Showing papers on "Zinc published in 1997"
TL;DR: In this paper, the authors used sequential extraction to fractionate four heavy metals (Cd, Cu, Ni, and Zn) from nine contaminated soils into six operationally defined groups: water soluble, exchangeable, carbonate, Fe-Mn oxide, organic, and residual.
Abstract: Heavy metals are potentially toxic to human life and the environment. Metal toxicity depends on chemical associations in soils. For this reason, determining the chemical form of a metal in soils is important to evaluate its mobility and bioavailability. Sequential extraction was used to fractionate four heavy metals (Cd, Cu, Ni, and Zn) from nine contaminated soils into six operationally defined groups: water soluble, exchangeable, carbonate, Fe-Mn oxide, organic, and residual. The residual fraction was the most abundant pool for all four metals examined. A significant amount (2.4-44%) of Zn was present in the potentially available fraction: nonresidual fraction. A major portion (40-74%) of Cu was associated with the organic, Fe-Mn oxide, and carbonate fractions in most of the soils. Contamination of Cd and ni in these soils was not as severe as Zn and Cu. Assuming that mobility and bioavailability of these metals are related to their solubility and geochemical forms, and that they decrease in the order of extraction sequence, the apparent mobility and potential bioavailability for these four metals in the soils were: Zn > Cu > Cd > Ni. Metal distributions in different chemical fractions in these soils depended on respective total metal concentrations, except formore » Zn. 41 refs., 1 fig., 5 tabs.« less
676 citations
TL;DR: In this article, a homogeneous and stable solution was prepared by dissolving the zinc acetate in a solution of 2methoxyethanol and monoethanolamine, which was obtained by preheating the dip-coating films at temperatures from 200° − 500°C for 10 min after each coating and postheating at temperatures between 500° − 800°c for 1 h.
583 citations
TL;DR: In this paper, the growth of p-type ZnO film was realized for the first time by the simultaneous addition of NH3 in carrier hydrogen and excess Zn in source Zn O powder.
Abstract: The growth of p-type ZnO film was realized for the first time by the simultaneous addition of NH3 in carrier hydrogen and excess Zn in source ZnO powder. The resistivity was typically 100 Ωcm. A model showing nitrogen incorporation suggests the possibility of realizing p-type ZnO film of low resistivity by optimizing thermal annealing.
558 citations
07 Mar 1997
TL;DR: In this paper, the bioavailability and ion channel function radiotracers for nutritionally essential mineral elements were assessed by bioavailability, ion channel functions, and interaction between mineral elements.
Abstract: Calcium phosphorus sodium and chloride in nutrition magnesium potassium zinc copper iron magnesium cobalt chronium molybdenum nickel boron lithium lead selenium iodine fluorine silicon vanadium arsenic mineral-iron interaction as assessed by bioavailability and ion channel function radiotracers for nutritionally essential mineral elements.
557 citations
TL;DR: Increased levels of chelatable zinc have been shown to be present in cell cultures of immune cells undergoing apoptosis, very reminiscent of the zinc staining of neuronal perikarya dying after an episode of ischemia or seizure activity.
546 citations
TL;DR: Zinc transporter-3 (ZnT-3) as mentioned in this paper is a member of a growing family of mammalian zinc transporters, which is expressed in regions of the brain that are rich in histochemically reactive zinc (as revealed by the Timm's stain), including entorhinal cortex, amygdala, and hippocampus.
Abstract: Zinc transporter-3 (ZnT-3), a member of a growing family of mammalian zinc transporters, is expressed in regions of the brain that are rich in histochemically reactive zinc (as revealed by the Timm’s stain), including entorhinal cortex, amygdala, and hippocampus. ZnT-3 protein is most abundant in the zinc-enriched mossy fibers that project from the dentate granule cells to hilar and CA3 pyramidal neurons. We show here by electron microscopy that ZnT-3 decorates the membranes of all clear, small, round synaptic vesicles (SVs) in the mossy fiber boutons of both mouse and monkey. Furthermore, up to 60–80% of these SVs contain Timm’s-stainable zinc. The coincidence of ZnT-3 on the membranes of SVs that accumulate zinc, and its homology with known zinc transporters, suggest that ZnT-3 is responsible for the transport of zinc into SVs, and hence for the ability of these neurons to release zinc upon excitation.
