69 research outputs found

    Microstructural control of ultrafine and nanocrystalline WC-12Co-VC/Cr3C2 mixture by spark plasma sintering

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    The aim of this present work is to study the effect of VC and/or Cr 3C 2 in densification, microstructural control and mechanical behaviour of WC-12Co ultrafine and nanocrystalline mixtures, consolidated by spark plasma sintering at 1100 °C, applying a pressure of 80 MPa in combination with a heating rate of 100 °C min -1. Nanocrystalline and ultrafine mixtures with an average size of 30 nm and 100-250 nm, respectively, with the addition of 1 and 0.5 wt.% of VC/Cr 3C 2 grain growth inhibitors, respectively, were investigated. The density, microstructure, hardness and fracture toughness of the consolidated samples were measured and observed. The addition of VC inhibitor allows an excellent grain growth control keeping microstructures with an average grain size of 154 nm. The hardness values and fracture toughness obtained were about 2000 HV 30 and above 10 MPa m 1/2, respectively. © 2010 Elsevier Ltd and Techna Group S.r.l.The work is supported financially by the Spanish Ministry of Science and Innovation by means of the project MAT 2006-12945-C02. A. Borrell, is grateful to this Ministry for the mobility grant to the Institute of Materials Technology (ITM) of the Polytechnical University of Valencia, Spain.Bonache Bezares, V.; Salvador Moya, MD.; García-Rocha, V.; Borrell Tomás, MA. (2011). Microstructural control of ultrafine and nanocrystalline WC-12Co-VC/Cr3C2 mixture by spark plasma sintering. Ceramics International. 37(3):1139-1142. https://doi.org/10.1016/j.ceramint.2010.11.026S1139114237

    Effect of orthodontic treatment involving first premolar extractions on mandibular third molar angulation and retromolar space

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    Third molars present more problems than other teeth because they are the last teeth to erupt, and so it is important to assess their development when designing an orthodontic treatment plan. The aim of this study was to compare the angulation of the mandibular third molar and retromolar space before and after orthodontic treatment in cases involving first premolar extraction. 76 patients, 59 women (77.63%) and 17 men (22.36%), were recruited from the Orthodontics Clinic at Benemérita Universidad Autónoma de Puebla (Mexico). Panoramic radiographs were analyzed before and after orthodontic treatment that included first premolar extractions, measuring retromolar space (RS) and the angles formed by the intersection of the axes of the third and second molar (?) and the intersection of the axis of the mandibular plane and third molar (?). The data obtained underwent statistical analysis. The angle ? and ? showed statistically significant differences on the left side in women. In men, only the right side ? angle showed significant differences. Retromolar space increased significantly on both sides for both sexes. Third molar angulation presents different behaviors between men and women, with greater verticalization in women

    Spark plasma sintering of TiyNb1-yCxN1-x monolithic ceramics obtained by mechanically induced self-sustaining reaction

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    Nanometer-sized titanium-niobium carbonitride powders (TiyNb1-yCxN1-x) with different Ti/Nb atomic ratios were obtained by a mechanically induced self-sustaining reaction, and sintered by spark plasma sintering technique at 1500 degrees C for 1 min in a vacuum atmosphere. Mechanical properties such as hardness and Young's modulus were determined by nanoindentation technique and friction and wear coefficients assessed by ball-on-disk testing using alumina ball in dry sliding conditions. The fracture surface and wear tracks of samples were examined by scanning electron microscopy. Results showed that it is possible to obtain dense monolithic ceramics from the solid solution (TiyNb1-yCxN1-x) with good mechanical properties and excellent wear resistance. The optimum values of nanomechanical properties were found for the Ti0.3Nb0.7C0.5N0.5 ceramic composition, which exhibited a high hardness over 26.0 GPa and Young's modulus around 400 GPa. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.The authors would like to thank Dr. Emilio Rayon for performing the nanoindentation analysis in the Materials Technology institute (ITM) of the Polytechnic University of Valencia and to acknowledge the financial support received from Spanish Ministry of Science and Innovation for FPI grant (MAT2006-01783). This work was supported by the Spanish government under grant (MAT2010-17046), which is financed in part by the European Regional Development Fund of 2007-2013. E. Chicardi was supported by CSIC through a JAE-Pre grant, which is financed in part by the European Social Fund (ESF).Borrell Tomás, MA.; Salvador Moya, MD.; Garcia-Rocha, V.; Fernandez, A.; Chicardi, E.; Gotor, FJ. (2012). Spark plasma sintering of TiyNb1-yCxN1-x monolithic ceramics obtained by mechanically induced self-sustaining reaction. Materials Science and Engineering: A. 543:173-179. https://doi.org/10.1016/j.msea.2012.02.071S17317954

