Electronic stripe patterns near the fermi level of tetragonal Fe(Se,S).

FeSe1-xSx remains one of the most enigmatic systems of Fe-based superconductors. While much is known about the orthorhombic parent compound, FeSe, the tetragonal samples, FeSe1-xSx with x > 0.17, remain relatively unexplored. Here, we provide an in-depth investigation of the electronic states of tetragonal FeSe0.81S0.19, using scanning tunneling microscopy and spectroscopy (STM/S) measurements, supported by angle-resolved photoemission spectroscopy (ARPES) and theoretical modeling. We analyze modulations of the local density of states (LDOS) near and away from Fe vacancy defects separately and identify quasiparticle interference (QPI) signals originating from multiple regions of the Brillouin zone, including the bands at the zone corners. We also observe that QPI signals coexist with a much stronger LDOS modulation for states near the Fermi level whose period is independent of energy. Our measurements further reveal that this strong pattern appears in the STS measurements as short range stripe patterns that are locally two-fold symmetric. Since these stripe patterns coexist with four-fold symmetric QPI around Fe-vacancies, the origin of their local two-fold symmetry must be distinct from that of nematic states in orthorhombic samples. We explore several aspects related to the stripes, such as the role of S and Fe-vacancy defects, and whether they can be explained by QPI. We consider the possibility that the observed stripe patterns may represent incipient charge order correlations, similar to those observed in the cuprates.

Mn-induced Fermi-surface reconstruction in the SmFeAsO parent compound.

The electronic ground state of iron-based materials is unusually sensitive to electronic correlations. Among others, its delicate balance is profoundly affected by the insertion of magnetic impurities in the FeAs layers. Here, we address the effects of Fe-to-Mn substitution in the non-superconducting Sm-1111 pnictide parent compound via a comparative study of SmFe[Formula: see text]Mn[Formula: see text]AsO samples with [Formula: see text] 0.05 and 0.10. Magnetization, Hall effect, and muon-spin spectroscopy data provide a coherent picture, indicating a weakening of the commensurate Fe spin-density-wave (SDW) order, as shown by the lowering of the SDW transition temperature [Formula: see text] with increasing Mn content, and the unexpected appearance of another magnetic order, occurring at [Formula: see text] and 20 K for [Formula: see text] and 0.10, respectively. We attribute the new magnetic transition at [Formula: see text], occurring well inside the SDW phase, to a reorganization of the Fermi surface due to Fe-to-Mn substitutions. These give rise to enhanced magnetic fluctuations along the incommensurate wavevector [Formula: see text], further increased by the RKKY interactions among Mn impurities.

Evidence for an Fulde-Ferrell-Larkin-Ovchinnikov State with Segmented Vortices in the BCS-BEC-Crossover Superconductor FeSe.

We present resistivity and thermal-conductivity measurements of superconducting FeSe in intense magnetic fields up to 35 T applied parallel to the ab plane. At low temperatures, the upper critical field µ_{0}H_{c2}^{ab} shows an anomalous upturn, while thermal conductivity exhibits a discontinuous jump at µ_{0}H^{*}≈24 T well below µ_{0}H_{c2}^{ab}, indicating a first-order phase transition in the superconducting state. This demonstrates the emergence of a distinct field-induced superconducting phase. Moreover, the broad resistive transition at high temperatures abruptly becomes sharp upon entering the high-field phase, indicating a dramatic change of the magnetic-flux properties. We attribute the high-field phase to the Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state, where the formation of planar nodes gives rise to a segmentation of the flux-line lattice. We point out that strongly orbital-dependent pairing as well as spin-orbit interactions, the multiband nature, and the extremely small Fermi energy are important for the formation of the FFLO state in FeSe.

Quantum Vortex Core and Missing Pseudogap in the Multiband BCS-BEC Crossover Superconductor FeSe.

FeSe is argued as a superconductor in the Bardeen-Cooper-Schrieffer Bose-Einstein condensation crossover regime where the superconducting gap size and the superconducting transition temperature T_{c} are comparable to the Fermi energy. In this regime, vortex bound states should be well quantized and the preformed pairs above T_{c} may yield a pseudogap in the quasiparticle-excitation spectrum. We performed spectroscopic-imaging scanning tunneling microscopy to search for these features. We found Friedel-like oscillations near the vortex, which manifest the quantized levels, whereas the pseudogap was not detected. These apparently conflicting observations may be related to the multiband nature of FeSe.

Knight Shift and Leading Superconducting Instability from Spin Fluctuations in Sr_{2}RuO_{4}.

