Gamma-ray Exposure Research Articles

Effectiveness of Gamma Rays in Attenuating Rodent Malaria Parasites of <em>Plasmodium berghei</em> in Blood of Mice

Malaria is a major public health problem in Indonesia. Therefore, an effective vaccine against this disease is actively being sought by using gamma rays to attenuate the parasites. However, the safety and efficacy of the resulting vaccine are dependent on the precise irradiation dose. The aim of this research was to determine the exact time when the parasites are attenuated by gamma ray exposure. Mice blood containing Plasmodium berghei of 5,0 X 10 7 parasites/ml was irradiated with gamma rays at doses of 0, 150, 175 and 200 Gy (doses rate of 380 Gy/h) and then was injected intraperitoneally to mice at 0, 1, 2, 3, and 4 h post irradiation. The parasitemia (parasite density) in mouse blood was observed starting with day 2 and repeated every 2-4 days up to 28 days. The survival of the mice was also observed during the experiment. The results showed that the pre-patent period advanced with exposing infected blood to 150 and 175 Gy irradiations, suggesting some degree of attenuation. The amount of radiation required to render the parasites non-viable is about 175 Gy for an inoculum of a number of parasites, but a delay of 4 h resulted in the death of parasites. There was no difference in the infectivity of irradiated parasite injected 1 h and 2 h post irradiation in terms of parasitemia and the survival of mouse. For a dose of 200 Gy which was injected 2 h post irradiation, no parasitemia was found in the blood and animals which died after times varying from 1 to 4 weeks. We concluded that irradiated parasites should be injected into the host within 1 h after irradiation. Received: 16 January 2013; Revised: 23 April 2013; Accepted: 24 April 2013

Studies on energy absorption and exposure buildup factors in some solutions of alkali metal chlorides

Buildup of photons has been investigated through the solutions LiCl, NaCl and KCl with different salt contents in the energy region 0.015-15 MeV up to a penetration depth of 40 mean free paths. Two types of buildup factors, the gamma ray energy absorption () and exposure buildup factors () have been calculated simultaneously using the five parameter geometric progression (G-P) fitting formula. The influence of photon energy, penetration depth and chemical composition on the buildup factors has been studied. Also, a comparison has been made between the values of and if any significant variation occurs between them. Moreover, the Monte Carlo simulation study has been made for the purpose of the comparison. Key words: Gamma ray buildup factor, energy absorption, exposure, solution, Monte Carlo method.

Study of Gamma Ray Exposure Buildup Factor for Some Ceramics with Photon Energy, Penetration Depth and Chemical Composition

Gamma ray exposure buildup factor for some ceramics such as boron nitride (BN), magnesium diboride (MgB2), silicon carbide (SiC), titanium carbide (TiC) and ferrite (Fe3O4) has been computed using five parametric geometric progression (G.P.) fitting method in the energy range of 0.015 to 15.0 MeV, up to the penetration of 40 mean free path (mfp). The variation of exposure buildup factors for all the selected ceramics with incident photon energy, penetration depth, and chemical composition has been studied.

Growth and scintillation properties of (Lu1 − Tm )2SiO5 [x = 0.001, 0.01, 0.1, 1

(Lu 1 − x Tm x ) 2 SiO 5 ( x = 0.001, 0.01, 0.1, 1) single crystalline scintillators were grown by the μ-PD method. In transmittance measurement, absorption bands due to Tm 3+ 4f–4f transitions were observed at 260, 292, 356, 463, 680 and 790 nm and they could be ascribed to the transition from the 3 H 6 ground state to its excited states, 1 I 6 , 3 P 6 , 1 D 2 , 1 G 4 , 3 F 3 and 3 H 4 , respectively. Strong emission peak due to 1 D 2 → 3 F 4 transition of Tm 3+ was shown at 453 nm under X-ray irradiation. Photoluminescence decay time constant caused by this transition were evaluated to be 11.9 μs. Tm 1% doped one exhibited the highest light yield of 3530 ± 200 photons/MeV when excited by 137 Cs gamma-ray exposure. ► (Lu 1 − x Tm x ) 2 SiO 5 single crystals were grown by the μ-PD method. ► The Tm 3+ 4f–4f emission and absorption lines were observed. ► The scintillation decay times were evaluated as 11.9–13.5 μs. ► Pulse height measurements showed the 1% Tm sample had the highest light yield. ► Quenching was observed in higher Tm concentration.

