kGy 60Co Research Articles

New lead-free chemistry for in-situ monitoring of advanced nuclear power plant

Nuclear power is essential for sustainable energy infrastructure and economic development, necessitating materials for high-radiation environments that can facilitate visualization and observation. Conventional lead glass is inadequate for future requirements due to radiation-induced darkening, poor mechanical properties, and toxicity. Therefore, there is urgent to find new window materials that offer multi-ionization shielding (particularly against deep-penetrating gamma ray, γ, and neutron, n, radiations), desirable opto-mechanical properties, service stability against darkening, and non-toxicity. In this study, we report a family of transparent rare-earth pyrochlore ceramics LaxGd2−xZr2O7, offering unique chemo-physical properties that are ideal for robust radiation shielding windows. Remarkably, we demonstrated the capability of maintaining high transparency under heavy-dose exposure to 1000 ​kGy 60Co γ radiation. We observed the service stability against radiation darkening can be greatly enhanced with La-rich compositions, while Gd-rich compositions undergo shallow darkening that can be reversibly recovered under visible light. This behavior is attributed to mitigated oxygen migration from 48f to 8a in La-rich compositions, which have high pyrochlore phase stability and well-ordered atomic structures, and reversible oxygen migration between 48f and 8a in Gd-rich compositions, which remain active at room temperature. Our proposal and demonstration unlock ample opportunities in designing functional transparent ceramics as window materials for demanding applications in high-radiation environments.

Conveniently synthesis of porous crown-based resin with efficient 90Sr capture from highly acidic wastewater

Effective removal of radioactive 90Sr is crucial for both management of spent nuclear fuel and recovery of radioactive strontium resources, while it’s still a great challenge due to the presence of high acid levels and intense radiation. Herein, a novel porous resin (DtBuCH18C6@CG-71) were synthesized by introducing 4′,4″(5″)-di-tert-butyldicyclohexano-18-crown-6 onto CG-71 resin using vacuum impregnation. The DtBuCH18C6@CG-71 resin maintains superior adsorption abilities in extreme conditions, including high acid resistance (3–12 mol/L HNO3), substantial γ-irradiation (200 kGy 60Co), and elevated temperatures (50–100 ℃). Impressively, even when exposed to a high concentration of matrix ions (59 elemental ions), the Sr(II) adsorption ratio onto DtBuCH18C6@CG-71 resin remains near 100 % even in highly acidic condition, which performance outpaces most of commercial resins. Dynamic column tests using an automated separation system further confirmed the superior ability of DtBuCH18C6@CG-71 in term of extracting Sr(II) from wastewater. Given its impressive features, cost-effectiveness, and scalability, DtBuCH18C6@CG-71 resin holds promising potential for 90Sr disposal in nuclear wastewater.

Influence of 60Co-γ Irradiation on the Components of Essential Oil of Curcuma.

The gas chromatography-ion mobility spectrometry (GC-IMS) method is a new technology for detecting volatile organic compounds. This study was carried out to evaluate the effects of volatile aroma compounds of Curcuma essential oils (EOs) after 60Co radiation by GC-IMS. Dosages of 0, 5, and 10 kGy of 60Co were used to analyze EOs of Curcuma after 60Co irradiation (named EZ-1, EZ-2, and EZ-3). The odor fingerprints of volatile organic compounds in different EOs of Curcuma samples were constructed by headspace solid-phase microextraction and GC-IMS after irradiation. The differences in odor fingerprints of EOs were compared by principal component analysis (PCA). A total of 92 compounds were detected and 65 compounds were identified, most of which were ketones, aldehydes, esters, and a small portion were furan compounds. It was found that the volatile matter content of 0 kGy and 5 kGy was closer, and the use of 10 kGy 60Co irradiation would have an unstable effect on the EOs. In summary, it is not advisable to use a higher dose when using 60Co irradiation for sterilization of Curcuma. Due to the small gradient of irradiation dose used in the experiment, the irradiation dose can be adjusted appropriately according to the required sterilization requirements during the production and storage process of Curcuma to obtain the best irradiation conditions. GC-IMS has the advantages of GC's high separation capability and IMS's fast response, high resolution, and high sensitivity, and the sample requires almost no pretreatment; it can be widely used in the analysis of traditional Chinese medicines containing volatile components. It is shown that irradiation technology has good application prospects in the sterilization of traditional Chinese medicines, but the changes in irradiation dose and chemical composition must be paid attention to.

