Assuming that the crystalline polymer consists of the crystalline and the non‐crystalline phase, a mechanical model for the crystalline polymer is constructed. We introduced into this model such complicated circumstances as some parts of the crystalline phase will be largely deformed under a stress concentration and other parts not so much. The temperature dependence of complex moduli of the crystalline polymers with various degrees of crystallinity is illustrated by using the model. On the basis of the model, we have derived an equation for calculating the strain‐optical coefficient of the crystalline polymer from those of the crystalline and the non‐crystalline phase. The equation gives a relation among the rheo‐optical quantities, the viscoelastic quantities and the parameters representing the fine structure and the crystallinity of the polymer. It is concluded from this equation that the strain optical coefficients cannot be expressed by such a simple additive relation as usually employed.

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N‐substituted poly(p‐phenylene terephthalamide)s (PPTA), such as N‐alkylated, N‐aralkylated, and N‐carboxymethylated poly(p‐phenylene terephthalamide), were synthesized from PPTA and the corresponding halides by the polymer reaction via the metalation reaction in a solution of sodium methylsulfinylcarbanion in dimethyl sulfoxide at low temperature. The introduction of various substitutional groups into the amide groups of PPTA increased their solubilities, but decreased their thermal stabilities compared with PPTA. The effects of various substitutional groups on the thermal properties and the solubilities are discussed. Liquid crystal formation was noticed for PPTA substituted with bulky groups such as 9‐anthrylmethyl group.

The effects of the nitrogen in the HfSiON gate dielectric on the electrical and thermal properties of the dielectric were investigated. It is clearly demonstrated that nitrogen enhances the dielectric constant of silicates. High dielectric constants of the HfSiON are maintained and boron penetration is substantially suppressed in the HfSiON during high temperature annealing. These properties are ascribed to the homogeneity of the bond structure in the film containing nitrogen through high temperature annealing.

UV-induced photoisomerization of acetylacetone in low-temperature argon matrixes has been studied by Fourier transform infrared spectroscopy. Identifications of the species produced by UV irradiation (λ > 280 nm) were carried out with the aid of the density functional theory (DFT) calculation, in which the 6-31G* basis set was used to optimize the geometrical structures. By comparison of the observed infrared bands with the calculated spectral patterns, it was found that cis−trans isomerization around the C−C, CC, and C−O bonds occurs to produce less-stable enol isomers, 2-hydroxy-2-penten-4-one. Shorter-wavelength irradiation (λ < 280 nm) induced hydrogen-atom migration of the enol isomers to produce a keto isomer, 2,4-pentanedione.

Complex moduli of oriented specimens of polyethylene (PE), polypropylene (PP), polyoxymethylene, polyethylene oxide), and polytetrahydrofuran were measured in sheet form as a function of direction. The dynamic tensile modulus (E′) along the stretched direction (0° direction) was found to be lower than that perpendicular to the stretched direction (90° direction) above the temperature of primary dispersion (αa) for all polymers cited above. Below the temperature of an dispersion the E′ value of 0° direction is higher than that of 90° direction as expected from the anisotropy of modulus of the crystal. This fact leads us to the model that the crystalline region (C) and this amorphous region (A) are arranged mainly in series along the stretched direction and at the same time the C region should be more or less continuous along the 90° direction. The actual drawn sample is composed of many microfibrils as proved ł y the x‐ray small‐angle scattering. Those conditions imposed on the model should be satisfied even when many microfibrils are bound together into a fiber. This picture agrees with the structural model of hot‐drawn PE presented by Hosemann after its slight modification. Effects of cold drawing on the anisotropy of modulus were also surveyed.

Initial events of T-cell activation involve movement of the T-cell receptor into lipid rafts. Gangliosides are major components of lipid rafts. While investigating T-cell activation in ganglioside-deficient mice, we observed that CD4 + and CD8 + T cells required different ganglioside subsets for activation. Activation of CD4 + T cells from GM3 synthase-null mice, deficient in GM3-derived gangliosides, is severely compromised, whereas CD8 + T-cell activation is normal. Conversely, in cells from GM2/GD2 synthase-null mice, expressing only GM3 and GD3, CD4 + T-cell activation is normal, whereas CD8 + T-cell activation is deficient. Supplementing the cells with the corresponding missing gangliosides restores normal activation. GM3 synthase-null mice do not develop experimental asthma. Distinct expression patterns of ganglioside species in CD4 + T and CD8 + T cells, perhaps in uniquely functional lipid rafts, define immune functions in each T-cell subset. Control of ganglioside expression would offer a strategy targeting for specific T-cell subpopulations to treat immune diseases.

We examined the effects of the tie‐molecule fraction on the yielding behavior of two isotactic polypropylenes, one having little ethylene content and the other as the homopolymer with no ethylene. The tie‐molecule fraction of the samples used in this study was controlled by blending ethylene‐α‐olefin of an α‐olefin content above 50 mol % in the blend of which the copolymers were incorporated into the amorphous regions of polypropylene (PP). An excellent linear relationship was observed between the measured yield stress and the tie‐molecule fraction estimated from the Huang–Brown model, suggesting that the tie‐molecule fraction and lamellar stiffness determine whether the lamellar fragmentation is easily activated or not, depending on the PP composition. Furthermore, an extended Huang–Brown model predicts a lamellar cluster connecting about five lamellae, which has a potential to account for morphological transformation of the spherulitic structure into a fibrillar one. Comparing the immiscible blends showing a phase‐separated morphology with the partially miscible blends mentioned above, the yield stress was lowered by the presence of rubber phase, apparently in a similar manner; but the yielding processes were clearly discriminated between both cases when the yield stress was plotted against the tie‐molecule fraction. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 357–368, 1999