Effect Of Γ-irradiation Research Articles

Investigation of infrared spectra of γ-irradiated polymer composite material

The effect of γ-irradiation on a polymer composite material based on low-molecular-weight polydiene-epoxy-ether-urethane and divinyl synthetic rubbers is investigated. Irradiation doses of 5 and 10 Mrad are shown to have almost no effect on the material, as evidenced by the characteristic spectral bands in the infrared region. Based on experimental data, a significant change is observed at an irradiation dose of 15 Mrad that induces a partial disruption of the −CH2−CH2− bonds and an increase in the number of N–H, –C=, C–, and C–O–C bonds. The irradiation dose of 15 Mrad is assumed to cause a partial disruption of some bonds and the formation of others, which affects the mechanical properties of this polymer composite material.

Effect of initial γ-irradiation on infrared laser ablation of poly(vinyl alcohol) studied by infrared spectroscopy

The effect of initial γ-irradiation of poly(vinyl alcohol) (PVA) on the kinetics of polymer ablation under CO2 laser irradiation was studied using infra-red spectroscopy. The rate of laser ablation rapidly decreases with increasing time of laser ablation up to 10 s. Initial γ-irradiation of a dose up to 100 kGy reduces the rate of the laser ablation, just like the effect of laser exposure. The number of OH and CH groups decrease in PVA both with laser irradiation and with γ-irradiation. The number of OH groups decreases more under laser irradiation. Unsaturated bonds are formed in γ–irradiated PVA on the surface of the crater formed by laser ablation of the polymer that has undergone radiolysis. Increasing the dose of initial γ-irradiation from 100 to 2300 kGy leads to an increase in the intensity of the IR bands of the unsaturated bonds. The number of IR bands in the spectra of the laser ablation crater of PVA does not change with the dose of initial γ-irradiation. A dose of radiolysis of 3500 kGy significantly changes the IR spectra of both the ablation crater and the coating formed from the ablation products. Many bands characteristic for PVA are no longer present and the intensities of bands corresponding to unsaturated bonds are increased. A computational model for loss of water and ketone formation was developed for PVA and PVA including a diol using G3(MP2). The highest activation energy barrier step in the decomposition reaction was formation of the enol species and water was shown to catalyze all decomposition steps.

The Role of Immunomodulator Betaleukin in Recovery of Hepatocytic Ploidy Profile in Delayed Terms after Irradiation.

We studied the radioprotective effect of betaleukin administered to (CBA×C57Bl/6)F1 mice in single doses of 50 and 3 μg/kg 2 and 22 h, respectively, prior to long-term (21 h) whole-body low-intensity (10 mGy/min) γ-radiation (137Сs; total dose 12.65 Gy). Hepatocyte ploidy, a biomarker of metabolic disorders of the liver, was evaluated, and nuclearity and ploidy indices were calculated. In 10 months after irradiation, a significant decrease in the ploidy index was revealed in the group of irradiated mice, while in animal receiving 3 or 50 μg/kg betaleukin, this parameter did not differ and even surpassed the control level, respectively. Thus, in vivo assessment of hepatocytic ploidy profile in mice revealed negative delayed effects of γ-irradiation in a dose of 12.65 Gy and a protective effect a single injection of immunomodulator betaleukin.

Effects of low-dose γ-irradiation on the structural, morphological, and optical properties of fluorine-doped tin oxide thin films

