kGy Gamma Irradiation Research Articles

Boron containing polyvinyl alcohol/ polyethylene oxide/polyvinyl pyrrolidone composites: Preparation, characterization, gamma radiation shielding and gamma radiation effect on it's thermal properties

The production of PVA/PEO/PVP-B4C and PVA/PEO/PVP-BN nanocomposites is presented in this study by adding certain proportions of boron nitride (BN) and boron carbide (B4C) to the polyvinyl alcohol(PVA)/polyethylene Oxide (PEO)/polyvinyl pyrrolidone (PVP) blend. The percentages of BN and B4C nano powder in the PVA/PEO/PVP blend have been determined as 5%, 10% and 20%. Thermal characterizations were carried out with different techniques such as Differential scanning calorimetry (DSC), Differential Thermal Analysis (DTA), Thermogravimetry (TG). Surface, crystal structure and atomic percentage distribution analyzes of the obtained composites were performed by X-ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction Analysis (XRD), Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM-EDX), and elemental analysis. 10 kGy gamma irradiation was performed on PVA/PEO/PVP-B4C and PVA/PEO/PVP-BN composites. The thermal behavior of the composites at this dose level was investigated. In addition, the radiation shielding properties of composite films obtained at 10 cm distances using Am-241 beam source were examined.

Radiation cross-linked ultra-absorbent hydrogel to rationalize irrigation water and fertilizer for maize planting in drought conditions

The study addresses the potential negative impacts of climate change on water resources, specifically irrigation water for crops. The radiation technique produces the biomaterial hydrogel as a soil conditioner by polymerizing hydroxy ethyl cellulose/acrylamide (HEC/AAm) at various irradiation doses and copolymer concentrations. A maximum swelling of 23.4 g/g is attained by (HEC/PAAm) hydrogel at 1/7.5 ratio, prepared by 10 kGy gamma irradiation. The study introduces a new class of ultra-absorbent hydrogel (UAH) to address the low swelling limitation for soil conditioner applications. The alkaline hydrolysis treatments with NaOH, LiOH, and KOH enhance the water absorbency of (HEC/PAAm) hydrogel, with the highest capacity of 1220 g/g achieved by the KOH treatment, surpassing NaOH (622 g/g) and LiOH (540 g/g). The cumulative release of fertilizers from the UAH sample shows a slow and controlled release behavior. Urea takes 22 days to reach 100 % release. The UAH demonstrates water retention for 28 days, improving the growth of Zea mays L. at drought stress levels of 0 %, 25 %, 50 %, and 100 %, revealing an increase in shoot length by 16 %, 19 %, 24 %, and 20 %, respectively. Also, UAH increased the contents of chlorophyll a, b, a + b, and carotenoid on maize plant leaves compared to the control sample.

Ultra‐Selective and Efficient Static/Dynamic Palladium Capture from Highly Acidic Solution with Robust Macrocycle‐Based Polymers

AbstractThe capture of palladium from spent nuclear fuel is crucial for the sustainable development of nuclear energy and resource recovery. One of the most challenging issues in this direction is the survival of adsorbents under extreme reprocessing conditions such as strongly acidic media and high radiation fields while still maintaining high extraction ability and selectivity. Herein, an approach to addressing this issue is reported by incorporating macrocycle into nitrogen‐rich covalent organic polymers (COPs). Dramatically outperforming current adsorbing materials, pillar[5]arene‐based COPs with pyridyl and triazolyl functionalities display record adsorption capacity for Pd(II) at 3 M HNO3 (403 mg g−1), extraordinary stability under 500 kGy gamma irradiation, and ultra‐high selectivity toward Pd(II) over both 17 coexisting cations and six anions. In particular, the material P5COP‐m‐BPT with the best performance also shows remarkable dynamic adsorption efficiency for Pd(II). This study not only provides a strategy to enhance all‐sided adsorption performance in palladium separation with nitrogen‐rich COPs materials but also demonstrates the superiority of customizing advanced materials with macrocycles.

