Adsorption characteristics and radiation stability of a silica-based DtBuCH18C6 adsorbent for Sr(II) separation in HNO3 medium

A silica-based adsorbent, (DtBuCH18C6 + dodecanol)/SiO₂-P, which is used for selective separation of Sr(II) from high level liquid wastes, against temperature and gama-irradiation was investigated. The adsorption characteristics of Sr(II), Ba(II), La(III), Nd(III), Gd(III) and Dy(III) under varying nitric acid concentration at different temperatures were measured by batch method. The adsorbent showed higher distribution coefficients (K _d) for Sr(II) compared to other tested metal ions, and the K _d values of Sr(II) decreased with increasing temperature. Thermodynamic parameters of the adsorption process were calculated. The related parameters in adsorption isotherm models were obtained using a non-linear fitting. Uptake capacity from 0.38 to 0.43 mmol g^?1 was obtained for Sr(II) in the temperature range of 298–323 K by the Langmuir equation fitting. The leakage of total organic carbon was below 120 ppm at 298 K and 180 ppm at 323 K, respectively. The degradation of the adsorbent irradiated in 2 M HNO₃ was investigated. It is found that the adsorbed dose of γ-ray more than 50 KGy has a strong influence on K _d of Sr(II). The K _d values of Sr(II) decrease about 3 times ranged from 50 to 500 KGy.     

Electron beam irradiated textile cellulose fibres.: ESR studies and derivatisation with glycidyl methacrylate (GMA)

Powdered samples of cotton, flax and viscose from textile fibres were subjected to electron beam irradiation (20-400 KGy). ESR signals were observed after irradiation. The intensity of the signals depended on the administered dose and exhibited an exponential decay with time. The ESR spectra, whose pattern depended drastically on the crystallinity of the samples, indicated the simultaneous presence of at least three carbon-centred radical species. When the whole irradiated textile fibres were quenched in a solution of glycidyl methacrylate (GMA) a significant increase of the weight was observed, the increase being strongly dependent on the administered dose and on the time interval elapsed between irradiation and quenching. Spectroscopic characterisation evidenced that GMA acted as cellulose radicals scavenger on the unsubstituted carbon of the double bond and was covalently linked to the fibre through a new C-C bond while maintaining unaltered the ester and the epoxide groups, available for further derivatisations. Because irradiation of the whole textile fibres in the range 20-200 KGy does not result in significant degradation of the material, GMA quenching of fibres irradiated in this dose range may represent an attractive route to their functionalisation.     

Influence of α-Tocopherol Load and Annealing Treatment on the Wear Resistance of Biomedical UHMWPE Irradiated with Electron Beam

A biomedical UHMWPE electron beam irradiated in air with doses raging between 25 and 100 KGy was doped with different amounts of α-tocopherol (0.1–0.7 wt.%) to prevent oxidative degradation. The polymer was annealed just after the irradiation at 110° for 24 h. Physical and mechanical tests were performed on the UHMWPE before and after the irradiation and on neat or doped material. Results showed that heat treatment after irradiation improves cross-links in the UHMWPE and α-tocopherol has good antioxidant action. The UHMWPE blended with 0.7% of antioxidant became harder and more wear resistant (+52%) after the irradiation with 100 KGy.     

Effect of gamma irradiation on microbial load,physicochemical and sensory characteristics of soybeans (Glycine max L. Merrill)

Gamma irradiation is highly effective in inactivating microorganisms in various foods and offers a safe alternative method of food decontamination. In the present study, soybeans (Glycine max L. Merrill) were treated with 0, 1.0, 3.0, 5.0 and 10.0 KGy of gamma irradiation. Microbial populations on soybeans, isoflavone, tocopherol contents, raffinose family oligosaccharides, color and sensory properties were evaluated as a function of irradiation dose. The results indicated that gamma irradiation reduced aerobic bacterial and fungal load. Irradiation at the doses applied did not cause any significant change (p>0.05) in the contents of isoflavone of soybeans, but decreased tocopherol contents. The content of key flatulence-producing raffinose family oligosaccharides in irradiated soybeans (10.0 kGy) decreased by 82.1% compared to the control. Sensory analysis showed that the odor of the soybeans was organoleptically acceptable at doses up to 5.0 kGy and no significant differences were observed between irradiated and nonirradiated samples in flavor, texture and color after irradiation.     

