An X-ray double-crystal method utilizing non-parallel setting for measuring local lattice mismatches between epitaxial films and substrates

An X-ray topographic method utilizing non-parallel (+,-) setting for measuring lattice mismatches between epitaxial films and substrates is reported. This method gives quantitative as well as topographical information on lattice distortions in a distorted crystal and allows us to study any reflection from various crystals, in which the fractional variation of lattice spacing, δd/d, is of the order of 10^-4?10^-5. Examples of applications are lattice mismatches between epitaxial magnetic garnet films and (111) gadolinium garnet (GGG) substrates. The spacing of the epitaxial film was slightly larger along the [111] direction than that of the substrate and the apparent crystal symmetry of the epitaxial film is rhombohedral.     

Three-dimensional polarimetric integral imaging

A three-dimensional (3D) polarimetric image sensing and display technique based on integral imaging is proposed. Three-dimensional polarization distribution of reflected light from a 3D object can be measured as elemental image arrays by a rotating linear polarizer. After the measurement of the polarization of the 3D object, the 3D polarimetric object can be reconstructed optically by displaying the polarization-selected elemental images in spatial light modulators with two quarter-wave plates. Experimental demonstration of 3D polarimetric imaging of a 3D object attached to two orthogonal linear polarizers is presented. To the best of our knowledge, this is the first report on 3D polarimetric sensing imaging and 3D optical reconstruction by integral imaging.     

Reversible light-driven structural changes between the mono- and bilayer stacking alignments in 4-octadecyloxystilbazolium arylcarboxylate films

The present investigation deals with the light-driven morphological changes in multilamella films of N-methyl-4-octadecyloxystilbazolium arylcarboxylates (C18OStz+X-) cast on glass slides. The results of XRD analysis show a photostimulated layer expansion and shrinkage of the stacked thin films along the c-axis under alternative illumination at >350 and 254 nm, respectively. It was revealed that such lamellar changes could be switched either way by a reversible transformation between the mono- and bilayer units in these stacked multilamella films. Moreover, such controlled structural adjustments in the alignment could be initiated by the photocyclodimerization of the stilbazolium moieties of the arylcarboxylate salts; i.e., a monolayer-to-bilayer transformation could be induced at a stage of only 10% cyclodimer formation. The photoinduced patterning on the surface of the films was also analyzed by SEM and fluorescence microscopic investigations.     

Characterization of the mod 3 cohomology of

It is shown that the mod 3 cohomology of a homotopy associative mod 3 -space which is rationally equivalent to the Lie group and which has integral 3-torsion is isomorphic to that of as a Hopf algebra over the mod 3 Steenrod algebra.

     

Pseudotwistors

We deal with the Hermitian Hurwitz pairs of signature (, s), + s = 5 + 4, | + 1 – s| = 2 + 4m;, m = 0, 1,.... We introduce the Hurwitz twistors for signature (3, 2) and its dual (1, 4) and we indicate the relationship between Hurwitz and Penrose twistors. The signatures (1, 8) and (7, 6) give rise to pseudotwistors and bitwistors, respectively. For pseudotwistors, we prove a counterpart of the Penrose theorem in the local version, on real analytic solutions of the related spinor equations versus harmonic forms, and in the semiglobal version, on holomorphic solutions of those equations versus Dolbeault cohomology groups. We prove an atomization theorem: There exist complex structures on isometric embeddings for the Hermitian Hurwitz pairs so that the embeddings are real parts of holomorphic mappings.