Vacancy formation in a 1D chain of dust particles in a DC discharge.

The paper presents the first experimental observation of an atypical phenomena during self-organization of dust particles into a one-dimensional chain structure levitated vertically in the plasma of a DC glow discharge. Using a laser, the third (middle) dust particle was removed from the chain of five particles so that the positions of the remaining particles did not significantly change, and a vacancy occurred in the place of the removed particle. This state of the chain turned out to be very stable, which is confirmed by the observation of the subsequent exchange of places of the fourth and the fifth particles of the chain upon the action of the laser on the forth particle. After the exchange process, vertical positions of all particles (first, second, fourth and fifth) in the chain remained almost the same as before the exchange, and the vacancy at the position of the third particle was preserved. The experimental data and the video record of the observed phenomena as well as the estimates of the plasma parameters are presented. An assumption has been made about the mechanism of the discovered phenomena that at present discharge conditions both the vacancy formation and the dust particles positions exchange are possible due to a strong ion wakes which are formed behind the upstream dust particles of the chain.

Modification of topological corner excitations at the interplay of boundary geometry and Coulomb interaction.

The effect of Coulomb interaction on the 2D second order topological superconductor is investigated taking into account different geometries of the boundary in the mainframe of the mean-field approximation. The spontaneous symmetry breaking, described earlier in Aksenovet al(2023Phys. Rev.B107125401), is found to be robust against the boundary deformation. Meanwhile, the details of the state with spontaneously broken symmetry is found to be dependent on the specific boundary geometry. Considering different types of the boundary of the 2D system, it is demonstrated that the deviation of the electron density in the broken symmetry state is determined by the position of the zero-dimensional (second-order) excitations with nearly zero energy. The critical value of the Coulomb interaction, at which the transition occurs, is found to be determined by the energy of these excitations, which is non-zero due to overlapping of the wave-functions at different corners.

Structural properties of a chain of dust particles in a field of external forces.

This paper presents a numerical study of the structural parameters of a one-dimensional chain of three dust particles levitating in the near-electrode layer of an rf discharge or in the stratum of a dc discharge. The model considers the motion of dust particles under the action of gravity, external electric field, the Coulomb repulsion, and the electrostatic force from the space charge surrounding the dust particles. Particular attention is paid to the effect of plasma polarization around dust particles and the wake formation under the action of the external electric field. Calculations showed that the charge of the first dust particle in the chain and the total charge of the entire chain, as well as the length of the chain, grow linearly with the external electric field strength. Obtained data are in qualitative agreement with the experimental and numerical data presented in the literature. It was shown that for a certain large value of the external electric field, the charge of the third dust particle is the smallest of all the particles in the chain. It was found that with an increase in the mean value of the external electric field, the chain of dust particles is displaced as a whole in the direction opposite to the action of the electrostatic force on them.

Non-relaxor behaviour of low-frequency vibration spectra of relaxor ferroelectric PbCo1/3Nb2/3O3: evidences from Brillouin and Raman scattering measurements.

This paper presents the results of studies of a low-frequency vibration spectrum of PbCo1/3Nb2/3O3 (PCN) relaxor ferroelectric crystal using the Brillouin and Raman light scattering in the temperature range from 80 to 750 K. The analysis of the temperature behaviour of the longitudinal acoustic phonon in Brillouin scattering spectra showed no anomalies in the vicinity of 'diffuse phase transition' (T m = 250 K) in PCN. Polarized Raman light scattering spectra were obtained in PCN over the entire temperature range studied. Analysis of low-frequency optical mode behaviour in PCN during temperature change also revealed no correlations with dielectric permeability anomaly in the vicinity of T m: softening of optical phonon at 43 cm-1 frequency in VV polarization is observed at 170 K. In the same temperature range, there are anomalies (a 'narrow' and weak component) in quasi-elastic light scattering (QELS) obtained in temperature behaviour with VH polarization in Raman spectra in PCN. A 'wide' and intense QELS component, obtained in Raman spectra with VV polarization, shows anomalies in the vicinity of T m. We associate the anomalies of optical phonons and QELS with structure distortions in the formation of phase stratification and the dynamics of polar nano-regions.

Corner excitations in the 2D triangle-shaped topological insulator with chiral superconductivity on the triangular lattice.

