Gamma-irradiated Samples Research Articles

INFLUENCE OF IONIZING RADIATION ON THE DIFFUSE REFLECTION SPECTRA OF STEATITE CERAMICS SNC

In this article, the radiation defects induced in steatite ceramics type- SNC- irradiated with high doses of gamma-rays of 60Co source and mixed reactor nо-gamma-irradiation were studied using optical spectroscopy, i.e. diffuse reflection method. An analysis of the results of the diffuse reflection spectra showed that some structural defects are formed under gamma-irradiation. These are oxygen vacancies, unbound oxygen atoms, and E1 -centers (a three-coordinated silicon atom that has captured an electron) in the ultraviolet region of the spectrum. In the visible region of the spectrum, the types of hole centers are different. After decomposing the spectrum of the visible region into Gaussians, it was found that in this region of the spectrum, with no –gamma- irradiation of the reactor, in comparison with gamma-irradiation, various types of hole centers - (O-Me, Me-metal) are additionally formed. The efficiency of creating these structural defects in nо-gamma-reactor irradiated samples was higher compared to gamma irradiated samples.

Ionizing radiation based advanced oxidation process for reactive orange 122 dye degradation and kinetics studies

Abstract In the current study, the degradation of reactive orange 122 (RO 122) dye was carried out under UV and gamma irradiation in presence of H2O2. The effect of variables such as UV exposure time, gamma-ray absorbed dose, initial concentration of dye and oxidant dose were investigated. The removal of 64.10, 58.84 and 55.46 (%) was observed for 50, 100 and 150 (mg/L) dye concentrations, respectively using UV radiation time of 150 (min). The degradation was enhanced to 80.39, 69.95 and 67.01 (%) when UV radiation was employed in the presence of H2O2 (0.5 mL/L) for above concentrations respectively. The degradation was further improved to 97, 92.54 and 81.32 (%) using 5 kGy absorbed dose along with H2O2 (0.5 mL/L). The reduction in chemical oxygen demand (COD) was 77, 64 and 57 (%) using UV/H2O2 (0.5 mL/L), while 63, 56 and 53 (%) in case of gamma/H2O2 for aforementioned concentrations. The removal efficiency (G-value), dose constants (k), dose indispensable for 50, 90 and 99 (%) degradation (D 0.5, D 0.90, and D 0.99) after the treatment with gamma radiation were determined. The G-value was noted as 0.46–0.0711 for 50–150 mg/L dye concentration for gamma irradiated samples which improved to 0.57–0.1204 for above mentioned concentrations in presence of H2O2. The FTIR analysis showed that all the peaks were disappeared using gamma/H2O2 at 5 kGy absorbed dose except a minor peak of −CO stretching. The degradation mechanism of dye followed pseudo-first-order kinetics. A significant decrease in peak area was observed by the HPLC analysis after treating the dye samples with gamma/H2O2 (0.5 mL/L) at absorbed dose of 5 kGy which has proven the process efficiency for dye degradation.

Evaluating changes in growth and pigmentation of Cladosporium cladosporioides and Paecilomyces variotii in response to gamma and ultraviolet irradiation

Melanin-containing fungi (black molds) have the capacity to thrive under extreme environmental conditions such as the elevated radiation levels inside the former Chernobyl reactors. These fungi have been hypothesized to grow toward and use gamma radiation as an energy source, but the literature does not clearly address which energies of the electromagnetic spectrum, if any, positively affect fungal growth. The goal of this work was to characterize the response of non-melanized and melanized fungi to two distinct electromagnetic wavelengths, i.e., ultraviolet (UV) and gamma ray, keeping absorption and other potentially confounding variables constant. Exposure to UV or gamma radiation induced significant changes in fungi pigmentation, but not growth rate of Cladosporium cladosporioides and Paecilomyces variotii. Specifically, increased pigmentation of both fungi was observed in samples exposed to UV, while decreased pigmentation was observed for gamma-irradiated samples. These results provide new insights into the role of electromagnetic energies on growth of fungi and provide an impetus to examine additional energies and types of radiation to develop a fundamental understanding of this phenomenon.

