Microwave Absorbing properties of metal functionalized-CNT-polymer composite for stealth applications.

In this study, we report on the electrical properties of multi-wall carbon nanotubes (MWCNT) composites functionalized with metal or metal alloy oxides and embedded in a polyurethane matrix to develop a lightweight material for microwave absorption and shielding. The CNT nanoparticles are functionalized with metallic oxides such as Cobalt oxide, Iron oxide, and Cobalt Iron oxide, at three different concentrations. Metallic oxides are used at 5%, 10%, and 20% concentration of the total CNT percentage weight. The resulting functionalized CNT is mixed with polyurethane polymer at 5% wt of the total composite weight. Three sets of cylindrical samples are developed, and each set contains three different metal oxide concentrations. The dielectric properties of the nine developed samples are obtained by measuring their permittivity spectra using an open-ended coaxial probe technique in the spectral range 5-50 GHz. The absorption efficiency of the composites is then obtained by calculating the reflection loss at normal incidence. The results show that the spectral range of absorption can be tuned by changing the CNT concentration, and the material thickness. Functionalized CNT with different alloyed metal oxides enhanced the absorption efficiency of the polyurethane/CNT composites. Such functionalized composites can be used to replace the common heavyweight materials used for microwave applications.

Chronic physical illnesses in patients with schizophrenia spectrum disorders are independently associated with higher rates of psychiatric rehospitalization; a cross-sectional study in Croatia.

BACKGROUND: Increased physical morbidity in patients with schizophrenia spectrum disorders (SSDs) is well documented. However, much less is known about the association between somatic comorbidities and psychosis treatment outcomes. SUBJECTS AND METHODS: This cross-sectional study, nested within the larger frame of a prospective cohort study, was done in 2016 at Psychiatric Hospital Sveti Ivan, Zagreb, Croatia. Data were collected on a consecutive sample of 301 patients diagnosed with schizophrenia spectrum disorders who achieved a stable therapeutic dosage. Key outcome was the number of psychiatric rehospitalizations since diagnosis of the primary psychiatric illness. Predictors were number of physical and psychiatric comorbidities. By robust regression, we controlled different clinical, sociodemographic, and lifestyle confounding factors. RESULTS: The number of chronic somatic comorbidities was statistically significantly associated with a larger number of psychiatric rehospitalizations, even after the adjustment for number of psychiatric comorbidities and large number of other clinical, sociodemographic, and lifestyle variables. CONCLUSIONS: Chronic somatic comorbidities are associated with higher rates of psychiatric rehospitalization independently of psychiatric comorbidities and other clinical, sociodemographic, and lifestyle factors. Therefore, to treat psychosis effectively, it may be necessary to treat chronic somatic comorbidities promptly and adequately. Chronic somatic comorbidities should be considered equally important as the SSD, and should be brought to the forefront of psychiatric treatment and research with the SSD as one entity. The integrative approach should be the imperative in clinical practice.

Bistability of vortex core dynamics in a single perpendicularly magnetized nanodisk.

Microwave spectroscopy of individual vortex-state magnetic nanodisks in a perpendicular bias magnetic field H is performed using a magnetic resonance force microscope. It reveals the splitting induced by H on the gyrotropic frequency of the vortex core rotation related to the existence of the two stable polarities of the core. This splitting enables spectroscopic detection of the core polarity. The bistability extends up to a large negative (antiparallel to the core) value of the bias magnetic field Hr, at which the core polarity is reversed. The difference between the frequencies of the two stable rotational modes corresponding to each core polarity is proportional to H and to the ratio of the disk thickness to its radius. Simple analytic theory in combination with micromagnetic simulations give a quantitative description of the observed bistable dynamics.

Magnetic resonance studies of the fundamental spin-wave modes in individual submicron Cu/NiFe/Cu perpendicularly magnetized disks.

Spin-wave spectra of perpendicularly magnetized disks consisting of a 100 nm permalloy layer sandwiched between two Cu layers of 30 nm are measured individually by a magnetic resonance force microscope. Using 3D micromagnetic simulations, it is demonstrated that, for submicron-size diameters, the lowest energy spin-wave mode of the saturated state is not spatially uniform, but rather is localized at the center of the Py/Cu interfaces in the region of the minimum demagnetizing field.

Scattering by a slab containing randomly located cylinders: comparison between radiative transfer and electromagnetic simulation.

This study is devoted to the examination of scattering of waves by a slab containing randomly located cylinders. For the first time to our knowledge, the complete transmission problem has been solved numerically. We have compared the radiative transfer theory with a numerical solution of the wave equation. We discuss the coherent effects, such as forward-scattering dip and backscattering enhancement. It is seen that the radiative transfer equation can be used with great accuracy even for optically thin systems whose geometric thickness is comparable with the wavelength. We have also shown the presence of dependent scattering.

Magnetic excitations in a weak-stripe-domain structure: A 2D dynamic micromagnetic approach

The high-frequency susceptibility spectra of ferromagnetic films supporting a weak-stripe-domain structure are computed using a 2D dynamic micromagnetic model that we have developed. The existence of multiple resonances resulting from the excitation of surface and volume modes is predicted. The main features of spectra (number of resonances, resonance frequencies, intensities, and linewidths) strongly depend on the equilibrium spin configuration and on the rf exciting field orientation. These theoretical results are successfully compared with zero-field microwave permeability measurements.