Unconventional Hysteretic Transition in a Charge Density Wave.

Hysteresis underlies a large number of phase transitions in solids, giving rise to exotic metastable states that are otherwise inaccessible. Here, we report an unconventional hysteretic transition in a quasi-2D material, EuTe_{4}. By combining transport, photoemission, diffraction, and x-ray absorption measurements, we observe that the hysteresis loop has a temperature width of more than 400 K, setting a record among crystalline solids. The transition has an origin distinct from known mechanisms, lying entirely within the incommensurate charge density wave (CDW) phase of EuTe_{4} with no change in the CDW modulation periodicity. We interpret the hysteresis as an unusual switching of the relative CDW phases in different layers, a phenomenon unique to quasi-2D compounds that is not present in either purely 2D or strongly coupled 3D systems. Our findings challenge the established theories on metastable states in density wave systems, pushing the boundary of understanding hysteretic transitions in a broken-symmetry state.

Externally Controlled Magnetism and Band Gap in Twisted Bilayer Graphene.

We theoretically study the effects of electron-electron interaction in twisted bilayer graphene in a transverse dc electric field. When the twist angle is not very small, the electronic spectrum of the bilayer consists of four Dirac cones inherited from each graphene layer. An applied bias voltage leads to the appearance of two holelike and two electronlike Fermi surface sheets with perfect nesting among electron and hole components. Such a band structure is unstable with respect to the exciton band-gap opening due to the screened Coulomb interaction. The exciton order parameter is accompanied by spin-density-wave order. The gap depends on the twist angle and can be varied by a bias voltage. This result correlates well with recent transport measurements [J.-B. Liu et al., Sci. Rep. 5, 15285 (2015)SRCEC32045-232210.1038/srep15285]. Our proposal allows the coexistence of (i) an externally controlled semiconducting gap and (ii) a nontrivial multicomponent magnetic order. This is interesting for both fundamental research and applications.

Spin-Valley Half-Metal as a Prospective Material for Spin Valleytronics.

Half-metallicity (full spin polarization of the Fermi surface) usually occurs in strongly correlated electron systems. We demonstrate that doping a spin-density wave insulator in the weak-coupling regime may also stabilize half-metallic states. In the absence of doping, the spin-density wave is formed by four nested bands [i.e., each band is characterized by charge (electron or hole) and spin (up or down) labels]. Of these four bands, only two accumulate the charge carriers introduced by doping, forming a half-metallic two-valley Fermi surface. Depending on the parameters, the spin polarizations of the electronlike and holelike valleys may be either (i) parallel or (ii) antiparallel. The Fermi surface of (i) is fully spin polarized (similar to usual half-metals). Case (ii), referred to as "a spin-valley half-metal," corresponds to complete polarization with respect to the spin-valley operator. The properties of these states are discussed.

[A retrospective historical study evaluating the safe use of current antidepressants in cardiology practice]. / Retrospektivnoe arkhivnoe issledovanie po otsenke bezo-pasnosti primeneniia sovremennykh antidepressantov v kardiologicheskoi praktike.

AIM: To confirm the data available in the literature on the cardiac safety of antidepressants. SUBJECTS AND METHODS: The archival data of 146 case histories were retrospectively analyzed. A study sample consisted of 96 cardiac inpatients regularly taking an antidepressant for more than 3 days during treatment for the underlying cardiovascular disease. The safe use of antidepressants was evaluated in terms of initial electrocardiogram (ECG) QTc interval changes, systolic and diastolic blood pressures (BP) (SBP and DBP), heart rate (HR), and hemorrhagic complications. The data obtained over periods of 3- and 6-8 days were analyzed. RESULTS: The sample showed no clinically significant ECG QTc interval changes when taking regularly antidepressants within 8 days. Analysis of the dynamics of BP and HR in patients receiving antidepressants revealed no statistically significant differences in these indicators before and 3 and 6-8 days after drug administration. No case of hemorrhagic complications was seen in the study group taking antidepressants. CONCLUSION: The investigation generally confirms the high cardiac safety of new-generation antidepressants within at least the first week of therapy. Noteworthy are the low daily drug dosages (relatively specified in the instructions) that are sufficient for most cardiac patients with depressive disorders and an additional factor for minimizing adverse reactions.

[Primary percutaneous interventions into the coronary arteries in patients with diabetes mellitus]. / Pervichnye chreskozhnye vmeshatel'stva na koronarnykh arteriyakh u patsientov s sakharnym diabetom.

