Topological superconductors are predicted to host exotic Majorana states that obey non-Abelian statistics and can be used to implement a topological quantum computer. Most of the proposed topological ...superconductors are realized in difficult-to-fabricate heterostructures at very low temperatures. By using high-resolution spin-resolved and angle-resolved photoelectron spectroscopy, we find that the iron-based superconductor FeTe
Se
(
= 0.45; superconducting transition temperature
= 14.5 kelvin) hosts Dirac-cone-type spin-helical surface states at the Fermi level; the surface states exhibit an s-wave superconducting gap below
Our study shows that the surface states of FeTe
Se
are topologically superconducting, providing a simple and possibly high-temperature platform for realizing Majorana states.
The structure of the superconducting gap in unconventional superconductors holds a key to understand the momentum-dependent pairing interactions. In superconducting FeSe, there have been ...controversial results reporting nodal and nodeless gap structures, raising a fundamental issue of pairing mechanisms of iron-based superconductivity. Here, by utilizing polarization-dependent laser-excited angle-resolved photoemission spectroscopy, we report a detailed momentum dependence of the gap in single- and multi-domain regions of orthorhombic FeSe crystals. We confirm that the superconducting gap has a twofold in-plane anisotropy, associated with the nematicity due to orbital ordering. In twinned regions, we clearly find finite gap minima near the vertices of the major axis of the elliptical zone-centered Fermi surface, indicating a nodeless state. In contrast, the single-domain gap drops steeply to zero in a narrow angle range, evidencing for nascent nodes. Such unusual node lifting in multi-domain regions can be explained by the nematicity-induced time-reversal symmetry breaking near the twin boundaries.
The crossover from BCS superconductivity to BEC superconductivity is controlled by electronic nematicity in FeSe
1 −
x
S
x
.
The crossover from the superconductivity of the Bardeen-Cooper-Schrieffer ...(BCS) regime to the Bose-Einstein condensation (BEC) regime holds a key to understanding the nature of pairing and condensation of fermions. It has been mainly studied in ultracold atoms, but in solid systems, fundamentally previously unknown insights may be obtained because multiple energy bands and coexisting electronic orders strongly affect spin and orbital degrees of freedom. Here, we provide evidence for the BCS-BEC crossover in iron-based superconductors FeSe
1 −
x
S
x
from laser-excited angle-resolved photoemission spectroscopy. The system enters the BEC regime with
x
= 0.21, where the nematic state that breaks the orbital degeneracy is fully suppressed. The substitution dependence is opposite to the expectation for single-band superconductors, which calls for a new mechanism of BCS-BEC crossover in this system.
Significance Pulmonary arterial hypertension (PAH) is a serious disease characterized by vascular remodeling in pulmonary arteries. Although an elevated IL-6 serum level correlates with poor ...prognosis of PAH patients, it is unclear how IL-6 promotes PAH. Here we identified IL-21 as a downstream target of IL-6 signaling in PAH. In mice with hypoxia-induced pulmonary hypertension (HPH), Th17 cells and M2 macrophages accumulate in the lungs after hypoxia exposure. IL-21 primarily derived from Th17 cells promotes M2 macrophage polarization. Consistently, IL-21 receptor-deficient mice show resistance to HPH with no accumulation of M2 macrophages in the lungs. IL-21 and M2 macrophage markers were upregulated in the lungs of patients with end-stage idiopathic PAH. These findings suggest promising therapeutic strategies for PAH targeting IL-6/IL-21–signaling axis.
IL-6 is a multifunctional proinflammatory cytokine that is elevated in the serum of patients with pulmonary arterial hypertension (PAH) and can predict the survival of patients with idiopathic PAH (IPAH). Previous animal experiments and clinical human studies indicate that IL-6 is important in PAH; however, the molecular mechanisms of IL-6–mediated pathogenesis of PAH have been elusive. Here we identified IL-21 as a downstream target of IL-6 signaling in PAH. First, we found that IL-6 blockade by the monoclonal anti-IL-6 receptor antibody, MR16-1, ameliorated hypoxia-induced pulmonary hypertension (HPH) and prevented the hypoxia-induced accumulation of Th17 cells and M2 macrophages in the lungs. Consistently, the expression levels of IL-17 and IL-21 genes, one of the signature genes for Th17 cells, were significantly up-regulated after hypoxia exposure in the lungs of mice treated with control antibody but not in the lungs of mice treated with MR16-1. Although IL-17 blockade with an anti–IL-17A neutralizing antibody had no effect on HPH, IL-21 receptor-deficient mice were resistant to HPH and exhibited no significant accumulation of M2 macrophages in the lungs. In accordance with these findings, IL-21 promoted the polarization of primary alveolar macrophages toward the M2 phenotype. Of note, significantly enhanced expressions of IL-21 and M2 macrophage markers were detected in the lungs of IPAH patients who underwent lung transplantation. Collectively, these findings suggest that IL-21 promotes PAH in association with M2 macrophage polarization, downstream of IL-6-signaling. The IL-6/IL-21–signaling axis may be a potential target for treating PAH.
Intraosseous lipoma remains a poorly-characterized tumor. In paticular, the natural course of intracalcaneus lipoma after conservative treatment and the appropriate surgical modalities are still ...quite controversial.
