Enhanced Radiation Resistance Research Articles

Antimony-modified soda-lime-silica glass: Towards low-cost radiation-resistant materials

The development of inexpensive radiation-resistant glass is important for potential applications in displays, optics, and nuclear or space environments. This study considers the γ-ray and X-ray resistance of glasses relevant to low-cost float glass (i.e., SiO2–Na2O–CaO–MgO), modified with various concentrations (0 – 10 mol%) of Sb2O3. Various doses (0, 0.2, 2.0, and 5.0 MGy) of γ-rays from the decay of 60Co nuclei, and X-rays generated by an X-ray fluorescence (XRF) spectrometer, have been applied to this series of Sb2O3-modified float-type glasses to study their resistance to radiation-induced damage. Irradiation leads to the formation of various defect centres (HC2, HC1, TE, E', and E− types). These radiation-induced defects cause photo-darkening of the glass, which reduces its visible-wavelength optical transparency. The addition of Sb2O3 to these glasses led to reductions in the formation of radiation-induced defect-centres, combined with forbidden bandgap narrowing which led to non-linear changes in visible-wavelength absorption as a function of Sb2O3 content such that the most transparent irradiated glasses were advantageously obtained at low (0.5 mol%) Sb2O3 content. The mechanisms of defect-formation involve the creation of Sb4+-ions which assists in mitigating the effects of irradiation on the visible-wavelength transparency of the glass. The 0.5 mol% of Sb2O3-modified float glass provided a maximized concentration of Sb4+-ions upon γ-ray irradiation. Combined with the smallest changes in the UV band gap narrowing, it enabled this glass to retain the highest visible-wavelength transparency at all doses of ionizing radiation studied (0.2, 2 and 5 MGy). This work confirms the substantially enhanced radiation resistance of Sb2O3-modified float-type glasses compared to standard float glass, which could potentially be further developed towards commercialization, for example as a low-cost solution for radiation resistant applications.

Radiation resistance property of barium gallo-germanate glass doped by Nb2O5

Effects of Nb2O5 dopant on the radiation response of barium gallo-germanate (BGG) glass are studied mainly by electron paramagnetic resonance and absorption spectroscopy. Owing to the Nb5+↔Nb3+ interconversion in doped samples, formations of Ge-related non-bridging oxygen hole center and Ge-related electron center defects after γ-ray irradiation are inhibited. Thereby, Nb2O5 dopant can enhance radiation resistance of BGG glass, and 1.0% Nb2O5 concentration is the best.

Effect of gamma and neutron irradiation on properties of boron nitride/epoxy resin composites

Improving the radiation resistance of epoxy resin (EP) is pivotal for the reliability of equipment and the safety of facilities in the nuclear industry. Hexagonal boron nitride (h-BN) is attractive in the preparation of radiation-resistant materials due to its good radiation stability and neutron shielding capability. In this work, h-BN/EP composites with enhanced radiation resistance were fabricated by solution blending. The tensile strength and thermal properties of the composites after γ-ray and neutron irradiation were investigated. The results showed that the addition of h-BN improved the mechanical property and the glassy transition temperature of the resin. The presence of low-level h-BN was favorable to enhance the radiation resistance of EP. As for composites with the 0.05% mass percentage of h-BN, the absorbed dose required to decrease relative tensile strength by 50% was about 300 kGy, which was higher than that of neat EP. The intrinsic mechanism of radiation resistance was attributed to the oxygen barrier effect as investigated by XPS and EPR. Then, benefiting from the absorbing neutrons capability of boron atoms, an addition of 0.55% h-BN to the EP resin could reduce the neutron transmittance of the resin by 5.6%. This study demonstrates that the blending with h-BN can increase the radiation-resistant property of EP resin, meanwhile augmenting the neutron shielding ability.

Simulations of primary damage in a High Entropy Alloy: Probing enhanced radiation resistance

High Entropy Alloys (HEA) attract attention as possible radiation resistant materials, a feature observed in some experiments that has been attributed to several unique properties of HEA, in particular to the disorder-induced reduced thermal conductivity and to the peculiar defect properties originating from the chemical complexity. To explore the origin of such behavior we study the early stages (less than 0.1 ns), of radiation damage response of a HEA using molecular dynamics simulations of collision cascades induced by primary knock-on atoms (PKA) with 10, 20 and 40 keV, at room temperature, on an idealized model equiatomic quinary fcc FeNiCrCoCu alloy, the corresponding “Average Atom” (AA) material, and on pure Ni. We include accurate corrections to describe short-range atomic interactions during the cascade. In all cases the average number of defects in the HEA is lower than for pure Ni, which has been previously used to help claiming that HEA is radiation resistant. However, simulated defect evolution during primary damage, including the number of surviving Frenkel Pairs, and the defect cluster size distributions are nearly the same in all cases, within our statistical uncertainty. The number of surviving FP in the alloy is predicted fairly well by analytical models of defect production in pure materials. All of this indicates that the origin of radiation resistance in HEAs as observed in experiments may not be related to a reduction in primary damage due to chemical disorder, but is probably caused by longer-time defect evolution.

Targeted Proteomic Analysis Revealed Kinome Reprogramming during Acquisition of Radioresistance in Breast Cancer Cells.

Radiotherapy constitutes a major therapeutic modality for early management of breast cancer. Despite the high efficacy in treating breast cancer (BC), radiation resistance and tumor recurrence are major hurdles in breast cancer radiotherapy. Herein, stable isotope labeling by amino acids in cell culture (SILAC) was employed, along with the parallel-reaction monitoring (PRM)-based targeted quantitative proteomic method, to examine the differences in kinase protein expression in MCF-7 and MDA-MB-231 breast cancer cells and their corresponding radioresistant C6 and C5 clones. We quantified the relative protein expression levels of 300 and 281 kinases in C5/MDA-MB-231 and C6/MCF-7 pairs of breast cancer cells, respectively. We also showed that TAF9, which was one of the differentially expressed kinases, enhances radiation resistance in breast cancer cells. Moreover, a correlation analysis of gene expression suggested TAF9's role in upregulating the expression of genes involved with radioresistance. Overall, our study uncovered a large number of differentially expressed kinases accompanied with the acquisition of radioresistance and revealed a role of TAF9 in promoting radioresistance in breast cancer.

Omnidirectional Circularly Polarized Antenna Based on Counter-Wound Helices

An innovative counter-wound helical antenna with omnidirectional circular polarization (OCP) is reported in this communication, with a significantly enhanced radiation resistance and matching bandwidth compared with the conventional normal-mode CP helix counterpart. The antenna is realized by combining several helical radiators with opposite winding directions. A three-segment OCP counter-wound helix is studied, featuring one right-handed helix in the middle and two left-handed helices sandwiching it from the top and the bottom. Besides achieving a stable OCP pattern with gain variations of less than 0.2 dB, the radiation resistance at the operating frequency f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is increased to 26.7 Ω compared with 3.3 Ω of the traditional uniform-wound helix. Theoretical analysis and simulations are presented. To further enhance the radiation resistance, a five-segment helical antenna prototype is demonstrated and tested. The radiation resistance rises further to 80.9 Ω at f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and the measured matching bandwidth reaches 2.8%, surpassing that of the conventional OCP helix by four times. Stable OCP radiation with a realized gain of up to 2.5 dBic is observed. Being compact and simple, the developed helical antenna could represent an ideal candidate for various wireless applications, for example, device-to-device (D2D) communications that require OCP radiations.

MiR-183 promotes radioresistance of lung adenocarcinoma H1299 cells via epithelial-mesenchymal transition.

Lung adenocarcinomas are usually sensitive to radiation therapy, but some develop resistance. Radiation resistance can lead to poor patient prognosis. Studies have shown that lung adenocarcinoma cells (H1299 cells) can develop radioresistance through epithelial-mesenchymal transition (EMT), and this process is regulated by miRNAs. However, it is unclear which miRNAs are involved in the process of EMT. In our present study, we found that miR-183 expression was increased in a radioresistant lung adenocarcinoma cell line (H1299R cells). We then explored the regulatory mechanism of miR-183 and found that it may be involved in the regulation of zinc finger E-box-binding homeobox 1 (ZEB1) expression and mediate EMT in lung adenocarcinoma cells. qPCR results showed that miR-183, ZEB1, and vimentin were highly expressed in H1299R cells, whereas no difference was observed in E-cadherin expression. Western blot results showed that ZEB1 and vimentin were highly expressed in H1299R cells, while E-cadherin expression was decreased. When miR-183 expression was inhibited in H1299R cells, radiation resistance, proliferation, and cell migration were decreased. The expression of ZEB1 and vimentin in H1299R cells was decreased, while the expression of E-cadherin was increased. Moreover, miR-183 overexpression in H1299 cells enhanced radiation resistance, proliferative capacity, and cell migration ability. The expression of ZEB1 and vimentin in H1299 cells was increased, while that of E-cadherin was decreased. In conclusion, miR-183 may promote EMT and radioresistance in H1299 cells, and targeting the miR-183-ZEB1 signaling pathway may be a promising approach for lung cancer treatment.

Geomagnetic Shielding Enhances Radiation Resistance by Promoting DNA Repair Process in Human Bronchial Epithelial Cells.

With the advent of long-duration space explorations, ionizing radiation (IR) may pose a constant threat to astronauts without the protection of Earth’s magnetic field, or hypomagnetic field (HMF). However, the potential biological effects of a HMF on the cellular response to IR have not been well characterized so far. In this study, immortalized human bronchial epithelial cells were exposed to X-rays under either a geomagnetic field (GMF, ~50 uT) or HMF (<50 nT) culture condition. A significant increase of the cell survival rate in HMF after radiation was observed by colony formation analysis. The kinetics of DNA double-strand breaks (DSBs), determined by γH2AX foci formation and disappearance, presented a faster decrease of foci-positive cells and a significantly lower mean number of γH2AX foci per nucleus in HMF-cultured cells than in GMF-cultured cells after radiation. In addition, a γH2AX/53BP1 colocalization assay showed an upregulated DSB recovery rate in HMF cultured cells. These findings provided the first evidence that HMF exposure may enhance the cellular DSB repair efficiency upon radiation, and consequently modulate the genotoxic effects of IR.

Helium implantation damage resistance in nanocrystalline W-Ta-V-Cr high entropy alloys

Nanocrystalline W-Ta-Cr-V high entropy alloys have shown promising properties as nuclear fusion materials with enhanced radiation resistance to heavy ion irradiation and negligible radiation hardening. In this work, we investigate the performance of the alloy under low energy helium (He) implantation up to a fluence of 1.25 × 1017 cm−2 at 1223 K. We observe a uniform high density of very small (~2–3 nm) bubbles grown at a slow rate along with enhanced He bubble damage resistance, further marked by no preferential bubble formation on the grain boundaries, even at much higher fluences compared to previously implanted tungsten grades. First principle calculations of He formation and migration energies in this alloy indicate deep energetic wells on the potential landscape and low diffusivity of He compared to pure W. The results imply higher overall (considering both grain matrices and grain boundaries) implantation resistance due to slow He diffusion and accumulation, and confirm the enhanced vacancy-self interstitial recombination argument in these alloys.

Sequential ion irradiations on Fe-Cr and ODS Fe-Cr alloys

• Sequential dual He/Fe irradiation at RT of a model Fe14Cr alloy and an ODS steel. • Both show small (<2nm) irradiation induced bubbles, mostly in the ferritic matrix. • TEM investigations of the ODS steel suggest that nanoparticles remain quite stable. • DB PAS suggest that He associates with vacancies introduced by the Fe+ irradiation. Oxide dispersion strengthened steels are candidate materials for nuclear reactor applications due to a powerful combination of properties, such as reduced activation, high-temperature strength and increased creep resistance. The dispersion of nanometric oxide particles in the steel matrix may also enhance radiation resistance by acting as trapping sites for irradiation induced defects. In this work, an Fe–14Cr–2 W–0.3-Ti–0.3Y 2 O 3 (wt%) steel and a model Fe-14Cr (wt%) alloy were sequentially irradiated with He + and Fe + ions up to 15 dpa and 8000 appm to simulate fusion radiation damage. Their microstructural stability was investigated by positron annihilation spectroscopy and transmission electron microscopy. Transmission electron microscopy studies show that under these irradiation conditions there are no significant changes in the mean size, qualitative chemical composition and number density of nanoparticles, although the irradiation appears to induce a slight coarsening of the smaller nanoparticles. Both materials exhibit very small (<2 nm) irradiation-induced bubbles, with similar sizes but lower number density in the ODS steel. Positron annihilation spectroscopy results show the presence of irradiation induced open volume defects, much more noticeable in the model alloy. In both alloys, helium appears to associate with the newly formed vacancy-type defects introduced by the subsequent Fe + irradiation.

Enhanced radiation resistance of ytterbium-doped silica fiber by pretreating on a fiber preform

We propose a new pretreatment method on fiber preforms by loading deuterium (D2), pre-irradiation, combined with thermal annealing. The effect of the pretreatment condition on the optical loss at 1200 nm and a laser slope efficiency of ytterbium-doped silica fibers (YDFs) before and after γ-radiation was comparatively investigated. The related mechanism was revealed by combining the optical absorption, continuous wave electron paramagnetic resonance (CW-EPR), Raman, and Fourier transform infrared (FTIR) spectroscopies. A laser experiment shows that the radiation resistance of YDFs can be significantly improved by the pretreatment on a fiber preform. Also, this new pretreatment method has no obvious negative impact on the laser performance of non-irradiated YDFs. Furthermore, the vacuum experiment confirms that the YDF obtained by this method, named pretreated YDF, may have a long-term radiation stability when it is used in a vacuum environment (such as space). CW-EPR spectra show that the formation of color centers was effectively inhibited in pretreated YDF, which is correlated with the decrease of color center precursor and the existence of the deuterium radical as confirmed by Raman and FTIR spectra.

