[Minimally invasive interventions for complications associated with intra-abdominal calculi after laparoscopic cholecystectomy]. / Vozmozhnosti minimal'no invazivnykh vmeshatel'stv v lechenii oslozhnenii, svyazannykh s vnutribryushnymi konkrementami posle videolaparoskopicheskoi kholetsistektomii.

OBJECTIVE: To study the possibilities of minimally invasive methods for removing intra-abdominal calculi after laparoscopic cholecystectomy. MATERIAL AND METHODS: There were 5 patients with abdominal abscesses associated with infected calculi after previous laparoscopic cholecystectomy at the Sklifosovsky Research Institute for Emergency Care between 2020 and 2023. Mean age of patients was 55±12 years. There were 3 (60%) women and 2 (40%) men. All patients underwent minimally invasive treatment. RESULTS: Four patients (80%) underwent percutaneous drainage of abscess with subsequent replacement by larger drains and removal of calculi with endoscopic assistance. Event-free period after cholecystectomy was 44±32 months. One patient developed subhepatic abscess in 72 months after laparoscopic cholecystectomy. This patient underwent transluminal removal of calculus through the duodenal wall. There was 1 calculus in 3 (60%) patients, 2 calculi in 1 (20%) patient and 3 calculi in 1 (20%) patient. CONCLUSION: The above-mentioned cases demonstrate successful minimally invasive interventions for symptomatic abdominal calculi after laparoscopic cholecystectomy. Minimally invasive treatment can reduce surgical aggression and accelerate rehabilitation.

[Pancreatic duct stenting in acute severe pancreatitis]. / Stentirovanie pankreaticheskogo protoka pri ostrom tyazhelom pankreatite.

OBJECTIVE: To evaluate the efficacy of endoscopic retrograde stenting of the pancreatic duct for acute severe pancreatitis. MATERIAL AND METHODS: We analyzed 94 patients with acute severe pancreatitis who underwent surgery (n=87, 92.6%) and endoscopic retrograde pancreatic stenting (n=28, 29.8%). The first group included 15 patients (16%) after pancreatic duct stenting in aseptic phase of acute pancreatitis. The second group enrolled 13 patients (13.8%) who underwent pancreatic duct stenting in the phase of sequestration and infection. The third group consisted of 66 patients (70.2%) after open surgery without pancreatic duct stenting. RESULTS: In the 1st group, we recanalized the necrosis zone up to distal pancreas via stenting. Infection was detected in 14 out of 15 patients. Surgical treatment was performed in 13 patients (13.8%). In the second group, pancreatic duct stenting was carried out in the phase of infected pancreatitis. We applied stenting to block the area of duct destruction or restore outflow in case of distal defect. No infection was observed in 1 out of 13 patients. Pancreatic duct stenting was not performed in 66 patients of the third group. Surgical treatment was performed in 59 patients (62.8%). In general, 11 of 94 patients (11.7%) were free from infection. CONCLUSION: Better postoperative outcomes were observed in patients with damage to pancreatic duct, pancreatic drainage through percutaneous drains installed at the first stage of treatment. Early pancreatic duct stenting did not lead to significant improvement in treatment outcomes.

[Endoscopic transluminal drainage for infected pancreatic necrosis]. / Endoskopicheskoe vnutriprosvetnoe drenirovanie zon pankreatogennoi destruktsii pri nekrotiziruyushchem pankreatite.

OBJECTIVE: To evaluate the effectiveness of intraluminal drainage of acute fluid accumulations for infected pancreatic necrosis. MATERIAL AND METHODS: There were 848 patients with acute pancreatitis between January 2018 and December 2020 at the Sklifosovsky Research Institute for Emergency Care. Necrotizing pancreatitis was detected in 232 (27.4%) patients. Among necrotic forms, pancreatic parenchymal necrosis was detected in 56 (24.1%) patients, its combination with peripancreatic necrosis - in 176 (75.9%) patients. All patients underwent transabdominal ultrasound, CT of the abdomen and retroperitoneal space, esophagogastroduodenoscopy, endo-ultrasonography of pancreatobiliary zone. Dimensions and localization of acute necrotic accumulations were established using ultrasound and CT data. Endoscopic transluminal drainage was performed in 22 patients with necrotizing pancreatitis and fluid accumulations attached to the stomach or duodenum. There were 12 men (55%) and 10 women (45%) aged 48.5 [39; 56] (35; 88) years. Effectiveness of endoscopic treatment was assessed considering clinical, endoscopic data and reduction of fluid accumulations confirmed by ultrasound and CT data. RESULTS: Among 22 patients, connection with pancreatic ductal system was detected in 3 patients (13.6%) that required pancreaticoduodenal stenting. Early postoperative period was complicated by bleeding from the area of pancreatogenic destruction in 4 patients (18.1%). Therefore, angiography and endovascular embolization of a. gastroduodenalis were required in 2 (9.1%) cases. In 1 (4.5%) case, we performed endoscopic hemostasis using Hemoblock hemostatic solution (4 ml). Combination of both methods was used in 1 (4.5%) patient. In 11 (50%) patients, endoscopic drainage was the final method of surgical treatment of necrotizing pancreatitis. Four patients (18.1%) died. Multiple organ failure caused mortality in 3 patients (13.6%). One (4.5%) patient died from severe nosocomial pneumonia developed in 32 days after drainage. Spurs not drained into the stomach with US-confirmed suspension and sequestration were observed in 11 (50%) out of 22 patients. These accumulations required additional ultrasound-assisted percutaneous drainage. CONCLUSION: Endoscopic transluminal drainage is a perspective minimally invasive method for necrotizing pancreatitis.

