Produção de partículas secundárias em reações de “spallation” induzidas por prótons

Cosmic radiation has been identi ed as one of the main hazard to crew, aircraft and sensitive equipments involved in long-term missions and even high-altitude commercial ights. Generally, shields are used in spatial units to avoid excessive exposure, by holding the incident radiation. Unfortunatelly, shielding in space is problematic, especially when high-energy cosmic particles are considered, due to the production of large number of secondary particles, mainly neutrons, protons and alpha particles, caused by spallation reactions and quasi-elastic processes of the corpuscular radiation with the shield. Good parameters for checking the secondary particle production at target material are diferential cross section and energy deposited in the shield. Addition experiments, some computer codes based on Monte Carlo method show themselves a suitable tool to calculate shield parameters, due to have evaluated nuclear data libraries implemented on the algorithm. In view of this, the aim of this work is determining the parameters evaluated in shielding materials, by using MCNPX code, who shows good agreement with experimental data from literature. Among the materials, Aluminium had lower emission and production of secondary particles

Influência do condicionamento ambiental sobre as propriedades viscoelásticas de compósitos aramida/epóxi

The increasing application of structural composites in the aerospace industry is mainly due to its low specific weight coupled with its excellent mechanical properties when in service. As a result of climatic variations that pass the aircraft is of paramount importance to study the influence of weathering on this type of material when subjected to such changes. The purpose of this work is to evaluate the mechanical behavior of specimens of kevlar fiber /epoxy matrix composites, by dynamic mechanical thermal analysis (DMA) and interlaminar shear strength tests (ILSS), after passing through three environmental conditioning: saline fog, hygrothermal and ultraviolet radiation. From the results, we concluded that the laminate was molded supplied homogeneously, not presenting problems such as porosity, delaminations or cracks inside. After a period of 625 hours of exposure to hygrothermal conditioning, we observed a 1,2% maximum of absorption of moisture. Samples subjected to the conditioning by UV irradiation (600 hours) and salt spray showed a reduction of about 24,30% and 32,30%, respectively, on the shear strength (ILSS). In DMA analysis is not observed significant changes on the glass transition temperature. However, when considering the storage modulus of the samples conditioned by UV radiation (1200 hours), salt spray and hygrothermal conditioning there is an increase of 5,34% , 7,19% and 5,57% respectively

Cálculo estrutural de barreiras: Desenvolvimento de um programa computacional de interface online

This study aimed to develop a computer program which systematizes the structural shielding design calculation in diagnostic radiology facilities. For this purpose methodology of the National Council of Radiation Protection and Measurements (NCRP 147[5]) was used. By comparative statistics studies, it was verified if reference parameters values suggested by the US publication correspond to the average national values. The World Wide Web was chosen because of its characteristics as a powerful mean of communication, especially in terms of the wide variety of useful resources and easy access. To compare the reference values of some parameters proposed by NCRP 147 to Brazilian average, studies about the normalized workload per patient, performance of X-ray tube and primary air kerma, unshielded, at one meter from the focal point of the X-ray tube were made. Through this research, relative differences were found. In workload values this differences reached up to 50% in mammography compared to those presented by the NCRP 147; in X-ray tube performance the percentage differences reached 69% in dental radiology, and air kerma results amounted 31% in fluoroscopy. This demonstrates the importance of validation of international protocols to local realities

Análise dosimétrica de aplicadores de Betaterapia

Betatherapy is a special medical technique using a radioactive source of strontium-90 for the treatment of superficial lesions, especially in dermatology and ophthalmology. Strontium-90 sources emit β radiation, which possesses high ionization power, but a very short distance propagation into matter. This work presents a method of dosimetric analysis of betatherapy using strontium- 90-based instrumentation, commonly used against superficial diseases, such as keloid and pterygium, aiming the description of the dosimetry analysis procedures, which can be easily implemented on tradiotherapy services that offers the betatherapy treatment. IBF-MEDIX radiographic films (conventional films) were exposed to betatherapy applicators during different time intervals according to the activity of the source, and afterwards the optical densities (O. D.) of the radiographic images were measured using an optical densitometer MACBETH. Therefore, the parameters used to make the dosimetric analysis in betatherapy were standardized, as the exposure time depended on the geometry and size of the source, providing an efficient and fast method of dosimetric analysis of the betatherapy equipment of the services, the majority of which do not have the scientific structure to perform this study

Análise da atividade de peroxidases e polifenoloxidases em diferentes órgãos vegetativos de espécies arbóreas nativas de diferentes grupos sucessionais

