Enhancing the Squareness and Bi-Phase Magnetic Switching of Co2FeSi Microwires for Sensing Application

In the current study we have obtained Co2FeSi glass-coated microwires with different geometrical aspect ratios, ρ = d/Dtot (diameter of metallic nucleus, d and total diameter, Dtot). The structure and magnetic properties are investigated at a wide range of temperatures. XRD analysis illustrates a notable change in the microstructure by increasing the aspect ratio of Co2FeSi-glass-coated microwires. The amorphous structure is detected for the sample with the lowest aspect ratio (ρ = 0.23), whereas a growth of crystalline structure is observed in the other samples (aspect ratio ρ = 0.30 and 0.43). This change in the microstructure properties correlates with dramatic changing in magnetic properties. For the sample with the lowest ρ-ratio, non-perfect square loops are obtained with low normalized remanent magnetization. A notable enhancement in the squareness and coercivity are obtained by increasing ρ-ratio. Changing the internal stresses strongly affects the microstructure, resulting in a complex magnetic reversal process. The thermomagnetic curves show large irreversibility for the Co2FeSi with low ρ-ratio. Meanwhile, if we increase the ρ-ratio, the sample shows perfect ferromagnetic behavior without irreversibility. The current result illustrates the ability to control the microstructure and magnetic properties of Co2FeSi glass-coated microwires by changing only their geometric properties without performing any additional heat treatment. The modification of geometric parameters of Co2FeSi glass-coated microwires allows to obtain microwires that exhibit an unusual magnetization behavior that offers opportunities to understand the phenomena of various types of magnetic domain structures, which is essentially helpful for designing sensing devices based on thermal magnetization switching.This research was funded by the Spanish MICIN, under PID2022-141373NBI00, by EU under “INFINITE” (Horizon Europe) project and by the Government of the Basque Country, under PUE_2021_1_0009 and Elkartek (MINERVA, ZE-KONP and MAGAF) projects and by under the scheme of “Ayuda a Grupos Consolidados” (Ref.: IT1670-22). MS wish to acknowledge the funding within the Maria Zambrano contract by the Spanish Ministerio de Universidades and European Union –Next Generation EU (“Financiado por la Unión Europea-Next Generation EU”)

Structural and Magnetic Properties of Ni0.8Fe0.2/Ti Nanoscale Multilayers

The influence of the thickness of the Ni0.8Fe0.2 (Permalloy, Py) layers on the structural and magnetic properties of magnetron sputtered Py/Ti multilayers was studied. The thickness of the Py layers was varied in the interval of 8 to 30 angstrom. X-ray reflectivity scans evidence the existence of a well-defined layered structure in all the samples considered, but also the presence of a complex intermixed interface. The shape of both the temperature dependence of magnetization and the hysteresis loops of the multilayered structures depends strongly on Py thickness. Magnetic and reflectivity measurements were comparatively analyzed in order to better understand the structure of the samples, and specifically, their interfaces. In particular, the presence of small superparamagnetic Py at the interfaces of the samples, especially evident in the samples with the thinnest Py layers, seems confirmed by the magnetic measurements, agreeing well with the reflectivity results.The research was supported by the Ministry of Education and Science of the Russian Federation (Agreement No. 02.A03.21.0006) and by the Spanish projects MAT2014-58034-R (MINECO/AEI/FEDER, EU) and PEII-2014-042-P (JCCM/FEDER, EU)

Grain growth kinetics and magnetic properties of a vanadium-doped ZnO dilute magnetic oxide

Zn0.95V0.05O ceramics, elaborated from milled ZnO and V2O5 nanopowders, were sintered at 900, 1000 and 1100 °C for 1, 2, 4, 6, 10 and 14 h. The growth kinetics was studied identifying the grain growth exponent, the activation energy and the pre-exponential factor. The high V2O5 concentration allowed a rapid grain growth at 900 °C only at the very first stages (t < 1 h). Meanwhile, at temperatures of 1000 and 1100 °C, the grain growth was extremely fast with a growth exponent of 0.72. The magnetic properties of the samples indicate that ferromagnetism exist in all samples in different magnitudes depending on the sintering conditions. In particular, the maximum magnetization was obtained on the sample sintered at 1100 °C for 14 h, despite the reduction of V concentration. Additionally, secondary paramagnetic phases were detected in the samples sintered at lower temperatures and shorter sintering times

