159 research outputs found

    Atomistic simulations of magnetoelastic effects on sound velocity

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    In this work, we leverage atomistic spin-lattice simulations to examine how magnetic interactions impact the propagation of sound waves through a ferromagnetic material. To achieve this, we characterize the sound wave velocity in BCC iron, a prototypical ferromagnetic material, using three different approaches that are based on the oscillations of kinetic energy, finite-displacement derived forces, and corrections to the elastic constants, respectively. Successfully applying these methods within the spin-lattice framework, we find good agreement with the Simon effect including high order terms. In analogy to experiments, morphic coefficients associated with the transverse and longitudinal waves propagating along the [001] direction are extracted from fits to the fractional change in velocity data. The present efforts represent an advancement in magnetoelastic modelling capabilities which can expedite the design of future magneto-acoustic devices

    Highly Active and Stable NiCuMo Electrocatalyst Supported on 304 Stainless Steel Porous Transport Layer for Hydrogen Evolution in Alkaline Water Electrolyzer

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    Several functionalized porous transport layers with Pt-free electrocatalysts for hydrogen evolution reaction in alkaline conditions, based on Ni, Cu, and Mo, are prepared through electrodeposition onto a 304 stainless steel mesh. Morphological characterization confirms the fabrication of electrodes with high electrochemical surface active area due to the formation of hierarchical nanostructures. Mo presence into the electrocatalysts increases the activity toward the hydrogen evolution reaction. The optimization of electrodeposition process leads to the preparation of highly active NiCuMo electrocatalyst that exhibits near zero onset overpotential and overpotentials of 15 and 113 mV at 10 and 100 mA cm(-2), respectively, in 1 m KOH electrolyte. Moreover, this electrocatalyst shows superior stability with respect to other Pt-free electrocatalysts, reaching 100 h of durability with low overpotentials value demonstrating the successful preparation of very promising functionalized porous transport layers for future-generation alkaline electrolyzers

    Size- And temperature-dependent magnetization of iron nanoclusters

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    The magnetic behavior of bcc iron nanoclusters, with diameters between 2 and 8 nm, is investigated by means of spin dynamics simulations coupled to molecular dynamics, using a distance-dependent exchange interaction. Finite-size effects in the total magnetization as well as the influence of the free surface and the surface/core proportion of the nanoclusters are analyzed in detail for a wide temperature range, going beyond the cluster and bulk Curie temperatures. Comparison is made with experimental data and with theoretical models based on the mean-field Ising model adapted to small clusters, and taking into account the influence of low coordinated spins at free surfaces. Our results for the temperature dependence of the average magnetization per atom MT, including the thermalization of the transnational lattice degrees of freedom, are in very good agreement with available experimental measurements on small Fe nanoclusters. In contrast, significant discrepancies with experiment are observed if the translational degrees of freedom are artificially frozen. The finite-size effects on MT are found to be particularly important near the cluster Curie temperature. Simulated magnetization above the Curie temperature scales with cluster size as predicted by models assuming short-range magnetic ordering. Analytical approximations to the magnetization as a function of temperature and size are proposed.Fil: Dos Santos Mendez, Gonzalo Joaquín. Universidad de Mendoza; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Aparicio, Romina Marcela. Universidad de Mendoza; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Linares, D.. Universidad Nacional de San Luis. Facultad de Ciencias Físico- Matemáticas y Naturales; ArgentinaFil: Miranda, Enrique Nestor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Tranchida, J.. Sandia National Laboratory; Estados UnidosFil: Pastor, G. M.. University Of Kasel; AlemaniaFil: Bringa, Eduardo Marcial. Universidad de Mendoza; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Mayor; Chil

    Myelolipoma of the Pelvis: A Case Report and Review of Literature

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    Myelolipomas are uncommon, benign tumors which typically occur in the adrenal glands and consist of mature adipose tissue and benign hematopoietic components. Myelolipomas can occur outside of the adrenal glands, but the presacral region, retroperitoneum, pelvis, and mediastinum are unusual locations for these tumors. It is important to recognize this entity in these locations since they can attain massive sizes leading to pressure symptoms and need to be differentiated from the malignant tumors like liposarcomas. We present a myelolipoma case in the presacral region. Our case illustrates the clinical approach of these tumors in such unusual locations