Effect of Eu doping on the thermoluminescence of UV and gamma irradiated Mg2 B2 O5 nanophosphors.

This article presents the effect of europium (Eu) doping on the thermoluminescence (TL) of ultraviolet (UV-254 nm) and gamma irradiated triclinic Mg2 B2 O5 nanophosphors. The diffuse reflectance predicts slight decrease in band gap from 5.18 to 4.99 eV with increasing Eu (1%, 3%, and 5%) content in Mg2 B2 O5 . The TL glow curves of UV irradiated samples comprised of a main peak around 500 K with weak intensity peak/shoulders in low temperature region. Interestingly Eu (3%) doped Mg2 B2 O5 shows maximum TL intensity with suppression of low temperature shoulder peaks and almost linear UV dose dependent TL response. However, in the case of gamma irradiated Eu (1% and 3% doped) samples, TL glow curve comprises of a main peak around 425-445 K and closely lying peak around 500-515 K with relatively lesser intensity. In case of Eu (5%) doped samples, TL peak around 508 K starts dominating over peak around 425 K. TL of both UV and gamma irradiated samples showed the presence of various deep and shallow defect states within the bandgap of materials having different kinetic parameters, which were determined using TLanal software based on Kiti's general order equation. The present study shows that Eu doped Mg2 B2 O5 nanophosphors can be tuned for UV and gamma dosimetry.

One-year ageing FTIR monitoring of PE/EVOH/PE film after gamma or electron beam irradiation

The effects of gamma and electron beam irradiation on PE/EVOH/PE film used in biopharmaceutical and biotechnological applications were screened using Fourier Transform Infrared (FTIR) spectroscopy combined with chemometric treatment. The modifications induced by different irradiation doses (25 and 50 kGy) and different post irradiation ageing periods (1, 6 and 24 months) were studied. Results show that shortly after irradiation gamma irradiated and non-sterilized samples exhibit a different behavior than electron beam irradiated samples, whereas 6 months after irradiation gamma irradiated samples are similar to electron beam irradiated samples from a polymer arrangement point of view.

Gamma Irradiation Effects on n-ZnSe/n-Si Isotype Heterojunctions

To get an insight into the isotype heterojunction (IHJ) properties, the influence of gamma irradiation (GI) on the structural and electrical properties of n-ZnSe/n-Si has been presented. The ZnSe thin films were deposited onto the n-Si substrate by thermal evaporation technique. The X-ray diffraction (XRD) studies revealed the nanocrystalline nature of ZnSe thin films with prominent (111) orientation. The gamma irradiated samples displayed no crystallographic phase transformation up to 10 kGy irradiation doses. But noticeable and inconsistent modifications in the different lattice parameters were observed due to irradiation-induced effects. From the analysis of I-V characteristics, it has been found a similar trend in the variation of lattice mismatch, Schottky barrier height and interface trap parameter at different irradiation doses. Thus demonstrating the poor rectification properties of n-ZnSe/n-Si IHJs due to intrinsic and gamma-induced defects, and their role in the space charge limited conduction (SCLC) mechanism that significantly dominating over the thermionic emission (TE) mechanism across the barrier.

Effect of Gamma Irradiation on the Mechanical and Thermal Properties of Biodegradable Packaging Materials

