Magnetic structure and internal field nuclear magnetic resonance of cobalt nanowires.

The magnetic properties of cobalt metal nanowires grown by electrodeposition in porous membranes depend largely on the synthesis conditions. Here, we focus on the role of electrolyte additives on the magnetic anisotropy of the electrodeposited nanowires. Through magnetometry and internal field nuclear magnetic resonance (IF NMR) studies, we compared both the magnetic and crystalline structures of 50 and 200 nm diameter Co nanowires synthesized in the presence or absence of organic additives. The spectral characteristics of IF NMR were compared structurally to X-ray diffraction patterns, and the anisotropy of the NMR enhancement factor in ferromagnetic multidomain structures to magnetometry results. While the magnetic behavior of the 50 nm nanowires was dominated, as expected, by shape anisotropy with magnetic domains oriented on axis, the analysis of the 200 nm proved to be more complex. 59Co IF NMR revealed that the determining difference between the samples electrodeposited in the presence or in absence of organic additives was not the dominant crystalline system (fcc or hcp) but the coherent domain sizes and boundaries. In the presence of organic additives, the cobalt crystal domains are smaller and with defective grain boundaries, as revealed by resonances below 210 MHz. This prevented the development in the Co hcp part of the sample of the strong magnetocrystalline anisotropy that was observed in the absence of organic additives. In the presence of organic additives, even in nanowires as wide as 200 nm, the magnetic behavior remained determined by the shape anisotropy with a positive effective magnetic anisotropy and strong anisotropy of the NMR enhancement factor.

Efficient and Robust Metallic Nanowire Foams for Deep Submicrometer Particulate Filtration.

The ongoing COVID-19 pandemic highlights the severe health risks posed by deep submicrometer-sized airborne viruses and particulates in the spread of infectious diseases. There is an urgent need for the development of efficient, durable, and reusable filters for this size range. Here we report the realization of efficient particulate filters using nanowire-based low-density metal foams which combine extremely large surface areas with excellent mechanical properties. The metal foams exhibit outstanding filtration efficiencies (>96.6%) in the PM0.3 regime, with the potential for further improvement. Their mechanical stability, light weight, chemical and radiation resistance, ease of cleaning and reuse, and recyclability further make such metal foams promising filters for combating COVID-19 and other types of airborne particulates.

Tunable Magnetism in Nanoporous CuNi Alloys by Reversible Voltage-Driven Element-Selective Redox Processes.

Voltage-driven manipulation of magnetism in electrodeposited 200 nm thick nanoporous single-phase solid solution Cu20 Ni80 (at%) alloy films (with sub 10 nm pore size) is accomplished by controlled reduction-oxidation (i.e., redox) processes in a protic solvent, namely 1 m NaOH aqueous solution. Owing to the selectivity of the electrochemical processes, the oxidation of the CuNi film mainly occurs on the Cu counterpart of the solid solution, resulting in a Ni-enriched alloy. As a consequence, the magnetic moment at saturation significantly increases (up to 33% enhancement with respect to the as-prepared sample), while only slight changes in coercivity are observed. Conversely, the reduction process brings Cu back to its metallic state and, remarkably, it becomes alloyed to Ni again. The reported phenomenon is fully reversible, thus allowing for the precise adjustment of the magnetic properties of this system through the sign and amplitude of the applied voltage.

Terminal patient care: advantages on the applicability of anticipated will directives in the hospital context. / Assistência ao doente terminal: vantagens na aplicabilidade das diretivas antecipadas de vontade no contexto hospitalar.

OBJECTIVE: To know the advantages related to the applicability of the advance directives of will in the hospital context from the perspective of nurses, doctors and family members. METHOD: Qualitative, descriptive and exploratory study with semi structured interviews carried out from October to November 2014, with nurses, doctors and family members of patients in the final stage. Afterwards, a discursive textual analysis was carried out. RESULTS: Four categories emerged: respect for patient's autonomy; support in confrontation of conflicts with and from family members; reduction of conflicts in the team about treatments and conducts; disclosure and instrumentation for application of the Advance Directives of Will. CONCLUSION: The respect for personal autonomy permeates the advantages when relating the conduct of treatments at the end of life with the Advance Directives of Will. Thus, disagreements involving the processes at the end of life would be supported by the patient's desire, besides implying in the reduction of the fear of professionals in facing lawsuits and in the support of the family.

Robust multiferroicity and magnetic modulation of the ferroelectric imprint field in heterostructures comprising epitaxial Hf0.5Zr0.5O2 and Co.

