893 resultados para Load bearing
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Financial support: FUNDHERP, CTC, INCTC, FAPESP, CNPq and CAPES.
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Financial Support FAPESP, CNPq, CTC/FUNDHERP and INCTC.
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Abstract Background and aims The aim of the present investigation was to examine the anti-wasting effects of theophylline (a methylxantine present in tea leaves) on a rat model of cancer cachexia. Methods The in vitro effects of the nutraceuticals on proteolysis were examined on muscle cell cultures submitted to hyperthermia. Individual muscle weights, muscle gene expression, body composition and cardiac function were measured in rats bearing the Yoshida AH-130 ascites hepatoma, following theophylline treatment. Results Theophylline treatment inhibited proteolysis in C2C12 cell line and resulted in an anti-proteolytic effect on muscle tissue (soleus and heart), which was associated with a decrease in circulating TNF-alpha levels and with a decreased proteolytic systems gene expression. Treatment with the nutraceutical also resulted in an improvement in body composition and cardiac function. Conclusion Theophylline - alone or in combination with drugs - may be a candidate molecule for the treatment of cancer cachexia.
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Introduction / objectives The number of orthopedic surgery, especially surgery of total hip and knee, have been more frequent due to technological advances. This study aims to determine the microbial load in the instruments used in clean surgeries, quantifying and identifying the genus and species of microbial growth.Methods Orthopedic surgical instruments were immersed, after use, in sterile water, sonicated in ultrasonic washer and consecutively shaken. Then, the lavage was filtered through a 0.45micron membrane, the result was incubated in aerobic medium, anaerobic medium and medium for fungi and yeasts. Results In clean surgeries, results showed that 47% of used instruments had microbiological growth in the range of 1 to 100 CFU/instrument. The most prevalent organism was Staphylococcus coagulase negative (28%), followed by Bacillus subtilis (11%).This study refuted the hypothesis that clean surgeries happen in micro-organismsfree surgery field. Conclusion The microbiological findings reinforce the importance of antibiotic prophylaxis, practice already well established for this category of surgical procedure.
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Schistosomiasis constitutes a major public health problem, with an estimated 200 million individuals infected worldwide and 700 million people living in risk areas. In Brazil there are areas of high, medium and low endemicity. Studies have shown that in endemic areas with a low prevalence of Schistosoma infection the sensitivity of parasitological methods is clearly reduced. Consequently diagnosis is often impeded due to the presence of false-negative results. The aim of this study is to present the PCR reamplification (Re-PCR) protocol for the detection of Schistosoma mansoni in samples with low parasite load (with less than 100 eggs per gram (epg) of feces). Three methods were used for the lysis of the envelopes of the S. mansoni eggs and two techniques of DNA extraction were carried out. Extracted DNA was quantified, and the results suggested that the extraction technique, which mixed glass beads with a guanidine isothiocyanate/phenol/chloroform (GT) solution, produced good results. PCR reamplification was conducted and detection sensitivity was found to be five eggs per 500 mg of artificially marked feces. The results achieved using these methods suggest that they are potentially viable for the detection of Schistosoma infection with low parasite load.
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Bearing pads are used in precast concrete connections to avoid concentrated stresses in the contact area between the precast elements. In the present research, the bearing pads are Portland cement mortar with styrene-butadiene latex (SB), lightweight aggregate (expanded vermiculite-term) and short fibers (polypropylene, glass and PVA), in order to obtain a material with low modulus of elasticity and high tenacity, compared with normal Portland cement mortar. The objective of this paper is to analyze the influence of surface roughness on the pads and test other types of polypropylene fibers. Tests were carried out to characterize the composite and test on bearing pads. Characterization tests show compressive strength of 41MPa and modulus of elasticity of 12.8GPa. The bearing pads tests present 30% reduction of stiffness in relation to a reference mortar. The bearing pads with roughness on both sides present a reduction up to 30% in stiffness and an increase in accumulated deformation of more than 120%, regarding bearing pads with both sides smooth.
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[EN]In this work, stiffness and damping functions of pile foundations with inclined end-bearing piles have been computed for square 2X2 and 3X3 pile groups embedded in a soft stratum overlaying a rigid bedrock. The paper algo invetigates the influence that the assumption of a perfectly rigid bedrock and fixed boundary conditions at the pile tips have on the impedance functions.