Highly selective removal of Technetium-99 using imidazolium-based macroporous anion exchange resins

Technetium-99 (99Tc), as a β-emitting radionuclide, is one of the main components of nuclear waste. The fast environmental mobility of 99TcO4- makes it a great threat to the environment and human beings. Although some adsorption materials have been developed to remove 99TcO4- from the nuclear wastewater, the low selectivity and poor stability under acid and radiation conditions limit their actual application. In this work, an N-methylimidazolium modified macroporous anion exchange resin (PMiMCl) was developed for the highly selective removal of 99TcO4-. Batch adsorption experiments demonstrated that the PMiMCl resin exhibited high adsorption capacity (Re(VII), 677.21 mg g−1) in a wide pH range (3–7). The resin showed high stability after acid (5 mol L-1 HCl), alkali (5 mol L-1 NaOH) and radiation (1000 KGy 60Co γ) treatment and the remove ability was little influenced. More importantly, in the presence of high concentration of competing anions, the removal efficiency of 99TcO4- with PMiMCl resin can also reach to 97.64%, which was much higher than those treated by commercial resins (93.02% for ZGANR170 and 93.10% for IRN78), demonstrating its good selectivity. The density functional theory calculations revealed that the high selectivity was attributed to the strongest interaction of imidazole cation in PMiMCl resin with 99TcO4- anion compared with NO3−, SO42− and Cl− anions. These superior features coupled with low cost and feasible for large scale production and application make PMiMCl resin great potential for 99Tc removal in nuclear wastewater.

Indigenous and commercial isolates of arbuscular mycorrhizal fungi display differential effects in Pyrus betulaefolia roots and elicit divergent transcriptomic and metabolomic responses.

Arbuscular mycorrhizal fungi (AMF) are beneficial soil fungi which can effectively help plants with acquisition of mineral nutrients and water and promote their growth and development. The effects of indigenous and commercial isolates of arbuscular mycorrhizal fungi on pear (Pyrus betulaefolia) trees, however, remains unclear. Trifolium repens was used to propagate indigenous AMF to simulate spore propagation in natural soils in three ways: 1. the collected soil was mixed with fine roots (R), 2. fine roots were removed from the collected soil (S), and 3. the collected soil was sterilized with 50 kGy 60Co γ-radiation (CK). To study the effects of indigenous AMF on root growth and metabolism of pear trees, CK (sterilized soil from CK in T. repens mixed with sterilized standard soil), indigenous AMF (R, soil from R in T. repens mixed with sterilized standard soil; S, soil from S in T. repens mixed with sterilized standard soil), and two commercial AMF isolates (Rhizophagus intraradices(Ri) and Funneliformis mosseae (Fm)) inoculated in the media with pear roots. Effects on plant growth, root morphology, mineral nutrient accumulation, metabolite composition and abundance, and gene expression were analyzed. AMF treatment significantly increased growth performance, and altered root morphology and mineral nutrient accumulation in this study, with the S treatment displaying overall better performance. In addition, indigenous AMF and commercial AMF isolates displayed common and divergent responses on metabolite and gene expression in pear roots. Compared with CK, most types of flavones, isoflavones, and carbohydrates decreased in the AMF treatment, whereas most types of fatty acids, amino acids, glycerolipids, and glycerophospholipids increased in response to the AMF treatments. Further, the relative abundance of amino acids, flavonoids and carbohydrates displayed different trends between indigenous and commercial AMF isolates. The Fm and S treatments altered gene expression in relation to root metabolism resulting in enriched fructose and mannose metabolism (ko00051), fatty acid biosynthesis (ko00061) and flavonoid biosynthesis (ko00941). This study demonstrates that indigenous AMF and commercial AMF isolates elicited different effects in pear plants through divergent responses from gene transcription to metabolite accumulation.

50 kGy–100 kGy 60Co γ-irradiation effects on structural and DC-electrical properties of sol–gel synthesized ZnF NPs

50 kGy–100 kGy 60Co γ-irradiation effects on structural and DC-electrical properties of sol–gel synthesized ZnF NPs

