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The substituent effect is determined on the facial bias and relative rate of the Diels-Alder reactions of maleic anhydrides set in the dibenzobicyclo(2.2.2)octatriene motif. Benzene ring substituents of these nonsterically biased dienophiles afford a sterically equivalent pi-face due to distance from the reaction center. The substituent effect is inconsistent with the effect on ketone and olefin derivatives, and depends on reagents that encompass a variety of interacting s- or p-orbital, and varying addition trajectories and HOMO-LUMO stabilization site.

The lipase modulator protein (LimL) of Pseudomonas sp. strain 109, in which the NH2-terminal hydrophobic region is absent, helps determine in vitro and in vivo lipase modulation. Immunoprecipitation in renatured lipase solution reveals the generation of a recombinant LipL (rLipL)-rLimL complex, and lipase activity is lowered by the binding of rLimL. Affinity chromatography with anti-rLimL antibody helps purify the native LimL, which occurs as a membrane-bound protein in Pseudomonas sp. strain 109.

Pi orbitals overlap in a sigma type overlap to produce unsymmetrical pi face of the olefin groups in dibenzobicyclo(2.2.2)octatrienes and the carbonyl groups in dibenzobicyclo(2.2.2)octadienones. First order pi-pi interactions are responsible for these perturbations in the orbitals. Internuclear regions having different orbital densities influence the unsymmetrization of the pi lobes.

Difficulties exist in identifying the intergranular exchange coupling constant ([h.sub.e]) via magnetic properties measurements and TEM observation of actual media. The [h.sub.e] was estimated to be 0.13 for Co[Cr.sub.12][Pt.sub.5]TaNb/CrMo and 0.115 for Co[Cr.sub.19][Pt.sub.5]TaNb/CrMo via micromagnetic simulation. The other parameters, which are the magnetostatic coupling constant ([h.sub.m]) and the grain geometry, were obtained from measuring the magnetic properties and observing the microstructure of actual media by TEM. The [h.sub.m] is 0.11 for Co[Cr.sub.12][Pt.sub.5]TaNb and 0.09 for Co[Cr.sub.19][Pt.sub.5]TaNb. The parameters were ascertained to be suitable by comparing the MFM images of the DC demagnetized state and the medium noise dependence of the linear density between the micromagnetic simulation and the experiments. Index-Terms - micromagnetic simulation, intergranular exchange coupling, medium noise, DC demagnetized noise, CoCrPtTaNb media.

A study was conducted to explore highly efficient intermolecular cycloaddition of N-boranonitrone with various alkenes to give the corresponding isoxazolidine derivatives in moderate to high yields. The reaction of terminal alkenes is found to be very useful for synthesis of 1,3-anti aminoaldohol derivatives by reductive cleavage of an N-O bond.

The structural features of the N-methyl pyridyl amide and its dynamic protonation-associated conformational conversion from layered to spiral and then flat are investigated. The dynamic conformational conversion is due to amide bond switching together with intramolecular hydrogen-bonding effects and this has considerable potential for controlling the shape of large molecules or supramolecules.

Presents information on a study that investigated the magneto-optical Faraday effect of porous films comprised of cobalt-substituted barium ferrite particles fixed by a resin. Film preparation and measurements; Results and discussion; Conclusion.

In this paper, magnetic and structural properties of near-equiatomic CoPt thin films, which exhibited a high coercivity in the film-normal direction-suitable for perpendicular magnetic recording media applications-are reported. The films exhibited a larger coercivity of about 6.5 kOe at 8 nm. The coercivity showed a monotonous decrease as the film thickness was increased. The transmission electron microscopy images indicated that the as fabricated CoPt film generally consists of a stack of magnetically hard hexagonal-close-packed phase, followed by stacking faults and face-centred-cubic phase. The thickness dependent magnetic properties are explained on the basis of exchange-coupled composite media. Epitaxial growth on Ru layers is a possible factor leading to the unusual observation of magnetically hard hcp-phase at high concentrations of Pt. [ABSTRACT FROM AUTHOR]

Schemes for SNR enhancement for advanced longitudinal recording media are discussed. SNR improvement is obtained by utilizing a bi-magnetic layer media, where the initial magnetic layer has lower magnetization, coercivity, and magnetic anisotropy, in comparison to the top magnetic layer. Further improvements in SNR and thermal stability are achieved using synthetic ferrimagnetic media. The selection of proper thickness and composition of the initial magnetic layer is important for the high performance of the synthetic ferrimagnetic media. Index Terms--High-density longitudinal recording, recording media, signal to noise ratio, thermal stability.

The thermal stability of a CoCrPtB-based media for over 20 Gbit/[in.sup.2] recording is investigated by magnetometry and spin stand methods. Recent quaternary and 5-element alloys for longitudinal magnetic recording media show significantly reduced grain sizes compared to Co-Cr-Pt-Ta alloys for the same underlayer structure. Cr segregation was also enhanced and the Cr-rich regions between grains were wider than those of cocrPtTa media. These resulted in significant gains in [S.sub.o]/[N.sub.m] necessary for high density and high data rate recording and also in the degradation of magnetic thermal stability. Although higher densities can be achieved by decreasing the bit aspect ratio, side erasure problems due to flux leakage from narrow write heads are worsened. Index Terms--Thermal stability, high density longitudinal recording, side erasure, overwrite, CoCrPtB.

The magnitude of temperature coefficient of coercivity (|d[H.sub.C]/dT|) of high-density recording media increases with decreasing media thickness and dilution of the Co in the interior of the grains by Cr or other substitutions. A reduction in magnetic anisotropy with temperature increases |d[H.sub.C]/dT| whereas a decrease in magnetization compensates for such change. Some approaches such as better Cr segregation, or utilizing a magnetic bilayer with the initial layer having a lower Curie temperature can be used to minimize |d[H.sub.C]/dT|. Index Terms--High-density longitudinal recording, recording media, temperature coefficient of coercivity, thermal effects.

A longitudinal medium was developed for 20 Gb/[in.sup.2] recording. This medium has a coercivity of 3380 Oe and [M.sub.r] [Delta] = 0.42 memu/[cm.sup.2] Modulation noise and track edge noise were well suppressed by the decrease in the activation volume. Remanent magnetization is stable; at 338 K, the coefficient of remanence reduction was -0.066 dB/decade in a reverse field of 460 Oe which corresponds to the demagnetizing field in a bit at 430 kFCI. Recording bits of 430 kfci were confirmed by MFM. The BER was 3.45x[10.sup.-6] using a conventional EPR4 channel with a 16/17 code rate at 405 kBPI (430 kFCI). From squeeze measurements, the track pitch was 0.505 [micro]m (50.3 ktpi) including a guard band of 0.06 [micro]m. 20.4 Gb/[in.sup.2] recording is made possible by the combination of a narrow gap spin-valve head and a low noise medium. Index Terms--20 Gb/[in.sup.2] demonstration, rigid disk medium, spin-valve read head and narrow pole-tip write head.