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Purpose: Establishing the tolerance limits of patient‐specific quality assurance (PSQA) processes based on the gamma passing rate (GPR) by using normal statistical process control (SPC) methods involves certain problems. The aim of this study was threefold: (a) to show that the heuristic SPC method can replace the quantile method for establishing tolerance limits in PSQA processes and is more robust, (b) to introduce an iterative procedure of "Identify‐Eliminate‐Recalculate" for establishing the tolerance limits in PSQA processes with unknown states based on retrospective GPRs, and (c) to recommend a workflow to define tolerance limits based on actual clinical retrospective GPRs. Materials and Methods: A total of 1671 volumetric‐modulated arc therapy (VMAT) pretreatment plans were measured on four linear accelerators (linacs) and analyzed by treatment sites using the GPRs under the 2%/2 mm, 3%/2 mm, and 3%/3 mm criteria. Normality testing was performed using the Anderson‐Darling (AD) statistic and the optimal distributions of GPRs were determined using the Fitter Python package. The iterative "Identify‐Eliminate‐Recalculate" procedure was used to identify the PSQA outliers. The tolerance limits of the initial PSQAs, remaining PSQAs after elimination, and in‐control PSQAs after correction were calculated using the conventional Shewhart method, two transformation methods, three heuristic methods, and two quantile methods. The tolerance limits of PSQA processes with different states for the respective methods, linacs, and treatment sites were comprehensively compared and analyzed. Results: It was found that 75% of the initial PSQA processes and 63% of the in‐control processes were non‐normal (AD test, p < 0.05). The optimal distributions of GPRs for the initial and in‐control PSQAs varied with different linacs and treatment sites. In the implementation of the "Identify‐Eliminate‐Recalculate" procedure, the quantile methods could not identify the out‐of‐control PSQAs effectively due to the influence of outliers. The tolerance limits of the in‐control PSQAs, calculated using the quantile of optimal fitting distributions, represented the ground truth. The tolerance limits of the in‐control PSQAs and remaining PSQAs after elimination calculated using the heuristic methods were considerably close to the ground truth (the maximum average absolute deviations were 0.50 and 1.03%, respectively). Some transformation failures occurred under both transformation methods. For the in‐control PSQAs at 3%/2 mm gamma criteria, the maximum differences in the tolerance limits for four linacs and different treatment sites were 3.10 and 5.02%, respectively. Conclusions: The GPR distributions of PSQA processes vary with different linacs and treatment sites but most are skewed. In applying SPC methodologies to PSQA processes, heuristic methods are robust. For in‐control PSQA processes, the tolerance limits calculated by heuristic methods are in good agreement with the ground truth. For unknown PSQA processes, the tolerance limits calculated by the heuristic methods after the iterative "Identify‐Eliminate‐Recalculate" procedure are closest to the ground truth. Setting linac‐ and treatment site‐specific tolerance limits for PSQA processes is necessary for clinical applications. [ABSTRACT FROM AUTHOR]

To uncover the fundamental chemistry of branched alkyl radical reaction with O 2 , especially the second oxidation process (O 2 + QOOH), iso-butyl is chosen as a combustion archetype and reactions on the potential energy surfaces of C 4 H 9 O 2 and C 4 H 9 O 4 are investigated by using quantum chemical calculations coupled with RRKM/master-equation method. In the present study we calculate the thermodynamics properties, the rate constants and branching ratios for major reaction pathways in a wide temperature range of 298−2400 K and pressure range of 0.01−10 atm. Our study indicates that the treatment of estimating the fate of OOQOOH in the second oxidation process by analogy with similar reaction type and molecular size for the fate of RO 2 in the first oxidation process could cause significant deviations. The accurate calculations conform that the rate constants for the second O 2 barrierless addition (QOOH + O 2) is half of the first O 2 barrierless addition (R + O 2). Morever, the accurate thermodynamics and kinetics data determined in the present work are indispensable for the detailed understanding and prediction of ignition properties of larger hydrocarbons. [ABSTRACT FROM AUTHOR]

