Radiation-induced Modifications Research Articles

Gamma Radiation-Induced Modification in Mechanical Properties of Hybrid PVA (Go/Ag)-Based Polymer Nanocomposites

Gamma Radiation-Induced Modification in Mechanical Properties of Hybrid PVA (Go/Ag)-Based Polymer Nanocomposites

Radiation-induced modification effects in covalent-network glass formers: Phenomenological description within unified configuration-enthalpy model

Externally-induced modification activated by high-energy excitation such as γ-irradiation from 60Co source is analyzed in chalcogenide glasses in terms of radiation-structural and glass-relaxation metastability, at the example of sulphides (including stoichiometric arsenic trisulphide, As2S3) and selenides. Unified configuration-enthalpy model evolving conjugated configuration-coordinate (free energy in dependence on configuration coordinate) and thermodynamic enthalpy (temperature deviations in enthalpy, configurational entropy or free volume) diagrams is proposed to describe metastability in these glasses under external influences, such as (1) physical ageing, (2) irradiation, (3) thermal annealing, (4) rejuvenation, and their combinations. The model predicts glass stabilization in the ground state composed of partial sub-states related to (i) irradiation, (ii) rejuvenation, (iii) annealing, as well as (iv) ideal-glass deep states, connected by over-barrier jumping and through-barrier tunneling transitions. This model allows an adequate parameterization of optical responses related to metastability in these glasses defined through blue (bleaching) or red (darkening) shift in their optical transmission spectra.

Gamma radiation-induced modifications in the physiochemical features of ZnO nanoparticles synthesized using microwave technique

Zinc oxide nanoparticles (ZnO NPs) have a wide range of applications, and their properties can be significantly affected by gamma (γ) radiation, particularly in metal oxide semiconductor-based devices. This study investigates the impact of γ-irradiation on the physicochemical properties of ZnO NPs. The ZnO NPs were synthesized using a microwave method with zinc nitrate hexahydrate as a precursor and urea as a fuel. These synthesized ZnO NPs were exposed with γ rays emitted from 60Co radioactive source at different doses (0, 25, 50, and 75 kGy). We systematically examined the effects of γ irradiation on the structure, optical properties, and colloidal stability of the ZnO NPs using various techniques, including XRD, Raman spectroscopy, FTIR, SEM, UV–visible absorption, and zeta potential/particle size analysis (ZP/PSA). The characterization results revealed that γ irradiation caused significant alterations in the microstructure of ZnO NPs, resulting in reduced crystallite and grain sizes. Additionally, the optical properties and colloidal stability were found to be dose-dependent, with absorption spectra shifting towards the blue region, an increase in optical bandgap, and a decrease in zeta potential values as the dose rate of γ radiation increased.

Radiation-Induced Surface Modification of MXene with Ionic Liquid to Improve Electrochemical Properties and Chemical Stability.

For the first time, an ionic liquid was grafted onto Ti3C2Tx MXene interlayers (MXene-g-IL) using a radiation technique. The IL was tightly immobilized on the surface of MXene nanosheets via chemical linkage, which exhibited excellent specific capacitance (160 F g-1 at 5 mV s-1) and improved structural stability (maintaining the sheet-like structure for 180 days). The facile, efficient, and scalable synthetic strategy derived from the radiation technique can open a new avenue for covalent functionalization of MXene-based materials and promote their further application.

