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1.
D. Desideri C. Roselli A. Rongoni D. Saetta 《Journal of Radioanalytical and Nuclear Chemistry》2005,266(2):191-197
Summary It is well known that the interest in radon concentration indoor as a pollutant emerged during the energy crisis of seventies
which led to reduce ventilation in dwellings. Recently the Euratom Recommendation 2001/928 suggested the necessity of performing
frequent 222Rn checks on tap waters. As a consequence of this Recommendation, Urbino and Perugia Universities carried out a preliminary
222Rn determination on tap waters of the Pesaro-Urbino province. Samplings were carried out in twenty-eight sites and radon concentration
was determined by liquid scintillation counting and gamma-spectrometry. The results obtained by the two techniques were comparable
(the deviation from the mean is lower than 10% for 54.5% of the samples). The resulted 222Rn concentration was very low (5 Bq . l-1 for 43% of the samples) and, therefore, radon in waters cannot be considered as a direct radiological risk for the local
population. 相似文献
2.
Alvarez Carrillo Pavel Anselmo Roselli Lucia Reis Peixoto Frej Eduarda Asfora de Almeida Adiel Teixeira 《Annals of Operations Research》2022,314(2):377-392
Annals of Operations Research - The aim of this paper is to solve an agricultural technology packages selection problem by considering multiple dimensions which influence a maize producer’s... 相似文献
3.
Monitoring the atmospheric stability by using radon concentration measurements: A study in a Central Italy site 总被引:1,自引:0,他引:1
D. Desideri C. Roselli L. Feduzi M. Assunta Meli 《Journal of Radioanalytical and Nuclear Chemistry》2006,270(3):523-530
Summary Meteorological and radon concentration data referring to a measurement campaign carried out in Urbino, Central Italy, are
reported and discussed. This study presents a method allowing monitoring of the vertical atmospheric stability using continuous
measurements of radon gas near ground. In particular radon evidences the presence of temperature inversion such as the formation
of the nocturnal stable layer and gives information on the vertical turbulence and the motion of air masses. This technique
is very useful in describing the temporal evolution of the pollutants in the atmosphere. 相似文献
4.
C. Testa D. Desideri M. A. Meli C. Roselli A. Bassignani P. B. Finazzi 《Journal of Radioanalytical and Nuclear Chemistry》1993,170(1):117-124
Low specific activity scales consisting of alkaline earth metal carbonates and sulfates are often present in some gaseous and liquid hydrocarbon plants; these scales contain a certain concentration of radium, uranium and thorium, which can cause a risk of -irradiation and of internal radiocontamination when they must be mechanically removed. That being stated,238U,232Th and226Ra were determined in scales, sludges and waters coming from different plants.238U and232Th concentrations were found very low; the isotopes238U and234U resulted in radioactive equilibrium, whilst232Th and228Th were not always in equilibrium.226Ra concentration was higher in scales and sludges than in waters. 相似文献
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6.
As is well known ammunitions containing depleted uranium (DU) were used by NATO during the Balkan war. The paper deals with the determination of uranium alpha emitting radiosotopes in Kosovo soils by chemical separation and alpha spectrometry. The samples were collected by CISAM (Centro Interforze Studi ed Applicazioni Militari, S. Piero a Grado, Livorno) in the period November 1999-April 2000. The DU distribution in soil appeared very disomogeneous; the isotope weight percentages for U-238, U-235 and U-234 resulted 99.76, 0.24 and 7.24.10(-4) respectively; consequently the activity distribution was 86.42%, 1.31%, 11.63% and the isotope ratios were 1.52.10(-2) and 0.134 for U-235/U-238 and U-234/U-238 showing clearly the presence of DU. A small peak at 4.49 MeV (U-236) in the alpha spectrum indicated that the used DU was the by-product of exhausted uranium reprocessing. In order to determine the chemical and physiological solubility of uranium a fractionation study was carried out by using the Tessier method: 55% of uranium showed a fair solubility, but 45% was solubilized only by 8 M HNO3. 相似文献
7.
Filippi A Roselli G Renzi G Grandinetti F Speranza M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(9):2072-2078
The kinetics and the stereochemistry of the protonation-induced unimolecular isomerization of (S)-(+)-1-D(1)-3-(p-tolyl)butane have been investigated in the gas phase in the 100-160 degrees C range. The process leads to the almost exclusive formation of the relevant meta isomer with complete racemization and partial 1,2-H shift in the migrating sec-butyl group. These results, together with the relevant activation parameters, point to the occurrence of low-energy, tightly bound isomeric sec-butyl cation/toluene complexes of defined structure and stability along the isomerization coordinate. The existence and the eta(1)-type structure of these low-energy intermediate species are confirmed by ab initio calculations on closely related systems at the MP2(full)/6-311++G**//HF/6-31+G** level of theory. Their role in the relevant energy surface clearly emerges from the comparison of the present results with those concerning sec-butylation of toluene carried out under comparable experimental conditions. 相似文献
8.
Maria Assunta Meli Donatella Desideri Carla Roselli Laura Feduzi 《Microchemical Journal》2011,99(2):273-277
This paper describes the methods of sampling, preconcentration, chemical separation and final count of 210Po and 210Pb present in different marine matrices to determine their background levels in a marine ecosystem. Complex, time consuming and selective radioanalytical methods have been used to prepare final clear sources for alpha spectrometry and beta count; in fact, gamma spectrometry, a method direct and non destructive, cannot be taken into account because the 210Pb activity is very low which does not allow to carry out sufficiently accurate measurements and 210Po is not a gamma emitter but it emits only alpha particle at 5.40 MeV. The results of 210Po and 210Pb activity concentrations obtained in different marine samples collected in the first two campaigns are still very few to discuss about the 210Po and 210Pb behavior in marine environment. 相似文献
9.
The regiochemical behavior of a series of aliphatic open chain epoxides bearing a heterofunctionality in an allylic or homoallylic relationship has been examined in the opening reaction with MeOH under both condensed and gas phase operating conditions. The results indicate that the proton (actually D+) possesses in the gas phase intrinsic chelating properties which are even superior than those of Li+ in the condensed phase. 相似文献
10.
Aequationes mathematicae - In this work we provide the mathematical framework of !FTL, a new gesture recognition algorithm. This allows us to algebraically quantify the notion of shape for a smooth... 相似文献