Predicción de la frescura del aceite de oliva virgen extra durante el almacenamiento mediante espectroscopía de fluorescencia

Virgin olive oil quality relates to flavor and unique health benefits. Some of these properties are at the most desirable level when the oil is just extracted, since it is not a product that improves with age. On the contrary, the concentrations of many compounds change during its shelf-life. These changes reveal the aging of the oil but do not necessarily mean decay in sensory properties, so in some cases an aged oil from healthy olives may be better qualified than a fresh one from olives affected by fermentation. The aim of this work is to analyze different methodologies proposed for assessing the quality of virgin olive oil with implications in freshness and aging of the oil, and to highlight the possibilities of rapid spectrofluorimetric techniques for assessing oil freshness by checking the evolution of pigments during storage. The observed change in the selected spectral features and mathematical modelling over time was compared with the accepted model for predicting the amount of pyropheophytin a, which is based on isokinetic studies. The best regression was obtained for 655 nm (adjustedR2 = 0.91) wavelength, which matches the distinctive band of pigments. The two mathematical models described in this study highlight the usefulness of pigments in the prediction of the shelf-life of extra virgin olive oil.La calidad del aceite de oliva virgen está relacionada con su flavor y sus beneficios únicos para la salud. Algunas de estas propiedades se encuentran en el nivel más deseable cuando el aceite está recién extraído, ya que no es un producto que mejore con el tiempo. Por el contrario, las concentraciones de muchos compuestos cambian a lo largo de la vida útil. Estos cambios revelan el envejecimiento del aceite, pero no implican necesariamente la alteración de las propiedades sensoriales, por lo que en algunos casos un aceite envejecido procedente de aceitunas sanas puede presentar mejor calidad que uno fresco procedente de aceitunas afectadas por procesos de fermentación. El objetivo de este trabajo es estudiar diferentes metodologías propuestas para evaluar la calidad del aceite de oliva virgen con implicaciones en la frescura y el envejecimiento del aceite, destacando las posibilidades de las rápidas técnicas espectrofluorométricas para evaluar la frescura del aceite verificando la evolución de los pigmentos durante el almacenamiento. El cambio observado en las características espectrales seleccionadas y su modelado matemático a lo largo del tiempo se comparó con el modelo aceptado para predecir la cantidad de pirofeofitina a, que se basa en estudios isocinéticos. Los dos modelos matemáticos descritos en este estudio pusieron de manifiesto la utilidad de los pigmentos en la predicción de la vida útil del aceite de oliva virgen extra. La mejor regresión se obtuvo para 655 nm (R2 -ajustado = 0,91), longitud de onda que coincide con la banda distintiva de pigmentos.Secretaría de Estado de Investigación, Desarrollo e Innovación de España-AGL2015-69320-

Predicción de la frescura del aceite de oliva virgen extra durante el almacenamiento mediante espectroscopía de fluorescencia

Virgin olive oil quality relates to flavor and unique health benefits. Some of these properties are at the most desirable level when the oil is just extracted, since it is not a product that improves with age. On the contrary, the concentrations of many compounds change during its shelf-life. These changes reveal the aging of the oil but do not necessarily mean decay in sensory properties, so in some cases an aged oil from healthy olives may be better qualified than a fresh one from olives affected by fermentation. The aim of this work is to analyze different methodologies proposed for assessing the quality of virgin olive oil with implications in freshness and aging of the oil, and to highlight the possibilities of rapid spectrofluorimetric techniques for assessing oil freshness by checking the evolution of pigments during storage. The observed change in the selected spectral features and mathematical modelling over time was compared with the accepted model for predicting the amount of pyropheophytin a, which is based on isokinetic studies. The best regression was obtained for 655 nm (adjustedR2 = 0.91) wavelength, which matches the distinctive band of pigments. The two mathematical models described in this study highlight the usefulness of pigments in the prediction of the shelf-life of extra virgin olive oil.La calidad del aceite de oliva virgen está relacionada con su flavor y sus beneficios únicos para la salud. Algunas de estas propiedades se encuentran en el nivel más deseable cuando el aceite está recién extraído, ya que no es un producto que mejore con el tiempo. Por el contrario, las concentraciones de muchos compuestos cambian a lo largo de la vida útil. Estos cambios revelan el envejecimiento del aceite, pero no implican necesariamente la alteración de las propiedades sensoriales, por lo que en algunos casos un aceite envejecido procedente de aceitunas sanas puede presentar mejor calidad que uno fresco procedente de aceitunas afectadas por procesos de fermentación. El objetivo de este trabajo es estudiar diferentes metodologías propuestas para evaluar la calidad del aceite de oliva virgen con implicaciones en la frescura y el envejecimiento del aceite, destacando las posibilidades de las rápidas técnicas espectrofluorométricas para evaluar la frescura del aceite verificando la evolución de los pigmentos durante el almacenamiento. El cambio observado en las características espectrales seleccionadas y su modelado matemático a lo largo del tiempo se comparó con el modelo aceptado para predecir la cantidad de pirofeofitina a, que se basa en estudios isocinéticos. Los dos modelos matemáticos descritos en este estudio pusieron de manifiesto la utilidad de los pigmentos en la predicción de la vida útil del aceite de oliva virgen extra. La mejor regresión se obtuvo para 655 nm (R2 -ajustado = 0,91), longitud de onda que coincide con la banda distintiva de pigmentos.Secretaría de Estado de Investigación, Desarrollo e Innovación de España-AGL2015-69320-

