Observation of topological superconductivity in a stoichiometric transition metal dichalcogenide 2M-WS2.

Topological superconductors (TSCs) are unconventional superconductors with bulk superconducting gap and in-gap Majorana states on the boundary that may be used as topological qubits for quantum computation. Despite their importance in both fundamental research and applications, natural TSCs are very rare. Here, combining state of the art synchrotron and laser-based angle-resolved photoemission spectroscopy, we investigated a stoichiometric transition metal dichalcogenide (TMD), 2M-WS2 with a superconducting transition temperature of 8.8 K (the highest among all TMDs in the natural form up to date) and observed distinctive topological surface states (TSSs). Furthermore, in the superconducting state, we found that the TSSs acquired a nodeless superconducting gap with similar magnitude as that of the bulk states. These discoveries not only evidence 2M-WS2 as an intrinsic TSC without the need of sensitive composition tuning or sophisticated heterostructures fabrication, but also provide an ideal platform for device applications thanks to its van der Waals layered structure.

Observation and control of the weak topological insulator state in ZrTe5.

A quantum spin Hall (QSH) insulator hosts topological states at the one-dimensional (1D) edge, along which backscattering by nonmagnetic impurities is strictly prohibited. Its 3D analogue, a weak topological insulator (WTI), possesses similar quasi-1D topological states confined at side surfaces. The enhanced confinement could provide a route for dissipationless current and better advantages for applications relative to strong topological insulators (STIs). However, the topological side surface is usually not cleavable and is thus hard to observe. Here, we visualize the topological states of the WTI candidate ZrTe5 by spin and angle-resolved photoemission spectroscopy (ARPES): a quasi-1D band with spin-momentum locking was revealed on the side surface. We further demonstrate that the bulk band gap is controlled by external strain, realizing a more stable WTI state or an ideal Dirac semimetal (DS) state. The highly directional spin-current and the tunable band gap in ZrTe5 will provide an excellent platform for applications.

Determination of interatomic coupling between two-dimensional crystals using angle-resolved photoemission spectroscopy.

Lack of directional bonding between two-dimensional crystals like graphene or monolayer transition metal dichalcogenides provides unusual freedom in the selection of components for vertical van der Waals heterostructures. However, even for identical layers, their stacking, in particular the relative angle between their crystallographic directions, modifies properties of the structure. We demonstrate that the interatomic coupling between two two-dimensional crystals can be determined from angle-resolved photoemission spectra of a trilayer structure with one aligned and one twisted interface. Each of the interfaces provides complementary information and together they enable self-consistent determination of the coupling. We parametrise interatomic coupling for carbon atoms by studying twisted trilayer graphene and show that the result can be applied to structures with different twists and number of layers. Our approach demonstrates how to extract fundamental information about interlayer coupling in a stack of two-dimensional crystals and can be applied to many other van der Waals interfaces.

Publisher Correction: A weak topological insulator state in quasi-one-dimensional bismuth iodide.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

['Point of no return' in diabetic neuropathies: a dangerous delusion]. / 'Tochka nevozvrata' pri diabeticheskikh neiropatiiakh: opasnoe zabluzhdenie.

Polyneuropathy in patients with diabetes mellitus is manifested by a lesion of peripheral sensory, motor and autonomic nervous system. Different severity of damage of sensory, motor and autonomic fibers in typical and atypical forms of diabetic polyneuropathy, requires a differentiated approach to therapy, but not the rejection of its implementation. In an interdisciplinary consensus, consultations are held with physicians from different regions of the Russian Federation, and modern methods of diagnosing and assessing the severity of diabetic polyneuropathies, which determine the algorithm for treating patients, are discussed.

[Investigation of the metabolic features of primary glioblastomas by Tc-MIBI SPECT/CT and evaluation of their effect on disease prognosis]. / Issledovanie metabolicheskikh osobennostei pervichnykh glioblastom metodom OFÉKT-KT s Tc-MIBI s otsenkoi ikh vliianiia na prognoz zabolevaniia.

