EVALUATION OF HEAVY METALS CONTENT IN EDIBLE MUSHROOMS BY MICROWAVE DIGESTION AND FLAME ATOMIC ABSORPTION SPECTROMETRY

The aim of this work was to determine the heavy metal (Cd, Cr, Ni, Pb, Mn, Zn, Fe and Cu) content of the fruiting bodies (cap and stipe) of four species (Amanita caesarea, Pleurotus ostreatus, Fistulina hepatica and Armillariella mellea) and their substrate, collected from forest sites in Dâmboviţa County, Romania. The elements were determined by Flame Atomic Absorption Spectrometry (FAAS) after microwave assisted digestion. From the same collecting point were taken n = 5 samples of young and mature fruiting bodies of mushrooms and their substrate. The high concentrations of lead, chrome and cadmium (Pb: 0.25 – 1.89 mg.kg-1, Cr: 0.36 – 1.94 mg.kg-1, Cd: 0.23 – 1.13 mg.kg-1) for all collected wild edible mushrooms, were determined. These data were compared with maximum level for certain contaminants in foodstuffs established by the commission of the European Committees (EC No 466/2001). A quantitative evaluation of the relationship of element uptake by mushrooms from substrate was made by calculating the accumulation coefficient (Ka). The moderately acid pH value of soil influenced the accumulation of Zn and Cd inside of the studied species. The variation of heavy metals content between edible mushrooms species is dependent upon the ability of the species to extract elements from the substrate and on the selective uptake and deposition of metals in tissue

Si Photovoltaic Semiconductor Devices Operating in Total and Partial Illumination

Power photovoltaic applications, as photovoltaic power plants or building integrated photovoltaic systems, are mainly built using parallel or serial photovoltaic modules strings. Daily usage of such systems usually produces non-uniform string connected behavior due to partial or total shading. In these conditions, less illuminated cells transform into power receivers, thus producing supplementary losses and local panel heating. This phenomenon, called hot-spot, may evolve into producing zonal or total destruction of the solar modules. For these purposes this paper will submit to your attention simulation and experimental results of the partial and total illumination phenomenon, targeting specific information in the effect evaluation of any photovoltaic panel

Evaluation of essential elements and heavy metal levels in fruiting bodies of wild mushrooms and their substrate by EDXRF spectrometry and FAA spectrometry

Abstract The essential elements (Zn, Cu, Fe, K, Mn, Mg, Se) and heavy metals (Cd, Cr, Ni, Pb, Ti, Sr, Co, Bi

THE STUDY OF HEAVY METAL FROM ENVIRONMENTAL SAMPLES BY ATOMIC TECHNIQUES

Using the Atomic Absorption Spectrometry (AAS) and Energy Dispersive X-ray spectrometry (EDXRF) techniques we analyzed the contents of heavy metals ( Cd, Cr, Ni, Pb, Ti, Sr, Co, Bi) from eight wild mushrooms and soil substrate samples (48 samples of eight fungal species and 32 underlying soil samples), collected from ten forest sites of Dambovița County Romania. It was determined that the elements, especially heavy metals, in soil were characteristic of the acidic soils of the Romanian forest lands and are influenced by industrial pollution. Analytical possibilities of AAS and EDXRF analytical techniques have been compared and the heavy metal transfer from substrate to mushrooms has been studied. The coefficient of accumulation of essential and heavy metals has been calculated as well. Heavy metal contents of all analyzed mushrooms were generally higher than previously reported in literature

The monitoring of 2d-3d transition for InAs/GaAs (001) self-assembled quantum dots by atomic force microscopy

We present a detailed Atomic Force Microscopy study of InAs/GaAs (001) self-assembled quantum dots, grown by Molecular Beam Epitaxy, during its complete evolution cycle, transition from 2D islands to 3D islands. We created the dots by deposing InAs on a GaAs substrate. After a critical InAs coverage value is reached the dots become self-assembled due to strain. The resulting dots typically have a height of 5.7 nm and an emission at about 900 nm occurs until a second critical coverage point is traversed

Special X-Ray Silicon Detectors for Medical Applications

The paper presents some results concerning the technology and behaviour of X-ray silicon detectors intended for controlling low radiation levels in interventional cardiology. An improved planar process was used for obtaining large area guard-ring test structures. The electrical characteristics, their modification after exposure to radiation and the results of spectroscopic X-ray measurements are discussed