; Nawar, N; Addison, A W; Abdel-Latif, D A; Monier, M

    2011-05-01

    The graft copolymerization of ethylacrylate (EA) onto chitosan initiated by potassium persulphate and Mohr's salt combined redox initiator system in limited aqueous medium was carried out in heterogeneous media. Moreover, modification of the grafted chitosan was carried out by reaction of the ester group (-COOEt) with 2-amino-4,5-pentamethylene-thiophene-3-carboxylic acid hydrazide which eventually produce chitosan-grafted-poly(2-amino-4,5-pentamethylene-thiophene-3-carboxylic acid N'-acryloyl-hydrazide) (chitosan-g-ATAH) chelating resin. The application of the modified resin for metal ion uptake was studied using Cu(2+), Co(2+) and Ni(2+) ions. The modified chelating resins were characterized using FTIR spectroscopy, SEM and X-ray diffraction. PMID:21277322

  3. Salicylic acid-derived poly(anhydride-ester) electrospun fibers designed for regenerating the peripheral nervous system

    PubMed Central

    Griffin, Jeremy; Delgado-Rivera, Roberto; Meiners, Sally; Uhrich, Kathryn E.

    2011-01-01

    Continuous biomaterial advances and the regenerating potential of the adult human peripheral nervous system offer great promise for restoring full function to innervated tissue following traumatic injury via synthetic nerve guidance conduits. To most effectively facilitate nerve regeneration, a tissue engineering scaffold within a conduit must be similar to the linear microenvironment of the healthy nerve. To mimic the native nerve structure, aligned poly(lactic-co-glycolic acid)/bioactive polyanhydride fibrous substrates were fabricated through optimized electrospinning parameters with diameters of 600 ± 200 nm. Scanning electron microscopy images show fibers with a high degree of alignment. Schwann cells and dissociated rat dorsal root ganglia demonstrated elongated and healthy proliferation in a direction parallel to orientated electrospun fibers with significantly longer Schwann cell process length and neurite outgrowth when compared to randomly orientated fibers. Results suggest that an aligned polyanhydride fiber mat holds tremendous promise as a supplement scaffold for the interior of a degradable polymer nerve guidance conduit. Bioactive salicylic acid based polyanhydride fibers are not limited to nerve regeneration and offer exciting promise for a wide variety of biomedical applications. PMID:21442724

  4. EDTA Chelation Therapy to Reduce Cardiovascular Events in Persons with Diabetes.

    PubMed

    Ouyang, Pamela; Gottlieb, Sheldon H; Culotta, Valerie L; Navas-Acien, Ana

    2015-11-01

    The Trial to Assess Chelation Therapy (TACT) was a randomized double-blind placebo-controlled trial enrolling patients age ≥50 years with prior myocardial infarction. TACT used a 2 × 2 factorial design to study ethylene diamine tetraacetic acid (EDTA) chelation and high-dose vitamin supplementation. Chelation provided a modest but significant reduction in cardiovascular endpoints. The benefit was stronger and significant among participants with diabetes but absent in those without diabetes. Mechanisms by which chelation might reduce cardiovascular risk in persons with diabetes include the effects of EDTA chelation on transition and toxic metals. Transition metals, particularly copper and iron, play important roles in oxidative stress pathways. Toxic metals, in particular cadmium and lead, are toxic for the cardiovascular system. This review discusses the epidemiologic evidence and animal and human studies supporting the role of these metals in the development of diabetes and ischemic heart disease and potential ways by which EDTA chelation could confer cardiovascular benefit. PMID:26364188

  5. Optimization studies on acid hydrolysis of oil palm empty fruit bunch fiber for production of xylose.

    PubMed

    Rahman, S H A; Choudhury, J P; Ahmad, A L; Kamaruddin, A H

    2007-02-01

    Oil palm empty fruit bunch fiber is a lignocellulosic waste from palm oil mills. It is a potential source of xylose which can be used as a raw material for production of xylitol, a high value product. The increasing interest on use of lignocellulosic waste for bioconversion to fuels and chemicals is justifiable as these materials are low cost, renewable and widespread sources of sugars. The objective of the present study was to determine the effect of H(2)SO(4) concentration, reaction temperature and reaction time for production of xylose. Batch reactions were carried out under various reaction temperature, reaction time and acid concentrations and Response Surface Methodology (RSM) was followed to optimize the hydrolysis process in order to obtain high xylose yield. The optimum reaction temperature, reaction time and acid concentration found were 119 degrees C, 60 min and 2%, respectively. Under these conditions xylose yield and selectivity were found to be 91.27% and 17.97 g/g, respectively. PMID:16647852

  6. Amino acid conjugated self assembling molecules for enhancing surface wettability of fiber laser treated titanium surfaces

    NASA Astrophysics Data System (ADS)

    Akkan, Cagri K.; Hür, Deniz; Uzun, Lokman; Garipcan, Bora

    2016-03-01

    Surface wetting properties of implants are one of the most critical parameter, which determine the interaction of proteins and cells with the implant surface. In this regards, acid etching and sand blasting are the mostly used methods at surface modification of Titanium (Ti) for enhanced surface wettability. Besides, these kinds of modifications may cause a conflict whether the surface wettability is influenced by the process related surface contaminations or by the surface roughness. In contrast, lasers might be an option for the alteration of surface wetting properties via supporting micro and/or nano surface topographies while preventing surface chemical contaminations. In this work, we focused on two steps of surface processing approaches of Ti surface: physical and chemical modifications. Herein, we hierarchically structured Ti surfaces by using microsecond modulated pulsed fiber laser. Subsequently, laser structured and non-structured Ti surfaces were further modified with novel histidine and leucine Amino Acid conjugated Self-Assembled Molecules (His1-SAMs2 and Leu3-SAMs) to alter the surface wettability by introducing biologically hydrophilic and hydrophobic groups. Modification of Ti surfaces with His-SAMs and Leu-SAMs ended up with stable wetting properties when compared to non-modified surfaces after 7 days which may enhances the cell-surface interaction.

  7. Detection of amino acid neurotransmitters by surface enhanced Raman scattering and hollow core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Tiwari, Vidhu S.; Khetani, Altaf; Monfared, Ali Momenpour T.; Smith, Brett; Anis, Hanan; Trudeau, Vance L.

    2012-03-01

    The present work explores the feasibility of using surface enhanced Raman scattering (SERS) for detecting the neurotransmitters such as glutamate (GLU) and gamma-amino butyric acid (GABA). These amino acid neurotransmitters that respectively mediate fast excitatory and inhibitory neurotransmission in the brain, are important for neuroendocrine control, and upsets in their synthesis are also linked to epilepsy. Our SERS-based detection scheme enabled the detection of low amounts of GLU (10-7 M) and GABA (10-4 M). It may complement existing techniques for characterizing such kinds of neurotransmitters that include high-performance liquid chromatography (HPLC) or mass spectrography (MS). This is mainly because SERS has other advantages such as ease of sample preparation, molecular specificity and sensitivity, thus making it potentially applicable to characterization of experimental brain extracts or clinical diagnostic samples of cerebrospinal fluid and saliva. Using hollow core photonic crystal fiber (HC-PCF) further enhanced the Raman signal relative to that in a standard cuvette providing sensitive detection of GLU and GABA in micro-litre volume of aqueous solutions.

  8. Application of Lactobacillus immobilized by Activated Carbon Fiber in Fermentation of Lactic Acid in Starch Wastewater

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Wang, Peng; Chi, Guoda; Huang, Chenyong

    2010-11-01

    Activated carbon fibers (ACF) as the carrier of Lactobacillus was introduced into fermenting system, and a method of modifying the surface of ACF by HNO3-Fe (III) was established. Factors that affect ACF carrier's effect on immobilization of Lactobacillus were studied. HCl, H2SO4, HNO3 and FeCl3 solutions were respectively used to modify the surface properties of ACF. The amount of Fe (III) carried on ACF surface was 0.1563 mol/kg after ACF surface was modified by HNO3 for 5 h and then by 0.1 mol/L FeCl3 for 4 h, when the thickness of Lactobacillus on a single silk of carrier reached 40 μm. When ACF modified by HNO3-Fe (III) was applied in the fermentation of lactic acid in starch industry wastewater, the fermentation period reduced by 8 h and the output of L-lactic acid was 65.5 g/L, which was 3.3% more than that fermented without the carrier.

  9. In vitro binding capacities of three dietary fibers and their mixture for four toxic elements, cholesterol, and bile acid.

    PubMed

    Zhang, Ning; Huang, Caihuan; Ou, Shiyi

    2011-02-15

    Water-soluble dietary fibers from apple peels and water-insoluble dietary fibers from wheat bran and soybean-seed hull were used to evaluate their binding capacities for four toxic elements (Pb, Hg, Cd, and As), lard, cholesterol, and bile acids. The water-soluble dietary fibers showed a higher binding capacity for three toxic cations, cholesterol, and sodium cholate; and a lower binding capacity for lard, compared to the water-insoluble ones. A mixture of the dietary fibers from all samples - apple peels, wheat bran, and soybean-seed hull - in the ratio 2:4:4 (w/w) significantly increased the binding capacity of water-insoluble dietary fibers for the three toxic cations, cholesterol, and sodium cholate; moreover, the mixture could lower the concentrations of Pb(2+) and Cd(+) in the tested solutions to levels lower than those occurring in rice and vegetables grown in polluted soils. However, all the tested fibers showed a low binding capacity for the toxic anion, AsO(3)(3-). PMID:21095057

  10. Effect of Cattle Breed on Meat Quality, Muscle Fiber Characteristics, Lipid Oxidation and Fatty Acids in China

    PubMed Central

    Xie, Xiangxue; Meng, Qingxiang; Cui, Zhenliang; Ren, Liping

    2012-01-01

    The objective was to compare meat quality, muscle fiber characteristics, lipid oxidation and fatty acids of Limousin (LIM), Simmtental (SIM), Luxi (LX), Qinchuan (QC) and Jinnan (JN) offered the same diet in China. After finishing, eight bulls from each breed were randomly selected for slaughter at 18.5 months old. Longissimus dorsi (ld) muscle was taken from the carcass for meat quality evaluations. Breed had little effect on most of meat and fat color parameters except for Hue and b* in which QC had lower values. LIM showed higher pH (24 h) and better water holding capacity than other breeds. LIM showed the lowest dry matter content but the highest crude protein. LX and LIM had higher percentage and density of red muscle fiber than other breeds. Lipid oxidations were significantly lower in LIM than in QC, with the LX, SIM and JN having the intermediate values. Compared to other four breeds, QC provided the highest values of polyunsaturated fatty acids (PUFA), n-6 fatty acids and n-3 fatty acids. In conclusion, LIM scored better on most of meat quality characteristics; however, local breeds such as LX and QC also had better muscle fiber characteristics and better fatty acids composition. PMID:25049633

  11. Application of vibrational spectroscopy in the in vitro studies of carbon fiber-polylactic acid composite degradation.

    NASA Astrophysics Data System (ADS)

    Blazewicz, Marta; Gajewska, Maria Chomyszyn; Paluszkiewicz, Czeslawa

    1999-05-01

    Vibrational spectroscopy was used for assessment of new material for stomatology, for guided tissue regeneration (GTR) techniqe.Implants applied in the healing of periodontal defects using GTR technique have to meet stringent requirements concerning their chemical as well physical properties.At present the implants prepared from two layers membranes differing in porosity in their outer and inner layers are studied clinically. Composite plates prepared by us consist of three layers: polylactic acid film, carbon fibres coated with polylactic acid and carbon fabric.Vibrational spectroscopic studies of the material; polylactic acid- carbon fiber have made it possible to analyse chemical reactions occurring between the polymer and carbon surface. Analysis of the IR spectra of samples treated in Ringer solution allowed to describe the phenomena resulting from the composite degradation. It was shown that material biostability is related to the presence of carbon fibers.

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

    USGS Publications Warehouse

    Lovley, D.R.; Woodward, J.C.; Chapelle, F.H.

    1996-01-01

    Fe(III) chelated to such compounds as EDTA, N-methyliminodiacetie acid, ethanol diglycine, humic acids, and phosphates stimulated benzene oxidation coupled to Fe(III) reduction in anaerobic sediments from a petroleum- contaminated aquifer as effectively as or more effectively than nitrilotriacetic acid did in a previously demonstrated stimulation experiment. These results indicate that many forms of chelated Fe(III) might be applicable to aquifer remediation.

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

    SciTech Connect

    Serne, R.J.; Felmy, A.R.; Cantrell, K.J.; Krupka, K.M.; Campbell, J.A.; Bolton, H. Jr.; Fredrickson, J.K.

    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.

  14. An Aqueous Thermodynamic Model for the Complexation of Sodium and Strontium with Organic Chelates valid to High Ionic Strength. I. Ethylenedinitrilotetraacetic acid (EDTA)

    SciTech Connect

    Felmy, Andrew R.; Mason, Marvin J.

    2003-04-01

    An aqueous thermodynamic model is developed, which accurately describes the effects of Na+ complexation, ionic strength, carbonate concentration, and temperature on the complexation of Sr2+ by ethylenedinitrilotetraacetic acid (EDTA) under basic conditions. The model is developed from the analysis of literature data on apparent equilibrium constants, enthalpies, and heat capacities; as well as on an extensive set of solubility data on SrCO3(c) in the presence of EDTA obtained as part of this study. The solubility data for SrCO3(c) were obtained in solutions ranging in Na2CO3 concentration from 0.01m to 1.8m, in NaNO3 concentration from 0 to 5m, and at temperatures extending to 75?C. The final aqueous thermodynamic model is based upon the equations of Pitzer and requires the inclusion of a NaEDTA3- species. An accurate model for the ionic strength dependence of the ion-interaction coefficients for the SrEDTA2- and NaEDTA3- aqueous species allows the extrapolation of standard state equilibrium constants for these species which are significantly different from the 0.1m reference state values available in the literature. The final model is tested by application to chemical systems containing competing metal ions (i.e., Ca2+) to further verify the proposed model and indicate the applicability of the model parameters to chemical systems containing other divalent metal-EDTA complexes.

  15. The effects of nitric acid and silane surface treatments on carbon fibers and carbon/vinyl ester composites before and after seawater exposure

    NASA Astrophysics Data System (ADS)

    Langston, Tye A.

    This research focuses on carbon fiber treatment by nitric acid and 3-(trimethoxysilyl)propyl methacrylate silane, and how this affects carbon/vinyl ester composites. These composites offer great benefits, but it is difficult to bond the fiber and matrix together, and without a strong interfacial bond, composites fall short of their potential. Silanes work well with glass fiber, but do not bond directly to carbon fiber because its surface is not reactive to liquid silanes. Oxidizing surface treatments are often prescribed for improved wetting and bonding to carbon, but good results are not always achieved. Furthermore, there is the unanswered question of environmental durability. This research aimed to form a better understanding of oxidizing carbon fiber treatments, determine if silanes can be bonded to oxidized surfaces, and how these treatments affect composite strength and durability before and after seawater exposure. Nitric acid treatments on carbon fibers were found to improve their tensile strength to a constant level by smoothing surface defects and chemically modifying their surfaces by increasing carbonyl and carboxylic acid concentrations. Increasing these surface group concentrations raises fiber polar energy and causes them to cohere. This impedes wetting, resulting in poor quality, high void content composites, even though there appeared to be improved adhesion between the fibers and matrix. Silane was found to bond to the oxidized carbon fiber surfaces, as evidenced by changes in both fiber and composite properties. The fibers exhibited low polarity and cohesion, while the composites displayed excellent resin wetting, low void content, and low seawater weight gain and swelling. On the contrary, the oxidized fibers that were not treated with silane exhibited high polarity and fiber cohesion. Their composites displayed poor wetting, high void content, high seawater weight gain, and low swelling. Both fiber treatment types resulted in great improvements

  16. Influence of the chelator structures on the stability of Re and Tc tricarbonyl complexes with iminodiacetic acid tridentate ligands: a computational study.

    PubMed

    Hernández-Valdés, Daniel; Rodríguez-Riera, Zalua; Díaz-García, Alicia; Benoist, Eric; Jáuregui-Haza, Ulises

    2016-08-01

    The development of novel radiopharmaceuticals for nuclear medicine based on M(CO)3 (M = Tc, Re) complexes has attracted great attention. The versatility of this core and the easy production of the fac-[M(CO)3(H2O)3](+) precursor could explain this interest. The main characteristics of these tricarbonyl complexes are the high substitution stability of the three CO ligands and the corresponding lability of the coordinated water molecules, yielding, via easy exchange of a variety of bi- and tridentate ligands, complexes xof very high kinetic stability. Here, a computational study of different tricarbonyl complexes of Re(I) and Tc(I) was performed using density functional theory. The solvent effect was simulated using the polarizable continuum model. These structures were used as a starting point to investigate the relative stabilities of tricarbonyl complexes with various tridentate ligands. These complexes included an iminodiacetic acid unit for tridentate coordination to the fac-[M(CO)3](+) moiety (M = Re, Tc), an aromatic ring system bearing a functional group (-NO2, -NH2, and -Cl) as a linking site model, and a tethering moiety (a methylene, ethylene, propylene butylene, or pentylene bridge) between the linking and coordinating sites. The optimized complexes showed geometries comparable to those inferred from X-ray data. In general, the Re complexes were more stable than the corresponding Tc complexes. Furthermore, using NH2 as the functional group, a medium length carbon chain, and ortho substitution increased complex stability. All of the bonds involving the metal center presented a closed shell interaction with dative or covalent character, and the strength of these bonds decreased in the sequence Tc-CO > Tc-O > Tc-N. PMID:27406231

  17. Removal of reactive dyes from textile wastewater by immobilized chitosan upon grafted Jute fibers with acrylic acid by gamma irradiation

    NASA Astrophysics Data System (ADS)

    Hassan, Mahmoud S.

    2015-10-01

    Jute fibers were grafted with acrylic acid by gamma irradiation technique. Chitosan was immobilized upon the grafted Jute fibers to be used as an adsorbent for waste reactive dye. The treated Jute fibers were characterized by using of Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effect of Jute treatment on its thermal stability by using thermogravimetric analysis (TGA) and its mechanical properties were investigated. The adsorption isotherm and the different factors affecting the dye adsorption such as pH and contact time were also studied. It was found that the dye adsorption was enhanced in the low pH range and increased with increasing of the contact time, regardless of temperature change.

  18. Effect of nano anhydrous magnesium carbonateon fire-retardant performance of polylactic acid/bamboo fibers composites.

    PubMed

    Li, Xingong; Wu, Yiqiang; Zheng, Xia

    2011-12-01

    Polylactic acid/bamboo fibers (PLA/BF) composites, which are extremely flammable, must be carried out fire-retardant processing. However, traditional organic flame retardants release certain amount of pollutant to the environment, and inorganic flame retardants require more addition, which influenced the mechanical properties of composites. Therefore, nano inorganic flame retardants, which have some characteristics of small size, uniform shape and high specific surface area, can bring good flame-retardant effect with relatively few addition. Meanwhile, it can enhance the interaction of composites interface, and disperse more evenly in polylactic acid matrix. Furthermore, it has light influence on the physical mechanical properties. In this study, nano anhydrous magnesium carbonate (NAMC) is used as flame retardant, Cone Calorimeter and Dynamic Thermal Mechanical Analyzer are adopted for studying the fire-retardant properties and the dynamic thermodynamic parameters of the polylactic acid/bamboo fiber composites, respectively. Results show that nano anhydrous magnesium carbonate flame retardant have good fire-retardant performance for the polylactic acid/bamboo fiber composites, considering practicality and economy, its ideal addition is 5%. PMID:22408960

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Poly(lactic) acid fibers loaded with mesoporous silica for potential applications in the active food packaging

    NASA Astrophysics Data System (ADS)

    Cacciotti, Ilaria; Nanni, Francesca

    2016-06-01

    Multifunctional fibrous systems based on poly(lactic) acid (PLA), mesoporous silica (SiO2) and ascorbic acid (AA) were produced by means of electrospinning technique, for potential applications in the active food packaging sector, as platform for the controlled release of antioxidant and/or antimicrobial agents with the additional filtering function. The ascorbic acid was physisorbed on the surface of mesoporous silica in order to stabilize it and to extend its antioxidant action. The influence of mesoporous silica and ascorbic acid on the microstructural and mechanical properties was investigated, revealing a revelant mechanical reinforcement in the case of fibers loaded only with SiO2 and a decrement in the case of SiO2 with physisorbed ascorbic acid, due to the worse interface between the fillers and the polymeric matrix.

  1. Synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotubes and carbon fiber for improved electro-activated polymeric shape-memory nanocomposite

    NASA Astrophysics Data System (ADS)

    Lu, Haibao; Min Huang, Wei

    2013-06-01

    The present work studies the synergistic effect of self-assembled carboxylic acid-functionalized carbon nanotube (CNT) and carbon fiber on the electrical property and electro-activated recovery behavior of shape memory polymer (SMP) nanocomposites. The combination of CNT and carbon fiber results in improved electrical conductivity in the SMP nanocomposites. Carboxylic acid-functionalized CNTs are grafted onto the carbon fibers and then self-assembled by deposition to significantly enhance the reliability of the bonding between carbon fiber and SMP via van der Waals and covalent crosslink. Furthermore, the self-assembled carboxylic acid-functionalized CNTs and carbon fibers enable the SMP nanocomposites for Joule heating triggered shape recovery.

  2. Label-free DNA biosensor based on a peptide nucleic acid-functionalized microstructured optical fiber-Bragg grating

    NASA Astrophysics Data System (ADS)

    Candiani, Alessandro; Bertucci, Alessandro; Giannetti, Sara; Konstantaki, Maria; Manicardi, Alex; Pissadakis, Stavros; Cucinotta, Annamaria; Corradini, Roberto; Selleri, Stefano

    2013-05-01

    We describe a novel sensing approach based on a functionalized microstructured optical fiber-Bragg grating for specific DNA target sequences detection. The inner surface of a microstructured fiber, where a Bragg grating was previously inscribed, has been functionalized by covalent linking of a peptide nucleic acid probe targeting a DNA sequence bearing a single point mutation implicated in cystic fibrosis (CF) disease. A solution of an oligonucleotide (ON) corresponding to a tract of the CF gene containing the mutated DNA has been infiltrated inside the fiber capillaries and allowed to hybridize to the fiber surface according to the Watson-Crick pairing. In order to achieve signal amplification, ON-functionalized gold nanoparticles were then infiltrated and used in a sandwich-like assay. Experimental measurements show a clear shift of the reflected high order mode of a Bragg grating for a 100 nM DNA solution, and fluorescence measurements have confirmed the successful hybridization. Several experiments have been carried out on the same fiber using the identical concentration, showing the same modulation trend, suggesting the possibility of the reuse of the sensor. Measurements have also been made using a 100 nM mismatched DNA solution, containing a single nucleotide mutation and corresponding to the wild-type gene, and the results demonstrate the high selectivity of the sensor.

  3. Acid Etching and Surface Coating of Glass-Fiber Posts: Bond Strength and Interface Analysis.

    PubMed

    Cecchin, Doglas; Farina, Ana Paula; Vitti, Rafael Pino; Moraes, Rafael Ratto; Bacchi, Ataís; Spazzin, Aloísio Oro

    2016-01-01

    The aim of this study was to evaluate the bond strength of a composite resin to glass-fiber post (GFP) treated or not with phosphoric acid, silane coupling agent, and unfilled resin. GFPs were etched or not with 37% phosphoric acid and different surface coating applied: silane coupling agent, unfilled resin, or both. Composite resin blocks were built around a 4-mm height on the GFP. Unfilled resin (20 s) and composite resin (40 s) were light activated by a light-emitting diode unit. The specimens were stored in distilled water at 37 °C for 24 h. Microtensile bond test was performed using a mechanical testing machine until failure (n=10). The data were analyzed using two-way ANOVA followed by Student-Newman-Keuls' test (p<0.05). Failure modes were classified as adhesive, mixed, or cohesive failures. Additional specimens (n=3) were made to analyze the bonded interfaces by scanning electron microscopy. The statistical analysis showed the factor 'surface coating' was significant (p<0.05), whereas the factor 'HP etching' (p=0.131) and interaction between the factors (p=0.171) were not significant. The highest bond strength was found for the silane and unfilled resin group (p<0.05). A predominance of adhesive and cohesive failures was found. Differences regarding the homogeneity and thickness of the unfilled resin layer formed by different GFP surface treatments were observed. The application of silane and unfilled resin can improve the bond strength between GFP and resin composite. PMID:27058389

  4. Binding of water, oil, and bile acids to dietary fibers of the cellan type.

    PubMed

    Dongowski, G; Ehwald, R

    1999-01-01

    Dietary fibers (DF) of the "cellan" type (consisting mainly or exclusively of undestroyed cells) were prepared as ethanol-dried materials from apple, cabbage, sugar-beet, soybean hulls, wheat bran, and suspension cultures of Chenopodium album L. and investigated with respect to their interactions with water, water-oil dispersions, bile acids, and oil. Water binding and retention capacities were found to be especially high in cellans obtained from thin-walled raw material. Water damp sorption by dry cellans, when analyzed according to the GAB and BET equations, shows a considerable fraction of monolayer water. At a water activity of 0.98, the cell and capillary spaces outside the walls remained in the air-filled state but the cell wall pores are filled with water. When the water content of a concentrated aqueous cellan suspension was equal to or below the water binding capacity, its rheological behavior was found to be of pseudoplastic nature. At a given dry weight concentration, yield stress and viscosity of such concentrated suspensions were highest for cellans with the highest water binding capacity. Dry cellan particles absorbed fatty oils without swelling but swell in a detergent-stabilized oil/water emulsion with a similar liquid absorption capacity as in water. In contrast to the dry or alkane-saturated cell wall, the hydrated wall is not permeable to oils in the absence of a detergent. Oil droplets may be entrapped within the cells, yielding a stable dispersion of oil in water. As DF of the cellan type absorb bile acids, preferentially glycoconjugates, from diluted solutions, they may have a potential to decrease the serum cholesterol level. PMID:10194401

  5. Kinetics and Thermodynamics of Reserpine Adsorption onto Strong Acidic Cationic Exchange Fiber

    PubMed Central

    Guo, Zhanjing; Liu, Xiongmin; Huang, Hongmiao

    2015-01-01

    The kinetics and thermodynamics of the adsorption process of reserpine adsorbed onto the strong acidic cationic exchange fiber (SACEF) were studied by batch adsorption experiments. The adsorption capacity strongly depended on pH values, and the optimum reserpine adsorption onto the SACEF occurred at pH = 5 of reserpine solution. With the increase of temperature and initial concentration, the adsorption capacity increased. The equilibrium was attained within 20 mins. The adsorption process could be better described by the pseudo-second-order model and the Freundlich isotherm model. The calculated activation energy Ea was 4.35 kJ/mol. And the thermodynamic parameters were: 4.97<ΔH<7.44 kJ/mol, -15.29<ΔG<-11.87 kJ/mol and 41.97<ΔS<47.35 J/mol·K. The thermodynamic parameters demonstrated that the adsorption was an endothermic, spontaneous and feasible process of physisorption within the temperature range between 283 K and 323 K and the initial concentration range between 100 mg/L and 300 mg/L. All the results showed that the SACEF had a good adsorption performance for the adsorption of reserpine from alcoholic solution. PMID:26422265

  6. Electrospun polylactic acid and polyvinyl alcohol fibers as efficient and stable nanomaterials for immobilization of lipases.

    PubMed

    Sóti, Péter Lajos; Weiser, Diana; Vigh, Tamás; Nagy, Zsombor Kristóf; Poppe, László; Marosi, György

    2016-03-01

    Electrospinning was applied to create easy-to-handle and high-surface-area membranes from continuous nanofibers of polyvinyl alcohol (PVA) or polylactic acid (PLA). Lipase PS from Burkholderia cepacia and Lipase B from Candida antarctica (CaLB) could be immobilized effectively by adsorption onto the fibrous material as well as by entrapment within the electrospun nanofibers. The biocatalytic performance of the resulting membrane biocatalysts was evaluated in the kinetic resolution of racemic 1-phenylethanol (rac-1) and 1-phenylethyl acetate (rac-2). Fine dispersion of the enzymes in the polymer matrix and large surface area of the nanofibers resulted in an enormous increase in the activity of the membrane biocatalyst compared to the non-immobilized crude powder forms of the lipases. PLA as fiber-forming polymer for lipase immobilization performed better than PVA in all aspects. Recycling studies with the various forms of electrospun membrane biocatalysts in ten cycles of the acylation and hydrolysis reactions indicated excellent stability of this forms of immobilized lipases. PLA-entrapped lipases could preserve lipase activity and enantiomer selectivity much better than the PVA-entrapped forms. The electrospun membrane forms of CaLB showed high mechanical stability in the repeated acylations and hydrolyses than commercial forms of CaLB immobilized on polyacrylamide beads (Novozyme 435 and IMMCALB-T2-150). PMID:26724947

  7. Polyvalent metal ion chelating agents for xanthan solutions

    SciTech Connect

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

    1984-08-21

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

  8. 3-hydroxy-2(1H)-pyridinone chelating agents

    DOEpatents

    Raymond, K.N.; Xu, J.

    1997-04-29

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

  9. 3-hydroxy-2(1H)-pyridinone chelating agents

    DOEpatents

    Raymond, Kenneth N.; Xu, Jide

    1997-01-01

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

  10. Efficacy of reversal of aortic calcification by chelating agents

    PubMed Central

    Lei, Yang; Sinha, Aditi; Vyavahare, Naren

    2013-01-01

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

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

    PubMed

    Durbin, Patricia W

    2008-11-01

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

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

    EPA Science Inventory

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

  13. A new radiochemical method to study the stability of metal chelates used in radiopharmaceuticals

    SciTech Connect

    Subramanian, K.M.; Wolf, W.

    1985-05-01

    Bifunctional chelates are more and more actively used to allow radiolabeling of proteins following metal chelation. While there are data in the literature on the stability constants of the free metal chelates in solution, such methods are neither simple nor suitable for the determination of metal-chelate stability constants following coupling of the bifunctional chelate to a protein. The authors present a novel method for determining the stability constants of indium chelates, which is based on the use of ferric ions as displacement cations. Indium-111 or inium-114m labeled 1:1 In-chelates were incubated with molar equivalents of ferric ions at acidic and neutral pH. At equilibrium this mixture was analyzed by paper and cation-exchange chromatography to determine free and complexed indium. The position equilibrium constants 'K' were calculated from the above data. Using the known stability constants of the ferric chelates ..beta.. and the 'K' values, the stability constants of the indium chelates of several amino polycarboxylic acids, such as NTA, EDTA, DTPA and TTHA were determined. The results obtained were: (current work, literature value) - In-NTA: 16.0, 16.9; In-EDTA: 25.3, 25.3; In-DTPA: 28.7, 29.0; In-TTHA: 27.8, -. These results document that the values obtained by this new method agree well with the values reported in the literature determined by potentiometric titrations. The simplicity of the current method and the ease of calculation of the K values renders this procedure easy to use for the study of indium (and probably other metal) chelates. This method may find special use in determining the stability constants of indium labeled chelates conjugated to proteins, such as in monoclonal antibodies.

  14. Questions and Answers on Unapproved Chelation Products

    MedlinePlus

    ... OTC) to prevent or treat diseases. Companies are marketing unapproved OTC chelation therapy products to patients with ... 4. Why did FDA take this action? Companies marketing unapproved OTC chelation products with unsubstantiated treatment claims ...

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

    PubMed Central

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

    2010-01-01

    Two bifunctional Cu-64 chelators (BFCs), (6-(6-(3-(2-pyridyldithio)propionamido)hexanamido)benzyl)-1,4,8,11-tetraazacyclotetradecane- 1,4,8,11-tetraacetic acid (TETA-PDP) and 4-(2-(2-pyridyldithioethyl)ethanamido)-11-carboxymethyl-1,4,8,11-tetraazabicyclo(6.6.2)hexadecane (CB-TE2A-PDEA), were synthesized and conjugated to long circulating liposomes (LCLs) via attachment to a maleimide lipid. An in vitro stability assay of 64Cu-TETA, 64Cu-TETA-PEG2k, and 64Cu-CB-TE2A-PEG2k liposomes showed that more than 86% of the radioactivity remains associated with the liposomal fraction after 48 hours of incubation with mouse serum. The in vivo time activity curves (TAC) for the three liposomal formulations showed that ~50% of the radioactivity cleared from the blood pool in 16 - 18 hours. As expected, the in vivo biodistribution and TAC data obtained at 48 hours demonstrate that the clearance of radioactivity from the liver slows with the incorporation of a polyethylene glycol-2k (PEG2k) brush. Our data suggest that 64Cu-TETA and 64Cu-CB-TE2A are similarly stable in the blood pool and accumulation of radioactivity in the liver and spleen is not related to the stability of Cu-64 chelator complex; however clearance of Cu-64 from the liver and spleen are faster when injected as 64Cu-TETA-chelated liposomes rather than 64Cu-CB-TE2A-chelated liposomes. PMID:20568726

  16. Hydroxypyridonate and hydroxypyrimidinone chelating agents

    SciTech Connect

    Raymond, Kenneth N.; Doble, Daniel M.; Sunderland, Christopher J.; Thompson, Marlon

    2005-01-25

    The present invention provides hydroxypyridinone and hydroxypyrimidone chelating agents. Also provides are Gd(III) complexes of these agents, which are useful as contrast enhancing agents for magnetic resonance imaging. The invention also provides methods of preparing the compounds of the invention, as well as methods of using the compounds in magnetic resonance imaging applications.

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

    SciTech Connect

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

    1997-11-01

    The absorption of nitric oxide (NO) into aqueous solutions of ferrous chelates of nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), hydroxyethylenediaminetriacetic acid (HEDTA), and diethylenetriaminepentaacetic acid (DTPA) was studied in a stirred cell reactor. The absorption leads to stable ferrous NO chelates. Due to the high reaction rate, in combination with the relatively high P{sub NO} applied, the absorption rate is strongly affected by mass transfer limitation only. By applying penetration theory, the ratio of the diffusion coefficients of ferrous chelates and NO was determined. At elevated T, (D{sub Fe(II)chelate}/D{sub NO}){sup 1/2} decreases due to the unusual T-dependency of D{sub NO}. For ferrous NTA, the formation of the ferrous NO chelate is accompanied by pH effects that can be understood from iron chelate chemistry. In the case of ferrous NTA, pH < 5, or an excess of ligand, these effects lead to local pH gradients at the gas-liquid interface, that substantially affect the NO absorption rates. Kinetic data from the literature on the absorption of NO into ferrous chelates were evaluated using the mass transfer parameters determined. These kinetic data are often unreliable.

  18. A multi-point sensor based on optical fiber for the measurement of electrolyte density in lead-acid batteries.

    PubMed

    Cao-Paz, Ana M; Marcos-Acevedo, Jorge; del Río-Vázquez, Alfredo; Martínez-Peñalver, Carlos; Lago-Ferreiro, Alfonso; Nogueiras-Meléndez, Andrés A; Doval-Gandoy, Jesús

    2010-01-01

    This article describes a multi-point optical fiber-based sensor for the measurement of electrolyte density in lead-acid batteries. It is known that the battery charging process creates stratification, due to the different densities of sulphuric acid and water. In order to study this process, density measurements should be obtained at different depths. The sensor we describe in this paper, unlike traditional sensors, consists of several measurement points, allowing density measurements at different depths inside the battery. The obtained set of measurements helps in determining the charge (SoC) and state of health (SoH) of the battery. PMID:22319262

  19. A Multi-Point Sensor Based on Optical Fiber for the Measurement of Electrolyte Density in Lead-Acid Batteries

    PubMed Central

    Cao-Paz, Ana M.; Marcos-Acevedo, Jorge; del Río-Vázquez, Alfredo; Martínez-Peñalver, Carlos; Lago-Ferreiro, Alfonso; Nogueiras-Meléndez, Andrés A.; Doval-Gandoy, Jesús

    2010-01-01

    This article describes a multi-point optical fiber-based sensor for the measurement of electrolyte density in lead-acid batteries. It is known that the battery charging process creates stratification, due to the different densities of sulphuric acid and water. In order to study this process, density measurements should be obtained at different depths. The sensor we describe in this paper, unlike traditional sensors, consists of several measurement points, allowing density measurements at different depths inside the battery. The obtained set of measurements helps in determining the charge (SoC) and state of health (SoH) of the battery. PMID:22319262

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

    SciTech Connect

    Domingo, J.L.; Ortega, A.; Llobet, J.M.; Corbella, J. )

    1990-01-01

    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.

  1. Natural chelating agents for radionuclide decorporation

    DOEpatents

    Premuzic, Eugene T.

    1988-01-01

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

  2. Chromium uptake by Spirodela polyrrhiza (L. ) Schleiden in relation to metal chelators and pH

    SciTech Connect

    Tripathi, R.D.; Chandra, P. )

    1991-11-01

    This paper reports the influence of metal chelators, ethylenediaminetetraacetic acid (EDTA) and salicylic acid, and pH on the accumulation of Cr by S. polyrrhiza under the laboratory conditions. This also includes the results of K.D. pond water treatment study by cultured fronds of S. polyrrhiza. In view of the occurrence of metal chelators in natural waters and pH variation the present study would enable to assess the performance of this species under the influence of these factors.

  3. Alteration of tissue disposition of cadmium by chelating agents. [Mice; rats

    SciTech Connect

    Klaassen, C.D.; Waalkes, M.P.; Cantilena, L.R. Jr.

    1984-03-01

    The effect of several chelating agents (diethyldithiocarbamic acid, DDC; nitrilotriacetic acid, NTA; 2,3-dimercaptopropanol, BAL; d,l-penicillamine, PEN; 2,3-dimercaptosuccinic acid, DMSA; ethylenediaminetetraacetic acid, EDTA; and diethylenetriaminepentaacetic acid, DTPA) on the toxicity, distribution and excretion of cadmium (Cd) was determined in mice. When chelators were administered immediately after Cd, significant increases in survival were noted after treatment with DMSA, EDTA, and DTPA. DTPA, followed by EDTA and then DMSA, were consistently the most effective in decreasing the tissue concentrations of Cd and increasing the excretion of Cd. NTA, BAL, DDC and PEN had no beneficial effects. To determine the role of MT in the acute decrease in chelator efficacy following Cd poisoning, rats were injected IV with Cd followed by DTPA at various times after Cd. Although DTPA reduced Cd content in the various organs when given immediately after Cd, the chelator was ineffective at all later times. Increases in hepatic and renal metallothionein (MT) did not occur until 2 hr after Cd, and did not coincide with the earlier drop in chelator efficacy. Blockade of MT synthesis by actinomycin D failed to eliminate this decreased DTPA effectiveness. Therefore, it appears that MT does not play an important role in the acute decrease in efficacy of chelation therapy for Cd poisoning. The effect of repeated daily administration of chelators on the distribution and excretion of Cd was studied by administering chelators daily for 5 days starting 48 hr after Cd. DTPA, EDTA, DMSA and BAL significantly increased the urinary elimination of Cd. Thus, mobilization of Cd into urine occurs with repeated chelation therapy, which may decrease tissue concentrations of Cd and reduce the toxicity of the metal. 4 references, 15 figures, 2 tables.

  4. PHENOLIC ACIDS, LIPIDS, AND PROTEINS ASSOCIATED WITH PURIFIED CORN FIBER ARABINOXYLANS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn fiber gum (CFG) is a hemicellulose (arabinoxylan)-enriched fraction obtained by the extraction of corn bran/fiber using a proprietary alkaline hydrogen peroxide process. When purified CFG prepared by this process was hydrolyzed with more concentrated base (1.5 N methanolic KOH at 70 °C for one...

  5. Structural, electrical, mechanical, and thermal properties of electrospun poly(lactic acid)/polyaniline blend fibers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conducting electrospun fiber mats based on PLA and PAni blends were obtained with average diameter values between 87 and 1,006 nm with PAni quantities from 0 to 5.6 wt.-%. Structural characteristics of fiber mats were compared to cast films with the same amount of PAni and studied by SEM, SAXS, and ...

  6. Effect of ascorbic acid, ethanol and acetone on adhesion between the treated fiber posts and composite resin cores

    PubMed Central

    Zahra, Khamverdi

    2012-01-01

    PURPOSE The aim of the present study was to assess the effect of ascorbic acid, ethanol and acetone on microtensile bond strength between fiber posts pre-treated with hydrogen peroxide and composite resin cores. MATERIALS AND METHODS Twenty four fiber posts were pre-treated with 24% hydrogen peroxide and divided into 4 groups as follows: G1: no treatment, as control group; G2: treatment with 10% ascorbic acid solution for 5 minutes; G3: treatment with 70% ethanol solution for 5 minutes; and G4: treatment with 70% acetone solution for 5 minutes. Each fiber post was surrounded by a cylinder-shaped polyglass matrix which was subsequently filled with composite resin. Two sections from each sample were selected for microtensile test at a crosshead with speed of 0.5 mm/min. Statistical analyses were performed using one-way ANOVA and a post hoc Tukey HSD test. Fractured surfaces were observed under a stereomicroscope at ×20 magnification. The fractured surfaces of the specimens were observed and evaluated under a SEM. RESULTS Means of microtensile bond strength values (MPa) and standard deviations in the groups were as follows: G1: 9.70±0.81; G2: 12.62±1.80; G3: 16.60±1.93; and G4: 21.24±1.95. G4 and G1 had the highest and the lowest bond strength values, respectively. A greater bond strength value was seen in G3 compared to G2. There were significant differences between all the groups (P<.001). All the failures were of the adhesive mode. CONCLUSION Application of antioxidant agents may increase microtensile bond strength between fiber posts treated with hydrogen peroxide and composite cores. Acetone increased bond strength more than ascorbic acid and ethanol. PMID:23236569

  7. Improved paramagnetic chelate for molecular imaging with MRI

    NASA Astrophysics Data System (ADS)

    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.