OBJECTIVE: To study the effect of metabolic characteristics of the tumor determined by 99mTc-MIBI single-photon emission computed tomography (SPECT) and various molecular genetic features on the outcomes of combination treatment of hemispheric glioblastomas. MATERIAL AND METHODS: This single-center prospective cohort study involved 68 patients aged 25-78 years (38 males and 30 females) with primary glioblastomas. Hypermetylation of the promotor region of the MGMT gene was observed in 24 (42%) out of 57 patients. The IDH1 mutation was revealed in two (3.5%) patients. The catamnestic data were available for 66 out of 68 patients. The first SPECT/CT study was carried out before chemoradiation therapy; the second SPECT/CT study was performed after the chemoradiation therapy. In each study, quantitative measures were calculated for the early (15-30 min after the patient had received a radiopharmaceutical) and late (after 45-60 min) phases. RESULTS: The actuarial survival rates after 12 and 24 months were 69.6 and 29.1%, respectively. The median overall survival rate was 17.5 months (95% CI 12.9-20.3). Favorable prognostic factors for overall survival included the higher uptake index (UI) in the late phase compared to UI in the early phase of the first SPECT/CT study (p=0.0444), dynamics of changes in UI during the second SPECT/CT compared to baseline over 10% (p=0.0436), MGMT hypermethylation (p=0.0003), and duration of the period between surgery and initiation of chemoradiotherapy being <1 month (p=0.0008). No statistically significant correlations were revealed between the absolute UI values in the tumor and its molecular genetic features. CONCLUSION: The 99mTc-MIBI SPECT/CT can be used to predict overall survival and to plan radiation therapy of glioblastoma as it is more readily available at primary healthcare facilities than amino acid PET.

[Secondary spondylogenic epidural abscess]. / Vtorichnyi spondilogennyi épidural'nyi abstsess.

The article presents the results of a retrospective analysis of 200 patients with hematogenous osteomyelitis of the spine who were treated in the Tyumen Regional Clinical Hospital #2. Neurological disorders were present in 37 patients (group I); 163 patients (group II) had no neurological disorders; according to CT and MRI, secondary spondylogenic epidural abscess was diagnosed in 24 patients. At admission, the severity of neurological deficit assessed using the Frankel scale was as follows: Grade A - 6 cases, Grade B - 7 cases, Grade C - 17 cases, Grade D - 5 cases, and Grade E - 2 cases (epidural abscess without neurological deficit). At discharge, the severity of neurological deficit was as follows: Grade A - 3 cases, Grade B - 2 cases, Grade C - 13 cases, Grade D - 11 cases, and Grade E - 8 cases. In group I, 35 out of 37 patients underwent surgery; of these, 21 patients had improvements. There were no statistically significant differences in neurological deficit changes between patients with and without epidural abscess. In 12 patients, the neurological status remained unchanged. Two patients died. We present an analysis of the severity of neurological symptoms, depending on the spinal lesion level, and the results of microbiological tests. Changes in neurological symptoms in lesions of various spinal parts are described. Cervical spine lesions and the process caused by S. aureus are shown to significantly increase the risk of neurological disorders. An active surgical approach for complicated forms of spinal osteomyelitis provided partial or complete regression of neurological disorders in 62.2% of cases.

A weak topological insulator state in quasi-one-dimensional bismuth iodide.

The major breakthroughs in understanding of topological materials over the past decade were all triggered by the discovery of the Z2-type topological insulator-a type of material that is insulating in its interior but allows electron flow on its surface. In three dimensions, a topological insulator is classified as either 'strong' or 'weak'1,2, and experimental confirmations of the strong topological insulator rapidly followed theoretical predictions3-5. By contrast, the weak topological insulator (WTI) has so far eluded experimental verification, because the topological surface states emerge only on particular side surfaces, which are typically undetectable in real three-dimensional crystals6-10. Here we provide experimental evidence for the WTI state in a bismuth iodide, ß-Bi4I4. Notably, the crystal has naturally cleavable top and side planes-stacked via van der Waals forces-which have long been desirable for the experimental realization of the WTI state11,12. As a definitive signature of this state, we find a quasi-one-dimensional Dirac topological surface state at the side surface (the (100) plane), while the top surface (the (001) plane) is topologically dark with an absence of topological surface states. We also find that a crystal transition from the ß-phase to the α-phase drives a topological phase transition from a nontrivial WTI to a normal insulator at roughly room temperature. The weak topological phase-viewed as quantum spin Hall insulators stacked three-dimensionally13,14-will lay a foundation for technology that benefits from highly directional, dense spin currents that are protected against backscattering.

