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Multilayered structures of YBa2Cu3O7-δ (YBCO) interlayered with thin layers of DyBa2Cu3O7-δ (DyBCO) were prepared on CeO2-buffered r-cut sapphire (Al2O3) substrates by pulsed laser deposition. Evaluation of the magnetic-field angular dependence of the critical current density [Jc(H,θ)] revealed that the flux pinning properties of multilayered YBCO/DyBCO films were significantly enhanced in comparison to single-layer YBCO films (monolayers) prepared using the same experimental parameters. The YBCO/DyBCO multilayers are highly anisotropic, i.e., the angular-dependent Jc exhibits a very prominent peak when the applied magnetic field (H) is oriented parallel to the ab-plane direction (H∥ab). Analysis of the Jc(H,θ) data revealed an enhanced random pinning for the multilayers for the entire range of field investigated. In the angular-dependent Jc data, correlated pinning along the c-axis crystallographic direction was also evidenced at low applied fields by a less prominent peak at H∥c. This result was further corroborated by the presence of defect microstructures comprised of linear and planar defects which were considered as strong sources of c-axis-correlated pinning. However, for higher applied fields the contribution of c-axis-correlated pinning is highly diminished and the ratio of Jc(H∥ab) to Jc(H∥c) is significantly enhanced. In addition to enhanced random pinning, it is considered that improved pinning along the H∥ab direction occurs due to ab-correlated pinning, arising from intrinsic pinning and possibly extended planar defects. [ABSTRACT FROM AUTHOR]

An abstract of the article "Photo-Periodic Response for Sargassum Horneri Receptacle Formation," by S. Yoshikawa, M. Kamiya and K. Ohki is presented.

An abstract of the article "Genetic Diversity of Marine and Freshwater Cladophora Species (Cladophorales, Ulvophyceae) From Mikata-Goko, Japan," by Y.-I. Hayakawa, S. Yoshikawa, K. Ohki and M. Kamiya, is presented.

An abstract of the article "Characterization of Parmales, a Siliceous Phytoplankton, Isolated From the Oyashio Water Near Japan," by M. Ichinomiya, S. Yoshikawa, M. Kamiya, K. Ohki and A. Kuwata, is presented.

Mutans streptococci are frequently isolated from dental plaque and carious lesions. These bacteria have been identified by conventional methods such as biochemical and serologic tests followed by the isolation of colonies on the mitis-salivarius agar, which are sometimes inconsistent. Recently, species-specific polymerase chain reaction (PCR) has been reported to rapidly identify Streptococcus mutans and Streptococcus sobrinus . However, in the case of identification and classification into several species, e.g. within the group of mutans streptococci consisting of seven species, the identification using species-specific PCR seems somewhat inefficient because of need for the development and preparation of specific primers for each species. Therefore, in this study we developed a simple method using restriction fragment length polymorphism analysis of PCR-amplified 16S ribosomal RNA genes (16S rRNA genes PCR-RFLP) for the identification of seven different species included in the group of mutans streptococci. We amplified 16S rRNA gene sequences from genomic DNA samples by PCR using universal primers and digested the PCR products with the restriction endonucleases, Hpa II and Hae III. Hpa II produced six RFLP patterns for eight reference strains, since the patterns for S. sobrinus, Streptococcus downei and Streptococcus ferus were similar. RFLP patterns produced with Hae III could separate these three species. Furthermore, the RFLP patterns predicted from the 16S rRNA gene sequences in the GenBank database agreed with the actual RFLP patterns produced in the present study. The 16S rRNA sequence comparisons can be used to identify oral mutans streptococci; however, the identification by sequencing is sometimes difficult in large-scale studies and for small laboratories. Therefore, 16S rRNA genes PCR-RFLP, using Hpa II and Hae III, could be an alternative method for the identification of mutans streptococci, and may be applicable for large-scale studies on the cariogenicity of mutans streptococci. [ABSTRACT FROM AUTHOR]