As formações vegetais são altamente dinâmicas e dependem principalmente da taxa de crescimento das espécies vegetais, entretanto, esta está intimamente relacionada e suscetível a estresses abióticos, como elevada ou baixa radiação solar, temperaturas extremas, e bióticos, como taque de patógenos e de herbívoros, o que faz com que as plantas necessitem de um sistema de defesa altamente eficiente o qual consiste na atuação de compostos secundários, e de enzimas como por exemplo peroxidases e polifenoloxidases. A atividade das peroxidases constitui a mais importante via do sistema de defesa vegetal a patógenos no que se refere a cicatrização de ferimentos e à herbivoria, propiciando um aumento da lignificação nos tecidos lesados, o que aumenta a resistência dos mesmos, dificultando assim a ocorrência de novas lesões. Quanto às polifenoloxidases, também pertencentes ao grupo das oxidorredutases, são enzimas que também atuam diretamente na via de defesa das plantas ao ataque de patógenos e na cicatrização de ferimentos e processos de senescência. Por meio da extração e análise da atividade de Peroxidases e Polifenoloxidases em porção de raiz, caule, ápice e em folhas de indivíduos de Erythrina speciosa Andrews, Eugenia uniflora L., Hevea brasiliensis M. Arg., Hymenaea courbaril L. var. stilbocarpa (Hayne) Lee et Lang, Joannesia princeps Vell., Licania tomentosa (Benth.) Fritsch, Pachira aquatica Aubl. e Psidium guajava L., obteve-se comportamento pioneiro para as espécies Eugenia uniflora L., Hymenaea courbaril L. var. stilbocarpa (Hayne) Lee et Lang, Joannesia princeps Vell. e Psidium guajava L., e comportamento não-pioneiro para as espécies Erythrina speciosa Andrews, Hevea brasiliensis M. Arg., Licania tomentosa (Benth.) Fritsch e Pachira aquatica Aubl.. Dessa maneira foi possível verificar que a análise da atividade peroxidásica... (Resumo completo, clicar acesso eletrônico abaixo)

Estudo da deposição de energia das radiofrequências através do método das diferenças finitas dependentes do tempo Monografia

Radiotherapy in veterinary practice is already known and widely distributed in large specialized centers of developed countries. In early 2000, there were about 30 radiotherapy equipment specifically designed for the veterinary clinic in the United States. In Brazil, the veterinary radiotherapy is still confined to research in universities, where most of the procedures is radiation therapy performed with superficial x-ray machines, with a voltage between 50 and 150 kVp, focus-distance surface (DFS) between 20,0cm and 40,0cm. As that occurs in human medicine, new research strengthens the development and prospects for the use of radiotherapy as a safe option for treating cancer in animals. This paper presents a methodology for calculating the exposure time for superficial radiotherapy procedures in veterinary medicine for small animals (dogs and cats). The dosimetric parameters of X-rays are determined using a spreadsheet tool for Microsoft Office Excel, developed in this paper for a device Dermopan 2, Veterinary Hospital of UNESP in Araçatuba. Using the worksheet helps the veterinarian to determine the time of exposure to radiation determined for each clinical case, optimize the workflow for professionals in veterinary radiotherapy procedures, which often lack the medical physics in team and at the time of radiotherapy. The correct use of spreadsheet decreases the chances of errors in dose rates of radiation, providing a higher quality of care

Métodos de Calibração e Dosimetria de Aplicadores de Betaterapia

The sources of betatherapy for clinical use in Brazil are, the vast majority of strontium-90, radioactive element that is not produced in the country, and therefore requires importation of international laboratories accredited by the International Atomic Energy Agency (IAEA).The use of these resources is always limited the crediting of characteristic values supplied by the manufacturer tables that provide the nominal value of activity and dose distribution to determine the irradiation time of the injury. The Institute of Nuclear Energy Research (IPEN / CNEN-SP) has recently researching the emission profile of these types of radiation sources, and some jobs are being developed with ionization chambers extrapolation for the purpose of standardizing a systematic calibration sources betatherapy. Other studies using parallel measures dosimeters (TLD's) and simulations with the Monte Carlo method. Radiological films have also been used in studies of applicators dosimetric analysis of strontium-90. This paper seeks to analyze the different methods for calibration of applicators betatherapy, already consolidated in studies by examining the advantages and disadvantages of each procedure

Aplicações práticas de proteção radiológica nas áreas de medicina nuclear e radiodiagnóstico em instalações hospitalares