Defragmenting public space : a guide for policymakers

While social inequalities remain key features of numerous cities globally, many still manage to provide spaces for collective social life, including public streets, market spaces and parks. Yet many countries today, with growing and significant socio-economic disparities and a rising fear of crime and violence, now see a range of strategies by their wealthiest citizens to avoid public spaces. This avoidance has generated a more fragmented engagement with the city by particular social groups. These processes, including the avoidance of public spaces and normalisation of gated communities, are reshaping cities leaving fewer shared spaces for collective life as public spaces are privatised. This report comes from a dialogue between researchers with interests in the risks and challenges for the public life of cities and these new and growing patterns of segregation and social avoidance. The collaboration between scholars and institutions seeks to understand the increasingly defensive quality of many urban centres and to identify forms of policy, practice and urban interventions capable of ensuring public safety and participation by all citizens. The purpose of this report is to engage researchers and practitioners in the discussion about the risks and challenges associated with urban fragmentation strategies and the means by which safer, more inclusive and liveable public spaces might be achieved

Concepts, models, and methods in computational heterogeneous catalysis illustrated through CO2 conversion

Theoretical investigations and computational studies have notoriously contributed to the development of our understanding of heterogeneous catalysis during the last decades, when powerful computers have become generally available and efficient codes have been written that can make use of the new highly parallel architectures. The outcomes of these studies have shown not only a predictive character of theory but also provide inputs to experimentalists to rationalize their experimental observations and even to design new and improved catalysts. In this review, we critically describe the advances in computational heterogeneous catalysis from different viewpoints. We firstly focus on modeling because it constitutes the first key step in heterogenous catalysis where the systems involved are tremendously complex. A realistic description of the active sites needs to be accurately achieved to produce trustable results. Secondly, we review the techniques used to explore the potential energy landscape and how the information thus obtained can be used to bridge the gap between atomistic insight and macroscale experimental observations. This leads to the description of methods that can describe the kinetic aspects of catalysis, which essentially encompass microkinetic modeling and kinetic Monte Carlo simulations. The puissance of computer simulations in heterogeneous catalysis is further illustrated by choosing CO2 conversion catalyzed by different materials for most of which a comparison between computational information and experimental data is available. Finally, remaining challenges and a near future outlook of computational heterogeneous catalysis are provided.publishe

Carbon capture and usage by MXenes

Two-dimensional pristine M2X MXenes are proposed as highly active catalytic materials for carbon dioxide (CO2) greenhouse gas conversion into carbon monoxide (CO) on the basis of a multiscale modeling approach, coupling calculations carried out in the framework of density functional theory and newly developed kinetic phase diagrams. The extremely facile CO2 conversion into CO leaves the MXene surfaces partially covered by atomic oxygen, recovering its pristine nature by a posterior catalyst regeneration by hydrogen (H2) treatment at high temperatures, with MXenes effectively working as two-step catalysts for the reverse water–gas shift reaction.publishe

Deuteration around the ultracompact HII region Mon R2

The massive star-forming region Mon R2 hosts the closest ultra-compact HII region that can be spatially resolved with current single-dish telescopes. We used the IRAM-30m telescope to carry out an unbiased spectral survey toward two important positions (namely IF and MP2), in order to studying the chemistry of deuterated molecules toward Mon R2. We found a rich chemistry of deuterated species at both positions, with detections of C2D, DCN, DNC, DCO+, D2CO, HDCO, NH2D, and N2D+ and their corresponding hydrogenated species and isotopologs. Our high spectral resolution observations allowed us to resolve three velocity components: the component at 10 km/s is detected at both positions and seems associated with the layer most exposed to the UV radiation from IRS 1; the component at 12 km/s is found toward the IF position and seems related to the molecular gas; finally, a component at 8.5 km/s is only detected toward the MP2 position, most likely related to a low-UV irradiated PDR. We derived the column density of all the species, and determined the deuterium fractions (Dfrac). The values of Dfrac are around 0.01 for all the observed species, except for HCO+ and N2H+ which have values 10 times lower. The values found in Mon R2 are well explained with pseudo-time-dependent gas-phase model in which deuteration occurs mainly via ion-molecule reactions with H2D+, CH2D+ and C2HD+. Finally, the [H13CN]/[HN13C] ratio is very high (~11) for the 10 km/s component, which also agree with our model predictions for an age of ~0.01-0.1 Myr. The deuterium chemistry is a good tool for studying star-forming regions. The low-mass star-forming regions seem well characterized with Dfrac(N2H+) or Dfrac(HCO+), but it is required a complete chemical modeling to date massive star-forming regions, because the higher gas temperature together with the rapid evolution of massive protostars.Comment: 14 pages of manuscript, 17 pages of apendix, 7 figures in the main text, accepted for publication in A&

