We propose that one of the main causes of the secular variation of the geomagnetic field is length-of-day (LOD) variation, namely, the variation of the rotation velocity of the mantle. We developed an analytical model, in which fluctuations of the rotation velocity of the mantle induces flow in the outer core through topographic coupling at the core-mantle boundary (CMB). The flow in turn bends the toroidal field to produce a poloidal field. Secular variation of the sectorial components of the geomagnetic field, from decadal to millennial time scale, is explained very well by our model. By comparing our theory with observations, we inferred important properties of the outer core and the mantle: the strength and the direction of the toroidal field, the dispersion relation of the slow magnetohydrodynamic oscillation, and the topography of the CMB.
The Re-Os age for molybdenite from the Hirase ore deposit, Japan, was determined. The obtained Re-Os age of 65.4Ma for molybdenite is in good agreement with the Rb-Sr whole rock age of 65.6Ma for the host Shirakawa granitic mass, but it is older than the K-Ar mineral age of 61.7Ma for the related wall rock. The difference between the K-Ar age and that determined by the Re/Os or Rb/Sr system can be explained to indicate the difference in the closure temperature among these chronological systems in the cooling history of ore deposit and host granitic masses.
Amphiphilic polysulfonates containing 1-adamantyl (Ad) or 1-naphthylmethyl (Np) groups were treated with didodecyldimethylammonium bromide (DDAB) (double-chain cationic surfactant) to yield Coulombic complexes which were soluble in common organic solvents. 1H-NMR spectra, 2D-NOESY, and NMR relaxation times for the complex of the Np-containing polymer in organic solution revealed that the motions of the Np residues were highly restricted, while those of the DDAB residues were much less restricted. These findings imply that the micelle structure of the parent amphiphilic polysulfonates in aqueous solution remained rather intact in the complexes even though they were dissolved in organic solvents. Covalently attached spin probes indicated that the complex was in a particularly compact form in benzene. Fluorescence emitted by pyrene incorporated in the complexes supported these findings.
Erythrocytes, which carry type-1 glucose transporters (GLUT-1) in their plasma membrane, were found to attach specifically and strongly to dishes which had been coated with a polystyrene derivative (PVG) substituted with reducing glucose moieties. The concave erythrocytes took teardrop shapes, stood on the rim, and swayed with gentle disturbance in the medium. In contrast, erythrocytes attached by nonspecific hydrophobic interaction on uncoated polystyrene dishes assumed fiat morphology and remained unperturbed by movements in the medium. The attachment to PVG substratum was suppressed by (1) GLUT-1 inhibitors such as phloretin, phloridzin, and cytochalasin B, and (2) PVG molecules in solution, and (3) at 4°C, suggesting that the specific recognition of high density of glucose on PVG and the dynamic movement of GLUT-1 are essential for the attachment. This novel combination of glucose transporter-carrying cells and reducing glucose-carrying polymer may lead to biomaterials with a wide range of applications.
Cathodically hydrogen charged type 316 austenitic stainless steel has been studied by x-ray diffraction. Both ε and α' martensites are formed by catholic charging in solution-treated samples, however very small amount of additional martensitic phase formation was observed in cold-worked samples. The volume fraction of ε phase decreases with increasing ageing time. ε and α' phases revert to γ phase below 723K and 923K, respectively. The incorporated hydrogen induces the metastable ε and α' phases. The transformation is suppressed by the tangled dislocation networks introduced by cold work. ε phase is more unstable, thereby it converts to α' and γ phases by hydrogen release. The hydrogen concentration in ε phase is higher han that in γ phase and that in α' phase is very low. The change of the x-ray profiles during ageing comes from the change of the spatial distribution of hydrogen atoms. By fitting the observed profiles to those calculated by Fick's law, the diffusion coefficent of hydrogen has been evaluated as 1.0×10-11cm2s-1, for both ε and γ phases.