Los afrodescendientes del Ecuador en la pandemia del covid-19

Este artículo describe una investigación realizada para conocer si hay un impacto discriminatorio del covid-19 en las comunidades afrodescendientes del Ecuador, y qué le corresponde hacer al Estado, tomando en cuenta las necesidades y demandas de este grupo étnico. Se analizaron datos relativos a los derechos a la vida, salud, educación, comunicación e información, trabajo, nivel adecuado de vida y la no violencia en hombres y mujeres, triangulando datos cuantitativos del Instituto Nacional de Estadísticas y Censos y del Registro Civil, con datos cualitativos brindados por informantes cualificados de comunidades afrodescendientes. Se encontró que los afrodescendientes empiezan desde una condición de discriminación respecto a todos los derechos evaluados, la cual se ensancha significativamente en el marco del covid-19. Sin embargo, es esencial, en un marco de derechos, que el Estado tome acciones concretas para reparar las injusticias discriminatorias históricas junto a las nuevas

Magneto-Transport Properties of Co–Cu Thin Films Obtained by Co-Sputtering and Sputter Gas Aggregation

Cu100−xCox thin films have been obtained by sputtering (x = 3, 9) and sputter gas aggregation (x = 2.5, 7.5) and subsequent annealing at 400 °C for 1 h. We have studied their structural, magnetic, and magnetotransport properties, both for the as-deposited and annealed samples, confirming the important role of the fabrication method in the properties. The magnetic measurements and the fitting of the hysteresis loops evidence that as-deposited samples consist of superparamagnetic (SPM) and/or ferromagnetic clusters, but in the samples obtained by gas aggregation the clusters are greater (with ferromagnetic behavior at room temperature) whereas in the samples obtained by sputtering, the clusters are smaller and there are also diluted Co atoms in the Cu matrix. The annealing affects negligibly the samples obtained by gas aggregation, but the ones obtained by sputtering are more affected, appearing greater clusters. This behavior is also reflected in the magnetoresistance (MR) measurements of the samples, with different shapes of the MR curves depending on the preparation method: more lineal in the whole range for sputtering, saturation at low fields (about 10 kOe) for gas aggregation. Finally, a Kondo-like minimum in the resistance versus temperature is found in the samples obtained by sputtering, affected by the magnetic field and the annealing. The observed Kondo-like behavior and the influence of annealing on a Kondo-like minimum in sputtered thin films have been attributed to the presence of diluted Co atoms in the Cu matrix and the Co precipitations from the Co–Cu solid solution upon annealing respectively.The authors gratefully acknowledge the financial support from the Plan Propio de la Universidad de Castilla-La Mancha (FEDER, EU) for the “Grupo de Materiales Magnéticos (GMM)”, by Spanish MCIU under PGC2018-099530-B-C31 (MCIU/AEI/FEDER, UE), by the Government of the Basque Country under PIBA 2018-44 and by the University of Basque Country under the scheme of “Ayuda a Grupos Consolidados” (Ref.: GIU18/192)

Influence of the orthorhombic phase content on the dielectric and magnetic properties of YMnO3

Here, we report on the dielectric and magnetic properties of polycrystalline samples of YMnO3 where the ratio between both orthorhombic (o-YMO) and hexagonal (h-YMO) phases has been controlled by means of appropriate sintering treatments. Interestingly, we observe that the dielectric behavior is dominated by the presence of the metastable o-YMO phase, even though its amount remains as a minority phase. However it also influences the magnetic behavior for sintering temperatures below 1000 °C, and in addition, a weak ferromagnetic contribution is always detected in our polycrystalline samples regardless of the o-YMO content

Study of carbon-doped Mn3Ga thin films with enhanced magnetization

Carbon-doped Mn3Ga thin films were grown on Si/SiO2 substrates using rf magnetron sputtering technique and they present an enhancement of their magnetization. In this work we focus on the structural stress, theoretical calculations and magnetization analysis (using both Bloch's and Kneller's laws). The residual stress component has been calculated by means of x-ray diffraction in gracing incidence, using the ? method for multiple crystallographic reflections. We have observed an increase of the cell volume or positive (tensile) strain, which is higher near the surface of the film. The existence of induced magnetism in Mn3GaC0.25, with C entering in interstitial positions has been investigated by first-principles calculations, using the projector-augmented-wave method, within the generalized gradient approximation. Spin charge distributions and magnetic moments associated with each ion, were analyzed by performing a Bader charge analysis. Noteworthily, in spite of being a thin film, the magnetic behavior of the sample can be well described considering it formed by magnetic nanoparticles. Magnetic field and temperature dependence of the magnetization measurements were used to evaluate the Bloch and Kneller exponents, showing that dipolar interactions take place between Mn3GaC0.25 nanoparticle

