The role of the oblique ligament in the mechanical behavior of the medial collateral ligament of the mongrel dog elbow joint - Some biomechanical aspects

This study investigated the oblique ligament mechanical contribution to the medial collateral ligament of the canine elbow joint. Fifteen dogs were used for the study of the failure load, displacement, and energy absorption of the medial collateral and oblique ligaments of the canine elbow joint, associate and separately in the joint. Medial collateral ligament failure load and energy absorption were significantly higher in relation to the isolated oblique ligament. When the ligaments were associated in the joint, they presented an increment in failure load, displacement and energy absorption in relation to the ligaments analyzed separately. It was concluded, therefore, that the oblique ligament could have an important paper in the stability of the canine elbow joint, as it favors the medial collateral ligament resistance to the tensile load, one of the main stabilizer of the elbow joint.

The force, power, and energy of the 100 meter sprint

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

Efeito da administração de alendronato, a longo prazo, sobre as propriedades mecânicas do tecido ósseo, sua reparação e mineralização ao redor de implantes osseointegráveis. Estudo em ratas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise estrutural de tubos de concreto armado com resíduo de borracha de pneu

Pós-graduação em Engenharia Civil - FEIS

Protocolo para sinterização de zircônia odontológica por energia de micro-ondas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Decrease in circulating glucose, insulin and leptin levels and improvement in insulin resistance at 1 and 3 months after gastric bypass

Background: Hyperglycemia, insulin resistance and hyperleptinemia are some of the consequences of obesity. Gastric bypass for morbid obesity provides gastric restriction with decreased energy absorption. To confirm and extend previous reports in the literature, We evaluated the plasma glucose, serum insulin and leptin and insulin resistance of patients preoperatively and 1 and 3 months after Roux-en-Y gastric bypass (RYGBP).Methods: We determined body mass index (BMI), plasma glucose (glucose-oxidase method), serum leptin (immunoassay) and insulin (chemiluminescent immunometric assay), and insulin resistance index (IRI) by Homeostasis Model Assessment (HOMA) of 20 patients with morbid obesity both preoperatively and 1 and 3 months after RYGBP.Results: Patients showed a mean decrease in weight of 8 kg/month. Glycemia was above reference levels in 65% of the preoperative patients but dropped significantly 1 month postoperatively, serum insulin and leptin levels and the HOMA index also decreasing significantly in the same period. The percentage of patients with preoperative elevated serum insulin and leptin relative to reference levels decreased significantly following RYGBP. We also observed a weak but significant correlation between BMI and glucose, BMI and insulin, and leptin and insulin.Conclusions: the beneficial effects of bariatric surgery are already noticeable 1 month postoperatively, the reduction in insulin levels being more important for leptin reduction than decreased BMI. Leptin appeared to be subject to multifactorial control and showed a larger reduction than body weight.

A influência do discurso do professor na motivação e na interação social em sala de aula

Estudos têm mostrado a importância das interações sociais desencadeadas em sala de aula como fundamentais para a aprendizagem dos alunos. Contudo, o professor deve ser capaz de motivar os estudantes para se envolverem mais ativamente com as atividades de ensino propostas. Este artigo apresenta os resultados de uma investigação sobre as interações sociais desenvolvidas no contexto de uma sala de aula do Ensino Médio, que explicou os princípios da conservação da energia mecânica com uma aula experimental de demonstração. O principal objetivo era entender como o discurso do professor pode contribuir para o bom nível de motivação do aluno durante uma aula. As entrevistas com professor e alunos e todo o processo de interação durante as atividades foram gravados, transcritos e analisados . Os resultados ressaltam a importância da abordagem discursiva dos professores para manter o processo de motivação entre os alunos.

