Showing papers on "Zinc published in 2007"
TL;DR: Effects of five types of nanoparticles on seed germination and root growth of six higher plant species were investigated and inhibition on root growth varied greatly among nanoparticles and plants.
1,522 citations
Patent•
03 Dec 2007TL;DR: The uppermost semiconductor layer is relatively strong against plasma shock and less decomposed when being exposed to plasma, thereby suppressing an increase in carrier concentration as mentioned in this paper, which has a relatively stable bonding energy against plasma.
Abstract: A TFT includes a zinc oxide (ZnO)-based channel layer having a plurality of semiconductor layers. An uppermost of the plurality of semiconductor layers has a Zn concentration less than that of a lower semiconductor layer to suppress an oxygen vacancy due to plasma. The uppermost semiconductor layer of the channel layer also has a tin (Sn) oxide, a chloride, a fluoride, or the like, which has a relatively stable bonding energy against plasma. The uppermost semiconductor layer is relatively strong against plasma shock and less decomposed when being exposed to plasma, thereby suppressing an increase in carrier concentration.
1,050 citations
TL;DR: A nucleation-based model is developed to explain the formation of the wurtzite phase during the catalyzed growth of freestanding nanowires of zinc blende semiconductors and shows that in vapor-liquid-solid nanowire growth, nucleation generally occurs preferentially at the triple phase line.
Abstract: We develop a nucleation-based model to explain the formation of the wurtzite phase during the catalyzed growth of freestanding nanowires of zinc blende semiconductors. We show that in vapor-liquid-solid nanowire growth, nucleation generally occurs preferentially at the triple phase line. This entails major differences between zinc blende and wurtzite nuclei. Depending on the pertinent interface energies, wurtzite nucleation is favored at high liquid supersaturation. This explains our systematic observation of zinc blende during early growth of gold-catalyzed GaAs nanowires.
726 citations
TL;DR: The preparation and characterization of two zinc MOFs based on a flexible and emissive linker molecule, stilbene, which retains its luminescence within these solid materials are described, resulting in luminescent crystals with increased emission lifetimes compared to solutions of trans-stilbenes.
Abstract: Applications of metal−organic frameworks (MOFs) require close correlation between their structure and function. We describe the preparation and characterization of two zinc MOFs based on a flexible and emissive linker molecule, stilbene, which retains its luminescence within these solid materials. Reaction of trans-4,4‘-stilbene dicarboxylic acid and zinc nitrate in N,N-dimethylformamide (DMF) yielded a dense 2-D network, 1, featuring zinc in both octahedral and tetrahedral coordination environments connected by trans-stilbene links. Similar reaction in N,N-diethylformamide (DEF) at higher temperatures resulted in a porous, 3-D framework structure, 2. This framework consists of two interpenetrating cubic lattices, each featuring basic zinc carboxylate vertices joined by trans-stilbene, analogous to the isoreticular MOF (IRMOF) series. We demonstrate that the optical properties of both 1 and 2 correlate with the local ligand environments observed in the crystal structures. Steady-state and time-resolved sp...
608 citations
TL;DR: The results suggest that the zinc wave is involved in intracellular signaling events, at least in part by modulating the duration and strength of FcɛRI-mediated signaling.
Abstract: Zinc is an essential trace element required for enzymatic activity and for maintaining the conformation of many transcription factors; thus, zinc homeostasis is tightly regulated. Although zinc affects several signaling molecules and may act as a neurotransmitter, it remains unknown whether zinc acts as an intracellular second messenger capable of transducing extracellular stimuli into intracellular signaling events. In this study, we report that the cross-linking of the high affinity immunoglobin E receptor (Fce receptor I [FceRI]) induced a release of free zinc from the perinuclear area, including the endoplasmic reticulum in mast cells, a phenomenon we call the zinc wave. The zinc wave was dependent on calcium influx and mitogen-activated protein kinase/extracellular signal-regulated kinase kinase activation. The results suggest that the zinc wave is involved in intracellular signaling events, at least in part by modulating the duration and strength of FceRI-mediated signaling. Collectively, our findings indicate that zinc is a novel intracellular second messenger.
527 citations
TL;DR: It is suggested that topical zinc therapy is underappreciated even though clinical evidence emphasizes its importance in autodebridement, anti‐infective action, and promotion of epithelialization.