The gamma irradiation was on to Poly(butylene sebacate-co-terephthalate) (PBSeT), Poly(butylene adipate- co-terephthalate) (PBAT), Poly(lactic acid) (PLA) and casting polypropylene (CPP) at dose levels from 0 to 50 kGy. The properties of gamma irradiated samples were analyzed using DSC, TGA, UTM and FT-IR spectra. The mechanical and thermal properties of PBSeT and PBAT after gamma irradiation were less affected than CPP. The tensile strength and elongation of PBSeT was not affected by gamma irradiation, while these of PBAT, PLA and CPP were significantly decreased at 50 kGy gamma-ray dose. The thermal stability of PBSeT, PBAT, PLA and CPP showed a similar tendency to tensile strength. The glass transition temperature(Tg) and melting temperature(Tm) of PBSeT and PBAT were not altered by increasing gamma-ray dose, while these of PLA and CPP decreased. The chemical composition of all samples was not modified by gamma irradiation, and it was confirmed by FT-IR spectra. Based on mechanical and thermal stability studies of gamma irradiation on bioplastics, tested biodegradable packaging materials showed a potential to be used in sterilization process up to 35 kGy.

SERS Investigation on Oligopeptides Used as Biomimetic Coatings for Medical Devices.

The surface-enhanced Raman scattering (SERS) spectra of three amphiphilic oligopeptides derived from EAK16 (AEAEAKAK)2 were examined to study systematic amino acid substitution effects on the corresponding interaction with Ag colloidal nanoparticles. Such self-assembling molecular systems, known as “molecular Lego”, are of particular interest for their uses in tissue engineering and as biomimetic coatings for medical devices because they can form insoluble macroscopic membranes under physiological conditions. Spectra were collected for both native and gamma-irradiated samples. Quantum mechanical data on two of the examined oligopeptides were also obtained to clarify the assignment of the prominent significative bands observed in the spectra. In general, the peptide–nanoparticles interaction occurs through the COO− groups, with the amide bond and the aliphatic chain close to the colloid surface. After gamma irradiation, mimicking a free oxidative radical attack, the SERS spectra of the biomaterials show that COO− groups still provide the main peptide–nanoparticle interactions. However, the spatial arrangement of the peptides is different, exhibiting a systematic decrease in the distance between aliphatic chains and colloid nanoparticles.

Gamma radiation on silver nano colloid for anti-fungal activity

Soft gamma ray irradiation is done on Silver nano colloids prepared using Pepper Nigrum as reducing and stabilizing agent. Change in surface morphology and the structure of the colloid is obtained from Transmission Electron Microscope images and Selected area Electron Diffractogram. Morphology of the gamma irradiated sample is devoid of nano particle clusters and the Selected Area Electron Diffraction pattern confirms the crystal nature as face centered cubic structure of nano silver. UV–visible spectroscopic analysis gives the absorption peaks in the green region. Gamma irradiation results in the reduction in peak intensity without any change in wavelength. A statistical approach is done on treating the gamma irradiated colloidal sample with the as prepared silver nano colloid for measuring the area of affecting fungal infection on a potato-agar medium. It is found that the fungal growth is declined rapidly with the introduction of gamma irradiated silver nano colloid than the as prepared colloid.

Loss of chemical bonds induced by high doses of γ-radiation in a PADC polymer film: The influence of dose and dose rate on radiation chemical yields

The effects of gamma rays on molecular properties of a poly allyl diglycol carbonate (PADC) polymer, commercially named as CR-39, have been studied. PADC films were exposed to gamma rays at doses ranging from 0.5 to 3 MGy. Gamma exposure induces considerable molecular modifications in PADC films. These modifications were analyzed using Fourier transform infrared (FT-IR) spectroscopy. FT-IR absorption spectra of the gamma irradiated samples show a change in the intensity and the shape of the absorption bands of the chemical groups forming the PADC polymer relative to the pristine one. We have determined G-values for the loss of carbonate ester and ether chemical moieties within PADC. By comparing our G-values with those from other studies, we show that dose rate and dose significantly affect the radiation chemical yields and play an important role of molecular bond kinematics.

