Effect Of Γ-ray Irradiation Research Articles

THE PROPERTIES OF GAMMA IRRADIATED ELASTOMERIC NANOCOMPOSITES BASED ON CHLOROSULFONATED POLYETHYLENE

In the case of irradiation of polymeric materials, the progress in oxidative degradation depends on absorbed dose, dose rate, exposure environment, energy of irradiation, chemistry of material, and previous state of ageing. It is known that the main effect of the interactions between gamma rays and rubber macromolecules is the formation of free radicals, whose further evolution can cause crosslinking with increase in the crosslinking density or chain scission. Chlorosulfonated polyethylene is specifically recommended for sheeting of cables in nuclear energetic plants. Elastomers based on this network precursor are resistant to wear and repeated deformation and have excellent irradiation resistance. The goal of the current work was to study the effects of γ-ray radiation for elastomers based on chlorosulfonated polyethylene in combination with nitrile rubber. The reinforcing filler was nano-silica. The irradiation was performed in the Co60 radiation sterilization unit. The level of ageing was evaluated using the hardness and swelling measurement. The use of silica nano-particles improved the swelling resistance in toluene after irradiation ageing.

Flame-retardant EPDM compounds containing phenanthrene to enhance radiation resistance

Ethylene propylene diene monomer (EPDM) compounds with good flame-retardant and γ-ray radiation resistant properties were prepared by adding complex flame retardants and phenathrene. The resultant EPDM formulations have a long time to ignition (TTI >46s), a low peak heat release rate (PHRR~341kW/m2) and a high limited oxygen index (LOI >30). Effects of γ-ray radiation on the resultant flame-retardant EPDM was investigated. The formulated EPDM is a crosslinking dominated polymer under γ-ray radiation. The γ-ray radiation resistant property of EPDM was enhanced by adding phenanthrene. Elongation at break of EPDM formulated with phenanthrene could retain 91% after being irradiated to 0.3MGy and still retains 40% elongation even after being irradiated to 0.9MGy, which is much better the control. It is expected that the formulated flame-retardant and radiation resistant EPDM materials could meet the requirements for use in radiation environments.

Investigations on the effect of gamma-ray irradiation on the gas sensing properties of SnO2 nanoparticles

In recent years, SnO2 nanoparticles (NPs) have been subjected to various modifications in order to improve their performance in sensing and other applications. Here, we report the synthesis of SnO2 NPs by microwave irradiation, and subsequent exposure to gamma (γ) radiation at different doses (0–150 kGy) to induce desirable physico-chemical properties. The irradiated samples were characterized by x-ray powder diffraction (XRD), transmission electron microscopy (TEM and HR-TEM), and photoluminescence (PL) to evaluate the effect of γ-ray irradiation on their morphology and microstructure. The results revealed that the bulk crystal structure remained unchanged after irradiation, while the existence of defects and a damaged over-layer have been confirmed by PL and HR-TEM respectively. The influence of γ-irradiation on the electrical and CO sensing characteristics was also investigated in the temperature range between 150 and 400 °C. γ-irradiated SnO2 NP based resistive sensors showed better CO sensing characteristics (i.e. higher response and lower working temperature) compared to non-irradiated SnO2. Upon optimizing the γ-ray dose irradiation level and working temperature, a ten-fold enhancement in the response to CO has been achieved (R/R0 = 12 to 50 ppm of CO in air) in 50 kGy irradiated SnO2 NP based sensors operating at 150 °C. A possible mechanism for the enhanced sensing performance of γ-irradiated SnO2 NPs has been proposed.

