174 research outputs found
Thermomagnetic detection of recrystallization in FeCoNbBCu nanocrystalline alloys
The recrystallization process in FeCoNbBCu nanocrystallinealloys is evidenced from thermomagnetic results as a significant decrease in magnetization at the second crystallization stage. The lowering in the volume fraction of α-FeCo crystals indicates that some of these crystals contribute to the boride phases formed. Electron microscopy images reveal that the final microstructure consists of large crystals (∼500 nm) of a fcc (FeCo)23B6(FeCo)23B6 phase and small crystals (∼20 nm) of bcc α-FeCo and of some boride phases as such (FeCo)2B
The cosmic evolution of the spatially-resolved star formation rate and stellar mass of the CALIFA survey
We investigate the cosmic evolution of the absolute and specific star
formation rate (SFR, sSFR) of galaxies as derived from a spatially-resolved
study of the stellar populations in a set of 366 nearby galaxies from the
CALIFA survey. The analysis combines GALEX and SDSS images with the 4000 break,
H_beta, and [MgFe] indices measured from the datacubes, to constrain parametric
models for the SFH, which are then used to study the cosmic evolution of the
star formation rate density (SFRD), the sSFR, the main sequence of star
formation (MSSF), and the stellar mass density (SMD). A delayed-tau model,
provides the best results, in good agreement with those obtained from
cosmological surveys. Our main results from this model are: a) The time since
the onset of the star formation is larger in the inner regions than in the
outer ones, while tau is similar or smaller in the inner than in the outer
regions. b) The sSFR declines rapidly as the Universe evolves, and faster for
early than for late type galaxies, and for the inner than for the outer regions
of galaxies. c) SFRD and SMD agree well with results from cosmological surveys.
At z< 0.5, most star formation takes place in the outer regions of late spiral
galaxies, while at z>2 the inner regions of the progenitors of the current E
and S0 are the major contributors to SFRD. d) The inner regions of galaxies are
the major contributor to SMD at z> 0.5, growing their mass faster than the
outer regions, with a lookback time at 50% SMD of 9 and 6 Gyr for the inner and
outer regions. e) The MSSF follows a power-law at high redshift, with the slope
evolving with time, but always being sub-linear. f) In agreement with galaxy
surveys at different redshifts, the average SFH of CALIFA galaxies indicates
that galaxies grow their mass mainly in a mode that is well represented by a
delayed-tau model, with the peak at z~2 and an e-folding time of 3.9 Gyr.Comment: 23 pages, 16 figures, 6 tables, accepted for publication in Astronomy
& Astrophysics. *Abridged abstract
Results of the 2004 Spanish Experimental Fishing in NAFO Subarea 1
An experimental fishing was carried out with three bottom trawlers commercial Spanish vessels from July to December
of the year 2004 in the Subarea 1. The main objective of the experimental fishing was to search for cephalopods species
concentrations inside the territorial waters of Greenland. During the experimental fishing a scientific observer stayed on
board each vessel to collect effort data, catches and yields by haul and Division. The observers carried out length
distribution samplings of the following species: Reinhardtius hippoglossoides, Pandalus borealis, Gadus morhua,
Sebastes spp., Hippoglossoides platessoides and Macrourus berglax. Biological samplings of R. hippoglossoides, P.
borealis, H. platessoides, G. morhua and M. berglax were also carried out. Otoliths of Greenland halibut (1 356) and
Atlantic cod (739) were collected for age determination. Greenland halibut was the main species caught and the
cephalopods, target species, have not been found in the experimental fishing
Light-activated electroforming in ITO/ZnO/p-Si resistive switching devices
We report on light-activated electroforming of ZnO/p-Si heterojunction memristors with transparent indium tin oxide as the top electrode. Light-generated electron-hole pairs in the p-type substrate are separated by the external electric field and electrons are injected into the active ZnO layer. The additional application of voltage pulses allows achieving different resistance states that end up in the realization of the low resistance state (LRS). This process requires much less voltage compared to dark conditions, thus avoiding undesired current overshoots and achieving a self-compliant device. The transport mechanisms governing each resistance state are studied and discussed. An evolution from an electrode-limited to a space charge-limited transport is observed along the electroforming process before reaching the LRS, which is ascribed to the progressive formation of conductive paths that consequently induce the growth of conductive nanofilaments through the ZnO layer. This work was financially supported by the Spanish Ministry of Economy and Competitiveness (Project Nos. TEC2012-38540-C02-01 and TEC2016-76849-C2-1-R). O.B. also acknowledges the subprogram "Ayudas para Contratos Predoctorales para la Formación de-Doctores" from the Spanish Ministry of Economy and Competitiveness for economical support. J.L.F. acknowledges the subprogram "Ayudas para la Formación de Profesorado Universitario" (No. FPU16/06257) from the Spanish Ministry of Education, Culture and Sports for economical support. X.P., C.L., and C.G. are grateful to C. Frilay for his expertise in the maintenance of the sputtering setup used for the growth of the ZnO films
