University of Electro-Communications

About: University of Electro-Communications is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Laser & Robot. The organization has 8041 authors who have published 16950 publications receiving 235832 citations. The organization is also known as: UEC & Denki-Tsūshin Daigaku.

Carbonato-bridged Ni(II)2Ln(III)2 (Ln(III) = Gd(III), Tb(III), Dy(III)) complexes generated by atmospheric CO2 fixation and their single-molecule-magnet behavior: [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(MeOH or H2O)Ln(III)(NO3)}2]·solvent [3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato].

Abstract: Atmospheric CO2 fixation of [Ni(II)(3-MeOsaltn)(H2O)2]·2.5H2O [3-MeOsaltn = N,N'-bis(3-methoxy-2-oxybenzylidene)-1,3-propanediaminato], Ln(III)(NO3)3·6H2O, and triethylamine occurred in methanol/acetone, giving a first series of carbonato-bridged Ni(II)2Ln(III)2 complexes [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(MeOH)Ln(III)(NO3)}2] (1Gd, 1Tb, and 1Dy). When the reaction was carried out in acetonitrile/water, it gave a second series of complexes [(μ4-CO3)2{Ni(II)(3-MeOsaltn)(H2O)Ln(III)(NO3)}2]·2CH3CN·2H2O (2Gd, 2Tb, and 2Dy). For both series, each Ni(II)2Ln(III)2 structure can be described as two di-μ-phenoxo-bridged Ni(II)Ln(III) binuclear units bridged by two carbonato CO3(2-) units to form a carbonato-bridged (μ4-CO3)2{Ni(II)2Ln(III)2} structure. The high-spin Ni(II) ion has octahedral coordination geometry, and the Ln(III) ion is coordinated by O9 donor atoms from Ni(II)(3-MeOsaltn), bidentate NO3(-), and one and two oxygen atoms of two CO3(2-) ions. The NO3(-) ion for the first series roughly lie on Ln-O(methoxy) bonds and are tilted toward the outside, while for the second series, the two oxygen atoms roughly lie on one of the Ln-O(phenoxy) bonds due to the intramolecular hydrogen bond. The temperature-dependent magnetic susceptibilities indicated a ferromagnetic interaction between the Ni(II) and Ln(III) ions (Ln(III) = Gd(III), Tb(III), Dy(III)) for all of the complexes, with a distinctly different magnetic behavior between the two series in the lowest-temperature region due to the Ln(III)-Ln(III) magnetic interaction and/or different magnetic anisotropies of the Tb(III) or Dy(III) ion. Alternating-current susceptibility measurements under the 0 and 1000 Oe direct-current (dc) bias fields showed no magnetic relaxation for the Ni(II)2Gd(III)2 complexes but exhibited an out-of-phase signal for Ni(II)2Tb(III)2 and Ni(II)2Dy(III)2, indicative of slow relaxation of magnetization. The energy barriers, Δ/kB, for the spin flipping were estimated from the Arrhenius plot to be 12.2(7) and 6.1(3) K for 1Tb and 2Tb, respectively, and 18.1(6) and 14.5(4) K for 1Dy and 2Dy, respectively, under a dc bias field of 1000 Oe. Compound 1Dy showed relatively slow relaxation of magnetization reorientation even at zero dc applied field with Δ/kB = 6.6(4) K.

Kinetics in Surface Reconstructions on GaAs(001)

Abstract: We have successfully controlled the surface structures of GaAs(001) by changing incident As-molecular species. Under ${\mathrm{As}}_{4}$ fluxes, the $c(4\ifmmode\times\else\texttimes\fi{}4)$ reconstruction with Ga-As dimers [$c(4\ifmmode\times\else\texttimes\fi{}4)\ensuremath{\alpha}$ structure] is obtained, but the formation of three As-As dimer structures [$c(4\ifmmode\times\else\texttimes\fi{}4)\ensuremath{\beta}$ structure] is kinetically limited. On the other hand, the structure change from the $(2\ifmmode\times\else\texttimes\fi{}4)$, through $c(4\ifmmode\times\else\texttimes\fi{}4)\ensuremath{\alpha}$, to $c(4\ifmmode\times\else\texttimes\fi{}4)\ensuremath{\beta}$ phases is observed under ${\mathrm{As}}_{2}$ fluxes. We found that the $c(4\ifmmode\times\else\texttimes\fi{}4)\ensuremath{\alpha}$ structure is energetically metastable and provides a kinetic pathway for the structure change between the $(2\ifmmode\times\else\texttimes\fi{}4)$ and $c(4\ifmmode\times\else\texttimes\fi{}4)\ensuremath{\beta}$ phases under ${\mathrm{As}}_{2}$ fluxes.

Grain refinement in coarse-grained 7475 Al alloy during severe hot forging

Abstract: Grain refinement taking place in a coarse-grained 7475 Al alloy was studied in multidirectional compression at 490°C and at a strain rate of 3 × 10−4 s−1. The integrated flow curve displays significant work softening just after yielding and an apparent steady-state plastic flow at high strains. The structural changes are characterized by the development of deformation or microshear bands in coarse-grain interiors, followed by homogeneous evolution of new grains at high strains. The new grains are considered to be developed by a kind of continuous reaction through grain fragmentation that is similar to continuous dynamic recrystallization (cDRX). The mechanism of fine grain production and the factors controlling grain refinement during hot multidirectional deformation are discussed in detail.

Visualizing cyber attacks using IP matrix

Abstract: An Internet cyber threat monitoring system detects cyber threats using network sensors deployed at particular points on the Internet, statistically analyzes the time of attack, source of attack, and type of attack, and then visualizes the result of this analysis. Existing systems, however, simply visualize country-by-country statistics of attacks or hourly changes of attacks. Using these systems, it is difficult to understand the source of attack, the diffusion of the attack, or the relation between the target and the source of the attack. This paper described a method for visualizing cyber threats by using 2-dimensional matrix representation of IP addresses. The advantages of this method are that: (1) the logical distance of IP addresses is represented intuitively; (2) Internet address space is visualized economically; (3) macroscopic information (Internet level) and microscopic information (local level) are visualized simultaneously. By using this visualization framework, propagation of the Welchia worm and the Sasser.D worm are visualized.

Evidence for Strong Breit Interaction in Dielectronic Recombination of Highly Charged Heavy Ions

Abstract: Resonant strengths have been measured for dielectronic recombination of Li-like iodine, holmium, and bismuth using an electron beam ion trap. By observing the atomic number dependence of the state-resolved resonant strength, clear experimental evidence has been obtained that the importance of the generalized Breit interaction (GBI) effect on dielectronic recombination increases as the atomic number increases. In particular, it has been shown that the GBI effect is exceptionally strong for the recombination through the resonant state [1s2s{sup 2}2p{sub 1/2}]{sub 1}.