[Direct transfistulous ultrasound in minimally invasive surgical treatment of infected pancreatic necrosis]. / Pryamoe chresfistul'noe ul'trazvukovoe issledovanie pri minimal'no invazivnom khirurgicheskom lechenii patsientov s infitsirovannym pankreonekrozom.

OBJECTIVE: To develop a method for direct transfistulous ultrasound in minimally invasive treatment of infected pancreatic necrosis. MATERIAL AND METHODS: There were 148 patients with infected pancreatic necrosis between 2015 and 2019 at the Krasnodar City Clinical Hospital No. 2. Drainage with 28-32 Fr tubes was carried out at the first stage, endoscopic transfistulous sequestrectomy - at the second stage (19 (12.8%) patients). In 84 (56.8%) patients, we applied original diagnostic method (transfistulous ultrasonic assessment of inflammatory focus). RESULTS: There were 3 accesses to omental bursa in 93 (62.8%) patients and 2 in 43 (29.1%) patients. We also performed 2 access to retroperitoneal space in 63 (42.6%) patients and 1 access in 38 (25.8%) cases. Transfistulous ultrasound was used once in 19 (22.6%) patients, twice in 28 (33.3%) and 3 times in 37 (44.1%) patients. Examination was not performed in 18 (12.2%) patients due to the following reasons: migration of drainage catheters - 5, non-rectilinear fistulous tract - 13. No complications were observed. CONCLUSION: Transfistulous ultrasound makes it possible to diagnose pathological changes in the pancreas and parapancreatic tissue at various stages of surgical treatment.

[A modified method for percutaneous drainage of acute necrotic collections in patients with infected pancreatic necrosis]. / Modifitsirovannyi metod chreskozhnogo drenirovaniya ostrykh nekroticheskikh skoplenii u patsientov s infitsirovannym pankreonekrozom.

OBJECTIVE: To develop a modified method for percutaneous drainage of acute necrotic collections in patients with infected pancreatic necrosis. MATERIALS AND METHODS: Minimally invasive surgical technologies were used in 74 patients with infected acute necrotic collections at the Krasnodar Regional Clinical Hospital No. 2 between 2017 and 2019. Of these, 59 (79.7%) people underwent percutaneous drainage as a final treatment. In 11 (14.9%) patients, video sequestrectomy through the fistula was additionally used to increase efficiency of percutaneous drainage. RESULTS: PCD in our modification implies delivery of double-lumen drains 26-32 Fr in the same plane to zones of necrosis, their programmed replacement for prevention of obstruction and flexible endoscopy for control of pathological process. Local purulent-necrotic parapancreatitis occurred in 31 (41.9%) patients, widespread parapancreatitis - in 43 (58.1%) patients. There were 339 minimally invasive interventions. Laparotomy was required in 4 (5.4%) patients. Incidence of perioperative complications was 10.6%, mortality - 16.2%. CONCLUSION: A modified percutaneous drainage method may be used as final surgical treatment in 79.7% of patients with infected pancreatic necrosis.

[Technological features of open and minimally invasive surgical treatment of local complications of purulent-necrotic pancreatitis]. / Sravnenie tekhnologicheskikh osobennostei primeneniya otkrytykh i minimal'no invazivnykh sposobov khirurgicheskogo lecheniya mestnykh oslozhnenii gnoino-nekroticheskogo pankreatita.

There are various options for surgical treatment of purulent-necrotic pancreatitis with significant technological differences. Combining surgical methods other than traditional ones into a group of minimally invasive ones based on the principle of the absence of standard laparotomy is not entirely correct. The review presents modern methods of surgical treatment of acute pancreatitis, comparison of their technology regarding classical stages of surgical intervention and their classification.

[Transfistulous endoscopic sequestrectomy in the treatment of infected pancreatic necrosis]. / Sposob chresfistul'noi videoskopicheskoi nekrsekvestrektomii v lechenii infitsirovannogo pankreonekroza.

OBJECTIVE: To develop an effective minimally invasive method for the treatment of infected pancreatic necrosis. MATERIAL AND METHODS: There were 168 patients with infected pancreatic necrosis who were treated at the Regional Clinical Hospital No. 2 between 2011 and 2018. Eighty-seven (51.8%) patients underwent primary drainage with large-diameter double-lumen drains 28-32 Fr, and original technique of transfistulous endoscopic sequestrectomy was used. Puncture-drainage interventions with transfistulous endoscopic sequestrectomy were used in 23 (26.4%) patients with local and 64 (73.6%) patients with widespread purulent-necrotic parapancreatitis. RESULTS: Percutaneous channels are accesses to purulent-necrotic cavity and used for transfistulous endoscopic sequestrectomy. This procedure was performed 98 times. Time of primary sanitation in patients with 3 accesses in omental bursa was significantly less compared to 2 accesses (62±4.3 vs. 89±8.2 min, p<0.05). In case of repeated sanitation, time of intervention did not depend on the number of accesses. Incidence of local complications was 9.1%, extra-abdominal complications - 19.4%. Mortality rate was 12.6%. CONCLUSION: Original technique of transfistulous endoscopic sequestrectomy increases efficiency of sanitation of infected parapancreatitis, improves treatment outcomes and reduces mortality to 12.3%.

