Agricultural practices and geostatistical evaluation of nitrate pollution of groundwater in the Júcar River Basin District, Spain

[EN] Groundwater pollution by nitrates induced by intensive agriculture and overexploitation of water in the Júcar River Basin District is a major concern. This work is a contribution to understanding the spatial and temporal distribution of nitrates in groundwater and the possible relationships between the presence of nitrates and contextual variables, such as rainfall, seepage and lithology. A space-time table of groundwater measurements of nitrate levels between 1969 and 2012 (41 hydrological years) in 6381 monitoring locations is used. First, a statistical analysis was performed to find correlations between nitrate concentrations and the contextual variables of yearly rainfall and recharge amounts evaluated by the PATRICAL model. A geostatistical simulation approach was then used to build a space-time model of nitrate concentrations, including calculation of experimental variograms and fitting of a theoretical model. The results of the variograms were used to infer the maximum spatial correlation distance and the maximum time range of temporal correlation for the same location. Sequential Gaussian simulation was selected instead of kriging for the purpose of declustering of data locations. Finally, yearly maps of average nitrate concentrations were generated. The results show that nitrate concentrations have increased steadily from the early 1970s and have stabilized since 2005. Contamination by nitrates occurs predominantly in agricultural areas, such as the plateau of La Mancha and the coastal plain.This work is a contribution to Project UID/GEO/04035/2013 funded by Fundacao para a Ciencia e a Tecnologia (FCT), Portugal.Ferreira, D.; Almeida, JA.; Simões, M.; Pérez-Martín, MÁ. (2016). Agricultural practices and geostatistical evaluation of nitrate pollution of groundwater in the Júcar River Basin District, Spain. Emirates Journal of Food and Agriculture. 28(6):415-424. doi:10.9755/ejfa.2016-04-346S41542428

Synthesis, crystal structure and magnetic properties of an alternating manganese chain

A new 1D complex has been prepared and characterized. X-ray single crystal structure confirms that the Mn(II) ions assemble in alternating chains with Mn-Mn distances of 3.8432(13) and 4.4428(14) Å. A 3D network of hydrogen bonds links the chains together. The temperature dependence of the magnetic susceptibility reveals that this compound undergoes a magnetic transition and exhibits an antiferromagnetic interaction in the low-temperature phase with two alternating exchange interactions of -2.32(1) and -5.55(1) cm-1.http://www.sciencedirect.com/science/article/B6WM2-4JKC5PW-3/1/57fbdb3ac410627d046c6e4fdf2f0e3

Semiotic conflicts related to two-dimensional data organisation in High School textbooks

El objetivo de este trabajo es caracterizar los conflictos semióticos relacionados con la organización de datos bidimensionales que se presentan en los libros de texto de Bachillerato en España. Se analizan 16 libros de texto, según el Enfoque ontosemiótico del conocimiento y la instrucción matemáticos, donde encontramos una amplia variedad de conflictos, relacionados principalmente con el lenguaje, así como en la definición de conceptos o presentación de procedimientos. Estos resultados ayudarán al docente en el diseño, planificación e implementación del tema, y poder evitar que dichos conflictos se manifiesten en sus estudiantes.The aim of this work is to characterize the semiotic conflicts related to organizing two-dimensional data that arise in the Spanish High School textbooks. An analysis in a sample of 16 textbooks is carried out, based on the onto-semiotic approach of mathematical knowledge and instruction in mathematics education. We found a wide variety of conflicts that mainly concern the language used, as well as the definition of concepts and presentation of methods. These results will assist the teacher in the design, planning and implementation of this topic, in order to avoid that such conflicts are transmitted to the student.Proyecto EDU2013-41141-P y EDU2016-74848-P (MEC) y grupo FQM126 (Junta de Andalucía).info:eu-repo/semantics/publishedVersio

REFLEXIONES EN TORNO A LA INVESTIGACIÓN CON MÉTODOS MIXTOS

Objetivo: Se presenta una reflexión teórica basada en la experiencia de los autores como investigadores y docentes de unidades curriculares de Metodologías de Investigación. Método: reflexión teórica-filosófica. Resultados: la dicotomía entre los enfoques cualitativos y cuantitativos dio lugar a la discusión sobre la necesidad de pensar en la posibilidad de combinar estos métodos con el objetivo de responder a los nuevos y complejos problemas de investigación con los que actualmente nos enfrentamos. Esta discusión se transformó en una disputa que algunos autores apodaron “Science War”, debido a los desafíos metodológicos y epistemológicos de esta combinación que, por su vez, dio origen a los Métodos Mixtos (Mixed Methods). La reflexión que se propone se centra en algunas de las principales cuestiones que surgen en el ámbito de las actuales discusiones entre investigadores y reflejan/ traducen algunas de las inquietudes de los mismos.Descritores: Métodos Mixtos. Metodologías de Investigación. Investigación cualitativa y cuantitativa

