Biomimetic flow fields for proton exchange membrane fuel cells: A review of design trends

Bipolar Plate design is one of the most active research fields in Polymer Electrolyte Membrane Fuel Cells (PEMFCs) development. Bipolar Plates are key components for ensuring an appropriate water management within the cell, preventing flooding and enhancing the cell operation at high current densities. This work presents a literature review covering bipolar plate designs based on nature or biological structures such as fractals, leaves or lungs. Biological inspiration comes from the fact that fluid distribution systems found in plants and animals such as leaves, blood vessels, or lungs perform their functions (mostly the same functions that are required for bipolar plates) with a remarkable efficiency, after millions of years of natural evolution. Such biomimetic designs have been explored to date with success, but it is generally acknowledged that biomimetic designs have not yet achieved their full potential. Many biomimetic designs have been derived using computer simulation tools, in particular Computational Fluid Dynamics (CFD) so that the use of CFD is included in the review. A detailed review including performance benchmarking, time line evolution, challenges and proposals, as well as manufacturing issues is discussed.Ministerio de Ciencia, Innovación y Universidades ENE2017-91159-EXPMinisterio de Economía y Competitividad UNSE15-CE296

A Partial Allocation Local Search Matheuristic for Solving the School Bus Routing Problem with Bus Stop Selection

This paper addresses the school bus routing problem with bus stop selection, which jointly handles the problems of determining the set of bus stops to visit, allocating each student to one of these bus stops and computing the routes that visit the selected bus stops, so that the total routing cost is minimized and the walking distance of the students is limited by a given value. A fast and efficient matheuristic is developed based on an innovative approach that first partially allocates the students to a set of active stops that they can reach, and computes a set of routes that minimizes the routing cost. Then, a refining process is performed to complete the allocation and to adapt the routes until a feasible solution is obtained. The algorithm is tested on a set of benchmark instances. The computational results show the efficiency of the algorithm in terms of the quality of the solutions yielded and the computing time

A decision tool based on bilevel optimization for the allocation of water resources in a hierarchical system

This paper addresses the optimal allocation of water among competing stakeholders during a finite planning horizon. We focus on those water systems where there are two levels of decision making organized according to a hierarchical framework. At the upper level, a central authority allocates water to demand points having regard to environmental and sustainability issues as well as balancing water users' supply/demand. At the lower level of the hierarchy, demand point managers allocate water to users prioritizing economic strategies. On the other hand, when it comes to allocating limited resources that affect public welfare, the authority in charge can also use different political instruments such as fees to influence the decisions made at those levels of decision making that are not directly within its competence. We propose a multiobjective multifollower bilevel optimization problem that aims to fulfill the central authority goals while including the reaction of the demand point managers in terms of optimization problems as constraints. Using the well-known Karush–Kuhn–Tucker approach, we transform the bilevel model into an equivalent multiobjective mixed-integer single-level model for which we provide tight big-M values. For the purpose of showing the versatility of the model, extensive computational experiments on a set of instances have been carried out. The results show that the optimization problem can be solved to optimality in small computing times using off-the-shelf mixed-integer solvers even for complex water systems and long planning periods. In addition, they illustrate the effect of imposing fees on the achievement of the central authority's objectives

Aportaciones al conocimiento del género Equisetum L. II. E. x litorale Rupr.

Se realiza una descripción detallada de los caracteres morfológicos y anatomo-histológicos de Equisetum n litorale Rupr. (E. arvense x E. fluviatile).On réalise una description détaillée des caractères anatomo-histologiques et morphologiques de Equisetum x litorale Rupr. (E. arvense x E. fluviale )

Determination of enzymatic activities using a miniaturized system as a rapid method to assess soil quality

Soil quality determination requires the analysis of a number of soil attributes using different approaches. In recent years, one of the most promising approaches has been the determination of enzymatic activities. Generally, only a few enzymes have been analysed and related with other parameters, such as total carbon, nitrogenous content or microbial biomass carbon. The aim of this work was to investigate the possible use of the API ZYM strip, a semi-quantitative miniaturised system that determines 19 enzymatic activities, to study soil quality. To this end, we tested the system in different soil types, including albicArenosols, mollicLeptosols, rendzicLeptosols, haplicLeptosols, and calcaricRegosols. Fresh samples were sifted in a 2-mm sieve in the field and soil extracts were prepared by mixing 2-20 g (depending on the soil horizon characteristics) from each sample with 2-20 ml of sterile water. Next 65 μl aliquots of the supernatant extract were placed into each API ZYM microtube and were incubated at 37ºC for 16 h. Our results show significant qualitative and quantitative differences among the different soil types studied, with soil characteristics and biological properties correlating with biochemical parameters. The results provide useful information to not only assess soil quality, but also to determine soil degradation. As a whole, our results suggest that the use of the API ZYM system could prove most useful in different soil environmental studies. Finally, some suggestions are presented such as modifications to the system which could improve its application in this field