Density of states in locally ordered amorphous organic semiconductors: Emergence of the exponential tails.

We present a simple model of the local order in amorphous organic semiconductors, which naturally produces a spatially correlated exponential density of states (DOS). The dominant contribution to the random energy landscape is provided by electrostatic contributions from dipoles or quadrupoles. An assumption of the preferable parallel orientation of neighbor quadrupoles or antiparallel orientation of dipoles directly leads to the formation of the exponential tails of the DOS even for a moderate size of the ordered domains. The insensitivity of the exponential tail formation to the details of the microstructure of the material suggests that this mechanism is rather common in amorphous organic semiconductors.

[Endoscopic transluminal drainage of infected pancreatic necrosis]. / Endoskopicheskoe translyuminal'noe drenirovanie ostrogo zhidkostnogo skopleniya pri infitsirovannom pankreonekroze.

OBJECTIVE: To report initial experience of endoscopic transluminal drainage of infected pancreatic necrosis. MATERIAL AND METHODS: There were 8 patients with acute severe pancreatitis and large-focal pancreatic necrosis who underwent transluminal drainage of destruction zones for the period from December 2018 to October 2019. RESULTS: Transluminal drainage of pancreatogenic destruction zones in acute severe pancreatitis can be considered as the only surgical approach in 50% of cases that is comparable with literature data.

Simultaneous Enhancement of Thermopower and Electrical Conductivity through Isovalent Substitution of Cerium in Bismuth Selenide Thermoelectric Materials.

It is challenging to achieve highly efficient thermoelectric materials due to the conflicts between thermopower (Seebeck coefficient) and electrical conductivity. These parameters are the core factors defining the thermoelectric property of any material. Here, we report the use of isovalent substitution as a tool to decouple the interdependency of the Seebeck coefficient and the electrical properties of cerium-doped bismuth selenide thermoelectric material. With this strategy, we can achieve a simultaneous increase in both the electrical conductivity and the Seebeck coefficient of the material by tuning the concentration of cerium doping, due to formation of neutral impurities and consequently the improvement of carrier mobility. Our theoretical calculation reveals a downward shift of the valence band with cerium concentration, which influences the thermoelectric enhancement of the synthesized materials. Finally, an order of magnitude enhancement of the figure of merit is obtained due to isovalent substitution, thus providing a new avenue for enhancing the thermoelectric performance of materials.

Direct band-gap crossover in epitaxial monolayer boron nitride.

Hexagonal boron nitride is a large band-gap insulating material which complements the electronic and optical properties of graphene and the transition metal dichalcogenides. However, the intrinsic optical properties of monolayer boron nitride remain largely unexplored. In particular, the theoretically expected crossover to a direct-gap in the limit of the single monolayer is presently not confirmed experimentally. Here, in contrast to the technique of exfoliating few-layer 2D hexagonal boron nitride, we exploit the scalable approach of high-temperature molecular beam epitaxy to grow high-quality monolayer boron nitride on graphite substrates. We combine deep-ultraviolet photoluminescence and reflectance spectroscopy with atomic force microscopy to reveal the presence of a direct gap of energy 6.1 eV in the single atomic layers, thus confirming a crossover to direct gap in the monolayer limit.

Diffusion of a particle in the Gaussian random-energy landscape: Einstein relation and analytical properties of average velocity and diffusivity as functions of driving force.

We demonstrate that the Einstein relation for the diffusion of a particle in the random-energy landscape with the Gaussian density of states is an exclusive one-dimensional property and does not hold in higher dimensions. We also consider the analytical properties of the particle velocity and diffusivity for the limit of weak driving force and establish a connection between these properties and dimensionality and spatial correlation of the random-energy landscape.

Composition and strain relaxation of In x Ga1-x N graded core-shell nanorods.