Efficient Removal of Cr(VI) by Protonated Amino-Bamboo Char Prepared via Radiation Grafting: Behavior and Mechanism

Biochar is considered to be the most promising substrate for the preparation of environmentally functional materials. The modification of bamboo char can significantly improve the removal rate of toxic ions from wastewater; however, there are few reports that focus on the radiation grafting method. Here, glyceride methacrylate (GMA) is successfully grafted onto bamboo char through electron beam radiation, followed by amination using the existing epoxide group in diethyltriamine, and finally, treated with hydrochloric acid to obtain protonated diethyltriamine-functionalized bamboo char (CDGBC). The results of IR, TG, XRD, and SEM prove the successful fabrication of a CDGBC biosorbent. The results show that the solution pH has a great effect on the adsorption capacity, and a maximum adsorption capacity of 169.13 mg/g is obtained at pH = 2 for Cr(VI). In addition, the adsorption behavior of Cr(VI) onto CDGBC is demonstrated to obey the pseudo-second-order kinetic and Freundlich isotherm models, and thermodynamic analysis exhibits that Cr(VI) adsorption is an endothermic spontaneous process. A possible adsorption mechanism based on the electrostatic interaction, reduction, and surface complexation is proposed, according to the obtained results. This work confirms that radiation-induced grafting modification can effectively transform biochar into a high-performance adsorbent for Cr(VI) removal, offering a new approach to synthesizing an efficient biosorbent.

Early stages of X-ray induced molecular unit modifications in poly(lactic acid)

Exposure of polymers to ionizing radiation and high-energy particle beams is involved in many processes – from food sterilization to radiotherapy protocols. The resulting effects, at the final stages, determine the functional, structural, and morphological alteration of the material. However, the processes responsible for cumulative chain scission, crosslinking, and reactions with the environment are often difficult to disentangle as a sequence of elementary events. Here we report a spectroscopic study – by attenuated-total reflection Fourier transform infrared spectroscopy and powder x-ray diffraction measurements, together with differential scanning calorimetry and thermogravimetric analyses – that sheds light on the very initial stages of the mechanisms involved in radiation-induced modifications of poly(lactic acid) (PLA). The results, collected on samples from biobased processes and exposed to low x-ray doses in the range of 100–103Gy after different thermal treatments, show spectroscopic evidence of the emergence of molecular unit perturbations – mainly related to methyl and carbonyl groups with the formation of C=C double bonds – with a clear-cut dependence on the polymer conformation. Understanding the mechanisms involved and the role of crystallinity provides information potentially useful for the development of PLA with a suitable radiation hardness for applications in radiotherapy.

Obacunone Photoprotective Effects against Solar-Simulated Radiation-Induced Molecular Modifications in Primary Keratinocytes and Full-Thickness Human Skin.

Solar radiation can cause damage to the skin, leading to various adverse effects such as sunburn, reactive oxygen species production, inflammation, DNA damage, and photoaging. To study the potential of photoprotective agents, full-thickness skin models are increasingly being used as in vitro tools. One promising approach to photoprotection involves targeting the redox-sensitive transcription factor Nrf2, which is responsible for regulating various cellular defense mechanisms, including the antioxidant response, inflammatory signaling, and DNA repair. Obacunone, a natural triterpenoid, has been identified as a potent Nrf2 agonist. The present study aims to evaluate the relevance of full-thickness (FT) skin models in photoprotection studies and to explore the potential photoprotective effects of obacunone on those models and in human keratinocytes. Phenion® full-thickness skin models and keratinocytes were incubated with increasing concentrations of obacunone and irradiated with solar-simulated radiation (SSR). Various photodamage markers were evaluated, including histological integrity, oxidative stress, apoptosis, inflammation, photoaging-related dermal markers, and photocarcinogenesis markers. Increasing doses of SSR were found to modulate various biomarkers related to sun damage in the FT skin models. However, obacunone attenuated cytotoxicity, inflammation, oxidative stress, sunburn reaction, photoaging, and photocarcinogenesis in both keratinocytes and full thickness skin models exposed to SSR. These results suggest that obacunone may have potential as a photoprotective agent for preventing the harmful effects of solar radiation on the skin.

