Detection of Debonding Area in Aluminium-GFRP Laminates by Electromagnetic Transducer

Electromagnetic Acoustic Transducer (EMAT) is applied to nondestructive testing of aluminum-GFRP laminates. Because of its high specific strength, laminated FRP came to be used in place of metal materials. However, once delamination is introduced by the impact force in the out-of-plane direction, the compressive strength in the in-plane direction is greatly reduced. To improve the tolerance for impact force, fiber metal laminates (FML) have been developed. Since debonding may occur at the interface of FRP and metal sheet, nondestructive detection of the debonding is required as health monitoring of the FML. In this study, GFRP laminates were molded on aluminum sheets, and we measured the distribution of standing wave amplitude in the aluminum sheets using EMAT for shear wave. In the bonded area, the shear wave is partially transmitted to the FRP on reflection at the boundary, which makes the attenuation coefficient larger than that in the debonded area. It was found that in scanning the EMAT, the standing wave amplitude starts to change when the center of the EMAT passes the boundary between bonding and debonding areas. It was also revealed that minimum size of the debonding area that EMAT can detect is comparable to its effective area. For accurate evaluation of the debonding area, resonant frequency measurement is recommended at each point

Ordered assembly of Sld3, GINS and Cdc45 is distinctly regulated by DDK and CDK for activation of replication origins

Initiation of chromosome DNA replication in eukaryotes is tightly regulated through assembly of replication factors at replication origins. Here, we investigated dependence of the assembly of the initiation complex on particular factors using temperature-sensitive fission yeast mutants. The psf3-1 mutant, a GINS component mutant, arrested with unreplicated DNA at the restrictive temperature and the DNA content gradually increased, suggesting a defect in DNA replication. The mutation impaired GINS complex formation, as shown by pull-down experiments. Chromatin immunoprecipitation assays indicated that GINS integrity was required for origin loading of Psf2, Cut5 and Cdc45, but not Sld3. In contrast, loading of Psf2 onto origins depended on Sld3 and Cut5 but not on Cdc45. These results suggest that Sld3 functions furthest upstream in initiation complex assembly, followed by GINS and Cut5, then Cdc45. Consistent with this conclusion, Cdc7-Dbf4 kinase (DDK) but not cyclin-dependent kinase (CDK) was required for Sld3 loading, whereas recruitment of the other factors depended on both kinases. These results suggest that DDK and CDK regulate distinct steps in activation of replication origins in fission yeast