AIM: to investigate the specific features and results of percutaneous interventions (PCI) into the coronary arteries in patients with acute ST-segment elevation myocardial infarction (MI) and diabetes mellitus (DM) in clinical practice. SUBJECTS AND METHODS: A study group consisted of 120 patients with a history of type 2 DM, who had undergone primary PCI in 2008 to 2013. A comparison group included 601 patients without a history of DM. RESULTS: Assessment of the results of hospital interventions revealed no differences between the study and comparison groups in mortality rates (4.1 and 3.2%, respectively; p=0.376), stent thromboses (0.8 and 1.2%, respectively; p=0.601), and recurrent MI (0 and 1.5%, respectively; p=0.189). No differences were determined in the combined index including death, recurrent MI, and stent thrombosis (5 and 5%; p=0.985). At the same time, the no-reflow phenomenon developed statistically significantly more frequently in the patients with DM (7.4 and 2.8%; p=0.019). Binary logistic regression established independent associations between the presence of DM and patient age (odds ratio (OR) 1.04; 95% confidence interval (CI) 1.02 to 1.07; p<0.001), female sex (OR 0.36; 95% CI 0.23 to 0.56; p<0.001), and higher body mass index (OR 1.1; 95% CI 1.06 to 1.16; p<0.04). CONCLUSION: Primary PCIs in patients with DM are an effective and safe method for revascularization in acute ST-segment elevation MI and these are not followed by increases in mortality and frequency of major poor cardiac complications at the hospital stage despite the more common development of the no-reflow phenomenon.

Heat Transport in Spin Chains with Weak Spin-Phonon Coupling.

The heat transport in a system of S=1/2 large-J Heisenberg spin chains, describing closely Sr(2)CuO(3) and SrCuO(2) cuprates, is studied theoretically at T≪J by considering interactions of the bosonized spin excitations with optical phonons and defects. Treating rigorously the multiboson processes, we derive a microscopic spin-phonon scattering rate that adheres to an intuitive picture of phonons acting as thermally populated defects for the fast spin excitations. The mean-free path of the latter exhibits a distinctive T dependence reflecting a critical nature of spin chains and gives a close description of experiments. By the naturalness criterion of realistically small spin-phonon interaction, our approach stands out from previous considerations that require large coupling constants to explain the data and thus imply a spin-Peierls transition, absent in real materials.

EFFECT OF CYP2C19 GENETIC POLYMORPHISMS ON THE EFFICACY OF PROTON PUMP INHIBITOR-BASED TRIPLE ERADICATION THERAPY IN SLAVIC PATIENTS WITH PEPTIC ULCERS: A META-ANALYSIS.

INTRODUCTION: Several meta-analyzes reported the effect of CYP2C19 genetic polymorphisms on the efficacy of proton pump inhibitor-based triple therapy for Helicobacter pylori eradication. Most of the studies which were included in these meta-analyzes were held on Asian population. Thus, there is lack of information about the effect of CYP2C19 genetic polymorphisms on the efficacy of proton pump inhibitor-based triple eradication therapy in Slavic patients with peptic ulcers. The aim of the study - to determine whether CYP2C19 affect the efficacy of proton pump inhibitor-based triple eradica- tion therapy in Slavic patients with peptic ulcers. METHODS: Data search was performed using Russian index of scientific citation database, Google Scholar and MEDLINE PubMed. Statistics was held in Review Manager v 5.3. The odds ratio (OR) and 95% confidence interval (95% Cl) for eradication of H.pylori was estimated in a fixed-effect model when no heterogeneity across the studies was indicated. RESULTS: Four articles published between 2008 and 2015 were included in meta-analysis (three Russian studies, one Polish study). Eradication rates were significantly lower in CYP2C19 extensive metabolizers of proton pump inhibitors than in a combined group of intermediate and poor metabolizers (OR = 1,90, CI-95% 1,08-3,34, p = 0,03; heterogeneity: 12= 0%, p = 0,74). We also found that proton pump inhibitor-based triple eradication therapy achieved higher rates in poor metabolizers than in a combined group of intermediate and extensive metabolizers of CYP2C19 (OR= 5,48 CI-95% 1,51-19,93, p = 0,01; heterogeneity: F= 0%, p = 0,66). CONCLUSION: The impact of CYP2C19 genetic polymorphisms on the efficacy of proton pump inhibitor-based triple eradication therapy in Slavic patients appears significant.

ABCB1 polymorphism and acenocoumarol safety in patients with valvular atrial fibrillation.

