Local spectroscopic evidence for a nodeless magnetic kagome superconductor CeRu2.

We report muon spin rotation (µSR) experiments on the microscopic properties of superconductivity and magnetism in the kagome superconductor CeRu2withTc≃5 K. From the measurements of the temperature-dependent magnetic penetration depthλ, the superconducting order parameter exhibits nodeless pairing, which fits best to an anisotropics-wave gap symmetry. We further show that theTc/λ-2ratio is comparable to that of unconventional superconductors. Furthermore, the powerful combination of zero-field (ZF)-µSR and high-fieldµSR has been used to uncover magnetic responses across three characteristic temperatures, identified asT1∗≃110 K,T2∗≃65 K, andT3∗≃40 K. Our experiments classify CeRu2as an exceedingly rare nodeless magnetic kagome superconductor.

Pressure induced superconductivity in MnSe.

The rich phenomena in the FeSe and related compounds have attracted great interests as it provides fertile material to gain further insight into the mechanism of high temperature superconductivity. A natural follow-up work was to look into the possibility of superconductivity in MnSe. We demonstrated in this work that high pressure can effectively suppress the complex magnetic characters of MnSe, and induce superconductivity with Tc ~ 5 K at pressure ~12 GPa confirmed by both magnetic and resistive measurements. The highest Tc is ~ 9 K (magnetic result) at ~35 GPa. Our observations suggest the observed superconductivity may closely relate to the pressure-induced structural change. However, the interface between the metallic and insulating boundaries may also play an important role to the pressure induced superconductivity in MnSe.

Large magnetoresistance and quantum oscillations in Sn0.05Pb0.95Te.

We have synthesized high-quality single crystals of SnxPb1-xTe and carried out detailed studies of the magnetotransport properties of one of the samples, Sn0.05Pb0.95Te. Longitudinal magnetoresistance increases almost linearly with increasing applied field (H) and reaches ∼310% atH= 13 T. At higher fields, both longitudinal and Hall resistance show clear Shubnikov de Haas oscillations. The oscillations are smooth and periodic, and there exists only one frequency,fα∼ 57 T. However, an additional frequency,fß∼ 69 T, appears as the angle between the field direction and the normal to the sample surface (θ) is increased. Bothfαandfßexhibitθ-dependence;fαdecreases whereasfßincreases gradually with increasingθ. The presence of two frequencies in Sn0.05Pb0.95Te indicates that there exist two Fermi surface pockets (αandßpockets). We have constructed the Landau-level fan plot and determined the Berry phase (δ) for theαpocket to beδ∼ 0.1. Thisδvalue is very close to the expected value of 0 for a topologically trivial system.

Low-temperature microstructural studies on superconducting CaFe2As2.

Undoped CaFe2As2 (Ca122) can be stabilized in two slightly different non-superconducting tetragonal phases, PI and PII, through thermal treatments. Upon proper annealing, superconductivity with a Tc up to 25 K emerges in the samples with an admixture of PI and PII phases. Systematic low-temperature X-ray diffraction studies were conducted on undoped Ca122 samples annealed at 350 °C over different time periods. In addition to the diffraction peaks associated with the single-phase aggregation of PI and PII, a broad intermediate peak that shifts with annealing time was observed in the superconducting samples only. Our simulation of phase distribution suggests that the extra peak is associated with the admixture of PI and PII on the nanometer scale. High-resolution transmission electron microscopy confirms the existence of these nano-scale phase admixtures in the superconducting samples. These experimental results and simulation analyses lend further support for our conclusion that interfacial inducement is the most reasonable explanation for the emergence of superconductivity in undoped Ca122 single crystals.

Evidence of a 2D Fermi surface due to surface states in a p-type metallic Bi2Te3.

We present a systematic quantum oscillations study on a metallic, p-type Bi2Te3 topological single crystal in magnetic fields up to B = 7 T. The maxima/minima positions of oscillations measured at different tilt angles align to one another when plotted as a function of the normal component of magnetic field, confirming the presence of the 2D Fermi surface. Additionally, the Berry phase, ß = 0.4 ± 0.05 obtained from the Landau level fan plot, is very close to the theoretical value of 0.5 for the Dirac particles, confirming the presence of topological surface states in the Bi2Te3 single crystal. Using the Lifshitz-Kosevich analyses, the Fermi energy is estimated to be [Formula: see text] meV, which is lower than that of other bismuth-based topological systems. The detection of surface states in the Bi2Te3 crystal can be explained by our previous hypothesis of the lower position of the Fermi surface that cuts the 'M'-shaped valence band maxima. As a result, the bulk state frequency is shifted to higher magnetic fields, which allows measurement of the surface states signal at low magnetic fields.

