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Showing papers on "Zinc published in 2002"


Journal ArticleDOI
TL;DR: Activated carbon derived from bagasse, an agricultural waste material, has been investigated as a replacement for the current expensive methods of removing heavy metals from wastewater and it was concluded that the adsorption occurs through a film diffusion mechanism at low as well as at higher concentrations.

1,122 citations


Journal ArticleDOI
TL;DR: Thioglycerol-capped luminescent CdS QDs discriminate between copper and zinc ions and are therefore suitable for the analysis of copper ions in biological samples in the presence of physiological concentrations of zinc ions.
Abstract: Water-soluble luminescent CdS quantum dots (QDs) capped by polyphosphate, l-cysteine, and thioglycerol were synthesized in aqueous solution. The ligands were found to have a profound effect on the luminesence response of CdS QDs to physiologically important metal cations. Polyphosphate-capped CdS QDs were sensitive to nearly all mono- and divalent cations, showing no ion selectivity. Conversely, thioglycerol-capped CdS QDs were sensitive to only copper and iron ions. Similar concentrations of physiologically relevant cations, such as zinc, sodium, potassium, calcium, and magnesium ions did not affect the luminescence of thioglycerol-capped CdS QDs. On the other hand, l-cysteine-capped CdS QDs were sensitive to zinc ions and insensitive to other physiologically important cations, such as copper, calcium, and magnium ions. To demonstrate the detection capability of these new ion probes, l-cysteine and thioglycerol-capped CdS QDs were used to detect zinc and copper ions in physiological buffer samples. The d...

891 citations


Journal ArticleDOI
TL;DR: By decomposing Zn(OH)42- or Zn[NH3]42+ precursor in various solvents at suitable reaction conditions, zinc oxide with a diversity of well-defined morphologies was synthesized.
Abstract: By decomposing Zn(OH)42- or Zn(NH3)42+ precursor in various solvents at suitable reaction conditions, zinc oxide with a diversity of well-defined morphologies was synthesized. Flowerlike ZnO built ...

840 citations


Journal ArticleDOI
TL;DR: In this article, the effect of zinc supplementation on the physical growth and serum zinc concentrations of prepubertal children was investigated in a randomized controlled intervention trial with a total of 33 acceptable studies with appropriate data.

638 citations


Journal ArticleDOI
TL;DR: In this paper, two separate fixed bed modified activated carbon columns were used; TBA-carbon column for cyanide removal and SDDC-column for multi-species metal ion removal.

617 citations


Journal ArticleDOI
TL;DR: A pH above 9.0 was essential for the formation of wurtzite zinc oxide (ZnO) in aqueous solution systems as discussed by the authors, and the addition of complexing agents to decrease the deposition rate was required for the direct growth of ZnO on the surface of substrates through heterogeneous nucleation.
Abstract: A pH above 9.0 was essential for the formation of wurtzite zinc oxide (ZnO) in aqueous solution systems. The addition of complexing agents to decrease the deposition rate was required for the direct growth of ZnO on the surface of substrates through heterogeneous nucleation. The nucleation of the crystals was promoted by undercoats derived from zinc acetate. Wurtzite ZnO films consisting of hexagonal columns with diameters of 20–100 nm were successfully prepared on various substrates under suitable conditions.

552 citations


Journal ArticleDOI
TL;DR: The toxicity of ALS‐associated SOD mutants may be related to enhanced catalysis of protein nitration subsequent to zinc loss, and by acting as a high‐capacity zinc sink, NF‐L could foster the formation of zinc‐deficient SOD within motor neurons.
Abstract: Mutations to Cu/Zn superoxide dismutase (SOD) linked to familial amyotrophic lateral sclerosis (ALS) enhance an unknown toxic reaction that leads to the selective degeneration of motor neurons. However, the question of how >50 different missense mutations produce a common toxic phenotype remains perplexing. We found that the zinc affinity of four ALS-associated SOD mutants was decreased up to 30-fold compared to wild-type SOD but that both mutants and wild-type SOD retained copper with similar affinity. Neurofilament-L (NF-L), one of the most abundant proteins in motor neurons, bound multiple zinc atoms with sufficient affinity to potentially remove zinc from both wild-type and mutant SOD while having a lower affinity for copper. The loss of zinc from wild-type SOD approximately doubled its efficiency for catalyzing peroxynitrite-mediated tyrosine nitration, suggesting that one gained function by SOD in ALS may be an indirect consequence of zinc loss. Nitration of protein-bound tyrosines is a permanent modification that can adversely affect protein function. Thus, the toxicity of ALS-associated SOD mutants may be related to enhanced catalysis of protein nitration subsequent to zinc loss. By acting as a high-capacity zinc sink, NF-L could foster the formation of zinc-deficient SOD within motor neurons.