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The goal of the present study is to understand the mechanism of mass transfer, the composition and the role of fluids during crustal metasomatism in high-temperature metamorphic terranes. A well constrained case study, a locality at Rupaha, Sri Lanka was selected. It is located in the Highland Complex of Sri Lanka, which represents a small, but important fragment of the super-continent Gondwana. Excellent exposures of ultramafic rocks, which are embedded in granulites, were found at 10 localities. These provide a unique background for understanding the metasomatic processes. The boundary between the ultramafic and the granulite rocks are lined with metasomatic reaction zones up to 50cm in width. Progressing from the ultramafics to the granulite host rock, three distinct zones with the following mineral assemblages can be distinguished: (1). phlogopite + spinel + sapphirine, (2). spinel + sapphirine and (3). corundum + biotite + plagioclase. In order to assess the P-T-t path, the peak metamorphism and the exhumation history were constrained using different thermobarometers, as well as a diffusion model of garnet zoning. A maximum temperature of 875 ± 20oC (Opx-Cpx thermometer) and at the peak pressure of 9.0 ± 0.1 kbar (Grt-Cpx-Pl-Qtz) was calculated for the silicic granulite. The ultramafic rocks recorded a peak temperature of 840 ± 70oC (Opx-Cpx thermometer) at 9 kbar. Coexisting spinel and sapphirine from the reaction zone yield a temperature of 820 ± 40oC. This is in agreement with the peak-temperatures recorded in the adjacent granulites and ultramafics rocks. The structural concordance of the ultramafic rocks with the siliceous granulite host rock further support the suggestion, that all units have experienced the same peak metamorphism. Diffusion modeling of retrograde zoning in garnets from mafic granulites suggests a three-step cooling history. A maximum cooling rate of 1oC/Ma is estimated during the initial stage of cooling, followed by a cooling rate of ~30oC/Ma. The outermost rims of garnet indicate a slightly slower cooling rate at about 10-15oC/Ma. The sequences of mineral zones, containing a variety of Al-rich, silica undersaturated minerals in the reaction zones separating the ultramafic rocks from the silica-rich rocks can be explained by a diffusion model. This involves the diffusion of Mg from ultramafic rocks across the layers, and K and Si diffuse in opposite direction. Chemical potential of Mg and Si generated continuous monotonic gradient, allowing steady state diffusional transport across the profile. The strong enrichment in Al, and the considerable loss of Si, during the formation of reaction bands can be inferred from isocon diagrams. Some Al was probably added to the reaction zones, while Si was lost. This is most likely due to fluids percolating parallel to the zones at the boundary of the rock units. This study has shown that not only pressure and temperature conditions but most importantly PH2O and the concentration of the chlorine and fluorine in aqueous fluids also control the mass transport in different geological environments.
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ABSTRACT (italiano) Con crescente attenzione riguardo al problema della sicurezza di ponti e viadotti esistenti nei Paesi Bassi, lo scopo della presente tesi è quello di studiare, mediante la modellazione con Elementi Finiti ed il continuo confronto con risultati sperimentali, la risposta in esercizio di elementi che compongono infrastrutture del genere, ovvero lastre in calcestruzzo armato sollecitate da carichi concentrati. Tali elementi sono caratterizzati da un comportamento ed una crisi per taglio, la cui modellazione è, da un punto di vista computazionale, una sfida piuttosto ardua, a causa del loro comportamento fragile combinato a vari effetti tridimensionali. La tesi è incentrata sull'utilizzo della Sequentially Linear Analysis (SLA), un metodo di soluzione agli Elementi Finiti alternativo rispetto ai classici approcci incrementali e iterativi. Il vantaggio della SLA è quello di evitare i ben noti problemi di convergenza tipici delle analisi non lineari, specificando direttamente l'incremento di danno sull'elemento finito, attraverso la riduzione di rigidezze e resistenze nel particolare elemento finito, invece dell'incremento di carico o di spostamento. Il confronto tra i risultati di due prove di laboratorio su lastre in calcestruzzo armato e quelli della SLA ha dimostrato in entrambi i casi la robustezza del metodo, in termini di accuratezza dei diagrammi carico-spostamento, di distribuzione di tensioni e deformazioni e di rappresentazione del quadro fessurativo e dei meccanismi di crisi per taglio. Diverse variazioni dei più importanti parametri del modello sono state eseguite, evidenziando la forte incidenza sulle soluzioni dell'energia di frattura e del modello scelto per la riduzione del modulo elastico trasversale. Infine è stato effettuato un paragone tra la SLA ed il metodo non lineare di Newton-Raphson, il quale mostra la maggiore affidabilità della SLA nella valutazione di carichi e spostamenti ultimi insieme ad una significativa riduzione dei tempi computazionali. ABSTRACT (english) With increasing attention to the assessment of safety in existing dutch bridges and viaducts, the aim of the present thesis is to study, through the Finite Element modeling method and the continuous comparison with experimental results, the real response of elements that compose these infrastructures, i.e. reinforced concrete slabs subjected to concentrated loads. These elements are characterized by shear behavior and crisis, whose modeling is, from a computational point of view, a hard challenge, due to their brittle behavior combined with various 3D effects. The thesis is focused on the use of Sequentially Linear Analysis (SLA), an alternative solution technique to classical non linear Finite Element analyses that are based on incremental and iterative approaches. The advantage of SLA is to avoid the well-known convergence problems of non linear analyses by directly specifying a damage increment, in terms of a reduction of stiffness and strength in the particular finite element, instead of a load or displacement increment. The comparison between the results of two laboratory tests on reinforced concrete slabs and those obtained by SLA has shown in both the cases the robustness of the method, in terms of accuracy of load-displacements diagrams, of the distribution of stress and strain and of the representation of the cracking pattern and of the shear failure mechanisms. Different variations of the most important parameters have been performed, pointing out the strong incidence on the solutions of the fracture energy and of the chosen shear retention model. At last a confrontation between SLA and the non linear Newton-Raphson method has been executed, showing the better reliability of the SLA in the evaluation of the ultimate loads and displacements, together with a significant reduction of computational times.