Magnetoelectric multiferroics, either single-phase or composites comprising ferroelectric/ferromagnetic coupled films, are promising candidates for energy efficient memory computing. However, most of the multiferroic magnetoelectric systems studied so far are based on materials that are not compatible with industrial processes. Doped hafnia is emerging as one of the few CMOS-compatible ferroelectric materials. Thus, it is highly relevant to study the integration of ferroelectric hafnia into multiferroic systems. In particular, ferroelectricity in hafnia, and the eventual magnetoelectric coupling when ferromagnetic layers are grown atop of it, are very much dependent on quality of interfaces. Since magnetic metals frequently exhibit noticeable reactivity when grown onto oxides, it is expected that ferroelectricity and magnetoelectricity might be reduced in multiferroic hafnia-based structures. In this article, we present excellent ferroelectric endurance and retention in epitaxial Hf0.5Zr0.5O2 films grown on buffered silicon using Co as the top electrode. The crucial influence of a thin Pt capping layer grown on top of Co on the ferroelectric functional characteristics is revealed by contrasting the utilization of Pt-capped Co, non-capped Co and Pt. Magnetic control of the imprint electric field (up to 40% modulation) is achieved in Pt-capped Co/Hf0.5Zr0.5O2 structures, although this does not lead to appreciable tuning of the ferroelectric polarization, as a result of its high stability. Computation of piezoelectric and flexoelectric strain-mediated mechanisms of the observed magnetoelectric coupling reveal that flexoelectric contributions are likely to be at the origin of the large imprint electric field variation.

Robust Antiferromagnetic FeRh Films on Mica.

FeRh shows an antiferromagnetic to ferromagnetic phase transition above room temperature, which permits its use as an antiferromagnetic memory element. However, its antiferromagnetic order is sensitive to small variations in crystallinity and composition, challenging its integration into flexible devices. Here, we show that flexible FeRh films of high crystalline quality can be synthesized by using mica as a substrate, followed by a mechanical exfoliation of the mica. The magnetic and transport data indicate that the FeRh films display a sharp antiferromagnetic to ferromagnetic phase transition. Magnetotransport data allow for the observation of two distinguishable resistance states, which are written after a field-cooling procedure. It is shown that the memory states are robust under the application of magnetic fields of up to 10 kOe.

Nitrogen-Based Magneto-ionic Manipulation of Exchange Bias in CoFe/MnN Heterostructures.

Electric field control of the exchange bias effect across ferromagnet/antiferromagnet (FM/AF) interfaces has offered exciting potentials for low-energy-dissipation spintronics. In particular, the solid-state magneto-ionic means is highly appealing as it may allow reconfigurable electronics by transforming the all-important FM/AF interfaces through ionic migration. In this work, we demonstrate an approach that combines the chemically induced magneto-ionic effect with the electric field driving of nitrogen in the Ta/Co0.7Fe0.3/MnN/Ta structure to electrically manipulate exchange bias. Upon field-cooling the heterostructure, ionic diffusion of nitrogen from MnN into the Ta layers occurs. A significant exchange bias of 618 Oe at 300 K and 1484 Oe at 10 K is observed, which can be further enhanced after a voltage conditioning by 5 and 19%, respectively. This enhancement can be reversed by voltage conditioning with an opposite polarity. Nitrogen migration within the MnN layer and into the Ta capping layer cause the enhancement in exchange bias, which is observed in polarized neutron reflectometry studies. These results demonstrate an effective nitrogen-ion based magneto-ionic manipulation of exchange bias in solid-state devices.

Frequency-dependent stimulated and post-stimulated voltage control of magnetism in transition metal nitrides: towards brain-inspired magneto-ionics.

Magneto-ionics, which deals with the change of magnetic properties through voltage-driven ion migration, is expected to be one of the emerging technologies to develop energy-efficient spintronics. While a precise modulation of magnetism is achieved when voltage is applied, much more uncontrolled is the spontaneous evolution of magneto-ionic systems upon removing the electric stimuli (i.e., post-stimulated behavior). Here, we demonstrate a voltage-controllable N ion accumulation effect at the outer surface of CoN films adjacent to a liquid electrolyte, which allows for the control of magneto-ionic properties both during and after voltage pulse actuation (i.e., stimulated and post-stimulated behavior, respectively). This effect, which takes place when the CoN film thickness is below 50 nm and the voltage pulse frequency is at least 100 Hz, is based on the trade-off between generation (voltage ON) and partial depletion (voltage OFF) of ferromagnetism in CoN by magneto-ionics. This novel effect may open opportunities for new neuromorphic computing functions, such as post-stimulated neural learning under deep sleep.