Abstract: Zinc is an essential trace element in the human body and its importance in health and disease is appreciated. It serves as a cofactor in numerous transcription factors and enzyme systems including zinc-dependent matrix metalloproteinases that augment autodebridement and keratinocyte migration during wound repair. Zinc confers resistance to epithelial apoptosis through cytoprotection against reactive oxygen species and bacterial toxins possibly through antioxidant activity of the cysteine-rich metallothioneins. Zinc deficiency of hereditary or dietary cause can lead to pathological changes and delayed wound healing. Oral zinc supplementation may be beneficial in treating zinc-deficient leg ulcer patients, but its therapeutic place in surgical patients needs further clarification. Topical administration of zinc appears to be superior to oral therapy due to its action in reducing superinfections and necrotic material via enhanced local defense systems and collagenolytic activity, and the sustained release of zinc ions that stimulates epithelialization of wounds in normozincemic individuals. Zinc oxide in paste bandages (Unna boot) protects and soothes inflamed peri-ulcer skin. Zinc is transported through the skin from these formulations, although the systemic effects seem insignificant. We present here the first comprehensive account of zinc in wound management in relation to current concepts of wound bed preparation and the wound-healing cascade. This review article suggests that topical zinc therapy is underappreciated even though clinical evidence emphasizes its importance in autodebridement, anti-infective action, and promotion of epithelialization.
496 citations
TL;DR: It is concluded that natural clay can be used as an effective adsorbent for removing Cu(2+) and Zn(2+) from aqueous solutions.
456 citations
TL;DR: After zinc supplementation, the incidence of infections was significantlyLower, plasma zinc was significantly higher, and generation of tumor necrosis factor alpha and oxidative stress markers was significantly lower in the zinc-supplemented than in the placebo group.
441 citations
TL;DR: It is proposed that miR398 is a key factor in copper homeostasis in plants and regulates the stability of mRNAs of major copper proteins under copper-limited conditions, which takes place in response to changes in a low range of copper levels.
394 citations
TL;DR: Results from kinetics experiments suggest that cleavage of the phosphorus chalcogenide double bond (TOP=E) proceeds by the nucleophilic attack of phosphonate or oleate on a (TOP-E)-M complex, generating the initial M-E bond.
Abstract: The molecular mechanism of precursor evolution in the synthesis of colloidal group II−VI semiconductor nanocrystals was studied using 1H, 13C, and 31P NMR spectroscopy and mass spectrometry. Tri-n-butylphosphine chalcogenides (TBPE; E = S, Se, Te) react with an oleic acid complex of cadmium or zinc (M−OA; M = Zn, Cd) in a noncoordinating solvent (octadecene (ODE), n-nonane-d20, or n-decane-d22), affording ME nanocrystals, tri-n-butylphosphine oxide (TBPO), and oleic acid anhydride ((OA)2O). Likewise, the reaction between trialkylphosphine selenide and cadmium n-octadecylphosphonic acid complex (Cd−ODPA) in tri-n-octylphosphine oxide (TOPO) produces CdSe nanocrystals, trialkylphosphine oxide, and anhydrides of n-octadecylphosphonic acid. The disappearance of tri-n-octylphosphine selenide in the presence of Cd−OA and Cd−ODPA can be fit to a single-exponential decay (kobs = (1.30 ± 0.08) × 10-3 s-1, Cd−ODPA, 260 °C, and kobs = (1.51 ± 0.04) × 10-3 s-1, Cd−OA, 117 °C). The reaction approaches completion at 70...
386 citations
TL;DR: In this paper, the authors describe the electrolytic deposition of Zn, Sn and Zn/Sn alloys from a solution of the metal chloride salts separately in urea and ethylene glycol/choline chloride based ionic liquids.
TL;DR: A zinc(II)phtalocyanine-tin(IV)porphyrin dyad with a strong electronic coupling was synthesized and upon light excitation shown to exhibit ultra-fast, long-range electron transfer in a single step as mentioned in this paper.
Abstract: A zinc(II)phtalocyanine-tin(IV)porphyrin dyad with a strong electronic coupling was synthesized and upon light excitation shown to exhibit ultra-fast, long-range electron transfer in a single step.
TL;DR: This poster presents a probabilistic procedure to characterize the response of the immune system to chemotherapy-like injuries to treat central nervous disease.
Abstract: Reference LPI-ARTICLE-2007-001View record in Web of Science Record created on 2007-01-09, modified on 2017-05-12
TL;DR: In this paper, a flower-shaped ZnO nanostructures were synthesized by the solution process using zinc acetate dihydrate and sodium hydroxide at very low temperature of 90°C in 30min.
