Air separation via two-step solar thermochemical cycles based on SrFeO3-δ and (Ba,La)0.15Sr0.85FeO3-δ perovskite reduction/oxidation reactions to produce N2: rate limiting mechanism(s) determination.

Two-step solar thermochemical cycles based on reversible reactions of SrFeO3-δ and (Ba,La)0.15Sr0.85FeO3-δ perovskites were considered for air separation. The cycle steps encompass (1) the thermal reduction of SrFeO3-δ or (Ba,La)0.15Sr0.85FeO3-δ perovskites driven by concentrated solar irradiation and (2) oxidation in air to remove O2 and produce N2. Rate limiting mechanisms were examined for both reactions using a combination of isothermal and non-isothermal thermogravimetry for temperature-swings between 673 and 1373 K, heating rates of 10, 20, and 50 K min-1, and O2 pressure-swings between 20% O2/Ar and 100% Ar at atmospheric pressure. Evolved O2 and associated lag due to transport behavior were measured with gas chromatography and used with measured sample temperatures to predict equilibrium compositions from a compound energy formalism thermodynamic model. Measured and predicted chemical equilibrium changes in deviation from stoichiometry were compared. Rapid chemical kinetics were observed as the samples equilibrated rapidly for all conditions, indicative that heat and mass transfer were the rate limiting mechanisms. The effects of bulk diffusion (or gas diffusion through the bed or pellet) were examined using pelletized and loose powdered samples and determined to have no discernable impact.

An A- and B-Site Substitutional Study of SrFeO3-δ Perovskites for Solar Thermochemical Air Separation.

An A­ and B­site substitutional study of SrFeO3-δ perovskites (A'xA1-xB'yB1-yO3-δ, where A = Sr and B = Fe) was performed for a two­step solar thermochemical air separation cycle. The cycle steps encompass (1) the thermal reduction of A'xSr1-xB'yFe1-yO3-δ driven by concentrated solar irradiation and (2) the oxidation of A'xSr1-xB'yFe1-yO3-δ in air to remove O2, leaving N2. The oxidized A'xSr1-xB'yFe1-yO3-δ is recycled back to the first step to complete the cycle, resulting in the separation of N2 from air and concentrated solar irradiation. A-site substitution fractions between 0 ≤ x ≤ 0.2 were examined for A' = Ba, Ca, and La. B-site substitution fractions between 0 ≤ y ≤ 0.2 were examined for B' = Cr, Cu, Co, and Mn. Samples were prepared with a modified Pechini method and characterized with X-ray diffractometry. The mass changes and deviations from stoichiometry were evaluated with thermogravimetry in three screenings with temperature- and O2 pressure-swings between 573 and 1473 K and 20% O2/Ar and 100% Ar at 1 bar, respectively. A' = Ba or La and B' = Co resulted in the most improved redox capacities amongst temperature- and O2 pressure-swing experiments.

Metastasis, Mortality, and Quality of Life for Men With NCCN High and Very High Risk Localized Prostate Cancer After Surgical and/or Combined Modality Radiotherapy.

PURPOSE: To compare metastasis-free survival, overall survival, and patient-reported quality of life (QOL) of men with National Comprehensive Cancer Network high or very high risk prostate cancer after definitive surgery and/or multimodal radiotherapy (RT). PATIENTS AND METHODS: We studied a retrospective cohort study of 586 patients treated between the years 2000 and 2017 receiving radical prostatectomy with or without postoperative RT, external-beam RT (EBRT) with androgen deprivation therapy (ADT), or EBRT plus brachytherapy (Brachy) boost + ADT. Patient-reported QOL for urinary, bowel, sexual, and overall physical and mental functioning was assessed using the American Urological Association symptom scale, the Sexual Health Inventory in Men, the Rectal-Function Assessment Scale, the Expanded Prostate Cancer Index Composite, and the Veterans RAND 12-Item Health Survey. RESULTS: Median follow-up for survival was 5 years. No significant differences between the treatments were observed for overall survival or metastasis-free survival at the P < .05 threshold. The propensity-adjusted 5-year metastasis-free survival estimates for EBRT + ADT, EBRT + Brachy + ADT, and surgery were 74.6%, 94.8%, and 83.1%, respectively. The EBRT + Brachy + ADT and surgery cohorts had significantly worse mean American Urological Association symptom scores at 6 months than the EBRT + ADT cohort, which resolved by 1 year. Surgical patients had better rectal function scores than EBRT + ADT patients at years 1 to 3, but similar function thereafter. Adjuvant or salvage RT resulted in significant declines in various Expanded Prostate Cancer Index Composite urinary, sexual, and bowel domains, and Veterans RAND 12-Item Health Survey physical but not mental domains. CONCLUSION: Men with very and/or high-risk localized prostate cancer are likely to require multimodal therapy. The overall differences in survival and long-term QOL are similar for men choosing surgical versus RT pathways.