Development of Broadband Telecommunications System for Railways Using Laser Technology

We developed a high‐speed telecommunication system for use on railways to improve customer service and the efficiency of operator's telecommunications between ground facilities and trains under operation. We built a mobile telecommunication system, capable of achieving a transfer rate of 1 Gbps in theory, by utilizing laser beam communications technology. We carried out a field test using trains in active service, and obtained results in which a transfer rate of approximately 700 Mbps in the TCP layer was achieved between the ground and a train running at a speed of approximately 130 km/h .     

Computer simulation studies on overlapping polymer chains confined in narrow channels

Conformation of polymer chains strongly confined in a narrow channel space was studied over a broad range of polymer volume fractions φ using lattice Monte Carlo simulations. The longitudinal component of the chain dimension decreased in a power law of ∼φ⁻¹ as φ exceeded the overlap volume fraction. The conformation changed from the one extended along the channel to a random coil. The change occurred without much overlap between adjacent chains. As the conformational transition was completed, the chains started to penetrate each other. Contraction of the chains became more gradual, and eventually the longitudinal component of the chain dimension approached that of the unconfined chains with the overall chain dimension being smaller than that of the unconfined chains. Predictions of the scaling theory were thus confirmed with additional detailed information on the state of confined chains in each regime of characteristic φ dependence of chain dimensions.     

Fundamental study of adhesion of ice to cooling solid surface (Discussion on influence of copper oxide layer on ice adhesion force)

In many situations, ice often adheres to a cooling solid surface, frequently causing serious accidents. It is critical to clarify the mechanism of ice adhesion to the cooling surface in order to prevent ice adhesion. In a past study, the shearing stresses of two kinds of test plates with a copper surface having the higher thermal conductivity were measured. The shearing stress corresponds to ice adhesion force. Both shearing stresses were significantly different; however, the cause remains unclear.Therefore, the present study focuses on an oxide layer as the main factor causing the difference of both shearing stresses; the influence of the oxide layer formed on shearing stress was discussed. And in the removal and reformation processes of the oxide layer, the time variation of the shearing stress was clarified. Moreover, the relationship between the state of the copper surface and the shearing stress was also clarified by surface analysis.     

Low confinement loss hybrid-guiding tellurite photonic bandgap fiber

A hybrid-guiding tellurite (TZNLP) photonic bandgap fiber (PBGF) with low confinement loss is presented in this paper. A detailed comparison between the hybrid-guiding tellurite PBGF in which the high-index rods (TLWMN) replace one row of air holes in the radial direction and the all-solid tellurite PBGF has been accomplished. Low confinement loss windows can be achieved in this novel fiber due to the collaborated action of two guiding mechanisms–total internal reflection and antiresonant reflection.     

Inhibitory effects of caffeine on Ca2+ influx and histamine secretion independent of cAMP in rat peritoneal mast cells

Cleavage of tubulin at tryptophan residues yielded several peptides, one of which strongly interacted with aldolase as determined by inhibition of aldolase activity. This peptide was identified as the C-terminal, residues 408-451, of the alpha-subunit of tubulin. Peptides with identical sequences to the C-terminal regions of the alpha- and beta-subunits of tubulin were synthesized to further characterize interactions with glycolytic enzymes. A 43-amino-acid C-terminal peptide from alpha-tubulin (residues 409-451) was found to have binding properties similar to those of native tubulin and was designated the tubulin glycolytic enzyme binding domain (T-GEBD-43mer).     

Partitioning of polymer chains in solution with a square channel: lattice Monte Carlo simulations

Cubic lattice Monte Carlo simulation studies were conducted to examine the effect of confinement on dilute and non-dilute solutions of polymer chains in a channel with a square cross section. In dilute solutions, the partition coefficient K_c with channels of different widths d followed the scaling-law prediction, and was close to the square of the partition coefficient K_s with a slit of the same d. The chain with its bulk radius of gyration greater than ∼d/2 adopted a conformation extending along the channel and, with a decreasing channel width, the chain ends were forced to face outside. The chain conformation in broader channels was a compressed random coil. The K_c increased with an increasing polymer concentration φ_E in the exterior solution equilibrated with the channel. In a weak confinement, K_c closely followed K_s² of the same φ_E and d. The chains contracted at higher concentrations as they did in the bulk solutions. In a strong confinement, K_c was smaller than K_s² at the same φ_E in the semidilute regime, and, at higher concentrations, sharply increased to the value close to K_s².     

Promotion effect of residual K on the decomposition of N2O over cobalt–cerium mixed oxide catalyst

A series of cobalt–cerium mixed oxide catalysts (Co₃O₄–CeO₂) with a Ce/Co molar ratio of 0.05 were prepared by co-precipitation (with K₂CO₃ and KOH as the respective precipitant), impregnation, citrate, and direct evaporation methods and then tested for the catalytic decomposition of N₂O. XRD, BET, XPS, O₂-TPD and H₂-TPR methods were used to characterize the catalysts. Catalysts with a trace amount of residual K exhibited higher catalytic activities than those without. The presence of appropriate amount of K in Co₃O₄–CeO₂ may improve the redox property of Co₃O₄, which is important for the decomposition of N₂O. When the amount of K was constant, the surface area became the most important factor for the reaction. The co-precipitation-prepared catalyst with K₂CO₃ as precipitant exhibited the best catalytic performance because of the presence of ca. 2 mol% residual K and the high surface area. We also discussed the rate-determining step of the N₂O decomposition reaction over these Co₃O₄–CeO₂ catalysts.