485 citations


Journal ArticleDOI
TL;DR: In this paper, single-crystalline zinc oxide (ZnO) nanowires with high density were successfully synthesized on nickel monoxide (NiO) catalyzed alumina substrate through a simple metal-vapor deposition method at an extremely low temperature (450 °C).

431 citations


Journal ArticleDOI
TL;DR: In this article, a tetrapod-like zinc oxide (T-ZnO) nanorod was produced in bulk quantity by oxidation of Zn powders by a vapor-solid (VS) mechanism.

389 citations


Journal ArticleDOI
TL;DR: Low intracellular zinc status causes oxidative DNA damage and induces DNA-repair protein expression, but binding of p53 and important downstream signals leading to proper DNA repair are lost without zinc.
Abstract: Approximately 10% of the U.S. population ingests <50% of the current recommended daily allowance for zinc. We investigate the effect of zinc deficiency on DNA damage, expression of DNA-repair enzymes, and downstream signaling events in a cell-culture model. Low zinc inhibited cell growth of rat glioma C6 cells and increased oxidative stress. Low intracellular zinc increased DNA single-strand breaks (comet assay). Zinc-deficient C6 cells also exhibited an increase in the expression of the zinc-containing DNA-repair proteins p53 and apurinic endonuclease (APE). Repletion with zinc restored cell growth and reversed DNA damage. APE is a multifunctional protein that not only repairs DNA but also controls DNA-binding activity of many transcription factors that may be involved in cancer progression. The ability of the transcription factors p53, nuclear factor κB, and activator protein 1 (AP1) to bind to consensus DNA sequences was decreased markedly with zinc deficiency, as assayed by electrophoretic mobility-shift assays. Thus, low intracellular zinc status causes oxidative DNA damage and induces DNA-repair protein expression, but binding of p53 and important downstream signals leading to proper DNA repair are lost without zinc.

368 citations


Journal ArticleDOI
TL;DR: A strain of Pseudomonas aeruginosa showed the best solubilization andsolubilized both zinc oxide and zinc phosphate, but only when glucose was provided as a carbon source.
Abstract: Airborne bacteria isolated from a tannery air environment were screened for the property of solubilization of insoluble zinc oxide and zinc phosphate. Out of 10 strains tested, a strain of Pseudomonas aeruginosa (CMG 823) showed the best solubilization and solubilized both zinc oxide and zinc phosphate. Colonies of the bacterium produced clear haloes on solid medium which contained these insoluble metal compounds, but only when glucose was provided as a carbon source. Solubilization of zinc oxide and phosphate was accompanied by an increase in the H+ concentration of the medium, probably a consequence of the production of 2-ketogluconic acid.

Journal ArticleDOI
TL;DR: Red mud, an aluminum industry waste, has been converted into an inexpensive and efficient adsorbent for the removal of cadmium and zinc from aqueous solutions over a wide range of initial metal ion concentrations.
Abstract: Red mud, an aluminum industry waste, has been converted into an inexpensive and efficient adsorbent. The product obtained has been characterized and utilized in batch and column operations for the removal of cadmium and zinc from aqueous solutions over a wide range of initial metal ion concentrations (1.78 × 10-5 to 1.78 × 10-3 M for Cd2+ and 3.06 × 10-5 to 3.06 × 10-3 M for Zn2+; contact time, 24 h) adsorbent dose (5−20 g/L), and pH (1.0−6.0). The removal of Cd2+ and Zn2+ was almost complete at low concentrations, while it was 60−65% at higher concentrations at optimum pH's of 4.0 and 5.0, respectively, with 10 g/L of adsorbent in an 8−10 h equilibration time. The adsorption decreased with increase in temperature. Kinetic studies have been used to describe the mechanism of adsorption. Chemical regeneration of the columns has been achieved with 1% HNO3.

