Magneto Twister: Magneto Deformation of the Water-Air Interface by a Superhydrophobic Magnetic Nanoparticle Layer

[EN] Remote manipulation of superhydrophobic surfacesprovides fascinating features in water interface-related applications. Asuperhydrophobic magnetic nanoparticle colloid layer is able to float on the water-air interface and form a stable water-solid-air interface dueto its inherent water repulsion, buoyancy, and lateral capillarity properties. Moreover, it easily bends downward under an externally applied gradient magnetic field. Thanks to that, the layer creates a stabletwister-like structure with aflipped conical shape, under controlled waterlevels, behaving as a soft and elastic material that proportionally deformswith the applied magneticfield and then goes back to its initial state in the absence of an external force. When the tip of the twister structure touches the bottom of the water container, it provides a stable magnetomovable system, which has many applications in the microfluidicfield.We introduce, as a proof-of-principle, three possible implementations of this structure in real scenarios, the cargo and transport of water droplets in aqueous media, the generation of magneto controllableplugs in open surface channels, and the removal of floating microplastics from the air-water interfaceThe authors acknowledge the MaMi project, funded by the European Union's Horizon 2020 research and innovation programme under grant agreement no. 766007. The authors acknowledge funding support from "Ministerio de Ciencia y Educacion de Espana" under grant PID2020-120313GB-I00/AIE/10.13039/501100011033, Spanish AEI grant no PID2019-104604RB, Gobierno Vasco Dpto. Educacion for the consolidation of the research groups (IT1271-19 and IT1162-19), and European funding (ERDF and ESF). The authors thank for technical and human support provided by Dr. Edilberto Ojeda from GTScience and SGIker of UPV/EHU

Magnetic nanostructures for emerging biomedical applications

Magnetic nanostructures have been widely studied due to their potential applicability into several research fields such as data storage, sensing and biomedical applications. Focusing on the biomedical aspect, some new approaches deserve to be mentioned: cell manipulation and separation, contrast-enhancing agents for magnetic resonance imaging, and magnetomechanically induced cell death. This work focuses on understanding three different magnetic nanostructures, disks in the vortex state, synthetic antiferromagnetic particles and nanowires, first, by explaining their interesting properties and how they behave under an applied external field, before reviewing their potential applications for each of the aforementioned techniques.The authors acknowledge funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement No. 734801. C.R. and R.M. acknowledge funding from Basque Government Grant Nos. PIBA 2018-11 and IT1162-19, and Spanish Grant No. FIS2016-76058 (AEI/FEDER, UE). D.N. acknowledges the Spanish Ministry for Science, Innovation and Universities, for funding through the “Ramon y Cajal” program RYC-2017-22820. C.T. Sousa thanks FCT for financial support through the Investigador FCT program (Contract No. IF/01159/2015). R. Magalhães is grateful to the FCT SFRH/BD/148563/2019 PhD grant. This work was also supported by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) and COMPETE 2020 (FEDER) under the projects POCI-01-0145-FEDER-028676/PTDC/CTM-CTM/28676/2017, POCI-01-0145/FEDER-032257/PTDC/FIS-OTI/32257/2017, POCI-01-0145-FEDER031302/PTDC/FIS-MAC/31302/2017, and POCI-01-0141-FEDER032527

Competition of Magnetic Anisotropies in Permalloy Antidot Lattices

Antidot lattices made of magnetic thin films are good candidates to be employed in future magnetic recording media. In this manuscript we present a study on the effect of shape and field-induced magnetic anisotropies on the magnetization reversal of 10 nm and 50 nm thick permalloy antidot lattices. Rounded antidot square lattices were fabricated using a combination of electron beam evaporation and laser interference lithography, covering surfaces of a few cm2. We demonstrate that a magnetic anisotropy induced in the samples, as a consequence of an applied magnetic field during growth, competes with the shape anisotropy that dominates the response of the patterned thin films, and that the effect of the field-induced magnetic anisotropy scales with the thickness of the antidot thin films. Finally, we have quantified the anisotropy constant attributable to the uniaxial field-induced magnetic anisotropy in our antidot lattices. These findings are supported by micromagnetic simulations performed using MuMax3.We acknowledge financial support from the department of Education of the Basque Government through the PIBA project call (PIBA_2021_1_0051). A.V. and N.A.R.-L. acknowledge funding from the Basque Government Pre-doctoral fellowship program. R.M. and C.R. acknowledge funding from MCIN/ AEI/10.13039/501100011033/ under grant no. PID2019-104604RB-C33