Improvement of mechanical properties of jute-nano cellulose-reinforced unsaturated polyester resin-based composite: Effects of gamma radiation

In this research work, waste jute bags were utilized to synthesize nano cellulose which was further applied as reinforcing materials for the fabrication of unsaturated resin-based composites. Different percentages of nano cellulose were used to fabricate nano cellulose-reinforced unsaturated polyester resin-based composites and the composites were fabricated using the hand-lay-up technique. A 0.2% (w/w) incorporation of nano-cellulose in the matrix enhanced the mechanical properties of the fabricated composites. A variation was also maintained for high-energy gamma radiation doses such as 2.5, 5.0, and 7.5 KGy which were applied throughout the fabricated composite to enhance the properties. Higher mechanical properties were found for the incorporation of 0.2% nano cellulose and 5.0 KGy gamma radiation doses application such as ultimate tensile strength (210% increment), bending strength (200% increment), elongation at break (12.5% reduction), impact strength (56% increment), Fourier Transform Infrared, scanning electron microscope, as well as water uptake test.

Transcriptome analysis provides insight into gamma irradiation delaying quality deterioration of postharvest Lentinula edodes during cold storage

To better determine how gamma irradiation (GI) improves abiotic stress resistance, a transcriptome analysis of postharvest L. edodes in response to 1.0 kGy GI was conducted, and further the underlying mechanism of GI in delaying quality deterioration over 20 d of cold storage was explored. The results suggested that GI was involved in multiple metabolic processes in irradiated postharvest L. edodes. In comparison with the control group, the GI group contained 430 differentially expressed genes, including 151 upregulated genes and 279 downregulated genes, which unveiled characteristic expression profiles and pathways. The genes involved in the pentose phosphate pathway were mainly upregulated and the expression level of the gene encoding deoxy-D-gluconate 3-dehydrogenase was 9.151-fold higher. In contrast, the genes related to other energy metabolism pathways were downregulated. Concurrently, GI inhibited the expression of genes associated with delta 9-fatty acid desaturase, ribosomes, and HSP20; thus, GI helped postpone the degradation of lipid components, suppress transcriptional metabolism and regulate the stress response. Additionally, the metabolic behavior of DNA repair induced by GI intensified by noticeable upregulation. These regulatory effects could play a potential and nonnegligible role in delaying the deterioration of L. edodes quality. The results provide new information on the regulatory mechanism of postharvest L. edodes when subjected to 1.0 kGy GI during cold storage.

Radiation Sensitive Long-Period Fiber Grating Based on Tb-Doped Silica Fiber

We demonstrate a radiation sensitive long-period fiber grating (LPG) based on terbium (Tb)-doped silica fiber, fabricated by dual-sided CO2 laser exposure. At a total dose of 6.0 ± 0.2 kGy of gamma radiation, the maximum radiation-induced resonance wavelength shift (RIRWS) of LPG in Tb-doped silica fiber is up to 3.98 nm, which is much higher than that of 1.14 nm in standard single-mode fiber. To characterize the degree of modification of fibers by radiation, we calculate the radiation-induced refractive index change (RIRIC), which is as high as <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.05\times 10^{-5}$ </tex-math></inline-formula> for Tb-doped silica fiber, approximately 276.3% of that of standard single-mode fiber. In addition, the growth of RIRWS with increasing cladding mode order is analyzed, and the theoretical and experimental RIRWS of LPG are compared. This new type of LPG has great promise in the field of high-dose radiation sensing, such as dose monitoring in nuclear reactors, particle collision experiments, and so on.

Physical Chemical Investigation of Gamma-Irradiated Parchment for Preservation of Cultural Heritage

The historical artefacts of parchment are prone to degradation if the storage conditions are improper due to the collagen structure having a limited stability under physical, chemical, and biological agent attacks. The parchment structure is difficult to characterize due to the variety of manufacturing traditions (eastern/western), intrinsic variability of skins (i.e., species, breeding variation, living conditions, effects of pathologies, etc.), biodeterioration, and aging, and the main concern in its analysis is its uniformity. The deterioration of parchment collagen produces a rather stiff or in some circumstances, a relaxed structure. Any intervention or treatment of unique, very precious cultural heritage artefacts must not negatively influence the properties of the component materials. Gamma irradiation is a relatively new technique of bioremediation. Data on the leather properties pre- and post-ionizing radiation bioremediation treatments are few in the literature. Fewer data are available on the historical leather and parchment physical chemical characteristics after ionizing gamma irradiation. This research had two main objectives: (i) the characterization of the parchment structure's uniformity across the analyzed areas and its mechanical properties, i.e., tensile stress by mechanical tests and ATR-FTIR spectroscopy; and (ii) to establish parchment tolerance when exposed to ionizing gamma radiation as a pre-requisite for cultural heritage preservation irradiation treatment. It was found that the mechanical tests and ATR-FTIR spectroscopy may identify changes in the parchment's irradiated structure and that the preservation of cultural heritage parchment artefacts may be performed at maximum 15 kGy gamma irradiation dose.

