524 research outputs found

    Experimental studies on structural timber glass adhesive bonding

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    The utilization of timber in building structures has been increasing in the last years, partly due to technological developments in this field. New tectonic concepts such as prefabricated and industrialised systems arose, though very different from the ones presented by traditional solutions. Hence, the combination of timber with other constructive materials is emerging. Steel, composites materials or glass can be combined with timber, in order to obtain resistant products, highly typified, standardised and with low behavioural variation. The structural utilization of timber glass composite solutions is a daring construtive system, which although still in a very early stage, already presents an important potential of applicability in architecture. In order to fully benefit from composite timber glass cross sections, an adequate bonding between these two elements is essential. With the purpose of achieving the ideal balance between strength and flexibility, an extensive set of experimental tests is being carried out at the University of Minho. This presentation focus on the analysis of results regarding shear stress tests with timber glass bondings, using adhesive as structural bonding system. In these tests, various adhesives were applied, including different trades and adhesive types such as silicone, methacrylate, polyurethane, acrylics and superflex polymers.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BDE/15538/200

    Visser's Massive Gravity Bimetric Theory Revisited

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    A massive gravity theory was proposed by Visser in the late nineties. This theory, based on a backgroung metric bαβb_{\alpha \beta} and on an usual dynamical metric gαβg_{\alpha \beta} has the advantage of being free of ghosts as well as discontinuities present in other massive theories proposed in the past. In the present investigation, the equations of Visser's theory are revisited with a particular care on the related conservation laws.\ It will be shown that a multiplicative factor is missing in the graviton tensor originally derived by Visser, which has no incidence on the weak field approach but becomes important in the strong field regime when, for instance, cosmological applications are considered. In this case, contrary to some previous claims found in the literature, we conclude that a non-static background metric is required in order to obtain a solution able to mimic the Λ\LambdaCDM cosmology.Comment: 10 pages - Accepted for publication in Physical Review

    Numerical simulation and experiments of the multiphase flow in a liquid-liquid cylindrical cyclone separator

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    A Liquid-Liquid Cylindrical Cyclone separator (LLCC) is a device used in the petroleum industry to separate the oil-water mixture obtained from the well. The use of this device has not been widespread due to the lack of tools for predicting its separation capability. This paper presents a numerical and experimental study of the fluid dynamic performance of this type of cylindrical cyclone separators. The use of numerical simulations would reduce the time and cost necessary to obtain information for predicting the behavior of the equipment. The objective of this study is to determine if CFD (Computational Fluid Dynamics) techniques are able to reproduce the behavior of a LLCC separator. The CFD software examined was ANSYS-CFX 5.6TM and numerical simulations were carried out using the dispersed model with oil as the dispersed phase. The oil and water mixture entering the separator is divided due to centrifugal and buoyancy forces in an upper (oil rich) exit and a bottom (water rich) exit. The separation capability is determined as the maximum amount of water removed from the mixture with the minimum amount of oil content in the water rich exit. The experiments were conducted in a transparent LLCC separator that allows the visualization of the mixture and the measurement of the oil content. Experiments were conducted for three variables: mixture velocity and water content at the entrance, and the split ratio. The split ratio is defined as the bottom exit flow rate divided by the water flow rate at the entrance. The results showed that CFD tools are able to reproduce the oil content obtained from the experiments for all analyzed conditions. Additionally, the mixture distribution images from numerical and experimental data showed good agreement. This study confirms the capacity of CFD tools for the multiphase flow analysis of LLCC separators

    Numerical simulation and experiments of the multiphase flow in a liquid-liquid cylindrical cyclone separator

    Get PDF
    A Liquid-Liquid Cylindrical Cyclone separator (LLCC) is a device used in the petroleum industry to separate the oil-water mixture obtained from the well. The use of this device has not been widespread due to the lack of tools for predicting its separation capability. This paper presents a numerical and experimental study of the fluid dynamic performance of this type of cylindrical cyclone separators. The use of numerical simulations would reduce the time and cost necessary to obtain information for predicting the behavior of the equipment. The objective of this study is to determine if CFD (Computational Fluid Dynamics) techniques are able to reproduce the behavior of a LLCC separator. The CFD software examined was ANSYS-CFX 5.6TM and numerical simulations were carried out using the dispersed model with oil as the dispersed phase. The oil and water mixture entering the separator is divided due to centrifugal and buoyancy forces in an upper (oil rich) exit and a bottom (water rich) exit. The separation capability is determined as the maximum amount of water removed from the mixture with the minimum amount of oil content in the water rich exit. The experiments were conducted in a transparent LLCC separator that allows the visualization of the mixture and the measurement of the oil content. Experiments were conducted for three variables: mixture velocity and water content at the entrance, and the split ratio. The split ratio is defined as the bottom exit flow rate divided by the water flow rate at the entrance. The results showed that CFD tools are able to reproduce the oil content obtained from the experiments for all analyzed conditions. Additionally, the mixture distribution images from numerical and experimental data showed good agreement. This study confirms the capacity of CFD tools for the multiphase flow analysis of LLCC separators

