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Objective: Compared the dosimetric characteristics of half-field-based VMAT and half-field-based IMRT for left breast cancer patients combined with deep inspiration breath-hold (DIBH) and free breathing (FB) techniques. Methods: Twenty-one left breast cancer patients were included. Each patient underwent DIBH and FB CT scans, IMRT and VMAT plans in half-field beam mode for both breathing techniques, resulting in four plans: FB-IMRT (F-IMRT), FB-VMAT (F-VMAT), DIBH-IMRT (D-IMRT) and DIBH-VMAT (D-VMAT). The conformity index (CI), homogeneity index (HI), and the doses received at the heart, left anterior descending (LAD), left lung, right breast, and right lung, were compared among plans.The correlation between the difference in the volume of lung_L (ΔLVL) and the difference in the mean dose (ΔDmean) of lung_L under the DIBH and FB plans, the correlation between the difference in the heart-chest distance (ΔHCD) and the ΔDmean of the heart,LAD under the DIBH and FB plans. Results: The D-VMAT plan lower lung_L V5 than both the F-IMRT and F-VMAT plans (p <0.05), The D-VMAT plan lower values for V10, V20, V30, and Dmean than did the other plans (p < 0.05). For the heart, the D-VMAT plan lower V5, V10, V20, and Dmean values than did the other plans (p < 0.05). The D1% and Dmax of the heart and the Dmax and Dmean of the LAD obtained with the D-VMAT plan were lower than those obtained with the F-IMRT and F-VMAT plans (p < 0.05). ΔHCD exhibited correlation with the ΔDmean of the LAD between the D-VMAT and F-IMRT plans and between the D-VMAT and F-VMAT plans (R = -0.765 and -0.774, respectively, p = 0.000). Conclusion: the D-VMAT plan offered enhanced protection for OARs. The integration of the DIBH technique with half-field and VMAT technology in the D-VMAT plan offers a superior dose distribution. [ABSTRACT FROM AUTHOR]

The Liquid Phase Catalytic Exchange (LPCE) process plays a pivotal role in the separation of hydrogen isotopes, particularly in applications such as tritium removal in heavy water reactors. Effective separation is crucial for maintaining reactor safety and efficiency. In this study, the optimal operating conditions for the LPCE process were determined through orthogonal experiments and validated in different hydrogen isotope systems. The experiments investigated key operational parameters, including the filling ratio of catalyst to packing (FR), operating temperature (T), superficial gas velocity (V), and gas-to-liquid flow rate ratio (λ), using a robust L16 orthogonal experiment design. The results indicated that V and FR had the most significant effects on the height equivalent to a theoretical plate (HETP), while λ exhibited the greatest impact on dedeuterization efficiency (DE). The optimal conditions obtained were V = 0.1 m/s, FR = 1:2, T = 70 °C, and λ = 2.5. Furthermore, the reproducibility of the optimal conditions was verified in LPCE columns with varying diameters (1.5 cm, 2.5 cm, 4.5 cm). Additionally, the findings were applied to both H-D and D-T separation systems, demonstrating consistency in mass transfer efficiency and validating the applicability of the optimal conditions in different hydrogen isotope separations. This research provides critical insights for optimizing tritium removal systems in heavy water reactors, contributing to enhanced reactor safety and performance. [ABSTRACT FROM AUTHOR]

Activated carbon (AC) is a very diverse adsorbent material with high porosity, high surface area, and excellent performance in vapor phase adsorption. The pretreatment provides a guaranteed way for the efficient adsorption performance of AC, which can remove the impurities and improve the porosity of AC. In this study, the difference between acid pretreatment and alkali pretreatment of coconut shell carbon was systematically investigated. The effect of heating with stirring pretreatment and ultrasonic pretreatment after acid treatment were also researched. The Brunauer-Emmett-Teller (BET) specific surface area, the N2 saturation adsorption, and the porosity of AC by acid-ultrasonic pretreatment can reach 1094.30 m2g−1, 352.51 cm3 (STP) g−1, and 0.5453 cm3g−1, respectively, which are higher than that of acid-heating with stirring pretreatment and alkali-heating with stirring pretreatment. Combined with the Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS) analysis data, AC by acid-ultrasonic pretreatment has a better microstructure and clearer aperture. Among the three methods of preprocessing, acid-ultrasonic pretreatment yields the most favorable results. This work provides a possible way for AC pretreatment. [ABSTRACT FROM AUTHOR]

The hydrogen–water isotope catalytic exchange process has been widely applied in the tritium-containing water treatment process. It can be compared and analyzed conveniently with process simulation software. In this study, the catalytic exchange process was simulated by Aspen Plus software (V11). According to the simulation results, the main reaction process was that HDO in the liquid phase converts into HD in the gas phase, and the reaction mainly occurred at the bottom of the column, exhibiting a two-orders-of-magnitude-higher reaction amount compared to that observed in the top section. Different side reactions occur at distinct positions along the column, exhibiting a reaction amount that is lower by one to two orders of magnitude compared to the main reaction and aligning in the same direction as the main reaction. The optimum operating temperature is 60~80 °C, with the best performance observed at 70 °C, because of the large reaction equilibrium constant and the suitable ratio of vapor to hydrogen (1:4~1:1.5) in the gas phase. The influence of the residence time was investigated by introducing reaction kinetic equations. The residence time should be more than 1 s to ensure an adequate reaction. The influence of operating conditions on the hydrogen–water isotope catalytic exchange process can be deeply investigated by process simulation, and more mass transfer process quantities can be obtained. It plays a promoting role in guiding the process design and condition optimization. [ABSTRACT FROM AUTHOR]