Effect Of 60Co Irradiation Research Articles

Effect of 60Co Irradiation on Boehmite Dissolution in Caustic Solutions.

Here, we examine how radiation impacts the dissolution behavior of boehmite by subjecting dry nanoparticles of different sizes to 60Co γ radiation and subsequently analyzing their dissolution behavior in caustic solutions as a function of temperature. The measured kinetics show that irradiation with an amount 228.24 Mrad significantly slows the dissolution rate, particularly for smaller sizes at lower temperatures. Specifically, the temperature-dependent dissolution rates of irradiated 20 nm boehmite versus pristine material in 3 M NaOH solutions were several times lower (e.g., rate constant of 0.026 vs 0.075 h-1 at 60 °C), with an apparent activation energy 40 kJ mol-1 higher. Although various imaging techniques and X-ray diffraction measurements consistently revealed no obvious differences between pristine and irradiated samples, after irradiation significant binding energy shifts were detected in the X-ray photoelectron Spectroscopy peaks of Al 2p and O 1s, and a change in their relative intensities indicated a lower O/Al ratio. This suggests that γ-irradiation may stabilize boehmite particle surfaces by driving their chemistry and structure toward more stable aluminum oxide forms. This finding may help explain slower dissolution rates of boehmite in nuclear waste and may be useful for the development of more robust predictive models and effective strategies for waste processing.

Effects of 60Co-irradiation and superfine grinding wall disruption pretreatment on phenolic compounds in pine (Pinus yunnanensis) pollen and its antioxidant and α-glucosidase-inhibiting activities

Effects of 60Co-irradiation and superfine grinding wall disruption on the phenolic, antioxidant activity, and α-glucosidase-inhibiting potential of pine pollen were investigated. Eight soluble phenolics (SP) and insoluble-bound phenolic (IBP) compounds were characterized for the first time. After 60Co-irradiation, total phenolic content (TPC) and total flavonoid content (TFC) in SP increased by 16.90% and 14.66%, respectively; in IBP, they decreased by 53.26% and 21.57%, respectively; whereas they were unchanged in pine pollen, but antioxidant activity decreased by 29.18%–40.90%. After superfine grinding wall disruption, the TPC and TFC in IBP increased by 80.24% and 27.24%, respectively; in pine pollen, they increased by 22.66% and 10.61%, respectively; whereas they were unchanged in SP; and their antioxidant activity increased by 46.68%–58.06%. Both pretreatments had a little effect on the α-glucosidase-inhibiting activities of pine pollen. These results would be helpful in promoting the application of pine pollen in functional food.

Studies on damage of starches in irradiated wheat and white pepper using Rapid Visco-Analyser (RVA)

Effect of 60Co irradiation on wheat and white pepper grains were investigated in this study using Rapid Visco Analyser (RVA), near infrared reflectance spectroscopy and differential scanning calorimetry. Functional properties of wheat and white pepper were affected by irradiation indicated by a decrease in viscosity values. It was caused by changes of starch structure confirmed by the NIR spectra changes between wavelength 1560–1620 nm, which is the vibration of intermolecular hydrogen bonded OH groups in polysaccharides. The radiation used did not cause significant changes in the thermal properties. RVA proved to be useful for screening radiation induced changes in dry commodities of considerable large starch content on the basis of their rheological behaviour.

Tritium Measurement in High Gamma-Ray Radiation Fields by Using an Imaging Plate

An imaging plate (IP) was applied to measure tritium in high 60Co gamma-ray radiation fields. The IP made of europium-doped BaFBr(I), a photostimulated luminescence (PSL) material, is a two-dimensional radiation sensor. The PSL response of the IP has a peak at 20-50 keV and steeply decreases towards higher energy, falling by one hundredth at around 1 MeV. By utilizing a large difference in the PSL response to photon energy between 60Co (1.173 and 1.333 MeV) and tritium (maximum energy of 18.6 keV), the bremsstrahlung X-ray induced by tritium beta ray was detected in mixed radiation fields with tritium and 60Co, varying 60Co dose rate in the range 0.0013 to 9.22 μGy/min. It was found that the effect of 60Co irradiation to PSL value, obtained by irradiated with tritium of 12.5 MBq, was negligible by dose rate of 4.38 μGy/min and there was only 7.0% difference of PSL value, obtained by irradiated with tritium of 100 MBq, between dose rate of 0.0013 and 9.22 μGy/min. The IP tritium measurement method can be a promising candidate to measure tritium in high gamma-ray radiation fields.

Effect of 60Co irradiation on drying characteristics of apple

Few studies on the irradiation effects on dehydration characteristics and quality of dried-product ha ve been reported in the past three decades. This study focuses on drying characteristics of bio-products by hot-air after they are pretreated by gamma irradiation. Experiments were made to study the influence of different irradiation dose, air temperature, slice thickness of apple on the dehydration rate, and appearance quality ( L-values), vitamin C content, and the rehydration ratio of dried apple. A conclusion is reached that the three factors of irradiation dose, hot-air temperature, and initial slice thickness significantly affected the four indices of appearance quality ( L-values), vitamin C content, dehydration rate and rehydration ratio.

Colour centres induced by γ irradiation in scintillating glassy matrices for middle and low energy physics experiments

The effect of 60Co irradiation (1–250 Gy) on the optical properties of selected phosphate and silicate-based scintillating glasses was investigated by transmission measurements performed at room temperature in the UV–Visible part of the spectra. Samples doped with rare-earth ions (Ce 3+, Tb 3+ as emission centres, and Gd 3+ as an additional constituent in certain compositions) have been studied. The results are discussed taking into account the possible influence of different glass compositions on radiation induced colour centres.