Energy Absorption Buildup Factor Studies In Some Soils

An attempt is made to generate effective atomic number, energy absorption buildup factor (EABF) in the energy region 0.015-15.0 MeV up to a penetration depth of 40 mfp for some soils. The five parameters geometrical progression (G-P) fitting approximation has been used to calculate energy absorption build-up factor (EABF). The generated energy absorption buildup factors has been studied as function of incident photon energy & penetration depth and represented graphically. Index Terms: Energy absorption build-up factor (EABF), Mean free path (mfp), Effective atomic number (Zeff ), Equivalent atomic number (Zeq). I. INTRODUCTION Today, to benefit mankind, the radiations are used in basic sciences, medicine, and industry and for generating electricity Gamma radiations occupy the highest energy among the electromagnetic radiations. The exposure to gamma radiations with human body can occur during radiological diagnosis , nuclear reactors & nuclear research establishments .The use of radiations can be biologically hazardous, there is need of restrict and controlled exposure of human beings to these radiations by using shields of proper dimensions and of an appropriate material. The study has been focused on build-up factor which plays major role during interaction of gamma rays with the chosen soils. Nuclear accidents due to natural and manmade disasters cannot be refused in future. To avoid any hazard from day to day exposure of radiation the choice of material is very important for the purpose of shielding of radiations. People involved in industries, institutions & research labs may be the victim of gamma ray exposure. For the safety of people & selection of shielding materials, build-up factors study become important. When gamma radiations interact with material through Compton scattering. The scattering results in accumulation of photons in the interacting material due to which the number of photons buildup in the materials. Two types of build-up factors namely energy absorption build-up factor (EABF) & exposure build-up factor ( EBF). The concept of buildup factor was mutually introduced by White (1) and Fano (2) recognized its importance in attenuation studies.To calculate build-up factor there are different methods like G.P. fitting method. Harima et al. 1986 (3), invariant embedding method, Shimizu, 2002 (4); Shimizu et al., 2004 (5), iterative method, Suteau and Chiron, 2005 (6) and Monte Carlo method, Sardari et al., 2009 (7). Recently American National standards ANSI/ANS-6.4.3(8) has provided buildup factor data for 23 elements, one compound and two mixtures (i.e. air and water) and concrete at energies in the range 0.015-15 MeV up to penetration depths of 40 mfp by using the G.P method. D.Sardari and S. Baradaran 2010 (9) calculated buildup factor of gamma and X-ray photon the energy range of 0.2-2.0 MeV in water and soft tissue using Monte Carlo code MCNP4C. The results are compared with buildup factor data of pure water. In each case very small deviation is observed. There are successful contributions which are based on the buildup factor studies in some soils and ceramic materials available in the literature. For example, Brar et al. (10) have studied the variation of buildup factors of soils with weight fractions of iron and silicon. Sidhu et al. (11) have studied the energy and effective atomic number dependence of the exposure buildup factors in biological samples. Manohara et al. (12) studied the variation of exposure buildup factors for heavy metal oxide glass with photon energy and penetration depth. Singh et al. (13) studied the energy dependence of total photon attenuation coefficients of composite materials Sidhu et al. (14) have studied the energy and effective atomic number dependence of the exposure build-up factors in biological samples J. S. Dhillon et al.(15) have studied Gamma Ray Photon Energy Absorption build-up Factor In Some Soil II.

Investigation of X- and gamma ray photons buildup in some neutron shielding materials using GP fitting approximation

In the present work, the gamma ray energy absorption (EABF) and exposure (EBF) buildup factors have been calculated by using the five parameter geometric progression (GP) fitting formula for some neutron absorbent materials (H3BO3, Na2B4O7, NaCl) and neutron moderator hydrocarbons (C5H12, C6H14, C7H16, C20H42, C40H82) in the energy region 0.015–15MeV up to a penetration depth of 40mfp (mean free path). From the results, it has been concluded that the buildup of photons is less in NaCl when compared with other materials for the lower penetration depths (<15mfp for EABF, <10mfp for EBF) whereas for photon energies higher than 3MeV less buildup of secondary gamma rays occur in HC based materials than the other ones at higher penetration depths (>15mfp for EABF, >10mfp for EBF). The present results have been compared with MCNP calculations for various energies at 1mfp and a good correspondance has been obtained.

Measure of morphological and performance properties in polymeric silicone foams by X-ray tomography

In the absence of nuclear weapons testing, assuring comparable material performance for replacement of no-longer-available material with modern formulations is difficult. The replacement material must completely replicate the performance of the original. Quantification of morphological characteristics in three dimensions by micro X-ray computed tomography (μCT) lends statistics and property values not otherwise achieved. This allows for the measurement of lot-to-lot, synthesis formula variations, as well as pre- and post-experimental structural changes that would be invisible to qualitative image comparison techniques. Owing to the unavailability of the original material, several novel formulations of poly(dimethylsiloxane) (PDMS) foams were imaged and quantitatively compared to aid in choosing a replacement material. In this study, bulk properties were measured with μCT including, percent void volume, average void equivalent diameter and others, and were collected for four different formulations of PDMS foams from pristine, return for service, as well as samples that were aged by gamma ray exposure. Performance characteristics (e.g., Poisson ratio) were measured and compared. From this study, we will be able to provide more information for the selection of the material that most closely matches the performance of the original material.

