Characterization and improvement of rheological properties of sodium caseinate glycated with galactose, lactose and dextran

10 páginas, 7 figuras, 2 tablas.-- El pdf del artículo es la versión de autor.The aim of this work was to investigate the effect of non-enzymatic glycosylation with galactose, lactose, and 10 kDa dextran on the rheological properties of sodium caseinate. To promote the formation of covalent complexes, the reaction was done in solid state (aw = 0.67), pH 7.0 (0.1 M sodium phosphate buffer), and temperature set at 50 and 60 °C. The progress of Maillard reaction was indirectly traced by measuring the formation of the Amadori compound, through furosine (2-furoylmethyl-lysine) analysis, and brown polymers, and the resulting glycoconjugates were characterized by LC/ESI-MS and SEC. Results showed a higher reactivity of galactose than lactose and dextran to form the glycoconjugates, due to its smaller molecular weight. Glycation with galactose and lactose increased the viscosity of caseinate and also altered its flow characteristics from Newtonian to shear-thinning. Oscillatory testing showed a higher elastic modulus (G′) in glycoconjugates when compared to non-glycated caseinate, especially with galactose, where a gel-like behaviour was observed after long incubation times. Glycation with dextran did not produce substantial improvements in the rheological properties of caseinate, probably due to the limited extent of the reaction. Our results show that by controlling the rate and extent of the Maillard reaction is a technologically feasible operation to improve the viscosity and gelling properties of sodium caseinate-based ingredients.This work was supported by projects Consolider Ingenio 2010 FUN-C-FOOD CSD2007-00063 (Ministerio de Educación y Ciencia), ALIBIRD S-0505/AGR/000153 (Comunidad de Madrid) and Hatch project TEN00332 (University of Tennessee Institute of Agriculture). M. Corzo-Martínez thanks the CSIC for an I3P PhD-grant.Peer reviewe

On the Gas Surrounding High Redshift Galaxy Clusters

Francis & Hewett (1993) identified two 10-Mpc scale regions of the high redshift universe that were seemingly very overdense in neutral hydrogen. Subsequent observations showed that at least one of these gas-rich regions enveloped a cluster of galaxies at redshift 2.38. We present improved observations of the three background QSOs with sightlines passing within a few Mpc of this cluster of galaxies. All three QSOs show strong neutral hydrogen absorption at the cluster redshift, suggesting that this cluster (and perhaps all high redshift clusters) may be surrounded by a ~5 Mpc scale region containing ~ 10^12 solar masses of neutral gas. If most high redshift clusters are surrounded by such regions, we show that the gas must be in the form of many small ( 0.03 cm^-3) clouds, each of mass < 10^6 solar masses. These clouds are themselves probably gathered into > 20 kpc sized clumps, which may be galaxy halos or protogalaxies. If this gas exists, it will be partially photoionised by the UV background. We predict the diffuse Ly-alpha flux from this photoionisation, and place observational limits on its intensity.Comment: 19 pages, 5 figures. Accepted for publication in PAS

An alternative approach to estimate any subdaily extreme of rainfall and wind from usually available records

A wide variety of engineering applications requires the use of maximum values of rainfall intensity and wind speed related to short recording intervals, which can often only be estimated from available less exhaustive records. Given that many locations lack exhaustive climatic records that would allow accurate empirical correlations between different recording intervals to be identified, generic equations are often used to estimate these extreme values. The accuracy of these generic estimates is especially important in fields such as the study of wind-driven rain, in which both climatic variables are combined to characterise the phenomenon. This work assesses the reliability and functionality of some of these most widespread generic equations, analysing climatic datasets gathered since 2008 in 109 weather stations in Spain and the Netherlands. Considering multiple recording intervals at each location, it is verified that most of these generic estimations, used especially in the study of wind-driven rain, have functional limitations and can cause significant errors when characterising both variables for subdaily intervals and extreme conditions. Finally, an alternative approach is proposed to accurately extrapolate extreme values of both variables related to any subdaily recording interval in a functional manner and from any available records. © 2021, The Author(s)

Un estudio sobre el papel de las analogías en la construcción del modelo cinético-molecular de la materia