RADIOLYTIC STABILITY OF SOME RECENTLY DEVELOPED ION EXCHANGE AND EXTRACTION CHROMATOGRAPHIC RESINS CONTAINING DIPHOSPHONIC ACID GROUPS*

ABSTRACT The effect of 60Co irradiation on the Diphonix™, Diphosil and Diphonix-CS chelating ion exchange resins, and on two Dipex™ extraction chromatographic resins containing the P,P’-di(2-ethylhexyl) methanediphosphonic acid (H2DEH[MDP]) impregnated in the pores of a polymeric support (Dipex-1) and of silica (Dipex-2), respectively, has been investigated. The resins have been irradiated while in contact with HNO3 (Diphonix, Diphosil and Dipex resins) or NaOH (Diphonix-CS resin) up to an absorbed dose of about 200 Mrad. As a probe of the resin radiolytic degradation, metal uptake (both equilibrium and kinetics) and capacity measurements have been performed. Our results show that the Diphonix-CS resin properties are practically unaffected by irradiation under the experimental conditions used in this work. The Diphonix, Diphosil, and especially the Dipex resins suffer substantial capacity losses, but their affinity for actinide ions is not seriously compromised. On the other hand, the kinetics of metal uptake by the silica based Diphosil and Dipex-2 resins becomes substantially slower indicating that, from a radiolytic degradation standpoint, polymeric materials perform better than silica as supports for H2DEH[MDP] containing extraction chromatographic resins.

Toxoplasma gondii: experimental infection in cats vaccinated with 60Co-irradiated tachyzoites

The effects of 60Co-irradiation on the viability and immunogenicity of RH and Beverly strains of oxoplasma gondii was examined. While 60Co-irradiated tachyzoites retained invasive activity in mouse embryonal cells and sustained antigenicity in mouse peritoneal macrophages, the parasites did not develop in host cells. Vaccination of mice with 60Co-irradiated tachyzoites of either RH or Beverley strains induced resistance to challenge with a highly virulent strain (RH strain). Vaccination of kittens with 60-Co-irradiated tachyzoites of the Beverly strain partially prevented oocyst shedding when challenged with cysts (bradyzoites) from the Beverley strain. But kittens vaccinated with 60Co-irradiated or fixed tachyzoites of the RH strain shed oocysts when challenged with cysts (bradyzoites) from the Beverley strain. These results suggest that the development of protective immunity in feline toxoplasmosis seems to be strain and/or stage-specific.

Effect of 60Co irradiation and Fowler-Nordheim injection on MOS capacitors with thin plasma nitrided gate oxides

We have investigated the generation of interface traps during 60Co irradiation and Fowler-Nordheim (FN) injection in MOS structures with thin plasma nitrided gate oxides. By using deep level transient spectroscopy and capacitance-voltage measurements, we have studied the impact of nitridation time on the creation of fast and slow states in the silicon bandgap. After FN injection, electrical relaxation of the interface has been interpreted as the superposition of two mechanisms: an irreversible physico-chemical time-dependent transformation and a reversible bias-dependent neutralization.

Effect of 60Co Irradiation on Nerve Regeneration in Heterograft Nerve

The heterograft nerve might fail due to immunologic rejection, so there were few studies about heterografting to repair peripheral nerve injury. Previous studies showed that regeneration nerve fibers could grow into the heterograft nerve when heterogenic graft nerves were treated by freezing and thawing. This suggested that for successful nerve grafting, the antigenicity of the nerve graft must be reduced or

Action of radiation or alkylating agents on LSA lymphoma during growth

The effect of 60Co irradiation and the alkylating agents mustargen, cyclophosphamide, and bis-2-chloroethyl-1-nitrosourea (BCNU) was investigated on the LSA ascites tumor. Single exposures of radiation or alkylating agent was given at different stages of tumor growth. This tumor system was shown to have markedly changing tumor cell age cohort compositions at different tumor stages with differing 5 Fluorouracil (5-FU) sensitivities for cell killing and treatment-induced increase in host survival time, at different tumor stages. Similar variation in altering survival time also was found for the alkylating agents with all showing greater activity against the early, rapidly growing tumor. Stationary phase and advanced tumors also showed markedly different tumor response. The different agents had greatly different potencies against the advanced G1-arrested non-proliferating tumor. 60Co radiation showed much less variation in effectiveness than the alkylating agents based upon the host survival time. The mode of action of treatment-induced in vivo life prolongation by these agents is complex and tumor age dependent.

Effects of60Co Irradiation on VirulentToxoplasma Gondiiand Its Use in Experimental Immunization

The effects of 60Co irradiation on the virulence and immunogenicity of the RH strain of Toxoplasma gondii was studied by infecting batches of mice with graded inocula of tachyzoites that had been exposed to radiation doses ranging from 0 to 20 000 rad. While doses of 15 000 and 20 000 rads appeared to be effective, and 10 000 rad nearly effective in annulling the virulence, irradiation at 5000 rad was only partially effective in rendering the organisms avirulent and could achieve only a prolongation of survival time of the inoculated mice. The survivors of higher irradiation inocula showed no evidence of the development of the parasite in them, but could resist a limited virulent challenge. The use of a booster inoculation improved both the quality and the duration of protective effect.