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Determination of polymer additive residues that migrate from coffee capsules by means of stir bar sorptive extraction-gas chromatography-mass spectrometry and PARAFAC decomposition
Get PDFThis paper reports on the difficulties encountered when developing an analytical method for ultra-trace determination, in a complex matrix, of plastic additive residues which are ubiquitous in the laboratory. The simultaneous qualitative and quantitative determination of an antioxidant (2,6-di-tert-butyl-4-methyl-phenol, BHT), an UV stabilizer (benzophenone, BP), and a plasticizer (diisobutyl phthalate, DiBP), released from plastic capsules is carried out in coffee by means of GC–MS and parallel factor analysis decomposition. Stir bar sorptive extraction is used to extract and concentrate the analytes. Coffee samples are prepared with Milli-Q water, which contains residues of the target compounds, which can be significant for ultra-trace analysis and should be subtracted. In addition, matrix effect exits in coffee, so standard addition method is used. The residue concentrations released from the coffee capsules into the solid coffee are around 3, 1, and 12 μg kg−1 of BHT, BP and DiBP, respectively.Spanish MINECO (AEI/FEDER, UE) through project CTQ2017-88894-R and by Consejería de la Junta de Castilla y León through project BU052P20 (both co-financed with European FEDER funds). L. Valverde-Som thanks JCyL for her postdoctoral contract through BU052P20 project
Experimental and molecular modeling study on the binary mixtures of [EMIM][BF4] and [EMIM][TFSI] ionic liquids
Get PDFThe properties of [EMIM][BF4] + [EMIM][TFSI] double salt ionic liquid (DSIL) were studied as a function of
mixtures composition and temperature. Experimental physicochemical properties combined with molecular
simulation (quantum chemistry and classical molecular dynamics) were considered, thus providing a
micro and macroscopic characterization of fluids’ structuring, intermolecular forces and molecular aggregation.
The results were analysed in thermodynamics terms considering deviations of ideality and mixing
properties as well as from the solvation and interaction between the involved ionic liquids by the developed
complex hydrogen bonding networks. Likewise, liquid [EMIM][BF4] + [EMIM][TFSI] interfaces
(x[EMIM][BF4] = x[EMIM][TFSI] = 0.5) were also studied using molecular dynamics methods to examine the diffusion
of [BF4]- and [TFSI]- anions in the [EMIM][BF4] + [EMIM][TFSI] liquid interface, and the mechanism
of interface crossing. The results allow a multiscale characterization of the considered ionic liquid mixtures
thus providing another way of designing IL-type solvents for specific applications, by choosing
not only the ion identity but also the ion ratio.Ministerio de Ciencia, Innovación y Universidades (Spain, project RTI2018-101987-B-I00) and by Junta de Castilla y León (Spain, project BU094G18). We acknowledge SCAYLE (Supercomputación Castilla y León, Spain) for providing supercomputing facilities
Multi-criteria feasibility of real use of self-compacting concrete with sustainable aggregate, binder and powder
Get PDFReplacing natural raw materials with industrial by-products can increase the sustainability of Self-Compacting Concrete (SCC), although its fresh and hardened behavior will usually worsen. The benefits of increased sustainability must therefore outweigh any reduction in concrete flowability and strength. These aspects can be analyzed through Multi-Criteria Decision-Making (MCDM) algorithms. In all, 19 SCC mixes were studied. One reproduced commercial SCC (limestone filler and conventional cement), the others were produced with more sustainable materials: 100% coarse Recycled Concrete Aggregate (RCA); 0%, 50% or 100% fine RCA; 45% Ground Granulated Blast-furnace Slag (GGBS); and sustainable aggregate powders such as limestone fines 0/0.5 mm and RCA powder 0/0.5 mm. Decreased flowability at 15 and at 60 min, compressive strength, modulus of elasticity, carbon footprint, and cost of mix were all studied. Both the carbon footprint and the cost were calculated considering only the composition of the SCC, without including aspects that depend on each particular case study, such as transport distances. These aspects constituted the decision-making criteria of the MCDM analysis, under which 14 scenarios were evaluated with different requirements for SCC, using 3 different algorithms (TOPSIS, AHP, and PROMETHEE). The results suggested that the ideal choice for fast concreting is a combination of GGBS, 100% coarse RCA and limestone