[pt] Para estabelecer com exatidão as curvas em eficiência de detectores a germânio, usam-se radionuclídeos que possuem decaimento complexo, como o 152 Eu e 133 Ba. Porém, por possuírem poucas linhas gama de boa intensidade e irregularmente distribuídas no espectro, esses radionuclídeos não podem ser usados sozinhos. Para superar tais dificuldades, o 166m Ho mostra-se conveniente como padrão único destinado à calibração em eficiência dos espectrômetros a germânio, pois decai por emissão b - , com emissões subseqüentes de 40 linhas gama intensas e bem distribuídas entre 80 e 1500 keV. Além disso, sua longa meia-vida (1200 anos) e raios X característicos entre 40 e 50 keV, o tornam um padrão excelente para calibração de detectores de germânio. É preciso, no entanto, conhecer com exatidão as probabilidades de emissão de fótons de suas principais linhas, uma vez que a literatura tem apresentado estes valores com discrepâncias. Neste trabalho é proposta uma metodologia para determinar, com rigor metrológico, a probabilidade de emissão de suas principais linhas, por meio do uso combinado de espectrometria gama e técnicas de coincidência (4pb-g ). Os resultados experimentais apresentaram-se convergentes em relação aos dados de outros autores, com incertezas menores ou compatíveis. / [en] The efficiency and calibration curves as function of gamma- ray energy for a germanium detector are usually established by using many standard gamma-ray sources of radionuclides decaying with few gamma rays or radionuclides having complex decay scheme, as 152 Eu or 133 Ba. But these radionuclides cannot be used alone, because they have a few gamma lines with high intensity and these lines have a irregular distribution in the energy spectrum. 166m Ho is found to be a convenient single source for such calibration, because it decays by b - with subsequent emission of about 40 strong and well distributed gamma lines between 80 and 1500 keV. Moreover, its long half - life (1200 years) and X-rays characteristics between 40 and 50 keV makes it a good standard for calibration of germanium detectors. However, it is necessary to know with accuracy and precision the gamma ray intensities of their main lines, due to the fact that literature has showed discrepant values. Then, a methodology to determine the emission probability of its main lines is proposed by means of combined use of gamma spectrometry and coincidence 4pb - g techniques. The experimental results show consistence to the others authors, with lower or compatible uncertainties. / [es] Para estabelecer con exactitud las curvas en eficiencia de detectores la germánio, se utilizan radionuclídeos que poseen decaimiento complejo, como el 152 Eu y 133 Ba. Sin embargo, como poseen pocas líneas gama de buena intensidad y irregularmente distribuidas en el espectro, esos radionúcleos no pueden ser usados separadamente. Para superar tales dificuldades, el 166m Ho muestra se conveniente como padrón único destinado a la calibración en eficiencia de los espectrómetros la germánio, pues decae por emisión b , con emisiones subsecuentes de 40 líneas gama intensas y bien distribuidas entre 80 y 1500 keV. Además, su larga media vida (1200 anos) y rayos X característicos entre 40 y 50 keV, el tornan un padrón excelente para calibración de detectores de germanio. Es preciso conocer con exactitud las probabilidades de emisión de fóptons de sus principales líneas, una vez que la literatura ha presentado estos valores con discrepancias. En este trabajo se propone una metodología para determinar, con rigor metrológico, la probabilidad de emisión de sus principales líneas, por medio del uso combinado de espectrometría gama y técnicas de coincidencia (4pb g ). Los resultados experimentales presentaran se convergentes en relación a los datos de otros autores, con incertezas menores o compatibles.

