Abstract
The diagnostic value of white matter hyperintensities (WMH) in different types of migraineare unknown. To evaluate the WMH pattern of different subtypes in migraine patients with no vascular ...risk factors. 92 migraine patients (73 females, mean age 34.6 ± 8.9; 61 episodic migraine, 31 chronic migraine, 36 migraine with aura, 56 migraine without aura) without vascular risk factors underwent brain MRI (3 T). We also included a matched healthy control group with no migraine (n = 24). The prevalence of WMH in different types of migraine was similar and ranged from 38.7 to 44.4%; the control group showed no WMH at all. Lesions were located within frontal, parietal and temporal lobes (in order of decreasing incidence) in juxtacortical and/or deep white matter. WMH appeared as round or slightly elongated foci with a median size of 2.5 mm 1.5; 3. Total number, size and prevalence of WMH by lobes and white matter regions were similar between groups, and no interaction with age or sex was found. The number of lesions within the frontal lobe juxtacortical white matter correlated with the age of patients (r = 0.331, p = 0.001) and the duration since migraine onset (r = 0.264, p = 0.012). Patients with different migraine subtypes and without vascular risk factors are characterized by a similar pattern of WMH in the absence of subclinical infarctions or microbleedings. Therefore, WMH have no relevant prognostic value regarding the course of migraine and vascular complications. WMH pattern may be used to differentiate migraine as a primary disorder and other disorders with migraine-like headache and WMH.
A meander waveguide made of an yttrium iron garnet (YIG) film with variation of the profile is studied with a view to the possible control of band bands for surface spin waves (SSWs). The finite ...element method is used to determine the control mechanism of forbidden band gaps in thin YIG films. The electromagnetic problem is solved, and the dispersion characteristics of spin waves are plotted for various geometrical parameters of the meander. The nature of the change in the frequency ranges of Bragg forbidden band gaps is studied in detail depending on the profile of the meander. It is demonstrated that a three-dimensional spin-wave structure with broken translational symmetry that uses vertical spin-wave transport provides an information signal transmission in a three-dimensional configuration of magnonic networks.
•Specific absorption rate of nanoparticles with cubic anisotropy in viscous liquid is calculated.•The viscous and magnetic magnetization reversal modes of particles are obtained.•Heating ability of ...iron nanoparticles is much higher than that of uniaxial ones.•The range of applicability of linear response theory is investigated.
We calculated the specific absorption rate (SAR) and relaxation time of a dilute assembly of spherical iron nanoparticles with cubic anisotropy distributed in a viscous liquid. The behavior of unit magnetization vector was investigated by the solution of stochastic Landau–Lifshitz equation. The spatial orientation of magnetic nanoparticle was determined by the set of stochastic equations for multiple particle directors. The particle viscous and magnetic magnetization reversal modes are revealed at low and sufficiently high amplitudes of alternating magnetic field, respectively. The SAR of iron nanoparticle assembly is shown to exceed significantly that of iron oxide nanoparticles with uniaxial anisotropy at the same amplitudes and frequencies of applied magnetic field. The linear response theory is shown to be valid only at small magnetic field amplitudes, H0 ≤ 50–70 Oe.
The relationship between structural features and selective transport properties of a polymer remains to be the topic of major interest among the scientists working in the field of membrane materials ...development. In the present work the structural and morphological features of the sulfonated co-polyimide and their role in the realisation of its selective transport properties are discussed. The features of the macromolecular chain having limitedly flexible -O-Ph-O- fragment and their influence on the properties of the material are studied with X-Ray diffraction analysis and differential scanning calorimetry. Microphase separated morphology of the block-co-polyimide was detected by the means of atomic force microscopy in the lateral force contrast mode. Theoretical and practical studies on the influence of the counterion nature on the block-copolymer morphology are conducted. Transport properties of the co-polyimide were investigated in the processes of pervaporation and gas separation. Morphological features of the copolymer allow the realisation of the selective fixed-site carrier facilitated transport in terms of pervaporation separation of various binary methanol mixtures. The polymer showed good separation performance in application to pervaporation separation of close to azeotropic MeOH/DMC and MeOH/DME mixtures reaching selectivity values close to 4. The relationship between real and ideal separation selectivities during PV of the studied mixtures are established. The lamellar-like morphology of the studied co-polyimide along with its other unique properties makes it perspective in application to fixed-site carrier facilitated pervaporation and gas separation membranes development.
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•Structural features of the chain having -O-Ph-O- flexible fragment are discussed.•Hansen solubility parameters of the sulfonated co-polyimide are determined.•Flory-Huggins theory is applied to describe the morphology of the co-polyimide.•High values of PV selectivity for methanol rich mixtures are achieved.•The model for the prediction of the real PV selectivity values is proposed.
