Competing magnetic states andM-Hloop splitting in core-shell NiO nanoparticles.

Magnetic relaxation in a nanoparticles system depends on the intra-particle interactions, reversal mechanism, the anisotropy field, easy axis distribution, particle volume, lattice defects, surface defects, materials composite, etc. Here we report the competing magnetic states between superparamagnetic blocking and Néel transition states in 14 nm core-shell NiO nanoparticles. A crossover temperature of 50 K was observed for both these states from the zero field cooled/field cooled magnetization curves taken at different fields. At crossover temperature, an interestingM-Hloop splitting is observed which is attributed to the slow spin relaxation. This anomalousM-Hloop splitting behaviour was found to be particle size dependent and suppressed for diameters above and below 14 nm which indicates a critical size for these competing magnetic states. Additional neutron diffraction experiments confirmed this observation. This experimental study provides a new insight for the understanding of intra-particle interactions in fine antiferromagnetic nanoparticles and obtained results are an important step towards deeper understanding of the competing/non-competing modes between superparamagnetic blocked and Néel transition states.

Interplay between intra- and inter-nanowires dynamic dipolar interactions in the spin wave band structure of Py/Cu/Py nanowires.

We have studied both experimentally and theoretically the reprogrammable spin wave band structure in Permalloy(10 nm)/Cu(5 nm)/Permalloy(30 nm) nanowire arrays of width w = 280 nm and inter-wire separation in the range from 80 to 280 nm. We found that, depending on the inter-wire separation, the anti-parallel configuration, where the magnetizations of the two Permalloy layers point in opposite directions, is stabilized over specific magnetic field ranges thus enabling us to directly compare the band structure with that of the parallel alignment. We show that collective spin waves of the Bloch type propagate through the arrays with different magnonic bandwidths as a consequence of the interplay between the intra- and inter-nanowire dynamic dipolar interactions. A detailed understanding, e.g. whether they have a stationary or propagating character, is achieved by considering the phase relation (in-phase or out-of-phase) between the dynamic magnetizations in the two ferromagnetic layers and their average value. This work opens the path to magnetic field-controlled reconfigurable layered magnonic crystals that can be used for future nanoscale magnon spintronic devices.

Storage-recovery phenomenon in magnonic crystal.

The phenomenon of coherent wave trapping and restoration is demonstrated experimentally in a magnonic crystal. Unlike the conventional scheme used in photonics, the trapping occurs not due to the deceleration of the incident wave when it enters the periodic structure but due to excitation of the quasinormal modes of the artificial crystal. This excitation occurs at the group velocity minima of the decelerated wave in narrow frequency regions near the edges of the band gaps of the crystal. The restoration of the traveling wave is implemented by means of phase-sensitive parametric amplification of the stored mode.

Magnonic crystal as a medium with tunable disorder on a periodical lattice.

We show that periodic magnetic nanostructures represent a perfect system for studying excitations on disordered periodical lattices because of the possibility of controlled variation of the degree of disorder by varying the applied magnetic field. Magnetic force microscopy images and ferromagnetic resonance (FMR) data collected inside minor hysteresis loops for a periodic array of Permalloy nanowires were used to demonstrate correlation between the type of FMR response and the degree of disorder of the magnetic ground state.

Radiation of caustic beams from a collapsing bullet.

We show both theoretically and experimentally that a collapsing (2+1)-dimensional wave packet in a medium with cubic nonlinearity and a two-dimensional dispersion of an order higher than parabolic irradiates untrapped dispersive waves. The studies are performed for a spin-wave bullet propagating in an in-plane magnetized ferrimagnetic film. An induced uniaxial anisotropy in such a medium leads to the formation of narrow spin-wave caustic beams whose angles to the bullet's propagation direction are modified by the motion of the source.

Nondiffractive subwavelength wave beams in a medium with externally controlled anisotropy.

We predict and experimentally demonstrate that in a medium with externally induced anisotropy, a wave source of a sufficiently small size can excite practically nondiffractive wave beams with stable subwavelength transverse aperture. The direction of beam propagation is controlled by rotating the induced anisotropy axis. Nondiffractive wave beam propagation, reflection, and scattering, as well as beam steering have been directly observed by optically probing dipolar spin waves in yttrium iron garnet films, where the uniaxial anisotropy was created by an in-plane bias magnetic field.

Formation of guided spin-wave bullets in ferrimagnetic film stripes.

The formation of quasi-2D nonlinear spin-wave eigenmodes in longitudinally magnetized stripes of a ferrimagnetic film, the so-called guided spin-wave bullets, was experimentally observed by using time- and space-resolved Brillouin light scattering spectroscopy and confirmed by numerical simulation. They represent stable spin-wave packets propagating along a waveguide structure, for which both transversal instability and interaction with the side edges of the waveguide are important. The experiments and the numerical simulation of the evolution of the spin-wave excitations show that the shape of the formed packets and their behavior are strongly influenced by the confinement conditions. The discovery of these modes demonstrates the existence of quasistable nonlinear solutions in the transition regime between one-dimensional and two-dimensional wave packet propagation.

[Application of preparations--analogues of somatostatin in surgical pancreatology].

The experience of application of shortly acting and durably acting preparations--analogues of somatostatin in complex therapy of various pancreatic diseases was summarized. There was established similar efficacy of the preparations in blockade of the pancreatic external secretion and the various duration of their inhibiting influence on the blood flow. The trustworthy differences in the complications frequency and lethality while application of various preparations--analogues of somatostatin were not revealed.

[The splanchnic blood flow indices in the patients, suffering external pancreatic fistula, and their dynamics under the influence of sandostatin and somatulin according to the ultrasonographic duplex scanning data].