fines, although if SCC has to be transported to the concreting point, then conventional cement should be used. Strength and stiffness can be maximized by limiting the fine RCA content to 50%. Finally, considering a versatile choice, only SCC with coarse RCA, limestone fines, GGBS and 0% fine RCA could compete with conventional SCC. Adapting the design to minimize the detrimental effects of by-products is therefore essential to promote sustainable SCC that is also commercially competitive.Spanish Ministry MCIU, AEI and ERDF [grant numbers PID 2020-113837RB-I00; 10.13039/501100011033; FPU17/03374]; the Junta de Castilla y León (Regional Government) and ERDF [grant number UIC-231, BU119P17]; Youth Employment Initiative (JCyL) and ESF [grant number UBU05B_1274]; and, finally, the University of Burgos [grant number SUCONS, Y135.GI]
Assessment of longitudinal and transversal plastic behavior of recycled aggregate self-compacting concrete: A two-way study
Get PDFPlastic strain behavior in the transversal direction to the axis of loading has often been underestimated in concrete design and its strength performance. However, as this article demonstrates, it is fundamental to define the viability of using concrete of a certain composition in real applications. In this study, 15 Self-Compacting Concrete (SCC) mixtures produced with Recycled Concrete Aggregate (RCA) and Ground Granulated Blast Furnace Slag (GGBFS) were subjected to a monotonic-load test and a 5-cycle loading/unloading test with increasing maximum loads. Continuous monitoring of the applied loads and the SCC strain was performed. In the transversal direction, these tests caused the appearance of a yield step, cracking by vertical splitting, and higher levels of deformability than in the longitudinal direction. It was concluded that the RCA content of SCC should be defined according to serviceability conditions when used in compressed elements, to safeguard against failure due to transversal plastic strain.Spanish Ministry MCIU, AEI and ERDF [grant numbers FPU17/03374 and RTI2018-097079-B-C31; 10.13039/501100011033]; the Junta de Castilla y León (Regional Government) and ERDF [grant number UIC-231, BU119P17]; Youth Employment Initiative (JCyL) and ESF [grant number UBU05B_1274]; the University of Burgos [grant number SUCONS, Y135.GI], UPV/EHU (PPGA20/26) and, finally, our thanks also to the Basque Government research group IT1314-19
Solving the generalized multi-port container stowage planning problem by a matheuristic algorithm
Get PDFWe focus on a simplified container stowage planning problem where containers of different size and weight must be loaded and unloaded at multiple ports while maintaining the stability of the ship. We initially investigate how the difficulty in solving the problem changes with and without the consideration of container sizes and weight constraints. For this purpose, we provide integer programming formulations for the general problem as well as some special cases with identical container size and/or identical weights and evaluate their performance in randomly generated small- and medium-scale instances. We develop a matheuristic procedure, namely, an insert-and-fix heuristic, exploiting the special structure of the proposed formulations. The Insert-and-Fix method, in combination with a constructive algorithm that gives the solver an initial solution in each iteration, provides solutions with a low number of rehandles for instances with up to 5000 TEUs.Spanish Ministry of Science, Innovation, and Universities, FPU Grant A-2015-12849 and under the project “OPTEP-Port Terminal Operations Optimization” (No. RTI2018-094940-B-I00) financed with FEDER, Spain funds. The second author acknowledges the partial support by Data-driven logistics, Spain (FWO-S007318N) and Internal Funds KU Leuven, Spain
Fiber-reinforcement and its effects on the mechanical properties of high-workability concretes manufactured with slag as aggregate and binder