  8. Chitosan-tethered poly(acrylonitrile-co-maleic acid) hollow fiber membrane for lipase immobilization.

    PubMed

    Ye, Peng; Xu, Zhi-Kang; Che, Ai-Fu; Wu, Jian; Seta, Patrick

    2005-11-01

    A protocol was used to prepare a dual-layer biomimetic membrane as support for enzyme immobilization by tethering chitosan on the surface of poly(acrylonitrile-co-maleic acid) (PANCMA) ultrafiltration hollow fiber membrane in the presence of 1-ethyl-3-(dimethylaminopropyl) carbodiimide hydrochloride (EDC)/N-hydroxylsuccin-imide (NHS). The chemical change of the chitosan-modified PANCMA membrane surface was confirmed with Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Lipase from Candida rugosa was immobilized on this dual-layer biomimetic membrane using glutaraldehyde (GA), and on the nascent PANCMA membrane using EDC/NHS as coupling agent. The properties of the immobilized enzymes were assayed and compared with those of the free one. It was found that both the activity retention of the immobilized lipase and the amount of bound protein on the dual-layer biomimetic membrane (44.5% and 66.5 mg/m2) were higher than those on the nascent PANCMA membrane (33.9% and 53.7 mg/m2). The kinetic parameters of the free and immobilized lipases, Km and Vmax, were also assayed. The Km values were similar for the immobilized lipases, while the Vmax value of the immobilized lipase on the dual-layer biomimetic membrane was higher than that on the nascent PANCMA membrane. Results indicated that the pH and thermal stabilities of lipase increased upon immobilization. The residual activity of the immobilized lipase after 10 uses was 53% on the dual-layer biomimetic membrane and 62% on the nascent PANCMA membrane. PMID:15919112

  9. Osteogenesis of human adipose-derived stem cells on poly(dopamine)-coated electrospun poly(lactic acid) fiber mats.

    PubMed

    Lin, Chi-Chang; Fu, Shu-Juan

    2016-01-01

    Electrospinning is a versatile technique to generate large quantities of micro- or nano-fibers from a wide variety of shapes and sizes of polymer. The aim of this study is to develop functionalized electrospun nano-fibers and use a mussel-inspired surface coating to regulate adhesion, proliferation and differentiation of human adipose-derived stem cells (hADSCs). We prepared poly(lactic acid) (PLA) fibers coated with polydopamine (PDA). The morphology, chemical composition, and surface properties of PDA/PLA were characterized by SEM and XPS. PDA/PLA modulated hADSCs' responses in several ways. Firstly, adhesion and proliferation of hADSCs cultured on PDA/PLA were significantly enhanced relative to those on PLA. Increased focal adhesion kinase (FAK) and collagen I levels and enhanced cell attachment and cell cycle progression were observed upon an increase in PDA content. In addition, the ALP activity and osteocalcin of hADSCs cultured on PDA/PLA were significantly higher than seen in those cultured on a pure PLA mat. Moreover, hADSCs cultured on PDA/PLA showed up-regulation of the ang-1 and vWF proteins associated with angiogenesis differentiation. Our results demonstrate that the bio-inspired coating synthetic degradable PLA polymer can be used as a simple technique to render the surfaces of synthetic biodegradable fibers, thus enabling them to direct the specific responses of hADSCs. PMID:26478309

  10. Modification of poly(L-lactic acid) electrospun fibers and films with poly(propylene imine) dendrimer

    NASA Astrophysics Data System (ADS)

    Khaliliazar, Sh.; Akbari, S.; Kish, M. H.

    2016-02-01

    Poly(L-lactic acid) (PLLA) electrospun fibers and films were modified with the second generation of poly(propylene imine) dendrimer (PPI-G2) by three different approaches, namely, sodium hydroxide hydrolysis, plasma treatment and direct application of PPI-G2. For the first and the second approaches, PLLA was modified by sodium hydroxide hydrolysis or plasma treatment to produce carboxylic acid groups. Then, the carboxylic acid groups were activated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) and N,N‧-dicyclohexyl carbodiimide (DCC) as a hetero bi-functional cross-linker. The cross-linkers promoted the grafting of carboxylic acid groups on the modified PLLA with NH2 groups of PPI-G2. In the third approach, the PPI-G2 dendrimer was directly used as an aminolysis agent for the functionalization of PLLA in a one step process. FTIR analysis confirmed the presence of sbnd NH2 groups of PPI-G2 on the modified PLLA samples, resulting from each one of the three modification methods. Studies by SEM shows bead free electrospun fibers. Also, FE-SEM shows nano-cracks on the surface of films after modification. Contact angle, drug release tests, antibacterial effects and the dying results confirmed that these functionalization methods increased hydrophilicity and reactive side-chains of PLLA in the wet chemical process resulted in providing host-guest properties on the PLLA surface for adsorbing various kinds of guest molecules.

  11. Removal of nickel by chelating drugs from the organs of nickel poisoned rats

    SciTech Connect

    Dwivedi, P.P.; Athar, M.; Hasan, S.K.; Srivastava, R.C.

    1986-01-01

    The chelating drugs namely ethylenediamine tetraacetic acid (EDTA), 1,2,cyclohexylenediamine tetraacetic acid (CDTA), hydroxyethylenediamine triacetic acid (HEDTA) diethylenetriamine pentaacetic acid (DTPA), and triethylenetetraamine hexaacetic acid (TTHA), were examined for the mobilization of nickel from body organs of sham operated and partially hepatectomized rats in early nickel poisoning. These chelating drugs successfully reduced the body burden of nickel from both the nickel treated experimental groups. EDTA was relatively more effective in reducing the hepatic content of nickel while CDTA and HEDTA were more effective in reducing its renal content. These drugs also reduced nickel burden in heart and lung to variable degrees.

  12. Chelator-induced phytoextraction of zinc and copper by rice seedlings.

    PubMed

    Yu, Xiao-Zhang; Wang, Dun-Qiu; Zhang, Xue-Hong

    2014-05-01

    Solution culture was carried to investigate capacity of synthetic aminopolycarboxylic acids (ethylenediamine tetraacetate, N-hydroxyethylenediaminetriacetic acid, and diethylenetriamine-pentaacetate) for enhancing botanical removal and transport of heavy metals (Cu and Zn) by plants. Biodegradable organic acids (citric acid, malic acid, and oxalic acid) were also selected as alternatives to compare them with synthesized chelating agents for effectiveness. Young rice seedlings (Oryza sativa L. cv. XZX 45) were grown in nutrient solutions treated with single or combined metal solutions in presence or absence of chelating compounds. Calculation by chemical equilibrium program VISUAL MINTEQ showed that different chelating compounds had various complex potential with Cu(2+) and Zn(2+) ions, in which synthetic chelators exhibited higher complexed capability than biodegradable organic acids. All applied synthetic aminopolycarboxylic acids significantly decreased removal of metal from nutrient solution (p < 0.01), while more or less effects of organic acids supplied on biosorptive potential were observed with all treatments (p > 0.05), compared with the treatment without metal ligands. Synthetic aminopolycarboxylic acids significantly decreased metal concentrations in plant materials in all treatments (p < 0.01). However, biodegradable organic acids decreased metal concentrations in roots (p < 0.01), but enhanced them in shoots (p < 0.01). Results obtained indicated that synthetic aminopolycarboxylic acids decreased uptake of metals by rice seedlings, but translocation of metals complexed within plant materials was evident. Although exogenous biodegradable organic acids showed negligible effect on botanical removal of metals, metals complexed with organic acids was more mobile than those complexed with other chelating agents. These information collected here had important implication for the use of biodegradable metal chelators in transport of essential micronutrients in

  13. Heavy metal displacement in chelate-irrigated soil during phytoremediation

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

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

    2007-10-25

    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. PMID:17631934

  15. Luminescent lanthanide chelates and methods of use

    DOEpatents

    Selvin, Paul R.; Hearst, John

    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.

  16. Some Linguistic Detail on Chelation

    NASA Astrophysics Data System (ADS)

    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.

  17. Adaptation of healthy adult cats to select dietary fibers in vivo affects gas and short-chain fatty acid production from fiber fermentation in vitro.

    PubMed

    Barry, K A; Wojcicki, B J; Bauer, L L; Middelbos, I S; Vester Boler, B M; Swanson, K S; Fahey, G C

    2011-10-01

    Nine young adult (1.73 ± 0.03 yr) male cats were used to determine the effects of microbial adaptation to select dietary fiber sources on changes in pH in vitro and on total and hydrogen gas, short-chain fatty acid (SCFA), and branched-chain fatty acid (BCFA) production. Cats were adapted to diets containing 4% cellulose, fructooligosaccharides (FOS), or pectin for 30 d before fecal sampling. Each cat was used as a single donor, and fecal inoculum was reacted with each of the aforementioned fiber substrates. Adaptation to dietary FOS resulted in a greater change in pH when exposed to FOS than pectin (adaptation × substrate, P < 0.001). When exposed to the FOS substrate, adaptation to dietary FOS or pectin increased hydrogen gas production (adaptation × substrate, P = 0.021). Adaptation to dietary FOS increased acetate and total SCFA production when exposed to FOS substrate in vitro (adaptation × substrate, P = 0.001). When exposed to the FOS substrate, propionate production tended to increase with adaptation to dietary cellulose (adaptation × substrate, P = 0.060). The BCFA + valerate tended to decrease with adaptation to dietary FOS when exposed to FOS substrate in vitro (adaptation × substrate, P = 0.092). Fructooligosaccharides resulted in the greatest change in pH and production of total gas (P < 0.001), hydrogen gas (P < 0.001), acetate (P < 0.001), propionate (P < 0.001), butyrate (P < 0.001), total SCFA (P < 0.001), and total BCFA + valerate production (P < 0.001). Adaptation to the FOS or pectin diet increased production of hydrogen gas with FOS and pectin substrates. Adaptation to pectin increased (P = 0.033) total gas production with FOS and pectin substrates. Overall, adaptation to either FOS or pectin led to greater SCFA and gas production, but adaptation to FOS resulted in the greatest effect overall. PMID:21531846

  18. Photonic crystal fiber interferometric pH sensor based on polyvinyl alcohol/polyacrylic acid hydrogel coating.

    PubMed

    Hu, Pengbing; Dong, Xinyong; Wong, Wei Chang; Chen, Li Han; Ni, Kai; Chan, Chi Chiu

    2015-04-01

    We present a simple photonic crystal fiber interferometer (PCFI) that operates in reflection mode for pH measurement. The sensor is made by coating polyvinyl alcohol/polyacrylic acid (PVA/PAA) hydrogel onto the surface of the PCFI, constructed by splicing a stub of PCF at the distal end of a single-mode fiber with its free end airhole collapsed. The experimental results demonstrate a high average sensitivity of 0.9 nm/pH unit for the 11 wt.% PVA/PAA coated sensor in the pH range from 2.5 to 6.5. The sensor also displays high repeatability and stability and low cross-sensitivity to temperature. Fast, reversible rise and fall times of 12 s and 18 s, respectively, are achieved for the sensor time response. PMID:25967171

  19. Chelating agents and cadmium intoxication

    SciTech Connect

    Shinobu, L.A.

    1985-01-01

    A wide range of conventional chelating agents have been screened for (a) antidotal activity in acute cadmium poisoning and (b) ability to reduce aged liver and kidney deposits of cadmium. Chelating agents belonging to the dithiocarbamate class have been synthesized and tested in both the acute and chronic modes of cadmium intoxication. Several dithiocarbamates, not only provide antidotal rescue, but also substantially decrease the intracellular deposits of cadmium associated with chronic cadmium intoxication. Fractionating the cytosol from the livers and kidneys of control and treated animals by Sephadex G-25 gel filtration clearly demonstrates that the dithiocarbamates are reducing the level of metallothionein-bound cadmium. However, the results of cell culture (Ehrlich ascites) studies designed to investigate the removal of cadmium from metallothionein and subsequent transport of the resultant cadmium complex across the cell membrane were inconclusive. In other in vitro investigations, the interaction between isolated native Cd, Zn-metallothionein and several chelating agents was explored. Ultracentrifugation, equilibrium dialysis, and Sephadex G-25 gel filtration studies have been carried out in an attempt to determine the rate of removal of cadmium from metallothionein by these small molecules. Chemical shifts for the relevant cadmium-dithiocarbamate complexes have been determined using natural abundance Cd-NMR.

  20. Anaerobic conversion of lignocellulosic corn fiber to butyric acid, a substrate for microbial butanol production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many factors, including sharply fluctuating fuel prices and questions regarding the sustainability of fuel produced from potential food crops, have bolstered interest in renewable fuels from alternative feedstocks. We tested pretreated and nonpretreated corn fiber for its susceptibility to hydrolys...

  1. Feasibility study of prestressed natural fiber-reinforced polylactic acid (pla) composite materials

    NASA Astrophysics Data System (ADS)

    Hinchcliffe, Sean A.

    The feasibility of manufacturing prestressed natural-fiber reinforced biopolymer composites is demonstrated in this work. The objective of this study was to illustrate that the specific mechanical properties of biopolymers can be enhanced by leveraging a combination of additive manufacturing (3D printing) and post-tensioning of continuous natural fiber reinforcement. Tensile and flexural PLA specimens were 3D-printed with and without post-tensioning ducts. The mechanical properties of reinforcing fibers jute and flax were characterized prior to post-tensioning. The effect of matrix cross-sectional geometry and post-tensioning on the specific mechanical properties of PLA were investigated using mechanical testing. Numerical and analytical models were developed to predict the experimental results, which confirm that 3D-printed matrices improve the specific mechanical properties of PLA composites and are further improved via initial fiber prestressing. The results suggest that both additive manufacturing and fiber prestressing represent viable new methods for improving the mechanical performance of natural fiber-reinforced polymeric composites.

  2. Amino acid specificity of fibers of the facial/trigeminal complex innervating the maxillary barbel in the Japanese sea catfish, Plotosus japonicus.

    PubMed

    Caprio, John; Shimohara, Mami; Marui, Takayuki; Kohbara, Jun; Harada, Shuitsu; Kiyohara, Sadao

    2015-12-01

    The Japanese sea catfish, Plotosus japonicus, possesses taste and solitary chemoreceptor cells (SCCs) located on the external body surface that detect specific water-soluble substances. Here, we identify two major fiber types of the facial/trigeminal complex that transmit amino acid information to the medulla. Both single and few fiber preparations respond to amino acid stimulation in the 0.1 μM to mM range. One fiber type responds best to glycine and l-alanine (i.e. Gly/Ala fibers) whereas the other fiber type is best stimulated by l-proline and glycine betaine (hereafter referred to only as betaine) (i.e. Pro/Bet fibers). We demonstrate that betaine, which does not alter the pH of the seawater and therefore does not activate the animals' highly sensitive pH sensors (Caprio et al., Science 344:1154-1156, 2014), is sufficient to elicit appetitive food search behavior. We further show that the amino acid specificity of fibers of the facial/trigeminal complex in P. japonicus is different from that in Ariopsis felis (Michel and Caprio, J. Neurophysiol. 66:247-260, 1991; Michel et al., J. Comp. Physiol. A. 172:129-138, 1993), a representative member of the only other family (Ariidae) of extant marine catfishes. PMID:26459116

  3. Removal of humic acid by a new type of electrical hollow-fiber microfiltration (E-HFMF)

    NASA Astrophysics Data System (ADS)

    Shang, Ran; Deng, Hui-ping; Hu, Jing-yi

    2010-11-01

    Low pressure membrane filtration, such as microfiltration, was widely used in the field of drinking water purification in the past few decades. Traditional microfiltration membranes are not efficient enough in the removal of natural organic matters (NOM) from raw water. Moreover, they tend to be fouled by the NOM and the filtration age of the membranes is thus shrinked. To tackle these problems, a new type of electrical hollow-fiber microfiltration module (E-HFMF) was designed. In the E-HFMF module, the hollow-fiber microfiltration membranes were placed into the radialized electrical field which functioned from the centre to the exterior of the cylindrical cavity. The main goal of the present study was to evaluate the efficiency of E-HFMF to remove the humic acid (HA, one of the main components of NOM). According to the parallel tests compared with the traditional microfiltration, the removal rate of humic acid was raised to 70%˜85% in terms of UV-254 and to 60%˜75% in terms of DOC when filtrating with the E-HFMF, while the removal rates of humic acid were 10%˜20% and 1%˜10% respectively when filtrating with the traditional microfiltration. The negative charged humic acid moved to the anode because of the electrophoresis, so few humic acid could be able to permeate through the membrane. The electrophoresis mobility of the humic acid permeating through the traditional microfiltration decreased by 19%, while the same index from the E-HFMF decreased by 75%. This indicated that the electrophoresis played a significant role on removing the humic acid. According to the gel permeate chromatograph analysis, humic acid aggregated in an electric field and thus forms loose and permeable cake layer on the membrane surface, which also relieved membrane fouling. Meanwhile, the negative charged humic acid migrating to the anode at the center minimized the deposition onto the membrane surface, and eliminated the membrane fouling as a result. During the E-HFMF filtration, the

  4. Extraction of cellulose nano-crystals from old corrugated container fiber using phosphoric acid and enzymatic hydrolysis followed by sonication.

    PubMed

    Tang, Yanjun; Shen, Xiaochuang; Zhang, Junhua; Guo, Daliang; Kong, Fangong; Zhang, Nan

    2015-07-10

    Due to its amazing physicochemical properties and high environmental compatibility, cellulose nano-crystals (CNC) hold great promise for serving as a strategic platform for sustainable development. Now, there has been growing interest in the development of processes using waste or residual biomass as CNC source for addressing economic and environmental concerns. In the present work, a combined process involving phosphoric acid hydrolysis, enzymatic hydrolysis and sonication was proposed aiming to efficiently exact CNC from low-cost old corrugated container (OCC) pulp fiber. The effect of enzymatic hydrolysis on the yield and microstructure of resulting CNC was highlighted. Results showed that the enzymatic hydrolysis was effective in enhancing CNC yield after phosphoric acid hydrolysis. CNC was obtained with a yield of 23.98 wt% via the combined process with phosphoric acid concentration of 60 wt%, cellulase dosage of 2 mL (84 EGU) per 2g fiber and sonication intensity of 200 W. Moreover, the presence of enzymatic hydrolysis imparted the obtained CNC with improved dispersion, increased crystallinity and thermal stability. PMID:25857993

  5. An Evaluation of the Chelating Agent EDDS for Floriculture Crop Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  6. Molecular weight distribution of soluble fiber fractions and short chain fatty acids in ileal digesta of growing pigs.

    PubMed

    Ivarsson, E; Andersson, R; Lindberg, J E

    2012-12-01

    The effect of dietary fiber source on molecular weight (MW) distribution of soluble fiber fractions and short chain fatty acids (SCFA) in ileal digesta of 7 post valve T-cecum (PVTC) cannulated growing pigs was studied. Pigs were fed semisynthetic diets with sugar beet (Beta vulgaris) pulp (SBP) or chicory (Cichorium intybus) forage (CFO) as fiber sources of which the soluble nonstarch polysaccharide (NSP) fraction originated mainly from pectin. Three MW intervals were selected-large MW (MWL): 10,000,000 to 1,000,000 g/mol, medium MW (MWM): 1,000,000 to 200,000 g/mol, and small MW (MWS): 200,000 to 10,000 g/mol-and the relative distribution (% of total) of molecules in each interval was calculated. The MWM fraction was higher (P < 0.05) in ileal digesta of pigs fed diet SBP and the MWS fraction was higher (P < 0.05) in ileal digesta of pigs fed diet CFO. The mole/100 mole of propionic acid (HPr) was higher (P < 0.010) in pigs fed diet SBP whereas pigs fed diet CFO had higher (P < 0.010) mole/100 mole of acetic acid (HAc). The proportion of the MWL and MWM fractions in ileal digesta were negatively correlated to HAc (r = -0.52, P = 0.05, and r = -0.62, P = 0.02, respectively). The proportion of MWM in ileal digesta was positively correlated to HPr (r = 0.83; P = 0.001) whereas MWS and HPr were negatively correlated (r = -0.76; P = 0.002). In conclusion, the bacterial degradation of the soluble NSP fraction is selective and MW distribution may explain differences in SCFA production. PMID:23365284

  7. Evaluation of intakes of transuranics influenced by chelation therapy

    SciTech Connect

    LaBone, T.R.

    1994-02-01

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

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

    SciTech Connect

    Banks, M.L.

    1992-12-31

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

  9. Poly-3-hydroxy butyric acid interaction with the transgenic flax fibers: FT-IR and Raman spectra of the composite extracted from a GM flax.

    PubMed

    Wróbel-Kwiatkowska, Magdalena; Zuk, Magdalena; Szopa, Jan; Dymińska, Lucyna; Maczka, Mirosław; Hanuza, Jerzy

    2009-07-15

    The FT-IR and FT-Raman studies have been performed on commercial 3-hydroxy-butyric acid, commercial poly-3-hydroxy butyric acid as well as poly-3-hydroxy butyric acid (PHB) produced by bacteria. The data were compared to those obtained for poly-3-hydroxy butyric acid extracted from natural and genetically modified flax. Genetically modified flax was generated by expression of three bacterial genes coding for synthesis of poly-3-hydroxy butyric acid. Thus transgenic flaxes were enhanced with different amount of the PHB. The discussion of polymer structure and vibrational properties has been done in order to get insight into differences among these materials. The interaction between the cellulose of flax fibers and embedded poly-3-hydroxybutyric acid has been also discussed. The spectroscopic data provide evidences for structural changes in cellulose and in PHB when synthesized in fibers. Based on this data it is suggesting that cellulose and PHB interact by hydrogen and ester bonds. PMID:19328737

  10. Poly-3-hydroxy butyric acid interaction with the transgenic flax fibers: FT-IR and Raman spectra of the composite extracted from a GM flax

    NASA Astrophysics Data System (ADS)

    Wróbel-Kwiatkowska, Magdalena; Żuk, Magdalena; Szopa, Jan; Dymińska, Lucyna; Mączka, Mirosław; Hanuza, Jerzy

    2009-07-01

    The FT-IR and FT-Raman studies have been performed on commercial 3-hydroxy-butyric acid, commercial poly-3-hydroxy butyric acid as well as poly-3-hydroxy butyric acid (PHB) produced by bacteria. The data were compared to those obtained for poly-3-hydroxy butyric acid extracted from natural and genetically modified flax. Genetically modified flax was generated by expression of three bacterial genes coding for synthesis of poly-3-hydroxy butyric acid. Thus transgenic flaxes were enhanced with different amount of the PHB. The discussion of polymer structure and vibrational properties has been done in order to get insight into differences among these materials. The interaction between the cellulose of flax fibers and embedded poly-3-hydroxybutyric acid has been also discussed. The spectroscopic data provide evidences for structural changes in cellulose and in PHB when synthesized in fibers. Based on this data it is suggesting that cellulose and PHB interact by hydrogen and ester bonds.

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

    PubMed Central

    Huang, Saibo; Lin, Huimin; Deng, Shang-gui

    2015-01-01

    The ability of ferrous chelates including hairtail protein hydrolysates to prevent and reduce fatigue was studied in rats. After hydrolysis of hairtail surimi with papain, the hairtail protein hydrolysates (HPH) were separated into three groups by range of relative molecular weight using ultrafiltration membrane separation. Hairtail proteins were then chelated with ferrous ions, and the antioxidant activity, the amino acid composition and chelation rate of the three kinds of ferrous chelates including hairtail protein hydrolysates (Fe-HPH) were determined. Among the three groups, the Fe-HPH chelate showing the best conditions was selected for the anti-fatigue animal experiment. For it, experimental rats were randomly divided into seven groups. Group A was designated as the negative control group given distilled water. Group B, the positive control group, was given glutathione. Groups C, D and E were designated as the Fe-HPH chelate treatment groups and given low, medium, and high doses, respectively. Group F was designated as HPH hydrolysate treatment group, and Group G was designated as FeCl2 treatment group. The different diets were orally administered to rats for 20 days. After that time, rats were subjected to forced swimming training after 1 h of gavage. Rats given Fe-FPH chelate had higher haemoglobin regeneration efficiency (HRE), longer exhaustive swimming time and higher SOD activity. Additionally, Fe-FPH chelate was found to significantly decrease the malondialdehyde content, visibly enhance the GSH-Px activity in liver and reduce blood lactic acid of rats. Fe-HPH chelate revealed an anti-fatigue effect, similar to or better than the positive control substance and superior to HPH or Fe when provided alone. PMID:26633476

  12. Effects of dietary fibers and their mixtures on short chain fatty acids and microbiota in mice guts.

    PubMed

    Peng, Xichun; Li, Shaoting; Luo, Jianming; Wu, Xiyang; Liu, Liu

    2013-06-01

    Dietary fiber (DF) can be broken down into short-chain fatty acids (SCFAs) such as acetic, propionic and n-butyric acid by gut microbiota to obtain energy. Therefore, dietary fibers have effects on the balance of gut microbiota and the production of SCFAs. In the four-week feeding, mice were fed with four dietary fibers, including pectin, resistant starch (RS), fructo-oligosaccharide (FOS) and cellulose. The results showed that the mice body-weight gain was the smallest (7.0 ± 2.3 g) when the mixture of RS-FOS-cellulose was ingested, followed by the mixture of RS-cellulose (7.2 ± 3.5 g) and FOS-cellulose (8.3 ± 2.5 g). Ingestion of the mixture of pectin-FOS-cellulose, RS-FOS and RS-FOS-cellulose can respectively increase the diversity of the gut microbiota with 12, 11 and 11 terminal restriction fragments (TRFs) detected (digested by Hha I). The maximum amount of total SCFAs were produced by the mixture of FOS-cellulose (5.504 ± 0.029 μmol mL(-1)), followed by pectin-FOS-cellulose (3.893 ± 0.024 μmol mL(-1)) and pectin-RS-FOS-cellulose (3.309 ± 0.047 μmol mL(-1)). In conclusion, the addition of DFs (pectin, RS, FOS and cellulose), in single or mixture pattern, can exert different effects. An amount of 10.7% of single DF in the diet cannot be conducive to the balance of gut microbiota after ingestion for a long time, however, it can help with body weight loss like the mixtures of DFs in this study; FOS is a very important component in the mixture of DFs for both the balance of the gut microbiota and the production of SCFAs. PMID:23669739

  13. Bioinspired Polyelectrolyte-Assembled Graphene-Oxide-Coated C18 Composite Solid-Phase Microextraction Fibers for In Vivo Monitoring of Acidic Pharmaceuticals in Fish.

    PubMed

    Qiu, Junlang; Chen, Guosheng; Liu, Shuqin; Zhang, Tianlang; Wu, Jiayi; Wang, Fuxin; Xu, Jianqiao; Liu, Yan; Zhu, Fang; Ouyang, Gangfeng

    2016-06-01

    A novel solid-phase microextraction (SPME) fiber was prepared by gluing poly(diallyldimethylammonium chloride) (PDDA) assembled graphene oxide (GO)-coated C18 composite particles (C18@GO@PDDA) onto a quartz fiber with polyaniline (PANI). The fiber surface coating was sequentially modified with bioinspired polynorepinephrine, which provided a smooth biointerface and makes the coating suitable for in vivo sampling. The novel custom-made coating was used to extract acidic pharmaceuticals, and high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was employed for analysis. The custom-made coating exhibited a much higher extraction efficiency than the previously used commercial polydimethylsiloxane (PDMS) and polyacrylate (PA) coatings. The custom-made coating also possessed satisfactory stability (the relative standard deviations (RSDs) ranged from 1.60% to 10.3% for six sampling-desorption cycles), interfiber reproducibility (the RSDs ranged from 2.61% to 11.5%), and resistance to matrix effects. The custom-made fibers were used to monitor the presence of acid pharmaceuticals in dorsal-epaxial muscle of living fish, and satisfactory sensitivities (limits of detection ranged from 0.13 ng/g to 7.56 ng/g) were achieved. The accuracies were verified by the comparison with liquid extraction. Moreover, the novel fibers were successfully used to monitor the presence of acidic pharmaceuticals in living fish, which demonstrated that the custom-made fibers were feasible for possible long-term in vivo continuous pharmaceutical monitoring. PMID:27189112

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

    PubMed

    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

  15. No difference in fecal levels of bacteria or short chain fatty acids in humans, when consuming fruit juice beverages containing fruit fiber, fruit polyphenols, and their combination.

    PubMed

    Wallace, Alison J; Eady, Sarah L; Hunter, Denise C; Skinner, Margot A; Huffman, Lee; Ansell, Juliet; Blatchford, Paul; Wohlers, Mark; Herath, Thanuja D; Hedderley, Duncan; Rosendale, Douglas; Stoklosinski, Halina; McGhie, Tony; Sun-Waterhouse, Dongxiao; Redman, Claire

    2015-01-01

    This study examined the effect of a Boysenberry beverage (750 mg polyphenols), an apple fiber beverage (7.5 g dietary fiber), and a Boysenberry plus apple fiber beverage (750 mg polyphenols plus 7.5 g dietary fiber) on gut health. Twenty-five individuals completed the study. The study was a placebo-controlled crossover study, where every individual consumed 1 of the 4 treatments in turn. Each treatment phase was 4-week long and was followed by a 2-week washout period. The trial beverages were 350 g taken in 2 doses every day (ie, 175 mL taken twice daily). The hypothesis for the study was that the combination of polyphenols and fiber would have a greater benefit on gut health than the placebo product or the fiber or polyphenols on their own. There were no differences in fecal levels of total bacteria, Bacteroides-Prevotella-Porphyromonas group, Bifidobacteriumspecies, Clostridium perfringens, or Lactobacillus species among any of the treatment groups. Fecal short chain fatty acid concentrations did not vary among treatment groups, although prostaglandin E2 concentrations were higher after consumption of the Boysenberry juice beverage. No significant differences were found in quantitative measures of gut health between the Boysenberry juice beverage, the apple fiber beverage, the Boysenberry juice plus apple fiber beverage, and the placebo beverage. PMID:25530011

  16. Beliefs about chelation among thalassemia patients

    PubMed Central

    2012-01-01

    Background Understanding patients’ views about medication is crucial to maximize adherence. Thalassemia is a congenital blood disorder requiring chronic blood transfusions and daily iron chelation therapy. Methods The Beliefs in Medicine Questionnaire (BMQ) was used to assess beliefs in chelation in thalassemia patients from North America and London in the Thalassemia Longitudinal Cohort (TLC) of the Thalassemia Clinical Research Network (TCRN). Chelation adherence was based on patient report of doses administered out of those prescribed in the last four weeks. Results Of 371 patients (ages 5-58y, mean 24y), 93% were transfused and 92% receiving chelation (26% deferoxamine (DFO; a slow subcutaneous infusion via portable pump), 63% oral, 11% combination). Patients expressed high “necessity” for transfusion (96%), DFO chelation (92%) and oral chelation (89%), with lower “concern” about treatment (48%, 39%, 19% respectively). Concern about oral chelation was significantly lower than that of DFO (p<0.001). Self-reported adherence to chelation was not associated with views about necessity or concerns, but negatively correlated with perceived sensitivity to DFO (Sensitive Soma scale; r=−0.23, p=0.01) and side effects of oral chelation (r=−0.14, p=0.04). High ferritin iron levels, potentially indicating lower adherence, were found in 41% of patients reporting low necessity of oral chelation compared to 24% reporting high necessity (p=0.048). Concerns about treatment were associated with lower quality of life and more symptoms of anxiety and depression. Conclusions Despite their requirement for multimodal therapy, thalassemia patients have positive views about medicine, more so than in other disease populations. Patients may benefit from education about the tolerability of chelation and strategies to effectively cope with side effects, both of which might be beneficial in lowering body iron burden. Clinicaltrials.gov identifier NCT00661804 PMID:23216870

  17. Chelating ligands for nanocrystals' surface functionalization.

    PubMed

    Querner, Claudia; Reiss, Peter; Bleuse, Joël; Pron, Adam

    2004-09-22

    A new family of ligands for the surface functionalization of CdSe nanocrystals is proposed, namely alkyl or aryl derivatives of carbodithioic acids (R-C(S)SH). The main advantages of these new ligands are as follows: they nearly quantitatively exchange the initial surface ligands (TOPO) in very mild conditions; they significantly improve the resistance of nanocrystals against photooxidation because of their ability of strong chelate-type binding to metal atoms; their relatively simple preparation via Grignard intermediates facilitates the development of new bifunctional ligands containing, in addition to the anchoring carbodithioate group, a second function, which enables the grafting of molecules or macromolecules of interest on the nanocrystal surface. To give an example of this approach, we report, for the first time, the grafting of an electroactive oligomer from the polyaniline family-aniline tetramer-on CdSe nanocrystals after their functionalization with 4-formyldithiobenzoic acid. The grafting proceeds via a condensation reaction between the aldehyde group of the ligand and the terminal primary amine group of the tetramer. The resulting organic/inorganic hybrid exhibits complete extinction of the fluorescence of its constituents, indicating efficient charge or energy transfer between the organic and the inorganic semiconductors. PMID:15366904

  18. Fabrication and characterization of the nano-composite of whey protein hydrolysate chelated with calcium.

    PubMed

    Xixi, Cai; Lina, Zhao; Shaoyun, Wang; Pingfan, Rao

    2015-03-01

    The nano-composites of whey protein hydrolysate (WPH) chelated with calcium were fabricated in aqueous solution at 30 °C for 20 min, with the ratio of hydrolysate to calcium 15 : 1 (w/w). UV scanning spectroscopy, fluorescent spectroscopy, Fourier transform infrared spectroscopy, dynamic light scattering and atomic force microscopy were applied to characterize the structure of the WPH-calcium chelate. The nano-composites showed the successful incorporation of calcium into the WPH, indicating the interaction between calcium and WPH. The chelation of calcium ions to WPH caused molecular folding and aggregation which led to the formation of a WPH-calcium chelate of nanoparticle size, and the principal sites of calcium-binding corresponded to the carboxyl groups and carbonyl groups of WPH. The WPH-calcium chelate demonstrated excellent stability and absorbability under both acidic and basic conditions, which was beneficial for calcium absorption in the gastrointestinal tract of the human body. Moreover, the calcium absorption of the WPH-calcium chelate on Caco-2 cells was significantly higher than those of calcium gluconate and CaCl₂ in vitro, suggesting the possible increase in calcium bioavailability. The findings suggest that the WPH-calcium chelate has the potential in making dietary supplements for improving bone health of the human body. PMID:25588126

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

    PubMed

    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

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

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

    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-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. PMID:26878770

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

    PubMed

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

    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-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. PMID:26878770

  3. Covalent attachment of metal chelates to proteins:the stability in vivo and in vitro of the conjugate of albumin with a chelate of 111indium.

    PubMed Central

    Meares, C F; Goodwin, D A; Leung, C S; Girgis, A Y; Silvester, D J; Nunn, A D; Lavender, P J

    1976-01-01

    Human serum albumin has been conjugated to 1-(p-bnezenediazonium)-(ethylenedinitrilo)tetraacetic acid, a powerful chelating agent, and radioactive 111indium ions have been added specifically to the chelating groups. The product, with a specific radioactivity of about 1 mCi/mg of protein, was employed as a radiotracer in scintillation scanning studies with human volunteers. Results show that 48 hr after injection, practically all of the label remains attached to albumin. This is confirmed by electrophoresis of serum proteins; 7 days after injection, 85% of the radioactivity in the serum is still in the albumin fraction. These observations agree with in vitro studies of the labeled albumin in human serum, where loss of the metal ion from the chelating group to the protein transferrin amounts to less than 3% after 1 week and less than 5% after 2 weeks. Measurements of the distribution of label in mice up to 23 days after injection suggest that metabolism of the labeled protein does not lead to binding of indium ions by transferrin. The binding of indium and other metal ions by transferrin has previously posed a major impediment to the use of metal chelates for in vivo diagnostic procedures. Demonstration of the kinetic inertness of the chelate in these experiments suggests the use of related chelates as physical probes of biological systems. Images PMID:825856

  4. Mobility of chelated radionuclides in engineered concrete barriers

    SciTech Connect

    Dicke, C.A.; Smith, R.W.

    1993-12-31

    Concrete is a major component in many low-level radioactive waste (LLW) disposal facilities. The use of concrete is widespread because of its physical and structural properties and because it provides geochemical control on metal and radionuclide releases. Organic compounds are often disposed with radionuclides in LLW disposal facilities. Interactions between radionuclides and chelating agents must be evaluated to estimate mobility of radionuclides in concrete vaults. This paper quantifies the effects of two common organic components [citric acid and ethylenediaminetetraacetic acid (EDTA)] on radionuclide mobility in concrete barriers by using equilibrium geochemical calculations. Equilibrium speciation calculations indicate that some radionuclides are chelated in groundwater (pH 7) but are destabilized in the highly alkaline (pH 13) concrete pore fluids. Radionuclides complexed by by EDTA and citrate are replaced by calcium in the concrete pore fluids. In addition, the citrate nuclide complex reacts to form uncomplexed citrate in concrete pore fluids. The chemical performance of concrete LLW disposal facilities should not be compromised by small amounts of chelating agents disposed with some radionuclides. However, EDTA may form significant nickel and cobalt complexes above the pH important in the long-term service life of concrete barriers.

  5. Biocomposite from polylactic acid and lignocellulosic fibers: structure-property correlations.

    PubMed

    Faludi, G; Dora, G; Renner, K; Móczó, J; Pukánszky, B

    2013-02-15

    PLA biocomposites were prepared using three corn cob fractions and a wood fiber as reference. The composites were characterized by tensile testing, scanning electron microscopy (SEM) and polarization optical microscopy (POM). Micromechanical deformation processes were followed by acoustic emission measurements. The different strength of the components was proved by direct measurements. Two consecutive micromechanical deformation processes were detected in composites containing the heavy fraction of corncob, which were assigned to the fracture of soft and hard particles, respectively. The fracture of soft particles does not result in the failure of the composites that is initiated either by the fracture of hard particles or by matrix cracking. Very large particles debond easily from the matrix resulting in catastrophic failure at very low stresses. At sufficiently large shear stresses large particles break easily during compounding, thus reinforcement depending on interfacial adhesion was practically the same in all composites irrespectively of initial fiber characteristics. PMID:23399218

  6. Measurement of high acidity using a renewable-reagent fiber optic sensor

    SciTech Connect

    Kuhn, K.J.; Dyke, J.T.

    1995-02-01

    The renewable-reagent sensor concept was initially developed to address shortcomings in fiber optic chemical sensors dependent on immobilized, reversible reagents to produce analyte specific responses. The renewable-reagent sensor incorporates semi-selective membranes, analyte specific reagents and remote spectroscopic detection to extract selective responses. While renewable-reagent fiber optic sensor have been demonstrated for a number of chemical sensing applications, the transfer of laboratory prototypes to real world applications require devices which oversample the measurement matrix to differentiate among environmental and analyte specific response components. For example, optical sensor which acquire broadband rather than single wavelength spectroscopic data provide diagnostics regarding the identity of and measurement error associated with matrix interferences. The following describes the fabrication and evaluation of two renewable-reagent fiber optic sensor designs for the measurement of HNO{sub 3} in the 0.1 M to 10.0 M concentration range. Both sensor designs employ an internal pH indicator reagent and broadband visible spectroscopic detection to characterize HNO{sub 3} concentration.

  7. Nanomagnetic chelators for removal of toxic metal ions

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  8. Multidentate terephthalamidate and hydroxypyridonate ligands: towards new orally active chelators.

    PubMed

    Abergel, Rebecca J; Raymond, Kenneth N

    2011-01-01

    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 (59)Fe, (238)Pu, and (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. PMID:21599440

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

    SciTech Connect

    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.

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

    PubMed

    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

  11. Comparison of the antibacterial activity of chelating agents using the agar diffusion method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The agar diffusion assay was used to examine antibacterial activity of 2 metal chelators. Concentrations of 0 to 40 mM of ethylenediaminetetraacetic acid (EDTA) and ethylenediamine-N,N’-disuccinic acid (EDDS) were prepared in 1.0 M potassium hydroxide (KOH). The pH of the solutions was adjusted to 1...

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

    PubMed Central

    Stanton, Gretchen R.; Koz, Gamze

    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 diastereoselective method for the addition of dialkylzincs and (E)-di-, (E)-tri- and (Z)-disubstituted vinylzinc reagents to α-silyloxy ketones using alkyl zinc halide Lewis acids, RZnX, to give chelation-controlled products (dr ≥18:1). The compatibility of organozinc reagents with other functional groups makes this method potentially very useful in complex molecule synthesis. PMID:21534530

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

    PubMed

    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

  14. Improving cytoactive of endothelial cell by introducing fibronectin to the surface of poly L-Lactic acid fiber mats via dopamine.

    PubMed

    Yang, Wufeng; Zhang, Xiazhi; Wu, Keke; Liu, Xiaoyan; Jiao, Yanpeng; Zhou, Changren

    2016-12-01

    A simple but straightforward approach was reported to prepare fiber mats modified with fibronectin (Fn) protein for endothelial cells activity study. Based on the self-polymerization and strong adhesion feature of dopamine, poly L-Lactic acid (PLLA) fibers mat was modified via simply immersing them into dopamine solution for 16h. Subsequently, Fn was immobilized onto the fiber mats surface by the coupling reactive polydopamine (PDA) layer and Fn. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to determine the chemical compositions of fiber mats surface, which confirmed the successful immobilization of PDA and Fn molecules on the fiber surface. Scanning electronic microscopy (SEM) was used to observe the surface morphology changes after modification with PDA and Fn. The data of water contact angle showed that the hydrophilicity of the fiber mats was improved after surface modification. The data of in vitro cell culture proved that the PDA and Fn modified surface significantly enhanced the adhesion, proliferation and cell activity of endothelial cells on the fiber mats. And the release of tumor necrosis factor-α (TNF-α) by endothelial cells on the modified surface was suppressed compared to that on culture plate and PLLA film at 2 and 4days, while the secretion of interleukin-1β (IL-1β) was increased compared to that on culture plate and PLLA film at 2days. PMID:27612725

  15. Overexpression of Arabidopsis thaliana gibberellic acid 20 oxidase (AtGA20ox) gene enhance the vegetative growth and fiber quality in kenaf (Hibiscus cannabinus L.) plants.