RADIATION RESISTANT BIPOLAR SOI TRANSISTORS

In this paper the new design of lateral bipolar transistors is presented, made on the basis of the charge carrier transport modeling. New design provides high level of base current transmission coefficient and enhanced radiation resistance. The manufacturing technology of the lateral bipolar transistors is compatible with a submicron SOI CMOS technology and can be of vital importance when developing RF analogue-to-digital microcircuits for ionizing radiation resistant satellite-navigation equipment.

Enhanced Radiation Resistance of Pure-Silica-Core Polarization-Maintaining PANDA Optical Fibers

Radiation-induced absorption (RIA) is investigated at $ \lambda = {1.55}~ \mu \text{m}$ in technologically improved pure-silica-core (PSC) PANDAs, in which we minimized drawing-induced silica network strain. The results of the steady-state $\gamma $ - and pulsed-X-ray irradiations are compared with those obtained earlier on former, non-optimized PSC PANDAs. It is found that the technological improvements have resulted in nearly complete suppression of the most deleterious RIA band at ~1 eV to drastically improve the radiation resistance of the PSC PANDAs.

Erbium-doped optical fibre with enhanced radiation resistance for superluminescent fibre sources

This paper presents a study of the properties of erbium-doped optical fibres with enhanced gamma-ray resistance at a high dose rate. The fibres have a silica core containing different dopants. The gamma-ray resistance of the fibres is due to additional doping of their core with cerium and germanium ions, as well as to aluminium concentration optimisation. We assess the effect of fibre composition on the radiation-induced loss at a wavelength of 1310 nm and the output power and weighted average wavelength of superluminescent fibre sources based on erbium-doped fibre under pulsed gamma irradiation (dose per pulse, ∼ 20 Gy). The fibre doped with aluminium, germanium and cerium oxides is shown to be optimal for use in gamma-ray-resistant broadband superluminescent fibre sources.

Polysulfone–Ceria Mixed-Matrix Membrane with Enhanced Radiation Resistance Behavior

A novel polysulfone–cerium oxide (Psf–ceria) mixed-matrix membrane (MMM) with enhanced γ radiation resistant property was developed. Ceria nanoparticles were synthesized by gel-combustion route and...

NMDA Receptor-Mediated Signaling Pathways Enhance Radiation Resistance, Survival and Migration in Glioblastoma Cells-A Potential Target for Adjuvant Radiotherapy.

Glioblastoma is one of the most aggressive malignant brain tumors, with a survival time less than 15 months and characterized by a high radioresistance and the property of infiltrating the brain. Recent data indicate that the malignancy of glioblastomas depends on glutamatergic signaling via ionotropic glutamate receptors. In this study we revealed functional expression of Ca2+-permeable NMDARs in three glioblastoma cell lines. Therefore, we investigated the impact of this receptor on cell survival, migration and DNA double-strand break (DSB) repair in the presence of both, glutamate and NMDAR antagonists, and after clinically relevant doses of ionizing radiation. Our results indicate that treatment with NMDAR antagonists slowed the growth and migration of glutamate-releasing LN229 cells, suggesting that activation of NMDARs facilitate tumor expansion. Furthermore, we found that DSB-repair upon radiation was more effective in the presence of glutamate. In contrast, antagonizing the NMDAR or the Ca2+-dependent transcription factor CREB impaired DSB-repair similarly and resulted in a radiosensitizing effect in LN229 and U-87MG cells, indicating a common link between NMDAR signaling and CREB activity in glioblastoma. Since the FDA-approved NMDAR antagonists memantine and ifenprodil showed differential radiosensitizing effects, these compounds may constitute novel optimizations for therapeutic interventions in glioblastoma.