Effect of γ-rays irradiation on the structural, magnetic, and electrical properties of Mg–Cu–Zn and Ni–Cu–Zn ferrites

Nanoparticles of Ni0.35Cu0.15Zn0.5Fe2O4 and Mg0.35Cu0.15Zn0.5Fe2O4, have been synthesized by citrate precursor method. Then some of the prepared samples have been irradiated by γ-rays of 60Co radioactive source at room temperature with doses of 1Mrad and 2Mrad, at a dose rate of 0.1Mrad/h to study the effect of γ-rays irradiation on some structural, magnetic and electrical properties of the samples. The X-ray diffraction analysis (XRD), transmission electron microscopy, Fourier transform infrared spectroscopy and vibrating sample magnetometer measurements have been used to investigate the samples. The XRD results show that the irradiation has caused a decrease in the crystallite size and the measured density and an increase in the porosity, specific surface area, and microstrain in the case of Ni–Cu–Zn ferrite whereas in the case of Mg–Cu–Zn ferrite the reverse trend has been noticed. The lattice constant of the investigated samples has been increased with the increase of irradiation due to the conversion of Fe3+ (0.67Å) to Fe2+ (0.76Å). The magnetization results show an increase in saturation and remnant magnetizations for the two prepared ferrites after γ-rays irradiation. The main reason of this behavior is most probably due to the redistribution of the cations between A and B sites. The cation distribution has been proposed such that the values of theoretical and experimental magnetic moment are identical and increase as the magnetization increases. Moreover, a theoretical estimation of the lattice constant has been calculated on the basis of the proposed cation distribution for each sample and compared with the corresponding experimental values obtained by XRD analysis; where they have been found in a good agreement with each other. This can be considered as another confirmation of the validity of the cation distribution. Moreover, the cation distribution is thought to play an important role in increasing the values of dc conductivity of all samples with increasing the irradiation dose. The frequency dependence of ac conductivity, dielectric constant and dielectric loss of all samples have been studied. The Cole–Cole plots of (Z″ vs. Z′) give different two overlapping incomplete semi-circles depending upon the electrical parameters. Also, The Cole–Cole plots of (M″ vs. M′) insure that the electric stiffness is the dominant property of the investigated samples.

The effect of γ-ray irradiation on the adsorption properties and chemical stability of AMP/SiO2 towards Cs(I) in HNO3 solution

Silica based ammonium molybdophosphate (AMP/SiO2) adsorbent was used to remove Cs(I) from HNO3 solution. The adsorbent with different absorbed dose (0–300 kGy) was characteristed by X-ray power diffraction. The adsorption data against different γ-ray absorbed doses were analyzed by the Langmuir isotherm. The adsorption capacity decreased slightly from 23.22 to 22.37 mg/g with the increase of the absorbed dose. The breakthrough properties of Cs(I) were conducted using column packed with AMP/SiO2 before and after irradiation. The chemical stability of AMP/SiO2 at 300 kGy absorbed dose in 3 mol/L (M) HNO3 was excellent.

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

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

Effects of γ-Ray Irradiation on the Properties of Nano-Hydroxyapatite/Polyurethane Composite Porous Scaffolds

To well understand the influence of the sterilization on the properties of biomaterials prior to application is pivotal. The effect of γ-ray irradiation on the mechanical and thermal properties of nanohydroxyapatite/polyurethane (n-HA/PU) porous scaffold for bone tissue engineering was studied in this paper. The mechanical testing, fourier transform infrared spectroscopy and thermal analysis were employed to determine the structure and properties change of these composite scaffolds after γ-ray irradiation with different doses.The results show that thermal stability, and mechanical properties of the composite scaffolds increase after γ-ray irradiation with doses of15 kGy to 25 kGy, especially the irradiation dose of 15kGy which imposed a remarkable effect on these properties. However, a reverse trend is found when the 50kGy irradiation dose was applied.In general, it can be concluded that sterilization using γ-ray irradiation with proper dose has no adverse effect on the properties of n-HA/PU composite scaffolds.

Optical and positron annihilation spectroscopic studies on PMMA polymer doped by rhodamine B/chloranilic acid charge transfer complex: Special relevance to the effect of γ-ray irradiation

Polymeric sheets of poly (methylmethaclyerate) (PMMA) containing charge transfer (CT) complex of rhodamine B/chloranilic acid (Rho B/CHA) were synthesized in methanol solvent at room temperature. The systematic analysis done on the Rho B and its CT complex in the form of powder or polymeric sheets confirmed their structure and thermal stability. The IR spectra interpreted the charge transfer mode of interaction between the CHA central positions and the terminal carboxylic group. The polymer sheets were irradiated with 70kGy of γ radiation using 60Co source to study the enhanced changes in the structure and optical parameters. The microstructure changes of the PMMA sheets caused by γ-ray irradiation were analyzed using positron annihilation lifetime (PAL) and positron annihilation Doppler broadening (PADB) techniques. The positron life time components (τi) and their corresponding intensities (Ii) as well as PADB line–shape parameters (S and W) were found to be highly sensitive to the enhanced disorder occurred in the organic chains of the polymeric sheets due to γ-irradiation.

