Γ-ray Irradiation Research Articles

Nuclear Cogeneration of Methanol and Acetaldehyde from Ethylene Glycol Using Ionizing Radiation.

Despite offering low-carbon and reliable energy, the utilization of nuclear energy is declining globally due to high upfront capital costs and longer returns on investments. Nuclear cogeneration of valuable chemicals from waste biomass-derived feedstocks could have beneficial impacts while harnessing the underutilized resource of ionizing energy. Here, we demonstrate selective methanol or acetaldehyde production from ethylene glycol, a feedstock derived from glycerol, a byproduct of biodiesel, using irradiations from a nuclear fission reactor. The influence of radiation quality, dose rate, and the absorbed dose of irradiations on radiochemical yields (G-value) has been studied. Under low-dose-rate, γ-only radiolysis during reactor shutdown rate (<0.018 kGy min-1), acetaldehyde is produced at a maximum G-value of 8.28 ± 1.05 μmol J-1 and a mass productivity of 0.73 ± 0.06% from the 20 kGy irradiation of neat ethylene glycol. When exposed to a high-dose-rate (6.5 kGy min-1), 100 kGy mixed-field of neutron + γ-ray radiations, the radiolytic selectivity is adjusted from acetaldehyde to generate methanol at a G-value of 2.91 ± 0.78 μmol J-1 and a mass productivity of 0.93 ± 0.23%. Notably, utilizing 422 theoretical systems could contribute to 4.96% of worldwide acetaldehyde production using a spent fuel pool γ-ray scheme. This research reports G-values and production capacities for acetaldehyde for high-dose scenarios and shows the potential selectivity of a nuclear cogeneration process to synthesize chemicals based on their irradiation conditions from the same reagent.

Optical and scintillation properties of the Eu2O3-doped HfO2-Al2O3–SiO2 glass ceramics

In this study, Eu-doped 10HfO2–10Al2O3–80SiO2 glass ceramics with different Eu concentrations were prepared by the melt-quenching method using an optical floating zone furnace, and optical and scintillation properties were investigated to apply them for radiation detectors. All the glass ceramic samples were transparent, although they included not only an amorphous phase but also a crystal phase of cubic-HfO2. Photoluminescence and scintillation peaks due to Eu2+ were detected at 400–550 nm. In the glass ceramic samples with higher Eu concentration, the luminescence of Eu3+ was also observed. Quantum yields and afterglow levels decreased with increasing Eu concentration. The 1.0% Eu-doped sample had the highest light yield among all our glass samples, and the light yield was 630 photons/MeV under γ-ray irradiation from 137Cs.

Effects of Radiation-Induced Skin Injury on Hyaluronan Degradation and Its Underlying Mechanisms.

Radiation-induced skin injury (RISI) is a frequent and severe complication with a complex pathogenesis that often occurs during radiation therapy, nuclear incidents, and nuclear war, for which there is no effective treatment. Hyaluronan (HA) plays an overwhelming role in the skin, and it has been shown that UVB irradiation induces increased HA expression. Nevertheless, to the best of our knowledge, there has been no study regarding the biological correlation between RISI and HA degradation and its underlying mechanisms. Therefore, in our study, we investigated low-molecular-weight HA content using an enzyme-linked immunosorbent assay and changes in the expression of HA-related metabolic enzymes using real-time quantitative polymerase chain reaction and a Western blotting assay. The oxidative stress level of the RISI model was assessed using sodium dismutase, malondialdehyde, and reactive oxygen species assays. We demonstrated that low-molecular-weight HA content was significantly upregulated in skin tissues during the late phase of irradiation exposure in the RISI model and that HA-related metabolic enzymes, oxidative stress levels, the MEK5/ERK5 pathway, and inflammatory factors were consistent with changes in low-molecular-weight HA content. These findings prove that HA degradation is biologically relevant to RISI development and that the HA degradation mechanisms are related to HA-related metabolic enzymes, oxidative stress, and inflammatory factors. The MEK5/ERK5 pathway represents a potential mechanism of HA degradation. In conclusion, we aimed to investigate changes in HA content and preliminarily investigate the HA degradation mechanism in a RISI model under γ-ray irradiation, to consider HA as a new target for RISI and provide ideas for novel drug development.