Effect of gamma irradiation on shelf life and quality of indigenous chicken meat

The experiment was conducted on fresh indigenous chicken meat treated with 0 (non-irradiated), 1, 2 and 3 kGy 60Co gamma irradiation and stored for 0, 30 and 60 days at -20ºC to investigate the effects on proximate components, sensory attributes, and physicochemical, biochemical and microbial changes in meat quality. Data were analyzed under 4x3 factor CRD design of experiment in GLM procedure of SAS statistical package. The results showed that irradiation groups had significantly (p<0.05) higher color and tenderness of meat compared to that of non-irradiated group. The 2 kGy group showed significantly (p<0.05) higher Dry matter (DM) and Ether extract (EE) whereas the cooking loss, Free fatty acid (FFA), Peroxide value (PV), and Thiobarbituric acid reactive substances (TBARS) levels were higher in 3 kGy irradiated group. With the advancement of storage periods pH significantly (p<0.05) decreased. The 2 kGy irradiation group showed significantly (p<0.05) lower numbers of Total viable count (TVC), Total coliform count (TCC), Total yeast and mold count (TYMC) compared to non-irradiated group. From this study, it may be concluded that the 2 kGy irradiated group had positive effects on sensory evaluation, biochemical and microbial qualities of indigenous chicken meat to increase the shelf life and the quality of indigenous chicken meat.
 
 J Bangladesh Agril Univ 17(4): 560–566, 2019

Effect of 60Co γ-Irradiation on Physicochemical Properties of Adlay During Storage Period

Abstract γ-Irradiation is applied to many agricultural products as a method for quality control. This study investigated the influence of γ-irradiation on physicochemical properties of adlay. Adlay samples were treated with 0 to 4.0 kGy 60Co γ-irradiation and subsequently stored at cool temperature (8 to 10 °C). Hardness of all treatment groups showed no marked changes at 0 kGy but exhibited variations at 2.0 and 4.0 kGy. Linoleic acid (C18:2) was the most sensitive to irradiation among 11 fatty-acid compositions. Saturated fatty-acid (SFA) content was increased, whereas unsaturated fatty acid was reduced by dose augmentation. Types of volatile compound increased from 15 to 21, and the major compound n-hexanol was increased by 80.41 % after 4-kGy irradiation. Odor changes caused by doses of irradiation were more remarkable than those caused by 12 months of storage. Hence, we conclude that 1.0 kGy irradiation barely affects physicochemical properties during storage; it could be an alternative way to control quality of adlay during storage.

Decay resistance of polymerized ionic liquid-modified woods

A functional ionic liquid 1-butyl-3-vinylimidazolium iodide ([BuVyIm]I) was synthesized, and it exhibited the features of both decay resistance and leaching resistance after in-situ polymerization within wood. Treated wood specimens of Cryptomeria japonica were evaluated in this preliminary study using leaching tests with distilled water and decay tests for 12 weeks with brown rot fungi Fomitopsis palustris. The [BuVyIm]I polymerized by 100 kGy 60Co gamma irradiation was retained in wood after 10 wash and dry cycles, whereas nearly all of the [BuVyIm]I was washed out in the cases of 10 kGy and no irradiation. The decay testing of these specimens showed that sapwood had a different decay resistance depending on the strength of gamma irradiation used, whereas the treated heartwood did not support fungal growth. The results of this study imply that [BuVyIm]I polymerized by 100 kGy gamma irradiation have potential for wood preservation.

Effect of 60Co γ-ray irradiation on electrical properties of Ti/Au/GaAs1−xNx Schottky diodes

Current-voltage (I-V), capacitance-voltage-frequency (C-V-f) and conductance-voltage-frequency (G/ω-V-f) measurements at room temperature are used to study 50 kGy 60Co γ-ray electrical properties irradiation dependence of Ti/Au/GaAs1−xNx Schottky diodes with 0.2%; 0.4%; 0.8% and 1.2% nitrogen dilution. This γ-ray irradiation induces a permanent damage that has increased ideality factor and series resistance for all samples. It was accompanied by a decrease in Schottky barrier height with nitrogen content up to 0.4%N and remained constant thereafter. Radiation was also found to degrade the reverse leakage current.At high frequency (1 MHz), capacitance and conductance decreased after radiation due to a decrease in net doping concentration. Interface state density and series resistance were determined from C-V-f and G/ω-V-f characteristics using Hill-Coleman methods. Interface states density exponentially decreased with increasing frequency confirming the behavior of interface traps response to ac signal.Series resistance increases after irradiation is attributed to carrier's removal effect and mobility degradation. It has two peaks in the accumulation and inversion region for some diodes (0.4%N, 0.8%N). γ-ray irradiation produced traps levels and recombination centers that reduce relaxation time. An increase in %N content can impede irradiation damage with even some compensation when the percent of diluted nitrogen is high (1.2%N).