This paper presents the effects of low-dose γ-irradiation on the structural, morphological, and optical properties of Fluorine-doped tin oxide (FTO) thin films for application as a passive thermal control coating in future miniaturized lightweight spacecraft. Commercial-grade FTO films on glass substrate (Pilkington Ltd, UK) with a bulk density of 2.5 g/cm3, sheet resistance of 12 Ω.sq-1, coating thickness of 450 nm, optical band-gap of 3.80 eV, a carrier concentration of 1.50×1020 cm−3 and a mobility of 15 cm2/Vs were irradiated at room temperature and atmospheric pressure using a 60Co gamma source (with gamma energies of 1.17 MeV and 1.33 MeV) at iThemba Laboratory for Accelerator Based Sciences, Cape Town, South Africa. Each sample was exposed to γ-rays for a different span of time to achieve a series of different integrated absorbed doses of 20, 30, and 50 Gy, at a dose rate of 0.207 Gy/min. Evolution in structural properties of the films was characterized using a Bruker AXS D8 Advance XRD with Cu-Kα (λ = 1.54056 Å) scanned in the 2θ degree range of 20 – 80 degrees. Surface properties were analyzed using a VEECO Dimension 1100 AFM machine. Meanwhile, variations in optical transmittance of the films was investigated using a Cary 5000 UV-vis-NIR spectrophotometer of Varian, Inc. model internal DRA- 2500 in the wavelength range of 200 – 2500 nm. XRD results indicate an enhancement of crystallization after irradiation, slight peak shifts, and variations in crystallite sizes with increasing dose. Surface roughness decreased with increasing dose and the grain structures also seen to vary with dose. No significant variations in optical transmittance of the FTO films.

EFFECT OF GAMMA IRRADIATION ON THE CROSSLINKING PROCESS OF NITRILE- BUTADIENE RUBBER WITH TRIAZINE AND MALEIC COMPOUNDS

The effect of γ-irradiation on the crosslinking process of nitrile butadiene rubber (NBR) with the participation of 4-dichloro 6-diethylamino-simmtriazine (DChDEAST) and 2,4- dimethylphenyl maleimide (DMPhM) was investigated. The molecular structure of the binary systems NBR + DChDEAST and NBR + DMPhM was determined by Fourier spectroscopy. Fourier transform infrared spectroscopy (FTIR) was used to determine the molecular structure of binary composite systems NBR + DChDEAST and NBR + DMPhM. The relative concentration of double bonds was predicted by determining its absorption by the optical density at the maximum absorption (967, 912 and 750 cm-1 ). It was found that at radiation doses above 250 kGy, the the number of crosslinks in irradiated blends were 1.05 × 104 and 0.66 × 104 mol /cm3 , respectively. The sensitizing effects of triasine and maleic compounds in radiation-chemical processes was investigated as well. Comprehensive studies of the structure and spatial network parameter of crosslinked NBR showed that the introduction of low molecular weight triazine and maleimide compounds increase the radiation-chemical yield (Gc) and this process also affect to increase the number of crosslinked molecules (1/Mnτ) and molecular weight of elastomers in turn.

β-glucan from Oyster Mushroom (Pleurotus ostreatus) Cultivated in Himalayan Region: Effect of γ-irradiation on Structural, Thermal, Functional, Antioxidant, Antimicrobial, Antiproliferative and Immunomodulatory Properties

β-glucan from Oyster Mushroom (Pleurotus ostreatus) Cultivated in Himalayan Region: Effect of γ-irradiation on Structural, Thermal, Functional, Antioxidant, Antimicrobial, Antiproliferative and Immunomodulatory Properties

Effect of Ethylene Oxide Sterilization on Polyvinyl Alcohol Hydrogel Compared with Gamma Radiation.

