Junctional complexes and cell polarity in the urinary tubule

In this review, we demonstrate how differentiated membrane domains can be detected in epithelial cells using conventional light and electron microscopy, freeze-fracture electron microscopy and the immunoand cytochemical detection of membrane components. Using specific examples from the kidney, we show how the polarized insertion of these components into either apical or basolateral plasma membrane regions on either side of the tight junction barrier is related to specific functions of principal and intercalated cells in the collecting duct. In addition, distinct basal and lateral membrane domains have been revealed in some cells that are maintained in the absence of a tight junctional barrier in the plane of the membrane. This suggests that other factors, possibly related to cytoskeletal elements, may be involved in the functional segregation of these membrane areas. We propose that epithelial cell plasma membranes should be subdivided into apical, lateral and basal regions, and that the term “basolateral” may be an oversimplification.     

Application of the double slip plane crack model to temperature and strain rate sensitive BCC metals

The double slip plane crack model proposed by Weertman, Lin and Thomson (1982) has been applied to model the effect of temperature and strain rate on the stress intensity factor at a crack tip in temperature and strain rate sensitive materials. Increase in temperature or decrease in strain rate (as well as a decrease in slip plane spacing) are shown to increase the shielding of the crack tip by dislocation distributions on the slip planes. Furthermore, the effect of temperature on the fracture toughness, K_llc, at various strain rates was shown to exhibit the same sigmoidal shaped curve seen for K_lc data in typical alloy steels.     

Phase stability and grain boundary structure in the Cu-Bi system

Cu-Bi system is a model system for studies of interfacial phenomena, such as segregation and segregation induced faceting. In previous studies it was found that there is a strong preference for Σ = 3}111{-}111{ type facets, and their atomic structure was successfully resolved by combining high-resolution electron microscopy and computer simulation using Finnis-Sinclair type interatomic potential. The resolved grain-boundary structure was examined usingab initio full-potential linear muffin-tin orbital method by calculating formation enthalpies of several (hypothetical) Cu-Bi compounds under pressure. It was found that there is no driving force for the ordered alloy formed at the boundary to grow into a three-dimensional phase and thus specific interfacial phases are formed in this system. The range of applicability of Finnis-Sinclair potential used in the previous studies was also investigated by comparison withab initio calculations, and it was shown that the potential is entirely appropriate when Cu concentration is higher than about 66 at. %. In those cases the Cu-Bi system exhibits metallic behavior.     

Photoinjected carrier''s acoustic plasma oscillations

Resorting to the Nonequilibrium Statistical Operator Method (NSOM) we calculate the Raman spectrum of the double (electrons and holes) photoinjected plasma in direct-gap polar semiconductors. It allows us to identify four types of elementary excitations in the photoexcited carrier system. Besides the expected Raman bands corresponding to single quasi-particle excitations and a higher frequency plasma wave (labelled optical), there appear two low-frequency bands. They show a linear energy dispersion relation and are labelled acoustic plasma oscillations. While the optical plasma branch is ascribed to the out of phase collective movement of both types of carriers interacting through the bare Coulomb interaction, the acoustic branches are ascribed to the in-phase oscillation of each type of carriers interacting through the screened part of Coulomb interaction.     

Occurrence of Vibrio and other pathogenic bacteria in Mytilus galloprovincialis (mussels) harvested from Adriatic Sea, Italy.

Sixty-two samples of Mytilus galloprovincialis (mussels) harvested from approved shellfish waters in the Adriatic Sea were examined for the presence of Vibrio, Salmonella, Campylobacter, and verocytotoxin producing Escherichia coli. Vibrio spp. were isolated from 48.4% of samples; the species most frequently found were V. alginolyticus (32.2%) and V. vulnificus (17.7%), followed by V. cincinnatiensis (3.2%), V. parahaemolyticus (1.6%), V. fluvialis (1.6%) and V. cholerae non-O1 (1.6%). V. parahaemolyticus resulted negative to Kanagawa-phenomenon and to PCR amplification of tdh gene. V. cholerae resulted negative to PCR amplification of sto gene. No Salmonella, Campylobacter, or E. coli verocytotoxin-producing strains were isolated. The results of this study suggest the potential risk of ingesting raw or undercooked mussels due to the frequent presence of potentially pathogenic Vibrio species.