Magnetic properties of permalloy antidot arrayfabricated by interference lithography

The interference laser lithography and ion-beam sputtering have been reported. Magneto-optical Kerr effect magnetometry indicated that the sample exhibits four-fold anisotropic behaviour, i.e. different magnetization loops were observed when the external magnetic field was applied along either x-or y-axis, or along the array diagonal. Broadband ferromagnetic resonance measurements revealed a rich variety of different magnetization configurations in the unsaturated state that can be controlled by the orientation of the external magnetic field. Micromagnetic simulations have been performed to explain the observed results. On the contrary, in the saturated regime the system demonstrated almost isotropic magnetic behaviour that improves with external field increase. The obtained results show the potential of interference lithography for the fabrication of large area antidot arrays. (C) 2019 Author(s).The Portuguese team acknowledges the Network of Extreme Conditions Laboratories-NECL and Portuguese Foundation of Science and Technology (FCT) support through the projects NORTE-01-0145-FEDER-022096, MIT-EXPL/IRA/0012/2017, POCI-01-0145-FEDER-031302, EXPL/IF/01191/2013 (D.N.), EXPL/IF/00541/2015 (S.A.B.), EXPL/IF/00981/2013 (G.N.K). D.N., G.N.K., C.R and R.M. acknowledge the support by the European Union Horizon 2020 Research and Innovation Programme under Marie Sklodowska-Curie Grant Agreement EU H2020-MSCA-RISE-2016 (No 734801). The Spanish team acknowledges the support from Spanish MINECO through the grant FIS2016-76058 (AEI/FEDER, UE). A.H.-R. acknowledges the support from European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Action (reference H2020-MSCA-IF-2016-746958). G.N.K. and O.V.D. acknowledge the support from European Cooperation in Science and Technology (COST) project CA16218 "NANOCOHYBRI.

High-flow nasal cannula therapy for hypoxemic respiratory failure in patients with COVID-19.

INTRODUCTION: High-flow nasal cannula (HFNC) therapy in patients with hypoxemic respiratory failure due to COVID-19 is poorly understood and remains controversial. METHODS: We evaluated a large cohort of patients with COVID-19-related hypoxemic respiratory failure at the temporary COVID-19 hospital in Mexico City. The primary outcome was the success rate of HFNC to prevent the progression to invasive mechanical ventilation (IMV). We also evaluated the risk factors associated with HFNC success or failure. RESULTS: HFNC use effectively prevented IMV in 71.4% of patients [270 of 378 patients; 95% confidence interval (CI) 66.6-75.8%]. Factors that were significantly different at admission included age, the presence of hypertension, and the Charlson comorbidity index. Predictors of therapy failure (adjusted hazard ratio, 95% CI) included the comorbidity-age-lymphocyte count-lactate dehydrogenase (CALL) score at admission (1.27, 1.09-1.47; p < 0.01), Rox index at 1 hour (0.82, 0.7-0.96; p = 0.02), and no prior steroid treatment (0.34, 95% CI 0.19-0.62; p < 0.0001). Patients with HFNC success rarely required admission to the intensive care unit and had shorter lengths of hospital stay [19/270 (7.0%) and 15.0 (interquartile range, 11-20) days, respectively] than those who required IMV [104/108 (96.3%) and 26.5 (20-36) days, respectively]. CONCLUSION: Treating patients with HFNC at admission led to improvement in respiratory parameters in many patients with COVID-19

Symptom cluster analysis of long COVID-19 in patients discharged from the Temporary COVID-19 Hospital in Mexico City.

INTRODUCTION: Several reports have emerged describing the long-term consequences of COVID-19 and its effects on multiple systems. METHODS: As further research is needed, we conducted a longitudinal observational study to report the prevalence and associated risk factors of the long-term health consequences of COVID-19 by symptom clusters in patients discharged from the Temporary COVID-19 Hospital (TCH) in Mexico City. Self-reported clinical symptom data were collected via telephone calls over 90 days post-discharge. Among 4670 patients, we identified 45 symptoms across eight symptom clusters (neurological; mood disorders; systemic; respiratory; musculoskeletal; ear, nose, and throat; dermatological; and gastrointestinal). RESULTS: We observed that the neurological, dermatological, and mood disorder symptom clusters persisted in >30% of patients at 90 days post-discharge. Although most symptoms decreased in frequency between day 30 and 90, alopecia and the dermatological symptom cluster significantly increased (p < 0.00001). Women were more prone than men to develop long-term symptoms, and invasive mechanical ventilation also increased the frequency of symptoms at 30 days post-discharge. CONCLUSION: Overall, we observed that symptoms often persisted regardless of disease severity. We hope these findings will help promote public health strategies that ensure equity in the access to solutions focused on the long-term consequences of COVID-19

Impact of preemptive hospitalization on health outcomes at the temporary COVID-19 hospital in Mexico City: a prospective observational study.

