High Doses Of Gamma Radiation Research Articles

Thermoluminescence and photoluminescence properties of NaCl:Mn, NaCL:Cu nano-particles produced using co-precipitation and sono-chemistry methods

The NaCl: Cu and NaCl: Mn nanoparticles (NPs) were produced by co-precipitation and sono-chemistry methods and their thermoluminescence (TL) and photoluminescence (PL) properties were studied. By decreasing the particles size a considerable increase in sensitivity of the samples to high dose gamma radiation was observed. The NPs produced by sono-chemistry method have smaller size, homogeneous structure, more sensitivity to high gamma radiation and less fading than of those produced by co-precipitation method.

Comparison of gamma and electron beam irradiation in reducing populations of E. coli artificially inoculated on mung bean, clover and fenugreek seeds, and affecting germination and growth of seeds

Sprouts have frequently been implicated in outbreaks of foodborne illnesses, mostly due to contaminated seeds. Intervention technologies to decontaminate seeds without affecting sprout yield are needed. In the present study, we compared gamma rays with electron beam in inactivating E. coli artificially inoculated on three seeds (fenugreek, clover and mung bean) that differed in size and surface morphology. Furthermore, the germination and growth of irradiated seeds were evaluated. Results showed that the D10 values (dose required to achieve 1log reduction) for E. coli K12 on mung bean, clover, and fenugreek were 1.11, 1.21 and 1.40kGy, respectively. To achieve a minimum 5-log reduction of E. coli, higher doses were needed on fenugreek than on mung bean or clover. Electron beam treatment at doses up to 12kGy could not completely inactivate E. coli inoculated on all seeds even though most of the seeds were E. coli-free after 4–12kGy irradiation. Gamma irradiation at doses up to 6kGy did not significantly affect the germination rate of clover and fenugreek seeds but reduced the germination rate of mung bean seeds. Doses of 2kGy gamma irradiation did not influence the growth of seeds while higher doses of gamma irradiation reduced the growth rate. Electron beam treatment at doses up to 12kGy did not have any significant effect on germination or growth of the seeds. SEM imaging indicated there were differences in surface morphology among the three seeds, and E. coli resided in cracks and openings of seeds, making surface decontamination of seeds with low energy electron beam a challenge due to the low penetration ability. Overall, our results suggested that gamma rays and electron beam had different effects on E. coli inactivation and germination or growth of seeds. Future efforts should focus on optimization of electron bean parameters to increase penetration to inactivate E. coli without causing damage to the seeds.

Changes in wheat and potato starches induced by gamma irradiation: A comparative macro and microscopic study

ABSTRACTWheat and potato starches were treated by gamma irradiation (0, 3, 5, 10, 20, 35, and 50 kGy). Apparent amylose content, gelatinization maximum consistency, swelling power, viscosity, and textural parameters decreased in potato and wheat starch pastes as irradiation dose increased. Nevertheless, the decrease of apparent amylose content and swelling power was greater in potato starch than in wheat one. High gamma irradiation doses made potato starch granules more sensitive to shear. On the other hand, no modification in the granule shape was observed by scanning electron microscopy. However, through heat-treatment, starch granules destroyed as irradiation dose increased. Consequently, the effect of irradiation on granular structure appeared to be greater in potato starch than in wheat starch.

A comprehensive investigation of mechanical and acoustic modifications in wood treated with high doses of gamma radiation for sterilization

ABSTRACTGamma radiation is a most efficient tool for sterilization, and especially effective on infesting pest, as it also kills the eggs. However, the large radiation doses entailed (tens of kilogray and up) might have adverse effects on desirable properties of wood. Of particular interest are the acoustic properties, as radiation would otherwise appear to be the perfect tool for the sterilization of musical instruments. The present investigation was aimed at determining the effects on acoustic and mechanical properties. Samples of four different wood species – poplar, oak, fir and maple – were prepared selecting wood completely free of visually detectable defects and subjected to incremental dose levels, reaching 25, 50, 100 and 200 kGy. A further set of samples were subjected to 200 kGy in one go, to investigate possible differences with incremental doses. Irradiation was conducted at an industrial irradiation facility, operating with a cobalt-60 source of the order of the megacurie. The mechanical tests were designed to measure the elastic modulus and the bending strength as well as force and displacement at rupture. Acoustic tests were developed specifically for this experiment, with the purpose of measuring the vibrational modes of the samples. All the samples exhibited discoloration and noticeable changes in properties: rigidity increased, load to rupture decreased, the material became more brittle and effects increased with increasing dose. The acoustic tests revealed a shift toward higher frequencies of all the vibrational modes, and this was exhibited for all wood species investigated. No meaningful difference was observed between the samples treated with incremental doses up to a total of 200 kGy and with a single 200 kGy dose.