Percepción de Blended Learning en profesores universitarios de distintos ámbitos disciplinares

El papel de los profesores en el proceso de mejorar la eficacia y eficiencia de la integración de nuevos enfoques pedagógicos y el potencial que ofrecen los recursos tecnológicos es básico para introducir un cambio sustancial en los procesos de enseñanza-aprendizaje, en el contexto de la educación superior. En esta línea, el objetivo de este estudio es conocer las experiencias y percepciones de profesores universitarios de distintos ámbitos disciplinares (ramas de conocimiento) sobre aceptación y adopción de metodologías basadas en Blended Learning (BL). El trabajo empírico se realizó siguiendo un diseño metodológico mixto de tipo derivativo secuencial de equivalencia de estatus. La información cuantitativa fue recogida con un cuestionario, elaborado ad hoc, basado en el marco teórico propuesto por los Modelos de Aceptación Tecnológica (TAM), al que contestaron 980 profesores universitarios; de éstos, 86 manifestaron de forma abierta su opinión sobre estas metodologías, constituyendo la parte cualitativa objeto de este estudio. Los resultados ponen de manifiesto a juicio de los docentes participantes en el estudio, las debilidades, amenazas, fortalezas y oportunidades de la enseñanza B-learning. Palabras clave: blended learning; innovación tecnológica; educación superior; metodología cualitativa, caqdas

Impact of thermal sterilization on the physicochemical-sensory characteristics of Californian-style black olives and its assessment using an electronic tongue

The effect of thermal sterilization processes on the physicochemical parameters and sensory characteristics of Californian-style black olives, from Hojiblanca and Manzanilla Cacereña brine solutions, were evaluated. Two-way ANOVA showed that Hojiblanca olives had a lower phenols content and defect intensity and that increasing the sterilization period resulted in a decrease in total phenols and an increase of the cooked defect. The impact of thermal sterilization was further evaluated using a potentiometric electronic tongue, which was capable of discriminating the different sterilization treatments (repeated K-fold cross-validation sensitivity: 89.0?±?15.0% to 97.0?±?6.0%). Moreover, multiple regressions allowed the prediction of phenols (R2???0.95?±?0.03) and the intensity of the defect (R2???0.95?±?0.04). These results point out the feasibility of the electronic tongue as an analytical tool for monitoring the effects of thermal sterilization treatments. Furthermore, the satisfactory results obtained for the brine solutions may foresee a practical non-destructive method for indirect quality assessment of table olives.Consejería de Educación y Empleo of the Junta de Extremadura to work with a scholarship at the Polytechnic Institute of Bragança for 4 months (Resolución de 18 de julio de 2019, DOE de 25 de julio de 2019, no 143) (Expedient number A28). Nuno Rodrigues thanks to National funding by FCT- Foundation for Science and Technology, P.I., through the institutional scientific employment program-contract. The authors are also grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER, under Programme PT2020, for the financial support of CIMO (UID/AGR/00690/2019) and of CEB (UID/BIO/04469/2019) and to BioTecNorte operation (NORTE-01-0145-FEDER-000004)info:eu-repo/semantics/publishedVersio

Assessing acrylamide content in sterilized Californian-style black table olives using HPLC-MS-QQQ and a potentiometric electronic tongue