326 citations
TL;DR: In this article, the effect of six different zinc (Zn) application methods on grain yield and concentrations of Zn in whole shoots and grain was studied in wheat cultivars (Triticum aestivum, L. cvs. Gerek and Desf. Kunduru).
Abstract: The effect of six different zinc (Zn) application methods on grain yield and concentrations of Zn in whole shoots and grain was studied in wheat cultivars (Triticum aestivum, L. cvs. Gerek‐79, Dagdas‐94 and Bezostaja‐1 and Triticum durum, Desf. cv. Kunduru‐1149) grown on severely Zn‐deficient calcareous soils (DTPA‐extractable Zn: 0.12 mg‐kg‐1 soil) of Central Anatolia which is the major wheat growing area of Turkey. Zinc application methods tested were: a) control (no Zn application), b) soil, c) seed, d) leaf, e) soil+leaf, and f) seed+leaf applications. Irrespective of the method, application of Zn significantly increased grain yield in all cultivars. Compared to the control, increases in grain yield were about 260% with soil, soil+leaf, and seed+leaf, 204% with seed and 124% with leaf application of Zn. In a similar manner, biomass production (dry weight of above‐ground parts) was increased by Zn treatments. The highest increase (109%) was obtained with the soil application and the lowest inc...
276 citations
TL;DR: Evidence is presented that Zap1p regulates transcription of its own promoter in response to zinc through a positive autoregulatory mechanism and plays a central role in zinc ion homeostasis by regulating transcription of the zinc uptake system genes in Response to zinc.
Abstract: Zinc ion homeostasis in Saccharomyces cerevisiae is controlled primarily through the transcriptional regulation of zinc uptake systems in response to intracellular zinc levels. A high-affinity uptake system is encoded by the ZRT1 gene, and its expression is induced more than 30-fold in zinc-limited cells. A low-affinity transporter is encoded by the ZRT2 gene, and this system is also regulated by zinc. We used a genetic approach to isolate mutants whose ZRT1 expression is no longer repressed in zinc-replete cells, and a new gene, ZAP1, was identified. ZAP1 encodes a 93-kDa protein with sequence similarity to transcriptional activators; the C-terminal 174 amino acids contains five C2H2 zinc finger domains, and the N terminus (residues 1 to 706) has two potential acidic activation domains. The N-terminal region also contains 12% histidine and cysteine residues. The mutant allele isolated, ZAP1-1up, is semidominant and caused high-level expression of ZRT1 and ZRT2 in both zinc-limited and zinc-replete cells. This phenotype is the result of a mutation that substitutes a serine for a cysteine residue in the N-terminal region. A zap1 deletion mutant grew well on zinc-replete media but poorly on zinc-limiting media. This mutant had low-level ZRT1 and ZRT2 expression in zinc-limited as well as zinc-replete cells. These data indicate that Zap1p plays a central role in zinc ion homeostasis by regulating transcription of the zinc uptake system genes in response to zinc. Finally, we present evidence that Zap1p regulates transcription of its own promoter in response to zinc through a positive autoregulatory mechanism.
267 citations
TL;DR: In prostate epithelial cells, in situ mitochondrial zinc levels inhibit m-aconitase activity, which provides a mechanism by which citrate oxidation is limited, and is revealed for the first time that zinc is a specific inhibitor of m-aconsitase of mammalian cells.
254 citations
TL;DR: In this article, the equilibrium isotherms of zinc adsorption onto natural bentonite show that the data correlate well with Freundlich and Langmuir models and that the adsoreption is physical in nature.