Effects of Gamma-Ray Irradiation of Bacteria Colonies in Animal Feeds and on Growth and Gut Health of Weaning Piglets

Animal feeds contain a substantial number and diversity of microorganisms, and some of them have pathogenic potential. The objectives of this study were to investigate the effects of different doses of gamma (γ)-ray irradiation on the bacteria count in different types of feed and then to test the effect of γ-ray-irradiation-treated fishmeal on the gut health and growth performance of weaning piglets. In trial 1, three fishmeal samples, two feather meal samples, three meat meal samples, three soybean meal samples, and three vitamin complexes were treated with γ-ray irradiation doses of 0, 3, 6, or 9 kGy. The 6 and 9 kGy doses eliminated most of the bacteria in the feed but also resulted in a loss of vitamin C and B1. In trial 2, 96 weaning piglets were fed one of the following three diets with eight replicates (pens) per group over a 14-day period: (1) the control diet—the basal diet supplemented with 6% fishmeal with a low bacteria count (40 CFU/g) and no E. coli; (2) the fishmeal-contaminated diet (FM-contaminated) diet—the basal diet supplemented with 6% fishmeal with a high bacteria count (91,500 CFU/g) and E. coli contamination; and (3) the irradiated fishmeal (irradiated FM) diet—the basal diet supplemented with γ-ray-irradiation-treated E. coli-contaminated fishmeal. The piglets that received the FM-contaminated diet had significantly lower average daily gain and a greater diarrhea index compared to those fed the control diet, whereas γ-ray irradiation treatment abrogated the negative effect of the E. coli-contaminated fishmeal. Collectively, γ-ray irradiation at a dose of 6–9 kGy was sufficient to eliminate the microorganisms in the feed, thereby benefitting the growth performance and gut health of the weaning piglets.

Space radiation environment adaptability of the domestic 5056 high-performance aluminum honeycomb

In order to investigate the influence of space radiation environment on the performance of domestic 5056 high-performance aluminum honeycomb core, the effects of different irradiation effects and different radiation doses on the nodal strength and mechanical properties of domestic 5056 high-performance aluminum honeycomb core were studied through space radiation environmental tests and mechanical property tests such as high-energy electron irradiation, γ-ray irradiation, ultraviolet irradiation, hot and cold shock test, vacuum volatilization test. The results show that under multiple environmental conditions such as high-energy electron irradiation γ-ray irradiation, ultraviolet irradiation, and hot and cold shock environment, the domestic high-performance aluminum honeycomb core shows excellent adaptability to the irradiation environment and can be used for a long time in the extravehicular environment. However, when the radiation dose is greater than 2 × 109rad, the strength of honeycomb core nodes decreased significantly. The vacuum volatilization test results sindicate that the material meets the gas requirements of aerospace raw materials and has extremely low vacuum pollution characteristics.

Scintillation property of Tl-doped NaI transparent ceramics

In this study, Tl-doped NaI transparent ceramics with varying doping concentrations (0.05, 0.1, 0.3, and 0.5%) were synthesized using the spark plasma sintering (SPS) method, and We investigated the optical and scintillation properties. In terms of optical properties, the 0.1% Tl-doped NaI sample showed the diffuse transmittance of ∼70% in the visible range. The photoluminescence peak was observed at around 420 nm with the decay time of approximately 150 ns. The scintillation peak was also observed at 420 nm due to 3P1→1S0 transition of Tl+. In addition, all the samples showed the scintillation peak at 330 nm due to self-trapped exciton. Among all the samples, the 0.1% Tl-doped NaI sample showed the highest light yield (36,000 ph/MeV) under 137Cs γ-ray irradiation, and this value is almost equivalent to that of Tl-doped NaI single crystals (38,000 ph/MeV).

Icaritin increases radiosensitivity of nasopharyngeal carcinoma cells by regulating iron death

