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We performed an angle-resolved photoemission spectroscopy study of Si-doped β-Ga2O3. We observed very small photoemission intensity near the Fermi level corresponding to non-dispersive states assigned to Si impurities. We show evidence for a quantization of these states that is accompanied by a confinement in the momentum space consistent with a real-space finite confinement observed in a previous scanning tunneling microscopy study. Our results suggest that this semi-localization in the conjugate spaces plays a crucial role in the electronic conduction of this material. [ABSTRACT FROM AUTHOR]

We performed systematic spin- and angle-resolved photoemission spectroscopy of TlBKSSe which undergoes a topological phase transition at x ~ 0.5. In TlBiSe2 (x = 1.0), we revealed a helical spin texture of Dirac-cone surface states with an intrinsic in-plane spin polarization of ~0.8. The spin polarization still survives in the gapped surface states at x > 0.5, although it gradually weakens upon approaching x = 0.5 and vanishes in the nontopological phase. No evidence for the out-of-plane spin polarization was found, irrespective of x and momentum. The present results unambiguously indicate the topological origin of the gapped Dirac surface states, and also impose a constraint on models to explain the origin of mass acquisition of Dirac fermions. [ABSTRACT FROM AUTHOR]

We have performed angle-resolved photoemission spectroscopy on Pb(Bi1-xSbx)2Te4, which is a member of lead-based ternary tellurides and has been theoretically proposed as a candidate for a new class of three-dimensional topological insulators. In PbBi2Te4, we found a topological surface state with a hexagonally deformed Dirac-cone band dispersion, indicating that this material is a strong topological insulator with a single topological surface state at the Brillouin-zone center. Partial replacement of Bi with Sb causes a marked change in the Dirac carrier concentration, leading to the sign change of Dirac carriers from n type to p type. The Pb(Bi1-xSbx)2Te4 system with tunable Dirac carriers thus provides a new platform for investigating exotic topological phenomena. [ABSTRACT FROM AUTHOR]

RATIONALE: Senescence marker protein-30 (SMP30) is a multifunctional protein providing protection to cellular functions from age-associated deterioration. We previously reported that SMP30 knockout (SMP30Y/-) mice are capable of being novel models for senile lung with age-related airspace enlargement and enhanced susceptibility to harmful stimuli. OBJECTIVES: Aging and smoking are considered as major contributing factors for the development of pulmonary emphysema. We evaluated whether SMP30Y/- mice are susceptible to oxidative stress associated with aging and smoking. METHODS: Age-related changes of protein carbonyls in lung tissues from the wild-type (SMP30Y/+) and SMP30Y/- mice were evaluated. Both strains were exposed to cigarette smoke for 8 wk. Histopathologic and morphologic evaluations of the lungs, protein carbonyls and malondialdehyde in the lung tissues, total glutathione content in the bronchoalveolar lavage fluid, and degree of apoptosis of lung cells were determined. MEASUREMENTS AND MAIN RESULTS: In the lungs of SMP30Y/- mice, protein carbonyls tended to increase with aging and were significantly higher than the age-matched SMP30Y/+ mice. Cigarette smoke exposure generated marked airspace enlargement (23.3% increase of the mean linear intercepts) with significant parenchymal destruction in the SMP30Y/- mice but not in the SMP30Y/+ mice (5.4%). The protein carbonyls, malondialdehyde, total glutathione, and apoptosis of lung cells were significantly increased after 8-wk exposure to cigarette smoke in the SMP30Y/- mice. Conclusions: Our results suggest that SMP30 protects mice lungs from oxidative stress associated with aging and smoking. The SMP30Y/- mice could be useful animal models for investigating age-related lung diseases, including cigarette smoke-induced pulmonary emphysema. [ABSTRACT FROM AUTHOR]

Abstract: We have performed ultrahigh-resolution photoemission spectroscopy (PES) on superconducting hexaboride YB6 ( K) to investigate the electronic structure in the vicinity of the Fermi level (). We have succeeded in directly observing the superconducting gap together with a sharp coherent peak in the superconducting state (5 K). From the numerical simulation of the PES spectra by using isotropic Dynes function, we have estimated the size of the superconducting gap to be 0.9 meV, which corresponds to 2 (0)/. We found a dip structure around 10 meV with respect to in the PES spectrum in the superconducting state. This structure is attributed to the strong coupling feature of electrons with the 10 meV acoustic phonon. These results indicate that YB6 is categorized into phonon-mediated BCS superconductor in the strong or intermediate coupling regime. [Copyright &y& Elsevier]