246 citations
TL;DR: In this article, the Raman and infrared spectra of zinc phosphate glasses, xZnO·(1−x)P2O5 with 0≤x≤0.5, and the crystalline compounds, o′-P 2O5, ZnP4O11, α1-, α2-, and β-Zn(PO3)2, were measured.
Abstract: The Raman and infrared spectra of zinc phosphate glasses, xZnO·(1−x)P2O5 with 0≤x≤0.5, and the crystalline compounds, o′-P2O5, ZnP4O11, α1-, α2-, and β-Zn(PO3)2, were measured. An analysis of the vibrational spectra is discussed in comparison with the results of the investigation of the same glasses by 31 P -MAS–NMR spectroscopy and X-ray diffraction. The structure of the zinc phosphate glasses can be described by substructures of the high-temperature modifications of the three crystalline compounds with x=0, 0.33, and 0.5.
TL;DR: In this paper, the effect of sediment redox conditions on the behavior of As, Cd, Cr, and Zn in bottom sediment collected from a Louisiana coastal site receiving produced water discharge was quantified.
TL;DR: In this paper, the effect of particle size, contact time, and surface loading of zinc and cadmium on the adsorbent for their removal have been studied at the optimum pH (6.0 for Zn2+ and 5.5 for Cd2+).
Abstract: Blast furnace slag, a waste generated in steel plants in India, has been converted into a low cost potential adsorbent. The resulting product has been characterized and used for the removal of zinc and cadmium. The effect of particle size, contact time, and surface loading of zinc and cadmium on the adsorbent for their removal have been studied at the optimum pH (6.0 for Zn2+ and 5.0 for Cd2+). Kinetic studies were undertaken to show the mechanistic aspects of the process and to obtain the thermodynamic parameters. Sorption data have been correlated with both Langmuir and Freundlich adsorption models. Column operations were also performed in an attempt to simulate industrial conditions. Some feasibility experiments have been performed with a view to recovering Zn2+ and Cd2+ and for the chemical regeneration of the spent columns without dismantling them.
TL;DR: In this paper, the competitive effect of exopolysaccharide (EPS) on the uptake of various heavy metals on the Alteromonas macleodii subsp fijiensis has been studied using the Langmuir model for bisolute systems.
TL;DR: The metal biosorbent granules prepared are a value-added product that has the potential for removal/recovery of lead and zinc from dilute solutions on a commercial scale.
TL;DR: In this article, zinc oxide films were deposited by a rf magnetron sputtering using a zinc oxide target and characterized as a function of deposition temperature, pressure, argon-oxygen gas flow ratio, target-substrate distance.
TL;DR: Differential modulation of NR1/NR2A and NR1-NR2B currents by zinc may play a role in regulating NMDA receptor-induced synaptic plasticity and neurotoxicity.
Abstract: Zinc has been shown to be present in synaptic vesicles of a subset of glutamatergic boutons and is believed to be coreleased with glutamate at these synapses. A variety of studies have suggested that zinc might play a role in modulation of excitatory transmission, as well as excitotoxicity, by inhibitingN-methyl-d-aspartate (NMDA)-type glutamate receptors. To further investigate the modulatory effects of zinc on NMDA receptors of different subunit compositions, we coexpressed the recombinant subunit NR1 with NR2A and/or NR2B in HEK 293 cells. In whole-cell patch-clamp recordings from these transfected cells, zinc inhibited peak glutamate-evoked current responses in a noncompetitive manner, but there were significant differences between the receptor subtypes in sensitivity to zinc inhibition. For NR1/NR2A, ∼40% of the peak current was inhibited by zinc in a voltage-independent manner with an IC50 value of 5.0 ± 1.6 nm and at a VH value of −60 mV; the remainder was blocked at a second, voltage-dependent site with an IC50 value of 79 ± 18 μm. In contrast, NR1/NR2B currents showed nearly complete inhibition at a voltage-independent site with an IC50 value of 9.5 ± 3.3 μm. Cells cotransfected with NR1, NR2A, and NR2B showed zinc sensitivity intermediate between that characteristic of NR1/NR2A and that of NR1/NR2B. Furthermore, zinc accelerated the macroscopic desensitization of both NR1/NR2A and NR1/NR2B in a dose-dependent manner, apparently independently of glycine-sensitive desensitization and Ca2+-dependent inactivation; maximal effects were to decrease desensitization time constants for NR1/NR2A by ∼75% and for NR1/NR2B by ∼90%. Differential modulation of NR1/NR2A and NR1/NR2B currents by zinc may play a role in regulating NMDA receptor-induced synaptic plasticity and neurotoxicity.
