A medida de traços radioativos, no ambiente e em elimentos, é de fundamental importância para o monitoramento dos níveis de radiação a que o homem està exposto, direta ou indiretamente. Este trabalho consiste na medida de traços radioativos em leite em pó, através da espectrometria gama de alta resolução. Foi possível identificar os radionuclídeos 40K, 137Cs e 232Th (obtido do 208Tl) com as respectivas atividades médias, em Bq/Kg, 482 ± 37, 5,1 - 11,2 and 1,6 - 3,7. Os resultados foram comparados com os limites estabelecidos pela Comissão Nacional de Energia Nuclear (CNEN), apresentando níveis normais para os leites analisados, podendo ser consumido sem restrições.

The control and monitoring of radioactive elements in foodstuffs is fundamental for human health maintenance. This work presents procedures to measure radioactivity levels in powdered milk samples and also a brief discussion of radionuclide transference from the environment to mankind. The measurements were performed utilizing a high-resolution gamma-ray spectrometer using an HPGe detector. The results allowed the quantification of 40K, 137Cs and 208Tl radionuclides. For 40K the average activity was 482 ± 37 Bq/kg and for 137Cs and 208Tl the lower level of detection was, respectively, 3.7 ± 1.1 and 0.5 ± 0.2 (Bq/kg). The results obtained for the milk samples were compared to data found in the literature and to the limits established by the Brazilian National Commission of Nuclear Energy (CNEN) to assure its safety to human consuption.

With the nuclear fission discovery and development of nuclear weapons in 1940s, artifi cial radioisotopes were introduced in the environment. This contamination is due to worldwide fallout by superfi cial nuclear tests realized from early 1950s to late 1970s by USA, former URSS, UK, France and China. One of theses radioisotopes that have been very studied is cesium-137. Cesium-137 has a half-life of 30.2 years and its biological behavior is similar to the potassium. The behavior in soil matrix, depth distribution, spatial variability and inventories values of cesium-137 has been determinate for several regions of the world. In Brazil, some research groups have worked on this subject, but there are few works published about theses properties of cesium-137. The aim of this paper was study the depth distribution, spatial variability, and inventory of cesium-137 in native forest. Two native forests (Mata 1 and Mata UEL) were sampling in region of Londrina, PR. The results shows that there is a spatial variability of 40% for Mata 1 and 42% for Mata UEL. The depth distribution of cesium-137 for two forests presented a exponential form, characteristic to undisturbed soil. Cesium-137 inventory determinate for Mata 1 was 358 Bq m-2 and for Mata UEL was 320 Bq m-2.

The recent resumption of the synthesis of new superheavy nuclei has provided relevant results for nuclear physics and chemistry. These nuclei provide experimental confirmation of theoretical calculations that predict the existence of two islands of stability, one with maximum stability in Z=114 and N=184 and the other in Z=120 or Z=126 and N=184 or N=228. Through cold fusion, recently synthesized nuclei with Z=114, 116 and 118 have confirmed the theoretical predictions, providing a possibility of reaching the maximum of these islands of stability. Because of the low production rate and the extremely short half-life of these nuclei, it has not yet been possible to determine their energy spectra. However, it has been theoretically predicted that the nuclei should acquire a spherical form in these islands of stability, thus supplying characteristic vibrational energy spectra. The predictions also indicate the existence of deformed superheavy nuclei in the region between the islands, which can possess rotational energy spectra. In this work, the hydrodynamic equation of energy was corrected by inserting terms referring to coulombian effects, shell closure and nuclear deformation, enabling us to predict the energies of the first excited state for superheavy nuclei of quadrupole deformation, the quadrupole phonon state and an octupole phonon for spherical superheavy nuclei. Four anharmonic vibrational models were then used to describe higher energy states of the nuclei in question. The energy spectra of the (266)104, (268)106, (270)108, (274)110, (278)112, (298)114, (304)120, (348)120, (354)126 nuclei and their closest neighbors were determined.

Utilizou-se o césio-137 para avaliar as taxas de perda ou ganho de solo numa microbacia com diferentes culturas, situada no município de Cambe (PR), a 23º16' Sul e 51º17' Oeste. Foi utilizada uma equação teórica que considera a perda ou ganho de solo num ponto diretamente proporcional à redistribuição de césio-137. Uma amostragem em transectos foi efetuada com o objetivo de avaliar a redistribuição de solo dentro da microbacia. Um ponto em mata nativa na microbacia foi amostrado para estimar a quantidade de césio-137 depositado na região pela precipitação radioativa. Os pontos amostrados em área de pastagem apresentaram, em sua maioria, perda de solo. Os pontos amostrados em área de cafeeiro não apresentaram perda nem ganho de solo. Os pontos amostrados em área de soja, em sistema convencional de preparo de solo, apresentaram perda de solo.

The methodology cesium-137 was used to assess soil erosion and deposition rates in a small watershed with varied crops, at 23º16' S and 51º17' W, in a district of Cambé, Paraná State, Brazil. A theoretical equation which considers soil loss or gain directly proportional to the cesium-137 redistribution was utilized in this study. In the watershed, soil redistribution was assessed by transect sampling, and the regional input of cesium-137 by radioactive rainfall determined based on samples from a point in the native forest. Most sampled pasture points presented soil loss, as well as the points in the soybean area under conventional tillage, while in the coffee crop there was neither soil loss nor gain.