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Gamma Irradiation (gamma + irradiation)
Selected AbstractsGAMMA IRRADIATION ON FROZEN AND PACKAGED HEADED SHRIMPJOURNAL OF FOOD QUALITY, Issue 4 2009V.K.G. ABREU ABSTRACT The objective of this work was to evaluate the effects of , irradiation (0, 2, 4 and 6 kGy doses), applied on frozen and packaged headed shrimps, on pathogenic Vibrio cholerae O1 and Salmonella enteritidis bacteria, as well as on some of the physical and sensory characteristics of this kind of food. The 6 kGy dose was highly efficient in inhibiting V. cholerae O1 and S. enteritidis and in decreasing lipid oxidation in shrimps compared with the nonirradiated product. Shrimp texture was not affected by any of the irradiation doses studied, but the lightness of the surface color increased in shrimps irradiated with 6 kGy compared with those irradiated with 2 kGy. Shrimps irradiated with 6 kGy showed lower overall acceptability than those irradiated with 2 kGy or were nonirradiated. The application of , irradiation in doses up to 6 kGy on frozen and packaged headed shrimps could improve the microbiological quality of this commodity. PRACTICAL APPLICATIONS The use of , irradiation has the potential to ensure safety effectively by inactivating bacteria, increasing shelf life and maintaining food quality without significant chemical changes in the food matrix. Besides, this process can be applied to frozen and packaged products. Thus, irradiation of frozen and packaged shrimps could benefit the local processing industry, which could offer the international market a high-quality product, with an additional safety treatment. [source] CONTAMINATION OF GRAINS BY MYCOTOXIN-PRODUCING MOLDS AND MYCOTOXINS AND CONTROL BY GAMMA IRRADIATIONJOURNAL OF FOOD SAFETY, Issue 3 2006NAGY H. AZIZ ABSTRACT Ninety random grain samples were collected and analyzed for mycotoxins, and the effect of gamma irradiation on the production of mycotoxins in grains was studied. Aspergillus, Penicillium, Mucor, Rhizopus, Fusarium, Alternaria, Scopulariopsis and Cladosporium were the most common fungal genera isolated from grains. Aspergillus flavus, Aspergillus niger, Aspergillus candidus, Aspergillus ochraceus, Penicillium citrinum, Penicillium expansum, Penicillium citreonigrum, Penicillium purpurogenum, Penicillium griseofulvum and Penicillium verrucosumwere the most common Aspergillus and Penicillium species in grains. Out of 120 Aspergillus and Penicillium isolates, 80 were mycotoxin producers. Analysis of grains revealed the occurrence of aflatoxin B1 ochratoxin A, cycolopiazonic acid and citrinin. Of the 90 samples, 67 were positive for one or more mycotoxin. Irradiation of grains at dose of 2.0 and 4.0 kGy decreased significantly the total fungal counts compared with unirradiated controls. After 100 days of storage at room temperature, the unirradiated grains were contaminated with high concentrations of mycotoxins as compared with irradiated 4.0-kGy samples. Mycotoxin production in grains decreased with increasing irradiation doses and was not detected at 6.0 kGy over 100 days of storage. [source] Effect of Sequential Treatment of Warm Water Dip and Low-dose Gamma Irradiation on the Quality of Fresh-cut Green OnionsJOURNAL OF FOOD SCIENCE, Issue 3 2005Hyun Jung Kim ABSTRACT: The effect of warm water dip in combination with irradiation on quality of fresh-cut green onions was studied. Fresh-cut green onions were treated with and without warm water (50°C for 20 s) and packaged prior to irradiation at 0, 0.5, 1.0, and 1.5 kGy, then stored at 4°C for 14 d. Color, texture, decay percentage, electrolyte leakage, sensory qualities, and total aerobic count (TAC) were measured at 1,4,8, and 14 d of storage. The warm water treatment reduced the TAC by 0.9 log initially but the beneficial effect disappeared during storage. With the test conditions used in this study, the warm water treatment did not provide added benefits for quality improvements. Irradiation at all tested doses reduced TAC and the development of decay and off-odor, improved visual quality, and preserved green color. [source] Effects of Low-dose Gamma Irradiation and Conventional Treatments on Shelf Life and Quality Characteristics of Diced CeleryJOURNAL OF FOOD SCIENCE, Issue 6 2000A. Prakash ABSTRACT: The effects of 0.5 and 1.0 kGy gamma irradiation on microbial and sensory characteristics of diced celery were compared to conventional