A study of the physiological changes and the nutritional qualities of irradiated apples and the effect of irradiation on apples stored at room temperature

The effects of γ-irradiation on the metabolism and nutritional qualities of cold Delicious apples and on the lethality of verticillate pathogenic fungi have been studied. The storage effect of irradiation on apples at room temperature has been observed. The results showed that the respiratory intensity of irradiated apple at 0.3–0.5 kGy was near or lower than that of unirradiated apple after 15 days irradiation. The amount of ethylene release was obviously inhibited when fruits were irradiated with 0.3–0.7 kGy. The flesh firmness of apple irradiated with 0.3–0.9 kGy was higher than that of unirradiated apple with the increasing of storage time. The negative correlations between the flesh firmness and the activities of pectinesterase (PE), polygalacturonase (PG) were observed when the dosage was lower than 1.5 kGy. The 2.0 kGy irradiation damaged the ultrastructure of cells, induced the softening of apple. When apples were irradiated with 0.7–2.0 kGy, the contents of 4 important volatile components of apple would be decreased. However, the dosage mentioned above had no effects on the pure chemicals. The studies showed that there was no significant effect of irradiation with 0.3–2.0 kGy on the nutritional qualities of apples and this dosage range could effectively control the verticillate pathogenic fungi. The result of storage experiments showed that the rotting fruits were obviously decreased by 0.3–0.9 kGy irradiation.     

Functionalization of a polyaspartamide with glycidyl methacrylate: A useful method to prepare hydrogels through gamma irradiation

α,β-Poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) was derivatized with glycidyl methacrylate (GMA). Aqueous solutions of the obtained copolymer PHEA-GMA (PHG) were irradiated by gamma rays with a dose rate of 0.5 KGy/h and at zero°C in the presence or in the absence of N, N'-methylenebisacrylamide (BIS). New hydrogel systems were obtained and characterized by FT-IR analyses and swelling measurements in aqueous medium at different pH values.     

Measurement of Phosphorus in Metals by RNAA

An RNAA procedure has been developed for measurement of low-level phosphorus in metals. Samples are irradiated at a neutron flux of 2.7·10¹³ n·cm^–2·s^–1 then mixed with carrier and dissolved in acid. After chemical separation and purification of the phosphorus and gravimetric determination of carrier yield, ³²P is determined using a beta proportional counter. The detection limit for a 0.1 g sample irradiated for 30 minutes is 5 g/kg. The method has been used to determine 6.4±0.6 mg/kg phosphorus in SRM 2175 refractory alloy.     

Paramagnetic centers by X-ray-irradiation of aluminium hydroxide

EPR spectra of paramagnetic centers originating from X-ray-irradiation of aluminium hydroxide at room temperature have been measured. The EPR spectrum represents a superposition of EPR spectra of ionic centers O^–, holes of type and trapped electrons. Radiation chemical yield of paramagnetic centers observed at room temperature (293 K) is G(spins.)=4.4±0.6) spins per 100 eV absorbed energy. The decay of paramagnetic centers in irradiated Al(OH)₃ was oberved at 293 K. The rate constant of the paramagnetic centers decay in irradiated Al(OH)₃ is K₂=(0.0980±0.0019) kg·mol^–1·min^–1 and their half-life is 9.43±0.18 days.Dedicated to the memory of the late Genrikh Markovis Kolyiari.     

Effect of γ-radiation on ointment cold cream

In this paper, Co-60γ ray was used to irradiate the ointment cold cream at room temperature (25°C). We also used FTIR, GC and thin film chromatogram to analyse various irradiated samples. It was found that the ointment cold cream can be irradiated at dose of 5–35 kGy and at dose rate from 0.2 to 0.6 kGy/h at room temperature (25°C) without evident decomposition. At dose of 5–15 kGy, the number of bacteria can be reduced to hygienic standard value. The radiation sterilization is a safe method for killing the bacteria in the ointment cold cream.     

Production of a fluorescence probe in ion-beam radiolysis of aqueous coumarin-3-carboxylic acid solution—2: Effects of nuclear fragmentation and its simulation with PHITS

The G(OH) values in aqueous coumarin-3-carboxylic-acid (3-CCA) solutions irradiated with ¹²C⁶⁺ beams having the energies of 135, 290 and 400 MeV/u were measured by a fluorescent method around the Bragg peak, with 0.6 mm intervals, and quartz cells of 1 cm optical lengths, at the Heavy Ion Medical Accelerator in Chiba, National Institute of Radiological Sciences (NIRS). For each ion, the G(OH) has been calculated as a function of dose average LET and position. The calculated results have been compared to measurements, and the results, reproducibility and reliability of the calculations are discussed in the paper.     