    Resequencing

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    [ES] La revolución que supone la secuenciación de próxima generación está permitiendo la resecuenciación del genoma completo (WGRS) de cientos o incluso miles de ejemplares de cultivos básicos y especies modelo. Con el lanzamiento de su genoma de referencia, progresivamente se están emprendiendo proyectos WGRS también para otras especies de plantas en una amplia variedad de estudios. En berenjena común (Solanum melongena L.), aunque se ha publicado un primer borrador de la secuencia del genoma de referencia, hasta el momento no se han realizado estudios de resecuenciación. En este capítulo presentamos los primeros resultados de la resecuenciación de ocho accesiones, siete de berenjena común y una del pariente silvestre S. incanum L., que corresponden a los progenitores de un cruce multiparental de generación avanzada (MAGIC) población que se encuentra actualmente en desarrollo utilizando la secuencia del genoma de la berenjena recién desarrollada que se presenta en el Cap. 7 de este libro. Se identificaron más de diez millones de polimorfismos entre las accesiones, el 90% de ellos en el S. incanum silvestre relacionado, lo que confirma la erosión genética de la berenjena común cultivada. Entre los progenitores de la población MAGIC, el patrón de distribución de polimorfismos comunes a lo largo de los cromosomas ha revelado posibles huellas de introgresión ancestral de cruces interespecíficos. El conjunto de polimorfismos se ha anotado extensamente y actualmente se está utilizando para análisis adicionales con el fin de genotipar eficientemente la población MAGIC en curso y diseccionar rasgos agronómicos y morfológicos importantes. La información proporcionada en este primer estudio de resecuenciación en berenjena será extremadamente útil para ayudar al fitomejoramiento a desarrollar nuevas variedades mejoradas y resistentes para enfrentar futuras amenazas y desafíos.[EN] The next-generation sequencing revolution is allowing the whole-genome resequencing (WGRS) of hundreds or even thousands of accessions for staple crops and model species. With the release of their reference genome, progressively also other plants, species are undertaking WGRS projects for a broad variety of studies. In common eggplant (Solanum melongena L.), although a first draft of the reference genome sequence has been published, no resequencing studies have been performed so far. In this chapter, we present the first results of the resequencing of eight accessions, seven of common eggplant and one of the wild relative S. incanum L., that correspond to the parents of a multi-parent advanced generation inter-cross (MAGIC) population that is currently under develop- ment using the newly developed eggplant genome sequence presented in Chap. 7 of this book. Over ten million polymorphisms were identified among the accessions, 90% of them in the wild related S. incanum, confirming the genetic erosion of the cultivated common eggplant. Among the MAGIC population parents, the common polymorphism distribu- tion pattern along the chromosomes has revealed possible footprints of ancestral intro- gression from interspecific crosses. The set of polymorphisms has been extensively anno- tated and currently is being used for further analyses in order to efficiently genotype the ongoing MAGIC population and to dissect important agronomic and morphological traits. The information provided in this first resequencing study in eggplant will be extremely helpful to assist plant breeding to develop new improved and resilient varieties to face future threats and challenges.This work has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No 677379 (G2P-SOL project: Linking genetic resources, genomes and phenotypes of Solanaceous crops) and from Spanish Ministerio de Economía, Industria y Competitividad and Fondo Europeo de Desarrollo Regional (grant AGL2015-64755-R from MINECO/FEDER).Prohens Tomás, J.; Vilanova Navarro, S.; Gramazio, P. (2019). Resequencing. En The Eggplant Genome. Springer. 81-89. http://hdl.handle.net/10251/181875S818

    Sequencing and Analysis of Plastid Genome in Mycoheterotrophic Orchid Neottia nidus-avis

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    Plastids are the semiautonomous organelles that possess their own genome inherited from the cyanobacterial ancestor. The primary function of plastids is photosynthesis so the structure and evolution of plastid genomes are extensively studied in photosynthetic plants. In contrast, little is known about the plastomes of nonphotosynthetic species. In higher plants, plastid genome sequences are available for only three strictly nonphotosynthetic species, the liverwort Aneura mirabilis and two flowering plants, Epifagus virginiana and Rhizanthella gardneri. We report here the complete sequence of a plastid genome of nonphotosynthetic mycoheterotrophic orchid Neottia nidus-avis, determined using 454 pyrosequencing technology. It was found to be reduced in both genome size and gene content; this reduction is however not as drastic as in the other nonphotosynthetic orchid, R. gardneri. Neottia plastome lacks all genes encoding photosynthetic proteins, RNA polymerase subunits but retains most genes of translational apparatus. Those genes that are retained have an increased rate of both synonymous and nonsynonymous substitutions but do not exhibit relaxation of purifying selection either in Neottia or in Rhizanthella

    On-chip pressure measurements and channel deformation after oil absorption

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    Microfluidic channels moulded from the soft polymer poly(dimethylsiloxane) (PDMS) are widely used as a platform for mimicking biological environments, and can be used for the simulation of fluid filled structures such as blood and lung vessels. The control of pressure and flow rate within these structures is vital to mimic physiological conditions. The flexibility of PDMS leads to pressure-induced deformation under flow, leading to variable flow profiles along a device. Here, we investigate the change in Young’s modulus of microfluidic channels due to infiltration of mineral oil, a PDMS permeable fluid, and how this affects the resulting pressure profile using a novel pressure measurement method. We found a 53% decrease in Young’s modulus of PDMS due to mineral oil absorption over the course of 3 h accounted for lower internal pressure and larger channel deformation compared to fresh PDMS at a given flow rate. Confocal fluorescence microscopy used to image channel profiles before and after the introduction of mineral oil showed a change in pressure-induced deformation after infiltration of the oil. Atomic force microscopy (AFM) nanoindentation was used to measure Young’s modulus of PDMS before (2.80±0.032.80±0.03 MPa) and after (1.32±0.041.32±0.04 MPa) mineral oil absorption. Raman spectroscopy showed the infiltration of mineral oil into PDMS from channel walls and revealed the diffusion coefficient of mineral oil in PDMS

