Search results for "ZINC"
showing 10 items of 1081 documents
Characteristic intraepidermal nerve fibre endings of the intervibrissal fur in the mystacial pad of the rat: morphological details revealed by intrav…
1999
Light microscopic observations employing intravital methylene blue staining and impregnation by the zinc iodide-osmium tetroxide technique are presented for intraepidermal nerve fibre endings of the intervibrissal fur in the mystacial pad of the rat snout. Both procedures revealed anatomical details of the intraepidermal nerve fibre plexus in epidermal hillocks often located very close to the mouths of hairs. These nerve fibres appeared to resemble those described in previous immunohistochemical studies as cluster or bush endings. The methylene blue preparations demonstrated the existence of an intensely stained enlargement at the site of the branching point of the nerve fibres which seemed…
Analytical Study of Raw Materials of Zinc Oxide Used for Enamels on Industrial Ceramics: Quantitative Analysis of Zinc, Lead, and Sulfur in These Sam…
2006
Abstract An analytical study is carried out to optimize X‐ray fluorescence (XRF) and flame atomic absorption spectrometry (FAAS) quantitative analysis of Zn, Pb, and S in ZnO samples commonly used to obtain industrial ceramic enamels. Pb and S in the raw materials often contaminate ZnO and are very detrimental in industrial applications. Thus, very accurate analytical determination of these elements in ceramic samples is extremely important. First of all, a mineralogical study by X‐ray diffraction (XRD) on the different components in these raw materials and the materials produced during the firing process is performed in order to establish the mineral forms in a reference sample for analysi…
Stereoselective synthesis of 1-aminoalkanephosphonic acids with two chiral centers and their activity towards leucine aminopeptidase
2003
The stereoselective synthesis of 1-amino-2-alkylalkanephosphonic acids, namely, compounds bearing two chiral centers, was achieved by the condensation of hypophosphorous acid salts of (R)(+) or (S)(-)-N-alpha-methylbenzylamine with the appropriate aldehydes in isopropanol. Simultaneous deprotection and oxidation by the action of bromine water provided equimolar mixtures of the RS:RR and SR:SS diastereomers of desired acids. They appeared to act as moderate inhibitors of kidney leucine aminopeptidase with potency dependent on the absolute configuration of both centers of chirality.
Calcium, iron and zinc uptakes by Caco-2 cells from white beans and effect of cooking
2006
White beans (Phaseolus vulgaris L.) have an interesting content of essential elements, calcium, iron and zinc, but they content also phytates, oxalates, proteins, polyyphenols and complex polysaccharides that are known to interact with minerals and to affect their bioavailability. The bioavailability of calcium, iron and zinc from raw and cooked white beans was estimated using their uptake by Caco-2 cells as the criteria. Previously, the mineral fraction (soluble or dialysable) to be added to the Caco-2 cell monolayer was selected. The results obtained show that cooking increases the Caco-2 cells' uptake percentages (calcium, 18.8 versus 3.6; iron, 33.7 versus 1.7; and zinc, 17.2 versus 2.1…
Effects and future trends of casein phosphopeptides on zinc bioavailability
2007
This review focuses on studies of the effects of CPPs on zinc bioavailability. It evaluates the main differences in studies performed in the last two decades, such as methodology used to measure zinc, food matrix, CPP preparation, CPP dose, CPP:Zn molar ratio and presence and concentration of zinc absorption inhibitors, such as phytate, iron and calcium. The future trends of CPPs as functional ingredients in zinc-enriched or zinc-containing foods are also discussed.
Control on the morphology and photoelectrocatalytic properties of ZnO nanostructures by simple anodization varying electrolyte composition
2021
Abstract Zinc oxide nanostructured electrodes were successfully synthesized by a simple method of anodization in different aqueous bicarbonate electrolytes. The influence of the anodization electrolyte composition (by adding ethanol or glycerol) on the morphology and the photoelectrocatalytic properties of the zinc oxide electrodes was studied, as well as the combined effect of anodizing under controlled hydrodynamic conditions. Field Emission Scanning Electron Microscope (FE-SEM) images of the ZnO electrodes showed that the addition of ethanol or glycerol to the anodization electrolyte resulted in changes in size and morphology of the nanostructures. Thus, ZnO nanowires, nanotubes, nanospo…
Erroneous p-type assignment by Hall effect measurements in annealed ZnO films grown on InP substrate
2013
We report on incorrect carrier type identification achieved by Hall effect measurements performed on ZnO films grown by pulsed laser deposition on InP substrates and subsequently annealed for 1 h at 600 C in air. While Hall measurements, after post-growth annealing, reveal a change in the electrical properties of the films, from n-type to p-type, both photocurrent-based and standard C V measurements performed on the same samples show no change in the native n-type doping of the ZnO films. A possible interpretation of the two results is reported. In particular, p-type conductivity observed by Hall effect may be ascribed to a highly conductive thin layer formed during the annealing process at…
Controlling the oxidation processes of Zn nanoparticles produced by pulsed laser ablation in aqueous solution
2016
We used online UV-VIS optical absorption and photoluminescence spectra, acquired during and after pulsed laser ablation of a Zinc plate in aqueous solution, to investigate the effect of the laser repetition rate and liquid environment on the oxidation processes of the produced nanoparticles. A transient Zn/ZnO core-shell structure was revealed by the coexistence of an absorption peak around 5.0 eV due to Zn surface plasmon resonance and of an edge at 3.4 eV coming from wurtzite ZnO. The growth kinetics of ZnO at the various repetition rates, selectively probed by the excitonic emission at 3.3 eV, began immediately at the onset of laser ablation and was largely independent of the repetition …
Raman and photoluminescence spectroscopy of zinc tungstate powders
2009
ZnWO4 powders, synthesized using co-precipitation technique and annealed in air at different temperatures in the range of 80-800 � C, were studied by Raman and photoluminescence spectroscopy. ZnWO4 single crystal was used for comparison. The interpretation of the observed variations of the Raman spectra and intrinsic photoluminescence band upon annealing is suggested.
Correlation between Zn vacancies and photoluminescence emission in ZnO films.
2006
Photoluminescence and positron annihilation spectroscopy have been used to characterize and identify vacancy-type defects produced in ZnO films grown on sapphire by metal-organic chemical-vapor deposition. The photoluminescence of the samples in the near band edge region has been studied, paying particular attention to the emission at 370.5 nm (3.346 eV). This emission has been correlated to the concentration of Zn vacancies in the films, which has been determined by positron annihilation spectroscopy. Jesus.Zuniga@uv.es Vicente.Munoz@uv.es