Multigrid solvers for multipoint flux approximations of the Darcy problem on rough quadrilateral grids

In this work, an efficient blackbox-type multigrid method is proposed for solving multipoint flux approximations of the Darcy problem on logically rectangular grids. The approach is based on a cell-centered multigrid algorithm, which combines a piecewise constant interpolation and the restriction operator by Wesseling/Khalil with a line-wise relaxation procedure. A local Fourier analysis is performed for the case of a Cartesian uniform grid. The method shows a robust convergence for different full tensor coefficient problems and several rough quadrilateral grids.Francisco J. Gaspar has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska–Curie grant agreement no. 705402, POROSOS. The work of Laura Portero is supported by the Spanish project MTM2016-75139-R (AEI/FEDER, UE) and the Young Researchers Programme 2018 from the Public University of Navarre. Andrés Arrarás acknowledges support from the Spanish project PGC2018-099536-A-I00 (MCIU/AEI/FEDER, UE) and the Young Researchers Programme 2018 from the Public University of Navarre. The work of Carmen Rodrigo is supported by the Spanish project PGC2018-099536-A-I00 (MCIU/AEI/FEDER, UE) and the DGA (Grupo de referencia APEDIF, ref. E24_17R)

Mixed-dimensional geometric multigrid methods for single-phase flow in fractured porous media

This paper deals with the efficient numerical solution of single-phase flow problems in fractured porous media. A monolithic multigrid method is proposed for solving two-dimensional arbitrary fracture networks with vertical and/or horizontal possibly intersecting fractures. The key point is to combine two-dimensional multigrid components (smoother and intergrid transfer operators) in the porous matrix with their one-dimensional counterparts within the fractures, giving rise to a mixed-dimensional geometric multigrid method. This combination seems to be optimal since it provides an algorithm whose convergence matches the multigrid convergence factor for solving the Darcy problem. Several numerical experiments are presented to demonstrate the robustness of the monolithic mixed-dimensional multigrid method with respect to the permeability of the fractures, the grid size, and the number of fractures in the network.The work of the first and fourth authors was supported by Spanish project PGC2018-099536-A-I00 (MCIU/AEI/FEDER, UE). The work of the second author was supported by the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement 705402, POROSOS. The work of the third author was partially supported by the Spanish project FEDER/MCYT MTM2016-75139-R. The work of the fourth author was supported by the DGA (Grupo de referencia APEDIF, ref. E24 17R)

Tissue inhibitor of metalloproteinase-1 (TIMP-1) regulates mesenchymal stem cells through let-7f microRNA and Wnt/β-catenin signaling

Tissue inhibitor of metalloproteinases 1 (TIMP-1) is a matrix metalloproteinase (MMP)-independent regulator of growth and apoptosis in various cell types. The receptors and signaling pathways that are involved in the growth factor activities of TIMP-1, however, remain controversial. RNA interference of TIMP-1 has revealed that endogenous TIMP-1 suppresses the proliferation, metabolic activity, and osteogenic differentiation capacity of human mesenchymal stem cells (hMSCs). The knockdown of TIMP-1 in hMSCs activated the Wnt/β-catenin signaling pathway as indicated by the increased stability and nuclear localization of β-catenin in TIMP-1–deficient hMSCs. Moreover, TIMP-1 knockdown cells exhibited enhanced β-catenin transcriptional activity, determined by Wnt/β-catenin target gene expression analysis and a luciferase-based β-catenin– activated reporter assay. An analysis of a mutant form of TIMP-1 that cannot inhibit MMP indicated that the effect of TIMP-1 on β-catenin signaling is MMP independent. Furthermore, the binding of CD63 to TIMP-1 on the surface of hMSCs is essential for the TIMP-1–mediated effects on Wnt/β-catenin signaling. An array analysis of microRNAs (miRNAs) and transfection studies with specific miRNA inhibitors and mimics showed that let-7f miRNA is crucial for the regulation of β-catenin activity and osteogenic differentiation by TIMP-1. Let-7f was up-regulated in TIMP-1–depleted hMSCs and demonstrably reduced axin 2, an antagonist of β-catenin stability. Our results demonstrate that TIMP-1 is a direct regulator of hMSC functions and reveal a regulatory network in which let-7f modulates Wnt/β-catenin activity