Recent nuclear magnetic resonance studies [A. Pustogow et al., Nature 574, 72 (2019)] have challenged the prevalent chiral triplet pairing scenario proposed for Sr_{2}RuO_{4}. To provide guidance from microscopic theory as to which other pair states might be compatible with the new data, we perform a detailed theoretical study of spin fluctuation mediated pairing for this compound. We map out the phase diagram as a function of spin-orbit coupling, interaction parameters, and band structure properties over physically reasonable ranges, comparing when possible with photoemission and inelastic neutron scattering data information. We find that even-parity pseudospin singlet solutions dominate large regions of the phase diagram, but in certain regimes spin-orbit coupling favors a near-nodal odd-parity triplet superconducting state, which is either helical or chiral depending on the proximity of the γ band to the van Hove points. A surprising near degeneracy of the nodal s^{'} and d_{x^{2}-y^{2}} wave solutions leads to the possibility of a near-nodal time-reversal symmetry broken s^{'}+id_{x^{2}-y^{2}} pair state. Predictions for the temperature dependence of the Knight shift for fields in and out of plane are presented for all states.

High-T c superconductivity in undoped ThFeAsN.

Unlike the widely studied ReFeAsO series, the newly discovered iron-based superconductor ThFeAsN exhibits a remarkably high critical temperature of 30 K, without chemical doping or external pressure. Here we investigate in detail its magnetic and superconducting properties via muon-spin rotation/relaxation and nuclear magnetic resonance techniques and show that ThFeAsN exhibits strong magnetic fluctuations, suppressed below ~35 K, but no magnetic order. This contrasts strongly with the ReFeAsO series, where stoichiometric parent materials order antiferromagnetically and superconductivity appears only upon doping. The ThFeAsN case indicates that Fermi-surface modifications due to structural distortions and correlation effects are as important as doping in inducing superconductivity. The direct competition between antiferromagnetism and superconductivity, which in ThFeAsN (as in LiFeAs) occurs at already zero doping, may indicate a significant deviation of the s-wave superconducting gap in this compound from the standard s ± scenario.Exploring the interplay between the superconducting gap and the antiferromagnetic phase in Fe-based superconductors remains an open issue. Here, the authors show that Fermi-surface modifications by means of structural distortions and correlation effects are as important as doping in inducing superconductivity in undoped ThFeAsN.

[New approaches for recovery of erectile function in patients after radical prostatectomy].

Prostate cancer (PCa) is one of the most common maligmancies and causes of death among men. Radical prostatectomy (RP) is optimal and recommended treatment modality for localized prostate cancer. More than half of all men undergoing surgery experience problems with erectile function and existing treatments do not provide a positive effect. Thus, there is a need for new approaches to the restoration of erectile function in patients after RP. One of these is the use of cell technologies, namely the stromal-vascular fraction and autologous platelet-rich plasma. This review examines the results of preclinical and clinical studies investigating the efficacy and safety of these treatment options in erectile dysfunction.

World's First Clinical Case of Gene-Activated Bone Substitute Application.

Treatment of patients with large bone defects is a complex clinical problem. We have initiated the first clinical study of a gene-activated bone substitute composed of the collagen-hydroxyapatite scaffold and plasmid DNA encoding vascular endothelial growth factor. The first patient with two nonunions of previously reconstructed mandible was enrolled into the study. Scar tissues were excised; bone defects (5-14 mm) between the mandibular fragments and nonvascularized rib-bone autograft were filled in with the gene-activated bone substitute. No adverse events were observed during 12 months of follow-up. In 3 months, the average density of newly formed tissues within the implantation zone was 402.21 ± 84.40 and 447.68 ± 106.75 HU in the frontal and distal regions, respectively, which correlated with the density of spongy bone. Complete distal bone defect repair with vestibular and lingual cortical plates formation was observed in 6 and 12 months after surgery; thereby the posterior nonunion was successfully eliminated. However, there was partial resorption of the proximal edge of the autograft entailed to relapse of the anterior nonunion. Thus, the first clinical data on the safety and efficacy of the gene-activated bone substitute were obtained. Given a high complexity of the clinical situation the treatment, results might be considered as promising. NCT02293031.

[Slow Formation and Degradation of γH2AX Foci in Human Skin Fibroblasts Exposed to Low-Dose X-Ray Radiation].

