Structural, Magnetic, and Magneto-Optical Properties of Thin Films of BaM Hexaferrite Grown by Laser Molecular Beam Epitaxy.

Thin films of BaM hexaferrite (BaFe12O19) were grown on α-Al2O3(0001) substrates by laser molecular beam epitaxy. Structural, magnetic, and magneto-optical properties were studied using medium-energy ion scattering, energy dispersive X-ray spectroscopy, atomic force microscopy, X-ray diffraction, magneto-optical spectroscopy, and magnetometric techniques, and the dynamics of magnetization by ferromagnetic resonance method. It was shown that even a short time annealing drastically changes the structural and magnetic properties of films. Only annealed films demonstrate magnetic hysteresis loops in PMOKE and VSM experiments. The shape of hysteresis loops depends on thickness of films showing practically rectangular loops and high value of remnant magnetization (Mr/Ms~99%) for thin films (50 nm) and much broader and sloped loops in thick (350-500 nm) films. The magnitude of magnetization 4πMs ≈ 4.3 kG in thin films corresponds to that in bulk BaM hexaferrite. Photon energy and sign of bands in magneto-optical spectra of thin films correspond to ones observed earlier in bulk samples and films of BaM hexaferrite. FMR spectra of 50 nm films at 50 GHz consist of a number of narrow lines. The width of main line ΔH~20 Oe is lower than has been reported up to now.

Heart Dysfunction in Essential Hypertension Depends on Systemic Proinflammatory Influences: A Retrospective Clinical Pathophysiological Study.

Low-intensity systemic inflammation is an important element of heart failure pathogenesis. The aim of this study is to assess proinflammatory status serum indicators (C-reactive protein (CRP), tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6)) in middle-aged males (M) and females (F) with essential hypertension (HTN) depending on left ventricular (LV) diastolic dysfunction (LVDD). The main group comprised 55 M and 49 F with the first- to second-severity grade HTN with mild heart failure and a preserved LV ejection fraction ≥50%. Patients had sinus rhythm, first or second-severity degree LVDD, LV hypertrophy, left atrium dilatation, and NT-proBNP > 125 pg/mL. Comparison group: 30 hypertensives without cardiac dysfunction; control group: 31 normotensives. Quantitative features were compared using the Mann−Whitney test, median χ2, ANOVA module. Spearman's rank correlation coefficients were determined to identify the relationship between the proinflammatory pattern and exercise tolerance. Hypertensive M had markedly higher CRP, TNF-α, and IL-6 levels compared to F. All mean values corresponded to reference range. In patients with second-degree LVDD, CRP, TNF-α, and IL-6 levels were significantly greater than in subjects with first-degree LVDD (both within M and within F samples). Significant negative associations between CRP, IL-6, and TNF-α levels and the 6 min walk test existed in hypertensive M and F. The study demonstrated a close relationship between the proinflammatory pattern and LVDD and exercise tolerance indicators, regardless of the hypertensive patient's sex.

Correlation between crystal structure and magnetism in PLD grown epitaxial films of ε-Fe2O3 on GaN.

In the present paper we discuss correlations between crystal structure and magnetic properties of epitaxial ε-Fe2O3 films grown on GaN. The large magnetocrystalline anisotropy and room temperature multiferroic properties of this exotic iron oxide polymorph, make it a perspective material for the development of low power consumption magnetic media storage devices. Extending our recent progress in PLD growth of ε-Fe2O3 on the surface of technologically important nitride semiconductors, we apply reciprocal space tomography by electron and x-ray diffraction to investigate the break of crystallographic symmetry occurring at the oxide-nitride interface resulting in the appearance of anisotropic crystallographic disorder in the sub-100 nm ε-Fe2O3 films. The orthorhombic-on-hexagonal nucleation scenario is shown responsible for the development of a peculiar columnar structure observed in ε-Fe2O3 by means of HRTEM and AFM. The complementary information on the direct and reciprocal space structure of the columnar ε-Fe2O3 films is obtained by various techniques and correlated to their magnetic properties. The peculiar temperature dependence of magnetization studied by the small-field magnetization derivative method and by neutron diffraction reveals the existence of a magnetic softening below 150 K, similar to the one observed earlier solely in nanoparticles. The magnetization reversal in ε-Fe2O3 films probed by X-ray magnetic circular dichroism is found different from the behavior of the bulk averaged magnetization measured by conventional magnetometry. The presented results fill the gap between the numerous studies performed on randomly oriented ε-Fe2O3 nanoparticles and much less frequent investigations of epitaxial epsilon ferrite films with lattice orientation fixed by the substrate.

Polymer photonic crystal membrane for thermo-regulating textile.

We study numerically the absorption and scattering properties of a polymer photonic membrane to thermoregulate the human body microclimate which corresponds to the area between the skin and a textile. We first show that the structuration of the absorbing photonic membrane with air holes leads to a modulation of the optical spectrum in the Mid-Infrared range. Indeed, we show that the membrane is able to modulate the transmission amplitude by 28% in benefit or deficit of both the absorption and reflection. We then studied the thermal balance between the human body and the surrounding environment through the photonic membrane. We found that, compared to a regular membrane, the photonic crystal structure behaves as a heating component that offers the possibility to reduce the temperature of the room up to +1 °C. The membrane is flexible, low cost, 3D-printable, free of metallic particles, and can easily be added to usual textiles.

