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Journal Articles

Retreat from stress; Rattling in a planar coordination

Suekuni, Koichiro*; Lee, C. H.*; Tanaka, Hiromi*; Nishibori, Eiji*; Nakamura, Atsushi*; Kasai, Hidetaka*; Mori, Hitoshi*; Usui, Hidetomo*; Ochi, Masayuki*; Hasegawa, Takumi*; et al.

Advanced Materials, 30(13), p.1706230_1 - 1706230_6, 2018/03

https://doi.org/10.1002/adma.201706230
 Times Cited Count：58 Percentile：89.18(Chemistry, Multidisciplinary)

Thermoelectric materials for highly efficient devices must satisfy conflicting requirements of high electrical conductivity and low thermal conductivity. In this paper, we studied the crystal structure and phonon dynamics of tetrahedrites (Cu,Zn)$$_{12}$$(Sb,As)$$_{4}$$S$$_{13}$$. The results revealed that the Cu atoms in a planar coordination are rattling, which effectively scatter phonons. These findings provide a new strategy for the development of highly efficient thermoelectric materials with planar coordination.

Journal Articles

First-principles study of antimony doping effects on the iron-based superconductor CaFe(Sb$$_{x}$$As$$_{1-x}$$)$$_{2}$$

Nagai, Yuki; Nakamura, Hiroki; Machida, Masahiko; Kuroki, Kazuhiko*

Journal of the Physical Society of Japan, 84(9), p.093702_1 - 093702_4, 2015/09

https://doi.org/10.7566/JPSJ.84.093702
 Times Cited Count：6 Percentile：43.68(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Switching of intra-orbital spin excitations in electron-doped iron pnictide superconductors

Iimura, Soshi*; Matsuishi, Satoru*; Miyakawa, Masashi*; Taniguchi, Takashi*; Suzuki, Katsuhiro*; Usui, Hidetomo*; Kuroki, Kazuhiko*; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; et al.

Physical Review B, 88(6), p.060501_1 - 060501_5, 2013/08

https://doi.org/10.1103/PhysRevB.88.060501
 Times Cited Count：26 Percentile：69.83(Materials Science, Multidisciplinary)

Journal Articles

$$Q$$-scan analysis of the neutron scattering in iron-based superconductors

Nagai, Yuki; Kuroki, Kazuhiko*

Physical Review B, 85(13), p.134521_1 - 134521_7, 2012/04

https://doi.org/10.1103/PhysRevB.85.134521
 Times Cited Count：6 Percentile：27.00(Materials Science, Multidisciplinary)

We propose a way to determine the pairing state of the iron pnictide superconductors exploiting the momentum ($$Q$$) scan of the neutron scattering data. We investigate the spin susceptibility in the $$s$$$$pm$$ and $$s$$$$_{++}$$ superconducting states for various doping levels using the effective five-orbital model and considering the quasiparticle damping. The peak position of the intensity shifts from the position on the line $$Q$$$$_{x}$$ = $$pi$$ to that on the line $$Q$$$$_{y}$$ = 0 as the doping level is decreased from electron doping to hole doping. We find that the $$Q$$ dependence of the ratio of the intensity in the superconducting state to that in the normal state is qualitatively different between the $$s$$$$pm$$-wave and $$s$$$$_{++}$$-wave pairings. We propose to investigate experimentally this ratio in $$Q$$ space to distinguish the two pairing states.

Journal Articles

Theoretical analysis for inelastic neutron scattering on BaFe$$_{2}$$(As$$_{1-x}$$,P$$_{x}$$)$$_{2}$$ using realistic three-dimensional 10-orbital tight-binding model

Nagai, Yuki; Nakamura, Hiroki; Suzuki, Katsuhiro*; Usui, Hidetomo*; Kuroki, Kazuhiko*; Machida, Masahiko

Journal of the Physical Society of Japan, 80(Suppl.B), p.SB021_1 - SB021_4, 2011/12

https://doi.org/10.1143/JPSJS.80SB.SB021
 Times Cited Count：0 Percentile：0.00(Physics, Multidisciplinary)

We calculate spin susceptibility on the basis of the multi-orbital random-phase approximation with use of the realistic three-dimensional 10-orbital tight-binding model for an iron-based superconductor BaFe$$_{2}$$(As$$_{1-x}$$,P$$_{x}$$)$$_{2}$$ which seems to have gap-nodes. We show that the shape of nodes on the Fermi surface for BaFe$$_{2}$$(As$$_{1-x}$$,P$$_{x}$$)$$_{2}$$ is distinguishable according to inelastic neutron scattering experiments. Our results are consistent with the recent neutron scattering experiments for BaFe$$_{2}$$(As$$_{1-x}$$,P$$_{x}$$)$$_{2}$$ with Tc = 30 K.