Background: To develop a low-dose cone beam CT (LD-CBCT) reconstruction method named simultaneous algebraic reconstruction technique and dual-dictionary learning (SART-DDL) joint algorithm for image guided radiation therapy (IGRT) and evaluate its imaging quality and clinical application ability.Methods: In this retrospective study, 62 CBCT image sets from February 2018 to July 2018 at west china hospital were randomly collected from 42 head and neck patients (mean [standard deviation] age, 49.7 [11.4] years, 12 females and 30 males). All image sets were retrospectively reconstructed by SART-DDL (resultant D-CBCT image sets) with 18% less clinical raw projections. Reconstruction quality was evaluated by quantitative parameters compared with SART and Total Variation minimization (SART-TV) joint reconstruction algorithm with paired t test. Five-grade subjective grading evaluations were done by two oncologists in a blind manner compared with clinically used Feldkamp-Davis-Kress algorithm CBCT images (resultant F-CBCT image sets) and the grading results were compared by paired Wilcoxon rank test. Registration results between D-CBCT and F-CBCT were compared. D-CBCT image geometry fidelity was tested.Results: The mean peak signal to noise ratio of D-CBCT was 1.7 dB higher than SART-TV reconstructions (P < .001, SART-DDL vs SART-TV, 36.36 ± 0.55 dB vs 34.68 ± 0.28 dB). All D-CBCT images were recognized as clinically acceptable without significant difference with F-CBCT in subjective grading (P > .05). In clinical registration, the maximum translational and rotational difference was 1.8 mm and 1.7 degree respectively. The horizontal, vertical and sagittal geometry fidelity of D-CBCT were acceptable.Conclusions: The image quality, geometry fidelity and clinical application ability of D-CBCT are comparable to that of the F-CBCT for head-and-neck patients with 18% less projections by SART-DDL. [ABSTRACT FROM AUTHOR]

In this work, a series of alumina coating reduced graphene oxide (RGO@Al 2 O 3) composites with core-shell structure was synthesized by the atomic layer deposition (ALD) method. The alumina (Al 2 O 3) thickness of the RGO@Al 2 O 3 could be controlled by changing the number of ALD cycles. The microstructure, high-temperature resistance, and microwave absorbing properties of the composites were investigated in detail. The composite could provide excellent high-temperature resistance and microwave absorbing properties. The composite started decomposition at 620 °C. The maximum reflection loss value of the composite obtained by applying 200 Al 2 O 3 deposition cycles is −14.2 dB at 15.7 GHz, and its effective absorption bandwidth reaches 5.0 GHz (13.0–18.0 GHz). The results show that the RGO@Al 2 O 3 composite has the potential application in high-temperature microwave absorbing fields, due to excellent high-temperature resistance, reflection loss, and effective absorption bandwidth. [ABSTRACT FROM AUTHOR]

Different drying methods were used to prepare catalytic membranes for the simultaneous removal of dust and NO to explore their effect on the distribution of active components, with the structural properties, filtration performance, catalytic performance, and working mechanism of the preferred prepared catalytic membrane systematically investigated. The results indicated that microwave drying, in contrast to traditional electric drying with blasting, effectively inhibited the migration of the precursor solution to achieve uniform loading of active components, thus endowing the catalytic membrane with excellent catalytic activity. Meanwhile, the pore structure of the fibrous ceramic substrate was not almost affected by the loaded catalyst and still exhibited high porosity. These characteristics contributed to the development of a catalytic membrane with good filtration and catalytic performance, as well as superior adaptable NO concentration and filtration velocity properties. Therefore, fibrous ceramic-based catalytic membranes prepared using microwave assistance offer considerable application prospects for integrated purification of high-temperature flue gases. Furthermore, the removal of dust and NO was determined to follow the Eley–Rideal reaction mechanism and surface filtration mechanism of the residual dust cake, respectively. [ABSTRACT FROM AUTHOR]

A method for preparing surface-enhanced Raman scattering substrate with high sensitivity is presented in this study. The new type of substrate was fabricated by depositing silver nanoparticles, using electroplating, onto the surface of boron-doped single silicon with a texture of inverted pyramid arrays prepared by the technology of texturization. In order to evaluate the enhancement ability of the substrate, a test of Raman scattering with Rhodamine 6G (R6G) as probe molecules was performed and the results showed a high sensitivity, good uniformity and stability. Relay on the enhancement by the substrate, the Raman scattering signal of R6G with a high signal-to-noise ratio could be detected out at a rather low concentration level of 10−18 M. The performance of the substrate is also simulated and illustrated using the software COMSOL Multiphysics. The electric field is greatly enhanced on the surface of silicon wafer with inverted pyramid morphology, especially in pits. According to the electromagnetic enhancement theory, the calculated Raman enhancement factor is as high as 1011, which strongly supports the experimental data. This work may offer a novel and practical method for Raman spectroscopy application in trace analysis. • Texture of inverted pyramid arrays on boron-doped single silicon • SERS substrate by depositing silver nanoparticles on the surfaces of texturization • The electric field on the surface of silicon wafer was simulated by multiphysics. [ABSTRACT FROM AUTHOR]