BACKGROUND: Oral anticoagulant drugs (AD) are commonly used to treat patients with thromboembolic diseases. The ADs have narrow therapeutic index and wide pharmacokinetic and pharmacodynamic interindividual variability. Some genetic variations could influence interindividual variability in response to AD. Acenocoumarol (AC) is a coumarin, vitamin K derivate with antagonistic activity, used as anticoagulant therapy mainly in Central Europe and Latin America. P - glycoprotein (PGP), a transporter encoded by the ABCB1 gene, plays a major role in the drug disposition [1]. PGP is expressed in normal tissues, where it performs a defensive role against potentially toxic substances in intestinal cells and endothelial cells of the brain capillary endothelium. ABCB1 - is highly polymorphic, C3435T polymorphism in exon 26 has been associated with the expression of PGP [2]. There is some evidence that PGP could influence coumarin sensitivity. OBJECTIVE: To assess effects of the ABCB1 pilymorphisms on safety profile and dosing regimen of acenocoumarol in the patients with valvular atrial fibrillation. METHODS: 50 patients (34 male and 16 female), 40-70 years of age were included. All patients received acenocoumarol at doses of 1-6 mg daily with a target international normalized ratio (INR) of 2.0 to 3.0. Genotyping for polymorphism marker C3435T of ABCB1 gen was performed using PCR and RFLP (restriction fragment length polymorphisms) techniques. Statistics were performed by Fishers exact tests. All enrolled patients provided written informed consent. RESULTS: Genotype CC was found in 10 patients (20%), genotype CT in 25 patients (50%) and genotype TT in 15 patients (30%). In the CC group (n = 10) bleeding was found in 1 patient (2%). There were 19 patients (38%) with bleedings in combined group of CT and TT genotype (p = 0.0366). We compared the average doses of acenocoumarol in groups identified according to their genotypes: CC (3.45 mg/day), CT (2.64 mg/day), TT (3.07 mg/day) and found no significant differences. CONCLUSIONS: ABCB1 CT and TT genotypes were found to be significantly associated with higher risk of bleeding. There was no influence of ABCB1 polymorphisms on dosing regimens of acenocoumarol.

One-dimensional fermions with neither Luttinger-liquid nor Fermi-liquid behavior.

It is well known that, generically, one-dimensional interacting fermions cannot be described in terms of a Fermi liquid. Instead, they present a different phenomenology, that of a Tomonaga-Luttinger liquid: the Landau quasiparticles are ill defined, and the fermion occupation number is continuous at the Fermi energy. We demonstrate that suitable fine tuning of the interaction between fermions can stabilize a peculiar state of one-dimensional matter, which is dissimilar to both Tomonaga-Luttinger and Fermi liquids. We propose to call this state a quasi-Fermi liquid. Technically speaking, such a liquid exists only when the fermion interaction is irrelevant (in the renormalization group sense). The quasi-Fermi liquid exhibits the properties of both a Tomonaga-Luttinger liquid and a Fermi liquid. Similar to a Tomonaga-Luttinger liquid, no finite-momentum quasiparticles are supported by the quasi-Fermi liquid; on the other hand, its fermion occupation number demonstrates a finite discontinuity at the Fermi energy, which is a hallmark feature of a Fermi liquid. A possible realization of the quasi-Fermi liquid with the help of cold atoms in an optical trap is discussed.

Instabilities of the AA-stacked graphene bilayer.

Tight-binding calculations predict that the AA-stacked bilayer graphene has one electron and one hole conducting band, and that the Fermi surfaces of these bands coincide. We demonstrate that as a result of this degeneracy, the bilayer becomes unstable with respect to a set of spontaneous symmetry violations. Which of the symmetries is broken depends on the microscopic details of the system. For strong on-site Coulomb interaction we find that antiferromagnetism is the most stable order parameter. For an on-site repulsion energy typical for graphene systems, the antiferromagnetic gap can exist up to room temperature.

Evaluation of the two-particle propagator for the Hubbard model with the help of the Hubbard-I approximation.

The Hubbard-I approximation is generalized to allow for direct evaluation of the equal-time anomalous two-electron propagator for the Hubbard model on a two-dimensional square lattice. This propagator is compared against the quantum Monte Carlo data obtained by Aimi and Imada (2007 J. Phys. Soc. Japan 76 113708) in the limit of strong electron-electron interaction. The Hubbard-I predictions are in good qualitative agreement with the Monte Carlo results. In particular, d-wave correlations decay as cr( - 3) ('free-electron' behaviour) if the separation r exceeds 2-3 lattice constants. However, the Hubbard-I approximation underestimates the coefficient c by a factor of about 3. We conclude that the Hubbard-I approximation, despite its simplicity and artefacts, captures the qualitative behaviour of the two-particle propagator for the Hubbard model, at least for moderate values of r.

