Una investigación sobre las tensiones efectivas en suelos no saturados

Esta tesina se centra en el estudio del comportamiento hidromecánico de un suelo no saturado ante cambios de succión y de tensión neta. La mecánica de suelo se desarrolló inicialmente con el estudio de los suelos saturados y la introducción de la tensión efectiva para los mismos. Sin embargo, una gran parte de los suelos naturales (depósitos fluviales, aluviales, etc.), así como las estructuras de tierra realizadas por el hombre (terraplenes, núcleos de presas, etc.), están construidas con suelos no saturados. De ahí la necesidad de un estudio profundo de éstos que en los últimos años se ha incrementado de forma importante

Ripening behaviour and consumer acceptance of ‘Conference’ pears during shelf life after long term DCA-storage

With the increasing demand for ready to eat fruit, understanding how pear quality evolves during shelf life (SL) is of paramount importance for retailers. Accordingly, the relationships between physicochemical quality parameters, the emission of volatile compounds and consumer satisfaction were investigated in ‘Conference’ pears from different orchards and stored at 20 °C following 8 months of cold storage (-0.5 °C) under dynamic controlled atmosphere (DCA). Our results showed that DCA storage strongly inhibits firmness loss ( 0.96). Prolonged DCA storage of Conference did not completely impede ripening as indicated by the reducing trend of IAD and the ethylene postclimacteric behavior of the fruit during SL. In parallel to the decrease of firmness during SL, there was a consistent increase in most ester-type volatiles and especially in hexyl acetate and butyl acetate. Generally, the highest consumer satisfaction after DCA cold storage of ‘Conference’ pears was reached after 3 d at 20 °C. In this sense, the most appreciated pears by consumer were those showing high flavour in combination with firmness values in the range of 10–30 N. The Partial Least Square (PLS) model showed that total soluble solids (TSS), the ratio TSS/TTA (total titratable acidity), consumer flavour perception and some particular volatile compounds (i.e. methyl, ethyl and hexyl acetates as well as ethyl trans,cis-2,4-decadienoate) were positively correlated to consumer’s overall liking while firmness, TTA and index of absorbance difference (IAD) had a negative correlation and higher prediction capability.info:eu-repo/semantics/acceptedVersio

Spatial distribution of flavor components and antioxidants in the flesh of ‘Conference’ pears and its relationship with postharvest pathogens susceptibility

The spatial distribution of dry matter, ethylene production, respiration rate, organic acids, sugars, antioxidants, volatiles and fungal (Penicillium expansum and Rhizopus stolonifer) growth was evaluated analyzing four different slices of ‘Conference’ pear flesh taken along an equatorial radius. A common spatial distribution trend was found for ethylene emission, CO2 production, antioxidant capacity and total phenolic compounds with a minimum in the slice under the skin and a maximum in the slice near the core. Fructose, which was the dominant sugar followed by sucrose and glucose, showed a quasi-linear decreasing profile from the outer slice towards the core. Malic and ascorbic acid had the highest content in the outer slice while citric remained practically constant over the different slices. Twenty-nine volatile organic compounds (VOCs) were identified using solid-phase microextraction (SPME), yet only six of them showed significant differences between flesh slices. The content in VOCs was further related to the tissue susceptibility to the above-mentioned postharvest pathogens using a multivariate approach. Fruit flesh from inner sections was more prone to P. expansum whereas flesh from the slice under the skin presented the highest incidence of R. stolonifer. A Partial Least Square (PLS) model showed that P. expansum growth was negatively correlated with malic acid, dry matter content, 2-ethyl-hexanal and butyl hexanoate concentrations and R. stolonifer was negatively correlated to sucrose and some volatiles such as hexanal and 1-butanol. Based on the results from the PLS, selected volatiles naturally present in the pear flesh were tested in vitro, at different concentrations, in order to investigate their effectiveness to control blue mold caused by P. expansum and soft rot caused by R. stolonifer. A completely control of P. expansum was found with 2-ethyl-hexanal application and hexanal while 1-butanol showed a total fungicide effect against R. stolonifer. This study is a step towards a better understanding of how biochemical compounds are spatially distributed among different slices of ‘Conference’ pears as well as in the development of natural compounds to fight major postharvest pathogens in pear fruit.info:eu-repo/semantics/acceptedVersio

Statistical similarity between the compression of a porous material and earthquakes

It has been long stated that there are profound analogies between fracture experiments and earthquakes; however, few works attempt a complete characterization of the parallelisms between these so separate phenomena. We study the Acoustic Emission events produced during the compression of Vycor (SiO2). The Gutenberg-Richter law, the modified Omori's law, and the law of aftershock productivity are found to hold for a minimum of 5 decades, are independent of the compression rate, and keep stationary for all the duration of the experiments. The waiting-time distribution fulfills a unified scaling law with a power-law exponent close to 2.45 for long times, which is explained in terms of the temporal variations of the activity rate.Comment: 4 pages and a bit more, 4 figure

Exploring the effects of interchange rotations on high-intensity activities of elite futsal players