We reviewed six symptomatic patients who underwent curettage of intracalcaneus lipoma followed by grafting of α- or β-tricalcium phosphate. An endoscopically-assisted technique was used in one case.
All patients experienced heel pain that increased acutely after minor trauma. Heel pain disappeared soon after surgery in five cases. One patient experienced short-term mild chronic regional pain syndrome for short term. β-tricalcium phosphate was completely resorbed and remodeled after transplantation.
Surgical treatment is indicated for cases that are: i) symptomatic, ii) larger than the critical size, and iii) prone to pathological fracture. Curettage of intracalcaneus lipoma involving an endoscopically-assisted technique and filling of the defect with β-tricalcium phosphate is a feasible method and is minimally-invasive for the patient.
Abstract
Hyperparathyroidism, which is increased parathyroid hormone (PTH) levels in the blood, could cause delayed or non-union of bone fractures. But, no study has yet demonstrated the effects of ...excess continuous PTH exposure, such as that seen in hyperparathyroidism, for fracture healing. Continuous human PTH
1–34
(teriparatide) infusion using an osmotic pump was performed for stabilized tibial fractures in eight-week-old male mice to determine the relative bone healing process compared with saline treatment. Radiographs and micro-computed tomography showed delayed but increased calcified callus formation in the continuous PTH
1–34
infusion group compared with the controls. Histology and quantitative histomorphometry confirmed that continuous PTH
1–34
treatment significantly increased the bone callus area at a later time point after fracture, since delayed endochondral ossification occurred. Gene expression analyses showed that PTH
1–34
resulted in sustained
Col2a1
and reduced
Col10a1
expression, consistent with delayed maturation of the cartilage tissue during fracture healing. In contrast, continuous PTH
1–34
infusion stimulated the expression of both
Bglap
and
Acp5
through the healing process, in accordance with bone callus formation and remodeling. Mechanical testing showed that continuously administered PTH
1–34
increased the maximum load on Day 21 compared with control mice. We concluded that continuous PTH
1–34
infusion resulted in a delayed fracture healing process due to delayed callus cell maturation but ultimately increased biomechanical properties.
The objective of this study is to reduce V content of Ni-base dual two-phase intermetallic alloy, with keeping the dual two-phase microstructure and also without sacrificing their mechanical and ...chemical properties. The dual two-phase microstructure was maintained when Cr and Nb instead of V were added to the alloy and their valence electron concentration (e/a) ranges from 8.59 to 8.43. Consequently, the contents of V in the dual two-phase intermetallic alloy were reduced by 8at%, 8at%, and 3at% by Cr substitutions for V-site, both of Ni- and V-sites, and Ni-site, respectively. The density of the modified alloys slightly increased from that of the base alloy. Hardness was higher in the modified alloys than in the base alloy. The flow strength of the modified alloys is much improved from that of the base alloy in a wide range of temperatures. Also, oxidation resistance of the modified alloys was superior to those of the base alloy.
Treatment of refractory Takayasu arteritis (TA) remains an unresolved clinical issue. Patients usually respond to glucocorticoid (GC) therapy, but often relapse on tapering of the GC dose. The aim of ...the present study was to assess the safety and efficacy of the interleukin-6 (IL-6) receptor antibody tocilizumab (TCZ) in patients with TA refractory to conventional therapies including GC. Four patients with TA who had shown GC resistance received TCZ infusions (8 mg/kg) every 4 weeks a total of at least 24 times (range, 24 to 51). Clinical symptoms, the serum levels of acute phase proteins and IL-6, GC dosage necessary to maintain remission, and cross-sectional imaging by enhanced CT and MRI were assessed. All patients achieved good clinical response and rapid normalization of the acute phase proteins such as C-reactive protein and serum amyloid A during the therapy with TCZ. The mean dosage of prednisolone could be reduced from 21.3 mg/day to 1.5 mg/day. Although the serum IL-6 level was transiently elevated in all patients after several TCZ infusions, it gradually recovered to the initial level. Along with the decrease of serum IL-6, two patients exhibited signifi cant reduction in thickened arterial lesions. No drug-related adverse effects were noted. In this small group of patients with refractory TA, TCZ therapy was effective and well-tolerated. Further larger studies should be conducted to confirm this finding.
12-Oxo-phytodienoic acid (OPDA) is an important metabolite on the octadecanoid pathway of plants. This study shows an efficient in vitro synthesis of (+)-cis-OPDA by using a flaxseed extract and an ...allene oxide cyclase. The OPDA yield of the reaction in this study was almost 7-fold higher than that in the conventional reaction with the flaxseed extract.
A topological insulator film coupled to a simple isotropic s-wave superconductor substrate can foster helical pairing of the Dirac fermions associated with the topological surface states. ...Experimental realization of such a system is exceedingly difficult, however using a novel "flip-chip" technique, we have prepared single-crystalline Bi
Se
films with predetermined thicknesses in terms of quintuple layers (QLs) on top of Nb substrates fresh from in situ cleavage. Our angle-resolved photoemission spectroscopy (ARPES) measurements of the film surface disclose superconducting gaps and coherence peaks of similar magnitude for both the topological surface states and bulk states. The ARPES spectral map as a function of temperature and film thickness up to 10 QLs reveals key characteristics relevant to the mechanism of coupling between the topological surface states and the superconducting Nb substrate; the effective coupling length is found to be much larger than the decay length of the topological surface states.
PDF
