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Search Results: 1 - 10 of 474103 matches for " Wagner de S.;Kelecom "
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International Recommendations on Calculation of Absorbed Dose in Biota: A Comprehensive Revue  [PDF]
Wagner de S. Pereira, Alphonse Kelecom
Journal of Environmental Protection (JEP) , 2014, DOI: 10.4236/jep.2014.59077
Abstract:

Since the early times, radioprotection has been focused on the human being. Currently this approach has changed, being now also necessary to take care of the protection of the environment from unwanted effects of ionizing radiation. To this end, several institutions (UNSCEAR, ICRP, IAEA, DOE, ACRP) and consortia of institutions (FASSET, ERICA) have established procedures in order to protect the biota of such effects. Developed procedures are based on the calculation of the absorbed dose in biota (ICRP, DOE, IAEA), or on environmental risk assessment―ERA (DOE, ACRP, FASSET, ERICA); but even in this latter approach the parameters used are related to the absorbed doses in biota. The calculation of dose is the standard procedure in human radioprotection, and this points such an approach as the most interesting for providing a convergence between human and nonhuman (= biota) radioprotections. On the other hand, the ERA approach is easier to apply, because this methodology is used in several countries for non-radioactive contamination assessments. Since the world radioprotection system follows a number of institutions (UNSCEAR, ICRP, IAEA and regulatory institutions of member countries) that use dose calculation, this appears to be the way for biota radioprotection. We here review and comment the evolution of the concepts and approaches of the recommendations for radioprotection of non-human biota.

Analysis of Radium Isotopes in Surface Waters nearby a Phosphate Mining with NORM at Santa Quitéria, Brazil  [PDF]
Wagner de S. Pereira, Alphonse Kelecom, Juliana R. de S. Pereira
Journal of Environmental Protection (JEP) , 2014, DOI: 10.4236/jep.2014.53023
Abstract:

The radium isotopes 226Ra and 228Ra were analyzed in surface water at six points in the neighborhood of a mine of phosphate, associated with uranium, in the region of Santa Quitéria, state of Ceará, Brazil. Water samples were collected during twenty months, filtered and the concentrations of activity determined in the soluble and particulate phases. The results were analyzed using the Principal Component Analysis (PCA) for ordination of environmental data, and also by ANOVA, Tukey and Z tests to compare sets of data considering the radionuclides, the two analyzed phases and the six collecting points. The PCA identified four groups that included all collecting points, using aggregation features such as radionuclide and analyzed phase. The first group is composed by the samples of 226Ra in the soluble phase; the second group by samples of 226Ra in the particulate phase; the third one by 228Ra in the soluble phase, and finally, the fourth group by 228Ra in the particulate phase. This last group has two discrepant points (01 and 06). Statistical analysis identified differences between the concentrations of activity of radionuclides (228Ra higher than 226Ra) and in analyzed phases (soluble phase higher than the particulate one) but showed no differences between sampled points.

Release of Uranium by an Ore Treatment Unit at Caldas, MG, Brazil  [PDF]
Wagner de S. Pereira, Alphonse Kelecom, Juliana R. de S. Pereira, Delcy de A. Py Júnior
Journal of Environmental Protection (JEP) , 2013, DOI: 10.4236/jep.2013.46066
Abstract:

This study aims to assess the behavior of the release of Unat (i.e. uranium isotopes in natural relative abundance) from the release of water treated by the Ore Treatment Unit (UTM) in Caldas, state of Minas Gerais, Brazil, during the years 1999 to 2009. During this period, the unit showed no industrial activity, except between 2004 and 2005, when UTM operated 400 tons of monazite in a process to obtain rare earths. Unat was analyzed by spectrophotometry once per week in the effluent waters at sampling point 014. Two fractions were considered for analysis: the soluble one (that passes through a 0.45 μm filter) and the particulate one (retained on a 0.45 μm filter). Statistical analyses were performed: the “Z” test and Pearson’s r2 correlation index. The values for the soluble fraction were consistently lower than those of the particulate fraction and no statistically significant correlation was observed between the soluble and particulate fractions. However, the particulate and the total fractions (the sum of soluble and particulate) strongly correlated.