Impact of gamma-ray irradiation on photo emission from InGaN/GaN LED

The impact of gamma-irradiation on the unpacked InGaN/GaN LED properties has been studied. Before gamma irradiation exposure, three peaks located at 400, 447 and 568 nm were observed from room temperature photoluminence (PL) spectra, which were ascribed to InxGa1−xN (x = 0.11), InGaN/GaN multiple quantum wells and from (VGa–ON)2−/1−, respectively. Their peak positions remain unaffected for cumulative gamma-ray doses up to 100 kGy, but the PL intensities were changed with the gamma irradiation. The emission intensity from InGaN/GaN MQWs was firstly increased by 40 % with 30 kGy, the emission intensity from InxGa1−xN (x = 0.11) was decreased by one-third with a total dose of 30 kGy gamma irradiation and by two-third with 50 kGy. The LED properties showed that the operating voltage was increased with the total doses, the luminous flux and the photoelectric conversion efficiency were decreased with the total doses. The time-resolved photoluminence (TRPL) measurements showed that the lifetime prolonged gradually with the radiation doses.

Irradiation-induced effects on structure and optical properties of PbO-B2O3-Na2O glasses: γ-dosimetry application

The objective of this research is to study the impact of gamma irradiation on various PbO-B2O3-Na2O glasses that have been doped with CdO, BaO, MoO3, and WO3. The prepared glass has been experimentally examined before and after 65 kGy gamma irradiation at a dose rate of 0.799 kGy/h at 30 °C. X-ray diffraction has been used to confirm the amorphous nature of glass samples. Structural and optical properties were studied using Infrared (IR) and UV–vis spectroscopic techniques. IR experiments of all glass samples indicate absorption bands specific to different types of borate structures. The optical characterizations such as the direct and indirect optical energy gap, index of refraction, and Fermi energy were analyzed using UV–vis spectra in the wavelength range of 190–1100 nm. We found that the values of the direct and indirect optical energy gap of these glasses are in the range of 3.57–2.81 eV and 3.27–2.45 eV, respectively. The main resonance paramagnetic centers for all prepared samples have been confirmed by the ESR spectrum.

Gamma irradiation effect on the microbial load and physicochemical properties of honey from Ghana

Abstract. Larbi DA, Klutse CK, Adotey DK. 2022. Gamma irradiation effect on the microbial load and physicochemical properties of honey from Ghana. Cell Biol Dev 6: 94-107. The honey's high sugar concentration and low pH give it antimicrobial properties and make it difficult for microorganisms to grow. This study is to ascertain microorganisms' presence in Ghanaian honey, the sources of microbial contamination, the physico-chemical properties of honey, and the effect of gamma radiation on the microbial load. Furthermore, 90 honey samples were collected from Brong Ahafo, Ashanti, and Greater Accra, Ghana, with 30 from each region. Honey was sampled directly from the beehive with the comb before the farmer harvested, and honey was sampled from retailers who buy directly from the farmer. The effect of gamma radiation on the microbial load was studied using a 60Co source gamma irradiation facility at doses of 20 kGy, 30 kGy, and 40 kGy on the presence of microbes and the physicochemical properties (pH, reducing sugar, apparent sucrose, and ash content) of honey. The pH values obtained for the Honey Comb samples were in the range of 3.6-3.9, and the pH for the Retail samples was in the range of 4.9-5.6. Microorganisms were not detected in about 70% of the honey sampled directly from the honeycomb. The mean microbial count in the remaining 30% was within the range of 30-35%, whereas all the honey sampled from the retailers was contaminated with microbes. The mean microbial counts in the retailer samples were 148 CFU/g, 183 CFU/g, and 271 CFU/g for Ashanti, Brong Ahafo, and Greater Accra Regions, respectively. These values were significantly higher than the required maximum relative to the MERCOSUR (Mercado Comun del SUR) standard (? 100 CFU/g). The low level of microbial detection in the Honey Comb samples (30-35 CFU/g) could be due to their relatively low pH levels (3.6-3.9) compared to the retailer samples with pH within 4.9-5.6. The ash content of all the honey sampled and analyzed was within the required standard, with an average of 0.16% in the honeycomb samples and an average of 0.62% for the retail samples. The apparent sucrose concentration (in percentage) in honey sampled from the retailers was within the range of 22-33%, which is beyond the required maximum as stipulated by the CODEX Alimentarius Commission (? 10%). The study showed that a 20 kGy gamma radiation dose was enough to denature the microbes and preserve the honey's essential qualities. Finally, to ensure good quality honey on the Ghanaian market, it is recommended that honey meant for human consumption should undergo gamma irradiation (cold pasteurization).