    PubMed

    Withanage, Samanthi Priyanka; Hossain, Md Aktar; Kumar M, Sures; Roslan, Hairul Azman B; Abdullah, Mohammad Puad; Napis, Suhaimi B; Shukor, Nor Aini Ab

    2015-06-01

    Kenaf (Hibiscus cannabinus L.; Family: Malvaceae), is multipurpose crop, one of the potential alternatives of natural fiber for biocomposite materials. Longer fiber and higher cellulose contents are required for good quality biocomposite materials. However, average length of kenaf fiber (2.6 mm in bast and 1.28 mm in whole plant) is below the critical length (4 mm) for biocomposite production. Present study describes whether fiber length and cellulose content of kenaf plants could be enhanced by increasing GA biosynthesis in plants by overexpressing Arabidopsis thaliana Gibberellic Acid 20 oxidase (AtGA20ox) gene. AtGA20ox gene with intron was overexpressed in kenaf plants under the control of double CaMV 35S promoter, followed by in planta transformation into V36 and G4 varieties of kenaf. The lines with higher levels of bioactive GA (0.3-1.52 ng g(-1) fresh weight) were further characterized for their morphological and biochemical traits including vegetative and reproductive growth, fiber dimension and chemical composition. Positive impact of increased gibberellins on biochemical composition, fiber dimension and their derivative values were demonstrated in some lines of transgenic kenaf including increased cellulose content (91%), fiber length and quality but it still requires further study to confirm the critical level of this particular bioactive GA in transgenic plants. PMID:26175614

  16. Overexpression of Arabidopsis thaliana gibberellic acid 20 oxidase (AtGA20ox) gene enhance the vegetative growth and fiber quality in kenaf (Hibiscus cannabinus L.) plants

    PubMed Central

    Withanage, Samanthi Priyanka; Hossain, Md Aktar; Kumar M., Sures; Roslan, Hairul Azman B; Abdullah, Mohammad Puad; Napis, Suhaimi B.; Shukor, Nor Aini Ab.

    2015-01-01

    Kenaf (Hibiscus cannabinus L.; Family: Malvaceae), is multipurpose crop, one of the potential alternatives of natural fiber for biocomposite materials. Longer fiber and higher cellulose contents are required for good quality biocomposite materials. However, average length of kenaf fiber (2.6 mm in bast and 1.28 mm in whole plant) is below the critical length (4 mm) for biocomposite production. Present study describes whether fiber length and cellulose content of kenaf plants could be enhanced by increasing GA biosynthesis in plants by overexpressing Arabidopsis thaliana Gibberellic Acid 20 oxidase (AtGA20ox) gene. AtGA20ox gene with intron was overexpressed in kenaf plants under the control of double CaMV 35S promoter, followed by in planta transformation into V36 and G4 varieties of kenaf. The lines with higher levels of bioactive GA (0.3–1.52 ng g−1 fresh weight) were further characterized for their morphological and biochemical traits including vegetative and reproductive growth, fiber dimension and chemical composition. Positive impact of increased gibberellins on biochemical composition, fiber dimension and their derivative values were demonstrated in some lines of transgenic kenaf including increased cellulose content (91%), fiber length and quality but it still requires further study to confirm the critical level of this particular bioactive GA in transgenic plants. PMID:26175614

  17. High surface-area amidoxime-based polymer fibers co-grafted with various acid monomers yielding increased adsorption capacity for the extraction of uranium from seawater.

    PubMed

    Oyola, Yatsandra; Dai, Sheng

    2016-06-01

    Uranium is dissolved in the ocean at a uniform concentration of 3.34 ppb, which translates to approximately 4-5 billion tons of uranium. The development of adsorbents that can extract uranium from seawater has been a long term goal, but the extremely dilute uranium concentration along with the competition of other metal salts (which are at higher concentrations) has hindered the development of an economical adsorption process. Several acid monomers were co-grafted with acrylonitrile (AN) to help increase the hydrophilicity of the adsorbent to improve access to the metal adsorption sites. Grafting various acid monomers on PE fibers was found to significantly affect the uranium adsorption in simulated seawater in the following order: acrylic acid (AA) < vinyl sulfonic acid (VSA) < methacrylic acid (MAA) < itaconic acid (ITA) < vinyl phosphonic acid (VPA). Interestingly, the uranium adsorption capacity significantly increased when Mohr's salt was added with acrylic acid, most likely due to the reduction of co-polymerization of the monomers. When testing under more realistic conditions, the acid-grafted PE fiber adsorbents were exposed to natural seawater (more dilute uranium), the uranium adsorption capacity increased in the following order: MAA < AA (Mohr's salt) < VSA < ITA (Mohr's salt) < ITA < VPA, which agreed well with the simulated seawater results. Characterization of the adsorbents indicated that the increase in uranium adsorption capacity with each acid monomer was related to higher grafting of AN and therefore a higher conversion to amidoxime (AO). PMID:27145863

  18. Lactic acid fermentation of germinated barley fiber and proliferative function of colonic epithelial cells in loperamide-induced rats.

    PubMed

    Jeon, Jeong Ryae; Choi, Joon Hyuk

    2010-08-01

    To develop a functional food from the dietary fiber fraction of germinated barley (Hordeum vulgare L.) (GBF), lactic acid fermentation was attempted using Lactobacillus acidophilus, Streptococcus thermophilus, and Bifidobacterium bifidus. The quality characteristics of the lactic acid-fermented product and its effect on gastrointestinal function in an animal model were examined. The anaerobic fermentation of 1% and 2% GBF yielded lactic acid bacteria at 8.9 +/- 1.0 x 10(8) and 1.6 +/- 0.2 x 10(9) colony-forming units/mL, and it was considered acceptable for consumption by sensory assessment. To determine the effect on gastrointestinal function, Sprague-Dawley rats were fed with three types of diets: a normal chow diet and chow diets supplemented with 10% lactic acid bacteria or a yogurt fermented with 2% GBF (GBFY). The rats fed GBFY for 6 weeks gained less body weight, excreted more fecal mass, and had improved gastrointestinal transit as examined with barium sulfate. The effect of GBFY on colonic epithelial proliferation was investigated through loperamide (LPM)-induced constipation in rats. The rats fed with GBFY for 6 weeks were intraperitoneally administered LPM twice daily for 7 days. GBFY supplementation decreased fecal excretion and moisture content in feces and depleted goblet cells as observed by hematoxylin and eosin stain. However, the rats supplemented with GBFY prior to the LPM administration had enhanced bowel movement, mucin secretion, and production of short-chain fatty acids compared with values for the LPM-alone group. Immunohistochemistry revealed that the GBFY supplement increased the numbers of nuclei stained positively for Ki-67 and extended from the base to the middle zone of crypts. These results indicate that GBFY alleviates constipation via the proliferation of the colonic crypts in LPM-administered rats. PMID:20673062

  19. Comparative effects of chelating drugs on trace metal and biochemical alterations in the rat

    SciTech Connect

    Misra, M.; Athar, M.; Hasan, S.K.; Srivastava, R.C.

    1988-08-01

    Chelation therapy is the most successful modality for the management of heavy metal poisoning. The success of these drugs stem from their multidentate polyfunctional chelating behavior. The therapeutic mechanism for chelating drugs involves their interaction with toxic metals leading to their rapid excretion from the body. However, because of their indiscriminate affinity for various metal ions, the potential interactions between these drugs and endogenous trace metals is of concern. It was, therefore, of importance to define new chelating drugs which in addition to being effective as an antidote in metal poisoning may possess low undesirable toxicity. In the present communication the authors compare the acute effect of Cyclam with those of other conventional chelating drugs namely, triethylenetetramine (TETA), reduced glutathione (GSH), ethylenediamine tetraacetic acid (EDTA), cyclohexanediamine tetraacetic acid (CDTA), diethylene triamine pentaacetic acid (DTPA) and hydroxyethylenediamine triacetic acid (HEDTA) on (i) serum levels of Cu, Zn, lactate dehydrogenase (LDH), glutamyloxaloacetic transaminase (GOT) and ceruloplasmin (CP); (ii) hepatic and renal levels of Cu, Mn, Zn and Fe and (iii) hepatic and renal levels of GSH, glutathione-S-transferase (GST) and phosphoglucomutase (PGM) at various time intervals (16, 24 and 72 hrs) after their administration to rats.

  20. Phytic acid, in vitro protein digestibility, dietary fiber, and minerals of pulses as influenced by processing methods.

    PubMed

    Chitra, U; Singh, U; Rao, P V

    1996-06-01

    The objective of this project was to determine the effect of various types of processing on selected nutrition related parameters of commonly consumed Indian pulses and soybean. Germination reduced the phytic acid content of chickpea and pigeonpea seeds by over 60%, and that of mung bean, urd bean, and soybean by about 40%. Fermentation reduced phytic acid contents by 26-39% in all these legumes with the exception of pigeonpea in which it was reduced by more than 50%. Autoclaving and roasting were more effective in reducing phytic acid in chickpea and pigeonpea than in urd bean, mung bean, and soybean. Germination and fermentation greatly increased the in vitro protein digestibility (IVPD). IVPD was only slightly increased by roasting and autoclaving of all legumes. Germination and fermentation also remarkably decreased the total dietary fiber (TDF) in all legumes. Autoclaving and roasting resulted in slight increases in TDF values. All the processing treatments had little effect on calcium, magnesium and iron contents. PMID:8983057

  1. Effect of chelating agents and solubility of cadmium complexes on uptake from soil by Brassica juncea.

    PubMed

    Van Engelen, Debra L; Sharpe-Pedler, Rachel C; Moorhead, Kevin K

    2007-06-01

    Brassica juncea, or Indian mustard, was grown in soil artificially contaminated with either a soluble salt, CdCl(2), at 186mg Cdkg(-1), or alternately an insoluble, basic salt, CdCO(3), at 90mg Cdkg(-1). These experiments study the range of Cd uptake by Indian mustard from conditions of very high Cd concentration in a soluble form to the other extreme with an insoluble Cd salt. After plants were established, four different chelating agents were applied. Chelating agents increased plant uptake of Cd from the CdCl(2) soil but did not significantly increase plant uptake of Cd from the CdCO(3) contaminated soil. Addition of ethylenediaminetetraacetic acid (EDTA) increased the plant concentration of Cd by almost 10-fold in soils contaminated with CdCl(2), with a concentration of 1283mg Cdkg(-1) in the dried EDTA-treated plants over a concentration of 131mg Cdkg(-1) in plants without added chelate. However, EDTA increased the aqueous solubility of Cd by 36 times over the soil matrix without added chelator, and thereby, increased the possibility of leaching. Other chelators used in both experiments were ethylenebis(oxyethylenenitrilo)tetraacetic acid, trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid, and diethylenetriaminepentaacetic acid (DTPA) increasing Cd in plants to 1240, 962, and 437mg Cdkg(-1), respectively. The other chelating agents increased the solubility of Cd in the leachate but not to the extent of EDTA. Comparing all chelating agents studied, DTPA increased plant uptake in terms of Cd in dried plant concentration most relative to the solubility of complexed Cd in runoff water. PMID:17320931

  2. The effect of dietary fiber from wheat processing streams on the formation of carboxylic acids and microbiota in the hindgut of rats.

    PubMed

    Haskå, Lina; Andersson, Roger; Nyman, Margareta

    2011-04-13

    Colonic fermentation of dietary fiber produces carboxylic acids and may stimulate the growth of beneficial bacteria. This study investigated how byproducts of wheat processing (distillers' grains and two fractions from the wet fractionation to starch and gluten, one of which was treated with xylanase) affect the composition of the cecal microbiota and the formation of carboxylic acids in rats. Differences were mostly found between diets based on supernatants and pellets, rather than between fiber sources. Cecal pools and levels of most carboxylic acids in portal blood were higher for rats fed the supernatant diets, while cecal pH and ratios of acetic to propionic acid in portal blood were lower. The diet based on supernatant from distillers' grains gave the highest level of bifidobacteria. Molecular weight and solubility are easier to modify with technological processes, which provides an opportunity to optimize these properties in the development of health products. PMID:21391670

  3. The formation of short-chain fatty acids is positively associated with the blood lipid-lowering effect of lupin kernel fiber in moderately hypercholesterolemic adults.

    PubMed

    Fechner, Anita; Kiehntopf, Michael; Jahreis, Gerhard

    2014-05-01

    Lupin kernel fiber beneficially modifies blood lipids because of its bile acid-binding capacity. The aim of this study was to evaluate the preventive effects of a lupin kernel fiber preparation on cardiovascular diseases and to clarify possible mechanisms. In a randomized, double-blind, controlled crossover trial, 60 moderately hypercholesterolemic adults (plasma total cholesterol: >5.2 mmol/L) passed 3 intervention periods in different orders with a 2-wk washout phase between each. Participants consumed either a high-fiber diet containing 25-g/d lupin kernel fiber (LF) or citrus fiber (CF), or a low-fiber control diet (CD) for 4 wk each. Anthropometric, plasma, and fecal variables were assessed at baseline and after the interventions. Contrary to the CF period, total (9%) and LDL (12%) cholesterol as well as triacylglycerols (10%) were lower after the LF period when compared with the CD period [P ≤ 0.02, adjusted for baseline, age, gender, and body mass index (BMI)]. HDL cholesterol remained unchanged. Moreover, the LF period reduced high-sensitivity C-reactive protein (P = 0.02) and systolic blood pressure (P = 0.01) when compared with baseline. Bile acid binding could not be shown because the excretion of total bile acids remained constant after the high-fiber diets. However, the LF period resulted in an enhanced formation of the main short-chain fatty acids in comparison with the CD period. During the CF period, only acetate increased significantly. Both high-fiber diets led to higher satiety and modified nutritional behavior, resulting in significantly lower body weight, BMI, and waist circumference compared with the CD period. The blood lipid-lowering effects of LF are apparently not a result of bile acid binding. Rather, we hypothesize for the first time, to our knowledge, that the blood lipid-lowering effects of LF may be mainly attributed to the formation of short-chain fatty acids, specifically propionate and acetate. This trial was registered at

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

    PubMed

    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

  5. Natural chelating agents for radionuclide decorporation

    DOEpatents

    Premuzic, E.T.

    1985-06-11

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

  6. Effects of dietary fiber on cecal short-chain fatty acid and cecal microbiota of broiler and laying-hen chicks.

    PubMed

    Walugembe, M; Hsieh, J C F; Koszewski, N J; Lamont, S J; Persia, M E; Rothschild, M F

    2015-10-01

    This experiment was conducted to evaluate the effects of feeding dietary fiber on cecal short-chain fatty acid (SCFA) concentration and cecal microbiota of broiler and laying-hen chicks. The lower fiber diet was based on corn-soybean meal (SBM) and the higher fiber diet was formulated using corn-SBM-dried distillers grains with solubles (DDGS) and wheat bran to contain 60.0 g/kg of both DDGS and wheat bran from 1 to 12 d and 80.0 g/kg of both DDGS and wheat bran from 13 to 21 d. Diets were formulated to meet or exceed NRC nutrient requirements. Broiler and laying-hen chicks were randomly assigned to the high and low fiber diets with 11 replicates of 8 chicks for each of the 4 treatments. One cecum from 3 chicks was collected from each replicate: one cecum underwent SCFA concentration analysis, one underwent bacterial DNA isolation for terminal restriction fragment length polymorphism (TRFLP), and the third cecum was used for metagenomics analyses. There were interactions between bird line and dietary fiber for acetic acid (P = 0.04) and total SCFA (P = 0.04) concentration. There was higher concentration of acetic acid (P = 0.02) and propionic acid (P < 0.01) in broiler chicks compared to laying-hen chicks. TRFLP analysis showed that cecal microbiota varied due to diet (P = 0.02) and chicken line (P = 0.03). Metagenomics analyses identified differences in the relative abundance of Helicobacter pullorum and Megamonas hypermegale and the genera Enterobacteriaceae, Campylobacter, Faecalibacterium, and Bacteroides in different treatment groups. These results provide insights into the effect of dietary fiber on SCFA concentration and modulation of cecal microbiota in broiler and laying-hen chicks. PMID:26316341

  7. Production of fermentable sugars from corn fiber using soaking in aqueous ammonia (saa) pretreatment and fermentation to succinic acid by Escherichia coli afp184

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conversion of corn fiber (CF), a by-product from the corn-to-ethanol conversion process, into fermentable sugar and succinic acid was investigated using soaking in aqueous ammonia (SAA) pretreatment followed by biological conversions including enzymatic hydrolysis and fermentation using genetically ...

  8. Mercury removal in utility wet scrubber using a chelating agent

    DOEpatents

    Amrhein, Gerald T.

    2001-01-01

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

  9. On hafnium chelation by EDTA and DTPA for TDPAC experiments

    NASA Astrophysics Data System (ADS)

    Chain, Cecilia Y.; Pasquevich, A. F.

    2010-04-01

    Polyaminocarboxilate chelating agents, like ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA), form stable complexes with many heavy metals ions and are of spread use in the industrial and biomedical field. In this paper, Time Differential Perturbed Angular Correlations (TDPAC) spectroscopy has been used to investigate the formation of Hf-complexes prepared from 181Hf-HfF4 and polyaminocarboxylic acids, by taking into account the possible formation of inorganic compounds. The obtained wet precipitates were measured at room temperature. Different behaviors were observed depending on the ratio fluorine/sodium atoms present in the sample. The obtaining of sodium heptafluorohafnate Na3HfF7 was verified when the ratio F/Na was approximately 1.5 and tridecafluorodihafnate Na5Hf2F13 appeared for relations between 3 and 4. No evidence of hafnium complexation by the polyaminocarboxilic acids was observed.

  10. Effect of metal chelators on excretion and tissue levels of essential trace elements

    SciTech Connect

    Tandon, S.K.; Jain, V.K.; Mathur, A.K.

    1984-10-01

    The influence of one, three, and six doses of ethylenediaminetetraacetic acid (EDTA) diethylenetriaminepentaacetic acid (DTPA), and triethylenetetramine (TETA) on the urinary excretion of Ca, Cu, Fe, and Zn, and on their levels in liver, kidneys, heart, and serum in rats, was investigated to ascertain their suitability in amelioration of metal intoxication. While excretion of all the essential trace metals examined was enhanced significantly, the tissue and serum levels of some of them either increased or decreased after administration of the chelators. The results suggest depletion of some of the endogenous trace metals from the body and their intertissue redistribution following treatment with these chelating agents.

  11. Bifunctional Chelates Optimized for Molecular MRI

    PubMed Central

    2015-01-01

    Important requirements for exogenous dyes or contrast agents in magnetic resonance imaging (MRI) include an effective concentration of paramagnetic or superparamagnetic ions at the target to be imaged. We report the concise synthesis and characterization of several new enantiopure bifunctional derivatives of (α1R,α4R,α7R,α10R)-α1,α4,α7,α10-tetramethyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTMA) (and their 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) analogues as controls) that can be covalently attached to a contrast agent delivery system using either click or peptide coupling chemistry. Gd complexes of these derivatives can be attached to delivery systems while maintaining optimal water residence time for increased molecular imaging sensitivity. Long chain biotin (LC-biotin) derivatives of the Eu(III) and Gd(III) chelates associated with avidin are used to demonstrate higher efficiencies. Variable-temperature relaxometry, 17O NMR, and nuclear magnetic resonance dispersion (NMRD) spectroscopy used on the complexes and biotin–avidin adducts measure the influence of water residence time and rotational correlation time on constrained and unconstrained systems. The Gd(III)-DOTMA derivative has a shorter water residence time than the Gd(III)-DOTA derivative. Compared to the constrained Gd(III)-DOTA derivatives, the rotationally constrained Gd(III)-DOTMA derivative has ∼40% higher relaxivity at 37 °C, which could increase its sensitivity as an MRI agent as well as reduce the dose of the targeting agent. PMID:24933389

  12. Heavy metal bioavailability and chelate mobilization efficiency in an assisted phytoextraction process.

    PubMed

    Cao, Alessia; Cappai, Giovanna; Carucci, Alessandra; Lai, Tiziana

    2008-04-01

    The heavy metal bioavailable fraction of a soil is a core parameter to verify the potential risks of contaminant exposure to organisms or plants. The purpose of the present work is to identify the bioavailable metal fraction in soils treated with chelates. This fraction was evaluated directly by analyzing metal concentrations in soil solution and indirectly using sequential extraction procedures. The metal bioavailable fraction was compared with metal accumulated in plant leaves, grown in both untreated and chelate-treated reactors. In order to verify the effect of the readily and slowly biodegradable chelates [S,S]-ethylenediaminedisuccinic acid (EDDS), methylglycine diacetic acid (MGDA), and ethylenediaminetetraacetic acid (EDTA) on metal speciation in soils, a simulation of chelate treatment was made and metal concentrations in different soil compartments before and after the simulation were compared. Lead concentration in the soil solution was positively correlated with metal concentration in the test plants. The soluble fraction showed the best correlation with metal concentration in soil solution. The simulation of the chelate treatment demonstrated that EDTA and EDDS were able to extract part of the organic- and sulfide-bound fraction, which are less available to plants. PMID:18253843

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

    NASA Astrophysics Data System (ADS)

    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

  14. Nanoscale-supported heteropoly acid as a new fiber coating for solid-phase microextraction coupled with gas chromatography-mass spectrometry.

    PubMed

    Abolghasemi, Mir Mahdi; Hassani, Sona; Rafiee, Ezzat; Yousefi, Vahid

    2015-02-13

    In the present study, 12-tungstophosphoric (PW) acid as heteropoly acid, supported on silica-coated γ-Fe2O3 nanoparticles (NPs), was used as a new fiber coating for solid-phase microextraction (SPME). The γ-Fe2O3@SiO2-PW nanocomposite with high surface area was synthesized and characterized by SEM and FT-IR. The prepared nanocomposite was immobilized on a stainless steel wire for fabrication of the SPME fiber. The fiber was evaluated for the extraction of some phenolic compounds (PCs) from water sample in combination with gas chromatography-mass spectrometry (GC-MS). A one-at-a-time optimization strategy was applied for optimizing the important extraction parameters such as extraction temperature, extraction time, ionic strength, stirring rate, pH, and desorption temperature and time. In optimum conditions, the repeatability for one fiber (n=3), expressed as relative standard deviation (R.S.D. %), was between 4.8% and 9.6% for the test compounds. The detection limits for the studied compounds were between 0.004 and 0.05 pg mL(-1). The developed method offers the advantage of being simple to use, with shorter analysis time, lower cost of equipment, thermal stability of fiber and high relative recovery in comparison to conventional methods of analysis. PMID:25618361

  15. Clickable bifunctional radiometal chelates for peptide labeling†

    PubMed Central

    Lebedev, Artem Y.; Holland, Jason P.; Lewis, Jason S.

    2016-01-01

    Novel synthetic methods for producing an array of chelates for use in “click”-radiolabeling of peptides are described, and their reactivity with regards to subsequent conjugation and radiolabeling is discussed. PMID:20177623

  16. [Analysis of alkaline CuO degradation products of acid detergent fiber from tobacco leaves by using liquid chromatography].

    PubMed

    Hao, Weiqiang; Wang, Leijun; Wu, Shun; Yue, Bangyi; Chen, Qiang; Zhang, Peipei

    2015-07-01

    The acid detergent fiber (ADF) from tobacco leaves was obtained by treating the sample with petroleum ether-ethanol (6:4, v/v), 30 g/L sodium dodecylsulfate and 0.5 mol/L sulphuric acid containing 20 g/L hexadecyl trimethyl ammonium bromide successively. The ADF was degraded by the alkaline CuO oxidation procedure. In this work, six samples of ADF degradation products from tobacco leaves were prepared. The samples were analyzed by using gradient liquid chromatography (LC) where an Ultimate XB C18 column was used as stationary phase, with a mixture of methanol and water as mobile phase, at a column temperature of 35 °C and a flow rate of 0.8 mL/min. Dual wavelengths of 280 nm and 320 nm were chosen for the detection. It was found that there were four characteristic peaks for the ADF degradation products. By taking these peaks as research object, the optimum time for the degradation was found to be 5 h and the sample solution could be kept stable within 7 days. The established method may provide a new approach for the studies of the differences between lignin composition in different tobacco leaves and the relationship between lignin content and the smoking quality of tobacco leaves. PMID:26672209

  17. Carbon fiber cloth supported Au nano-textile fabrics as an efficient catalyst for hydrogen peroxide electroreduction in acid medium

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Cheng, Kui; Wang, Guiling; Cao, Dianxue

    2015-09-01

    The size-controlled hierarchical textile-like Au nanostructures supported carbon fiber cloth (Au NTs/CFC) is successfully fabricated through a simple low-cost electrochemical route. The electrodes are characterised by scanning electron microscopy equipped with an energy dispersive X-ray spectrometer, transmission electron microscopy and X-ray diffractometer. Without any conducting carbons and polymer binders, the 3D electrode with unique structure is directly used as the electrocatalyst for H2O2 reduction in acid solution and the catalytic performance is evaluated by voltammetry and chronoamperometry. The Au NTs/CFC electrode exhibits much higher catalytic activity and remarkably improved utilization of Au than Au nanoparticles (Au NPs/CFC) prepared by the same method owing to its unique structure. In the solution of 3.0 mol L-1 H2SO4 + 0.1 mol L-1 H2O2, with the reduction potential of 0 V, the current of -0.72 A cm-2 mg-1 can be obtained on Au NTs/CFC electrode and only a current of -0.09 A cm-2 mg-1 can be achieved on Au NPs/CFC electrode. All these results reveal that the novel Au NTs/CFC electrode exhibits excellent catalytic performance and superior stability for H2O2 electroreduction in acid medium, benefitting from the unique 3D structure which can ensure high utilization of catalyst.

  18. Fabrication of novel poly(lactic acid)/amorphous magnesium phosphate bionanocomposite fibers for tissue engineering applications via electrospinning.

    PubMed

    Zhou, Huan; Nabiyouni, Maryam; Lin, Boren; Bhaduri, Sarit B

    2013-05-01

    Fibrous bionanocomposites consisting of amorphous magnesium phosphate (AMP) nanospheres and polylactic acid (PLA) were fabricated by electrospinning. There are two important signatures of this paper. First, AMP, as an alternative to well-known calcium phosphate (CaP) materials, is added to PLA as the second phase. To the best of our knowledge, it is the first attempt to fabricate magnesium phosphate (MgP)/biopolymer composite. This is made possible by our previously reported research on the successful synthesis of AMP nanospheres via microwave processing. Second, the sustained release of magnesium and phosphate ions from PLA matrix can stimulate a series of cell responses. The structure of the composites and their bone-like apatite-forming abilities in simulated body fluid (SBF) were examined. Additionally, the effects on the proliferation and differentiation of preosteoblast cells were evaluated by performing in vitro cell culture and monitoring markers such as Osteocalcin (OCN), Osteopontin (OPN), Alkaline phosphatase (ALP) and Collagen type-I (Col I) using real-time polymerase chain reaction (PCR). For better dispersion of AMP in the fibers, a surfactant, 12-hydroxysteric acid (HSA), as previously reported in the literature, was used. However, HSA significantly inhibited the proliferation and differentiation of preosteoblast cells, indicating the potential risk in using HSA in the combination of AMP or MgP in tissue engineering applications. PMID:23498262

  19. Quantitative analysis of mechanical and electrostatic properties of poly(lactic) acid fibers and poly(lactic) acid—carbon nanotube composites using atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Iqbal, Qais; Bernstein, Peter; Zhu, Yazhe; Rahamim, Joseph; Cebe, Peggy; Staii, Cristian

    2015-03-01

    We use atomic force microscopy (AFM) to perform a systematic quantitative characterization of the elastic modulus and dielectric constant of poly(L-lactic acid) electrospun nanofibers (PLLA), as well as composites of PLLA fibers with 1.0 wt% embedded multiwall carbon nanotubes (MWCNTs-PLLA). The elastic moduli are measured in the fiber skin region via AFM nanoindentation, and the dielectric constants are determined by measuring the phase shifts obtained via electrostatic force microscopy (EFM). We find that the average value for the elastic modulus for PLLA fibers is (9.8 ± 0.9) GPa, which is a factor of 2 larger than the measured average elastic modulus for MWCNT-PLLA composites (4.1 ± 0.7) GPa. We also use EFM to measure dielectric constants for both types of fibers. These measurements show that the dielectric constants of the MWCNT-PLLA fibers are significantly larger than the corresponding values obtained for PLLA fiber. This result is consistent with the higher polarizability of the MWCNT-PLLA composites. The measurement methods presented are general, and can be applied to determine the mechanical and electrical properties of other polymers and polymer nanocomposites.

  20. Influence of the addition of β-TCP on the morphology, thermal properties and cell viability of poly (lactic acid) fibers obtained by electrospinning.

    PubMed

    Siqueira, L; Passador, F R; Costa, M M; Lobo, A O; Sousa, E

    2015-01-01

    Electrospinning is a simple and low-cost way to fabricate fibers. Among the various polymers used in electrospinning process, the poly (lactic acid) (PLA) stands out due to its excellent biodegradability and biocompatibility. Calcium phosphate ceramics has been recognized as an attractive biomaterial because their chemical composition is similar to the mineral component of the hard tissue in the body. Furthermore, they are bioactive and osteoinductive and some are even quite biodegradable. The beta-tricalcium phosphate (β-TCP) particles were synthesized by solid state reaction. Different contents of β-TCP particles were incorporated in polymer matrices to form fibers of PLA/β-TCP composites by electrospinning aiming a possible application as a scaffold for tissue engineering. The fibers were characterized by scanning electron microscopy (SEM), infrared (FTIR), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The average diameter of the fibers varied in the range of 260-519.6 ± 50 nm. The presence of β-TCP particles promoted changes on thermal properties of the fibers. The composite with 8 wt-% of β-TCP showed a low degree of crystallinity and can be used for application in tissue engineering. The cell viability was analyzed by reduction of the methyl tetrazolium salt by the pyruvate dehydrogenase enzymatic complex present in the matrix of mitochondria (MTT test). All PLA fiber groups, with different contents of β-TCP, showed cytocompatibility ability with non-cytotoxicity effect and bioactive properties using SBF assay. PMID:25953550

  1. Effect of dietary physically effective fiber on ruminal fermentation and the fatty acid profile of milk in dairy goats.

    PubMed

    Li, Fei; Li, Zongjun; Li, Shengxiang; Ferguson, James D; Cao, Yangchun; Yao, Junhu; Sun, Feifei; Wang, Xiao; Yang, Ting

    2014-01-01

    The objective of this experiment was to characterize the relationship among rumen fermentation variables, milk fatty acid profile, and dietary physically effective neutral detergent fiber (peNDF) content in a study that controlled for the potential confounding effects of dissimilar dry matter intake among treatments. Ten multiparous Xinong Saanen dairy goats were divided into 2 groups with 2 ruminally cannulated goats per group. Goats in each group were assigned to 1 of 2 dietary treatments (high and low peNDF) according to a 2×2 crossover design with 2 periods. The peNDF content of alfalfa hay (proportion of neutral detergent fiber retained on an 8.0-mm screen) was 42.1% for the high-peNDF and 14.5% for the low-peNDF group. To ensure similar dry matter intake, each morning the amount of alfalfa hay consumed on the prior day by the high-peNDF group was determined (amount offered minus morning refusals), and this was the amount of hay offered to the low-peNDF group that day. Each adaptation period consisted of 21d, followed by a 9-d sampling period. Dry matter intake and milk production and composition were similar between treatments. Milk energy efficiency increased with low dietary peNDF. Duration of pH below 5.60 was longer for goats fed the low-peNDF ration compared with the high-peNDF ration (4.08 vs. 0.41h/d); however, mean rumen pH (6.05 vs. 6.13) was not different between treatments. Reducing dietary peNDF increased rumen total volatile fatty acids (114.6 vs. 95.1mM) and decreased chewing time (404 vs. 673min/d), but did not affect the ratios of acetate, propionate, and butyrate. The relative abundance of Fibrobacter succinogenes and Ruminococcus flavefaciens increased with reduced dietary peNDF, but Ruminococcus albus proportions were not influenced by treatment. Reducing dietary peNDF decreased the proportion of iso C14:0, iso C15:0, and trans-11 C18:1 in milk fat, whereas the iso C17:0 and trans-10 C18:1 increased. This study demonstrated that low

  2. Mathematical modeling of the effects of aerobic and anaerobic chelate bioegradation on actinide speciation.

    SciTech Connect

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

    1998-03-19

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    PubMed

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

    2015-04-01

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

  5. Biodegradability of injection molded bioplastics containing polylactic acid and poultry feather fiber

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biodegradability of three types of bioplastic pots was evaluated by measuring carbon dioxide (CO2) produced from lab-scale compost reactors containing mixtures of pot fragments and compost inoculum held at 58 C for 60 days. Biodegradability of pot type A (composed of 100% polylactic acid (PLA)) was...

  6. Iron-chelating activity of chickpea protein hydrolysate peptides.

    PubMed

    Torres-Fuentes, Cristina; Alaiz, Manuel; Vioque, Javier

    2012-10-01

    Chickpea-chelating peptides were purified and analysed for their iron-chelating activity. These peptides were purified after affinity and gel filtration chromatography from a chickpea protein hydrolysate produced with pepsin and pancreatin. Iron-chelating activity was higher in purified peptide fractions than in the original hydrolysate. Histidine contents were positively correlated with the iron-chelating activity. Hence fractions with histidine contents above 20% showed the highest chelating activity. These results show that iron-chelating peptides are generated after chickpea protein hydrolysis with pepsin plus pancreatin. These peptides, through metal chelation, may increase iron solubility and bioavailability and improve iron absorption. PMID:25005984

  7. Separation of silver nanoparticles by hollow fiber flow field-flow fractionation: Addition of tannic acid into carrier liquid as a modifier.

    PubMed

    Saenmuangchin, Rattaporn; Mettakoonpitak, Jaruwan; Shiowatana, Juwadee; Siripinyanond, Atitaya

    2015-10-01

    A homemade hollow fiber flow-field fractionation (Hf-FlFFF) coupled with inductively coupled plasma mass spectrometry (ICP-MS) was set-up for silver nanoparticles (AgNPs) separation by using polysulfone hollow fiber membrane (30,000 MW cutoff) as a separation channel. Tannic acid and citrate stabilized AgNPs were synthesized and introduced into Hf-FlFFF. The effects of carrier liquid and stabilizing agent on retention behavior of AgNPs were investigated. Different elution behaviors were observed as follows: with 0.02% (w/v) FL-70, all of AgNPs were eluted from Hf-FlFFF but differences in retention behaviors were observed for AgNPs with tannic acid and citrate stabilizing agents; and with 30mM TRIS buffer, only tannic acid stabilized AgNPs were eluted from Hf-FlFFF, whereas citrate stabilized AgNPs were not eluted. In this work, tannic acid addition into carrier liquid was proposed to modify the surface of AgNPs and the surface of the membrane, and thereby adjusting the retention behaviors of AgNPs. Various concentrations of tannic acid were added into FL-70 and TRIS buffer. With the use of 0.1mM tannic acid in 30mM TRIS buffer as the carrier liquid, retention behaviors of both tannic acid stabilized- and citrate stabilized-AgNPs were similar and with similar fractionation recovery. PMID:26341593

  8. Effects of chelators on chromium and nickel uptake by Brassica juncea on serpentine-mine tailings for phytoextraction.

    PubMed

    Hsiao, Kai-Hsun; Kao, Po-Hsu; Hseu, Zeng-Yei

    2007-09-01

    This study compares the effect of synthetic aminopolycarboxylic acids ethylenediamine tetraacetate (EDTA) and diethylenetriamine pentaacetate (DTPA) with natural low-molecular-weight organic acids (LMWOAs) oxalic acid and citric acid as chelators for enhancing phytoextraction of Cr and Ni by Brassica juncea on serpentine-mine tailings. Chelator treatments were applied at doses of 0.05 and 0.10 mmolkg(-1) dry soils after seedlings were grown in pots for 56 days. Experimental results indicate that EDTA and DTPA were the most efficient chelators of increasing the levels of Cr and Ni in the soil solutions over time. Additionally, the reduction of plant shoot biomass caused by the two synthetic chelators exceeds that caused by the LMWOAs. The total uptake (mass removal from soil) of metals by plants was enhanced via the chelators. Experimental results supported the use of B. juncea for Cr and Ni phytoremediation: B. juncea improved the removal of Cr and Ni from serpentine-mine tailings. However, low plant biomass did not assist phytoextraction by using EDTA and DTPA, both of which carry environmental risk. Therefore, adding LMWOAs during phytoremediation can provide an environmentally compatible alternative, which may decrease the use of synthetic chelators. PMID:17391842

  9. [Chelate-induced phytoextraction of copper contaminated upland red soil].

    PubMed

    Wu, L; Luo, Y; Huang, H

    2001-06-01

    A copper spiked red soil was used in pot experiment to study the effects of EDTA and low molecule weight organic acids on Cu speciation in soil, and Cu uptake by Brassica juncea. The results showed that the mobility of Cu in soil was improved obviously when EDTA was added at the vigorous growth stage. Both water-extractable and exchangeable Cu concentration increased significantly following EDTA addition. Citric acid and malic acid only had an effect on water-extractable Cu, and no effect on Cu uptake by the plant. EDTA significantly increased the concentration of Cu in plant leaves and roots, and the Cu uptake by Brassica juncea. All of these indicated the chelate-induced phytoextraction. PMID:11758431

  10. Ultrasound-triggered dual-drug release from poly(lactic-co-glycolic acid)/mesoporous silica nanoparticles electrospun composite fibers

    PubMed Central

    Song, Botao; Wu, Chengtie; Chang, Jiang

    2015-01-01

    The aim of this study was to achieve on-demand controlled drug release from the dual-drug-loaded poly(lactic-co-glycolic acid)/mesoporous silica nanoparticles electrospun composite fibers by the application of ultrasound irradiation. Two drugs were loaded in different part of the composite fibrous materials, and it was found that ultrasound as an external stimulus was able to control release of drugs due to both its thermal effect and non-thermal effect. With the selective irradiation of ultrasound, the drug carrier enabled to realize controlled release, and because of different location in fibers and sensitivity of two different kinds of drugs to ultrasound irradiation, the release rate of two drugs was different. These results indicated that ultrasound irradiation was a facile method to realize the on-demand controlled release of two drugs from the electrospun fibers. PMID:26816645

  11. Leaching heavy metals in municipal solid waste incinerator fly ash with chelator/biosurfactant mixed solution.

    PubMed

    Xu, Ying; Chen, Yu

    2015-07-01

    The chelator [S,S]-ethylene diamine disuccinic acid, citric acid, and biosurfactant saponin are selected as leaching agents. In this study, the leaching effect of saponin mixed with either ethylene diamine disuccinic acid or citric acid on the levels of copper, zinc, lead, and cadmium in municipal solid waste incinerator fly ash is investigated. Results indicate that saponin separately mixed with ethylene diamine disuccinic acid and citric acid exhibits a synergistic solubilisation effect on copper, zinc, lead, and cadmium leaching from fly ash. However, saponin and ethylene diamine disuccinic acid mixed solution exhibits a synergistic solubilisation effect that is superior to that of a saponin and citric acid mixed solution. The extraction rate of heavy metal in fly ash leached with a saponin and chelator mixed solution is related to the pH of the leaching solution, and the optimal range of the pH is suggested to be approximately neutral. After leaching with a saponin and chelator mixed solution, copper, zinc, lead, and cadmium contents significantly decreased (p < 0.05) in the extractable or acid-soluble and reducible fractions. By adopting the proposed approach, the leaching concentrations of copper, zinc, lead, and cadmium in treated fly ash are in accordance with Standard for Pollution Control on the Security Landfill Site for Hazardous Wastes GB18598-2001. PMID:26185165

  12. Increased Uptake of Chelated Copper Ions by Lolium perenne Attributed to Amplified Membrane and Endodermal Damage

    PubMed Central

    Johnson, Anthea; Singhal, Naresh

    2015-01-01

    The contributions of mechanisms by which chelators influence metal translocation to plant shoot tissues are analyzed using a combination of numerical modelling and physical experiments. The model distinguishes between apoplastic and symplastic pathways of water and solute movement. It also includes the barrier effects of the endodermis and plasma membrane. Simulations are used to assess transport pathways for free and chelated metals, identifying mechanisms involved in chelate-enhanced phytoextraction. Hypothesized transport mechanisms and parameters specific to amendment treatments are estimated, with simulated results compared to experimental data. Parameter values for each amendment treatment are estimated based on literature and experimental values, and used for model calibration and simulation of amendment influences on solute transport pathways and mechanisms. Modeling indicates that chelation alters the pathways for Cu transport. For free ions, Cu transport to leaf tissue can be described using purely apoplastic or transcellular pathways. For strong chelators (ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA)), transport by the purely apoplastic pathway is insufficient to represent measured Cu transport to leaf tissue. Consistent with experimental observations, increased membrane permeability is required for simulating translocation in EDTA and DTPA treatments. Increasing the membrane permeability is key to enhancing phytoextraction efficiency. PMID:26512647

  13. Effect of dietary fibers on cholic acid induced cell proliferation in the colonic epithelium of C57BL/6J mice

    SciTech Connect

    Robblee, N.M.; Bruce, W.R.; Bird, R.P.

