Insights into the room temperature magnetism of ZnO/Co3O4 mixtures

The origin of room temperature (RT) ferromagneticlike behavior in ZnO-based diluted magnetic semiconductors is still an unclear topic. The present work concentrates on the appearance of RT magnetic moments in just mixed ZnO/Co3O4 mixtures without thermal treatment. In this study, it is shown that the magnetism seems to be related to surface reduction of the Co3O4 nanoparticles, in which, an antiferromagnetic Co3O4 nanoparticle (core) is surrounded by a CoO-like shell. This singular superficial magnetism has also been found in other mixtures with semiconductors such as TiO2 and insulators such as Al2O3

Strongly coupled magnon-plasmon polaritons in graphene- 2D ferromagnet heterostructures

Magnons and plasmons are two very different types of collective modes, acting on the spin and charge degrees of freedom, respectively. At first sight, the formation of hybrid plasmon-magnon polaritons in heterostructures of plasmonic and magnetic systems would face two challenges, the small mutual interaction, via Zeeman coupling of the electromagnetic field of the plasmon with the spins, and the energy mismatch, as in most systems plasmons have energies in the eV range, orders of magnitude larger than magnons. Here we show that graphene plasmons form polaritons with the magnons of two-dimensional ferrromagnetic insulators, placed up to to half a micron apart, with Rabi couplings in the range of 100 GHz (dramatically larger than cavity QED magnonics). This strong coupling is facilitated both by the small energy of graphene plasmons and the cooperative super-radiant nature of the plasmon-magnon coupling afforded by phase matching. We show that the Rabi coupling can be modulated both electrically and mechanically and we propose a attenuated total internal reflection experiment to implement ferromagnetic resonance experiments on 2D ferromagnets driven by plasmon excitation.Comment: 7 pages, 3 figures, appendi

Xeno-free bioengineered human skeletal muscle tissue using human platelet lysate-based hydrogels

Bioengineered human skeletal muscle tissues have emerged in the last years as new in vitro systems for disease modeling. These bioartificial muscles are classically fabricated by encapsulating human myogenic precursor cells in a hydrogel scaffold that resembles the extracellular matrix. However, most of these hydrogels are derived from xenogenic sources, and the culture media is supplemented with animal serum, which could interfere in drug testing assays. On the contrary, xeno-free biomaterials and culture conditions in tissue engineering offer increased relevance for developing human disease models. In this work, we used human platelet lysate (PL)-based nanocomposite hydrogels (HUgel) as scaffolds for human skeletal muscle tissue engineering. These hydrogels consist of human PL reinforced with aldehyde-cellulose nanocrystals (a-CNC) that allow tunable mechanical, structural, and biochemical properties for the 3D culture of stem cells. Here, we developed hydrogel casting platforms to encapsulate human muscle satellite stem cells in HUgel. The a-CNC content was modulated to enhance matrix remodeling, uniaxial tension, and self-organization of the cells, resulting in the formation of highly aligned, long myotubes expressing sarcomeric proteins. Moreover, the bioengineered human muscles were subjected to electrical stimulation, and the exerted contractile forces were measured in a non-invasive manner. Overall, our results demonstrated that the bioengineered human skeletal muscles could be built in xeno-free cell culture platforms to assess tissue functionality, which is promising for drug development applications.The authors thank the technical support of MicroFabSpace and Microscopy Characterization Facility, Unit 7 of ICTS 'NANBIOSIS' from CIBER-BBN at IBEC. We would also like to thank the muscle team from the Biosensors for Bioengineering group for their feedback in the review process of this manuscript. Human immortalized muscle satellite stem cells used in this study were kindly provided by Dr Bénédicte Chazaud (Institut NeuroMyoGène (INMG), Lyon, France). This project received financial support from European Research Council program Grant ERC-StG-DAMOC: 714317 (J R-A), European Commission under FET-open program BLOC Project: GA- 863037 (J R-A), Spanish Ministry of Economy and Competitiveness, through the 'Severo Ochoa' Program for Centres of Excellence in R&D: SEV-2016–2019, Spanish Ministry of Economy and Competitiveness: 'Retos de investigación: Proyectos I+D+i': TEC2017-83716-C2-2-R (J R-A), CERCA Programme/Generalitat de Catalunya: 2017-SGR-1079 (J R-A), and Fundación Bancaria 'la Caixa'- Obra Social 'la Caixa': project IBEC-La Caixa Healthy Ageing (J R-A). The authors also acknowledge the European Union's Horizon 2020 research and innovation program under European Research Council Grant Agreement 772817 and Twinning Grant Agreement No. 810850—Achilles. Fundação para a Ciência e a Tecnologia (FCT) for CEECIND/01375/2017 (M G-F) and 2020.03410.CEECIND (R M A D)

Coagulation and fragmentation processes with evolving size and shape profiles : a semigroup approach

We investigate a class of bivariate coagulation-fragmentation equations. These equations describe the evolution of a system of particles that are characterised not only by a discrete size variable but also by a shape variable which can be either discrete or continuous. Existence and uniqueness of strong solutions to the associated abstract Cauchy problems are established by using the theory of substochastic semigroups of operators

