Effective water chemistry technology can inhibit the radiolysis of primary coolants and material corrosion in pressurized water reactors (PWRs). Research and operational experience suggest that methanol is a potential additive for the coolant transformation of PWRs. However, due to a lack of comprehensive understanding regarding the behavior and mechanism of methanol radiolysis in primary circuit scenarios, supporting methanol-based water chemistry control is challenging. This study initially outlines the importance of methanol radiolysis. It then summarizes global research progress on methanol radiolysis and its aqueous solution. Additionally, it discusses the yield of methanol radiolysis products and free-radical reactions at room temperature, as well as the radiolysis of methanol aqueous solutions under primary circuit conditions and its impact on material corrosion, are then discussed in detail. Finally, the study offers suggestions for future research on the radiolysis of methanol aqueous solutions.
Silicone rubbers are extensively used in high-end equipment in ionizing radiation environments because of their satisfactory elasticity, thermostability, high/low-temperature resistance, and aging resistance characteristics. Experimental studies and theoretical calculations are of equal importance because of their complicated radiolytic behaviors and mechanisms. This paper reviews the progress of simulation studies on radiation-aged silicone rubber. Many examples are listed and summarized to reveal their highlights in solving practical issues from the perspective of multiscale simulations, where mutual validation and verification of experiments and simulations are also discussed. Based on the characteristics of the spatiotemporal scale of the modeling methods, this paper is organized into the following six sections. Frequently adopted simulation methods include quantum electrodynamics, density functional theory, quantum molecular dynamics, reactive molecular dynamics, traditional molecular dynamics, and constitutive models and finite-element simulations. These methods are strongly associated with research demands, including the process and mechanism of interaction of silicone with radiation, evolution law and mechanism of system damage, and the structure–property relationship. Some studies have involved several modeling methods that are compiled into the most featured sections. This review presents a wide range of simulation studies on silicone rubber, outlining its research status and the current challenges for the academic and engineering community. This review provides novel ideas and knowledge bases for experimental studies and solutions to engineering problems.
The effects of UV irradiation on the chemical structure, thermal stability, surface morphology, and mechanical properties of aramid fibers were systematically studied. Changes in the chemical structure and thermal stability of the aramid fibers were characterized using Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis, respectively. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray wide-angle diffractometry (XRD) were employed to observe the surface morphology and crystal structure transformation of the aramid fibers before and after UV irradiation, respectively. Finally, the mechanical properties of the fibers were characterized using a monofilament strength testing machine. The FTIR results showed that the aramid fiber surfaces were photodegraded after UV irradiation, and new oxygen-containing functional groups appeared. The SEM and AFM results revealed that the surfaces became rough and gullied after ultraviolet irradiation. XRD results showed that UV irradiation had little effect on the crystal structure of the aramid fibers. Finally, the tensile properties indicated that the tensile strength decreased with increasing irradiation time. Based on these results, the surface chemical activity and roughness of the aramid fibers were increased after UV irradiation, which improved the interface adhesion between the aramid fibers and composite matrix while enhancing the interface force. Thus, solving the bottleneck problem of high-performance fibers, which are difficult to weave and exhibit poor composite strengths, is important. This study provides a reference for further expanding the application of aramid fibers in the field of composite materials. These applications include high-protective clothing and protective upperwear, which require enhanced interface adhesion.
To improve the rate of pesticide utilization, reduce pesticide usage, and effectively eliminate the adverse effects of pesticides on the environment, a carrier material was prepared by modifying starch using a one-step irradiation treatment. This carrier material was subsequently loaded with glyphosate isopropylamine salt to synthesize a glyphosate isopropylamine salt slow-release agent. The morphology and composition of this slow-release agent were characterized using scanning electron microscopy and infrared spectroscopy, and the slow-release performance, surface tension, and herbicidal activity of the different drug-loaded systems were also examined. Compared with the unloaded and attapulgite-loaded glyphosate isopropylamine salts, the rate of release obtained using the slow-release agent was reduced by 44.00% and 20.45% at 720 min, respectively. The release equilibrium time of the attapulgite-loaded glyphosate isopropylamine salt was 1 440 min, whereas that of the slow-release agent was 1 700 min. Based on the kinetic analysis and fitting, the first-order model correlation coefficient R2 of the glyphosate isopropylamine salt release curve ranged from 0.956 6 to 0.997 2, indicating that the fitting accuracy was high. Furthermore, a comparison of herbicidal activities showed that this glyphosate isopropylamine salt slow-release agent exhibited an improved control effect on barnyard grasses. In summary, the method for obtaining carrier materials by irradiation is simple, efficient, energy-saving, and environmentally friendly. The glyphosate isopropylamine salt slow-release agent synthesized based on this exhibited favorable slow-release performance and herbicidal activity, providing a new approach for the development of slow-release pesticides.
