This report presents the materials property data of additively manufactured (AM) 316L stainless steel (SS) accumulated for the assessment of core materials in the Transformational Challenge Reactor (TCR) program. The TCR manufacturing approach includes using the laser powder bed fusion (LPBF) method for metallic (316L and Inconel 718) components. To assess the mechanical performance of printed components in reactor-relevant conditions and build a property database for the AM materials, mechanical tests and evaluations were performed before and after neutron irradiation. Miniature tensile specimens were irradiated in the High Flux Isotope Reactor to 0.2, 2, 8, and 10 dpa at target temperatures of 300 and 600°C. Postirradiation evaluation for the 0.2 and 2 dpa specimens was performed during FY20 and FY21, and the results are presented and discussed in this document.To obtain the baseline mechanical property data, uniaxial tension testing over a wide temperature range from room temperature (RT) to 600°C was performed for the same materials that were irradiated, including AM 316L SS in the as-built, stress-relieved, and solution-annealed conditions, as well as reference wrought (WT) 316L SS. Regardless of the postbuild heat treatment, the AM 316L SS showed higher strength than the WT 316L SS, but they had similar ductility. A statistical treatment of RT tensile data indicated that variations in the strength and ductility datasets of AM 316L steels were smaller than or similar to those of WT 316L SS. Additionally, 2D mapping of tensile properties for the stress-relieved AM plates also showed clear location dependence of the properties but with limited magnitudes.Postirradiation tensile testing was conducted at RT, 300, 500, and 600°C for selected irradiation conditions. Additional tests were performed near the measured irradiation temperatures of 260 and 390°C for checking the impact of the difference between the targeted and actual irradiation temperatures. Neutron irradiation induced significant changes in the mechanical behavior of the AM SSs, including hardening and softening. Although the as-built 316L SS tested at 300°C after irradiation to 2 dpa at 390°C showed unstable plastic deformation (i.e., necking) immediately after yielding, the overall property changes of the as-printed alloy became much less significant after higher temperature (610 and 690°C) irradiations or when tested at different temperatures. Irradiation-induced ductilization was also observed in the higher strength materials (i.e., in as-built and stress-relieved conditions) after higher temperature (>600°C) irradiations. The strength change after irradiation was generally smaller in the relatively stronger materials (i.e., the as-built and stress-relieved AM SSs) than in the solution-annealed AM and WT SSs. Overall, these relatively lower strength 316L SSs retained higher ductility in the irradiation conditions tested, but the stronger 316L SSs demonstrated a similar level of ductility after higher temperature irradiations. For the AM 316L mate...
BackgroundBloodstream infections (BSI) due to Enterobacteriaceae often require empiric intravenous (IV) antibiotics. Oral antibiotics for the definitive treatment of these infections have been reserved to antibiotics with “high” oral bioavailability, mainly fluoroquinolones (FQ). Safety concerns and increasing resistance associated with FQ has modified clinical practice to identify alternative oral therapies. Select β-lactam (BL) antibiotics are well-tolerated, have moderately high bioavailability, and possess in-vitro activity against Escherichia coli (E. coli), Klebsiella pneumoniae (K. pneumoniae), and Proteus mirabilis (P. mirabilis). Limited evidence exists for oral BL step-down therapy for definitive treatment of BSI due to these organisms.MethodsThis retrospective cohort study compares clinical outcomes of patients treated with oral BL antibiotics to those who received oral FQ or trimethoprim/sulfamethoxazole (TS) for the treatment of BSI due to E. coli, K. pneumoniae, and P. mirabilis. The primary outcome is a composite of 30-day all-cause mortality, 30-day readmission due to recurrence, and/or change in oral antibiotic therapy. Secondary endpoints include 90-day development of Clostridium difficile infection, 90-day all-cause readmission, hospital length of stay (LOS), and 90-day recovery of a multi-drug-resistant organism.ResultsNine hundred eighty-one patients were screened and 397 adult patients were included. Excluded patients: IV only (n = 291), polymicrobial blood culture (n = 112), immunocompromised (n = 61), other (n = 120). Two-hundred patients received oral step-down therapy with a BL, and 197 with either an FQ or TS. E. coli was the causative organism for most patients in both groups, and urinary tract was the most common source of BSI. The median total duration of therapy was 14 days in both groups. There was no significant difference in the primary composite endpoint (7% vs. 5.6%, P = 0.561). There was no mortality or differences in secondary outcomes, except LOS (6 vs. 5 days, P = 0.043).ConclusionUtilization of oral BL for the step-down therapy of uncomplicated BSI due to E. coli, K. pneumoniae, and P. mirabilis did not result in worse outcomes compared with those receiving oral FQ or TS.Disclosures All authors: No reported disclosures.
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