Nonuniform Distribution of Molecularly Thin Lubricant Caused by Inhomogeneous Buried Layers of Discrete Track Media

A method of estimating the thickness distribution on a surface with inhomogeneous buried layers is presented. It revealed that the lubricant distributes nonuniformly on discrete track media (DTM). First, the estimation method was theoretically developed. To balance the disjoining pressures of the lubricants in the track and off-track regions, the lubricant takes different film thicknesses in the two regions because the regions consist of different materials and have different intermolecular interactions. Formulating the balance of the disjoining pressures by using the theory for intermolecular force, we obtained the thicknesses in the two regions. Next, the validity of the theoretical estimation was experimentally verified. When a nonpolar lubricant was applied to a nanometer-thick oxide layer on a silicon surface, which was locally fabricated by probe oxidation, AFM images showed that the lubricant height in the oxide region decreased and the thickness distribution agreed well with that predicted by theory. Using the developed theory, we estimated the lubricant thicknesses on DTM. Even if lubricant is uniformly applied onto the disk, it moves from the off-track to track regions due to the pressure balance. Thus, the theory predicts that the lubricant is thicker in the track regions than the off-track region at equilibrium.journal articl

PE磨耗ゼロを目指すTi-13Nb-13Zr (F1713)製人工股関節骨頭コンポーネントの開発

One of the major problems of total hip arthroplasty is the wear of ultra-high molecular weight polyethylene (UHMWPE) acetabular socket, therefore it is necessary to intercept the wear products. The authors tried to dissolve this problem to keep a good fluid film lubrication between the Ti-13Nb-13Zr femoral head ball and the PE socket. Because , the directly contact of the components was avoided with the film to establish by a newly precise processing technology of these components.textapplication/pdfdepartmental bulletin pape

Evidence for Muon Neutrino Oscillation in an Accelerator-Based Experiment

journal articl

Screening of differential expression of mRNAs related with synaptic plasticity : Changes of mRNA expressions for limbic-specific serine protease・neuropsin and seven sialyltransferase isoenzymes in kindled-mouse brain

奈良先端科学技術大学院大学博士(バイオサイエンス)doctoral thesi

Well-Conserved Tandem G·A Pairs and the Flanking C·G Pair in Hammerhead Ribozymes Are Sufficient for Capture of Structurally and Catalytically Important Metal Ions

An important metal ion in reactions catalyzed by hammerhead ribozymes is the so-called P9 metal ion (the metal ion captured by the phosphorus atom of A9 (P9) and N7 of G10.1 [P9−G10.1 motif]). Hammerhead ribozymes have catalytically important tandem G·A pairs in the core region, and the P9−G10.1 motif captures the P9 metal ion, which is most probably a Mg2+ ion under physiological conditions. In this study, we used 1H, 31P, and 13C NMR spectroscopy to examine whether this motif by itself, in the absence of other catalytic loops, might be sufficient to capture structurally and catalytically important metal ions in solution. We deduced that the P9−G10.1 motif was able to capture a Mg2+ ion in solution in the absence of any other part of a hammerhead ribozyme, because the chemical shift values of the phosphorus atom of A6 (P/A6), C8 of G7 (C8/G7), and H8 of G7 (H8/G7) in the P9−G10.1 motif of a model duplex, designated GA10, were selectively perturbed during titration up to a 1:1 molar ratio of Mg2+ ions and the P9−G10.1 motif. We next studied the binding of a Cd2+ ion to the P9−G10.1 motif and found that, in agreement with recent kinetic studies (Yoshinari and Taira, Nucleic Acids Res. 2000, 28, 1730−1742), a Cd2+ ion also bound to this motif. Finally, we conclude that the P9−G10.1 motif (a sheared-type G·A pair with a guanine residue on the 3‘ side of the adenine residue) with several flanking base pairs is sufficient for capture of divalent cations such as Mg2+ and Cd2+ ions and that hammerhead ribozymes utilize this intrinsic metal-binding property of the P9−G10.1 motif for catalysis