Get PDFThe feasibility of manufacturing fiber-reinforced concretes of high workability through additions of high volumes of electric arc furnace steel slag is evaluated in this paper, using sustainable binders with ground granulated blast furnace slag and ladle furnace slag as a supplementary cementitious material. An extensive experimental plan is developed to test four (self-compacting and pumpable) concrete mixtures, some reinforced with 0.5% vol. of (metallic or synthetic) fibers, in both the fresh and the hardened state. Very specific mechanical aspects are examined, such as the evaluation of both longitudinal and transversal stress-strain compressive behavior, and the assessment of direct tensile strength through the “dog-bone” test. The results of testing this sustainable concrete design yielded suitable mechanical strengths, and good toughness, ductility and impact strength, among other properties. Good adhesion between the fibers and the cementitious matrix was also evident from the fiber pull-out test results. Finally, the overall results confirmed that the use of electric arc furnace steel slag can make a real contribution to construction-sector sustainability and that the mechanical behavior of these novel concretes meets the basic design requirements for use in real structures.Spanish Ministries MCI, AEI, EU and ERDF [RTI2018-097079-B-C31; 10.13039/501100011033; FPU17/03374]; the Junta de Castilla y León (Regional Government) and ERDF [UIC-231, BU119P17]; the Basque Government research group [IT1314-19]; Youth Employment Initiative (JCyL) and ESF [UBU05B_1274]; the University of Burgos [Y135.GI] and the University of the Basque Country [PPGA20/26]. Likewise, our thanks to CHRYSO and HORMOR for supplying the materials used in this research
Modelling Photosynthetic Active Radiation (PAR) through meteorological indices under all sky conditions
Get PDFIn this study, ten-minute meteorological data-sets recorded at Burgos, Spain, are used to develop models of Photosynthetic Active Radiation () following two different procedures: multilinear regression and Artificial Neural Networks. Ten Meteorological Indices (MIs) are chosen as inputs to the models: clearness index (), diffuse fraction (), direct fraction (), Perez's clear sky index (ɛ), brightness index (), cloud cover (), air temperature (), pressure (), solar azimuth cosine (), and horizontal global irradiation (). The experimental data are clustered according to the sky conditions, following the CIE standard sky classification. A previous feature selection procedure established the most adequate MIs for modelling in clear, partial and overcast sky conditions. was the common MI used by all models and for all sky conditions. Additional variables were also included: the geometrical parameter, , and three variables related to the sky conditions, , and Both modelling methods, multilinear regression and ANN, yielded very high determination coefficients () with very close results in the models for each of the different sky conditions. Slight improvements can be observed in the ANN models. The results underline the equivalence of multilinear regression models and ANN models of PAR following previous feature selection procedures.Regional Government of Castilla y León, under projects BU021G19 and INVESTUN/19/BU/0004 and the Spanish Ministry of Science & Innovation under the I+D +i state program “Challenges Research Projects” (Ref. RTI2018-098900-B-I00). Diego Granados López expresses his thanks to the Junta de Castilla y León for economic support (PIRTU Program, ORDEN EDU/556/2019)
Оценка виртуализированной экологии саморегулируемого обучения для дидактики естественных наук во время кризиса COVID-19
Get PDFLos modelos de enseñanza-aprendizaje universitarios están siendo afectados por la crisis
originada por la COVID-19. Para atender a esta crisis desencadenada se diseñó de urgencia
una propuesta de ecología de aprendizaje autorregulado virtualizada durante el confinamiento
de 2020 en la asignatura de Ciencias de la Naturaleza y su Didáctica I del Grado en
Maestro de Educación Primaria. En este artículo se describe esta ecología de aprendizaje:
los materiales elaborados, los contextos diseñados y la utilización de estrategias de enseñanza-
aprendizaje basadas en el aprendizaje autorregulado, tanto durante la docencia
virtual como durante la tutorización del alumnado. El objetivo de este estudio es analizar
la ecología de aprendizaje autorregulado a través de la apreciación del alumnado con respecto
a su motivación hacia la asignatura, su opinión sobre la calidad de los materiales y
sobre la evaluación, la percepción del alumnado de la motivación del profesorado hacia la
asignatura y respecto a la carga de trabajo de la asignatura, así como la satisfacción general
de la labor docente. La información se recabó utilizando el Cuestionario de opinión del
alumnado sobre la calidad de la docencia realizado por la Universidad de Burgos. Todos
los ítems fueron bien valorados, por lo que la experiencia puede sentar las bases para la
implementación de ecologías de aprendizaje que puedan extrapolarse a otras titulaciones
universitarias y contextos diferentes al aquí implementado.University teaching-learning models are being affected by the crisis caused by COVID-19.
