700 research outputs found

    High submicellar liquid chromatography

    Get PDF
    Surfactant addition above the critical micellar concentration (CMC), in reversed-phase liquid chromatography (RPLC), was proposed as a way to modify the selectivity and analysis time, giving rise to a chromatographic mode called micellar liquid chromatography (MLC). However, solutions containing only surfactant are too weak and yield poor peak shape. This was remediated by the addition of a small amount of organic solvent. To preserve the existence of micelles, in MLC high contents of organic solvent are avoided. Nevertheless, there is no reason to neglect the potentiality of mobile phases containing a surfactant above its CMC in water and a high organic solvent content (without micelles). This chromatographic mode has been called high submicellar liquid chromatography (HSLC). Several reported procedures show that the combination of stronger elution strength, larger selectivity and improved peak shape, with respect to MLC and conventional RPLC, makes HSLC a promising chromatographic mode to achieve in practical times separations of compounds unresolved or highly retained with other RPLC modes. Some insights on the interactions that occur inside the chromatographic column, the modification of the stationary and mobile phases, retention modeling, and chromatographic performance in HSLC are here offered, in comparison to MLC and conventional RPLC

    Design of the laboratory script by the students in chemistry practicals: Analysis of water

    Get PDF
    Comunicació presentada a INTED2018, 12th International Technology, Education and Development Conference. (March 5-7, 2018, Valencia, Spain).The laboratory practices during the Degree in Chemistry are currently designed so that the student must learn and execute a fully developed experimental protocol, previously written up by the professor, which contains all the information and requirements for the correct development of each laboratory session. Under these conditions, students do not need to take any initiative and, consequently, they do not put enough effort in reaching practical abilities with a well-based scientific criterion and do not try to think over the purpose of each lab operation, as well as the reason to use each material and/or each reagent. Thus, with the aim to promote a more active role of the students in their learning process and to improve their autonomy, a new laboratory practices design has been developed in this work, which follows methodologies on project-based cooperative learning: the students have been requested to elaborate themselves the laboratory script by pairs. With this innovative design, we pursue to involve the students in both elaboration and execution steps of the laboratory practicals, and then to increase their attention on them. Besides, the required bibliographic research would improve their knowledge about the studied topic and all aspects about the work at the laboratory. The practicals to-be-developed were related to the study of the physico-chemical quality of natural water, which has a high social relevance

    Management of diversity in master classroom: an increasing challenge for science education in valencian universities

    Get PDF
    Comunicació presentada a INTED2018, 12th International Technology, Education and Development Conference. (March 5-7, 2018, Valencia, Spain).Currently, many foreign students study a Master degree at the Valencian Universities. We can find students, which have immigrated to Spain in the recent years, and then have partially or fully follow the Spanish curricula (High School and/or Grade), and others which have come specifically to study the Master, attracted by the reputation of the Universities and the job and way-of-life offered by the country, and then have achieved their Grade in their countries. This has increased the diversity of the students in the classrooms, related to the ethnic origin, mother language, study practices, background and integration in the society. The present work gives an overview on how students and teacher manage the heterogeneity and diversity in a Master classroom related to chemistry. The term “diversity” is first detailed prior to discussing explicit studies. Different aspects of diversity are stated. The personal experience of the foreign students to adapt to the Spanish courses and environment was investigated. The actions taken by the lecturer to take advantage of diversity and minimize its negative effects were examined. A comparison between the academic results obtained by international and national students is given. Finally, the attention will be focused on language, study practices and background, since these dimensions are frequently discussed in the Valencian context. The implications and opportunities that offer diversity for national but also for international science research are presented

    Implantación de las buenas prácticas de laboratorio en la asignatura "Química para las Ingenierias" en la Universitat Jaume I

    Get PDF
    Comunicación presentada en la V Jornada Nacional sobre Estudios Universitarios, celebrades en la Universitat Jaume I (Castellón, España), los dies 12 y 13 de Noviembre de 2015.En el presente artículo, se detalla la implementación de las Buenas Prácticas de Laboratorio (BPL) en el laboratorio de la asignatura «Química para las Ingenierías» (EX1006), impartida en varios grados de ingeniería (Agroalimentaria y del Medio Ambiente, Mecánica, Eléctrica, Tecnologías Industriales y Química) de la Universitat Jaume I. Las BLP son un conjunto de normas y procedimientos operativos acerca de la forma adecuada de organizar y trabajar en el laboratorio en una amplia variedad de disciplinas científicas, incluida la química. El principal objetivo de las BPL es asegurar la fiabilidad, estabilidad y calidad de los resultados. Para ello, se indica cómo el procedimiento experimental debe ser planificado, ejecutado, supervisado, anotado, registrado y archivado. Asimismo, proporciona recomendaciones para la gestión del laboratorio, en especial para minimizar el vertido de residuos tóxicos, e incrementar la seguridad laboral en el laboratorio. Varias organizaciones y agencias internacionales (industria farmacéutica, la Organización para la Cooperación y el Desarrollo Económicos, US Food and Drug Administration y la Comisión Europea), han desarrollado y promulgado varios conjuntos de normas BLP. La Universitat Jaume I considera que un conocimiento profundo y una aplicación adecuada de las BPL son muy importantes para desarrollar un trabajo correcto en el laboratorio químico. Por ello, los estudiantes de química deben ser conscientes desde el primer curso académico de su relevancia, así como conocer las normas principales y la forma de aplicarlas en el laboratorio. Por ello, las BPL se han incluido en la guía docente de la asignatura de Laboratorio de Química para las Ingenierías (1er curso académico) Además, los profesores deben centrarse en las BLP al impartir la docencia, para un correcto aprendizaje por parte de los estudiantes. Se requirió a los estudiantes que evaluasen el proceso de implantación y mostrasen su grado de aceptación de las BPL, mediante un cuestionario global de la asignatura. Como resultado final, se puede remarcar que los estudiantes comprendieron la utilidad de las BPL y la importancia de conocerlas para su futuro laboral, así como la necesidad de su inclusión en la guía docente de las asignatura de laboratorios de química