Activity of natural radionuclides and their contribution to the absorbed dose in the fish cubera snapper (lutjanus cyanopterus, cuvier, 1828) on the coast of Ceara, Brazil
Pereira, Wagner de S.;Kelecom, Alphonse;Py Júnior, Delcy de A.;
Brazilian Journal of Oceanography , 2010, DOI: 10.1590/S1679-87592010000800005
Abstract: a methodology was developed for converting the activity concentration of radionuclides (bq kg-1) into absorbed dose rate (gy y-1), aiming an approach to environmental radioprotection based on the concept of standard dose limit. the model considers only the internal absorbed dose rate. this methodology was applied to the cubera snapper fish (lutjanus cyanopterus, cuvier, 1828) caught off the coast of ceará. the natural radionuclides considered were uranium-238, radium-226, lead-210, thorium-232 and radium-228. the absorbed dose rates were calculated for individual radionuclides and the type of emitted radiation. the average dose rate due to these radionuclides was 5.36 μgy y-1, a value six orders of magnitude smaller than the threshold value of absorbed dose rate used in this study (3.65 103 mgy y-1), and similar to that found in the literature for benthic fish. ra-226 and u-238 contributed 67% and 22% of the absorbed dose rate, followed by th-232 with 10%. ra-228 and pb-210, in turn, accounted for less than 1% of the absorbed dose rate. this distribution is somewhat different from that reported in the literature, where the ra-226 accounts for 86% of the absorbed dose rate.
Teores elevados de Pol nio-210 em plantas aquáticas da restinga de Carapebus, RJ
Kelecom Alphonse,Santos Pedro Lopes dos,Gouvea Rita de Cássia S.,Dutra Iedo Ramos
Química Nova , 1999,
Abstract: 210Po concentrations have been determined in one green alga and in five freshwater plants grown in a pond of the Carapebus restinga (State of Rio de Janeiro). The alga Chara sp showed elevated concentration of 210Po, similar to that observed for marine algae. All the other plants had the lowest concentration of 210Po in the stems and the highest in the roots. Intermediate values were observed in the leaves. The unexpected high concentration of 210Po in the roots, even superior to reported values for roots of plants from high radioactive background areas, must be due to the elevated levels of this radionuclide in associated soils that are known to be rich in humic organic material. There seem to have been no translocation of this radionuclide from the roots to the other parts of the plants.
Teores elevados de Pol?nio-210 em plantas aquáticas da restinga de Carapebus, RJ
Kelecom, Alphonse;Santos, Pedro Lopes dos;Gouvea, Rita de Cássia S.;Dutra, Iedo Ramos;Fevereiro, Paulo Cesar Ayres;
Química Nova , 1999, DOI: 10.1590/S0100-40421999000500007
Abstract: 210po concentrations have been determined in one green alga and in five freshwater plants grown in a pond of the carapebus restinga (state of rio de janeiro). the alga chara sp showed elevated concentration of 210po, similar to that observed for marine algae. all the other plants had the lowest concentration of 210po in the stems and the highest in the roots. intermediate values were observed in the leaves. the unexpected high concentration of 210po in the roots, even superior to reported values for roots of plants from high radioactive background areas, must be due to the elevated levels of this radionuclide in associated soils that are known to be rich in humic organic material. there seem to have been no translocation of this radionuclide from the roots to the other parts of the plants.
Lignanes from the Brazilian Melia azedarach, and their activity in Rhodnius prolixus (Hemiptera, Reduviidae)
Cabral, Marise M. O.;Garcia, Eloi S.;Kelecom, Alphonse;
Memórias do Instituto Oswaldo Cruz , 1995, DOI: 10.1590/S0074-02761995000600018
Abstract: a study of the phagoinhibitor and anti-moulting activities of the brazilian melia azedarach, collected in the state of rio de janeiro, brazil, allowed the isolation of four lignanes identified as pinoresinol, bis-epi-pinoresinol, the hemicetal and the diacid. these substances are devoid of anti-moulting activity.
Modelos de aten??o à saúde: a organiza??o de Equipes de Referência na rede básica da Secretaria Municipal de Saúde de Betim, Minas Gerais
Carvalho, Sérgio Resende;Campos, Gast?o Wagner de Sousa;
Cadernos de Saúde Pública , 2000, DOI: 10.1590/S0102-311X2000000200021
Abstract: this article describes and analyzes a new basic health care system approach termed reference teams, or health unit teams accountable for a reference population, organized in betim, minas gerais. empirical data and other forms of evidence were collected by the authors with the purpose of describing the project's history. based on this experience and other studies on the subject, some theoretical reflections shaping models for health care reform were formulated.
Algoritmo preditivo baseado em modelo aplicado ao controle de velocidade do motor de indu??o
Santana, Eudemario S. de;Bim, Edson;Amaral, Wagner C.;
Sba: Controle & Automa??o Sociedade Brasileira de Automatica , 2008, DOI: 10.1590/S0103-17592008000200005
Abstract: this article presents the results concerning the control of rotor flux and speed of the induction motor using mbpc algorithm. a nonlinear state space model of induction motor is used to describe its dynamic. the rotor flux and speed are estimated using an extended kalman filter. the load torque is considered as a disturbance and its value is calculated through the electromechanical equation. simulated and experimental results have shown the good performance of this strategy.
UV Aerosol Indices from SCIAMACHY: introducing the SCattering Index (SCI)
M. J. M. Penning de Vries, S. Beirle,T. Wagner
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2009,
Abstract: The Absorbing Aerosol Index (AAI) is a useful tool for detecting aerosols that absorb UV radiation – especially in cases where other aerosol retrievals fail, such as over bright surfaces (e.g. desert) and in the presence of clouds. The AAI does not, however, consider contributions from scattering (hardly absorbing) aerosols and clouds: they cause negative AAI values and are usually disregarded. In this paper, we demonstrate the use of the AAI's negative counterpart, the SCattering Index (SCI) to detect scattering aerosols. Consideration of the full UV Aerosol Index scale is of importance if the Aerosol Index is to be used for the quantification of aerosol absorption in the future. Maps of seasonally averaged SCI show significantly enhanced values in summer in Southeast USA and Southeast Asia, pointing to a high production of scattering aerosols (presumably mainly sulphate aerosols and secondary organic aerosols) in this season. The application of a cloud filter makes the presence of scattering aerosols even more clear. Radiative transfer calculations were performed to investigate the sensitivity of AAI and SCI to cloud parameters, and it is demonstrated that clouds cause significant SCI, in some special cases even small AAI values. The results from cloud modelling imply that cloud effects need to be taken into account when AAI and SCI are used in a quantitative manner. The paper concludes with a comparison of aerosol parameters from AERONET and our Aerosol Indices (AAI and SCI) from SCIAMACHY, where reasonable agreement was found for six AERONET stations in Southeast USA, Southeast Asia, and Africa. These findings corroborate the suitability of SCI as a tool to detect scattering aerosols.
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