Moving loads on railway bridges: The Spanish Code approach

This paper presents the results of part of the research carried out by a committee in charge of the elaboration of the new Spanish Code of Actions in Railway Bridges. Following the work developed by the European Rail Research Institute (ERRI), the dynamic effects caused by the Spanish high-speed train TALGO have been studied and compared with other European trains. A simplified envelope of the impact coefficient is also presented. Finally, the train-bridge interactions has been analysed and the results compared with those obtained from simple models based on moving loads

Scaling of the elastic contribution to the surface free energy of a nematic on a sawtoothed substrate

We characterize the elastic contribution to the surface free energy of a nematic in presence of a sawtooth substrate. Our findings are based on numerical minimization of the Landau-de Gennes model and analytical calculations on the Frank-Oseen theory. The nucleation of disclination lines (characterized by non-half-integer winding numbers) in the wedges and apexes of the substrate induces a leading order proportional to qlnq to the elastic contribution to the surface free energy density, q being the wavenumber associated with the substrate periodicity.Comment: 7 pages, 6 figures, accepted for publication in Physical Review

Scoping assessment of free-field vibrations due to railway traffic

The number of railway lines both operational and under construction is growing rapidly, leading to an increase in the number of buildings adversely affected by ground-borne vibration (e.g. shaking and indoor noise). Post-construction mitigation measures are expensive, thus driving the need for early stage prediction, during project planning/development phases. To achieve this, scoping models (i.e. desktop studies) are used to assess long stretches of track quickly, in absence of detailed design information. This paper presents a new, highly customisable scoping model, which can analyse the effect of detailed changes to train, track and soil on ground vibration levels. The methodology considers soil stiffness and the combination of both the dynamic and static forces generated due to train passage. It has low computational cost and can predict free-field vibration levels in accordance with the most common international standards. The model uses the direct stiffness method to compute the soil Green's function, and a novel two-and-a-half dimensional (2.5D) finite element strategy for train-track interaction. The soil Green's function is modulated using a neural network (NN) procedure to remove the need for the time consuming computation of track-soil coupling. This modulation factor combined with the new train-track approach results in a large reduction in computational time. The proposed model is validated by comparing track receptance, free-field mobility and soil vibration with both field experiments and a more comprehensive 2.5D combined finite element-boundary element (FEM-BEM) model. A sensitivity analysis is undertaken and it is shown that track type, soil properties and train speed have a dominant effect on ground vibration levels. Finally, the possibility of using average shear wave velocity introduced for seismic site response analysis to predict vibration levels is investigated and shown to be reasonable for certain smooth stratigraphy's.Ministerio de Economía y Competitividad - BIA2016-75042-C2-1-

Quinoline-based hydrazone derivative as a biocide chemosensor: synthesis and sensing studies

Tributyltin (TBT) is an organic biocide used on antifouling paints to avoid biofouling on boats and submersed structures. It is toxic to a variety of aquatic organisms and was banned by the Rotterdam Convention in 1998. TBT sensing is an important issue as the biocide is still affecting aquatic environments as some countries did not sign the convention and are still using it. Currently, TBT monitoring methods are based on sampling and laboratory analysis, which is expensive, time-consuming, and require expert users. Therefore, a new simple and fast TBT sensing method would be of high interest. In this work, a new quinoline-based hydrazone derivative was synthesized by a condensation reaction in 67% yield. The new compound was characterized by the usual spectroscopic and spectrometric techniques. The preliminary chemosensory study of the hydrazone derivative in the presence of TBT in acetonitrile solution resulted in a color change from colorless to red together with the appearance of fluorescence. This interaction was confirmed by spectrophotometric and spectrofluorimetric titrations, which revealed that 17 equivalents of TBT led to the maximum optical signal in terms of fluorescence intensity and absorbance.This research was funded by Fundação para a Ciência e Tecnologia (FCT) and FEDER (European Fund for Regional Development)-COMPETE-QRENEU through the Chemistry Research Centre of the University of Minho (Ref. CQ/UM UID/QUI/00686/2020) as well as a PhD grant to R. P. C. L. Sousa (SFRH/BD/145639/2019)

Flexible Laser-Reduced Graphene Oxide Thermistor for Ubiquitous Electronics

This work presents a versatile sensing platform, intended for ubiquitous and flexible electronics based on a laser reduced-Graphene-Oxide thermistor. This technique enables the fast and ecological production of reduced Graphene Oxide without the need of masks or expensive lithography processes. The final transducer is fabricated on a flexible plastic substrate in order to use it as a superficial patch. Finally, a full demonstrator, which integrates this flexible thermistor with a low power System on Chip with wireless transmission, is presented.This work has been partially supported by the Spanish Ministry of Education, Culture and Sport (MECD) through the pre-doctoral grant FPU16/01451 , the National Excellence Research Project TEC2017-89955-P and the University of Granada through the scholarship ”Initiation to Research

Development of the Checklist of Psychomotor Activities for 5- to 6-Year-Old Children