INTRODUCTION: In response to the evolution of the coronavirus disease 2019 (COVID-19) pandemic, the admission protocol for the temporary COVID-19 hospital in Mexico City has been updated to hospitalize patients preemptively with an oxygen saturation (SpO2) of >90%. METHODS: This prospective, observational, single-center study compared the progression and outcomes of patients who were preemptively hospitalized versus those who were hospitalized based on an SpO2 ⩽90%. We recorded patient demographics, clinical characteristics, COVID-19 symptoms, and oxygen requirement at admission. We calculated the risk of disease progression and the benefit of preemptive hospitalization, stratified by CALL Score: age, lymphocyte count, and lactate dehydrogenase (<8 and ⩾8) at admission. RESULTS: Preemptive hospitalization significantly reduced the requirement for oxygen therapy (odds ratio 0.45, 95% confidence interval 0.31-0.66), admission to the intensive care unit (ICU) (0.37, 0.23-0.60), requirement for invasive mechanical ventilation (IMV) (0.40, 0.25-0.64), and mortality (0.22, 0.10-0.50). Stratification by CALL score at admission showed that the benefit of preemptive hospitalization remained significant for patients requiring oxygen therapy (0.51, 0.31-0.83), admission to the ICU (0.48, 0.27-0.86), and IMV (0.51, 0.28-0.92). Mortality risk remained significantly reduced (0.19, 0.07-0.48). CONCLUSION: Preemptive hospitalization reduced the rate of disease progression and may be beneficial for improving COVID-19 patient outcomes

Evolución térmica del acoplamiento magnético de multicapas de GdxCo1-x y propiedades magnéticas de láminas y nanoestructuras 1D de aleaciones de MT-Met (MT: Fe, Co; Met:Si)

En esta tesis, de carácter experimental, se ha estudiado la evolución térmica del comportamiento magnético de sistemas de baja dimensionalidad de materiales magnéticos amorfos. El estudio se ha realizado principalmente mediante medidas magneto-ópticas, que han permitido poner de relieve fenómenos de acoplamiento magnético en multicapas, así como una variedad de procesos de inversión de la imanación en láminas y nanoestructuras ordenadas. En primer lugar se han diseñado y puesto a punto dos sistemas experimentales, para medir ciclos de histéresis mediante el efecto Kerr transversal (T-MOKE). El sistema de bajas temperaturas permite realizar medidas en el rango 10K-440K, utilizando luz blanca, que ilumina todo la muestra, o un láser focalizado, que obtiene ciclos en diferentes puntos de la superficie. El otro sistema experimental opera a temperatura ambiente y se ha pensado para estudiar láminas delgadas nanoestructuradas con áreas muy reducidas (menores a 0.1 mm2) y, por tanto, con muy poca señal magnética. Una característica adicional de este equipo es que permite medir también la proyección de la imanación en la dirección perpendicular al campo aplicado

Role of the antiferromagnetic bulk spin structure on exchange bias

The cooling field dependence of the exchange bias field in ferromagnet/antiferromagnet (FM/AF) multilayers demonstrates that the bulk AF spin structure plays a crucial role on the origin of exchange bias. FM/AF/FM trilayers were designed to eliminate any interlayer exchange coupling between the FM slabs. By choosing the magnetic cooling field, the AF is ordered below its Néel temperature with the FM layers fully saturated either parallel or antiparallel to each other. The significant difference in the exchange bias field between these two cooling configurations confirms that exchange bias cannot be a purely interfacial effect and that the bulk AF moments play a significant role in pinning the uncompensated spins at the AF/FM interface. This experiment also demonstrates that the mechanism responsible for coercivity enhancement has a different origin and is independent of the process that gives rise to exchange bias.Work at UCSD is supported by the U.S. Department of Energy and European MarieCurie OIF (R. M.). Work at UCD is supported by ACS-PRF (No. 43637-AC10), CITRIS, and Alfred P. Sloan Foundation. R. M. and J. M. A also acknowledge Spanish MEC FIS2005-07392 and FIS2008-06249 funding.Peer reviewe