Los exámenes de Física en la enseñanza por transmisión y en la enseñanza por investigación

In this paper we show the results of a comparative ancilysis between ordinary tests of Physics and Chemistry and the ones used from a constructivist view. The study is focused in two aspects: firstly, it aims to show that the constructivist conception of leaming imposes considerable modifications in the tests content; secondly it highlights the deficiencies found in the tests designed after constructivist teaching. These deficiencies will just be solved by an investigation mainly aimed to assessment transformation

New guidelines for testing “Deep eutectic solvents” toxicity and their effects on the environment and living beings

Deep eutectic solvents (DESs) were described at the beginning of this century as an alternative to ionic liquids (ILs) in green chemistry. Despite their obvious sustainable advantages as reaction media, there is still controversy about their potential toxicity. Most of the ecotoxicity assays done up to now involving DESs are based on antibiograms. This is not a good approach due to the high density and viscosity of most DESs already described. Additionally, antibiograms do not allow continuous monitoring of neither cellular growth nor changes on physicochemical parameters like culture acidification due to cellular growth or DESs metabolization. This work starts by displaying advantages and disadvantages of the DESs toxicity assays already reported. Then, using a new DES recently described and Escherichia coli as a model microorganism, liquid cultures with continuous monitoring of pH, temperature, shaking and optical density have been used, for the first time, to quantify potential toxicity of the DES as well as the degree of the cellular tolerance (in preadapted and non-preadapted cells). The results obtained show that this new DES is not toxic for E. coli at concentrations up to 300 mM and cellular preadaptation was crucial for the cells to grow. At concentrations between 300 mM and 450 mM, cells can tolerate this DES. Above 600 mM, the DES is toxic causing complete inhibition of growth. This toxicity is not only due to the chemical composition of the DES, but also due to the high acidification of the media caused by the DES hydrolysis during cellular growth. The consequences of sterilization procedures on the DES stability are also analysed into detail, finding that sterilization by autoclave promotes DES hydrolysis. From these results, new guidelines are proposed for furthers studies aiming to characterize and quantify DESs toxicity.This work was supported by the University of Alicante (VIGROB-173 and VIGROB-309), the Spanish Ministerio de Economía, Industria y Competitividad (CTQ2015-66624-P, PGC2018-096616-B-I00 and RTI2018-099860-B-I00). X.M. and J.T. C. thank Generalitat Valenciana (ACIF/2016/057 and ACIF/2016/077) for their fellowships

Sensitivity of combustion noise and NOx and soot emissions to pilot injection in PCCI Diesel engines

Diesel engines are the most commonly used internal combustion engines nowadays, especially in European transportation. This preference is due to their low consumption and acceptable driveability and comfort. However, the main disadvantages of traditional direct injection Diesel engines are their high levels of noise, nitrogen oxides (NO x) and soot emissions, and the usage of fossil fuels. In order to tackle the problem of high emission levels, new combustion concepts have been recently developed. A good example is the premixed charge compression ignition (PCCI) combustion, a strategy in which early injections are used, causing a burning process in which more fuel is burned in premixed conditions, which affects combustion noise. The use of a pilot injection has become an effective tool for reducing combustion noise. The main objective of this paper is to analyze experimentally the pollutant emissions, combustion noise, and performance of a Diesel engine operating under PCCI combustion with the use of a pilot injection. In addition, a novel methodology, based on the decomposition of the in-cylinder pressure signal, was used for combustion noise analysis. The results show that while the PCCI combustion has potential to reduce significantly the NO x and soot emission levels, compared to conventional Diesel combustion strategy, combustion noise continues to be a critical issue for the implementation of this new combustion concept in passenger cars.This work has been partially supported by Ministerio de Educacin y Ciencia through Grant No. TRA2006-13782. L.F. Monico holds the Grant 2009/003 from Santiago Grisolia Program of Generalitat Valenciana.Torregrosa, AJ.; Broatch Jacobi, JA.; García Martínez, A.; Mónico Muñoz, LF. (2013). Sensitivity of combustion noise and NOx and soot emissions to pilot injection in PCCI Diesel engines. Applied Energy. 104:149-157. https://doi.org/10.1016/j.apenergy.2012.11.040S14915710

A non-linear quasi-3D model with Flux-Corrected-Transport for engine gas-exchange modelling

