Modified atmosphere packaging and dark/light refrigerated storage in green leafy vegetables have impact on nutritional value

The consumption of zeaxanthin (Z) through a vegetable-rich diet is recommended to reduce the progression of age-related macular degeneration. Due to Z’s intrinsic dynamic character that results from its participation in the photoprotective xanthophyll cycle involving the carotenoids violaxanthin, antheraxanthin and zeaxanthin (VAZ), post-harvest handling practices and storage usually retain low amounts of this bioactive compound (compared to the rest of phytochemicals that are, in general, more stable). Thus, the aim of this work was to investigate in important consumed leafy vegetables the effects of different storage conditions on carotenoids (mainly Z) including i) packaging under three modified atmospheres (MAs), ii) light refrigerated supermarket storage and iii) dark refrigerated domestic storage. The results showed that an MA with low O2 and high CO2 enhanced the Z content under light. Moreover, both light and dark refrigerated storage showed dynamic and circadian pigment changes that enhanced the total VAZ pool. These results can contribute to generating practical recommendations for industries, supermarkets, and consumers when high Z content is a nutritional target.RE received a Juan de la Cierva-incorporación grant IJCI-2014-21452. JB is a holder of a PhD fellowship from the Public University of Navarre. This research was supported by research BFU 2010-15021 and CTM2014- 53902-C2-2-P from the Ministry of Education and Science of Spain and the ERDF (FEDER) and research project UPV/EHU IT-1018-16. Technical and human support by Eroski supermarkets and “Fundación Tecnova” is gratefully acknowledged

An augmented Lagrangian frictional contact formulation for nonsmooth multibody systems

This work presents a frictional contact formulation for the transient simulation of non-smooth dynamic mechanical systems composed of rigid bodies, kinematic joints and contact conditions. More precisely, we extend the non-smooth generalized-alpha scheme to account for frictional contacts. The non-smooth generalized-alpha method imposes the constraints at position and velocity levels, preventing any non-physical penetration. The formulation and the numerical behaviour of the method for frictional contact problems are studied. Finally, its performance is evaluated for several numerical examples

Drought tolerance response of high-yielding soybean varieties to mild drought: physiological and photochemical adjustments

Soybean is a crop of agronomic importance that requires adequate watering during its growth to achieve high production. In this study, we determined physiological, photochemical and metabolic differences in five soybean varieties selected from the parental lines of a nested association mapping population during mild drought. These varieties have been described as high yielding (NE3001, HY1; LD01-5907, HY2) or drought tolerant (PI518751; HYD1; PI398881, HYD2). Nevertheless, there has been little research on the physiological traits that sustain their high productivity under water-limited conditions. The results indicate that high-yielding varieties under drought cope with the shortage of water by enhancing their photoprotective defences and invest in growth and productivity, linked to a higher intrinsic water use efficiency. This is the case of the variety N-3001 (HY1), with a tolerance strategy involving a faster transition into the reproductive stage to avoid the drought period. The present study highlights the role of the physiological and biochemical adjustments of various soybean varieties to cope with water-limited conditions. Moreover, the obtained results underscore the fact that the high phenotypic plasticity among soybean phenotypes should be exploited to compensate for the low genetic variability of this species when selecting plant productivity in constrained environments.This work was supported by grants from the Spanish Ministry of Science and Innovation and FEDER funds (AGL2014-52396) and from the Basque Government (UPV/EHU-GV IT-1018-16; IT-932-16). J.B. is a holder of a PhD fellowship from the Public University of Navarre. R.E. received a Juan de la Cierva-incorporacion grant (IJCI-2014-21452)

The importance of the urea cycle and its relationships to polyamine metabolism during ammonium stress in Medicago truncatula

The ornithine–urea cycle (urea cycle) makes a signifcant contribution to the metabolic responses of lower photosynthetic eukaryotes to episodes of high nitrogen availability. In this study, we compared the role of the plant urea cycle and its relationships to polyamine metabolism in ammonium-fed and nitrate-fed Medicago truncatula plants. High ammonium resulted in the accumulation of ammonium and pathway intermediates, particularly glutamine, arginine, ornithine, and putrescine. Arginine decarboxylase activity was decreased in roots, suggesting that the ornithine decarboxylase-dependent production of putrescine was important in situations of ammonium stress. The activity of copper amine oxidase, which releases ammonium from putrescine, was signifcantly decreased in both shoots and roots. In addition, physiological concentrations of ammonium inhibited copper amine oxidase activity in in vitro assays, supporting the conclusion that high ammonium accumulation favors putrescine synthesis. Moreover, early supplementation of plants with putrescine avoided ammonium toxicity. The levels of transcripts encoding urea-cyclerelated proteins were increased and transcripts involved in polyamine catabolism were decreased under high ammonium concentrations. We conclude that the urea cycle and associated polyamine metabolism function as important protective mechanisms limiting ammonium toxicity in M. truncatula. These fndings demonstrate the relevance of the urea cycle to polyamine metabolism in higher plants.This work was supported by the grants from the Spanish Government AGL2014-52396-P (MICINN) and AGL2017-86293-P (MINECO/ FEDER) to JFM, and the Basque Government, Spain, IT-1018-16 (UPV/EHU-GV) to RE. MU is a recipient of a pre-doctoral fellowship from the Government of Navarre, Spain. JB and PLG have received pre-doctoral fellowships from the Public University of Navarre, Spain. PT has received funding from the Italian Ministry of Education, University and Research (Grant to Department of Science, University ‘Roma Tre’-‘Dipartimenti di Eccellenza’, ARTICOLO 1, COMMI 314– 337. LEGGE 423 232/2016; PRIN 2017—CUP F84I19000730005). Partial support was obtained from the Spanish State Research Agency AGL2017-83358-R (AEI/FEDER) and the Government of Aragon, Spain, Group A09-20R to YG. Open Access funding was provided by the Public University of Navarra

