Waseda University

About: Waseda University is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Catalysis & Large Hadron Collider. The organization has 24220 authors who have published 46859 publications receiving 837855 citations. The organization is also known as: Waseda daigaku & Sōdai.

Fabrication of two-dimensional hybrid sheets by decorating insulating PANI on reduced graphene oxide for polymer nanocomposites with low dielectric loss and high dielectric constant

Abstract: Novel polyaniline decorated reduced graphene oxide (rPANI@rGO) two-dimensional (2D) hybrids sheets were successfully prepared by in situ polymerization of aniline on graphene oxide (GO) sheets and successive reduction by hydrazine. PANI is heavily reduced, thus it is electrically insulating. The hybrid sheets were used as a novel filler for high performance poly(methyl methacrylate) (PMMA) nanocomposites. Our results show that, when compared with the PMMA/rGO composites, the PMMA/rPANI@rGO nanocomposites not only show a high dielectric constant but also have low dielectric loss. For example, at 1000 Hz, a dielectric constant of 40 and a dielectric loss of 0.12 were observed in the PMMA/rPANI@rGO nanocomposite with rGO/PMMA volume ratio of 6%, whereas the dielectric constant and dielectric loss of PMMA/rGO composite with rGO/PMMA volume ratio of 6% are about 20 and 1250, respectively. More importantly, the dielectric properties of PMMA/rPANI@rGO nanocomposites can be tuned by controlling the addition of the hybrid sheets. The improved dielectric properties in PMMA/rPANI@rGO nanocomposites should originate from the isolation effect of rPANI on the rGO in PMMA matrix, which not only improves the dispersion of rGO but also hinders the direct electrical contact between rGO. This research sets up a novel route to polymer composites with high dielectric constants and low dielectric loss, and also expands the application space of graphene-based fillers.

Dynamical mass ejection from black hole-neutron star binaries

Abstract: We investigate properties of material ejected dynamically in the merger of black hole-neutron star binaries by numerical-relativity simulations. We systematically study the dependence of ejecta properties on the mass ratio of the binary, spin of the black hole, and equation of state of the neutron-star matter. Dynamical mass ejection is driven primarily by tidal torque, and the ejecta is much more anisotropic than that from binary neutron star mergers. In particular, the dynamical ejecta is concentrated around the orbital plane with a half opening angle of 10\ifmmode^\circ\else\textdegree\fi{}--20\ifmmode^\circ\else\textdegree\fi{} and often sweeps out only a half of the plane. The ejecta mass can be as large as $\ensuremath{\sim}0.1{M}_{\ensuremath{\bigodot}}$, and the velocity is subrelativistic with $\ensuremath{\sim}0.2--0.3c$ for typical cases. The ratio of the ejecta mass to the bound mass (disk and fallback components) is larger, and the ejecta velocity is larger, for larger values of the binary mass ratio, i.e., for larger values of the black-hole mass. The remnant black hole-disk system receives a kick velocity of $O(100)\text{ }\text{ }\mathrm{km}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ due to the ejecta linear momentum, and this easily dominates the kick velocity due to gravitational radiation. Structures of postmerger material, velocity distribution of the dynamical ejecta, fallback rates, and gravitational waves are also investigated. We also discuss the effect of ejecta anisotropy on electromagnetic counterparts, specifically a macronova/kilonova and synchrotron radio emission, developing analytic models.

Search for Heavy Higgs Bosons Decaying into Two Tau Leptons with the ATLAS Detector Using pp Collisions at s =13 TeV

Abstract: A search for heavy neutral Higgs bosons is performed using the LHC Run 2 data, corresponding to an integrated luminosity of 139 fb^{-1} of proton-proton collisions at sqrt[s]=13 TeV recorded with the ATLAS detector. The search for heavy resonances is performed over the mass range 0.2-2.5 TeV for the τ^{+}τ^{-} decay with at least one τ-lepton decaying into final states with hadrons. The data are in good agreement with the background prediction of the standard model. In the M_{h}^{125} scenario of the minimal supersymmetric standard model, values of tanβ>8 and tanβ>21 are excluded at the 95% confidence level for neutral Higgs boson masses of 1.0 and 1.5 TeV, respectively, where tanβ is the ratio of the vacuum expectation values of the two Higgs doublets.

Changes in markers of muscle damage, inflammation and HSP70 after an Ironman triathlon race

Abstract: We investigated the effects of an Ironman triathlon race on markers of muscle damage, inflammation and heat shock protein 70 (HSP70). Nine well-trained male triathletes (mean +/- SD age 34 +/- 5 years; VO(2peak) 66.4 ml kg(-1) min(-1)) participated in the 2004 Western Australia Ironman triathlon race (3.8 km swim, 180 km cycle, 42.2 km run). We assessed jump height, muscle strength and soreness, and collected venous blood samples 2 days before the race, within 30 min and 14-20 h after the race. Plasma samples were analysed for muscle proteins, acute phase proteins, cytokines, heat shock protein 70 (HSP70), and clinical biochemical variables related to dehydration, haemolysis, liver and renal functions. Muscular strength and jump height decreased significantly (P < 0.05) after the race, whereas muscle soreness and the plasma concentrations of muscle proteins increased. The cytokines interleukin (IL)-1 receptor antagonist, IL-6 and IL-10, and HSP70 increased markedly after the race, while IL-12p40 and granulocyte colony-stimulating factor (G-CSF) were also elevated. IL-4, IL-1beta and tumour necrosis factor-alpha did not change significantly, despite elevated C-reactive protein and serum amyloid protein A on the day after the race. Plasma creatinine, uric acid and total bilirubin concentrations and gamma-glutamyl transferase activity also changed after the race. In conclusion, despite evidence of muscle damage and an acute phase response after the race, the pro-inflammatory cytokine response was minimal and anti-inflammatory cytokines were induced. HSP70 is released into the circulation as a function of exercise duration.

Involvement of SLX4 in interstrand cross-link repair is regulated by the Fanconi anemia pathway

Abstract: Interstrand cross-links (ICLs) block replication and transcription and thus are highly cytotoxic. In higher eukaryotes, ICLs processing involves the Fanconi anemia (FA) pathway and homologous recombination. Stalled replication forks activate the eight-subunit FA core complex, which ubiquitylates FANCD2-FANCI. Once it is posttranslationally modified, this heterodimer recruits downstream members of the ICL repairosome, including the FAN1 nuclease. However, ICL processing has been shown to also involve MUS81-EME1 and XPF-ERCC1, nucleases known to interact with SLX4, a docking protein that also can bind another nuclease, SLX1. To investigate the role of SLX4 more closely, we disrupted the SLX4 gene in avian DT40 cells. SLX4 deficiency caused cell death associated with extensive chromosomal aberrations, including a significant fraction of isochromatid-type breaks, with sister chromatids broken at the same site. SLX4 thus appears to play an essential role in cell proliferation, probably by promoting the resolution of interchromatid homologous recombination intermediates. Because ubiquitylation plays a key role in the FA pathway, and because the N-terminal region of SLX4 contains a ubiquitin-binding zinc finger (UBZ) domain, we asked whether this domain is required for ICL processing. We found that SLX4−/− cells expressing UBZ-deficient SLX4 were selectively sensitive to ICL-inducing agents, and that the UBZ domain was required for interaction of SLX4 with ubiquitylated FANCD2 and for its recruitment to DNA-damage foci generated by ICL-inducing agents. Our findings thus suggest that ubiquitylated FANCD2 recruits SLX4 to DNA damage sites, where it mediates the resolution of recombination intermediates generated during the processing of ICLs.