Comprehensive inelastic neutron scattering study of the multiferroic M n 1 - x C o x W O 4 .

Using high-resolution inelastic neutron scattering, we examine the spin dynamics of M n 1 - x C o x W O 4 in the collinear AF1, the a c - b spiral AF2, and the a c cycloidal AF5 phases. The spin wave excitations are well described by a Heisenberg model with competing long-range exchange interactions ( J i up to 12th nearest neighbors) and the single-ion anisotropy K induced by the spin-orbit interaction. While the exchange constants are relatively unchanged, the dominant effect of doping is to change the single-ion anisotropy from easy axis ( K > 0 ) in the collinear AF1 phase to easy plane ( K < 0 ) in the two multiferroic phases.

Estimation of Right-Lobe Graft Weight From Computed Tomographic Volumetry for Living Donor Liver Transplantation.

BACKGROUND: The objective of the study was to establish a right-lobe graft weight (GW) estimation formula for living donor liver transplantation (LDLT) from right-lobe graft volume without veins (GVw/o_veins), including portal vein and hepatic vein measured by computed tomographic (CT) volumetry, and to compare its estimation accuracy with those of existing formulas. Right-lobe GW estimation formulas established with the use of graft volume with veins (GVw_veins) sacrifice accuracy because GW measured intra-operatively excludes the weight of blood in the veins. Right-lobe GW estimation formulas have been established with the use of right-lobe GVw/o_veins, but a more accurate formula must be developed. METHODS: The present study developed right-lobe GW estimation formulas based on GVw/o_veins as well as GVw_veins, using 40 cases of Korean donors: GW = 29.1 + 0.943 × GVw/o_veins (adjusted R2 = 0.94) and GW = 74.7 + 0.773 × GVw_veins (adjusted R2 = 0.87). The proposed GW estimation formulas were compared with existing GVw_veins- and GVw/o_veins-based models, using 43 cases additionally obtained from two medical centers for cross-validation. RESULTS: The GVw/o_veins-based formula developed in the present study was most preferred (absolute error = 21.5 ± 16.5 g and percentage of absolute error = 3.0 ± 2.3%). CONCLUSIONS: The GVw/o_veins-based formula is preferred to the GVw_veins-based formula in GW estimation. Accurate CT volumetry and alignment between planned and actual surgical cutting lines are crucial in the establishment of a better GW estimation formula.

Pancreas Transplantation After Liver Transplantation: A Case Report.

Our aim was to describe the clinical indications, surgical technique, and clinical outcomes of a pancreas transplantation, performed 4 years after liver transplantation, as treatment for new-onset, uncontrolled diabetes mellitus in a 53-year-old man. Liver transplantation was performed for end-stage liver disease secondary to hepatitis B virus infection and hepatocellular carcinoma. The patient had no history of diabetes prior to the liver transplantation. The decision to proceed with a pancreas transplantation was made when the patient's blood sugar levels could not be normalized despite insulin doses >100 IU/d. A modified cadaveric transplantation technique was used, with the recipient's inferior vena cava dissected for anastomosis with the portal vein of the graft, using a diamond-shaped patch procedure. Moreover, the right common iliac artery was anastomosed with a Y-graft in the pancreas graft, and the duodenum remnant of the graft was anastomosed to the recipient's duodenum using a side-to-side procedure. The 6-month postoperative follow-up included repeated endoscopic biopsy of the graft duodenum, with no evidence of thrombosis or rejection of the graft, with glucose level within normal limits without requirement for diabetic drugs. To our knowledge, this is the first reported case of pancreas transplantation after liver transplantation.

Evaluation of nasal patency by visual analogue scale/nasal obstruction symptom evaluation questionnaires and anterior active rhinomanometry after septoplasty: a retrospective one-year follow-up cohort study.

