Distintas narrativas para un mismo contenido : la tabla periódica en los libros de texto

Se analizan las ‘narrativas’ implícitas en una muestra amplia de libros de texto para establecer una tipologia que tiene implicaciones en la selección de los contenidos de los temas que se tratan en el libro. Se ha centrado el estudio en la Tabla periódica de los elementos, siguiendo las investigaciones de Linares (2004) y Izquierdo y Adúriz (2007). Los resultados del análisis que se ha realizado en una muestra amplia de libros de texto a partir de los años cincuenta muestran que la manera de presentar a la Tabla Periódica en el libro intenta ser coherente con el enfoque global de la química en él. Ahora bien, se detectan incoherencias que nos llevan a proponer un foro de discusión sobre el diseño de los contenidos de química a la luz de las propuestas didácticas actuales y sobre la función actual de los libros de texto en la enseñanza de la Química

Enhanced recovery after surgery pathways in thoracic surgery, do they end at discharge?

Fast track pulmonary resection protocols have shown to be feasible and to improve hospital related costs, shortening length of stay and maintaining quality of care (1-4). Despite the increasing number of scientific literature addressing the benefits of specific lobectomy pathways (4,5) and the recent publication of Enhanced Recovery after Surgery (ERAS®) guidelines in thoracic surgery (4-6) the truth is that the description of most of these interventions ends at patients’ discharge, with no clear indications for follow up or measures to prevent unintended hospital readmissions (2,3

Analysis of elastic nonlinearity for impact damage detection in composite laminates

This paper concerns the experimental analysis of nonlinear response features of a composite laminate plate for impact damage detection. The measurement procedure is based on the Scaling Subtraction Method (SSM) and consists in exciting the damaged specimen with two sinusoidal signals at different amplitude. The linearly rescaled response signal at low amplitude excitation is subtracted from the response at large amplitude excitation to extract the nonlinear signatures. The latter are analysed in the time domain to infer the presence of damage. Results are compared with frequency domain analyses using the nonlinear vibro-acoustic modulation technique (NWMS). Changes in amplitude and phase as well as modulation effects of the acquired responses are also monitored. Surface-bonded, low profile piezoceramic transducers are used for excitation and sensing. Both measurements techniques are applied to detect barely visible impact damage in laminate composite plate. Non-destructive penetrant-enhanced X-ray inspections are carried out to characterize the extent of internal damage. The behavior of the nonlinear features and the sensitivity of each technique are also investigated in the paper

Antimicrobial potential of Ericaria selaginoides extracts against Listeria monocytogenes in “mató”, a Catalan fresh cheese

The objective of this work was to assess the antimicrobial effect of crude extracts and non-polar and mid-polar subfractions of the brown macroalga Ericaria selaginoides, using a mid-polarity extraction medium. The activity was evaluated through challenge testing against Listeria monocytogenes in Catalan “mató” (fresh cheese) selected as a food matrix. Three concentrations were tested, representing 2 ×, 4 × and 10 × Minimum Bactericidal Concentration values obtained for crude extract in previous in vitro assays. Ericaria selaginoides extracts inhibited L. monocytogenes growth in a dose-dependent manner. Intermediate concentrations of the three extracts were able to notably reduce the growth rate of the pathogen. Highest concentration of crude extract and non-polar subfraction were able to completely inhibit the growth of L. monocytogenes during the 10 days of storage at 8 °C. Moreover, a slight listericidal effect was observed in presence of the non-polar subfraction, reducing the L. monocytogenes level by ca. 3 log after 10 days of refrigerated storage. These results prove the potential of E. selaginoides extracts as a source of valuable antimicrobial compounds that can be used as natural food ingredients to develop safer fresh dairy food.info:eu-repo/semantics/publishedVersio

Effective GDNF brain delivery using microspheres-A promising strategy for Parkinson's disease

Glial cell line-derived neurotrophic factor (GDNF) has shown promise in the treatment of neurodegenerative disorders of basal ganglia origin such us Parkinson\u27s disease (PD). In this study, we investigated the neurorestorative effect of controlled GDNF delivery using biodegradable microspheres in an animal model with partial dopaminergic lesion. Microspheres were loaded with N-glycosylated recombinant GDNF and prepared using the Total Recirculation One-Machine System (TROMS). GDNF-loaded microparticles were unilaterally injected into the rat striatum by stereotaxic surgery two weeks after a unilateral partial 6-OHDA nigrostriatal lesion. Animals were tested for amphetamine-induced rotational asymmetry at different times and were sacrificed two months after microsphere implantation for immunohistochemical analysis. The putative presence of serum IgG antibodies against rat glycosylated GDNF was analyzed for addressing safety issues. The results demonstrated that GDNF-loaded microspheres, improved the rotational behavior induced by amphetamine of the GDNF-treated animals together with an increase in the density of TH positive fibers at the striatal level. The developed GDNF-loaded microparticles proved to be suitable to release biologically active GDNF over up to 5 weeks in vivo. Furthermore, none of the animals developed antibodies against GDNF demonstrating the safety of glycosylated GDNF use

Los modelos en la enseñanza de la Química

‘Modelo’ es un término polisémico que debemos precisar debido a la importancia que tiene actualmente para la enseñanza de las ciencias. Apela al pensamiento abstracto y a su relación con lo que llamamos ‘realidad’. En la medida que se comprende que también los fenómenos y las evidencias dependen del marco teórico (de las preguntas con sentido que se pueden llegar a formular sobre ellos por quienes saber cómo intervenir en ellos y transformarlos) aparece la necesidad de establecer cuál puede ser el fundamento epistemológico de la ciencia que se hace en la escuela. Presentamos nuevos desarrollos del MCQ que ha sido presentado en otras ocasiones y que estamos aplicando a la enseñanza de la química a maestros (en formación inicial y en formación permanente)

Soda-lime glass as biocompatible material to fabricate capillary-model devices by laser technologies

Microfluidic devices have been widely developed in the last decades because of the huge number of fields where they can be applied. Among all the different fabrication techniques available, laser direct writing stands out since it is a fast, accurate, versatile and non-contact method. It is particularly well-suited when working with glass, a robust and cost-efficient material. These laser advantages allow the direct fabrication of not only high quality single microchannel devices but also complex and bifurcated structures. This work establishes a roadmap for manufacturing capillary-model devices with good biocompability in soda-lime glass substrates with pulsed lasers operating in the nanosecond, picosecond and femtosecond temporal range. We determine the optimal laser parameters required for fabricating channels with a diameter:depth rate of 2:1, keeping a semi-circular section. The presence of tin doping (∼2%) in the soda-lime glass is shown to enable the fabrication with nanosecond pulses, and to improve the quality of the channels, reducing the cracking at the sides, when picosecond or femtosecond pulses were used. On the other hand, two regimes of surface roughness are found: a low roughness regime for channels fabricated with nanosecond lasers and a high roughness regime for those fabricated with pico and femtosecond lasers. Human umbilical vein endothelial cells (HUVEC) are employed for cell culturing for evaluating the biocompatibility of the channels. Structures manufactured with the nanosecond laser resulted more suitable in terms of cell adhesion than those fabricated with the picosecond and femtosecond lasers, due to the different surface roughness regimes obtained. In order to increase the biocompatibility of the channels fabricated with pico and femtosecond lasers and to improve the cell growth, a controlled post-thermal treatment is carried out for smoothing the surface