[Terminal patient home care: the family caregivers perspective]. / Internação domiciliar do paciente terminal: o olhar do cuidador familiar.

This study was aimed at getting to know the relationships built among patients, family caregivers and the health care team, during home care,from the perspective of the family caregiver It is a qualitative study with 11 family caregivers of terminal patients, registered on a home care service of a university hospital in the South of Brazil. Data collection was carried out through narrative interviews that were recorded transcribed and analyzed through content analysis. Three categories were built from data analysis: relationships among the family caregiver, the patient and the health care team; awareness of the patient's terminal condition. the caregiver's perspective; and situation in which patients are unaware of their terminal condition. They approach how the home care relationships are established among the caregivers, such as health care professionals and family caregivers, and the people who are taken care of such as the patients, highlighting the importance of communication in such care related context.

Bendable Polycrystalline and Magnetic CoFe2O4 Membranes by Chemical Methods.

The preparation and manipulation of crystalline yet bendable functional complex oxide membranes has been a long-standing issue for a myriad of applications, in particular, for flexible electronics. Here, we investigate the viability to prepare magnetic and crystalline CoFe2O4 (CFO) membranes by means of the Sr3Al2O6 (SAO) sacrificial layer approach using chemical deposition techniques. Meticulous chemical and structural study of the SAO surface and SAO/CFO interface properties have allowed us to identify the formation of an amorphous SAO capping layer and carbonates upon air exposure, which dictate the crystalline quality of the subsequent CFO film growth. Vacuum annealing at 800 °C of SAO films promotes the elimination of the surface carbonates and the reconstruction of the SAO surface crystallinity. Ex-situ atomic layer deposition of CFO films at 250 °C on air-exposed SAO offers the opportunity to avoid high-temperature growth while achieving polycrystalline CFO films that can be successfully transferred to a polymer support preserving the magnetic properties under bending. Float on and transfer provides an alternative route to prepare freestanding and wrinkle-free CFO membrane films. The advances and challenges presented in this work are expected to help increase the capabilities to grow different oxide compositions and heterostructures of freestanding films and their range of functional properties.

Reversible writing/deleting of magnetic skyrmions through hydrogen adsorption/desorption.

Magnetic skyrmions are topologically nontrivial spin textures with envisioned applications in energy-efficient magnetic information storage. Toggling the presence of magnetic skyrmions via writing/deleting processes is essential for spintronics applications, which usually require the application of a magnetic field, a gate voltage or an electric current. Here we demonstrate the reversible field-free writing/deleting of skyrmions at room temperature, via hydrogen chemisorption/desorption on the surface of Ni and Co films. Supported by Monte-Carlo simulations, the skyrmion creation/annihilation is attributed to the hydrogen-induced magnetic anisotropy change on ferromagnetic surfaces. We also demonstrate the role of hydrogen and oxygen on magnetic anisotropy and skyrmion deletion on other magnetic surfaces. Our results open up new possibilities for designing skyrmionic and magneto-ionic devices.

From Binary to Ternary Transition-Metal Nitrides: A Boost toward Nitrogen Magneto-Ionics.

Magneto-ionics is an emerging actuation mechanism to control the magnetic properties of materials via voltage-driven ion motion. This effect largely relies on the strength and penetration of the induced electric field into the target material, the amount of generated ion transport pathways, and the ionic mobility inside the magnetic media. Optimizing all these factors in a simple way is a huge challenge, although highly desirable for technological applications. Here, we demonstrate that the introduction of suitable transition-metal elements to binary nitride compounds can drastically boost magneto-ionics. More specifically, we show that the attained magneto-ionic effects in CoN films (i.e., saturation magnetization, toggling speeds, and cyclability) can be drastically enhanced through 10% substitution of Co by Mn in the thin-film composition. Incorporation of Mn leads to transformation from nanocrystalline into amorphous-like structures, as well as from metallic to semiconducting behaviors, resulting in an increase of N-ion transport channels. Ab initio calculations reveal a lower energy barrier for CoMn-N compared to Co-N that provides a fundamental understanding of the crucial role of Mn addition in the voltage-driven magnetic effects. These results constitute an important step forward toward enhanced voltage control of magnetism via electric field-driven ion motion.

Electrically Enhanced Exchange Bias via Solid-State Magneto-ionics.