OBJECTIVE: To assess the efficacy of septoplasty and the correlation between the subjective evaluations of a visual analogue scale (VAS) and the Nasal Obstruction Symptom Evaluation (NOSE) questionnaire and active anterior rhinomanometry of the nasal airway after septoplasty. DESIGN: A retrospective, individual cohort study. SETTING: Ear, Nose and Throat Department, Taipei City Hospital, Taipei, Taiwan. PARTICIPANTS: Fifty patients with chronic nasal obstruction were enrolled in the study. All 50 patients underwent septoplasty because of nasal septal deviation. Another 28 patients without nasal symptoms served as controls. MAIN OUTCOME MEASURES: VAS, NOSE and active anterior rhinomanometry were used to measure the sensation of nasal obstruction. All measurements were performed in both groups preoperatively and then repeated on three postoperative visits (3, 6 and 12 months). RESULTS: The mean VAS score, NOSE score and the nasal resistance in the narrow side of the nose in the study group showed reduced symptoms at 3, 6 and 12 months postoperatively compared with the respective preoperative measurements (P < 0.001, all). The VAS and NOSE scores did not significantly correlate with total nasal resistance preoperatively or postoperatively. The VAS and nasal resistance in the obstructed nasal cavity correlated significantly preoperatively (P < 0.05), but not postoperatively. CONCLUSIONS: The subjective and objective symptoms of nasal obstruction had improved 1 year after septoplasty. A significant correlation between VAS scores and nasal resistance in the narrow side of the nose was found before surgery. The subjective and objective measurements of nasal obstruction lacked significant correlation postoperatively.

Development and Applicability of the A-P 200 Criteria for Liver Transplantation for Hepatocellular Carcinoma.

BACKGROUND: The Milan criteria are widely accepted for indicating liver transplantation in patients with hepatocellular carcinoma (HCC). However, a 7% to 20% possibility of HCC recurrence remains, even among patients who fulfill the Milan criteria. METHODS: We retrospectively reviewed 88 patients with HCC who underwent liver transplantation at Pusan National University Yangsan Hospital between May 2010 and December 2014. The risk factors for HCC recurrence were analyzed, and the overall survival and disease-free survival rates were calculated based on each risk factor. RESULTS: Seventeen patients (19.3%) experienced HCC recurrence. Multivariate analyses revealed that the independent risk factors for HCC recurrence were protein induced by vitamin K absence or antagonist II (PIVKA-II) levels of >200 mAU/mL, levels of >200 for alpha-fetoprotein (ng/mL) or PIVKA-II (mAU/mL), and microvascular invasion. Therefore, we defined the A-P 200 criteria as simultaneously exhibiting alpha-fetoprotein levels of ≤200 ng/mL and PIVKA-II levels of ≤200 mAU/mL. The 3-year overall survival rates among patients who fulfilled or exceeded the A-P 200 criteria were 89.2% and 80.0%, respectively (P = .79). The 3-year disease-free survival rates among patients who fulfilled or exceeded the A-P 200 criteria were 89.9% and 43.1%, respectively (P < .001). We also applied the A-P 200 criteria to patient data from another major center and observed similar results. CONCLUSION: These findings confirm that the A-P 200 criteria can be used to predict recurrence after liver transplantation among patients with HCC.

Inferior Vena Cava-Duodenal Drainage in Pancreas Alone Transplantation for Chronic Pancreatitis: A Case Report.

Enteric drainage has been the main trend in solitary pancreas transplantation. Compared with bladder drainage, it does not cause metabolic or urologic complications, but there is no way to perform immunologic monitoring, except by graft pancreas biopsy. Additionally, although portal drainage of the graft vein is considered physiological drainage, it has more of a risk for surgical complications. To overcome these disadvantages, we successfully performed inferior vena cava (IVC)-duodenal drainage in pancreas alone transplantation. A 44-year-old man underwent pancreas alone transplantation. He had insulin-dependent diabetes because of chronic pancreatitis, thus he had taken a pancreatic enzyme. After right-sided medial visceral rotation, the IVC was dissected for anastomosis with a graft portal vein. The right common iliac artery was anastomosed with a Y-graft in the pancreas graft. The graft duodenum was anastomosed with recipient duodenum using the side-to-side manner. Postoperatively, he underwent protocol biopsies of the graft duodenum through endoscopy two times. There was no evidence of graft thrombosis or rejection. He had a normal glucose level without any diabetic drugs, and he required no pancreatic enzyme for digestion. The IVC-duodenum drainage procedure was a feasible method for preventing thrombosis and providing an opportunity for direct graft monitoring through endoscopy.

Beneficial Effect of Extracorporeal Membrane Oxygenation on Organ Perfusion During Management of the Unstable Brain-dead Donor: A Case Series.

