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Graphical Abstract Highlights  VUV/UV/persulfate (VUV/UV/PS) process obviously enhanced methylene blue degradation. VUV UV HO • other SO 4 •-J o u r n a l P r e -p r o o f  Degradation and mineralization of methylene blue exhibited different trends with pH. HO • and SO4 •were proved to be the principal reactive oxygen species. The application potential of VUV/UV/PS process was demonstrated in real waters. Solution pH notably affected photon absorption distributions and reaction mechanism. AbstractThis study investigated methylene blue (MB) degradation by the vacuumultraviolet/ultraviolet/persulfate (VUV/UV/PS) process using a mini-fluidic VUV/UV photoreaction system. Results show that MB degradation by the VUV/UV/PS process was significantly higher than that of the conventional UV/PS process, as the VUV photolysis of H2O and PS generated more reactive oxygen species (ROSs). HO • and SO4 •-, identified as the main ROSs, were mostly consumed by dissolved organic carbon and Clin real waters, respectively. Additionally, the impacts of solution pH and the concentrations of PS, humic acid, and inorganic ions (HCO3 -, Cl -, NO3 -, SO4 2-, Fe(II), and Fe(III)) were systematically evaluated. The solution pH significantly affected the photon absorption distributions, as well as the contributions of photolysis and oxidation to MB degradation, resulting in different variations in the degradation rate constant and total organic carbon removal ratio with increasing solution pH. At all tested pH levels (3.0-11.0), particularly under acidic conditions, HO • and SO4 •were two predominant contributors to MB degradation, while VUV and UV photolysis contributed more when the solution pH increased. This study provides a highly efficient process for organic J o u r n a l P r e -p r o o f pollutant removal, which could be applied in water treatment. S O 2 SO ( 1.4) hv        (1) Low-pressure (LP) mercury lamps are a highly efficient UV light source for water treatment, with a photon-energy efficiency of approximately 36% [12]. By using J o u r n a l P r e -p r o o f

Laser speckle contrast imaging is a full-field imaging technique for measuring blood flow by mapping the speckle contrast with high spatial and temporal resolution. However, the statically scattered light from stationary tissues seriously degrades the accuracy of flow speed estimation. In this Letter, we present a simple calibration approach to calculate the proportions of dynamically scattered light and correct the effect of static scattering with single exposure time. Both the phantom and animal experimental results suggest that this calibration approach has the ability to improve the estimation of the relative blood flow in the presence of static scattering.

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Kinetic comparisons of micropollutant degradation by ultraviolet (UV) based advanced oxidation processes among various radiation sources are an important issue, yet this is still a challenge at present. This study investigated comparatively the kinetics of sulfamethazine (SMN) degradation by the UV/H2O2 process among three representative radiation sources, including low-pressure mercury UV (LPUV, monochromatic), medium-pressure mercury UV (MPUV, polychromatic), and vacuum UV­(VUV)/UV (dual wavelengths causing different reaction mechanisms) lamps. Experiments were conducted with a newly developed mini-fluidic MPUV photoreaction system and a previously developed mini-fluidic VUV/UV photoreaction system. Measured and modeled results both indicate that the photon fluence-based SMN degradation rate constant (k p ′) followed a descending order of VUV/UV/H2O2 > MPUV/H2O2 (200–300 nm) > LPUV/H2O2, and the k p ′ of the MPUV lamp was dependent on the wavelength range selected for photon fluence calculation. Analysis of potential errors revealed that a shorter effective path-length could have a lower error, and the maximum errors for the MPUV/H2O2 and LPUV/H2O2 processes in this study were 7.7% and 18.2%, respectively. This study has developed a new method for kinetic comparisons of micropollutant degradation by UV-AOPs among various radiation sources at bench-scale, which provides useful reference to practical applications.

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