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71.
In this Letter, we investigate the environmental dependence of dark matter halos in theories which attempt to explain the accelerated expansion of the Universe by modifying general relativity (GR). Using high-resolution N-body simulations in f(R) gravity models which recover GR in dense environments by virtue of the chameleon mechanism, we find a significant difference, which depends on the environment, between the lensing and dynamical masses of dark matter halos. This environmental dependence of the halo properties can be used as a smoking gun to test GR observationally. 相似文献
72.
Yoshinao Kumagai Yuuki Enatsu Masanari Ishizuki Yuki Kubota Jumpei Tajima Toru Nagashima Hisashi Murakami Kazuya Takada Akinori Koukitu 《Journal of Crystal Growth》2010,312(18):2530-2536
Void formation at the interface between thick AlN layers and (0 0 0 1) sapphire substrates was investigated to form a predefined separation point of the thick AlN layers for the preparation of freestanding AlN substrates by hydride vapor phase epitaxy (HVPE). By heating 50–200 nm thick intermediate AlN layers above 1400 °C in a gas flow containing H2 and NH3, voids were formed beneath the AlN layers by the decomposition reaction of sapphire with hydrogen diffusing to the interface. The volume of the sapphire decomposed at the interface increased as the temperature and time of the heat treatment was increased and as the thickness of the AlN layer decreased. Thick AlN layers subsequently grown at 1450 °C after the formation of voids beneath the intermediate AlN layer with a thickness of 100 nm or above self-separated from the sapphire substrates during post-growth cooling with the aid of voids. The 79 μm thick freestanding AlN substrate obtained using a 200 nm thick intermediate AlN layer had a flat surface with no pits, high optical transparency at wavelengths above 208.1 nm, and a dislocation density of 1.5×108 cm−2. 相似文献
73.
74.
Recently, the CDF Collaboration reports an anomaly in dijet mass distribution in association with a lepton and missing energy. We discuss a possibility that the origin of the lepton and missing energy comes not from a W boson but a new boson particle, which is also responsible for the dijet mass peak. We show that such a situation can be realized in the framework of the minimal supersymmetric standard model and the dijet anomaly can be explained. 相似文献
75.
Kazuya Tanaka Aya Sakaguchi Yutaka Kanai Haruo Tsuruta Atsushi Shinohara Yoshio Takahashi 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):1927-1937
We analyzed 137Cs in aerosols, rock, soil and river suspended sediment collected after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. Based on the results, we discuss the post-event behavior and transportation of radiocesium in the environment from the air into ground and river systems. First, radionuclides were emitted from the FDNPP as airborne ‘hot’ particles, which contained water-soluble fractions of radiocesium. Radiocesium was still present in a water-soluble fraction after deposition on the ground. Subsequent interaction of the ‘hot’ particles with water (e.g. rainfall) dissolved and strongly fixed the radiocesium on rock and soil particles, thus changing the radiocesium into insoluble forms. The distribution of ‘hot spots’ was possibly controlled by the initial position of deposition on the ground. Consequently, ‘hot spots’ were studded on the rock surface rather than being uniformly distributed. The distribution of radiocesium in river suspended particles was not homogeneous during water transportation, reflecting the heterogeneity of radiocesium in rock and soil. Leaching experiments demonstrated that radiocesium in rock, soil and river suspended sediment was fairly insoluble, showing that the adsorption reaction is irreversible. The micro-scale heterogeneous distribution of radiocesium in aerosols, soil and suspended particles was due to the presence of ‘hot’ particles in aerosols. Dissolution of radiocesium in the ‘hot’ particles in the aerosols and subsequent irreversible adsorption onto the soil particle complex are responsible for the preservation of the heterogeneity both in soil and in river suspended particles. 相似文献
76.
Synthesis and healing properties of poly(arylether sulfone)–poly(alkylthioether) multiblock copolymers containing disulfide bonds 下载免费PDF全文
Takayoshi Akiyama Akira Ushio Yoshitaka Itoh Yuya Kawaguchi Kazuya Matsumoto Mitsutoshi Jikei 《Journal of polymer science. Part A, Polymer chemistry》2017,55(21):3545-3553
Thermoplastic elastomers composed of soft and hard segments are important elastic and processable synthetic polymers. The microphase‐separated soft domains show low glass transition temperature and possess sufficient chain mobility at room temperature. In this study, we report the synthesis and healing properties of multiblock copolymers containing disulfide bonds as dynamic covalent bonds. The multiblock copolymers composed of poly(arylether sulfone) and poly(alkylthioether) segments were synthesized by oxidative coupling polymerization of the corresponding thiol‐terminated oligomers. Atomic force microscopy phase images, differential scanning calorimetry, and dynamic mechanical analysis curves indicated the microphase‐separated morphology of the multiblock copolymer. Self‐healing properties of the polymer were evaluated by changes in the elongation at break of the cut/adhered samples. The elongation recovery increased with UV irradiation time, and the multiblock copolymer showed a 93% recovery after UV irradiation for 5 h. The healing efficiency induced by UV irradiation, determined by subtracting the recovery without UV irradiation, was calculated to be 51%. According to the UV spectra and solubility changes after UV irradiation, the main healing factor in this study was the crosslinking reactions caused by thiyl radicals generated from UV irradiation instead of disulfide exchange reactions. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3545–3553 相似文献
77.
