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X-ray Absorption and Photoemission Spectroscopy Study of Nd½A½Mn₁-yCryO₃ (A=Ca, Sr)
J.-S. Kang,J. H. Kim,S. W. Han,K. H. Kim,E. J. Choi,A. Sekiyama,S. Kasai,S. Suga,T. Kimura 한국자기학회 2003 Journal of Magnetics Vol.8 No.4
Valence states and electronic structures of Cr-doped Nd½A½MnO₃ (NAMO; A=Ca, Sr) manganites have been investigated using x-ray absorption spectroscopy (XAS) and high-resolution photoemission spectroscopy (PES). All the Cr-doped NAMO systems exhibit the clear metallic Fermi edges in the Mn e_g PES spectra near E_F. The spectral intensity at E_F is higher for Cr-doped Nd½Sr½MnO₃ (NSMO) than for Cr-doped Nd½Ca½MnO₃ (NCMO), reflecting the stronger metallic nature for NSMO than for NCMO. The measured Cr 2p XAS spectra are found to be very similar to that of Cr₂O₃, indicating that Cr ions in Cr-doped NAMO are in the trivalent Cr³+ states (t³_(2g)). The Cr 2p XAS data are consistent with the Cr 3d PES spectra located at ~1.3 eV below EF and having no emission near E_F.
Ryu, H.J.,Jin, X.,Lee, J.H.,Woo, H.J.,Kim, Y.M.,Kim, G.J.,Seo, E.S.,Kang, H.K.,Kim, J.,Cho, D.L.,Kimura, A.,Kim, D. IPC Science and Technology Press ; Elsevier Scienc 2010 Enzyme and microbial technology Vol.47 No.5
Long isomalto-oligosaccharides (IMOs) were generated via an engineered fusion enzyme of dextransucrase and dextranase (DSXR). To increase the expression level, response surface methodology (RSM) was utilized for optimization of protein expression conditions for enhancement of protein production by the effects of three-level-three-factors and their mutual interaction in Escherichia coli. Seventeen experiments were designed and conducted for investigation of cell density to start induction, induction temperature, and induction time. Optimal induction conditions included a cell density to start induction (A<SUB>600</SUB>) of 0.76 at 12.16<SUP>o</SUP>C for 18h for dextransucrase activity and a cell density to start induction (A<SUB>600</SUB>) of 0.75 at 10.5<SUP>o</SUP>C for 20.9h for dextranase activity. The produced dextransucrase or dextranase activity was obtained at 120.1+/-7.2 or 871+/-58U, respectively, from 1L cultures.
Single-crystal Study on the Low-temperature Magnetism of the Pyrochlore Magnet Pr2Zr2O7
Kenta Kimura,Satoru Nakatsuji,A. Agung Nugroho 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3
A single-crystal study on the low-temperature magnetism of a pyrochlore magnet Pr2Zr2O7 hasbeen carried out. The temperature dependence of the magnetic susceptibility shows no magneticordering at temperatures down to 1.9 K. The Curie-Weiss behavior was observed at temperaturesbelow 10 K, yielding an effective moment µeff = 2.5µB. This result, combined with those of recentreports on other Pr3+ pyrochlore magnets, suggests that the ground state of the Pr3+ crystal electricfield is a well-separated magnetic doublet. An anisotropic magnetization process is observed at lowertemperatures, and the saturated magnetization values along the three high-symmetry directions areconsistent with a local h111i Ising anisotropy with a magnetic moment gJJ = µeff = 2.5µB.
Giant magneto-elastic coupling in multiferroic hexagonal manganites
Lee, Seongsu,Pirogov, A.,Kang, Misun,Jang, Kwang-Hyun,Yonemura, M.,Kamiyama, T.,Cheong, S.-W.,Gozzo, F.,Shin, Namsoo,Kimura, H.,Noda, Y.,Park, J.-G. Nature Publishing Group 2008 Nature Vol.451 No.7180
The motion of atoms in a solid always responds to cooling or heating in a way that is consistent with the symmetry of the given space group of the solid to which they belong. When the atoms move, the electronic structure of the solid changes, leading to different physical properties. Therefore, the determination of where atoms are and what atoms do is a cornerstone of modern solid-state physics. However, experimental observations of atomic displacements measured as a function of temperature are very rare, because those displacements are, in almost all cases, exceedingly small. Here we show, using a combination of diffraction techniques, that the hexagonal manganites RMnO<SUB>3</SUB> (where R is a rare-earth element) undergo an isostructural transition with exceptionally large atomic displacements: two orders of magnitude larger than those seen in any other magnetic material, resulting in an unusually strong magneto-elastic coupling. We follow the exact atomic displacements of all the atoms in the unit cell as a function of temperature and find consistency with theoretical predictions based on group theories. We argue that this gigantic magneto-elastic coupling in RMnO<SUB>3</SUB> holds the key to the recently observed magneto-electric phenomenon in this intriguing class of materials.
IRRADIATION EMBRITTLEMENT OF CLADDING AND HAZ OF RPV STEEL
Lee J.S.,Kim I.S.,Jang C.H.,Kimura A. Korean Nuclear Society 2006 Nuclear Engineering and Technology Vol.38 No.5
Microstructural features and their related mechanical property changes in the 309L cladding and the heat affected zone (HAZ) of SA508 cl.3 steel were investigated through the use of TEM, tensile and small punch (SP) tests. The specimens were irradiated at 563 K up to the neutron fluences of $5.79{\times}10^{19}n/cm^2$ (>1MeV). The microstructure of the clad was mainly composed of a fcc ${\gamma}-phase$, a low percentage of bcc ${\delta}-ferrite$, and a brittle ${\sigma}-phase$. Along the weld fusion line there formed a heavy carbide precipitation with a width of $20{\sim}40{\mu}m$, showing preferential cracking during plastic deformation. The yield stress and ductile-to-brittle transition temperature (DBTT) of the irradiated clads increased. The origin of the hardening and the shift of the DBTT are discussed in terms of the irradiation-produced defect clusters of a fine size and brittle ${\sigma}-phase$.
