Linear Attenuation Coefficient
Mostrando 1-11 de 11 artigos, teses e dissertações.
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1. Evaluation of a Metal-Organic Composite (Tungsten-Lignin) for Attenuation of Gamma Radiation
The objective of this work was to use tungsten and lignin as precursors to obtain a metal-organic composite tungsten-lignin (W-Lig) using different sintering temperatures. Tungsten is a refractory metal and it was selected for the composite since it is widely used for high-energy radiation shielding as it has an excellent absorption cross section for thermal
Mat. Res.. Publicado em: 02/09/2019
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2. Elemental concentration via portable x-ray fluorescence spectrometry: Assessing the impact of water content
RESUMO A fluorescência de raios-X portátil (pXRF) pode ser considerada como um dos principais avanços para a caracterização química de diferentes materiais. A umidade das amostras pode afetar o desempenho dessa análise. Assim, foi realizado um ensaio para verificar o efeito da umidade na concentração elementar obtida via pXRF. Como inovação, objet
Ciênc. agrotec.. Publicado em: 27/05/2019
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3. Partitioning of the diffuse attenuation coefficient for photosynthetically available irradiance in a deep dendritic tropical lake
ABSTRACT We studied the effects of particulate and dissolved optically active components on the attenuation of photosynthetic active radiation (PAR) in a tropical lake. The temporal and spatial distribution of tripton, Chl-a and aCDOM(440) and their relative contribution to the diffuse PAR attenuation coefficient (Kd) was investigated at 21 sites (dry and we
An. Acad. Bras. Ciênc.. Publicado em: 2017-05
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4. Heterogeneity correction in the construction of optimized planning in radiotherapy using linear programming
A radiotherapy planning is considered optimal when all the parameters involved, physical or biological, have been investigated and appropriate for each patient. In this type of planning, the major concern is with the tumor irradiation with the minimum possible damage to healthy tissues of the irradiated region, especially the organs at risk. The optimal plan
Pesquisa Operacional. Publicado em: 2011-12
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5. Estudo semianalítico da qualidade de imagem e dose em mamografia / Semianalytical study of image quality and dose in mamography
Neste trabalho, foram desenvolvidos modelos semianalíticos para estudar os parâmetros de qualidade da imagem (contraste objeto, SC, e razão contraste-ruído, CNR) e a dose glandular normalizada (DgN ) em mamografia convencional e digital. As características de 161 amostras de tecidos mamários (coeficiente de atenuação linear e densidade) e os espectro
Publicado em: 2011
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6. Desenvolvimento de procedimentos analíticos limpos e com alta sensibilidade para a determinação de espécies de interesse ambiental / Development of clean analytical procedures with high sensitivity for determination of species of environmental interest
Clean analytical procedures with high sensitivity for the determination of species of environmental interest (carbaryl, sulphate and chlorine) were developed. Flow systems with solenoid micropumps were coupled to long optical pathlength spectrophotometry or cloud point extraction procedures, aiming the concentration of species for determination without emplo
Publicado em: 2009
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7. Assessment of proximal caries lesions through microtomography, cone beam CT and digital radiographs / Avaliação de cáries proximais por meio da microtomografia, tomografia Cone Beam e radiografias digitais
Dental caries is still a great challenge to dentists, manly in proximal surfaces due to its difficult diagnosis. Many types of equipment have been designed to minimize this problem, specially aiming early caries detection. Among all, one of the most used by clinicians is the interproximal radiograph. The International Caries Assessment System (ICDAS) is a cl
Publicado em: 2009
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8. Analysis of concrete material through gamma ray computerized tomography
Computerized Tomography (CT) refers to the cross sectional imaging of an object from both transmission or reflection data collected by illuminating the object from many different directions. The most important contribution of CT is to greatly improve abilities to distinguish regions with different gamma ray transmittance and to separate over-lying structures
Brazilian Journal of Physics. Publicado em: 2004-09
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9. Analysis of the efficiency from visible-light sources used to polimerize odontological resins. / Estudo da eficiência de aparelhos para fotopolimerizar resinas odontológicas.
In this work, five photopolymerizators was characterized, Visilux 2, Resilux, Fibralux, Translux III and Primelite. Initially the emission specter from five light sources was obtained with a monochromator, and to these specters was adjusted gaussians functions. The better adjustments was obtained with a sum of gaussian functions, originating a caracteristic
Publicado em: 1993
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10. Minitomografo de raio-X e raio-gama computadorizado para aplicações multidisciplinares
The main result of this thesis is the development, implementation and use of an X-ray and y-ray computerized minitomography scanner with possible applications in multidisciplinary fields particularly in soil physics. The hardware is basically a mechanical table with two step motors, one for rotation and another for translation motions, radioactive,source, co
Publicado em: 1987
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11. Radiological Studies Reveal Radial Differences in the Architecture of the Polysaccharide Capsule of Cryptococcus neoformans
The polysaccharide capsule of the pathogenic fungus Cryptococcus neoformans is an important virulence factor, but relatively little is known about its architecture. We applied a combination of radiological, chemical, and serological methods to investigate the structure of this polysaccharide capsule. Exposure of C. neoformans cells to gamma radiation, dimeth
American Society for Microbiology.