TL;DR: In this paper, the authors report characteristic of indium gallium zinc oxides (GIZOs) which is strongly associated with the film surface, and they show that at the pressure of 8×10−6Torr, the turn-on voltage dramatically shifts to nearly −47V of the negative gate bias direction.
Abstract: In this study, the authors report characteristic of indium gallium zinc oxides (GIZOs) which is strongly associated with the film surface. In ambient air, turn-on voltage of GIZO thin film transistors is approximately −7V. However, at the pressure of 8×10−6Torr, the turn-on voltage dramatically shifts to nearly −47V of the negative gate bias direction. When the oxygen is introduced in the chamber, the turn-on voltage returns to the normal value, that of air. It is believed that the adsorbed oxygen forms depletion layer below the surface, resulting in Von shifts. The carrier concentration of the channel varies from 1×1019to1×1020cm−3 due to oxygen adsorption.
TL;DR: Toxic impacts of lead, copper, and zinc over a concentration gradient of 0.05-0.20 mg/L on proline, malondialdehyde (MDA), and superoxide dismutase (SOD) in the cyanobacterium Spirulina platensis-S5 pointed to the occurrence of a scavenging mechanism.
TL;DR: A review of the literature and identifying key themes in the reported mechanisms for the attractive properties of zinc-magnesium coated steel (ZMG) can be found in this article, where a 3-fold increase in time to red rust compared to conventional zinc-coated steel was measured.
TL;DR: Aligned zinc oxide nanorods were synthesized directly via a two-step solution approach on an Al2O3 tube, and were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) as mentioned in this paper.
Abstract: Aligned zinc oxide nanorods were synthesized directly via a two-step solution approach on an Al2O3 tube, and were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The zinc oxide nanorods prepared were uniform with diameters of 10–30 nm and lengths about 1.4 μm. The response Sr (= Ra/Rg) of the aligned zinc oxide nanorod sensor reached 18.29 and 10.41 to 100 ppm ethanol and hydrogen, respectively, which was a two-fold increase compared with that reported in literature, demonstrating the potential for developing stable and sensitive gas sensors.
TL;DR: The correlation of the infrared spectra of zinc(II) carboxylates with their structures was investigated and conclusions about the carboxyate binding which resulted from the Delta values, were confronted with the crystal structure of the complexes.
TL;DR: 5-ketogluconic acid, a derivative of gluconic Acid as the major organic acid produced by G. diazotrophicus PAl5 cultured with glucose as carbon source, may be an important agent that helped in the solubilization of insoluble Zn compounds.
TL;DR: A working group meeting was convened by the World Health Organization, the United Nations Children's Fund, the International Atomic Energy Agency, and the International Zinc Nutrition Consultative Group to provide standard recommendations for the use of specific biochemical, dietary, and functional indicators of zinc status in populations.
Abstract: Zinc deficiency is an important cause of morbidity in developing countries, particularly among young children, yet little information is available on the global prevalence of zinc deficiency. A working group meeting was convened by the World Health Organization (WHO), the United Nations Children's Fund (UNICEF), the International Atomic Energy Agency (IAEA), and the International Zinc Nutrition Consultative Group (IZiNCG) to review methods of assessing population zinc status and provide standard recommendations for the use of specific biochemical, dietary, and functional indicators of zinc status in populations. The recommended biochemical indicator is the prevalence of serum zinc concentration less than the age/sex/time of day-specific cutoffs; when the prevalence is greater than 20%, intervention to improve zinc status is recommended. For dietary indicators, the prevalence (or probability) of zinc intakes below the appropriate estimated average requirement (EAR) should be used, as determined from quantitative dietary intake assessments. Where the prevalence of inadequate intakes of zinc is greater than 25%, the risk of zinc deficiency is considered to be elevated. Previous studies indicate that stunted children respond to zinc supplementation with increased growth. When the prevalence of low height-for-age is 20% or more, the prevalence of zinc deficiency may also be elevated. Ideally, all three types of indicators would be used together to obtain the best estimate of the risk of zinc deficiency in a population and to identify specific subgroups with elevated risk. These recommended indicators should be applied for national assessment of zinc status and to indicate the need for zinc interventions. The prevalence of low serum zinc and inadequate zinc intakes may be used to evaluate their impact on the target population's zinc status.