High expression of RAD18 in glioma induces radiotherapy resistance via down-regulating P53 expression

As a key regulator of DNA translesion synthesis (TLS) pathway, RAD18 is reported to be abnormally expressed in many kinds of cancers. In glioma, RAD18 was overexpressed in the primary and recurrent glioblastoma multiforme specimens, and its overexpression weakened ionizing radiation-induced apoptosis in glioma A172 cells. Moreover, A172 cells with mutational P53 also showed enhanced radiation resistance. And RAD18 activation induced by cyclin-dependent kinase 2 (CDK2) was repressed by P53. However, whether P53 involves in RAD18-induced radiation resistance remains unknown. Therefore, this study was conducted to explore the effects and mechanism of RAD18 in the radiation resistance of glioma and study P53 role in this process. Results showed that, RAD18 expression was obviously elevated in glioma tissues and cell lines such as U251, SHG-44, A172, U-87 MG and U-118 MG as compared with the normal brain tissues and neuroglia cells. Up-regulation of RAD18 in U-118 MG and A172 cells with lentivirus infection significantly increased cell growth and inhibited cell apoptosis, determined by CCK-8 and flow cytometry technologies. Besides, RAD18 overexpression enhanced cell growth and inhibited cell apoptosis after U-118 MG or A172 cells were irradiated at a dose of 4 Gy. On the contrary, silencing of endogenous RAD18 sensitized U-118 MG and A172 cells to radiation. Moreover, RAD18 and P53 proteins were co-located in the nucleus, and up-regulation of RAD18 decreased the expression of P53 protein and facilitated its nuclear export. Furthermore, cell growth promotion and cell apoptosis inhibition induced by RAD18 up-regulation were impaired when P53 expression was up-regulated under radiation condition. In a word, this study clarifies that RAD18 functions as a promoter in glioma progression and reduces glioma cells’ sensibility to radiation through down-regulating P53, which provides new strategies to overcome the radiation resistance in glioma.

Activation of PTGS2/NF‐κB signaling pathway enhances radiation resistance of glioma

ObjectiveWe focused on the effects of PTGS2/NF‐κB signaling pathway on the radiation resistance of glioma in the study.MethodsWe downloaded the microarray data from the Gene Expression Omnibus (GEO) database. We verified transfection successfully through QRT‐PCR analysis. Immunofluorescence was used to detect γH2AX content under 2 Gy radiation. The survival rates of cells under 2 Gy irradiation were tested by clonogenic survival assay. Flow cytometry was used to detect cell cycle. Western blot was applied to detect the expression of NF‐κB pathway‐related proteins. We also used MTT assay to detect the proliferation of cells.ResultsIn this research, we discovered that the expression of the PTGS2 was upregulated in radiation‐resistant glioma cells. The radio‐tolerance rate of U87 cells was obviously elevated after the overexpression of PTGS2. The radioresistance of U87R cells was significantly reduced after the knockdown of PTGS2. After radiotherapy, the number of cells arrested in G2/M phase decreased after PTGS2 overexpression in U87cells but increased in PTGS2 knockdown in U87R cells. The survival rate of U87 and U87R cells under radiation decreased significantly after the addition of NF‐κB inhibitor. The proliferation of U87 cells was suppressed by radiation and the addition of Bay 11. In addition, PTGS2 activated NF‐κB signaling pathway and prevented DNA damage after radiotherapy. Lastly, PTGS2 was proved to facilitate tumor cell proliferation and improve the radio‐tolerance.Conclusion PTGS2/NF‐κB signaling pathway was involved in radio‐tolerance of glioma cells, which provided a new insight into glioma therapy.

MiR-182 enhances radioresistance in non-small cell lung cancer cells by regulating FOXO3.

Upregulated in lung cancer, miRNA-182 was found to be related to cancer proliferation and chemoresistance. However, there is no report on the role of miR-182 in radioresistance, which is a main obstacle of radiotherapy. In this study, we aim to depict the effect of miR-182 inhibition on cellular sensitivity to ionizing radiation. Our data confirm that miR-182 is upregulated in lung cancers and tissues and that miR-182 is responsive to irradiation. We also show that miR-182 knockdown suppresses cell proliferation and increases cell apoptosis after irradiation. DNA damage remains unrepaired in miR-182 knockdown cells, which results in cell cycle arrest. Finally, we find that FOXO3 is a direct target of miR-182 and that overexpression of FOXO3 enhances radiation resistance in miR-182 knockdown cells. In conclusion, our data suggest that miR-182 might account for radioresistance in lung cancer and that miR-182-FOXO3 provides a novel radiosensitizing target.

Exploring radiation induced segregation mechanisms at grain boundaries in equiatomic CoCrFeNiMn high entropy alloy under heavy ion irradiation

High entropy alloys have gained significant interest due to several unique properties including enhanced radiation resistance. In this work, radiation induced segregation, a key phenomenon observed in alloys under irradiation, is examined for the first time at high angle grain boundaries under Ni heavy ion irradiation in the CoCrFeNiMn alloy. Our experimental study indicates significant Mn depletion and Co and Ni enrichment at grain boundaries. The segregation is discussed in the context of a proposed vacancy dominated radiation induced segregation mechanism and compared to existing models in conventional single core component alloys including stainless steels.