Systemic Action of Inflammatory Mediators in Patients with Essential Hypertension and Diastolic Chronic Heart Failure: A Clinical Pathophysiological Study.

The aim of this research was to correlate indicators of proinflammatory status and the structural/functional characteristics of the cardiovascular system comparatively in male and female patients with essential hypertension (EH) complicated by diastolic chronic heart failure (CHF) with preserved left ventricular ejection fraction (LVEF). The study included 104 middle-aged patients (55 males (M) and 49 females (F)) with first- or second-degree EH complicated by CHF with preserved LVEF. They all belonged to the low functional class of CHF, with LVEF ≥50%, first- or second-degree of LV diastolic dysfunction (LVDD), LV hypertrophy (LVH), and dilatation of the left atrium (LA) with a sinus rhythm and N-terminal brain natriuretic peptide >125 pg/mL. Serum levels of C-reactive protein (CRP), tumor necrosis factor alpha (TNF-α), and interleukin-6 (IL-6) were measured. To identify the relationship between the proinflammatory pattern and cardiovascular parameters, Spearman's rank correlation coefficients were determined. M had markedly higher levels of CRP, TNF-α, and IL-6 compared to F. However, all the mean values corresponded to the reference range. Significant direct associations of CRP level with the LV mass index (LVMI), relative wall thickness (RWT), LA volume index (LAVI), E/e' ratio, and systolic and diastolic blood pressure (SBP, DBP) existed in both M and F, as well as negative correlations of CRP with LVDD parameter e' and distance covered in a 6 min walk test. M and F had a positive association between IL-6 and LVMI, LAVI, E/e' ratio, SBP, RWT, and DBP, as well as strong negative associations between IL-6 and e' and distance passed in 6 min in each group. Significant direct correlations existed between serum TNF-α level and LVMI, RWT, LAVI, E/e', SBP, and DBP both in M and F. Furthermore, there were negative relationships of TNF-α level with e' and the distance covered for the 6 min walk. This study demonstrated a close relationship between the blood levels of proinflammatory autacoids and indicators of EH, exercise tolerance, LVH, LVDD, and LA enlargement, regardless of the patient's sex. Compared to female patients, male patients had stronger correlations of CRP, TNF-α, and IL-6 levels with indicators of LVDD degree.

Idiopathic Normal Pressure Hydrocephalus (Hakim-Adams Syndrome): Clinical Symptoms, Diagnosis and Treatment.

Idiopathic normal pressure hydrocephalus is a chronic steadily progressing disease. Nowadays a vital and acute socially significant problem still has not been solved. The etiology and pathogenesis of this disease remain so far poorly understood. Variable clinical manifestations, as well as difficulties in differential diagnosis with other neurodegenerative diseases - lead to underdiagnosing of the illness that causes a significant decrease in patient's quality of life and even results in disability. The number of patients with idiopathic normal pressure hydrocephalus has been steadily increasing. That is why, the coverage and a full study of this problem is of great interest for a broad circle of medical professionals.

Magnetization reversal in YIG/GGG(111) nanoheterostructures grown by laser molecular beam epitaxy.

Thin (4-20 nm) yttrium iron garnet (Y3Fe5O12, YIG) layers have been grown on gadolinium gallium garnet (Gd3Ga5O12, GGG) 111-oriented substrates by laser molecular beam epitaxy in 700-1000 °C growth temperature range. The layers were found to have atomically flat step-and-terrace surface morphology with step height of 1.8 Å characteristic for YIG(111) surface. As the growth temperature is increased from 700 to 1000 °C the terraces become wider and the growth gradually changes from layer by layer to step-flow regime. Crystal structure studied by electron and X-ray diffraction showed that YIG lattice is co-oriented and laterally pseudomorphic to GGG with small rhombohedral distortion present perpendicular to the surface. Measurements of magnetic moment, magneto-optical polar and longitudinal Kerr effect (MOKE), and X-ray magnetic circular dichroism (XMCD) were used for study of magnetization reversal for different orientations of magnetic field. These methods and ferromagnetic resonance studies have shown that in zero magnetic field magnetization lies in the film plane due to both shape and induced anisotropies. Vectorial MOKE studies have revealed the presence of an in-plane easy magnetization axis. In-plane magnetization reversal was shown to occur through combination of reversible rotation and abrupt irreversible magnetization jump, the latter caused by domain wall nucleation and propagation. The field at which the flip takes place depends on the angle between the applied magnetic field and the easy magnetization axis and can be described by the modified Stoner-Wohlfarth model taking into account magnetic field dependence of the domain wall energy. Magnetization curves of individual tetrahedral and octahedral magnetic Fe3+ sublattices were studied by XMCD.