This study investigated the effects of terminal sterilization of polyvinyl alcohol (PVA) biomaterials using clinically translatable techniques, specifically ethylene oxide (EtO) and gamma (γ) irradiation. While a few studies have reported the possibility of sterilizing PVA with γ-radiation, the use of EtO sterilization of PVA requires additional study. PVA solutions were chemically crosslinked with trisodium trimetaphosphate and sodium hydroxide. The three experimental groups included untreated control, EtO, and γ-irradiation, which were tested for the degree of swelling and water content, and mechanical properties such as radial compliance, longitudinal tensile, minimum bend radius, burst pressure, and suture retention strength. In addition, samples were characterized with scanning electron microscopy, differential scanning calorimetry, X-ray photoelectron spectroscopy, and water contact angle measurements. Cell attachment was assessed using the endothelial cell line EA.hy926, and the sterilized PVA cytotoxicity was studied with a live/dead stain. Platelet and fibrin accumulation was measured using an ex vivo shunt baboon model. Finally, the immune responses of PVA implants were analyzed after a 21-day subcutaneous implantation in rats and a 30-day implantation in baboon. EtO sterilization reduced the PVA graft wall thickness, its degree of swelling, and water content compared with both γ-irradiated and untreated PVA. Moreover, EtO sterilization significantly reduced the radial compliance and increased Young's modulus. EtO did not change PVA hydrophilicity, while γ-irradiation increased the water contact angle of the PVA. Consequently, endothelial cell attachment on the EtO-sterilized PVA showed similar results to the untreated PVA, while cell attachment significantly improved on the γ-irradiated PVA. When exposing the PVA grafts to circulating whole blood, fibrin accumulation of EtO-sterilized PVA was found to be significantly lower than γ-irradiated PVA. The immune responses of γ-irradiated PVA, EtO-treated PVA, and untreated PVA were compared. Implanted EtO-treated PVA showed the least MAC387 reaction. The terminal sterilization methods in this study changed PVA hydrogel properties; nevertheless, based on the characterizations performed, both sterilization methods were suitable for sterilizing PVA. We concluded that EtO can be used as an alternative method to sterilize PVA hydrogel material. Impact statement Polyvinyl alcohol (PVA) hydrogels have been used for a variety of tissue replacements, including neural, cardiac, meniscal, cartilage, muscle, pancreatic, and ocular applications. In addition, PVA can be made into a tubular shape and used as a small-diameter vascular graft. Ethylene oxide (EtO) is one of the Food and Drug Administration-approved methods for sterilization, but its effect on PVA has not been studied extensively. The outcome of this study provides the effects of EtO and γ-irradiation of PVA grafts on both the material properties and the in vivo responses, particularly for vascular applications. Knowledge of these effects may ultimately improve the success rate of PVA vascular grafts.

Effects of γ-Irradiation on Phenolic Compounds and Antioxidant Activity of Saffron (Crocus sativus L.) Petal

Saffron (Crocus sativus L.) petal is the main by-product of saffron processing, which is produced in large amounts annually. The objectives of this study were to study the antioxidant and radical-scavenging activity of saffron petal extracts. Saffron petal extract was γ-irradiated to different doses (0, 10, 20, 30, and 40 kGy). The antioxidant activity of irradiated and nonirradiated saffron petal extract was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical method. The total antioxidant activity of nonirradiated (0 kGy) and irradiated (10, 20, 30 and 40 kGy) samples of saffron petal was 20, 66, 61, 53, and 54%, respectively. The IR spectra of γ-irradiated and nonirradiated saffron petals revealewd an increase in the content of phenolic and flavonoid components of saffron petals with increasing dose up to 30 kGy. Thus, γ-irradiation allows enhancement of the antioxidant activity and content of phenolic and flavonoid components in saffron petals, with 20 kGy being an optimum dose.

Delineation of gamma irradiation (60Co) induced oxidative stress by decrypting antioxidants and biochemical responses of microalga, Chlorella sp.

The use of different radiation technologies are becoming more popular in health care (radiotherapy) and food processing. On the other hand, gamma (γ) radiation is a potential ionizing radiation that can generate huge amount of free radicals and Reactive Oxygen Species (ROS) cause a potential damage to important macromolecules in the cell. Therefore, information on biochemical components significantly need attention for their potential usefulness in counteracting gamma radiation-induced oxidative damage. Chlorella is an unicellular microalga enrich with high protein contents and other potential nutritional supplements. However, the information about the change of active biochemical attributes by the effects of gamma radiation on Chlorella is scanty. Hence, this is highly significant to assess the impacts of gamma radiation on microalga Chlorella sp. (BUACC06). The main objectives of this study is to unlock the information of the change of phytochemicals and antioxidants content in response to γ-irradiation on Chlorella sp. (BUACC06). This strain was treated with acute doses of γ-irradiation (0.01 kGy, 0.05 kGy, 0.075 kGy of 60 Co). The effect of higher dose γ-irradiation resulted in a decline in growth, total phenolic, total flavonoid, antioxidant activity, free radical scavenging and alternation of pigmentation; these could be due to the accumulation of radiation-induced ROS in the cell. Further, protein content and antioxidant enzyme activities were increased as increasing of dose and the effective dose was 0.075 kGy. It was concluded that the administration of Chlorella sp. showed radio resistance response to low dose of gamma radiation by synthesize more proteins, carotenoids, and active antioxidant compounds as radio-protective phytochemicals. This gamma radiation could be used as novel effective method to activate biosynthesis of certain bioactive compounds in algal cells to establish improved varieties of microalgae.

Effect of γ-irradiation on ruthenium-morin nanocomposite for trace detection of Ce(IV), Ce(III) and Dy(III)

The article reports on the generation of Ru-morin nanocomposites using a simple methodology in presence and in absence of γ-irradiation. The nanocomposites were characterized using several techniques including, N2 adsorption-desorption, Brunauer−Emmett−Teller (BET) method, transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, powder X-ray diffractometric (XRD) technique, dynamic light scattering (DLS) and X-ray photoelectron spectroscopic (XPS) methods. The results revealed the production of comparatively smaller sized particles with smaller pores when prepared in presence of energetic γ-irradiation. The irradiated nanocomposite was found to be an eligible candidate for analytical sensing of Ce(IV), Ce(III) and Dy(III) out of a set of different lanthanoids. The lowest values of limit of detection (LOD) out of all the pH conditions for Ce(IV), Ce(III) and Dy(III) were 0.09 μM (at pH 12), 0.08 μM (at pH 12) and 5.37 μM (at pH 2) respectively using absorption spectroscopy. The LOD of Ce(IV) at pH 7 was found to be 0.35 μM by fluorescence spectroscopic method. It is established that the sensing is a pH dependent phenomenon which enables a selective and mutually exclusive sensing of these three lanthanoids individually. The study was also extended towards two environmental samples viz., tap water and ground water with significant recovery of Ce(IV), Ce(III) and Dy(III) from tap water and Ce(IV) and Dy(III) from ground water.

Effect of γ-Irradiation on the Gel-Forming Capability of a Crosslinked Acrylic Polymer

The effect of γ-radiation on the gel-forming capability of a Carbomer 140 crosslinked acrylic polymer has been investigated. It has been found that an increase in the radiation dose led to a decrease in the gel-forming capability. Based on IR-spectroscopic data and the results of rheological studies, it has been shown that irradiation of the polymer causes its partial degradation, leading to a decrease in the viscosity of gels and the impossibility of their formation at high radiation doses. Formulations of antibacterial gel compositions have been developed using a radiation-modified Carbomer.

Changes in the Activity of Genes Involved in the Regulation of Hematopoiesis during Tumorigenesis in Irradiated Mice.

We used 183 F1 CBA×C57Bl hybrid mice to study the delayed effects of low-power long-term γ-irradiation at a dose of 12.6 Gy (10 mGy/min) 8 and 10 months after the treatment. Eight months after the treatment we found the increased expression of the transcription factor NFκB and its target genes iNOS and G-SCF in the bone marrow (BM). Ten months after the treatment malignant lymphomas were revealed in 14 of 94 mice in the liver, abdominal cavity, and subcutaneously. In the BM of these mice, the transcription of the PTEN, NFκB, and iNOS genes was inhibited and the contents of long non-coding RNAs (lncRNAs) lnc p21, NEAT1, and microRNA miR-125b were decreased. The expression of the NFκB(p65) gene and miR-125b was inhibited in the BM of irradiated mice without tumors ten months after the treatment. These data show the deregulation of the P53 system supporting the genome stability in the BM of irradiated mice. These indices will be studied as potential markers of risk of development of irradiation-induced tumors.

Post-γ -irradiation effects on structural, optical and morphological properties of chemical vapour deposited MWCNTs