    Leucemia mieloide aguda con diferenciación monocítica: reporte de un caso

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    We present a case of acute monocytic leukemia with monocytic differentiation in a 58-year-old male patient, who was admitted for emergency care at the Alberto Sabogal Sologuren National Hospital. The clinical and laboratory findings of the particular case are described, with emphasis on cytomorphology and immunophenotype. Likewise, a general presentation of the disease is made and, since it is a rare hematologic neoplasm, recommendations for its identification and reporting from the laboratory are proposed.Presentamos un caso de leucemia mieloide aguda con diferenciación monocítica en un paciente varón de 58 años, captado por atención de emergencia en el Hospital Nacional Alberto Sabogal Sologuren. Se describen los hallazgos clínicos y de laboratorio del caso particular, con énfasis en la citomorfología y el inmunofenotipo. Asimismo, se hace una exposición general de la enfermedad y por tratarse de una neoplasia hematológica poco frecuente, se proponen recomendaciones para su identificación y reporte desde el laboratorio

    Leucemia mieloide aguda con diferenciación monocítica: reporte de un caso

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    Presentamos un caso de leucemia mieloide aguda con diferenciación monocítica en un paciente varón de 58 años, captado por atención de emergencia en el Hospital Nacional Alberto Sabogal Sologuren. Se describen los hallazgos clínicos y de laboratorio del caso particular, con énfasis en la citomorfología y el inmunofenotipo. Asimismo, se hace una exposición general de la enfermedad y por tratarse de una neoplasia hematológica poco frecuente, se proponen recomendaciones para su identificación y reporte desde el laboratorio

    Cost efficiency and resistance to chemical attack of a fly ash geopolymeric mortar versus epoxy resin and acrylic paint coatings

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    This article presents results of an experimental investigation on the resistance to chemical attack (with sulphuric, hydrochloric and nitric acid) of several materials: OPC concrete, high-performance concrete, epoxy resin, acrylic painting and a fly ash-based geopolymeric mortar). Three types of acids with three high concentrations (10, 20 and 30%) were used to simulate long-term degradation. A cost analysis was also performed. The results show that the epoxy resin has the best resistance to chemical attack independently of the acid type and the acid concentration. However, the cost analysis shows that the epoxy resin-based solution is the least cost-efficient solution being 70% above the cost efficiency of the fly ash-based geopolymeric mortar

    TGF-β antagonist attenuates fibrosis but not luminal narrowing in experimental tracheal stenosis.

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    Introduction/Objective: Acquired tracheal stenosis (ATS) is an unusual disease often secondary to prolonged mechanical trauma. ATS pathogenesis involves inflammation and subsequent fibrosis with narrowing of the tracheal lumen. TGF-β represents a pivotal factor in most fibrotic processes and therefore, a potential target in this context. The aim of this study is to analyze the role of TGF-β as a target for anti-fibrotic interventions in tracheal stenosis. Methods: Human stenotic tracheobronchial tissues from patients with benign airway stenosis and normal controls from pneumonectomy specimens were analyzed. Tracheal stenosis was induced in adult NZ rabbits by a circumferential thermal injury to the mucosa during open surgery and re-anastomosis. Rabbits were treated postoperatively with a peritracheal collagen sponge containing a TGF-β peptide antagonist (p17) or vehicle. Fibrosis was determined by Masson’s trichrome staining, and α-SMA+ Results: Human and rabbit stenotic tissues showed extensive submucosal fibrosis, characterized by significantly increased α-SMA myofibroblasts, CTGF and p-Smad2/3 expression by immunohistochemistry. + myofibroblasts and CTGF expression. In human stenotic lesions, increased p-Smad2/3+ nuclei were also observed. p17 treatment significantly reduced the fibrotic thickness as well as the density of α-SMA+ myofibroblasts and CTGF+ Conclusion: ATS is characterized by a TGF-β dependent fibrotic process but reduction of the fibrotic component by TGF-β1 antagonist therapy was not sufficient to improve tracheal narrowing, suggesting that fibrosis may not be the main contributor to luminal stenosis. cells in rabbit stenotic lesions but failed to improve the luminal area.pre-print1304 K

    Moisture effect on the separation of CO2/CH4 mixtures with amine-functionalised porous silicas

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    The effect of minor amounts of water on the CO2 and CH4 adsorption on primary and secondary amine-functionalised mesoporous silicas (APTES@SBA-15 and DEAPTES@SBA15, respectively) was studied with a combination of high-pressure gas adsorption, solid state NMR of labelled 13CO2 and density functional theory (DFT) calculations. Known amounts of water were pre-adsorbed on the materials (0.047 to 0.157 mmol∙g−1) and the adsorption performance for CO2 and CH4 was compared to the performance of the dry samples. We observed that even when only minor amounts of water are present, the tertiary amine-functionalised material revealed a significant enhancement of the selectivity for CO2 (from ca. 5.8 to 208) while the one with primary amine maintained the same adsorption properties. This is related to the change in the adsorption mechanism in DEAPTES@SBA15 when water is present since water participates in the reaction of the tertiary amine with CO2 to produce bicarbonate (confirmed by NMR and DFT results). Such species was not observed in APTES@SBA-15 with water. From a broader perspective, the results presented in this work are relevant to confirm the suitability of this type of hybrid adsorbents in industrial applications related with CO2 adsorption, where minor amounts of water may be present in the process streams, such as during bio, landfill, or natural gas upgrading, or also in carbon capture applications.publishe
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