Suitability of pure nanocrystalline LiF as a TLD dosimeters for high dose gamma radiation

Suitability of pure nanocrystalline LiF as a TLD dosimeters for high dose gamma radiation

The dosimetric properties of phosphate glass systems prepared by different chemical nanomaterials.

The synthesis and characterization of glass systems were carried out using prepared nanocrystals injected into a glass matrix as a thermoluminescence (TL) activator using the melt-quenching method. Sample 1 was prepared as [40P2 O5 50BaO:2.5MgO, 2.5Na2 O, 5TiO2 ], sample 2 as [37.5P2 O5 37.5CaO:25TiO2 ] and sample 3 as [50P2 O5 -50Li2 O]. Formation of the synthesized compound was confirmed by studying the X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM) images. An annealing procedure was carried out for 1h at 400°C. The glow curve position and shape shifted dramatically and linearly to the higher temperature values on increasing the heating rate. A heating rate of 30°C/s was the most suitable for obtaining a high TL response. Samples 2 and 3 have the highest TL response, which approached the effective atomic number (Zeff ) of natural bone. The observed TL sensitivity of the prepared samples 2 and 3 is less than that of commercially available 'TLD-200 chips' and LiF:Mg,Ti (TLD-100) phosphor. Sample [37.5P2 O5 37.5CaO:25TiO2 ] would be useful in personal and environmental dosimetry for measuring high doses of gamma radiation. Sample [50P2 O5 -50Li2 O] is a good dosimeter, although it requires the addition of an appropriate transitional metal (activator) to overcome the problem of high fading. Copyright © 2016 John Wiley & Sons, Ltd.

High gamma irradiation doses and long storage times reduce soybean seed quality

High quality seeds are required for soybean production. This study evaluated the effect of gamma irradiation and storage time on seed quality in soybean lines VX04-6828 and VX04-5692. Seeds were gamma irradiated (60Co) with 0, 50, 150, and 250 Gy. After the first seed production cycle (M1), the harvested seeds were stored in the laboratory for 0, 2, 4, and 6 months. Moisture content, seed quality (germination rate, dead seeds, and normal and abnormal seedlings), and seed vigor (first germination count, germination index, and seedling length) were determined. Data were submitted to analysis of variance for each soybean line using a 4 x 4 factorial design (four storage times x four gamma irradiation doses). Response surfaces were constructed based on the F test significance (p ? 0.05). VX04-5692 seeds were more sensitive to gamma radiation than were VX04-6828 seeds. Soybean seed quality was highest in M2 seeds derived from seeds irradiated with less than 100 Gy and stored for up to two months. High gamma irradiation doses and long storage times reduced soybean seed quality.

Effects of high dose gamma irradiation on ITO thin film properties

Transparent thin-film Indium Tin Oxides (ITO) were prepared on 0.7mm thick glass substrates using a pulsed laser deposition (PLD) process with average thickness of 150nm. The samples were then exposed to high gamma γ radiation doses by 60Co radioisotope. The films have been irradiated by performing exposure cycles up to 250kGy total doses at room temperature. The surface structures before and after irradiation were analysed by x-ray diffraction. Atomic Force Microscopy (AFM) was performed on all samples before and after irradiation to investigate any change in the grain sizes, and also in the roughness of the ITO surface.We investigated the influence of γ irradiation on the spectra of transmittance T, in the ultraviolet-visible-near infrared spectrum using spectrophotometer measurements. Energy band gap Eg was then calculated from the optical spectra for all ITO films. It was found that the optical band gap values decreased as the radiation dose was increased.To compare the effect of the irradiation on refractive index n and extinction coefficient k properties, additional measurements were done on the ITO samples before and after gamma irradiation using an ellipsometer. The optical constants n and k increased by increasing the irradiation doses. Electrical properties such as resistivity and sheet resistance were measured using the four-point probe method. The good optical, electrical and morphological properties maintained by the ITO films even after being exposed to high gamma irradiation doses, made them very favourable to be used as anodes for solar cells and as protective coatings in space windows.

