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A sputtered tape that uses a CoPt-based granular recording layer was developed for practical application in the next generation of large-capacity magnetic tapes. 1) First, disk media were prepared by depositing films onto glass substrates using an inline disk sputter machine in which the substrates were stationary facing the target, and the ability to control the crystalline orientation, the magnetic isolation, and the magnetic anisotropy of the recording layer, which are the important functions of the underlayer, was investigated. As a result, it was found that the medium with Co60Cr40 (45 nm)/Co60Cr40-15 vol.% TiO2 (5 nm) as the underlayer has the same properties as the medium with the Ru underlayer. 2) Next, a sputtered magnetic tape with Co60Cr40 (25 nm)/Co60Cr40-SiO2 (25 nm) as the underlayer deposited on a polymer film was prepared using a roll-to-roll sputtering machine. The ability to control the crystalline orientation and magnetic isolation of the magnetic recording layer was evaluated, and from the results it was found that a magnetic film with a granular structure was formed on the sputtered magnetic tape in which the $c$ -axis of the magnetic crystal grains is oriented in the direction perpendicular to the film and the magnetic crystal grains are separated by the SiO2 amorphous phase. 3) Furthermore, when the recording properties of the sputtered magnetic tape with a Co60Cr40 (25 nm)/Co60Cr40-SiO2 (25 nm) underlayer were compared with those of a magnetic tape for a linear tape-open (LTO) format eighth-generation tape cartridge (LTO 8), it was confirmed that the broadband signal-to-noise ratio of the sputtered tape with a Co60Cr40/Co60Cr40-SiO2 underlayer is 4.2 dB higher than that of the LTO 8 tape at a linear density of 300 kfci.

A prototype perpendicularly oriented sputtered tape sample was investigated using a prototype high-moment tape write head and a 48 nm-wide tunneling magnetoresistive hard disk drive read head. A linear density of 818 kbpi with a post-detection byte-error rate $\sigma $ -PES) ≤ 6.5 nm was also demonstrated over a tape speed range of 1.2–4.1 m/s. This magnitude of PES in combination with a 48 nm-wide reader enables reliable recording at a track width of 103 nm corresponding to a track density of 246.2 ktpi, for an equivalent areal density of 201.4 Gb/in2.

In programming exercises, a few professors and assistants generally instruct many students. To conduct precise guidance, it is important for professors but difficult to detect the learning situation of each student, such as whether they are having difficulties in learning. However, there have been no effective methods for extracting occurrences of stumbling that do not result in compilation errors since most existing methods have targeted only those that do. In this research, we aimed at developing methods for detecting when inexperienced students make mistakes in expressing the intended processing as a program (i.e. stumbling in the construction of program logic). In this paper, we initially describe a method we developed for extracting candidates of such stumbling on the basis of an analysis of compilation histories. We also describe methods for estimating such stumbling from among extracted candidates by analyzing transitions in the similarity between source codes. Finally, we describe an experiment done using multiple methods of similarity calculation and discuss the characteristics of our methods on the basis of results.

A method was developed that was capable of producing a 1000 m length of sputter-deposited magnetic tape using a roll-to-roll in-line sputtering system. This method produced a magnetic recording structure having perpendicular magnetic orientation and uniform grain size, which was observed over the full length of the sputtered area. The potential read/write performance of 60 Gb/in 2 areal density and good durability were also observed. Therefore, the possibility of utilizing sputter-deposited tape production for high recording density media was evident.

We investigated the relationship between the shape of clusters of Co crystallites, obtained by transmission electron microscopy (TEM), and the magnetic anisotropy field of grains (Hkgrain) of Co-CoO obliquely evaporated magnetic tape. Comparison of the former with the latter revealed that the Hkgrain of Co-CoO obliquely evaporated magnetic tape closely correlates with the aspect ratio (N) of clusters of Co crystallites. The magnitude of Hkgrain is defined as that of a magnetic field where the rotational hysteresis loss of the torque curve is zero. We investigated the relationship between the Hkgrain and saturation magnetization Ms, using samples prepared under various conditions. The results showed that Hkgrain becomes asymptotic to the value HkCo + Ms/2, determined by the maximum value of the shape anisotropy Ms/2 in the region of low Ms. The value of Hkgrain calculated by using a value of N obtained from TEM images was found to be close to the value of Hkgrain obtained by magnetic torque measurement, and this tendency was confirmed qualitatively.