In this work, the effect of γ-irradiation with 1.25 MeV average energy (Co-60) was studied on the structural, optical and morphological properties of chemical vapour deposited MWCNTs at 10–60 kGy dose. The XRD spectra with the peak at 2θ ~ 26.08° of (002) plane confirm the MWCNTs formation and conspicuous modifications were observed after γ- irradiation. The UV–Vis studies show that the UV lower wavelength shifts towards the higher region with increasing γ- dose, bandgap decreasing from 3.57 eV to 3.33 eV (372 nm–347 nm) because of the generation of charge trapping of the radiolytic holes or electrons, which change the valence and conduction bandgap in electronic states. The FTIR results provided confirmation of the attachment of hydroxyl and carboxyl functional groups to the MWCNTs sidewalls whereas after γ- irradiation caused significant changes in the structure of the sidewalls of MWCNTs. The Raman spectra confirmed the ID/IG ratio decreases after γ- irradiation which is due to the enhancement in defects through the interaction between MWCNTs and photons during γ-irradiation. The TEM and FESEM results confirmed the inter-mingling or agglomeration of the network of nanotubes having varying diameters of about 40–60 nm on account of the interaction of γ-ray. SAED pattern shows a dispense halo pattern due to the presence of amorphous carbon.

Endoreduplication in Drosophila melanogaster progeny after exposure to acute γ-irradiation.

The purpose of this investigation was to study the effect of acute γ-irradiation of parent adults on the endoreduplication of giant chromosomes in F1 generation of Drosophila melanogaster Meig. A wild-type Oregon-R strain was used as the material. Virgin females and males of Drosophila adults at the age of 3days were irradiated with doses of 8, 16 and 25Gy. Giant chromosomes were studied by cytomorphometry on squashed preparations of Drosophila salivary glands stained with acetoorsein. The preparations were obtained at late third instar larvae. The mean values of the polyteny degree of chromosomes (PDC) in males increased after 8Gy by 10.6%, after 25Gy by 7.4%, and did not change after the dose of 16Gy. In females, the PDC did not differ from the control irrespective of the irradiation dose. An increase in endoreduplication was also evidenced by the accelerated development of offsprings of both sexes after irradiation of parents with 25Gy, and in males also at a dose of 16Gy. The statistical impact of power of radiation on polyteny was 26.8%, while the impact of sex was 4.9%. The impact of power of radiation on the developmental rate of offspring was 4.4% in males and 7.5% in females. The enhancement of endoreduplication is considered as a consequence of increasing selection pressure after irradiation. The possible involvement of epigenetic effects in the effect of ionizing radiation on endoreduplication is discussed.

Study of the Radiosensitizing and Radioprotective Efficacy of Bromelain (a Pineapple Extract): In Vitro and In Vivo

This study hypothesizes that, bromelain (BL) acts as radiosensitizer of tumor cells and that it protects normal cells from radiation effects. In vitro and in vivo studies have been carried out to prove that assumption. In vitro MTT cell proliferation assay has shown that the irradiated Ehrlich ascites carcinoma (EAC) cell line could be sensitized by BL pretreatment. In vivo: animals were randomly divided into 5 groups, Group 1: control (PBS i.p for 10 days), Group 2: Ehrlich solid tumor (EST) bearing mice, Group 3: EST + γ-radiation (fractionated dose, 1 Gy × 5), Group 4: EST + BL (6 mg/kg, i.p), daily for 10 days, Group 5: EST + BL for 10 days followed by γ-irradiation (1 Gy × 5). The size and weight of tumors in gamma-irradiated EST bearing mice treated with BL decreased significantly with a significant amelioration in the histopathological examination. Besides, BL mitigated the effect of γ-irradiation on the liver relative gene expression of poly ADP ribose polymerase-1 (PARP1), nuclear factor kappa activated B cells (NF-κB), and peroxisome proliferator-activated receptor α (PPAR-α), and it restored liver function via amelioration of paraoxonase1 (PON1) activity, reactive oxygen species (ROS) content, lipid peroxidation (LPO) and serum aspartate transaminase (AST), alanine transaminase (ALT), and albumin (ALB). It is concluded that BL can be considered as a radio-sensitizer and radio-protector, suggesting a possible role in reducing radiation exposure dose during radiotherapy.