Gamma and electron beam irradiation use in the control of a radiation-resistant fungus (Epicoccum nigrum) for preservation of contaminated organic artefacts of traditional heritage

When artefacts of traditional cultural heritage are waterlogged due to floods and other disasters, they can be quickly protected from contamination by harmful fungi using irradiation treatments. In this study, we showed that Epicoccum nigrum has the potential to contaminate traditional heritage artefacts made of Korean paper and silk under waterlogged conditions. E. nigrum showed 60% lower mycelial growth in medium containing freshwater than in medium containing natural seawater. Control of this contamination was attempted using gamma and electron beam irradiation disinfection technology. The mycelial growth of E. nigrum irradiated with a 5 kGy dose of gamma rays was completely controlled at 15 kGy dose. Next, we evaluated the effect of irradiation on contaminated sample artefacts. E. nigrum growing on waterlogged sample artefacts of cultural heritage was completely controlled at 15 kGy in freshwater-immersed artefacts of Korean paper and silk and seawater-immersed silk. However, in Korean paper immersed in seawater, 15 kGy gamma-irradiation treatment did not control growth of the fungus. Our results suggest that at least 15 kGy of gamma radiation should be used to for treatment, to preserve waterlogged traditional cultural heritage artefacts of Korea, after flooding or other disasters involving water.

Bacillus spizizenii DN and microbial consortia biostimulation followed by gamma irradiation for efficient textile wastewater treatment

Textile wastewater still poses a huge environmental problem due to its high water consumption and high effluent release that is full of toxic chemicals. In the present study, different approaches were studied to layout an operating procedure for textile wastewater treatment in order to obtain treated wastewater that is safe for non-potable uses. Our approach depended on (1) co-substrate to biostimulate indigenous microbial textile wastewater community by adding Tryptone Soy Broth (TSB) and TSB supplemented with 1% glucose, (2) co-culture (bioaugmentation) with Bacillus spizizenii DN cells (previously isolated, identified and characterized as efficient decolorizing bacteria), and (3) co-metabolites using Bacillus spizizenii DN metabolites. The obtained results show that using Bacillus spizizenii DN cells resulted in 97.78% decolorization while adding Bacillus spizizenii DN metabolites resulted in 82.92% decolorization, both after 48 h incubation under microaerophilic conditions. The phyla identified for all treatments were Bacteroidota, Firmicutes, and Proteobacteria. The dynamic changes in the bacteria showed that both Clostridium and Acinetobacter disappeared for co-substrate, co-culture, and co-metabolite cultures. While Alkalibacterium and Stenotrophomonas appeared after adding Bacillus spizizenii DN cells, Flavobacterium increased for co-substrate and co-metabolic cultures while iron reducing bacteria appeared only for co-metabolic cultures. The use of 25 kGy gamma irradiation as a sterilization dose post bioremediation ensured safe use of treated wastewater. This was confirmed by cytotoxicity assay; the obtained IC50 tested on BJ fibroblasts obtained from skin showed that gamma irradiated treated wastewater are about 80.1% less toxic than non-irradiated treated wastewater. We conclude that (1) we can use combined bioaugmentation and biostimulation as initial steps for in situ bioremediation in collection tanks and that (2) the proposed protocol for bioremediation of industrial wastewater should be tailored based on the required application and level of safety needed for re-use.Graphical abstract