    1986-03-01

    It has been postulated that high fat diets promote tumorigenesis by increasing the level of secondary bile acids in the colonic lumen. Dietary fibers are thought to be protective perhaps through their interaction with bile acids. In the present study, animals were fed diets containing either 0%, 5%, or 10% cellulose (C), pectin (P), or wheat bran (WB). The diets were formulated to contain either 0% (control) or 0.2% cholic acid (test). After two weeks of dietary treatment the animals were injected with (/sup 3/H)-thymidine and their colons were processed for autoradiography. The number of labeled cells (LC) in the colonic crypts was determined. Among the control diets, 10%P induced a two-fold increase in the LC. All the test groups had significantly higher LC than in their controls. However, the C group excited a higher LC than the P or WB groups (5.2 +/- 0.8 vs 3.9 +/- 0.8 or 3.9 +/- 0.6). These results were substantiated by metaphase arrest technique. The authors results show that nonfermentable fiber does not alleviate bile acid induced cell proliferative activity in the colon whereas fermentable fibers will counteract the promotional effect of a high fat diet.

  14. The Impact of Enzyme Characteristics on Corn Stover Fiber Degradation and Acid Production During Ensiled Storage

    NASA Astrophysics Data System (ADS)

    Ren, Haiyu; Richard, Tom L.; Moore, Kenneth J.

    Ensilage can be used to store lignocellulosic biomass before industrial bioprocessing. This study investigated the impacts of seven commerical enzyme mixtures derived from Aspergillus niger, Trichoderma reesei, and T. longibrachiatum. Treatments included three size grades of corn stover, two enzyme levels (1.67 and 5 IU/g dry matter based on hemicellulase), and various ratios of cellulase to hemicellulase (C ∶ H). The highest C ∶ H ratio tested, 2.38, derived from T. reesei, resulted in the most effective fermentation, with lactic acid as the dominant product. Enzymatic activity during storage may complement industrial pretreatment; creating synergies that could reduce total bioconversion costs.

  15. Additive for electrolyte of lead-acid batteries

    SciTech Connect

    Greene, R.M.

    1986-10-14

    This patent describes a lead-acid storage battery containing as an electrolyte for each cell, an aqueous sulfuric acid solution containing an activating amount of an additive comprising a mixture of an iron chelate and a magnesium salt or chelate. The chelates for the iron and magnesium are formed from the chelating agents which form 4 to 6 membered rings with the iron and magnesium and which contain a member of the group consisting of amine groups, phenol groups and aldehyde groups.

  16. Dietary fiber down-regulates colonic tumor necrosis factor alpha and nitric oxide production in trinitrobenzenesulfonic acid-induced colitic rats.

    PubMed

    Rodríguez-Cabezas, Maria Elena; Gálvez, Julio; Lorente, Maria Dolores; Concha, Angel; Camuesco, Desirée; Azzouz, Shamira; Osuna, Antonio; Redondo, Luis; Zarzuelo, Antonio

    2002-11-01

    Previous studies have revealed the beneficial effects exerted by dietary fiber in human inflammatory bowel disease, which were associated with an increased production of SCFA in distal colon. The aim of the present study was to elucidate the probable mechanisms involved in the beneficial effects of a fiber-supplemented diet (5% Plantago ovata seeds) in the trinitrobenzenesulfonic acid (TNBS) model of rat colitis, with special attention to its effects on the production of some of the mediators involved in the inflammatory response, such as tumor necrosis factor alpha (TNFalpha) and nitric oxide (NO). Rats were fed the fiber-supplemented diet for 2 wk before TNBS colitis induction and thereafter until colonic evaluation 1 wk later. The results obtained showed that dietary fiber supplementation facilitated recovery from intestinal insult as evidenced both histologically, by a preservation of intestinal cytoarchitecture, and biochemically, by a significant reduction in colonic myeloperoxidase activity and by restoration of colonic glutathione levels. This intestinal anti-inflammatory effect was associated with lower TNFalpha levels and lower NO synthase activity in the inflamed colon, showing significant differences when compared with nontreated colitic rats. Moreover, the intestinal contents from fiber-treated colitic rats showed a significantly higher production of SCFA, mainly butyrate and propionate. We conclude that the increased production of these SCFA may contribute to recovery of damaged colonic mucosa because they constitute substrates for the colonocyte and, additionally, that they can inhibit the production of proinflammatory mediators, such as TNFalpha and NO. PMID:12421838

  17. Spontaneous Differentiation of Human Mesenchymal Stem Cells on Poly-Lactic-Co-Glycolic Acid Nano-Fiber Scaffold

    PubMed Central

    Sonomoto, Koshiro; Yamaoka, Kunihiro; Kaneko, Hiroaki; Yamagata, Kaoru; Sakata, Kei; Zhang, Xiangmei; Kondo, Masahiro; Zenke, Yukichi; Sabanai, Ken; Nakayamada, Shingo; Sakai, Akinori; Tanaka, Yoshiya

    2016-01-01

    Introduction Mesenchymal stem cells (MSCs) have immunosuppressive activity and can differentiate into bone and cartilage; and thus seem ideal for treatment of rheumatoid arthritis (RA). Here, we investigated the osteogenesis and chondrogenesis potentials of MSCs seeded onto nano-fiber scaffolds (NFs) in vitro and possible use for the repair of RA-affected joints. Methods MSCs derived from healthy donors and patients with RA or osteoarthritis (OA) were seeded on poly-lactic-glycolic acid (PLGA) electrospun NFs and cultured in vitro. Results Healthy donor-derived MSCs seeded onto NFs stained positive with von Kossa at Day 14 post-stimulation for osteoblast differentiation. Similarly, MSCs stained positive with Safranin O at Day 14 post-stimulation for chondrocyte differentiation. Surprisingly, even cultured without any stimulation, MSCs expressed RUNX2 and SOX9 (master regulators of bone and cartilage differentiation) at Day 7. Moreover, MSCs stained positive for osteocalcin, a bone marker, and simultaneously also with Safranin O at Day 14. On Day 28, the cell morphology changed from a spindle-like to an osteocyte-like appearance with processes, along with the expression of dentin matrix protein-1 (DMP-1) and matrix extracellular phosphoglycoprotein (MEPE), suggesting possible differentiation of MSCs into osteocytes. Calcification was observed on Day 56. Expression of osteoblast and chondrocyte differentiation markers was also noted in MSCs derived from RA or OA patients seeded on NFs. Lactic acid present in NFs potentially induced MSC differentiation into osteoblasts. Conclusions Our PLGA scaffold NFs induced MSC differentiation into bone and cartilage. NFs induction process resembled the procedure of endochondral ossification. This finding indicates that the combination of MSCs and NFs is a promising therapeutic technique for the repair of RA or OA joints affected by bone and cartilage destruction. PMID:27055270

  18. Biodegradability of injection molded bioplastic pots containing polylactic acid and poultry feather fiber.

    PubMed

    Ahn, H K; Huda, M S; Smith, M C; Mulbry, W; Schmidt, W F; Reeves, J B

    2011-04-01

    The biodegradability of three types of bioplastic pots was evaluated by measuring carbon dioxide produced from lab-scale compost reactors containing mixtures of pot fragments and compost inoculum held at 58 °C for 60 days. Biodegradability of pot type A (composed of 100% polylactic acid (PLA)) was very low (13 ± 3%) compared to literature values for other PLA materials. Near infrared spectroscopy (NIRS) results suggest that the PLA undergoes chemical structural changes during polymer extrusion and injection molding. These changes may be the basis of the low biodegradability value. Biodegradability of pot types B (containing 5% poultry feather, 80% PLA, 15% starch), and C (containing 50% poultry feather, 25% urea, 25% glycerol), were 53 ± 2% and 39 ± 3%, respectively. More than 85% of the total biodegradation of these bioplastics occurred within 38 days. NIRS results revealed that poultry feather was not degraded during composting. PMID:21320772

  19. From Dietary Fiber to Host Physiology: Short-Chain Fatty Acids as Key Bacterial Metabolites.

    PubMed

    Koh, Ara; De Vadder, Filipe; Kovatcheva-Datchary, Petia; Bäckhed, Fredrik

    2016-06-01

    A compelling set of links between the composition of the gut microbiota, the host diet, and host physiology has emerged. Do these links reflect cause-and-effect relationships, and what might be their mechanistic basis? A growing body of work implicates microbially produced metabolites as crucial executors of diet-based microbial influence on the host. Here, we will review data supporting the diverse functional roles carried out by a major class of bacterial metabolites, the short-chain fatty acids (SCFAs). SCFAs can directly activate G-coupled-receptors, inhibit histone deacetylases, and serve as energy substrates. They thus affect various physiological processes and may contribute to health and disease. PMID:27259147

  20. Studying Cellulose Fiber Structure by SEM, XRD, NMR and Acid Hydrolysis

    SciTech Connect

    Zhao, Haibo; Kwak, Ja Hun; Zhang, Z. Conrad; Brown, Heather M.; Arey, Bruce W.; Holladay, John E.

    2007-03-21

    Cotton linters were partially hydrolyzed in dilute acid and the morphology of remaining macrofibrils studied with Scanning Electron Microscopy (SEM) under various magnifications. The crystal region (microfibril bundles) in the macrofibrils was not altered by hydrolysis, and only amorphous cellulose was hydrolyzed and leached out from the macrofibrils. The diameter of microfibril bundles was 20-30 nm after the amorphous cellulose was removed by hydrolysis. XRD experiments confirm the unaltered diameter of the microfibrils after hydrolysis. The strong stability of these microfibril bundles in hydrolysis limits both the total sugar monomer yield and the size of nano particles or rods produced in hydrolysis. The large surface potential on the remaining microfibril bundles drives the agglomeration of macrofibrils.

  1. Asbestos-induced endothelial cell activation and injury. Demonstration of fiber phagocytosis and oxidant-dependent toxicity.

    PubMed

    Garcia, J G; Gray, L D; Dodson, R F; Callahan, K S

    1988-10-01

    Vascular endothelial cell injury is important in the development of a variety of chronic interstitial lung disorders. However, the involvement of such injury in the inflammatory response associated with the inhalation of asbestos fibers is unclear and the mechanism of asbestos fiber cytotoxicity remains unknown. In the present study, human umbilical vein endothelial cells were challenged with amosite asbestos and several parameters of cellular function were examined. Electron microscopic examination revealed that endothelial cell exposure to asbestos resulted in active phagocytosis of these particulates. Biochemical evidence of dose-dependent asbestos-mediated endothelial cell activation was indicated by increased metabolism of arachidonic acid. For example, amosite asbestos (500 micrograms/ml) produced a ninefold increase in prostacyclin (PGI2) levels over those levels in non-exposed cells. Incubation of human endothelial cells with asbestos fibers induced specific 51Cr release in both a dose- and time-dependent fashion indicative of cellular injury. Injury induced by amosite asbestos was not significantly attenuated by treatment of the endothelial cell monolayer with either the iron chelator deferoxamine, which prevents hydroxyl radical (.OH) formation, or by the superoxide anion (O2-) scavenger, superoxide dismutase. However, significant dose-dependent protection was observed with the hydrogen peroxide (H2O2) scavenger, catalase. Chelation of elemental iron present within amosite asbestos fibers by deferoxamine produced a 33% reduction in asbestos cytotoxicity, suggesting a potential role for hydroxyl radical-mediated injury via the iron-catalyzed Haber-Weiss reaction.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3202471

  2. Copper Chelation in Alzheimer's Disease Protein

    NASA Astrophysics Data System (ADS)

    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.

  3. Preparation and physicochemical properties of soluble dietary fiber from orange peel assisted by steam explosion and dilute acid soaking.

    PubMed

    Wang, Lei; Xu, Honggao; Yuan, Fang; Fan, Rui; Gao, Yanxiang

    2015-10-15

    The coupled pretreatment of orange peel with steam explosion (SE) and sulfuric-acid soaking (SAS) was investigated to enhance the yield and improve the functionality of soluble dietary fiber (SDF). When orange peel was pretreated by SE at 0.8MPa for 7 min, combined with 0.8% SAS, the content of SDF was increased from 8.04% to 33.74% in comparison to the control and SDF prepared with SE-SAS showed the high water solubility, water-holding capacity, oil-holding capacity, swelling capacity, emulsifying activity, emulsion stability and foam stability. SDF from orange peel treated by SE-SAS exhibited significantly (p < 0.05) higher binding capacity for three toxic cations (Pb, As and Cu) and smaller molecular weight (Mw = 174 kDa). Furthermore, differential scanning calorimetry (DSC) measurement showed that SDF from orange peel treated by SE-SAS had a higher peak temperature (170.7 ± 0.4 °C) than that of the untreated sample (163.4 ± 0.3 °C). Scanning electron micrograph (SEM) images demonstrated that the surface of SDF from orange peel treated by SE-SAS was rough and collapsed. It can be concluded that SDF from orange peel treated by SE-SAS has the higher potential to be applied as a functional ingredient in food products. PMID:25952845

  4. Phytoremediation of Cr(VI) by Spirodela polyrrhiza (L.) Schleiden employing reducing and chelating agents.

    PubMed

    Bala, Rajni; Thukral, Ashwani K

    2011-01-01

    Phytoremediation of Cr(VI) by Spirodela polyrrhiza in binary combinations with low molecular weight organic compounds (LMWOCs) with a reducing or chelating potential, viz., ascorbic acid, citric acid, tartaric acid, oxalic acid, lactic acid, and glycerol was studied in Cr(VI) containing hydroponic media. Significant increase in the relative dry weight of plants with respect to Cr(VI) treated controls was observed with ascorbic acid and glycerol. The uptake of chromium by S. polyrrhiza followed Michaelis-Menten kinetics of active ion uptake. Interaction between Cr and ascorbic acid, oxalic acid, and lactic acid decreased Cr uptake, whereas citric acid, glycerol, and tartaric acid increased it. Supplementation of LMWOCs to Cr(VI) containing media decreased the MDA content of the plants. Multiple regression models revealed that LMWOCs decrease lipid peroxidation independently, as well as that induced by Cr(VI). It was found that superoxide dismutase (SOD), guaiacol peroxidase (GPX), and catalase (CAT) activities were increased significantly in plants growing in media containing Cr(VI). The study established that lactic acid, citric acid, ascorbic acid, and glycerol were most effective in increasing the Cr(VI) phytoremediating potential of S. polyrrhiza and LMWOCs with reducing or chelating properties decrease Cr(VI) stress in S. polyrrhiza. PMID:21598777

  5. Carboxymethylated polyethylenimine-polymethylenepolyphenylene isocyanate chelating ion exchange resin preconcentration for inductively coupled plasma spectrometry

    SciTech Connect

    Horvath, A.; Barnes, R.M.

    1986-06-01

    A carboxymethylated polyethylenimine-polylmethylenepolyphenylene isocyanate chelating ion exchange resin was prepared, characterized, and used for metals preconcentration for inductively coupled plasma spectrometry. The uptake of copper, cadmium, lead, and zinc by the resin was quantitative in the presence of high concentrations of ammonium, calcium, magnesium, potassium, sodium, and acetate and citrate salts. These metals could be collected from artificial seawater, Dead Sea water, and dissolved bone with a recovery of nearly 100%. The resin also chelates heavy metals and rare earths. Complexed metals can be eluted from the resin column with strong acids. The resin does not change volume with ionic form changes and can be regenerated for repeated use.

  6. Bifunctional Gallium-68 Chelators: Past, Present, and Future.

    PubMed

    Spang, Philipp; Herrmann, Christian; Roesch, Frank

    2016-09-01

    This article reviews the development of bifunctional chelates for synthesising (68)Ga radiopharmaceuticals. It structures the chelates into groups of macrocycles, nonmacrocycles, and chimeric derivatives. The most relevant bifunctional chelates are discussed in chelate structure, parameters of (68)Ga-labeling, and stability of the (68)Ga-chelate complexes. Furthermore those derivatives are included, where (67)Ga was applied instead of (68)Ga. A particular feature discussed is the ability of certain bifunctional chelate structures to function in kit-type preparation of the (68)Ga radiopharmaceuticals. Currently, nonmacrocyclic and chimeric derivates attract particular attention such as THP-derivates and DATA-derivates. PMID:27553464

  7. Trypanotoxic activity of thiosemicarbazone iron chelators.

    PubMed

    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

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

    PubMed

    Rush, Travis; Hjelmhaug, Julie; Lobner, Doug

    2009-01-01

    Chelation therapy for the treatment of acute, high dose exposure to heavy metals is accepted medical practice. However, a much wider use of metal chelators is by alternative health practitioners for so called "chelation therapy". Given this widespread and largely unregulated use of metal chelators it is important to understand the actions of these compounds. We tested the effects of four commonly used metal chelators, calcium disodium ethylenediaminetetraacetate (CaNa2EDTA), D-penicillamine (DPA), 2,3 dimercaptopropane-1-sulfonate (DMPS), and dimercaptosuccinic acid (DMSA) for their effects on heavy metal neurotoxicity in primary cortical cultures. We studied the toxicity of three forms of mercury, inorganic mercury (HgCl2), methyl mercury (MeHg), and ethyl mercury (thimerosal), as well as lead (PbCl2) and iron (Fe-citrate). DPA had the worst profile of effects, providing no protection while potentiating HgCl2, thimerosal, and Fe-citrate toxicity. DMPS and DMSA both attenuated HgCl2 toxicity and potentiated thimerosal and Fe toxicity, while DMPS also potentiated PbCl2 toxicity. CaNa2EDTA attenuated HgCl2 toxicity, but caused a severe potentiation of Fe-citrate toxicity. The ability of these chelators to attenuate the toxicity of various metals is quite restricted, and potentiation of toxicity is a serious concern. Specifically, protection is provided only against inorganic mercury, while it is lacking against the common form of mercury found in food, MeHg, and the form found in vaccines, thimerosal. The potentiation of Fe-citrate toxicity is of concern because of iron's role in oxidative stress in the body. Potentiation of iron toxicity could have serious health consequences when using chelation therapy. PMID:19027035

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

    PubMed

    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

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

    PubMed

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

    2006-09-27

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

  11. Chelation of cadmium without increased renal cadmium deposition.

    PubMed Central

    Cherian, M G

    1984-01-01

    Cadmium (Cd) is mainly accumulated in liver and kidney bound to metallothionein (MT) and excreted very slowly from the body. In chronic exposure, Cd is gradually transported from liver to kidney; the renal toxic effects appear when renal Cd concentration exceeds the critical concentration. In order to prevent the Cd-induced renal disease, it is important to control the movement of Cd to the kidney and its renal deposition. However, the chelation of Cd from liver is difficult because of the high affinity of intracellular MT for Cd. A number of chelating agents containing both carboxyl and thiol groups were able to mobilize and excrete Cd more easily in a short time (1/2 hr) after Cd exposure than longer times (24 hr), after MT synthesis. The renal deposition of Cd increased on BAL (2,3-dimercaptopropanol) treatment a short time (1/2 hr) after Cd exposure. However, it was observed that if BAL was administered 24 hr after Cd exposure, it could mobilize Cd from hepatic MT and increase the biliary excretion of Cd without any increase in renal Cd concentration. Studies using a number of structurally related thiols (mono-, di- and trithiols) showed that the major structural requirement for in vivo chelation of Cd from intracellular MT were the vicinal thiol groups on an aliphatic chain, and lipophilicity. BAL was the most effective of all the compounds studied and it did not mobilize Cd to the kidney, when most of the intracellular Cd was bound to MT. Furthermore, a delayed treatment with BAL or DTPA (diethylenetriamine pentaacetic acid) after synthesis of MT resulted in an increase in fecal or urinary excretion of Cd in rat model experiment.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6734559

  12. Reversible adsorption of catalase onto Fe(3+) chelated poly(AAm-GMA)-IDA cryogels.

    PubMed

    Aktaş Uygun, Deniz; Uygun, Murat; Akgöl, Sinan; Denizli, Adil

    2015-05-01

    In this presented study, poly(acrylamide-glycidyl methacrylate) [poly(AAm-GMA)] cryogels were synthesized by cryopolymerization technique at sub-zero temperature. Prepared cryogels were then functionalized with iminodiacetic acid (IDA) and chelated with Fe(3+) ions in order produce the metal chelate affinity matrix. Synthesized cryogels were characterized with FTIR, ESEM and EDX analysis, and it was found that the cryogel had sponge like structure with interconnected pores and their pore diameter was about 200 μm. Fe(3+) chelated poly(AAm-GMA)-IDA cryogels were used for the adsorption of catalase and optimum adsorption conditions were determined by varying the medium pH, initial catalase concentration, temperature and ionic strength. Maximum catalase adsorption onto Fe(3+) chelated poly(AAm-GMA)-IDA cryogel was found to be 12.99 mg/g cryogel at 25 °C, by using pH 5.0 acetate buffer. Adsorbed catalase was removed from the cryogel by using 1.0M of NaCl solution and desorption yield was found to be 96%. Additionally, reusability profile of the Fe(3+) chelated poly(AAm-GMA)-IDA cryogel was also investigated and it was found that, adsorption capacity of the cryogels didn't decrease significantly at the end of the 40 reuses. Catalase activity studies were also tested and it was demonstrated that desorbed catalase retained 70% of its initial activity. PMID:25746283

  13. Antioxidant and metal chelating activities of peptide fractions from phaseolin and bean protein hydrolysates.

    PubMed

    Carrasco-Castilla, Janet; Hernández-Álvarez, Alan Javier; Jiménez-Martínez, Cristian; Jacinto-Hernández, Carmen; Alaiz, Manuel; Girón-Calle, Julio; Vioque, Javier; Dávila-Ortiz, Gloria

    2012-12-01

    Bean protein isolate and phaseolin were hydrolysed using pepsin and pancreatin, and the resulting hydrolysates were filtered through a 1kDa cut-off membrane and fractionated by size exclusion chromatography. Three fractions corresponding to MW 0.7-1.0kDa, 0.43-0.7kDa and <0.43kDa (A1, A2, and A3 for protein isolate fractions, and B1, B2, and B3 for phaseolin fractions) were assayed for antioxidant and metal chelating activity and they were also subjected to amino acid and SDS-PAGE analysis. Fractions A1 and B1 had the highest copper chelating activity (78% and 82%, respectively), while iron chelating activity was the highest in fractions A1 and B3 (36% and 16%, respectively). Fractions A2 and B3 had the highest antioxidant activity as determined by inhibition of reducing power and β-carotene bleaching, while the highest ABTS radical scavenging activity was found in A3 and B3. Thus, fractions coming from the isolate and phaseolin had similar activities except for iron chelation, suggesting that phaseolin is the major contributor to the antioxidant and copper chelating activities of the hydrolysed protein isolate. PMID:22953924

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

    PubMed

    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

  15. Contribution of lipids, phenolic acids, and protein rich components to emulsifying properties of corn fiber gum and acacia gum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn fiber gum (CFG) is an arabinoxylan enriched fraction obtained by the extraction of corn bran/fiber using a proprietary alkaline hydrogen peroxide process. When purified CFG prepared by this process was hydrolyzed with concentrated base (1.5 N methanolic KOH at 70 °C for one hour) considerable ...

  16. Structural, electrical, mechanical and thermal properties of electrospun fibers of poly(lactic acid)/polyaniline blend.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conducting electrospun fiber mats based on PLA and PAni blends were obtained with average diameter values between 87 and 1 006nm with PAni quantities from 0 to 5.6 wt.-%. Structural characteristics of fiber mats were compared to cast films with the same amount of PAni and studied by SEM, SAXS, and A...

  17. Synthesis and Evaluation of New Generation Cross-Bridged Bifunctional Chelator for (64)Cu Radiotracers.

    PubMed

    Dale, Ajit V; An, Gwang Il; Pandya, Darpan N; Ha, Yeong Su; Bhatt, Nikunj; Soni, Nisarg; Lee, Hochun; Ahn, Heesu; Sarkar, Swarbhanu; Lee, Woonghee; Huynh, Phuong Tu; Kim, Jung Young; Gwon, Mi-Ri; Kim, Sung Hong; Park, Jae Gyu; Yoon, Young-Ran; Yoo, Jeongsoo

    2015-09-01

    Bifunctional chelators have been successfully used to construct (64)Cu-labeled radiopharmaceuticals. Previously reported chelators with cross-bridged cyclam backbones have various essential features such as high stability of the copper(II) complex, high efficiency of radiolabeling at room temperature, and good biological inertness of the radiolabeled complex, along with rapid body clearance. Here, we report a new generation propylene-cross-bridged chelator with hybrid acetate/phosphonate pendant groups (PCB-TE1A1P) developed with the aim of combining these key properties in a single chelator. The PCB-TE1A1P was synthesized from cyclam with good overall yield. The Cu(II) complex of our chelator showed good robustness in kinetic stability evaluation experiments, such as acidic decomplexation and cyclic voltammetry studies. The Cu(II) complex of PCB-TE1A1P remained intact under highly acidic conditions (12 M HCl, 90 °C) for 8 d and showed quasi-reversible reduction/oxidation peaks at -0.77 V in electrochemical studies. PCB-TE1A1P was successfully radiolabeled with (64)Cu ions in an acetate buffer at 60 °C within 60 min. The electrophoresis study revealed that the (64)Cu-PCB-TE1A1P complex has net negative charge in aqueous solution. The biodistribution and in vivo stability study profiles of (64)Cu-PCB-TE1A1P indicated that the radioactive complex was stable under physiological conditions and cleared rapidly from the body. A whole body positron emission tomography (PET) imaging study further confirmed high in vivo stability and fast clearance of the complex in mouse models. In conclusion, PCB-TE1A1P has good potential as a bifunctional chelator for (64)Cu-based radiopharmaceuticals, especially those involving peptides. PMID:26286436

  18. Development of an upconverting chelate assay

    NASA Astrophysics Data System (ADS)

    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.

  19. Chelating agents exert distinct effects on biofilm formation in Staphylococcus aureus depending on strain background: role for clumping factor B

    PubMed Central

    Abraham, Nabil M.; Lamlertthon, Supaporn; Fowler, Vance G.

    2012-01-01

    Staphylococcus aureus is a leading cause of catheter infections, and biofilm formation plays a key role in the pathogenesis. Metal ion chelators inhibit bacterial biofilm formation and viability, making them attractive candidates as components in catheter lock solutions. The goal of this study was to characterize further the effect of chelators on biofilm formation. The effect of the calcium chelators ethylene glycol tetraacetic acid (EGTA) and trisodium citrate (TSC) on biofilm formation by 30 S. aureus strains was tested. The response to subinhibitory doses of EGTA and TSC varied dramatically depending on strain variation. In some strains, the chelators prevented biofilm formation, in others they had no effect, and they actually enhanced biofilm formation in others. The molecular basis for this phenotypic variability was investigated using two related strains: Newman, in which biofilm formation was inhibited by chelators, and 10833, which formed strong biofilms in the presence of chelators. It was found that deletion of the gene encoding the surface adhesin clumping factor B (clfB) completely eliminated chelator-induced biofilm formation in strain 10833. The role of ClfB in biofilm formation activity in chelators was confirmed in additional strains. It was concluded that biofilm-forming ability varies strikingly depending on strain background, and that ClfB is involved in biofilm formation in the presence EGTA and citrate. These results suggest that subinhibitory doses of chelating agents in catheter lock solutions may actually augment biofilm formation in certain strains of S. aureus, and emphasize the importance of using these agents appropriately so that inhibitory doses are achieved consistently. PMID:22516131

  20. Effect of boiling in water of barley and buckwheat groats on the antioxidant properties and dietary fiber composition.

    PubMed

    Hęś, Marzanna; Dziedzic, Krzysztof; Górecka, Danuta; Drożdżyńska, Agnieszka; Gujska, Elżbieta

    2014-09-01

    In recent years, there has been an ever-increasing interest in the research of polyphenols obtained from dietary sources, and their antioxidative properties. The purpose of this study was to determine the effect of boiling buckwheat and barley groats on the antioxidant properties and dietary fiber composition. Antioxidative properties were investigated using methyl linoleate model system, by assessing the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity and metal chelating activity. The results were compared with butylated hydroxytoluene (BHT). Raw barley and buckwheat groats extracts showed higher DPPH scavenging ability compared to boiled barley and buckwheat groats extracts. Raw barley groats extract exhibited higher antioxidant activity than boiled groats extract in the methyl linoleate emulsion. Higher chelating ability in relation to Fe (II) ions was observed for boiled groats extracts as compared to raw groats extracts. BHT showed small antiradical activity and metal chelating activity, while showing higher antioxidative activity in emulsion system. The analysis of groats extracts using HPLC method showed the presence of rutin, catechin, quercetin, gallic, p-hydroxybenzoic, p-coumaric, o-coumaric, vanillic, sinapic, and ferulic acids. Differences in the content of dietary fiber and its fractions were observed in the examined products. The highest total dietary fiber content was detected in boiled buckwheat groats, while the lowest - in boiled barley groats. The scientific achievements of this research could help consumers to choose those cereal products available on the market, such as barley and buckwheat groats, which are a rich source of antioxidative compounds and dietary fiber. PMID:24938316

  1. Exovascular application of epigallocatechin-3-O-gallate-releasing electrospun poly(L-lactide glycolic acid) fiber sheets to reduce intimal hyperplasia in injured abdominal aorta.

    PubMed

    Lee, Mi Hee; Kwon, Byeong-ju; Koo, Min-Ah; Jang, Eui Hwa; Seon, Gyeung Mi; Park, Jong-Chul

    2015-09-01

    Intimal hyperplasia is an excessive ingrowth of tissue resulting in chronic structural lesions commonly found at sites of atherosclerotic lesions, arterial angioplasty, vascular graft anastomoses, and other vascular abnormalities. Epigallocatechin-3-O-gallate (EGCG) was shown to elicit antioxidant, anti-proliferative, and anti-thrombogenic effects. In this study, we used an electrospinning technique to synthesize EGCG-eluting biodegradable poly(L-lactide glycolic acid) (PLGA) fiber sheets for local delivery of EGCG and investigated the effect of their exovascular application on intimal hyperplasia following balloon-induced abdominal aorta injury in a rabbit experimental model. The morphology of the composite sheets was characterized using scanning electron microscopy and Fourier transform-infrared spectroscopy. EGCG was loaded and dispersed into the PLGA-based electrospun fibers. The EGCG-loaded PLGA sheets exhibited sustained EGCG release following the initial 24 h of burst release in phosphate-buffered saline. In vivo studies demonstrated significant inhibition of intimal hyperplasia following the application of the EGCG-eluting electrospun PLGA fiber sheets, compared with vehicle PLGA controls. In conclusion, our results show that exovascular application of EGCG-eluting PLGA electrospun fiber sheets may provide a useful system for the effective local delivery of drugs for the prevention of intimal hyperplasia. PMID:26391656

  2. Determination of equilibrium constants of alkaline earth metal ion chelates with Dowex A-1 chelating resin.

    PubMed

    Harju, L; Krook, T

    1995-03-01

    A complexation chemistry model is applied to chelating ion-exchange systems and a method is presented for the determination of equilibrium constants for metal ion chelates with these resins. Protonation constants for the iminodiacetic based chelating resin Dowex A-1 were determined from potentiometric pH-data. Equilibrium constants were determined for 1:1 beryllium, magnesium, calcium, strontium and barium chelates with the resin in a wide pH range by measuring the concentrations of respective metal ions in the aqueous phase with direct current plasma atomic emission spectrometry (DCP-AES). A batch technique was used for the equilibrium experiments. At pH below 7 protonated 1:1 species were also found to be formed with the resin. From the obtained equilibrium constants, theoretical distribution coefficients were calculated as function of pH for respective metal ion resin system. PMID:18966248

  3. Branched polymeric media: boron-chelating resins from hyperbranched polyethylenimine.

    PubMed

    Mishra, Himanshu; Yu, Changjun; Chen, Dennis P; Goddard, William A; Dalleska, Nathan F; Hoffmann, Michael R; Diallo, Mamadou S

    2012-08-21

    Extraction of boron from aqueous solutions using selective resins is important in a variety of applications including desalination, ultrapure water production, and nuclear power generation. Today's commercial boron-selective resins are exclusively prepared by functionalization of styrene-divinylbenzene (STY-DVB) beads with N-methylglucamine to produce resins with boron-chelating groups. However, such boron-selective resins have a limited binding capacity with a maximum free base content of 0.7 eq/L, which corresponds to a sorption capacity of 1.16 ± 0.03 mMol/g in aqueous solutions with equilibrium boron concentration of ∼70 mM. In this article, we describe the synthesis and characterization of a new resin that can selectively extract boron from aqueous solutions. We show that branched polyethylenimine (PEI) beads obtained from an inverse suspension process can be reacted with glucono-1,5-D-lactone to afford a resin consisting of spherical beads with high density of boron-chelating groups. This resin has a sorption capacity of 1.93 ± 0.04 mMol/g in aqueous solution with equilibrium boron concentration of ∼70 mM, which is 66% percent larger than that of standard commercial STY-DVB resins. Our new boron-selective resin also shows excellent regeneration efficiency using a standard acid wash with a 1.0 M HCl solution followed by neutralization with a 0.1 M NaOH solution. PMID:22827255

  4. Using iron chelating agents to enhance dermatological PDT

    NASA Astrophysics Data System (ADS)

    Curnow, Alison; Dogra, Yuktee; Winyard, Paul; Campbell, Sandra

    2009-06-01

    Topical protoporphyrin IX (PPIX) induced photodynamic therapy (PDT) of basal cell carcinoma (BCC) produces good clinical outcomes with excellent cosmesis as long as the disease remains superficial. Efficacy for nodular BCC however appears inferior to standard treatment unless repeat treatments are performed. Enhancement is therefore required and is possible by employing iron chelating agents to temporarily increase PPIX accumulation above the levels normally obtained using aminolevulinic acid (ALA) or the methyl ester of ALA (MAL) alone. In vitro studies investigated the effect of the novel iron chelator, CP94 on necrotic or apoptotic cell death in cultured human skin fibroblasts and epidermal carcinoma cells incubated with MAL. Furthermore, following a dose escalating safety study conducted with ALA in patients, an additional twelve nodular BCCs were recruited for topical treatment with standard MAL-PDT +/- increasing doses of CP94. Six weeks later following clinical assessment, the whole treatment site was excised for histological analysis. CP94 produced greater cell death in vitro when administered in conjunction with MAL than this porphyrin precursor could produce when administered alone. Clinically, PDT treatment using Metvix + CP94 was a simple and safe modification associated with a trend of reduced tumor thickness with increasing CP94 dose.

  5. Tuning Chelation by the Surfactant-Like Peptide A6H Using Predetermined pH Values

    PubMed Central

    2013-01-01

    We examine the self-assembly of a peptide A6H comprising a hexa-alanine sequence A6 with a histidine (H) “head group”, which chelates Zn2+ cations. We study the self-assembly of A6H and binding of Zn2+ ions in ZnCl2 solutions, under acidic and neutral conditions. A6H self-assembles into nanotapes held together by a β-sheet structure in acidic aqueous solutions. By dissolving A6H in acidic ZnCl2 solutions, the carbonyl oxygen atoms in A6H chelate the Zn2+ ions and allow for β-sheet formation at lower concentrations, consequently reducing the onset concentration for nanotape formation. A6H mixed with water or ZnCl2 solutions under neutral conditions produces short sheets or pseudocrystalline tapes, respectively. The imidazole ring of A6H chelates Zn2+ ions in neutral solutions. The internal structure of nanosheets and pseudocrystalline sheets in neutral solutions is similar to the internal structure of A6H nanotapes in acidic solutions. Our results show that it is possible to induce dramatic changes in the self-assembly and chelation sites of A6H by changing the pH of the solution. However, it is likely that the amphiphilic nature of A6H determines the internal structure of the self-assembled aggregates independent from changes in chelation. PMID:24369761

  6. Development of Iron-Chelating Poly(ethylene terephthalate) Packaging for Inhibiting Lipid Oxidation in Oil-in-Water Emulsions.

    PubMed

    Johnson, David R; Tian, Fang; Roman, Maxine J; Decker, Eric A; Goddard, Julie M

    2015-05-27

    Foods such as bulk oils, salad dressings, and nutritionally fortified beverages that are susceptible to oxidative degradation are often packaged in poly(ethylene terephthalate) (PET) bottles with metal chelators added to the food to maintain product quality. In the present work, a metal-chelating active packaging material is designed and characterized, in which poly(hydroxamic acid) (PHA) metal-chelating moieties were grafted from the surface of PET. Biomimetic PHA groups were grafted in a two-step UV-initiated process without the use of a photoinitiator. Surface characterization of the films by attenuated total reflective Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM) suggested successful grafting and conversion of poly(hydroxyethyl acrylate) (PHEA) to PHA chelating moieties from the surface of PET. Colorimetric (ferrozine) and inductively coupled plasma mass spectroscopy (ICP-MS) assays demonstrated the ability of PET-g-PHA to chelate iron in a low-pH (3.0) environment containing a competitive metal chelator (citric acid). Lipid oxidation studies demonstrated the antioxidant activity of PET-g-PHA films in inhibiting iron-promoted oxidation in an acidified oil-in-water (O/W) emulsion model system (pH 3.0). Particle size and ζ-potential analysis indicated that the addition of PET-g-PHA films did not affect the physical stability of the emulsion system. This work suggests that biomimetic chelating moieties can be grafted from PET and effectively inhibit iron-promoted degradation reactions, enabling removal of metal-chelating additives from product formulations. PMID:25985711

  7. Passive extraction and clean-up of phenoxy acid herbicides in samples from a groundwater plume using hollow fiber supported liquid membranes.

    PubMed

    Liu, Jing-Fu; Toräng, Lars; Mayer, Philipp; Jönsson, Jan Ake

    2007-08-10

    Hollow fiber supported liquid membranes were applied for the passive extraction of phenoxy acid herbicides from water samples. Polypropylene hollow fiber membranes (240 microm i.d., 30 microm wall thickness, 0.05 microm pore size, 30 cm length) were impregnated with 2.0% tri-n-octylphosphine oxide (TOPO) in di-n-hexyl ether in the pores of the fiber wall to form a liquid membrane. They were then filled with basic solution in the lumen as acceptor and finally placed into the sample (donor). Complete extraction of phenoxy acid herbicides including 2,4-D, MCPA, dichlorprop, and mecoprop from an acidified sample (4 mL, adjusted to pH 1.5 with HCl) into basic acceptor (10 microL of 0.2M NaOH) was achieved after 4 h of shaking (100 rpm) resulting in an enrichment factor of 400 times. The acceptor was then neutralized by addition of HCl and injected into a HPLC system for the determination of the phenoxy acid herbicides. Environmentally relevant salinity (0-3.5% NaCl) and dissolved organic matter (0-25 mg/L of dissolved organic carbon) had no significant effect on the extraction. The method provided extraction efficiencies of more than 91%, detection limits of 0.3-0.6 microg/L, and combined extraction and clean up in one single step. This procedure was applied to determine aqueous concentrations of phenoxy acid herbicides in groundwater samples collected from an old dumping site (Cheminova, Denmark) with detected concentrations up to 5800 microg/L. Although the samples were very dirty with large amounts of suspended particles, non-aqueous phase liquids (NAPLs) and dissolved organic matters, good spike recoveries (80-126%) were obtained for 10 of the 11 samples. PMID:17449052

  8. Fluoride ion recognition by chelating and cationic boranes.

    PubMed

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

    2009-02-17

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

  9. Extraction kinetics of rare earth metals with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester using a hollow fiber membrane extractor

    SciTech Connect

    Kubota, Fukiko; Goto, Masahiro; Nakashio, Fumiyuki; Hano, Tadashi

    1995-03-01

    A kinetic study concerning chemical complexation-based solvent extraction of rare earth metals with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester dissolved as an extractant in n-heptane was carried out using a microporous hydrophobic hollow fiber membrane extractor. The effects of concentration of chemical species in aqueous and organic feed solutions on the apparent permeabilities of metal species for extraction and stripping, respectively, were investigated to clarify the permeation mechanism. From the experimental results it was predicted that the permeation rate is controlled by diffusion of the chemical species in aqueous and organic phases and by interfacial chemical reaction. The experimental data were analyzed by the diffusion model accompanied with an interfacial reaction, taking into account the velocity distributions of the aqueous and organic phases through the inner and outer sides of the hollow fiber.

  10. Low dielectric polyimide fibers

    NASA Technical Reports Server (NTRS)

    Dorogy, William E., Jr. (Inventor); St.clair, Anne K. (Inventor)

    1994-01-01

    A high temperature resistant polyimide fiber that has a dielectric constant of less than 3 is presented. The fiber was prepared by first reacting 2,2-bis (4-(4aminophenoxy)phenyl) hexafluoropropane with 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride in an aprotic solvent to form a polyamic acid resin solution. The polyamic acid resin solution is then extruded into a coagulation medium to form polyamic acid fibers. The fibers are thermally cured to their polyimide form. Alternatively, 2,2-bis(4-(4-aminophenoxy)phenyl) hexafluoropropane is reacted with 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride to form a polyamic acid, and the polyamic acid is chemically converted to its polyimide form. The polyimide is then dissolved in a solvent to form a polyimide resin solution, and the polyimide resin is extruded into a coagulation medium to form a polyimide wet gel filament. In order to obtain polyimide fibers of increased tensile properties, the polyimide wet gel filaments are stretched at elevated temperatures. The tensile properties of the fibers were measured and found to be in the range of standard textile fibers. Polyimide fibers obtained by either method will have a dielectric constant similar to that of the corresponding polymer, viz., less than 3 at 10 GHz.