[Diabetic and non-diabetic neuropathies in patients with diabetes mellitus]. / Diabeticheskie i nediabeticheskie polineiropatii u patsientov s sakharnym diabetom.

Diabetic polyneuropathy is the most often complication of diabetes mellitus. However, patients with diabetes may have other neuropathies, which need to be recognized and treated. Chronic nnflammatory demyelinating polyneuropathy is the most common non-diabetic polyneuropathy in patients with diabetes. The article discusses the classification, clinical features of diabetic and nondiabetic polyneuropathies, modern methods of diagnosis and approaches to treatment.

Metallic phase in stoichiometric CeOBiS2 revealed by space-resolved ARPES.

Recently CeOBiS2 system without any fluorine doping is found to show superconductivity posing question on its origin. Using space resolved ARPES we have found a metallic phase embedded in the morphological defects and at the sample edges of stoichiometric CeOBiS2. While bulk of the sample is semiconducting, the embedded metallic phase is characterized by the usual electron pocket at X point, similar to the Fermi surface of doped BiS2-based superconductors. Typical size of the observed metallic domain is larger than the superconducting correlation length of the system suggesting that the observed superconductivity in undoped CeOBiS2 might be due to this embedded metallic phase at the defects. The results also suggest a possible way to develop new systems by manipulation of the defects in these chalcogenides with structural instability.

[Vestibular migraine: diagnostic difficulties and treatment optimization]. / Vestibuliarnaia migren': diagnostika i optimizatsiia terapii.

AIM: The study aimed at showing actual information about vestibular migraine and presenting different features of vestibular migraine for prevention of diagnostic mistakes and choosing an effective treatment. MATERIAL AND METHODS: Fifty patients with vestibular migraine were diagnosed according to the International Classification of Headache Disorders 3rd edition and examined in a neurological department. RESULTS: Problems with outpatient diagnosis and treatment were found. Many patients were not diagnosed correctly and, therefore, did not receive effective management of vestibular migraine. All clinical features, information of disease history and different objective signs were important for differential diagnosis with other types of dizziness. Management according to guidelines for migraine treatment and recent research of vestibular migraine showed its efficiency for patients. CONCLUSION: Spreading of actual information about vestibular migraine is important due to its underdiagnosis. Knowledge of clinical features is helpful for diagnosis and differential diagnosis. Treatment approaches according to guidelines and last research should be used.

Indium selenide: an insight into electronic band structure and surface excitations.

We have investigated the electronic response of single crystals of indium selenide by means of angle-resolved photoemission spectroscopy, electron energy loss spectroscopy and density functional theory. The loss spectrum of indium selenide shows the direct free exciton at ~1.3 eV and several other peaks, which do not exhibit dispersion with the momentum. The joint analysis of the experimental band structure and the density of states indicates that spectral features in the loss function are strictly related to single-particle transitions. These excitations cannot be considered as fully coherent plasmons and they are damped even in the optical limit, i.e. for small momenta. The comparison of the calculated symmetry-projected density of states with electron energy loss spectra enables the assignment of the spectral features to transitions between specific electronic states. Furthermore, the effects of ambient gases on the band structure and on the loss function have been probed.

A methodology for calculating transport emissions in cities with limited traffic data: Case study of diesel particulates and black carbon emissions in Murmansk.

This paper presents a methodology for calculating exhaust emissions from on-road transport in cities with low-quality traffic data and outdated vehicle registries. The methodology consists of data collection approaches and emission calculation methods. For data collection, the paper suggests using video survey and parking lot survey methods developed for the International Vehicular Emissions model. Additional sources of information include data from the largest transportation companies, vehicle inspection stations, and official vehicle registries. The paper suggests using the European Computer Programme to Calculate Emissions from Road Transport (COPERT) 4 model to calculate emissions, especially in countries that implemented European emissions standards. If available, the local emission factors should be used instead of the default COPERT emission factors. The paper also suggests additional steps in the methodology to calculate emissions only from diesel vehicles. We applied this methodology to calculate black carbon emissions from diesel on-road vehicles in Murmansk, Russia. The results from Murmansk show that diesel vehicles emitted 11.7 tons of black carbon in 2014. The main factors determining the level of emissions are the structure of the vehicle fleet and the level of vehicle emission controls. Vehicles without controls emit about 55% of black carbon emissions.

[Facial pain].