Journal ArticleDOI
TL;DR: In this article, a template-assisted method for synthesizing ZnS nanostructures with controlled morphology has been proposed, using as-synthesized ZnO nanobelts as a template.
Abstract: ZnS, an important wide-bandgap semiconductor, is a photo-luminescence material. [1] Due to its wide bandgap of 3.8 eV, doping of ZnS with elements such as Tb and Eu, [2] can produce a wide range of exciting optical properties. Quantum dots of core±shell structured CdSe/ZnS have been found to exhibit a lasing effect and can be used for fluoro-immunoas-says, biological imaging, and biosensors. [3,4] Quantum confinement induced lasing has been observed in CdSe/ZnS. Semiconducting ZnO is one of the most important functional oxides for smart devices and optoelectronics. Recently, ultra-long nanobelt structures of ZnO, SnO 2 , In 2 O 3 , CdO, Ga 2 O 3 , and PbO 2 have been synthesized by simply evaporating the desired commercial metal oxide powders at high temperatures. [6,7] The as-synthesized oxide nanobelts are pure, structurally uniform, single crystalline, and most of them are free from dislocations. They have a rectangular cross section with typical widths of 100±300 nm, width-to-thickness ratios of 5±10 nm, and lengths of up to a few millimeters. The nano-belts are an ideal system for fully understanding dimensionally confined transport phenomena in functional oxides and for building functional devices along individual nanobelts. Nanosize sensors and field-effect transistors based on individual nanobelts have been fabricated. Colloid based methods are likely the most popular techniques for synthesis of semiconductor quantum dots. In this paper, using as-synthesized ZnO nanobelts as a template , nanostructured ZnS nanocables and nanotubes have been synthesized by chemical reaction. The structure of the ZnS has been analyzed and the corresponding photolumines-cence properties have been measured. A small blue shift is observed for the ZnO±ZnS cable structures, suggesting a small quantum-confinement effect. The template-assisted method is demonstrated to be a unique technique for producing ZnS nanostructures with controlled morphology. We first present the structural change of the ZnO nanobelt pre-and post-reaction with H 2 S. Figure 1a shows a scanning electron microscope (SEM) image of the as-synthesized ZnO nanobelts, which are pure and structurally uniform. A transmission electron microscope (TEM) image of the nanobelts is given in Figure 2a, clearly showing its uniformity in shape. The ZnO nanobelts have two fast growth directions, [0001] and [1010]. [6] For the [0001] ZnO nanobelts, the top surfaces are ± (21 10), and the side surfaces are ± (0110). The contrast observed on the nanobelts is due to bending induced strain, which is the so-called bending contour in electron diffrac-tion. Based …

Journal ArticleDOI
TL;DR: Findings suggest that the zinc-containing tricalcium phosphate is a biomaterial that has a pharmaceutical effect of promoting bone formation.

Journal ArticleDOI
TL;DR: In this paper, fluorescent indicators with nanomolar to micromolar affinities for Zn(2+) have been synthesized in wavelengths from UV to the far red, which exhibit large and pH-independent fluorescence increases with increasing zinc concentrations.

Journal ArticleDOI
TL;DR: The results suggest that ZnT-5 plays an important role for transporting zinc into secretory granules in pancreatic β cells.


Journal ArticleDOI
TL;DR: The evidence supporting zinc's antioxidant role in protecting against free radical‐induced oxidative damage is reviewed, and zinc protects against UV radiation, enhances wound healing, contributes to immune and neuropsychiatric functions, and decreases the relative risk of cancer and cardiovascular disease.
Abstract: Antioxidants play a critical role in keeping skin healthy. The antioxidant benefits of vitamin C and E are well known, but the importance of the trace mineral, zinc, has been overlooked. This article reviews the evidence supporting zinc's antioxidant role in protecting against free radical-induced oxidative damage. Zinc protects against UV radiation, enhances wound healing, contributes to immune and neuropsychiatric functions, and decreases the relative risk of cancer and cardiovascular disease. All body tissues contain zinc; in skin, it is five to six times more concentrated in the epidermis than the dermis. Zinc is required for the normal growth, development and function of mammals. It is an essential element of more than 200 metalloenzymes, including the antioxidant enzyme, superoxide dismutase, and affects their conformity, stability, and activity. Zinc also is important for the proper functioning of the immune system, and for glandular, reproductive and cell health. Abundant evidence demonstrates the antioxidant role of zinc. Topical zinc, in the form of divalent zinc ions, has been reported to provide antioxidant photoprotection for skin. Two antioxidant mechanisms have been proposed for zinc: zinc ions may replace redox active molecules, such as iron and copper, at critical sites in cell membranes and proteins; alternatively, zinc ions may induce the synthesis of metallothionein, sulfhydryl-rich proteins that protect against free radicals. No matter how they work, topical zinc ions may provide an important and helpful antioxidant defense for skin.