  11. Crystallization kinetics and densification of YAG nanoparticles from various chelating agents

    SciTech Connect

    Hou, J.G.; Kumar, R.V.; Qu, Y.F.; Krsmanovic, Dalibor

    2009-08-05

    Yttrium aluminium garnet (YAG, Y{sub 3}Al{sub 5}O{sub 12}) nanoparticles were prepared using sonochemical sol-gel method with three different chelating agents and the effect of crystallization kinetics was investigated with differential scanning calorimetry-thermogravimetry (DSC-TG). The activation energy values of crystallization for the as-synthesized YAG nanoparticles using citric acid (CA), glycine (G) or a mixture of citric acid-glycine (CA-G), as chelating agents were found to be 160.5, 142.2 and 140.4 kJ mol{sup -1} and the corresponding Avarami constants were 2.2, 2.1 and 1.9, respectively. Samples produced with the mixed chelating agent under sonification, could be crystallized to single phase YAG nanoparticles (10-65 nm) after annealing at 1100 deg. C. Pellets made from the annealed YAG particles could be sintered to a relative density greater than 99% at 1500 deg. C with a grain size of 4.5 {mu}m, made up of secondary particles formed from primary nano-crystals within the grains. Grain size and relative density increased with different chelating agents from CA to G and CA-G in the increasing order when YAG samples were sintered. Grain growth and densification occurred at a relatively low temperature of 1500 deg. C as compared to over 1800 deg. C in solid-state reactions.

  12. Relationship among Chelator Adherence, Change in Chelators, and Quality of Life in Thalassemia

    PubMed Central

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

    2015-01-01

    Purpose Thalassemia, a chronic blood disease, necessitates life-long adherence to blood transfusions and chelation therapy to reduce iron overload. We examine stability of Health-Related Quality of Life (HRQOL) in thalassemia and adherence to chelation therapy over time, especially after changes in chelator choice. Methods Thalassemia Longitudinal Cohort participants in the US, UK, and Canada completed the SF-36v2 (ages 14+), and the PF-28 CHQ (parents of children<14 years). Chelation adherence was defined as self-reported percent of doses administered in the last 4 weeks. Results 258 adults/adolescents (mean 29.7 years) and 133 children (mean 8.5 years) completed a mean of 2.8 years follow-up. Children made few chelator changes, whereas a mean of 2.2 changes was observed among the 37% of adults/adolescents who made chelator changes, mainly, due to patient preference or medical necessity. Physical HRQOL improved among those with lower iron burden (better health status) at baseline who made a single change in chelator, but declined among participants with multiple changes and/or high iron burden (worse health status). Mental health improved among participants with lower iron burden, but iron overload was negatively associated with social functioning. Adherence did not significantly change over follow-up except for an increase after a change from DFO infusion to oral deferasirox (p=0.03). Predictors of lower adherence for adults/adolescents at follow-up included side effects, smoking, younger age, problems preparing DFO, increased number of days per week DFO prescribed, and lower physical QOL. Conclusions Strategies to balance medical needs with family, work, and personal life may assist in adherence. PMID:24682717

  13. The Use of Pristine and Intercalated Graphite Fiber Composites as Buss Bars in Lead-Acid Batteries

    NASA Technical Reports Server (NTRS)

    Opaluch, Amanda M.

    2004-01-01

    This study was conducted as a part of the Firefly Energy Space Act Agreement project to investigate the possible use of composite materials in lead acid batteries. Specifically, it examined the use of intercalated graphite composites as buss bars. Currently, buss bars of these batteries are made of lead, a material that is problematic for several reasons. Over time, the lead is subject to both corrosion at the positive plate and sulfation at the negative plate, resulting in decreased battery life. In addition, the weight and size of the lead buss bars make for a heavy and cumbersome battery that is undesirable. Functionality and practicality of lead buss bars is adequate at best; consequently, investigation of more efficient composite materials would be advantageous. Practically speaking, graphite composites have a low density that is nearly one fourth that of its lead counterpart. A battery made of less dense materials would be more attractive to the consumer and the producer because it would be light and convenient. More importantly, low weight would be especially beneficial because it would result in greater overall power density of the battery. In addition to power density, use of graphite composite materials can also increase the life of the battery. From a functional standpoint, corrosion and sulfation at the positive and negative plates are major obstacles when considering how to extend battery life. Neither of these reactions are a factor when graphite composites replace lead parts because graphite is chemically non-reactive with the electrolyte within the battery. Without the problem of corrosion or sulfation, battery life expectancy can be almost doubled. The replacement of lead battery parts with composite materials is also more environmentally favorable because of easy disposal of organic materials. For this study, both pristine and bromine intercalated single-ply graphite fiber composites were created. The composites were fabricated in such a way as to

  14. Investigation of stabilization mechanism and size controlling of Fe3O4 nanoparticles using anionic chelating agents

    NASA Astrophysics Data System (ADS)

    Ghazanfari, Mohammad Reza; Kashefi, Mehrdad; Jaafari, Mahmoud Reza

    2016-07-01

    Chelating agents have potential effects on different properties of nanoparticles. Fe3O4 nanoparticles were synthesizes Using coprecipitation technique and oxalic, citric, stearic and lauric acids with concentrations of 0.5, 1, 2, and 5 vol% were utilized as the chelating agents. Subsequently, stability, structural, and magnetic properties of the samples were studied using measurement of zeta potential as well as FT-IR, XRD, DLS, TEM, and VSM analyses. It was found that the lower end of the size range was achieved for all samples utilizing 2 vol% chelating agents. So, in the present study, it was chosen as the optimum volume percentage of the chelating agents. Furthermore, for the nanoparticles treated with oxalic and citric acids, particle sizes were lower and the zeta potentials were larger comparing to those treated with stearic and lauric acids, which is an indication of their higher stabilization ability. Finally, the type of chelating agents had negligible effects on the structural and magnetic properties of the synthesized nanoparticles.

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

    SciTech Connect

    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

  16. Paramagnetic lanthanide chelates for multicontrast MRI.

    PubMed

    Cakić, Nevenka; Savić, Tanja; Stricker-Shaver, Janice; Truffault, Vincent; Platas-Iglesias, Carlos; Mirkes, Christian; Pohmann, Rolf; Scheffler, Klaus; Angelovski, Goran

    2016-07-28

    The preparation of a paramagnetic chelator that serves as a platform for multicontrast MRI, and can be utilized either as a T1-weighted, paraCEST or (19)F MRI contrast agent is reported. Its europium(iii) complex exhibits an extremely slow water exchange rate which is optimal for the use in CEST MRI. The potential of this platform was demonstrated through a series of MRI studies on tube phantoms and animals. PMID:27291157

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

    PubMed

    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

  18. Iron Chelation Therapy in Thalassemia Syndromes

    PubMed Central

    Cianciulli, Paolo

    2009-01-01

    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. PMID:21415999

  19. Comparative Assessment of Complex Stabilities of Radiocopper Chelating Agents by a Combination of Complex Challenge and in vivo Experiments.

    PubMed

    Litau, Shanna; Seibold, Uwe; Vall-Sagarra, Alicia; Fricker, Gert; Wängler, Björn; Wängler, Carmen

    2015-07-01

    For (64) Cu radiolabeling of biomolecules to be used as in vivo positron emission tomography (PET) imaging agents, various chelators are commonly applied. It has not yet been determined which of the most potent chelators--NODA-GA ((1,4,7-triazacyclononane-4,7-diyl)diacetic acid-1-glutaric acid), CB-TE2A (2,2'-(1,4,8,11-tetraazabicyclo[6.6.2]hexadecane-4,11-diyl)diacetic acid), or CB-TE1A-GA (1,4,8,11-tetraazabicyclo[6.6.2]hexadecane-4,11-diyl-8-acetic acid-1-glutaric acid)--forms the most stable complexes resulting in PET images of highest quality. We determined the (64) Cu complex stabilities for these three chelators by a combination of complex challenge and an in vivo approach. For this purpose, bioconjugates of the chelating agents with the gastrin-releasing peptide receptor (GRPR)-affine peptide PESIN and an integrin αv β3 -affine c(RGDfC) tetramer were synthesized and radiolabeled with (64) Cu in excellent yields and specific activities. The (64) Cu-labeled biomolecules were evaluated for their complex stabilities in vitro by conducting a challenge experiment with the respective other chelators as challengers. The in vivo stabilities of the complexes were also determined, showing the highest stability for the (64) Cu-CB-TE1A-GA complex in both experimental setups. Therefore, CB-TE1A-GA is the most appropriate chelating agent for *Cu-labeled radiotracers and in vivo imaging applications. PMID:26011290

  20. Decorporation of Pu/Am Actinides by Chelation Therapy: New Arguments in Favor of an Intracellular Component of DTPA Action.

    PubMed

    Grémy, Olivier; Laurent, David; Coudert, Sylvie; Griffiths, Nina M; Miccoli, Laurent

    2016-06-01

    Diethylenetriaminepentaacetic acid (DTPA) is currently still the only known chelating drug that can be used for decorporation of internalized plutonium (Pu) and americium (Am). It is generally assumed that chelation occurs only in biological fluids, thus preventing Pu/Am deposition in target tissues. We postulate that actinide chelation may also occur inside cells by a mechanism called "intracellular chelation". To test this hypothesis, rats were given DTPA either prior to (termed "prophylactic" treatment) or belatedly after (termed "delayed" treatment) Pu/Am injection. DTPA decorporation efficacy was systematically tested for both plutonium and americium. Both prophylactic and delayed DTPA elicited marked decreases in liver Pu/Am. These results can be explained by chelation within subcellular compartments where DTPA efficacy increased as a function of a favorable intracellular DTPA-to-actinide molar ratio. The efficacy of intracellular chelation of liver actinides decreased with the delay of treatment. This is probably explained by progressive actinide binding to the high-affinity ligand ferritin followed by migration to lysosomes. Intracellular chelation was reduced as the gap between prophylactic treatment and contamination increased. This may be explained by the reduction of the intracellular DTPA pool, which declined exponentially with time. Skeletal Pu/Am was also reduced by prophylactic and delayed DTPA treatments. This decorporation of bone actinides may mainly result from extracellular chelation on bone surfaces. This work provides converging evidence for the involvement of an intracellular component of DTPA action in the decorporation process. These results may help to improve the interpretation of biological data from DTPA-treated contamination cases and could be useful to model DTPA therapy regimens. PMID:27195610

  1. Determination of fatty acids in soil samples by gas chromatography with mass spectrometry coupled with headspace solid-phase microextraction using a homemade sol-gel fiber.

    PubMed

    Shuai, Qin; Ding, Xiaoxiao; Huang, Yunjie; Xu, Shuangshuang; Xu, Shengrui; Gao, Qiang; Deng, Haidong

    2014-11-01

    Through the use of a homemade sol-gel-derived fiber, a headspace solid-phase microextraction technique coupled to gas chromatography with mass spectrometry was developed for the determination of fatty acids with long, even-numbered carbon chains (C12 -C24 ) in soil samples. The experimental parameters such as reaction time, temperature, and ionic strength that might affect derivatization, extraction, and desorption were investigated. Under the optimized conditions, the linearity of the method ranged from 0.1 to 100 mg/L with a correlation coefficient >0.997. The limit of detection values based on a signal-to-noise ratio of 3:1 were determined with the concentration from 0.39 to 39.4 μg/L. The recoveries of the method for the soil samples were from 91.15 to 108.1%. This developed method using a homemade fiber showed a higher sensitivity than that using a commercial polydimethylsiloxane fiber and was also for the analysis of real soil samples from the Paomaling geological park of China. PMID:25168645

  2. Characterization of cytoprotective and toxic properties of iron chelator SIH, prochelator BSIH and their degradation products.

    PubMed

    Jansová, Hana; Bureš, Jan; Macháček, Miloslav; Hašková, Pavlína; Jirkovská, Anna; Roh, Jaroslav; Wang, Qin; Franz, Katherine J; Kovaříková, Petra; Šimůnek, Tomáš

    2016-03-28

    Free cellular iron catalyzes the formation of toxic hydroxyl radicals and therefore chelation of iron could be a promising therapeutic approach in pathological states associated with oxidative stress. Salicylaldehyde isonicotinoyl hydrazone (SIH) is a strong intracellular iron chelator with well documented potential to protect against oxidative damage both in vitro and in vivo. Due to the short biological half-life of SIH and risk of toxicity due to iron depletion, boronate prochelator BSIH has been designed. BSIH cannot bind iron until it is activated by certain reactive oxygen species to active chelator SIH. The aim of this study was to examine the toxicity and cytoprotective potential of BSIH, SIH, and their decomposition products against hydrogen peroxide-induced injury of H9c2 cardiomyoblast cells. Using HPLC, we observed that salicylaldehyde was the main decomposition products of SIH and BSIH, although a small amount of salicylic acid was also detected. In the case of BSIH, the concentration of formed salicylaldehyde consistently exceeded that of SIH. Isoniazid and salicylic acid were not toxic nor did they provide any antioxidant protective effect in H9c2 cells. In contrast, salicylaldehyde was able to chelate intracellular iron and significantly preserve cellular viability and mitochondrial inner membrane potential induced by hydrogen peroxide. However it was consistently less effective than SIH. The inherent toxicities of salicylaldehyde and SIH were similar. Hence, although SIH - the active chelating agent formed following the BSIH activation - undergoes rapid hydrolysis, its principal decomposition product salicylaldehyde accounts markedly for both cytoprotective and toxic properties. PMID:27046792

  3. Iron-[S,S']-EDDS (FeEDDS) Chelate as an Iron Source for Horticultural Crop Production: Marigold Growth and Nutrition, Spectral Properties, and Photodegradation

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  4. Ruthenium recovery from acetic acid industrial effluent using chemically stable and high-performance polyethylenimine-coated polysulfone-Escherichia coli biomass composite fibers.

    PubMed

    Kim, Sok; Choi, Yoon-E; Yun, Yeoung-Sang

    2016-08-01

    Recovery of precious metal ions from waste effluents is of high concern. In general, ruthenium (Ru) is used in the Cativa process as promoter for carbonylation catalyst and discharged into acetic acid effluent. In the present work, we have designed and developed polyethylenimine-coated polysulfone-bacterial biomass composite fiber (PEI-PSBF) to recover Ru from industrial effluent. The sorbent was manufactured by electrostatic attachment of polyethylenimine (PEI) to the surface of polysulfone-biomass composite fiber (PSBF), which was prepared through spinning of the mixture of polysulfone and Escherichia coli biomass in N,N-dimethylformamide (DMF) into water. Developed PEI-PSBF was highly stable in the acetic acid effluent. The maximum sorption capacity of the developed sorbent PEI-PSBF, coated with PEI (with M.W. of 75,000), was 121.28±13.15mg/g, which was much higher than those of ion exchange resins, TP214, Amberjet 4200, and M500. The PEI-PSBF could be successfully applied in the flow-through column system, showing 120 beds of breakthrough volume. PMID:27045623

  5. Chelation in metal intoxication. XIV. Comparative effect of thiol and amino chelators on lead-poisoned rats with normal or damaged kidneys

    SciTech Connect

    Tandon, S.K.; Flora, S.J.; Singh, S.

    1985-06-30

    D-Penicillamine (DPA), diethyldithiocarbamate (DDC), L-cysteine, ethylenediaminetetraacetic acid (EDTA), cyclohexylenediaminetetraacetic acid (CDTA), and diethylene triamine pentaacetic acid (DTPA) were compared for their efficacy to enhance urinary excretion of Pb, to reduce Pb concentration of body organs, and to restore the enhanced urinary excretion of delta-aminolevulinic acid (delta-ALA), the inhibited activities of blood delta-ALA dehydratase, and renal enzymes in Pb-administered rats (10 mg/kg, po, 4 weeks) with normal or experimentally damaged kidneys. The acute renal damage was induced by uranyl acetate (3 mg/kg, sc, once) prior to treatment with the chelators (0.3 mmol/kg, ip, twice) and evaluated by enhanced urinary excretion of diagnostic enzymes and inhibition in their renal activities. Among thiol chelators, DPA was the most effective followed by DDC in enhancing the urinary excretion of Pb, reducing the concentration of Pb in blood, kidneys and liver, and in restoring Pb-induced biological alterations in urine, blood, and kidneys. Among amino carboxylic acids, DTPA was the most effective and EDTA and CDTA were about equally potent in countering Pb toxicity. Protection was more marked in animals with normal kidneys than in those with acutely damaged kidneys.

  6. Chelators whose affinity for calcium is decreased by illumination

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

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

    PubMed

    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

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

    PubMed Central

    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

  9. BN Bonded BN fiber article from boric oxide fiber

    DOEpatents

    Hamilton, Robert S.

    1978-12-19

    A boron nitride bonded boron nitride fiber article and the method for its manufacture which comprises forming a shaped article with a composition comprising boron oxide fibers and boric acid, heating the composition in an anhydrous gas to a temperature above the melting point of the boric acid and nitriding the resulting article in ammonia gas.

  10. An enzymatic approach to bifunctional chelating agents.

    PubMed

    Minazzi, Paolo; Lattuada, Luciano; Menegotto, Ivan G; Giovenzana, Giovanni B

    2014-09-21

    Bifunctional chelating agents (BFCAs) combine the complexing properties of a multidentate ligand with the presence of a free reactive functional group, mainly devoted to conjugation purposes. Indeed, products obtained by conjugation of a BFCA to a biomolecule and coordination of a suitable metal ion are widely applied in medicine nowadays as diagnostic and therapeutic agents. BFCAs are generally prepared through multi-step syntheses and with extensive application of protection-deprotection strategies, due to the large number of functional groups involved. Hydrolytic enzymes, with their unique chemoselectivity, provided the best results in the preparation of three different BFCAs based on very useful and well known ligand platforms. PMID:25060174

  11. Metal regeneration of iron chelates in nitric oxide scrubbing

    DOEpatents

    Chang, Shih-Ger; Littlejohn, David; Shi, Yao

    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.degree. and 90.degree. C. to reduce NO present, produce ammonia or an ammonium ion, and produce free iron (II) (CHELATE) at a pH of between about 3 and 8. The process is useful to remove NO from flue gas and reduce pollution.

  12. Metal regeneration of iron chelates in nitric oxide scrubbing

    DOEpatents

    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.

  13. Chemical treatment of chelated metal finishing wastes.

    PubMed

    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

  14. Lead toxicosis of captive vultures: case description and responses to chelation therapy

    PubMed Central

    2013-01-01

    Background Lead, a serious threat for raptors, can hamper the success of their conservation. This study reports on experience with accidental lead intoxication and responses to chelation therapy in captive Cinereous (Aegypius monachus) and Egyptian (Neophron percnopterus) Vultures. Results Soil contamination by lead-based paint sanded off the steel aviary resulted in poisoning of eight Cinereous and two Egyptian Vultures. A male Egyptian Vulture developed signs of apathy, polydipsia, polyuria, regurgitation, and stupor, and died on the next day. Liver, kidney and blood lead concentrations were 12.2, 8.16 and 2.66 μg/g, respectively. Laboratory analyses confirmed severe liver and kidney damage and anaemia. Blood Pb levels of Pb-exposed Cinereous Vultures were 1.571 ± 0.510 μg/g shortly after intoxication, decreased to 0.530 ± 0.165 μg/g without any therapy in a month and to 0.254 ± 0.097 μg/g one month after CaNa2EDTA administration. Eight months later, blood lead levels decreased to close to the background of the control group. Blood parameters of healthy Pb-non-exposed Cinereous Vultures were compared with those of the exposed group prior to and after chelation therapy. Iron levels in the lead-exposed pre-treatment birds significantly decreased after chelation. Haematocrit levels in Pb-exposed birds were significantly lower than those of the controls and improved one month after chelation. Creatine kinase was higher in pre-treatment birds than in the controls but normalised after therapy. Alkaline phosphatase increased after chelation. A marked increase in the level of lipid peroxidation measured as thiobarbituric acid reactive species was demonstrated in birds both prior to and after chelation. The ferric reducing antioxidant power was significantly lower in pre-treatment vultures and returned to normal following chelation therapy. Blood metallothionein levels in lead-exposed birds were higher than in controls. Reduced glutathione dropped after

  15. Vegetable fiber fermentation by human fecal bacteria: cell wall polysaccharide disappearance and short-chain fatty acid production during in vitro fermentation and water-holding capacity of unfermented residues.

    PubMed

    Bourquin, L D; Titgemeyer, E C; Fahey, G C

    1993-05-01

    Dietary fiber from eight vegetables (broccoli, carrot, cauliflower, celery, cucumber, lettuce, onion and radish) was analyzed for chemical composition and potential in vitro fermentation by human fecal bacteria. Total dietary fiber concentration of substrates ranged from 34.9 (broccoli) to 5.8 (cucumber) g/kg edible matter. Substrate fiber fractions were composed primarily of pectic substances and cellulose with smaller concentrations of hemicelluloses and lignin. Total dietary fiber residues isolated from substrates were fermented in vitro for 24 h with fecal bacteria obtained from each of three human volunteers. Substrate dry matter disappearance during fermentation was highest for carrot (63.7%) and lowest for cucumber (49.4%). Averaged across all substrates, disappearances of arabinose, galactose, glucose, mannose, xylose and uronic acids during fermentation were 96, 90, 54, 68, 51 and 97%, respectively. Short-chain fatty acid (SCFA) production during substrate fermentation averaged 10.5 mmol SCFA/g dry matter fermented. Averaged across all substrates, production of the major SCFA, acetate, propionate and butyrate, occurred in the molar ratio 76:14:10. Potential water-holding capacity of substrates was not influenced by fiber source and averaged 2.04 g H2O/g original substrate dry matter. Extent of substrate fermentation, SCFA production and substrate potential water-holding capacity were significantly different among inoculum donors, indicating that considerable inter-individual variation exists in the potential in vivo fermentation of vegetable fiber. PMID:8387579

  16. Lead analysis by anti-chelate fluorescence polarization immunoassay.

    PubMed

    Johnson, David K; Combs, Sherry M; Parsen, John D; Jolley, Michael E

    2002-03-01

    Lead concentrations were determined by a fluorescence polarization immunoassay (FPIA) method that uses polyclonal antibodies raised against the lead(II) chelate of ethylenediamine-N,N,N',N'-tetraacetic acid (EDTA). The technique is based on competition for a fixed concentration of antibody binding sites between Pb-EDTA, formed by treating the sample with excess EDTA, and a fixed concentration of a fluorescent analogue of the Pb-EDTA complex. The objective was to correlate results obtained by FPIA with those produced by conventional atomic spectroscopy analysis of soils, solid waste leachates (produced by the Toxicity Characteristic Leachate Procedure; TCLP), airborne dust, and drinking water. Linear regression analysis of FPIA results for 138 soil samples containing 0-3094 ppm Pb(II) by flame atomic absorption spectroscopy and 40 TCLP extracts containing 0-668 ppm Pb(II) by inductively coupled plasma atomic emission spectroscopy produced correlation coefficients (r2) of 0.96 and 0.93, respectively. Pilot studies of mineral acid extracts of airborne dust trapped on fiberglass filters and of two sources of drinking water demonstrated the feasibility of also measuring lead in these matrixes by FPIA. The limit of detection under conditions that minimized sample dilution was approximately 1 ppb, and cross reactivity with 15 nontarget metals was below 0.5% in all cases. The methods are simple to perform and are amenable to field testing and mobile laboratory use, allowing timely and cost-effective characterization of suspected sources of lead contamination. PMID:11917989

  17. Dietary Fiber

    MedlinePlus

    Fiber is a substance in plants. Dietary fiber is the kind you eat. It's a type of carbohydrate. You may also see it listed on a food label as soluble fiber or insoluble fiber. Both types have important health benefits. Good sources of dietary fiber include Whole grains Nuts ...

  18. In vitro characterization of the impact of selected dietary fibers on fecal microbiota composition and short chain fatty acid production.

    PubMed

    Yang, Junyi; Martínez, Inés; Walter, Jens; Keshavarzian, Ali; Rose, Devin J

    2013-10-01

    The effects of six dietary fibers [pectin, guar gum, inulin, arabinoxylan, β-glucan, and resistant starch] on the human fecal microbiota during in vitro fermentation were determined. Bifidobacterium increased almost 25% on pectin compared with the control; a significant increase in Bifidobacterium adolescentis type-2 was observed on resistant starch. Bacteroides exhibited a positive correlation with propionate/short chain fatty acid (SCFA) production (r = 0.59, p < 0.01), while Ruminococcaceae and Faecalibacterium displayed positive correlations with butyrate/SCFA production (r = 0.39, 0.54, p < 0.01). A negative correlation was detected between inulin utilization and Subdoligranulum (r = -0.73, p ≤ 0.01), while strong positive relationships were found between β-glucan utilization and Firmicutes (r = 0.73, p ≤ 0.01) and resistant starch utilization and Blautia wexlerae (r = 0.82, p < 0.01). Dietary fibers have specific and unique impacts on intestinal microbiota composition and metabolism. These findings provide a rationale for the development of functional ingredients targeted towards a targeted modulation of the gut microbiota. PMID:23831725

  19. XAS studies of the effectiveness of iron chelating treatments of Mary Rose timbers

    NASA Astrophysics Data System (ADS)

    Berko, A.; Smith, A. D.; Jones, A. M.; Schofield, E. J.; Mosselmans, J. F. W.; Chadwick, A. V.

    2009-11-01

    The oxidation of sulfur in marine archaeological timbers under museum storage conditions is a recently identified problem, particularly for major artefacts such as historic ships excavated from the seabed. Recent work on the Vasa has stressed the role of iron in catalysing the oxidative degradation of the wood cellulose and the polyethylene glycols used to restore mechanical integrity to the timbers. In developing new treatment protocols for the long term preservation of Henry VIII of England's flagship, the Mary Rose, we are investigating the potential of chelating agents to neutralise and remove the iron products from the ships timbers. We have explored the use of aqueous solutions of chelating agents of calcium phytate, ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA) and ammonium citrate to extract the iron compounds. All of these solutions exhibit some level of iron removal; however the key is to find the most effective concentration at pH of around 7 of the reagent solution, to minimise the treatment time and find the most cost-effective treatment for the whole of the Mary Rose hull. Fe K-edge XAFS data from samples of Mary Rose timbers, before and after treatment by the chelating agents mentioned has been collected. The data collected provide valuable insights into the effectiveness of the treatment solutions.

  20. Synergistic effect of chelators and Herbaspirillum sp. GW103 on lead phytoextraction and its induced oxidative stress in Zea mays.

    PubMed

    Govarthanan, Muthusamy; Kamala-Kannan, Seralathan; Kim, Seol Ah; Seo, Young-Seok; Park, Jung-Hee; Oh, Byung-Taek

    2016-10-01

    Phytoremediation is an in situ, low-cost strategy for cleanup of the sites contaminated with heavy metals. Experiments were conducted to assess the impact of synthetic chelators and plant growth-promoting rhizosphere bacteria (Herbaspirillum sp. GW103) on heavy metal lead (Pb) uptake in Z. mays cultivated in Pb-contaminated soil. The present study investigated the Pb phytoaccumulation rate and plant antioxidant enzyme activities in Z. mays exposed to 100 mg/kg of PbNO3. The combination of gluconic acid (GA) with Herbaspirillum sp. GW103 treatment showed higher Pb solubility (18.9 mg/kg) compared with other chelators. The chemical chelators showed the significant difference in phytoaccumulation as well as antioxidant enzyme activities. The antioxidant enzymes such as catalase, peroxidase and superoxide dismutase activities changed under Pb stress. The study indicated that increased activity of antioxidant enzymes may play as signal inducers to fight against Pb. PMID:27154571

  1. Chelation Treatment for Autism Spectrum Disorders: A Systematic Review

    ERIC Educational Resources Information Center

    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…

  2. Carboxyethylester-polyrotaxanes as a new calcium chelating polymer: synthesis, calcium binding and mechanism of trypsin inhibition.

    PubMed

    Ooya, Tooru; Eguchi, Masaru; Ozaki, Atsushi; Yui, Nobuhiko

    2002-08-21

    A carboxyethylester-polyrotaxane was synthesized as a novel calcium chelating polymer in the field of oral drug delivery and characterized in terms of mechanism of trypsin inhibition. Here, carboxyethylester (CEE) groups are introduced to all the primary hydroxyl groups in alpha-cyclodextrins (alpha-CDs), which are threaded onto a poly(ethylene glycol) chain capped with bulky end-groups (polyrotaxane). The solubility of the CEE-polyrotaxane in physiological conditions increased with pH, indicating ionization-related solubility similar to conventional polyacrylates. The ability of calcium (Ca2+) chelation was found to increase in the order of poly(acrylic acid) (PAA)>CEE-polyrotaxanez.Gt;CEE-alpha-CD, suggesting that the increased density of carboxyl groups enhances the Ca2+ chelating ability. The activity of trypsin was inhibited by these compounds in the same order of the calcium chelation. However, the inhibitory effect of CEE-polyrotaxane was reduced by adding excess Ca2+ without precipitation that was observed in the presence of PAA. Such the reduced inhibition and precipitation by CEE-alpha-CD was not observed. Therefore, the inhibitory effect of CEE-polyrotaxane is due to Ca2+ chelation from trypsin without non-specific interaction. PMID:12176224

  3. Monitoring the effects of chelating agents and electrical fields on active forms of Pb and Zn in contaminated soil.

    PubMed

    Tahmasbian, Iman; Safari Sinegani, Ali Akbar

    2013-11-01

    The application of electrical fields and chelating agents is an innovative hybrid technology used for the decontamination of soil polluted by heavy metals. The effects of four center-oriented electrical fields and chelating agents on active fractions of lead and zinc were investigated in this pot experiment. Ethylenediaminetetraacetic acid (EDTA) as a synthetic chelator and cow manure extract (CME) and poultry manure extract (PME) as natural chelators were applied to the pots (2 g kg(-1)) 30 days after the first irrigation. Two weeks later, four center-oriented electrical fields were applied in each pot (in three levels of 0, 10, and 30 V) for 1 h each day for 14 days. The soil near the cathode and anodes was collected and analyzed as cathodic and anodic soil, respectively. Results indicated that the soluble-exchangeable fraction of lead and zinc were decreased in the cathodic soil, while the carbonate-bound fractions were increased. In the anodic soil, however, the opposite result was observed. EDTA enhanced the soluble-exchangeable form of the metals in both anodic and cathodic soils. Furthermore, the amounts of carbonate-bound heavy metals were increased by the application of CME in both soils. The organic-bound fraction of the metals was increased by the application of natural chelators, while electrical fields had no significant impacts on this fraction. PMID:23685981

  4. Synthetic approaches to mixed ligand chelators on t-butylphenol-formaldehyde oligomer (PFO) platforms

    PubMed Central

    Young, Jennifer A.; Karmakar, Sukhen

    2012-01-01

    Synthetic approaches to mixed ligand chelators on readily available t-butylphenol-formaldehyde oligomer, PFO, scaffolds were examined. In a promising approach, tris and tetraphenol oligomers were selectively mono or di protected using t-butyldiphenyl silyl chloride. The utility of these protected intermediates to prepare representative mixed PFO chelators, carrying ligands such as hydroxamic acid, 3,2-hydroxypyridinones and others was then demonstrated. The introduction of the ligand tethers onto the phenolic scaffold can be done sequentially under relatively mild conditions that tolerate the presence of other sensitive ligand groups. The differential reactivity of the disilyl derivative 20b, allowed stepwise introduction of two different ligands on the internal phenolic positions. This enabled the introduction of three different ligand groups of choice onto the tetra phenol platform. PMID:23226883

  5. A Simple and Sensitive Method to Quantify Biodegradable Nanoparticle Biodistribution using Europium Chelates

    PubMed Central

    Crawford, Lindsey; Higgins, Jaclyn; Putnam, David

    2015-01-01

    The biodistribution of biodegradable nanoparticles can be difficult to quantify. We report a method using time resolved fluorescence (TRF) from a lanthanide chelate to minimize background autofluorescence and maximize the signal to noise ratio to detect biodegradable nanoparticle distribution in mice. Specifically, antenna chelates containing europium were entrapped within nanoparticles composed of polylactic acid-polyethylene glycol diblock copolymers. Tissue accumulation of nanoparticles following intravenous injection was quantified in mice. The TRF of the nanoparticles was found to diminish as a second order function in the presence of serum and tissue compositions interfered with the europium signal. Both phenomena were corrected by linearization of the signal function and calculation of tissue-specific interference, respectively. Overall, the method is simple and robust with a detection limit five times greater than standard fluorescent probes. PMID:26346817

  6. The Ca(2+)-EDTA chelation as standard reaction to validate Isothermal Titration Calorimeter measurements (ITC).

    PubMed

    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

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

    PubMed Central

    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 of using principles of metal chelation in medicinal contexts beyond the traditional notion of chelation therapy. These strategies include altering metal biodistribution, inhibiting specific metalloenzymes associated with disease, enhancing the reactivity of a metal complex to promote cytotoxicity, and conversely, passivating the reactivity of metals by site-activated chelation to prevent cytotoxicity. PMID:23332666

  8. Chelators for copper radionuclides in positron emission tomography radiopharmaceuticals†

    PubMed Central

    Cai, Zhengxin; Anderson, Carolyn J.

    2014-01-01

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

  9. Chelating Agents and the Regulation of Metal Ions

    PubMed Central

    Bulman, Robert A.

    1994-01-01

    Up to about the early 1980s it was perhaps still possible to summarize in a review of a moderate length the development of the medicinal applications of chelation chemistry and the exploitation of such chemistry in regulating the metal ion concentrations in the body. However, in the last few years there has a great surge in the development of chelation chemistry and its usage in medicine and related areas of life sciences research. It is no longer the case that such a review primarily concentrates upon the use of chelating agents in removing toxic metals from the body but it must now cover the use of chelating agents in the imaging procedures nuclear medicine and magnetic resonance imaging (MRI), the use of chelating agents in unravelling the biochemistry of reactive oxidative species (ROS) and the control and measurement of intracellular calcium ions. It is in the recent applications that there have been the greatest developments over the last ten years. PMID:18476223

  10. Novel pendant-type macrocyclic bifunctional chelating agents: (Carboxymethyl)amino derivatives of 2-(4-nitrobenzyl)-1,4,7,10-tetraazacyclo-dodecane-N,N{prime},N{double_prime},N{prime}{double_prime}-tetraacetic acid and their complex formation with yttrium(III)

    SciTech Connect

    Takenouchi, Kazuya; Tabe, Masayasu; Watanabe, Kenzo

    1993-11-19

    The authors investigated novel synthetic routes to pendant-type {rho}-NO{sub 2}-BZ-DOTA, 1 and 2, containing a (carboxymethyl) amino group appended to the DOTA structure via a methylene (1) and an ethylene (2) spacer, respectively. The complexation of Yttrium (III) with these chelates is reported. 1 fig., 1 tab.

  11. Chelating ionic liquids for reversible zinc electrochemistry.

    PubMed

    Kar, Mega; Winther-Jensen, Bjorn; Forsyth, Maria; MacFarlane, Douglas R

    2013-05-21

    Advanced, high energy-density, metal-air rechargeable batteries, such as zinc-air, are of intense international interest due to their important role in energy storage applications such as electric and hybrid vehicles, and to their ability to deal with the intermittency of renewable energy sources such as solar and wind. Ionic liquids offer a number of ideal thermal and physical properties as potential electrolytes in such large-scale energy storage applications. We describe here the synthesis and characterisation of a family of novel "chelating" ILs designed to chelate and solubilize the zinc ions to create electrolytes for this type of battery. These are based on quaternary alkoxy alkyl ammonium cations of varying oligo-ether side chains and anions such as p-toluene sulfonate, bis(trifluoromethylsulfonyl)amide and dicyanoamides. This work shows that increasing the ether chain length in the cation from two to four oxygens can increase the ionic conductivity and reduce the melting point from 67 °C to 15 °C for the tosylate system. Changing the anion also plays a significant role in the nature of the zinc deposition electrochemistry. We show that zinc can be reversibly deposited from [N(222(20201))][NTf2] and [N(222(202020201))][NTf2] beginning at -1.4 V and -1.7 V vs. SHE, respectively, but not in the case of tosylate based ILs. This indicates that the [NTf2] is a weaker coordinating anion with the zinc cation, compared to the tosylate anion, allowing the coordination of the ether chain to dominate the behavior of the deposition and stripping of zinc ions. PMID:23558696

  12. The effects of repeated parenteral administration of chelating agents on the distribution and excretion of uranium

    SciTech Connect

    Domingo, J.L.; Ortega, A.; Llobet, J.M.; Paternain, J.L.; Corbella, J.

    1989-04-01

    The effects of repeated ip administration of gallic acid, 4,5-dihydroxy-1,3-benzenedisulfonic acid (Tiron), diethylenetriaminepentaacetic acid (DTPA), and 5-aminosalicylic acid (5-AS) on the distribution and excretion of uranium were assessed in male Swiss mice. Only Tiron significantly increased the amount of uranium excreted into urine and feces. A significant decrease in the concentration of uranium in liver, spleen and bone was observed after administration of Tiron, whereas injection of gallic acid or DTPA resulted in a significant decrease in the concentration of the metal in the liver. The results show that Tiron was consistently the most effective chelator of those tested in the treatment of uranium poisoning after repeated daily administration of the metal.

  13. Determining resin/fiber content of laminates

    NASA Technical Reports Server (NTRS)

    Garrard, G. G.; Houston, D. W.

    1979-01-01

    Article discusses procedure where hydrazine is used to extract graphite fibers from cured polyimide resin. Method does not attack graphite fibers and is faster than hot-concentrated-acid digestion process.

  14. Solubility and accumulation of metals in Chinese brake fern, vetiver and rostrate sesbania using chelating agents.

    PubMed

    Lou, L Q; Ye, Z H; Wong, M H

    2007-01-01

    Greenhouse experiments were conducted to study the effects of chelating agents on the growth and metal accumulation of Chinese brake fern (Pteris vittata L.), vetiver (Vetiveria zizanioides L.), and rostrate sesbania (Sesbania rostrata L.) in soil contaminated with arsenic (As), Cu, Pb, and Zn. Among the five chelating agents used [ethylenediaminetriacetic acid (EDTA), hydroxyethylenediaminetriacetic acid (HEDTA), nitrilotriacetic acid (NTA), oxalic acid (OA), and phytic acid (PA)], OA was the best to mobilize As, EDTA to mobilize Cu and Pb, and HEDTA to mobilize Zn from soil, respectively. The biomass of vetiver was the highest, followed by rostrate sesbania. All chelating agents inhibited the growth of Chinese brake fern and rostrate sesbania, but HEDTA significantly increased the aboveground biomass of vetiver. Dry weights of both Chinese brake fern and rostrate sesbania decreased with increasing EDTA concentrations amended in the soil, especially in treatments with high EDTA concentrations. EDTA and HEDTA enhanced Cu, Zn, and Pb, but lowered As accumulation in all three plant species, except for As in vetiver, while OA significantly enhanced As accumulation in the aboveground part of vetiver. Concentrations of Cu, Zn, and Pb in the aboveground parts of plants increased significantly with the increase of EDTA concentrations and treatment time. In addition to As, Chinese brake fern also accumulated the highest Cu, Pb, and Zn in its aboveground parts among the three plant species grown in metal-contaminated soil with EDTA/HEDTA treatments. This species, therefore, can be used to simultaneously clean up As, Cu, Pb, and Zn from contaminated soils with the aid of EDTA or HEDTA. PMID:18246709

  15. Nature of impurities in fertilizers containing EDDHMA/Fe(3+), EDDHSA/Fe(3+), and EDDCHA/Fe(3+) chelates.

    PubMed

    Alvarez-Fernández, Ana; Cremonini, Mauro A; Sierra, Miguel A; Placucci, Giuseppe; Lucena, Juan J

    2002-01-16

    Iron chelates derived from ethylenediaminedi(o-hydroxyphenylacetic) acid (EDDHA), ethylenediaminedi(o-hydroxy-p-methylphenylacetic) acid (EDDHMA), ethylenediaminedi(2-hydroxy-5-sulfophenylacetic) acid (EDDHSA), and ethylenediaminedi(5-carboxy-2-hydroxyphenylacetic) acid (EDDCHA) are remarkably efficient in correcting iron chlorosis in plants growing in alkaline soils. This work reports the determination of impurities in commercial samples of fertilizers containing EDDHMA/Fe(3+), EDDHSA/Fe(3+), and EDDCHA/Fe(3+). The active components (EDDHMA/Fe(3+), EDDHSA/Fe(3+), and EDDCHA/Fe(3+)) were separated easily from other compounds present in the fertilizers by HPLC. Comparison of the retention times and the UV-visible spectra of the peaks obtained from commercial EDDHSA/Fe(3+) and EDDCHA/Fe(3+) samples with those of standard solutions showed that unreacted starting materials (p-hydroxybenzenesulfonic acid and p-hydroxybenzoic acid, respectively) were always present in the commercial products. 1D and 2D NMR experiments showed that commercial fertilizers based on EDDHMA/Fe(3+) contained impurities having structures tentatively assigned to iron chelates of two isomers of EDDHMA. These findings suggest that current production processes of iron chelates used in agriculture need to be improved. PMID:11782196

  16. Analysis of the Microbial Community in an Acidic Hollow-Fiber Membrane Biofilm Reactor (Hf-MBfR) Used for the Biological Conversion of Carbon Dioxide to Methane

    PubMed Central

    Jeon, Byoung Seung; Choi, Okkyoung; Kim, Hyun Wook; Um, Youngsoon; Lee, Dong-Hoon; Sang, Byoung-In

    2015-01-01

    Hydrogenotrophic methanogens can use gaseous substrates, such as H2 and CO2, in CH4 production. H2 gas is used to reduce CO2. We have successfully operated a hollow-fiber membrane biofilm reactor (Hf-MBfR) for stable and continuous CH4 production from CO2 and H2. CO2 and H2 were diffused into the culture medium through the membrane without bubble formation in the Hf-MBfR, which was operated at pH 4.5–5.5 over 70 days. Focusing on the presence of hydrogenotrophic methanogens, we analyzed the structure of the microbial community in the reactor. Denaturing gradient gel electrophoresis (DGGE) was conducted with bacterial and archaeal 16S rDNA primers. Real-time qPCR was used to track changes in the community composition of methanogens over the course of operation. Finally, the microbial community and its diversity at the time of maximum CH4 production were analyzed by pyrosequencing methods. Genus Methanobacterium, related to hydrogenotrophic methanogens, dominated the microbial community, but acetate consumption by bacteria, such as unclassified Clostridium sp., restricted the development of acetoclastic methanogens in the acidic CH4 production process. The results show that acidic operation of a CH4 production reactor without any pH adjustment inhibited acetogenic growth and enriched the hydrogenotrophic methanogens, decreasing the growth of acetoclastic methanogens. PMID:26694756

  17. Determination of perfluorinated sulfonate and perfluorinated acids in tissues of free-living European beaver (castor fiber L.) by d-SPE/ micro-UHPLC-MS/MS.