Sleep-Related Falling Out of Bed in Parkinson's Disease

Background and purposeSleep-related falling out of bed (SFOB), with its potential for significant injury, has not been a strong focus of investigation in Parkinson's disease (PD) to date. We describe the demographic and clinical characteristics of PD patients with and without SFOB.MethodsWe performed a retrospective analysis of 50 consecutive PD patients, who completed an REM sleep behavior disorder screening questionnaire (RBDSQ), questionnaires to assess for RBD clinical mimickers and questions about SFOB and resulting injuries. Determination of high risk for RBD was based on an RBDSQ score of 5 or greater.ResultsThirteen patients reported history of SFOB (26%). Visual hallucinations, sleep-related injury, quetiapine and amantadine use were more common in those patients reporting SFOB. Twenty-two patients (44%) fulfilled criteria for high risk for RBD, 12 of which (55%) reported SFOB. Five patients reported injuries related to SFOB. SFOB patients had higher RBDSQ scores than non-SFOB patients (8.2±3.0 vs. 3.3±2.0, p<0.01). For every one unit increase in RBDSQ score, the likelihood of SFOB increased two-fold (OR 2.4, 95% CI 1.3-4.2, p<0.003).ConclusionsSFOB may be a clinical marker of RBD in PD and should prompt confirmatory polysomnography and pharmacologic treatment to avoid imminent injury. Larger prospective studies are needed to identify risk factors for initial and recurrent SFOB in PD

Archaeological prospection with corona and wv-3 satellite imagery of the archaeological site of zar tepe (uzbekistan)

Abstract. The use of different data from satellite platforms for archaeological prospecting and remote sensing has been applied since the end of the 20th century. Although the current use of drones with different visible and multispectral sensors for small areas has partially replaced in some cases the use of this type of satellite information due to its higher spatial resolution. The historical importance of satellite imagery is essential to find out about and compare the transformations of the archaeological landscape of the last 60 years since the CORONA satellite program started in 1960. In this paper we propose the evaluation of a proposal for the automation of processes of two photographic reconnaissance correlative satellite programs CORONA (1960-1972), HEXAGON (1971-1986) declassified since 1995 and 2011 respectively, and the commercial satellite WorldView-3 (WV3) (2014) for use in the detection of buried archaeological structures at the archaeological site of Zar Tepe in the southeast of Uzbekistan. This is a site located in the Surkhan Darya region very little known between the first century BC and the fourth century AD. This methodology is part of the IPAEB project (International Pluridisciplinary Archaeological Expedition to Bactria) led by the University of Barcelona, the University of Salamanca and recently in 2019 the University of Zaragoza. IPAEB was started in 2006 in the South of Uzbekistan and is currently trying to explore the urban planning of the Zar Tepe archaeological site and the elements that make up its natural physical environment: evidence of communication routes, smallholdings, irrigation channels, fences and sources of raw materials

Ensayo biogeográfico de la Pteridoflora valenciana

En el presente trabajo se realiza un análisis comparativo de las pteridofloras de los diiferentes sectores fitogeográficos (sensu Costa, 1986) que integran la Comunidad Valenciana.The present paper deals with the biogeography and of pteridophytes in the Comunidad Valenciana (Levante, Spain), following the present chorological division of this area

How the other half lives: CRISPR-Cas's influence on bacteriophages

CRISPR-Cas is a genetic adaptive immune system unique to prokaryotic cells used to combat phage and plasmid threats. The host cell adapts by incorporating DNA sequences from invading phages or plasmids into its CRISPR locus as spacers. These spacers are expressed as mobile surveillance RNAs that direct CRISPR-associated (Cas) proteins to protect against subsequent attack by the same phages or plasmids. The threat from mobile genetic elements inevitably shapes the CRISPR loci of archaea and bacteria, and simultaneously the CRISPR-Cas immune system drives evolution of these invaders. Here we highlight our recent work, as well as that of others, that seeks to understand phage mechanisms of CRISPR-Cas evasion and conditions for population coexistence of phages with CRISPR-protected prokaryotes.Comment: 24 pages, 8 figure