591 research outputs found

    Teacher education and the teachers’ competencies:a view from primary school pre-service teachers’ perceptions

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    Abstract. Scholars understand competencies as a mixture of abilities, knowledge, skills, and behaviors. Equally, it can be understood as a measure of one’s performance. Thus, varied catalogs of teachers’ competencies are discussed in the academical set. However, Ding (2016), categorized eight key competencies for the primary teacher. They are: Pedagogical competencies; Curriculum Knowledge; Assessment; Classroom Management; Culture and Cross-Culture competencies; Ethical and Professional Values; Social, Emotional and Communication; and Life-long Learning competencies. This set of competencies was chosen as the base of data collection and helped to categorize the data in the data analysis procedure. The aim was to explore the teachers’ competencies in Primary Teacher Education based on the pre-service teachers’ perceptions and to explore the competencies required for the teaching practice in Primary Schools, making a comparison between work field and teacher training under the competencies theme. The study was conducted using a qualitative method, and the data was collected via semi-structured one-on-one interviews and content analyzed. The chosen method for sampling was the non-probabilistic convenience one. The research questions were: What are the pre-service teachers’ perceptions of the competencies the Teacher Education provides? What are the competencies the work requires according to the Primary school curriculum? And what are the differences and similarities between the pre-service teachers’ perceptions of competencies they have gained and the competencies the Primary Education field actually requires? As results, this study showed that there is a difference between the competencies pre-service teachers are learning in Teacher Education and the competencies they need in the working field. Also, the relevance of practice was explored as it helps bridge the gap that exists between theoretical knowledge and challenges that are encountered in the classroom. The relatively short time for teaching practice, the low acquisition of teachers’ competencies from the student-teachers, and the lack of a mentor’s support from University or the school are some of the issues the pre-service teachers are facing that are establishing this gap

    Characterization of a Copper Powder for Heat Pipe Wick Applications

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    In powder metallurgy, it is necessary to know the powder's nature to understand how the processing of a powder occurs. In this paper, a characterization of a copper powder for heat pipe wick applications was experimentally done. The copper powder manufacturing method was atomization. This metallic powder was characterized by Scanning Electron Microscopy (SEM), X-Ray Fluorescence Spectrometry (ED-XRF), and Laser Diffraction Granulometry. As a result, the purity and the shape are compatible with the powder manufacturing method and great for wicks. Also, the copper powder has a unimodal distribution that is excellent for capillary structures

    Study of ph effect on AZ31 magnesium alloy corrosion for using in temporary implants

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    Currently, magnesium alloys are gaining great interest for medical applications due to their degrading properties in the human body ensuring a great biocompatibility. These alloys also provide profitable mechanical properties due similarities with human bone.  However, a difficulty in applying these materials in the biomaterials industries is the corrosion prior to cell healing. The effect of the chemical composition of Mg alloys on their corrosion behavior is well known. In this study, samples of AZ31 magnesium alloy were cut into chips for elemental chemical analysis by neutron activation analysis (NAA). Concentrations of the elements As, La, Mg, Mn, Na, Sb and Zn were determined in the AZ31 alloy. Visualization tests of agar corrosion development in various media, of 0.90% sodium chloride solution (mass), phosphate buffer saline (PBS) and simulated body fluid (SBF) were performed. Visualizations of the effect of agar gel corrosion revealed pH variation during the corrosion process due to the released into the cathode. The highest released of hydroxyl ions occurred in NaCl solution compared to PBS and SBF solutions indicating that NaCl solution was much more aggressive to the alloy compared to the others

    Qualidade de vida de pacientes submetidos à cirurgia bariátrica: estudo transversal