It is well known that the quality of organs retrieved from brain-dead donors (DBDs) is better than those retrieved from circulatory death donors. However, in situations of organ retrieval from marginal DBDs, who are unstable despite intensive care, transplantation outcomes are not good. Organ ischemia is the most important determining factor in decreased organ quality in circulatory death donors and in some DBDs. Extracorporeal membrane oxygenation (ECMO) for management of DBDs can be an emergency countermeasure. The purpose of this report is to relay our experience with four cases of ECMO for DBD management. In all four cases, the donors were unstable and showed clear signs of ischemia despite intensive care, including ventilator use and administration of inotropic agents. Two donors had acute respiratory distress syndrome, and two exhibited dysfunctional oxygen delivery. ECMO was used to improve organ perfusion. ECMO resulted in an increased partial pressure of arterial oxygen increased and decreased lactic acid levels. Vital signs were stabilized, especially in the donors who were bleeding. The organ was successfully retrieved from each donor. Two livers (one of them was split), eight kidneys, and one pancreas were retrieved from four DBDs. All other organs were transplanted successfully, and there were no cases of primary nonfunction or delayed graft function. The ECMO machine is the most powerful supportive device for management of unstable DBDs. The use of ECMO in unstable DBDs can be beneficial in expanding the donor pool as well as improving the quality of retrieved organs.

Irreversible Graft Failure Requiring 3 Repeated Liver Transplantations Combined With a 2-Stage Liver Transplantation: A Case Report.

INTRODUCTION: Although repeated liver transplantation (RLT) for irreversible graft failure is relatively rare, RLT is the only life-saving option available for a patient with failure of a previous liver transplant (LT). In cases in which failure of a previous LT is combined with TLS and exsanguination, waiting for organ allocation is not feasible and 2-stage liver transplantation (TSLT) is required. The aim of our case report was to describe the clinical management, including the criteria informing clinical decisions, for a patient who required 3 RLTs combined with TSLT. CASE: A 55-year-old man was admitted with liver cirrhosis associated with hepatitis B and multiple hepatocellular carcinomas. LT was performed using an emergent deceased donor graft of marginal quality. The graft was unsuccessful, with the patient showing hemodynamic deterioration and primary nonfunction of the graft. A total hepatectomy, with temporary portocaval shunt, was performed, with a second transplantation performed 3 days later. The second graft was from a 71-year-old, non-heart-beating donor, which resulted in a second episode of primary nonfunction. A third transplantation was performed 4 days later. The patient progressively recovered with extensive rehabilitation. CONCLUSION: We report the successful outcome for a patient requiring 3 RLTs, with TSLT used as a bridge between transplants to reduce the duration of the anhepatic state. In selected cases, the combination of RLT and TSLT can provide a chance of survival from life-threatening liver failure.

Complete Regression of Recurrent Advanced Hepatocellular Carcinoma After Liver Transplantation in Response to Sorafenib Treatment: A Case Report.

Liver transplantation is a potentially curative treatment for hepatocellular carcinoma. However, patients with recurrent hepatocellular carcinoma after liver transplantation have few treatment options and local treatment may not be feasible. Sorafenib, an orally active multikinase inhibitor approved for the treatment of advanced hepatocellular carcinoma, significantly improves progression-free and overall survival. However, only a few studies have evaluated the efficacy of sorafenib in patients with recurrent hepatocellular carcinoma following liver transplantation. Here, we report a case of a patient with recurrent advanced hepatocellular carcinoma after living donor liver transplantation who achieved complete remission in response to sorafenib treatment. The patient has survived for more than 4 years post-transplantation.

Formation of Collateral Veins in a Graft Pancreas After a Simultaneous Pancreas and Kidney Transplantation: A Case Report.

A graft vein thrombosis is the main cause of early graft failure after pancreas transplantation. We report a case of formation of collateral veins in a graft pancreas after transplant. A 30-year-old woman underwent simultaneous pancreas and kidney transplantation. She was discharged 16 days after the operation with good pancreas and kidney function. A total occlusion of the portal vein was discovered on computed tomography (CT) performed at an outpatient clinic. She had no symptoms or signs of hyperglycemia. Venography was attempted for vein thrombectomy but failed. After 2 weeks of heparinization therapy, the edema disappeared and perfusion of the graft pancreas improved. However, the thrombotic occlusion was not resolved on CT. Arteriography of the Y-graft revealed collateral veins. She was discharged with warfarin. She is currently doing well without any symptoms or signs. This is the first reported case of collateral vein formation in a grafted pancreas after pancreas transplantation.

Observation of universal strong orbital-dependent correlation effects in iron chalcogenides.