    PubMed

    Surma, Magdalena; Giżejewski, Zygmunt; Zieliński, Henryk

    2015-10-01

    Perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA) are the main representatives of an rising class of persistent organic pollutants (POPs), perfluorochemicals (PFCs). In this study, determination of selected PFCs concentration in liver, brain, tail, adipose and peritoneum tissues of free-living European beaver (Castor fiber L.) was addressed. Tissue samples, collected from beavers living in Masurian Lakeland (NE Poland), were analyzed by dispersive Solid Phase Extraction (d-SPE) with micro-UHPLC-MS/MS system. In a group of ten selected pefrluorinated compounds only two perfluorinated acids (PFOA and PFNA) and one perfluorinated sulfonate (PFOS) were quantified. PFOA was detected in all analysed tissue samples in both female and male beavers in a range from 0.55 to 0.98ngg(-1) ww whereas PFOS was identified in all analyzed female beaver tissues and only in liver, subcutaneous adipose and peritoneum tissues of male beavers at the concentration level from 0.86 to 5.08ngg(-1) ww. PFNA was only identified in female beaver tissues (liver, subcutaneous adipose and peritoneum) in a range from 1.50 to 6.61ngg(-1) ww. This study demonstrated the bioaccumulation of PFCs in tissue samples collected from beavers living in area known as green lungs of Poland. The results provided in this study indicate for the increasing risk of PFCs occurrence in the environment and the level of PFCs in tissue of free-living European beavers may serve as bioindicator of environmental pollution by these compounds. PMID:26143169

  18. Hollow fiber liquid-phase microextraction coupled with gas chromatography-flame ionization detection for the profiling of fatty acids in vegetable oils.

    PubMed

    Siang, Gan Hui; Makahleh, Ahmad; Saad, Bahruddin; Lim, Boey Peng

    2010-12-24

    The development of a two phase hollow fiber liquid-phase microextraction technique, followed by gas-chromatography-flame ionization detection (GC-FID) for the profiling of the fatty acids (FAs) (lauric, myristic, palmitic, stearic, palmitoleic, oleic, linoleic, linolenic and arachidic) in vegetable oils is described. Heptadecanoic acid methyl ester was used as the internal standard. The FAs were transesterified to their corresponding methyl esters prior to the extraction. Extraction parameters such as type of extracting solvent, temperature, extraction time, stirring speed and salt addition were studied and optimized. Recommended conditions were extraction solvent, n-tridecane; extraction time, 35 min; extraction temperature, ambient; without addition of salt. Enrichment factors varying from 37 to 115 were achieved. Calibration curves for the nine FAs were well correlated (r(2)>0.994) within the range of 10-5000 μg L(-1). The limit of detection (signal:noise, 3) was 4.73-13.21 ng L(-1). The method was successfully applied to the profiling of the FAs in palm oils (crude, olein, kernel, and carotino cooking oil) and other vegetable oils (soybean, olive, coconut, rice bran and pumpkin). The encouraging enrichments achieved offer an interesting option for the profiling of the minor and major FAs in palm and other vegetable oils. PMID:21081239

  19. Surface-Deacetylated Chitin Nano-Fiber/Hyaluronic Acid Composites as Potential Antioxidative Compounds for Use in Extended-Release Matrix Tablets

    PubMed Central

    Anraku, Makoto; Tabuchi, Ryo; Ifuku, Shinsuke; Ishiguro, Takako; Iohara, Daisuke; Hirayama, Fumitoshi

    2015-01-01

    In this study, we examined a possible use of a surface-deacetylated chitin nano-fiber (SDCH-NF) and hyaluronic acid (HA) interpolymer complex (IPC) tablet as a potential antioxidative compound in extended-release matrix tablets. The antioxidant properties of untreated chitin (UCH), SDCH-NF, and HA were examined using N-centered radicals derived from 1,1′-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). SDCH-NF and HA had acceptable scavenging abilities and were relatively efficient radical scavengers, but UCH was much less effective. The results suggest that SDCH-NF and HA could serve as scavengers of compounds related to the development of oxidative stress. An SDCH-NF/HA IPC tablet was prepared and evaluated as an extended-release tablet matrix using famotidine (FMT) as a model drug. The release of FMT from the IPC tablet (DCF-NF:HA = 1:1) was slower than that from a SDCH-NF only tablet. Turbidity measurements and X-ray diffraction (XRD) data also indicated that the optimum complexation ratio for IPC between SDCH-NF/HA is 1/1, resulting in a good relationship between turbidity or XRD of the complex and the release ratio of FMT. These results suggest that an SDCH-NF/HA tablet has the potential for use in an extended-release IPC tablet with a high antioxidant activity. PMID:26501272

  20. Analysis of the Microbial Community in an Acidic Hollow-Fiber Membrane Biofilm Reactor (Hf-MBfR) Used for the Biological Conversion of Carbon Dioxide to Methane.

    PubMed

    Shin, Hyun Chul; Ju, Dong-Hun; Jeon, Byoung Seung; Choi, Okkyoung; Kim, Hyun Wook; Um, Youngsoon; Lee, Dong-Hoon; Sang, Byoung-In

    2015-01-01

    Hydrogenotrophic methanogens can use gaseous substrates, such as H2 and CO2, in CH4 production. H2 gas is used to reduce CO2. We have successfully operated a hollow-fiber membrane biofilm reactor (Hf-MBfR) for stable and continuous CH4 production from CO2 and H2. CO2 and H2 were diffused into the culture medium through the membrane without bubble formation in the Hf-MBfR, which was operated at pH 4.5-5.5 over 70 days. Focusing on the presence of hydrogenotrophic methanogens, we analyzed the structure of the microbial community in the reactor. Denaturing gradient gel electrophoresis (DGGE) was conducted with bacterial and archaeal 16S rDNA primers. Real-time qPCR was used to track changes in the community composition of methanogens over the course of operation. Finally, the microbial community and its diversity at the time of maximum CH4 production were analyzed by pyrosequencing methods. Genus Methanobacterium, related to hydrogenotrophic methanogens, dominated the microbial community, but acetate consumption by bacteria, such as unclassified Clostridium sp., restricted the development of acetoclastic methanogens in the acidic CH4 production process. The results show that acidic operation of a CH4 production reactor without any pH adjustment inhibited acetogenic growth and enriched the hydrogenotrophic methanogens, decreasing the growth of acetoclastic methanogens. PMID:26694756

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

    PubMed Central

    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 heart of enzymes with a metal cofactor such as copper or zinc. Peptides glutathione and metallothionein chelate both essential and toxic elements as they are sequestered, transported, and excreted. Enhancing natural chelation detoxification pathways, as well as use of pharmaceutical chelators against heavy metals are reviewed. Historical adverse outcomes with chelators, lessons learned in the art of using them, and successes using chelation to ameliorate renal, cardiovascular, and neurological conditions highlight the need for renewed attention to simple, safe, inexpensive interventions that offer potential to stem the tide of debilitating, expensive chronic disease. PMID:23690738

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

    PubMed Central

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

    2013-01-01

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

  3. Active Insolubilized Antibiotics Based on Cellulose-Metal Chelates1

    PubMed Central

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

    1974-01-01

    Cellulose was converted into a more reactive form by chelation with the transition metals titaniumIII, ironIII, tinIV, vanadiumIII, and zirconiumIV. The remaining unsubstituted ligands of the transition metal ions were found to be amenable to replacement by electron-donating groups of antibiotic molecules. Ampicillin, gentamicin, kanamycin, neomycin, paromomycin, polymyxin B, and streptomycin were used as antibacterial antibiotics, and amphotericin B and natamycin were used as antifungal antibiotics. Antibacterial activity of the products was tested against two gram-positive and two gram-negative bacteria, and antifungal activity was tested against four fungi. That the antibacterial antibiotics had complexed with the cellulose-metal chelates was demonstrated in that the product cellulose-metal-antibiotic chelates exhibited antibiotic activities whereas the metal chelates of cellulose themselves were inactive. Of 140 tests conducted, cellulose-metal-antibiotic chelates were active in 102 cases. Since the antibiotic derivatives were water insoluble and in fact retain some of the antibacterial activities of the parent compounds, the chelation method provides a facile way of rendering cellulose surfaces, etc., resistant to microbial attack over and above that degree of protection afforded by noncovalent adsorption of the antibiotic to cellulose itself. The underlying principles of the chelation reactions involved are discussed in detail. PMID:4451349

  4. Nanoparticle and Iron Chelators as a Potential Novel Alzheimer Therapy

    PubMed Central

    Liu, Gang; Men, Ping; Perry, George; Smith, Mark A.

    2010-01-01

    Current therapies for Alzheimer disease (AD) such as the acetylcholinesterase inhibitors and the latest NMDA receptor inhibitor, Namenda, provide moderate symptomatic delay at various stages of the disease, but do not arrest the disease progression or bring in meaningful remission. New approaches to the disease management are urgently needed. Although the etiology of AD is largely unknown, oxidative damage mediated by metals is likely a significant contributor since metals such as iron, aluminum, zinc, and copper are dysregulated and/or increased in AD brain tissue and create a pro-oxidative environment. This role of metal ion-induced free radical formation in AD makes chelation therapy an attractive means of dampening the oxidative stress burden in neurons. The chelator desferrioxamine, FDA approved for iron overload, has shown some benefit in AD, but like many chelators, it has a host of adverse effects and substantial obstacles for tissue-specific targeting. Other chelators are under development and have shown various strengths and weaknesses. Here, we propose a novel system of chelation therapy through the use of nanoparticles. Nanoparticles conjugated to chelators show unique ability to cross the blood–brain barrier (BBB), chelate metals, and exit through the BBB with their corresponding complexed metal ions. This method may provide a safer and more effective means of reducing the metal load in neural tissue, thus attenuating the harmful effects of oxidative damage and its sequelae. Experimental procedures are presented in this chapter. PMID:20013176

  5. Chelating agents and their use in radiopharmaceutical sciences.

    PubMed

    Wängler, B; Schirrmacher, R; Bartenstein, P; Wängler, C

    2011-10-01

    Radiometal nuclides can serve as diagnostic markers in molecular imaging or can be used in therapeutic settings for a rising number of human afflictions. For the targeted delivery of these medically interesting ions, appropriate chelating agents forming stable complexes are of fundamental importance. For different metal ions exhibiting different physical and chemical properties, resulting in different coordination chemistries and therefore differing requirements on the chelator used, a broad variety of chelating agents has been developed over the years. Not only the chemical properties of the metal ion determine the choice of the chelator, but also the desired in vivo behavior of the resulting molecular imaging or therapeutic compound influences the choice of the complexation agent. Furthermore, the conjugation chemistry for the introduction of the chelator into the biologically active compound and the complexation reaction of the metal ion can affect the choice of the appropriate chelator. This review outlines chelating agents used in medicinal chemistry, their radiometal complexation behavior and their potential influence on the properties of the resulting drugs. PMID:21762096

  6. Effects of Organic Chelation on the Behavior of Aluminum Relative to Gallium During Pedogenesis

    NASA Astrophysics Data System (ADS)

    Herz, M. M.; Derry, L. A.

    2003-12-01

    This study of gallium and aluminum behavior in the soil weathering environment provides a first step toward using Ga/Al as a tracer of aluminum dynamics during pedogenesis. Previously, the interpretation of aluminum behavior in soils was confounded by the monoisotopic nature of aluminum and its subsequent lack of a comparative tracer. Like aluminum, gallium is a strongly hydrolyzing group III element. It is included in the same mineral systems as aluminum and the two are believed to have similar chemistries in most natural environments. Aluminum is a highly toxic metal whose removal from mineral matrices is enhanced by acid deposition and chelation by organic ligands. As much as 80% of dissolved aluminum in upper soil horizons can be complexed by organic ligands, most of which are secreted by plant and soil microorganisms to detoxify their surroundings. However, gallium makes comparatively unstable complexes with organic chelators, and is not expected to be carried into solution or leached from the soil profile by them to the same extent as aluminum. The Hawaiian Islands provide a unique opportunity to study the evolution of aluminum and gallium concentrations during soil development along gradients where age or climate varies, but all other soil forming factors are held constant. Ga/Al in older and more intensely weathered soils can be as high as 2.58 (mg/g), whereas the basaltic parent material is almost 10 times lower (0.30 mg/g). The factor driving soil Ga/Al ratios away from those found in parent material may be the strong control that organic chelation exerts over aluminum mobility. The enhancement of aluminum dissolution by organic chelation can be inferred from the decrease in Ga/Al ratios of exchangeable cations along a gradient of increasing rainfall; where wetter, more organic rich sites have Ga/Al ratios 10 to 100 times lower than drier sites where organic chelation is a less important factor in driving aluminum dynamics. Along this same gradient, the

  7. Fiber biology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotton fiber cells arising from seed epidermis is the most important agricultural textile commodity in the world. To produce fully mature fibers, approximately two months of fiber developmental process are required. The timing of four distinctive fiber development stages consisting of initiation, ...

  8. Effect of endodontic chelating solutions on the bond strength of endodontic sealers.

    PubMed

    Tuncel, Behram; Nagas, Emre; Cehreli, Zafer; Uyanik, Ozgur; Vallittu, Pekka; Lassila, Lippo

    2015-01-01

    The purpose of this in vitro study was to evaluate the effect of various chelating solutions on the radicular push-out bond strength of calcium silicate-based and resin-based root canal sealers. Root canals of freshly-extracted single-rooted teeth (n = 80) were instrumented by using rotary instruments. The specimens were randomly divided into 4 groups according to the chelating solutions being tested: (1) 17% ethylenediaminetetraacetic acid (EDTA); (2) 9% etidronic acid; (3) 1% peracetic acid (PAA); and (4) distilled water (control). In each group, the roots were further assigned into 2 subgroups according to the sealer used: (1) an epoxy resin-based sealer (AH Plus) and (2) a calcium silicate-based sealer (iRoot SP). Four 1 mm-thick sections were obtained from the coronal aspect of each root (n = 40 slices/group). Push-out bond strength test was performed at a crosshead speed of 1 mm/min., and the bond strength data were analyzed statistically with two-way analysis of variance (ANOVA) with Bonferroni's post hoc test (p < 0.05). Failure modes were assessed quantitatively under a stereomicroscope. Irrespective of the irrigation regimens, iRoot SP exhibited significantly higher push-out bond strength values than AH Plus (p < 0.05). For both the sealers, the use of chelating solutions increased the bond strength, but to levels that were not significantly greater than their respective controls (p > 0.05). iRoot SP showed higher resistance to dislocation than AH Plus. Final irrigation with 17% EDTA, 9% Etidronic acid, and 1% PAA did not improve the bond strength of AH Plus and iRoot SP to radicular dentin. PMID:25992788

  9. Metal distribution and spectroscopic analysis after soil washing with chelating agents and humic substances.

    PubMed

    Tsang, Daniel C W; Hartley, Neil R

    2014-03-01

    Biodegradable chelating agents ([S,S]-ethylenediamine-N,N-disuccinic acid (EDDS) and glutamic-N,N-diacetic acid (GLDA)) and natural humic substances (lignite-derived, standard, and commercially available humic acids) are potentially useful for enhancing soil remediation of timber treatment sites. This study integrated macroscopic and spectroscopic analyses to assess their influence on the distribution and chemical speciation of the remaining metals as well as their interaction with the soil surface after 48-h washing of a field-contaminated soil. The results demonstrated that EDDS and GLDA were an appealing alternative to non-biodegradable ethylenediamine-tetraacetic acid, but the three humic substances were less effective. As shown by sequential extractions, Cu was primarily extracted from the carbonate fraction while Cr and As extraction resulted from (co-)dissolution of the oxide fraction. As a result, the relative proportion of strongly bound organic matter and residual fractions increased by 7-16 %. However, it was noteworthy that the exchangeable fraction also increased by 5-11 %, signifying that a portion of the remaining metals was destabilized by chelating agents and transformed to be more labile in the treated soil. The X-ray photoelectron spectroscopy spectra confirmed the substantial removal of readily accessible Cu from the soil surface, but Cr maintained its original chemical forms of trivalent chromium oxides and iron-chromium coprecipitates, whereas As remained as arsenic trioxide/pentoxide and copper arsenate precipitates. On the other hand, the absence of characteristic peaks of adsorbed carboxylate groups in the Fourier-transform infrared (FTIR) spectra inferred that the extent of adsorption of chelating agents and humic substances on the bulk soil was insufficient to be characterized by FTIR analysis. These results suggested that attention should be paid to the exchangeable fraction of Cu and oxides/coprecipitates of As prior to possible on

  10. A Rosemary Extract Rich in Carnosic Acid Selectively Modulates Caecum Microbiota and Inhibits β-Glucosidase Activity, Altering Fiber and Short Chain Fatty Acids Fecal Excretion in Lean and Obese Female Rats

    PubMed Central

    Larrosa, Mar; Obiol, María; García-Villalba, Rocío; González-Barrio, Rocío; Issaly, Nicolas; Flanagan, John; Roller, Marc; Tomás-Barberán, Francisco A.; García-Conesa, María-Teresa

    2014-01-01

    Background Carnosic acid (CA) and rosemary extracts (RE) show body-weight, energy metabolism and inflammation regulatory properties in animal models but the mechanisms are not yet understood. Gut microbiota plays an important role in the host metabolism and inflammatory status and is modulated by the diet. The aim of this research was to investigate whether a RE enriched in CA affected caecum microbiota composition and activity in a rat model of genetic obesity. Methods and Principal Findings A RE (40% CA) was administered with the diet (0.5% w/w) to lean (fa/+) and obese (fa/fa) female Zucker rats for 64 days. Changes in the microbiota composition and β-glucosidase activity in the caecum and in the levels of macronutrients and short chain fatty acids (SCFA) in feces were examined. The RE increased the Blautia coccoides and Bacteroides/Prevotella groups and reduced the Lactobacillus/Leuconostoc/Pediococccus group in both types of animals. Clostridium leptum was significantly decreased and Bifidobacterium increased only in the lean rats. β-Glucosidase activity was significantly reduced and fecal fiber excretion increased in the two genotypes. The RE also increased the main SCFA excreted in the feces of the obese rats but decreased them in the lean rats reflecting important differences in the uptake and metabolism of these molecules between the two genotypes. Conclusions Our results indicate that the consumption of a RE enriched in CA modifies microbiota composition and decreases β-glucosidase activity in the caecum of female Zucker rats while it increases fiber fecal elimination. These results may contribute to explain the body weight gain reducing effects of the RE. The mutated leptin receptor of the obese animals significantly affects the microbiota composition, the SCFA fecal excretion and the host response to the RE intake. PMID:24733124

  11. The role of biomass in polyethylenimine-coated chitosan/bacterial biomass composite biosorbent fiber for removal of Ru from acetic acid waste solution.

    PubMed

    Won, Sung Wook; Kwak, In Seob; Yun, Yeoung-Sang

    2014-05-01

    The present study is aimed at understanding the role of bacterial biomass in functionalizing polyethylenimine (PEI)-coated bacterial biosorbent fiber (PBBF). To make PBBF, chitosan/biomass composite fiber was coated with PEI and then cross-linked by glutaraldehyde. The role of biomass in the fiber was investigated through sorption experiments and SEM, FTIR and XPS analyses with differently prepared fiber sorbents. In the case that the chitosan fiber was made without the biomass, it could not be coated with PEI. Meanwhile, the chitosan/biomass composite fiber could successfully coated with PEI and primary amine groups were significantly increased on the surface of the fiber. Therefore, the biomass should be essential to make PEI-reinforced chitosan fiber. PMID:24524856

  12. Preparation and Evaluation of the Chelating Nanocomposite Fabricated with Marine Algae Schizochytrium sp. Protein Hydrolysate and Calcium.

    PubMed

    Lin, Jiaping; Cai, Xixi; Tang, Mengru; Wang, Shaoyun

    2015-11-11

    Marine algae have been becoming a popular research topic because of their biological implication. The algae peptide-based metal-chelating complex was investigated in this study. Schizochytrium sp. protein hydrolysate (SPH) possessing high Ca-binding capacity was prepared through stepwise enzymatic hydrolysis to a degree of hydrolysis of 22.46%. The nanocomposites of SPH chelated with calcium ions were fabricated in aqueous solution at pH 6 and 30 °C for 20 min, with the ratio of SPH to calcium 3:1 (w/w). The size distribution showed that the nanocomposite had compact structure with a radius of 68.16 ± 0.50 nm. SPH was rich in acidic amino acids, accounting for 33.55%, which are liable to bind with calcium ions. The molecular mass distribution demonstrated that the molecular mass of SPH was principally concentrated at 180-2000 Da. UV scanning spectroscopy and Fourier transform infrared spectroscopy suggested that the primary sites of calcium-binding corresponded to the carboxyl groups, carbonyl groups, and amino groups of SPH. The results of fluorescent spectroscopy, size distribution, atomic force microscope, and (1)H nuclear magnetic resonance spectroscopy suggested that calcium ions chelated with SPH would cause intramolecular and intermolecular folding and aggregating. The SPH-calcium chelate exerted remarkable stability and absorbability under either acidic or basic conditions, which was in favor of calcium absorption in the gastrointestinal tracts of humans. The investigation suggests that SPH-calcium chelate has the potential prospect to be utilized as a nutraceutical supplement to improve bone health in the human body. PMID:26499390

  13. Antioxidant, Metal Chelating, Anti-glucosidase Activities and Phytochemical Analysis of Selected Tropical Medicinal Plants

    PubMed Central

    Wong, Fai-Chu; Yong, Ann-Li; Ting, Evon Peir-Shan; Khoo, Sim-Chyi; Ong, Hean-Chooi; Chai, Tsun-Thai

    2014-01-01

    The purpose of this investigation was to determine the antioxidant potentials and anti-glucosidase activities of six tropical medicinal plants. The levels of phenolic constituents in these medicinal plants were also quantified and compared. Antioxidation potentials were determined colorimetrically for scavenging activities against DPPH and NO radicals. Metal chelating assay was based on the measurement of iron-ferrozine absorbance at 562 nm. Anti-diabetic potentials were measured by using α-glucosidase as target enzyme. Medicinal plants’ total phenolic, total flavonoid and hydroxycinnamic acid contents were determined using spectrophotometric methods, by comparison to standard plots prepared using gallic acid, quercetin and caffeic acid standards, respectively. Radical scavenging and metal chelating activities were detected in all medicinal plants, in concentration-dependent manners. Among the six plants tested, C. nutans, C. formosana and H. diffusa were found to possess α-glucosidase inhibitory activities. Spectrophotometric analysis indicated that the total phenolic, total flavonoid and hydroxycinnamic acid contents ranged from 12.13-21.39 mg GAE per g of dry sample, 1.83-9.86 mg QE per g of dry sample, and 0.91-2.74 mg CAE per g of dry sample, respectively. Our results suggested that C. nutans and C. formosana could potentially be used for the isolation of potent antioxidants and anti-diabetic compounds. To the best of our knowledge, this study represents the first time that C. nutans (Acanthaceae family) was reported in literature with glucosidase inhibition activity. PMID:25587331

  14. Luminescent solutions and powders of new samarium complexes with N,N',O,O'-chelating ligands

    NASA Astrophysics Data System (ADS)

    Kharcheva, Anastasia V.; Nikolskiy, Kirill S.; Borisova, Nataliya E.; Ivanov, Alexey V.; Reshetova, Marina D.; Yuzhakov, Viktor I.; Patsaeva, Svetlana V.

    2016-04-01

    Imaging techniques in biology and medicine are crucial tools to obtain information on structural and functional properties of living cells and organisms. To fulfill the requirements associated with application of these techniques it appears necessary to design markers with specific characteristics. Luminescent complexes of trivalent lanthanide ions with chelating ligands are of increasing importance in biomedical applications because of their millisecond luminescence lifetime, narrow emission band, high signal-to-noise ratio and minimal photodamage to biological samples. In order to extend the available emission wavelength range the luminescent samarium chelates are highly desirable. In this study the ligands with diamides of 2,2'-bipyridin-6,6'-dicarboxylic acid were used to improve photophysical characteristics of samarium complexes. We report the luminescence characteristics of samarium complexes with novel ligands. All complexes exhibited the characteristic emission of Sm (III) ion with the lines at 565, 597, 605, 645 and 654 nm, the intensity strongly depended on the ligand. Absorption and luminescence excitation spectra of Sm (III) complexes showed main peaks in the UV range demonstrating lanthanide coordination to the ligand. The absolute lumenescence quantum yield was measured for solutions in acetonitrile with excitation at 350 nm. The largest luminescence quantum yield was found for the samarium complex Bipy 6MePy Sm (3%) being much higher that for samarium complexes reported in the literature earlier. These results prove as well that samarium chelates are potential markers for multiparametric imaging techniques.

  15. The determination of the rate of conjugation immunoglobuline with bifunctional chelator

    NASA Astrophysics Data System (ADS)

    Málek, Z.; Miler, V.; Budský, F.

    2006-01-01

    The work was performed under the GACR project: "Technology of preparation of radionuclides and their labelled compounds for nuclear medicine and pharmacy with the use of the reactor LVR-15" reg. no. 104/03/0499. Imaging of cell’s antigens with the use of labelled immunoglobulines allows imaging of specific receptors on cell membrane and specific tumours. It is necessary to carry out the labelling of the immunoglobulines with radionuclides of suitable physical properties, which form cations (e.g., 111In, 90Y, 177Lu) that form very strong chelates of sufficiently high stability constant preventing the dissociation of complexes or the radionuclide under “in-vivo” conditions. The immunoglobuline must be conjugated with the bifunctional chelator (BCH), which contains both chelating unit and reactive group for binding to the immunoglobuline. In our laboratory we have conjugated human IgG and monoclonal antibody CD20 with diethylenetriamine pentaacetic acid dianhydride (cDTPAA). Radionuclides 90Y and 177Lu prepared on the LVR-15 reactor in NRI Rez were used for labelling. After conjugation and labelling the yields in relation to the amount of isotopic carrier have been determined.

  16. High-yielding aqueous 18F-labeling of peptides via Al18F chelation.

    PubMed

    D'Souza, Christopher A; McBride, William J; Sharkey, Robert M; Todaro, Louis J; Goldenberg, David M

    2011-09-21

    The coordination chemistry of a new pentadentate bifunctional chelator (BFC), NODA-MPAA 1, containing the 1,4,7-triazacyclononane-1,4-diacetate (NODA) motif with a methylphenylacetic acid (MPAA) backbone, and its ability to form stable Al(18)F chelates were investigated. The organofluoroaluminates were easily accessible from the reaction of 1 and AlF(3). X-ray diffraction studies revealed aluminum at the center of a slightly distorted octahedron, with fluorine occupying one of the axial positions. The tert-butyl protected prochelator 7, which can be synthesized in one step, is useful for coupling to biomolecules on solid phase or in solution. High yield (55-89%) aqueous (18)F-labeling was achieved in 10-15 min with a tumor-targeting peptide 4 covalently linked to 1. Defluorination was not observed for at least 4 h in human serum at 37 °C. These results demonstrate the facile application of Al(18)F chelation using BFC 1 as a versatile labeling method for radiofluorinating other heat-stable peptides for positron emission imaging. PMID:21805975

  17. Actinide chelation: biodistribution and in vivo complex stability of the targeted metal ions.

    PubMed

    Kullgren, Birgitta; Jarvis, Erin E; An, Dahlia D; Abergel, Rebecca J

    2013-01-01

    Because of the continuing use of nuclear fuel sources and heightened threats of nuclear weapon use, the amount of produced and released radionuclides is increasing daily, as is the risk of larger human exposure to fission product actinides. A rodent model was used to follow the in vivo distribution of representative actinides, administered as free metal ions or complexed with chelating agents including diethylenetriamine pentaacetic acid (DTPA) and the hydroxypyridinonate ligands 3,4,3-LI(1,2-HOPO) and 5-LIO(Me-3,2-HOPO). Different metabolic pathways for the different metal ions were evidenced, resulting in intricate ligand- and metal-dependent decorporation mechanisms. While the three studied chelators are known for their unrivaled actinide decorporation efficiency, the corresponding metal complexes may undergo in vivo decomposition and release metal ions in various biological pools. This study sets the basis to further explore the metabolism and in vivo coordination properties of internalized actinides for the future development of viable therapeutic chelating agents. PMID:22957518

  18. A transcript profiling approach reveals an abscisic acid specific glycosyltransferase (UGT73C14) induced in developing fiber of Ligon lintless-2 mutant of cotton (Gossypium hirsutum L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ligon lintless-2, a monogenic dominant cotton (Gossypium hirsutum L.) fiber mutation, causing extreme reduction in lint fiber length with no pleiotropic effects on vegetative growth, represents an excellent model system to study fiber elongation. A UDP-glycosyltransferase that was highly expressed i...

  19. Safety profiles of gadolinium chelates in juvenile rats differ according to the risk of dissociation.

    PubMed

    Fretellier, Nathalie; Maazouz, Meryam; Luseau, Alexandrine; Baudimont, Fannie; Jestin-Mayer, Gaëlle; Bourgery, Simon; Rasschaert, Marlène; Bruneval, Patrick; Factor, Cécile; Mecieb, Fatiha; Idée, Jean-Marc; Corot, Claire

    2014-12-01

    This study was designed to compare the safety of two gadolinium chelates (GCs), used as contrast agents for magnetic resonance imaging, in juvenile rats. Juvenile rats received five intravenous administrations (between postnatal day [PND] 4 and 18) of gadoteric acid (macrocyclic ionic GC), gadodiamide (linear nonionic GC) or saline, and sacrificed at PND 25. Gadodiamide induced mortality, alopecia and hyperpigmentation of dorsal skin. Two gadodiamide-treated rats presented severe epidermal and dermal lesions. No abnormal signs were detected following administration of gadoteric acid. Higher tissue gadolinium concentrations were found in the gadodiamide group compared to the gadoteric acid group. Dissociation of gadodiamide was observed in skin and liver, with the presence of dissociated and soluble gadolinium. In conclusion, repeated administration of gadoteric acid was well tolerated by juvenile rats. In contrast, gadodiamide induced significant toxicity and more marked tissue gadolinium retention (at least partly in the dissociated and soluble form). PMID:25462783

  20. The effect of regioisomerism on the coordination chemistry and CEST properties of lanthanide(III) NB-DOTA-tetraamide chelates

    PubMed Central

    Slack, Jacqueline R.; Woods, Mark

    2014-01-01

    Chemical exchange saturation transfer (CEST) offers many advantages as a method of generating contrast in magnetic resonance images. However, many of the exogenous agents currently under investigation suffer from detection limits that are still somewhat short of what can be achieved with more traditional Gd3+ agents. To remedy this limitation we have undertaken an investigation of Ln3+ DOTA-tetraamide chelates (where DOTA is 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) that have unusually rigid ligand structures: the nitrobenzyl derivatives of DOTA-tetraamides with (2-phenylethyl)amide substituents. In this report we examine the effect of incorporating hydrophobic amide substituents on water exchange and CEST. The ligand systems chosen afforded a total of three CEST-active isomeric square antiprismatic chelates; each of these chelates was found to have different water exchange and CEST characteristics. The position of a nitrobenzyl substituent on the macrocyclic ring strongly influenced the way in which the chelate and Ln3+ coordination cage distorted. These differential distortions were found to affect the rate of water proton exchange in the chelates. But, by far the greatest effect arose from altering the position of the hydrophobic amide substituent, which, when forced upwards around the water binding site, caused a substantial reduction in the rate of water proton exchange. Such slow water proton exchange afforded a chelate that was 4.5 times more effective as a CEST agent than its isomeric counterparts in dry acetonitrile and at low temperatures and very low presaturation powers. PMID:24287873

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

    SciTech Connect

    Lewis, Scott; lynch, Andrew; Bachas, Leonidas; hampson, Steve; Ormsbee, Lindelle; Bhattacharyya, Dibakar

    2008-06-01

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

  2. Assessment of dietary fiber fermentation: effect of Lactobacillus reuteri and reproducibility of short-chain fatty acid concentrations.

    PubMed

    Stewart, Maria L; Savarino, Vincenzo; Slavin, Joanne L

    2009-05-01

    This investigation had two aims: (i) to determine the reproducibility of SCFA production of two fibers: wheat dextrin and inulin, in two separate in vitro batch fermentation systems, and (ii) to determine if the addition Lactobacillus reuteri, a probiotic bacterium, enhanced the fermentation of wheat dextrin, inulin, and psyllium using in vitro batch fermentation. Samples were removed at 0, 4, 8, 12, and 24 h. SCFAs were measured by GC. L. reuteri improved inulin's fermentation profile by reducing the total SCFA peak at 4 h and enhancing fermentation at 8 and 12 h. Wheat dextrin and psyllium were largely unaffected. Wheat dextrin's total SCFA and propionate production curves were steady and replicable, but concentration values varied between fermentations. Partially hydrolyzed guar gum (PHGG) and wheat dextrin had similar fermentation patterns from 0-8 h, but PHGG plateaued at 8 h for all measures. Psyllium produced peak SCFA concentrations at 8 h, similar to inulin. L. reuteri could be combined with inulin for enhancing fermentation, but it does not improve wheat dextrin or psyllium fermentation. Wheat dextrin will likely produce similar physiological within a group of individuals due to the reproducibility of fermentation. PMID:18837468

  3. Why the NIH Trial to Assess Chelation Therapy (TACT) Should Be Abandoned

    PubMed Central

    Atwood, Kimball C.; Woeckner, Elizabeth; Baratz, Robert S.; Sampson, Wallace I.

    2008-01-01

    The National Institutes of Health (NIH) Trial to Assess Chelation Therapy (TACT) was begun in 2003 and is expected to be completed in 2009. It is a trial of office-based, intravenous disodium ethylene-diamine-tetra-acetic acid (Na2EDTA) as a treatment for coronary artery disease (CAD). A few case series in the 1950s and early 1960s had found Na2EDTA to be ineffective for CAD or peripheral vascular disease (PVD). Nevertheless, a few hundred physicians, almost all of whom advocate other dubious treatments, continued to peddle chelation as an office treatment. They claim that chelation dramatically improves symptoms and prolongs life in 80% to 90% of patients. In response, academics performed 4 controlled trials during the 1990s. None favored chelation, but chelationists repudiated those findings. We have investigated the method and the trial. We present our findings in 4 parts: history, origin and nature of the TACT, state of the evidence, and risks. We present evidence that chelationists and their organization, the American College for Advancement in Medicine, used political connections to pressure the NIH to fund the TACT. The TACT protocols justified the trial by misrepresenting case series and by ignoring evidence of risks. The trial employs nearly 100 unfit co-investigators. It conflates disodium EDTA and another, somewhat safer drug. It lacks precautions necessary to minimize risks. The consent form reflects those shortcomings and fails to disclose apparent proprietary interests. The trial's outcome will be unreliable and almost certainly equivocal, thus defeating its stated purpose. We conclude that the TACT is unethical, dangerous, pointless, and wasteful. It should be abandoned. PMID:18596934

  4. Properties, Solution State Behavior, and Crystal Structures of Chelates of DOTMA

    PubMed Central

    Aime, Silvio; Botta, Mauro; Garda, Zoltán; Kucera, Benjamin E.; Tircso, Gyula; Young, Victor G.; Woods, Mark

    2011-01-01

    The chemistry of polyamino carboxylates and their use as ligands for Ln3+ ions is of considerable interest from the point of view of the development of new imaging agents. Of particular interest is the chemistry of the macrocyclic ligand 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and its derivatives. Herein we report that the tetramethylated DOTA derivative, DOTMA, possess several properties that, from an imaging agent development point of view, are more advantageous than those of the parent DOTA. In particular, the Ln3+ chelates of DOTMA exhibit a marked preference for the monocapped twisted square antiprismatic coordination isomer which imparts more rapid water exchange kinetics on the chelates; τM298 was determined to be 85 ns for GdDOTMA. Differential analysis of the 17O R2ρ temperature profiles of both GdDOTA and GdDOTMA afforded the τM298 values for the square (SAP) and twisted square antiprismatic (TSAP) isomers of each chelate that were almost identical: 365 ns (SAP) and 52 ns (TSAP). The origin of this accelerated water exchange in the TSAP isomer appears to be the slightly longer Gd–OH2 bond distance (2.50 Å) that is observed in the crystal structure of GdDOTMA which crystallizes in the P2 space group as a TSAP isomer. The Ln3+ chelates of DOTMA also exhibit high thermodynamic stabilities ranging from log KML = 20.5 for CeDOTMA, 23.5 for EuDOTMA and YbDOTMA comparable to, but a shade lower than, those of DOTA. PMID:21819052

  5. Aminothiol multidentate chelators against Chagas disease.

    PubMed

    Deharo, E; Loyevsky, M; John, C; Balanza, E; Ruiz, G; Muñoz, V; Gordeuk, V R

    2000-03-01

    Three compounds of an aminothiol family of iron chelators were examined for activity against trypomastigote (human) and epimastigote (vector) forms of Trypanosoma cruzi: tetraethyl and tetramethyl derivatives of ethane-1,2-bis (N-1-amino-3-ethyl butyl-3-thiol) (BAT-TE and BAT-TM) and N',N',N'-tris-(2-methyl-2-mercaptopriopyl)- 1,4,7-triazacyclonane (TAT). BAT-TE at 270 microM completely arrested the growth of trypomastigote forms in mouse blood stored at 4 degrees C for 24 h (IC(50) 67.7+/-7 microM), while BAT-TM arrested growth at 630 microM (IC(50) 158+/-17 microM) and TAT at concentrations >800 microM (IC(50) 415+/-55 microM). In T. cruzi-infected mice, BAT-TE and BAT-TM had no anti-trypanosomal activity in doses up to 200 mg/kg, whether the route of administration was intraperitoneal or oral, and TAT was not tested due to insufficient quantity. TAT had an IC(50) of 52+/-7 microM against the epimastigote forms while BAT-TM and BAT-TE were inhibitory only at concentrations >250 microM. The trypanocidal activity of BAT derivatives in blood stored at 4 degrees C makes these compounds potential candidates for the purpose of clearing donated blood of trypomastigotes. PMID:10831386

  6. Making Solid Aromatic Polyimide Fibers

    NASA Technical Reports Server (NTRS)

    St. Clair, Anne K.; Ely, Robert M.; Dorogy, William E., Jr.

    1991-01-01

    Improved wet-spinning process makes aromatic polyamic acid fibers containing no voids, and converts to polyimide fibers also free of voids. Elimination of voids found to improve tensile strength and other tensile properties. Improved polyimide fibers prove useful in protective clothing, sealing materials, filters for harsh chemical and/or thermal environments, and other applications taking advantage of excellent chemical resistance, high thermal stability, and good tensile properties.

  7. Cell assay using a two-photon-excited europium chelate

    PubMed Central

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

    2011-01-01

    We report application of two-photon excitation of europium chelates to immunolabeling of epidermal growth factor receptor (EGFR) cell surface proteins on A431 cancer cells. The europium chelates are excited with two photons of infrared light and emit in the visible. Europium chelates are conjugated to antibodies for EGFR. A431 (human epidermoid carcinoma) cells are labeled with this conjugate and imaged using a multiphoton microscope. To minimize signal loss due to the relatively long-lived Eu3+ emission, the multiphoton microscope is used with scanning laser two-photon excitation and non-scanning detection with a CCD. The chelate labels show very little photobleaching (less than 1% during continuous illumination in the microscope for 20 minutes) and low levels of autofluorescence (less than 1% of the signal from labeled cells). The detection limit of the europium label in the cell assay is better than 100 zeptomoles. PMID:21833362

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Metal chelate process to remove pollutants from fluids

    DOEpatents

    Chang, S.G.T.

    1994-12-06

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

  10. Metal chelate process to remove pollutants from fluids

    DOEpatents

    Chang, Shih-Ger T.