Thermoluminescence dosimetric characteristics of terbium doped barium metaborate phosphors

Rare earth doped barium metaborate (BaB2O4) polycrystalline phosphors were synthesized by the solid-state method. Among these, the BaB2O4:Tb phosphor showed a favorable thermoluminescence (TL) glow curve with good sensitivity. TL dosimetric characteristics were studied for BaB2O4:Tb by optimizing the concentration of the Tb dopant at 0.45 mol%. The powder XRD results confirm the formation of stable crystalline material with rhombohedral structure. The TL glow curve of gamma irradiated powder samples revealed two major peaks at 485 K and 620 K. The gamma dose response of this phosphor has been studied from 200 mGy to 20 kGy. For the 485 K peak, the response is found to be linear up to 1 Gy, then there is a supralinearity up to 250 Gy followed by a sublinear response with a linearity index varying from 1 to 1.4 (max.) and finally reducing to 0.9. The TL kinetic parameters such as the activation energy (E), frequency factor (s), and order of the kinetics have been obtained by initial rise, peak shape, and glow curve deconvolution methods. The order of the kinetics for the TL peak has been found to be 2.25 for 485 K and 2 for 620 K. The dosimetric studies showed that BaB2O4:Tb is suitable for dose measurements in high radiation areas, like glove box, hot cells, gamma irradiators etc., except for low energy gammas and x-rays.

Effect of High Doses Gamma Irradiation on Texturing of Bi2Sr2CaCu2O8 (Bi-2212) Superconductor

The effect of high doses gamma irradiation on the texture and microstructure of Bi2Sr2CaCu2O8 (Bi-2212) superconductor is studied in order to observe the sustainability of the material in radiation environment such as gamma radiation. The prepared samples have been irradiated with 100 kGray (kGy) of gamma irradiation and investigated by powder X-ray diffraction (XRD) and scanning electron microsopy (SEM). The Texture Coefficient (TC) for both the non-irradiated and irradiated samples has been calculated. The XRD patterns of the samples showed the Bi-2212 phase as the dominant phase. However, reduction in the intensity of Bi-2212 phase is observed in the gamma irradiated sample. Furthermore the calculated TC percentage of the irradiated sample have lower values when compared to the non-irradiated sample. The SEM micrograph of the irradiated sample showed random grains orientation with poorly connected inter and intra-grain microstructure that are in agreement with the calculated TC percentage.

Amendment the physicochemical properties of polycarbonate/polybutylene terephthalate blend by gamma-ray irradiation doses

In this study, blend of polycarbonate (PC)/polybutylene terephthalate thin films was used. This blend belongs to the class of polymeric solid-state nuclear track detectors. Blend samples were exposed to gamma-rays with different doses (55–355 kGy). The compositional changes, the changes of optical properties, the electrical parameters changes and surface morphology in the gamma irradiated samples were studied. Different techniques were used to study improving the physicochemical properties of the irradiated samples, such as Fourier transform infrared spectroscopy, UV–Visible spectroscopy, LCR Meter Bridge and scanning electron microscope, as well as, the roughness testing. Fourier transform infrared measurements exhibit that the degradation in the polymer chain occurs after irradiation with gamma-rays. This means that some functional groups are the most sensible groups to gamma-rays. UV–Visible spectra of the gamma exposed samples exhibited a shift in the absorbance edge toward the region of higher wavelength. This trend reflects a decrease in the band gap energy, which leads to an increase in the electrical conductivity of the samples. The outcomes of dielectric loss and dielectric constant are sensible parameters for whole frequency range to the changes in the structural and optical behaviors as a result to gamma irradiation. Additionally, the surface changes were discussed.

Dose-Dependent Differentiation of Gamma-Irradiated Hazelnut Samples by Mid-Infrared Spectroscopy Coupled with Chemometrics

Gamma irradiation is used as a food preservation method. It is known that high-dose irradiation causes several structural and functional damages. Therefore, the detection of high-dose irradiated food samples is a critical issue in international trade. The objective of this work is to evaluate the potential of Fourier transform infrared (FTIR) spectroscopy for the differentiation of γ-irradiated hazelnuts at higher doses (3 kGy and 10 kGy) from the lower (1.5 kGy) and nonirradiated ones using multivariate statistical analysis, namely, principal component analysis (PCA) and hierarchical cluster analysis (HCA). This study showed that high-dose irradiated hazelnut samples can be clearly differentiated from the low-dose irradiated samples using unsupervised methods based on the spectral differences. Furthermore, dose-dependent discrimination was also achieved. In conclusion, FTIR spectroscopy combined with multivariate statistical analysis has potential for the development of a reliable and fast methodology for separation of high-dose irradiated food samples.

