Proposal for a radiation shielding study aiming the implantation of neutrons beam shutter in the J-9 radiation channel of the Argonauta reactor of the Nuclear Engineering Institute.

Argonauta, the only nuclear research reactor situated in Rio de Janeiro, located at the Institute of Nuclear Engineering (IEN), regularly serves a network of users focused on research and development, and also provides its infrastructure for experimental classes and completion work course. Due to increasing demand for non-destructive thermal neutron assays and production of radioisotopes, there is a search for new procedures and/or devices that optimize users' exposure to neutrons. The implementation of mechanisms that allow access to the irradiation channels without the reactor being turned off and with a shielding configuration that limits the occupational doses at this location is very useful for the operation of the reactor. In order to achieve this, the present work proposes the establishment of a neutron beam shutter of the J-9 irradiation channel of the IEN’s Argonauta reactor. In a first step, experimental measurements were made in the irradiation channel of the reactor using a BF3 detector, which is coupled to a spectrometer. In this phase, the neutron beam was aligned to the spectrometer, and different materials were used as shields, aiming the attenuation of the beam. To validate and/or change the configuration of the barrier that best meets the material irradiation needs, a second planned phase is involving the neutron flux simulation of the reactor and the various shields with different boundary conditions using the particle transport code, Monte Carlo N-Particle Extended (MCNP- X)

Cold neutron irradiation facility for the brazilian research reactors

Neutron irradiation in research reactors and accelerators can be realized at appropriated neutron guides or beam holes shared around a cold neutron source (CNS) with neutron of variable intensity and energy. An irradiation facility for multiple applications including an intense CNS was calculated for the three Brazilian research reactors and can be utilized as a first concept for the new research reactor to be designed, the Brazilian multiple purpose research reactor (RMB). A study about coolant and moderators properties, and simulations with neutron physics and thermal codes, may be important for the definition of the type of the CNS to be utilized. Some earlier results of MCNP simulations and a discussion about the different factors involved in the definition of its installation in the Brazilian research reactors are here presented. One suggests an international cooperation for the design development of this system and posterior construction of a prototype in the Argonauta reactor at the Instituto de Engenharia Nuclear (IEN-CNEN-RJ). It is also being considered the inclusion of other devices as a neutron fiber to guide the neutron beams away of the gamma radiation and fast neutron background. The cold neutron facility increases the intensity of cold neutrons, without the need of additional fuel burn up

Fitoterápicos que atuam no sistema digestório: possíveis mecanismos de ação / Phytotherapics that act on the digestive system: possible mechanisms of action

O sistema digestório é responsável pela digestão, fazendo assim a nutrição do corpo afim de colaborar no desenvolvimento e manutenção do organismo, sendo constituído pelo tubo digestivo e órgãos anexos. Todavia, o consumo de alimentos industrializados submetidos ao uso de agrotóxico, o estresse cotidiano e o uso crônico de medicamentos podem prejudicar o funcionamento do sistema digestório. Diante disso, a fitoterapia, ciência milenar baseada pelo uso de plantas medicinais em suas diferentes formas farmacêuticas, pode auxiliar no tratamento, bem como na prevenção de doenças no sistema digestório. Embora o uso medicinal de algumas plantas seja reconhecido, muitos mecanismos de ação ainda não são bem estabelecidos, o que dificulta a difusão dessas informações, bem como a compreensão mais ampla das possíveis contraindicações e interações. Assim, o presente trabalho será uma revisão sobre os mecanismos de ação dos medicamentos fitoterápicos com ação no sistema digestório

Abstracts

Tradução, para a língua inglesa, dos resumos dos artigos publicados nesta edição

Use of Creatine Monohydrate in MDX Mice: Morphometric and Stereological Analysis of the Diaphragm

Duchenne muscular dystrophy is a genetic disease that is clinically manifested by progressive muscle atrophy, followed by loss of strength, motor coordination and functional impairment. In the final stages of the disease, the patient has severe difficulty in breathing mechanics, due to the involvement of the muscles involved with the mechanics of breathing, including the diaphragm. The present study sought to identify the effects of creatine monohydrate supplementation in MDX mice on the morphology, morphometry and stereology of the striated muscle tissue of the diaphragm of these animals. The results indicate that, despite not influencing the increase in cell volume, supplementation acts in an anti-inflammatory way, reducing the progressive process of fibrosis that occurs in these animals in the face of muscle atrophy followed by the replacement of muscle parenchyma by connective tissue. in this way, supplementation provides a better condition for tissue maintenance, enabling more survival of MDX mice. Monohydrate creatine supplementation has been shown to be a complementary therapeutic alternative, especially for muscular dystrophies and severe myopathies

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements