Radiation-induced defects in nanomaterials are an important aspect of the research on the effects of radiation on materials. Recently, the research on radiation-induced defects in semiconductor materials, low-dimensional materials, and high-specific-surface porous materials has become a new application of radiation technology. Radiation-induced nanomaterial defect engineering has the potential to be used to improve the electromagnetic, catalytic, adsorption, and mechanical properties of nanomaterials and will play an important role in materials science, electronic-device development, catalysis, and environmental science. Therefore, this review presents the recent progress and state-of-art in the formation and tuning mechanism of radiation-induced defects in nanomaterials and provides a direction for future development.
In this study, electron beam irradiation technology was used to degrade torasemide in an aqueous solution. By investigating the degradation effect, its influencing factors, and degradation products, the radiation degradation characteristics and possible degradation pathways of torasemide were systematically discussed. The study demonstrated that torasemide can be effectively degraded via electron beam irradiation. The experimental results showed that the active •OH particles played a dominant role in the degradation process. The initial torasemide concentration, absorbed dose, pH of the solution, amount of H2O2 and inorganic anions (CO32-,NO2-, SO32-, SO42-) and other environmental factors influence the irradiation effect of torasemide. A higher degradation efficiency was obtained with a lower initial torasemide concentration, higher absorbed dose, and lower pH. The degradation of torasemide was promoted in the presence of SO42- and low concentrations of H2O2, while it was inhibited in the presence of CO32-,NO2-, and SO32-and high concentrations of H2O2. Finally, the degradation products were detected by high performance liquid chromatography-quadrupole time of flight mass spectrometer (HPLC-QTOF), and the degradation pathways were deduced.
To explore the short-term impact of uranium pollution on the microecology of farmland soil, this study investigated the activities of four enzymes involved in key soil processes (β-glucosidase, urease, phosphatase, and arylsulfatase) and analyzed the changes in microbial metabolic activity, carbon utilization capacity, and diversity using Biolog EcoPlate under short-term (3 d, 13 d, and 20 d) uranium treatments (0 mg/kg, 50 mg/kg, 200 mg/kg, and 500 mg/kg). The results showed that the activities of the three soil enzymes, except that of urease, were inhibited by uranium pollution, especially phosphatase activity, which was reduced by 75.9% in the 20-day U500 treatment group. In addition, microbial metabolic activity was inhibited by uranium pollution. However, the inhibition effect showed a downward trend with the extension of the treatment time. The carbon metabolism capacity of microorganisms was inhibited. By contrast, the ability of microorganisms to utilize amino acids, carbohydrates, and polymer carbon sources was positively correlated with time in the U50 treatment group. The results of diversity indices analysis and sho principal component analysis wed little effect on the microbial diversity of uranium contamination. Therefore, uranium pollution inhibited the metabolic activities of farmland soil microorganisms, especially the carbon, phosphorus, and sulfur cycles. This study provides a direction for the ecological restoration of farmland soil uranium pollution.
Radiotherapy error in breast cancer mainly comprises setup error and respiratory breast motion. An accurate measurement of the setup error can provide a clinical reference for breast cancer planning target volume (PTV) expansion and improve treatment accuracy. Setup error rates were measured in 31 patients with breast cancer who underwent im-age-guided radiotherapy between June and October 2021. Cone beam computed tomography (CBCT) was performed for each patient first three times of treatment, and then once a week until the end of treatment. Bone registration was performed between the CBCT images and the CT images of the treatment plan. Record the registration results and obtain the setup errors. Calculated the external boundary of the PTV according to the setup error. A total of 131 CBCT scans were obtained for 31 patients. The standard deviation of systematic error and random error on the X (left and right), Y (the head and foot), and Z (the abdomen and back) axes were 1.40 and 0.67 mm, 1.89 and 0.56 mm, and 1.68 and 1.16 mm, respectively. The maximum absolute values of the setup errors were 4.9 mm, 6.4 mm, and 8.7 mm, respectively. The errors within 5.0 mm accounted for 100%, 98.47%, and 93.89%, respectively. The incidence of setup errors X, Y, and Z axes were 88.55%, 79.39%, and 75.57%, respectively. Based on the outward expansion of the clinical target volume, the PTV theoretical boundaries of breast cancer were 3.98 mm, 5.11 mm, and 5.02 mm, respectively. In foam-immobilized radiotherapy for breast cancer, the actual setup error cannot be accurately reflected considering the empirical PTV external boundary. It is clinically significant to measure and analyze the setup error using CBCT to calculate the PTV external boundary and guide clinical target area delineation.
To predict rectal and bladder radiation doses during volumetric modulated arc therapy (VMAT) for cervical cancer, a relevant model was established to guide clinical practice. Forty-four cases of cervical cancer treated using VMAT radiotherapy were retrospectively analyzed. The positional relationships of the anatomical spaces between the cervical cancer target volume and the organs at risk (bladder and rectum) were evaluated. Volume and spatial location characteristics of the target volume for the bladder and rectum were inserted as input data in a dose-volume histogram and Python toolkit for statistical analysis. The output data were the bladder and rectal V40 and D33. A mathematical model was developed to predict the bladder and rectal doses. When the actual and predicted values were compared, they were quite similar for both the bladder and rectal doses. The relative error ranges of rectal V40 and D33 were between 1.40% and 6.89%, and between 2.12% and 6.81%, respectively. Likewise, the relative error ranges of bladder V40 and D33 were between 2.47% and 6.67%, and between 0.38% and 4.28%, respectively. There were no significant differences between the actual and predicted values (p>0.05). This model can effectively predict the bladder and rectal doses needed during intensity-modulated radiotherapy for cervical cancer and could serve as a guide for radiotherapy clinical practice.