The 2D triangle-shaped C 3-symmetric topological insulator with the chiral superconducting coupling on the triangular lattice is investigated. While such a system cannot provide the topologically protected corner excitations, we report the presence of the nontopological corner excitations with energy value to lie in the first-order edge spectrum gap. Though these excitations are not topologically protected, they appear for a rather wide range of the parameters values and are robust against the boundary defects and weak disorder. We reveal the presence of the Majorana corner states, which appear along the line in the parameter space.

The edge states properties of the topological insulator with fermion path nonanalyticity points located at the edge.

The edge states properties of a finite-size 2D topological insulator (TI) with the open boundary conditions in both directions are studied. It is shown that fermion path nonanalyticity points appearing on the edge of finite-size TI cause a nonuniform edge state distribution along the TI edge. The character of this distribution depends substantially on the edge state's energy position in the bulk band gap. The edge state with the energy in the middle of the gap tends to be located in the corners between two nonparallel edges of the system, while the edge states with the energy close to the bulk band edge avoid the corners. The monotonic transition from one space distribution of the edge state wave function to another along the edge state's band is observed. The mentioned edge state's structure leads to the nonlinear current-voltage characteristic of the square-shaped TI with contacts connected with the corners of the device. It opens the possibility to control the current with the gate voltage and is useful for construction the nano-size devices. For the edge states with energy in the middle of a bulk gap, the vortex structure of the probability flux located near corners is found.

[A new method of aponevrosis suturing after laparotomy in urgent abdominal surgery]. / Sposob ushivaniia aponevroza posle laparotomii v urgentnoi khirurgii.

OBJECTIVE: To improve the results of treatment of patients undergoing laparotomy by using of a new method of aponeurosis suturing after laparotomy. MATERIAL AND METHODS: Training process for a new method of aponeurosis suturing after laparotomy was organized on the patented medical simulator for learning the technique of laparotomy closure. The method was introduced into surgical practice later. The study involved 130 patients who underwent emergency abdominal surgery through median laparotomy. The main group consisted of 70 patients (laparotomy closure using the proposed method (RF patent No.2644846 dated 02/14/18). Interrupted sutures were applied for aponeurosis suturing in the control group. RESULTS: Duration of laparotomy closure was similar in both groups. Postoperative ventral hernias in 1 year after surgery occurred in 5 (8%) patients of the main group and in 11 (18%) patients of the control group. CONCLUSION: The proposed method of aponeurosis suturing after laparotomy is mastered by students and serves as effective method for prevention of postoperative ventral hernias and eventration.

[Aspects of the importance of postoperative hepatoprotector therapy in urgent surgery]. / Aspekty znachimosti posleoperatsionnoi gepatoprotektornoi terapii v urgentnoi khirurgii.

The purpose of this study was to determine the effect on the effectiveness of the correction of enteric insufficiency syndrome in patients with urgent surgical pathology included in the scheme of complex therapy Remaxol. The results of complex therapy of 227 patients (98 people with common peritonitis and 129 patients with acute intestinal obstruction) were analyzed. 128 patients of the main group in the postoperative period were included in the therapy scheme Remaxol: intravenously drip in a daily dose of 400 ml at a rate of 40 drops per minute, a course of -5 days. Patients of the control group (99 people) received standard treatment. The study is devoted to the role of postoperative hepatoprotective therapy in the treatment of patients with urgent surgical pathology. The main attention is paid to the hepatoenteric link of the pathogenesis of polyorganism insufficiency. This approach gives hope for a reduction in the risk of abdominal sepsis and a reduction in mortality among patients with acute abdominal pathology. The study found that in patients with acute abdominal pathology, an increase in the severity of enteric insufficiency syndrome due to toxic aggression and bacterial translocation can lead to hepatic dysfunction. Consequently, the implementation of hepatoprotective therapy is a pathogenetic link in the complex treatment of urgent surgical patients. The obtained results allowed to draw a number of conclusions. In particular, it has been established that the use of hepatoprotective therapy in the complex medical treatment of patients with acute abdominal pathology makes it possible to stop hepatorenal syndrome by the 5th day, and the syndrome of enteric insufficiency by the 7th day. Earlier relief of hepatic dysfunction and enteral insufficiency syndrome due to hepatoprotective therapy allowed to reduce the incidence of infectious complications to 9.7%, to reduce the lethality to 9.4% and to shorten hospitalization from 17.29 to 1.734 to 12.14±1.385 bed/day.

Plasma anisotropy around a dust particle placed in an external electric field.