    1994-01-01

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

  11. Strategies for the preparation of bifunctional gadolinium(III) chelators

    PubMed Central

    Frullano, Luca; Caravan, Peter

    2012-01-01

    The development of gadolinium chelators that can be easily and readily linked to various substrates is of primary importance for the development high relaxation efficiency and/or targeted magnetic resonance imaging (MRI) contrast agents. Over the last 25 years a large number of bifunctional chelators have been prepared. For the most part, these compounds are based on ligands that are already used in clinically approved contrast agents. More recently, new bifunctional chelators have been reported based on complexes that show a more potent relaxation effect, faster complexation kinetics and in some cases simpler synthetic procedures. This review provides an overview of the synthetic strategies used for the preparation of bifunctional chelators for MRI applications. PMID:22375102

  12. Effect of pH on the release of radionuclides and chelating agents from cement-solidified decontamination ion-exchange resins collected from operating nuclear power stations

    SciTech Connect

    McIsaac, C.V.; Akers, D.W.; McConnell, J.W. )

    1991-06-01

    Data are presented on the physical stability and leachability of radionuclides and chelating agents from cement-solidified decontamination ion-exchange resin wastes collected from two operating commercial light water reactors. Small-scale waste--form specimens collected during solidifications performed at the Brunswick Steam Electric Plant Unit 1 and at the James A. FitzPatrick Nuclear Power Station were leach-tested and subjected to compressive strength testing in accordance with the Nuclear Regulatory Commission's Technical Position on Waste Form'' (Revision 1). Samples of untreated resin waste collected from each solidification vessel before the solidification process were analyzed for concentrations of radionuclides, selected transition metals, and chelating agents to determine the quantities of these chemicals in the waste-form specimens. The chelating agents included oxalic, citric, and picolinic acids. In order to determine the effect of leachant chemical composition and pH on the stability and leachability of the waste forms, waste-form specimens were leached in various leachants. Results of this study indicate that differences in pH do not affect releases from cement-solidified decontamination ion-exchange resin waste forms, but that differences in leachant chemistry and the presence of chelating agents may affect the releases of radionuclides and chelating agents. Also, this study indicates that the cumulative releases of radionuclides and chelating agents are similar for waste- form specimens that decomposed and those that retained their general physical form. 36 refs., 60 figs., 28 tabs.

  13. Iron Chelation Adherence to Deferoxamine and Deferasirox in Thalassemia

    PubMed Central

    Trachtenberg, Felicia; Vichinsky, Elliott; Haines, Dru; Pakbaz, Zahra; Mednick, Lauren; Sobota, Amy; Kwiatkowski, Janet; Thompson, Alexis A.; Porter, John; Coates, Thomas; Giardina, Patricia J.; Olivieri, Nancy; Yamashita, Robert; Neufeld, Ellis J.

    2015-01-01

    The Thalassemia Clinical Research Network collected adherence information from 79 patients on deferoxamine and 186 on deferasirox from 2007 to 2009. Chelation adherence was defined as percent of doses administered in the last 4 weeks (patient report) out of those prescribed (chart review). Chelation history since 2002 was available for 97 patients currently on deferoxamine and 217 on deferasirox, with crude estimates of adherence from chart review. Self-reported adherence to both deferoxamine and deferasirox were quite high, with slightly higher adherence to the oral chelator (97 vs. 92%). Ninety percent of patients on deferasirox reported at least 90% adherence, compared with 75% of patients on deferoxamine. Adherence to both chelators was highest in children, followed by adolescents and older adults. Predictors of lower deferoxamine adherence were smoking in the past year, problems sticking themselves (adults only), problems wearing their pump, and fewer transfusions in the past year. Predictors of lower deferasirox adherence were bodily pain and depression. Switching chelators resulted in increased adherence, regardless of the direction of the switch, although switching from deferoxamine to deferasirox was far more common. As adherence to deferoxamine is higher than previously reported, it appears beneficial for patients to have a choice in chelators. PMID:21523808

  14. Visible light photocatalytic activity of rutile TiO2 fiber clusters in the degradation of terephthalic acid

    NASA Astrophysics Data System (ADS)

    Yener, H. Banu; Helvacı, Şerife Ş.

    2015-09-01

    Rutile TiO2 nanoparticles, in different structural and morphological properties, were produced by the hydrolysis of titanium tetrachloride in a highly acidic reaction media at moderate temperatures without calcination. Their photocatalytic activities were investigated in the liquid-phase degradation of terephthalic acid under visible light illumination. The parameters, which are the concentration of the titanium tetrachloride solution (0.1-1 M) and reaction temperature (60-95 °C), effective on the properties of the particles, and their photocatalytic performances, were investigated. The XRD patterns indicated a pure rutile crystal structure at moderate temperatures without need of calcination. The FEGSEM images showed the formation of flower-, pinecone-, and sphere-like clusters consisting of interconnected nanofibers. The N2 adsorption-desorption isotherms pointed out the microporous structure of the clusters. Band gap energies were found to be varying between 3.02 and 3.08 eV due to the well-developed rutile crystallite structure. Systematic studies elucidated that the optimum reactant concentration and reaction temperature are 0.5 M TiCl4 and 95 °C, respectively. The rutile clusters synthesized at the optimum reaction conditions exhibited 99 % of the photocatalytic degradation of TPA under visible light illumination at shorter irradiation times compared with commercial P25 TiO2.

  15. Carbon fiber modification

    NASA Technical Reports Server (NTRS)

    Thompson, T. E.

    1979-01-01

    The effect of several chemical treatments on the electrical and mechanical properties of carbon fibers was investigated with an optimum goal of increasing the electrical resistivity by a factor of 1000 without appreciably changing the mechanical properties. It was possible to effect resistivity increases from 10 to 50 percent without adversely affecting the tensile strength or Young's modulus for T-300 and C-6000 PAN fibers by treatments with either AlCl3 or nitric acid mixtures. Larger increases in the resistivity were produced with pitch fibers treated with nitric acid mixtures. This treatment also produced a partial decomposition of the pitch fiber and deterioration of the mechanical properties. The rationale behind the approch was to immobilize the conductivity producing pi electrons in the microscopic aromatic structure of the carbon fibers without destroying the strength producing sigma bonds. The investigations indicate that certain chemical treatments can produce such results, but the total reduction in the electrical conductivity which was achieved was not large enough to impact on problems which might arise from the high conductivities of the fibers.

  16. Synthesis and application of lactosylated, 99mTc chelating albumin for measurement of liver function.

    PubMed

    Chaumet-Riffaud, Philippe; Martinez-Duncker, Ivan; Marty, Anne-Laure; Richard, Cyrille; Prigent, Alain; Moati, Frederic; Sarda-Mantel, Laure; Scherman, Daniel; Bessodes, Michel; Mignet, Nathalie

    2010-04-21

    Neogalactosylated and neolactosylated albumins are currently used as radiopharmaceutical agents for imaging the liver asialoglycoprotein receptors, which allows the quantification of hepatic liver function in various diseases and also in healthy liver transplant donors. We developed an original process for synthesizing a chelating neolactosylated human albumin using maleimidopropyl-lactose and maleimidopropyl-diethylene triamine pentaacetic acid (DTPA) derivatives. The lactosylated protein (LACTAL) conjugate showed excellent liver uptake compared to nonlactosylated protein and a very high signal-to-noise ratio, based on functional assessment of biodistribution in mice using (99m)Tc-scintigraphy. PMID:20201600

  17. Highly nucleophilic dipropanolamine chelated boron reagents for aryl-transmetallation to iron complexes.

    PubMed

    Dunsford, Jay J; Clark, Ewan R; Ingleson, Michael J

    2015-12-21

    New aryl- and heteroarylboronate esters chelated by dipropanolamine are synthesised directly from boronic acids. The corresponding anionic borates are readily accessible by deprotonation and demonstrate an increase in hydrocarbyl nucleophilicity in comparison to other common borates. The new borates proved competent for magnesium or zinc additive-free, direct boron-to-iron hydrocarbyl transmetallations with well-defined iron(II) (pre)catalysts. The application of the new borate reagents in representative Csp(2)-Csp(3) cross-coupling led to almost exclusive homocoupling unless coupling is performed in the presence of a zinc additive. PMID:26554484

  18. [Surface characterization of urushiol-titanium chelate polymers by inverse gas chromatography].

    PubMed

    Xu, Yanlian; Lin, Jinhuo; Xia, Jianrong; Hu, Binghuan

    2011-03-01

    Urushiol-titanium chelate polymer (UTP), the reaction product of urushiol with titanium compound, is a special eco-friendly polymer with excellent performances, such as strong acids-resistance, strong alkalis-resistance, salt solution-resistance and several organic solvent-resistance. Inverse gas chromatography (IGC) was used to measure the dispersive component of surface free energy (gamma(s)d) and the Lewis acid-base parameters of UTP in this work. The gamma(s)d and the acid/base characters of UTP' surfaces were estimated by the retention time with different non-polar and polar probes at infinite dilution region. n-Pentane (C5), n-hexane (C6), n-heptane (C7), n-octane (C8) and n-nonane (C9) were chosen as the non-polar probes to characterize the gamma(s)d. Trichloromethane (CHCl3), tetrahydrofuran (THF) and acetone were chosen as polar probes to detect the Lewis acid-base parameters. The specific free energy (deltaG(a)AB) and the enthalpy (deltaH(a)AB) of adsorption corresponding to acid-base surface interactions were determined. By correlating deltaH(a)AB with the donor and acceptor numbers of the probes, the acidic (K(a)) and the basic (K(b)) parameters of the samples were calculated. The results showed that the dispersive components of the free energy of UTP were 37.68, 33.53, 35.92, 24.01 and 31.32 mJ/m2 at 70, 80, 90, 100 and 110 degrees C, respectively. The Lewis acidic number K(a) of UTP was 0.185 3, and the Lewis basic number K(b) was 0.966 2. The results were of great importance to the study of the surface properties and the applications for urushiol-metal chelate polymers. PMID:21657056

  19. The Structural Basis of Action of Vanadyl (VO2+) Chelates in Cells

    PubMed Central

    Makinen, Marvin W.; Salehitazangi, Marzieh

    2014-01-01

    extravascular space. Serum albumin, as the most abundant transport protein in the blood stream, serves commonly as the carrier protein for small molecules, and transcytosis of albumin through capillary endothelium is regulated by a Src protein tyrosine kinase system. In this respect it is of interest to note that inorganic VO2+ has the capacity to enhance insulin receptor kinase activity of intact 3T3-L1 adipocytes in the presence of albumin, albeit weak; however, in the presence of transferrin no activation is observed. In addition to facilitating glucose uptake, the capacity of VO2+- chelates for insulin-like, antilipolytic action in primary adipocytes has also been reviewed. We conclude that measurement of inhibition of release of only free fatty acids from adipocytes stimulated by epinephrine is not a sufficient basis to ascribe the observations to purely insulin-mimetic, antilipolytic action. Adipocytes are known to contain both phosphodiesterase-3 and phosphodiesterase-4 (PDE3 and PDE4) isozymes, of which insulin antagonizes lipolysis only through PDE3B. It is not known whether the other isozyme in adipocytes is influenced directly by VO2+- chelates. In efforts to promote improved development of VO2+- chelates for therapeutic purposes, we propose synergism of a reagent with insulin as a criterion for evaluating physiological and biochemical specificity of action. We highlight two organic compounds that exhibit synergism with insulin in cellular assays. Interestingly, the only VO2+- chelate for which this property has been demonstrated, thus far, is VO(acac)2. PMID:25237207

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

    PubMed

    Makinen, Marvin W; Salehitazangi, Marzieh

    2014-11-01

    the extravascular space. Serum albumin, as the most abundant transport protein in the blood stream, serves commonly as the carrier protein for small molecules, and transcytosis of albumin through capillary endothelium is regulated by a Src protein tyrosine kinase system. In this respect it is of interest to note that inorganic VO(2+) has the capacity to enhance insulin receptor kinase activity of intact 3T3-L1 adipocytes in the presence of albumin, albeit weak; however, in the presence of transferrin no activation is observed. In addition to facilitating glucose uptake, the capacity of VO(2+)- chelates for insulin-like, antilipolytic action in primary adipocytes has also been reviewed. We conclude that measurement of inhibition of release of only free fatty acids from adipocytes stimulated by epinephrine is not a sufficient basis to ascribe the observations to purely insulin-mimetic, antilipolytic action. Adipocytes are known to contain both phosphodiesterase-3 and phosphodiesterase-4 (PDE3 and PDE4) isozymes, of which insulin antagonizes lipolysis only through PDE3B. It is not known whether the other isozyme in adipocytes is influenced directly by VO(2+)- chelates. In efforts to promote improved development of VO(2+)- chelates for therapeutic purposes, we propose synergism of a reagent with insulin as a criterion for evaluating physiological and biochemical specificity of action. We highlight two organic compounds that exhibit synergism with insulin in cellular assays. Interestingly, the only VO(2+)- chelate for which this property has been demonstrated, thus far, is VO(acac)2. PMID:25237207

  1. A Transcript Profiling Approach Reveals an Abscisic Acid-Specific Glycosyltransferase (UGT73C14) Induced in Developing Fiber of Ligon lintless-2 Mutant of Cotton (Gossypium hirsutum L.)

    PubMed Central

    Gilbert, Matthew K.; Bland, John M.; Shockey, Jay M.; Cao, Heping; Hinchliffe, Doug J.; Fang, David D.; Naoumkina, Marina

    2013-01-01

    Ligon lintless-2, a monogenic dominant cotton (Gossypium hirsutum L.) fiber mutation, causing extreme reduction in lint fiber length with no pleiotropic effects on vegetative growth, represents an excellent model system to study fiber elongation. A UDP-glycosyltransferase that was highly expressed in developing fibers of the mutant Ligon lintless-2 was isolated. The predicted amino acid sequence showed ~53% similarity with Arabidopsis UGT73C sub-family members and the UDP-glycosyltransferase was designated as UGT73C14. When expressed in Escherichia coli as a recombinant protein with a maltose binding protein tag, UGT73C14 displayed enzymatic activity toward ABA and utilized UDP-glucose and UDP-galactose as the sugar donors. The recombinant UGT73C14 converted natural occurring isoform (+)-cis, trans-ABA better than (+)-trans, trans-ABA and (-)-cis, trans-ABA. Transgenic Arabidopsis plants constitutively overexpressing UGT73C14 did not show phenotypic changes under standard growth conditions. However, the increased glycosylation of ABA resulted in phenotypic changes in post-germinative growth and seedling establishment, confirming in vivo activity of UGT73C14 for ABA. This suggests that the expression level of UGT73C14 is regulated by the observed elevated levels of ABA in developing fibers of the Li2 mutant line and may be involved in the regulation of ABA homeostasis. PMID:24086489

  2. The magnesium chelation step in chlorophyll biosynthesis

    SciTech Connect

    Weinstein, J.

    1990-11-01

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

  3. High aspect ratio nanoimprinted grooves of poly(lactic-co-glycolic acid) control the length and direction of retraction fibers during fibroblast cell division.

    PubMed

    Su, Yi-Hsuan; Chiang, Po-Chieh; Cheng, Li-Jing; Lee, Chau-Hwang; Swami, Nathan S; Chou, Chia-Fu

    2015-01-01

    Retraction fibers (RFs) determine orientation of the cell division axis and guide the spreading of daughter cells. Long and unidirectional RFs, which are especially apparent during mitosis of cells in three-dimensional (3D) environments, enable improved control over cell fate, following division. However, 3D gel environments lack the cues necessary for predetermining the orientation of RFs to direct tissue architecture. While patterning of focal adhesion regions by microcontact printing can determine orientation of the RFs through enhancing focal adhesion numbers along particular directions, the RFs remain short due to the two-dimensional culture environment. Herein, the authors demonstrate that nanoimprinted grooves of polylactic acid glycolic acid (PLGA) with a high aspect ratio (A.R. of 2.0) can provide the cues necessary to control the direction of RFs, as well as enable the maintenance of long and unidirectional RFs as observed within 3D cultures, while the same is not possible with PLGA grooves of lower A.R. (1.0 or lower). Based on enhanced levels of contact guidance of premitotic fibroblast protrusions at high A.R. grooves and deeper levels of focal adhesion due to filopodia extensions into these grooves, it is suggested that submicron (800 nm width) PLGA grooves with A.R. of 2 are capable of supporting mechanical forces from cell protrusions to a greater depth, thereby enabling the maintenance of the protrusions as long and unidirectional RFs during cell division. Given the scalability and versatility of nanoimprint techniques, the authors envision a platform for designing nanostructures to direct tissue regeneration and developmental biology. PMID:26652706

  4. Method for preparing radionuclide-labeled chelating agent-ligand complexes

    DOEpatents

    Meares, Claude F.; Li, Min; DeNardo, Sally J.

    1999-01-01

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

  5. Biconical tapered optical fiber biosensor for measuring refractive index of a-amino acids in aqueous D-glucose and sucrose solution

    NASA Astrophysics Data System (ADS)

    Zibaii, M. I.; Latifi, H.; Karami, M.; Gholami, M.; Hosseini, S. M.; Ghezelayagh, M. H.

    2010-04-01

    A single-mode biconical tapered optical fiber (BTOF) sensor was utilized for sensing the variation of refractive index (RI) with concentration of D-glucose in double distilled deionized water and measuring of RI of amino acids (AAs) in carbohydrate solutions. This method showed a rewarding ability in understanding the basis of biomolecular interactions in biological systems. The BTOF is fabricated by heat pulling method, utilizing a CO2 laser. The detection limit of the BTOF was 50 ppb for the D-glucose concentration ranging from 0 to 80 ppm, and RI detection limit corresponding to these concentrations in the range at 1.3333 to 1.3404 was 5.4×10-6 as a refractometer sensor. The response of the BTOF shows that the different kinds of interactions of various groups of AAs such as L-alanine, L-leucine, and L-cystein with D-glucose, sucrose and water molecules depend on functional groups in AAs such as OH, SH;CH2;NH3+ ,COO-. These results can be interpreted in terms of solute-solute and solute-solvent interactions and structure making/breaking ability of solutes in the given solution.

  6. Cannabidiolic acid, a major cannabinoid in fiber-type cannabis, is an inhibitor of MDA-MB-231 breast cancer cell migration.

    PubMed

    Takeda, Shuso; Okajima, Shunsuke; Miyoshi, Hiroko; Yoshida, Kazutaka; Okamoto, Yoshiko; Okada, Tomoko; Amamoto, Toshiaki; Watanabe, Kazuhito; Omiecinski, Curtis J; Aramaki, Hironori

    2012-11-15

    Cannabidiol (CBD), a major non-psychotropic constituent of fiber-type cannabis plant, has been reported to possess diverse biological activities, including anti-proliferative effect on cancer cells. Although CBD is obtained from non-enzymatic decarboxylation of its parent molecule, cannabidiolic acid (CBDA), few studies have investigated whether CBDA itself is biologically active. Results of the current investigation revealed that CBDA inhibits migration of the highly invasive MDA-MB-231 human breast cancer cells, apparently through a mechanism involving inhibition of cAMP-dependent protein kinase A, coupled with an activation of the small GTPase, RhoA. It is established that activation of the RhoA signaling pathway leads to inhibition of the mobility of various cancer cells, including MDA-MB-231 cells. The data presented in this report suggest for the first time that as an active component in the cannabis plant, CBDA offers potential therapeutic modality in the abrogation of cancer cell migration, including aggressive breast cancers. PMID:22963825

  7. Cannabidiolic acid, a major cannabinoid in fiber-type cannabis, is an inhibitor of MDA-MB-231 breast cancer cell migration

    PubMed Central

    Takeda, Shuso; Okajima, Shunsuke; Miyoshi, Hiroko; Yoshida, Kazutaka; Okamoto, Yoshiko; Okada, Tomoko; Amamoto, Toshiaki; Watanabe, Kazuhito; Omiecinski, Curtis J.; Aramaki, Hironori

    2014-01-01

    Cannabidiol (CBD), a major non-psychotropic constituent of fiber-type cannabis plant, has been reported to possess diverse biological activities, including anti-proliferative effect on cancer cells. Although CBD is obtained from non-enzymatic decarboxylation of its parent molecule, cannabidiolic acid (CBDA), few studies have investigated whether CBDA itself is biologically active. Results of the current investigation revealed that CBDA inhibits migration of the highly invasive MDA-MB-231 human breast cancer cells, apparently through a mechanism involving inhibition of cAMP-dependent protein kinase A, coupled with an activation of the small GTPase, RhoA. It is established that activation of the RhoA signaling pathway leads to inhibition of the mobility of various cancer cells, including MDA-MB-231 cells. The data presented in this report suggest for the first time that as an active component in the cannabis plant, CBDA offers potential therapeutic modality in the abrogation of cancer cell migration, including aggressive breast cancers. PMID:22963825

  8. Enhanced capacitance performance of Al₂O₃-TiO₂ composite thin film via sol-gel using double chelators.

    PubMed

    Du, Xianfeng; Men, Kai; Xu, Youlong; Li, Bing; Yang, Zhuo; Liu, Zihan; Li, Long; Li, Liang; Feng, Tianyu; Wasif ur Rehman; Ullah, Inam; Mao, Shengchun

    2015-04-01

    Titanium dioxide (TiO2) is usually introduced into dielectric layer of aluminum electrolytic capacitor to enhance capacitance performance via forming Al2O3-TiO2 composite film. However, there is a big obstacle caused by high crystallization temperature of TiO2 to capacitance enhancement. In present work, a facile route was proposed to synthesize crystalline TiO2 with the size of 3-10 nm at room temperature using lactic acid (LA) and acetylacetone (Acac) as double chelators. After being introduced into the surface of etched aluminum foils as dielectric layer, TiO2 boosted the specific capacitance by about 24% compared to that without TiO2, and about 11% compared to that with TiO2 using lactic acid as only chelator. PMID:25554973

  9. Apatite coating of electrospun PLGA fibers using a PVA vehicle system carrying calcium ions.

    PubMed

    Kim, In Ae; Rhee, Sang-Hoon

    2010-01-01

    A novel method to coat electrospun poly(D,L-lactic-co-glycolic acid) (PLGA) fiber surfaces evenly and efficiently with low-crystalline carbonate apatite crystals using a poly(vinyl alcohol) (PVA) vehicle system carrying calcium ions was presented. A non-woven PLGA fabric was prepared by electrospinning: a 10 wt% PLGA solution was prepared using 1,1,3,3-hexafluoro-2-propanol as a solvent and electrospun under a electrical field of 1 kV/cm using a syringe pump with a flowing rate of 3 ml/h. The non-woven PLGA fabric, 12 mm in diameter and 1 mm in thickness, was cut and then coated with a PVA solution containing calcium chloride dihydrate (specimen PPC). As controls, pure non-woven PLGA fabric (specimen P) and fabric coated with a calcium chloride dihydrate solution without PVA (specimen PC) were also prepared. Three specimens were exposed to simulated body fluid for 1 week and this exposure led to form uniform and complete apatite coating layer on the fiber surfaces of specimen PPC. However, no apatite had formed to the fiber surfaces of specimen P and only inhomogeneous coating occurred on the fiber surfaces of specimen PC. These results were explained in terms of the calcium chelating and adhesive properties of PVA vehicle system. The practical implication of the results is that this method provides a simple but efficient technique for coating the fiber surface of an initially non-bioactive material with low-crystalline carbonate apatite. PMID:20507712

  10. Synthesis of Naphthalimidedioxime Ligand-Containing Fibers for Uranium Adsorption from Seawater

    DOE PAGESBeta

    Chatterjee, Sabornie; Bryantsev, Vyacheslav S.; Brown, Suree; Johnson, J. Casey; Grant, Christopher D.; Mayes, Richard T.; Hay, Benjamin P.; Dai, Sheng; Saito, Tomonori

    2015-12-16

    Uranium exists as uranyl carbonates (primarily as [UO2(CO3)3]4-) at a low concentration of 3.3 ppb, in seawater. Due to the ocean's vast volume, the total amount of uranium in seawater has been estimated at 4.5 billion tons or nearly 1000 times more than land-based resources. This large surplus provides attractive solution to supply nuclear fuel feeds in future. However, the presence of a variety of competing metal ions and the low concentration of uranium in seawater make the extraction of uranium from seawater challenging. The goal of this work is to develop adsorbent fibers that can recover uranium from themore » slightly alkaline (pH 8.0 - 8.3) seawater. In this process, radiation-induced graft polymerization (RIGP) is used where fibers are prepared by irradiating and treating polyethylene (PE) with different bulk ratios of vinyl benzyl chloride (VBC) and methacrylic acid (MAA) or itaconic acid. Furthermore, chemical modifications of these fibers were performed via two step processes, where novel bisimidoxime ligands are incorporated into fibers. These ligands contain imidedioxime, which is known to be a uranium-philic functionality. Also, the core structures of these ligands containing three donor atoms facilitate the formation of chelates with uranyl ion in seawater. Density functional theory (DFT) calculations were performed to quantify the binding strength with the uranyl ion. The adsorbent showed moderate to high uranium (~35-50 g-U/kg adsorbent) adsorption capacity in a model seawater with a uranium concentration of 6 ppm at pH 8.0 8.3.« less

  11. Synthesis of Naphthalimidedioxime Ligand-Containing Fibers for Uranium Adsorption from Seawater

    SciTech Connect

    Chatterjee, Sabornie; Bryantsev, Vyacheslav S.; Brown, Suree; Johnson, J. Casey; Grant, Christopher D.; Mayes, Richard T.; Hay, Benjamin P.; Dai, Sheng; Saito, Tomonori

    2015-12-16

    Uranium exists as uranyl carbonates (primarily as [UO2(CO3)3]4-) at a low concentration of 3.3 ppb, in seawater. Due to the ocean's vast volume, the total amount of uranium in seawater has been estimated at 4.5 billion tons or nearly 1000 times more than land-based resources. This large surplus provides attractive solution to supply nuclear fuel feeds in future. However, the presence of a variety of competing metal ions and the low concentration of uranium in seawater make the extraction of uranium from seawater challenging. The goal of this work is to develop adsorbent fibers that can recover uranium from the slightly alkaline (pH 8.0 - 8.3) seawater. In this process, radiation-induced graft polymerization (RIGP) is used where fibers are prepared by irradiating and treating polyethylene (PE) with different bulk ratios of vinyl benzyl chloride (VBC) and methacrylic acid (MAA) or itaconic acid. Furthermore, chemical modifications of these fibers were performed via two step processes, where novel bisimidoxime ligands are incorporated into fibers. These ligands contain imidedioxime, which is known to be a uranium-philic functionality. Also, the core structures of these ligands containing three donor atoms facilitate the formation of chelates with uranyl ion in seawater. Density functional theory (DFT) calculations were performed to quantify the binding strength with the uranyl ion. The adsorbent showed moderate to high uranium (~35-50 g-U/kg adsorbent) adsorption capacity in a model seawater with a uranium concentration of 6 ppm at pH 8.0 8.3.

  12. Dietary Fiber

    MedlinePlus

    Fiber is a substance in plants. Dietary fiber is the kind you eat. It's a type of carbohydrate. You may also see it listed on a food label as soluble ... types have important health benefits. Good sources of dietary fiber include Whole grains Nuts and seeds Fruit and ...

  13. Aspen Tension Wood Fibers Contain β-(1---> 4)-Galactans and Acidic Arabinogalactans Retained by Cellulose Microfibrils in Gelatinous Walls.

    PubMed

    Gorshkova, Tatyana; Mokshina, Natalia; Chernova, Tatyana; Ibragimova, Nadezhda; Salnikov, Vadim; Mikshina, Polina; Tryfona, Theodora; Banasiak, Alicja; Immerzeel, Peter; Dupree, Paul; Mellerowicz, Ewa J

    2015-11-01

    Contractile cell walls are found in various plant organs and tissues such as tendrils, contractile roots, and tension wood. The tension-generating mechanism is not known but is thought to involve special cell wall architecture. We previously postulated that tension could result from the entrapment of certain matrix polymers within cellulose microfibrils. As reported here, this hypothesis was corroborated by sequential extraction and analysis of cell wall polymers that are retained by cellulose microfibrils in tension wood and normal wood of hybrid aspen (Populus tremula × Populus tremuloides). β-(1→4)-Galactan and type II arabinogalactan were the main large matrix polymers retained by cellulose microfibrils that were specifically found in tension wood. Xyloglucan was detected mostly in oligomeric form in the alkali-labile fraction and was enriched in tension wood. β-(1→4)-Galactan and rhamnogalacturonan I backbone epitopes were localized in the gelatinous cell wall layer. Type II arabinogalactans retained by cellulose microfibrils had a higher content of (methyl)glucuronic acid and galactose in tension wood than in normal wood. Thus, β-(1→4)-galactan and a specialized form of type II arabinogalactan are trapped by cellulose microfibrils specifically in tension wood and, thus, are the main candidate polymers for the generation of tensional stresses by the entrapment mechanism. We also found high β-galactosidase activity accompanying tension wood differentiation and propose a testable hypothesis that such activity might regulate galactan entrapment and, thus, mechanical properties of cell walls in tension wood. PMID:26378099

  14. Heavy Metal Displacement in Chelate-Assisted Phytoremediation of Biosolids Soil

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

    Heavy metals in biosolids (sewage sludge) applied to land contaminate the soil. 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 biosolids following solubilization with chelates. The objective of this work was to determine the mobility of heavy metals, as affected by a chelate, in soil (Haynie very fine sandy loam) from a 25-year old sludge farm. Soil columns (105 cm long; 39 cm in diameter) either had a plant (hybrid poplar; Populus deltoides Marsh. x P. nigra L.) or no plant. When the poplars were 144 days old, the tetrasodium salt of the chelating agent EDTA (ethylenediamine-tetraacetic acid) was irrigated onto the soil at a rate of 1 g per kg of soil. Drainage water, soil, and plants were analyzed for three toxic heavy metals (Cd, Ni, Pb) and four essential heavy metals (Cu, Fe, Mn, Zn). Without EDTA, concentrations of the seven heavy metals in the leachate from columns with or without plants were low or below detection limits. With or without plants, the EDTA mobilized all heavy metals and increased their concentration in drainage water. Without plants, the concentrations of Cd, Cu, Fe, Pb, and Zn in the leachate from columns with EDTA were above drinking-water standards. (There is no drinking-water standard for Ni.) The presence of poplar plants in the soil reduced the concentrations of Cu, Fe, and Zn in the leachate so it fell within drinking-water standards. Concentrations of Cd and Pb in the leachate remained above drinking-water standards with or without plants. At harvest (124 days after the EDTA application), total concentration of each heavy metal in the soil at different depths in the columns with EDTA was similar to that in the columns without EDTA. The chelate did not affect the concentration of heavy metals in the roots, stems, or leaves

  15. Chelating and antibacterial properties of chitosan nanoparticles on dentin

    PubMed Central

    Bramante, Clovis Monteiro; Duarte, Marco Antonio Hungaro; de Moura, Marcia Regina; Aouada, Fauze Ahmad; Kishen, Anil

    2015-01-01

    Objectives The use of chitosan nanoparticles (CNPs) in endodontics is of interest due to their antibiofilm properties. This study was to investigate the ability of bioactive CNPs to remove the smear layer and inhibit bacterial recolonization on dentin. Materials and Methods One hundred bovine dentin sections were divided into five groups (n = 20 per group) according to the treatment. The irrigating solutions used were 2.5% sodium hypochlorite (NaOCl) for 20 min, 17% ethylenediaminetetraacetic acid (EDTA) for 3 min and 1.29 mg/mL CNPs for 3 min. The samples were irrigated with either distilled water (control), NaOCl, NaOCl-EDTA, NaOCl-EDTA-CNPs or NaOCl-CNPs. After the treatment, half of the samples (n = 50) were used to assess the chelating effect of the solutions using portable scanning electronic microscopy, while the other half (n = 50) were infected intra-orally to examine the post-treatment bacterial biofilm forming capacity. The biovolume and cellular viability of the biofilms were analysed under confocal laser scanning microscopy. The Kappa test was performed for examiner calibration, and the non-parametric Kruskal-Wallis and Dunn tests (p < 0.05) were used for comparisons among the groups. Results The smear layer was significantly reduced in all of the groups except the control and NaOCl groups (p < 0.05). The CNPs-treated samples were able to resist biofilm formation significantly better than other treatment groups (p < 0.05). Conclusions CNPs could be used as a final irrigant during root canal treatment with the dual benefit of removing the smear layer and inhibiting bacterial recolonization on root dentin. PMID:26295022

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

    PubMed

    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

  17. Improving the efficiency of phytoremediation using electrically charged plant and chelating agents.

    PubMed

    Tahmasbian, Iman; Safari Sinegani, Ali Akbar

    2016-02-01

    The low efficiency of phytoremediation is a considerable problem that limits the application of this environmentally friendly method on heavy metal-polluted soils. The combination of chelate-assisted phytoextraction and electrokinetic remediation could offer new opportunities to improve the effectiveness of phytoextraction. The current experiment aims to investigate the effects of electrical fields and chelating agents on phytoremediation efficiency. In a pot experiment using mine soil, poultry manure extract (PME), cow manure extract (CME), and ethylenediaminetetraacetic acid (EDTA) were applied to soil as chelating agents (2 g kg(-1)) at the beginning of the flowering stage. A week later, Helianthus annuus (sunflower) was negatively charged by inserting a stainless steel needle with 10 and 30 V DC electricity in the lowest part of the stems for 1 h each day for a 14-day period. At the end of the experiment, the shoot and root dry weight, lead (Pb) concentration in plant organs, translocation factor (TF), metal uptake index (UI), and soil available Pb (diethylene triamine pentaacetic acid (DTPA) extractable) were detected. Results indicated that the application of electrical fields had no significant impact on the shoot and root dry weights, while Pb concentration and UI increased in the 10-V EDTA treatment by 500 % compared to control. There was no significant difference between UI in 30- and 10-V EDTA treatments. Soil available Pb significantly increased in the 30-V treated soil. A positive correlation was observed between the available Pb in soil near the root and Pb concentration in shoot, its TF, and UI. In conclusion, a negatively charged plant along with the application of EDTA significantly increased the phytoremediation efficiency. PMID:26423283

  18. Highly regioselective hydroformylation with hemispherical chelators.

    PubMed

    Sémeril, David; Matt, Dominique; Toupet, Loïc

    2008-01-01

    The hemispherical diphosphites (R,R)- or (S,S)-5,11,17,23-tetra-tert-butyl-25,27-di(OR)-26,28-bis(1,1'-binaphthyl-2,2'-dioxyphosphanyloxy)calix[4]arene (R=OPr, OCH(2)Ph, OCH(2)-naphtyl, O-fluorenyl; R=H, R'=OPr) (L(R)), all with C(2) symmetry, have been synthesised starting from the appropriate di-O-alkylated calix[4]arene precursor. In the presence of [Rh(acac)(CO)(2)], these ligands straightforwardly provide chelate complexes in which the metal centre sits in a molecular pocket defined by two naphthyl planes related by the C(2) axis and the two apically situated R groups. Hydroformylation of octene with the L(Pr)/Rh system turned out to be highly regioselective, the linear-to-branched (l:b) aldehyde ratio reaching 58:1. The l:b ratio significantly increased when the propyl groups were replaced by -CH(2)Ph (l:b=80) or -CH(2)naphthyl (l:b=100) groups, that is, with substituents able to sterically interact with the apical metal sites, but without inducing an opening of the cleft nesting the catalytic centre. The trend to preferentially form the aldehyde the shape of which fits with the shape of the catalytic pocket was further confirmed in the hydroformylation of styrene, for which, in contrast to catalysis with conventional diphosphanes, the linear aldehyde was the major product (up to ca. 75 % linear aldehyde). In the hydroformylation of trans-2-octene with the L(benzyl)/Rh system, combined isomerisation/hydroformylation led to a remarkably high l:b aldehyde ratios of 25, thus showing that isomerisation is more effective than hydroformylation. Unusually large amounts of linear products were also observed with all the above diphosphites in the tandem hydroformylation/amination of styrene (l:b of ca. 3:1) as well as in the hydroformylation of allyl benzyl ether (l:b ratio up to 20). PMID:18686280

  19. Oxidation-Induced Degradable Nanogels for Iron Chelation

    PubMed Central

    Liu, Zhi; Wang, Yan; Purro, Max; Xiong, May P.

    2016-01-01

    Iron overload can increase cellular oxidative stress levels due to formation of reactive oxygen species (ROS); untreated, it can be extremely destructive to organs and fatal to patients. Since elevated oxidative stress levels are inherent to the condition in such patients, oxidation-induced degradable nanogels for iron chelation were rationally designed by simultaneously polymerizing oxidation-sensitive host-guest crosslinkers between β-cyclodextrin (β-CD) and ferrocene (Fc) and iron chelating moieties composed of deferoxamine (DFO) into the final gel scaffold in reverse emulsion reaction chambers. UV-Vis absorption and atomic absorption spectroscopy (AAS) was used to verify iron chelating capability of nanogels. These materials can degrade into smaller chelating fragments at rates proportional to the level of oxidative stress present. Conjugating DFO reduces the cytotoxicity of the chelator in the macrophage cells. Importantly, the nanogel can effectively reduce cellular ferritin expression in iron overloaded cells and regulate intracellular iron levels at the same time, which is important for maintaining a homeostatic level of this critical metal in cells. PMID:26868174

  20. Ab Initio Coordination Chemistry for Nickel Chelation Motifs

    PubMed Central

    Jesu Jaya Sudan, R.; Lesitha Jeeva Kumari, J.; Sudandiradoss, C.

    2015-01-01

    Chelation therapy is one of the most appreciated methods in the treatment of metal induced disease predisposition. Coordination chemistry provides a way to understand metal association in biological structures. In this work we have implemented coordination chemistry to study nickel coordination due to its high impact in industrial usage and thereby health consequences. This paper reports the analysis of nickel coordination from a large dataset of nickel bound structures and sequences. Coordination patterns predicted from the structures are reported in terms of donors, chelate length, coordination number, chelate geometry, structural fold and architecture. The analysis revealed histidine as the most favored residue in nickel coordination. The most common chelates identified were histidine based namely HHH, HDH, HEH and HH spaced at specific intervals. Though a maximum coordination number of 8 was observed, the presence of a single protein donor was noted to be mandatory in nickel coordination. The coordination pattern did not reveal any specific fold, nevertheless we report preferable residue spacing for specific structural architecture. In contrast, the analysis of nickel binding proteins from bacterial and archeal species revealed no common coordination patterns. Nickel binding sequence motifs were noted to be organism specific and protein class specific. As a result we identified about 13 signatures derived from 13 classes of nickel binding proteins. The specifications on nickel coordination presented in this paper will prove beneficial for developing better chelation strategies. PMID:25985439

  1. Essential Metalloelement Chelates Facilitate Repair of Radiation Injury

    PubMed Central

    Soderberg, Lee S. F.; Chang, Louis W.; Walker, Richard B.

    2001-01-01

    Treatment with essential metalloelement (Cu, Fe, Mn, and Zn) chelates or combinations of them before and/or after radiation injury is a useful approach to overcoming radiation injury. No other agents are known to increase survival when they are used to treat after irradiation, in a radiorecovery treatment paradigm. These chelates may be useful in facilitating de novo syntheses of essential metalloelement-dependent enzymes required to repair radiation injury. Reports of radioprotection, which involves treatment before irradiation, with calcium-channel blockers, acyl Melatonin homologs, and substituted anilines, which may serve as chelating agents after biochemical modification in vivo, as well as Curcumin, which is a chelating agent, have been included in this review. These inclusions are intended to suggest additional approaches to combination treatments that may be useful in facilitating radiation recovery. These approaches to radioprotection and radiorecovery offer promise in facilitating recovery from radiation-induced injury experienced by patients undergoing radiotherapy for neoplastic disease and by individuals who experience environmental, occupational, or accidental exposure to ultraviolet, x-ray, or γ-ray radiation. Since there are no existing treatments of radiation-injury intended to facilitate tissue repair, studies of essential metalloelement chelates and combinations of them, as well as combinations of them with existing organic radioprotectants, seem worthwhile. PMID:18475999

  2. Short communication: Using diurnal patterns of (13)C enrichment of CO2 to evaluate the effects of nitrate and docosahexaenoic acid on fiber degradation in the rumen of lactating dairy cows.

    PubMed

    Klop, G; Bannink, A; Dieho, K; Gerrits, W J J; Dijkstra, J

    2016-09-01

    Nitrate decreases enteric CH4 production in ruminants, but may also negatively affect fiber degradation. In this experiment, 28 lactating Holstein dairy cows were grouped into 7 blocks. Within blocks, cows were randomly assigned to 1 of 4 isonitrogenous treatments in a 2×2 factorial arrangement: control (CON); NO3 [21g of nitrate/kg of dry matter (DM)]; DHA [3g of docosahexaenoic acid (DHA)/kg of DM]; or NO3+DHA (21g of nitrate/kg of DM and 3g of DHA/kg of DM). Cows were fed a total mixed ration consisting of 21% grass silage, 49% corn silage, and 30% concentrates on a DM basis. Based on the difference in natural (13)C enrichment and neutral detergent fiber and starch content between grass silage and corn silage, we investigated whether a negative effect on rumen fiber degradation could be detected by evaluating diurnal patterns of (13)C enrichment of exhaled carbon dioxide. A significant nitrate × DHA interaction was found for neutral detergent fiber digestibility, which was reduced on the NO3 treatment to an average of 55%, as compared with 61, 64, and 65% on treatments CON, DHA, and NO3+DHA, respectively. Feeding nitrate, but not DHA, resulted in a pronounced increase in (13)C enrichment of CO2 in the first 3 to 4 h after feeding only. Results support the hypothesis that effects of a feed additive on the rate of fiber degradation in the rumen can be detected by evaluating diurnal patterns of (13)C enrichment of CO2. To be able to detect this, the main ration components have to differ considerably in fiber and nonfiber carbohydrate content as well as in natural (13)C enrichment. PMID:27344384

  3. Enhanced accumulation of Cd in castor (Ricinus communis L) by soil-applied chelators.

    PubMed

    Chhajro, Muhammad Afzal; Rizwan, Muhammad Shahid; Guoyong, Huang; Jun, Zhu; Kubar, Kashif Ali; Hongqing, Hu

    2016-07-01

    Phytoextraction has been identified as one of the most propitious methods of phytoremediation. This pot experiment were treated with varying amounts of (ethylenediamine triacetic acid) EDTA 3-15, (Nitriloacetic acid) NTA 3-10, (Ammonium citrate) NH4 citrate 10 - 25 mmol and one mg kg(-1)Cd, filled with 5 kg soil. The addition of chelators significantly increased Cd concentration in soil and plant. The results showed that maximum Cd uptake was noted under root, shoot and leaf of castor plant tissue (2.26, 1.54, and 0.72 mg kg(-1)) under EDTA 15, NTA 10, and NH4 citrate 25 mmol treatments respectively, and in soil 1.08, 1.06 and 0.52 mg kg(-1) pot(-1) under NH4 citrate 25, NTA 10 and EDTA 15 mmol treatments respectively, as against to control (p < 0.05). Additions of chelators reduction biomass under the EDTA 15 mmol as compared to other treatments, However, Bioconcentration factor (BCF), translocation factor (TF) and remediation factor (RF) were significantly increased under EDTA 15 and NH4 citrate 25 mmol as against control. Our results demonstrated that castor plant proved satisfactory for phytoextraction on contaminated soil, and EDTA 15 and NH4 citrate 25 mmol had the affirmative effect on the Cd uptake in the artificial Cd-contaminated soil. PMID:26588431

  4. Metal chelate affinity precipitation of RNA and purification of plasmid DNA

    NASA Technical Reports Server (NTRS)

    Balan, Sindhu; Murphy, Jason; Galaev, Igor; Kumar, Ashok; Fox, George E.; Mattiasson, Bo; Willson, Richard C.