TL;DR: Zinc and zinc+iron supplements reduced morbidity but had no effect on growth or body composition, and the extent to which growth stunting could be reversed and the number of infectious disease episodes reduced by zinc and/or iron supplementation was assessed.
TL;DR: In this article, a family of peptides modeled after the zinc finger domains, which has led to the production of a fluorescent peptidyl sensor for divalent zinc with enhanced oxidative stability, are reported.
Abstract: The design, synthesis, and characterization of a family of peptides modeled after the zinc finger domains, which has led to the production of a fluorescent peptidyl sensor for divalent zinc with enhanced oxidative stability, are reported. The chemosensor design comprises a synthetic peptidyl template and a covalently attached fluorescent reporter which is sensitive to metal-induced conformational changes in the polypeptide construct. The modular synthetic approach employed for the construction of these chemosensors allows independent modification of the metal coordination sphere and the fluorescent reporter group. The structural, fluorescence, and zinc binding properties of these peptides and the effects of integrating various environment sensitive fluorophores, 4-(dimethylamino)benzamide, 5-(dimethylamino)naphthalenesulfonamide, and 3-carboxamidocoumarin, are described. Manipulation of the ligand sphere, by removal of one of the pair of thiolate ligands, was undertaken to enhance the oxidative stability ...
Journal Article•
TL;DR: In this article, a dansylamidoethyl−pendant cyclen (1-(2-(5-(dimethylamino)-1-naphthalenesulfonamido)ethyl)-1,4,7,10-tetraazacyclododecane, HL) has been synthesized as a novel type of zinc(II)−fluorophore.
Abstract: On the basis of the chemical principle of carbonic anhydrase (CA)−aromatic sulfonamide inhibitor interaction, a dansylamidoethyl−pendant cyclen (1-(2-(5-(dimethylamino)-1-naphthalenesulfonamido)ethyl)-1,4,7,10-tetraazacyclododecane, HL) has been synthesized as a novel type of zinc(II)−fluorophore. The new ligand HL forms very stable complexes (ML) with zinc(II), cadmium(II), and copper(II) at physiological pH. The potentiometric and spectrophotometric pH-titration study disclosed the 1:1 metal(II) complexes stability constants log K(ML) (= log([ML]/[M][L])) to be 20.8 ± 0.1 for ZnL, 19.1 ± 0.1 for CdL, and >30 for CuL. The crystalline zinc(II) complex ZnL was isolated from aqueous solution at pH 7. The X-ray crystal study of ZnL disclosed a five-coordinate, distorted square-pyramidal structure with the deprotonated dansylamide N- coordinating at the apical site. Crystals of the monoperchlorate salt of ZnL (C22H35N6O6SClZn) are orthorhombic, space group Pna21 (no. 33) with a = 23.777(3) A, b = 12.744(5) A,...
Patent•
08 Aug 1997TL;DR: In this article, a spinel type structure was proposed for linear monocarboxylic acid esters with 6 to 26 carbon atoms, which can be used as a fuel or combustible and pure glycerine.