Hemodynamical effects of the somatostatin analogues were studied in the patients with external pancreatic fistula. There were examined 29 patients, using ultrasonographic duplex scanning, for investigation of the blood flow indices in a. mesenterica superior, truncus coeliacus and its branches, v. lienalis, v. portae and pancreatic intraorgan arteries. Initial indices of splanchnic blood flow were compared with such while administration of octreotide. The main splanchnic blood flow indices in patients, suffering external pancreatic fistula, did not differ from that in controls, the lowering of the pulsation and resistance indices was noted as well as enhancement of the vessels quantity in pancreatic surgical margin. Under the influence of somatostatin the quantity of visualized vessels had reduced, the pulsation and resistance indices increased, the blood flow velocity along a. mesenterica superior, a. lienalis and pancreatic intraorgan arteries lowered, causing reduction of the blood flow linear and volumetric velocity along v. mesenterica superior and vv. intrapancreatici. Inhibitory action of the preparation on splanchnic blood flow was maximal in terms from 6 till 24 h after its infusion and had lowered step by step during all the follow-up period.

Tunneling of dipolar spin waves through a region of inhomogeneous magnetic field.

We show experimentally and by numerical simulations that spin waves propagating in a magnetic film can pass through a region of a magnetic field inhomogeneity or they can be reflected by the region depending on the sign of the inhomogeneity. If the reflecting region is narrow enough, spin-wave tunneling takes place. We investigate the tunneling mechanism and demonstrate that it has a magnetic dipole origin.

Collision properties of quasi-one-dimensional spin wave solitons and two-dimensional spin wave bullets.

Collision properties of quasi-one-dimensional spin wave envelope solitons propagating in narrow ferrite film waveguides and of two-dimensional self-focused spin wave packets (spin wave bullets) propagating in wide ferrite film samples are studied both experimentally and numerically. The experiments, performed by means of a space- and time-resolved Brillouin light scattering technique, have shown that quasi-one-dimensional spin wave envelope solitons retain their shapes after collisions, while two-dimensional spin wave bullets are destroyed in collisions. The experiments have also shown that the introduction of a fixed phase shift between the colliding envelope solitons leads to a qualitative change in their interaction at the collision point. Numerical modeling of head-on collisions of nonlinear spin wave packets based on two different approaches provides a good qualitative description of the observed collision phenomena.

[Venous thromboembolic complications in abdominal and vascular surgery. The risk factors and measures of prophylaxis]. / Venoznye tromboémbolicheskie oslozhneniia v abdominal'noi i sosudistoi khirurgii. Faktory riska i mery profilaktiki.

There were analyzed 4675 histories of cases of patients, who were operated on for disease of the digestion organs (3349) and for obliterating atherosclerosis of abdominal aorta and peripheral arteries (1326). The risk factors of occurrence were established, the prophylaxis methods for venous thromboembolic complications (TEC) in postoperative period were elaborated. High efficacy of application of fraxiparine in the venous TEC prophylaxis in abdominal and vascular surgery was noted.

[Pathophysiology, prophylaxis and treatment of reperfusion syndrome in the surgery of abdominal aorta aneurysm]. / Patofiziologiia, profilaktika i lechenie reprefuzionnogo sindroma v khirurgii anervrizmy briushnoi chasti aorty.

The peroxidal oxidation of the lipids state was studied up, as well as of the whole blood neutrophils functional activity, hemodynamics and microcirculation of lower extremities in surgical treatment of the abdominal aorta aneurysm. The main significance in the reperfusional syndrome pathophysiology, caused by temporary overcompression of aorta, has the neutrophils activation, their interrelationship with the endothelium cells and the activity lowering of the tissue antioxidant system, manifestated by vascular spasm, which is mostly expressed in the patients with stenotic affection of the lower extremities arteries. Positive effect was noted in application of preparation corvitin, which has antioxidant action.

[The characteristics of the alpha-rhythm electroencephalogram in patients with liver cirrhosis]. / Osoblyvosti al'fa-rytmu elektroentsefalohramy u khvorykh na tsyroz pechinky.

The brain functional state in patients with liver cirrhosis was investigated, the correlational dependence between the intrinsically present alpha-rhythm of electroencephalogram pattern of examined patients and the brain reactions signs while the functional tests conduction was studied up. The data obtained are compared with the results of such investigations, conducted in healthy persons. The results of investigations witness the brain functional possibilities lowering in patients with liver cirrhosis. The test with photostimulation is pathognomonic for this disease.

[The evaluation of the elastic properties of the arterial wall by ultrasonic study data in patients with atherosclerotic vascular lesions]. / Otsenka élasticheskikh svoistv arterial'noi stenki po dannym ul'trazvukovogo issledovaniia u bol'nykh s ateroskleroticheskim porazheniem sosudov.

Ultrasonic scanning method in a real scale of time was used in examination of 10 patients with abdominal aorta (AA) aneurysm, 10-with arterial hypertension (AH), 10-with obliterating atherosclerosis of the lower extremities vessels (OALEV) without AH and practically healthy controls aged 32-45 years. AA aneurysm and OALEV diagnosis was made according to the ultrasonic investigation and roentgen-contrast angiography data obtained. The statistically significant (P < 0.05) reduce of AA wall distentivity and its rigidity increase was disclosed while there were no differences of the values of vessel diameter, normalized for the body surface square, determined by the measured magnitude of the relative vessels deformation caused by the pulse change in arterial pressure. The changes of the vascular wall elastic-viscositive properties in patients with OALEV and AH were directed similarly but they lacked intensity. The AA aneurysm magnitude did not correlate with the degree of vascular wall distentivity (r = 0.46).