Magnetic Order in YbMn2Si2 - Neutron Scattering Investigation

S. J. Campbell,M. Hofmann,R. A. Mole,K. Prokes,D. Wallacher,J. L. Wang 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3

Several mechanisms have been proposed to account for the structural and magnetic behaviour ofthe rare earth intermetallic compound YbMn2Si2 below the transition that occurs around 30 K. We have carried out detailed neutron diffraction measurements over the temperature range 0.3 -52 K and confirm both an antiferromagnetic structure with ferromagnetic Mn (001) planes coupledantiferromagnetically along the c-axis above 30 K and the absence of ordering of the Yb sublatticedown to 0.3 K. The decrease in intensity of the (111) reflection around 30 K together with theappearance of satellite reflections of propagation vector k = 00 12 confirm that the magnetic unitcell doubles along the c axis below TN2. The resultant molecular field acting on half of the ionsbelow 30 K removes the degeneracy of the Kramers doublets of the Yb3+ ions and accounts forthe additional excitations observed below 30 K compared with the inelastic neutron scatteringabove 30 K.

Brain Tumor in the First Year of Life: A Single Institute Study

Chung, S.-K Korean Academy of Medical Science 1998 Journal of Korean medical science Vol.13 No.1

Dielectric and piezoelectric properties of Li-substituted lead-free (Bi_0.5Na_0.5)TiO₃@?(Bi_0.5K_0.5)TiO₃@?BaTiO₃ ceramics

Wang, L.,Song, T.K.,Lee, S.C.,Cho, J.H.,Sung, Y.S.,Kim, M.H.,Choi, K.S. Elsevier 2010 CURRENT APPLIED PHYSICS Vol.10 No.4

Lead-free 0.79(Bi<SUB>0.5</SUB>Na<SUB>0.5</SUB>)TiO<SUB>3</SUB>-0.14[Bi<SUB>0.5</SUB>(K<SUB>0.5-x</SUB>Li<SUB>x</SUB>)]TiO<SUB>3</SUB>-0.07BaTiO<SUB>3</SUB> (BNBK79+xLi, x=0.0, 0.1, 0.2, 0.25, 0.3, and 0.4) ceramics were prepared by conventional solid state reaction process. The crystalline structures and surface morphologies are investigated by X-ray diffraction method and scanning electron microscopy. Dielectric and piezoelectric properties were measured. With increasing of lithium substitution, the Curie temperatures of BNBK79+xLi ceramics increase, but the maximum value of the dielectric constant decreases. And a relatively large remnant polarization of 17.6μC/cm<SUP>2</SUP> and 157pC/N of d<SUB>33</SUB> has been obtained when x=0.3.

Effect of Temperature on Mechanical Anisotropy of Zircaloy-4 Sheet

Wang, Y .,Murty, K . L . 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.4

The effect of test temperature on the mechanical anisotropy parameters of Zircaloy-4 sheet was investigated using grilled tensile samples. The anisotropy parameters R and P were determined from tensile tests along the rolling (RD) and transverse (TD) directions respectively. Tests were carried out at a cross-head speed of 2.54 × 10^(-3) mm/s for various temperatures in the. range of ambient to 828 K. It was observed that the R parameter was essentially constant with a value of around 1.5. P parameter was constant in the range of ambient to 600 K with a value of around 2.8 while it decreased at higher temperatures to a value of around 1.