γ-Irradiation effects in borosilicate glass studied by EPR and UV–Vis spectroscopies

Assessing the behavior of borosilicate glass used for nuclear waste immobilization under irradiation is essential for determining the long-term behavior of the high-level waste. In this work, the γ irradiation induced structural properties of the borosilicate glass have been studied via ultraviolet–visible (UV–Vis) spectroscopy and electron paramagnetic resonance (EPR) spectroscopy. The optical band gap (Eg) and the Urbach energy (Eu) deduced from the UV–Vis spectra of borosilicate glasses. The Eg decreased and the Eu increased with the increase of absorbed dose, which indicated the increase of non-bridging oxygen and disorder in the glass network. The EPR results revealed that there formed the following paramagnetic defects: hole center associated with boron (BOHC), hole centers near alkaline ions (HC1 center), E′ centers (Si), peroxy radical (Oxy defect), non-bridging oxygen hole centers (NBOHC), BO3− center, Si − BOHC (BOSi) and B–O–B–iso center (HOHOBOH-O·-BOHOH).

Influence of [formula omitted]-irradiation and ultrasound treatment on current mechanism in Au-SiO2-Si structure

The effect of 60Co γ-irradiation (5·107 rad) and ultrasound treatment (4 MHz, 2 W/cm2, up to 60 min) on current-voltage characteristics is experimentally investigated in an Au-SiO2-Si structure. The change in the current mechanism is analysed in terms of a modifying defect system. The irradiation is shown to enhance the space charge limited current and trap-assisted tunneling current. Experimental observations of the acoustically induced low temperature annealing of the Pb and E′ centers, which causes the partial recovery of irradiated silicon MOS structure characteristics, are highlighted.

Nano-ZrO2 filled high-density polyethylene composites: Structure, thermal properties, and the influence γ-irradiation

High-density polyethylene (HDPE) composites with different amounts of ZrO2 nanoparticles (1–20 vol%) were prepared by high-pressure thermal pressing. The effect of γ-irradiation on their structural and thermal properties was investigated using small-angle neutron scattering (SANS), X-ray diffraction (XRD), Raman spectroscopy, infrared spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). SANS analysis confirmed good dispersion of the nanoparticles in HDPE matrix. Upon exposure to γ-radiation only small changes in the lattice parameters and the crystalinity degree occurred for both HDPE and the nanocomposities. More significant changes for irradiated HDPE were observed in DSC-derived parameters, including the decrease in the melting point, and increase in crystalinity degree. This trend was even more pronounced for the nanocomposities. A possible explanation assuming resonant enchantment of polymer chain scission in the presence of ZrO2 nanoparticles is discussed. The extent of radiation-induced oxidation was essentially the same for pure HDPE and the nanocomposities, suggesting that the process is diffusion controlled. The thermal stability of the irradiated composites was somehow higher than that pure HDPE.

Effect of Gamma Irradiation on Conductivity of Cd1 – xFexTe

The effect of γ-irradiation at the dose Dγ = 605.6 kGy on the temperature dependences of conductivity and dielectric permittivity of Cd1 – xFexTe semimagnetic semiconductors were investigated. The character of the e(T) dependences of the irradiated Cd1 – xFexTe changes: there is a drop in the curves in the temperature range of 300–400 K at measurement frequencies 10 kHz–1 MHz, and e increases by 20 times. In the σ(T) dependence, at all measurement frequencies a maximum appears at a temperature of 400 K and conductivity increases by 40 times. We assume that the character of the temperature dependences of dielectric permittivity and conductivity corresponds to the ionic conductivity.

Antioxidant activity assisted by modified particle surface in POSS/EPDM hybrids

The presented results prove the stabilization activity of modified POSS particles in the thermal and radiochemical degrading EPDM. Various mono- or di-substituents (-CH3, -OCH3, -F, -Cl) assist the delay of oxidative degradation by the electronic interactions of free radicals inside the free volume of polyhedral oligomeric silsequioxanes (POSS) with substituents placed on the outer particle surface. The stabilization of EPDM/modified POSS patterns is characterized by chemiluminescence, FTIR spectroscopy and thermogravimetric analysis. The concern of each formulation is individually defined by the accumulation of oxygen-containing configurations, which depicts the degree of conversion for free radicals into degradation products. The efficiency ranks of substituents based on the surface effects are conclusive in respect with POSS molecular compositions. The performance of protection against oxidation is evident on the high temperature range and the advanced exposure to the action of γ-radiation. Meanwhile the damaging effect of γ-irradiation on the inorganic phase is characterized by XRD and SEM assays.