    WHOLE-GENOME RE-SEQUENCING OF TWO TOMATO LANDRACES REVEALS SEQUENCE VARIATIONS UNDERPINNING KEY ECONOMICALLY IMPORTANT TRAITS

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    In the post-genomic era, one of the major challenges is the identification of alleles directly responsible for phenotype variation among different genotypes within the same species. Tomato is a model crop for understanding the development and ripening of climacteric fleshy fruits, and it is also known to be an important source of health-promoting compounds. In addition, cultivated tomato germplasm shows a high phenotypic variation despite its very low genetic diversity. Toward the identification of sequence variations responsible for stress tolerance, high fruit quality and long shelf life, we re-sequenced the genomes of two traditional landraces grown in the Campania region (Southern Italy). Crovarese, belonging to the Corbarino type (COR), and Lucariello (LUC) are typically grown under low water regimes and produce highly appreciated fruits, which can be stored up to 4-8 months. We generated 65.8M and 56.4M of paired-end 30-150 bp reads with an average insert size of 380 bp (± 52bp) and 364 bp (± 49bp) for COR and LUC, respectively. A referenceguided assembly was performed using 'Heinz 1706' as a reference genome. We estimated a mean coverage depth of ~15X for COR and 13X for LUC. Comparing the genomes of COR and LUC with that of 'Heinz 1706' we found a similar distribution of SNPs (68.8% vs. 69.9%, respectively), small deletions (8.9% vs. 8.6%) and small insertions (22.1% vs. 21.3%). Through a de novo assembly of the unmapped reads we identified 29 and 36 new contigs in COR and LUC, respectively. The new contigs could be assigned to the chromosomes thanks to the use of a splitread approach. On average, the contigs inserted in COR were 654bp, whereas those inserted in LUC were 616bp. Using custom RNA-seq data, a total of 43054 and 44576 gene loci were annotated in COR and LUC, corresponding to 62369 and 65094 transcripts, respectively. Among the genes showing a similar structure in COR and LUC compared to 'Heinz 1706', we identified ~2000 and 1700 SNPs causing potentially disruptive effects on the function of 1371 and 1201 genes in COR and LUC, respectively. Interesting GO categories highly represented in genes affected by sequence changes were identified. Major variations were present in stress-responsive genes as well as in fruit quality and development-related genes. From a practical perspective, the identified SNPs and InDels are candidate polymorphisms to track DNA variations associated to key traits of economic interest

    Modulation of hepatic inflammation and energy-sensing pathways in the rat liver by high-fructose diet and chronic stress

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    Purpose High-fructose consumption and chronic stress are both associated with metabolic inflammation and insulin resistance. Recently, disturbed activity of energy sensor AMP-activated protein kinase (AMPK) was recognized as mediator between nutrient-induced stress and inflammation. Thus, we analyzed the effects of high-fructose diet, alone or in combination with chronic stress, on glucose homeostasis, inflammation and expression of energy sensing proteins in the rat liver. Methods In male Wistar rats exposed to 9-week 20% fructose diet and/or 4-week chronic unpredictable stress we measured plasma and hepatic corticosterone level, indicators of glucose homeostasis and lipid metabolism, hepatic inflammation (pro- and anti-inflammatory cytokine levels, Toll-like receptor 4, NLRP3, activation of NF kappa B, JNK and ERK pathways) and levels of energy-sensing proteins AMPK, SIRT1 and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1 alpha). Results High-fructose diet led to glucose intolerance, activation of NF kappa B and JNK pathways and increased intrahepatic IL-1 beta, TNF alpha and inhibitory phosphorylation of insulin receptor substrate 1 on Ser(307). It also decreased phospho-AMPK/AMPK ratio and increased SIRT1 expression. Stress alone increased plasma and hepatic corticosterone but did not influence glucose tolerance, nor hepatic inflammatory or energy-sensing proteins. After the combined treatment, hepatic corticosterone was increased, glucose tolerance remained preserved, while hepatic inflammation was partially prevented despite decreased AMPK activity. Conclusion High-fructose diet resulted in glucose intolerance, hepatic inflammation, decreased AMPK activity and reduced insulin sensitivity. Chronic stress alone did not exert such effects, but when applied together with high-fructose diet it could partially prevent fructose-induced inflammation, presumably due to increased hepatic glucocorticoids
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