TL;DR: Serum zinc concentration can be considered a useful biomarker of a population's risk of zinc deficiency and response to zinc interventions, although it may not be a reliable indicator of individual zinc status.
Abstract: Assessing the prevalence and severity of zinc deficiency in populations is critical to determine the need for and appropriate targeting of zinc intervention programs and to assess their effectiveness for improving the health and well-being of high-risk populations. However, there is very little information on the zinc status of populations worldwide due to the lack of consensus on appropriate biochemical indicators of zinc status. The objective of this review was to evaluate the use of serum zinc concentration as an indicator of population zinc status.We have reviewed the response of serum zinc concentration to dietary zinc restriction and zinc supplementation. In addition, we completed pooled analyses of nine zinc intervention trials in young children to assess the relations between serum zinc concentration of individuals before treatment and their responses to zinc supplementation. Also, in updated combined analyses of previously published data, we investigated the relation between the mean initial seru...
TL;DR: In this paper, the authors provide an overview of zinc metabolism and a description of inherited and acquired zinc deficiency, which is made by way of clinical presentation together with histopathology and laboratory tests.
Abstract: Acrodermatitis enteropathica is a rare autosomal recessive disorder of zinc deficiency. The genetic defect has been mapped to 8q24 and the defective gene identified as SLC39A4, which encodes the zinc transporter Zip4. The diagnosis is made by way of clinical presentation together with histopathology and laboratory tests. Here we provide an overview of zinc metabolism and a description of inherited and acquired zinc deficiency.
TL;DR: It is concluded that zinc has an important role in cell-mediated immune functions and also functions as antiinflammatory and antioxidant agent.
Abstract: Zinc deficiency in humans decreases the activity of serum thymulin (a thymic hormone), which is required for maturation of T-helper cells. T-helper 1 (Th(1)) cytokines are decreased but T-helper 2 (Th(2)) cytokines are not affected by zinc deficiency in humans. This shift of Th(1) to Th(2) function results in cell-mediated immune dysfunction. Because IL-2 production (Th(1) cytokine) is decreased, this leads to decreased activities of natural-killer cell and T cytolytic cells, which are involved in killing viruses, bacteria, and tumor cells. In humans, zinc deficiency may decrease the generation of new CD4+ T cells from the thymus. In cell culture studies (HUT-78, a Th(0) human malignant lymphoblastoid cell line), as a result of zinc deficiency, nuclear factor-kappaB (NF-kappaB) activation, phosphorylation of IkappaB, and binding of NF-kappaB to DNA are decreased and this results in decreased Th(1) cytokine production. In another study, zinc supplementation to humans decreased the gene expression and production of pro-inflammatory cytokines and decreased oxidative stress markers. In HL-60 cells (a human pro-myelocytic leukemia cell line), zinc deficiency increased the levels of TNF-alpha, IL-1beta, and IL-8 cytokines and mRNA. In these cells, zinc induced A20, a zinc finger protein that inhibited NF-kappaB activation via tumor necrosis factor receptor associated factor pathway, and this decreased gene expression of pro-inflammatory cytokines and oxidative stress markers. We conclude that zinc has an important role in cell-mediated immune functions and also functions as antiinflammatory and antioxidant agent.
TL;DR: In this article, the authors report the growth of ultralong ZnO nanowires on silicon (100) substrates via the gold-catalyzed vapor transport approach.
Abstract: We report the growth of ultralong ZnO nanowires on silicon (100) substrates via the gold-catalyzed vapor transport approach. An ample supply of zinc vapor generated through carbothermal reduction o...
TL;DR: It is suggested that microbially derived extracellular proteins can limit the dispersal of nanoparticulate metal-bearing phases, such as the mineral products of bioremediation, that may otherwise be transported away from their source by subsurface fluid flow.
Abstract: High-spatial-resolution secondary ion microprobe spectrometry, synchrotron radiation-based Fourier-transform infrared spectroscopy, and polyacrylamide gel analysis demonstrated the intimate association of proteins with spheroidal aggregates of biogenic zinc sulfide nanocrystals, an example of extracellular biomineralization. Experiments involving synthetic zinc sulfide nanoparticles and representative amino acids indicated a driving role for cysteine in rapid nanoparticle aggregation. These findings suggest that microbially derived extracellular proteins can limit the dispersal of nanoparticulate metal-bearing phases, such as the mineral products of bioremediation, that may otherwise be transported away from their source by subsurface fluid flow.