A self-consistent model of plasma polarization around an isolated micron-sized dust particle under the action of an external electric field is presented. It is shown that the quasineutral condition is fulfilled and the formed volume charge totally screens the dust particle. The ion focusing and wake formation behind the dust particle are demonstrated for different ion mean free paths and the external electric fields. It is obtained that at low values of the external electric field the trapped ions play the main role in the screening of the dust particle charge. For high external electric fields, the density of trapped ions decreases and the dust particle is screened mainly by the free ions.

[Comparative analysis of laparotomy closure techniques]. / Sravnitel'nyi analiz sposobov ushivaniia laparotomnoi rany.

AIM: To assess experimentally different laparotomy closure techniques. MATERIAL AND METHODS: Experimental research on laboratory animals was performed. Laboratory animals underwent laparotomy followed by aponeurosis suturing by using of interrupted, continuous suture and continuous suture with an arrangement of stitches at different levels. Tensometric and histological examination of tissue specimens together with sutures was made in 7, 14, 60 days after surgery. RESULTS: Correlation of laparotomy closure technique with values of durability, elasticity and wound process course was obtained. CONCLUSION: Continuous suture after laparotomy promotes the formation of more mature granulation tissue and more solid scar with low elasticity compared with interrupted sutures.

Features of Microbial Landscape of Wound Surface in Patients with Diabetic Foot Syndrome.

Reliable inhibition of an infectious agent in the wound is an integral part of the therapeutic measures for the diabetic foot syndrome. Because of low immunity in patients with diabetes the use of antibiotics should be based not only on the'systemic but also local signs of the infection. Unfortunately, the antibiotic therapy does not always provide adequate inhibition of the pathogens. Investigation of the microbial landscape of the wound surface and susceptibility of the pathogens to antibiotics in patients with the diabetic foot syndrome showed that the main pathogens were Staphylococcus aureus, Enterococcus faecalis, Enterobacter cloacae and the Acinetobacter baumannii complex. A detailed analysis of the microbiological tests in a particular -department allows to identify the, most significant pathogens, that makes it possible to assign an earlier rational empirical antibiotic therapy for such pathology.

Genetically Encoded Spin Labels for In Vitro and In-Cell EPR Studies of Native Proteins.

Electron paramagnetic resonance (EPR) spectroscopy in combination with site-directed spin labeling (SDSL) is a powerful approach to study the structure, dynamics, and interactions of proteins. The genetic encoding of the noncanonical amino acid spin-labeled lysine 1 (SLK-1) eliminates the need for any chemical labeling steps in SDSL-EPR studies and enables the investigation of native, endogenous proteins with minimal structural perturbation, and without the need to create unique reactive sites for chemical labeling. We report detailed experimental procedures for the efficient synthesis of SLK-1, the expression and purification of SLK-1-containing proteins under conditions that ensure maximal integrity of the nitroxide radical moiety, and procedures for intramolecular EPR distance measurements in proteins by double electron-electron resonance.

Dust-void formation in a dc glow discharge.

Experimental investigations of dusty plasma parameters of a dc glow discharge were performed in a vertically oriented discharge tube. Under certain conditions, dust-free regions (voids) were formed in the center of the dust particle clouds that levitated in the strong electric field of a stratified positive column. A model for radial distribution of dusty plasma parameters of a dc glow discharge in inert gases was developed. The behavior of void formation was investigated for different discharge conditions (type of gas, discharge pressure, and discharge current) and dust particle parameters (particle radii and particle total number). It was shown that it is the ion drag force radial component that leads to the formation of voids. Both experimental and calculated results show that the higher the discharge current the wider dust-free region (void). The calculations also show that more pronounced voids are formed for dust particles with larger radii and under lower gas pressures.

Dust particle radial confinement in a dc glow discharge.

