Fatigue performance and durability of structural adhesive joints

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Prion disease tempo determined by host-dependent substrate reduction

The symptoms of prion infection can take years or decades to manifest following the initial exposure. Molecular markers of prion disease include accumulation of the misfolded prion protein (PrPSc), which is derived from its cellular precursor (PrPC), as well as downregulation of the PrP-like Shadoo (Sho) glycoprotein. Given the overlapping cellular environments for PrPC and Sho, we inferred that PrPC levels might also be altered as part of a host response during prion infection. Using rodent models, we found that, in addition to changes in PrPC glycosylation and proteolytic processing, net reductions in PrPC occur in a wide range of prion diseases, including sheep scrapie, human Creutzfeldt-Jakob disease, and cervid chronic wasting disease. The reduction in PrPC results in decreased prion replication, as measured by the protein misfolding cyclic amplification technique for generating PrPSc in vitro. While PrPC downregulation is not discernible in animals with unusually short incubation periods and high PrPC expression, slowly evolving prion infections exhibit downregulation of the PrPC substrate required for new PrPSc synthesis and as a receptor for pathogenic signaling. Our data reveal PrPC downregulation as a previously unappreciated element of disease pathogenesis that defines the extensive, presymptomatic period for many prion strain

Blast testing of RC slabs retrofitted with NSM CFRP plates

In this paper, blast testing was performed on two reinforced concrete specimens: a plain reinforced concrete (RC) specimen; and an identical RC specimen retrofitted with near surface mounted (NSM) carbon fibre reinforced polymer (CFRP) plates. Each specimen was subjected to two separate explosive loads at a standoff distance of 0.6m, with the aim of investigating the performances of both specimens within both their elastic and plastic response ranges. The first blast (Blast 1) and second blast (Blast 2) consisted of an equivalent TNT charge weight of 0.079kg and 2.09kg respectively. The elastic-range responses of both specimens after the small shot (Blast 1), such as acceleration and deflection were obtained and comparisons were made between the specimens. The plastic performances of both specimens, such as tension face scabbing, crack patterns, plastic hinges and permanent deflection, after the large shot (Blast 2) were also analysed and compared. A number of unique failures and behaviours of both specimens were observed, investigated and analyzed. The test results provide a vital direction in the development of an optimal retrofit in future research.Chengqing Wu, Deric John Oehlers, John Wachl, Craig Glynn, Adrian Spencer, Matthew Merrigan, Ian Da

Layered Blast Capacity Analysis of FRP Retrofitted RC Member

Fibre reinforced polymer (FRP) retrofitting of RC structures against blast loading is an emerging research area of major significance. Currently, several guidelines are available for the FRP retrofitting of RC structures against monotonic and seismic loads. However, no advice is provided from these guidelines for the retrofit RC structures against blast loading. This paper formulates a layered model that allows for both FRP strengthening and the consideration of strain rate effects on the blast resistant capacity of flexural structural members. The layered model is incorporated into a single degree of freedom model for dynamic analyses and it is validated with blast tests. The validated model is then used in a parametric study which investigates the changes in strength, ductility and energy absorption capacities of flexural FRP strengthened members under blast loads. It is found that the capacity of a flexural member to resist a blast load can be increased greatly with the use of compressive face plating with the ductility of the flexural member being the key factor.Chengqing Wu, Deric John Oehlers and Ian Da