[Cutaneous and visceral leishmaniasis in patients with HIV infection in Russia. Case report].

The article contains information on the problem of the combined course of HIV infection and leishmaniasis: a number of statistical and overview data in the world. It also presents a brief description of known cases of HIV patients with leishmaniasis in the Russian Federation. In all cases the diagnostics of leishmaniasis was difficult due to the lack of alertness of physicians to this illness, as well as poor knowledge of epidemiological situation of leishmaniasis. All patients with visceral leishmaniasis but one caught it during their stay in Crimea. Cutaneous leishmaniasis was described in HIV infection in the Russian Federation for the second time and is associated with the patient's residence in the Chechen Republic.

[Minimally invasive surgical interventions in the treatment of severe acute pancreatitis]. / Mini-invazivnye khirurgicheskie vmeshatel'stva v lechenii patsientov s ostrym pankreatitom tyazheloi stepeni.

OBJECTIVE: To improve the outcomes in patients with severe destructive pancreatitis undergoing minimally invasive surgery. MATERIAL AND METHODS: There were 482 patients with acute destructive pancreatitis for the period from 2007 to 2016. Non-infected acute destructive pancreatitis was diagnosed in 58% (n=280) of patients, infected pancreatic necrosis - in 42% (n=202) of patients. Minimally invasive technologies were used in the treatment of purulent complications of destructive pancreatitis: endoscopic papillotomy, percutaneous puncture of fluid accumulations, ultrasound- and X-ray-assisted drainage of abscesses and retroperitoneal phlegmon. RESULTS: There were 688 drainage surgeries in 92 patients with infected pancreatic necrosis: US-assisted Seldinger drainage - 599 (87%), single-stage drainage - 89 (13%) cases. Percutaneous transfistular retroperitoneal interventions were made in 72 patients (one intervention - 29 patients, redo procedures - 43 patients). Complications associated with minimally invasive procedures developed in 2.7% (19) of cases. Six patients required laparotomy. Mean length of hospital-stay was 36.5 days. Mean rate of restitution of post-necrotic areas was 37.7 days. CONCLUSION: Minimally invasive procedures reduce overall mortality up to 6% in patients with acute pancreatitis and up to 14% in those with destructive forms of inflammation.

Chimera state in complex networks of bistable Hodgkin-Huxley neurons.

In this paper we study a chimera state in complex networks of bistable Hodgkin-Huxley neurons with excitatory coupling, which manifests as a termination of spiking activity of a part of interacting neurons. We provide a detailed investigation of this phenomenon in scale-free, small-world, and random networks and show that the chimera state is robust to the network topology. Nevertheless, network topological properties determine the stability of spatiotemporal states and therefore affect the excitability of the chimera state in the whole network. In particular, the scale-free network whose higher degree nodes are more stable to small perturbations is least exposed to chimera formation and exhibits an abrupt transition from a spiking to a silent regime. On the other hand, small-world and random networks are more likely to provide transitions to the chimera state.

Microscopic Nature of the First-Order Field-Induced Phase Transition in the Strongly Anisotropic Ferrimagnet HoFe_{5}Al_{7}.

We report on x-ray magnetic circular dichroism experiments in pulsed fields up to 30 T to follow the rotations of individual magnetic moments through the field-induced phase transition in the ferrimagnet HoFe_{5}Al_{7}. Near the ground state, we observe simultaneous stepwise rotations of the Ho and Fe moments and explain them using a two-sublattice model for an anisotropic ferrimagnet with weak intersublattice exchange interactions. Near the compensation point, we find two phase transitions. The additional magnetization jump reflects the fact that the Ho moment is no longer rigid as the applied field acts against the intersublattice exchange field.

Hybrid Sound Modes in One-Dimensional Quantum Liquids.

We study sound in a single-channel one-dimensional quantum liquid. In contrast to classical fluids, instead of a single sound mode we find two modes of density oscillations. The speeds at which these two sound modes propagate are nearly equal, with the difference that scales linearly with the small temperature of the system. The two sound modes emerge as hybrids of the first and second sounds, and combine oscillations of both density and entropy of the liquid.

Extended stability range of the non-Fermi liquid phase in UCoAl.

