Search results for "Metals"
showing 10 items of 2013 documents
Discrimination of Lithogenic and Anthropogenic Metals in Calcareous Agricultural Soils: A Case Study of the Lower Vinalopó Region (SE Spain)
2008
Analysis of heavy metal concentrations in soils and their sources is required to identify agricultural areas affected by contamination on a regional level, according to the European Thematic Strategy for Soil Protection. Pseudo-total and EDTA-extractable concentrations of nine elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in eighteen agricultural soils with vegetable crops in the Lower Vinalopo region (southeast Spain) were determined. The main aim was to assess the present state of the agricultural soils in relation to contamination processes by heavy metals for a representative area of the Mediterranean region under semiarid conditions. The pseudo-total concentrations for heavy metals …
A mesoscopic approach to radiation-induced defect aggregation in alkali halides stimulated by the elastic interaction of mobile Frenkel defects
1994
The radiation-induced aggregation of Frenkel defects in alkali halides is studied in terms of a mesoscopic approach. The asymmetry in elastic interactions between mobile interstitials (I–I) and bet...
Metal drugs and the anticancer immune response
2018
The immune system deploys a multitude of innate and adaptive mechanisms not only to ward off pathogens but also to prevent malignant transformation ("immune surveillance"). Hence, a clinically apparent tumor already reflects selection for those malignant cell clones capable of evading immune recognition ("immune evasion"). Metal drugs, besides their well-investigated cytotoxic anticancer effects, massively interact with the cancer-immune interface and can reverse important aspects of immune evasion. This topic has recently gained intense attention based on combination approaches with anticancer immunotherapy (e.g., immune checkpoint inhibitors), a strategy recently delivering first exciting…
Effects of Metal-Organic Chemical Vapour Deposition grown seed layer on the fabrication of well aligned ZnO nanorods by Chemical Bath Deposition
2011
Well aligned, long and uniform ZnO nanorods have been reproducibly fabricated adopting a two-steps Metal-Organic Chemical Vapour Deposition (MOCVD) and Chemical Bath Deposition (CBD) fabrication approaches. Thin (<100 nm) ZnO buffer layers have been seeded on silicon substrates by MOCVD and ZnO layers have been subsequently grown, in form of well textured nanorods, using CBD. It has been found that the structure and thickness of the seed layer strongly influence the final morphology and the crystal texturing of ZnO nanorods as well as the CBD growth rate. There is, in addition, a strong correlation between morphologies of CBD grown ZnO nanorods and those of the seed layer underneath. Thus, …
Stability of biogenic metal(loid) nanomaterials related to the colloidal stabilization theory of chemical nanostructures
2018
In the last 15 years, the exploitation of biological systems (i.e. plants, bacteria, mycelial fungi, yeasts, and algae) to produce metal(loid) (Me)-based nanomaterials has been evaluated as eco-friendly and a cost-effective alternative to the chemical synthesis processes. Although the biological mechanisms of biogenic Me-nanomaterial (Bio-Me-nanomaterials) production are not yet completely elucidated, a key advantage of such bio-nanostructures over those chemically synthesized is related to their natural thermodynamic stability, with several studies ascribed to the presence of an organic layer surrounding these Bio-Me-nanostructures. Different macromolecules (e.g. proteins, peptides, lipids…
Facile formation of a meso–meso linked porphyrin dimer catalyzed by a manganese(iv)–oxo porphyrin
2011
A manganese(IV)-oxo porphyrin catalyzes C-C bond formation between zinc porphyrins at the meso-position with a two-electron oxidant to afford the meso-meso linked porphyrin dimer efficiently. The meso-meso linked dimer is formed via formation of the porphyrin radical cation, and the rate-determining step in the catalytic cycle is the formation of a manganese(IV)-oxo porphyrin with a two-electron oxidant.
Photophysical properties of a rhodium tetraphenylporphyrin-tin corrole dyad. The first example of a through metal-metal bond energy transfer
2005
The luminescence spectroscopy study and the determination of the photophysical parameters for the M-M'-bonded rhodium meso-tetraphenylporphyrin-tin(2,3,7,13,17,18-hexamethyl-8,12-diethylcorrole) complex, (TPP)Rh-Sn(Me6Et2Cor) 1, was investigated. The emission bands as well as the lifetimes (tau(e)) and the quantum yields (Phi(e); at 77 K using 2MeTHF as solvent) were compared with those of (TPP)RhI 2 (TPP = tetraphenylporphyrin) and (Me6Et2Cor)SnCl 3 (Me6Et2Cor = 2,3,7,13,17,18-hexamethyl-8,12-diethylcorrole) which are the two chemical precursors of 1. The energy diagram has been established from the absorption, fluorescence and phosphorescence spectra. The Rh(TPP) and Sn(Me6Et2Cor) chromop…
GENE STRUCTURE, DIFFERENTIAL EXPRESSION AND PHYLOGENETIC ANALYSIS OF THE METALLOTHIONEIN GENE FAMILY OF THE SEA URCHIN PARACENTROTUS LIVIDUS
2017
Metallothioneins (MT) are small and cysteine-rich proteins that bind metal ions such as zinc, copper, cadmium, and nickel1. Several functions were proposed for these peptides, ranging from toxic metal protection to physiological metal homeostasis, free radical scavenging, oxidative stress protection, antiapoptotic defense, control of the redox status of the cell and also roles during development. Previously, we reported the identification of five different MT homologues (PlMT4-8) from the Mediterranean sea urchin species P. lividus2. In order to shed some light on MT gene structure and evolution, we cloned seven P. lividus MT genes, comparing them to Echinodermata and Chordata genes3. Moreo…
Chemical and electrochemical behaviour of 4,4’,4’’,4’’’-tetrakis(dimethylamino)-tetraphenylethylene in an oxidant environment: Toward a new sensor fo…
2020
Abstract Electrochromic compounds are suitable candidates for being used in sensor design. Here we report the use of 4,4’,4’’,4’’’-tetrakis(dimethylamino)-tetraphenylethylene for detecting both NO2 and SO2. Whereas the sensing mechanism in the case of nitrogen dioxide is a simple chemical oxidation reaction, in the case of sulfur dioxide, the mechanism is much more complex and the reaction requires the presence of t-butylhydroperoxide to take place. By modifying the detection conditions both compounds can be detected in gas phase. Additionally, a wide electrochemical study has been carried out to understand the role played by the t-butylhydroperoxide in the reaction with sulfur dioxide.
Electro-optical spectroscopy on aggregated chromophore systems in Langmuir-Blodgett films
1992
Linear and quadratic Stark spectra were measured on LB films that contained a hydrophobically substituted cyanine chromophore in binary mixtures with arachidic acid. The external field was applied normal or parallel to the film surface on samples with different internal symmetry. It was found that the orientation of the symmetry axis of the dye molecule is close to the surface normal. A significant number of molecules, 5–10%, are flipped head-to-tail from the main orientation. Parallel to the film surface, large polarizability changes on electronic excitation, Δα ∼ 1000 A3, were observed that reflect electron delocalization over aggregates. At low dye concentrations, large internal electric…