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1.
P. S. Bedregal P. A. Mendoza M. S. Ubillús I. M. Cohen E. H. Montoya 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(2):673-678
The advantages of instrumental neutron activation analysis applied to archaeological ceramics have been enhanced through the analysis of entire objects, using both the k 0 method and the relative method, respectively, to determine the concentrations of chemical elements in aliquots of replicate objects used as comparators and in the sample object. Twenty-two chemical elements of archaeological importance were measured in mud figurines from Caral civilization (5000 year BC), irradiated inside a well-characterized radial channel facility of the nuclear research reactor at IPEN, Peru. The results showed less than 10 % of bias for most of the elements. 相似文献
2.
E. H. R. Montoya I. M. Cohen P. Mendoza Hidalgo B. Torres Chamorro P. Bedregal Salas 《Journal of Radioanalytical and Nuclear Chemistry》1999,240(2):475-479
The errors occurred when α, the parameter that accounts for the non-ideal behavior of the epithermal flux, are neglected,
have been evaluated for the determination of twenty elements in biological materials, using. gold and sodium comparators,
and zirconium to measure the thermal to epithermal flux ratio (f). Sodium allows the determination of 15 elements, and up to 18 elements can be determined in positions relatively well thermalized
by the simultaneous use of gold and sodium comparators, in all the cases with errors ≦2%, when α is not considered. Results
obtained for reference materials are presented. 相似文献
3.
Bedregal Patricia S. Ubillus Marco S. Poma Víctor R. Cohen Isaac M. 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(3):695-701
Journal of Radioanalytical and Nuclear Chemistry - The methodology adopted at the Laboratory of Analytical Techniques of Instituto Peruano de Energía Nuclear for preparation of monitors and... 相似文献
4.
Eduardo H. Montoya Pablo A. Mendoza Patricia S. Bedregal Oscar R. Baltuano Isaac M. Cohen 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(1):175-178
A method that combines the use of non-destructive neutron activation analysis and high-resolution α spectrometry has been
developed for determination of the activities of 234U and 238U in geological samples of low uranium content. The 238U content is determined by k0-based neutron activation analysis, whereas the 234U/238U relationship is measured by α spectrometry after isolation and electrodeposition of the uranium extracted from a lixiviation
with 6 M HCl. The main advantage of the method is the simplicity of the chemical operations, including the fact that the steps
destined to assure similar chemical state for the tracer and the uranium species present in the sample are not necessary.
The method was applied to soil samples from sites of the North Peru Coast. Uranium concentration range 3–40 mg/kg and the
isotopic composition correspond to natural uranium, with about 10% uncertainty. 相似文献
5.
Benjamín Callejas Bedregal 《Journal of Algorithms in Cognition, Informatics and Logic》2007,62(3-4):135-147
Most of the normal forms for fuzzy logics are versions of conjunctive and disjunctive classical normal forms. Unfortunately, they do not always preserve tautologies and contradictions which is important, for example, for automated theorem provers based on refutation methods.De Morgan implicative systems are triples like the De Morgan systems, which consider fuzzy implications instead of t-conorms. These systems can be used to evaluate the formulas of a propositional language based on the logical connectives of negation, conjunction and implication. Therefore, they determine different fuzzy logics, called implicative De Morgan fuzzy logics.In this paper, we will introduce a normal form for implicative De Morgan systems and we will show that for implicative De Morgan fuzzy logics whose t-norms are strict, this normal form preserves contradictions as well as tautologies. 相似文献
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Patricia S. Bedregal Pablo A. Mendoza Isaac M. Cohen Oscar Baltuano Eduardo H. Montoya 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(1):37-42
A new approach for analysis of entire potsherds of archaeological interest by INAA, using the conventional relative method,
is described. The analytical method proposed involves, primarily, the preparation of replicates of the original archaeological
pottery, with well known chemical composition (standard), destined to be irradiated simultaneously, in a well thermalized
external neutron beam of the RP-10 reactor, with the original object (sample). The basic advantage of this proposal is to
avoid the need of performing complicated effect corrections when dealing with large samples, due to neutron self shielding,
neutron self-thermalization and gamma ray attenuation. In addition, and in contrast with the other methods, the main advantages
are the possibility of evaluating the uncertainty of the results and, fundamentally, validating the overall methodology. 相似文献
10.
Blaauw M. Ridikas D. Baytelesov S. Salas P. S. Bedregal Chakrova Y. Eun-Ha Cho Dahalan R. Fortunato A. H. Jacimovic R. Kling A. Muñoz L. Mohamed N. M. A. Párkányi D. Singh T. Van Dong Duong 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(1):409-418
Journal of Radioanalytical and Nuclear Chemistry - Molybdenum-99 is one of the most important radionuclides for medical diagnostics. In 2015, the International Atomic Energy Agency organized a... 相似文献