Apodized waveguide arrays induced by photorefractive nonlinear surface waves.

A new type of nonlinear waveguides, photorefractive surface optical waveguides is suggested, which can be induced by photorefractive surface waves on the boundary of photorefractive crystal. The disturbed refractive index distribution of such waveguides behaves as a periodic lattice with apodized envelope, thus we call them photorefractive surface apodized waveguide arrays. Moreover, the dispersion relation and corresponding modes are analyzed. It is very interesting that the dispersion curves of index-guided modes and Bragg-guided modes couple and intertwine with each other, and anti-crossings instead of crossings between them hence generate some mini-gaps. Moreover there exists a type of extraordinary modes constituted by the splice of index-guided modes and Bragg-guided modes.

[Biochemical and molecular characterization of gliadins].

Gliadins account for about 40-50% of the total proteins in wheat seeds and play an important role on the nutritional and processing quality of flour. Usually, gliadins could be divided into alpha- (alpha/beta-), gamma- and omega-groups, whereas the low-molecular-weigh (LMW) gliadins were novel seed storage proteins. The low-molecular-weight glutenin subunits (LMW-GSs) were also designated as gliadins in a few literatures. The genes encoding gliadins were mainly located on the short arms of group 6 and group 1 chromosomes, and not evenly distributed. Repetitive sequences covered most of un-coding regions, which attributed greatly to the evolution of wheat genome. Primary structure of each gliadin has been divided into several domains, and the long repetitive domains consisted of peptide motifs. Conserved cysteine residues mainly formed intramolecular disulphide bonds. The rare potential intermolecular disulphide bonds and the long repetitive domains played an important role in the wheat flour quality. There was a general idea that gliadin genes, even prolamin genes, have a common origin and subsequent divergence lead to the gene polymorphism. The gamma-gliadins have been considered to be the most ancient of the wheat prolamin family. Several elements in the 5'-flanking (e.g. CAAT and TATA box) and the 3'-flanking sequences had been detected, which had been shown necessary for the proper expression of gliadins.