To explore the radiosensitizing effect of icaritin on nasopharyngeal carcinoma (NPC) cells and the underlying mechanism. MTT assay and clonal formation assay were used to evaluate the effect of icaritin on proliferation of human NPC HONE1 and HNE1 cells. The effects of icaritin treatment, γ-ray radiation, or both on production of reactive oxygen species (ROS), cell cycle distribution and apoptosis of the NPC cells were assessed using flow cytometry. The expressions of DNA damage markers γ-H2AX, cycle-related proteins CDC25C, p-CDC25C and cyclin B1, and ferroptosis markers ACSL4 and GXP4 were detected using Western blotting. A nude mouse model bearing subcutaneous HONE1 cell xenograft was used to observe the effect of icaritin and radiation on tumor growth. Icaritin dose-dependently inhibited the viability of the NPC cells and enhanced the inhibitory effect of radiation on cell proliferation. Flow cytometry and Western blotting showed that icaritin treatment prior to radiation significantly promoted ROS production and γ-H2AX expression in the NPC cells (P<0.001). Compared with radiation exposure alone, the combined treatment caused cell cycle arrest in G2 phase, down-regulated CDC25C and cyclin B1 expression, and up-regulated p-CDC25C expression in the cells (P<0.01), resulting also in increased cell apoptosis, enhanced expression of ferroptosis protein ACSL4 and lowered expression of GXP4 (P<0.001). In the tumor-bearing mice, icaritin treatment, compared with radiation alone, significantly reduced the tumor growth rate and decreased tumor weight (P<0.001). Icaritin can enhance radiosensitivity of NPC cells both in vitro and in nude mice possibly by enhancing ROS production to promote iron death of the cells.

Evaluating a novel protective agent against radiation-induced acute intestinal injury

ObjectiveTo develop and synthesize a novel derivative of ethyl pyruvate, named TZC02, and investigate its radioprotective effects against ionizing radiation (IR)-induced intestinal injury in mice. MethodsMale C57BL/6J mice weighing (20 ​± ​2) g in the survival experiment were randomly divided into five groups (n ​= ​10 in each): control group, IR group, IR ​+ ​TZC02 (50 ​mg/kg) group, IR ​+ ​TZC02 (100 ​mg/kg) group, and IR ​+ ​TZC02 (200 ​mg/kg) group. Mice's survival rates were monitored for 7 ​d. In other experiments, the male mice were randomly divided into three groups (n ​= ​5 per group): control group, IR group, and IR ​+ ​TZC02 (100 ​mg/kg) group. TZC02 was intragastrically administered 1 ​h before 12 ​Gy abdominal γ-ray irradiation (ABI) and 24 h, 48 h after irradiation, respectively. Three days after IR exposure, small intestinal tissues were collected and the number of small intestinal crypts was determined using hematoxylin & eosin (H&E) staining. Immunohistochemical analysis was used to assess the regenerative capacity of the small intestine (SI) and radiation-induced damage, stemness markers or DNA repair surrogates, including Ki67, lysozyme, and villus. The expressions of histone H2AX phosphorylation (γH2AX) and caspase-3 were evaluated through immunofluorescence analyses. Additionally, in vitro cultured small intestinal organoids were employed to investigate the effects of TZC02 on SI regeneration after irradiation. ResultsThe administration of TZC02 significantly improved the 7 ​d- survival rate of mice exposed to 12 ​Gy ABI (P ​< ​0.05). Compared to the IR group, TZC02 treatment attenuated the decrease of SI Ki67-positive cells [(59.60 ​± ​6.33) vs. (37.70 ​± ​7.82), t ​= ​11.89, P ​< ​0.0001) and Paneth cells [(9.90 ​± ​1.37) vs.(5.50 ​± ​1.71) , t ​= ​6.02, P ​< ​0.001) in five crypts, and reduced structural damage to the SI [villus height, (349.49 ​± ​60.17) μm vs. (294.72 ​± ​40.09) ​μm; t ​= ​3.39; P < ​0.05]. TZC02 also significantly decreased the crypt apoptosis detected by caspase-3 [(10.75 ​± ​1.26) vs. ​(29.83 ​± ​2.56), t ​= ​13.39, P ​< ​0.0001) and DNA damage detected by gH2AX [(10.40 ​± ​1.14) vs. ​(29.60 ​± ​2.70), t ​= ​10.13, P ​< ​0.0001)]. The organoid survival 7 ​d post-irradiation further confirmed the protective effects of TZC02 (area of organoids, (0.119 ​± ​0.081) ​mm2vs. ​(0.080 ​± ​0.037) ​mm2; t ​= ​2.30; P ​< ​0.05). ConclusionsThis study demonstrate that TZC02 can offer effective protection against IR-induced intestinal injury, suggesting its potential as a promising protective compound for patients treated with radiotherapy.

Construction of Watermelon Mutant Library Based on 60Co γ-ray Irradiation and EMS Treatment for Germplasm Innovation

Watermelon is a crucial horticultural crop worldwide but its genetic base has become extremely narrow owing to long-term cultivation. Induced mutagenesis can create a range of variations with distinctive agricultural characteristics. To broaden the genetic diversity of watermelon, we established a mutagenesis library containing over 4000 M1 seeds from an inbred line ‘M08’, which was irradiated by 350 Gy of 60Co γ-rays for 3 h. The rates of germination, emergence, and survival of the M1 seeds were reduced by 5.88%, 18.66%, and 41.96%, respectively. After phenotypic screening, 20 and 10 types of morphological changes were observed in the M1 and M2 generations, with approximately 10.57% and 14.17% mutation frequencies, respectively. Six mutants with desirable horticultural alterations were selected for additional presentation, including the leaf color mutant C1-NO.1, the yellow peel mutant C1-NO.2, the pericarp thickening mutant C1-NO.3, the pericarp thinning mutant C1-NO.4, the seedless mutant C1-NO.5, and the C2-No.1 mutant with normal female flowers and malformed male flowers. Moreover, the three mutants M1-3, M2-1, and M1-5 were identified from our EMS-induced M2 library, exhibiting the fusiform fruit, the dark green peel, and the yellow leaves, respectively. Compared to the wild type (WT), the photosynthetic pigments and parameters were negatively impacted in the yellow-leaf mutant M1-5. For example, the total chlorophyll was 1.22 and 2.22 mg/g in the young and mature leaves of M1-5, respectively, which were significantly lower than those in the WT (2.58 and 2.90 mg/g, respectively). Notably, some mutagenesis phenotypes could be stably inherited, including traits such as yellow leaf color, fusiform fruit shape, and thickening and thinning pericarp. Taken together, these results indicate that these two mutant libraries serve as essential resources to discover new phenotypic germplasms, thereby facilitating the genetic breeding and functional gene exploration in watermelon.

A KGd(WO4)2 powder/Er2Ce2O7–SiO2 aerogel with low thermal conductivity and excellent radiation shielding performance for thermal insulation of nuclear power plants

To meet the application requirements of thermal insulation materials for nuclear power plants, Rare earth composite aerogel (KGd(WO4)2 powder/Er2Ce2O7–SiO2) were prepared by compounding rare earth precursor sol and rare earth powder with silica aerogel based on directional freeze drying method. The effect of thermal diffusivity of rare earth salt crystals on the thermal conductivity of rare earth composite aerogel was found, and the mechanism of the effect of the type and morphology of rare earth powder on the γ-ray shielding performance was explored. The irradiation and temperature resistance measurement shows that the KGd(WO4)2 powder/Er2Ce2O7–SiO2 aerogel can withstand 1 × 107 Gy γ-ray and high temperature baking above 1100 °C. KGd(WO4)2 powder/Er2Ce2O7–SiO2 aerogel is an ideal new generation multi-functional shielding and thermal insulation material for nuclear power plants because of its low thermal conductivity, excellent γ-ray and neutron radiation shielding, high temperature resistance and radiation aging resistance.

Performance degradation mechanism of γ-ray irradiated sol-gel silica film

γ-ray radiation effect on sol-gel silica films was investigated at different absorbed doses ranging from 10 kGy to 1000 kGy. The defect and microstructure evolutions of silica films were analyzed to understand the performance degradation behavior and mechanism of the γ-ray irradiated silica films. The cracks appear on the silica film surface and further expand at larger γ-ray absorbed dose, while surface roughness slightly decreases. During γ-ray irradiation, the thermal effect and the increased rate of diffusion-controlled process lead to the condensation of Si-OH groups and the recombination of ODCs. However, the ionization of atoms leads to generation and accumulation of E′ centers and NBOHCs. γ-ray irradiation leads to the reductions of bond lengths and bond angles of Si-O-Si groups, thus causing the densification of films. The refractive index and mechanical property firstly enhance and then reduce with the increase of absorbed dose associated with the change of silica film density. After γ-ray irradiation, the decreased contact angle and increased surface free energy indicate the reduction of anti-pollution ability of silica films. The dose-dependent surface quality, defects and mechanical properties determine the variation in laser-induced damage threshold (LIDT) of silica film. The results provide a reference to control the structural damage and performance degradation of silica films, which is very important for the research of safe operation of high-power laser facilities for inertial confinement fusion (ICF).