This work is devoted to the study of the composition and structure of thin “spin-on glass” films and xerogels prepared from silica sols containing platinum and palladium compounds, both separately ...and together. The thickness and concentration distribution of Pt/Pd nanoparticles (NPs) in silica films depending on the concentration of precursors of platinum and palladium in silica sols were determined using the method of X-ray reflectometry. The composition and size of Pt/Pd nanoparticles formed in xerogels and thin films were determined in the nanometer and submicron ranges by means of atomic force and transmission electron microscopy of high resolution as well as by means of X-ray diffraction analysis. It was also determined that bimetallic Pt/Pd nanoparticles possess a common crystal lattice forming clusters with the structure of a mixed alloy type.
Highlights
Pt/Pd NPs with bimetallic crystal lattices form from TEOS-derived sols doped with Pt and Pd.
The size of Pt/Pd bimetallic NPs formed in films is 5–6 nm and of the ones formed in xerogels–10–18 nm.
A Pt and Pd concentration gradient is detected in 30–40 nm-thick doped silica films.
Pt/Pd crystallites up to 70 nm in size form at the meso level as well.
This study investigates the thermal and structural properties of multilayer composites based on chitosan (CS) and polyanions with different functionalities, including sodium sulfoethyl cellulose ...(SEC), sodium alginate (ALG), and sodium hyaluronate (HA). Unlike polyelectrolyte complexes (PECs) obtained by polymer mixing, the formation of a PEC layer by a process of layer-by-layer deposition of oppositely charged polymers is accompanied by the transformation of the CS polymorphic state, and this affects the relaxation and thermal properties of the resulting multilayer composite. X-ray diffraction analysis showed that the formation of the PEC layer in the CS/SEC multilayer film is accompanied by crystallization of the CS chains and the formation of a predominantly anhydrous CS modification. Thermogravimetric analysis of the CS/SEC film registers a high-temperature peak associated with the thermal decomposition of crystalline CS in the PEC composition. According to the dynamic mechanical analysis, the CS/SEC composite was characterized by a single glass transition temperature, indicating a strong interaction between the layers when using SEC (a strong acid salt) as the counterion to CS. For multilayer composites with weak polyacid salts (ALG and HA), the crystallization of CS in the PEC layer is weaker, as reflected in the thermal degradation of these films. A high-temperature peak is recorded in the thermal decomposition of CS/HA and is absent in the case of CS/ALG. Dynamic mechanical analysis of the CS/ALG composite showed two glass transition temperatures close to those of the original polymers, indicating weak PEC formation. The CS/HA composite showed an intermediate response. Thus, the effect of the PEC layer on the properties of the poly-layer composites decreases in the order CS/SEC > CS/HA > CS/ALG.
The effect of pretreatment and Pt content on the catalytic properties as well as mechanistic features of DR were investigated for structured catalysts comprised of Pt supported on CeO
2–ZrO
2 oxide ...doped by Pr. Progressive reduction of cationic Pt species by the reaction feed lowers the activity in CH
4 dry reforming while accelerating the reverse water gas shift reaction catalyzed only by Pt
0, which then decreases progressively the H
2/CO ratio in the effluent. This process is counteracted by the mobility of surface oxygen supplying oxygen atoms to reduced Pt centers thus ensuring their reoxidation and generating in parallel surface oxygen vacancies for the dissociation of CO
2.
A mathematical model and software were developed for numerically studying the transients of the complex catalytic reactions. The processing of experimental data was fulfilled taking into account the importance of cationic forms of Pt, reactivity of carbonate complexes coordinated to these cations and oxygen surface/bulk diffusion. A quantitative evaluation of the density of catalyst's active sites and their coverage by reactive species was accomplished and the rates both of the lattice oxygen diffusion and main stages of the catalytic reaction were estimated.
A biosensor for the direct determination of organophosphorus pesticides (OPs) is described. It utilizes an ion‐selective field‐effect transistor and phosphotriesterase enzyme (PTE), which provides ...cleavage of OPs. The sensitivity of the biosensor was increased after PTE immobilization on the surface of the transistor. Packaging of the integrated circuit and creation of a microfluidic system for analyte delivery stabilized the signal. This system was able to detect 0.1 µM paraoxon and 0.5 µM parathion and methyl parathion and was stable for at least 1 month (PBS, 1°), and could thus provide the basis for a portable device for analyzing OPs in water.
The characteristics of acoustic-gravity waves (waveforms, time durations, amplitudes, azimuths and horizontal phase speeds) from the eruption of the Hunga-Tonga-Hunga-Hapai volcano detected at ...different infrasound stations of the Infrasound Monitoring System and at a network of low-frequency microbarographs in the Moscow region are studied. Using the correlation analysis of the signals at different locations, six arrivals of signals from the volcano, which made up to two revolutions around the Earth, were detected. The Lamb mode of acoustic gravity waves from the volcano eruption is identified and the effect of this mode on generation of tsunami waves and variation of aerosol concentration is studied. The energy released from an underwater volcano into the atmosphere is estimated from the parameters of the Lamb wave and compared with the energy released from the most powerful nuclear bomb of 58 Mt TNT.
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