Rate coefficients for the reactions of O(3P) with selected biogenic Hydrocarbons

The rate coefficients for the reaction of O(³P) with the biogenic hydrocarbons Δ³-carene, α-pinene, and isoprene have been measured using a direct method for the first time. O(³P) was generated from the pulsed photolysis of NO₂ or O₃ at 308 nm, and measured by resonance fluorescence at 131 nm. Rate coefficients at room temperature for the biogenics are similar: (3.4 ± 0.6) × 10^?11, (3.7 ± 0.6) × 10^?11, and (3.5 ± 0.6) × 10^?11 cm³ molec^?1 s^?1, for Δ³-carene, α-pinene, and isoprene, respectively. The rate coefficients for the reaction of O(³P) with NO₂ and ethene were also measured with the same method, and these values are within 4% and 10% of the currently recommended values, respectively. The correlation between OH and O(³P)-alkene reaction rate coefficients is updated and discussed. © 1995 John Wiley & Sons, Inc.     

Phototransformation of imidacloprid on isolated tomato fruit cuticles and on tomato fruits

Imidacloprid, a neonicotinoid insecticide, is widely used in plant protection to prevent crop losses. The objective of this study was to show the photochemical fate of imidacloprid on plant surfaces by irradiation experiments on isolated tomato fruit cuticles and tomato fruits (Lycopersicon esculentum Mill.). Imidacloprid spiked samples were irradiated both under sunlight simulator and natural sunlight conditions for 24 h, which resulted in recoveries of 23% and 24%, respectively, if isolated cuticles were studied. On whole tomato fruits, recoveries were 33% and 71%, respectively. Similar results were obtained on cuticles spiked with the formulation Confidor and irradiated under natural sunlight. However, on tomato fruits the application of Confidor resulted in a higher loss (56%) of imidacloprid. During all irradiation experiments both on cuticles and whole fruits, 1-[(6-chloropyridin-3-yl)methyl]imidazolidin-2-imine was generally formed at 10–14 mol%, but different other photoproducts were also detected in low amounts, whereas N-nitrosoimidacloprid was only detected under natural sunlight conditions. Rapid photodegradation of imidacloprid could be demonstrated in all experiments. The identified photoproducts, 1-[(6-chloropyridin-3-yl)methyl]imidazolidin-2-imine and N-nitrosoimidacloprid, are possible reaction partners for plant cuticle constituents to form cuticle bound residues.     

Hydrolysis, Condensation, and Tetragonal Phase Formation in Sol-Gel Zirconia Prepared with Electron-Irradiated Alkoxide Solutions

Sol-gel zirconia precursor, zirconium n-butoxide in ter-butanol, was irradiated with 1.3 MeV electrons to a dose of 330 KGy. Gelling was instantaneously produced when an aqueous solution of sulfuric, hydrochloric or acetic acid was added to the irradiated solution; no hydrolysis catalyst was required. Samples were characterized with X-ray powder diffraction, infrared spectroscopy, and electron paramagnetic resonance. The electron irradiation accelerated hydrolysis and condensation, which avoided the stabilization of the tetragonal phase via carboxyls, and decreased the capability of sulfate ions to stabilize it. These results suggest that the stabilization of the tetragonal phase of sol-gel zirconia via carboxyl and sulfate ions depends on their diffusion in the sol.     

Effects of low-level gamma irradiation on the characteristics of fermented pork sausage during storage