Evaluation of La_1.8Sr_0.2NiO_4+δ as cathode for intermediate temperature solid oxide fuel cells

Wang, Y.P.,Xu, Q.,Huang, D.P.,Zhao, K.,Chen, M.,Kim, B.H. Pergamon Press ; Elsevier Science Ltd 2016 International journal of hydrogen energy Vol.41 No.15

<P>The electrical conducting, thermal expansion and electrochemical properties of La1.8Sr0.2NiO4+delta were investigated in view of cathode utilization for intermediate temperature solid oxide fuel cells. La1.8Sr0.2NiO4+delta exhibited electrical conductivities of 96 -114 S cm(-1) at 600-800 degrees C and a thermal expansion coefficient of 12.6 x 10(-6) K-1 between 50 and 1000 degrees C. Based on a three-electrode half cell, the electrode properties of La1.8Sr0.2NiO4+delta were diagnosed using electrochemical impedance spectroscopy and chronopotentiometry techniques. Moreover, the, performance of an anode-supported single cell with La1.8Sr0.2NiO4+delta cathode was examined. Compared with La2NiO4+delta, La1.8Sr0.2NiO4+delta manifested improved electrode properties under cathodic polarization conditions while showing an analogous catalytic activity under open-circuit conditions. At 800 degrees C in air, La1.8Sr0.2NiO4+delta electrode displayed a polarization resistance of 0.41 0 cm(2) and a cathodic overpotential of 90 mV at 200 mA cm(-2). The anode-supported single cell with La1.8Sr0.2NiO4+delta cathode achieved a maximum power density of 520 mW cm(-2) at 800 degrees C in hydrogen fuel. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.</P>

Efficient long-term amplification of hepatitis B virus isolates after infection of slow proliferating HepG2-NTCP cells

Kö,nig, Alexander,Yang, Jaewon,Jo, Eunji,Park, Kyu Ho Paul,Kim, Hyun,Than, Thoa Thi,Song, Xiyong,Qi, Xiaoxuan,Dai, Xinghong,Park, Soonju,Shum, David,Ryu, Wang-Shick,Kim, Jung-Hee,Yoon, Seung Kew,P Elsevier 2019 Journal of hepatology Vol.71 No.2

<P><B>Background & Aims</B></P> <P>As hepatitis B virus (HBV) spreads through the infected liver it is simultaneously secreted into the blood. HBV-susceptible <I>in vitro</I> infection models do not efficiently amplify viral progeny or support cell-to-cell spread. We sought to establish a cell culture system for the amplification of infectious HBV from clinical specimens.</P> <P><B>Methods</B></P> <P>An HBV-susceptible sodium-taurocholate cotransporting polypeptide-overexpressing HepG2 cell clone (HepG2-NTCPsec+) producing high titers of infectious progeny was selected. Secreted HBV progeny were characterized by native gel electrophoresis and electron microscopy. Comparative RNA-seq transcriptomics was performed to quantify the expression of host proviral and restriction factors. Viral spread routes were evaluated using HBV entry- or replication inhibitors, visualization of viral cell-to-cell spread in reporter cells, and nearest neighbor infection determination. Amplification kinetics of HBV genotypes B-D were analyzed.</P> <P><B>Results</B></P> <P>Infected HepG2-NTCPsec+ secreted high levels of large HBV surface protein-enveloped infectious HBV progeny with typical appearance under electron microscopy. RNA-seq transcriptomics revealed that HBV does not induce significant gene expression changes in HepG2-NTCPsec+, however, transcription factors favoring HBV amplification were more strongly expressed than in less permissive HepG2-NTCPsec−. Upon inoculation with HBV-containing patient sera, rates of infected cells increased from 10% initially to 70% by viral spread to adjacent cells, and viral progeny and antigens were efficiently secreted. HepG2-NTCPsec+ supported up to 1,300-fold net amplification of HBV genomes depending on the source of virus. Viral spread and amplification were abolished by entry and replication inhibitors; viral rebound was observed after inhibitor discontinuation.</P> <P><B>Conclusions</B></P> <P>The novel HepG2-NTCPsec+ cells efficiently support the complete HBV life cycle, long-term viral spread and amplification of HBV derived from patients or cell culture, resembling relevant features of HBV-infected patients.</P> <P><B>Lay summary</B></P> <P>Currently available laboratory systems are unable to reproduce the dynamics of hepatitis B virus (HBV) spread through the infected liver and release into the blood. We developed a slowly dividing liver-derived cell line which multiplies infectious viral particles upon inoculation with patient- or cell culture-derived HBV. This new infection model can improve therapy by measuring, in advance, the sensitivity of a patient’s HBV strain to specific antiviral drugs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cell culture system that mimicks complete HBV life cycle from entry to egress. </LI> <LI> Efficient <I>in vitro</I> infection with crude HBV patient sera. </LI> <LI> Up to 50- and 1,300-fold net amplification of patient- and cell culture-derived input HBV in the supernatant. </LI> <LI> Polyethylene glycol-independent HBV spread to adjacent cells, forming infected cell clusters. </LI> <LI> Evaluation of patient- and cell culture-derived HBV amplification w/wo antivirals over 8 weeks. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Cas5d Protein Processes Pre-crRNA and Assembles into a Cascade-like Interference Complex in Subtype I-C/Dvulg CRISPR-Cas System

