Enhanced transmission through squeezed modes in a self-cladding magnonic waveguide.

We study spin-wave propagation in 360-nm wide Ni(80)Fe(20) nanowires using all-electrical spin-wave spectroscopy. Creating a zigzag-like magnetization state, we find enhanced spin-wave transmission compared to the states of more homogeneous magnetization. Micromagnetic simulations show that the spin waves propagate in narrow channels, which in particular, are remotely positioned from the edges. The internal channels reflect field-controlled self-cladding. Interestingly, rotation of the magnetic field at a specific value is found to vary the propagation velocity without changing the eigenfrequency. This opens the perspective of the velocity modulation transistor following a concept known from semiconductor electronics.

Forbidden band gaps in the spin-wave spectrum of a two-dimensional bicomponent magnonic crystal.

The spin-wave band structure of a two-dimensional bicomponent magnonic crystal, consisting of Co nanodisks partially embedded in a Permalloy thin film, is experimentally investigated along a high-symmetry direction by Brillouin light scattering. The eigenfrequencies and scattering cross sections are interpreted using plane wave method calculations and micromagnetic simulations. At the boundary of both the first and the second Brillouin zones, we measure a forbidden frequency gap whose width depends on the magnetic contrast between the constituent materials. The modes above and below the gap exhibit resonant spin-precession amplitudes in the complementary regions of periodically varying magnetic parameters. Our findings are key to advance both the physics and the technology of band gap engineering in magnonics.

Anisotropic propagation and damping of spin waves in a nanopatterned antidot lattice.

All-electrical spin-wave spectroscopy, Brillouin light scattering, as well as the magneto-optical Kerr effect are combined to study spin-wave propagation through a magnetic antidot lattice nanopatterned into a Ni(80)Fe(20) thin film. The propagation velocities and, in particular, the relaxation are found to depend characteristically on the applied in-plane magnetic field. We explain the observed anisotropies by magnetic field-controlled spin-wave guiding in a network of interconnected nanowires which takes place over distances of up to 20 µm.

DHA Supplementation Attenuates MI-Induced LV Matrix Remodeling and Dysfunction in Mice.

OBJECTIVE: Myocardial ischemia and reperfusion (I/R) injury is associated with oxidative stress and inflammation, leading to scar development and malfunction. The marine omega-3 fatty acids (ω-3 FA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) are mediating cardioprotection and improving clinical outcomes in patients with heart disease. Therefore, we tested the hypothesis that docosahexaenoic acid (DHA) supplementation prior to LAD occlusion-induced myocardial injury (MI) confers cardioprotection in mice. METHODS: C57BL/6N mice were placed on DHA or control diets (CD) beginning 7 d prior to 60 min LAD occlusion-induced MI or sham surgery. The expression of inflammatory mediators was measured via RT-qPCR. Besides FACS analysis for macrophage quantification and subtype evaluation, macrophage accumulation as well as collagen deposition was quantified in histological sections. Cardiac function was assessed using a pressure-volume catheter for up to 14 d. RESULTS: DHA supplementation significantly attenuated the induction of peroxisome proliferator-activated receptor-α (PPAR-α) (2.3 ± 0.4 CD vs. 1.4 ± 0.3 DHA) after LAD occlusion. Furthermore, TNF-α (4.0 ± 0.6 CD vs. 1.5 ± 0.2 DHA), IL-1ß (60.7 ± 7.0 CD vs. 11.6 ± 1.9 DHA), and IL-10 (223.8 ± 62.1 CD vs. 135.5 ± 38.5 DHA) mRNA expression increase was diminished in DHA-supplemented mice after 72 h reperfusion. These changes were accompanied by a less prominent switch in α/ß myosin heavy chain isoforms. Chemokine mRNA expression was stronger initiated (CCL2 6 h: 32.8 ± 11.5 CD vs. 78.8 ± 13.6 DHA) but terminated earlier (CCL2 72 h: 39.5 ± 7.8 CD vs. 8.2 ± 1.9 DHA; CCL3 72 h: 794.3 ± 270.9 CD vs. 258.2 ± 57.8 DHA) in DHA supplementation compared to CD mice after LAD occlusion. Correspondingly, DHA supplementation was associated with a stronger increase of predominantly alternatively activated Ly6C-positive macrophage phenotype, being associated with less collagen deposition and better LV function (EF 14 d: 17.6 ± 2.6 CD vs. 31.4 ± 1.5 DHA). CONCLUSION: Our data indicate that DHA supplementation mediates cardioprotection from MI via modulation of the inflammatory response with timely and attenuated remodeling. DHA seems to attenuate MI-induced cardiomyocyte injury partly by transient PPAR-α downregulation, diminishing the need for antioxidant mechanisms including mitochondrial function, or α- to ß-MHC isoform switch.

Parameters predicting COVID-19-induced myocardial injury and mortality.