Effects of high-dose gamma irradiation on tensile properties of human cortical bone: Comparison of different radioprotective treatment methods

There are growing interests in the radioprotective methods that can reduce the damaging effects of ionizing radiation on sterilized bone allografts. The aim of this study was to investigate the effects of 50kGy (single dose, and fractionated) gamma irradiation, in presence and absence of l-Cysteine (LC) free radical scavenger, on tensile properties of human femoral cortical bone. A total of 48 standard tensile test specimens was prepared from diaphysis of femurs of three male cadavers (age: 52, 52, and 54 years). The specimens were assigned to six groups (n=8) according to different irradiation schemes, i.e.; Control (Non-irradiated), LC-treated control, a single dose of 50kGy (sole irradiation), a single dose of 50kGy in presence of LC, 10 fractions of 5kGy (sole irradiation), and 10 fractions of 5kGy in presence of LC. Uniaxial tensile tests were carried out to evaluate the variations in tensile properties of the specimens. Fractographic analysis was performed to examine the microstructural features of the fracture surfaces. The results of multivariate analysis showed that fractionation of the radiation dose, as well as the LC treatment of the 50kGy irradiated specimens, significantly reduced the radiation-induced impairment of the tensile properties of the specimens (P<0.05). The fractographic observations were consistent with the mechanical test results. In summary, this study showed that the detrimental effects of gamma sterilization on tensile properties of human cortical bone can be substantially reduced by free radical scavenger treatment, dose fractionation, and the combined treatment of these two methods.

Amorphous and crystalline optical materials used as instruments for high gamma radiation doses estimations

Nuclear radiation induce some changes to the structure of exposed materials. The main effect of ionizing radiation when interacting with optical materials is the occurrence of color centers, which are quantitatively proportional to the up-taken doses. In this paper, a relation between browning effect magnitude and dose values was found. Using this relation, the estimation of a gamma radiation dose can be done. By using two types of laser wavelengths (532nm and 633nm), the optical powers transmitted thru glass samples irradiated to different doses between 0 and 59.1kGy, were measured and the associated optical browning densities were determined. The use of laser light gives the opportunity of using its particularities: monochromaticity, directionality and coherence. Polarized light was also used for enhancing measurements quality. These preliminary results bring the opportunity of using glasses as detectors for the estimation of the dose in a certain point in space and for certain energy, especially in particles accelerators experiments, where the occurred nuclear reactions are involving the presence of high gamma rays fields.

Study of the luminescent behavior of Spectrolite + Teflon pellets in 90Sr + 90Y beams

The Spectrolite, from the silicate family, a variety of Labradorite, was already studied in relation to its thermoluminescence (TL) and optically stimulated luminescence (OSL) responses, in high-dose gamma radiation fields; the results indicated their good application as gamma radiation detectors. In the present work, the analyses performed to investigate powdered Spectrolite are presented, by means of the XRD, SEM and EDX techniques. The luminescent behavior of Spectrolite + Teflon samples, in the concentration of 1:1, was studied in beta radiation beams (90Sr + 90Y), using the luminescent phenomena of TL and OSL. The results showed adequate TL and OSL reproducibility of the samples; the dose–response curves for both techniques presented a linear behavior in a range from 0.5 Gy to 1 kGy, and the fading showed that after 150 h there were 46.7% and 31.6% of the remaining signal of samples for TL and OSL responses, respectively. Therefore, the Spectrolite + Teflon pellets may be used in beta radiation dosimetry.

Protective Effect of Pyruvate Against Radiation-Induced Damage in Collagenized Tissues

Exposure to high doses of ionizing radiation produces both acute and late effects on the collagenized tissues and have profound effects on wound healing. Because of the crucial practical importance for new radioprotective agents, our study has been focused on evaluation of the efficacy of non-toxic naturally occurring compounds to protect tissue integrity against high-dose gamma radiation. Here, we demonstrate that molecular integrity of collagen may serve as a sensitive biological marker for quantitative evaluation of molecular damage to collagenized tissue and efficacy of radioprotective agents. Increasing doses of gamma radiation (0-50kGy) result in progressive destruction of the native collagen fibrils, which provide a structural framework, strength, and proper milieu for the regenerating tissue. The strategy used in this study involved the thermodynamic specification of all structural changes in collagenized matrix of skin, aortic heart valve, and bone tissue induced by different doses and conditions of g-irradiation. This study describes a simple biophysical approach utilizing the Differential Scanning Calorimetry (DSC) to characterize the structural resistance of the aortic valve matrix exposed to different doses of g-irradiation. It allows us to identify the specific response of each constituent as well as to determine the influence of the different treatments on the characteristic parameters of protein structure. We found that pyruvate, a substance that naturally occurs in the body, provide significant protection (up to 80%) from biochemical and biomechanical damage to the collagenized tissue through the effective targeting of reactive oxygen species. The recently discovered role of pyruvate in the cell antioxidant defense to O2 oxidation, and its essential constituency in the daily human diet, indicate that the administration of pyruvate-based radioprotective formulations may provide safe and effective protection from deleterious effects of ionizing radiation.

Impact of High Dose of Gamma Radiation on Field Collected &lt;i&gt;Aedes aegypti&lt;/i&gt;

Mosquitoes that transmit pathogens to humans received much attention during last few decades. Aedes aegypti causes certain diseases like dengue, yellow fever andchikungunya. There are no effective vaccines and drugs available for those diseases. The control of Aedes aegypti is the only effective way for prophylyxis from this disease. Radiation has played an important role in insect pest management. To determine the radio sensitivity, an experiment was conducted to understand the effect of γ - radiation at higher doses on immature stages of Aedes aegypti. One day old pupae were irradiated with variable doses between 100Gy to 1000Gy to study the pupal viability, adult emergence and development of malformation if any. The dose response curve between the pupal viability and dose was determined and there was a marked difference in radiation sensitivity . It was observed that the pupal viability decreased with increase in radiation dose in dose dependent manner. Pupal viability of about 99.2%, 61.4%, 42.5%, 13.4%, 7.5%, 6.7% and 3.9% was found after exposure to gamma radiation at 100Gy, 250Gy, 400Gy, 550Gy, 700Gy, 850Gy and 1000Gy respectively. Similarly, adult emergence was also drastically affected by radiation exposure. The percent adult emergence from irradiated pupae were about 99.2%, 61.3%, 42.4%, 13.4%, 7.2%, 6.4%, and 3.0% at 100Gy, 250Gy, 400Gy, 550Gy, 700Gy, 850Gy and 1000Gy respectively. Morphological deformities on both pupae and adult of Aedes aegypti were noticed after irradiation indicates the somatic damage of pupae and adults. It was observed that head, thorax and part of the abdomen with fore wings were released but the rest of the body still attached to the puparia. Similarly, few malformed adults with curled legs, crumpled wings and with curved abdomen were obtained due to the effects of high dose of gamma radiation at 400Gy and above.

The effects of terminal sterilization upon the biological activity and stiffness of extracellular matrix hydrogels

The effects of terminal sterilization upon the biological activity and stiffness of extracellular matrix hydrogels

Developing Suitable Sensitive Compound Semiconductor Materials Doped by Transition Metals for Occupational Thermoluminescence Dosimetry

The essential objective of radiation dosimetry is to develop suitable sensitive materials for different measurements in radiation fields. Our exploration is to find potentially suitable high gamma radiation dosimeters in the range from 0.5E4 to 1.5E4 Gy. Gamma rays source (60Co, 136 Gy/min) has been used. Many compound semiconductor materials were prepared and investigated. Thermoluminescence (TL) glow curve was analyzed into its component by analytical segregation program using computerized glow curve deconvolution (CGCD). Three zero dose readings for non-irradiated powders of the materials have been taken as lower limit of detection. The results indicated that some of the tested materials have exhibited TL linearly with respect to dose. In addition, dose response of these materials was found to be useful for high radiation dosimetry. Glow curve structures exhibited several peaks corresponding to the various energies of the emptied traps. Variation in the standard deviation for reusability cycles has been ten readout. The fading at ambient temperature was studied up to 60 days which reached a relative stability (~1.5% for all), 10 days after irradiation. A typical glow curve of CoPa which irradiated with 1.5E4 Gy was analyzed. Characterizations of tested materials indicated that crystals of ZnLa:Li, ZnLa:Cd, and ZnLa:Cr have stable and increasing thermoluminescent responses with high gamma radiation dose range. Special glow peaks can be used as estimators for absorbed doses as well as re-estimation for time elapsed exposures.

Effects of film thickness on scintillation characteristics of columnar CsI:Tl films exposed to high gamma radiation doses

Oriented columnar films of Tl doped CsI (CsI:Tl) of varying thicknesses from 50µm to 1000µm have been deposited on silica glass substrates by a thermal evaporation technique. The SEM micrographs confirmed the columnar structure of the film while the powder X-ray diffraction pattern recorded for the films revealed a preferred orientation of the grown columns along the <200> direction. Effects of high energy gamma exposure up to 1000Gy on luminescence properties of the films were investigated. Results of radio-luminescence, photo-luminescence and scintillation studies on the films are compared with those of a CsI:Tl single crystal with similar thickness. A possible correlation between the film thicknesses and radiation damage in films has been observed.

