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111.
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
112.
Hironori Ohashi Hiroyuki Ezoe Yoshihiro Okaue Yasuhiro Kobayashi Shuji Matsuo Tsutomu Kurisaki Akane Miyazaki Hisanobu Wakita Takushi Yokoyama 《Analytical sciences》2005,21(7):789-793
The effect of UV (ultraviolet) irradiation on the adsorption of Au(III) ions on manganese dioxide and their reduction to Au(0) (gold with 0 valence state) was investigated using XPS (X-ray photoelectron spectroscopy) and 197Au M?ssbauer spectroscopy. The UV irradiation accelerated the adsorption and the reduction. From the fact that the proportion of Au(0) estimated from Au 4f XPS spectra for surface analysis was significantly smaller than that from 197Au M?ssbauer spectra for bulk analysis, we deduced that Au(0) was interpenetrated to the inside of manganese dioxide (into deeper places than about 30 A) where XPS is impossible to detect. The content of surface hydroxyl groups on manganese dioxide also increased due to the UV irradiation. The relationship between the charge in the content of hydroxyl groups and the interpenetration of Au(0) is discussed. 相似文献
113.
Tomoaki Matsugi Shin‐Ichi Kojoh Nobuo Kawahara Shingo Matsuo Hideyuki Kaneko Norio Kashiwa 《Journal of polymer science. Part A, Polymer chemistry》2003,41(24):3965-3973
Polyethylene‐block‐poly(methyl methacrylate) (PE‐b‐PMMA) was successfully synthesized through the combination of metallocene catalysis with living radical polymerization. Terminally hydroxylated polyethylene, prepared by ethylene/allyl alcohol copolymerization with a specific zirconium metallocene/methylaluminoxane/triethylaluminum catalyst system, was treated with 2‐bromoisobutyryl bromide to produce terminally esterified polyethylene (PE‐Br). With the resulting PE‐Br as an initiator for transition‐metal‐mediated living radical polymerization, methyl methacrylate polymerization was subsequently performed with CuBr or RuCl2(PPh3)3 as a catalyst. Then, PE‐b‐PMMA block copolymers of different poly(methyl methacrylate) (PMMA) contents were prepared. Transmission electron microscopy of the obtained block copolymers revealed unique morphological features that depended on the content of the PMMA segment. The block copolymer possessing 75 wt % PMMA contained 50–100‐nm spherical polyethylene lamellae uniformly dispersed in the PMMA matrix. Moreover, the PE‐b‐PMMA block copolymers effectively compatibilized homopolyethylene and homo‐PMMA at a nanometer level. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3965–3973, 2003 相似文献
114.
Koji Matsuo 《Annals of Global Analysis and Geometry》1995,13(1):43-54
We introduce the notion of a locally conformally Hermitian-flat manifold and derive a necessary and sufficient condition for a Hermitian manifold to be locally conformally Hermitian-flat. In addition, we construct a family of examples. 相似文献
115.
Systematic synthesis of high-mannose-type sugar chains of asparagine-linked glycoproteins is described. To construct the target sugar chains, we employed the convergent route, using three oligosaccharide components, the common hexasaccharide, branched tri-, tetra- and pentasaccharides, and mono-, di-, and triglucosyl fragments. Construction of the β-mannoside linkage was performed using p-methoxybenzyl-assisted intramolecular aglycon delivery. The hexasaccharide fragment was coupled with the branched mannooligosaccharide donors such as M5, M4B, M4C, and M3 to give undecasaccharide (M9), decasaccharide (M8B and M8C), and nonasaccharide (M7), respectively. Incorporation of mono-, di-, and triglucosyl fragments toward them gave tetradecasaccharide (G3M9), tridecasaccharide (G2M9), dodecasaccharide (G1M9), undecasaccharide (G1M8B and G1M8C), and decasaccharide (G1M7), respectively. 相似文献
116.
The present numerical study has dealt with the enhancement of latent heat Release by using plate type fins mounted on the vertical cooling surface in the rectangular vessel packed with molten salt as a latent heat storage material. It was found that the fin thickness and pitch exerted an influence on solidification heat transfer in a liquid layer of a nitric molten salt. The numerical results elucidated the flow pattern, velocity profile and heat transfer rate in the melted liquid layer. 相似文献
117.
Dr. Aya Yoshimura Yuki Takamachi Prof. Dr. Li‐Biao Han Prof. Dr. Akiya Ogawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(40):13930-13933
An efficient metal‐free diboration of terminal alkynes is reported. In the presence of a catalytic amount of organosulfides under light, the addition of bis(pinacolato)diboron (B2pin2) to terminal alkynes takes place efficiently to produce the corresponding double borylation products in good yields. Mechanistic studies indicate that this metal‐free sulfide‐catalyzed diboration of alkynes likely occurs by generation of a boryl‐centered radical with the aid of light and a sulfide, since such a radical was detected in the reaction mixture by electron spin resonance (ESR) spectroscopy. The present form of catalysis (sulfide/light) is thought to be unprecedented and provides a new means of preparation for organoboranes without heavy metal contamination in the products, which is highly desired in the preparation of drugs and electronic materials. 相似文献
118.
Aya Yoshimura Akihiro Nomoto Mari Uchida Hiroki Kusano Tomokazu Saeki Akiya Ogawa 《Research on Chemical Intermediates》2017,43(6):3433-3443
The functionalization of polysilanes is an important subject in materials science because functionalized polysilanes are expected to exhibit potentially innovative properties. This research aims at the addition of a water-shedding property to polysilanes by introducing perfluoroalkyl groups into their skeleton. The photoinduced iodoperfluoroalkylation of various vinylsilanes takes place successfully upon irradiation with a xenon lamp: vinylmonosilanes undergo iodoperfluoroalkylation with perfluoroalkyl iodides (RfI) regioselectively, and the corresponding perfluoroalkylated silanes are obtained in moderate to high yields. Detailed optimization of the photoinduced iodoperfluoroalkylation has been investigated to apply this method to the functionalization of polysilanes. Polysilanes having vinyl groups can be synthesized by the reductive coupling of dichlorovinylsilanes with samarium diiodide (SmI2) and samarium metal (Sm) upon irradiation with visible light. The synthesized vinylpolysilanes and RfI (about 1.0 mM CHCl3 solution) are coated on a glass plate sequentially, and then the following photoirradiation with light of a wavelength over 300 nm successfully adds an excellent water-shedding property to the glass plate. 相似文献
119.
A great number of experimental data indicating shock wave/boundary layer interactions in internal or external supersonic flows
were reviewed to make clear the mechanism of the interaction and to decide the onset of shock-induced separation. The interesting
conclusions were obtained for the considerably wide range of flow geometries that the onset of separation is independent of
the flow geometries and the boundary layer Reynolds number. It is found that the pressure rise necessary to separate the boundary
layer in supersonic external flows could be applied to such internal flows as overexpanded nozzles or diffusers. This is due
to the fact that the separation phenomenon caused by shock wave/boundary layer interactions is processed through a supersonic
deceleration. The shock-induced separation in almost all of interacting flow fields is governed by the concept of free interaction,
and the onset of shock-induced separation is only a function of the Mach number just upstream of shock wave. However, physical
scales of the produced separation are not independent of the downstream flow fields. 相似文献