[Changes of dynamics of the lymph production after the cannulation of the thoracic duct].

An adequate cannulation of the thoracic duct is always accompanied with appropriate dynamics of the lymph production. As a result, the daily output of lymph increases from 2.0 to 2.2 times during 4-5 days. To find out the reasons of the lymph production changes were examined 57 patients with acute purulent inflammatory diseases of abdominal and thoracic organs. It was determined that the lymph production change is conditioned by 2 factors: the first is the stopping of the flow into venous vessels via lympho-venous anastomosies of the thoracic duct, lymphatic trunks and large lymphatic vessels. It leads to a mobilization of the greater part of lymph in lymphatic vessels. The second is the speeding-up of lymph production.

Effect of artrofoon and SCENAR therapy on parameters of LPO and antioxidant system of the blood in patients with peritonitis in postoperative period.

Administration of artrofoon in combination with SCENAR therapy to patients with localized suppurative peritonitis in the postoperative period considerably reduced plasma MDA level, stabilized ceruloplasmin activity, and increased catalase activity in erythrocytes compared to the corresponding parameters in patients receiving standard treatment in combination with SCENAR therapy.

Thermal conductivity of quasi-one-dimensional antiferromagnetic spin-chain materials.

We study heat transport in quasi-one-dimensional spin-chain systems by considering the model of one-dimensional bosonic spin excitations interacting with three-dimensional phonons and impurities in the limit of weak spin-lattice coupling and fast spin excitations. A combined effect of the phonon and impurity scatterings yields the following spin-boson thermal conductivity behavior: kappa(s) proportional to T2 at low, kappa(s) proportional to T-1 at intermediate, and kappa(s)= const at higher temperatures. Our results agree well with the existing experimental data for Sr2CuO3. We predict an unusual dependence on the impurity concentration for a number of observables and propose further experiments.

[Development of liver surgery at the Vishnevsky Central Military Clinical Hospital]. / Razvitie gepatokhirurgii v TsVKG im. A. A. Vishnevskogo.

The work of coloproctological center of Vishnevsky Central Military Clinical Hospital for he last 10 years is analyzed. The increased number of treated patients and surgical interventions is noted. The greatest group includes the oncological patients and 90% of them are operated radically. Among the peculiarities of treatment tactics the introduction of laparoscopic operations, interoperation intraperitoneal hyperthermal chemotherapy for relapses and metastases, Lango operation for haemorrhoids are noted. 72 casualties with colon injuries were treated in the center.

[Invaginated esophageal anastomosis]. / Invaginatsionnyi pishchevodnyi anastomoz.

Extirpation of the stomach accounts for 55.5% of all radical surgery for gastric cancer. Five hundred and sixty-two operations with creation of invaginated esophageal-intestinal (gastric) anastomosis were performed. The surgical technique is presented, its positive points are demonstrated. Main advantages of the invaginated anastomosis are physiologic function in postoperative period and a decreased rate of sutures insufficiency. Complications after extirpation and proximal resection of the stomach were seen in 17.6% cases, 5.9% patients died. Insufficiency of anastomosis sutures was in 8 (14%) patients, 4 (0.7%) of them died.

[Cryosurgical treatment in metastatic liver cancer]. / [Kriokhirugicheskoe lechenie metastaticheskogo raka pecheni]

All patients endured cryosurgical operations well. Right-sided pleurisy developed in one patient that was eliminated by single puncture of pleural cavity. Short thrombocytopenia was observed in two patients. At present the patients are under dynamic control and the signs of further tumoral growth in the liver are not revealed. According to the data of ultrasonic investigation and computer tomography the process of connective tissue organization expressiveness of which depends on time of surgical intervention was noted in the areas of hepatic tissue subjected to cryosurgery.

[Infectious complications of severe trauma: achievements and problems]. / Infektsionnye oslozhneniia tiazheloi travmy: dostizheniia i problemy.

On the base of treatment results obtained in 2000 casualties the pathogenically substantiated classification of infectious complications of the injuries and traumas was proposed. The principles of classification are in conformity with modern ideas connected with the conception of systemic inflammatory response, the theory of general adaptation and the concept of traumatic disease. The classification determines the purposeful diagnostic tactics and provides the preventative therapy of traumas' infectious complications. Selection of special direction in the surgery of injuries in order to solve the problem of traumas' infectious complications in scientific, methodical and practical aspects is substantiated. First of all it is creation of specialized centers that provide the introduction into medical practice of the modern conception of traumas' infectious complications.