Transcription factor NRF2 uses the Hippo pathway effector TAZ to induce tumorigenesis in glioblastomas

Transcription factor NRF2 orchestrates a cellular defense against oxidative stress and, so far, has been involved in tumor progression by providing a metabolic adaptation to tumorigenic demands and resistance to chemotherapeutics. In this study, we discover that NRF2 also propels tumorigenesis in gliomas and glioblastomas by inducing the expression of the transcriptional co-activator TAZ, a protein of the Hippo signaling pathway that promotes tumor growth. The expression of the genes encoding NRF2 (NFE2L2) and TAZ (WWTR1) showed a positive correlation in 721 gliomas from The Cancer Genome Atlas database. Moreover, NRF2 and TAZ protein levels also correlated in immunohistochemical tissue arrays of glioblastomas. Genetic knock-down of NRF2 decreased, while NRF2 overexpression or chemical activation with sulforaphane, increased TAZ transcript and protein levels. Mechanistically, we identified several NRF2-regulated functional enhancers in the regulatory region of WWTR1. The relevance of the new NRF2/TAZ axis in tumorigenesis was demonstrated in subcutaneous and intracranial grafts. Thus, intracranial inoculation of NRF2-depleted glioma stem cells did not develop tumors as determined by magnetic resonance imaging. Forced TAZ overexpression partly rescued both stem cell growth in neurospheres and tumorigenicity. Hence, NRF2 not only enables tumor cells to be competent to proliferate but it also propels tumorigenesis by activating the TAZ-mediated Hippo transcriptional program.This study was funded by the Spanish Ministry of Economy and Competitiveness (MINECO) under the grant SAF2016-76520-R. ME is recipient of a postdoctoral contract Juan de la Cierva; DL and NRA of a FPU contract of MINECO; MP and RFG of a FPI contracts of Autonomous University of Madrid. RG has been funded by the AECC Scientific Foundation

Mesothelial-to-Mesenchymal Transition and Exosomes in Peritoneal Metastasis of Ovarian Cancer

Most patients with ovarian cancer (OvCA) present peritoneal disseminated disease at the time of diagnosis. During peritoneal metastasis, cancer cells detach from the primary tumor and disseminate through the intraperitoneal fluid. The peritoneal mesothelial cell (PMC) monolayer that lines the abdominal cavity is the first barrier encountered by OvCA cells. Subsequent progression of tumors through the peritoneum leads to the accumulation into the peritoneal stroma of a sizeable population of carcinoma-associated fibroblasts (CAFs), which is mainly originated from a mesothelial-to-mesenchymal transition (MMT) process. A common characteristic of OvCA patients is the intraperitoneal accumulation of ascitic fluid, which is composed of cytokines, chemokines, growth factors, miRNAs, and proteins contained in exosomes, as well as tumor and mesothelial suspended cells, among other components that vary in proportion between patients. Exosomes are small extracellular vesicles that have been shown to mediate peritoneal metastasis by educating a pre-metastatic niche, promoting the accumulation of CAFs via MMT, and inducing tumor growth and chemoresistance. This review summarizes and discusses the pivotal role of exosomes and MMT as mediators of OvCA peritoneal colonization and as emerging diagnostic and therapeutic targets

Epitaxial growth of the cubic L21-Mn2.6Ga Heusler alloy on MgO(001)

The Mn3Ga Heusler alloy possesses different crystalline structures representing a range of properties of interest for spintronic applications. We report on the structural and magnetic characterization of the disordered cubic-fcc L21-Mn2.6Ga thin films grown on MgO(001) substrates. The first two nanometers of thickness of the Mn2.6Ga thin films are highly strained to the substrate with a lattice mismatch of 9.54%, playing the role of a template layer for the subsequent growth of relaxed L21-Mn2.6Ga. Once the films reach a critical thickness of 15 nm, the cubic phase reorients its epitaxial relationship from a (001) to a (111) in-plane orientation. Magnetic measurements show that the samples exhibit perpendicular magnetic anisotropy and also that the usually antiferromagnetic L21-Mn3Ga films are ferromagnetic with a Curie temperature > 400 K due to partially compensated Mn moments