En este trabajo se propone, en primer lugar, un marco teórico para analizar el papel de las analogías en la construcción de modelos sobre fenómenos científicos por parte de los alumnos. Tomando como base dicho marco, se fundamenta, en segundo lugar, un diseño didáctico concreto encaminado a facilitar la construcción del modelo cinético-molecular de la materia a través de analogías, en alumnos de educación secundaria obligatoria. Finalmente, se evalúa el diseño didáctico empleado comparando los resultados finales alcanzados en pruebas de interpretación y predicción de fenómenos en un grupo experimental y en otro de control. Los resultados obtenidos parecen indicar que las analogías jugaron un papel relevante en la comprensión de los alumnos que fueron enseñados a través de dicho recurso. Éstos aportaron, finalmente, modelos explicativos más acordes con el modelo científico que los alumnos que fueron enseñados según un diseño semejante pero sin analogías, si bien las diferencias encontradas fueron pequeñas.In order to analyze the role of the analogies on the model construction about scientific phenomena in the students, a theoretical framework is firstly proposed. From this framework, a concrete didactic design is also proposed with regard to facilitating the construction of a kinetic-molecular model of matter through analogies, in students of compulsory secondary education. Finally, the didactic design used is evaluated, comparing the final results in the interpretation and prediction of phenomena between an experimental group and a control one. The post-test results indicate that the analogies used played a relevant role in the learning process of the pupils who were taught through the mentioned resource. They provided, finally, explanatory models more in agreement with the scientific model than the pupils who were taught according to a similar design but without analogies, although the differences found were small

Una propuesta didáctica basada en la investigación para el uso de analogías en la enseñanza de las ciencias

In this paper, an analysis about the advantages and difficulties of the analogies, as a didactic resource in science education, is accomplished. According to the results of the investigation developed in this field during the last years, some criteria to take into account with the purpose of improving their use in the classroom, are also provided. All these contributions are accompanied by concrete examples that help to illustrate the considerations and the didactic implications for educational practice

CVS-Q teen©: computer vision syndrome in adolescents and its relationship with digital textbooks

Objetivo: Analizar la prevalencia y la evolución del síndrome visual informático en estudiantes de secundaria y bachillerato mediante el CVS-Q© adaptado y validado para adolescentes, según empleen libros en papel o en soporte digital. Método: Se adaptará el CVS-Q© mediante un pilotaje en adolescentes y un grupo nominal compuesto por especialistas en salud visual, profesorado y padres/madres. Se evaluarán la calidad y la aplicabilidad de la versión resultante (CVS-Q teen©) y se realizará un estudio de validación con pruebas visuales, retest y análisis psicométrico. Posteriormente, se realizará un estudio prospectivo longitudinal con cuatro medidas repetidas en adolescentes de dos institutos de San Juan de Alicante (uno ha sustituido libros por tabletas). Se medirá el síndrome visual informático mediante el CVS-Q teen© con tres seguimientos. Se analizará la prevalencia de síndrome visual informático según factores sociodemográficos, visuales y de uso de dispositivos digitales. Se realizarán modelos de regresión logística con efecto aleatorio por estudiante y tiempo de uso.Objective: To analyse the prevalence and progression of computer vision syndrome in secondary and high school students with the CVS-Q© adapted and validated for adolescents, depending on whether they use textbooks or digital books. Method: The CVS-Q© will be adapted by a pilot study in adolescents and a nominal group of visual health specialists, teachers and parents. The resulting version (CVS-Q teen©) will be tested to confirm its quality and applicability and a validation study will be done with visual tests, retest and psychometric analysis. Subsequently, a prospective longitudinal study with four repeated measures will be carried out in adolescents from two secondary schools of San Juan de Alicante (one has replaced textbooks by tablets). Computer vision syndrome will be measured by the CVS-Q teen© with three follow-ups. The prevalence of computer vision syndrome will be analysed according to sociodemographic, visual and digital device use variables. Logistic regression models will be performed, with random effect by student and time of use.Los autores agradecen al Vicerrectorado de Investigación de la Universidad de Alicante por el contrato de formación predoctoral de la segunda autora (UAFPU2019-08). El presente proyecto ha sido financiado por la convocatoria «Proyectos de Investigación en Salud», Fondo de Investigación en Salud del Instituto de Salud Carlos III, Ministerio de Ciencia e Innovación y Unión Europea, a través de los Fondos Europeos de Desarrollo Regional (FEDER) «Una manera de hacer Europa», con la referencia PI20/01629