As cargas, dipolos, quadrupolos e multipolos atômicos de maior ordem, bem como suas derivadas, permitem um maior entendimento de diversas propriedades elétricas em sistemas moleculares, como momentos de dipolo, derivadas do momento dipolar, intensidades de infravermelho e potenciais eletrostáticos, além de forças eletrostáticas. Os multipolos aqui estudados foram aqueles advindos da Teoria Quântica de Átomos em Moléculas (QTAIM) e, em certos casos, foram comparados com resultados do formalismo CHELPG (CHarges from Electrostatic Potentials using a Grid based method). As investigações desse projeto foram divididas em duas etapas distintas, sendo que a primeira focou no desempenho dos multipolos atômicos na descrição dos potenciais eletrostáticos quando da interação de uma carga pontual carregada positivamente com uma molécula. Algumas simples moléculas diatômicas (F2, Cl2, BF, AlF, BeO, MgO, LiH e NaCl) e outras mais complexas (H2O, H2CO, NH3, PH3, BF3 e CO2) foram consideradas nesta etapa, sendo que os cálculos foram feitos com B3LYP/6-311G(3d,3p). Já, na segunda etapa, estudou-se o modelo carga - fluxo de carga - fluxo de dipolo (CCFDF, do inglês \"charge - charge flux - dipole flux\") na investigação e interpretação das intensidades fundamentais de infravermelho em modos de vibração molecular. Nessa etapa optou-se pelo estudo de sistemas que apresentavam ligações de hidrogênio, como homodímeros (H2O-H2O, HF-HF, HCl-HCl, HCN-HCN, HNC-HNC e NH3-NH3) e heterodímeros (HF-HCN, HCl-HF e HF-H2O). Os cálculos destes sistemas foram realizados com CCSD/cc-pVQZ-mod. Os resultados sugerem que os multipolos QTAIM são melhores que as cargas CHELPG, na maioria dos casos, para descrição dos potenciais eletrostáticos em sistemas próton - molécula. Por sua vez, o modelo CCFDF/QTAIM consegue reproduzir as intensidades de infravermelho em dímeros que apresentam ligações de hidrogênio. Finalmente, o aumento de intensidade do estiramento X-H do monômero doador, em dímeros lineares, é explicado pela variação da contribuição de fluxo de carga durante a dimerização. / The charges, dipoles, quadrupoles and high order terms, along with their derivatives, allow a better understanding of electric properties. We can cite dipole moments, dipole moment derivatives, infrared intensities, electrostatic potentials and electrostatic forces. The multipoles treated here are obtained from the Quantum Theory of Atoms in molecules (QTAIM) and they are compared with CHELPG (CHarges from Electrostatic Potentials using a Grid based method) results. The investigations of this project can be divided in two distinct parts and the first one focuses in the performance of atomic multipoles in the description of electrostatic potentials when one positive particle interacts with molecules. Some simple diatomic (F2 , Cl2 , BF, AlF, BeO, MgO, LiH and NaCl) and polyatomic molecules (H2O, H2CO, NH3 ,PH3 ,BF3 and CO2) were considered in this investigation and the calculations were carried out at the B3LYP/6-311G(3d,3p) level. The second part of this dissertation was a study of infrared intensities in vibrational modes by means of the charge-charge flux -dipole flux model. The systems treated now are dimers with hydrogen bonds such as homodimers (H2O-H2O, HF-HF, HCl-HCl, HCN-HCN, HNC-HNC and NH3-NH3) and heterodimers (HF-HCN, HCl-HF and HF-H2O). The calculations of these systems were carried out at the CCSD/cc-pVQZ-mod level. The results suggest that QTAIM multipoles are better in describing electrostatic potentials in almost all proton-molecule arrangements than CHELPG charges. The charge-charge flux -dipole flux model can reproduce infrared intensities of dimer with hydrogen bonds. Finally, the increase in intensities of X-H stretching modes associated to the donor monomer in linear dimers is explained by changes in charge flux contributions during dimerization.

This thesis describes the concept of transport solution with the help of microsimulation. Using intensities obtained from the landscape is a simulation of the current status and new proposals. They are compared using a detention time. For the winning option will be implemented spatial study.

No description available.