A radiation dose study based on analysis of primary color chrominance

Purpose: The purpose of this study was to assess the possibility of measuring radiation dose based on primary color chrominance in chemical solutions. Methods: We used an aqueous solution with different concentrations of Alphaurine A and Tracid Brilliant Red B. This was irradiated by 1.5–13.5 kGy 60Co γ radiation. Data were collected by an instrument that can detect information on the three primary colors. Data were analyzed and manipulated for each experiment. Results and conclusions: The result shows that three primary colors chrominance in the aqueous solutions change with different doses of 60Co γ-rays and different concentrations of Alphaurine A and Tracid Brilliant Red B. For Alphaurine A, the red chrominance is gradually reduced as a function of radiation dose. The blue chrominance gradually increases concurrently. The red and green chrominance changes obviously and inversely, but the green chrominance changes little. In Tracid Brilliant Red B solution, the red chrominance gradually decreases as the radiation dose increases. The green chrominance gradually increases concurrently. The red and green chrominance changes are obvious and inverted. The blue chrominance changes little. Our experiments demonstrate that radiation dose can be studied based on three primary colors chrominance. This may be a new tool to measure the radiation dose.

On the interface states and series resistance profiles of (Ni/Au)–Al0.22Ga0.78N/AlN/GaN heterostructures before and after 60Co (γ-ray) irradiation

The values of interface states (N SS) and series resistance (R S) of (Ni/Au)–Al0.22Ga0.78N/AlN/GaN heterostructures were obtained from admittance and current–voltage measurements before and after 250 kGy 60Co irradiation. The analyses of these data indicate that the values of capacitance and conductance decrease, as the R S increases with increasing dose rate due to the generation of N SS. The increase in R S with increasing dose rate was attributed to two main models. According to the first model, it has been attributed to a direct decrease in the donor concentration in semiconductor material as a result of the elimination of shallow donor states. According to the second model, it is a result of irradiation because of the formation of deep acceptor centers in the semiconductor bulk, and electrons from the shallow donor centers are captured by these acceptors.

Deinococcus radiodurans PprI Switches on DNA Damage Response and Cellular Survival Networks after Radiation Damage

Preliminary findings indicate that PprI is a regulatory protein that stimulates transcription and translation of recA and other DNA repair genes in response to DNA damage in the extremely radioresistant bacterium Deinococcus radiodurans. To define the repertoire of proteins regulated by PprI and investigate the in vivo regulatory mechanism of PprI in response to gamma radiation, we performed comparative proteomics analyses on wild type (R1) and a pprI knock-out strain (YR1) under conditions of ionizing irradiation. Results of two-dimensional electrophoresis and MALDI-TOF MS or MALDI-TOF/TOF MS indicated that in response to low dose gamma ray exposure 31 proteins were significantly up-regulated in the presence of PprI. Among them, RecA and PprA are well known for their roles in DNA replication and repair. Others are involved in six different pathways, including stress response, energy metabolism, transcriptional regulation, signal transduction, protein turnover, and chaperoning. The last group consists of many proteins with uncharacterized functions. Expression of an additional four proteins, most of which act in metabolic pathways, was down-regulated in irradiated R1. Additionally phosphorylation of two proteins was under the control of PprI in response to irradiation. The different functional roles of representative PprI-regulated genes in extreme radioresistance were validated by gene knock-out analysis. These results suggest a role, either directly or indirectly, for PprI as a general switch to efficiently enhance the DNA repair capability and extreme radioresistance of D. radiodurans via regulation of a series of pathways.

Cell growth on tissue-engineering scaffolds prepared by gamma irradiation grafting of N-vinyl-2-pyrrolidone onto polyvinyl alcohol

In the field of tissue engineering, promoting cell attachment and proliferation in polymer matrices is an attractive challenge for treating patients suffering from the loss or dysfunction of tissues or organs. In this study we have investigated the effect of grafting N-vinyl-2-pyrrolidone (NVP) by gamma irradiation onto polyvinyl alcohol (PVA), a highly hydrophilic and non-toxic material. PVA scaffolds were prepared by freeze–thaw and progen (glycerol) methods. In the first method, samples were freeze–thawed for three consecutive cycles at −25°C (90 min) and room temperature (60 min); in the latter, 0–40% glycerol was used as progen. Gamma irradiation of the scaffolds in the presence of NVP was performed at different concentrations (2, 3, 4 and 6%) with 5, 10 and 15 kGy 60Co. The highest percentage of grafting was obtained at 4% NVP solution and 15 kGy. Cell attachment was optimal for the scaffolds prepared using freeze–thaw and glycerol methods with 3.8% and 2.7% polyvinyl pyrrolidone (PVP), respectively.