It was shown that the kinetics of changes of γH2AX foci number (marker of DNA double-strand breaks) in human skin fibroblasts after exposure to low doses of X-ray radiation (20, 40 and 80 mGy) differs from that observed after exposure to medium-low doses (160 and 240 mGy). After exposure to 160 and 240 mGy the highest number of γH2AX foci was detected at 30 min after exposure (first experimental point) and further their decrease was observed. At the same time we observed a fast phase of repair (upto 4 h), in which there was a decrease of the foci amount to ~50-60% and a slow phase of repair (from 4 h to 24 h). After 24 h only ~3-5% of the foci amount observed at 30 min after irradiation was left. After exposure to low doses, the foci number did not decrease during 2 h and even 24 h after exposure their amount was ~25% from that observed at maximum points (1 h after irradiation at 40 and 80 mGy and 2 h after irradiation at 20 mGy).

[Prospects for the use of cells possessing myogenic potential in the treatment of skeletal muscle diseases: a review of research. Part 1 - satellite cells].

Musculoskeletal functions disorders may develop as a consequence of injuries and various types of congenital / acquired diseases, among which a special place belongs to muscular dystrophy. The technology with use of cells possessing myogenic potential is considered as one of the most promising approaches to solve the problem of effective restoration of skeletal muscles structure and function. In part I of the article the characteristic features, functions and phenotypic characteristics of satellite cells (SC) are reviewed as key factors of skeletal muscle tissue regeneration. Presented analysis of research results (preclinical and clinical) concerning therapeutic possibilities of technology using SC. In the second part of review will be presented data of the therapeutic use of stem cells of muscle and non-muscle origin for the treatment of skeletal muscles diseases.

Mutual Independence of Critical Temperature and Superfluid Density under Pressure in Optimally Electron-Doped Superconducting LaFeAsO(1-x)F(x).

The superconducting properties of LaFeAsO(1-x)F(x) under conditions of optimal electron doping are investigated upon the application of external pressure up to ∼23 kbar. Measurements of muon-spin spectroscopy and dc magnetometry evidence a clear mutual independence between the critical temperature T(c) and the low-temperature saturation value for the ratio n(s)/m(*) (superfluid density over effective band mass of Cooper pairs). Remarkably, a dramatic increase of ∼30% is reported for n(s)/m(*) at the maximum pressure value while T(c) is substantially unaffected in the whole accessed experimental window. We argue and demonstrate that the explanation for the observed results must take the effect of nonmagnetic impurities on multiband superconductivity into account. In particular, the unique possibility to modify the ratio between intraband and interband scattering rates by acting on structural parameters while keeping the amount of chemical disorder constant is a striking result of our proposed model.

[Characteristics of immune response and inflammatory reaction in atherothrombotic stroke and myocardial infarction]. / Osobennosti immunnogo otveta i vospalitel'noi reaktsii pri aterotromboticheskom insul'te i infarkte miokarda.

AIM: To study characteristics of ischemic tissue damage basing on the assessment of the correlations between markers of immune response, inflammation and apoptosis in patients with myocardial infarction (MI) and atherothrombotic stroke (AS). MATERIAL AND METHODS: Concentrations of matrix metalloproteinase-9 (MMP-9), immune complexes with cryogenic properties, soluble Fas-ligand, tumor necrosis factor alpha, interleukin-10 measured with ELISA as well as the activity of spontaneous apoptosis of mononuclear cells and surface expression of Toll-like receptors-4 and intracellular heat shock proteins measured with flow cytofluorometry were determined in the blood of 93 patients with the first AS and 94 patients with MI without concomitant inflammation in the 1st and 7th day of the disease. RESULTS AND CONCLUSION: Increased levels of the markers of immune response, inflammation, apoptosis and destruction of the extracellular matrix were identified at the beginning of MI and AS. The results provide the evidence that similar mechanisms may be involved in ischemic tissue damage. Multivariate analysis conducterd by of principal component analysis correlation matrix revealed the specificity of the relationships between all of these markers. This is the completely new approach to assessin the role and importance of defined parameters in the acute period of the myocardial ischemia and brain.

[Prospects for the Use of Cells Possessing Myogenic Potential in the Treatment of Skeletal Muscle Diseases: a Review of Research. Part 2--Populations of stem cells of muscle and non-muscle origin].

The paper reviews research results of myogenic potential, specific properties, functions, and phenotypic features of a number of stem cells populations of muscle and non-muscle origin, their ability to participate in the restoration of the physiological homeostasis of skeletal muscle. The results of scientific research allow to predict with high probability the establishment of an effective cell technology to treat degenerative muscle diseases.

Anisotropic softening of magnetic excitations along the nodal direction in superconducting cuprates.