Journal Articles

$$s_{pm}$$-like spin resonance in the iron-based nodal superconductor BaFe$$_2$$(As$$_{0.65}$$P$$_{0.35}$$)$$_2$$ observed using inelastic neutron scattering

Ishikado, Motoyuki; Nagai, Yuki; Kodama, Katsuaki; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Wakimoto, Shuichi; Nakamura, Hiroki; Machida, Masahiko; Suzuki, Katsuhiro*; et al.

Physical Review B, 84(14), p.144517_1 - 144517_5, 2011/10

https://doi.org/10.1103/PhysRevB.84.144517
 Times Cited Count：27 Percentile：70.59(Materials Science, Multidisciplinary)

We performed inelastic neutron scattering on a powder sample of iron-based superconductor BaFe$$_2$$(As$$_{0.65}$$P$$_{0.35}$$)$$_2$$ with $$T_c$$ = 30 K. Although this system is expected to have line nodes in its superconducting order parameter, we have observed spin resonance at the same scattering vector as that appeared in the $$s_{pm}$$-wave iron-based superconductors without line nodes. Moreover, the resonance enhancement, which can be a measure of the area of sign reversal between the hole and electron Fermi surfaces (FSs), is comparable to those without line nodes. These facts indicate that the sign reversal between the FSs is still dominant in this system, and the line nodes should create only limited area of sign-reversal on a single FS. Hence the system can hold higher Tc than the other iron-based superconductors with nodal symmetry, such as LaFePO$$_{1-y}$$ and KFe$$_2$$As$$_2$$ ($$T_c <$$ 10 K).

Journal Articles

Determination of the pairing state in iron-based superconductors through neutron scattering

Nagai, Yuki; Kuroki, Kazuhiko*

Physical Review B, 83(22), p.220516_1 - 220516_4, 2011/06

https://doi.org/10.1103/PhysRevB.83.220516
 Times Cited Count：14 Percentile：50.35(Materials Science, Multidisciplinary)

We calculate the spin susceptibility in the $$s_pm$$ and $$s_{++}$$ superconducting states of the iron pnictides using the effective five orbital model and considering the quasiparticle damping. For the experimentally evaluated magnitude of the quasiparticle damping and the superconducting gap, the results at the wave vector $$simeq(pi,0)$$ show that the $$s_pm$$ state is more consistent with the neutron scattering experiments, while for larger quasiparticle damping and the superconducting gap, the $$s_{++}$$ state can be more consistent. To distinguish between two cases that reproduce the experiments at the wave vector $$simeq(pi,0)$$, we propose to investigate experimentally the wave vector $$simeq(pi,pi)$$.

Journal Articles

Distinct structural requirements for interleukin-4 (IL-4) and IL-13 binding to the shared IL-13 receptor facilitate cellular tuning of cytokine responsiveness

Ito, Takachika*; Suzuki, Shoichi*; Kanaji, Sachiko*; Shiraishi, Hiroshi*; Ota, Shoichiro*; Arima, Kazuhiko*; Tanaka, Go*; Tamada, Taro; Honjo, Eijiro*; Garcia, K. C.*; et al.

Journal of Biological Chemistry, 284(36), p.24289 - 24296, 2009/09

https://doi.org/10.1074/jbc.M109.007286
 Times Cited Count：24 Percentile：45.76(Biochemistry & Molecular Biology)

Both IL-4 and IL-13 can bind to the shared receptor composed of the IL-4 receptor $$alpha$$ chain and the IL-13 receptor $$alpha$$-1 chain (IL-13R$$alpha$$1); however, the assembly mechanisms of these ligands to the receptor is different, enabling the principal functions of these ligands to be different. We have previously shown that the N-terminal Ig-like domain in IL-13R$$alpha$$1, called the D1 domain, is the specific and critical binding unit for IL-13. However, it has still remained obscure which the amino acid has specific binding capacity to IL-13 and why the D1 domain acts as the binding site for IL-13, but not IL-4. To address these questions, in this study, we performed the mutational analyses for the D1 domain, combining the structural data to identify the amino acids critical for binding to IL-13. Mutations of Lys76, Lys77, or Ile78 in c' strand in which the crystal structure showed interact with IL-13 and those of Trp65 and Ala79 adjacent to the interacting site, resulted in significant impairment of IL-13 binding, demonstrating that these amino acids generate the binding site. Furthermore, mutations of Val35, Leu38, or Val42 at N-terminal $$beta$$-strand also resulted in loss of IL-13 binding, probably from decrease structural stability. None of the mutations employed here affected IL-4 binding. These results demonstrate that the hydrophobic patch composed of Lys76, Lys77, and Ile78 is the IL-13 recognition site and solidify our understanding that the differential requirements of the D1 domain in IL-13R$$alpha$$1 allows the shared receptor to respond differentially to IL-4 and IL-13.

