Continuous fabrication of Co-Cr perpendicular magnetic recording tape

To achieve high-throughput fabrication of Co-Cr/Ni-Fe double-layer perpendicular media, the optimum conditions for continuous preparation and construction of a new dc magnetron sputtering target have been investigated with respect to the aperture shield mask position and the magnetic circuit. The perpendicular magnetic tape media fabricated in a roll-coater equipped with the improved target showed high reproduced voltage at high densities.     

Comparison of the apparent masses and cross-axis apparent masses of seated humans exposed to single- and dual-axis whole-body vibration

Humans are exposed to whole-body vibration in many types of environment. In almost all cases, the vibration to which the human is exposed comprises multi-axis vibration, such that vibration occurs in all directions simultaneously. Despite the complex nature of vibration to which humans are exposed in the workplace, almost all laboratory studies investigating the biomechanical response of the person have been completed using single-axis simulators. This paper presents a study whereby 15 male subjects were exposed to single-axis whole-body vibration in the x-, y- and z-directions and dual-axis vibration in the xy-, xz-, and yz-directions using a 6 degree-of-freedom vibration simulator. All vibration magnitudes were 0.4 ms⁻² rms in each axis. Acceleration and force was measured in the x-, y-, and z-direction during all trials. Subjects sat in two postures (‘back-on’ and ‘back-off’) on a flat rigid seat. Apparent masses measured using single-axis and dual-axis vibration stimuli showed comparable results; similarly, cross-axis apparent masses (i.e. the ratio of the force in one direction to the acceleration in another direction) were almost identical for the single- and dual-axis vibration stimuli. All results were in agreement with data previously published using single-axis vibration. In most cases, the peaks in the apparent mass and the cross-axis apparent mass occurred at a slightly lower frequency for the dual-axis vibration than for the single-axis vibration. It is hypothesised that this change is due to a nonlinear effect, analogous to that which occurs with increasing vibration magnitude for single-axis vibration.     

Structure of mildiomycin,a new antifungal nucleoside antibiotic

The chemical structure of mildiomycin (1) active against powdery mildews was determined by chemical degradations and physical analyses to be 2 - [(2R, 5S, 6S) - 2 - (4 - amino - 1,2 - dihydro - 5 - hydroxymethyl - 2 -oxopyrimidin -1 - yl) - 5,6 - dihydro - 5 - L - serylamino - 2H - pyran - 6 - yl] - 5 - (3H⁺ - guanidino) - 2,4 -dihydroxyvalerate as shown in Chart 1.¹     

A regioselective ω-epoxidation of polyisoprenoids by the sodium bromide promoted electrochemical oxidation

A regioselective ω-epoxidation of polyisoprenoids has been realized by the sodium bromide promoted electrochemical oxidation in a mixed solvent (MeCN-THF-H₂O).     

Anomalous magnetic behaviour and susceptibility maximum in CeSn3

Anomalous magnetic behaviour observed in one of cerium intermetallic compound, CeSn₃, is analysed in the spirit of the Fermi liquid model, by regarding even the 4f-electrons of cerium as itinerant. It is shown that the appearance of the broad peak of the susceptibility at about 150°K can be attributed to the T²1nT dependence of the susceptibility on temperature.     

Electric polarization memory effect in a magnetoelectric multiferroic CuFe1−xGaxO2

Magnetic oxide CuFeO₂ is a magnetoelectric multiferroic with new type of spin–polarization coupling different from that in the spin-current mechanism, where magnetic field-induced or nonmagnetic impurity-induced proper helical magnetic ordering generates a spontaneous electric polarization parallel to the helical axis. Using a CuFe_1−xGa_xO₂ sample with x=0.035, in which the single ferroelectric phase is realized below T_N8 K in zero magnetic field unlike CuFe_1−xAl_xO₂, we have performed pyroelectric current, thermally stimulated current (TSC) and polarized neutron diffraction measurements to study a memory effect that the electric polarization is partially preserved even for 2nd-cooling from above T_N without poling electric field. It was found that the charge trapped during 1st-cooling with poling electric field, which is released as TSC on heating, plays an important role in the memory effect.     

2‐Pyridone–tartronic acid (1/1), 3‐hydroxy­pyridinium hydrogen tartronate and 4‐hydroxy­pyridinium hydrogen tartronate

Tartronic acid forms a hydrogen‐bonded complex, C₅H₅NO·C₃H₄O₅, (I), with 2‐pyridone, while it forms acid salts, namely 3‐hydroxy­pyridinium hydrogen tartronate, (II), and 4‐hy­droxy­pyridinium hydrogen tartronate, (III), both C₅H₆NO⁺·C₃H₃O₅⁻, with 3‐hydroxy­pyridine and 4‐hydroxy­pyridine, respectively. In (I), the pyridone mol­ecules and the acid mol­ecules form R(8) and R(10) hydrogen‐bonded rings, respectively, around the inversion centres. In (II) and (III), the cations and anions are linked by N—H⋯O and O—H⋯O hydrogen bonds to form a hydrogen‐bonded chain. In each of (I), (II) and (III), an intermolecular hydrogen bond is formed between a carboxyl group and the hydroxyl group attached to the central C atom, and in (I), the hydroxyl group participates in an intramolecular hydrogen bond with a carbonyl group. No intermolecular hydrogen bond is formed between the carboxyl groups in (I), or between the carboxyl and carboxyl­ate groups in (II) and (III).     

Application of selective 13C?{1H} nuclear overhauser effects with low-power 1H irradiation in carbon-13 NMR spectroscopy

The feasibility of the application of selective ¹³C? {¹H} nuclear Overhauser effect (NOE) measurements to organic structural analysis in ¹³C NMR spectroscopy has been investigated at 25 MHz using citraconic anhydride and the methyl ester of pentalenolactone as model compounds. This selective ¹³C? {¹H} NOE technique with single frequency low-power ¹H irradiation should find wide application in the structural elucidation of organic compounds, especially for the reliable assignment of quaternary carbon signals.     

Naturally reductive Riemannian homogeneous structures on some classes of generic submanifolds in complex space forms

We prove that the universal covering spaces of the generic submanifolds of C P _n and of C H _n are naturally reductive homogeneous spaces by determining explicitly tensor fields defining naturally reductive homogeneous structures on them.