Two cell lines producing monoclonal antibodies, Abp4 (IgM) and Abp7 (IgG1) against ampicillin were established. The epitopes and the cross-reactions of the antibodies with various beta-lactams were examined by enzyme-linked immunosorbent assay (ELISA) and ELISA inhibition test. Abp4 showed broad cross-reaction to human serum albumin (HSA) conjugates of several beta-lactams, 6-aminopenicillanic acid and 7-aminocephalosporanic acid. Abp7 reacted only with ampicillin and cephalexin, which have the same acyl side chain. In ELISA inhibition tests, Abp4 inhibited binding to ampicillin-HSA by benzylpenicilloyl-epsilon-amino-n-caproic acid, and strongly inhibited the binding by penicillamine. Abp7 strongly inhibited the reaction by aminobenzylpenicilloyl-epsilon-amino-n-caproic acid, but benzylpenicilloyl-epsilon-amino-n-caproic acid was less effected. These data suggest that Abp4 recognizes the thiazolidine ring and Abp7 recognizes the acyl side chain. Therefore, the thiazolidine ring-epitope acts in broad cross-reaction among beta-lactams, and the acyl side chain acts only in the cross-reactivity between penam and cephem, which have a similar acyl side chain. [ABSTRACT FROM AUTHOR]

Abstract: We have performed UV and X-ray angle-resolved photoemission spectroscopy (ARPES) on AlB2 which is a non-superconducting reference of MgB2. We found that the -band is totally occupied in AlB2 in contrast to the partially occupied -band in MgB2, which suggests that the -band on the Fermi level is essential for the superconductivity. We also found an electron pocket centered at the (A) point in the UVARPES spectrum as in MgB2, while it is absent in the X-ray ARPES spectra. This indicates that the electron pocket is of surface origin. [Copyright &y& Elsevier]

We report high-resolution angle-resolved photoemission spectroscopy of LaRh3B2, which is a nonmagnetic reference compound of RRh3B2 (R: rare-earth metals). We found two hole-like Fermi surfaces (FSs) and two electron-like FSs centered at and points, respectively. The estimated volume of FSs at point shows a good agreement with the LDA band calculation, while the band dispersion and the topology of FSs at point show a remarkable disagreement. [Copyright &y& Elsevier]

Magnesium diboride, MgB2, has the highest transition temperature (Tc = 39?K) of the known metallic superconductors. Whether the anomalously high Tc can be described within the conventional BCS (Bardeen-Cooper-Schrieffer) framework has been debated. The key to understanding superconductivity lies with the 'superconducting energy gap' associated with the formation of the superconducting pairs. Recently, the existence of two kinds of superconducting gaps in MgB2 has been suggested by several experiments; this is in contrast to both conventional and high-Tc superconductors. A clear demonstration of two gaps has not yet been made because the previous experiments lacked the ability to resolve the momentum of the superconducting electrons. Here we report direct experimental evidence for the two-band superconductivity in MgB2, by separately observing the superconducting gaps of the s and p bands (as well as a surface band). The gaps have distinctly different sizes, which unambiguously establishes MgB2 as a two-gap superconductor. [ABSTRACT FROM AUTHOR]

Magnesium diboride, MgB2, has the highest transition temperature (Tc = 39?K) of the known metallic superconductors. Whether the anomalously high Tc can be described within the conventional BCS (Bardeen-Cooper-Schrieffer) framework has been debated. The key to understanding superconductivity lies with the 'superconducting energy gap' associated with the formation of the superconducting pairs. Recently, the existence of two kinds of superconducting gaps in MgB2 has been suggested by several experiments; this is in contrast to both conventional and high-Tc superconductors. A clear demonstration of two gaps has not yet been made because the previous experiments lacked the ability to resolve the momentum of the superconducting electrons. Here we report direct experimental evidence for the two-band superconductivity in MgB2, by separately observing the superconducting gaps of the s and p bands (as well as a surface band). The gaps have distinctly different sizes, which unambiguously establishes MgB2 as a two-gap superconductor. [ABSTRACT FROM AUTHOR]