Novel gamma-ray enhanced TiO2 nanoparticles photoanode for efficient photoelectrochemical (PEC) water splitting

The photocatalytic activity of TiO2 nanoparticles (TiO2NPs) for Hydrogen Evolution Reduction (HER) was significantly enhanced through a multi-step process involving oxygen-doping with γ-ray irradiation treatment (ranging from 10 kGy to 100 kGy), methanolic dispersion, and post-annealing temperatures. Remarkably, γ rays induced oxygen-doping, leading to improved electronic properties and chemical bonding, as demonstrated in the XPS section, which ultimately contributed to the exceptional stability of the photoanode. The resulting higher crystallinity and larger crystallite sizes, evident in Raman and XRD spectra, further enhanced the structure of the TiO2NPs. Upon γ irradiation, the deposited TiO2NPs exhibited enlargement and agglomeration, which promoted enhanced surface area, catalytic sites, and light absorption when used as a photoanode in PEC cells. The post-irradiation conditions caused a reduction in the energy band gap, resulting in a quenching effect from 3.25 eV to 3.18 eV. Intriguingly, PL analysis showed that the radiated photoanode displayed a remarkable reduction in the energetic separation of photo-generated electron-hole pairs, accompanied by a simultaneous decrease in carrier recombination. Overall, the 70 kGy TiO2NP photoanode demonstrated exceptional photostability and significantly outperformed the pure TiO2NP counterpart by increasing the photocurrent density by over 300%, reaching approximately 100.12 μA cm−2 at 1.23 vs. RHE, compared to 36.42 μA cm−2 for the pure TiO2NP. These findings underscore the significance of gamma irradiation in the field of nanomaterials and its promising potential for photoelectrochemical (PEC) solar water splitting applications.

Enhanced heat resistance of ABS/poly(N-(4-fluorophenyl) maleimide-alt-triallyl isocyanurate) composites based on solid-state interfacial reaction

The poor heat resistance of acrylonitrile-butadiene-styrene copolymer (ABS) is a significant limitation that restricts its application in various fields, including automotive, electronic devices and other fields. To address this issue, we employed a strategy involving the crosslinking of a macromolecular heat-resistant agent to enhance the heat resistance of ABS. Poly(N-(4-fluorophenyl) maleimide-alt-triallyl isocyanurate) (PFT), a reactive heat-resistant agent known for its rigid and reactive structures, was selected for this purpose. ABS/PFT composites were prepared by subjecting them to γ-ray irradiation, resulting in crosslinking through a solid-state interfacial reaction (SSIR) between PFT and ABS. The results show that the heat distortion temperature (HDT), glass transition temperature (Tg), tensile strength and bending strength of the irradiated ABS/PFT (i-ABS/PFT) composites increased by 23.86%, 23.35%, 20.0% and 9.0%, respectively compared to pure ABS. Furthermore, ABS/PFT composites with SSIR exhibit the highest heat resistance, Tg and HDT compared to non-SSIR ABS. The work presented in this paper provides a new direction for the heat-resistant modification of ABS and will expand its application in new fields.

Mechanical Properties, Radiation Resistance Performances, and Mechanism Insights of Nitrile Butadiene Rubber Irradiated with High-Dose Gamma Rays.

The radiation effect of materials is very important and directly related to the safety and reliability of nuclear reactors. Polymer materials, one of the indispensable materials in nuclear power equipment, must withstand the ordeal of high-energy ionizing rays. In this work, through screening different γ-ray dose irradiation conditions, we systematically and comprehensively study the changes in the structure and properties of nitrile butadiene rubber (NBR) before and after γ-ray static irradiation at a high dose rate, and master the rule and mechanism of the γ-ray static irradiation effect of these polymer materials. The mapping relationship between the macroscopic properties, microstructure, and irradiation dose of NBR is accurately characterized. With an increase in total irradiation dose, the C=C double bond reaction occurs, and the C≡N bond, C=C, and C=O participate in the hyper crosslinking reaction. The glass transition temperature (Tg) increases with the cumulative irradiation amount. With the increased total irradiation amount, the degree of rubber cross-linking increases, causing an increased crystallinity and decomposition temperature. A growing amount of gamma irradiation causes the mechanical properties of the rubber to degrade simultaneously, increasing the shore hardness while decreasing the tensile strength and ultimate elongation at break. When the cumulative amount reaches 1 MGy, the ultimate elongation at break decreases significantly. A cumulative dose of radiation resistance of 4 MGy can be achieved by the samples. This work can provide theoretical and experimental support for the long-term stability of nitrile butadiene rubber and its derivatives in nuclear radiation fields and space radiation conditions.