Two In x Ga1-x N nanorod samples with graded In compositions of x = 0.5-0 (Ga-rich) and x = 0.5-1 (In-rich) grown by molecular beam epitaxy were studied using transmission electron microscopy. The nanorods had a wurtzite crystal structure with growth along [Formula: see text] and core-shell structures with an In-rich core and Ga-rich shell. Energy-dispersive x-ray analysis confirmed grading over the entire compositional range and showed that the axial growth rate was primarily determined by the In flux, and the radial growth rate by the Ga flux. There was no evidence of misfit dislocations due to grading, but the strain due to the lattice mismatch between the In-rich core and Ga-rich shell was relaxed by edge dislocations at the core-shell interface with Burgers vectors [Formula: see text] and [Formula: see text].

[Choice of surgical tactics in patients with acute cholecystitis complicated by cholelithiasis]. / Vybor taktiki khirurgicheskogo lecheniia bol'nykh s ostrym kholetsistitom, oslozhnennym kholedokholitiazom.

PURPOSE OF THE STUDY: Comparison of the methods of surgical treatment of cholelithiasis. MATERIAL AND METHODS: The work is based on the experience of treating 139 patients with acute cholecystitis complicated by choledocholithiasis from 2008 to 2016, who were on treatment of the department of acute surgical diseases of the liver and pancreas, N.V. Sklifosovsky. RESULTS: The use of percutaneous drainage of the gallbladder in an acute period can reduce complications and reduce the number of urgent video-laparoscopic cholecystectomies to 1%.

Diffusion of a particle in the spatially correlated exponential random energy landscape: Transition from normal to anomalous diffusion.

Diffusive transport of a particle in a spatially correlated random energy landscape having exponential density of states has been considered. We exactly calculate the diffusivity in the nondispersive quasi-equilibrium transport regime for the 1D transport model and found that for slow decaying correlation functions the diffusivity becomes singular at some particular temperature higher than the temperature of the transition to the true non-equilibrium dispersive transport regime. It means that the diffusion becomes anomalous and does not follow the usual ∝ t1/2 law. In such situation, the fully developed non-equilibrium regime emerges in two stages: first, at some temperature there is the transition from the normal to anomalous diffusion, and then at lower temperature the average velocity for the infinite medium goes to zero, thus indicating the development of the true dispersive regime. Validity of the Einstein relation is discussed for the situation where the diffusivity does exist. We provide also some arguments in favor of conservation of the major features of the new transition scenario in higher dimensions.

Comparative Monte-Carlo simulations of charge carrier transport in amorphous molecular solids as given by three most common models of disorder: The dipolar glass, the Gaussian disorder, and their mix.

We have performed Monte-Carlo simulations of the charge carrier transport in a model molecularly doped polymer using three most popular hopping theories (the dipolar glass model, the Gaussian disorder model, and an intermediate between them) in a wide range of applied electric fields and temperatures. Time of flight transients have been computed and analyzed in logarithmic coordinates to study the Poole-Frenkel field dependence, the non-Arrhenius mobility temperature dependence, and the nondispersive versus dispersive current shapes. We also have made an attempt to estimate the total disorder energy directly from simulation data at the lowest electric field thus checking the consistency of the model fitting. Computational results have been compared with the analytical and experimental information available in the literature.

An atomic carbon source for high temperature molecular beam epitaxy of graphene.

We report the use of a novel atomic carbon source for the molecular beam epitaxy (MBE) of graphene layers on hBN flakes and on sapphire wafers at substrate growth temperatures of ~1400 °C. The source produces a flux of predominantly atomic carbon, which diffuses through the walls of a Joule-heated tantalum tube filled with graphite powder. We demonstrate deposition of carbon on sapphire with carbon deposition rates up to 12 nm/h. Atomic force microscopy measurements reveal the formation of hexagonal moiré patterns when graphene monolayers are grown on hBN flakes. The Raman spectra of the graphene layers grown on hBN and sapphire with the sublimation carbon source and the atomic carbon source are similar, whilst the nature of the carbon aggregates is different - graphitic with the sublimation carbon source and amorphous with the atomic carbon source. At MBE growth temperatures we observe etching of the sapphire wafer surface by the flux from the atomic carbon source, which we have not observed in the MBE growth of graphene with the sublimation carbon source.

Hopping charge transport in amorphous semiconductors with the spatially correlated exponential density of states.

Hopping charge transport in amorphous semiconductors having spatially correlated exponential density of states has been considered. Average carrier velocity is exactly calculated for the quasi-equilibrium (nondispersive) transport regime. We suggest also a heuristic approach for the consideration of the carrier velocity for the non-equilibrium dispersive regime.

X-ray detection with zinc-blende (cubic) GaN Schottky diodes.