Numerical simulation of frictional contact problems in flexible multibody dynamics

The simulation of mechanical systems subjected to impacts and friction requires to solve highly non-linear systems of equations stemming from the Signorini’s conditions and the Coulomb friction’s law, which present several practical difficulties, which are not yet completely solved. For systems involving nonsmooth phenomena the common methods used to study the dynamics of structures with a finite element spatial discretization, such as the Newmark method, the Hilbert-Hughes-Taylor method (HHT) and the standard generalized-α method, can no longer be applied. These implicit integrators assume that the kinematic variables are smooth. However, in the presence of instantaneous changes of the velocity, which occurs due to the impact effects, these methods may produce numerical solutions with notable precision losses, non physical behaviors and the generation of fictitious energy at the contact instant. Thus, nonsmooth time integration methods able to deal with nonsmooth motion equations are needed. This work presents the development of a robust and accurate time integrator. The integrator is built upon a previously developed nonsmooth generalized-α scheme time integrator which was able to deal well with nonsmooth dynamical problems avoiding any constraint drift phenomena and capturing vibration effects without introducing too much numerical dissipation. However, when dealing with problems involving nonlinear bilateral constraints and/or flexible elements, it is necessary to adopt small time-step sizes to ensure the convergence of the numerical scheme. In order to tackle these problems more efficiently, a fully decoupled version of the nonsmooth generalized-α method is proposed in this work, avoiding these inconveniences. To account for friction, a new node-to-face contact element compatible with the proposed nonsmooth generalized-α solver has been developed. The node and face can be attached, each one, to either flexible or rigid bodies. For the sake of robustness and numerical performance, the frictional contact problem is treated using an augmented Lagrangian technique inspired by the work of Alart and Curnier for quasi-static problems. Finally, this methodology has been implemented in the general purpose finite element software Oofelie. The algorithm and the frictional contact element have been coded using the existing data structure and in a non intrusive manner, in order to preserve the compatibility with the existing utilities and the wide element library. Using this implementation several numerical experiments have been done. The results of theses examples have been compared to analytical solutions or previous numerical solutions obtained by other authors showing good agreement and convergence rate

Análisis de la respuesta de edificios unifamiliares adosados de obra de fábrica sometidos a asentamientos inducidos por tunelación

En el presente trabajo se estudia el comportamiento de la obra de fábrica como elemento estructural portante. La obra de fábrica es un material que por su constitución presenta una capacidad nula o prácticamente nula de resistir tracciones. Por ello, los edificios proyectados con este material se diseñan con formas geométricas priorizando las compresiones, como pueden ser las paredes de carga, los pilares, arcos y bóvedas. El problema resulta cuando, por razones imprevistas, la estructura se ve sometida a cargas accidentales produciéndose daños en la estructura. En las ciudades hay muchos edificios proyectados en obra de fábrica, muchas de las cuales forman parte de un patrimonio cultural importante. La tunelación en los últimos años está teniendo un gran auge, lo que hace necesario poder predecir el comportamiento que tendrían estas estructuras ante los asentamientos del terreno producidas por la tunelación. Por ello en este trabajo se estudian posibles modelos numéricos capaces de representar el comportamiento de dicho material ante este tipo de acciones, determinando la problemática y virtudes de cada uno. De forma inicial se lleva a cabo la simulación de un muro sometido a cargas de compresión y cortante documentado en la literatura mediante tres macromodelos susceptibles de ser utilizados en la modelación de estructuras de obra de fábrica, comprobando su rendimiento y fiabilidad. Continuando con la validación se realiza la simulación de un pórtico construido en obra de fábrica de un edificio sometido a acciones de asentamientos diferenciales. La validación de uno de los macromodelos estudiados anteriormente conducirá a su utilización en el análisis numérico de una vivienda unifamiliar sometida a asentamientos diferenciales producidos por la construcción de un túnel de metro. Como se dispone de un correcto levantamiento de daños y los asentamientos fueron registrados, se realiza una exhaustiva comparativa entre los daños previstos por el macromodelo y los reales. También se estudia, en el caso de los dos edificios, las diferencias y la necesidad de utilizar el método del módulo de balasto para representar de forma más real la interacción entre el suelo y la estructura