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    Purpose: Analyze factors that influenced the quality of life (QoL) of patients after bariatric surgery. Methods: A cross-sectional study was carried out, involving 307 adult bariatric surgery patients between 2012 and 2014. Data was obtained from the electronic patient records and telephone interviews. To assess the QoL, the World Health Organization Quality of Life-Bref (WHOQOL-bref) was used. A simple linear regression model was constructed, adjusted by sociodemographic variables, with p<0.05. Results: The domains with the worst scores were the physical (mean=58.45; SD±10.42) and environmental (mean=65.19; SD±11.36). The best domains were the social (mean=76.51; SD±15.71) and psychological (mean=68.70; SD±15.71). In the linear regression model, it was observed that time since the surgery was inversely associated with the physical health domain. For each month post-bariatric surgery, the patient’s average score dropped by 2.66 points, adjusted by sex and age. Conclusions: Time since the surgery could be an important determinant of the physical domain score of quality of life. Identifying the quality of life after bariatric surgery and influential factors is fundamental to prepare these patients for the changes deriving from the weight loss.Objetivo: Analizar los factores que influyeron en la calidad de vida (CV) de los pacientes después de la cirugía bariátrica. Métodos: Se llevó a cabo un estudio transversal en el que participaron 307 pacientes adultos con cirugía bariátrica entre 2012 y 2014. Se han obtenido los datos de los registros electrónicos de los pacientes y de sus entrevistas telefónicas. Después se construyó un modelo de regresión lineal simple, ajustado por variables sociodemográficas, con p <0.05. Para evaluar la CV, se utilizó la Calidad de Vida Breve de la Organización Mundial de la Salud (WHOQOL-bref). Resultados: Los dominios con las peores puntuaciones fueron el físico (media = 58,45; SD ± 10,42) y ambiental (media = 65,19; SD ± 11,36). Los mejores dominios fueron el social (media = 76.51; SD ± 15.71) y psicológico (media = 68.70; SD ± 15.71). En el modelo de regresión lineal, se observó que el tiempo desde la cirugía se asoció inversamente con el dominio de la salud física. Por cada mes posterior a la cirugía bariátrica, el puntaje promedio del paciente se redujo en 2.66 puntos, ajustado por sexo y edad. Conclusión: El tiempo transcurrido desde la cirugía puede ser un determinante importante de la puntuación del dominio físico de la calidad de vida. Identificar la calidad de vida después de la cirugía bariátrica y los factores influyentes es fundamental para preparar a estos pacientes para los cambios derivados de la pérdida de peso.Objetivo: Analisar os fatores que influenciaram a qualidade de vida (QV) dos pacientes após a cirurgia bariátrica. Método: Realizado um estudo transversal envolvendo 307 pacientes adultos submetidos à cirurgia bariátrica, no período de 2012 a 2014. Os dados foram obtidos por meio de prontuário eletrônico e entrevistas telefônicas. Para avaliar a QV, foi utilizada a World Health Organization Quality of Life-bref (WHOQOL-bref). Um modelo de regressão linear simples foi construído, ajustado por variáveis sociodemográficas, com p <0,05.Resultados: Os domínios com os piores escores foram físico (média = 58,45; DP ± 10,42) e ambiental (média = 65,19; DP ± 11,36). Os melhores domínios foram o social (média = 76,51; DP ± 15,71) e o psicológico (média = 68,70; DP ± 15,71). No modelo de regressão linear, observou-se que o tempo desde a cirurgia foi inversamente associado ao domínio saúde física. Para cada mês pós-cirurgia bariátrica, a pontuação média do paciente caiu em 2,66 pontos, ajustada por sexo e idade. Conclusão: O tempo desde a cirurgia pode ser um importante determinante do escore do domínio físico de QV. Identificar a QV após a cirurgia bariátrica e fatores que a influenciam é fundamental para preparar esses pacientes para as mudanças decorrentes da perda de peso

    A study on corrosion resistance of ISO 5832-1 austenitic stainless steel used as orthopedic implant

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    The ISO 5832-1 austenitic stainless steel used as biomaterial is largely applied in the area of orthopedics, especially in the manufacture of implants, such as temporary or permanent replacement of bone structures. The objective of this study was to evaluate the localized corrosion resistance of the ISO 5832-1 stainless steel used in orthopedic implants by electrochemical tests in two different solutions. The results of this study are of great interest to evaluate the corrosion of metallic implants that can result in the release of corrosion products into bodily fluids causing possible adverse biological reactions. The determination of the chemical elements in the composition of the ISO 5832-1 stainless steel was performed by neutron activation analysis (NAA). The samples for electrochemical tests were grinded with silicon carbide paper up to #4000 finishing, followed by mechanical polishing with diamond paste. The open circuit potential measurements and anodic polarization curves were obtained in solution of 0.90 wt. % of NaCl and of simulated body fluid (SBF). The results indicated that the ISO 5832-1 stainless steel presented a high resistance to crevice corrosion in simulated body fluid solution but high susceptibility to this form of corrosion in the chloride solution. &nbsp

    iphasic oxidative denitrogenation with H2O2 of a simulated fuel using sustainable carbon nanotube catalysts