Electrically induced ionic motion offers a new way to realize voltage-controlled magnetism, opening the door to a new generation of logic, sensor, and data storage technologies. Here, we demonstrate an effective approach to magneto-ionically and electrically tune the exchange bias in Gd/Ni1-xCoxO thin films (x = 0.50 and 0.67), where neither of the layers alone is ferromagnetic at room temperature. The Gd capping layer deposited onto antiferromagnetic Ni1-xCoxO initiates a solid-state redox reaction that reduces an interfacial region of the oxide to ferromagnetic NiCo. An exchange bias is established after field cooling (FC), which can be enhanced by up to 35% after a voltage conditioning and subsequently reset with a second FC. These effects are caused by the presence of an interfacial ferromagnetic NiCo layer, which further alloys with the Gd layer upon FC and voltage application, as confirmed by electron microscopy and polarized neutron reflectometry studies. These results highlight the viability of the solid-state magneto-ionic approach to achieve electric control of exchange bias, with potential for energy-efficient magneto-ionic devices.

The Accessibility of the Cell Wall in Scots Pine (Pinus sylvestris L.) Sapwood to Colloidal Fe3O4 Nanoparticles.

This work presents a rapid and facile way to access the cell wall of wood with magnetic nanoparticles (NPs), providing insights into a method of wood modification to prepare hybrid bio-based functional materials. Diffusion-driven infiltration into Scots pine (Pinus sylvestris L.) sapwood was achieved using colloidal Fe3O4 nanoparticles. Optical microscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray powder diffraction analyses were used to detect and assess the accessibility of the cell wall to Fe3O4. The structural changes, filling of tracheids (cell lumina), and NP infiltration depth were further evaluated by performing X-ray microcomputed tomography analysis. Fourier transform infrared spectroscopy was used to assess the chemical changes in Scots pine induced by the interaction of the wood with the solvent. The thermal stability of Fe3O4-modified wood was studied by thermogravimetric analysis. Successful infiltration of the Fe3O4 NPs was confirmed by measuring the magnetic properties of cross-sectioned layers of the modified wood. The results indicate the feasibility of creating multiple functionalities that may lead to many future applications, including structural nanomaterials with desirable thermal properties, magnetic devices, and sensors.

Cardiovascular disorders in hospitalized patients with dengue infection. / Manifestaciones cardiovasculares en pacientes hospitalizados con dengue.

INTRODUCTION: Cardiac complications in dengue patients are not uncommon and are not diagnosed, since they are usually mild and self-limiting. OBJECTIVES: To characterize the cardiovascular manifestations in hospitalized patients with dengue infection. METHODS: We conducted an observational, analytical, longitudinal, prospective epidemiological study, which included 427 patients treated at Manuel Fajardo Clinical-Surgical Teaching Hospital with diagnosis of dengue infection since April 2017 to April 2018. RESULTS: Cardiovascular manifestations (19.7%), mainly heart rate disorders (sinus bradycardia [13.8%], atrial [4.9%] and ventricular [4.0%] extrasystoles) were frequent in dengue infection patients. Pericarditis and myocarditis were diagnosed in 1.6% and 0.2% respectively. These disorders were self-limiting in 83.3% of cases and occurred in the first days of the onset of fever in 75.0%. Advanced age (OR=1.70), male sex (OR=1.94), decreased platelet count (OR=1.13) and dengue with warning signs (OR=3.29) were related to a higher probability of presenting cardiovascular disorders in the course of a dengue infection. CONCLUSIONS: Cardiovascular manifestations in dengue patients are frequent, and are related to advanced age, male sex, as well as severe forms of the disease.

Magneto-Ionics in Single-Layer Transition Metal Nitrides.

Magneto-ionics allows for tunable control of magnetism by voltage-driven transport of ions, traditionally oxygen or lithium and, more recently, hydrogen, fluorine, or nitrogen. Here, magneto-ionic effects in single-layer iron nitride films are demonstrated, and their performance is evaluated at room temperature and compared with previously studied cobalt nitrides. Iron nitrides require increased activation energy and, under high bias, exhibit more modest rates of magneto-ionic motion than cobalt nitrides. Ab initio calculations reveal that, based on the atomic bonding strength, the critical field required to induce nitrogen-ion motion is higher in iron nitrides (≈6.6 V nm-1) than in cobalt nitrides (≈5.3 V nm-1). Nonetheless, under large bias (i.e., well above the magneto-ionic onset and, thus, when magneto-ionics is fully activated), iron nitride films exhibit enhanced coercivity and larger generated saturation magnetization, surpassing many of the features of cobalt nitrides. The microstructural effects responsible for these enhanced magneto-ionic effects are discussed. These results open up the potential integration of magneto-ionics in existing nitride semiconductor materials in view of advanced memory system architectures.

[Acute amiodarone pulmonary toxicity with low impregnation dose: case report]. / Toxicidad pulmonar aguda por amiodarona con dosis baja de impregnación: reporte de caso.

