Morphological and biomechanical study of abdominal aorta of rats submitted to experimental chronic alcoholism

OBJETIVO: avaliar a influência do alcoolismo crônico experimental na morfologia e biomecânica da artéria aorta de ratos. MÉTODOS:ratos Wistar foram divididos em dois grupos de 22 animais. Grupo alcoolista: os ratos receberam água com concentração crescente de etanol e ração ad libitum durante 6 meses. Grupo controle: os animais receberam água e ração ad libitum pelo mesmo período. Os animais foram sacrificados com overdose de pentobarbital e as aortas abdominais foram excisadas para realização de histologia (hematoxilina-eosina, tricrômio de Masson, Calleja, Picrosirius red), histomorfometria e avaliação biomecânica (carga máxima, alongamento na carga máxima, limite de proporcionalidade, alongamento no limite de proporcionalidade e coeficiente de rigidez). RESULTADOS: A histologia e a histomorfometria não mostraram diferenças significantes na morfologia da aorta em ambos os grupos. A avaliação biomecânica mostrou aumento do alongamento no limite de proporcionalidade no grupo alcoolista (p<0.05). CONCLUSÃO: o alcoolismo crônico experimental não provocou alterações morfológicas na parede da aorta, mas causou aumento da sua elasticidade, sem modificar as outras propriedades mecânicas avaliadas.

Qualidade físico-química e sensorial da carne de peito de matrizes pesadas de descarte

O objetivo do presente trabalho foi avaliar as características de qualidade: pH, cor, valor R, perda por exsudação, capacidade de retenção e absorção de água, capacidade de emulsificação, perdas por cocção, força de cisalhamento e análise sensorial da carne de matrizes pesadas de descarte de frangos de corte. A carne de peito de matrizes apresentou valores médios do parâmetro pH, valor R, perda por exsudação e valor de L* de 5,70, 1,43, 2,00 e 50,11, respectivamente. Para a capacidade de retenção e absorção de água, perda de peso por cozimento e força de cisalhamento, os valores médios foram de 77, 58, 18% e 4,94kgf cm-2, respectivamente. Na análise sensorial, a carne de matriz apresentou baixa intensidade de maciez (6,9) e menor suculência (3,4) e foi a mais elástica, borrachenta e difícil de deglutir. A carne de matrizes pesadas de descarte apresenta boas características de qualidade tecnológicas que possibilitam sua utilização como matéria-prima para a elaboração de industrializados.

Avaliação de painéis produzidos a partir de resíduos sólidos para aplicação na arquitetura

O presente trabalho tem por objetivo o reaproveitamento de resíduos sólidos na preparação de painéis para uso na arquitetura. Para atingir as metas propostas, painéis foram preparados a partir de resíduos provenientes de embalagens cartonadas e plásticas, utilizando-se como elemento de reforço, resíduos lignocelulósicos (casca de amendoim e de arroz). A concentração e a natureza dos resíduos utilizados como matriz e como carga foram variadas gerando doze condições experimentais diferentes. As propriedades avaliadas dos painéis foram o módulo de ruptura, módulo de elasticidade, tração perpendicular à superfície, inchamento em espessura, absorção de água e densidade. Todos os ensaios foram realizados segundo as normas ASTM D1037 e EN 317, referente à chapa de partículas. Os resultados foram analisados segundo a norma ANSI A208.1 que especifica as propriedades de desempenho requeridas para as chapas de partículas. Os painéis foram classificados como de baixa densidade, podendo ser utilizados como forros, divisórias, revestimento decorativos e demais aplicações que requerem as mesmas propriedades físicas e mecânicas. Os painéis a base de embalagem plástica reforçados com casca de arroz apresentaram propriedades superiores do que os demais painéis produzidos. O elemento arquitetônico desenvolvido neste estudo representa um novo mercado potencial, podendo ser empregado no ambiente urbano e rural, atendendo ao conceito de produto ecoeficiente.

Propriedades mecânicas de três fios de sutura no reparo do tendão do músculo flexor profundo do dedo de cães

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

Study of stress distribution with finite element method in a root with prefabricated threaded split shaft post - Part I

A finite element analysis was carried out to study the role of prefabricated threaded split shaft post (Flexi-Post) on dentinal stress in pulpless tooth. Three dimensional plane strain model of mesio-distal section of a human maxillary central incisor without restoration was analysed with the MSC/NASTRAN (MacNeal/ Schwendler) general purpose finite analysis program was executed on a microcomputer. The model as discretized into 48.954 axisymmetric finite elements defined by 10.355 nodes. Each element was assigned unique elastic properties to represent the materials modeled. Homogeneity, isotropy and linear elasticity were assume for all material. A simulation of static load of 100N was applied to the incisal edge of the post; vertical. Maximal principal stresses and von Mises equivalent stress were calculated. Using the element analysis model employed in this study, the following can be concluded concerning threaded split shaft post (Flexi-Post): Maximum principal stresses in dentin were located at cervical place and at the post apex. The apical threads of the post not redirecting stresses away from the root.