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    The presence of nitrogenated compounds in liquid fuels (e.g. quinoline (QN), azapyrene, pyrrole, indole or carbazole) is associated with a series of environmental and health issues [1], as upon their combustion, noxious NOx gases are formed. Typically, those heteroatoms are removed by hydrodenitrogenation (HDN), a process based on the application of H2 under high temperature and pressure [2]. However, due to the type of nitrogenated compounds found in crude oils, which consist mostly of cyclic structures containing two double bonds between N and C atoms, HDN fails to efficiently remove nitrogen without affecting the properties of the fuel [1]. Thus, alternatives to HDN have been sought, the removal of those nitrogenated compounds via oxidative processes being found as promising [1]. In oxidative denitrogenation (ODN), nitrogen-based compounds are oxidized towards more polar compounds, which can be further removed from the fuel with an extractant [3]. Furthermore, another contemporary issue is the production and accumulation of residues, especially plastic solid waste (PSW). PSW can be used as precursors for the synthesis of sustainable carbon nanotubes (CNTs), which could be further applied as catalysts in ODN. In this work, a nitrogen-rich fuel was simulated by dissolving QN (CQN-i-octane,0 = 1 g L-1) in 2,2,4-trimethylpentane (i-octane), and ODN was carried out using H2O2 as oxidant and CNTs (derived from a mixture of polymers simulating PSW) as catalysts, under a biphasic system (oxidation and extraction co-occurrence).This work was financially supported by project "PLASTIC_TO_FUEL&MAT – Upcycling Waste Plastics into Fuel and Carbon Nanomaterials" (PTDC/EQU-EQU/31439/2017), Base Funding - UIDB/50020/2020 of the Associate Laboratory LSRE-LCM - funded by national funds through FCT/MCTES (PIDDAC), and CIMO (UIDB/00690/2020) through FEDER under Program PT2020. Fernanda F. Roman acknowledges the national funding by FCT, Foundation for Science and Technology, and FSE, European Social Fund, through the individual research grant SFRH/BD/143224/2019.info:eu-repo/semantics/publishedVersio

    Oxidative denitrogenation of a simulated fuel under a biphasic green system

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    Este trabalho trata da desnitrificação catalítica de um combustível simulado (quinolina (QN) em 2,2,4-trimetilpentano) por oxidação com peróxido de hidrogénio em meio bifásico. Como catalisadores, foram utilizados três materiais: (i) ferro suportado em alumina (Fe/Al2O3) obtido por sol-gel, (ii) nanotubos de carbono (CNT) produzidos através da deposição química em fase de vapor de propileno (PP) sobre o catalisador anterior (Fe/Al2O3), e (iii) os CNT fornecidos pela Sigma Aldrich. A contribuição da adsorção e da extração foi avaliada, sendo ambas consideradas desprezáveis ou pouco efetivas para a remoção da QN. O desempenho de cada material foi analisado em testes de reação de 4 h, a 80 °C, através da monitorização da degradação de H2O2 e da concentração de QN em meio oleoso e aquoso. Como resultados, todos os materiais utilizados atenderam ao objetivo proposto, sendo 100% da QN removida da fase oleosa nos ensaios de oxidação bifásica. Em resumo, todos os catalisadores produzidos foram eficientes no processo proposto e são comparáveis ao desempenho obtido pelo CNT comercialThis work deals with the catalytic denitrogenation of a simulated fuel (quinoline (QN) in 2,2,4-trimethylpentane) by oxidation with hydrogen peroxide in a biphasic medium. As catalysts, three materials were used (i) iron supported on alumina (Fe/Al2O3) obtained by sol-gel, carbon nanotubes (CNT) produced by chemical vapor deposition of propylene (PP) growth on the previous catalyst (Fe/Al2O3) and (iii) a commercial sample of CNT supplied by Sigma Aldrich. The contribution of adsorption and extraction was also assessed, both being considered negligible or ineffective for the removal of QN. The performance of each catalyst was analysed in 4 h reaction tests, at 80 °C, by monitoring the degradation of H2O2 and the concentration of QN in the oily and aqueous media. As a result, all catalysts used met the proposed objective, with 100% of QN being removed from the oily phase in the biphasic oxidation tests. In summary, all the catalysts produced were efficient in the proposed process and are comparable to the performance obtained by the commercial CNT sample.This work was financially supported by project “PLASTIC_TO_FUEL&MAT – Upcycling Waste Plastics into Fuel and Carbon Nanomaterials” (PTDC/EQU-EQU/31439/2017), LA/P/0045/2020 (ALiCE), UIDB/50020/2020 and UIDP/50020/2020 (LSRE-LCM), funded by national funds through FCT/MCTES (PIDDAC) and CIMO (UIDB/00690/2020) through FEDER under Program PT2020. Fernanda F. Roman acknowledges the national funding by FCT, Foundation for Science and Technology, and FSE, European Social Fund, through the individual research grant SFRH/BD/143224/2019. Jose L. Diaz de Tuesta acknowledges the financial support through the program of “Atracción al Talento” of “Comunidad de Madrid” (Spain) for the individual research grant 2020-T2/AMB-19836.info:eu-repo/semantics/publishedVersio
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