Abstract: For the production of linear monocarboxylic acid esters with 6 to 26 carbon atoms vegetable oils or animal oils, which may or may not be neutral, are reacted with monoalcohols having a low molecular weight, for example 1 to 5 carbon atoms, in the presence of a catalyst that is selected from among zinc oxide, mixtures of zinc oxide and aluminum oxide, and the zinc aluminates that correspond to the formula: ZnAl.sub.2 O.sub.4, x ZnO, y Al.sub.2 O.sub.3 (with x and y each being in the range of 0-2) and having more particularly a spinel type structure, thereby enabling the direct production in one or more stages, of an ester that can be used as a fuel or combustible and a pure glycerine.
TL;DR: In this paper, the structural, electrical, and optical properties of several ternary alloy thin films were examined, and it was shown that a single phase is essential for the highest electrical conductivity and lowest optical absorbance.
Abstract: In this article we examine the structural, electrical, and optical properties of several ternary alloy thin films. The alloys are zinc oxide and cadmium oxide, each of which was reacted with both indium oxide and tin oxide to form sputtering targets. The films were deposited by rf sputtering. X-ray diffraction spectroscopy showed that cadmium stannate, cadmium indate, and zinc stannate films were all polycrystalline spinel phase, but only when deposited at room temperature in pure oxygen and then annealed in argon/cadmium sulfide. The fourth alloy, zinc indate, exhibited a hexagonal phase when prepared under identical conditions. Cadmium stannate has one of the lowest resistivities of any transparent conducting oxide (TCO), has low absorbance in the visible spectrum, and is an excellent compromise between electrical and optical requirements. For this material, we show that a single phase is essential for the highest electrical conductivity and lowest optical absorbance. Zinc stannate has a resistivity more than one order of magnitude higher than cadmium stannate but, because of a larger band gap, has an even lower absorbance. We conclude that there is no “best” TCO, and the decision regarding which to use depends on the specific application and the weighting given to electrical versus optical properties. The zinc-bearing alloys are nontoxic, which may also be an attractive feature for many applications.
TL;DR: In this article, a new method for the synthesis of zinc oxide nanoparticles using ethanol-in-oil microemulsions with Zn-DEHSS (diethylhexyl sulfosuccinate) as surfactant was described.
TL;DR: In this paper, the corrosion and protection characteristics of zinc and manganese phosphate coatings in aqueous solutions were investigated by means of physical methods and electrochemical measurements, and the results showed that the insulation property of zinc phosphate coating is better than that of mananganese phosphate, but the porosity of the former is inferior to that of the latter.
Abstract: The corrosion and protection characteristics of zinc and manganese phosphate coatings in aqueous solutions are investigated by means of physical methods and electrochemical measurements. The results show that the insulation property of zinc phosphate coating is better than that of manganese phosphate, but the porosity of the former is inferior to that of the latter. The anodic current of coated samples decreases and polarization resistance increases compared to the substrate. The corrosion of phosphated steel exhibits the characteristics of no diffusion in acidic solution, a finite-length diffusion in neutral medium, and a semi-infinite diffusion in alkahne solution. Chemical dissolution is the primary form in the failure of phosphate coatings, which is induced by the electrochemical corrosion of the substrate. The protection ability of phosphate coatings mainly depends on their barrier performance.
TL;DR: In this paper, modified montmorillonite compounds and polynuclear Al13 were investigated as potential binding agents to reduce heavy metal solubility in soil solutions, and the experiments were carried out in batch reactors with solutions/suspensions containing Al-13, Al-montmorill lonite, or Al13-almonmine, which was most effective in the pH ranges 6−8 for nickel and zinc, 4−6 for copper and 7−9 for cadmium.