The literature lacks an understanding of the physical demands of team sports with unlimited substitutions (player interchange rotations). Because of this characteristic of the game, it is necessary to analyze the physical requirements through player rotation rather than analyzing global averages. The objective of this research is to investigate the relationship between high-intensity activities (HIA; sum of accelerations, decelerations, and high-speed running actions) performed per interchange rotations and match time variables (playtime, rest time, and work–rest ratio) in elite futsal players. A retrospective observational design was used. Twelve matches from an elite male team competing in the Premier Spanish Futsal League were analyzed using a local positioning system, yielding a total sample of 17 players. The number of HIA performed per interchange rotation varies between players and allows the identification of three distinct activity profiles—lower HIA (10 HIA), medium HIA (28 HIA), and higher HIA (38 HIA). Furthermore, these profiles were found to be stable alongside the existing interchange rotations throughout the match. Playtime (F = 40.9, p < .001) and work–rest ratio (F = 15.6, p < .001) are the time variables that best differentiate match activity profiles. Players with more playing time (4.6 ± 1.0 min) and a work–rest ratio equal to or greater than 1 (1.1 ± 0.6 a.u.) have a greater ability to repeat HIA per rotation.info:eu-repo/semantics/publishedVersio

Online oxygen monitoring using integrated inkjet-printed sensors in a liver-on-a-chip system

The demand for real-time monitoring of cell functions and cell conditions has dramatically increased with the emergence of organ-on-a-chip (OOC) systems. However, the incorporation of co-cultures and microfluidic channels in OOC systems increases their biological complexity and therefore makes the analysis and monitoring of analytical parameters inside the device more difficult. In this work, we present an approach to integrate multiple sensors in an extremely thin, porous and delicate membrane inside a liver-on-a-chip device. Specifically, three electrochemical dissolved oxygen (DO) sensors were inkjet-printed along the microfluidic channel allowing local online monitoring of oxygen concentrations. This approach demonstrates the existence of an oxygen gradient up to 17.5% for rat hepatocytes and 32.5% for human hepatocytes along the bottom channel. Such gradients are considered crucial for the appearance of zonation of the liver. Inkjet printing (IJP) was the selected technology as it allows drop on demand material deposition compatible with delicate substrates, as used in this study, which cannot withstand temperatures higher than 130 °C. For the deposition of uniform gold and silver conductive inks on the porous membrane, a primer layer using SU-8 dielectric material was used to seal the porosity of the membrane at defined areas, with the aim of building a uniform sensor device. As a proof-of-concept, experiments with cell cultures of primary human and rat hepatocytes were performed, and oxygen consumption rate was stimulated with carbonyl-cyanide-4-(trifluoromethoxy)phenylhydrazone (FCCP), accelerating the basal respiration of 0.23 ± 0.07 nmol s-1/106 cells up to 5.95 ± 0.67 nmol s-1/106 cells s for rat cells and the basal respiration of 0.17 ± 0.10 nmol s-1/106 cells by up to 10.62 ± 1.15 nmol s-1/106 cells for human cells, with higher oxygen consumption of the cells seeded at the outflow zone. These results demonstrate that the approach of printing sensors inside an OOC has tremendous potential because IJP is a feasible technique for the integration of different sensors for evaluating metabolic activity of cells, and overcomes one of the major challenges still remaining on how to tap the full potential of OOC systems.Peer ReviewedPostprint (author's final draft

Relating external load variables with individual tactical actions with reference to playing position: an integrated analysis for elite futsal

The purpose of this study was to contextualise players’ high-intensity activities (HIA) with individual tactical actions during match play with reference to playing positions. Tracking data was obtained using local positioning system devices from 19 male elite futsal players (28.8 ± 2.4 years). The HIA measures included high-intensity acceleration (ACC; ≥3 m · s−2), deceleration (DEC; ≤−3 m · s−2), and high-speed running (HSR; ≥18 km · h−1). Tracking data and match footage were synchronised using the SPRO™ to code players’ physical performance and technical-tactical actions. A small statistically significant association was observed between HIA and players’ actions with or without the ball (χ2 = 183.27 (2, N = 4234), p<.001; Cramer’s V = 0.21). When players have the ball, the number of DEC efforts tends to increase with a corresponding decrease in ACC and HSR. When the players do not have the ball, ACC and HSR running tend to increase with a corresponding decrease in DEC. A comparison between HIA revealed that futsal performance requires greater mechanical efforts (ACC + DEC) than kinematic efforts (HSR). This underscores the importance of mechanical efforts within short space for futsal performance. Moreover, the diverse tactical actions associated with different player positions contribute to distinct activity profiles and physical requirements.info:eu-repo/semantics/publishedVersio

Cyclobutane-based peptides/terpyridine conjugates : Their use in metal catalysis and as functional organogelators

Two new conjugates, hcptpyDP and hcptpyTP, of a terpyridine derivative incorporating artificial peptide moieties, have been synthesized and their use in the preparation of metal catalysts and organogelators has been investigated. Ru(II) complexes derived from these ligands showed electrochemical behavior and activity as catalysts in the epoxidation of olefins similar to that of Beller's catalyst. As organogelators, these conjugates were able to gelate a variety of solvents, from toluene to methanol, with satisfactory mgc (minimum gelation concentration) values. The presence of 4'-(4-carboxy)phenylterpyridine (hcptpy) moiety allows tuning the gelling properties and also influences the supramolecular self-assembling mode to produce chiral aggregates with respect to parent peptides DP and TP. In the case of the conjugates, π−π interactions provided by the aromatic moieties cooperate with inter-molecular hydrogen bonding between NH and CO in the amide groups. Further properties of peptide/terpyridine conjugates are under investigation in view of future applications