University of Patras

About: University of Patras is a education organization based out in Pátrai, Greece. It is known for research contribution in the topics: Population & Catalysis. The organization has 13372 authors who have published 31263 publications receiving 677159 citations. The organization is also known as: Panepistímio Patrón.

The effects of manufacturing-induced and in-service related bonding quality reduction on the mode-I fracture toughness of composite bonded joints for aeronautical use

Abstract: The scope of the present work is to investigate the possible effects of manufacturing and in-service induced reduction of bonding quality on the mechanical performance of composite bonded joints appearing in aeronautical applications, due to defects that cannot be detected sufficiently by means of conventional NDT. To this end, an experimental program has been conducted to measure mode-I interlaminar fracture toughness of adhesively bonded CFRP laminates. Five different representative scenarios have been considered; namely, poor curing of the adhesive, release agent contamination and moisture uptake by the composite substrates, which may occur during manufacturing of the joints, as well as Skydrol contamination and thermal degradation of the composite substrates, which are related to in-service life and could affect an adhesively bonded repair. Eight specimens for each scenario were tested. To assess the effects of each scenario, the experimental results have been compared with relative measurements taken from a set of reference specimens. Prior to mechanical testing, and the conventional NDT techniques, ultrasound C-scan and X-ray tests have been conducted to assess the quality of the bondline. All scenarios considered in the present study have been found to have an effect on the mode-I fracture toughness of the composite bonded joints. It was also shown that conventional NDT, such as ultrasonic and X-ray inspection, are not capable to sufficiently detect the defects resulting from the specific scenarios considered and being responsible for the reduction of joint’s performance.

Two International Methicillin-Resistant Staphylococcus aureus Clones Endemic in a University Hospital in Patras, Greece

Abstract: Pulsed-field gel electrophoresis (PFGE) of SmaI macrofragments and hybridization of ClaI digests with the mecA- and Tn554-specific DNA probes were used to define the endemic clones of methicillin-resistant Staphylococcus aureus (MRSA) among strains collected in 1993 and 1998 to 2000 at the University Hospital of Patras, Patras, Greece. Representatives of each clonal type were analyzed by spaA typing, multilocus sequence typing (MLST), and staphylococcal chromosomal cassette mec (SCCmec) typing. The results indicated the existence of two successive international MRSA clones: (i) a clonal type with PFGE type A, sequence type (ST) 30 (ST30), and SCCmec type IV, which was very similar to a clone widely spread in the United Kingdom, Mexico, and Finland, and (ii) a clonal type with PFGE type B, ST239, and SCCmec III, which was related to the Brazilian clone. Both clones seem to be widespread in Greece as well. A novel MRSA clone is also described and is characterized by a new MLST type (ST80) associated with SCCmec type IV and with the presence of Panton-Valentine leukocidin genes.

Global stability results for systems under sampled-data control

Abstract: In this work sufficient conditions for uniform input-to-output stability and uniform input-to-state stability are presented for finite-dimensional systems under feedback control with zero-order hold. The conditions are expressed by means of single and vector Lyapunov functions. Copyright © 2008 John Wiley & Sons, Ltd.

Plasmon-induced enhancement of quantum interference near metallic nanostructures.

Abstract: We show that the quantum interference between two spontaneous emission channels can be greatly enhanced when a three-level V-type atom is placed near plasmonic nanostructures such as metallic slabs, nanospheres, or periodic arrays of metal-coated spheres. The spontaneous emission rate is calculated by a rigorous first-principles electromagnetic Green's tensor technique. The enhancement of quantum interference is attributed to the strong dependence of the spontaneous emission rate on the orientation of an atomic dipole relative to the surface of the nanostructure at the excitation frequencies of surface plasmons.