The study aimed to evaluate the effects of olive cultivar (cvs. Manzanilla Cacereña and Hojiblanca) and the sterilization intensity/time-period (F0 of 1025minat 121±3°C) on the formation of acrylamide in table olives and brine. Olive cultivar and thermal sterilization had a significant impact on the amount of acrylamide produced (varying from 228±94 to 286±110 and 336±126 to 373±159ngg1, for table olives and brine, respectively, determined by HPLC-MS-QQQ). Moreover, for both cultivars, linear positive relationships (0.931R20.994) were found between the acrylamide concentration in olives and respective brine solutions, allowing to foresee a non-destructive indirect methodology for quantifying acrylamide in table olives. Finally, a potentiometric E-tongue was used to quantify acrylamide in both matrices. The lipid sensor membranes comprised on the sensor device showed potentiometric semi-logarithmic responses (0.962R20.999) towards the acrylamide concentration for aqueous standard solutions, permitting the establishment of accurate multiple linear predictive models for the quantification of acrylamide in olives and brine solutions (repeated K-fold-CV: 0.97±0.03R20.99±0.01; 12±8RMSE 28±14ngg1) for both olive cultivars. E-tongue could be used as non-destructive indirect detection method of acrylamide, based on the brine solution evaluation, and so, a complementary analytical tool to the conventional chromatographic analysis.Daniel Martín-Vertedor thanks the mobility grant of the Consejeríade Educación y Empleo of the Junta de Extremadura to work with ascholarship at the Polytechnic Institute of Bragança for 4 months(Resolución de 18 de julio de 2019, DOE de 25 de julio de 2019, no143) (Expedient number A28). The authors are grateful to theFoundation for Science and Technology (FCT, Portugal) and FEDERunder Program PT2020 forfinancial support to CIMO (UIDB/00690/2020) and to CEB (UIDB/04469/2020) units and to BioTecNorte op-eration (NORTE-01-0145-FEDER-000004) funded by the EuropeanRegional Development Fund under the scope of Norte2020 - ProgramaOperacional Regional do Norte. Nuno Rodrigues thanks to Nationalfunding by FCT- Foundation for Science and Technology, P.I., throughthe institutional scientific employment program-contract. The authorswish to thank to the Elemental and Molecular Analysis Service be-longing to the Research Support Service of the University ofExtremadura by the development of acrylamide determination methodand MaDolores López Soto and Elena Rodríguez Paniagua for their helpin the performance of this study.info:eu-repo/semantics/publishedVersio

Olive oil characteristics of eleven cultivars produced in a high-density grove in Valladolid province (Spain)

The olive oil composition of eleven cultivars (cvs. Arbequina, Arbosana, Arroniz, Cornicabra, Frantoio, Hojiblanca, Manzanilla, Picual, Picudo, Redondilla and Royuela) cultivated in a high-density olive grove located in a non-traditional producing region (Valladolid, Spain) was studied during four consecutive crop seasons. The results showed that the 122 monovarietal olive oils studied could be classified as extra virgin oils, according to the quality parameters. Furthermore, the olive cultivar had a marked effect on the chemical composition and antioxidant activity. In general, olive oils from cvs. Picual and Cornicabra showed the highest total phenolic contents, oxidative stability, and tocopherols contents, whereas the worst results for oxidative stability were observed for cv. Redondilla olive oils, probably associated to the lowest contents of phenolics and tocopherols and the highest amounts of polyunsaturated fatty acids. Finally, it was found that, despite the different crop years evaluated, the quality-chemical profiles could be used to successfully discriminate the monovarietal oils under study (linear discriminant analysis sensitivities: 92 ± 5% for the repeated K-fold cross-validation), using the data of 15 non-redundant variables identified by the simulated annealing variable selection algorithm.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES to CIMO (UIDB/00690/2020) and Associate Laboratories for Green Chemistry-LAQV (UIDB/50006/2020) and SusTEC (LA/P/0007/2020). Nuno Rodrigues thanks to National funding by FCT- Foundation for Science and Technology, P.I., through the institutional scientific employment program-contract.info:eu-repo/semantics/publishedVersio

Enose Lab made with vacuum sampling: Quantitative applications

Producción CientíficaA lab-made electronic nose (Enose) with vacuum sampling and a sensor array, comprising nine metal oxide semiconductor Figaro gas sensors, was tested for the quantitative analysis of vapor–liquid equilibrium, described by Henry’s law, of aqueous solutions of organic compounds: three alcohols (i.e., methanol, ethanol, and propanol) or three chemical compounds with different functional groups (i.e., acetaldehyde, ethanol, and ethyl acetate). These solutions followed a fractional factorial design to guarantee orthogonal concentrations. Acceptable predictive ridge regression models were obtained for training, with RSEs lower than 7.9, R2 values greater than 0.95, slopes varying between 0.84 and 1.00, and intercept values close to the theoretical value of zero. Similar results were obtained for the test data set: RSEs lower than 8.0, R2 values greater than 0.96, slopes varying between 0.72 and 1.10, and some intercepts equal to the theoretical value of zero. In addition, the total mass of the organic compounds of each aqueous solution could be predicted, pointing out that the sensors measured mainly the global contents of the vapor phases. The satisfactory quantitative results allowed to conclude that the Enose could be a useful tool for the analysis of volatiles from aqueous solutions containing organic compounds for which Henry’s law is applicable.Fundación para la Ciencia y la Tecnología (FCT, Portugal) y Fondo Europeo de Desarrollo Regional (FEDER) under Programme PT2020 - (grants UID/AGR/00690/2019 y LA/P/0007/2020