Mechanochemical synthesis of ceramic powders with perovskite structure

The mechanical activation is one of the most effective method for obtaining highly disperse system due to mechanical action stress fields form in solids during milling procedure. This effect results in changes of free energy, leading to release of heat, formation of a new surface, formation of different crystal lattice defects and initiation of solid-state chemical reaction. The accumulated deformation energy determines irreversible changes of crystal structure and consequently microstructure resulting in the change of their properties. Mechanochemical processing route has been developed recently for the production of intermetallic and alloy compounds. The intrinsic advantage of this process is that the solid-state reaction is activated due to mechanical energy instead of the temperature. It was shown that the chemical reactivity of starting materials could be improved significantly after mechanochemical activation and, subsequently, the calcination temperature was reduced. Besides, it was apparent that the mechanochemical treatment could enhance the reactivity of constituent oxides; however, the sintering process could not be avoided to develop the desired ceramics. A novel mechanochemical technique for synthesis of fine-grained perovskite structured powders has shown that it is possible to form perovskite at room temperature. The effect of milling on the formation of perovskite structure of barium titanate (BT), lead titanate (PT), PZT, PZN, magnesium niobate (PMN) and LM ceramic materials was analyzed. The dielectric properties of sintered ceramics are comparable with those prepared by other methods in the literature. (C) 2003 Elsevier B.V. B.V. All rights reserved.

Structure, mobility and clustering of interstitial O in La2CuO4+delta in the limit of small delta

Anelastic spectra (elastic energy absorption as a function of temperature) are reported which provide evidence that excess O in La2CuO4+delta starts forming two different types of defects already at very low concentrations, where no phase separation or changes in the type of O intercalation are believed to occur. The absorption peak with the lowest activation enthalpy, H/k(B) = 5600 K, is visible at lowest values of delta and is attributed to the hopping of single interstitial O2- ions. The second process, with a slightly slower dynamics, appears at higher values of delta and soon becomes preponderant over the former process. The latter process is proposed to be due to stable pairs of O atoms and is put in connection with the formation of partially covalent bonds between interstitial and apical oxygen; such bonds would reduce the doping efficiency of excess O at increasing delta. The geometry of the interstitial O defect is discussed. O 1998 Published by Elsevier B.V. B.V. All rights reserved.

Thermally activated dynamics of the tilts of the CuO6 octahedra, hopping of interstitial O, and possible instability towards the LTT phase in La2CuO4+δ

The anelastic spectrum (dynamic Young's modulus and elastic energy absorption) of La2CuO4+δ has been measured between 1 and 700 K with 0<δ<0.02. The spectrum of stoichiometric La2CuO4 in the low-temperature orthorhombic (LTO) phase is dominated by two intense relaxation processes which cause softenings of 16% around 150 K and 9% below 30 K at f∼1 kHz. The relaxation at 150 K is attributed to the presence of a fraction of the CuO6 octahedra which are able to change their tilted configuration by thermal activation between orientations which are nearly energetically equivalent, possibly within the twin boundaries. The relaxation below 30 K is governed by tunneling, and involves a considerable fraction of the lattice atoms. It is proposed that the double-well potentials for the low-temperature relaxation are created by the tendency of the LTO phase to form low-temperature tetragonal (LTT) domains, which however are not stabilized like when La is partially substituted with Ba. On doping with excess O, the relaxation rates of these processes are initially enhanced by hole doping, while their intensities are depressed by lattice disorder; an explanation of this behavior is provided. Excess O also causes two additional relaxation processes. The one appearing at lower values of δ is attributed to the hopping of single interstitial O2- ions, with a hopping rate equal to τ-1=2×10-14exp(-5600/T) s. The second process is slower and can be due to O pairs or other complexes containing excess O.

Dielectric and ferroelectric properties of PZT and PT thin films for saw sensors applications

It is very important for the building of the SAW devices to study dielectric and ferroelectrics properties because every SAW device is based in piezoelectric effect that it is made up to transform an electric sign in the mechanical or acoustic sign and a mechanical or acoustic sign in an electric sign. Thus, the purpose of the present work is to prepare PbZr 0,53Ti0.47O3 (PZT) and PbTiO3 (PT) thin films on the Si (100) substrates across spin-coating using a chemical method based in polymeric precursors. After conventional treatment in the furnace, the films were characterized by impedance spectroscopy and hysteresis loops to know its dielectric and ferroelectric properties.

Study of cutting forces on machinability properties of gray cast iron using new ceramics cutting tools

During gray cast iron cutting, the great rate of mechanical energy from cutting forces is converted into heat. Considerable heat is generated, principally in three areas: the shear zone, rake face and at the clearance side of the cutting edge. Excessive heat will cause undesirable high temperature in the tool which leads to softening of the tool and its accelerated wear and breakage. Nowadays the advanced ceramics are widely used in cutting tools. In this paper a composition special of Si3N4 was sintering, characterized, cut and ground to make SNGN120408 and applyed in machining gray cast iron with hardness equal 205 HB in dry cutting conditions by using digital controlled computer lathe. The tool performance was analysed in function of cutting forces, flank wear, temperature and roughness. Therefore metal removing process is carried out for three different cutting speeds (300 m/min, 600 m/min, and 800 m/min), while a cutting depth of 1 mm and a feed rate of 0.33 mm/rev are kept constant. As a result of the experiments, the lowest main cutting force, which depends on cutting speed, is obtained as 264 N at 600 m/min while the highest main cutting force is recorded as 294 N at 300 m/min.

