22 research outputs found

    ElaboraciĂł d'una llibreta de laboratori

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    Material docent d'auto aprenentatge de com elaborar adequadament una llibreta de laboratori de quĂ­mica analĂ­tica

    Material characterization and functional implications of a Claude Laurent Glass Flute

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    The Claude Laurent glass flutes (1805–1844) are singular elements that contributed to the transformation of musical instruments through the introduction of new styles and technologies. These flutes combine improved technical capabilities with aesthetic criteria, making them high-quality instruments and appreciated objects of art. Through the analysis of an 1823 flute, the present study is focused on the determination of their material characteristics and the relationship of these materials with the flute's structure and constructive process. The composition of the glass and metallic parts has been determined by XRF after establishing a specific calibration for each material and energy range. A potash-lime-silica glass, which shows similar composition to some previously analysed flutes conserved at the Library of Congress in Washington, was used for the glass parts of the flute. Composition of the metallic parts of a Laurent flute is presented for the first time. Regarding the larger parts, four different composition groups can be distinguished. The composition established can yield information about the constructive process and can be related to the function of each group. For example, a silver-copper alloy serving aesthetic reasons was used for all visible metallic parts, while hidden parts that demand higher mechanical resistance were made with bronze. Regarding the flute's smaller metallic parts, which consist of the keys and key levers and some mechanical pieces, such as screws or springs, the materials detected include a silver-copper alloy and steel

    Analysis of isotopes of plutonium in water samples with a PSresin based on aliquatâ‹…336

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    There is a necessity to have techniques capable to perform rapid determinations of specific radionuclides with the aim to provide fast response in emergency situations where a large number of samples need to be measured in a short time. Plastic Scintillation Resins (PSresins) raises as an adequate tool to achieve this purpose and in the present study a methodology to determine plutonium using a PSresin based on Aliquat·336 was developed. Different sample treatments have been studied under acidic conditions with an emphasis on valence adjustment treatment to achieve an effective retention within the PSresin. Under 3 M nitric acid conditions and an iron sulphamate (II) + nitrite valence adjustment, quantitative retention and 100% detection efficiency were achieved. The retention of the different interferences evaluated (238U, 230Th, 241Am, 210Pb and 99Tc) was low and therefore they do not interfere significantly in the determination of plutonium, except for 99Tc. Finally, a stable tracer to calculate the PSresin separation yield was studied, revealing that gold is suitable for this purpose. This procedure was applied to the analysis of spiked sea and river water samples, obtaining errors lower than 10% in their quantification

    Skill development in experimental courses

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    Experimental courses offer a good opportunity to work with competences, promoting the incorporation of strategies oriented towards motivating students to actively involve in the learning process, promoting reflexive learning and developing generic skills. This study presents different ways of developing and evaluating some important general skills, settle on four specific objectives: 1. To increase student motivation using samples of potential interest to students and explaining real-live application of their samples analyses; 2. To assist students' self-regulation and learning autonomy by using the portfolio; 3. To promote group work through experiments in pairs and small-group discussions; 4. To develop communication skills through small-group discussions and oral presentations. Results show that the type of sample used and real-life application has important influence on motivation. The portfolio is a good tool to promote reflection and to evaluate both specific and generic skills in experimental courses, the dynamics of a laboratory course permit students to develop their group-work and communicative skills, and peer evaluations both improve students' communication skills and promote metacognitive reflection. Finally, the project demonstrates that it is possible to train students in general skills using the specific course content and that the incorporation of participatory methodologies encourages students to become actively involved in the teaching-learning process

    PSresin for the analysis of alpha-emitting radionuclides: Comparison of diphosphonic acid-based extractants

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    The analysis of radionuclides is complex, with high economic and time costs. For this reason, there is a need to develop new methods and strategies to reduce these costs. One important group in the analysis of radionuclides is the actinides, which are the main constituents assessed in the total gross alpha together with radium and radon test used to measure radioactivity in drinking water. Moreover, in nuclear dismantling processes, the possible spread of the released radionuclides has to be controlled, which is measured by many techniques, depending on the radionuclides, through scintillation. This work presents a new method to analyse actinides using plastic scintillation resins (PSresins) packed in a solid-phase extraction cartridge. The proposed method combines chemical separation and sample measurement into a single step, reducing the effort, time and reagents required for analysis as well as decreasing the amount of waste generated. The PSresins compared in this study contained three selective extractants based on Methylenediphosphonic acid with different radicals, which has a high affinity for tri-, tetra-, and hexavalent actinides in dilute acids. These extractants were immobilised on plastic scintillation microspheres at a ratio of 1/1:6, producing a retention and detection efficiency of 100% for 241Am, 230Th, Uranium and 238Pu. The retention and detection efficiency were 20% and 100%, respectively, for 210Po and low for 226Ra

    Skill development in experimental courses

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    Experimental courses offer a good opportunity to work with competences, promoting the incorporation of strategies oriented towards motivating students to actively involve in the learning process, promoting reflexive learning and developing generic skills. This study presents different ways of developing and evaluating some important general skills, settle on four specific objectives: 1. To increase student motivation using samples of potential interest to students and explaining real-live application of their samples analyses; 2. To assist students’ self-regulation and learning autonomy by using the portfolio; 3. To promote group work through experiments in pairs and small-group discussions; 4. To develop communication skills through small-group discussions and oral presentations. Results show that the type of sample used and real-life application has important influence on motivation. The portfolio is a good tool to promote reflection and to evaluate both specific and generic skills in experimental courses, the dynamics of a laboratory course permit students to develop their group-work and communicative skills, and peer evaluations both improve students’ communication skills and promote metacognitive reflection. Finally, the project demonstrates that it is possible to train students in general skills using the specific course content and that the incorporation of participatory methodologies encourages students to become actively involved in the teaching-learning proces

    Evaluation of synthesis conditions for plastic scintillation foils used to measure alpha- and beta-emitting radionuclides

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    Plastic scintillation foils of polystyrene and polycarbonate with a thickness between 45 and 200 ÎĽm, have been produced using the solvent evaporation method. PSfoils presented a reproducible thickness (10-20%). PSfoils were characterized by the measurement of 36Cl or 241Am. For 36Cl spectrum is located at medium energies since not all energy is deposited in the scintillator and not all betas interact with the foils. For 241Am the efficiency values are very high and spectrum is a sharp peak located at high energies. 222Rn absorption (LD and K) and desorption capacities of the PSfoils have been also evaluated

    Carpeta docent / Bienni 2010-2012 - Héctor Bagán Navarro

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    Màster de Docència Universitària per a Professorat Novell, Institut de Ciències de l'Educació, Universitat de Barcelona. Bienni: 2010-2012. Mentor: Dr. José F. García MartínezEs presenta la carpeta docent elaborada en el context del màster i l'aplicació a les assignatures de "Laboratori bàsic de Química Analítica" i "Laboratori de Química Analítica" de la Facultat de Química de la Universitat de Barcelona

    ElaboraciĂł d'una llibreta de laboratori

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    Material docent d'auto aprenentatge de com elaborar adequadament una llibreta de laboratori de quĂ­mica analĂ­tica

    ElaboraciĂł d'una llibreta de laboratori

    No full text
    Material docent d'auto aprenentatge de com elaborar adequadament una llibreta de laboratori de quĂ­mica analĂ­tica
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