Effect of ajwain (Trachyspermum ammi) extract and gamma irradiation on the shelf-life extension of rohu (Labeo rohita) and seer (Scomberomorus guttatus) fish steaks during chilled storage

Fishes are highly perishable, mainly stored and transported under frozen condition; however, they are mainly preferred as fresh or in chilled form for consumption because frozen storage compromises the texture quality and other sensory attributes. Shelf-life enhancement of rohu and seer fish steaks was studied using combination of ajwain extract (various concentrations) and γ-irradiation (various doses) under chilled storage (4 °C). These were analyzed periodically by microbiological, sensory, color and biochemical analyses during storage. Gas chromatography - mass spectrometry (GC-MS) analysis showed thymol as major component. High performance liquid chromatography (HPLC) analysis showed the presence of nine phenolic compounds including thymol in ajwain extract. The best result was achieved when samples were dipped in 10 % ajwain extract with 2 kGy gamma irradiation dose. An extended shelf-life of 5 and 10 days in case of rohu and seer fish steaks were attained respectively using this combination. These results were confirmed by microbial, biochemical and sensory analyses. The present study thus promises potential application of the above protocol in fishery industry for good quality of fish and commercial benefits.

Comprehensive Temporal Protein Dynamics during Postirradiation Recovery in Deinococcus radiodurans.

Deinococcus radiodurans (D. radiodurans) is an extremophile that can tolerate ionizing radiation, ultraviolet radiation, and oxidation. How D. radiodurans responds to and survives high levels of ionizing radiation is still not clear. In this study, we performed label-free proteomics to explore the proteome dynamics during postirradiation recovery (PIR). Surprisingly, proteins involved in translation were repressed during the initial hours of PIR. D. radiodurans also showed enhanced DNA repair and antioxidative response after 6 kGy of gamma irradiation. Moreover, proteins involved in sulfur metabolism and phenylalanine metabolism were enriched at 1 h and 12 h, respectively, indicating different energy and material needs during PIR. Furthermore, based on these findings, we proposed a novel model to elucidate the possible molecular mechanisms of robust radioresistance in D. radiodurans, which may serve as a reference for future radiation repair.

Effects of Radiation on Cross-Linking Reaction, Microstructure, and Microbiological Properties of Whey Protein-Based Tissue Adhesive Development.

Whey proteins are mainly a group of small globular proteins. Their structures can be modified by physical, chemical, and other means to improve their functionality. The objectives of this study are to investigate the effect of radiation on protein–protein interaction, microstructure, and microbiological properties of whey protein–water solutions for a novel biomaterial tissue adhesive. Whey protein isolate solutions (10%, 27%, 30%, 33%, and 36% protein) were treated by different intensities (10–35 kGy) of gamma radiation. The protein solutions were analyzed for viscosity, turbidity, soluble nitrogen, total plate count, and yeast and mold counts. The interactions between whey proteins were also analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and scanning electron microscopy. The viscosity of protein solution (27%, w/w) was increased by the treatment of gamma radiation and by the storage at 23 °C. The 35 kGy intensity irradiated soluble nitrogen (10%, w/w) was reduced to about half of the sample treated by 0 kGy gamma radiation. The effects of gamma radiation and storage time can significantly increase the viscosity of whey protein solutions (p < 0.05). Radiation treatment had significant impact on soluble nitrogen of whey protein solutions (p < 0.05). SDS-PAGE results show that the extent of oligomerization of whey protein isolate solutions are increased by the enhancement in gamma radiation intensity. Photographs of SEM also indicate that protein–protein interactions are induced by gamma radiation in the model system. Consistent with above results, the bonding strength increases by the addition of extent of gamma radiation and the concentration of glutaraldehyde. Our results revealed that the combination of gamma-irradiated whey protein isolate solutions and glutaraldehyde can be used as a novel biomaterial tissue adhesive.

Effects of Chemical Sterilization and Gamma Irradiation on the Biochemical and Biomechanical Properties of Human Tendon Allografts In Vitro Study.