New oxomolybdenum(V) porphyrin complexes, [MoO(tmp)(C6H5SO3)] 1, [MoO(tpp)(C6H5SO3)] 2, [MoO(tpp)(HSO4)] 3, [{MoO(tpp)}2(μ-SO4)] 4, and [MoO(tpp)(NO3)] 5, were synthesized and characterized by UV-vis, IR, FAB-MS, and ESR measurements. The structures of the complexes, 1, 4, and 5, were determined by X-ray crystallographic analysis. The benzenesulfonate ion in 1 and the nitrate ion in 5 coordinate to the molybdenum atom as monodentate ligands. The oxidation number of the central molybdenum ion of these complexes was confirmed to be 5+ by ESR measurements. In the dinuclear complex 4, a sulfate ion bridges two molybdenum porphyrins. The dinuclear complex 4 exhibited spin coupling between the two molybdenum nuclei.

The planar oxomolybdenum(IV) and Fe(II) tetraphenylporphyrins (tpp) and fullerene C 60 are encapsulated by monolayer dispersion technique in the mesoporous ordered channels(2.7, 4.7 nm diameter) of FSM-16. They exhibit a stoichiometric adsorption of O 2 at 300 K and 50–250 Torr forming a 1:1 dioxygen complexes( ν (O–O)=928 and 1025 cm -1 ) with Mo IV O(tpp) and Fe II (tpp) entrapped in FSM-16, although the Mo(=O) and Fe porphyrins are inactive for O 2 uptake in crystal and solution. The mesoporous cylindrical channels of FSM-16 act as the confined hydrophobic circumstances to accommodate isolated Mo and Fe porphyrins and prevent the irreversible formation of a paramagnetic μ -oxo dimer, similar to the picket-fenced porphyrin complexes such as Mo IV O(tmp)=5,10,15,20-tetramesitylporphyrin). The reversible removal of O 2 bound with the Mo and Fe porphyrins proceeds at 300 K by high-pressure Hg photoirradiation. The isotopic labeling tracer studies reveal that they are catalytically active for oxygen transfer via fullerene C 60 in the selective photo-oxidation of propene towards acetone at 303–393 K.

The molybdenum(VI) porphyrin dioxygen complex, [MoVIO(O2)(tmp)] (tmp = 5,10,15,20-tetramesitylporphyrinato), prepared from the reaction of [MoIVO(tmp)] with dioxygen at room temperature is characterized in detail. Bulky mesityl substituents on the porphyrin rings enable the isolation of the dioxygen complex. Photoirradiation of the toluene solution of the dioxygen complex with visible light regenerated [MoIVO(tmp)] immediately. Upon heating the solid sample of the dioxygen complex, dioxygen gas was liberated around 40—90 °C, leaving [MoIVO(tmp)]. The solid and a toluene solution of [MoIVO(tmp)] thus formed, again absorbed O2 from air to make [MoVIO(O2)(tmp)]. The IR and 1H NMR data confirmed that O2 was coordinated as a peroxide mode to the central molybdenum(VI) ion from the same side of the porphyrin plane with the oxo ligand and that both the axial ligands (peroxo and oxo) eclipsed the trans-N atoms of the porphyrin rings. The second-order rate constant for the formation of the dioxygen complex in tolu...