Michio Sorai Kazuya Saito Tadahiro Nakamoto Mayumi Ikeda Yuri G. Galyametdinov Irina Galyametdinova Rudolf Eidenschink Wolfgang Haase 《Liquid crystals》2003,30(7):861-869
The heat capacity of the cubic mesogen ACBC(16) was measured between 16 and 500 K by adiabatic calorimetry. As well as the known condensed phases, a new crystalline phase was found to undergo a glass transition at around 165 K. Phase transitions between crystal, SmC, cubic, and isotropic liquid phases took place at 399.16, 431.15, and 474.30 K, respectively. As in the case of ANBC, a broad hump was observed in the heat capacity of the isotropic liquid phase. The first order nature of the SmC-cubic phase transition was confirmed for the first time by the observation of supercooling of the cubic phase. The broad hump in the isotropic liquid phase was shown to extend to a low temperature side if the isotropic liquid was supercooled, suggesting that the event occurring at the hump is not directly related to the cubic-isotropic liquid phase transition. 相似文献
78.
Kazuya Hayata 《Optical Review》1997,4(2):303-304
It is shown that, at a critical point where the effective refractive index of a mode coincides with the bulk index of a cladding region, optical waveguide modes exhibiting a lognormal feature are supportable for a hyperlongrange refractive-index profile. As a typical example of waveguides that support lognormal modes a parabolic-index core surrounded by a depressed-index cladding is presented. 相似文献
79.
Dr. Yasuhide Akizuki Dr. Ikuya Yamada Dr. Koji Fujita Kazuya Taga Dr. Takateru Kawakami Dr. Masaichiro Mizumaki Prof. Katsuhisa Tanaka 《Angewandte Chemie (International ed. in English)》2015,54(37):10870-10874
Of particular interest is a peculiar motion of guest atoms or ions confined to nanospace in cage compounds, called rattling. While rattling provides unexplored physical properties through the guest–host interactions, it has only been observed in a very limited class of materials. Herein, we introduce an A‐site‐ordered quadruple perovskite, CuCu3V4O12, as a new family of cage compounds. This novel AA′3B4O12‐type perovskite has been obtained by a high‐pressure synthesis technique and structurally characterized to have cubic Im$\bar 3$ symmetry with an ionic model of Cu2+Cu2+3V4+4O12. The thermal displacement parameter of the A‐site Cu2+ ion is as large as Uiso≈0.045 Å2 at 300 K, indicating its large‐amplitude thermal oscillations in the oversized icosahedral cages. Remarkably, the presence of localized phonon modes associated with rattling of the A‐site Cu2+ ion manifests itself in the low‐temperature specific heat data. This work sheds new light on the structure–property relations in perovskites. 相似文献
80.
Dr. Shinichiro Fuse Ayako Ikebe Kazuya Oosumi Tomoya Karasawa Keisuke Matsumura Dr. Miho Izumikawa Dr. Kohei Johmoto Dr. Hidehiro Uekusa Dr. Kazuo Shin‐ya Prof. Takayuki Doi Prof. Takashi Takahashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(26):9454-9460
An asymmetric total synthesis of ent‐pyripyropene A was achieved by a convergent synthetic route. We used our originally developed TiIII‐catalyzed radical cyclization to construct an AB‐ring portion that consisted of a trans‐decalin skeleton with five contiguous stereogenic centers. The coupling between the AB‐ring and the DE‐ring portions, and a subsequent C‐ring cyclization, led to the total synthesis of ent‐pyripyropene A. An evaluation of the insecticidal activity of ent‐pyripyropene A against two aphid species revealed that ent‐pyripyropene A was 35–175 times less active than naturally occurring pyripyropene A. This result indicated that the biological target of pyripyropene A recognizes the absolute configuration of pyripyropene A. 相似文献