The effect of gamma irradiation (0.5, 1, 2, and 4 kGy) on the quality of vacuum-packaged dry fermented sausages during refrigerated storage was evaluated. At Day 0 of irradiation, the pH, redness (CIE a^?), yellowness (CIE b^?), 2-thiobarbituric acid-reactive substances (TBARS) and volatile basic nitrogen (VBN) values of samples irradiated at 2 and 4 kGy were higher (p<0.05), but the CIE L^? values (lightness) were lower than those of the non-irradiated control (p<0.05). At<1 kGy irradiation, however, the pH, CIE L^?, CIE a^? and CIE b^?-value of samples were not significantly influenced by irradiation. The CIE a^?, and CIE b^?-values of samples irradiated at 2 and 4 kGy decreased with the increase of storage time. The VBN, TBARS, and CIE L^?-values of samples irradiated at 4 kGy were not changed significantly during refrigerated storage for 90 days (p>0.05). The total plate counts (TPC) and lactic acid bacteria (LAB) in the samples irradiated at 4 kGy were significantly lower (p<0.01) than those with lower irradiation doses. At the end of storage, the TPC, coliform, and LAB in the samples were not increased after irradiation at 1, 0.5 and 1 kGy, respectively. TPC and LAB were not detected in samples irradiated at 4 kGy at Day 90. In addition, no coliform bacteria were found in samples irradiated at 1 kGy during refrigerated storage. Sensory evaluation indicated that the rancid flavor of samples irradiated at 4 kGy was significantly higher, but aroma and taste scores were lower than those of the control at Day 3 of storage. Irradiation of dry fermented sausages at 2 kGy was the best conditions to prolong the shelf-life and decrease the rancid flavor without significant quality deterioration.     

Preparation and Characterization of Single-Phase Perovskite La0.6Sr0.4Co0.8Fe0.2O3-δ

Single-phase perovskite La0.6Sr0.4Co0.8Fe0.2O3-δ has been successfully prepared by using citrate-EDTA complexation method at relatively low calcination temperature. The structure and thermal decomposition process of the complex precursor have been investigated by means of differential scanning calorimetry-thermal gravimetric analysis (DSC/TGA), X-ray diffraction (XRD), and Fourier transform infrared spectroscopic (FT-IR) measurements. The precursor decomposed completely and started to form perovskite-type oxide above 420℃ according to the differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) results. Single-phase perovskite La0.6Sr0.4Co0.8Fe0.2O3-δ obtained has been confirmed from the XRD pattern, and no peak of SrCO3 was found by XR.D of the oxides synthesized at a relatively low temperature of 800 ℃. The reducibility of La0.6Sr0.4Co0.8Fe0.2O3-δ was also characterized by the temperature programmed reduction (TPR) technique. Disk shaped dense La0.6Sr0.4Co0.8Fe0.2O3-δ membrane was prepared by the isostatical pressing method. The oxygen flux rate of dense La0.6Sr0.4Co0.8Fe0.2O3-δ membrane was (2.8-18)×10-8 mol/(cm2·s) in the temperature range of 800-1 000℃.     

Electrochemical characteristics of La0.6Sr0.4CoO3-δ, Pr0.6Sr0.4CoO3-δ and Gd0.6Sr0.4CoO3-δ on Ce0.85Sm0.15O1.925 electrolyte

Cyclic voltammetry, chronoamperometry and electro-chemical impedance have been used for the analysis of the following medium temperature half-cells: Ce_0.85Sm_0.15O_1.925| La_0.6Sr_0.4CoO_3-δ, Ce_0.85Sm_0.15O_1.925| Pr_0.6Sr_0.4CoO_3-δ and Ce_0.85Sm_0.15O_1.925| Gd_0.6Sr_0.4CoO_3-δ. The influence of the atomic mass of the A–site cation in the perovskite cathode on the oxygen reduction kinetics has been discussed. The total polarisation resistance, obtained from the Z′′, Z′-plots, increases with the rise of atomic mass of the cation in the A-site position. Two different time constants have been obtained for the oxygen electroreduction process, and the replacement of La³⁺ by Gd³⁺ in the cathode material decreases somewhat the surface catalytic activity, but the noticeably higher low-frequency series resistance, i.e. mainly diffusion-like mass transfer resistance, values have been obtained. However, the mainly diffusion-limited process at T≤773 K for Gd_0.6Sr_0.4CoO_3-δ and the kinetically mixed process (diffusion + charge transfer) for Pr_0.6Sr_0.4CoO_3-δ and La_0.6Sr_0.4CoO_3-δ have been established. At higher temperature (T≥993 K) and more negative potentials, the O₂ reduction process is limited mainly by the heterogeneous charge transfer step. Presented at the fourth Baltic Conference on Electrochemistry, Greifswald, March 13–16, 2005.     