A self-consistent nonlocal model of the positive column of a dc glow discharge with dust particles is presented. Radial distributions of plasma parameters and the dust component in an axially homogeneous glow discharge are considered. The model is based on the solution of a nonlocal Boltzmann equation for the electron energy distribution function, drift-diffusion equations for ions, and the Poisson equation for a self-consistent electric field. The radial distribution of dust particle density in a dust cloud was fixed as a given steplike function or was chosen according to an equilibrium Boltzmann distribution. The balance of electron and ion production in argon ionization by an electron impact and their losses on the dust particle surface and on the discharge tube walls is taken into account. The interrelation of discharge plasma and the dust cloud is studied in a self-consistent way, and the radial distributions of the discharge plasma and dust particle parameters are obtained. It is shown that the influence of the dust cloud on the discharge plasma has a nonlocal behavior, e.g., density and charge distributions in the dust cloud substantially depend on the plasma parameters outside the dust cloud. As a result of a self-consistent evolution of plasma parameters to equilibrium steady-state conditions, ionization and recombination rates become equal to each other, electron and ion radial fluxes become equal to zero, and the radial component of electric field is expelled from the dust cloud.

[Preperitoneal suprainguinal access with prosthesis of the anterior abdominal wall in treatment of complex forms of incarcerated inguinal hernias].

The article describes a non-typical access to treatment of gigantic incarcerated inguinal hernias. Preperitoneal suprainguinal access allows solution of the main task of operative aid in this pathology: inspection of the strangulated organs, safe dissection of the incarcerating ring and prosthesis of the anterior abdominal wall. This method in many aspects is comparable with traditional methods of hernioplasty, but the postoperative quality of life is much better.

Influence of dust-particle concentration on gas-discharge plasma.

A self-consistent kinetic model of a low-pressure dc glow discharge with dust particles based on Boltzmann equation for the electron energy distribution function is presented. The ions and electrons production in ionizing processes as well as their recombination on the dust-particle surface and on the discharge tube wall were taken into account. The influence of dust-particle concentration N(d) on gas discharge and dust particles parameters was investigated. It is shown that the increase of N(d) leads to the increase of an averaged electric field and ion density, and to the decrease of a dust-particle charge and electron density in the dusty cloud. The results were obtained in a wide region of different discharge and dusty plasma parameters: dust particles density 10(2)-10(8) cm(-3), discharge current density 10(-1)-10(1) mA/cm(2), and dust particles radius 1, 2, and 5 microm. The scaling laws for dust-particle surface potential and electric filed dependencies on dust-particle density, particle radius and discharge currents were revealed. It is shown that the absorption of electrons and ions on the dust particles surface does not lead to the electron energy distribution function depletion due to a self-consistent adjustment of dust particles and discharge parameters.

Effect of trapped ions and nonequilibrium electron-energy distribution function on dust-particle charging in gas discharges.

Dust-particles charging in a low-pressure glow discharge was investigated theoretically. The dust-particle charge was found on the basis of a developed self-consistent model taking into account the nonequilibrium character of electron distribution function and the formation of an ionic coat composed of bound or trapped ions around the dust particle. The dust-particle charge, the radial distributions of electron density, free and trapped ions densities, and the distribution of electrostatic potential were found. It was shown that the non-Maxwellian electron distribution function and collisional flux of trapped ions both reduce the dust-particle charge in comparison with that received with the help of the conventional orbital motion limited (OML) model. However, in rare collisional regimes in plasma when the collisional flux is negligible, the formation of ionic coat around a particle leads to a shielding of the proper charge of a dust particle. In low-pressure experiments, it is only possible to detect the effective charge of a dust particle that is equal to the difference between the proper charge of the particle and the charge of trapped ions. The calculated effective dust particle charge is in fairly good agreement with the experimental measurements of dust-particle charge dependence on gas pressure.

[Suture and suture material in the surgery of finger tendons].

The authors describe two methods of suturing injured finger tendons and requirements to suture material. A polyamide monofilament thread with a conventional number 3/0 used by the authors for a removable suture of the tendon is the suture material of choice. For a buried suture it is expedient to use absorbable threads which begin degrading within three weeks after operation. The developed by the authors loop-shaped removable and buried sutures are strong, atraumatic and simple for fulfillment.

[Syphilis lesions of the stomach]. / O sifiliticheskom porazhenii zheludka.

The paper describes a syphilitic lesion of the stomach in a man who for the first time consulted therapeutist and gastroenterologist with symptoms similar to stomach tumors. A possible infection took place during diagnostic fibrogastroscopy (FGS). Reiterated FGS did not permit endoscopists to suspect syphilis. The data of roentgenography fell into the pattern of stomach cancer. After additional examination with performance of specific seroreactions, an early latent syphilis was diagnosed. The treatment resulted in full clinico-serologic regression of the disease. A timely detection of syphilitic stomach lesion is a great problem if clinical manifestations are estimated separately from anamnestic data.