Integrated 2D-Graded Index Plasmonic Lens on a Silicon Waveguide for Operation in the Near Infrared Domain.

In this article we address the nanoscale engineering of the effective index of silicon on insulator waveguides by using plasmonic metasurface resonances to realize a graded index lens. We report the design, implementation, and experimental demonstration of this plasmonic metasurface-based graded index lens integrated on a silicon waveguide for operation in the near-infrared domain. The 2D-graded index lens consists of an array of gold cut wires fabricated on the top of a silicon waveguide. These gold cut wires modify locally the effective index of the silicon waveguide and allow the realization of this gradient lens. The reported solution represents a promising alternative to the bulky or multilayered metamaterials approach in the near IR domain. This enabling technology may have found its place in silicon photonic applications by exploiting the plasmonic resonances to control the light at nanoscale.

Enhanced Dielectric Environment Sensitivity of Surface Plasmon-Polariton in the Surface-Barrier Heterostructures Based on Corrugated Thin Metal Films with Quasi-Anticorrelated Interfaces.

A new approach to the formation of a 1D planar periodicity on the front of a plasmonic photodetector based on Schottky barrier is proposed. It allows forming a 1D planar periodicity with corrugation at the "metal/environment" interface by laser interference lithography using embedded chalcogenide wires, whereas the "metal/semiconductor" interface is flat that leads to reducing of surface recombination losses at Shottky barrier in contrary to the conventional technology for forming corrugated metal films on the semiconductor surface requiring chemical etching of the semiconductor substrate. In this case, the metal film interfaces are quasi-anticorrelated as opposed to correlated ones in the conventional technology. It has been theoretically predicted that the polarization sensitivity (T p /T s ) strongly depends on the cross-sectional shape of chalcogenide wires and reaches a value of 8. Furthermore, it was theoretically found that the maximum sensitivity of the signal intensity on the environment refractive index is three times larger than for an equivalent structure obtained by conventional technology. Comparison of experimental data for the photocurrent in the case of two types of correlation between metal film interfaces demonstrates good agreement with numerical simulations.

Hybridization of Surface Plasmon Polariton and Photonic Crystal Modes in Bragg Mirror with Periodically Profiled Metal Film.

The hybridization of the plasmonic and guided modes in the case of one-dimension photonic crystal based on Bragg mirror terminated by a corrugated metal film has been demonstrated theoretically. The simulations have showed that the hybrid plasmonic-photonic mode is characterized by low broadening due to redistribution of the electric field intensity between photonic mode and surface plasmon polariton. It was found that the Q-factor and the polarisation sensitivity of these modes are about 144 and 25, respectively, that is 3 times greater than for surface plasmon polariton exciting in similar structure without Bragg mirror.

Prospective for creating a near-field scalpel for laser surgery.

The efficient electric field enhancement due to coating a dielectric wedge by plasmon-carrying nanowires has been demonstrated numerically within the framework of the finite-difference frequency-domain method. The numerical simulations show increasing of electric field intensity in the near-field region of the dielectric wedge coated by silver nanowires in the regime of local plasmon excitation up to 100 times versus the uncoated case.

Hybrid colloidal plasmonic-photonic crystals.

We review the recently emerged class of hybrid metal-dielectric colloidal photonic crystals. The hybrid approach is understood as the combination of a dielectric photonic crystal with a continuous metal film. It allows to achieve a strong modification of the optical properties of photonic crystals by involving the light scattering at electronic excitations in the metal component into moulding of the light flow in series to the diffraction resonances occurring in the body of the photonic crystal. We consider different realizations of hybrid plasmonic-photonic crystals based on two- and three-dimensional colloidal photonic crystals in association with flat and corrugated metal films. In agreement with model calculations, different resonance phenomena determine the optical response of hybrid crystals leading to a broadly tuneable functionality of these crystals.

High light transmission through thin absorptive corrugated films.

The enhancement of light transmittance through periodically relief thin absorptive film at surface plasmon polariton excitation conditions, as a function of relief interrelation, was considered theoretically. Our calculation of transmittance-reflectance through periodically relief thin absorptive film was performed in the framework of differential formalism. There are two basic relief interrelation forms, namely, correlated and anticorrelated ones. The obtained spectral and angular dependencies demonstrate an essential increase of surface plasmon polariton peaks in the case of anticorrelated corrugation of film in comparison with the correlated ones.

Improved method for computing of light-matter interaction in multilayer corrugated structures.

An improved method for the calculation of light-matter interaction that appears with the light propagation through multilayer periodically corrugated structures consisting of any dielectric or absorptive media is reported. The method is based on the differential formalism for a system of Maxwell's equations when the boundary conditions are simplified by the introduction of a curvilinear nonorthogonal coordinate system. The solution for electromagnetic fields was written in the form of the superposition of partial plane waves. The obtained method essentially reduces computation time and increases accuracy compared with the Chandezon method. For a numerical demonstration of the proposed method, calculation of long-range surface plasmon polaritons was performed. The presented method can be enhanced for calculations of light propagation through thin absorptive films with various periodic profiles at both film interfaces.