The room temperature X-ray responses as functions of time of two n type cubic GaN Schottky diodes (200 µm and 400 µm diameters) are reported. The current densities as functions of time for both diodes showed fast turn-on transients and increases in current density when illuminated with X-ray photons of energy up to 35 keV. The diodes were also electrically characterized: capacitance, implied depletion width and dark current measurements as functions of applied bias at room temperature are presented. At -5 V reverse bias, the capacitances of the diodes were measured to be (84.05 ± 0.01) pF and (121.67 ± 0.02) pF, respectively. At -5 V reverse bias, the dark current densities of the diodes were measured to be (347.2 ± 0.4) mA cm(-2) and (189.0 ± 0.2) mA cm(-2), respectively. The Schottky barrier heights of the devices (0.52 ± 0.07) eV and (0.63 ± 0.09) eV, respectively, were extracted from the forward dark current characteristics.

Far tails of the density of states in amorphous organic semiconductors.

Far tails of the density of state (DOS) are calculated for the simple models of organic amorphous material, the model of dipolar glass and model of quadrupolar glass. It was found that in both models far tails are non-Gaussian. In the dipolar glass model, the DOS is symmetric around zero energy, while for the model of quadrupolar glass, the DOS is generally asymmetric and its asymmetry is directly related to the particular geometry of quadrupoles. Far tails of the DOS are relevant for the quasi-equilibrium transport of the charge carriers at low temperature. Asymmetry of DOS in quadrupolar glasses means a principal inequivalence of the random energy landscape for the transport of electrons and holes. Possible effect of the non-Gaussian shape of the far tails of the DOS on the temperature dependence of carrier drift mobility is discussed.

Compositional variations in In(0.5)Ga(0.5)N nanorods grown by molecular beam epitaxy.

The composition of InxGa1 - xN nanorods grown by molecular beam epitaxy with nominal x = 0.5 has been mapped by electron microscopy using Z-contrast imaging and x-ray microanalysis. This shows a coherent and highly strained core-shell structure with a near-atomically sharp boundary between a Ga-rich shell (x âˆ¼ 0.3) and an In-rich core (x âˆ¼ 0.7), which itself has In- and Ga-rich platelets alternating along the growth axis. It is proposed that the shell and core regions are lateral and vertical growth sectors, with the core structure determined by spinodal decomposition.

Charge carrier transport in molecularly doped polycarbonate as a test case for the dipolar glass model.

We present the results of Monte Carlo simulations of the charge carrier transport in a disordered molecular system containing spatial and energetic disorders using the dipolar glass model. Model parameters of the material were chosen to fit a typical polar organic photoconductor polycarbonate doped with 30% of aromatic hydrazone, whose transport properties are well documented in literature. Simulated carrier mobility demonstrates a usual Poole-Frenkel field dependence and its slope is very close to the experimental value without using any adjustable parameter. At room temperature transients are universal with respect to the electric field and transport layer thickness. At the same time, carrier mobility does not depend on the layer thickness and transients develop a well-defined plateau where the current does not depend on time, thus demonstrating a non-dispersive transport regime. Tails of the transients decay as power law with the exponent close to -2. This particular feature indicates that transients are close to the boundary between dispersive and non-dispersive transport regimes. Shapes of the simulated transients are in very good agreement with the experimental ones. In summary, we provide a first verification of a self-consistency of the dipolar glass transport model, where major transport parameters, extracted from the experimental transport data, are then used in the transport simulation, and the resulting mobility field dependence and transients are in very good agreement with the initial experimental data.

[Functional significance of sulfated glycosaminoglycan complex for the control of fibroblast proliferation in vitro].

The effect of an original sulfated glycosaminoglycan (sGAG) mixture (keratan sulfate with chondroitin sulfate) was examined in the in vitro experiment with the cell culture of murine fibroblasts (cell line L929). Two forms (solution and gel) of the active substance were tested in different concentrations (0.1-5.0%). The growth dynamics of fibroblasts in culture was traced for the periods up to 144 h using the automated digital immersion confocal microscope. The study of the original sGAG mixture demonstrated the bimodal effect: low concentrations (0.1-0.5%) stimulated the proliferation of fibroblasts, while high concentrations (1-5%) possessed an antiproliferative effect. Changes of the form (solution or gel) had no effect on the functional properties of the mixture. High sGAG concentrations (3-5.0%), along with the antiproliferative effect, had a hidden weak cytotoxic action (a delayed effect).

[Treatment of diaphyseal femoral fractures with extramedullary compressive-dynamic osteosynthesis].

Since 2000 year 39 patients with diaphyseal femoral fractures have been treated using the technique of extramedullary compressive-dynamic osteosynthesis. Treatment is finished in 25 patients, 11 of them resumed their previous activities, while 14 did not. They are under follow-up and demonstrate different stages of fracture consolidation. The constructed device meets the requirements of extramedullary fixation and develops the necessary compression of the fracture zone. The flexible partly transfers the load to the fracture area, stimulating, thus, regeneration and consolidation of the lesion.