Electron holography is effective for the study of the micromagnetic structure of various advanced magnetic materials. Although the microstructure of obliquely evaporated Co-CoO tapes has been explicitly described so far, the investigation of magnetization in the as-recorded state is indispensable for the in-depth understanding of the magnetization transition mechanism of the tape. In this study, for the first time, a clear image is shown depicting the magnetization transition of an oblique Co-CoO tape obtained by electron holography. The image is compared with those obtained by computer simulation taking into account the recording process. It is found that although the easy axes of Co crystal particles are titled at approximately 45deg to the tape plane, the recorded magnetization shows a circular shape with its center located slightly above the center plane of the tape. Using the images of the magnetization, some possible ways to improve the recording performance of the tape are discussed

Magnetic properties and read-write characteristics of Co-CoO obliquely evaporated tape provided with a CoO underlayer were investigated. By forming a fine CoO crystal plane on the underlayer surface and optimizing the thickness and oxygen flow rate of the magnetic layer, we were able to make a medium with a coercivity, Hc=240 kA/m, the highest for the Co-CoO obliquely evaporated media. This medium also shows a decrease in the switching field distribution compared to the conventional medium. The read-write characteristics of this medium present a narrower half-amplitude pulsewidth (PW/sub 50/) and a higher output than conventional medium. The obtained results suggest that providing an underlayer brings about a sharp magnetization reversal.

The growth mechanism that determines the microstructure of obliquely evaporated Co-CoO tapes has been investigated. A preferred orientation relation hcp--Co //CoO is found in the neighboring grains when the hcp-Co grains grow on top of the CoO. However, no preferred orientation is observed in the lower to middle part of the magnetic layer when the CoO grains grow on top of the hcp-Co. The structural properties of the Co-CoO tapes can be explained accordingly based on the preferred orientation relation.

Azidochromium(III) tetraphenylporphyrin, Cr III (tpp)N 3 (tpp = 5,10,15,20-tetraphenylporphyrinato), and azidoiron(III) tetraphenylporphyrin, Fe III (tpp)N 3 , in the solid state, were pyrolysed under 10 −5 –10 −6 torr at around 250°C, liberating nitrogen gas to afford Cr II (tpp) and Fe II (tpp) as final products, respectively. Cr V (tpp)N formed in the process of the Cr III (tpp)N 3 pyrolysis is reduced to Cr II (tpp), although pure Cr V (tpp)N prepared independently is not pyrolysed under the same conditions. In the presence of dioxygen in the toluene solutions of these pyrolysed products, Cr IV (tpp)O or [Fe(tpp)] 2 O is formed. The mechanisms of these reactions in the solid state are discussed in comparison with those in solution.

New dioxygen molybdenum porphyrins were formed by the introduction of dioxygen into the toluene solutions of oxomolybdenum(IV) porphyrins, MoIVO(tpp) and MoIVO(oep), around −70 °C. By raising the temperature to 25 °C, or by the photoirradiation of the solutions with the wavelength of the Soret bands, the parent oxomolybdenum(IV) porphyrins were regenerated. A structure for the dioxygen complexes is proposed.

The microstructure and magnetic domain structure of a Co-CoO obliquely evaporated tape for magnetic recording are studied by analytical electron microscopy and electron holography, respectively. While the existence of Co and CoO crystallites is confirmed by energy-filtered electron diffraction, columnar structure of the Co crystallites surrounded by the densely packed CoO crystallites is visualized by an elemental mapping method with electron energy loss spectroscopy, and the crystal orientation relation among the Co crystallites is clarified by high-resolution electron microscopy. It is found that the neighboring Co crystallites have close crystal orientations. On the other hand, electron holography reveals the magnetic flux distribution in a thin section of the tape. Although there exists the background resulting from the effect of inner potential with thickness variation, the distribution of lines of magnetic flux is found to correspond well to the recorded pattern.

Reversible dioxygenation reaction of a molybdenum(IV) porphyrin, MoIVO(tmp), in the solid state with dioxygen, was confirmed directly by in-situ UV-vis spectral measurements.

A new molybdenum porphyrin dioxygen complex [MoVIO(tmp)(O2)], formed by the reversible reaction of [MoIVO(tmp) with dioxygen in aprotic solvents at room temperature, is isolated and characterized by temperature-programme desorption mass, IR, 1H NMR, and UV–VIS spectroscopy.