Conversion of Ce3+ to Ce4+ ions after gamma ray irradiation on CeO2–PbO–B2O3 glasses

Abstract The structural and optical parameters of gamma ray irradiated cerium doped lead borate glasses have been analyzed using FTIR, UV–visible absorption, transmittance and density measurement techniques. It has been observed that due to gamma ray exposure, the optical band gap decreases, density increases and molar volume decreases correspondingly. FTIR spectroscopy confirms the conversion of [BO 3 ] to [BO 4 ] and also shows the presence of [CeO 4 ] groups of cerium in glass samples. The transmittance of the glass samples decreases due to formation of hole centers.

Unknown Quantity: Regulating Radionuclides in Tap Water

Radioactivity surrounds us; each day we are exposed to a certain amount by virtue of being alive on planet Earth. Some of this exposure comes from radioactive substances (radionuclides) that occur naturally in a wide variety of geologic and soil formations. Occasionally these naturally occurring substances become more concentrated or accessible through human activities such as mining and nuclear energy production, resulting in greater potential for exposure than their original natural occurrence would suggest. Other radionuclides are artificially created. Residents in almost all parts of the United States live on lands that contain minor to substantial concentrations of radionuclides of one type or another.1 These substances often make their way into tap water, leading to exposures by ingestion, inhalation, or dermal pathways during showering or other contact with the water. Although radionuclides are widespread, there are large gaps in our knowledge about sources of these materials, their distribution, associated health risks, and mitigation measures. However, the information we do have suggests that current drinking water standards for radionuclides established by the U.S. Environmental Protection Agency (EPA) may not adequately protect health. The EPA is set to review these standards relatively soon, and the next two years are prime time for filling in numerous information gaps and doing other legwork to make sure the review is as well informed as possible.

Gamma ray mediated mutagenesis of Phialocephala humicola: Effect on kinetics and thermodynamics of -amylase production

The current report dealt with the development of the fungus Phialocephala humicolathrough gamma ray treatment for the hyper production of α-amylases, which have diverse industrial applications. Improvement of microbes for the over production of industrial products has been the hallmark of all commercial fermentation processes. Three mutants (M13, M16 and M24) were selected based on the hyper-production of α-amylases. The mutants had gamma ray exposure of 100 and 140 krad (killing rate ≥ 99%). The mutants showed ≥ 2-fold improvement in enzyme production. The effects of inoculum size, temperature, pH and starch concentration on the growth kinetic parameters [µ, td, Yp/x, qp,µm, Ks(x), qpmax, Ks(p)] and thermodynamic parameters [ΔG*(x), ΔH*(x), ΔS*(x) and ΔG*(p), ΔH*(p), ΔS*(p)] were determined. Optimal conditions for the amylase production by the mutants were: inoculum 10% (v/v); pH range of 4-5 and temperature 37°C. The activation energy for cell mass [Ea(x)] of parent, M13, M16 and M24 was 3.095, 15.73, 3.68 and 8.03 kJ mol-1, respectively, whereas their Ea(p) for the enzyme production was 69.42, 22.94, 17.04 and 20.78 kJ mol-1, respectively. The maximum specific rate of cell mass formation (µm) of all mutated strains were greater than that of the parent strain, while specific rate for the maximum product formation (qpmax) of the mutants was about two fold higher than the parental strain. Key words: Activation energy, cell mass estimation, entropy, gibbs free energy growth kinetics.

Effect of gamma irradiation on the etching properties of Lexan and Makrofol-DE polycarbonate plastics

It is observed that for Lexan and Makrofol-DE polycarbonate plastic detectors the mean diameters of fission fragments from a 252Cf source increases as a result of gamma-ray exposure. We have studied the bulk etching rate and track etching rate before and after gamma-ray irradiation on Lexan and Makrofol-DE polycarbonate plastics. The mechanism of Lexan and Makrofol-DE polycarbonate plastic detectors can be understood with the help of this exposures. It is also noted that degree of ordering of Lexan and Makrofol-DE polycarbonate is dependent on the gamma ray dose due to degradation and cross-linking processes. The results show that bulk and track etch rate increases with gamma dose while activation energy associated with bulk and track etch rates at a particular temperature and sensitivity decreases with gamma dose.