Journal Articles

Expression of the extracellular region of the human interleukin-4 receptor $$alpha$$ chain and interleukin-13 receptor $$alpha$$1 chain by a silkworm-baculovirus system

Honjo, Eijiro; Shoyama, Yoshinari; Tamada, Taro; Shigematsu, Hideki*; Hatanaka, Takaaki*; Kanaji, Sachiko*; Arima, Kazuhiko*; Ito, Yuji*; Izuhara, Kenji*; Kuroki, Ryota

Protein Expression and Purification, 60(1), p.25 - 30, 2008/07

https://doi.org/10.1016/j.pep.2008.03.020
 Times Cited Count：13 Percentile：32.79(Biochemical Research Methods)

The receptor binding to Interleukin (IL)-13 is composed of the IL-13 receptor $$alpha$$1 chain (IL-13R $$alpha$$1) and the IL-4 receptor $$alpha$$ chain (IL-4R $$alpha$$). In order to investigate the interaction of IL-13 with IL-13R $$alpha$$1 and IL-4R $$alpha$$, the DNA fragments coding the extracellular regions of human IL-13R $$alpha$$1 and the IL-4R $$alpha$$ were fused with mouse Fc and expressed by a silkworm-baculovirus system. The expressed receptors were successfully purified by affinity chromatography using protein A, and the Fc region was removed by thrombin digestion. Size exclusion chromatography and SPR analysis revealed that mixture of IL-13 and IL-13R$$alpha$$1 showed predominant affinity to IL-4R$$alpha$$, although neither detectable affinity of IL-13 nor IL-13R$$alpha$$1 was observed against IL-4R$$alpha$$. Combining these data with the moderate affinity of IL-13 to IL-13R$$alpha$$1, this indicates that IL-13 first binds to IL-13R$$alpha$$1 and recruits consequently to IL-4R.

Oral presentation

Neutron scattering as a probe for determining the pairing state in iron pnictide superconductors

Nagai, Yuki; Kuroki, Kazuhiko*

no journal, , 

no abstracts in English

Oral presentation

Magnetic scattering on Fe-based superconductors La1111 and BaFe$$_2$$(As,P)$$_2$$

Ishikado, Motoyuki; Nagai, Yuki; Kodama, Katsuaki; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Mizuno, Fumio; Wakimoto, Shuichi; Nakamura, Hiroki; Machida, Masahiko; et al.

no journal, , 

We report systematic studies on Fe-based superconductors LaFeAsO$$_{1-x}$$F$$_x$$ ($$T^{max}_{rm c}$$ =28 K) and BaFe$$_2$$(As,P)$$_2$$ ($$T^{max}_{rm c}$$ =31 K) by using inelastic neutron scattering measurement.

Oral presentation

Spin resonance on nodal iron-based high-TC superconductors

Ishikado, Motoyuki; Kodama, Katsuaki; Wakimoto, Shuichi; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Mizuno, Fumio; Nagai, Yuki; Nakamura, Hiroki; Machida, Masahiko; et al.

no journal, , 

We have systematically studied nodal iron-based superconductor LaFePO$$_{0.9}$$ ($$T_{rm c}$$=5 K) and BaFe$$_2$$(As,P)$$_2$$ ($$T_{rm c}$$=30 K) by using Fermi chopper spectrometer 4SEASONS (J-PARC) and Triple Axis Spectrometer (TAS-1) at JRR-3. In the session, we will discuss the relation between superconductivity and spin fluctuation.

Oral presentation

Expression and purification of extracellular region of interleukin-13 receptor $$alpha$$1 chain and its interaction with its ligand

Kuroki, Ryota; Honjo, Eijiro; Tamada, Taro; Arima, Kazuhiko*; Izuhara, Kenji*

no journal, , 

Interleukin-13 (IL-13) interacts with two types of receptors, the IL-13R$$alpha$$1 chain (IL-13R$$alpha$$1) and the IL-4R$$alpha$$ chain (IL-4R$$alpha$$), that transduce the IL-13 signals. In order to investigate the interaction of IL-13 with IL-13R$$alpha$$1 and IL-4R$$alpha$$, the genes coding the extracellular regions of human IL-13R$$alpha$$1 and the IL-4R$$alpha$$ containing cytokine receptor homologous region (CRH), were fused with human Fc, and expressed by silk worm. After further purification with anion-exchange chromatography, the receptors were used to investigate the ligand-receptor interaction. The size exclusion chromatography showed that association between IL-13 and IL-13Ra1 could not be observed in this condition whereas the clear association of IL-13 and IL-13Ra1 was observed after adding IL-4R$$alpha$$. It indicates that the association between IL-13 and IL-4R$$alpha$$ increase the IL-13 affinity to IL-13R$$alpha$$1.

