Rheooptische Studien an verstreckten Poly?thylen-Filmen

Ohne Zusammenfassung     

Free-radical identification by ESR in polyethylene and nylon

Identification of the free radicals in polyethylene and nylon produced by irradiation, grinding, and pulling to fracture was carried out by comparing the experimentally observed spectra with the spectra constructed from theoretical consideration with the aid of a computer. It was demonstrated that the various primary and secondary radicals are produced and formed in the materials depending upon means of degradation, degradation processes, orientation of materials, and conditions of ESR measurement.     

Stabilization of skyrmions via ϱ-mesons

It is shown that a skyrion can be stabilized by introducing ?-mesons into the chiral SU(2)_L × SU(2)_R lagrangian without higher-derivative terms like the Skyrme term. The ?-mesons are considered as dynamical gauge bosons associated with a hidden local symmetry of the non-linear sigma model. The lagrangian reduces to the Skyrme model in a limit of parameters. The Skyrmion mass M is found to be M = 1058 MeV when the parameters are fixed so as to satisfy the KSRF relation. It is also shown that a solition solution in a model with Ω-meson coupled with the baryonic current is a saddle-point solution.     

Current-voltage characteristics of charge-ordered organic crystals

The current-voltage characteristics of layered organic crystals theta-(BEDT-TTF)2MZn(SCN)4 (M = Cs, Rb) follow the power law with a large exponent (e.g., 8.4 at 0.29 K for M = Cs) over a wide range of currents in the low-temperature insulating state. The power-law characteristics are attributed to electric field-induced unbinding of electron-hole pairs that are thermally excited in the background of the two-dimensional charge order. The magnitude of crossover electric fields from Ohmic to the power-law characteristics indicates that the electron-electron Coulomb interaction is significantly long-ranged: The screening length is greater than 10 molecule sites.     

Damping constant of Co/Pt multilayer thin-film media

Gilbert's damping constants, α, of Co(t_Co)/Pt (1.4 nm) multilayer thin films are investigated by Q-band FMR analysis. α is calculated from the resonance width of the FMR spectrum. With decreasing t_Co, the α value decreases from 0.034 (t_Co=8.7 nm) to 0.023 (t_Co=1.8 nm), and then increases to 0.037 (t_Co=1.0 nm). The decrease of α with t_Co>1.8 nm is probably due to the eddy current loss effects. The increase of α with t_Co<1.8 nm would be caused by the increase of the distortion between the Co and the Pt layers at the interface. When the magnetic field direction was changed from θ=90° (parallel to the specimen) to θ=0° (perpendicular to the specimen), the α of all the specimens increased, and a sharp step in α was observed around θ=40°, where the α has the maximum value.     

Stereoselective synthesis of scyphostatin hydrophilic moiety

A stereoselective synthesis of scyphostatin hydrophilic moiety was accomplished. Substrate- and reagent-controlled dihydroxylation of tri- and monosubstituted alkenes afforded desired diols, respectively. Chemo- and stereoselective allylation of α-(methoxycarbonyl)cyclohexanone provided allylcyclohexanol. Oxidative cleavage of glycol and subsequent β-elimination of siloxycyclohexanone furnished the desired epoxycyclohexenone.