Nam, K.,Haitjema, C.,Liu, X.,Ding, F.,Wang, H.,DeLisa, Matthew P.,Ke, A. Current Biology 2012 Structure Vol.20 No.9

Clustered regularly interspaced short palindromic repeats (CRISPRs), together with an operon of CRISPR-associated (Cas) proteins, form an RNA-based prokaryotic immune system against exogenous genetic elements. Cas5 family proteins are found in several type I CRISPR-Cas systems. Here, we report the molecular function of subtype I-C/Dvulg Cas5d from Bacillus halodurans. We show that Cas5d cleaves pre-crRNA into unit length by recognizing both the hairpin structure and the 3' single stranded sequence in the CRISPR repeat region. Cas5d structure reveals a ferredoxin domain-based architecture and a catalytic triad formed by Y46, K116, and H117 residues. We further show that after pre-crRNA processing, Cas5d assembles with crRNA, Csd1, and Csd2 proteins to form a multi-sub-unit interference complex similar to Escherichia coli Cascade (CRISPR-associated complex for antiviral defense) in architecture. Our results suggest that formation of a crRNA-presenting Cascade-like complex is likely a common theme among type I CRISPR subtypes.

Overview of KSTAR research progress and future plans toward ITER and K-DEMO

Park, H.K.,Choi, M.J.,Hong, S.H.,In, Y.,Jeon, Y.M.,Ko, J.S.,Ko, W.H.,Kwak, J.G.,Kwon, J.M.,Lee, J.,Lee, J.H.,Lee, W.,Nam, Y.B.,Oh, Y.K.,Park, B.H.,Park, J.K.,Park, Y.S.,Wang, S.J.,Yoo, M.,Yoon, S.W.,B IOP 2019 Nuclear fusion Vol.59 No.11

<P>A decade-long operation of the Korean Superconducting Tokamak Advanced Research (KSTAR) has contributed significantly to the operation of superconducting tokamak devices and the advancement of tokamak physics which will be beneficial for the ITER and K-DEMO programs. Even with limited heating capability, various conventional as well as new operating regimes have been explored and have achieved improved performance. As examples, a long pulse high-confinement mode operation with and without an edge-localized mode (ELM) crash was well over 70 and 30 s, respectively. The unique capabilities of KSTAR allowed it to improve the capability of controlling harmful instabilities, and they have been instrumental in uncovering much new physics. The highlights are that the L/H transition threshold power is sensitive to the resonant magnetic perturbation (RMP) and insensitive to non-resonant magnetic perturbation. Co-<I>I</I> <SUB>p</SUB> offset rotation dominated by an electron channel predicted by general neoclassical toroidal viscosity theory was confirmed. Improved heat dispersal in a divertor system using three rows of rotating RMP was demonstrated and predictive control of the ELM-crash with <I>a priori</I> modeling was successfully tested. In magnetohydrodynamic physics, validation of the full reconnection model (i.e. <I>q</I> <SUB>0</SUB>  >  1 right after the sawtooth crash) and self-consistent validation of the anisotropic distribution of turbulence amplitude and flow in the presence of the 2/1 island with theoretical models were achieved. The turbulence amplitude induced by RMP was linearly increased with the slow RMP coil current ramp-up time (i.e. the magnetic diffusion time scale). The <I>D</I> <SUB> <I>α</I> </SUB> spikes (i.e. ELM-crash amplitude) was linearly decreased with the turbulence amplitude and not correlated with the perpendicular electron flow. In the turbulence area, a non-diffusive ‘avalanche’ transport event and the role of a quiescent coherent mode in confinement were studied. To accommodate the anticipation of a higher performance of the KSTAR plasmas with the increased heating powers, a new divertor/internal interface with a full active cooling system will be implemented after a full test of the new heating (neutral beam injection II and electron cyclotron heating) and current drive (CD) (Helicon and lower hybrid CD) systems. An upgrade plan for the internal hardware, heating systems and efficient CD system may allow for a long pulse operation of higher performance plasmas at <I>β</I> <SUB>N</SUB>  >  3.0 with <I>f</I> <SUB>bs</SUB> ~ 0.5 and <I>T</I> <SUB>i</SUB>  >  10 keV.</P>

