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1.
H. Sakaue H. Fujimaki S. Tonouchi S. Itou T. Hashimoto 《Journal of Radioanalytical and Nuclear Chemistry》2007,274(3):449-454
A portable system for high-speed time interval analysis (TIA) method was constructed. The system installed with an original
time counting board could record pulse incident time of 1 MHz precisely. During the measurement, calculation of time intervals
for all the pulses and on-line display of the results were performed simultaneously. Using this system, the correlated decay
events of 214Bi to 210Po in the airborne dust collected on filter paper were counted, together with a dual-phosphor type alpha/beta detector. A
rapidly detective technique of artificial radioactivity under the variations of naturally occurring radioactivities is discussed. 相似文献
2.
H. A. Sakaue T. Negishi Y. Seki T. Takayanagi K. Wakiya F. Koike H. Suzuki 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,25(2):157-160
Ejected-electron spectra have been measured for collisions of He-atoms with Na+-ions, whose impact energy ranged from 1.7 to 7.0 keV. The ion impact-energy dependence of the angular-differential cross-section of the ejected electrons has been investigated for an aligned autoionizing state Na**(2p 5 3s 2 2 P), which has been created by charge transfer from the He-atoms. The alignment of the autoionizing state Na**(2p 5 3s 2 2 P) is discussed in relation to the scattering angles of the Na+-ions. A complete longitudinal alignment has been observed with respect to the quasimolecular axis. 相似文献
3.
Oki Michinori Toyofuku Yoshitaka Sakaue Tatsuya Hirose Takanori Asakura Mitsuhiro Morita Nobuhiro Toyota Shinji 《Russian Journal of Organic Chemistry》2003,39(4):542-553
X-ray crystallography of the ap-form of the 1-(9-fluorenyl)-2-(2-methyl-2-oxiranyl)naphthalene has revealed that the carbon atom of the oxirane which is connected to the naphthyl group in this compound is almost planar. The specific structural features of the epoxy ring in this compound are caused by sterical effects and by the presence of a -system in the immediate vicinity of the oxirane ring. Certain differences have been found also in reactivity of rotational isomers of 2-X-substituted 1-[1-(9-fluorenyl)-2-naphthyl]ethyl cations (X = O, S, Se). At X = O arose more deprotonation product from the -position of the oxygen than in reactions of sulfur and selenium-containing analogs. Reactions of epoxides with zinc chloride almost exclusively gave the corresponding aldehydes. 相似文献
4.
We studied the stability and dynamics of a model of a nucleosome, the fundamental unit for the packing of long DNA in eukaryotes, using a Brownian dynamics simulation. For the proper folding of a stiff polymer on a core particle, moderate attractive interaction is shown to be essentially important, which explains the empirical experimental protocol for the reconstitution of nucleosomes. The effect of the chain end on the positioning of the core particle is examined and compared with the experimental data by atomic force microscopy measurement. It is also suggested that the core particle exhibits sliding motion along the chain as a manifestation of Brownian motion. 相似文献
5.
Sakaue T 《Physical review letters》2011,106(16):167802
We propose a simple mean-field theory for the structure of ring polymer melts. By combining the notion of topological volume fraction and a classical van der Waals theory of fluids, we take into account many-body effects of topological origin in dense systems. We predict that although the compact statistics with the Flory exponent ν=1/3 is realized for very long chains, most practical cases fall into the crossover regime with the apparent exponent ν?2/5 during which the system evolves toward a topological dense-packed limit. 相似文献
6.
By analyzing the real space non-equilibrium dynamics of polymers, we elucidate the physics of driven translocation and propose
its dynamical scaling scenario analogous to that in the surface growth phenomena. We provide a detailed account of the previously
proposed tension-propagation formulation and extend it to cover the broader parameter space relevant to real experiments.
In addition to a near-equilibrium regime, we identify three distinct non-equilibrium regimes reflecting the steady-state property
of a dragged polymer with finite extensibility. Finite-size effects are also pointed out. These elements are shown to be crucial
for the appropriate comparison with experiments and simulations. 相似文献
7.