Dynamic simulations in SixTrack

The DYNK module allows element settings in SixTrack to be changed on a turn-by-turn basis. This document contains a technical description of the DYNK module in SixTrack. It is mainly intended for a developer or advanced user who wants to modify the DYNK module, for example by adding more functions that can be used to calculate new element settings, or to add support for new elements that can be used with DYNK.Comment: Submission to CERN yellow report / conference proceeding, the 2015 collimation tracking code worksho

Structural and Electronic Properties of Metal/Oxide Nanostructures from First-Principles: Ru13 Supported on (TiO2)84 as a Case Study

All electron density functional theory-based calculations are carried out to investigate the properties of metal/oxide nanostructures taking the case of a Ru13 cluster supported on an octahedral anatase (TiO2)84 nanoparticle, as a representative system. The interaction between both systems is exothermic showing binding energies below −4 eV. In spite of the large interaction, the structure of the (TiO2)84 nanoparticle remains unaltered. However, the metal-support interaction promotes the deformation of the Ru13 cluster atomic structure. This deformation is more accentuated when the Ru13 nanocluster is situated in the facet region of the (TiO2)84 nanoparticle than when the interaction involves the edge regions. The formation of the Ru13/(TiO2)84 heterostructure leads to a decrease of the energy gap inherent to the bare (TiO2)84 nanoparticle, becoming almost negligible. This is due to the contribution of the partially filled Ru 4d orbitals with Kohn-Sham energies spanning in the energy range of those of the O 2p occupied and Ti 3d empty manifolds. This feature is systematically observes no matter the interaction involves the oxide nanoparticle facet or edge regions. This study constitutes a first step in designing a strategy to investigate metal-semiconductor nanostructures using realistic models that go beyond the use of extended surfaces

Effect of conductivity and frequency on detection of heterogeneities in solid/liquid interfaces using local electrochemical impedance Theoretical and experimental study

This short communication demonstrates, by solving the Laplace equation with proper boundary conditions (BC) using finite element method (FEM), that it is not possible to establish a correlation between what happens in the electrolyte near an active boundary and what really occurs at the actual boundary if adequate ranges of electrolyte conductivity and input AC signal frequency are not selected, especially when inhomogeneities approximated by Neumann BC are present. Experimental evidence obtained by local electrochemical impedance mapping (LEIM) supports the theoretical results.This work has been supported by the Ministry of Science and Inno-vationofSpain(MAT2006-04486andIPT-020000-2010-0001Projects

Growth patterns of the topshell Phorcus lineatus (da Costa, 1778) in northern Iberia deduced from shell sclerochronology

Combined shell growth pattern and oxygen isotope analysis has become a powerful approach in palaeoclimate and archaeological studies for reconstructing palaeoclimate conditions and littoral exploitation patterns, respectively. Recent investigations have shown that the gastropod Phorcus lineatus (da Costa, 1778) forms its shell in conditions of near equilibrium with the oxygen isotope signature of the seawater environment, demonstrating the utility of this species for reconstruction of sea surface temperature and determination of the season of harvest in archaeological studies. In contrast, the shell growth patterns of this species have received virtually no attention despite providing information on the rate and timing of shell growth that is crucial for correctly interpreting environmental proxies derived from shell geochemistry. In this paper, we compare microgrowth patterns and isotopic profiles of four modern individuals of the gastropod P. lineatus from northern Iberia to determine the timing and periodicity of subannual growth markers within the shells. Results of this sclerochronological study showed the presence of two types of growth lines/increments: i) large-scale accretionary units formed with variable periodicity, and ii) small-scale accretionary units formed by micro growth lines and increments determined by semidiurnal tidal cycles. Results suggest that shells grew uninterruptedly during early ontogeny. However, older specimens exhibited growth cessation/slowdown during summer and winter/spring. Therefore, shell growth rate is not only controlled by environmental conditions, but also by ontogenetic age and/or endogenous rhythms. A high correlation was found between seawater temperature derived from shell oxygen isotopes and instrumental seawater temperature (r2 = 0.88–0.98; p-values < 0.0001). This study shows that establishing accurate growth patterns of the topshell P. lineatus is essential for correctly reconstructing past seawater temperature conditions in palaeoclimate studies and for determining with higher precision the season(s) when the subfossil shells were collected by humans.This research was performed as part of the project TRACECHANGE: Tracing Climatic Abrupt Change Events and their Social Impact during the Late Pleistocene and Early Holocene (15–7 ky cal BP) (2014–2016) (HAR2013-46802-P), funded by the Spanish Ministry of Economy and Competitiveness, MINECO. AGE was funded by the University of Cantabria through a predoctoral grant (no code available). IGZ was also supported by the Juan de la Cierva Research Programme (grant number JCI-2012-12094) funded by the MINECO