Effect of γ-ray irradiation on the optical property and laser damage performance of silica

High purity fused silica samples have been irradiated by 60Co γ-ray at the doses of 50, 500 and 5000kGy, and the effect of γ-ray irradiation on the optical property and laser damage performance of silica have been investigated. After γ-ray irradiation, there is no obvious change on the surface of silica observed. However, the surface roughness increases slightly with increasing γ-ray irradiation dose. When the irradiation dose reached 500kGy and above, a broad absorption band at 215nm, ascribed to E′ color center, is significantly observed and its intensity increases greatly with increasing dose. After laser irradiation, the distribution of laser induced damage threshold (LIDT) is related to γ-ray dose, and the LIDT decreases monotonously with increasing dose. A mechanism for the degradation of laser damage resistance is presented.

Effects of γ-ray radiation on two-dimensional molybdenum disulfide (MoS2) nanomechanical resonators

We report on experimental investigation and analysis of γ-ray radiation effects on two-dimensional molybdenum disulfide (MoS2) drumhead nanomechanical resonators vibrating at megahertz frequencies. Given calibrated dosages of γ-ray radiation of ∼5000 photons with energy at 662 keV, upon exposure over 24 or 12 h, all the MoS2 resonators exhibit ∼0.5–2.1% resonance frequency upshifts due to the ionizing γ-ray induced charges and their interactions. The devices show γ-ray photon responsivity of ∼30–82 Hz/photon, with an intrinsic γ-ray sensitivity (limit of detection) estimated to approach ∼0.02–0.05 photon. After exposure expires, resonance frequencies return to an ordinary tendency where the frequency variations are dominated by long-term drift. These γ-ray radiation induced frequency shifts are distinctive from those due to pressure variation or surface adsorption mechanisms. The measurements and analyses show that MoS2 resonators are robust yet sensitive to very low dosage γ-ray, demonstrating a potential for ultrasensitive detection and early alarm of radiation in the very low dosage regime.

Effects of 60Co γ-ray irradiation on microstructure and ferroelectric properties of Bi3.25La0.75Ti3O12 thin films

Bi3.25La0.75Ti3O12 (BLT) thin films were deposited on Pt/Ti/SiO2/Si substrates through sol–gel method. Films underwent 60Co γ-ray irradiation with different doses; 0, 50, 100 and 150kGy, respectively. Impacts of γ-ray on the microstructure, ferroelectric properties, leakage current density and fatigue characteristic were studied in detail. The results of SEM images show that grain patterns become irregular. Remnant polarization (2Pr) and coercive field (2Ec) decrease with irradiation dose increase. C–V curves reveal obvious asymmetry along y-axis. The irradiated thin films display lower leakage current density and fatigue endurance up to more than 1010 switching cycles. These results suggest that radiation can improve the film performance in some areas.

Effect of γ-ray irradiation on the microstructure and self-heating property of carbon fiber/polyethylene composite films

High-density polyethylene composite films filled with various contents of carbon fiber (CF) were manufactured by melt mixing. The electrical and self-heating properties of the composite films were investigated. The composite films containing 10wt% CF were exposed to γ-ray irradiation. The structural, morphological, and self-heating properties of the irradiated composite films were examined. The results indicated that the surface temperature (Ts) of the composite films was strongly dependent on the applied voltage and filler content. The Ts of the irradiated composite films was higher than that of the non-irradiated films, which contributed to the lower thermal expansion and the higher degree of crystallization of the irradiated composite films. In addition, the mechanical properties of the irradiated composite films were significantly improved. Using a rechargeable battery as the applied voltage source to evaluate the self-heating property of the irradiated composite films, a heating temperature of 54.2°C was achieved, which lasted for 6h.

