WTC2005-64346 RAIL CORRUGATIONS CAUSED BY LOW COEFFICIENT OF FRICTION IN A SUBMARINE RAILWAY TUNNEL

ABSTRACT One of some types of rail corrugations is caused on railway rail surface in a submarine tunnel. It poses a large problem from the aspects of railway vehicle and railway track deterioration. In this paper, the mechanism of the rail corrugations was studied with the focus placed on roll-slip of wheel and rail interface. Traction and vertical force interacting between wheel and rail were investigated by a vehicle/track interaction model, and the coefficient of friction (COF) on rail surface was measured. Also, the rail surface was analysed with infrared to understand the chemical composition of surface layer influenced by salty and very humid atmosphere in the submarine tunnel. ß-FeOOH was found out as a cause of reducing COF on rail surface

WTC2005-64346 RAIL CORRUGATIONS CAUSED BY LOW COEFFICIENT OF FRICTION IN A SUBMARINE RAILWAY TUNNEL

ABSTRACT One of some types of rail corrugations is caused on railway rail surface in a submarine tunnel. It poses a large problem from the aspects of railway vehicle and railway track deterioration. In this paper, the mechanism of the rail corrugations was studied with the focus placed on roll-slip of wheel and rail interface. Traction and vertical force interacting between wheel and rail were investigated by a vehicle/track interaction model, and the coefficient of friction (COF) on rail surface was measured. Also, the rail surface was analysed with infrared to understand the chemical composition of surface layer influenced by salty and very humid atmosphere in the submarine tunnel. ß-FeOOH was found out as a cause of reducing COF on rail surface

Conformational alterations in unidirectional ion transport of a light-driven chloride pump revealed using X-ray free electron lasers

光でイオンを輸送する膜タンパク質の巧妙な仕組み --XFELが捉えた光駆動型イオンポンプロドプシンの構造変化--. 京都大学プレスリリース. 2022-02-28.Light-driven chloride-pumping rhodopsins actively transport anions, including various halide ions, across cell membranes. Recent studies using time-resolved serial femtosecond crystallography (TR-SFX) have uncovered the structural changes and ion transfer mechanisms in light-driven cation-pumping rhodopsins. However, the mechanism by which the conformational changes pump an anion to achieve unidirectional ion transport, from the extracellular side to the cytoplasmic side, in anion-pumping rhodopsins remains enigmatic. We have collected TR-SFX data of Nonlabens marinus rhodopsin-3 (NM-R3), derived from a marine flavobacterium, at 10-µs and 1-ms time points after photoexcitation. Our structural analysis reveals the conformational alterations during ion transfer and after ion release. Movements of the retinal chromophore initially displace a conserved tryptophan to the cytoplasmic side of NM-R3, accompanied by a slight shift of the halide ion bound to the retinal. After ion release, the inward movements of helix C and helix G and the lateral displacements of the retinal block access to the extracellular side of NM-R3. Anomalous signal data have also been obtained from NM-R3 crystals containing iodide ions. The anomalous density maps provide insight into the halide binding site for ion transfer in NM-R3