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Introduction: The term Clinimetric was introduced by Feinstein in 1982, who first noticed that despite all the improvements in the assessment methods, a number of clinical phenomena were still unconsidered during the evaluation process. Yet today clinical phenomena, such as stress, relevant in diseases progression and course, are not completely evaluated. Only recently, according to the clinimetric approach, Fava and colleagues have introduced specific criteria for evaluating the allostatic overload in clinical setting. Methods: Participants were 240 blood donors recruited from May 2007 to December 2009 in 4 different blood Centers (AVIS) in Italy. Blood samples from each participant were collected for laboratory test the same day the self-rating instruments were administered (Psychosocial Index, Symptom Questionnaire, Psychological well-being scales, Temperament and Character inventory, Self-Report Altruism scale). The study explore different aspects describing sample characteristics and correlates of stress in the total sample (part I), new selection criteria applied to existing instruments to identify individuals reporting allostatic load (part II), and differences on biological correlates between subjects with vs without AL. Results: Significant differences according to gender and past illnesses have been found in different dimensions of well-being and distress. Further, distress was explained for more than 60% by 4 main factors such as anxiety, somatic symptoms, environmental mastery and persistence. According to the new criteria, 98 donors reported AL. Allostatic load individuals reported to engage in less altruistic behaviours. Also they differ in personality traits and characters from controls. In the last part, results showed significant differences among donors according to allostatic load on diverse biological parameters (RBC, MCV, immune essay). Conclusion: This study presents obvious limitations due to its preliminary nature. Further research are need to confirm that these new criteria may lead to identify high risk individuals reporting not only stressful situations but also vulnerabilities.
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The weathering of Fe-bearing minerals under extraterrestrial conditions was investigated by Mössbauer (MB) spectroscopy to gain insights into the role of water on the planet Mars. The NASA Mars Exploration Rovers Spirit and Opportunity each carry a miniaturized Mössbauer spectrometer MIMOS II for the in situ investigation of Martian soils and rocks as part of their payload. The MER flight instruments had to be modified in order to work over the Martian diurnal temperature range (180 K – 290 K) and within the unique electronic environment of the rovers. The modification required special calibration procedures. The integration time necessary to obtain a good quality Mössbauer spectrum with the MIMOS II flight instruments was reduced by 30 % through the design of a new collimator. The in situ investigation of rocks along the rover Spirit's traverse in Gusev crater revealed weakly altered olivine basalt on the plains and pervasively altered basalt in the Columbia Hills. Correlation plots of primary Fe-bearing minerals identified by MB spectroscopy such as olivine versus secondary Fe-bearing phases such as nanophase Fe oxides showed that olivine is the mineral which is primarily involved in weathering reactions. This argues for a reduced availability of water. Identification of the Fe-oxyhydroxide goethite in the Columbia Hills is unequivocal evidence for aqueous weathering processes in the Columbia Hills. Experiments in which mineral powders were exposed to components of the Martian atmosphere showed that interaction with the atmosphere alone, in the absence of liquid water, is sufficient to oxidize Martian surface materials. The fine-grained dust suspended in the Martian atmosphere may have been altered solely by gas-solid reactions. Fresh and altered specimens of Martian meteorites were investigated with MIMOS II. The study of Martian meteorites in the lab helped to identify in Bounce Rock the first rock on Mars which is similar in composition to basaltic shergottites, a subgroup of the Martian meteorites. The field of astrobiology includes the study of the origin, evolution and distribution of life in the universe. Water is a prerequisite for life. The MER Mössbauer spectrometers identified aqueous minerals such as jarosite and goethite. The identification of jarosite was crucial to evaluate the habitability of Opportunity's landing site at Meridiani Planum during the formation of the sedimentary outcrop rocks, because jarosite puts strong constrains on pH levels. The identification of olivine in rocks and soils on the Gusev crater plains provide evidence for the sparsity of water under current conditions on Mars. Ratios of Fe2+/Fe3+ were obtained with Mössbauer spectroscopy from basaltic glass samples which were exposed at a deep sea hydrothermal vent. The ratios were used as a measure of potential energy for use by a microbial community. Samples from Mars analogue field sites on Earth exhibiting morphological biosignatures were also investigated.