The present research aimed to develop the Checklist of Psychomotor Activities (CPA) to measure psychomotor development in 5-6 year old children. We recruited 694 preschool children in the province of Albacete; their teachers were trained to use and complete this instrument to gather data for testing its psychometric properties (reliability, and content, construct, and discriminant validity). The CPA is composed of three subtests measuring children's performance in motor, perceptual, and emotional-social aspects of psychomotor functioning. To gather evidence of content validity, we applied the Delphi method, based on the comments of seven judges. We assessed construct validity with confirmatory factor analysis, and we tested discriminant validity by comparing the scores of premature and typically developing children and separate groups of children defined by their body mass index. We found adequate item consistency on each scale and evidence of validity from the various methods outlined. We conclude that the CPA is an effective and comprehensive tool for the assessment of psychomotor skills in children at this important stage of development.2018-1

Aritmética en coma flotante y programación en ensamblador en las prácticas de Estructura de Computadores: Control de un simulador de radar

La enseñanza del lenguaje ensamblador es complicada debido a la dificultad que supone a los alumnos enfrentarse a un lenguaje de bajo nivel. La experiencia nos dice que plantear unas prácticas atractivas al alumno les hace interesarse por dicho lenguaje y por la asignatura de Estructura de los Computadores I (en la que se estudia, en la Universidad de Granada). La programación de un control de radar puede ser una práctica atractiva a los alumnos, de forma que la programación en ensamblador resulte casi un juego conforme mejoran la programación del cálculo de las coordenadas

Effects of culture media and physical factors on the mycelial growth of the three wild strains of Volvariella volvacea from Ecuador

Volvariella volvacea is an edible and nutraceutical tropical mushroom species. This study reports the optimal culture conditions for efficient growth of mycelia of the three wild strains of V. volvacea (La Clementina, Vinces, and Montalvo) from Ecuador. The mycelial growths were evaluated on the three culture media, pH, aeration, illumination, and temperature. Mycelia of the three strains grew best on Sabouraud dextrose agar at pH 6.5–7.5 when incubated in either sealed and unsealed conditions at 26–28°C and 32°C. Vinces and Montalvo strains favored dark and lighted conditions, respectively, whereas La Clementina favored both. Therefore, the three exotic strains of V. volvacea could be commercially cultivated in the Philippines and utilized in various applications

MODIFICACIÓN DE UN CONFLICTO SEMIÓTICO EN UN AMBIENTE DE TRABAJO COLABORATIVO

En este escrito se presenta un análisis de la actividad matemática realizada por dos estudiantesen un curso de Didáctica de la Variación del programa de Licenciatura en Educación Básicacon Énfasis en Matemáticas de la Universidad Distrital Francisco José de caldas- Bogotá,para describir y analizar el uso del registro algebraico alfanumérico al resolver un problema demodelación relacionado con la función lineal cuando participaron en un entorno deaprendizaje que promueve el trabajo colaborativo. El análisis reporta evidencia de la presenciade conflictos semióticos y de la modificación de un conflicto interaccional en un conflictocognitivo. Este análisis permite caracterizar la emergencia de los conflictos semióticos y cómoson manejados por las estudiantes, aportando información útil para comprender los procesosde aprendizaje de los estudiantes para profesor de matemáticas, en un contexto de aula en elque se adopta la resolución de problemas.Palabras clave: registro algebraico, conflicto semiótico, trabajo colaborativo.MODIFICATION OF CONFLICT SEMIOTICIN A COLLABORATIVE WORK ENVIRONMENTAbstractThis paper presents an analysis of mathematical activity developed by two students in a courseon Didactic of Variation which belongs to the Program of Teachers Formation in BasicEducation with Emphasis in Mathematics from the Universidad Distrital Francisco José deCaldas, Bogotá. It describes and analyzes the use that those students did about alphanumericalgebraic register to solve a modeling problem related to the linear function when they wereinvolved in a learning environment that promotes collaborative work. The analysis evidencethe presence of semiotic conflicts and the change from interactional conflict into a cognitiveconflict. This analysis allows characterizing the semiotic conflicts emergence and how theyare handled by the students, providing useful information for understanding the learningprocesses of students trying to become a mathematics teacher in a classroom context in whichthe solving of problems is adopted

Superhydrophobic Cerium-Based Coatings on Al-Mg Alloys and Aluminized Steel

Aluminum-magnesium (Al-Mg) alloy and aluminum-coated steel (aluminized steel) are typically used for the manufacturing of baking trays and molds. For these applications, these materials must be modified to develop release and hydrophobic properties. With this aim, the bare substrates are typically coated with low-surface energy materials such as fluoropolymers, elastomers, or sol-gel layers. In this work, some alternative strategies to prepare these functional surfaces are presented. We used three-step processes involving (i) micro-texturing, (ii) nano layer deposition through immersion and electrodeposition, and (iii) hydrophobization. The raw substrates were sanded or sandblasted at the micro scale, accordingly. Texturization at the nano scale was achieved with a cerium layer formed by electrodeposition or solution immersion. The cerium layers were hydrophobized with fatty acids. The wetting properties of the samples were studied with tilting-plate and bouncing drop methods. We measured the surface roughness of the samples by contact profiling and analyzed their surface morphology using a field emission scanning electron microscope (FESEM). The elemental chemical composition of the samples was analyzed by energy-dispersive X-ray spectroscopy (EDX). The wettability results indicated that the best performance for the Al-Mg substrates was reached by sandblasting and later immersion in a cerium nitrate solution. For aluminized steel substrates, the best results were obtained with both electrodeposition and immersion methods using a cerium chloride solution