Hydroponics as a valid tool to assess arsenic availability in mine soils

The low solubility of As in mine soils limits its phytoavailability. This makes the extrapolation of data obtained under hydroponic conditions unrealistic because the concentration in nutrient solution frequently overexposes plants to this metalloid. This work evaluates whether As supply in hydroponics resembles, to some extent, the As phytoavailable fraction in soils and the implications for phytoremediation. Phytotoxicity of As, in terms of biomass production, chlorophyll levels, and As concentrations in plants, was estimated and compared in both soils and hydroponics. In order for hydroponic conditions to be compared to soil conditions, plant exposure levels were measured in both cultures. Hydroponic As concentration ranging from 2-8 μM equated to the same plant organ concentrations from soils with 700-3000 mg kg-1. Total and extractable As fractions exceeded those values, but As concentrations in pore water were bellow them. According to our results (i) hydroponics should include doses in the range 0-10 μM As to allow the extrapolation of the results to As-polluted soils, and (ii) phytoextraction of As in mining sites will be limited by low As phytoavailabilityThis study was supported by the Spanish Ministry of Education and Science, project CTM 2007-66401-CO2/TECNO, and by Comunidad de Madrid, project S-0505/AMB/029

Techniques for the In Vitro Production of Queens in Stingless Bees (Apidae, Meliponini)

Considering the ecological importance of stingless bees as caretakers and pollinators of a variety of native plants makes it necessary to improve techniques which increase of colonies’ number in order to preserve these species and the biodiversity associated with them. Thus, our aim was to develop a methodology of in vitro production of stingless bee queens by offering a large quantity of food to the larvae. Our methodology consisted of determining the amount of larval food needed for the development of the queens, collecting and storing the larval food, and feeding the food to the larvae in acrylic plates. We found that the total average amount of larval food in a worker bee cell of F. varia is approximately 26.70 } 3.55 μL. We observed that after the consumption of extra amounts of food (25, 30, 35 and 40 μL) the larvae differentiate into queens (n = 98). Therefore, the average total volume of food needed for the differentiation of a young larva of F. varia queen is approximately 61.70 } 5.00 μL. In other words; the larvae destined to become queens eat 2.31 times more food than the ones destined to become workers. We used the species Frieseomelitta varia as a model, however the methodology can be reproduced for all species of stingless bees whose mechanism of caste differentiation depends on the amount of food ingested by the larvae. Our results demonstrate the effectiveness of the in vitro technique developed herein, pointing to the possibility of its use as a tool to assist the production of queens on a large scale. This would allow for the artificial splitting of colonies and contribute to conservation efforts in native bees

Protein extract and activity antioxidant of corn (Zea mays) and sorghum (Sorghum bicolor L. Moench) grains

Brazil is a major producer of grains, such as sorgh um and corn, which are used for export. Sorghum and corn grains have in its composition 9.5% and 9. 8 protein, respectively. Proteins are the most abundant and most diverse functions in living syste ms molecules. Currently, food proteins are increasingly recognized as a source of beneficial b ioactive peptides, and they are physiologically released during digestion. The aim of the work was to evaluate the protein extraction (four methods) and antioxidant activity of sorghum and corn grains . The proximal composition of grains was evaluated in relation to moisture, protein, lipids and ash contents, furthermore were quantified proteins concentration and antioxidant activity by FRAP method in the four extracts. The corn and sorghum grains were ground, homogenized (60 mesh) a nd stored at 5°C until analysis. The protein extraction utilized were: 1) dichloromethane/methan ol; 2) NH 4 HCO 3 (5mM, pH 8.0)/heat treatment; 3) water/ethanol/heat treatment; and 4) alkaline ex traction and precipitation. The corn and sorghum presented, protein 6.62% and 9.87%, lipids 4.45% an d 4.32%, moisture 8.87% and 8.23%, ash 0.96% and 1.15%, carbohydrates 79.01% and 76.41%, t otalizing a caloric value of 382.9 and 384.1 Kcal g -1 , respectively. The 2 and 3 methods in corn grain p resented highest protein content 133.16 and 142.24 μ g g -1 , respectively. In sorghum grain, methods 1, 2 and 3 presented protein content between 173.59 – 223.63 μg g -1 . The antioxidant activity of protein extracts was between 0.90 – 9.73μM of ferrous sulphate for corn and between 4.4 1 – 15.04μ M of ferrous sulphate for sorghum. The best results in the extraction using the method 3 for both grains could be due to the structure of proteins (zein and kafirins) which are soluble in a lcoholic solutions and insoluble in water. In conclusion, method 3 - water/ethanol/heat treatment (corn: 142.24 μg g -1 and sorghum: 223.63 μg g - 1 ) and method 3 (corn: 9.73 μM and sorghum: 15.04 μ M ) showed the best results for extracting protein and antioxidant activity, respectively. The protein extracts obtainedhave great potential as natural antioxidant

Protein extraction of the sunflower grains and bran

[Excerpt] Sunflower grains have a high protein content (24%) with high quality amino acid profile and are used to extraction of vegetable oil. The sunflower brain is produced during the processing of vegetal oil. The sunflower grains and by-product (bran) can be used with raw materials for obtaining peptides with bioactivity for protein hydrolysis after extraction, since they have great amount of essential amino acids, typically nonpolar, soluble and insoluble alcoholic solutions in water. The aim of this work was to evaluate protein extraction (three methods) of sunflower grains and bran. (...

