Significance of Hydroxyl Radical in Photoinduced Oxygen Evolution in Water on Monoclinic Bismuth Vanadate

Understanding the details of the mechanism of water photo-oxidation on monoclinic bismuth vanadate (m-BiVO₄) is intriguing for efficient oxygen (O₂) evolution under solar light. Hydroxyl (OH) radical was confirmed in a photocatalytic system of m-BiVO₄ powders. OH radical is highly reactive to dimerize into hydrogen peroxide (H₂O₂), which is further oxidized into O₂ molecule. Therefore, O₂ evolution from OH radicals could be one of the plausible mechanisms. In the present study, to clarify the significance of O₂ evolution from OH radicals, O₂ molecules and OH radicals were generated by photoelectrochemical water oxidation on m-BiVO₄ electrode. The amounts of O₂ molecules and OH radicals were quantified by using an oxygen meter and a fluorescence probe method, respectively. The current efficiency of the photocurrent for the formation of OH radicals (∼0.06%) was much smaller than that for O₂ evolution (∼100%), indicating that O₂ evolution from OH radicals was not significant on m-BiVO₄

Probability of Two-Step Photoexcitation of Electron from Valence Band to Conduction Band through Doping Level in TiO₂

For an Ir-doped TiO₂ (Ir:TiO₂) photocatalyst, we examined the most dominant electron-transfer path for the visible-light-driven photocatalytic performance. The Ir:TiO₂ photocatalyst showed a much higher photocatalytic activity under visible-light irradiation than nondoped TiO₂ after grafting with the cocatalyst of Fe³⁺. For the Ir:TiO₂ photocatalyst, the two-step photoexcitation of an electron from the valence band to the conduction band through the Ir doping level occurred upon visible-light irradiation, as observed by electron spin resonance spectroscopy. The two-step photoexcitation through the doping level was found to be a more stable process with a lower recombination rate of hole–electron pairs than the two-step photoexcitation process through an oxygen vacancy. Once electrons are photoexcited to the conduction band by the two-step excitation, the electrons can easily transfer to the surface because the conduction band is a continuous electron path, whereas the electrons photoexcited at only the doping level could not easily transfer to the surface because of the discontinuity of this path. The observed two-step photoexcitation from the valence band to the conduction band through the doping level significantly contributes to the enhancement of the photocatalytic performance

Weekly number of admitted leptospirosis cases, cumulative rainfall, mean temperature and flood events.

<p>(upper panel) Time series of the number of leptospirosis cases per week admitted to San Lazaro Hospital. (lower panel) Weekly cumulative rainfall (mm) (vertical bars), weekly mean temperature (°C) (solid line) and flood events (tick marks at the top).</p

Summary statistics of the weekly number of leptospirosis cases admitted to San Lazaro Hospital in Manila, the Philippines in 2001–2012.

<p>Summary statistics of the weekly number of leptospirosis cases admitted to San Lazaro Hospital in Manila, the Philippines in 2001–2012.</p

Assumed causal relationships among rainfall, flood and leptospirosis and other environmental factors.

<p>Assumed causal relationships among rainfall, flood and leptospirosis and other environmental factors.</p

The relationship between flood occurrence and leptospirosis at lags 0 to 7 weeks.

<p>The relationship between flood occurrence and leptospirosis at lags 0 to 7 weeks.</p

Lagged relationships between rainfall and leptospirosis.

<p>(A) Mean fitted relative risk surface over lag and weekly rainfall (flood-unadjusted model), (B) Cross-sectional plots of Fig 3(A) at constant lag / rainfall values with relative risk (RR) (solid red line) and 95% CIs (gray area) and (C) Cross-sectional plots at constant lag / rainfall values (flood-adjusted model) with relative risk (RR) (dotted blue line) and 95% CIs (gray area).</p

Effectiveness of primary series, first, and second booster vaccination of monovalent mRNA COVID-19 vaccines against symptomatic SARS-CoV-2 infections and severe diseases during the SARS-CoV-2 omicron BA.5 epidemic in Japan: vaccine effectiveness real-time surveillance for SARS-CoV-2 (VERSUS)

This study aimed to evaluate VE of primary, first, and second booster ancestral-strain monovalent mRNA COVID-19 vaccination against symptomatic infections and severe diseases in Japan. We conducted a test-negative case-control study. We included medically attended episodes and hospitalizations involving individuals aged ≥16 with signs and symptoms from July to November 2022, when Omicron BA.5 was dominant nationwide. To evaluate VE, we calculated adjusted ORs of vaccination among test-positive versus test-negative individuals using a mixed-effects logistic regression. For VE against symptomatic infections among individuals aged 16 to 59, VE of primary vaccination at > 180 days was 26.1% (95% CI: 10.6–38.8%); VE of the first booster was 58.5% (48.4–66.7%) at ≤90 days, decreasing to 41.1% (29.5–50.8%) at 91 to 180 days. For individuals aged ≥60, VE of the first booster was 42.8% (1.7–66.7%) at ≤90 days, dropping to 15.4% (−25.9–43.2%) at 91 to 180 days, and then increasing to 44.0% (16.4–62.5%) after the second booster. For VE against severe diseases, VE of the first and second booster was 77.3% (61.2–86.7%) at ≤90 days and 55.9% (23.4–74.6%) afterward. mRNA booster vaccination provided moderate protection against symptomatic infections and high-level protection against severe diseases during the BA.5 epidemic in Japan.</p