High-speed holographic microscopy is applied to take three successive photographs of fast propagating cracks in Homalite 100 or in Araldite B at the moment of bifurcation. Crack speed at bifurcation is about 540 m/s on Homalite 100, and about 450 m/s on Araldite B. From the photographs, crack speeds immediately before and after bifurcation are obtained, and it is found that discontinuous change of crack speed does not exist at the moment of bifurcation in the case of Homalite 100, but exists in the case of Araldite B. From the photographs, crack opening displacement (COD) is also measured along the cracks as a function of distance r from the crack tips. The measurement results show that the CODs are proportional to √r before bifurcation. After bifurcation, the CODs of mother cracks are proportional to √r, though the CODs of branch cracks are not always proportional to √r. The energy release rate is obtained from the measured CODs, and it is found that energy release rate is continuous at bifurcation point in both cases of Homalite 100 and Araldite B. Energy flux that shows the energy flow toward a crack tip is also obtained. 相似文献
8.
Using fluorescence microscopy (FM), which permits the observation of single molecules, we found that a pearling structure is generated on a single long DNA molecule upon the addition of a gemini (dimeric) surfactant. This pearling structure was further investigated by performing atomic force microscopy measurements on the same DNA molecules as observed by FM. These observations revealed that the pearling structure is composed of many rings that are interconnected by elongated coil parts along a single DNA molecule, i.e., rings-on-a-string structure. The mechanism of the formation of such an intrachain segregated structure in terms of microphase separation on a single polyelectrolyte chain is discussed. 相似文献
9.
Naofumi Nishida Yuki Hori Akane Yamauchi Hazuki Fujiwara Makoto Sakurai Yuya Fujiwara Shin-ichi Honda Shunjiro Fujii Hiroyuki A. Sakaue Daiji Kato Tomohiro Yamaguchi Koji Ishibashi Toshifumi Terui Kuei-Yi Lee 《X射线光谱测定》2020,49(1):99-103
Interaction of highly charged ions (HCIs) with surfaces produce various specific phenomena as a consequence of the potential energy that HCI possesses. In the present study, we have observed photon emission, structural, magnetic, and electronic modification on various carbon-based materials such as carbon nanotube by the impact of HCIs using an electron beam ion source named Kobe EBIS installed at the Kobe University. In order to study the potential effect, HCIs of Arq+ (q = 6–16) with the intensity of 0.1–1 nA are projected on the surface with a constant kinetic energy (16 keV). For photon emission measurements, we observed spatial and spectral distribution of visible light emission from the surface during irradiation with HCIs. On the other hand, the structural modification of multi-walled carbon nanotubes (MWCNTs) irradiated with HCIs has been analyzed using a transmission electron microscopy and Raman spectroscopy. Irradiation effects on the resistivity of single MWCNT supported on micrometer scale bridge pattern were also measured. We have also measured magnetic structure of highly oriented pyrolytic graphite irradiated with HCIs using electron spin resonance at low temperature. At the present paper, we will review our recent experimental results on the interaction of HCI with various carbon-based materials. 相似文献
10.
Naofumi Nishida Yuuki Hori Akane Yamauchi Makoto Sakurai Hiroyuki A. Sakaue Daiji Kato 《X射线光谱测定》2020,49(1):74-77
The electron beam ion source (Kobe EBIS) has been developed to perform modification of surfaces using highly charged ions (HCIs) at the Kobe University, Japan. Recent study revealed that periodic intermission of electron beam improves charge state distribution of extracted ions. The period of intermission is in the order of 100 ms, and the width of beam-off time is 1 ms or less. This operational mode (pulse mode) makes it possible to produce Ar15+ to Ar17+ effectively, whereas the charge is limited less than 14+ under the ordinary operational mode with direct current (DC) electron beam. A spike of HCIs with a peak current in the order of nA is also observed at each moment of electron beam off. The measurement of the time evolution of Ar16+ intensity around the timing of mode change revealed that the intensity of extracted Ar16+ changes slowly after mode change with a time constant of few seconds. 相似文献