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Highlights • Independent f t and K IC can be determined by using various concrete specimens. • Average Δ a fic ≈ 1.0 d max can be assumed for 3-p-b and WS concrete specimens. • Structural failure of concrete can be constructed by using independent f t and K IC. • Safe design diagrams with limits (±15%) can cover all experimental results. • Theoretical specimen size meeting linear elastic fracture mechanics are obtained. • Predicted peak loads using the Δ a fic ≈ 1.0 d max fit experimental peak loads. Abstract Concrete tensile strength and fracture toughness are two important material constants that should be independent of specimen size, geometry or type. In this study, on the basis of the improved boundary effect model, independent tensile strength and fracture toughness of concrete, which are unaffected by the specimen type, were determined by using various specimens, e.g., three-point-bending and wedge-splitting specimens. The concrete structural failure was fully predicted using independent material constants, and the constructed safe design diagrams with upper and lower limits (±15%) can cover all experimental results. The theoretical minimum size of the concrete meeting the linear elastic fracture mechanics were quantified, and the peak loads of concrete specimens were predicted using various average fictitious crack growth length. [ABSTRACT FROM AUTHOR]

We evaluated the field diagnostic accuracy of a syphilis rapid test (RDT), using serum and whole blood by non-laboratorians in two Canadian Arctic communities. We implemented a multisite prospective field evaluation wherein patients were screened by an RDT containing treponemal and non-treponemal components (Chembio DPP® Syphilis Screen & Confirm) between January 2020 and December 2021. Venous whole blood and serum were collected for rapid testing and compared with laboratory-based serology reference testing using a reverse sequence algorithm of treponemal and rapid plasma reagin (RPR) testing. Overall, 135 whole blood and 139 serum specimens were collected from 161 participants during clinical encounters. Treponemal-RDT sensitivity against a treponemal-reference standard (38/161 confirmed cases) was similar for serum (78% [95% CI: 61–90%]) and whole blood (81% [95% CI: 63–93%]). In those with RPR titres ≥1:8 (i.e. suggestive of recent/active infection), sensitivity increased to 93% (95% CI: 77–99%) for serum and 92% (95% CI: 73–99%) for whole blood. Treponemal-RDT specificity was excellent (99% [95% CI: 95–100%]) for both specimen types. Non-treponemal-RDT sensitivity against RPR was 94% (95% CI: 80–99%) for serum and 79% (95% CI: 60–92%) for whole blood. Sensitivity increased to 100% (95% CI: 88–100%) for serum and 92% (95% CI: 73–99%) for whole blood when RPR titres ≥1:8. RDT performance with whole blood was similar to that with serum. Non-laboratorians using the RDT accurately identified individuals with infectious syphilis under real-world conditions in an intended-use setting at the point of care. Implementing the RDT can eliminate treatment delays and may enhance disease control. [ABSTRACT FROM AUTHOR]

• Modified CDC-based assays can detect SARS-CoV-2 across a range of sample types. • SARS-CoV-2 N1 assay detection sensitivity was comparable between specimen types. • Of the specimen types detected using the N2 assay, CSF was the most sensitive. Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has caused considerable disruption across the world, resulting in more than 235,000 deaths since December 2019. SARS-CoV-2 has a wide tropism and detection of the virus has been described in multiple specimen types, including various respiratory secretions, cerebrospinal fluid, and stool. To evaluate the accuracy and sensitivity of a laboratory modified CDCbased SARS-CoV-2 N1 and N2 assay across a range of sample types. Study Design We compared the matrix effect on the analytical sensitivity of SARS-CoV-2 detection by qRT-PCR in nasal swabs collected in viral transport medium (VTM), bronchoalveolar lavage (BAL), sputum, plasma, cerebral spinal fluid (CSF), stool, VTM, phosphate buffered saline (PBS), and Hanks' Balanced Salt Solution (HBSS). Initial limits of detection (LoD) were subsequently narrowed to confirm an LoD for each specimen type and target gene. LoDs were established using a modified CDC-based laboratory developed test and ranged from a mean CT cut-off of 33.8–35.7 (10–20 copies/reaction) for the N1 gene target, and 34.0–36.2 (1–10 copies/reaction) for N2. Alternatives to VTM such as PBS and HBSS had comparable LoDs. The N2 gene target was found to be most sensitive in CSF. A modified CDC-based laboratory developed test is able to detect SARSCoV- 2 accurately with similar sensitivity across all sample types tested. [ABSTRACT FROM AUTHOR]