Abstract: Modified montmorillonite compounds and polynuclear Al13 were investigated as potential binding agents to reduce heavy metal solubility in soil solutions. The experiments were carried out in batch reactors with solutions/suspensions containing montmorillonite, polynuclear Al13, Al-montmoril lonite, or Al13-montmorillonite. Nickel, copper, and zinc were adsorbed specifically on Al-montmorillonite and Al13-montmorillonite. These three metals were also incorporated in the interlayers of Al-montmorillonite and Al13-montmorillonite during the aging processes. Al-montmorillonite was most effective in the pH ranges 6−8 for nickel and zinc, 4−6 for copper, and 7−9 for cadmium. The immobilization of the heavy metal cations by Al13-montmorillonite was restricted to a smaller pH range. The polynuclear Al13 decreased the dissolved concentrations of nickel, copper, and zinc by specific binding from pH 6.1 to pH 7.5. In the pH range 5.8−6.1 nickel, copper, zinc, cadmium, and lead formed soluble complexes with Al13, whic...
TL;DR: Evidence that zinc may play a role in a form of long-term potentiation exhibited by the mossy fibre pathway is presented, and a method for imaging zinc release in live brain slices is developed.
TL;DR: In this paper, water quality, metals concentration, and particle size distributions were characterized in urban runoff, and the presence of zinc was highly correlated with organic carbon, each displaying significant concentrations in both size fractions.
Abstract: Water quality, metals concentration, and particle size distributions were characterized in urban runoff. The distribution of metals in the macrocolloidal (0.45–20 μm) and dissolved (<0.45 μm) size fractions was determined from samples taken under both storm and background conditions. Concentrations of particle number, organic carbon, suspended solids, iron, and zinc increased during storms. The presence of zinc was highly correlated with organic carbon, each displaying significant concentrations in both size fractions. Iron existed almost exclusively in the macrocolloidal fraction. Differences in iron and zinc behavior suggest that sedimentation is not always an effective technique for metals removal. Data from two storms followed throughout their duration show individual materials eluting at different stages during storms. These measurements also indicated potential relationships between the zinc/organic carbon and iron/macrocolloid pairs. In addition, elevated contaminant concentrations and increased fl...
TL;DR: A series of phenoxyl radical complexes of zinc(II) have been generated in solution and, in one instance, isolated as solid material (5) in order to study their spectroscopic features by EPR, resonance Raman, and UV−vis spectroscopy as mentioned in this paper.
Abstract: A series of phenoxyl radical complexes of zinc(II) have been generated in solution and, in one instance, isolated as solid material (5) in order to study their spectroscopic features by EPR, resonance Raman, and UV−vis spectroscopy. They serve as model complexes for the active form of the copper containing fungal enzyme galactose oxidase. The complexes [Zn(L1H2)]BF4·H2O (1), [Zn(L2H2)]BF4·H2O (2), [Zn(L2H)] (2a), [Zn(L3)(Ph2acac)] (3), [Zn(L4)(Ph2acac)] (4), and [Zn(L4)(Me-acac)] (6) were synthesized from solutions of Zn(BF4)2·4H2O and the corresponding ligand (L1H3 = 1,4,7-tris(3,5-tert-butyl-2-hydroxybenzyl)-1,4,7-triazacyclononane; L2H3 = 1,4,7-tris(3-tert-butyl-5-methoxy-2-hydroxybenzyl)-1,4,7-triazacyclononane; L3H = 1,4-dimethyl-7-(3,5-di-tert-butyl-2-hydroxybenzyl)-1,4,7-triazacyclononane; L4H = 1,4-dimethyl-7-(3-tert-butyl-5-methoxy-2-hydroxybenzyl)-1,4,7-triazacyclononane, Ph2acac- = 1,3-diphenyl-1,3-propanedionate, and Me-acac- = 3-methyl-2,4-pentanedionate). Complexes 2, 3·0.5 toluene·1n-hexane...
TL;DR: It is hypothesised that the increased zinc level in AD patients is caused by an increase in the amount of ZEN terminals, which could be the result of a sprout of Zen terminals in diseased areas of the brain.
TL;DR: In this article, the absorption spectra for Sm3+ ions in zinc and alkali zinc borosulphate glasses at room temperature were presented and the absorption bands responsible for various transitions were assigned and analyzed in terms of a parametrized model Hamiltonian (HFI).