High-resolution angle-resolved photoemission spectroscopy has been carried out to clarify the anomalous superconductivity of MgB2. We observed three bands crossing the Fermi level, which are ascribed to B2p–σ, π and surface bands. We have succeeded for the first time in directly observing the superconducting gaps of these bands separately. We have found that the superconducting-gap sizes of σ and surface bands are 6.5 ± 0.5 and 6.0 ± 0.5 meV, respectively, while that of the π band is much smaller (1.5 ± 0.5 meV). The present experimental result unambiguously demonstrates the validity of the two-band superconductivity in MgB2. [Copyright &y& Elsevier]

We have performed a temperature-dependent ultrahigh-resolution photoemission spectroscopy on SmB6 to study the “Kondo-insulator” nature. We found a sharp Sm 4f-derived peak about 18 meV away from EF and a pseudogap at EF at low temperature. The pseudogap is gradually filled-in by the transfer of spectral weight from the sharp peak at high temperatures. This indicates that the pseudogap is a Kondo-insulator gap originating in the hybridization between the Sm 4f states and the conduction electrons. [Copyright &y& Elsevier]

We report high-resolution angle-resolved photoemission spectroscopy (ARPES) on high quality single crystal of graphite (kish graphite) to elucidate the origin of anomalous physical properties of carbon-based materials. We found an almost flat band in the vicinity of the Fermi level around the K(H) point which is not predicted by the bulk band calculation. We discuss the origin of this anomalous structure in relation to the edge-localized state on the step edges of cleaved surface. [ABSTRACT FROM AUTHOR]

We have performed spin-and angle-resolved photoemission spectroscopy on tungsten (110) interfaced with an ultrathin iron (Fe) layer to study an influence of ferromagnetism on the Dirac-cone-like surfaceinterface states. We found an unexpectedly large energy gap of 340 meV at the Dirac point, and have succeeded in switching the Dirac-fermion mass by controlling the direction of Fe spins (in plane or out of plane) through tuning the thickness of the Fe overlayer or adsorbing oxygen on it. Such a manipulation of Dirac-fermion mass via the magnetic proximity effect opens a promising platform for realizing new spintronic devices utilizing a combination of exchange and Rashba-spin-orbit interactions. [ABSTRACT FROM AUTHOR]

We have performed high-resolution angle-resolved photoemission spectroscopy on layered polymorph series of 1H-, 5H-, and 6H-CaAlSi, which exhibit superconductivity below 6.5, 5.7, and 7.7 K, respectively. While the overall band structure in the valence-band region is similar among these compounds, the volume of the Fermi surface at the M point and the magnitude of the superconducting gap are markedly different from each other. Implications of such variation in the electronic structure due to the superstructure along the c axis are discussed in relation to the physical properties of CaAlSi. [ABSTRACT FROM AUTHOR]

We report high-resolution spin- and angle-resolved photoemission spectroscopy of bismuth thin film on Si(1 1 1) to discuss the spin structure of surface states. We found that, unlike conventional picture of the Rashba splitting, the magnitude of the in-plane spin polarization is asymmetric between two hole pockets across the Brillouin-zone center. In addition, these pockets exhibit a giant out-of-plane spin polarization as large as the in-plane counterpart, which changes the sign across the Γ ¯     M ¯ line. We also revealed that the spin polarization of the Rashba surface states near the Brillouin-zone boundary (the M ¯ point) is gradually reduced on decreasing the film thickness. Our result provides a new pathway to generate and control spin-polarized electrons in the Rashba system. [ABSTRACT FROM AUTHOR]

We performed an angle-resolved photoemission spectroscopy study of Si-doped β-Ga2O3. We observed very small photoemission intensity near the Fermi level corresponding to non-dispersive states assigned to Si impurities. We show evidence for a quantization of these states that is accompanied by a confinement in the momentum space consistent with a real-space finite confinement observed in a previous scanning tunneling microscopy study. Our results suggest that this semi-localization in the conjugate spaces plays a crucial role in the electronic conduction of this material. [ABSTRACT FROM AUTHOR]

We have performed angle-resolved photoemission spectroscopy of CuABi2Se3 as a function of Cu doping (x = 0.0-0.25) to investigate the doping-induced evolution of the electronic structure. We found that the topological surface state is preserved even in the heavy-doping region (x = 0.25), indicative of the robustness of the surface state against doping and impurities. The estimated carrier concentration is far smaller than that expected from a simple intercalation picture, and saturates at x ∼ 0.1 where superconductivity emerges. This indicates that the carrier concentration responsible for superconductivity is dominated by a subtle balance between two competing processes of electron and hole doping. [ABSTRACT FROM AUTHOR]