The eye lens is recognized as one of the most radiosensitive structures in the human body. The widespread use of intensity-modulated radiotherapy (IMRT) complicates dose verification and necessitates high standards of dose computation. The purpose of this work was to assess the computed dose accuracy of eye lens through measurements using a metal–oxide–semiconductor field-effect transistor (MOSFET) dosimetry system. Sixteen clinical IMRT plans of head and neck patients were copied to an anthropomorphic head phantom. Measurements were performed using the MOSFET dosimetry system based on the head phantom. Two MOSFET detectors were imbedded in the eyes of the head phantom as the left and the right lens, covered by approximately 5-mm-thick paraffin wax. The measurement results were compared with the calculated values with a dose grid size of 1 mm. Sixteen IMRT plans were delivered, and 32 measured lens doses were obtained for analysis. The MOSFET dosimetry system can be used to verify the lens dose, and our measurements showed that the treatment planning system used in our clinic can provide adequate dose assessment in eye lenses. The average discrepancy between measurement and calculation was 6.7 ± 3.4%, and the largest discrepancy was 14.3%, which met the acceptability criterion set by the American Association of Physicists in Medicine Task Group 53 for external beam calculation for multileaf collimator-shaped fields in buildup regions. [ABSTRACT FROM AUTHOR]

The depletion of fossil fuels and the increasing environmental problems, make biomass energy a serious alternative resource of energy. Biomass gasification is one of the major biomass utilization technologies to produce high quality gas. In this paper, biomass gasification was performed in a self-designed fluidized bed. The main factors (equivalence ratio, bed temperature, added catalyst, steam) influenced the gasification process were studied in detail. The results showed that the combustible gas content and the heating value increased with the increase of the temperature, while the CO 2 content decreased. The combustible gas content decreased with the increase of the equivalence ratio (ER), but CO 2 content increased. At the same temperature and at different ratios of CaO (from 0 to 20%), H 2 content was increased significantly, CO content was also increased, CH 4 content increased slightly, but CO 2 content was decreased. With the addition of steam at different temperature, the gas in combustible components increased, the content of H 2 increased obviously. The growth rate was 50% increased. As the bed temperature increased, gas reforming reaction increased, the CO and CH 4 content decreased, but CO 2 and H 2 content increased. • The main factors influenced the gasification process were studied in detail. • The results showed that the combustible gas content and the heating value increased with the increase of the temperature. • The combustible gas content decreased with the increase of the equivalence ratio. • With the addition of steam at different temperature, the gas in combustible components increased. [ABSTRACT FROM AUTHOR]

In the study, the influence and mechanisms of metal and non-metal dopants on the photochemical properties of the semiconductor catalyst g-C 3 N 4 are investigated. The results reveal that doping Ni, Ru, and B on g-C 3 N 4 results in significant alterations to the energy band structure, the band gap value decreases to 0.78 eV (Ru@g-C 3 N 4), 0.69 eV (Ni@g-C 3 N 4), 0.5 eV (RuB@B-g-C 3 N 4), and 0.1 eV (NiB@B-g-C 3 N 4) from the original value of 1.139 eV. The doping of metal and non-metal atoms can significantly enhance the light absorption capability and photothermal conversion efficiency of B-g-C 3 N 4. The mechanism of ammonia borane (AB) dehydrogenation follows the stepwise dehydrogenation principle. AB molecules adsorb onto the active metal centers, and with the assistance of the catalytic sites, CH 3 OH molecules activate and attack the B–N bond in AB molecules, leading to the initial breakage of the B–N bond, the interaction between O atoms in CH 3 OH and N atoms in AB continues, forming NH 3 BH 2 (OCH 3). Interactions between H(B) and H(O) result in the production of H 2 , the energy barrier for this reaction is 34.14 kcal/mol. Compared to dark conditions, RuB@B-g-C 3 N 4 exhibits higher catalytic activity under light irradiation, the reaction time from 9′20″ reduce to 8′. This shows that there is a synergistic effect between photocatalytic AB methanolysis and conventional metal catalyzed AB methanolysis in the RuB@B-g-C 3 N 4 catalytic system. The study provides the novel way for the development of dual-function catalysts combining metal catalysis and photocatalysis through Ru and B modification of g-C 3 N 4. • The doping of Ru, Ni, B can enhance the light absorption of g-C 3 N 4 significantly. • O–H bond cleavage in CH 3 OH is the rate-determining step in AB methanolysis. • Coupling photocatalysis and metal catalysis can enhance AB methanolysis reaction. [ABSTRACT FROM AUTHOR]