Observation ofB0→pp¯K*0with a LargeK*0Polarization

Chen, J.-H.,Wang, M.-Z.,Adachi, I.,Aihara, H.,Arinstein, K.,Aulchenko, V.,Aushev, T.,Bakich, A. M.,Balagura, V.,Barberio, E.,Bay, A.,Bedny, I.,Belous, K.,Bitenc, U.,Bondar, A.,Bozek, A.,Brač,ko, American Physical Society 2008 Physical review letters Vol.100 No.25

<P>Using a 492 fb{-1} data sample collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e{+}e{-} collider, we observe the decay B{0}-->ppK*0 with a branching fraction of (1.18{-0.25}{+0.29}(stat)+/-0.11(syst))x10{-6}. We study the decay dynamics of B{0}-->ppK*0 and compare with B{+}-->ppK*+. The K*0 meson is found to be almost 100% polarized (with a fraction of (101+/-13+/-3)% in the helicity zero state), while the K*+ meson has a (32+/-17+/-9)% fraction in the helicity zero state. The direct CP asymmetries for B{0}-->ppK*0 and B{+}-->ppK*+ are measured to be -0.08+/-0.20+/-0.02 and -0.01+/-0.19+/-0.02, respectively. In addition, we report improved measurements of the branching fractions B(B{+}-->ppK*+)=(3.38{-0.60}{+0.73}+/-0.39)x10{-6} and B(B{0}-->ppK{0})=(2.51{-0.29}{+0.35}+/-0.21)x10{-6}, which supersede our previous measurements.</P>

Electronic and phonon excitations in α−RuCl3

Reschke, S.,Mayr, F.,Wang, Zhe,Do, Seung-Hwan,Choi, K.-Y.,Loidl, A. American Physical Society 2017 Physical Review B Vol.96 No.16

<P>We report on terahertz (THz), infrared reflectivity, and transmission experiments for wavenumbers from 10 to 8000 cm(-1) (similar to 1meV-1eV) and for temperatures from 5 to 295 K on the Kitaev candidate material alpha-RuCl3. As reported earlier, the compound under investigation passes through a first-order structural phase transition, from a monoclinic high-temperature to a rhombohedral low-temperature phase. The phase transition shows an extreme and unusual hysteretic behavior, which extends from 60 to 166 K. In passing this phase transition, in the complete frequency range investigated, we found a significant reflectance change, which amounts to almost a factor of two. We provide a broadband spectrum of dielectric constant, dielectric loss, and optical conductivity from the THz to the mid-infrared regime and study in detail the phonon response and the low-lying electronic density of states. We provide evidence for the onset of an optical energy gap, which is on the order of 200 meV, in good agreement with the gap derived from measurements of the dc electrical resistivity. Remarkably, the onset of the gap exhibits a strong blue shift on increasing temperatures.</P>