The Two-Point Codes on a Hermitian Curve with the Designed Minimum Distance

This is the second part of the series of papers devoted to the determination of the minimum distance of two-point codes on a Hermitian curve. We study the case where the minimum distance agrees with the designed one. In order to construct a function which gives a codeword with the designed minimum distance, we use functions arising from conics in the projective plane. AMS Classification: 94B27, 14H50, 11T71, 11G20     

Extremal Ternary Self-Dual Codes Constructed from Negacirculant Matrices

In this paper, a construction of ternary self-dual codes based on negacirculant matrices is given. As an application, we construct new extremal ternary self-dual codes of lengths 32, 40, 44, 52 and 56. Our approach regenerates all the known extremal self-dual codes of lengths 36, 48, 52 and 64. New extremal ternary quasi-twisted self-dual codes are also constructed. Supported by an NSERC discovery grant and a RTI grant. Supported by an NSERC discovery grant and a RTI grant. A summer student Chinook Scholarship is greatly appreciated.     

Study on B2 structure epitaxial Fe/Co superlattice

The B2 structure Fe₅₀Co₅₀ alloy is very attractive material as a large spin conductance asymmetry. In this study, we have tried to fabricate epitaxial Fe/Co superlattice with B2 structure. In order to investigate the relationship between the film structure and the substrate temperature, the films were prepared at different substrate temperature. The film structure of Fe/Co was evaluated by reflection high energy electron diffraction (RHEED). The in-plane lattice spacing gradually decreased to that of a bulk Fe₅₀Co₅₀ as increase in the number of layers. The B2 structure ordered phase of Fe/Co superlattice was successfully confirmed by RHEED and X-ray diffraction (XRD).     

Cyclodehydration of cis-2-butene-1,4-diol with active methylene compounds catalyzed by a diphosphinidenecyclobutene-coordinated palladium complex

(π-Allyl)palladium triflate coordinated with 1,2-bis(4-methoxyphenyl)-3,4-bis(2,4,6-tri-t-butylphenylphosphinidene)cyclobutene (DPCB-OMe), [Pd(η³-C₃H₅)(DPCB-OMe)]OTf, efficiently catalyzes cyclodehydration of cis-2-butene-1,4-diol with active methylene compounds such as acetylacetone and ethyl acetoacetate in toluene in the presence of pyridine. The reactions can be performed in air, giving 2-vinyl-2,3-dihydrofurans in good to high yields.     

Phase-shift algorithm for white-light interferometry insensitive to linear errors in phase shift

White-light interference has changes in fringe contrast. When phase-shift techniques are applied to white-light interference, the phase-shift algorithm which can extract the phase accurately under the contrast changes is required. There is often another requirement that the phase shift between frames should not be restricted to π/2. Computer simulations show that the well-known algorithms have non-negligible errors under both requirements. To find an algorithm which will satisfy the requirements, I extract individual terms (I _j ∓ I _k ) in an algorithmic equation by considering symmetry of light intensity against phase, where I _j is light intensity just after the j-th phase shift. Using computer simulations, I search for appropriate coefficients by which the terms are multiplied in the equation, finally finding an algorithm which satisfies both the requirements with the phase shift used.     

Diffusion of Fe in iron tellurides by Mössbauer spectroscopy

The diffusional line broadening of the Mössbauer spectra of iron in β-, δ^′- and ε-phases of iron telluride was studied in the temperature range from 573 to 1023 K. The jump frequencies in the β- and δ^′-phases calculated from Mössbauer line broadening were 1.6×10⁸ and 4.7×10⁶ s^?1 at the temperature of 90% of each peritectic point, respectively. The jump frequency in the ε-phase was too small to measure even at 873 K near the peritectic point being less than 2×10⁶ s^?1. These data indicate that the jump frequency is likely to be dependent on the distance between the iron atom and the nearest neighboring sites.     

Calculation of stacking geometries by a modified MM2 method

The MM2 method has been modified using a three‐center charge model aimed at determining stacking geometries. The stacking interactions for the benzene dimer, porphine dimer, and bis(4,5‐diazafluoren‐9‐one thiosemicarbazonato)palladium(II) have been assessed with both the three‐center charge model and the conventional single‐center charge model using the MM2 method. The modified MM2 method always gave better results than the conventional method, and the obtained structures by the former method are in good agreement with the proposed structures from those theoretical and experimental results. The possible advantages of using the three‐center charge model for complex systems are also discussed. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 835–845, 2001     

New extremal doubly-even [64, 32, 12] codes

In this paper, we consider a general construction of doubly-even self-dual codes. From three symmetric 2-(31, 10, 3) designs, we construct at least 3228 inequivalent extremal doubly-even [64, 32, 12] codes. These codes are distinguished by their K-matrices.