Among the cervical cancer treatments for patients with long-size tumors using the varian edge linear accelerator, we compared the newly designed plan (NewPlan) with the AutoPlan, which was automatically generated by the treatment planning system, and explored the dosimetric difference between the two plans for a more beneficial treatment. According to the accelerator's multi-leaf collimator characteristics, 11 cases of cervical cancer treatment plans using the simultaneous volumetric modulated arc therapy were selected. Based on the Eclipse 13.6.23 version of the planning system, the SPSS 19.0 statistical software was used to analyze the data, and the GraphPad prism 9.0 software was used to produce statistical graphs. The dose distribution difference between the NewPlan and conventional AutoPlan in the target area and organs at risk was analyzed. The results showed that the two plans met the dosimetry requirements. There were significant differences in the D98%, D50%, Dmean, target coverage, and heterogeneity index (HI) of the PGTVnd in the high dose area (pp>0.05). There were significant differences in the D2%,D98%, D50%, Dmean, and HI of PTV in the planned target area (pDmeanV30, and V40 of the bladder and rectum were statistically significant (pp>0.05). The comparison of the two plans reveals that the NewPlan can reduce cold and hot spots in the target area, improve the therapeutic dose in the tumor area, and reduce the dose of the organs at risk, which is conducive to improving the efficacy. Based on the varian edge accelerator, the NewPlan design is feasible for the treatment of patients with long-size tumors.
This article reports the digestibility, antioxidant activity, and protein structure of treated egg white protein powder (EWP) after pretreatment with electron beam irradiation (EBI) at doses of 5-100 kGy. The results revealed that EWP exhibited excellent in vitro digestibility under the tested EBI dose conditions. After EBI pretreatment, the treated EWP digestibility of the treated sample was slightly higher than that of the untreated sample. When EWP wais treated at 100 kGy EBI, the EWP in vitro digestibility was high, reaching up to (99.30 ± 0.53)%. The EWP digestion solution exhibited high antioxidation capacities of ABTS•+ radical scavenging activity (˃80%), Fe2+ chelation ability (˃70%), and •OH radical scavenging activity (~40%). Circular dichroism and fluorescence spectrum analyses indicated differences in the surface hydrophobicity and secondary structure of the EWP protein at the tested EBI doses. The protein peptides of the EWP digestion solution observed via sodium dodecyl-sulfate polyacrylamide gel electrophoresis were close to 25 kDa and 10 kDa. We believe that this study provides technical support for future practical applications of EBI in protein food-processing fields.
To evaluate the sterilization effect of electron beam irradiation on Tibetan medicine Bawei Chenxiang powder and the influence on the active ingredients, medicine samples were irradiated with electron beam at doses of 0 kGy, 5 kGy, 7 kGy, 10 kGy, and 60Co γ at 7 kGy. The microbial and active substance costunolide levels were measured within 7 d after irradiation and after accelerated storage at 49 ℃ for 3 months, respectively. The results showed that electron beam and 60Co γ irradiation significantly reduced the total number of microorganisms in Bawei Chenxiang powder. Irradiation by electron beams at 5 kGy and 10 kGy reduced the total number of microorganisms in Bawei Chenxiang powder to the maximum requirement suggested by the Chinese Pharmacopoeia without significantly decreasing the amount of active ingredient. In conclusion, electron beam irradiation can effectively improve the microbial index of Bawei Chenxing powder, and 5 kGy is the optimal processing dose for this purpose.
This study aims to evaluate the safety of electromagnetic exposure of passers-by (adults and children) in the electromagnetic environment of walk-through metal detectors operating at 6.48 kHz. The magnetic induction intensity and induced electric field intensity in a human model were calculated using COMSOL simulation software to simulate the operating environment of the electromagnetic walk-through metal detectors and compared with the International Commission on Non-Ionizing Radiation Protection (ICNIRP) public exposure limits of 27 μT and 874.8 mV/m. The magnetic induction intensity was the highest in the human body when directly below the walk-through metal detectors near the coil side. This intensity was observed on the arm near the door panel 2.44 μT (adults) and 1.86 μT (children), corresponding to 9.04% and 6.89% of the ICNIRP limit (27 μT), respectively. The electric field intensity in the CNS tissue was the highest in the human body when inside the walk-through metal dectors, distributed over the scalp and skull near the coil side, 1.27 mV/m (adults) and 1.1 mV/m (children), corresponding 0.15% and 0.13% of the ICNIRP limit (874.8 mV/m), respectively. The simulation values were below the public exposure limits set by ICNIRP, indicating that the electromagnetic fields generated by the transmitting coils during the operation of the walk-through metal detectors do not pose a health risk to humans owing to electromagnetic exposure.
Lateral diffused metal oxide semiconductors (LDMOS) used in power management integrated circuits demonstrate low anti-radiation performance. To address this issue, a high voltage radiation hardened LDMOS structure was studied, and an N-LDMOS device with a breakdown voltage of 60 V was designed.We analyzed the radiation hardening mechanism of the heavily doped P+well and buffer layer structures using the Ta ion model (Linear energy transfer, LET=79.2 MeV·cm2/mg) with a TCAD simulation tool and verified it via an irradiation test. The results revealed that by using the heavily doped P+well and buffer layer structures, the single event burnout voltage of the high-voltage LDMOS could be improved to 60 V.