After the discovery of ionizing radiation, its applications in various fields of science began to take significant proportions. In the case of medicine, there are the application areas in radiotherapy, diagnostic radiology and nuclear medicine. It was then necessary to create the field of radiological protection to establish the conditions necessary for the safe use of such ionizing radiation. Apply knowledge obtained during the graduation stage and in the practice of radiological protection in the areas of nuclear medicine and diagnostic radiology. In the area of nuclear medicine, tests were made in the Geiger-Muller counters (GM) and the dose calibrator (curiometer), the monitoring tests of radiation, waste management, clean of the Therapeutic room and testing the quality control of gamma-chambers. In the area of radiology, were performed tests of quality control equipment for conventional X-ray equipment and x-ray fluoroscopy, all following the rules of the National Health Surveillance Agency (ANVISA), and reporting of tests. The routine developed in the fields of nuclear medicine in hospitals has proved very useful, since the quality control of GM counters contribute to the values of possible contamination are more reliable. The control of dose calibrator enables the patient not to receive different doses of the recommended amounts, which prevents the repetition of tests and unnecessary exposure to radiation. The management of waste following the rules and laws established and required for its management. Tests for quality control of gamma chambers help to evaluate its medical performance through image. In part of diagnostic radiology, tests for quality control are performed in order to verify that the equipment is acceptable for usage or if repairs are needed. The knowledge acquired at the internship consolidated the learning of graduation course

Classificação do grupo sucessional de espécies nativas por análise do processo de estiolamento de plântulas

As plantas apresentam moléculas que detectam a luz, entre elas estão os fitocromos que detectam mudanças na qualidade da luz nas regiões de vermelho (V) e vermelho-extremo (VE). O fitocromo age no crescimento das plantas possibilitando-as perceber o sombreamento por outras plantas, o que pode ocasionar no processo de estiolamento, ou seja, alongamento do caule. Assim, conforme aumenta o sombreamento, a razão V:VE diminui. Nas plantas de sol, quanto maior a proporção de VE, maior a taxa de estiolamento, enquanto que as plantas de sombra mostram pouca ou nenhuma redução na taxa de alongamento dos caules. Na sucessão florestal as plantas podem ser classificadas como pioneiras, sendo aquelas dependentes de luz e intolerantes à sombra, e as de transição ou clímax, que são tolerantes à sombra. Assim, este trabalho teve o intuito de analisar o processo de estiolamento de plântulas de espécies arbóreas nativas selecionadas, mantidas em condições de luz diferentes e correlacionar com a classe seral correspondente citada na literatura. As seguintes espécies foram analisadas: Bixa orellana, Caesalpinia peltophoroides, Dalbergia nigra, Erythrina speciosa, Eugenia uniflora, Hevea brasiliensis, Hymenaea courbaril, Licania tomentosa, Pachira aquatica, Piptadenia gonoacantha, Psidium guajava, Schizolobium parahyba. Todos os experimentos foram desenvolvidos no jardim experimental da UNESP de Rio Claro. As espécies foram expostas a seis condições luminosas diferentes, com razão V:VE de: 0,1; 0,19; 0,21; 0,35; 1,15 e 1,17. E radiação solar incidente de: 3,16UM; 44,78UM; 27,7UM; 73,54UM; 1987,00UM; 1453,00UM. Foram tiradas medidas do comprimento dos hipocótilos e epicótilos. Posteriormente foram realizadas análises estatísticas com nível de significância de 5%. As espécies consideradas pioneiras foram D. nigra e S. parahyba. E as espécies classificadas como não pioneiras foram:... (Resumo completo, clicar acesso eletrônico abaixo)

Análise filogenética comportamental: o caso dos mustelídeos

Pós-graduação em Biociências - FCLAS

Avaliação da atividade antioxidante, fotoprotetora e antiglicação dos extratos de folhas e frutos de espécies da família Annonaceae

Pós-graduação em Biociências - FCLAS

Retrospecto de lesões radiológicas da cabeça de cães e gatos

Pós-graduação em Cirurgia Veterinária - FCAV

Integridade dos dados meteorológicos obtidos por duas estações meteorológicas automatizadas

Pós-graduação em Agronomia (Ciência do Solo) - FCAV

O assoalhamento em Bokermannohyla alvarengai (Anura, Hylidae): história natural e adaptações morfo-fisiológicas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

O modelo atômico de Bohr e as abordagens para seu ensino na escola média

The teaching of modern and contemporary Physics subjects in high school is indispensable and it was already justified by several researchers. Among the subjects which must be taught, there is, for instance, Bohr atomics model. However, as it was noticed in literature review, many didactic materials do not deal with this model adequately, since that they do not take into account Bohr ideas, which involved Planck studies on black-body radiation, Einsten theory for photoelectric effect, Rutherford experiences and atomics model and the empiric results upon the spectrums of chemical elements emission. From that, it is extremely important teaching through approaches which potentialize the learning of the model proposed by Niels Bohr. On the other hand, teachers from high schools cannot have clearness about which approaches can be applied for teaching the mentioned model. Thus, it is presented some possibilities for teaching Bohr atomics model, with examples and justifications for the use of each one. Special treatment was attributed to the teaching from Science History and Philosophy, from the reading of scientific diffusion and original scientific texts, from analogies, from comic strips and from computer simulations.