Multi–length scale characterization of point defects in thermally oxidized, proton irradiated iron oxides

A key for the success of safe nuclear power generation system is to consider structural materials that are economical, meet mechanical property needs, possess good corrosion resistance, and are radiation tolerant. Nevertheless, fundamental insights that elucidate the details of radiation damage on materials corrosion performance are lacking. This includes the behavior of surface oxides which often regulate corrosion. For example, it is unclear how non-equilibrium point defects, oxide structure, mass transport in oxides, and subsequent oxidation behavior are altered by the radiation. In this work, some of the effects of proton irradiation on the attributes of point defects, iron oxide microstructures, and the physical nature of the oxidation product were correlated with corrosion behavior. Iron oxides, fabricated by thermal oxidation in air at 400°C and 800°C for 1 h, were subjected to 200 keV, 0.03 dpa (displacements per atom) of proton irradiation, and subjected to corrosion reactivity assessment using AC and DC electrochemical methods. Experimental methods that target materials information at different length scales, such as positron annihilation spectroscopy (atomistic), transmission electron microscopy (mesoscopic), and electrochemical methods (macroscopic), were coupled to shed light on the impact of radiation-induced defect modifications and structural changes in oxides on corrosion reactivity which ultimately affects durability in harsh environments.

ОКИСЛИТЕЛЬНАЯ МОДИФИКАЦИЯ ДНК ПЛАЗМИД СПОСОБСТВУЕТ ИХ ПРОНИКНОВЕНИЮ В ЦИТОПЛАЗМУ МЕЗЕНХИМНЫХ СТВОЛОВЫХ КЛЕТОК ЧЕЛОВЕКА

It is well known that the action of ionizing radiation causes oxidative stress in the cells of the body and leads to the synthesis of reactive oxygen species, which lead to multiple damage to cellular DNA, including the formation of oxidized bases. In this paper, we consider the effect of radiation-induced oxidative modification of plasmid DNA on their penetration into human mesenchymal stem cells. To study the role of oxidative DNA modification in cell penetration, a genetic construct was created based on the pEGFP-C1 (pC1) vector, GenBankAccession: U55763, containing as an insert an artificially synthesized DNA fragment containing a poly-G region (p12G) serving as target for efficient oxidation of the cloned DNA fragment. As a "marker", the selected vector contains the EGFP fluorescent protein (GFP) gene. Flow cytometry and fluorescence microscopy showed that recombinant constructs based on the pEGFP vector containing duplicated poly-G regions and Gn repeats penetrate cells much more efficiently than the original pEGFP vector. Exposure to radiation at a dose of 50 cGy, which causes an increase in the level of 8-oxodG in plasmids after irradiation, leads to a more intense penetration of oxidized plasmids compared to a similar experiment without irradiation.

Radiation-processed silk fibroin micro- /nano-gels as promising antioxidants: Electron beam treatment and physicochemical characterization

This study explored some aspects of the radiation-induced chemical modification of silk fibroin in pure water solution as a means to synthesize micro- /nano-gels with antioxidant properties and low cytotoxicity. The amino acid composition of the starting SF material was analyzed by NMR spectroscopy. Special attention was paid to the initial content and fate upon irradiation of the tyrosine residues. The effects of electron beam irradiation on aqueous solutions of silk fibroin was assessed by measuring structural and dimensional changes of SF particles in the solutions as a function of dose. This revealed the gradual decrease of the average hydrodynamic dimensions, initially in the 300–500 nm range for the unirradiated samples to values smaller than 100 nm for doses exceeding 20 kGy. Radical scavenging efficiency of the obtained micro- /nano-gels was assessed by DPPH-based spectrophotometric measurements which revealed the gradual enhancement of the antioxidant properties as a function of dose, yet with a correlated reduction of the scavenging kinetics. Cell viability tests have shown that introducing either the unirradiated or 10 kGy-irradiated SF micro-/nano-gels confirmed the low cytotoxicity of SF-based hydrogel materials, opening new perspectives for the radiation-mediated preparation of SF-based bioactive materials for biomedical and cosmetic applications.

The Radiation Environment of Ceres and Implications for Surface Sampling.

