Theory of vortex states in magnetic nanodisks with induced Dzyaloshinskii-Moriya interactions

Vortex states in magnetic nanodisks are essentially affected by surface/interface induced Dzyaloshinskii-Moriya interactions. Within a micromagnetic approach we calculate the equilibrium sizes and shape of the vortices as functions of magnetic field, the material and geometrical parameters of nanodisks. It was found that the Dzyaloshinskii-Moriya coupling can considerably increase sizes of vortices with "right" chirality and suppress vortices with opposite chirality. This allows to form a bistable system of homochiral vortices as a basic element for storage applications.Comment: 8 pages, 8 figure

Post-trocar hernias after laparoscopic cholecystectomy

Catedra chirurgie generală, Universitatea din Transnistria, Tiraspol, Republica Moldova, Al XII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova cu participare internațională 23-25 septembrie 2015Introducere: Aplicarea în practică a colecistectomiilor laparoscopice (CEL) nu a exclus riscul de apariție a herniilor ventrale postoperatorii. Herniile se dezvoltă în locurile de plasare a trocarelor și poartă denumirea de „hernii post-trocar” – HPT. Acestea alcătuiesc circa 0,3-1,1% din numărul total al herniilor ventrale postoperatorii și demonstrează o tendință spre creștere. Conform datelor literaturii, HPT în 0,9% cazuri se formează lângă ombilic și în 0,1% cazuri au o altă localizare. Material și metode: Analiza este bazată pe experiența tratamentului a 19 pacienți cu HPT după CEL pe parcursul a 10 ani (2002-2013). În această perioadă în Clinică au fost efectuate 1112 CEL. Rata formării herniilor a constituit 1,7%. Vîrsta medie a bolnavilor – 54 ani. Intervalul de la momentul apariției herniei – de la 1 la 3 ani. La 16 (1,4%) bolnavi au avut loc supurații de plagă postoperatorie paraombilicală. Diastaza mușchilor recți de gradul 1-2 a fost diagnosticată la 14 (1,2%) bolnavi. În 18 (1,6%) cazuri hernia s-a localizat paraombilical și într-un caz pe peretele abdominal lateral. HPT se caracterizează printr-o discordanță între dimensiunile porților și a sacului herniar. Rezultate: La 2 pacienți a fost depistată prezența a 2 defecte a liniei albe abdominale. Absența în 10 (0,8%) cazuri a ligaturilor aponeurotice în regiunea herniei indică lipsa suturării defectului liniei albe după prima operație. În 3 (0,2%) cazuri cu dimensiunile defectului herniar <2 cm a fost efectuată autoplastia aponeurotică după Sapejco. În celelalte cazuri (defectul herniar >3 cm și prezența diastazei mușchilor recți) s-a efectuat hernioplastia cu lambou autodermal. Cazuri de complicații și recidive postoperatorii nu au fost înregistrate. Concluzii: Profilaxia HPT după CEL necesită suturarea prudentă a defectului aponeurotic în locul plasării trocarelor cu diametrul peste 1 cm. La pacienții de vârstă avansată și la bătrîni regiunea paraombilicală reprezintă o zonă de risc pentru dezvoltarea HPT.Introduction: The implementation of laparoscopic cholecystectomies (LCE) did not exclude the formation of post-operative hernia. Hernia appears in the place of trocar ports („post-trocar hernia” – PTH). PTH represents 0.3-1.1% of total number of post-operative hernias and tends to increase. According to the literature in 0.9% cases hernias are formed around the umbilicus, and in 0.1% – in other areas. Material and methods: The analysis is based on the experience of surgical treatment of 19 patients with PTH after LCE within 10 years (2002-2013). During this period were performed 1112 LCE. The rate of hernia was 1.7%. The mean age of the patients was 54 years. The interval from the hernia development was 1-3 years. After surgery 16 patients had infection of paraumbilical wound. The diastasis of rectus abdominis muscles grade 1-2 was diagnosed in 14 (1.2%) patients. Hernia was formed in 18 (1.6%) patients in paraumbilical region and in 1 case on the lateral abdominal wall. The peculiar feature of PTH is the mismatch of hernia ring size with size of the hernia sac. Results: In 2 patients was noted presence of 2 defects of the white line of the abdomen. The absence of aponeurotic sutures in the area of hernias in 10 (0.8%) patients indicated that white line defect after first operation was not sutured. In 3 (0.2%) cases of hernia 3 cm and the diastasis of the rectus abdominis muscles repair was performed by hernioplasty with autodermal implant. There were no complications or recurrences after surgery. Conclusions: Prevention of PTH after LCE requires careful suturing of aponeurotic defect in the site of trocar placement with diameter greater than 1 cm. In patients with advanced age and elderly the paraumbilical area represents the risk site for development of PTH