Yes / This research article analyzed the self-preserving behaviour of wall-wake region of a circular pipe mounted horizontally over a flat rigid sand bed in a shallow flow in terms of mean velocity, RSS, and turbulence intensities. The study aims to investigate self-preservation using appropriate length and velocity scales.in addition to that wall-normal distributions of the third-order correlations along the streamwise direction in the wake region are analyzed. An ADV probe was used to record the three-dimensional instantaneous velocities for four different hydraulic and physical conditions corresponding to four cylinder Reynolds numbers. The results revealed that the streamwise velocity deficits, RSS deficits, and turbulence intensities deficits distributions displayed good collapse on a narrow band when they were non-dimensionalized by their respective maximum deficits. The wall-normal distance was non-dimensionalized by the half velocity profile width for velocity distributions, while the half RSS profile width was used in the case of the RSS deficits and turbulence intensities deficits distributions. The results indicate the self-preserving nature of streamwise velocity, RSS, and turbulence intensities in the wall-wake region of the pipe. The third-order correlations distributions indicate that sweep is the dominant bursting event in the near-bed zone. At the same time, ejection is the dominant bursting event in the region above the cylinder height.

Molecules in the ‘X-C≡N’ chemical family serve as markers for chemical processes happening in various regions of space and are members of the prebiotic molecular pool, which makes them important in astrochemistry and astrobiology. Although these kinds of molecules have been identified in the interstellar medium, cometary comae, plumes of Enceladus, meteorites, and around young stellar objects, it is not clear which mechanisms are responsible for their formation. However, it has been suggested that they may serve as precursors to prebiotically important compounds, such as amino acids and nucleobases. In this work, a theoretical computational study was conducted using quantum mechanical approaches to predict properties of sixteen astrochemically relevant ‘X-C≡N’ molecules. To perform this study, General Atomic and Molecular Electronic Structure System (GAMESS(US)) and AutoGAMESS software were used to calculate optimized geometries, harmonic vibrational frequencies, infrared intensities, and Raman activities of each molecule using density functional theory (BLYP, B3LYP, PBE, and PBE0) and second order Møller-Plesset perturbation theory (MP2, SCS-MP2) paired with several basis sets (6-311++G(d,p), def2QZVPD, Sadlej-pVTZ, and aug-cc-pVQZ). Geometries and frequencies were additionally calculated using coupled cluster approaches (CCSD, CCSD(T), and CCSD(2)T) to help assess accuracy and reliability of the other calculations. For many of these species, experimentally and computationally determined Raman activities have not been reported in the literature. We assess the reliability of our calculations in comparison to previous works and discuss how the implementation of both Raman and infrared spectroscopy can offer new insights into potential reaction mechanisms linking these prebiotically relevant compounds.