The influence of the thickness on the functional properties of cassava starch edible films

The properties of edible films are influenced by several factors, including thickness. The purpose of this paper was to study the influence of thickness on the viscoelasticity properties, water vapor permeability, color and opacity of cassava starch edible films. These films were prepared by a casting technique, the film-forming solutions were 1, 2, 3 and 4% (w/v) of starch, heated to 70degreesC. Different thicknesses were obtained by putting 15 to 70 g of each solution on plexiglass plates. After drying at 30degreesC and ambient relative humidity, these samples were placed for 6 days at RH of 75%, at 22degreesC. The sample thicknesses were determined by a digital micrometer (+/-0.001 mm), as the average of nine different points. The viscoelasticity properties were determined by stress relaxation tests with a texture analyser TA.XT2i (SMS), being applied the Burgers model of four parameters. The water vapor permeability was determined with a gravimetric method, and color and opacity were determined using a Miniscan XE colorimeter, operated according to the Hunterlab method. All the tests were carried out in duplicate at 22degreesC. Practically, the four visco-elasticity properties calculated by the Burgers model had the same behavior, increasing with the thickness of all films, according to a power law model. The water vapor permeability and the color difference increased linearly with the thickness (0.013-0.144 mm) of all films prepared with solution of 1 to 4% of starch. on the other hand, the effect of the variation of the thickness over the opacity, was more important in the films with 1 and 2% of starch. It can be concluded that the control of the thickness in the elaboration of starch films by the casting technique is of extreme importance.

Fabrication of phytic acid sensor based on mixed phytase-lipid Langmuir-Blodgett films

This paper reports the surface activity of phytase at the air-water interface, its interaction with lipid monolayers, and the construction of a new phytic acid biosensor on the basis of the Langmuir-Blodgett (LB) technique. Phytase was inserted in the subphase solution of dipalmitoylphosphatidylglycerol (DPPG) Langmuir monolayers, and its incorporation to the air-water interface was monitored with surface pressure measurements. Phytase was able to incorporate into DPPG monolayers even at high surface pressures, ca. 30 mN/m, under controlled ionic strength, pH, and temperature. Mixed Langmuir monolayers of phytase and DPPG were characterized by surface pressure-area and surface potential-area isotherms, and the presence of the enzyme provided an expansion in the monolayers ( when compared to the pure lipid at the interface). The enzyme incorporation also led to significant changes in the equilibrium surface compressibility (in-plane elasticity), especially in liquid-expanded and liquid-condensed regions. The dynamic surface elasticity for phytase-containing interfaces was investigated using harmonic oscillation and axisymmetric drop shape analysis. The insertion of the enzyme at DPPG monolayers caused an increase in the dynamic surface elasticity at 30 mN m(-1), indicating a strong interaction between the enzyme and lipid molecules at a high-surface packing. Langmuir-Blodgett (LB) films containing 35 layers of mixed phytase-DPPG were characterized by ultraviolet-visible and fluorescence spectroscopy and crystal quartz microbalance nanogravimetry. The ability in detecting phytic acid was studied with voltammetric measurements.

Alternatives Panels from Waste Plastics Reinforced With Fibers of Pupunha Palm for Use in Civil Construction and Furniture Industry

In order to cooperate in minimizing the problems of the current and growing volume of waste, this work aims at the production of panels made from industrial waste -thermoplastic (Polypropylene - PP; Polyethylene - PE and Acrylonitrile Butadiene Styrene - ABS) reinforced with agro-industrial waste - pupunha palm waste (shells and sheaths). The properties of the panels were evaluated: density, thickness swelling, water absorption and moisture content. It was used the ASTM D1037; EN 317; and ANSI A208.1 standards regarding particle boards. The best results in physical tests were treatments 1 (100% waste plastic), 6 (60% plastic waste and 40% waste of pupunha) and 7 (70% waste plastic and 30% waste of pupunha). The best results in the mechanical tests were treatments 3 (30% de residuos plasticos e 70% de residuos da pupunha), 4 (40% de residuos plasticos c 60% de residuos da pupunha) and 5 (50% de residuos plasticos e 50% de residuos da pupunha). For mechanical tests it was concluded that the results of modulus of rupture and of modulus of elasticity the best treatments were those with more fibers. In the tensile tests perpendicular to the surface, it is clear that using more waste plastics leads to the best results. It was concluded that the waste can be used as raw material for the production of alternative materials mainly in civil construction and furniture industries, and it can be employed in urban or rural environment, given the concept of eco-efficient products.