Thermoluminescence and photoluminescence in the NaCaPO4:Dy3+ phosphor

Dy(3+)-doped NaCaPO(4) phosphor was synthesised at an initiating combustion temperature of 600°C, using urea as the fuel. The crystallinity of the phosphor was investigated by using X-ray diffraction. The photoluminescence and thermoluminescence (TL) behaviours of NaCaPO(4):Dy(3+) phosphor was also studied. It has a simple TL glow curve structure, which does not change when exposed to gamma-rays. A TL glow peak is observed at 230°C and TL intensity is around 1.15 times more compared with commercial CaSO(4):Dy TLD phosphor. The TL characteristics of the phosphor prepared show that it has good sensitivity, linear response with gamma-rays exposure, emission in the blue-yellow regions of the spectrum, negligible fading and excellent reusability. These results make Dy(3+)-doped NaCaPO(4) phosphor attractive for TLD applications.

Radiation Effects in Si-NW GAA FET and CMOS Inverter: A TCAD Simulation Study

In this brief, we have analyzed the response of silicon-nanowire (Si-NW) gate-all-around (GAA) field-effect transistor to total ionizing dose (TID) effects and assessed the impact of single-event effects (SEEs) in simple inverter circuit built from such devices. The analysis of radiation effects is carried out with 3-D technology computer-aided design simulations. Reliability of n-channel and p-channel Si-NW MOSFET is investigated for TID effects with gamma ray exposure. The transient effects at the device level are studied for alpha particle and heavy-ion strikes. It is found that Si-NW MOSFET is inherently hardened to TID effects. This result is in concordance with the earlier reported experimental results. However, we found that Si-NW CMOS inverter is not as tolerant to SEE, as Si-NW MOSFET is to TID. This study highlights the need for radiation-hardened Si-NW FET circuits against SEE.

Correlation between mechanoluminescence and lyoluminescence in gamma-irradiated KBr:Ce3+ phosphor for radiation dosimetry

Abstract Comparative study of mechanoluminescence (ML) and the lyoluminescence (LL) of γ-irradiated coloured powder of KBr:Ce3+ (0.1–10 mol%) phosphor is reported in this paper. Correlation between mechanoluminescence and lyoluminescence is observed, based on the formed colour centre due to γ-irradiation. All samples were prepared by a wet-chemical method. Single isolated ML and LL glow curve is observed in all samples. The variation of peak ML and LL intensities with gamma rays exposure and with different concentration of Ce3+ doped in KBr:Ce3+ is studied. The ML and LL intensities are found to be dependant on concentrations of Ce3+ and gamma radiation dose. The variation of peak ML and LL intensities of KBr:Ce3+ (0.5 mol%) with different gamma dose is found to be sublinear upto 1.5 kGy high dose and then the intensity becomes saturated. Negligible fading in the prepared sample is observed.

Radio-Sensitivity of Some Selected Landraces of Pulses to Gamma Irradiation: Indices for Use as Improvement and Preservation Techniques

Aim: Effects of gamma irradiation on amino acid profile, proximate and anti-nutritional compositions of selected landraces of pulses were investigated. Methods: Seeds of Brown “Fiofio”, White “Fiofio” ( Cajanus cajan ) and “Olaudi” ( Vigna unguiculata ) were exposed to gamma irradiation. Each variety was divided into five groups of fifty grams weight and was exposed to 200, 400, 600, 800Gray (Gy) doses of gamma irradiation from Cobalt 60 source while the fifth group served as control. Results: Our results revealed that the proximate, anti-nutritive factors and amino acid profile were significantly (P 0.05) affected, there was delayed germination and survival percentage became zero percent on exposure to 400Gy and above. “Olaudi” variety was less affected by the gamma rays exposure going by the result of the days to seedling emergence and percentage survival, making pigeon pea species more sensitive to the irradiation. Conclusion: Taking the results together, it does importantly suggest, however, that lower doses of gamma irradiation might be preferred for achieving the dual purpose of improvement and preservation but high enough to reduce the anti-nutritional factors.

