Search Results

You are looking at 11 - 20 of 72 items for

  • Author or Editor: A. Sanchez x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

The enrichment of234U in ground waters is a well established experiments fact. In the course of measurements of uranium contamination in rivers of the Guadiana basin we have found the contamination near the uranium mines with the equilibrium isotope ratios of uranium. With distance from the mines we found not only the expected decrease in contamination but also an increasing enrichment of the lighter isotopes. For the235U isotope, this is the first observation with good separation and low interference between the most significant peaks of each isotope.

Restricted access

Abstract  

To combust coal together with a small percentage (<10%) of sewage sludge may be an option for the management of these wastes. Combustion of two different sewage sludge, one semianthracite coal and several sludges-coal blends (containing different dried mass% of each of the two sewage sludges) were studied by simultaneous TG/MS dynamic runs carried out at 5C min–1 in the temperature range 100–800C. No interactions have been observed between coal and sludge during the blends combustion. Neither the combustion process, neither the studied emissions have changed appreciably for the mass% of sludge in the blends considered in this work.

Restricted access

Abstract  

A thermogravimetric (TG) and mass spectrometric (MS) study was carried out of the process of devolatilization of the organic fraction of municipal solid wastes (OFMSW) and polyethylene terephthalate (PET). This involved an analysis of the heating profiles in an inert atmosphere for each of these residues separately and for a mixture made up of half of each by mass. The fit between the experimental and calculated values was checked by means of the least squares method. No interaction at all was observed between the two types of waste when the fit between the experimental and theoretical figures was checked, in the light of the low values obtained from the objective function showing fit. The study of mass spectrometry shows major emissions of energy-producing gases although fewer pollutants are emitted.

Restricted access

Abstract  

Sewage sludge disposal is a difficult task owing to increasingly restrictive re-use policies. Its final destination will obviously depend on its nature and composition but the generation of energy is a significant option. The thermochemical conversion requires exhaustive gas emission controls. In this regard, this paper offers the results of the use of mass spectrometry together with a thermogravimetric analysis system used to study the thermal conversion processes of two kinds of sewage sludge under different atmospheres simulating pyrolysis, gasification and combustion. This TG-MS combination indicates that gasification is the best process for one kind of sludge while a co-combustion process is more suitable for the other.

Restricted access

Thermal studies on metal complexes of 5-Nitrosopyrimidine derivatives

V. thermal behaviour of Zn(II), Cd(II), Hg(II) and Hg(I) complexes of 4-amino-5-nitroso-6-oxo-1,2,3,6-tetrahydro-2-thiopyrimidine

Journal of Thermal Analysis and Calorimetry
Authors: M. P. Sánchez-Sánchez, J. M. Salas-Peregrin, and M. A. Romero-Molina

New 4-amino-5-nitroso-6-oxo-1,2,3,6-tetrahyaro-2-thiopyrimidine (TANH) complexes of Zn(II), Cd(II), Hg(II) and Hg(I) were prepared and their thermal behaviour was studied by TG and DSC techniques.

Restricted access

Abstract  

The British Nuclear Fuels Limited (BNFL) complex (Sellafield) in Cumbria discharges into the atmosphere, under authorization by the Environment Agency (and previously, the Ministry of Agriculture, Fisheries and Food (MAFF), radioactive waste consisting of gases, mists and dusts. As part of MAFF's radiological surveillance programme, the intake of radionuclides via food ingestion by members of the public living near this nuclear installation is routinely assessed from measurements made on local food and environmental samples and by using computer models simulating the dispersion and incorporation of radioactivity into foodstuffs. In this study, the individual diets of adults and children living near the Sellafield complex and those from a control group were assessed for their radionuclide content. The participants were selected via a food survey questionnaire which was aimed at identifying those who consume home grown fruits and vegetables or derive these from local sources. The diets were collected over a one-week period in August 1995 and following radiochemical analyses of the diets for239+240Pu,137Cs,90Sr,14C, and129I, the doses received by the participants from these nuclides were extrapolated over a one-year period and compared to doses calculated from food surveillance data and to doses predicted using the MAFF food-chain computer model.

Restricted access

Abstract  

Unsupported 210Pb fluxes were determined from sediment core inventories in lakes located in Northern Patagonia, Argentina. Total 210Pb, 226Ra, associated with supported 210Pb, and 137Cs specific activity profiles were measured by gamma-ray spectrometry. Unsupported 210Pb fluxes showed very low values when compared to other regions, with a 12 fold variation, ranging from 4 to 48 Bq m–2.y–1. The linear correlation observed between the 210Pb fluxes and137Cs cumulative fluxes in sediment cores sampled from water bodies within a zone with similar precipitation demonstrated that both radioisotopes behave in the same manner in these systems concerning the processes occurred from fallout to sediment deposition, and that there are no appreciable local or regional sources of unsupported 210Pb. Positive correlation of 210Pb fluxes with organic matter contents of the uppermost sediment core layers was also observed.

Restricted access

Abstract

Here we show a comparison of top economics departments in the US and EU based on a summary measure of the multidimensional prestige of influential papers in 2010. The multidimensional prestige takes into account that several indicators should be used for a distinct analysis of structural changes at the score distribution of paper prestige. We argue that the prestige of influential articles should not only consider one indicator as a single dimension, but in addition take into account further dimensions, since several different indicators have been developed to evaluate the impact of academic papers. After having identified the multidimensionally influential articles from an economics department, their prestige scores can be aggregated to produce a summary measure of the multidimensional prestige of research output of this department, which satisfies numerous properties.

Restricted access