Perceptual Information Integration: Hypothetical Role of Astrocytes

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

Isochronal sintering of the blended elemental Ti-35Nb alloy

Titanium alloy parts are ideally suited for advanced aerospace systems and surgical implants because of their unique combination of high specific strength at both room temperature and moderately elevated temperature, in addition to excellent corrosion resistance. In this work, results of the Ti-35Nb alloy sintering are presented. This alloy, due to its lower modulus of elasticity and high biocompatibility, is a promising candidate for surgical and aerospace applications. Samples were produced by mixing of initial metallic hydride powders followed by uniaxial and cold isostatic pressing with subsequent densification by isochronal sintering between 700 and 1500 degrees C, in vacuum. Sintering behavior was studied by means of microscopy and density. Sintered samples were characterized for phase composition, microstructure and microbardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. Samples sintered at high temperatures display a fine plate-like a structure and intergranular P. A few remaining pores are still found, and density above 97% for specimens sintered at 1500 degrees C is reached. (c) 2007 Elsevier B.V. All rights reserved.

Interaction potential between vortex lines for uniaxial superconductors in the London approximation

Two distinct expressions of the interaction potential between arbitrarily oriented curved vortex lines with respect to the crystal c axis are derived within the London approximation. One of these expressions is used to compute the eigenvalues of the elasticity matrix. We examine the elastic properties of the vortex chain lattice, recently proposed, concerning shearing deformation.

Long-wave and short-wave asymptotics in nonlinear dispersive systems

In this paper we study the interplay between short- and long-space scales in the context of conservative dispersive systems. We consider model systems in (1 + 1) dimensions that admit both long- and short-wavelength solutions in the linear regime. A nonlinear analysis of these systems is constructed, making use of multiscale expansions. We show that the equations governing the lowest order involve only short-wave properties and that the long-wave effects to leading order are determined by a secularity elimination procedure. © 1999 The American Physical Society.

Autosolitons in trapped Bose-Einstein condensates with two- and three-body inelastic processes

The conditions for the existence of autosolitons were considered in trapped Bose-Einstein condensates with attractive atomic interactions. The expression for the parameters of the autosoliton was derived using the time-dependent variational approach for the nonconservative 3-dimensional Gross-pitaevskii equation and their stability was checked. The results were in agreement with the exact numerical calculations. It was shown that the transition from unstable to stable point solely depends on the magnitude of the parameters.

Food restriction-induced myocardial dysfunction demonstrated by the combination of in vivo and in vitro studies

The aim of this study was to test the hypothesis that protein-calorie undernutrition decreases myocardial contractility jeopardizing ventricular function, and that ventricular dysfunction can be detected noninvasively. Five-month-old male Wistar-Kyoto rats were fed with regular rat chow ad libitum for 90 days (Control group, n = 14). A second group of rats received 50% of the amount of diet consumed by de control group (Food restricted group, n = 14). Global LV systolic function was evaluated in vivo, noninvasively, by transthoracic echocardiogram. After echocardiographic study, myocardial contractility was assessed in vitro in the isovolumetrically beating isolated heart in eight animals from each group (Langendorff preparation). The in vivo LV fractional shortening showed that food restriction depressed LV systolic function (p < 0.05). Myocardial contractility was impaired as assessed by the maximal rate of rise of LV pressure (+dP/dt), and developed pressure at diastolic pressure of 25 mmHg (p < 0.05). Furthermore, food restriction induced eccentric ventricular remodeling, and reduced myocardial elasticity and LV compliance (p < 0.05). In conclusion, food restriction causes systolic dysfunction probably due to myocardial contractility impairment and reduction of myocardial elasticity. © 2002 Elsevier B.V. All rights reserved.

Drought tolerance of two field-grown clones of Coffea canephora

We compared tolerance to soil drought of two field-grown clones of Coffea canephora (clone 46, drought-sensitive; and clone 120, drought-tolerant). Under irrigation, there were no marked differences between the clones in water relation parameters, gas exchange and total leaf area. Under rainfed conditions, clone 46 showed osmotic adjustment and increased tissue rigidity. These adjustments, however, were incapable of preventing substantial decreases in xylem pressure potential. By contrast, clone 120 did not exhibit osmotic adjustment, but was able to increase tissue elasticity and to maintain xylem pressure potentials to a greater extent than clone 46 (despite having twice the total leaf area of this clone). Stomatal conductance was lowered by drought in clone 120 but not in clone 46. Carbon assimilation per unit leaf area in both clones remained unaffected under stress. Long-term water use efficiency (WUE), as estimated through carbon isotope discrimination, was consistently greater in clone 120 than in clone 46. Because of these traits, clone 120 was better able to postpone dehydration and to maintain whole-tree photosynthesis. It is proposed that these features should decisively contribute to buffer its productivity in drought-prone areas. © 2002 Elsevier Science Ireland Ltd. All rights reserved.