Honeycomb oxide heterostructure: a new platform for Kitaev quantum spin liquid

Kitaev quantum spin liquid, massively quantum entangled states, is so scarce in nature that searching for new candidate systems remains a great challenge. Honeycomb heterostructure could be a promising route to realize and utilize such an exotic quantum phase by providing additional controllability of Hamiltonian and device compatibility, respectively. Here, we provide epitaxial honeycomb oxide thin film Na3Co2SbO6, a candidate of Kitaev quantum spin liquid proposed recently. We found a spin glass and antiferromagnetic ground states depending on Na stoichiometry, signifying not only the importance of Na vacancy control but also strong frustration in Na3Co2SbO6. Despite its classical ground state, the field-dependent magnetic susceptibility shows remarkable scaling collapse with a single critical exponent, which can be interpreted as evidence of quantum criticality. Its electronic ground state and derived spin Hamiltonian from spectroscopies are consistent with the predicted Kitaev model. Our work provides a unique route to the realization and utilization of Kitaev quantum spin liquid

Freuden ondorioak: psikoanalisia eta egungo zientziaren diskurtsoa

Hydrogen permeation membranes are a key element in improving the energy conversion efficiency and decreasing the greenhouse gas emissions from energy generation. The scientific community faces the challenge of identifying and optimizing stable and effective ceramic materials for H2 separation membranes at elevated temperature (400–800 °C) for industrial separations and intensified catalytic reactors. As such, composite materials with nominal composition BaCe0.8Eu0.2O3-δ:Ce0.8Y0.2O2-δ revealed unprecedented H2 permeation levels of 0.4 to 0.61 mL·min−1·cm−2 at 700 °C measured on 500 μm-thick-specimen. A detailed structural and phase study revealed single phase perovskite and fluorite starting materials synthesized via the conventional ceramic route. Strong tendency of Eu to migrate from the perovskite to the fluorite phase was observed at sintering temperature, leading to significant Eu depletion of the proton conducing BaCe0.8Eu0.2O3-δ phase. Composite microstructure was examined prior and after a variety of functional tests, including electrical conductivity, H2-permeation and stability in CO2 containing atmospheres at elevated temperatures, revealing stable material without morphological and structural changes, with segregation-free interfaces and no further diffusive effects between the constituting phases. In this context, dual phase material based on BaCe0.8Eu0.2O3-δ:Ce0.8Y0.2O2-δ represents a very promising candidate for H2 separating membrane in energy- and environmentally-related applications

Expression of CD99 in Pleomorphic Carcinomas of the Lung

Pleomorphic carcinoma of the lung (PCL) is characterized by a mixture of sarcomatoid and carcinoma components, and a poor prognosis. However, no immunophenotype of tumor markers has been characterized in PCL. To charaterize the immunophenotype for CD99 in PCL, we performed an immunohistochemical evaluation of PCLs for thyroid transcription factor-1 (TTF-1), cytokeratin (CK) 7 and 20, and for CD99. CD99 was found to be expressed in both carcinomatous (47%) and sarcomatous components such as spindle cells (92%) and giant cells (57%). In the case of spindle cells, CK7 was expressed in 6 cases (46%) and TTF-1 in 2 cases (15%), whereas for giant cells CK7 was expressed in 8 cases (57%) and TTF-1 in one case (7%). However, CK20 was not expressed in either the carcinomatous or sarcomatous components in any case. Thus, CD99 was found to be widely expressed in both sarcomatous and carcinoma component in PCL. A clinicopathological analysis showed no direct correlation between the expression of CD99 and the clinical indices (stage, survival rate, invasion) of PCL

Emerging Need for Vaccination against Hepatitis A Virus in Patients with Chronic Liver Disease in Korea

