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PurposeDose calculation is one of the most computationally intensive, yet essential tasks in the treatment planning process. With the recent interest in automatic beam orientation and arc trajectory optimization techniques, there is a great need for more efficient model-based dose calculation algorithms that can accommodate hundreds to thousands of beam candidates at once. Foundational work has shown the translation of dose calculation algorithms to graphical processing units (GPUs), lending to remarkable gains in processing efficiency. But these methods provide parallelization of dose for only a single beamlet, serializing the calculation of multiple beamlets and under-utilizing the potential of modern GPUs. In this paper, the authors propose a framework enabling parallel computation of many beamlet doses using a novel beamlet context transformation and further embed this approach in a scalable network of multi-GPU computational nodes.MethodsThe proposed context-based transformation separates beamlet-local density and TERMA into distinct beamlet contexts that independently provide sufficient data for beamlet dose calculation. Beamlet contexts are arranged in a composite context array with dosimetric isolation, and the context array is subjected to a GPU collapsed-cone convolution superposition procedure, producing the set of beamlet-specific dose distributions in a single pass. Dose from each context is converted to a sparse representation for efficient storage and retrieval during treatment plan optimization. The context radius is a new parameter permitting flexibility between the speed and fidelity of the dose calculation process. A distributed manager-worker architecture is constructed around the context-based GPU dose calculation approach supporting an arbitrary number of worker nodes and resident GPUs. Phantom experiments were executed to verify the accuracy of the context-based approach compared to Monte Carlo and a reference CPU-CCCS implementation for single beamlets and broad beams composed by addition of beamlets. Dose for representative 4π beam sets was calculated in lung and prostate cases to compare its efficiency with that of an existing beamlet-sequential GPU-CCCS implementation. Code profiling was also performed to evaluate the scalability of the framework across many networked GPUs.ResultsThe dosimetric accuracy of the context-based method displays

As the numerous industrial solid waste, coal gangue caused serious environmental pollution in China, while the it could be modified and reused as an effective adsorption material in environmental remediation. In the current study, the coal gangue was modified by environmentally friendly ball-milling chemical modification method and used for simultaneous adsorption heavy metal and ammonia in wastewater. Both the initial and modified coal gangue were characterized for structure and composition. Optimization of ball-milling conditions and adsorption parameters was carried out, followed by thermodynamic and kinetic experiments under the defined conditions. The results showed that the adsorption of Pb2+, Zn2+, and NH4+–N accorded with the quasi-second-order kinetic model, with all adsorption isotherms conforming to the Langmuir model. Thermodynamic analysis indicates that the adsorption of Pb2+, Zn2+, and NH4+–N is an exothermic process, and the adsorption reaction can occur independently. Moreover, modified coal gangue exhibited sufficient adsorption sites for the combination of Pb2+, Zn2+, and NH4+–N at low concentrations in adsorption competition experiment, with an adsorption sequence like Pb2+ > Zn2+ > NH4+–N. Our results provide that ball-milling-modified coal gangue can be used as a helpful adsorption material for heavy metal ions and ammonia removal in wastewater treatment. [ABSTRACT FROM AUTHOR]

C16H11NO10U, monoclinic, P21/c (no. 14), a = 16.4675(12) Å, b = 11.7192(8) Å, c = 9.6663(7) Å, β = 100.823(2)°, V = 1832.3(2) Å3, Z = 4, R gt(F) = 0.0277, wR ref(F2) = 0.0673, T = 170.0 K.

The adsorption–desorption behaviours of La3+, Sm3+, and Y3+ on 2‐ethylhexylphosphonic acid mono‐2‐ethyl hexyl ester (HEHEHP) extraction resin were investigated in a chloride medium. The effects of reaction time, pH, hydrochloric acid concentration, flow rate, and adsorption mechanism were studied in detail using static and dynamic experimental methods. The results show that La3+ is the first to reach adsorption equilibrium, followed by Sm3+ and Y3+; the highest adsorption capacities of La3+, Sm3+, and Y3+ are obtained at solution pH of 4 and in the order of Y3+ > Sm3+ > La3+. La3+, Sm3+, and Y3+ can be eluted by 0.3, 0.5, and 3 mol/L hydrochloric acid, respectively, indicating that La3+ elutes most easily, and Y3+ is difficult. Moreover, the flow rate has little effect on the peak of rare earth desorption. The adsorption process is chemisorption; the slope method indicates that for each mol Sm3+ or Y3+ ion adsorbed, 3 mol H+ ions are simultaneously released, but two for La3+ under the given pH conditions. It is expected to provide theoretical and technical support for preparation of ultra‐high purity rare earth by HEHEHP extraction resin. [ABSTRACT FROM AUTHOR]

A two-dimensional uranyl organic framework (UOF) UO2(L)(DMA) (1) (H2L = 2-aminoisophthalic acid, DMA = N, N-dimethylacetamide) has been solvothermally synthesized and characterized thoroughly by elemental analysis, infrared spectroscopy, single-crystal X-ray diffraction, solid fluorescence, powder X-ray diffraction, thermogravimetric analysis, and UV–visible spectroscopy. Furthermore, the degradation efficiencies of UOF 1 to organic dye methylene blue (MB) and rhodamine B (RhB) are 93.2 and 86.5% under irradiation of visible light which indicates that UOF 1 has remarkable photocatalytic activity. UOF 1 also displayed a certain selectivity for mixed dyes of MB & RhB. [ABSTRACT FROM AUTHOR]