Opto-structural characterization of proton (3 MeV) irradiated polycarbonate and polystyrene

Polycarbonate (Makrofol-N) and polystyrene thin films were irradiated with protons (3 MeV) under vacuum at room temperature with the fluence ranging from 1×10¹⁴ to 1×10¹⁵ protons cm⁻². The change in optical properties, degradation of the functional groups and crystallinity of the proton-irradiated polymers were investigated with UV–vis, Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) techniques, respectively. The UV–vis analysis revealed that the optical band gap of irradiated Makrofol-N is reduced by 30% as compared to 27.5% in polystyrene at highest fluence of 1×10¹⁵ protons cm⁻², owing to higher electronic energy loss of protons in Makrofol-N. The calculations of the number of carbon atoms per conjugation length, N and number of carbon atoms per clusters, M embedded in the network of polymers further revealed that Makrofol-N is more modified as compared to polystyrene on proton irradiation. FTIR results reveal the reduction in absorption intensity of the main characteristic bands of both the polymers after irradiation. The proton-irradiated Makrofol-N shows a strong decrease of almost all of its characteristic absorption bands at about 1×10¹⁴ protons cm⁻². Beyond a critical dose an increase of almost all its characteristic bands are noticed, however, no such effect had been observed in polystyrene at this particular fluence. Appearance of new –OH groups was observed at the higher fluences in the FTIR spectra of both proton-irradiated polymers. XRD measurements show the decrease of the main peak intensity and the crystallite size, confirming the increase of amorphization in polymers under irradiation.     

TSL and EPR studies of SrBPO5 doped with CeO2 and co-doped with CeO2 and Sm2O3

Thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) investigations were carried out on gamma irradiated SrBPO₅ samples doped with CeO₂ and co-doped with CeO₂ and Sm₂O₃. On gamma-irradiation at room temperature, BO₃ ^2–, O₂ ^– and O^– radicals were produced. It was seen that the O^– radical ion disappeared in the sample annealed at 500 K. It is proposed that the recombination between trapped electrons and O^– radical ions results in transfer of recombination energy to the impurity centre Ce³⁺ resulting in TSL glow peak at 485 K. In the case of co-doped samples energy transfer occurs between Ce³⁺ to Sm³⁺ resulting in increase in the intensity of glow peak at 485 K.The authors are grateful to Dr. V. K. Manchanda, Head, Radiochemistry Division, BARC for his keen interest and encouragement during the course of this work.     

Effect of gamma-irradiation on thermoluminescence values in dried fruits

Studies were conducted to measure the effect of irradiation treatment on thermoluminescence (TL) values in dried fruits such as apricots, dates and raisins. For this purpose, inorganic dust particulate (minerals) adhering to the fruit surface was collected from untreated and treated (0.5, 1.0 and 1.5 kGy) samples. The TL responses of the isolated minerals was measured in the temperature range of 80–320°C at an increasing rate of 10°C/s. It was observed that peak of the TL signals appeared at 200°C in each case and generally the magnitude of the peak signals was almost 10³ times that of unirradiated samples. Regression and correlation analysis of the data indicated strong relationship between radiation absorbed dose and TL values at each temperature (r≥0.98). It was concluded that TL measurements could serve as a fast and reliable method for distinguishing as well as determining absorbed dose in irradiated dried apricot, date and raisin.     

The synthesis and photoactivated cytotoxicity of 2-methyl-4-oxo-3-prop-2-yn-1-ylcyclopent-2-en-1-yl-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate conjugated with α-terthienyl derivatives

The synthesis of one pyrethroid insecticide [2-methyl-4-oxo-3-prop-2-yn-1-ylcyclopent-2-en-1-yl-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate (Abbrev. JZ) (Fig. 1)] conjugated with a series of α-terthienyl derivatives (2–8) (Fig. 1) by palladium/copper-catalyzed cross-coupling reaction is presented here for evaluating the photoactivated cytotoxicity. The photoactivated cytotoxicity on Spodoptera litura (SL) cell line was detected by MTT assay. The inhibitory activity of all the conjugates was enhanced in the irradiation condition, compared with that of JZ. The IC₅₀ values of the most effective compound 9 (Fig. 1) treated with irradiation were 11.60 μg mL⁻¹ at 24 h and 8.93 μg mL⁻¹ at 48 h, respectively. Generation of intracellular reactive oxygen species (ROS) and change of mitochondrial transmembrane potential (MMP) on SL cells treated with compound 9 were used for the further photoactivated study. A summary of these experiments on compound 9 demonstrated the notable ROS generation and dramatic MMP decrease when irradiated with UVA light. The results also represented statistically significant difference between dark and irradiation treatment of compound 9. However, in control and JZ groups, the effects were not statistically different. It was proved that our prepared compounds were ideal candidates for new photoactivated pyrethroid insecticides.