Diagnosis and treatment of facial pain is a problem for physicians of different specialties (neurologists, dentists, surgeons, oculists, otolaryngologists and psychiatrists). A classification of this pathology is far from ideal and an interdisciplinary comprehensive approach is needed. Current approaches to etiotropic, symptomatic and pathogenetic treatment of patients with most frequent variants of orofacial pain are presented.

[Polyneuropathy in elderly patients].

In this article, the authors consider the characteristics of pathogenesis and clinical picture of peripheral nervous system lesions in elderly patients. Current approaches to pathogenetic and symptomatic treatment of polyneuropathy in elderly patients are analyzed. The authors suggest complex treatment approaches using antiepileptic drugs, group B vitamins, alpha-lipoic acid.

The nature of the Fe-graphene interface at the nanometer level.

The emerging fields of graphene-based magnetic and spintronic devices require a deep understanding of the interface between graphene and ferromagnetic metals. This paper reports a detailed investigation at the nanometer level of the Fe-graphene interface carried out by angle-resolved photoemission, high-resolution photoemission from core levels, near edge X-ray absorption fine structure, scanning tunnelling microscopy and spin polarized density functional theory calculations. Quasi-free-standing graphene was grown on Pt(111), and the iron film was either deposited atop or intercalated beneath graphene. Calculations and experimental results show that iron strongly modifies the graphene band structure and lifts its π band spin degeneracy.

Spectromicroscopy of electronic phase separation in KxFe2-ySe2 superconductor.

Structural phase separation in AxFe2-ySe2 system has been studied by different experimental techniques, however, it should be important to know how the electronic uniformity is influenced, on which length scale the electronic phases coexist, and what is their spatial distribution. Here, we have used novel scanning photoelectron microscopy (SPEM) to study the electronic phase separation in KxFe2-ySe2, providing a direct measurement of the topological spatial distribution of the different electronic phases. The SPEM results reveal a peculiar interconnected conducting filamentary phase that is embedded in the insulating texture. The filamentary structure with a particular topological geometry could be important for the high Tc superconductivity in the presence of a phase with a large magnetic moment in AxFe2-ySe2 materials.

[Aging and pain: specific features of neuropathy treatment in the elderly].

The changes in the somatosensory system in aging and peripheral neuropathies are similar. Higher pain sensitivity thresholds in the presence of axonopathy are accompanied by paradoxically decreased pain tolerance associated with neuroplastic changes in the spinal cord and brain. The symptomatic treatment of neuropathic pain syndrome with antidepressants, anticonvulsants, and opioids is related to the lower quality of life in elderly patients and to the high risk of severe side effects. The pathogenetic treatment of polyneuropathies frequently increases the intensity of neuropathic pain at its beginning; however, it can recover the function of an axon and reduce the degree of deficiency states. The paper discusses methods for increasing the safety of treatment for neuropathic pain in elderly patients, a relationship between the pathogenesis of nervous system aging and distal diabetic polyneuropathy, and ways of their correction.

[The detection of activating somatic mutations in gene KRAS using pyrosequencing technique].

The technique to detect all possible variants of mutations in 12, 13 and 15 codons of gene KRAS was developed on the basis of the pyrosequencing technology. The analytical characteristics of the developed technique were identified. The limit of detection for mutations G34T, G35A and G38A detected on the cloned control samples consisted 3%. The limit of blank for various mutations consisted from 0.3% to 4.1%. The system was tested on clinical samples. The 7 different types of mutations were identified and detected in quantitative format. No discrepancy of pyrosequencing data with results of sequencing according Sanger was established.

Nitrogen-doped graphene: efficient growth, structure, and electronic properties.

A novel strategy for efficient growth of nitrogen-doped graphene (N-graphene) on a large scale from s-triazine molecules is presented. The growth process has been unveiled in situ using time-dependent photoemission. It has been established that a postannealing of N-graphene after gold intercalation causes a conversion of the N environment from pyridinic to graphitic, allowing to obtain more than 80% of all embedded nitrogen in graphitic form, which is essential for the electron doping in graphene. A band gap, a doping level of 300 meV, and a charge-carrier concentration of ∼8×10(12) electrons per cm2, induced by 0.4 atom % of graphitic nitrogen, have been detected by angle-resolved photoemission spectroscopy, which offers great promise for implementation of this system in next generation electronic devices.