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Research at OU


19  Amaya, T.; Mori, K. ; Wu, H.-L.; Ishida, S. ; Nakamura, J. ; Murata, K.; Hirao, T.
(Graduate School of Engineering)
Synthesis and Characterization of π-Extended Bowl-Shaped π-Conjugated Molecules
Chemical Communications, 1902-1904 (2007)

A synthetic route to π-extended bowl-shaped π-conjugated molecules was developed by using sumanene, a C3v symmetrical partial structure of buckminsterfullerene C60. Various π-bowls were synthesized and characterized, and among them the terthiophene derivative showed a remarkable red-shifted absorption and small band gap, which was rationalized by molecular orbital calculation. Such unique π-bowl systems are expected to be applied to organic electronic materials.

20 Arakawa, K.; Hatanaka, M.; Kuramoto, E.; Ono, K.; Mori, H.
(Research Center for Ultra-High Voltage Electron Microscopy)
Change in the Burgers Vector of Perfect Dislocation Loops without Contact with External Dislocations
Physical Review Letters, 96, 125506/1-4 (2006)

21 Asuha,; Im; S.-S. Tanaka, M.; Imai, S.; Takahashi, M.; Kobayashi, H.
(Institute of Scientific and Industrial Research)
Formation of 10—30 nm SiO2/Si Structure with a Uniform Thickness
at ~120°C by Nitric Acid Oxidation Method

Surface Science, 600, 2523-2527 (2006)

Silicon dioxide (SiO2) layers with a thickness more than 10 nm can be formed at ~120°C by direct Si oxidation with nitric acid. The nitric acid oxidation rates are the same for (111) and (100) orientations. The oxidation rate is constant up to 15 nm, indicating that the interfacial reaction is the rate-determining step. SiO2 layers with a uniform thickness are formed even on a rough surface of poly-Si thin films, and thus this technology is applicable to TFT.

22 Chen, W.; Kirihara, S.; Miyamoto, Y.
(Joining and Welding Research Institute)
Fabrication of Three-Dimensional Micro Photonic Crystals of Resin-Incorporating TiO2 Particles and their Terahertz Wave Properties
Journal of American Ceramic Society, 90, 92-96 (2007)

23 Cui, L.*1; Fujii, H.*1; Tsuji N.*2; Nogi, K.*1
*1(Joining and Welding Research Institute)
*2(Graduate School of Engineering)
Friction Stir Welding of a High Carbon Steel
Scripta Materialia, 56, 637-640 (2007)

A high carbon steel joint, S70C (0.72wt%C) was successfully friction stir welded without any preheat or postheat treatments. There are two methods for obtaining proper joint properties. The first method is to decrease the peak temperature to below A1, and the other method to decrease the cooling rate to less than the lower critical cooling rate. It was proved that friction stir welding enables us to properly control the cooling rate and peak temperature, which was impossible using traditional welding.

24 Hagihara, K.; Tanaka, T.; Fujimoto. H.; Nakano, T.; Umakoshi, Y.
(Graduate School of Engineering)
Microstructure and Plastic Deformation Behavior of Ni3(Ti, X) (X=Nb, Al) Single Crystals with Long-period Geometrically Closely Packed Crystal Structures
Intermetallics, 14, 1332-1338 (2006)

Relation between the crystal structure and plastic deformation behavior was investigated in Ni3(Ti1-xNbx) [x=0~0.10] and Ni3(Ti1-yAly) [y=0.16 or 0.28] single crystals. The substitution of Ti by Nb in Ni3Ti induced the formation of various long-period stacking ordered structures with different stacking sequences. Yield stress anomaly (YSA) appeared as well as in binary Ni3Ti by slip on the common close-packed plane. However it was clarified the change in stacking sequence strongly affects the peak stress of YSA due to the change in anti-phase boundary energy.

25 Hanasaki, I.; Nakatani, A.
(Graduate School of Engineering)
Flow Structure of Water in Carbon Nanotubes: Poiseuille Type or Plug-like?
The Journal of Chemical Physics, 124, 144708-1-9 (2006)

We investigated the water-molecule flow in carbon nanotubes (CNTs) using molecular dynamics method, and found that it has characteristics qualitatively different from macroscopic fluid flow having parabolic velocity profile. The water flow in the CNTs is not of Poiseuille nature, but it is more like plug flow that has flat streaming velocity profile. Using hydrogen bond lifetime as a measure, we have also shown that the structural robustness of collective structure of water molecules in the CNTs does not decrease from equilibrium state.

26 Hara, T.; Madria, S.K.
(Graduate School of Information Science and Technology)
Data Replication for Improving Data Accessibility in Ad Hoc Networks
IEEE Transactions on Mobile Computing, 5, 1515-1532 (2006)

27 Hashimoto,S.; Murayama, S.; Sugahara, T.; Sato, H.; Ohgaki,K.
(Graduate School of Engineering Science)
Thermodynamic and Raman Spectroscopic Studies on H2 + Tetrahydrofuran + Water and H2 + Tetra-n-Butyl Ammonium Bromide + Water Mixtures Containing Gas Hydrates
Chemical Engineering Science, 61, 7884-7888, (2006)

We have firstly reported that tetra-n-butyl ammonium bromide(TBAB) hydrate can be utilized as the H2 storage medium. Thermodynamic stabilities and Raman spectra for the H2 + tetrahydrofuran and H2 + TBAB mixed gas hydrates were measured. The equilibrium curve of H2 + TBAB mixed gas hydrates shifts to the 8 K higher-temperature side than that of H2 + tetrahydrofuran mixed gas hydrate. Raman spectra reveal that H2 molecule is enclathrated in only small hydrate-cage of both systems.

28 Hirai, H.; Miyazaki F.
(Graduate School of Engineering Science)
Dynamic Coordination Between Robots: The Self-organized Timing Selection in a Juggling-like Ball Passing Task
IEEE Transactions on Systems, Man, and Cybernetics-PART B: Cybernetics, 36, 738-754 (2006)

This paper describes the hierarchical architecture for a rhythmic coordination between robots, which suits juggling-like tasks involving sensory-motor coordination. The proposed architecture contains two passive-control mechanisms, the “open-loop stable mechanism” and the “entrainment mechanism,” which lead to the self-organized temporal structure of rhythmic movement. Two robots are capable of passing two balls, performing synchronous motion emerging as behavioural attractors between the environment and robots. Some experimental results reveal that the proposed dynamics-based approach is useful not only for adaptive coordinated motion between robots but also for emergence of inter-agent coordination.

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