Modelling has proven to be an important tool in the design of manifolds and silencers for internal combustion engines. Although simple 1D models are generally sufficiently precise in the case of manifold models, they would usually fail to predict the high frequency behaviour of modern compact manifold designs and, of course, of a complex-shaped silencing system. Complete 3D models are able to account for transversal modes and other non-1D phenomena, but at a high computational cost. A suitable alternative is provided by time-domain non-linear quasi-3D models, whose computational cost is relatively low but still providing an accurate description of the high frequency behaviour of certain elements. In this paper, a quasi-3D model which makes use of a non-linear second order time and space discretization based on finite volumes is presented. As an alternative for avoiding overshoots at discontinuities, a Flux-Corrected Transport technique has been adapted to the quasi-3D method in order to achieve convergence and avoid numerical dispersion. It is shown that the combination of dissipation via damping together with the phoenical form of the anti-diffusion term provides satisfactory resultsTorregrosa, AJ.; Broatch Jacobi, JA.; Arnau Martínez, FJ.; Hernández-Marco, M. (2016). A non-linear quasi-3D model with Flux-Corrected-Transport for engine gas-exchange modelling. Journal of Computational and Applied Mathematics. 291:103-111. doi:10.1016/j.cam.2015.03.034S10311129

Phenomenological methodology for assessing the influence of flow conditions on the acoustic response of exhaust aftertreatment systems

[EN] The increasing limits of standards on aerosol and gaseous emissions from internal combustion engines have led to the progressive inclusion of different exhaust aftertreatment systems (EATS) as a part of the powertrain. Regulated emissions are generally abated making use of devices based on monolithic structures with different chemical functions. As a side effect, wave transmission across the device is affected and so is the boundary at the exhaust line inlet, so that the design of the latter is in turn affected. While some models are available for the prediction of these effects, the geometrical complexity of many devices makes still necessary in many cases to rely on experimental measurements, which cannot cover all the diversity of flow conditions under which these devices operate. To overcome this limitation, a phenomenological methodology is proposed in this work that allows for the sound extrapolation of experimental results to flow conditions different from those used in the measurements. The transfer matrix is obtained from tests in an impulse rig for different excitation amplitudes and mean flows. The experimental coefficients of the transmission matrix of the device are fitted to Fourier series. It allows treating the influence of the flow conditions on the acoustic response, which is manifested on changes in the characteristic periods, separately from the specific properties of every device. In order to provide predictive capabilities to the method, the Fourier series approach is coupled to a gas dynamics model able to account for the sensitivity of propagation velocity to variations in the flow conditions. (C) 2017 Elsevier Ltd. All rights reserved.This work has been partially supported by the Spanish Ministerio de Economia y Competitividad through Grant no. TRA2013-40853-R. Additionally, the Ph.D. student E.J. Sanchis has been funded by a grant from Universitat Politecnica de Valencia with reference FPI-2016-S2-1355. These supports are gratefully acknowledged by the authors. Finally, the authors wish also to acknowledge the suggestions of the referees, which have resulted in a considerable improvement of the text.Torregrosa, AJ.; Arnau Martínez, FJ.; Piqueras, P.; Sanchis-Pacheco, EJ.; Tartoussi, H. (2017). Phenomenological methodology for assessing the influence of flow conditions on the acoustic response of exhaust aftertreatment systems. Journal of Sound and Vibration. 396:289-306. https://doi.org/10.1016/j.jsv.2017.02.03328930639

Frecuencia del consumo de drogas legales: Diferencias de edad en la adolescencia

El consumo de drogas es especialmente relevante por sus efectos negativos sobre la salud psicofísica y el funcionamiento social de los jóvenes. El objetivo de este estudio fue analizar las diferencias de edad respecto a las frecuencias de consumo de alcohol y tabaco en una muestra de 354 escolares (50.85% varones) de 12 a 18 años (M = 14.66; DT = 1.08) que cumplimentaron el Questionnarie about Consume of Alcohol and Tobacco (TNT). Los resultados muestran que el 82.4% de los adolescentes ha consumido bebidas alcohólicas en alguna ocasión y el 25.6% es consumidor actualmente. Respecto al consumo de tabaco, el 40.4% de estudiantes afirma haber fumado en alguna ocasión, siendo consumidores actuales el 8.2%. Asimismo, se hallaron diferencias estadísticamente significativas entre la adolescencia temprana y tardía, observándose un aumento sustancial del consumo actual de ambas sustancias con la edad. Estos resultados resaltan la importancia de la variable edad a la hora de planificar medidas preventivas y de promoción de la salud en población adolescente

¿Qué hacer en la formación inicial del profesorado de ciencias de secundaria?