Ceres is a large water-rich dwarf planet located within the asteroid belt. Its surface displays evidence of material sourced from a deep subsurface liquid brine layer within recent geologic time, making it a candidate ocean world with possible present-day activity. However, Ceres lacks a substantial atmosphere and likely does not possess a global magnetic field. Therefore, any material emplaced or exposed on the surface will be subject to weathering by charged particles of solar and galactic origin. We have evaluated the effect of charged particle radiation on material within the near-surface of Ceres and find that the timescale for radiation-induced modification and destruction of organics and endogenic material is ∼100 Myr to 1 Gyr within the top 10-20 cm of the surface. Furthermore, we find that the timescale for sterilization of any putative living organisms contained within material at these depths is <500 kyr. Future missions to the surface may therefore consider targeting regions with geologic ages that fall between these two timescales to avoid the risk of backward contamination while ensuring that sampled material is not heavily radiation processed.

Effect of high-radiation-dose-induced structural modifications of HfSiO4/n-Si on electrical characteristics

High-k/n-Si structures were formed with HfSiO4 films annealed at the temperature range of RT (room temperature)-900 °C and radiation-induced structural modifications were determined by XRD (X-ray diffraction) and XPS (X-ray photoelectron spectroscopy) techniques in the study. The effect of oxygen-deficient bond contents on the electrical characteristics of HfSiO4 pMOS (n type Metal Oxide Semiconductor) capacitors whose radiation response was investigated in the 0–50 kGy dose range was investigated. While no XRD peak was observed before and after irradiation at RT and 500 °C-HfSiO4/n-Si, crystallization started with irradiation at 900 °C. The dielectric constant of the film was found in the range of 16–23. It was determined that Hf–Hf oxygen-deficient bonds act as negative charge trapping centers, while Hf–Si and Si–Si oxygen-defective bonds act as positive charge trapping centers. The direction of the C–V (Capacitance-Voltage) curve changed continuously with increasing radiation dose. The change in the interface trap charge density was found to be higher than the change in the oxide trap charge density for all doses in RT-HfSiO4 pMOS capacitor and for 1 kGy at 500 °C-HfSiO4 pMOS capacitor. Oxygen defective bond content and Hf-O-Si/Si–O–Si ratios were sufficient to establish a link between structural analyses and electrical characteristics at some doses. In some cases, the frequency-dependent charges had a more dominant effect on the radiation response of the device compared to the oxide trap charges.

On the Mechanism of Electron Beam Radiation-Induced Modification of Poly(lactic acid) for Applications in Biodegradable Food Packaging

Poly(lactic acid) (PLA) is a biodegradable polymer used for food packaging. The effects of electron beam radiation on the chemical and physical properties of amorphous PLA were studied. In this study, amorphous, racemic PLA was irradiated at doses of 5, 10, 15, and 20 kGy in the absence of oxygen. Utilizing electron paramagnetic resonance spectrometry, it was found that alkoxyl radicals are initially formed as a result of C-O-C bond scissions on the backbone of the PLA. The dominant radiation mechanism was determined to be H-abstraction by alkoxyl radicals to form C-centered radicals. The C-centered radicals undergo a subsequent peroxidation reaction with oxygen. The gel permeation chromatography (GPC) results indicate reduction in polymer molecular mass. The differential scanning calorimetry and X-ray diffraction results showed a subtle increase in crystallinity of the irradiated PLA. Water vapor transmission rates were unaffected by irradiation. In conclusion, these results support that irradiated PLA is a suitable material for applications in irradiation of food packaging, including food sterilization and biodegradation.

