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Purpose: To design a patient specific quality assurance (PSQA) process for the CyberKnife Synchrony system and quantify its dosimetric accuracy using a motion platform driven by patient tumor traces with rotation. Methods: The CyberKnife Synchrony system was evaluated using a motion platform (MODUSQA) and a SRS MapCHECK phantom. The platform was programed to move in the superior‐inferior (SI) direction based on tumor traces. The detector array housed by the StereoPhan was placed on the platform. Extra rotational angles in pitch (head down, 4.0° ± 0.15° or 1.2° ± 0.1°) were added to the moving phantom to examine robot capability of angle correction during delivery. A total of 15 Synchrony patients were performed SBRT PSQA on the moving phantom. All the results were benchmarked by the PSQA results based on static phantom. Results: For smaller pitch angles, the mean gamma passing rates were 99.75% ± 0.87%, 98.63% ± 2.05%, and 93.11% ± 5.52%, for 3%/1 mm, 2%/1 mm, and 1%/1 mm, respectively. Large discrepancy in the passing rates was observed for different pitch angles due to limited angle correction by the robot. For larger pitch angles, the corresponding mean passing rates were dropped to 93.00% ± 10.91%, 88.05% ± 14.93%, and 80.38% ± 17.40%. When comparing with the static phantom, no significant statistic difference was observed for smaller pitch angles (p = 0.1 for 3%/1 mm), whereas a larger statistic difference was observed for larger pitch angles (p < 0.02 for all criteria). All the gamma passing rates were improved, if applying shift and rotation correction. Conclusions: The significance of this work is that it is the first study to benchmark PSQA for the CyberKnife Synchrony system using realistically moving phantoms with rotation. With reasonable delivery time, we found it may be feasible to perform PSQA for Synchrony patients with a realistic breathing pattern. [ABSTRACT FROM AUTHOR]

The creep characteristics of a composite geomembrane under different load levels were investigated by conducting a laboratory creep test for 2,100 h under 15 load levels from 10% to 80%. Test results showed that deformation increased rapidly when a load was applied, and the change in strain decreased gradually with an increase in time. The higher the load level, the higher the creep deformation and creep rate. When the load level was lower than or equal to 40%, the creep strain of the composite geomembrane increased linearly. When the load level was higher than or equal to 45%, the creep strain increase followed a quadratic function. When the load level was 40%–45%, the creep strain changed under the influence of the deformation characteristics of the composite material. Based on the creep test data, a piecewise empirical creep model with load level and time as parameters was established. The three-parameter and four-parameter viscoelastic constitutive models reflecting the creep properties were compared and analyzed, and it was found that the four-parameter model better reflected the creep characteristics of the composite geomembrane. [ABSTRACT FROM AUTHOR]

More catalytic active sites and fast interfacial charge transfer rates have been shown to be effective strategies to enhance photocatalytic water decomposition. In this work, a microconical textured silicon wafer was constructed by wet chemical etching. Fe3O4 nanospheres and NixSy (NiS and Ni3S4 complexes) nanoclusters were prepared by solvothermal method, and Fe3O4 and NixSy were deposited on Si micropyramids (denoted as Fe3O4/NiS/Ni3S4@SiMPs) by drop-coating methods. Fe3O4/NiS/Ni3S4@SiMPs exhibited excellent photoelectrochemical properties and good stability at the composite ratio of Fe3O4 to NixSy was 1:5, and the starting potential of the composite was 0.29 V vs.RHE, maximum photohydrogen conversion efficiency was 0.32% (+ 1.21 V vs. RHE), photocurrent density was 0.82 mA cm−2. Fe3O4/NiS/Ni3S4@SiMPs exhibited 42 times higher photocurrent density than NixSy@SiMPs with long-term stability was up to 4 h. The results show that Fe3O4 significantly improved the photoelectrochemical performance of NixSy@SiMPs composites, mainly because that Fe3O4 nanospheres have high conductivity contributing to photogenerated carrier migration, and the heterojunction between semiconductors with different energy levels (Fe3O4, NixSy, Si) effectively inhibited the recombination of electrons and holes. This work provides directions for the preparation and photoelectrochemical properties of monocrystalline silicon-based supported NixSy and Fe3O4 composites. [ABSTRACT FROM AUTHOR]

The construction of a highly efficient (photo)electrocatalyst plays a key role in improving (photo)electrocatalytic water-splitting performance. Herein, SbVO4 and MoS2 were prepared by the hydrothermal method. The prepared SbVO4 and MoS2 nanoparticles were further co-deposited on Co foams (denoted as SbVO4/MoS2@Co) and used as (photo)electrocatalysts. The SbVO4/MoS2@Co exhibited a high electrocatalytic oxygen evolution reaction (OER) at a current density of 50 mA cm−2 with an overpotential of 217 mV, which was 3.6 times lower than that of SbVO4@Co without MoS2, and the Tafel slope was 20.2 mV dec−1. SbVO4/MoS2@Co also demonstrated excellent photoelectrochemical (PEC) performance and stability. Under AM 1.5G simulated solar illumination, when the potential was 1.24 V vs. reversible hydrogen electrode (RHE), the maximum integrated solar thermal cycle (ISTC) conversion efficiency was about 0.38% (0.15% higher than that of SbVO4@Co) with a photocurrent density of 138 mA cm−2. The catalyst has a long-term stability up to 18 h. The excellent (photo)electrochemical performance of SbVO4/MoS2@Co was mainly due to the synergistic effect between SbVO4/MoS2 heterostructure and the cobalt matrix of the foam, increasing light absorption and facilitating charge and mass transport. [ABSTRACT FROM AUTHOR]