Journal ArticleDOI
TL;DR: In this paper, the electrical and optical properties of zinc oxide thin films were investigated as a function of oxygen deposition pressure, and they were used as an anode contact to fabricate organic light-emitting diodes.

Journal ArticleDOI
TL;DR: The results from this report suggest that the intracellular zinc homeostasis is mediated by many ZnT proteins, which act in tissue-, cell-, and organelle-specific manners.

Journal ArticleDOI
TL;DR: The results suggest that all three metals share some common uptake and transport sites on Chlorella cells and that copper out competes both cadmium and zinc for cell binding.
Abstract: The individual and combined effects of copper, cadmium, and zinc on the cell division rate of the tropical freshwater alga Chlorella sp. were determined over 48 to 72 h. Metal mixtures were prepared based on multiples of their single-metal median effective concentration (EC50) values, i.e., toxic units (TU) using a triangular mixture design with five toxicant levels (0, 0.75, 1.0, 1.25, and 1.5 TU). Single-metal EC50 values after a 72-h exposure were 0.11, 0.85, and 1.4 microM for copper, cadmium, and zinc, respectively. Significant interactions were observed for all metal combinations after 48 and 72 h. An equitoxic mixture of Cu + Cd was more than concentration additive (synergistic) to the growth of Chlorella sp., while combinations of Cu + Zn, Cd + Zn, and Cu + Cd + Zn were all less than concentration additive or were antagonistic. To determine the effect of each metal on the uptake of the other, extracellular (membrane-bound) and intracellular metal concentrations, both alone and in mixtures, were compared. The increased growth inhibition observed for mixtures of Cu + Cd was due to higher concentrations of cell-bound and intracellular copper in the presence of cadmium compared with copper alone (i.e., cadmium-enhanced copper uptake). In contrast, both extra- and intracellular cadmium concentrations were reduced in the presence of copper. In mixtures of Cu + Zn, copper also inhibited the binding and cellular uptake of zinc, which resulted in decreased toxicity. Zinc had no appreciable effect on the uptake of copper by Chlorella sp. Our results suggest that all three metals share some common uptake and transport sites on Chlorella cells and that copper out competes both cadmium and zinc for cell binding. Determination of metal cell distribution coefficients (K(d)) confirmed that K(d) values for cadmium and zinc in single-metal exposures decreased in the presence of copper.

Journal ArticleDOI
TL;DR: In this article, the selectivity of the zinc oxide film for a particular gas in presence of others was studied. And the operating temperature was found to play a key role in determining the resistivity of such sensors.
Abstract: Zinc oxide (ZnO) is a versatile material for different commercial applications such as transparent electrodes, piezoelectric devices, varistors, SAW devices etc because of its high piezoelectric coupling, greater stability of its hexagonal phase and its pyroelectric property. In fact, ZnO is a potential material for gas sensor applications. Good quality ZnO films were deposited on glass and quartz substrates by a novel CVD technique using zinc acetate as the starting solution. X-ray diffraction confirmed the crystallinity of the zinc oxide film and SEM study revealed uniform deposition of fine grains. Undoped ZnO films were used for detection of dimethylamine (DMA) and H2 at different temperatures by recording the change in resistivity of the film in presence of the test gases. The response was faster and the sensitivity was higher compared to the earlier reported ZnO based sensors developed in our laboratory. The main objective of this work was to study the selectivity of the ZnO film for a particular gas in presence of the others. The operating temperature was found to play a key role in the selectivity of such sensors.

Journal ArticleDOI
TL;DR: The properties of zinc transport systems in yeast vacuolar membrane vesicles were ATP-dependent, requiring a H+ gradient generated by the V-ATPase for function and showed a high specificity for Zn2+ over other physiologically relevant substrates such as Ca2+, Fe2+, and Mn2+.