DDB2 and MDM2 genes are promising markers for radiation diagnosis and estimation of radiation dose independent of trauma and burns.

In the field of biodosimetry, the current accepted method for evaluating radiation dose fails to meet the need of rapid, large-scale screening, and most RNA marker-related studies of biodosimetry are concentrating on a single type of ray, while some other potential factors, such as trauma and burns, have not been covered. Microarray datasets that contain the data of human peripheral blood samples exposed to X-ray, neutron, and γ-ray radiation were obtained from the GEO database. Totally, 33 multi-type ray co-induced genes were obtained at first from the differentially expressed genes (DEGs) and key genes identified by weighted gene co-expression network analysis (WGCNA), and these genes were mainly enriched in DNA damage, cellular apoptosis, and p53 signaling pathway. Following transcriptome sequencing of blood samples from 11 healthy volunteers, 13 patients with severe burns, and 37 patients with severe trauma, 6635 trauma-related DEGs and 7703 burn-related DEGs were obtained. Through the exclusion method, a total of 12 radiation-specific genes independent of trauma and burns were identified. ROC curve analysis revealed that the DDB2 gene performed the best in diagnosis of all three types of ray radiation, while correlation analysis showed that the MDM2 gene was the best in assessment of radiation dose. The results of multiple-linear regression analysis indicated that such analysis could improve the accuracy in assessment of radiation dose. Moreover, the DDB2 and MDM2 genes remained effective in radiation diagnosis and assessment of radiation dose in an external dataset. In general, the study brings new insights into radiation biodosimetry.

Resistance of Graphene/Epoxy Resin—Based Composite Materials to γ Radiation Damage and Their Mechanical Properties

This study aims to explore the role of graphene in enhancing the radiation resistance of epoxy resin (EP) composites. Through the resin transfer molding process, we prepared 0.3 wt% graphene oxide (GO) and Hummer’s method reduced graphene oxide (Hh-RGO) reinforced EP composites, respectively. By comparing the microstructure, free radical content, thermal stability, and mechanical properties of EP, GO/EP, and Hh-RGO/EP composites before and after γ-ray irradiation, we found that GO and Hh-RGO can effectively reduce the generation of free radicals in EP during irradiation, thereby reducing chemical bond breakage and enhancing its radiation resistance. Particularly, GO demonstrated stronger radiation damage resistance. The results showed that after γ-ray irradiation, the glass transition temperature, nano-indentation depth, and hardness of GO/EP composites decreased by 20.32%, 416.3 nm, and 16.00%, respectively, whereas EP decreased by 30.34%, 502.1 nm, and 41.82% respectively. This is mainly attributed to the fact that the addition of graphene nanoparticles as a reinforcement reduces the free radical content in EP and reduces the damage of free radicals to the EP crosslinked network during irradiation, thereby improving the thermal stability and mechanical properties of the composites. In addition, the Π electrons formed by the hexagonal honeycomb structure of GO and the Π-Π stacking effect formed with free radicals can slow down the aging of epoxy resin in a high-energy radiation environment, thereby prolonging its service life. This study provides important references for further optimization and application of graphene-modified epoxy resin.

Influence of γ-irradiation on the structural and optical properties of PVA/rGO films reinforced with rGO for nuclear shielding applications.

The polyvinyl alcohol films reinforced with reduced graphene oxide (PVA/rGO) have been synthesized by the film casting method. Fourier-transform infrared spectroscopy (FTIR) was used to measure the spectra for PVA/rGO films before and after being exposed to various dosages of γ-irradiation. XRD “X-ray diffraction” has been used to evaluate the structure of PVA/rGO before and after γ-ray irradiation and showed the potential for some H-bonding to be broken along with the splitting of the major chain. When compared to the non-irradiated sample, the FT-IR spectra of the irradiated samples show clear variations in peak locations and intensities. The absorbance spectral behavior of PVA/rGO film before and after irradiation with γ-rays at different dosages demonstrates a sharp and intense absorption spectrum centered at 205 nm and abroad, as well as a weak absorption spectrum centered at 277 nm. The absorbance spectrum fitting (ASF), the first derivation of the absorption spectrum fitting (DASF), and Tauc's methods were studied to investigate the optical energy gap for the PVA/rGO films before and after γ-irradiation with varied gamma doses. Also, the linear refractive index (n) for γ-irradiated PVA/rGO films was estimated and shows an increase in the values as the γ-doses increased. Such results show the great potential of the PVA/rGO polymer film in photovoltaic, polymer science applications, and radiation shielding.