TL and OSL dosimetric properties of Opal gemstone for gamma radiation dosimetry

In this work, the response of the natural material Opal was studied in relation to its thermoluminescence (TL) and optically stimulated luminescence (OSL), after exposure to the gamma radiation of a 60Co source. The structure of the powdered Opal was verified using the X-ray diffraction, scanning electronic microscopy and energy-dispersive X-ray spectroscopy techniques. The material, in its stone form, was turned into powder and mixed to Teflon (also in powder) in three different concentrations, and then pellets were manufactured. The aim of this work was to evaluate the response of these pellets in high-doses of gamma radiation beams, and to observe their possible application as dosimeters, using the TL and OSL techniques. The dosimetric properties of the samples were analyzed by means of different tests, as: TL emission curves and OSL signal decay curves, reproducibility of TL and OSL response, minimum detectable dose, TL and OSL dose–response curves (5 Gy–10 kGy), and fading. The results obtained in this work, for the TL and OSL phenomena, demonstrated that the pellets of Opal + Teflon present an adequate performance e possibility of use as dosimeters in beams of high-dose gamma radiation.

Whole-Genome Sequencing in Microbial Forensic Analysis of Gamma-Irradiated Microbial Materials

Effective microbial forensic analysis of materials used in a potential biological attack requires robust methods of morphological and genetic characterization of the attack materials in order to enable the attribution of the materials to potential sources and to exclude other potential sources. The genetic homogeneity and potential intersample variability of many of the category A to C bioterrorism agents offer a particular challenge to the generation of attributive signatures, potentially requiring whole-genome or proteomic approaches to be utilized. Currently, irradiation of mail is standard practice at several government facilities judged to be at particularly high risk. Thus, initial forensic signatures would need to be recovered from inactivated (nonviable) material. In the study described in this report, we determined the effects of high-dose gamma irradiation on forensic markers of bacterial biothreat agent surrogate organisms with a particular emphasis on the suitability of genomic DNA (gDNA) recovered from such sources as a template for whole-genome analysis. While irradiation of spores and vegetative cells affected the retention of Gram and spore stains and sheared gDNA into small fragments, we found that irradiated material could be utilized to generate accurate whole-genome sequence data on the Illumina and Roche 454 sequencing platforms.

Effects of gamma irradiation on hydrogen gas-sensing characteristics of Pd–SnO2 thin film sensors

Monitoring hydrogen levels in radioactive environments is important in nuclear energy safety and space study because leakage of this gas can cause destructive detonation. Herein, hydrogen gas sensing devices were fabricated by using a simple design of a planar-type structure sensor containing a SnO2 thin film sensitized with microsized Pd islands. In addition, the effects of gamma irradiation on sensor performance were investigated and results revealed that low doses of gamma irradiation had ignorable effect on the sensing performance of the device. However, a relatively high dose of gamma irradiation improved the sensitivity of the device because of oxygen defect generation. The enhancement of hydrogen gas-sensing characteristics was correlated with microstructure and optical characterization. Results show that gamma irradiation induced defects in the SnO2 thin film, controlling the doping level, and thus enhancing the gas-sensing characteristic of the device. The sensor can be used for monitoring hydrogen gas at low concentrations of 50 ppm–500 ppm, with fast response and recovery time, making it suitable for potential safety applications in monitoring hydrogen levels in radioactive environments.

Effect of gamma radiation on the growth, survival, hematology and histological parameters of rainbow trout (Oncorhynchus mykiss) larvae

Effects of low (1, 2.5 and 5Gy) and high doses (10, 20 and 40Gy) of gamma radiation were examined on the growth, survival, blood parameters and morphological changes of the intestines of rainbow trout (Oncorhynchus mykiss) larvae (103±20mg) after 12 weeks of exposure. Negative effects of gamma radiation on growth and survival were observed as radiation level and time increased. Changes were well documented at 10 and 20Gy. All the fish were dead at the dose of 40Gy. In all the treatments, levels of red blood cells (RBC), hematocrit (HCT) and hemoglobin (HB) were significantly (P<0.05) declined as the irradiation levels increased, whereas the amount of mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) did not change. No significant differences (P>0.05) were found in the levels of white blood cells (WBC), lymphocytes and monocytes. Destruction of the intestinal epithelium cells was indicated as the irradiation levels increased to 1Gy and above. The highest levels of growth, survival, specific growth rate (SGR), condition factor (CF) and protein efficiency rate (PER) were obtained in the control treatment. The results showed that gamma rays can be a potential means for damaging rainbow trout cells.