    2003-01-01

    The affinity of metal chelates for amino acids, such as histidine, is widely used in purifying proteins, most notably through six-histidine 'tails'. We have found that metal affinity interactions can also be applied to separation of single-stranded nucleic acids through interactions involving exposed purines. Here we describe a metal affinity precipitation method to resolve RNA from linear and plasmid DNA. A copper-charged copolymer of N-isopropyl acrylamide (NIPAM) and vinyl imidazole (VI) is used to purify plasmid from an alkaline lysate of E. coli. The NIPAM units confer reversible solubility on the copolymer while the imidazole chelates metal ions in a manner accessible to interaction with soluble ligands. RNA was separated from the plasmid by precipitation along with the polymer in the presence of 800 mM NaCl. Bound RNA could be recovered by elution with imidazole and separated from copolymer by a second precipitation step. RNA binding showed a strong dependence on temperature and on the type of buffer used.

  5. Studies on chelating adsorption properties of novel composite material polyethyleneimine/silica gel for heavy-metal ions

    NASA Astrophysics Data System (ADS)

    Gao, Baojiao; An, Fuqiang; Liu, Kangkai

    2006-12-01

    Firstly, the coordination processes of line-type polyethyleneimine with Cu 2+, Cd 2+ and Zn 2+ were studied by using visible light absorption spectroscopy and chelation conductivity titration method, and the structures of the chelates were determined. Afterwards, polyethyleneimine (PEI) was grafted onto the surface of silica gel particles via the coupling effect of γ-chloropropyl trimethoxysilane (CP), and the novel composite adsorption material PEI/SiO 2 with strong adsorption ability towards heavy-metal ions was prepared. The chelating adsorption properties of PEI/SiO 2 for Cu 2+, Cd 2+ and Zn 2+ were researched by both static (batch) and dynamic (flow) methods. The experiment results show that water-soluble polyamine PEI with line-type structure reacts with Cu 2+, Cd 2+ and Zn 2+ easily and quantitatively, and water-soluble chelates with four ligands are formed. The composite material PEI/SiO 2 possesses very strong chelating adsorption ability for heavy-metal ions, and the saturated adsorption amount can reach 25.94 mg g -1 and 50.01 mg g -1 for Cu 2+ under static and dynamic conditions, respectively. The isothermal adsorption data fit to Langmuir equation, and the adsorption is typical chemical adsorption with monomolecular layer. The adsorbing ability of PEI/SiO 2 towards the three kinds of the ions follows the order of Cu 2+ > Cd 2+ > Zn 2+. The pH value has great influence on the sorption, and at pH 6-7, the adsorption capacity is the greatest. The fact that adsorption capacity increases with temperature rising indicates the adsorbing process of PEI/SiO 2 for metal ions is endothermic. As diluted hydrochloric acid is used as eluent, the adsorbed heavy-metal ions are eluted easily from PEI/SiO 2, and the regeneration and reuse without decreasing sorption for PEI/SiO 2 are demonstrated.

  6. Media composition: antioxidants/chelators and cellular function.

    PubMed

    Combelles, Catherine M H; Hennet, Margo L

    2012-01-01

    Protection of embryos against oxidative insults during culture is necessary to maintain viability. Generation of excessive levels of reactive oxygen species (ROS) is triggered by various components of the in vitro environment, most of which embryos do not normally encounter in vivo. To compensate for these deficiencies in the culture environment, antioxidants and chelators are often used to control or suppress ROS levels as embryos develop. However, there is no consensus regarding dosage, time of exposure, or appropriate combinations of antioxidants and chelators in embryo culture. In order to elucidate this aspect of an embryo's chemical surroundings in vitro, we present the current knowledge on the function and effect of each antioxidant or chelator that is often included in an embryo culture medium. PMID:22829373

  7. Iron chelation inhibits the development of pulmonary vascular remodeling.

    PubMed

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

    2012-11-01

    Reactive oxygen species (ROS) have been implicated in the pathogenesis of pulmonary hypertension. Because iron is an important regulator of ROS biology, this study examined the effects of iron chelation on the development of pulmonary vascular remodeling. The administration of an iron chelator, deferoxamine, to rats prevented chronic hypoxia-induced pulmonary hypertension and pulmonary vascular remodeling. Various iron chelators inhibited the growth of cultured pulmonary artery smooth muscle cells. Protein carbonylation, an important iron-dependent biological event, was promoted in association with pulmonary vascular remodeling and cell growth. A proteomic approach identified that Rho GDP-dissociation inhibitor (a negative regulator of RhoA) is carbonylated. In human plasma, the protein carbonyl content was significantly higher in patients with idiopathic pulmonary arterial hypertension than in healthy controls. These results suggest that iron plays an important role in the ROS-dependent mechanism underlying the development of pulmonary hypertension. PMID:22974762

  8. The effect of iron overload and chelation on erythroid differentiation.

    PubMed

    Taoka, Kazuki; Kumano, Keiki; Nakamura, Fumihiko; Hosoi, Masataka; Goyama, Susumu; Imai, Yoichi; Hangaishi, Akira; Kurokawa, Mineo

    2012-02-01

    We investigated the mechanisms of hematopoietic disorders caused by iron overload and chelation, in particular, the inhibition of erythroblast differentiation. Murine c-kit(+) progenitor cells or human CD34(+) peripheral blood hematopoietic progenitors were differentiated in vitro to the erythroid lineage with free iron and/or an iron chelator. Under iron overload, formation of erythroid burst-forming unit colonies and differentiation to mature erythroblasts were significantly suppressed; these effects were canceled by iron chelation with deferoxamine (DFO). Moreover, excessive iron burden promoted apoptosis in immature erythroblasts by elevating intracellular reactive oxygen species (ROS). Interestingly, both DFO and a potent anti-oxidant agent reduced intracellular ROS levels and suppressed apoptosis, thus restoring differentiation to mature erythroblasts. Accordingly, intracellular ROS may represent a new therapeutic target in the treatment of iron overload. PMID:22193844

  9. Molecular nanotechnologies of gelatin-immobilization using macrocyclic metal chelates

    PubMed Central

    Mikhailov, Oleg V.

    2014-01-01

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

  10. A localized and propagating SPR, and molecular imprinting based fiber-optic ascorbic acid sensor using an in situ polymerized polyaniline-Ag nanocomposite.

    PubMed

    Shrivastav, Anand M; Usha, Sruthi P; Gupta, Banshi D

    2016-08-26

    We report a successful approach for the fabrication and characterization of a fiber-optic sensor for ascorbic acid (AA) detection, using a molecularly imprinted polyaniline-Ag (PANI-Ag) nanocomposite layer based on the combined phenomena of surface plasmon resonance (SPR) and localized SPR (LSPR). The PANI-Ag nanocomposite is synthesized by an in situ polymerization process and AA imprints are prepared on the polymeric composite. The confirmation of the PANI-Ag nanocomposite and AA imprinting is performed using various characterization methods such as x-ray diffraction (XRD), UV-vis, Fourier transform infrared spectroscopy and scanning electron microscopy. From XRD, the size of Ag nanoparticles is analyzed. The absorbance spectra are recorded for samples of different concentrations of AA around the sensing region of the probe. An increase in peak absorbance wavelength with the increase in AA concentration is observed with a linear response for the concentration range from 10(-8) M to 10(-6) M. The sensor possesses a high sensitivity of 45.1 nm log(-1) M near an AA concentration of 10(-8) M. The limit of detection (LOD) and limit of quantification of the sensor are found to be 7.383 × 10(-11) M and 4.16 × 10(-10) M, respectively. The LOD of the sensor is compared to studies reported in the literature and is found to be the lowest. The sensor possesses several other advantages such as cost effectiveness, selectivity, and low response time (<5 s), along with abilities of remote sensing and online monitoring. PMID:27405256

  11. Graphitic carbon nitrides modified hollow fiber solid phase microextraction for extraction and determination of uric acid in urine and serum coupled with gas chromatography-mass spectrometry.

    PubMed

    Sun, Ying-pei; Chen, Juan; Qi, Huan-yang; Shi, Yan-ping

    2015-11-01

    An elevated uric acid (UA) in urine or serum can affect renal function and blood pressure, which is an indicator of gout, cardiovascular and renal diseases, hypertension, etc. In this work, a new type of mixed matrix membrane (MMM), based on graphitic carbon nitrides (g-CNs) and hollow fiber (HF), was prepared and combined with solid phase microextraction (SPME) mode to determine UA in urine and serum followed by gas chromatography-mass spectrometry (GC/MS). The porous g-CNs were dispersed in ammonia, and then the exfoliated g-CNs nanosheets were held in the pores of HF by capillary forces and sonification. The prepared g-CNs modified HF (g-CNs-HF) was immersed in biofluid directly to extract UA with SPME mode and the solvent-free mode is convenient for further derivatization and analysis. To achieve the highest extraction efficiency (EF), main extraction and derivatization parameters, such as g-CNs-HF immobilizing time, sonification power and time of extraction, derivatization and desorption time, were optimized. Under the optimum extraction conditions, a favorable linearity of UA was obtained in the range 0.1-200μgmL(-1) with correlation coefficients higher than 0.9990, and the average recoveries at three spiked levels of UA in urine and serum ranged from 80.7% to 121.6%, from 84.7% to 101.1%, respectively. The obtained results demonstrated the developed g-CNs-HF-SPME is a simple, rapid, cost-effective, solvent-free method for the analysis of UA in biofluid. PMID:26444336

  12. A multiphasic hollow fiber reactor for the whole-cell bioconversion of 2-methyl-1,3-propanediol to (r)-beta-hydroxyisobutyric acid.

    PubMed

    León, R; Prazeres, D M; Fernandes, P; Molinari, F; Cabral, J M

    2001-01-01

    This paper describes the bioconversion of 2-methyl-1,3-propanediol to (R)-beta-hydoxyisobutyric acid (HIBA) by Acetobacter ALEI in a hollow fiber membrane bioreaction system arrangement that allows the integration of three liquid phases: the aqueous bioconversion phase, the organic phase consisting of a solution of trioctyl phosphine oxide (TOPO) in isooctane, and the third phase consisting of a basic stripping solution that allows reextraction of HIBA from the organic phase. A comparison of HIBA mass transfer experiments was carried out in the membrane reactor with two and three phases for different pH and TOPO concentrations. The use of the three-phase arrangement allows the extraction of high quantities of HIBA from the aqueous medium (higher than 85%) independently of the pH, whereas in the two-phase system the percentage of HIBA extracted from the aqueous medium was lower, 42% in the best case, and strongly influenced by the pH. The percentage of the extractive agent TOPO in the organic phase influenced on the mass transfer rate in both bi- and triphasic arrangements. By simply integrating the re-extraction phase in the system it was possible to increase the extraction yield by 2-fold, reduce the amount of TOPO by 4-fold, and operate at the more favorable pH 4. A bioconversion experiment was done in these conditions (pH = 4, TOPO = 5%) to confirm the advantages of including the third stripping solution. Fed-batch operation of the triphasic membrane reactor was maintained for more than 20 h, reaching an HIBA concentration in the stripping solution of 29 g L(-)(1). PMID:11386867

  13. A localized and propagating SPR, and molecular imprinting based fiber-optic ascorbic acid sensor using an in situ polymerized polyaniline–Ag nanocomposite

    NASA Astrophysics Data System (ADS)

    Shrivastav, Anand M.; Usha, Sruthi P.; Gupta, Banshi D.

    2016-08-01

    We report a successful approach for the fabrication and characterization of a fiber-optic sensor for ascorbic acid (AA) detection, using a molecularly imprinted polyaniline–Ag (PANI–Ag) nanocomposite layer based on the combined phenomena of surface plasmon resonance (SPR) and localized SPR (LSPR). The PANI–Ag nanocomposite is synthesized by an in situ polymerization process and AA imprints are prepared on the polymeric composite. The confirmation of the PANI–Ag nanocomposite and AA imprinting is performed using various characterization methods such as x-ray diffraction (XRD), UV–vis, Fourier transform infrared spectroscopy and scanning electron microscopy. From XRD, the size of Ag nanoparticles is analyzed. The absorbance spectra are recorded for samples of different concentrations of AA around the sensing region of the probe. An increase in peak absorbance wavelength with the increase in AA concentration is observed with a linear response for the concentration range from 10‑8 M to 10‑6 M. The sensor possesses a high sensitivity of 45.1 nm log‑1 M near an AA concentration of 10‑8 M. The limit of detection (LOD) and limit of quantification of the sensor are found to be 7.383 × 10‑11 M and 4.16 × 10‑10 M, respectively. The LOD of the sensor is compared to studies reported in the literature and is found to be the lowest. The sensor possesses several other advantages such as cost effectiveness, selectivity, and low response time (<5 s), along with abilities of remote sensing and online monitoring.

  14. Fiber sensing with photorefractive fiber

    NASA Astrophysics Data System (ADS)

    Yu, Francis T. S.; Guo, Ruyan; Wang, Bo; Liu, Yuexin

    2002-11-01

    Optical fibers have been widely used for transmitting temporal signal. However, the transmission of spatial signal has not been fully exploited. Although multimode fiber has a large space-bandwidth product, transmitting spatial signals by using a fiber is rather difficult. When a laser beam is lached into a multimode fiber, the exit light field produces a complicated speckle pattern caused by the modal phasing of the fiber. It is difficult to recover the transmitted informati from the speckle field. However, the fiber speckle field can be used to fiber sensing with a hologrpahic method. In other words, if a hologram is made with the speckle fiber field, the information of the fiber status can be recovered. Thus by reading the hologram by the same speckle field, the reference beam can be reconstructed, which represents the detection of the speckle field. In other words, instead of exploiting the temporal content, the spatial content from a multimode fiber can be exploited for sensing. Our analyses and experimentations have shown that the fiber specklegram sensor (FSS) is highly senstiive to perturbation, and it is less vulnerable to the environment factors. Applications of the FSS to temperature, transversal displacement, and dynamic sensing are also included.

  15. Effects of chelating agents on oral uptake and renal deposition and excretion of cadmium.

    PubMed Central

    Engström, B

    1984-01-01

    The gastrointestinal absorption, transport, tissue deposition and excretion of cadmium was studied in adult male mice given a single oral LD50 dose of 109Cd-labeled CdCl2 alone or in combination with nitrilotriacetic acid (NTA), sodium tripolyphosphate (STPP) or ethylenediaminetetraacetic acid (EDTA). Blood, intestinal mucosa, liver and kidneys were analyzed for 109Cd at different times after exposure and the influence of the chelating agents on Cd binding to metallothionein and other tissue ligands was also studied. Acute toxicity was noted. Complex formation between Cd and EDTA was studied in solutions containing Cd:EDTA at 1:04 and 1:4 molar ratios. Adult male mice were exposed orally or by direct infusion into the stomach to either of the two solutions (containing an LD50 dose of Cd). Body retention and tissue deposition of Cd was recorded after 4 (direct infusion) or 21 days (oral exposure), and the mortality in different exposure groups observed. Adult male were also exposed to a low oral dose of 109Cd-labeled cadmium (0.5 mg/kg), followed by 18 months continuous administration of NTA, (500 ppm) STPP (500 ppm) or EDTA (50 ppm) in the drinking water or the chelating agent in combination with Cd (50 ppm), Cd alone (50 ppm) or deionized water. Whole-body retention of 109Cd, tissue deposition of 109Cd and total Cd and development of proteinuria were observed. When cadmium was given with an excess of EDTA, all Cd ions were bound in a 1:1 Cd-EDTA complex. Decreased acute toxicity was observed which was related to increased body elimination of cadmium. The Cd passes though the body still bound to EDTA and is excreted via the kidneys in this form. Similar results were found in mice exposed to Cd + NTA, while gavage of CD + STPP led to an initially decreased systemic uptake of Cd and thereafter to a prolongation of the biological half-time and thus a comparatively higher body retention of the metal. Cd may form a 2:1 complex with EDTA in the presence of excess cadmium

  16. Evaluation of nitrogen-rich macrocyclic ligands for the chelation of therapeutic bismuth radioisotopes

    DOE PAGESBeta

    Wilson, Justin J.; Ferrier, Maryline; Radchenko, Valery; Maassen, Joel R.; Engle, Jonathan W.; Batista, Enrique R.; Martin, Richard L.; Nortier, Francois M.; Fassbender, Michael E.; John, Kevin D.; et al

    2015-05-01

    The use of α-emitting isotopes for radionuclide therapy is a promising treatment strategy for small micro-metastatic disease. The radioisotope ²¹³Bi is a nuclide that has found substantial use for targeted α-therapy (TAT). The relatively unexplored aqueous chemistry of Bi³⁺, however, hinders the development of bifunctional chelating agents that can successfully deliver these Bi radioisotopes to the tumor cells. Here, a novel series of nitrogen-rich macrocyclic ligands is explored for their potential use as Bi-selective chelating agents. The ligands, 1,4,7,10-tetrakis(pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane (Lpy), 1,4,7,10-tetrakis(3-pyridazylmethyl)-1,4,7,10-tetraazacyclododecane (Lpyd), 1,4,7,10-tetrakis(4-pyrimidylmethyl)-1,4,7,10-tetraazacyclododecane (Lpyr), and 1,4,7,10-tetrakis(2-pyrazinylmethyl)-1,4,7,10-tetraazacyclododecane (Lpz), were prepared by a previously reported method and investigated here for their abilitiesmore » to bind Bi radioisotopes. The commercially available and commonly used ligands 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and N-[(R)-2-amino-3-(p-isothiocyanato-phenyl)propyl]-trans-(S,S)- cyclohexane-1,2-diamine-N,N,N',N",N"-pentaacetic acid (CHX-A''-DTPA) were also explored for comparative purposes. Radio-thin-layer chromatography (TLC) was used to measure the binding kinetics and stabilities of the complexes formed. The long-lived isotope, ²⁰⁷Bi (t1/2 = 32 years), was used for these studies. Density functional theory (DFT) calculations were also employed to probe the ligand interactions with Bi³⁺ and the generator parent ion Ac³⁺.In contrast to DOTA and CHX-A''-DTPA, these nitrogen-rich macrocycles selectively chelate Bi³⁺ in the presence of the parent isotope Ac³⁺. Among the four tested, Lpy was found to exhibit optimal Bi³⁺-binding kinetics and complex stability. Lpy complexes Bi³⁺ more rapidly than DOTA, yet the resulting complexes are of similar stability. DFT

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

    PubMed

    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

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

    PubMed

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

    2009-10-15

    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. PMID:19595699

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

    SciTech Connect

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

    2009-10-15

    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.

  20. SEPARATION OF PLUTONIUM FROM LANTHANUM BY CHELATION-EXTRACTION

    DOEpatents

    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. Conservation, fiber digestibility, and nutritive value of corn harvested at 2 cutting heights and ensiled with fibrolytic enzymes, either alone or with a ferulic acid esterase-producing inoculant.

    PubMed

    Lynch, J P; Baah, J; Beauchemin, K A

    2015-02-01

    The aim of this study was to determine the effects of the use of a fibrolytic enzyme product, applied at ensiling either alone or in combination with a ferulic acid esterase-producing bacterial additive, on the chemical composition, conservation characteristics, and in vitro degradability of corn silage harvested at either conventional or high cutting height. Triplicate samples of corn were harvested to leave stubble of either a conventional (15cm; NC) or high (45cm; HC) height above ground. Sub-samples of chopped herbage were ensiled untreated or with a fibrolytic enzyme product containing xylanases and cellulases applied either alone (ENZ) or in combination with a ferulic acid esterase-producing silage inoculant (ENZ+FAEI). The fibrolytic enzyme treatment was applied at 2mL of enzyme product/kg of herbage dry matter (DM), and the inoculant was applied at 1.3×10(5) cfu/g of fresh herbage. Samples were packed into laboratory-scale silos, stored for 7, 28, or 70 d, and analyzed for fermentation characteristics, and samples ensiled for 70 d were also analyzed for DM losses, chemical composition, and in vitro ruminal degradability. After 70 d of ensiling, the fermentation characteristics of corn silages were generally unaffected by cutting height, whereas the neutral detergent fiber, acid detergent fiber, and ash concentrations were lower and the starch concentration greater for silages made with crops harvested at HC compared with NC. After 70 d of ensiling, the acetic acid, ethanol concentrations, and the number of yeasts were greater, and the pH and neutral detergent fiber concentrations were lower, in silages produced using ENZ or ENZ+FAEI than the untreated silages, whereas ENZ+FAEI silages also incurred higher DM losses. No effect of additive treatment was observed on in vitro degradability indices after 48h ruminal incubation. The use of a fibrolytic enzyme product, either alone or in combination with a ferulic acid esterase-producing inoculant, at ensiling

  2. Cage-like bifunctional chelators, copper-64 radiopharmaceuticals and PET imaging using the same

    DOEpatents

    Conti, Peter S.; Cai, Hancheng; Li, Zibo; Liu, Shuanglong

    2016-08-02

    Disclosed is a class of versatile Sarcophagine based bifunctional chelators (BFCs) containing a hexa-aza cage for labeling with metals having either imaging, therapeutic or contrast applications radiolabeling and one or more linkers (A) and (B). The compounds have the general formula ##STR00001## where A is a functional group selected from group consisting of an amine, a carboxylic acid, an ester, a carbonyl, a thiol, an azide and an alkene, and B is a functional group selected from the group consisting of hydrogen, an amine, a carboxylic acid, and ester, a carbonyl, a thiol, an azide and an alkene. Also disclosed are conjugate of the BFC and a targeting moiety, which may be a peptide or antibody. Also disclosed are metal complexes of the BFC/targeting moiety conjugates that are useful as radiopharmaceuticals, imaging agents or contrast agents.

  3. Kinetically and thermodynamically stable isomers of thorium chelates of polyaza polycarboxylic macrocycles

    NASA Astrophysics Data System (ADS)

    Jacques, Vincent; Desreux, Jean F.

    1994-10-01

    The solution conformation of the thorium(IV) complexes of two polyaza polycarboxylic macrocycles, DOTA and HEHA (1,4,7,10-tetraazacyclododecane-N, N', N(double prime), N(triple prime)-tetraacetic acid and 1,4,7,10,13,16-hexaazacyclooctadecane-N, N', N(double prime), N(triple prime), N(double prime)(double prime), N(double prime)(triple prime)-hexaacetic acid), was investigated by one- and two-dimensional nuclear magnetic resonance spectroscopy. ThHEHA(2+) forms a kinetically stable topomer of C2 symmetry and a thermodynamically stable topomer of S6 symmetry. Both complexes are assigned an icosahedral geometry. The activation energy for the intermolecular exchange is very high (214 kJ/mol). The behavior of ThHEHA(2+) contrasts with the properties of the other Th(IV) chelates that are known to be fluxional.

  4. Metal chelates anchored to poly-l-peptides and linear d,l-α-peptides with promising nanotechnological applications

    NASA Astrophysics Data System (ADS)

    Punzi, P.; Giordano, C.; Marino, F.; Morosetti, S.; De Santis, P.; Scipioni, A.

    2012-10-01

    Regular configurationally alternating amino acid sequences generate cyclic and linear helical peptides with a local β-conformation able to self-assemble in nanowires and nanoscaffolds directed and stabilized by hydrogen bonds. The possibility of modulating the chemical profile of the various amino acid residues containing reactive side chains means that peptides could be flexible templates for creating various building blocks. A method for the design of molecules with potential spintronic properties is described. Peptides containing lysine residues, the side chains of which are bridged through the formation of metal chelates via Schiff bases, could provide stable molecular channels. When metal chelates with high electron spin states are used, their coupling could generate materials that are interesting due to their magnetic properties as well as for the patterning of nanometric lattices driven by their orientation under a magnetic field. With this aim, three alternating d- and l-lysine-containing octapeptides are synthesized and the formation of their bis(pyridoxalaldimine) copper(II) chelate derivatives is shown by absorption and circular dichroism spectroscopies.

  5. Degradation of toluene, ethylbenzene, and xylene using heat and chelated-ferrous iron activated persulfate oxidation

    NASA Astrophysics Data System (ADS)

    Mondal, P.; Sleep, B.

    2014-12-01

    Toluene, ethylbenze, and xylene (TEX) are common contaminants in the subsurface. Activated persulfate has shown promise for degrading a wide variety of organic compounds. However, studies of persulfate application for in situ degradation of TEX and effects on the subsequent bioremediation are limited. In this work, degradation studies of TEX in aqueous media and soil are being conducted using heat activated and chelated-ferrous iron activated persulfate oxidation in batch and flow-through column experiments. In the batch experiments, sodium persulfate is being used at different concentrations to provide an initial persulfate to TEX molar ratios between 10:1 and 100:1. Sodium persulfate solutions are being activated at 20, 37, 60, and 80 oC temperatures for the heat activated oxidation. For the chelated-ferrous iron activated oxidation, ferrous iron and citric acid, both are being used at concentration of 5 mM. In the experiments with soil slurry, a soil to water ratio of 1 to 5 is being used. Flow through water saturated column experiments are being conducted with glass columns (45 cm in length and 4 cm in diameter) uniformly packed with soils, and equilibrated with water containing TEX at the target concentrations. Both the heat activation and chelated-ferrous iron activation of persulfate are being employed in the column experiments. Future experiments are planned to determine the suitability of persulfate oxidation of TEX on the subsequent biodegradation using batch microcosms containing TEX degrading microbial cultures. In these experiments, the microbial biomass will be monitored using total phospholipids, and the microbial community will be determined using quantitative real-time polymerase chain reaction (qPCR) on the extracted DNA. This study is expected to provide suitable operating conditions for in situ chemical oxidation of TEX with activated persulfate followed by bioremediation.

  6. Colour and stability assessment of blue ferric anthocyanin chelates in liquid pectin-stabilised model systems.

    PubMed

    Buchweitz, M; Brauch, J; Carle, R; Kammerer, D R

    2013-06-01

    The formation of blue coloured ferric anthocyanin chelates and their colour stability during storage and thermal treatment were monitored in a pH range relevant to food (3.6-5.0). Liquid model systems were composed of different types of Citrus pectins, juices (J) and the respective phenolic extracts (E) from elderberry (EB), black currant (BC), red cabbage (RC) and purple carrot (PC) in the presence of ferric ions. For EB, BC and PC, pure blue colours devoid of a violet tint were exclusively observed for the phenolic extracts and at pH values ≥ 4.5 in model systems containing high methoxylated and amidated pectins, respectively. Colour and its stability strongly depended on the amount of ferric ions and the plant source; however, colour decay could generally be described as a pseudo-first-order kinetics. Despite optimal colour hues for RC-E and RC-J, storage and heat stabilities were poor. Highest colour intensities and best stabilities were observed for model systems containing PC-E at a molar anthocyanin:ferric ion ratio of 1:2. Ascorbic and lactic acids interfered with ferric ions, thus significantly affecting blue colour evolution and stability. Colour loss strongly depended on heat exposure with activation energies ranging between 60.5 and 78.4 kJ/mol. The comprehensive evaluation of the interrelationship of pigment source, pH conditions and pectin type on chelate formation and stability demonstrated that ferric anthocyanin chelates are promising natural blue food colourants. PMID:23411339

  7. Species-dependent effective concentration of DTPA in plasma for chelation of 241Am

    PubMed Central

    Sueda, Katsuhiko; Sadgrove, Matthew P.; Jay, Michael; Di Pasqua, Anthony J.

    2013-01-01

    Diethylenetriaminepentaacetic acid (DTPA) is a chelating agent that is used to facilitate the elimination of radionuclides, such as americium, from contaminated individuals. Its primary site of action is in the blood, where it competes with various biological ligands, including transferrin and albumin, for the binding of radioactive metals. To evaluate the chelation potential of DTPA under these conditions, the competitive binding of 241Am between DTPA and plasma proteins was studied in rat, beagle and human plasma in vitro. Following incubation of DTPA and 241Am in plasma, the 241Am-bound ligands were fractionated by ultrafiltration and ion-exchange chromatography, and each fraction was assayed for 241Am content by gamma scintillation counting. Dose-response curves of DTPA for 241Am binding were established, and these models were used to calculate the 90% maximal effective concentration, or EC90, of DTPA in each plasma system. The EC90 were determined to be 31.4, 15.9 and 10.0 μM in rat, beagle and human plasma, respectively. These values correspond to plasma concentrations of DTPA that maximize 241Am chelation while minimizing excess DTPA. Based on the pharmacokinetic profile of DTPA in humans, after a standard 30 μmol kg−1 intravenous bolus injection, the plasma concentration of DTPA remains above EC90 for approximately 5.6 h. Likewise, the effective duration of DTPA in rat and beagle were determined to be 0.67 and 1.7 h, respectively. These results suggest that species differences must be considered when translating DTPA efficacy data from animals to humans and offer further insights into improving the current DTPA treatment regimen. PMID:23799506

  8. Evaluation of the potential role of chelation therapy in treatment of low to moderate lead exposures

    SciTech Connect

    Chisolm, J.J. Jr. )

    1990-11-01

    In the overall long-term management of lead poisoning, chelation therapy can have short-term benefits; however, these benefits must be accompanied by drastic reduction in environmental exposure to lead if therapy is to have any long-term benefit. This discussion is limited to calcium disodium ethylenediaminetetraacetate (CaNa{sub 2}EDTA), the chelating agent that has been the mainstay of treatment of lead poisoning for the past 38 years, and to meso-2,3-dimercaptosuccinic acid (DMSA), a new and promising oral chelating agent, which is an orphan drug and is currently classified as an investigational new drug by the US Food and Drug Administration. With both drugs, multiple courses of treatment will be needed if any substantial reduction in body lead burden is to be achieved. A major limitation of CaNa{sub 2}EDTA is the enormous diuresis of zinc that it produces. DMSA produces a comparable diuresis of lead, a greater decrease in blood lead, and has negligible influence on the urinary losses of zinc, copper, iron, and calcium. Limited experience to date in man has revealed no significant adverse side effects of DMSA. In animals, DMSA will promptly reduce the concentration of lead in brain and kidney, in particular. By contrast, similar 5-day courses of CaNa{sub 2}EDTA do not produce any net reduction in brain lead. This is important, as the brain is the critical organ of the adverse effects of lead in children. If the efficacy of DMSA is to be comprehensively evaluated ethically in children, new and more sensitive neurochemical, electrophysiologic, or other markers must be developed.

  9. [Carbohydrates and fiber].

    PubMed

    Lajolo, F M; de Menezes, E W; Filisetti-Cozzi, T M

    1988-09-01

    ) the proportion of "crude fiber" (as measured by acid and alkaline digestion) leads to an over-estimation of the proportion of digestible carbohydrates calculated by difference; 2) fiber may alter the polysaccharide utilization of some foods, as shown by the "glycemic index". It is difficult to make recommendations on dietary fiber due to insufficient data on intake, fiber composition, its physiological effects, and epidemiological studies. However, a preliminary evaluation of the diets from most Latin American countries shows large intakes of vegetable foods and, consequently, an adequate fiber intake may be expected. PMID:2856370

  10. Scanning electron microscopy of the root surface texture of extracted periodontally diseased teeth following various etching and chelating regimens.

    PubMed

    Bergenholtz, A; Babay, N

    1998-04-01

    Scanning electron microscopy of root surfaces that had been ultrasonically scaled and subjected to various conditioning regimens revealed the presence of two distinct types of cracks: extensive cracks, presumed to have been caused by drying before and during sputter-coating procedures; and smaller cracks that reflected the pattern of the irregular underlying dentin. Both etching and chelating agents appear to cause demineralization of the interfacial layer between cementum and dentin, causing a "peeling off" of cementum and exposure of the underlying dentin. The results suggest that burnishing the scaled root surface with either saline or any of the etching or chelating agents for at least 10 seconds, followed by soaking the cementum in 8% ethylenediaminetetraacetic acid for about 40 seconds, achieved a root surface that might be regarded as optimal for regeneration of periodontal tissues. PMID:9663095

  11. Enzyme-entrapping behaviors in alginate fibers and their papers

    SciTech Connect

    Kobayashi, Y.; Matsuo, R.; Ohya, T.; Yokoi, N.

    1987-01-01

    Enzyme immobilization in the form of fiber and paper was easily achieved by wet spinning of aqueous admixture of sodium alginate and enzymes into divalent metallic ion solution as a coagulating bath, followed by paper making of resultant shortly cut fibers. Entrapment yields of enzymes used, e.g., glucoamylase, cyclodextrin glucanotransferase, endo-polygalacturonase, and protease, were always higher in calcium alginate fibers and their papers than those in corresponding beads. It was found that the yields increased with an increase of the discharge rate through the spinning nozzle because the higher discharge rate could provide more highly oriented metal-chelate linear polymer molecules along the fiber axis for preventing leakage of entrapped enzymes. Divalent metallic ions affected greatly the entrapment of glucoamylase in alginate fibers, the order of which followed rougly the ionotropic series of Thiele. Entrapment of glucoamylase in bicomponent systems comprising alginate and other water-soluble polymers was also investigated. (Refs. 41).

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

    MedlinePlus

    ... a trained health professional. What did the chelation infusions contain? For TACT, the active, 10-component, chelation ... of normal saline and 1.2% dextrose. The infusions were prepared at a central pharmacy for the ...

  13. Novel peptide with a specific calcium-binding capacity from whey protein hydrolysate and the possible chelating mode.

    PubMed

    Zhao, Lina; Huang, Qimin; Huang, Shunli; Lin, Jiaping; Wang, Shaoyun; Huang, Yifan; Hong, Jing; Rao, Pingfan

    2014-10-22

    A novel peptide with a specific calcium-binding capacity was isolated from whey protein hydrolysates. The isolation procedures included diethylaminoethyl (DEAE) anion-exchange chromatography, Sephadex G-25 gel filtration, and reversed-phase high-performance liquid chromatography (HPLC). A peptide with a molecular mass of 237.99 Da was identified by liquid chromatography-electrospray ionization/mass spectrometry (LC-ESI/MS), and its amino acid sequence was confirmed to be Gly-Tyr. The calcium-binding capacity of Gly-Tyr reached 75.38 μg/mg, increasing by 122% when compared to the hydrolysate complex. The chelating interaction mode between the Gly-Tyr and calcium ion was investigated, indicating that the major binding sites included the oxygen atom of the carbonyl group and nitrogen of the amino or imino group. The folding and structural modification of the peptide arose along with the addition of the calcium ion. The profile of (1)H nuclear magnetic resonance (NMR) spectroscopy demonstrated that the electron cloud density around the hydrogen nucleus in the peptide changed was caused by the calcium ion. The results of ζ potential showed that the Gly-Tyr-Ca chelate was a neutral molecule in which the calcium ion was surrounded by the specific binding sites of the peptide. Moreover, thermogravimetry-differential scanning calorimetry (TG-DSC) and calcium-releasing assay revealed that the Gly-Tyr-Ca chelate exerted excellent thermal stability and solubility in both acidic and basic conditions, which were beneficial to calcium absorption in the gastrointestinal tract of the human body and, therefore, improved its bioavailability. These findings further the progress in the research of whey protein, suggesting the potential in making peptide-calcium chelate as a dietary supplement. PMID:25265391

  14. Desferrithiocin: A Search for Clinically Effective Iron Chelators

    PubMed Central

    2015-01-01

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

  15. Technical Report Summary: Metal Chelate, Eu-QCTME

    SciTech Connect

    Richter, James, A.

    2008-05-08

    A novel fluorescent metal complex, Eu-QCTME has shown promise for the early stage detection of cancer. This material has been shown to bind preferentially to xenographic tumors. The study, using HT29 murine xenographic tumors was performed to determine if the chelate preferentially binds to tumor tissue and the potential for an early stage diagnostic test and treatment for epithelial cell cancers.

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

    NASA Technical Reports Server (NTRS)

    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.

  17. Scintigraphic monitoring of immunotoxins using radionuclides and heterobifunctional chelators

    SciTech Connect

    Reardan, D.; Bernhard, S.

    1991-10-22

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

  18. The antioxidant effect of fermented papaya preparation involves iron chelation.

    PubMed

    Prus, E; Fibach, E

    2012-01-01

    Iron-overload is a major clinical problem in various diseases. Under this condition, serum iron which surpasses the binding capacity of transferrin is present as non-transferrin bound iron and cellular unbound Labile Iron Pool (LIP) is increased. LIP participates in the generation of free radicals, including reactive oxygen species (ROS). Increased ROS, with concomitant decrease in anti-oxidants, results in oxidative stress and toxicity to the liver, heart and other tissues, causing serious morbidity and eventually mortality. Therapeutic iron chelation reduces the LIP and thereby ameliorates oxidative stress-mediated toxicity. Many food-derived antioxidants have the capacities to scavenge ROS and chelate iron. We have reported that fermented papaya preparation (FPP) has ROS scavenging effect on blood cells in vitro or in vivo (in thalassemic patients and experimental animals). We now investigated FPP's iron chelating effect - its ability to prevent (and revert) LIP accumulation. Liver- and heart-derived cells, and RBCs were exposed to non-transferrin bound iron in the form of ferrous ammonium sulfate and the effect of FPP on their LIP content and ROS generation was measured by flow-cytometry. The results indicate that FPP reduces LIP and ROS, and suggests that its antioxidant mechanism is related, at least in part, to iron chelation. PMID:22824747

  19. Metal chelation, radical scavenging and inhibition of Aβ₄₂ fibrillation by food constituents in relation to Alzheimer's disease.

    PubMed

    Chan, Stephen; Kantham, Srinivas; Rao, Venkatesan M; Palanivelu, Manoj Kumar; Pham, Hoang L; Shaw, P Nicholas; McGeary, Ross P; Ross, Benjamin P

    2016-05-15

    Various food constituents have been proposed as disease-modifying agents for Alzheimer's disease (AD), due to epidemiological evidence of their beneficial effects, and for their ability to ameliorate factors linked to AD pathogenesis, namely by: chelating iron, copper and zinc; scavenging reactive oxygen species; and suppressing the fibrillation of amyloid-beta peptide (Aβ). In this study, nine different food constituents (l-ascorbic acid, caffeic acid, caffeine, curcumin, (-)-epigallocatechin gallate (EGCG), gallic acid, propyl gallate, resveratrol, and α-tocopherol) were investigated for their effects on the above factors, using metal chelation assays, antioxidant assays, and assays of Aβ42 fibrillation. An assay method was developed using 5-Br-PAPS to examine the complexation of Zn(II) and Cu(II). EGCG, gallic acid, and curcumin were identified as a multifunctional compounds, however their poor brain uptake might limit their therapeutic effects. The antioxidants l-ascorbic acid and α-tocopherol, with better brain uptake, deserve further investigation for specifically addressing oxidative stress within the AD brain. PMID:26775960

  20. Rhodium catalyzed chelation-assisted C-H bond functionalization reactions

    PubMed Central

    Colby, Denise A.; Tsai, Andy S.; Bergman, Robert G.; Ellman, Jonathan A.

    2011-01-01

    Conspectus Over the last several decades, researchers have achieved remarkable progress in the field of organometallic chemistry. The development of metal-catalyzed cross-coupling reactions represents a paradigm shift in chemical synthesis, and today synthetic chemists can readily access carbon-carbon and carbon-heteroatom bonds from a vast array of starting compounds. Although we cannot understate the importance of these methods, the required pre-functionalization to carry out these reactions adds cost and reduces the availability of the starting reagents. The use of C-H bond activation in lieu of pre-functionalization has presented a tantalizing alternative to classical cross-coupling reactions. Researchers have met the challenges of selectivity and reactivity associated with the development of C-H bond functionalization reactions with an explosion of creative advances in substrate and catalyst design. Literature reports on selectivity based on steric effects, acidity, and electronic and directing group effects are now numerous. Our group has developed an array of C-H bond functionalization reactions that take advantage of a chelating directing group, and this Account surveys our progress in this area. The use of chelation control in C-H bond functionalization offers several advantages with respect to substrate scope and application to total synthesis. The predictability and decreased dependence on the inherent stereoelectronics of the substrate generally result in selective and high yielding transformations with broad applicability. The nature of the chelating moiety can be chosen to serve as a functional handle in subsequent elaborations. Our work began with the use of Rh(I) catalysts in intramolecular aromatic C-H annulations, which we further developed to include enantioselective transformations. The application of this chemistry to the simple olefinic C-H bonds found in α,β-unsaturated imines allowed access to highly substituted olefins, pyridines, and