ObjectivePre‐implantation sterilization procedures for tendons are important measures to reduce the risk of disease transmission, however these procedures may compromise tendon microarchitecture and biomechanical properties to varying degrees. We explore the effects of different sterilization procedures on the micro‐histology, biomechanical strength and biochemical properties of human tendon allografts in vitro study.MethodsThe tendon allografts were harvested from cadaveric donors after the donors were serologically screened by antibody or nucleic acid testing of infectious agents. All samples were divided into five groups, which were fresh‐frozen group (control group), 15 kGy gamma irradiation group, 25 kGy gamma irradiation group, 70% ethanol group, and peracetic acid‐ethanol group. Each group included 10 tendons for testing. Histological staining and transmission electron microscopy were applied to observe the internal structure and arrangement of tendon collagen fibers, while the machine learning classifier was trained to distinguish the darker cross‐sections of collagen fibers and brighter backgrounds of the electron micrograph to detect the distribution of diameters of tendon collagen fibers. The viscoelasticity, mechanical properties and material properties of tendon allografts were examined to detect the influence of different intervention factors on the biomechanical properties of tendons.ResultsHistological staining and transmission electron microscopy showed that the structure of fresh‐frozen tendons was similar to the structures of other experimental groups, and no obvious fiber disorder or delamination was observed. In the uniaxial cyclic test, the cyclic creep of 25 kGy irradiation group (1.5%) and peracetic acid‐ethanol group (1.5%) were significantly lower than that of the control group (3.6%, F = 1.52, P = 0.039) while in the load‐to‐failure test, the maximum elongation and maximum strain of the peracetic acid‐ethanol group were significantly higher than those of the control group (F = 4.60, P = 0.010), and there was no significant difference in other biomechanical indicators. According to the experimental results of denatured collagen, it could be seen that no matter which disinfection procedure was used, the denaturation of the tendon sample would be promoted (F = 1.97, P = 0.186), and high‐dose irradiation seemed to cause more damage to collagen fibers than the other two disinfection procedures (296.2 vs 171.1 vs 212.9 μg/g).ConclusionBiomechanical experiments and collagen denaturation tests showed that 15 kGy gamma irradiation and 70% ethanol can preserve the biomechanical strength and biochemical properties of tendons to the greatest extent, and these two sterilization methods are worthy of further promotion.

Radiochemical transformation of mucilage extracted from Opuntia ficus-índica using gamma radiation

Gamma irradiation is a powerful tool for modifying the physicochemical properties of polymers. Gamma radiation has been widely used to carry out reactions such as crosslinking, depolymerization, and graft copolymerization, with a wide variety of synthetic and natural polymers. Although gamma irradiation proved to be useful to modify the chemical properties of several polysaccharides, this method has not been applied to mucilage. However, irradiation could bring beneficial changes to mucilage for its use in different applications. Thus, the aim of this work was to study the radiochemical transformation of mucilage extracted from Opuntia ficus-indica using gamma radiation. Results obtained from FTIR-ATR, pH and electrical conductivity in aqueous solution showed that decarboxylation of mucilage occurs applying a radiation dose from 2 to 12 kGy. Further, it was observed that thermal stability of mucilage was enhanced with a radiation dose of 2 and 6 kGy. The decarboxylation degree was proportional to the radiation dose in the interval of 0–12 kGy. Further, mucilage was irradiated in the presence of acrylic acid forming mucilage/PAA hydrogels with high swelling capacity. The best swelling capacity (734%) was observed for the hydrogel obtained applying 2 kGy of gamma radiation. Hydrogels prepared with higher radiation doses (4–20 kGy) showed lower swelling capacity and higher thermal stability, which suggest a higher crosslinking degree. The experiments performed in this work were performed using 100 mg of mucilage but gamma irradiation allows a high scalability of the process. The usefulness of gamma irradiation relays on the development of a method for preparing hydrogels by an easy and scalable method.

