Ferromagnetic properties of cyclically deformed Fe3Ge and Ni3Ge

The magnetisation behaviour of cyclically deformed and non-deformed Fe₃Ge and Ni₃Ge is examined at sufficiently low temperatures below the Curie point. Despite these two intermetallics having the same L1₂ structure, they are found to show quite different behaviour in their ferromagnetic properties; the spontaneous magnetisation (M _S) remains unaffected in the former whereas it decreases notably in the latter after cyclic deformation. The origin of the difference is investigated and attributed to the difference in operative shear planes. These are mainly on {001} planes without the introduction of notable amounts of anti-phase boundary (APB) tubes in Fe₃Ge and mainly on {111} planes with the introduction of a high density of APB tubes composed of {111} APBs in Ni₃Ge. The effects of cyclic deformation on the high-field susceptibility?χ?and the coercive force (H _C) are also discussed by taking into account the dislocation distributions introduced by the {001} and {111} slips.     

Glycoconjugated polymer. I. Synthesis and characterization of amphiphilic polystyrenes with glucose,maltose, and maltohexaose as hydrophilic segments

Glucosyl styrene ( 1a ), maltosyl styrene ( 1b ), and maltohexaosyl styrene ( 1c ) were prepared by the glycosylation of 4‐vinylbenzyl alcohol with the corresponding glycosyl trichloroacetimidates with boron trifluoride diethyl ether complex. The copolymerizations of 1a – 1c with styrene were carried out with 2,2′‐azobis(2‐methylpropionitrile) as an initiator in dry N,N‐dimethylformamide at 60 °C, and this was followed by deacetylation to produce amphiphilic polystyrenes with glucose ( 3a ), maltose ( 3b ), and maltohexaose ( 3c ) as hydrophilic segments. 3 showed various solubility characteristics that were dependent on the content of glucose residues, especially within a range of 20–50 wt %. The solubility characteristics of 3 , related to the copolymer composition, indicated that the hydrophilic property was remarkably improved with an increased number of glucose units, that is, in the order 3a < 3b ? 3c . The results described in this article provide useful information for the design of glycoconjugated architectures with desired amphiphilic properties. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4061–4067, 2001     

Alignment error of arrayed beams in optical fiber array device

The alignment error of arrayed beams in optical fiber array devices is caused by structural errors of the optical fibers themselves such as error in cladding surface diameter, core offset, and the noncircularity of the cladding surface. In this study, the relations among them are analytically clarified. Moreover, by probability evaluation, the allowable structure errors for suppressing the alignment error below a certain level are calculated. The predicted yield rate below an alignment error of 0.4 μm for five beams is compared with the result of real fabrication.     

Hydrophobic modification of SiO2 surface by aminosilane derivatives

New aminosilanes with hydrolysable Si-N bond(s) were prepared by the amination of chlorosilanes and used as hydrophobic modifiers of SiO₂ surface. The aminosilanes are rather stable towards hydrolysis in air compared to their chlorosilane analogs. The modified SiO₂ was applied as a gate insulator of an organic thin-film transistor with a vapor-deposited film of pentacene as the active material. The transistor with the aminosilane-modified SiO₂ showed two- to threefold higher hole mobility than the device with bare SiO₂.     

Rheology and morphology change with temperature of SEBS/hydrocarbon oil blends

The effect of hydrocarbon oil incorporation on the rheological and phase behaviors of poly(styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene) (SEBS) has been investigated. SEBS‐A1 (neat SEBS) shows a presence of very long relaxation time mode even at the highest temperature carried out here. On the other hand, G′ of SEBS‐A3 (oil concentration = 50 wt %) drastically decreases with increase of temperature at a critical temperature, which can be assigned to be order–disorder transition (ODT). The critical temperature was determined by two rheological criteria. Incorporation of hydrocarbon oil affects the ODT temperature. The rheological response is very sensitive to a few temperature increases around the ODT temperature. Above the critical temperature, G′ finally yields the terminal flow in the low frequency range. The morphological observation at various temperatures was determined using atomic force microscopy (AFM) equipped with environmental controller. This enabled in situ observation of structural change of SEBS induced by temperature and phase transition. We found that the layered texture, mostly aligned along the surface can be seen for SEBS‐A1 ranging from room temperature to 230 °C, though the image contrast reduced by an increase of temperature. SEBS‐A3 showed sphere domains at room temperature and also remains the structure at a critical temperature. The phase separated structure disappeared almost completely above ODT temperature, which was confirmed by the rheologial criteria. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 955–965, 2009     

Euler polynomials,Bernoulli polynomials,and Lévyʼs stochastic area formula

In 1951, P. Lévy represented the Euler and Bernoulli numbers in terms of the moments of Lévy?s stochastic area. Recently the authors extended his result to the case of Eulerian polynomials of types A and B. In this paper, we continue to apply the same method to the Euler and Bernoulli polynomials, and will express these polynomials with the use of Lévy?s stochastic area. Moreover, a natural problem, arising from such representations, to calculate the expectations of polynomials of the stochastic area and the norm of the Brownian motion will be solved.     

Polarized optical waveguide spectroscopy: Effective tool to analyze adsorption process of dye molecules

Real time changes of the molecular orientational state are readily analyzed with polarized optical waveguide (POW) spectroscopy. Assembly or orientation of over 20 different dye molecules in solution have been analyzed during air-drying. The dynamic behavior of dyes including both orientational direction and degree of aggregation has been discussed with the key group structures of dyes. We suggest that certain interaction between dimethylimino residue of dyes and silanol residue of the waveguide surface should be responsible for these orientational changes. Furthermore, greater aggregation of these dyes tended to give rise to perpendicular orientation on the waveguide surface.