Radiation induced surface activation on Leidenfrost and quenching phenomena

Improving the limit of boiling heat transfer or critical heat flux requires that the cooling liquid can contact the heating surface, or a high wettability, highly hydrophilic heating surface, even if a vapor bubble layer is generated on the surface. In our previous study, contact angle, an indicator of macroscopic wettability, of a water droplet on metal oxide at room temperature was measured by image processing of the images obtained by a CCD video camera. The results showed that the surface wettability on metal oxide pieces of titanium, zircaloy No. 4, SUS-304, and copper was improved significantly by the radiation induced surface activation (RISA) phenomenon. To delineate the effect of RISA on heat transferring phenomena, the Leidenfrost condition and quenching of metal oxides irradiated by γ-rays were investigated in this study. In the Leidenfrost experiment, when the temperature of the heating surface reached the wetting limit temperature, water–solid contact vanished because a stable vapor film existed between the droplet and the metal surface; i.e., a Leidenfrost condition obtained. The wetting limit temperature increased with integrated irradiation dose. After irradiation, the wet length and the duration of contact increased, and the contact angle decreased. In the quenching test, high surface wettability, or a highly hydrophilic condition, of a simulated fuel rod made of SUS was achieved, and the quenching velocities were increased up to 20–30% after 300 kGy 60Co γ-ray irradiation.

Differential biodistribution of native and 2 kGy 60Co irradiated crotoxin in tissues of CBA/J mice

Crotalus durissus envenomation is treated using antivenins produced in horses. During production, animals have problems, sometimes followed by death, due to the high toxicity of the main toxin, crotoxin. Several methods tested to detoxify this toxin often resulted in decreased immunogenicity. Gamma irradiation has proved to be a successful method for crotoxin detoxification without loss of immunogenicity. We have studied the biodistribution of 2 kGy 60Co irradiated crotoxin (iCTX) in mouse tissues. We used both 125I-labeled iCTX or its detection by a specific immunohistochemistry assay (IHA). Both approaches showed similar early excretion of toxins by the kidneys. Higher iCTX uptake was seen in spleen and liver, which are rich in immune responder cells. In contrast to previous reports concerning native crotoxin (nCTX), we failed to detect iCTX in the neuromuscular junction, but both toxins were found on the kidney tubular cell surface, with rapid excretion that was more intense for iCTX. Kupffer cells and splenocyte macrophages presented IHA staining, as shown by the increased uptake of 125I toxin by these organs. No staining was observed in the brain, lung or heart, which also showed very low 125I counts. Allied to reduced toxicity, irradiation induced early endocytosis of crotoxin by phagocytic cells, improving antigen processing. Copyright © 1998 John Wiley & Sons, Ltd.

Irradiation of Crotalus durissus terrificus crotoxin with 60Co gamma-rays induces its uptake by macrophages through scavenger receptors

Purpose: To investigate the action of 2 kGy 60Co gamma-rays on crotoxin and its favoured uptake through scavenger receptor (ScvR) mouse peritoneal macrophages. Materials and methods: Native or irradiated crotoxin (iCTX) (50 mu g/ml) dosed with 2 kGy 60Co gamma-rays (dose-rate 540 Gy/h) were offered to mouse peritoneal macrophages; their uptake was evaluated by immunohistochemistry and quantitative in situ ELISA. Receptors recognizing irradiated crotoxin were evaluated with specific ScvR blockers (Probucol and dextran sulphate) or with non-specific blocking using foetal calf serum (FCS). Results: Immunohistochemical assays revealed more deeply staining intracytoplasmic vacuoles in macrophages incubated with iCTX. Using in situ ELISA with ScvR specific blockers, it was shown that the increased uptake of iCTX was blocked by Probucol or dextran sulphate, but not by FCS. On the other hand, the uptake of native crotoxin was decreased by FCS, but not affected by ScvR blockers. The morphology and viability of macrophages were preserved during the experiments. Conclusions: It is concluded that 60Co gamma-rays probably induced oxidative changes in crotoxin, driving this toxin towards ScvR mouse peritoneal macrophages. This suggests a different in vivo route of iCTX away from toxic neural sites by a preferential and rapid internalization and processing by macrophages, leading to the induction of a better immune response.