Topological magnons in CrI3 monolayers: an itinerant fermion description

Magnons dominate the magnetic response of ferromagnetic two-dimensional crystals such as CrI3. Because of the arrangement of Cr spins in a honeycomb lattice, magnons in CrI3 bear a strong resemblance with electrons in graphene. Neutron scattering experiments carried out in bulk CrI3 show the existence of a gap at the Dirac points, conjectured to have a topological nature. We propose a theory for magnons in CrI3 monolayers based on an itinerant fermion picture, with a Hamiltonian derived from first principles. We obtain the magnon dispersion for 2D CrI3 with a gap at the Dirac points with the same Berry curvature in both valleys. For CrI3 ribbons, we find chiral in-gap edge states. Analysis of the magnon wave functions in momentum space confirms their topological nature. Importantly, our approach does not require a spin Hamiltonian, and can be applied to insulating and conducting 2D materials with any type of magnetic order.GVA - Generalitat Valenciana(Prometeo2017/139); European Commission through the project 'Graphene- Driven Revolutions in ICT and Beyond' (reference No. 881603 – Core 3), and the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Financing UID/FIS/04650/2013, COMPETE2020, PORTUGAL2020, FEDER and the Portuguese Foundation for Science and Technology (FCT) through projects PTDC/FIS-NAN/3668/2013 and POCI-01-0145-FEDER-028114. J F-R acknowledges financial support from FCT UTAPEXPL/NTec/0046/2017 project, as well as Generalitat Valenciana funding Prometeo2017/139 and MINECO Spain (Grant No. MAT2016-78625-C2). D L R S thankfully acknowledges the use of HPC resources provided by the National Laboratory for Scientific Computing (LNCC/MCTI, Brazil). A T C thankfully acknowledges the use of computer resources at MareNostrum and the technical support provided by Barcelona Supercomputing Center (RES-FI-2019-2-0034

Phase Transition in Liquid Drop Fragmentation

A liquid droplet is fragmented by a sudden pressurized-gas blow, and the resulting droplets, adhered to the window of a flatbed scanner, are counted and sized by computerized means. The use of a scanner plus image recognition software enables us to automatically count and size up to tens of thousands of tiny droplets with a smallest detectable volume of approximately 0.02 nl. Upon varying the gas pressure, a critical value is found where the size-distribution becomes a pure power-law, a fact that is indicative of a phase transition. Away from this transition, the resulting size distributions are well described by Fisher's model at coexistence. It is found that the sign of the surface correction term changes sign, and the apparent power-law exponent tau has a steep minimum, at criticality, as previously reported in Nuclear Multifragmentation studies [1,2]. We argue that the observed transition is not percolative, and introduce the concept of dominance in order to characterize it. The dominance probability is found to go to zero sharply at the transition. Simple arguments suggest that the correlation length exponent is nu=1/2. The sizes of the largest and average fragments, on the other hand, do not go to zero but behave in a way that appears to be consistent with recent predictions of Ashurst and Holian [3,4].Comment: 10 pages, 11 figures. LaTeX (revtex4) with psfig/epsfi

Visual behaviour and decision-making in attack situations in volleyball

El objetivo de estudio fue comparar el comportamento visual (número y duración de las fijaciones visuales) y la toma de decisiones (TD) en el análisis de escenas de ataque en voleibol, entre entrenadores y jóvenes jugadores. Participaron 59 sujetos - 34 entrenadores (M=32.5; DT=9.4) con experiencia como jugadores y entrenadores de voleibol (M=16.78; DT=11.09), y 25 jugadores (M=16.9; DT=1) con experiencia como jugadores de voleibol (M=3.72; DT=1.17). Para el análisis de la calidad de la TD se emplearon las escenas de ataque del Test de Conocimiento Táctico Declarativo en Voleibol (TCTD:Vb). Para el análisis del comportamiento visual se utilizó el Eye Tracking SMI RED500® durante el análisis de las escenas. Los resultados muestran diferencias significativas en la duración de las fijaciones siendo mayores en el grupo de los entrenadores. Concluye que existe un patrón similar de comportamiento visual en la comparación entre los grupos únicamente diferenciado por la duración de las fijaciones visualesThe objective of comparing visual behavior (number and duration of visual fixations) and decision-making (DM) in the analysis of attack scenes in volleyball, between coaches and young players. 59 subjects will participate – 34 coaches (M = 16.7, SD = 9.4) with experience as players and volleyball coaches (M = 16.78, SD = 11.09), and 25 players (M = 16.9, SD = 1) with experience as volleyball players (M = 3.72 , SD = 1.17). For the analysis of DM quality, the attack scenes of the Tactical Declarative Knowledge Test in Volleyball (TDKT:Vb) were used. For the analysis of visual behavior, the Eye Tracking SMI RED500® was used during the analysis of the scenes. The results show significant differences in duration of fixations being greater for the coaches group. It concludes that there is a similar pattern of visual behavior in the comparison between groups only differentiated by the duration of the visual fixation

Pulsational frequencies of the eclipsing delta-Scuti star HD 172189

The eclipsing delta-Scuti star HD 172189 is a probable member of the open cluster IC 4756 and a promising candidate target for the CoRoT mission. The detection of pulsation modes is the first step in the asteroseismological study of the star. Further, the calculation of the orbital parameters of the binary system allows us to make a dynamical determination of the mass of the star, which works as an important constraint to test and calibrate the asteroseismological models. From a detailed frequency analysis of 210 hours of photometric data of HD 172189 obtained from the STEPHI XIII campaign we have identified six pulsation frequencies with a confidence level of 99% and a seventh with a 65% confidence level in the range between 100-300 uHz. In addiction, three eclipses were observed during the campaign, allowing us to improve the determination of the orbital period of the system.Comment: 6 pages, 7 figure