This study employs radiation grafting technology to attach a silane coupling agent onto cotton fabric, followed by the cross-linking of long-afterglow nanoparticles. This process yields a cotton fabric material with a high-intensity long-afterglow luminescence capacity. Characterization techniques, including total reflection infrared spectroscopy, thermogravimetry, X-ray diffraction, and scanning electron microscopy, were employed to investigate the loading of long-afterglow nanoparticles. Additionally, optical performance characterization was conducted to confirm the excellent optical properties of the material. The findings demonstrate that this material exhibits rapid energy charging and high brightness and can emit light continuously for more than 10 h. In addition, the material exhibits satisfactory cyclic and reprocessing performance, meeting the practical requirements of various applications. Because of its straightforward production process, ready availability of raw materials, and remarkable stability, this material holds promising prospects for use in decoration, emergency response, and other domains. This study also offers novel insights into the development of functional fabrics.
To improve the compatibility of natural rubber (NR) and ethylene-propylene-diene terpolymer (EPDM) and enhance the resistance of NR/EPDM blends to hot air aging, radiation-vulcanized NR/EPDM blends were prepared by γ-ray radiation. The effects of blend ratio and radiation vulcanization on the mechanical properties of the blends were investigated by using a uniaxial tensile test. With increasing EPDM content, the tensile strength and elongation at break of the hot-vulcanized sample first decreased and then increased due to the poor compatibility between NR and EPDM. In addition, the mechanical properties of the radiation-vulcanized sample degraded with increasing blend ratio of EPDM. The irradiation treatment improved the initial mechanical properties of the NR/EPDM rubber, and radiation crosslinking enhanced the coupling structure between the NR and EPDM polymer. Following aging treatment in hot air, the mechanical properties of the radiation-vulcanized sample were found to be less degraded than those of the hot-vulcanized one. This proved that the introduction of radiation technology via thermal crosslinking improved the elongation retention rate of the radiative crosslinked sample after thermal aging. In particular, the change rate of elongation at break of the radiation sample was reduced by ~50% when the blend ratio of the NR was greater than that of EPDM. The results showed that the NR/EPDM blends prepared by radiation vulcanization had greater resistance to hot air aging than those prepared by hot vulcanization.
This study aimed to investigate the effect of diatrizoate vaginal stump markers on the dose distribution of postoperative radiotherapy for cervical cancer. From July 2022 to July 2023, 12 patients who underwent radical postoperative radiotherapy for cervical cancer at Gansu Provincial Maternity and Child-Care Hospital, Gansu Provincial Central Hospital, and who had cotton balls with meglumine diatrizoate placed to mark the vaginal stump before positioning were enlisted. Volume modulated arc therapy was designed as Plan A and was used in the actual treatment plan. The relative electron density value of the vaginal stump area marked by meglumine diatrizoate was replaced by the relative electron density value of the normal vaginal wall, and Plan B was recalculated, keeping the planning optimization parameters unchanged. The evaluation indicators and dose distributions were compared between the two group. The results showed that the Homogeneity index(HI)was slightly worse in the Plan B group than the Plan A group (1.048 vs. 1.047) but the Conformance index (CI) (0.870 vs. 0.868) was better in the Plan B group. The average dose to the planned target volum (46.48 vs. 46.47) and the dose to the vaginal stump (47.14 vs. 46.45) were higher for Plan B than Plan A, and the minimum dose to the rectum (6.42 vs. 6.49) was lower for Plan B than Plan A. The effect of diatrizoate vaginal stump markers on dose distribution was negligible.
