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[en] This project has been carried out to study the devitalization of pork meat cysticerci, using ionizing radiation with doses in the order of 5 KGy, a Co-60 source of 8000 Ci, beloging to Nuclear Science Institute, E.P.N., was use for irradiations. To make the vitality test the cysticerci were prepared by carefully removing the connective tissue of the cysts and then placing them in an isotonic bile solution. Combined treatments were studied in order to reduce requirement of radiation. Organoleptic tests showerd no significant difference al p=0.05 between the treated and untreated samples
[en] Application of differents dosimeter systems: Standard Frickie, Modify Frickie, Yellow Perspex, Amber Perspex, Red Perspex and Clear Prespex, for industrial irradiation were studied. Dosimeter expositions in the range 0.05 KGy to 10 KGy were applied using both a Gammacell 220 source and a semi-industrial irradiator of Co-60, with dosis rates of 0.2 KGy/hr and 4 KGy/hr respectivily. During the experiment variables like storage temperature with 20, 35 and 45 degC were studied. Experimental results point out that Standard Frickie and Perspex dosimeter system can be used successfully with a very low dependence upon storage temperature and storage time
[en] The intermountain basin of the Cauca River, located close to the active margin in western Colombia, is one of the keys to understand the evolution and recent seismic activity in the westernmost Andes in Colombia. The discovery of evidences of neotectonic activity in this basin, between Cali and Cartago, and the application of tectonic and radiometric analysis led to the characterization of three zones with distinctive morpho-structural expressions: 1) Foothills of the Cordillera Central. It shows contemporary normal faulting with Miocene deposits that were reactivated as reverse faults during Quaternary, and back thrusts indicating the existence of a subcritical wedge. Radiometric analysis indicates the episodic nature of the neotectonic activity. 2) Foothills of the Cordillera Occidental. The horizontal component of faulting is predominant over the dip-slip one. 3) Flood plain of the Cauca river. Extensional faulting is common on recent fluvial and lacustrine deposits. Sedimentary structures related to faulting suggest that most of them were produced by liquefaction of the substrate during seismic shaking. The topographic gradient, along the Cauca River is not uniform, it shows a higher slope and greater sinuosity in front of the thrust sheets of the Buga Salient. The results of this work are discussed and compared with existing information and a structural model is provided for this area of western Colombia.
[en] A graptolite fauna, composed dominantly by the genus Phyllograptus (s.l.) ssp., was recovered from the Venado River sequences. The remains, found in grey shales, suggest a Floian-Darriwilian age. As it is suggested by faunal similarities, Early Paleozoic sequences of Colombia were deposited on a passive margin that was connected with Peruvian, Bolivian and Argentinean platform. Furthermore, on the basis of these new data, it is found that stratigraphy nomenclature currently used for the Early Paleozoic series of the Venado River has to be emendated.
[en] Volcanic rocks of Yavi Formation of upper Jurassic? Lower - Cretaceous age from the Media Luna synclinal (Huila Department) were studied. The petrography is described. It is present chemical analyses and his geotectonic position is discussed. The composition of the volcanic rocks indicates subduction-related magmatism. On the basis of geochemical interpretation of the samples (pyroclastic and lava flows) we conclude that they were generated on the margin of a plate in a back arc magmatic system.
[en] We describe the synthesis of 12 new ethyl and methyl quinoxaline-7-carboxylate 1,4-di-N-oxide derivatives on solid supports with room temperature and microwave-assisted solvent-free procedures. Results show that solid supports have good catalytic activity in the formation of quinoxaline 1,4-di-N-oxide derivatives. We found that florisil and montmorillonite KSF and K10 could be used as new, easily available, inexpensive alternatives of catalysts. Additionally, room temperature and microwave-irradiation solvent-free synthesis was more efficient than a conventional procedure (Beirut reaction), reducing reaction time and increasing yield. (author)
[en] In Mexico the use of electron accelerators for treating cancerous tumors had grown enormously in the last decade. When the treatments are carried out with X-ray beam energy below 10 MV the design of the shielding of the radioactive facility is determined by analyzing the interaction of X-rays, which have a direct impact and dispersion, with materials of the facility. However, when it makes use of X-ray beam energy equal to or greater than 10 MV the neutrons presence is imminent due to their generation by the interaction of the primary beam X-ray with materials head of the accelerator and of the table of treatment, mainly. In these cases, the design and calculation of shielding considers the generation of high-energy neutrons which contribute the equivalent dose that public and Occupationally Staff Exposed (POE) will receive in the areas surrounding the facility radioactive. However, very few measurements have been performed to determine the actual contribution to the neutron dose equivalent received by POE and public during working hours. This paper presents an estimate of the actual contribution of the neutron dose equivalent received by public and POE facilities in various radioactive medical use, considering many factors. To this end, measurements were made of the equivalent dose by using a neutron monitor in areas surrounding different radioactive installations (of Mexico) which used electron accelerators medical use during treatment with X-ray beam energy equal to or greater than 10 MV. The results are presented after a statistical analysis of a wide range of measures in order to estimate more reliability real contribution of the neutron dose equivalent for POE and the public. (author)