Journal ArticleDOI
21 Sep 2002-Langmuir
TL;DR: In this article, aqueous magnetic fluids constituted of zinc ferrite nanoparticles with a size ranging between 4 and 6 nm have been synthesized using a soft chemical approach Chemical analysis has shown that the Zn087Fe209X004O4 (X represents vacancies) obtained silica nanoparticles (40−60 nm) with a ZnFe2O4 magnetic core (4−6 nm) have been characterized by X-ray diffraction, electron microscopy, and magnetization measurements.
Abstract: Synthesis of nanoparticles under restricted environments offered by water-in-oil microemulsions provides excellent control over particle size and shape and interparticle spacing These environments have been used in the synthesis of silica nanoparticles with a ZnFe2O4 magnetic core First, aqueous magnetic fluids constituted of zinc ferrite nanoparticles with a size ranging between 4 and 6 nm have been synthesized using a soft chemical approach Chemical analysis has shown that the zinc ferrite nanoparticles are nonstoichiometric with the estimated formula Zn087Fe209X004O4 (X represents vacancies) The obtained silica nanoparticles (40−60 nm) with a zinc ferrite magnetic core (4−6 nm) have been characterized by X-ray diffraction, electron microscopy, and magnetization measurements Preliminary magnetic measurements have inferred that the magnetic properties of these nanoparticles at low temperature are essentially governed by the interface particle−habitat


Journal ArticleDOI
TL;DR: These relations are considered as indicative of the ability of alfalfa plants to take up elements from a soil matrix contaminated with a mixture of cadmium, copper, nickel, and zinc.

Journal ArticleDOI
TL;DR: The densities of different substituted apatites were close to theoretical for pressed and sintered samples, which is evidence for low bulk porosity, and the grain sizes of substituted apAtite were smaller than those of pure HA except for cadmium-containing apatite.
Abstract: Hydroxylapatite (HA) was made containing magnesium, zinc, cadmium, and yttrium. Salts of these cations were added to precipitating HA; the precipitates were dried and sintered at 1100 degrees C for 1 h. Lattice parameters from X-ray diffraction spectra showed that these elements were incorporated into the apatite structure at a level of 2% added fraction of calcium in HA and up to 7% for yttrium. The densities of different substituted apatites were close to theoretical for pressed and sintered samples, which is evidence for low bulk porosity. The grain sizes of substituted apatites were smaller than those of pure HA except for cadmium-containing apatite. Surfaces of etched samples showed no second phases, whereas surfaces of unetched samples showed second phases and higher porosity than etched surfaces.

Journal ArticleDOI
TL;DR: In this paper, the effects of carbon type and solution pH on adsorption isotherms were evaluated in a batch adsorber, and the results showed that nearly three times as much Zn(II) was adsorbed onto C carbon as on the other three carbon types.

Journal ArticleDOI
TL;DR: In this article, the adsorption behavior of Cd, Zn, and Pb from mixed solutions on synthetically prepared Hydroxyaluminum (HyA)-and Hydrohexaluminosilicate (HAS)-montmorillonite (Mt) complexes within the pH range 4 to 8 was examined.
Abstract: We examined the adsorption behavior of Cd, Zn, and Pb from mixed solutions on synthetically prepared Hydroxyaluminum (HyA)-and Hydroxyaluminosilicate (HAS)-montmorillonite (Mt) complexes within the pH range 4 to 8. Initial concentrations of each metal (Me 1 ) of 1 x 10 -6 M in binary systems and 1 x 10 -6 , 2 x 10 -5 , 5 X 10 -5 M in ternary systems were used in a background electrolyte of 0.01 M NaCIO 4- . The presence of HyA and HAS polymers on Mt greatly increased the adsorption of all three metals. Lead appeared to have the strongest affinity for adsorption on both Mt and on the complexes. The adsorption affinity sequence of Pb > Cd > Zn on Mt did not change with Me 1 and could be explained with hard-soft acid-base (HSAB) theory. On the complexes, the affinity sequences of Zn > Cd in binary systems and Pb » Zn= Cd in most ternary systems were consistent with predictions based on the first hydrolysis constants. We propose that HyA-Mt and HAS-Mt are composed of nonuniform metal adsorption sites. For a given type of site, metal selectivity was predominantly determined by the metal properties, softness and ease of hydrolysis, while ionic potential had a limited predictive index for metal adsorption. The overall adsorption behavior of the metals along with their extraction patterns showed that the strength of adsorption followed the order of Pb » Zn > Cd among the metals and of HyA-Mt =HAS-Mt >> Mt among the adsorbents.

Journal ArticleDOI
TL;DR: In this paper, it was shown that Diels-Alder reactions occur in high yield in novel Lewis acidic ambient temperature ionic liquids composed of choline chloride-MCl2 (1:2) (M = Zn or Sn).