Establishing the appropriate theoretical framework for unconventional superconductivity in the iron-based materials requires correct understanding of both the electron correlation strength and the role of Fermi surfaces. This fundamental issue becomes especially relevant with the discovery of the iron chalcogenide superconductors. Here, we use angle-resolved photoemission spectroscopy to measure three representative iron chalcogenides, FeTe0.56Se0.44, monolayer FeSe grown on SrTiO3 and K0.76Fe1.72Se2. We show that these superconductors are all strongly correlated, with an orbital-selective strong renormalization in the dxy bands despite having drastically different Fermi surface topologies. Furthermore, raising temperature brings all three compounds from a metallic state to a phase where the dxy orbital loses all spectral weight while other orbitals remain itinerant. These observations establish that iron chalcogenides display universal orbital-selective strong correlations that are insensitive to the Fermi surface topology, and are close to an orbital-selective Mott phase, hence placing strong constraints for theoretical understanding of iron-based superconductors.

Magnetic and structural relationship of RFe2Si2 and R(Fe(1-x)M(x))2Si2(x = 0-1) systems (R = La, Y and Lu, M = Ni, Mn and Cu).

Due to the similarity between AFe(2)As(2) (A = Ba, Sr) and RFe(2)Si(2) (R = La, Y and Lu), the RFe(2)Si(2) system has been proposed as a potential candidate for a new high TC superconducting family containing Fe-Si (instead of Fe-As) layers as a structural unit. Various R (Fe(1-x)M(x))2 Si(2) (M = Ni and Cu) materials were synthesized and measured for their magnetic properties. None of these materials is superconducting down to 1.8 K. A pronounced peak at 232 K was observed in the magnetization curve of YFe(2)Si(2). (57)Fe Mössbauer studies confirm the absence of any long-range magnetic ordering below 232 K. Similar peaks at various temperatures also appear in R (Fe(1-x)M(x))2 Si2 samples. For Y (Fe(1-x)Mn(x))2 Si(2) the peak position is dramatically affected by the magnetic Mn dopants. Four independent factors affect the peak position and shift it to lower temperatures: (i) the lattice parameters, (ii) the concentration of x (iii) the applied magnetic field and (iv) the magnetic nature of M. It is proposed that the magnetic peaks observed in RFe(2)Si(2) and in R (Fe(1-x)M(x))2 Si(2) represent a new nearly ferromagnetic Fermi liquid system, its nature is yet to be determined.

Neurocognitive dysfunction and grey matter density deficit in children with obstructive sleep apnoea.

BACKGROUND: Cerebral structural changes related to obstructive sleep apnoea (OSA) have been reported in adult OSA patients; however, similar data and their associations with neurocognitive dysfunction are scarce in childhood OSA. OBJECTIVE: To compare neurocognitive function, regional grey matter density and cerebral volume in children with and without OSA. METHODS: Fifty OSA cases and 27 normal controls underwent a panel of neurocognitive tests. High resolution 3-dimensional magnetic resonance images of the brain were obtained from 23 OSA cases and 15 gender and age matched controls. Total cerebral volume and regional grey matter density were analyzed using voxel-based morphometry technique and compared between the two groups. Individuals with an obstructive apnoea hypopnoea index (OAHI) > 5 were defined as having moderate-to-severe OSA. RESULTS: Children with OSA showed significantly reduced attention and visual-fine motor coordination scores compared with controls. Grey matter volume deficit was observed in prefrontal and temporal regions of cases with moderate-to-severe OSA only. Significant negative correlations were found between the visual-fine motor coordination score and the ratio of grey matter volume over total brain volume. CONCLUSION: Children with OSA had impaired attention and visual-fine motor coordination. Regional grey matter reduction was evident in children with more severe OSA.

Observation of temperature-induced crossover to an orbital-selective Mott phase in A(x)Fe(2-y)Se2 (A=K, Rb) superconductors.

Using angle-resolved photoemission spectroscopy, we observe the low-temperature state of the A(x)Fe(2-y)Se(2) (A=K, Rb) superconductors to exhibit an orbital-dependent renormalization of the bands near the Fermi level-the d(xy) bands heavily renormalized compared to the d(xz)/d(yz) bands. Upon raising the temperature to above 150 K, the system evolves into a state in which the d(xy) bands have depleted spectral weight while the d(xz)/d(yz) bands remain metallic. Combined with theoretical calculations, our observations can be consistently understood as a temperature-induced crossover from a metallic state at low temperatures to an orbital-selective Mott phase at high temperatures. Moreover, the fact that the superconducting state of A(x)Fe(2-y)Se(2) is near the boundary of such an orbital-selective Mott phase constrains the system to have sufficiently strong on-site Coulomb interactions and Hund's coupling, highlighting the nontrivial role of electron correlation in this family of iron-based superconductors.