    Waste-polystyrene foams-derived magnetic carbon material for adsorption and redox supercapacitor applications

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    The current impact of plastic waste on the environment and nature pushes for coming up with methods for their efficient reuse and recycle. Expanded polystyrene waste, massively produced worldwide, is presented in this work as a novel precursor of magnetic activated carbons (MAC) for the first time. A simple methodology based on the impregnation of EPS samples with Fe3+ in solution, followed by pyrolysis under Ar pressure and chemical activation is proposed. The as-prepared carbonaceous magnetic materials present nanometric phases of Fe0, Fe3C, and Fe3O4, and showed high specific surface area (672 m2 g−1) and total pore volume (0.35 cm3 g−1), one of the highest found in the carbonaceous magnetic materials literature. Their excellent textural, chemical and electrical properties, combined with the possibility of magnetically collection and regeneration after operation guaranteed an excellent performance of MAC in two different applications: as adsorbents of organic contaminants and as electrodes of redox supercapacitors.The authors would like to thank the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) for the financial support. P.F.R. Ortega acknowledges the FAPEMIG (DOF nº. 2720262/2018). The authors are also grateful to Rede Mineira de Química. R.L. Lavall is recipient of fellowship from CNPq (grant number 313304/2017-3). N. C. F. Machado, K. H. A. Mendes, and L. A. M. de Jesus would like to thank CEFET-MG and FAPEMIG for scholarships receivedPeer reviewe

    Propuesta de mejora del Sistema Interno de Garantía de Calidad de la Facultad de Medicina

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    La garantía de calidad en el ámbito universitario puede considerarse como la atención sistemática, estructurada y continua a las titulaciones ofertadas. La garantía de calidad se compromete a poner en marcha los medios que aseguren y demuestren la calidad de los programas formativos que se desarrollan en cada una de las titulaciones ofrecidas por la Universidad y así cumplir con la obligación que tiene con la sociedad. El presente proyecto nace como fruto de la responsabilidad adquirida para el cumplimiento de las funciones encomendadas y, con el objetivo de seguir adoptando una estrategia de mejora continua de la calidad de la docencia y satisfacción de los colectivos implicados en el proceso de enseñanza-aprendizaje (Profesorado, Estudiantes y PAS)

    Is there a divide between local medicinal knowledge and Western medicine? a case study among native Amazonians in Bolivia

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    Background: Interest in ethnomedicine has grown in the last decades, with much research focusing on how local medicinal knowledge can contribute to Western medicine. Researchers have emphasized the divide between practices used by local medical practitioners and Western doctors. However, researchers have also suggested that merging concepts and practices from local medicinal knowledge and Western science have the potential to improve public health and support medical independence of local people. In this article we study the relations between local and Western medicinal knowledge within a native Amazonian population, the Tsimane'. Methods: We used the following methods: 1) participant observation and semi-structured interviews to gather background information, 2) free-listing and pile-sorting to assess whether Tsimane' integrate local medicinal knowledge and Western medicine at the conceptual level, 3) surveys to assess to what extent Tsimane' combine local medicinal knowledge with Western medicine in actual treatments, and 4) a participatory workshop to assess the willingness of Tsimane' and Western medical specialists to cooperate with each other. Results: We found that when asked about medical treatments, Tsimane' do not include Western treatments in their lists, however on their daily practices, Tsimane' do use Western treatments in combination with ethnomedical treatments. We also found that Tsimane' healers and Western doctors express willingness to cooperate with each other and to promote synergy between local and Western medical systems. Conclusion: Our findings contrast with previous research emphasizing the divide between local medical practitioners and Western doctors and suggests that cooperation between both health systems might be possible

    Geopolymers based on spent catalyst residue from a fluid catalytic cracking (FCC) process