Ionizing radiation-induced epigenetic modifications and transgenerational effects

Nowadays a number of nations are exploring differences in gene expression resulting from changes in DNA methylation and modification of chromatin structure in response to external stimuli, such as radiation. It has been also well known that Ionizing radiation affects variety processes in exposed cells, in particular, cause changes in gene expression, mitochondria metabolic activity, chromosomal instability, apoptotic cell death and other changes at the molecular level. The point of view of the transgenerational nature of genomic instability suggests the possible involvement of epigenetic mechanisms. Kazakhstan has the potential to be exposed to a variety of hazardous materials, including radon, a radioactive gas that naturally occurs as a result of the indirect decay of uranium. It is also important to indicate that the Republic of Kazakhstan is considered the leader in terms of large reserves of uranium ores. Radioactive contamination is considered to be an important point that affects both the surrounding environment and human health. According to the World Health Organization, chronic exposure to radon and its decay products is the number one cause of lung cancer in non-smokers. All of the above facts prove the long-term pollution of the atmosphere by radiation has consequences for the health of the nation. Taking into account the importance of radon as a risk factor for lung cancer, this review focuses on discussion of possible radiation-induced alterations.

Raman investigations of the radiation-induced modifications in iPP-VGCNF nanocomposites: The nanofillers’ tale

• Isotactic polypropylene - Vapor Grown Carbon Nanofibers obtained by melt mixing of components. • Effect of gamma irradiation (using a Co60 source). in air, at integral doses ranging from 0 to 27 kGy on Raman spectra. • Effect of loading by Vapor Grown Carbon Nanofibers up to about 30 % wt. on Raman spectra analyzed. • Raman investigation of the D and G band parameters upon gamma irradiation and loading by vapor grown carbon nanofibers. Nanocomposites of isotactic polypropylene loaded by various amounts of vapor-grown carbon nanotubes ranging from 0 to 20% wt. were obtained by extrusion. Raman investigations on these nanocomposites are reported. The nanocomposites were irradiated using a 60 Co, with an integral dose of 1 kGy/h up to integral doses of 9 kGy, 18 kGy, and 27 kGy, in air, at room temperature. Raman measurements were performed by using a Bruker Senterra confocal Raman spectrometer operating at 785 nm. The research is focused on the information contained within the D and G Raman lines of these nanocomposites as a function of nanotube loading for various integral doses. The experimental data revealed the graduate silencing of the molecular motions assigned to the polymeric matrix due to the nanofiller and ionizing radiation. Based on experimental data, it is concluded that the positions of the D and G lines exhibit faint shifts due to the irradiation and that (on average) these shifts are consistent with the changes of the positions of D and G lines upon the increase of the loading with vapor-grown carbon nanofibers. Raman data suggest that the irradiation relaxes the pressure exerted on the nanofiller by the polymeric matrix, indicating a path to improve the physical features of polymer-carbon nanostructure nanocomposites. The research demonstrates the capability of Raman spectroscopy to sense the modifications of molecular vibrations in polymer-based nanocomposites, for both the polymeric matrix and the nanofiller.

New high-throughput endstation to accelerate the experimental optimization pipeline for synchrotron X-ray footprinting.

Synchrotron X-ray footprinting (XF) is a growing structural biology technique that leverages radiation-induced chemical modifications via X-ray radiolysis of water to produce hydroxyl radicals that probe changes in macromolecular structure and dynamics in solution states of interest. The X-ray Footprinting of Biological Materials (XFP) beamline at the National Synchrotron Light Source II provides the structural biology community with access to instrumentation and expert support in the XF method, and is also a platform for development of new technological capabilities in this field. The design and implementation of a new high-throughput endstation device based around use of a 96-well PCR plate form factor and supporting diagnostic instrumentation for synchrotron XF isdescribed. This development enables a pipeline for rapid comprehensive screening of the influence of sample chemistry on hydroxyl radical dose using a convenient fluorescent assay, illustrated here with a study of 26 organic compounds. The new high-throughput endstation device and sample evaluation pipeline now available at the XFP beamline provide the worldwide structural biology community with a robust resource for carrying out well optimized synchrotron XF studies of challenging biological systems with complex samplecompositions.

Stability of Antimicrobial Drug Molecules in Different Gravitational and Radiation Conditions in View of Applications during Outer Space Missions.