Caracterização Tecnológica das Rochas Ornamentais do Maciço Capão Bonito, SP

The Capão Bonito Granitic Massif is situated in the south portion of the São Paulo State and represents an elongate body with general direction NE-SW, intrusive in epimetamorphic rocks of Açungui Group (Votuverava Formation), and in granitic rocks of the Três Córregos Complex. It is partially covered by sedimentary rocks of the Paraná Basin (Itararé Group). As the chief type we have red sienogranite, holo to leucocratic with biotite and rare hornblende, inequigranular with medium to coarse grains to porphiritic and isotropic to slightly cataclastic textures of marginal zones. This granite was analyzed for petrographics (composition, structure and texture), chemical composition (major elements), physical and mechanical (water absorption, resistance to abrasion, impact of hard body and efforts of compression and traction) and chemical attack aspects. The results were compared to suggested values for granitic rocks used for ornamental purposes. The whole massif shows compositional, textural, structural (related to isotropy) and chemical (major elements) characteristics very homogeneous. The varieties of sienogranite named commercially as Capão Bonito or Rubi Red Granite showed results very similar to each other, with some variations in the physical and mechanical resistance resulting of the penetrative brittle deformation of regional occurrence, evidenced by differences in the microfissural index.

Signal classification of submerged aquatic vegetation based on the hemispherical-conical reflectance factor spectrum shape in the yellow and red regions

The water column overlying the submerged aquatic vegetation (SAV) canopy presents difficulties when using remote sensing images for mapping such vegetation. Inherent and apparent water optical properties and its optically active components, which are commonly present in natural waters, in addition to the water column height over the canopy, and plant characteristics are some of the factors that affect the signal from SAV mainly due to its strong energy absorption in the near-infrared. By considering these interferences, a hypothesis was developed that the vegetation signal is better conserved and less absorbed by the water column in certain intervals of the visible region of the spectrum; as a consequence, it is possible to distinguish the SAV signal. To distinguish the signal from SAV, two types of classification approaches were selected. Both of these methods consider the hemispherical-conical reflectance factor (HCRF) spectrum shape, although one type was supervised and the other one was not. The first method adopts cluster analysis and uses the parameters of the band (absorption, asymmetry, height and width) obtained by continuum removal as the input of the classification. The spectral angle mapper (SAM) was adopted as the supervised classification approach. Both approaches tested different wavelength intervals in the visible and near-infrared spectra. It was demonstrated that the 585 to 685-nm interval, corresponding to the green, yellow and red wavelength bands, offered the best results in both classification approaches. However, SAM classification showed better results relative to cluster analysis and correctly separated all spectral curves with or without SAV. Based on this research, it can be concluded that it is possible to discriminate areas with and without SAV using remote sensing. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

Hydrogen production by biogas steam reforming: A technical, economic and ecological analysis

Fuel cells are electrochemical energy conversion devices that convert fuel and oxidant electrochemically into electrical energy, water and heat. Compared to traditional electricity generation technologies that use combustion processes to convert fuel into heat, and then into mechanical energy, fuel cells convert the hydrogen and oxygen chemical energy into electrical energy, without intermediate conversion processes, and with higher efficiency. In order to make the fuel cells an achievable and useful technology, it is firstly necessary to develop an economic and efficient way for hydrogen production. Molecular hydrogen is always found combined with other chemical compounds in nature, so it must be isolated. In this paper, the technical, economical and ecological aspects of hydrogen production by biogas steam reforming are presented. The economic feasibility calculation was performed to evaluate how interesting the process is by analyzing the investment, operation and maintenance costs of the biogas steam reformer and the hydrogen production cost achieved the value of 0.27 US$/kWh with a payback period of 8 years. An ecological efficiency of 94.95%, which is a good ecological value, was obtained. The results obtained by these analyses showed that this type of hydrogen production is an environmentally attractive route. © 2013 Elsevier Ltd.