TL;DR: A molecular platform for dual-function fluorescence/MRI sensing of mobile zinc with strategically attached porphyrin template is reported, anticipating that in vivo applications of the probes will facilitate a deeper understanding of the physiological roles of zinc and allow detection of abnormal zinc homeostasis for pathological diagnoses.
Abstract: We report a molecular platform for dual-function fluorescence/MRI sensing of mobile zinc. Zinc-selective binding units were strategically attached to a water-soluble porphyrin template. The synthetic strategy for achieving the designed target ligand is flexible and convenient, and the key intermediates can be applied as general building blocks for the construction of other metal sensors based on a similar mechanism. The metal-free form, (DPA-C2)2-TPPS3 (1), where DPA is dipicolylamine and TPPS3 is 5-phenyl-10,15,20-tris(4-sulfonatophenyl)porphine, is an excellent fluorescent sensor for zinc. It has certain superior physical properties compared with earlier-generation zinc sensors including emission in the red and near-IR regions [λem = 645 nm (s) and 715 nm (m)], with a large Stokes shift of >230 nm. The fluorescence intensity of 1 increases by >10-fold upon zinc binding. The fluorescence “turn-on” is highly selective for zinc versus other divalent metal ions and is relatively pH-insensitive within the biologically relevant pH window. The manganese derivative, [(DPA-C2)2-TPPS3Mn(III)] (2), switches the function of the molecule to generate an MRI contrast agent. In the presence of zinc, the relaxivity of 2 in aqueous solution is significantly altered, which makes it a promising zinc MRI sensor. Both metal-free and Mn(III)-inserted forms are efficiently taken up by live cells, and the intracellular zinc can be imaged by either fluorescence or MR, respectively. We anticipate that in vivo applications of the probes will facilitate a deeper understanding of the physiological roles of zinc and allow detection of abnormal zinc homeostasis for pathological diagnoses.
TL;DR: Zinc homeostasis has been demonstrated to affect dendritic cells, in particular the involvement of zinc transport proteins during lipopolysaccharide-induced upregulation of major histocompatibility complex proteins and co-stimulatory molecules.
TL;DR: In this paper, the trace metal content of nine fish species harvested from the Black and Aegean Seas were determined by microwave digestion and atomic absorption spectroscopy (MD-AAS).
TL;DR: These chemical characteristics match cellular requirements for Zn(II) and suggest how the molecular structures and redox chemistries of metallothionein and thionein determine Zn (II) availability for biological processes.
Abstract: Each of the seven Zn(II) ions in the Zn(3)S(9) and Zn(4)S(11) clusters of human metallothionein is in a tetrathiolate coordination environment. Yet analysis of Zn(II) association with thionein, the apoprotein, and analysis of Zn(II) dissociation from metallothionein using the fluorescent chelating agents FluoZin-3 and RhodZin-3 reveal at least three classes of sites with affinities that differ by 4 orders of magnitude. Four Zn(II) ions are bound with an apparent average log K of 11.8, and with the methods employed, their binding is indistinguishable. This binding property makes thionein a strong chelating agent. One Zn(II) ion is relatively weakly bound, with a log K of 7.7, making metallothionein a zinc donor in the absence of thionein. The binding data demonstrate that Zn(II) binds with at least four species: Zn(4)T, Zn(5)T, Zn(6)T, and Zn(7)T. Zn(5)T and Zn(6)T bind Zn(II) with a log K of approximately 10 and are the predominant species at micromolar concentrations of metallothionein in cells. Central to the function of the protein is the reactivity of its cysteine side chains in the absence and presence of Zn(II). Chelating agents, such as physiological ligands with moderate affinities for Zn(II), cause dissociation of Zn(II) ions from metallothionein at pH 7.4 (Zn(7)T Zn(7-n)T + nZn(2+)), thereby affecting the reactivity of its thiols. Thus, the rate of thiol oxidation increases in the presence of Zn(II) acceptors but decreases if more free Zn(II) becomes available. Thionein is such an acceptor. It regulates the reactivity and availability of free Zn(II) from metallothionein. At thionein/metallothionein ratios > 0.75, free Zn(II) ions are below a pZn (-log[Zn(2+)](free)) of 11.8, and at ratios < 0.75, relatively large fluctuations of free Zn(II) ions are possible (pZn between 7 and 11). These chemical characteristics match cellular requirements for Zn(II) and suggest how the molecular structures and redox chemistries of metallothionein and thionein determine Zn(II) availability for biological processes.