Gelam honey acting as a radioprotectant agent in gamma-irradiated human diploid fibroblasts

In this study, the effect of Gelam honey against radiation-induced DNA damage and cell survival rate of human diploid fibroblasts (HDFs) was evaluated. The degree of damaged DNA was determined by Comet assay while Clonogenic assay was used to evaluate cell survival rate. Irradiated Gelam honey at the concentration of 6 mg/ml was used to treat HDFs pre-, during- and post-exposure to 1 Gy of gamma-rays to evaluate its radioprotectant properties. Comet assay showed that exposure to gamma-rays caused a significant increase in total DNA damage in a dose dependent manner (p<0.05). Pre-treatment with Gelam honey at 6 mg/ml decreased the degree of damaged DNA significantly (p<0.05) which was not observed when Gelam honey treatment was given during- and post-irradiation. Clonogenic assay showed the percentage of survival fraction of HDFs decreased significantly with increasing dose of gamma-rays exposure (p<0.05). Cell survival rate however was significantly increased when HDFs were treated with Gelam honey pre- and during-irradiation. These findings indicated that pre-treatment with Gelam honey protected against radiation-induced DNA damage and enhanced cell survival rate. In conclusion, Gelam honey may acts as a radioprotectant agent in gamma-irradiated human diploid fibroblasts. Key words: Gelam honey, radioprotectant, human diploid fibroblasts (HDFs), DNA damage, cells survival.

Gamma ray effects on flash memory cell arrays

Information stored in flash memories is physically represented by the absence or presence of charge on electrically isolated floating gates. Interaction of gamma rays with the insulators surrounding the floating gate produces effects that degrade the properties of memory cells, possibly leading to the corruption of the stored content. The cumulative nature of these effects is expressed through the total ionizing dose deposited by the gamma rays in the insulators surrounding the floating gate. Relying on both theory and experiment, we examine how the properties of cells in commercially available flash memories affect their sensitivity to gamma rays. Memory samples from several manufacturers, currently available on the market, can be compared with respect to data retention under gamma ray exposure.

A Comprehensive Study on Energy Absorption and Exposure Buildup Factors for some Soils and Ceramic Materials

Study of gamma ray energy absorption (EABF) and exposure buildup factors (EBF) for some essential soils, ceramic materials in the energy region 0.015-15 MeV up to a penetration depth of 40 mfp (mean free path). To calculate both EABF and EBF, five parameter geometric progressions (G-P) fitting approximation has been used. Variation of EABF and EBF with incident photon energy, penetration depth and effective atomic number (Zeff) has been studied and presented in the form of graphs. This change results from the dominance of different interaction process in different energy regions. Significant variations were also observed between EABF and EBF which may due to different chemical composition of given materials. Keywords: Cascade silt loam (CSL), Energy absorption buildup factor, Exposure buildup factor, Kaolinite (KLN), Mica, Sand.

Radio-protective response on the environmental pollutant induced oxidative stress

The purpose of this study was to investigate the protective effect of low dose radiation on TCE induced oxidative damage in rats. The oxidative damage of both liver and kidney was assessed by serum alkaline phosphatase (ALP), Gamma Glutamyl Trans-Peptidase (GGTP), Alanine and Aspartate Amino Transferase (ALT & AST) activities in addition concentrations of cholesterol, high density lipoprotein-cholesterol (HDL-c), low density lipoprotein-cholesterol (LDL-c), Triacyglycerols (TGs), urea and creatinine were analyzed. Liver lipid peroxidation (MDA), Nitric Oxide (NO), reduced glutathione (GSH) levels, and activities of both Super-Oxide Dismutase (SOD) and Glutathione Peroxidase (GSH-Px) were measured. Results: TCE administration increase serum ALP, GGTP, ALT, AST activities, cholesterol, triacylglycerols, LDL-c, urea and creatinine concentrations, besides liver MDA and NO, whereas it decreased SOD, GSH-Px activities, GSH level in liver, HDL-c in serum. Low dose of gamma rays (0.5 Gy) exposure significantly improved lipid peroxidation and oxidative injury induced by TCE. Conclusion: The study indicates that treatment with low dose of gamma rays ameliorate harmful effects induced by TCE taking in consideration the effect of gamma radiation as a stimulant of radical detoxification.

Radon, gamma-ray exposure and natural radionuclides

Abstract Measurements were conducted to determine residential radon exposure levels in provinces with high lung cancer incidence in three different regions of Thailand. The measurements revealed that the average indoor radon levels were 20.0, 24.4, and 13.1 Bq m−3, and that the average gamma dose rates were 145, 164, and 54 nSv h−1 in Chiangmai, Songkhla and Khonkaen provinces, respectively. The spectroscopic analysis of soil samples collected from the three provinces showed that the highest contents of Ra-226, Th-232, and K-40 were present in Songkhla, with values of 93.7, 71.9, and 786.9 Bq kg−1, respectively, and the lowest contents were present in Khonkaen, with values of 15.6, 19.0, and 46.8 Bq kg−1, respectively. The results of our analysis of the activity concentrations of naturally occurring radionuclides helped explain the lower levels of radon gas and gamma-ray exposure in Khonkaen.