Anti Fungal Studies of Tea Leaf mediated Silver Nano Colloid

Silver nano colloids are prepared using Tea leaf as reducing and stabilizing agent. Samples with different concentrations of the reducing agents are irradiated with gamma rays of various doses. Transmission Electron Microscope images of the samples show agglomerated clusters of nano particles before irradiation while the images of after irradiation show chain free individual nano particles with reduced size and spherical morphology. The Selected Area Electron Diffraction pattern confirms the crystal nature and face centred cubic structure of nano silver. UV-Visible spectroscopy gives absorption peaks in the blue region. Gamma irradiation results in the reduction in peak intensity without any change in wavelength. A statistical approach is done on treating the gamma irradiated colloidal sample with the as prepared silver nano colloid for measuring the affected area of fungal infection on a potato-agar medium. It is found that the fungal growth is declined rapidly with the introduction of gamma irradiated silver nano colloid than the as prepared colloid.

Study of a Gamma Radiation Impact on Concrete Properties Under Severe Accident Conditions

Abstract Concrete is an important structural material used in nuclear power plant (NPP) design. Due to relatively high amount of hydrogen as well as the presence of heavier elements, it also acts as a biological shielding. One of the important tasks for prolongation of operational life time is the determination of concrete components' condition after long-term irradiation. The paper aims to present the current activities in the CV Řež institute (Research Centre Řež—CVR) regarding the investigation of ionizing radiation effects on concrete properties. In its first part, the paper deals with experimental identification of the character of mixed neutron and gamma spectra in the concrete part of the VVER-1000 Mock-Up. Using the knowledge, the radiation field character can be scaled up to the commercial power plants with VVER-1000 light water reactor. It also provides justification for usage of the 60Co source for performed irradiation experiments with concrete. The second part of the article describes the experimental studies of the properties of gamma-irradiated concrete samples by strong 60Co source. This irradiation experiment can be understood as the first step in characterizing concrete degradation as gamma flux in biological shielding is significantly higher than that of neutron flux. In order to better understand the concrete properties and the behavior under irradiation, nondestructive as well as destructive testing methods were applied. We found that after 48 days of irradiation by the 60Co source the sample obtained dose from gamma corresponding to approximately 1% of the total during the NPP lifetime operation. Concrete microstructure degraded and the modulus of elasticity slightly decreased within 5%. Conversely, destruction tests prove significant flexural strength decrease by 27% in case of normal test and by 63% at the loss of coolant accident (LOCA) test.

Mapping the local structure of fullerene C60 and Cu–C60 nanocomposite thin films by gamma rays irradiation

The stability of fullerene C60 and Cu–C60 nanocomposite thin films are measured by exposing to gamma irradiation at different doses ranging from 25 kGy to 100 kGy. FTIR vibrational spectroscopy shows no effect of gamma irradiation on the fullerene C60 but gives a CC vibration at the highest dose of 100 kGy in Cu–C60 nanocomposite. The Raman spectroscopy was performed at two different wavelengths (325 nm and 532 nm) to know the structural transformation of fullerene and its nanocomposite thin film. At the wavelength of 532 nm, polymerization of fullerene molecules is observed in Cu–C60 nanocomposite thin film. UV–visible spectroscopy shows more prominent modes of fullerene C60 after gamma irradiation. Transmission electron microscopy is used to know the increase in particle size of the nanocomposite thin films. Contact angle measurements are also performed to know the wettability of the gamma irradiated samples. Finally, X-Ray photoelectron spectroscopy is performed to know the elemental state of these samples.