Excitation of elastic oscillations in solids by a pulsed proton beam

At present, the beams of charged particles are used not only in fundamental researches but they have found a wide application in solving the plasma electronics problems, modification of material surfaces properties and in a number of other applications

Methane Pyrolysis over Carbon Catalysts

Methane pyrolysis at the temperature range of 550-1000 °C in gas flow reactor with fixed bed of mixed  catalysts based on carbon materials of various structure (fullerene cocoons, fullerene black, vacuum black, cathode deposit, onion-like carbon, glassy carbon, carbon fibers, mineral shungite and graphite) has been studied. Methane pyrolysis products, including stoichiometric amount of hydrogen are C3-C4 alkanes, C2-C4 alkenes, aromatics and pyrolytic carbon. Methane pyrolysis is carried out both on a catalytic surface and in a volume and contribution of the surface is determined by pyrolysis temperature. Materials with curved carbon surface show an activity in methane dehydrogenation at lower temperatures, than materials with planar basic structure elements. Materials with a small specific surface area favor methane aromatization at 950–1000 °C with formation of mainly benzene, toluene and naphthalene. The primary activation of C–H bond in methane at temperatures of lower than 850 °C, as well as the multiple dehydrogenation conversions resulting in the formation of pyrolytic carbon and its precursors (aromatics), are, probably, heterogeneous reactions

Provision for Sanitary Epidemiological Welfare of the Population of the Jewish Autonomous Region during High Water and Post-Flooding Period

Put forward was operational protocol as regards Rospotrebnadzor institutions policies in the territory of the Jewish Autonomous Region for the prevention of epidemiological implications during the post-flooding period in reference to infectious diseases. Carried out were control measures over infection morbidity rate, drinking water quality, disinfection of water supply sources, as well as sewage systems. Actions undertaken made it possible to prevent cluster cases of infectious diseases both in the flooded areas and at the temporal accommodation sites; to provide control over acute intestinal and natural-focal disease incidence, keeping it to the level of long-term average annual indexes; and to supply the population with drinking water of high quality

Polygonal Structures in the Gaseous Disk: Numerical Simulations

The results of numerical simulations of a gaseous disk in the potential of a stellar spiral density wave are presented. The conditions under which straightened spiral arm segments (rows) form in the gas component are studied. These features of the spiral structure were identified in a series of works by A.D. Chernin with coauthors. Gas-dynamic simulations have been performed for a wide range of model parameters: the pitch angle of the spiral pattern, the amplitude of the stellar spiral density wave, the disk rotation speed, and the temperature of the gas component. The results of 2D- and 3D-disk simulations are compared. The rows in the numerical simulations are shown to be an essentially nonstationary phenomenon. A statistical analysis of the distribution of geometric parameters for spiral patterns with rows in the observed galaxies and the constructed hydrodynamic models shows good agreement. In particular, the numerical simulations and observations of galaxies give $\simeq 120^\circ$ for the average angles between straight segments.Comment: 22 pages, 10 figure

Dynamics of Gaseous Disks in a Non-axisymmetric Dark Halo

The dynamics of a galactic disk in a non-axisymmetric (triaxial) dark halo is studied in detail using high-resolution, numerical, hydrodynamical models. A long-lived, two-armed spiral pattern is generated for a wide range of parameters. The spiral structure is global, and the number of turns can be two or three, depending on the model parameters. The morphology and kinematics of the spiral pattern are studied as functions of the halo and disk parameters. The spiral structure rotates slowly, and its angular velocity varies quasi-periodically. Models with differing relative halo masses, halo semi-axis ratios, distributions of matter in the disk, Mach numbers in the gaseous component, and angular rotational velocities of their halos are considered.Comment: 22 pages, 11 figure