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Purpose To compare the performance and interobserver agreement of the COVID-19 Reporting and Data System (CO-RADS), the COVID-19 imaging reporting and data system (COVID-RADS), the RSNA expert consensus statement, and the British Society of Thoracic Imaging (BSTI) guidance statement. Materials and Methods In this case-control study, total of 100 symptomatic patients suspected of having COVID-19 were included: 50 patients with COVID-19 (59±17 years, 38 men) and 50 patients without COVID-19 (65±24 years, 30 men). Eight radiologists independently scored chest CT images of the cohort according to each reporting system. The area under the receiver operating characteristic curves (AUC) and interobserver agreements were calculated and statistically compared across the systems. Results A total of 800 observations were made for each system. The level of suspicion of COVID-19 correlated with the RT-PCR positive rate except for the “negative for pneumonia” classifications in all the systems (Spearman’s coefficient: ρ=1.0, P=

A sharp initial crack tip is required for measuring the fracture toughness or energy release rate of adhesive joints, especially at cryogenic temperatures because a blunt initial crack tip in the adhesive may lead to a higher value of fracture toughness than a sharp initial crack tip. Although ASTM D3433 standard specifies how to measure the fracture toughness of adhesive layers in bonded joints, it does not state the way to generate crack tips. In this work, the fracture toughness of adhesive joints was measured at the cryogenic temperature of −150°C with respect to the crack generation method and location of the initial crack, and compared to that at 25°C. From the experimental results, it was concluded that an initial sharp crack tip should be generated in the adhesive region to measure accurately the energy release rate of the adhesively bonded joint. Also, the fracture toughness of the adhesive joint at the cryogenic temperature of −150°C should be measured with respect to crack tip location.

Fracture toughness and crack resistance of aluminum adhesive joints were measured at the cryogenic temperature of −150°C, with respect to the orientation and volume fraction of the E-glass fibers in the epoxy adhesive. Cleavage tests on the DCB (Double Cantilever Beam) adhesive joints were performed using two different test rates of 1.67 × 10−2 and 8.33 × 10−4 mm/s to observe the crack propagation trends. From the experiments, it was found that the DCB joints bonded with the epoxy adhesive reinforced with E-glass fibers not only showed a stable crack propagation with a low crack propagation speed, but also higher fracture toughness and crack resistance than those of the DCB joints bonded with the unreinforced epoxy adhesive at a cryogenic temperature of −150°C.

Since metal foils such as aluminum, copper or nickel foils have been used in composite structures for radiation shielding and EMI protection in space environments, high adhesive bonding strength and durability between metal foils and composites under large temperature variations are very important. In this study, the strength of co-cure bonded joint between an aluminum foil and a composite has been investigated, with three different aluminum surface treatments such as standard PAA (Phosphoric Acid Anodization) procedure, abrasion with sandpaper, and carbon black pasting on the metal foils. From the double cantilever beam (DCB) tests, it was found that the interlaminar peel strength with carbon black pasting improved 60% compared to the laminate without any surface treatment. Also it was found that the interlaminar peel strength of the co-cure carbon/epoxy composite-aluminum foil hybrid laminate with the carbon black pasting on the aluminum foil did not decrease after many thermal cycles from 30°C to –196°C.