A proteomics study of chilling injury in tomato fruit, a low-temperature stress-induced physiological disorder affecting fruit quality

Trabajo presentado a la conferencia "Molecular Basis of Plant Stress" celebrado en Bulgaria del 21 al 23 de septiembre de 2011.-- FP7 REGPOT Project "BioSupport".Tomato (Solanum lycopersicum L.) is the second most cultivated horticultural crop in the world in terms of harvested area and production, after the potato (FAOSTAT 2011, data from 2009). A main problem regarding its postharvest life is its sensitivity to low temperature stress during refrigerated storage, which constitutes a main obstacle for its long-term commercialization. This sensitivity is reflected in the physiopathy of chilling injury (CI), which negatively affects the final fruit quality. The main symptoms of CI-affected fruits are skin depressions, tissue decomposition and impaired ripening, which results in deficient flavour and aroma. Physiological and biochemical events involved in CI progress have been extensively described, but the precise molecular mechanisms that ultimately regulate the plant response to cold stress remain unclear. In order to investigate this response at molecular level in tomato fruit a proteomics strategy has undertaken. The proteome analysis provides a direct insight on the changes undergone by proteins, which are the major functional determinants of the cell machinery, in a certain biological situation such as low temperature stress. The protein expression profile of chilled tomato fruits has been compared with fruits stored at nonchilling temperature (control). The protein analysis has been performed by two-dimensional differential-in-gel-electrophoresis (2D-DIGE), and mass spectrometry of protein spots was applied to identify proteins differentially expressed. Comparative analysis revealed significant changes in abundance of 31 identified proteins between the proteomes of chilled and control fruits. Major modifications in the expression profile are related to those proteins specifically involved in stress (chaperonins and heat-shock proteins); cell wall biochemistry (hydrolytic enzymes), and carbohydrate metabolism (enzymes involved in glycolisis, tricarboxylic acids cycle, photosynthesis and sucrose biosynthesis).This work was supported by the Spanish Ministry of Science and Innovation (MICINN) through grant and PIE2009-40I080, and by the Council of Science and Technology from the Spanish Region of Murcia (Fundación SENECA) through grant no. 04553/GERM/06.Peer Reviewe

A new fast-acting backup protection strategy for embedded MVDC links in future distribution networks

This paper presents a new fast-acting backup protection strategy for future hybrid ac-dc distribution networks. By examining the impedance measured by a distance protection relay measuring from the “ac-side” of the network, a unique characteristic is established for faults occurring on the “dc-side” of an embedded medium-voltage dc (MVDC) link, interconnecting two 33 kV distribution network sections. Based on the identified impedance characteristic, appropriate settings are developed and deployed on a verified software model of a commercially available distance protection relay. To remain stable for ac-side faults, it is found that the tripping logic of the device must be altered to provide correct time grading between standard, ac, protection zones and the fast-acting dc region, which can identify faults on the dc system within 40 ms. An additional confirmatory check is also employed to reduce the likelihood of mal-operation. Trials on a test system derived from an actual distribution network, which employs distance protection, are shown to provide stable operation for both ac-side and dc-side pole-pole and pole-pole-ground fault

A Metabolomic Approach To Detect Effects of Salmon Farming on Wild Saithe (Pollachius virens) Populations

A metabolomics approach was used to analyze effects of salmon farming on wild saithe (Pollachius virens) populations. Saithe fish were captured at two salmon farms and at two control locations around the island of Hitra, Norway. Changes in diet seem to drive changes in metabolic status of fishes. The liver and muscle tissues, from the fishes captured around the farm, showed higher levels of lactate and certain amino acids (glutamine, glutamate, and alanine) and lower levels of glucose and choline than the fishes captured in the control locations, far from the farm locations. The higher levels of lactate and amino acids could be related to the facility of obtaining food around the farm and the deficit in choline to the deficit of this nutrient in the salmon feed. At each location the fish were captured with either benthic gill nets and automatic jigging machines, and this feature showed also variations in different metabolites.This research was funded by the Norwegian Seafood Research Fund through the project “Evaluation of actions to promote sustainable coexistence between salmon culture and coastal fisheries, ProCoEx” (Project 900772). K.T.-G. was supported by a grant from Iceland, Liechtenstein, and Norway through the EEA Financial Mechanism