High pressure was used to investigate the stability of the non-Fermi liquid (NFL) state, observed in electrical resistivity of uranium-based band metamagnet UCoAl in a pure form (paramagnet) or with Fe substitution (ferromagnetic ground state), both in a single-crystal form. By combining the pressure variations of magnetization and resitivity in these materials the phase diagram for UCoAl had been constructed. The band metamagnet transforms into the ferromagnetic state as the critical metamagnetic field is reduced to zero by the lattice expansion analogous to the negative pressure. Within the same diagram, the increasing hydrostatic pressure drives the critical metamagnetic field upwards while reducing the magnetization increment at the transition. The NFL state persists to about 4-5 GPa. Although spin fluctuations play an important role in the character of UCoAl, they do not exhibit any criticality in the sense of divergence of parameters describing the resistivity around the Ferro-NFL phase transition, which is of the first order type.

Longitudinal Negative Magnetoresistance and Magnetotransport Phenomena in Conventional and Topological Conductors.

Recently, a large negative longitudinal (parallel to the magnetic field) magnetoresistance was observed in Weyl and Dirac semimetals. It is believed to be related to the chiral anomaly associated with topological electron band structure of these materials. We show that in a certain range of parameters such a phenomenon can also exist in conventional centrosymmetric and time-reversal invariant conductors, lacking topological protection of the electron spectrum and the chiral anomaly. We also discuss the magnetic field enhancement of the longitudinal components of the thermal conductivity and thermoelectric tensors.

Anomalous Hall Effect in Type-I Weyl Metals.

We study the ac anomalous Hall conductivity σ_{xy}(ω) of a Weyl semimetal with broken time-reversal symmetry. Even in the absence of free carriers these materials exhibit a "universal" anomalous Hall response determined solely by the locations of the Weyl nodes. We show that the free carriers, which are generically present in an undoped Weyl semimetal, give an additional contribution to the ac Hall conductivity. We elucidate the phy146sical mechanism of the effect and develop a microscopic theory of the free carrier contribution to σ_{xy}(ω). The latter can be expressed in terms of a small number of parameters (the electron velocity matrix, the Fermi energy µ, and the "tilt" of the Weyl cone). The resulting σ_{xy}(ω) has resonant features at ω∼2µ which may be used to separate the free carrier response from the filled-band response using, for example, Kerr effect measurements. This may serve as a diagnostic tool to characterize the doping of individual valleys.

Second Sound in Systems of One-Dimensional Fermions.

We study sound in Galilean invariant systems of one-dimensional fermions. At low temperatures, we find a broad range of frequencies in which in addition to the waves of density there is a second sound corresponding to the ballistic propagation of heat in the system. The damping of the second sound mode is weak, provided the frequency is large compared to a relaxation rate that is exponentially small at low temperatures. At lower frequencies, the second sound mode is damped, and the propagation of heat is diffusive.

Magneto-elastic coupling across the first-order transition in the distorted kagome lattice antiferromagnet Dy3Ru4Al12.

Structural changes through the first-order paramagnetic-antiferromagnetic phase transition of Dy3Ru4Al12 at 7 K have been studied by means of X-ray diffraction and thermal expansion measurements. The compound crystallizes in a hexagonal crystal structure of Gd3Ru4Al12 type (P63/mmc space group), and no structural phase transition has been found in the temperature interval between 2.5 and 300 K. Nevertheless, due to the spin-lattice coupling the crystal volume undergoes a small orthorhombic distortion of the order of 2×10-5 as the compound enters the antiferromagnetic state. We propose that the first-order phase transition is not driven by the structural changes but rather by the exchange interactions present in the system.

UH3-based ferromagnets: new look at an old material.

UH3 is the first discovered material with ferromagnetism based purely on the 5f electronic states, known for more than half century. Although the U metal is Pauli paramagnet, the reduced 5f-5f overlap in compounds allows for moment formation and ordering, typically if the U-U spacing exceeds the Hill limit, i.e. about 340 pm. The stable form of UH3, known as ß-UH3, has rather high TC ≈ 170 K. Such high value is rather unusual, considering dU-U = 331 pm. Properties of metastable α-UH3 with dU-U = 360 pm could be never well established. Using the fact that α-UH3 is in fact bcc U with interstitials filled by H, we attempted to synthesize α-UH3 starting from the γ-U alloys, with the bcc structure retained to room temperature by doping combined with ultrafast cooling. While up to 15% Zr a contamination by ß-UH3 was obtained, 20% Zr yielded single phase α-UH3. The TC value remains high and very similar to ß-UH3. One can see an increase up to 187 K for 15% Zr, followed by a weak decrease. Magnetic moments remain close to 1 µB/U atom. An insight is provided by ab-initio calculations, revealing a a charge transfer towards H-1s states, depopulating the U-6d and 7s states, leaving almost pure 5f character around the Fermi level. The 5f magnetism exhibits a high coercivity (µ0Hc up to 5.5 T) and large spontaneous volume magnetostriction of 3.2*10-3. Even higher increase of TC, reaching up to 203 K, can be achieved in analogous Mo stabilized hydrides, which yield an amorphous structure. The compounds represent, together with known hydrides of U6Fe and U6Co, a new group of robust 5f ferromagnets with small dU-U but high TC. Although common hydrides are fine powders, some of the new hydrides described as (UH3)(1-x)T x (T = Zr or Mo) remain monolithic, which allows to study transport and thermodynamic properties.

