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Copyright of Journal of Natural Fibers is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of the paper is to show the importance of the acoustic attenuation and probe frequency for the reliable evaluation of delaminations on composite materials subjected to NDI ultrasonic investigation.An original ultrasonic NDI methodology has been applied to some composite materials of wide application, characterized by a high acoustic attenuation. The materials are based on Kevlar/polyester and glass/polyester systems; the fiber form is woven fabric, and the thicknesses are between 5 and 6 mm. All the specimens are made by RTM technology. The specimens have been subjected to low-velocity impact tests, and then the extension of delaminated areas has been evaluated.The ultrasonic test apparatus operates in the form of reflection, using two different probes at 5 and 15 MHz. The results point out how the higher frequency probe has a greater resolution and higher sensibility; nevertheless, the higher attenuation at 15 MHz causes a lower inspection depth along the specimen thickness. Thus, for materials with high attenuation the 5 MHz probe is preferable in order to have accurate ultrasonic maps along the thickness and reliable values for the delaminated areas. [ABSTRACT FROM PUBLISHER]

AbstractThe routes through which Norway spruce recolonized the Alps after the last ice age were investigated at the genetic level. Seven populations along the Alpine range plus one Apennine population were characterized for seven sequence-characterized amplified region (SCAR) loci, detecting an overall FST = 0.118. This rather high value for forest species reflects an uneven distribution of genetic variability, and was analysed through different statistical methods. Alternative hypotheses were tested under the isolation-by-distance model and using the analysis of molecular variance (amova) frame. We conclude that the hypothesis of the existence of a glacial refugium in the Apennines should be rejected, while a putative relict population is identified in the Maritime Alps. The Alpine range of Norway spruce appears to be split in two parts across a north–south line. The results are discussed in comparison with data based on morphological markers, isozymes, chloroplast microsatellites and mitochondrial markers. [ABSTRACT FROM AUTHOR]

Studies men with idiopathic azoospermia and severe oligozoospermia, cytogenically normal, for the presence of microdeletions on Yq chromosome. Defects in spermatogenesis in association with deletions of different portions of Y chromosome long arm (Yq); Use of polymerase chain reaction (PCR) and Southern blotting techniques to analyze loci on Yq; Deletions in association with defects in spermatogenesis.

Copyright of Meccanica is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of the present paper is to evaluate the tensile strength reduction of angle-ply composite laminates due to low-velocity impact. Three angle ply lay-up were chosen: [+30',-300]2s, [+45',-45oI2s and +60',[-60]2s. Impact tests were performed at different impact energy level and then an ultrasonic scan NDI was performed, to evaluate the internal damage. The impacted specimens were subjected to tensile load until failure occurs and the ultimate tension strength after impact was compared with the corresponding value for undamaged specimens.Moreover, for a better understanding of the failure phenomenon, some tension tests for damaged specimens were interrupted at different load levels (respectively at 30%, 60%, 85% and 90% of the corresponding failure load) and ultrasonic scans at any step were performed to evaluate the delamination growth due to tensile load. A correlation between the amount of delamination areas and the impact energy has been determined. [ABSTRACT FROM PUBLISHER]