Improvement of Fatigue Life of GH3039 Superalloy by Laser Shock Peening

In order to improve fatigue life of GH3039 superalloy, GH3039 superalloy sheets were treated by laser shock peening (LSP). The microstructure of GH3039 superalloy before and after LSP was characterized using an optical microscope, transmission electron microscope (TEM), and X-ray diffractometer. The fatigue life of the samples with and without LSP was investigated by fatigue experiments. Moreover, surface profile and residual stress were also examined. Experimental results indicated that the grains in the surface layer of the LSP sample were remarkably refined and reached the nanometer scale. The average surface roughness increased from 0.024 μm to 0.19 μm after LSP. The average fatigue life of the laser treated samples was 2.01 times larger than that of the untreated specimens. Additionally, mathematical statistical analysis confirms that LSP has a significant influence on the fatigue life of GH3039 superalloy. The improvement of fatigue life for the laser processed GH3039 superalloy was mainly attributed to compressive residual stress and grain refinement generated by LSP

Fifteen novel microsatellite markers for rock shell (Thais clavigera)

Public Welfare Project of State Oceanic Administration [201205024-2]Rock shell (Thais clavigera), a common neogastropod snail, is not only an organism with important pharmaceutical values but also a favorable biological indicator useful for monitoring contamination of metals and tributyltin. However, its wild population has been overharvested and its natural habitat has been destroyed. Thus, establishment of conservation strategy of T. clavigera is urgently needed. To provide genetic information required for this purpose, we isolated fifteen novel polymorphic microsatellite loci of T. clavigera. The number of allele per locus varied from 3 to 17. The expected and observed heterozygosity ranged from 0.3439 to 0.9128 and 0.3333 to 0.8611, respectively. Three loci (TCA44, TCA117 and TCA134) showed significant deviations from Hardy-Weinberg equilibrium after Bonferroni corrections and no linkage disequilibrium was detected. We expect these loci could be further applied in population genetics studies, which could benefit the conservation of this species

Complete Mitogenomes of <i>Polypedates</i> Tree Frogs Unveil Gene Rearrangement and Concerted Evolution within Rhacophoridae

New developments in sequencing technology and nucleotide analysis have allowed us to make great advances in reconstructing anuran phylogeny. As a clade of representative amphibians that have radiated from aquatic to arboreal habitats, our understanding of the systematic status and molecular biology of rhacophorid tree frogs is still limited. We determined two new mitogenomes for the genus Polypedates (Rhacophoridae): P. impresus and P. mutus. We conducted comparative and phylogenetic analyses using our data and seven other rhacophorid mitogenomes. The mitogenomes of the genera Polypedates, Buergeria, and Zhangixalus were almost identical, except that the ATP8 gene in Polypedates had become a non-coding region; Buergeria maintained the legacy “LTPF” tRNA gene cluster compared to the novel “TLPF” order in the other two genera; and B. buergeri and Z. dennysi had no control region (CR) duplication. The resulting phylogenetic relationship supporting the above gene rearrangement pathway suggested parallel evolution of ATP8 gene loss of function (LoF) in Polypedates and CR duplication with concerted evolution of paralogous CRs in rhacophorids. Finally, conflicting topologies in the phylograms of 185 species reflected the advantages of phylogenetic analyses using multiple loci