Aharonov-Bohm oscillations in singly connected disordered conductors.

We show that the transport and thermodynamic properties of a singly connected disordered conductor exhibit quantum Aharonov-Bohm oscillations as a function of the total magnetic flux through the sample. The oscillations are associated with the interference contribution from a special class of electron trajectories confined to the surface of the sample.

Electronic properties of α-UH3 stabilized by Zr.

Pure hydride of the α-UH3 type without any ß-UH3 admixture was prepared by high-pressure hydrogenation of bcc U stabilized by Zr. Such material, characterized by a general formula (UH3)1-x Zr x , is stable in air at ambient and elevated temperatures. H release is observed between 400-450 °C similar to ß-UH3. Its stability allowed to measure magnetic properties, specific heat, and electrical resistivity in a wide temperature range. Despite rather different crystal structure and inter-U spacing, the electronic properties are almost identical to ß-UH3. Its ferromagnetic ground state with Curie temperature TC ≈ 180 K (weakly and non-monotonously dependent on Zr concentration) and U moments of 1.0 µB indicate why mixtures of α- and ß-UH3 exhibited only one transition. Magnetic ordering leads to a large spontaneous magnetostriction ωs = 3.2*10-3, which can be explained by the increase of the spin moment between the paramagnetic (Disordered Local Moment) and the ferromagnetic state. The role of orbital moments in magnetism is indicated by fully relativistic electronic structure calculations.

High-field magnetization and magnetoelasticity of single crystalline HoFe5Al7.

Magnetization and ultrasound measurements have been performed in pulsed magnetic fields up to 60 T on a ferrimagnetic HoFe5Al7 single crystal (Curie temperature TC = 216 K, compensation point Tcomp = 65 K) with a tetragonal crystal structure of the ThMn12-type. The compound exhibits a high magnetic anisotropy of the easy-plane type. A large anisotropy is also observed within the basal plane having an easy-magnetization direction along the [110] axis with the spontaneous magnetic moment Ms = 2 µB/f.u. at T = 2 K. Along the easy axis, two first-order field-induced magnetic transitions are observed. At both transitions sharp anomalies in the acoustic properties are found. The critical fields of the transitions depend on temperature in a different manner. Within molecular-field theory and using the high-field magnetization data the Ho-Fe inter-sublattice exchange parameter has been determined to be nHoFe ≈ 4 T/µB. The magnetoelasticity has also been probed by magnetization measurements under hydrostatic pressure. TC decreases with a rate dTC/dp = -10 K/GPa, whereas Tcomp increases with dTcomp/dp = 3.5 K/GPa.

Unusual 5f magnetism in the U2Fe3Ge ternary Laves phase: a single crystal study.

Magnetic properties of the intermetallic compound U(2)Fe(3)Ge were studied on a single crystal. The compound crystallizes in the hexagonal Mg(2)Cu(3)Si structure, an ordered variant of the MgZn(2) Laves structure (C14). U(2)Fe(3)Ge displays ferromagnetic order below the Curie temperature T(C) = 55 K and presents an exception to the Hill rule, as the nearest inter-uranium distances do not exceed 3.2 Å. Magnetic moments lie in the basal plane of the hexagonal lattice, with the spontaneous magnetic moment M(s) = 1.0 µ(B)/f.u. at T = 2 K. No anisotropy within the basal plane is detected. In contrast to typical U-based intermetallics, U(2)Fe(3)Ge exhibits very low magnetic anisotropy, whose field does not exceed 10 T. The dominance of U in the magnetism of U(2)Fe(3)Ge is suggested by the (57)Fe Mössbauer spectroscopy study, which indicates very low or even zero Fe moments. Electronic structure calculations are in agreement with the observed easy-plane anisotropy but fail to explain the lack of an Fe contribution to the magnetism of U(2)Fe(3)Ge.

Electromagnetic propulsion and separation by chirality of nanoparticles in liquids.

We introduce a new mechanism for the propulsion and separation by chirality of small ferromagnetic particles suspended in a liquid. Under the action of a uniform dc magnetic field H and an ac electric field E isomers with opposite chirality move in opposite directions. Such a mechanism could have a significant impact on a wide range of emerging technologies. The component of the chiral velocity that is odd in H is found to be proportional to the intrinsic orbital and spin angular momentum of the magnetized electrons. This effect arises because a ferromagnetic particle responds to the applied torque as a small gyroscope.