Alternaria alternata (A.alternata) is a major pathogenic fungus that causes black mold disease in pears, goji berries, and other crops. In this study, we investigated the inactivation mechanism and kinetics of A.alternata by using contact glow discharge plasma (CGDP). First, the optimal sterilization process and conditions were determined by examining the effects of exposure time, electrolytes, and voltage on the fungicidal rate. Second, the sterilization mechanism of A.alternata by CGDP was studied by evaluating cell membrane integrity and leakage of spore nucleic acids and proteins, and an inactivation kinetic model was constructed. These results showed that CGDP had a significant sterilization effect on A.alternata.. The sterilization rate increased with increasing voltage and treatment duration. Leakage of spore nucleic acids and proteins gradually increased with increasing treatment time. Propidium iodide and Fluorescein diacetate staining, as well as scanning electron microscopy indicated that the effect of CGDP on A.alternata was due to the disruption of its morphology and cell membrane integrity. Spore inactivation kinetics were consistent with dose-response modeling, and the results provide an important theoretical basis for further studies on the bactericidal mechanism of A.alternata.
The effects of 200 keV and 10 MeV electron-irradiation accelerators on the eradication of lasioderma serricorne and bacteria in tobacco and on the quality of tobacco leaf are investigated. By controlling the parameters of electron-beam irradiation, all lasioderma serricorne and bacteria inside tobacco can be eradicated efficiently and rapidly. The irradiated tobacco exhibits good retention based on a validation experiment, and no colonies are detected within 38 d. The irradiation has no significant effects on the basic physical and chemical indexes or the organic-acid and mineral-element contents of tobacco. Excessive energy levels reduce the volatilization loss of neophytadiene in tobacco from 589.91 to 418.64 μg/g, which indicates that the aroma quality of the tobacco deteriorates to a certain extent. Fluka simulation results show that a 3 MeV electron beam is sufficient to penetrate a full box of stored tobacco at existing tobacco stacking densities.
The deuterium-tritium fusion reaction is the fastest commercially achievable artificially controlled fusion reaction. However, tritium, as a fuel and neutron radiation-activated material, poses radioactive safety challenges. To simulate the migration of tritium and radioactive dust in the environment under accident conditions, a dispersion simulation program called ACCTRI (ACCidental model for TRItium release) has been developed based on the modified Gaussian multi-puff model, considering dry and wet deposition and tritium re-emission effects. The concentration and dose results calculated using ACCTRI are very close to those calculated using UFOTRI and HotSpot, with a maximum difference of no more than one order of magnitude. A comparison with the experimental results reveals that the results of ACCTRI with tritium buoyancy correction are close to the experimental data. ACCTRI has good accuracy and can be used as a reference for environmental radioactivity safety in fusion reactor site selection and hypothetical accident analysis.
The double exponential pulse waveform developed by the International Electrotechnical Commission is used to simulate the nuclear electromagnetic pulse, and the amplitude, spectrum, and phase of the main harmonic components of the waveform are analyzed. A dipole antenna model and a three-dimensional human body model are established in the simulation software COMSOL Multiphysics. Through the coupling modules of electromagnetic and thermal fields, the induced electric field intensity, magnetic field intensity, specific absorption rate (SAR), and temperature distribution in human tissues were obtained. The results are compared with the "Guidelines for Limiting Exposure to Electromagnetic Fields" established by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The results showed that when the human body is 1 km away from the exposure source, the induced electric field intensity, magnetic field intensity, local maximum SAR value, and average SAR value are 88.8 V/m, 0.58 A/m, 0.66 W/kg, and 0.011 W/kg, respectively. The electric and magnetic fields exceed the ICNIRP limits of 59.8 V/m and 0.22 A/m, respectively. However, at a distance of 10 km, the electric field, magnetic field, local maximum SAR value, and average SAR value all meet the safety limits. The temperature rise in human tissues is mainly concentrated in the brain, and after an exposure time of 6 minutes, the temperature rise is 0.217 1 ℃, which meets the ICNIRP's local temperature rise limit of 2 ℃ and core temperature rise limit of 1 ℃. This study provides a scientific basis for the health risk assessment of electromagnetic exposure in the human body in a nuclear electromagnetic pulse environment.
The distribution and transfer behavior of fibers within yarns has garnered significant research interest. Synchrotron radiation three-dimensional (3D) micro X-ray computed tomography (μ-XCT) is known for its strong penetration and high resolution and is used to visualize the internal structures of objects. In this study, a cotton yarn (ring-spun cotton yarn) was scanned, then reconstructed using 3D printing, visualized, and trimmed using the AI-assisted segmentation module in the Avizo software. The results showed that the sub-micrometer-resolution 3D microscopic imaging of cotton yarn could be achieved. This can be used to acquire the structural features of the yarn and its fiber transfer characteristics. A comprehensive understanding of the structure and performance of yarns was developed, providing valuable information for optimizing cotton yarn production and improving yarn quality and performance.