The high-Tc cuprate superconductors are close to antiferromagnetic order. Recent measurements of magnetic excitations have reported an intriguing similarity to the spin waves--magnons--of the antiferromagnetic insulating parent compounds, suggesting that magnons may survive in damped, broadened form throughout the phase diagram. Here we show by resonant inelastic X-ray scattering on Bi(2)Sr(2)CaCu(2)O(8+δ) (Bi-2212) that the analogy with spin waves is only partial. The magnon-like features collapse along the nodal direction in momentum space and exhibit a photon energy dependence markedly different from the Mott-insulating case. These observations can be naturally described by the continuum of charge and spin excitations of correlated electrons. The persistence of damped magnons could favour scenarios for superconductivity built from quasiparticles coupled to spin fluctuations. However, excitation spectra composed of particle-hole excitations suggest that superconductivity emerges from a coherent treatment of electronic spin and charge in the form of quasiparticles with very strong magnetic correlations.

Magnetically driven suppression of nematic order in an iron-based superconductor.

A theory of superconductivity in the iron-based materials requires an understanding of the phase diagram of the normal state. In these compounds, superconductivity emerges when stripe spin density wave (SDW) order is suppressed by doping, pressure or atomic disorder. This magnetic order is often pre-empted by nematic order, whose origin is yet to be resolved. One scenario is that nematic order is driven by orbital ordering of the iron 3d electrons that triggers stripe SDW order. Another is that magnetic interactions produce a spin-nematic phase, which then induces orbital order. Here we report the observation by neutron powder diffraction of an additional fourfold-symmetric phase in Ba1-xNaxFe2As2 close to the suppression of SDW order, which is consistent with the predictions of magnetically driven models of nematic order.

[Experimental model of severe local radiation injuries of the skin after X-rays].

The experimental model of severe local radiation injuries skin under the influence of a relatively soft X-rays on a modified device RAP 100-10 produced by "Diagnostica-M" (Russia) was proposed. The model can be used as pre-clinical studies in small experimental animals in order to improve the treatment of local radiation injuries, especially in the conditions of application of cellular therapy.

[Experience of contemporary treatment of radiation burns in individuals subjected to ionizing radiation].

The article presents new approach to treatment of radiation disorders presenting as indolent ulcers. The approach is based on autologous multipotent mesenchimal stromal cells applied locally and injected around the injuried zone. The ulcers heal due to the fact that the transplanted cells stimulate local regeneration processes, angiogenesis, ceased inflammation and apoptosis. The method is a new medical technology based on vast preclinical studies and could be put into medical practice.

Successful treatment of localised radiation lesions in rats and humans by mesenchymal stem cell transplantation.

Transplantation of mesenchymal stem cells (MSCs), at early and later stages after local exposure of rats to 140 Gy 90Sr/90Y beta radiation, was found to stimulate recovery of damaged skin. The area of local radiation injuries (LRIs) and accelerated healing of radiation ulcers was obtained. Clinical evolution showed the high efficiency of the transplantations of autologous MSCs for the treatment of deep beam ulcers, usually refractive to standard conservative treatment. Analogous to our results in the rats the authors obtained promising results with the application of MSCs for the treatment of severe LRIs in two human patients. Their radiation ulcers showed complete healing after stem cell application. Thus, further developments should determine the best possible conditions for MSC use in LRI treatment.

Effect of Fermi surface nesting on resonant spin excitations in Ba(1-x)K(x)Fe2As2.

We report inelastic neutron scattering measurements of the resonant spin excitations in Ba(1-x)K(x)Fe(2)As(2) over a broad range of electron band filling. The fall in the superconducting transition temperature with hole doping coincides with the magnetic excitations splitting into two incommensurate peaks because of the growing mismatch in the hole and electron Fermi surface volumes, as confirmed by a tight-binding model with s(±)-symmetry pairing. The reduction in Fermi surface nesting is accompanied by a collapse of the resonance binding energy and its spectral weight, caused by the weakening of electron-electron correlations.

[Mesenchymal stem cells transplantation in the treatment of radiation skin lesions].

Transplantation of mesenchymal stem cells, both at early and later stage after local exposure of rats source beta radiation dose, 90Sr/90Y 140 GR, stimulates recovery of damaged skin. Diminution area local radiation injuries and accelerate healing radiation ulcers. Clinically shows the high efficiency of the transplantations autologous mesenchymal stem cells in treatment of deep beam ulcers, intractable standard conservative treatment. Found promising application of mesenchymal stem cells for treatment of severe local radiation injuries and the need to develop the best possible conditions for their use.