Effect of the particle size and solids volume fraction on the thermal degradation behaviour of Invar 36 feedstocks
Degradation kinetics and the thermal stability of Invar 36 powder injection moulding feedstocks (PIM) based on cellulose acetate butyrate (CAB) and polyethylene glycol (PEG) binders were investigated using simultaneous thermogravimetric analysis (STA) and differential scanning calorimetry (DSC). The initial decomposition temperature (IDT) and the integral procedure decomposition temperature (IPDT) were used to analyse the thermal stability of the binder system as a function of the solid loading content and powder particle size. The degradation kinetics was studied, and the process apparent activation energies were assessed using isoconversional methods. All the methodologies revealed changes in the thermal degradation behaviours of the feedstocks for solid loadings that were previously determined to correspond to optimal solid loadings using other experimental procedures. The studies also contrast previous similar findings with a ceramic powder. Therefore these results strengthen the proposal of thermodynamic degradation studies of feedstocks as an alternative or complementary technique to determine optimal solid loading contents in metal injection moulding (MIM).The authors a wish to thank GUZMÁN GLOBAL S.L. and MIM
TECH ALFA for their collaboration on the ECOPIM project (ref. IPT
2011 0931 20000) that was funded by the Spanish Ministry of
the Economy and Competitiveness. Furthermore, the authors
would like to acknowledge the strong support from the ESTRUMAT
projects (ref. S2009/MAT 1585), which were funded by the CAM
Consejería Educación Dir. Gral. Universidades e Investigación, and
from the COMETAS project (ref. MAT2009/14448 C02 02), which
was funded by the Spanish Ministry of the Economy and Compet
itiveness. J.P.F. B. acknowledges support from “Marie Curie”
Amarout Europe Program
Processing and mechanical properties of novel biodegradable poly-lactic acid/Zn 3D printed scaffolds for application in tissue regeneration
The feasibility to manufacture scaffolds of poly-lactic acid reinforced with
Zn particles by fused filament fabrication is demonstrated for the first time.
Filaments of 2.85 mm in diameter of PLA reinforced with different weight
fractions of m-sized Zn - 1 wt. \% Mg alloy particles (in the range 3.5 to
17.5 wt. \%) were manufactured by a double extrusion in method in which
standard extrusion is followed by a precision extrusion in a filament-maker
machine. Filaments with constant diameter, negligible porosity and a
homogeneous reinforcement distribution were obtained for Zn weight fractions of
up to 10.5\%. It was found that the presence of Zn particles led to limited
changes in the physico-chemical properties of the PLA that did not affect the
window temperature for 3D printing nor the melt flow index. Thus, porous
scaffolds could be manufactured by fused filament fabrication at 190\textdegree
C with poly-lactic acid/Zn composites containing 3.5 and 7 wt. \% of Zn and at
170\textdegree C when the Zn content was 10.5 wt. \% with excellent dimensional
accuracy and mechanical properties
Single-cell RNA sequencing analysis of cirrhotic patients reveals that Cathepsin D-expressing mononuclear phagocytes are involved in ECM remodelling
Resumen del trabajo presentado en el XXXIII Congrés de la Societat Catalana de Digestologia, celebrado en Lleida, del 25 al 27 de enero de 202
Concept of finite limit of a function at a point: meanings and specific terms
In this paper, we present some results of an exploratory study performed with students aged 16-17. We investigate the different uses that these students make of terms such as ‘to approach’, ‘to tend’, ‘to reach’, ‘to exceed’ and ‘limit’ that describe the basic notions related to the concept of the finite limit of a function at a point. We use the interpretive framework of conceptual analysis to infer the meanings that students associate with these specific terms in connection with the effective use of terms in their answers.This study was performed with aid and financing from Fellowship FPU AP2010-0906 (MEC-FEDER), Projects EDU2009-11337 and EDU2012-33030 of the National Plan for R&D&R (MICIN), Subprogram EDUC and Group FQM-193 of the 3rd Andalusian Research Plan (PAIDI).This chapter is derived in part from an article published in International Journal of Mathematical Education in Science and Technology 05 Jul 2013, available online: http://www.tandfonline.com/10.1080/0020739X.2013.80588
Unraveling the proteolytic network controlling collagen remodeling during liver fibrosis
Resumen del trabajo presentado en el 48 Congreso anual Asociación Española para el Estudio del Hígado, celebrado en Madrid (España), del 15 al 17 de marzo de 202
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