Vaccination against hepatitis A virus (HAV) is recommended for patients with chronic liver disease (CLD), but this has been deemed unnecessary in Korea since the immunity against HAV was almost universal in adults. However, this practice has never been reevaluated with respect to the changing incidence of adult acute hepatitis A. We retrospectively reviewed the medical records of 278 patients with acute hepatitis A diagnosed from January 1995 to November 2005 and prospectively tested 419 consecutive CLD patients from July to December 2005 for the presence of IgG anti-HAV. The number of patients with acute hepatitis A has markedly increased recently, and the proportion of adult patients older than 30 yr has been growing from 15.2% during 1995-1999, to 28.4% during 2000-2005 (p=0.019). Among 419 CLD patients, the seroprevalences of IgG anti-HAV were 23.1% for those between 26 and 30 yr, 64% between 31 and 35 yr, and 85.0% between 36 and 40 yr. These data demonstrate that immunity against HAV is no more universal in adult and substantial proportion of adult CLD patients are now at risk of HAV infection in Korea. Therefore, further study on seeking proper strategy of active immunization against HAV is warranted in these populations

Pilot KaVA monitoring on the M87 jet: confirming the inner jet structure and superluminal motions at sub-pc scales

We report the initial results of our high-cadence monitoring program on the radio jet in the active galaxy M87, obtained by the KVN and VERA Array (KaVA) at 22 GHz. This is a pilot study that preceded a larger KaVA-M87 monitoring program, which is currently ongoing. The pilot monitoring was mostly performed every two to three weeks from December 2013 to June 2014, at a recording rate of 1 Gbps, obtaining the data for a total of 10 epochs. We successfully obtained a sequence of good quality radio maps that revealed the rich structure of this jet from <~1 mas to 20 mas, corresponding to physical scales (projected) of ~0.1-2 pc (or ~140-2800 Schwarzschild radii). We detected superluminal motions at these scales, together with a trend of gradual acceleration. The first evidence for such fast motions and acceleration near the jet base were obtained from recent VLBA studies at 43 GHz, and the fact that very similar kinematics are seen at a different frequency and time with a different instrument suggests these properties are fundamental characteristics of this jet. This pilot program demonstrates that KaVA is a powerful VLBI array for studying the detailed structural evolution of the M87 jet and also other relativistic jets.Comment: 10 pages, 9 figures, accepted for publication in PAS

Obesity and hepatocellular carcinoma in patients receiving entecavir for chronic hepatitis B

Background/Aims This study aimed to clarify the effect of obesity on the development of hepatocellular carcinoma (HCC) in chronic hepatitis B (CHB) patients receiving antiviral treatment. Methods This study applied a retrospective analysis to a historical cohort in Bundang Jesaeng Hospital. In total, 102 CHB patients were treated with entecavir as an initial treatment for CHB and checked for obesity using a body composition analyzer. Hepatic steatosis was measured semiquantitatively using Hamaguchi’s scoring system in ultrasonography. Risk factors for the development of HCC were analyzed, including obesity-related factors (body mass index [BMI], waist circumference [WC], waist-to-hip ratio [WHR], visceral fat area [VFA], and hepatic steatosis). Results The median follow-up duration of the patients was 45.2 months (interquartile range: 36.0-58.3 months). The cumulative incidence rates of HCC at 1 year, 3 years, and 5 years were 0%, 5.3%, and 9.0%, respectively. Univariable analysis revealed that the risk factors for HCC development were a platelet count of <120,000 /mm2 (hazard ratio [HR]=5.21, P=0.031), HBeAg negativity (HR=5.61, P=0.039), and liver cirrhosis (HR=10.26, P=0.031). Multivariable analysis showed that the significant risk factor for HCC development was liver cirrhosis (HR=9.07, P=0.042). However, none of the obesity-related risk factors were significantly associated with HCC: BMI ≥25 kg/m2 (HR=0.90, P=0.894), WC ≥90 cm (HR=1.10, P=0.912), WHR ≥0.9 (HR=1.94, P=0.386), VFA ≥100 cm2 (HR=1.69, P=0.495), and hepatic steatosis (HR=0.57, P=0.602). Conclusion HCC development is associated with liver cirrhosis but not obesity-related factors in CHB patients receiving entecavir