Acoustic Emission Analysis of SCS-6 Fiber Fracture in Titanium Matrix Composites

One aspect of successful composite design involves development of a detailed knowledge of damage evolution. In metal matrix composites, cracking and/or plastic deformation of one or more constituents together with fiber-matrix interfacial debonding and sliding generally occur prior to catastrophic failure [1, 2]. The nature and severity of these damage processes controls mechanical performance. In ductile matrix systems having a low fiber-matrix interfacial strength, the failure process can involve successive fragmentation of the fibers with increasing load. Broken fibers shed load (equally among the unbroken fibers in the case of global load sharing) until the fiber fracture density reaches some critical value and the sample catastrophically fails. Characterization of damage development has been slowed by a lack of NDE techniques. Here, the use of acoustic emission (AE) techniques is explored to further understand and quantify failure processes of this type.</p

Isolation, characterization and expression analysis of a hypoxia-responsive glucose transporter gene from the grass carp, Ctenopharyngodon idellus

Glucose transporters (GLUTs) have been implicated in adaptive and survival responses to hypoxic stress in mammals. In fish, the expression and regulation of GLUT in relation to hypoxia remains unexplored. Here we describe the identification of a hypoxia-responsive glucose transporter gene (gcGLUT) and the corresponding full-length cDNA from the grass carp. The gene spans ≈ 11 kb of genomic sequence and consists of 12 exons and 11 introns, and an open reading frame (ORF) of 1599 bp encoding a polypeptide of 533 amino acids, with a predicted molecular mass of ≈ 57 kDa and a pI of 8.34. BLASTX analysis showed that the ORF shared high sequence identity with the GLUT1 (57-59%), GLUT3 (59-60%) and GLUT4 (55-59%) proteins from different vertebrates. Comparative analysis of GLUT genomic structures showed that the arrangement of exons and position of split codons are highly conserved amongst members of the class I GLUTs suggesting that these genes share a common ancestor. Phylogenetic analysis indicated that gcGLUT is most closely related to the GLUT3 proteins. Northern blot analysis showed that the 3.1-kb gcGLUT transcript was most abundantly expressed and responsive to hypoxia in kidney. Up-regulated expression by hypoxia was also evident in eye and gill, but differential patterns of expression were observed. Low expression levels detected in brain, heart, liver and muscle were not responsive to hypoxic stress.link_to_subscribed_fulltex

Measurement of the eta and eta(') transition form factors at q(2)=112 GeV2

We report a study of the processes e+e-→ηγ and e+e-→η′γ at a center-of-mass energy of 10.58 GeV, using a 232fb-1 data sample collected with the BABAR detector at the PEP-II collider at SLAC. We observe 20-5+6ηγ and 50-7+8η′γ events over small backgrounds, and measure the cross sections σ(e+e- →ηγ)=4.5-1.1+1.2±0.3fb and σ(e+e- →η′γ)=5.4±0.8±0.3fb. The corresponding transition form factors at q2=112GeV2 are q2|Fη(q2)|=0.229±0. 030±0.008GeV, and q2|Fη′(q2)|=0.251±0.019±0. 008GeV, respectively. © 2006 The American Physical Society