Computer and Experimental Simulation of Alloxazine Synthesis from Gamma Irradiation of Amino Acids on Iceland Spar: A Prebiotic Chemistry Perspective.

On ancient Earth, environmental conditions favored prebiotic chemical reactions. In the Archean, some molecules with conjugated rings might have been synthesized, displaying structural stability in the Archean in the presence of ionizing radiation and hydration-dehydration events. Additionally, it is suggested that on ancient Earth, calcite was a common mineral promoting organic compound synthesis. In the present work a study of the interaction of amino acid mixtures with the (104) surface of calcite is presented. Our preliminary results show the abiotic synthesis of alloxazine (a flavin with relevant photochemical properties). Computer simulations were performed in HyperChem 8.0.1. by means of MM+ molecular mechanics and PM3 semi-empirical methods, in 27 possible amino acid trimers of alanine, glycine and lysine. Alloxazine formation is possible by the gamma irradiation of amino acids. The computer simulations show that trimers GGG and GGA promote the further transformation from diketopiperazines (DKP's) and KGK to alloxazine. The computer simulations with free radicals are not stable when alloxazine is interacting with the calcite surface. Experiments in anoxygenic environments with hydration-dehydration events in gamma irradiated samples allow the abiotic formation of flavins, DKP's and a heterocycle compound with possible relevance in prebiotic chemistry.

Producing Useful Chemicals Using a Nuclear Reactor

In this paper, the irradiation of glycerol and ethylene glycol by either mixed (neutron-γ) or γ-only (γ) fields at the TRIGA reactor of the Jožef Stefan Institute is described. This is highly relevant to future applications of fission reactor systems to produce useful feedstock derivatives from organic waste, beyond the production of heat and power. Samples of glycerol and ethyl glycol have been exposed to neutron-gamma radiation with fast neutron fluxes ranging from 7.7×1010 to 3×1012 cm−2s−1 and gamma-only irradiation at maximum dose-rates of 492 and 10 kGy hr−1, respectively. A study of the dependence of product yield versus absorbed dose has been conducted, for total dose ranges of 1 to 100 kGy. The products of these exposures have been identified through Gas Chromatography – Mass Spectrometry (GC-MS) techniques. Analysis comparing neutron-gamma irradiated samples of ethylene glycol and glycerol with gamma-irradiated samples shows no detectable qualitative difference between either irradiation type. Although, additional radiolysis products were detected when compared with available literature; ethyl acetate from ethylene glycol and solketal from glycerol. Quantitatively, neutron-gamma irradiation seems to be less effective at producing acetaldehyde from ethylene glycol, compared with gamma-only which can be explained through neutron moderation and consequent heating effects due to the borosilicate vials.

Degradation studies of a commercial radiation‐resistant polypropylene sterilized by gamma and electron beam technology before and after subsequent accelerated aging cycles

ABSTRACTIrradiation is one of the most widely used technologies for sterilization of medical products. Unfortunately, some polymers in the medical field are susceptible to high‐energy radiation. In the case of polypropylene, this leads to yellowing and embrittlement due to degradation mechanisms. This study compares the impact of gamma and eBeam sterilizations at a dose of 45 kGy on a commercially available, radiation‐resistant polypropylene in combination with accelerated aging studies. Mechanical behavior as well as yellowing, accompanied by structural investigations like molar mass characterization and crystallinity analysis, have been investigated. It is shown that eBeam has less damaging effects compared with gamma irradiation. This is shown by an initial drop in elongation at break by 46% for gamma irradiated samples in contrast to 24% decrease using eBeam irradiation. Also, an initial drop in molar mass by 43% was found for gamma irradiated samples and by 27% for eBeam. Change in color was observed by an initial increase in the yellowness index of 42% at samples after gamma irradiation, respectively, of 22% for eBeam irradiated samples. Interestingly, molar mass remained constant during aging, whereas yellowing and Embrittlement further change. Additionally, empirical equations were found, which describe the experimental data. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48436.