    An Innovative Project to Strengthen and Improve the Knowledge Acquisition in the Degree in Chemistry Using e-Learning Tools

    Get PDF
    Comunicació presentada a EDULEARN2018, 10th International Conference on Education and New Learning Technologies (July 2-4, 2018, Palma, Mallorca, Spain).The subject "Chemistry II (QU910)" is taught at first academic year (second semester) of the Degree in Chemistry at the University Jaume I. Some of its specific and general competencies are selflearning and writing and oral communication, regarding the main chemical concepts: chemical reactions, elements of the periodic table and calculations of the concentrations of the formed products and the remaining reagents in acid/base, complex, precipitation and redox reactions. We have noticed that 65% of the students have not studied any chemistry subjects (or only one) in High School or Professional Training before undertaking the Degree in Chemistry. The present project aims firstly to help these students to overcome their lack of background, secondly to compare the academic results of the students with and without previous contact with chemistry and finally, to establish actions to solve this prejudicial situation. This objective was reached by the implementation of a zero course, a course including the basic content of chemistry taught in the last years of High School, the month before the beginning of the first academic year. After the first year, students having attended chemistry before university obtained only 0.75/10 points more than the others. The Virtual Classroom, the emails and tutorial played an important role in the achievement of this zero-course

    Pentacene-Gate Dielectric Interface Modification with Silicon Nanoparticles for OTFTs

    Get PDF
    AbstractWe report on the properties of pentacene layers and OTFTs (Organic Thin Film Transistors) deposited on semiconductor-gate insulator interfaces covered with silicon nanoparticles (SiNPs) monolayer prepared by the Langmuir-Blodgett method compared to a reference sample (without SiNPs) prepared in an otherwise identical way. To analyse the structural quality, micro-Raman spectroscopy was employed and the correspondence between thin and bulk phase of the integral intensities peaks ratio (α) at 1154 and 1158cm-1 (α = Int1154 /Int1158) was evaluated. The AFM analysis of the pentacene layers reveals that the different surface treatment of SiO2 gate insulator (hydrophobic or hydrophilic) before SiNPs monolayer deposition has a distinct influence on the formation of different pentacene grain size and morphology. We demonstrate the higher time stability of pentacene OTFT and increasing of saturation current (∼ 2.5 ×) behavior after storage time if the semiconductor-gate insulator interface is modified using a SiNP monolayer

    Matéria orgânica do solo na integração lavoura-pecuária em Mato Grosso do Sul.

    Get PDF
    Nas condições ambientais da região centro-oeste do Brasil; o plantio direto (PD), aliado à rotação de culturas e pastagens, é apontado como a forma de manejo do solo mais adequada para conciliar produtividade com sustentabilidade. Os efeitos deste sistema de manejo sobre a dinâmica da matéria orgânica (MOS) e a agregação do solo foram estudadas a partir da avaliação de três experimentos de longa duração, localizados em Mato Grosso do Sul. As avaliações consistiram na determinação do teor e dos estoques de carbono orgânico total (COT) e de C nas frações da MOS, particulada (MOP) e associada aos minerais do solo (MOM). Foram determinados também a agregação do solo via peneiramento em água e a seco, o diâmetro médio ponderado 9MP) e o índice de estabiliade dos agregados (IEA).bitstream/item/38779/1/BP200529.pd

    Dynamic and volumetric variables reliably predict fluid responsiveness in a porcine model with pleural effusion

    Get PDF
    Background: The ability of stroke volume variation (SVV), pulse pressure variation (PPV) and global end-diastolic volume (GEDV) for prediction of fluid responsiveness in presence of pleural effusion is unknown. The aim of the present study was to challenge the ability of SVV, PPV and GEDV to predict fluid responsiveness in a porcine model with pleural effusions. Methods: Pigs were studied at baseline and after fluid loading with 8 ml kg−1 6% hydroxyethyl starch. After withdrawal of 8 ml kg−1 blood and induction of pleural effusion up to 50 ml kg−1 on either side, measurements at baseline and after fluid loading were repeated. Cardiac output, stroke volume, central venous pressure (CVP) and pulmonary occlusion pressure (PAOP) were obtained by pulmonary thermodilution, whereas GEDV was determined by transpulmonary thermodilution. SVV and PPV were monitored continuously by pulse contour analysis. Results: Pleural effusion was associated with significant changes in lung compliance, peak airway pressure and stroke volume in both responders and non-responders. At baseline, SVV, PPV and GEDV reliably predicted fluid responsiveness (area under the curve 0.85 (p<0.001), 0.88 (p<0.001), 0.77 (p = 0.007). After induction of pleural effusion the ability of SVV, PPV and GEDV to predict fluid responsiveness was well preserved and also PAOP was predictive. Threshold values for SVV and PPV increased in presence of pleural effusion. Conclusions: In this porcine model, bilateral pleural effusion did not affect the ability of SVV, PPV and GEDV to predict fluid responsiveness
    corecore