X-ray photoelectron spectroscopy of γ-ray-irradiated single-stranded DNA

The effects of γ-ray irradiation on herring sperm single-stranded DNA have been studied by using X-ray photoelectron spectroscopy (XPS) in the view of the bonding configurations and the structural modifications. The significant changes in the hydrogen, carbon, nitrogen, and phosphorous bonding energies, as revealed by the XPS analysis, indicate that electron transfers result in the creation of radicals and in DNA strand breaks.

γ-Ray irradiation effect on GdBO3/silica:Ce3+ composite prepared by sol gel method

Abstract Samples of GdBO3 doped with Ce3+ embedded in amorphous silica matrix were obtained by sol gel process and heat-treat at 1000 °C for 2 h in argon atmosphere. After elaboration, the samples were irradiated with γ-rays using cobalt (60Co) source in the dose range from 1 to 5 kGy. The irradiation effect of γ-rays on structural and optical properties of the synthesized samples were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transforms infrared spectroscopy (FTIR) and photoluminescence spectroscopy. XRD and TEM-EDS results reveal that γ-ray irradiation reduces the crystallite size from 55 nm to 30 nm. It is found from FTIR study that the absorption bands intensity assigned to structural groups containing BO4 and BO3 units as well as the banding of Si–O–Si bond increases with γ-ray dose up to 4 kGy. While photoluminescence measurements show that the emission bands attributed to the 5 d → 4 F transition of Ce+3 ion intensity decreases, it is still significant even after irradiation to a dose of 5 kGy. From this results it is concluded that the γ-ray irradiation up to a dose of 5 kGy improve the structural and morphological quality of the synthesized GdBO3/silica: Ce3+ without altering significantly its luminescence properties.

Improvement of fish meal replacements by soybean meal and soy protein concentrate in golden pompano diet through γ-ray irradiation

A 5-week feeding trial was conducted to examine the effect of γ-ray irradiation on the inclusion of soybean meal (SBM) and soy protein concentrate (SPC) in diets of juvenile golden pompano (Trachinotus ovatus). One diet containing 320 g kg−1 fish meal served as a reference (C), and another four diets were formulated with 75% of the fish meal replaced by SBM (SM), SPC (SC), SBM irradiated with γ-ray at 30 kGy (SM30) or SPC irradiated with γ-ray at 30 kGy (SC30). The weight gain was higher in fish fed diets SM30 and SC30 than in fish fed diets SM and SC, respectively, whereas fish consumed more diet SM30 than diets SM, SC or SC30. No significant differences were found in feed conversion ratio, nitrogen retention efficiency (NRE), phosphorus retention efficiency (PRE), condition factor, hepatosomatic index (HSI), body composition, waste outputs of nitrogen (NWO) and phosphorus (PWO) either between fish fed diets SM and SM30 or between fish fed diets SC and SC30. The weight gain and PWO were higher, but the PRE and the body phosphorus content were lower in fish fed diet C than those in fish fed diets SM30 or SC30. No significant differences were found in the NRE, condition factor, HSI and body composition (i.e. moisture, crude protein, crude lipid and ash) between fish fed diets C and SM30 or between fish fed diets C and SC30. Macromolecular proteins in SBM and SPC were degraded, whereas the contents of peptides with molecular weight <6.5 kDa were increased by γ-ray irradiation. This study reveals that γ-ray irradiation can improve the performance of SBM and SPC as a fish meal substitute in the golden pompano diet.

Influence of gamma ray irradiation and annealing temperature on the optical constants and spectral dispersion parameters of metal-free and zinc tetraphenylporphyrin thin films: A comparative study

In this work, we report on the effect of γ-ray irradiation and annealing temperature on the optical properties of metal-free tetraphenylporphyrin, H2TPP, and zinc tetraphenylporphyrin, ZnTPP, thin films. Thin films of H2TPP and ZnTPP were successfully prepared by the thermal evaporation technique. The optical properties of H2TPP and ZnTPP films were investigated using spectrophotometric measurements of the transmittance and reflectance at normal incidence of light in the wavelength range from 200 to 2500nm. The absorption spectra of H2TPP showed four absorption bands, namely the Q, B, N and M bands. The effect of inserting Zn atom into the cavity of porphyrin macrocycle in ZnTPP molecule distorted the Q and B bands, reduced the width of absorption region and influenced the optical constants and dispersion parameters. In all conditions, the type of electron transition is indirect allowed transition. Anomalous dispersion is observed in the absorption region but normal dispersion occurs in the transparent region of spectra. We adopted multi-oscillator model and the single oscillator model to interpret the anomalous and normal dispersion, respectively. We have found that the annealing temperature has mostly the opposite effect of γ-ray irradiation on absorption and dispersion characteristics of these films.