Amiodarone, considered a potent antiarrhythmic, is known to cause pulmonary toxicity. Chronic interstitial pneumonitis is the most common presentation. However, acute pulmonary toxicity is rare and has a higher case fatality rate. We present a 61-year-old patient with persistent atrial fibrillation who, after a one-month treatment with oral amiodarone at a low dose impregnation of 400 mg/day, develops acute pulmonary toxicity, with radiographic and tomographic resolution after antiarrhythmic suspension and steroid treatment.

Se sabe que la amiodarona, un potente antiarrítmico, causa toxicidad pulmonar. La neumonitis intersticial crónica es la presentación más común. Sin embargo, la toxicidad pulmonar aguda es rara y provoca una mayor mortalidad. Se presenta un paciente de 61 años con fibrilación auricular persistente que, tras tratamiento por un mes con amiodarona vía oral a dosis baja de impregnación de 400 miligramos al día, desarrolló toxicidad pulmonar aguda secundaria al antiarrítmico confirmada por radiografía y tomografía. Su caso tuvo resolución después de la suspensión del fármaco y tratamiento con esteroides.

Enhancing Magneto-Ionic Effects in Magnetic Nanostructured Films via Conformal Deposition of Nanolayers with Oxygen Acceptor/Donor Capabilities.

Effective manipulation of the magnetic properties of nanostructured metallic alloys, exhibiting intergrain porosity (i.e., channels) and conformally coated with insulating oxide nanolayers, with an electric field is demonstrated. Nanostructured Co-Pt films are grown by electrodeposition (ED) and subsequently coated with either AlOx or HfOx by atomic layer deposition (ALD) to promote magneto-ionic effects (i.e., voltage-driven ion migration) during electrolyte gating. Pronounced variations in coercivity (HC) and magnetic moment at saturation (mS) are found at room temperature after biasing the heterostructures. The application of a negative voltage results in a decrease of HC and an increase of mS, whereas the opposite trend is achieved for positive voltages. Although magneto-ionic phenomena are already observed in uncoated Co-Pt films (because of the inherent presence of oxygen), the ALD oxide nanocoatings serve to drastically enhance the magneto-ionic effects because of partially reversible oxygen migration, driven by voltage, across the interface between AlOx or HfOx and the nanostructured Co-Pt film. Co-Pt/HfOx heterostructures exhibit the most significant magneto-electric response at negative voltages, with an increase of mS up to 76% and a decrease of HC by 58%. The combination of a nanostructured magnetic alloy and a skinlike insulating oxide nanocoating is shown to be appealing to enhance magneto-ionic effects, potentially enabling electrolyte-gated magneto-ionic technology.

Voltage-driven motion of nitrogen ions: a new paradigm for magneto-ionics.

Magneto-ionics, understood as voltage-driven ion transport in magnetic materials, has largely relied on controlled migration of oxygen ions. Here, we demonstrate room-temperature voltage-driven nitrogen transport (i.e., nitrogen magneto-ionics) by electrolyte-gating of a CoN film. Nitrogen magneto-ionics in CoN is compared to oxygen magneto-ionics in Co3O4. Both materials are nanocrystalline (face-centered cubic structure) and show reversible voltage-driven ON-OFF ferromagnetism. In contrast to oxygen, nitrogen transport occurs uniformly creating a plane-wave-like migration front, without assistance of diffusion channels. Remarkably, nitrogen magneto-ionics requires lower threshold voltages and exhibits enhanced rates and cyclability. This is due to the lower activation energy for ion diffusion and the lower electronegativity of nitrogen compared to oxygen. These results may open new avenues in applications such as brain-inspired computing or iontronics in general.

Reversible, Electric-Field Induced Magneto-Ionic Control of Magnetism in Mesoporous Cobalt Ferrite Thin Films.

The magnetic properties of mesoporous cobalt ferrite films can be largely tuned by the application of an electric field using a liquid dielectric electrolyte. By applying a negative voltage, the cobalt ferrite becomes reduced, leading to an increase in saturation magnetization of 15% (MS) and reduction in coercivity (HC) between 5-28%, depending on the voltage applied (-10 V to -50 V). These changes are mainly non-volatile so after removal of -10 V MS remains 12% higher (and HC 5% smaller) than the pristine sample. All changes can then be reversed with a positive voltage to recover the initial properties even after the application of -50 V. Similar studies were done on analogous films without induced porosity and the effects were much smaller, underscoring the importance of nanoporosity in our system. The different mechanisms possibly responsible for the observed effects are discussed and we conclude that our observations are compatible with voltage-driven oxygen migration (i.e., the magneto-ionic effect).