<p> Exercise intensity is one of the major factors determining the utilization of carbohydrates (CHO) and lipids in mammalian skeletal muscle. Using indirect calorimetry, we determined maximal oxygen uptake (VO2max) and whole-body rates of CHO and lipid oxidation in rats selectively bred for high and low running capacity (HCR's and LCR's) during exercise at 50, 60, 70 and 80%VO2max. Previous studies have revealed a pattern of selection where mammals with different aerobic capacities use the same proportions of lipids and CHO when exercising at the same relative exercise intensity and as intensity increases, CHO use increases and lipid use decreases. The present results showed that the HCR's had a VO2max and distance run to exhaustion that was 1.3 and 4.0 times greater than the LCR's respectively. Also, both groups of rats followed the pattern of fuel selection seen in previous studies where the same proportions (in%) of lipids and CHO are used at the same relative exercise intensity. On an absolute scale, the HCR's used more lipids and CHO than the LCR's at all exercise intensities but the results were not always statistically significant. We also determined the exercise intensity that elicited the greatest lipid use to be 60% VO2max in both groups.</p> <p> In order to explain these patterns of fuel selection, metabolic indicators, metabolites and enzymes, in skeletal muscle were measured at rest and post exercise for one hour at 60%VO2max. Specifically, ATP and phosphocreatine (PCr) metabolite concentrations were determined in the medial and lateral gastrocnemius, extensor digitorum longus (EDL), tibialis anterior (TA), and soleus muscle. The medial gastrocnemius and soleus were analyzed (pre and post exercise samples were combined) for their oxidative and glycolytic enzyme activity by measuring citrate synthase (CS), cytochrome oxidase (COX), β-hydroxyacyl CoA dehydrogenase (HOAD), and lactate dehydrogenase (LDH) . PCr and ATP concentrations did not change pre and post exercise and between the HCR's and LCR's except for the EDL where there was a significant decrease (P<0.05) in both metabolites after exercise in both groups of rats. For the enzyme measurements, CS and COX activities were higher (P<0.05) in the HCR's for the soleus and HOAD activities were also higher in the HCR's medial gastrocnemius compared to the LCR's. We concluded that the HCR's have a greater oxidative capacity as shown by their greater aerobic and endurance capacity (VO2max and distance to exhaustion), their ability to oxidize a greater absolute amount of lipids and CHO's at the same relative exercise intensity, and their higher activities of oxidative enzymes in the soleus (CS and COX) and medial gastrocnemius (HOAD). Future research into the mechanisms involved in explaining these patterns of fuel selection may include examining fatty acid transport proteins, fatty acid and CHO availability, fiber types, and catecholamines.</p> / Thesis / Master of Science (MSc)

A study has been made of the external conversion spectrum of gamma-rays of less than 200 kev. A set of semi-empirical curves relating the photoelectric peak height to the gamma-ray intensity has been established using antimony radiators. These results will be discussed. A method of preparing thin beta sources will also be described. / Thesis / Master of Science (MSc)

Kombucha is a fermented tea beverage consumed for its probiotics and functional properties and has a unique sensory profile driven by the properties of tea polyphenols and fermentation products, including organic acids. Fermentation temperature and sucrose content affect the fermentation process and the production of organic acids, yet less is known about the impact on the sensory profile and consumer acceptance. Thus, we aim to examine the impact of sucrose concentration and fermentation temperature on sensory attributes and liking. For this study, kombucha tea was fermented at three different concentrations of sucrose and fermented at two temperatures for 11 days. Fermentation was monitored by pH, brix, and titratable acidity, and consumers (n=104) evaluated the kombucha for sensory attributes and overall liking. Fermentation temperature resulted in significant differences in titratable acidity, with higher temperatures producing more organic acids, resulting in higher astringency, and suppressed sweetness. The lower fermentation was reported as significantly more liked, with no difference in liking between the 7.5% and 10% sucrose kombucha samples. Overall, sucrose concentration had less of an impact on overall liking, and the sensory profile and fermentation temperature, which drives the fermentation rate and production of organic acids, strongly influenced the sensory profile.

Over the past thirty years, extensive research has been conducted with the objective of reducing wind damage to structures. Wind tunnel simulations of wind loads have been the major source of building codes. However, a simple comparison of pressure coefficients measured in wind tunnel simulations with full-scale measurements show that the simulations, in general, underpredict extreme negative pressure coefficients. One obvious reason is the lack of consensus on wind tunnel simulation parameters. The wind in the atmospheric surface layer is highly turbulent. In simulating wind loads on structures, one needs to simulate the turbulent character besides satisfying geometric and dynamic similitudes. Some turbulence parameters that have been considered in many simulations include, turbulence intensities, integral length scales, surface roughness, and frequency spectrum. One problem with these parameters is that they are time varying in the atmospheric boundary layer and their averaged value, usually considered in the wind tunnel simulations, cannot be used to simulate pressure peaks. In this work, we show how wavelet analysis and time-scale representation can be used to establish an intermittency factor that characterizes energetic turbulence events in the atmospheric flows. Moreover, we relate these events to the occurrence of extreme negative peak pressures. / Ph. D.