To address this unleashed crisis, a virtualized self-regulated learning ecology proposal was
urgently designed in the subject of Natural Sciences and its Didactics I, of the Degree in
Primary Education Teacher, during the confinement of 2020. In this article it is described
this learning ecology: the materials produced, the designed environments and the use of
teaching-learning strategies based on self-regulated learning, both in virtual teaching and
in student tutoring. The objective of this study is to analyze the ecology of self-regulated
learning through the students’ appreciation regarding their motivation towards the subject,
their opinion on the quality of the materials and on the evaluation, the students’ perception
of the teacher’s motivation towards the subject and with respect to the workload of
the subject, as well as the general satisfaction of the teaching work. The information was
collected using the Student Opinion Questionnaire on the quality of teaching carried out
by the University of Burgos. All the items were well valued, so the experience can lay the
foundations for the implementation of learning ecologies that can be extrapolated to other
university degrees and contexts other than the one implemented here.大学教学模式正在遭受新冠疫情危机的影响。为了解决这一危机，在 2020 年的隔离期间，
我们紧急设计了一项虚拟化的自我调节学习生态提案，其针对对象为小学师范本科学位
关于自然科学教学法 I的课程。本文描述了该学习生态：在进行虚拟教学和对学生辅导期
间所制作的材料、设计的环境以及对基于自我调节学习的教学策略的使用。本研究的目的
是通过学生对学习动机的评价、对教材质量和评估的看法以及学生对老师教学动机的看
法和其在该科目上的工作量和总体满意度来分析自主学习的生态。这些信息是通过对布尔戈斯大学教学质量的学生意见问卷收集的。所有项目都得到了很好的评价，因此该经验
可以为学习生态的实施奠定基础，并将其推行至其他大学学位和不同环境中。Университетские модели преподавания-обучения испытывают влияние кризиса,
вызванного COVID-19. Для преодоления этого кризиса, предложение по виртуализи-
рованной саморегулируемой экологии обучения было срочно разработано во время
заключения 2020 года по предмету «Естественные науки и их дидактика I степени в
начальном образовании». В данной статье описывается эта экология обучения: раз-
работанные материалы, созданные контексты и использование стратегий преподава-
ния-обучения, основанных на саморегулируемом обучении, как во время виртуаль-
ного обучения, так и во время репетиторства студентов. Цель данного исследования
- проанализировать экологию саморегулируемого обучения через оценку студентами
своей мотивации к предмету, их мнение о качестве материалов и об оценке, воспри-
ятие студентами мотивации преподавателей к предмету и в отношении нагрузки по
предмету, а также общую удовлетворенность преподавательской работой. Инфор-
мация была собрана с помощью Анкеты мнения студентов о качестве преподавания
в Университете Бургоса. Все предметы получили хорошие оценки, поэтому данный
опыт может заложить основы для внедрения экологий обучения, которые можно экс-
траполировать на другие университетские степени и контексты, отличные от реали-
зованного здесь.Proyecto de innovación de código UV-SFPIE_PID20-1350001 concedido por el Vicerectorat d’Ocupació i Programes Formatius i el Servei de Formació Permanent i Innovació Educativa de la Universitat de ValènciaInnovation project UV-SFPIE_ PID20-1350001 granted by the Office of the Deputy Vice-Chancellor of Employment and Training Programmes and the Permanent Training and Educational Innovation Service of the University of Valencia
El uso de los videojuegos como ocio digital en personas con trastorno del espectro del autismo
Get PDFDigital leisure and specifically videogames are increasingly entrenched in all segments of society. Making appropriate use of them implies a challenge for users, families, and professionals. In the present study, the use that people with Autism Spectrum Disorders make of this sort of entertainment is specifically approached, and a series of recommendations are presented that take the characteristics of this population into account. A questionnaire was prepared ad hoc for data-collection purposes and administered to 67 people with ASD of different ages. The results reflect that videogames are a very popular type of game among people with ASD, are perceived as highly attractive and motivating and can help to lower anxiety levels. Among the undesired aspects, the physical problems arising from the use of videogames may be highlighted, and the problems of addiction and isolation that their continual use can provoke. The widespread acceptance of this type of leisure among people with ASD calls for new studies of a qualitative nature for the analysis of the relevant variables.El ocio digital, y en concreto los videojuegos, están cada vez más afianzados en todos los segmentos de la sociedad. Hacer un uso adecuado de ellos implica un desafío para los usuarios, familias y profesionales. En el presente estudio se aborda de manera específica el uso que las personas con Trastornos del Espectro Autista hacen de este tipo de entretenimiento y se presentan una serie de recomendaciones que toman en cuenta las características de esta población. Para ello, se elaboró un cuestionario ad hoc y se administró a 67 personas con TEA de diferentes edades. Los resultados reflejan que los videojuegos son un tipo de juego muy popular entre las personas con TEA, se perciben como muy atractivos y motivadores y pueden ayudar a reducir los niveles de ansiedad. Entre los aspectos no deseados, se pueden destacar los problemas físicos derivados del uso de videojuegos y los problemas de adicción y aislamiento que puede provocar su uso continuado. La amplia aceptación de este tipo de ocio entre las personas con TEA exige nuevos estudios de carácter cualitativo para el análisis de las variables relevantes