The evolution of different antimicrobial drugs in terrestrial, microgravity and hypergravity conditions is presented within this review, in connection with their implementation during human space exploration. Drug stability is of utmost importance for applications in outer space. Instabilities may be radiation-induced or micro-/hypergravity produced. The antimicrobial agents used in space may have diminished effects not only due to the microgravity-induced weakened immune response of astronauts, but also due to the gravity and radiation-altered pathogens. In this context, the paper provides schemes and procedures to find reliable ways of fighting multiple drug resistance acquired by microorganisms. It shows that the role of multipurpose medicines modified at the molecular scale by optical methods in long-term space missions should be considered in more detail. Solutions to maintain drug stability, even in extreme environmental conditions, are also discussed, such as those that would be encountered during long-duration space exploratory missions. While the microgravity conditions may not be avoided in space, the suggested approaches deal with the radiation-induced modifications in humans, bacteria and medicines onboard, which may be fought by novel pharmaceutical formulation strategies along with radioprotective packaging and storage.

Radiation-induced surface modification of silanized silica with n-alkyl-imidazolium ionic liquids and their applications for the removal of ReO4− as an analogue for TcO4−

As a radioactive fission product, 99Tc always existed in the combined extreme conditions of super acidity, high ionic strength, and strong radiation field, which made the efficient removal of Tc a challenge. Herein, for the first time, a series of n-alkyl-imidazolium ionic liquids were grafted onto silanized silica using radiation technique. The surface and structure properties of prepared adsorbents (SiO2-MPTS-[CnVIm]Br) were characterized by FT-IR, TGA, XPS, BET, and SEM-EDS. Subsequently, their adsorption properties for ReO4− (a nonradioactive surrogate of TcO4−) were studied in detail. These adsorbents exhibited an adsorption capacity of approximately 190 mg g−1 for ReO4−. It was found that adsorbents with longer alkyl chains showed better selectivity against ReO4− under the conditions of strong acids and a large excess of competitive ions. Column experiments indicated that these adsorbents could be recycled 10 times with negligible capacity loss. In addition, their adsorption performance remained unchanged after 800 kGy radiation. The column experiments of treating simulated radioactive wastewater proved that SiO2-MPTS-[CnVIm]Br was promising for selective separation of TcO4−/ReO4− from a variety of fission products. Lastly, XPS and FT-IR analysis confirmed that the adsorption mechanism was based on ion-exchange.

Radiation-induced modifications in copper oxide growth

Cu samples were irradiated with 10 MeV Au3+ ions at 200 °C to damage levels of 5, 10, and 15 displacements per atom (dpa) as an analogue to study long term self-irradiation effects of alpha-decay in Pu. Samples were then subject to accelerated aging at 350 °C for 1 h in air resulting in mixed oxide layer growth (Cu2O and CuO). Raman spectroscopy revealed that the CuO phase fraction was gradually decreased as the damage level increased. These findings indicate that accumulated damage from self-irradiation causes quantifiable modifications in metal oxidation that could serve as a novel forensic signature.

Breeding behavior of radiation-induced effects in organic materials and their possible use as radiation dosimeters

The present study reveals a deep association between the effects of gamma rays in irradiated organic substances and the age of the material after exposure. The late effects of radiation-induced modifications in polymeric material were investigated by means of the infrared signature and correlation with ultraviolet absorption. Detectors made of poly(allyl diglycol carbonate) were irradiated with doses between 500 Gy and 5 MGy and compared by means of similar samples aged 8 and 12 years. Infrared investigation showed the differences between infrared spectra recorded directly after irradiation and those recorded for the aged samples. The aging effect was found to be minor at low doses. For samples irradiated at high doses, the material digested itself through processes that have radiation breeding-fermentation behavior. Ultraviolet absorption revealed the presence of a hyperchromic effect and a bathochromic shift in connection with the age of these samples. This breeding behavior of radiation-induced effects in organic materials should be taken into account in dosimetry.