Clinical manifestations of COVID-19 affect many organs, including the heart. Cardiovascular disease is a dominant comorbidity and prognostic factors predicting risk for critical courses are highly needed. Moreover, immunomechanisms underlying COVID-induced myocardial damage are poorly understood. OBJECTIVE: To elucidate prognostic markers to identify patients at risk. RESULTS: Only patients with pericardial effusion (PE) developed a severe disease course, and those who died could be identified by a high CD8/Treg/monocyte ratio. Ten out of 19 COVID-19 patients presented with PE, 7 (78%) of these had elevated APACHE-II mortality risk-score, requiring mechanical ventilation. At admission, PE patients showed signs of systemic and cardiac inflammation in NMR and impaired cardiac function as detected by transthoracic echocardiography (TTE), whereas parameters of myocardial injury e.g. high sensitive troponin-t (hs-TnT) were not yet increased. During the course of disease, hs-TnT rose in 8 of the PE-patients above 16 ng/l, 7 had to undergo ventilatory therapy and 4 of them died. FACS at admission showed in PE patients elevated frequencies of CD3+CD8+ T cells among all CD3+ T-cells, and lower frequencies of Tregs and CD14+HLA-DR+-monocytes. A high CD8/Treg/monocyte ratio predicted a severe disease course in PE patients, and was associated with high serum levels of antiviral cytokines. By contrast, patients without PE and PE patients with a low CD8/Treg/monocyte ratio neither had to be intubated, nor died. CONCLUSIONS: PE predicts cardiac injury in COVID-19 patients. Therefore, TTE should be performed at admission. Immunological parameters for dysfunctional antiviral immunity, such as the CD8/Treg/monocyte ratio used here, supports risk assessment by predicting poor prognosis.

Omnidirectional spin-wave nanograting coupler.

Magnonics as an emerging nanotechnology offers functionalities beyond current semiconductor technology. Spin waves used in cellular nonlinear networks are expected to speed up technologically, demanding tasks such as image processing and speech recognition at low power consumption. However, efficient coupling to microelectronics poses a vital challenge. Previously developed techniques for spin-wave excitation (for example, by using parametric pumping in a cavity) may not allow for the relevant downscaling or provide only individual point-like sources. Here we demonstrate that a grating coupler of periodically nanostructured magnets provokes multidirectional emission of short-wavelength spin waves with giantly enhanced amplitude compared with a bare microwave antenna. Exploring the dependence on ferromagnetic materials, lattice constants and the applied magnetic field, we find the magnonic grating coupler to be more versatile compared with gratings in photonics and plasmonics. Our results allow one to convert, in particular, straight microwave antennas into omnidirectional emitters for short-wavelength spin waves, which are key to cellular nonlinear networks and integrated magnonics.

Enhanced functionality in magnonics by domain walls and inhomogeneous spin configurations.

This paper discusses nanomagnetic structures enabling the manipulation of propagating spin waves. We address in particular how domain walls, or more generally speaking inhomogeneous spin configurations, enhance the control of spin-wave transmission and thereby the functionality of magnonic devices. Three different microscopic mechanisms are outlined, considering an interference device, a spin-wave bus and a magnonic crystal. Inhomogeneous spin configurations are argued to shift the spin-wave phase, guide spin waves in nanochannels and allow for reprogrammable spin-wave band structures in periodic nanostructures, respectively. Such devices and functionalities are relevant for further developments in magnonics.

A murine model of ischemic cardiomyopathy induced by repetitive ischemia and reperfusion.

BACKGROUND: Repetitive brief myocardial ischemia has been implicated in the pathogenesis of the ventricular dysfunction associated with ischemic cardiomyopathy and myocardial hibernation. In this study we examine the effects of repetitive ischemia and reperfusion (I/R) on murine myocardium. METHODS: C57/BL6 mice underwent daily 15 min left anterior descending coronary occlusions followed by reperfusion. After 3, 5, 7, 14, 21 and 28 days, echocardiographic studies were performed, and hearts of I/R and sham-operated animals were processed for histological examination. RESULTS: Histological studies showed no evidence of myocardial necrosis in the ischemic region. Quantitative assessment of collagen revealed a marked persistent interstitial deposition of collagen after seven days I/R in the anterior left ventricular wall (sham 4.6 +/- 2.0 %, I/R 21.5 +/- 6.5 %, p < 0.05). Echocardiographic studies showed persistent regional anterior wall dysfunction in I/R animals. Histological evaluation showed absence of neovessel formation. After discontinuation of the I/R protocol, fibrosis and regional ventricular dysfunction decreased within 60 days. CONCLUSIONS: Repetitive brief murine myocardial I/R induces reversible fibrotic remodeling and ventricular dysfunction, without myocardial infarction and necrosis, and may play a role in the pathogenesis of ischemic cardiomyopathy and myocardial hibernation.