La publicación del acuerdo del Consejo de Ministros, por el que se regula el plan de estudios en España para la futura formación inicial del profesorado de secundaria (ved BOE de 21 y 29 de diciembre de 2007), abre nuevas expectativas en un campo hasta ahora muy descuidado, pero esencial para poder mejorar el proceso de enseñanza y aprendizaje en ese nivel educativo. En este trabajo, tras analizar diversos problemas del modelo de formación que se ha venido desarrollando hasta ahora, se consideran algunos criterios que deberían orientar la formación inicial del profesorado de física y química de educación secundaria y se proponen unos posibles contenidos a contemplar dentro del bloque específico del plan de estudios correspondiente.Palabras clave: Didáctica de las ciencias; formación inicial del profesorado de secundariaWhat to do in secondary school science teachers preservice training?During December 2007 regulations about training for secondary school teachers trainees, were introduced in Spain. This creates new expectations in a so far quite neglected field, but essential to improve the learning and teaching processes at this educational level. In this paper, we consider some criteria which should be applied to the initial training of science teachers and we also suggest likely contents.Keywords: Science education; secondary school teacher training

Conducta agresiva e inteligencia emocional en la adolescencia

Son escasos los estudios que analizan la relación entre conducta agresiva e inteligencia emocional. Este estudio examina la relación entre inteligencia emocional rasgo y los componentes motor (agresividad física y agresividad verbal), cognitivo (hostilidad) y afectivo/emocional (ira) de la conducta agresiva. El Trait Emotional Intelligence Questionnaire-Adolescents Short Form (TEIQue-ASF) y el Aggression Questionnaire Short version (AQ-S) fueron administrados a una muestra de 314 adolescentes (52.5% chicos) de 12 a 17 años. Los resultados indicaron que los adolescentes con altas puntuaciones en conducta agresiva física, verbal, hostilidad e ira presentaron puntuaciones significativamente más bajas en inteligencia emocional rasgo que sus iguales con puntuaciones bajas en conducta agresiva física, verbal, hostilidad e ira. Este patrón de resultados fue el mismo tanto para la muestra total como para chicos, chicas y los grupos de edad de 12-14 años y 15-17 años. Además, en la mayoría de los casos se hallaron tamaños del efecto grandes apoyando la relevancia empírica de estas diferencias.There are few studies examining the relationship between aggressive behavior and emotional intelligence. This study examines the relationship between trait emotional intelligence and behavioral (physical aggression and verbal aggression), cognitive (hostility) and affective/emotional (anger) components of aggressive behavior. The Trait Emotional Intelligence Questionnaire- Adolescents Short Form (TEIQue-ASF) and the Aggression Questionnaire Short (AQ-S) were administered to a sample of 314 adolescents (52.5% boys) aged 12 to 17 years. The results indicated that adolescents with high scores on physical and verbal aggression, hostility and anger showed significantly lower scores in trait emotional intelligence than their peers with low scores on physical and verbal aggression, hostility and anger. This pattern of results was the same for the total sample and for boys and girls and age groups of 12-14 years and 15-17 years. Furthermore, in most cases, large effect sizes were found supporting the empirical relevance of these differences

Exploring the molecular machinery of denitrification in Haloferax mediterranei through proteomics

Many proteins and enzymes involved in denitrification in haloarchaea can be inferred to be located between the cytoplasmic membrane and the S-layer, based on the presence of a Tat signal sequence and the orientation of the active site that some of these enzymes have. The membrane fraction of the haloarchaeon Haloferax mediterranei (R-4), grown under anaerobic conditions in the presence of nitrate, was solubilized to identify the respiratory proteins associated or anchored to it. Using Triton X-100, CHAPS, and n-Octyl-β-d-glucopyranoside at different concentrations we found the best conditions for isolating membrane proteins in micelles, in which enzymatic activity and stability were maintained. Then, they were subjected to purification using two chromatographic steps followed by the analysis of the eluents by NANO-ESI Chip-HPLC-MS/MS. The results showed that the four main enzymes of denitrification (nitrate, nitrite, nitric oxide, and nitrous oxide reductases) in H. mediterranei were identified and they were co-purified thanks to the micelles made with Triton X-100 (20% w/v for membrane solubilisation and 0.2% w/v in the buffers used during purification). In addition, several accessory proteins involved in electron transfer processes during anaerobic respiration as well as proteins supporting ATP synthesis, redox balancing and oxygen sensing were detected. This is the first characterization of anaerobic membrane proteome of haloarchaea under denitrifying conditions using liquid chromatography-mass spectrometry. It provides new information for a better understanding of the anaerobic respiration in haloarchaea