Multifunctional Additive: A novel regulate strategy for improving mechanical property, aging life and fire safety of EVA composites

A multifunctional additive is carefully designed for crosslinked ethylene–vinyl acetate copolymer (XLEVA) composites to improve their mechanical properties, aging resistance and fire safety. In this study, first, a layer of silica was microencapsulated on magnesium hydroxide to give a large amount of hydroxyl group on the magnesium hydroxide surface; second, the primary antioxidant 3-(3, 5-di-tert-butyl-4 hydroxyphenyl) propionicacid was grafted on SiMH surface to prepare antioxidant microencapsulated flame retardants (MCMH). Compared with the pure XLEVA, the peak heat release rate and the maximum smoke density of flame retardant XLEVA/MCMH are decreased by 89.46% and 53.6%, respectively. Moreover, these oxidation induction time values of XLEVA/MH/AO and XLEVA/SiMH/AO decreased sharply after extracted for 1d. However, the OIT value of XLEVA/MCMH was basically unchanged after extracted for 5d. After aging at 165 °C for 14 days and γ-ray irradiation dose of 500 kGy, the retention of elongation at break could reach 71.8% and 86.6%, showing excellent aging resistance. These results show that MCMH has a good synergistic effect for enhancing the flame retardant, mechanical property as well as aging resistance of XLEVA composites. The “Killing three birds with one stone” strategy provides an excellent solution for obtaining high-performance XLEVA cable materials.

The mechanism of the irradiation synergistic effect of silicon bipolar junction transistors explained by multiscale simulations of Monte Carlo and excited-state first-principle calculations.

Neutron and γ-ray irradiation damages to transistors are found to be non-additive, and this is denoted as the irradiation synergistic effect (ISE). Its mechanism is not well-understood. The recent defect-based model [Song and Wei, ACS Appl. Electron. Mater. 2, 3783 (2020)] for silicon bipolar junction transistors (BJTs) achieves quantitative agreement with experiments, but its assumptions on the defect reactions are unverified. Going beyond the model requires directly representing the effect of γ-ray irradiation in first-principles calculations, which was not feasible previously. In this work, we examine the defect-based model of the ISE by developing a multiscale method for the simulation of the γ-ray irradiation, where the γ-ray-induced electronic excitations are treated explicitly in excited-state first-principles calculations. We find the calculations agree with experiments, and the effect of the γ-ray-induced excitation is significantly different from the effects of defect charge state and temperature. We propose a diffusion-based qualitative explanation of the mechanism of positive/negative ISE in NPN/PNP BJTs in the end.

Radiation synthesis of boronic acid modified graphene oxide for enhance the neutron shielding property of silicone rubber

In this study, poly(3-acrylaminophenylboronic acid) modified graphene oxide (GO-PAAPBA) has been prepared by polymerization of 3-acrylaminophenylboronic acid (AAPBA) on the surface of GO. The –O· free radical was formed by γ-ray radiation, which initiated the polymerization of AAPBA. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and Raman spectroscopy were employed to characterize the structure of GO-PAAPBA. The grafting density of poly(3-acrylaminophenylboronic acid) is increased with increasing of the absorbed dose. The GO-PAAPBA was added into vinyl-terminated polydimethylsiloxane (Vi-PDMS) to prepare room temperature cured silicon rubber composites (SR/GO-PAAPBA). The GO-PAAPBA exhibits better dispersion performance than pure GO, which is contribute to improve thermal conductivity and mechanical properties. Significantly, with grafting density of PAAPBA increasing, the comprehensive performances of SR/GO-PAAPBA are more remarkable. SR/GO-PAAPBA-1.88 with outstanding thermal and mechanical abilities exhibits beat neutron shielding property. The neutron transmission of SR/GO-PAAPBA-1.88 is 10% lower than that of SR. The SR nanocomposite with efficient thermal conductivity and neutron shielding ability has a promising prospect to be applied as advanced flexible shielding material.