Effect of γ-irradiation on rice seed vigor assessed by near-infrared spectroscopy

High-energy radiation such as γ-ray can kill pests, insects and bacteria with high efficiency and low-cost, and so it has been utilized as one of the most promising tools for food storage. On the other hand, high-energy radiation may also induce physiological, biochemical and genetic changes of crops. In this study, near-infrared (NIR) spectroscopy as a non-destructive, fast, low-cost analytical tool was employed to investigate the effect of γ-ray irradiation on the irradiated rice seeds. The alteration of seed vigor was assessed after the rice seeds were irradiated with different irradiation doses and at different storage ages. The relationship between seedling height, seed vigor and irradiation dosage was established based on the analysis of the NIR spectral data. The accuracy of the PLS (partial least squares) prediction model was checked by parameters such as the root mean square error of prediction (RESEP) and the residual prediction deviation (RPD). Our results showed that with increase of irradiation dosage and storage age, seed injury increased resulting in reduced seed vigor and seedling height. This work thus demonstrates the successful application of NIR for the rapid and non-invasive evaluation of rice seeds after irradiation and storage.

Effect of high dose γ-ray irradiation on GaAs p-i-n photodetectors

Metal organic vapor phase epitaxy grown GaAs p-i-n photodetector devices are fabricated and tested for the assessment of practical usage of the detector after the exposure to high radiation doses of γ-ray. Increased values of saturation current, ideality factor and leakage current after 360kGy γ-ray irradiation confirm a substantial increase in the number of generation–recombination centers. It is further observed that the leakage current density, current per unit volume (Jv), increases linearly with the radiation fluence (Φ). The slope (α=ΔJv/ΔΦ) of the leakage current density versus γ-ray radiation fluences curve is two order less (4–5×10−l9A/cm) for GaAs compared to Si (4–6×10−l7A/cm). The lower value of α (radiation damage constant) confirms that GaAs is radiation harder than Si. Subsequently, it is also observed that the photo response of 360kGy γ-ray irradiated GaAs device is reduced by ~50% due to the reduction of quantum efficiency by the radiation induced generation–recombination centers. The functionality of the irradiated sensor is verified by comparing the response of the pristine and irradiated detectors to the photoluminescence of semiconductor quantum well structures.

Combined reactor neutron beam and 60Co γ-ray radiation effects on CMOS APS image sensors

The combined reactor neutron beam and 60Co γ-ray radiation effects on complementary metal-oxide semiconductor (CMOS) active pixel sensors (APS) have been discussed and some new experimental phenomena are presented. The samples are manufactured in the standard 0.35-μm CMOS technology. Two samples were first exposed to 60Co γ-rays up to the total ionizing dose (TID) level of 200 krad(Si) at the dose rates of 50.0 and 0.2 rad(Si)/s, and then exposed to neutron fluence up to 1 × 1011 n/cm2 (1-MeV equivalent neutron fluence). One sample was first exposed to neutron fluence up to 1 × 1011 n/cm2 (1-MeV equivalent neutron fluence), and then exposed to 60Co γ-rays up to the TID level of 200 krad(Si) at the dose rate of 0.2 rad(Si)/s. The mean dark signal (KD), the dark signal non-uniformity (DSNU), and the noise (VN) versus the total dose and neutron fluence has been investigated. The degradation mechanisms of CMOS APS image sensors have been analyzed, especially for the interaction induced by neutron displacement damage and TID damage.

Effect of γ-ray radiation and sun exposure on transmittance of ZF6 lead glass

Effect of γ-ray radiation and sun exposure on transmittance of ZF6 lead glass