Oral presentation

Spin resonance on Fe-based superconductor BaFe$$_2$$(As,P)$$_2$$ with nodal gap symmetry

Ishikado, Motoyuki; Kodama, Katsuaki; Wakimoto, Shuichi; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Nagai, Yuki; Nakamura, Hiroki; Machida, Masahiko; Suzuki, Katsuhiro*; et al.

no journal, , 

In this study, we performed inelastic neutron scattering measurement on 36g polycrystalline powder sample of optimally-doped BaFe$$_2$$(As$$_{0.65}$$P$$_{0.35}$$)$$_2$$ using a Fermi chopper spectrometer 4SEASONS in J-PARC. We observed strong spin resonance at the same $$Q$$-position similar to those of other iron-based superconductors with fully-gapped $$s_{pm}$$-wave. We will discuss about the possible superconducting gap symmetry and what causes relatively high-$$T_{rm c}$$ of this material based on our inelastic neutron scattering results.

Oral presentation

Impurity effect in multi-orbital, sign-reversing s-wave superconductors

Nagai, Yuki; Kuroki, Kazuhiko*; Machida, Masahiko; Aoki, Hideo*

no journal, , 

no abstracts in English

Oral presentation

Efficient production of recombinant protease and cellulase by ${it Brevibacillus}$, expression system while difficult by ${it E. coli}$

Onishi, Hiromasa*; Mizukami, Makoto*; Hanagata, Hiroshi*; Tokunaga, Masao*; Kuroki, Ryota; Adachi, Motoyasu; Ishikawa, Kazuhiko*; Miyauchi, Akira*

no journal, , 

${it Brevibacillus}$ is one of the remarkable host developing to produce secretory proteins. The proteins above amount of 10g/L have been expressed into the medium using the Brevibacillus expression system as known examples. In addition, there are many examples of expression of proteins derived from bacteria to human proteins and including disulfide bridge. Recently, we succeeded in high-level and secretory expression of protease and cellulase which are not efficiently produced in E. coli expression system.

Oral presentation

Neutron scattering resonance as a probe for determining the pairing state in iron pnictide superconductor

Nagai, Yuki; Kuroki, Kazuhiko*

no journal, , 

no abstracts in English

Oral presentation

Spin resonance mode on Fe-based superconductor BaFe$$_2$$(As,P)$$_2$$ with $$T_{rm c}$$=30K

Ishikado, Motoyuki; Nagai, Yuki; Kodama, Katsuaki; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Wakimoto, Shuichi; Nakamura, Hiroki; Machida, Masahiko; Suzuki, Katsuhiro*; et al.

no journal, , 

In this study, we performed inelastic neutron scattering measurement on 36g polycrystalline powder sample of optimally-doped BaFe$$_2$$(As$$_{0.65}$$,P$$_{0.35}$$)$$_2$$ using Fermi chopper spectrometer 4SEASONS in J-PARC. Unexpectedly, we observed spin resonance at the same $$Q$$-position and nearly identical resonance enhancement ratio to other iron-based superconductors with fully-gapped $$s_{pm}$$-wave. We will discuss about the possible superconducting gap symmetry based on our inelastic neutron scattering experiment and theoretical calculations.

Oral presentation

Theoretical analyses of inelastic neutron scattering in iron pnictide superconductor

Nagai, Yuki; Kuroki, Kazuhiko*

no journal, , 

no abstracts in English

Oral presentation

Effect of HisTag on the secretion of cellulase EGPf by brevibacillus expression system

Shimizu, Rumi; Hiromoto, Takeshi; Adachi, Motoyasu; Kuroki, Ryota; Kataoka, Misumi*; Ishikawa, Kazuhiko*

no journal, , 

For neutron crystal structure analysis of proteins, it is necessary to prepare large crystals in volume (several mm$$^{3}$$) compared to that required for X-ray crystal structure analysis. To prepare the large volume crystal, we inevitably need much amount of purified protein. As a development in preparation of samples for neutron crystal structure analysis of proteins, we have tried to develop expression system for many kinds of protein using Eschericha coli, Brevibacillus, Pichia pastoris, cultivation cell and so on. Recently, we have succeeded in high level expression of cellulose (EGPf) derived from Archaea ${it Pyrococcus furiosus}$ using Brevibacillus system.

24 (Records 1-20 displayed on this page)