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    This paper assesses the use of alkali activation technology in the valorization of a spent fluid catalytic cracking (FCC) catalyst, which is a residue derived from the oil-cracking process, to produce geopolymer binders. In particular, the effects of activation conditions on the structural characteristics of the spent catalyst- based geopolymers are determined. The zeolitic phases present in the spent catalyst are the main phases participating in the geopolymerization reaction, which is driven by the conversion of the zeolitic material to a highly Al-substituted aluminosilicate binder gel. Higher alkali content and SiO2/Na2O ratio lead to a denser structure with a higher degree of geopolymer gel formation and increased degree of crosslinking, as identified through 29Si MAS NMR. These results highlight the feasibility of using spent FCC catalyst as a precursor for geopolymer production.This study was sponsored by research scholarship BES-2008-002440 and EEBB-2011-43847 from the Ministerio de Ciencia y Tecnologia of Spain, the European regional development fund (FEDER), and the Universitat Politecnica de Valencia (Spain). The participation of SAB and JLP was funded by the Australian Research Council through the Discovery Projects program, and also including partial funding through the Particulate Fluids Processing Centre, a Special Research Centre of the ARC. The authors wish to acknowledge the Advanced Microscopy Facility at The University of Melbourne for assistance with the electron microscopy experiments conducted in this study.Rodriguez Martinez, ED.; Bernal, SA.; Provis, JL.; Gehman, JD.; Monzó Balbuena, JM.; Paya Bernabeu, JJ.; Borrachero Rosado, MV. (2013). Geopolymers based on spent catalyst residue from a fluid catalytic cracking (FCC) process. Fuel. 109:493-502. https://doi.org/10.1016/j.fuel.2013.02.053S49350210

    Hypoinsulinaemic, hypoketotic hypoglycaemia due to mosaic genetic activation of PI3-kinase.

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    OBJECTIVE: Genetic activation of the insulin signal-transducing kinase AKT2 causes syndromic hypoketotic hypoglycaemia without elevated insulin. Mosaic activating mutations in class 1A phospatidylinositol-3-kinase (PI3K), upstream from AKT2 in insulin signalling, are known to cause segmental overgrowth, but the metabolic consequences have not been systematically reported. We assess the metabolic phenotype of 22 patients with mosaic activating mutations affecting PI3K, thereby providing new insight into the metabolic function of this complex node in insulin signal transduction. METHODS: Three patients with megalencephaly, diffuse asymmetric overgrowth, hypoketotic, hypoinsulinaemic hypoglycaemia and no AKT2 mutation underwent further genetic, clinical and metabolic investigation. Signalling in dermal fibroblasts from one patient and efficacy of the mTOR inhibitor Sirolimus on pathway activation were examined. Finally, the metabolic profile of a cohort of 19 further patients with mosaic activating mutations in PI3K was assessed. RESULTS: In the first three patients, mosaic mutations in PIK3CA (p.Gly118Asp or p.Glu726Lys) or PIK3R2 (p.Gly373Arg) were found. In different tissue samples available from one patient, the PIK3CA p.Glu726Lys mutation was present at burdens from 24% to 42%, with the highest level in the liver. Dermal fibroblasts showed increased basal AKT phosphorylation which was potently suppressed by Sirolimus. Nineteen further patients with mosaic mutations in PIK3CA had neither clinical nor biochemical evidence of hypoglycaemia. CONCLUSIONS: Mosaic mutations activating class 1A PI3K cause severe non-ketotic hypoglycaemia in a subset of patients, with the metabolic phenotype presumably related to the extent of mosaicism within the liver. mTOR or PI3K inhibitors offer the prospect for future therapy

    EuReCa ONE—27 Nations, ONE Europe, ONE Registry A prospective one month analysis of out-of-hospital cardiac arrest outcomes in 27 countries in Europe

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    AbstractIntroductionThe aim of the EuReCa ONE study was to determine the incidence, process, and outcome for out of hospital cardiac arrest (OHCA) throughout Europe.MethodsThis was an international, prospective, multi-centre one-month study. Patients who suffered an OHCA during October 2014 who were attended and/or treated by an Emergency Medical Service (EMS) were eligible for inclusion in the study. Data were extracted from national, regional or local registries.ResultsData on 10,682 confirmed OHCAs from 248 regions in 27 countries, covering an estimated population of 174 million. In 7146 (66%) cases, CPR was started by a bystander or by the EMS. The incidence of CPR attempts ranged from 19.0 to 104.0 per 100,000 population per year. 1735 had ROSC on arrival at hospital (25.2%), Overall, 662/6414 (10.3%) in all cases with CPR attempted survived for at least 30 days or to hospital discharge.ConclusionThe results of EuReCa ONE highlight that OHCA is still a major public health problem accounting for a substantial number of deaths in Europe.EuReCa ONE very clearly demonstrates marked differences in the processes for data collection and reported outcomes following OHCA all over Europe. Using these data and analyses, different countries, regions, systems, and concepts can benchmark themselves and may learn from each other to further improve survival following one of our major health care events
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