oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 8 )

2018 ( 6 )

2017 ( 9 )

2016 ( 18 )

Custom range...

Search Results: 1 - 10 of 183 matches for " Alphonse Kelecom "
All listed articles are free for downloading (OA Articles)
Page 1 /183
Display every page Item
Synthesis of Marine Natural Products in Brazil
Kelecom, Alphonse;
Journal of the Brazilian Chemical Society , 1998, DOI: 10.1590/S0103-50531998000200002
Abstract: syntheses of 23 marine natural products carried out in brazil or by brazilian chemists are comprehensively reviewed.
Secondary metabolites from marine microorganisms
KELECOM, ALPHONSE;
Anais da Academia Brasileira de Ciências , 2002, DOI: 10.1590/S0001-37652002000100012
Abstract: after 40 years of intensive research, chemistry of marine natural products has become a mature field. since 1995, there are signals of decreased interest in the search of new metabolites from traditional sources such as macroalgae and octocorals, and the number of annual reports on marine sponges stabilized. on the contrary, metabolites from microorganisms is a rapidly growing field, due, at least in part, to the suspicion that a number of metabolites obtained from algae and invertebrates may be produced by associated microorganisms. studies are concerned with bacteria and fungi, isolated from seawater, sediments, algae, fish and mainly from marine invertebrates such as sponges, mollusks, tunicates, coelenterates and crustaceans. although it is still to early to define tendencies, it may be stated that the metabolites from microorganisms are in most cases quite different from those produced by the invertebrate hosts. nitrogenated metabolites predominate over acetate derivatives, and terpenes are uncommon. among the latter, sesquiterpenes, diterpenes and carotenes have been isolated; among nitrogenated metabolites, amides, cyclic peptides and indole alkaloids predominate.
Marine organisms: an alternative source of potentially valuable natural products
Kelecom, Alphonse;
Memórias do Instituto Oswaldo Cruz , 1991, DOI: 10.1590/S0074-02761991000600024
Abstract: this paper recalls the outcoming of marine natural products research and reviews a selection of marirne bioactive metabolites in current use together with promising trends in marine pharmacology.
Secondary metabolites from marine microorganisms
KELECOM ALPHONSE
Anais da Academia Brasileira de Ciências , 2002,
Abstract: After 40 years of intensive research, chemistry of marine natural products has become a mature field. Since 1995, there are signals of decreased interest in the search of new metabolites from traditional sources such as macroalgae and octocorals, and the number of annual reports on marine sponges stabilized. On the contrary, metabolites from microorganisms is a rapidly growing field, due, at least in part, to the suspicion that a number of metabolites obtained from algae and invertebrates may be produced by associated microorganisms. Studies are concerned with bacteria and fungi, isolated from seawater, sediments, algae, fish and mainly from marine invertebrates such as sponges, mollusks, tunicates, coelenterates and crustaceans. Although it is still to early to define tendencies, it may be stated that the metabolites from microorganisms are in most cases quite different from those produced by the invertebrate hosts. Nitrogenated metabolites predominate over acetate derivatives, and terpenes are uncommon. Among the latter, sesquiterpenes, diterpenes and carotenes have been isolated; among nitrogenated metabolites, amides, cyclic peptides and indole alkaloids predominate.
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.

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.
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.
Page 1 /183
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.