Synergetic impacts of mesoporous α-Fe2O3 nanoparticles on the performance of alkali-activated slag against fire, gamma rays, and some microorganisms

This study describes the fabrication of green composite pastes with multifunctional properties that can be utilized in special applications. Low-cost mesoporous hematite nanoparticles (HNPs) were prepared using a sol-gel technique. Different doses of HNPs (0.25, 0.5, and 1%) were added to alkali-activated slag (AAS) using an aqueous solution of NaOH (5 wt % of slag) as an activator. All composite pastes, AAS and AAS-HNPs, were kept under high humidity at normal temperature for 90 days. After 28 days of curing, a group of specimens was fired at elevated temperatures in a range of 200–900 °C, and another group was exposed to 1000- 3000 KGy gamma radiation. The formed phases and morphological features of some selected composites were characterized using X-ray diffraction (XRD), thermal analyses (TGA/DTG), Fourier transformation infrared (FTIR), and scanning electron microscope with energy dispersive X-ray (SEM/EDX). The outcomes of the compressive strength test emphasized that AAS-0.25 HNPs composite paste has a superior thermal resistivity at all firing temperatures and the best impedance to radiation till 3000 KGy. Agar diffusion test (ASTM D4300-1) revealed that AAS containing 1% HNPs composite possessed an excellent antimicrobial activity with various microorganisms; two bacterial strains (Escherichia Coli ATCC 8739 and Staphylococcus aureus ATCC 6538) and two fungal strains (Aspergillus flavus and Mucor circinelloide).

Exploring thermal, optical, structural and luminescent properties of gamma irradiated Dy3+doped tellurite glasses: Photon shielding properties

The TeO2–B2O3–ZnO-Dy2O3 (TBZDyx) glasses were irradiated with 50 kGy gamma radiation using a60Co radioisotope source. The effect of gamma irradiation on the physical, optical and spectroscopic properties of TBZDyx glasses was studied. The glasses remained amorphous after gamma irradiation. The optical studies revealed that the band gap values decreased after irradiation. The spectroscopic properties such as stimulated emission cross-section, bandwidth, lifetime etc. got marginally modified. The characteristic photon shielding properties of the Dy3+- doped TeO2–B2O3–ZnO (TBZDyx) glasses were studied using Phy-X/PSD software. The photon shielding properties of the glasses were accessed in terms of mass attenuation coefficient, half value layer and effective atomic number. The mass attenuation coefficient decreased as photon energy increased with exception at 0.004 MeV. The maximum value of MAC was found to be at 0.0015 MeV for TBZDy2.5 glass. The half value layer and mean free path decreased with increase in Dy3+-concentration. Whereas, the effective atomic number increased with increasing Dy3+- concentration. The results suggested that the photon shielding properties of the glasses improved with the addition of Dy3+ and can be considered as candidates for photon shielding materials.

Ionizing radiation response of bismuth titanate-based metal-ferroelectric-semiconductor (MFS) type capacitor

In this study, the ionizing radiation (gamma-irradiation) response of the metal-ferroelectric-semiconductor (MFS) type capacitors whose interfacial layer is bismuth titanate (Bi4Ti3O12), which is from the Aurivillius family, was investigated. The capacitance-voltage (CV) and conductance-voltage (G/ω-V) characteristics and the device parameters derived from these characteristics provide essential information about the radiation response. Therefore, MFS-type capacitors in which their Schottky/rectifier contacts Au and interfacial layer Bi4Ti3O12 (BTO) were prepared and exposed to various doses of gamma-rays. The voltage-dependent C and G/ω data were obtained before irradiation and after some irradiation doses using the Hewlett Packard Impedance Analyzer. Experimental results showed that the CV curves exhibited multilayer capacitor behavior before and after radiation rather than conventional Schottky structures due to the very thin Silicon dioxide (SiO2) interlayer at the BTO/Si interface, which was assumed to form during the annealing of BTO films in air ambient. On the other hand, the C-G/ω-V curves exhibited asymmetric and hysteretic behavior because of the different electrical properties at the bottom and top interfaces and the natural ferroelectric behavior of the BTO. On the other hand, considering the radiation effects, the C-G/ω-V characteristics and other device parameters did not show any significant changes at the 5 kGy irradiation dose, but significant differences were observed in all parameters at the 22 kGy dose. Therefore, it can be concluded that these MFS-type structures with the BTO interlayer can be used as a capacitor or radiation sensor at doses around 5 kGy and below 22 kGy. However, it is not recommended to use them as capacitors at doses close to 22 kGy due to the large capacitive change (approximately tenfold decrease) at this dose. Besides, the tendency of the device to deteriorate at 22 kGy doses indicates that it is not suitable for use as a capacitor or radiation sensor above 22 kGy gamma-irradiation doses.