Multi-Quasiparticle States in Odd-Odd 118I
C.-B. Moon,이춘식,M. Oshima,Y. Toh,J. Goto,Y. Hatsukawa,A. Kimura,M. Koizumi,A. Osa,T. Komatsubara,K. Miyakawa 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.4
The excited states of the doubly odd nucleus 118I have been studied by using in-beam γ-ray spectroscopy with the 110Cd(12C, p3n) reaction at Elab = 80 MeV. We have established several multi-quasiparticle states associated with different proton and neutron quasiparticle configurations. A I* = 14- level at 2561 keV was newly observed and found to be associated with the πh11/2υd5/2 configuration coupled to a pair of protons in the g7/2 orbital. TRS calculations for the 14- level indicated a favored oblate state based on the fully aligned four-quasiparticle π[h11=2(g7/2)2]23/2-υ[d5/2]5/2+ configuration. Another energetically favored state I* = 24- at 6216 keV could be interpreted as a noncollective oblate state from the fully aligned six-quasiparicle π[h11/2(g7/2)2]23/2-υ[d5/2(h11/2)2]25/2+ configuration. No Δ = 1 side band of the same parity as the πh11/2υh11/2 band was observed while a side band built on the πg9/2υh11/2 configuration was considered to be caused by the γ vibration coupling.
Kim, D Y,Ryu, D H,Hong, J B,Park, J-G,Kwon, Y S,Jung, M A,Jung, M H,Takeda, N,Ishikawa, M,Kimura, S IOP Pub 2004 Journal of Physics, Condensed Matter Vol.16 No.46
<P>We report on the magnetic susceptibility, specific heat and electrical resistivity of the heavy fermion compounds CeNiGe<SUB>2−<I>x</I></SUB>Si<SUB><I>x</I></SUB> (<img ALIGN='MIDDLE' SRC='http://ej.iop.org/images/0953-8984/16/46/018/cm185233ieqn1.gif' ALT='0\leq x \leq 1 '/>). Compounds with <I>x</I><1 show antiferromagnetic order, which with increasing <I>x</I> shifts toward lower temperature owing to increased exchange coupling between the localized 4f magnetic moments and conduction electrons. Eventually, the magnetic order almost becomes absent, for <I>x</I> = 1. An anomaly observed in the specific heat is well interpreted by the Kondo model for a degenerate impurity spin <I>J</I> = 1/2 in the Coqblin–Schrieffer limit. A coherence peak indicative of the formation of a Kondo lattice is found in the electrical resistivity, whose features are consistent with the results for the specific heat. Interestingly, there is a significant deviation from Fermi-liquid behaviour at the critical concentration <I>x</I> = 1. This deviation is attributed to a quantum phase transition in a model with two-dimensional antiferromagnetic fluctuations.</P>
Rapid Variable-Number Tandem-Repeat Genotyping for Mycobacterium leprae Clinical Specimens
Kimura, M.,Sakamuri, R. M.,Groathouse, N. A.,Rivoire, B. L.,Gingrich, D.,Krueger-Koplin, S.,Cho, S.-N.,Brennan, P. J.,Vissa, V. American Society for Microbiology 2009 Journal of clinical microbiology Vol.47 No.6
<P>Mycobacterium leprae is the noncultivable pathogen of leprosy. Since the genome sequence of an isolate of M. leprae has become available, multiple-locus variable-number tandem-repeat (VNTR) analysis (MLVA) has been explored as a tool for strain typing and identification of chains of transmission of leprosy. In order to discover VNTRs and develop methods transferable to clinical samples, MLVA was applied to a global collection of M. leprae isolates derived from leprosy patients and propagated in armadillo hosts. PCR amplification, agarose gel electrophoresis, and sequencing methods were applied to DNA extracts from these infected armadillo tissues (n = 21). We identified polymorphisms in 15 out of 25 short-tandem-repeat (STR) loci previously selected by in silico analyses of the M. leprae genome. We then developed multiplex PCR for amplification of these 15 loci in four separate PCRs suitable for fluorescent fragment length analysis and demonstrated STR profiles highly concordant with those from the sequencing methods. Subsequently, we extended this method to DNA extracts from human clinical specimens, such as skin biopsy specimens (n = 30). With these techniques, mapping of multiple loci and differentiation of genotypes have been possible using total DNA extracts from limited amounts of clinical samples at a reduced cost and with less time. These practical methods are therefore available and applicable to answer focused epidemiological questions and to allow monitoring of the transmission of M. leprae in different countries where leprosy is endemic.</P>
T. Kin,K. Furutaka,S. Goko,H. Harada,A. Kimura,F. Kitatani,S. Nakamura,M. Ohta,M. Oshima,Y. Toh,J. Hori,M. Igashira,T. Katabuchi,M. Koizumi,M. Mizumoto,T. Kamiyama,K. Kino,Y. Kiyanagi 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
A ``4π germanium spectrometer'' was developed for measurements of neutron capture cross sections of minor actinides and long-lived fission products. It was installed on the Beam Line No. 04 of the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex. The time-of-flight method is used to measure the cross sections. To obtain characteristics of the spectrometer, a measurement was done of prompt gamma rays emitted following neutron capture reactions of gold whose cross section was well studied. In the present paper, we show the procedure of analysis of the data obtained with the spectrometer and discuss the characteristics to measure neutron capture cross section.