Macroeconomics in practice: using WIKIS for collaborative learning

This project is based on the creation of collaborative wikis for students of Macroeconomics to elaborate a final work in which they apply the theoretical knowledge learnt in the subject to the real world. The initiative was implemented during the course 2015-2016 and aimed at 140 students enrolled in the subject at the Degree of Finance and Accountancy of the University of Cadiz. To emphasize the link between the theories explained in class and the real world, in previous courses we have already used news and other resources. With this project, we now introduce the use of wikis, which consist on the creation of a website to allow collaborative creation and modification of contents and structure from the web browser. Students were organized in 44 teams, of about 3 members, to examine data on a certain macroeconomic variable (i.e. inflation or GDP), in a particular geographical context (i.e. G20 or EU countries). The objectives of the project include: i) to enhance learning and comprehension of theoretical knowledge and ii) to contribute to the development of skills related to the subject, such as the skill to apply the acquired knowledge, the skill to analyze and search information and teamwork. Students’ opinions gathered from a survey at the end of the course suggest that these objectives have been achieved

Estudio del efecto de la variación de la viscosidad sobre el poder adhesivo del cianoacrilato de n-butilo

Los cianoacrilatos se adhieren fuertemente a los tejidos vivos cuando son aplicados en forma de una delgada capa, esto ha promovido el estudio y uso de estos materiales como adhesivos tisulares. Ellos poseen también la propiedad de favorecer la coagulación de la sangre por lo que se han estudiado y aplicado como agentes hemostáticos. La viscosidad de estos compuestos se encuentra en el rango de 2 a 2,5 cP medidos a 26 0C. Sin embargo en estudios de estabilidad realizados en el laboratorio a temperatura de conservación por debajo de 8 0C se ha detectado que en el período de un año se incrementa gradualmente este valor, aunque se mantiene dentro de los límites aceptables para su aplicación en la medicina. En este trabajo se comprobó, mediante mediciones de fuerzas de cizalla a probetas de TR1 utilizando cianoacrilato de n-butilo como adhesivo, que la variación de la viscosidad dentro del rango de aplicación en medicina no afecta significativamente la fuerza de adhesión del adhesivo. Se demostró también un comportamiento lineal en un rango de valores de hasta 20 cP entre la fuerza de cizalla y la viscosidad y que el mecanismo de ruptura de las probetas de fallo cohesivo, es decir, que en estos casos la fuerza de adhesión es óptima.Peer Reviewe

Mammal traits and soil biogeochemistry: Functional diversity relates to composition of soil organic matter

Mammal diversity affects carbon concentration in Amazonian soils. It is known that some species traits determine carbon accumulation in organisms (e.g., size and longevity), and are also related to feeding strategies, thus linking species traits to the type of organic remains that are incorporated into the soil. Trait diversity in mammal assemblages – that is, its functional diversity – may therefore constitute another mechanism linking biodiversity to soil organic matter (SOM) accumulation. To address this hypothesis, we analyzed across 83 mammal assemblages in the Amazon biome (Guyana), the elemental (by ED‐XRF and CNH analysis) and molecular (FTIR‐ATR) composition of SOM of topsoils (401 samples) and trait diversity (functional richness, evenness, and divergence) for each mammal assemblage. Lower mammal functional richness but higher functional divergence were related to higher content of carbonyl and aliphatic SOM, potentially affecting SOM recalcitrance. Our results might allow the design of biodiversity management plans that consider the effect of mammal traits on carbon sequestration and accumulation in soils.Xunta de Galicia | Ref. ED431C 2021/32Xunta de Galicia | Ref. ED481D 2019/024National Science Foundation | Ref. BE/CNH 05 0809