treatments such as acidification, blanching, and chlorination. Aerobic plate counts for the irradiated celery did not exceed 107 CFU/g, in contrast, the acidified, blanched, chlorinated, and control samples surpassed aerobic microbial counts of 108 CFU/g in 22, 19, 12, and 8 d, respectively. Importantly, the 1.0-kGy treatment eliminated inoculated Listeria monocytogenes and E. coli. While the acidified and blanched samples had significantly different sensory profiles compared to the other treatments, the irradiated samples maintained their color, texture, and aroma longer and were preferred in the sensory tests. The sensory shelf life of the 1.0-kGy-treated celery was 29 d compared to 22 d for the control, chlorinated, and 0.5 kGy, and 15 d for the acidified and blanched celery. [source] The lethal effects of gamma irradiation on larvae of the Huhu beetle, Prionoplus reticularis: a potential quarantine treatment for New Zealand export pine treesENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2000Philip J. Lester Abstract Gamma irradiation was investigated as a possible method for disinfestation of huhu beetle larvae, Prionoplus reticularis White, in Pinus radiata D. Don. Larvae of four representative size classes were irradiated at six doses, and the lethal dose (LD99) calculated from mortality data 3 days and 10 days post treatment. All larval size classes showed a similar sensitivity to gamma irradiation and required 3677 Gray (Gy) and 2476 Gy for a LD99 3 and 10 days post-treatment, respectively. The penetration of gamma irradiation into pine wood was found to be lowest in freshly cut logs, and decreased linearly at a rate of 0.698 Gy mm,1 of wood. The penetration was greatest in wood that had been stored for 2 years, and decreased 0.512 Gy mm,1 of wood. These results are likely to be correlated with wood moisture content. Gamma irradiation appears to be a potential alternative method to fumigation for quarantine treatment of P. reticularis. [source] Effect of gamma irradiation and sulphitation treatments on keeping quality of white button mushroom Agaricus bisporus (J. Lge)INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2009Ali M. Wani Summary Gamma irradiation, alone and in combination with sulphitation, was tested for preventing the browning and maintaining the quality attributes of the white button mushrooms. Mushrooms were subjected to treatment of gamma irradiation in the dose range of 0.5,2.0 kGy and to combination treatments of sulphitation at a concentration of 0.1% potassium metabisulphite (KMS) and gamma irradiation (dose range 0.5,2.0 kGy) followed by storage at 10 ± 2 °C (RH 85%). A dose of 2.0 kGy significantly reduced the weight loss, prevented browning and mould growth. Cap and veil opening of mushrooms was delayed by 9 days and shelf life was extended by 12 days at a dose level of 2.0 kGy. Sulphitation alone at a concentration of 0.1% KMS was effective in controlling browning only upto 3 days, beyond which both browning and cap opening increased significantly (P , 0.05) and the samples were unacceptable after 6 days of storage. No synergistic effect of sulphitation and irradiation was observed with respect to the shelf-life extension of mushroom. [source] Gamma irradiation alters fatigue-crack behavior and fracture toughness in 1900H and GUR 1050 UHMWPEJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 5 2002Jantzen C. Cole Abstract Pitting and delamination remain causative factors of polyethylene failure in total knee replacement. Gamma irradiation induces cross linking in ultra-high-molecular-weight polyethylene, which has been shown to improve wear resistance. Irradiation may reduce fracture toughness and fatigue strength, however, and the effects of irradiation are dependent upon the resin, processing technique, and radiation dose. The effects of varying levels of gamma irradiation (0, 33, 66, and 100 kGy) on the fracture toughness and fatigue-crack resistance of UHMWPE, isostatically molded from 1900H and GUR 1050 resins, were examined. Paris law regressions were performed to quantify fatigue-crack propagation rates as functions of change in stress intensity, and J -integral methods were used to quantify the elastic,plastic fracture toughness. The results indicated that gamma irradiation reduced the resistance of both materials to fatigue-crack growth, and that the reductions were radiation dosage and resin dependent. Irradiation at any level was detrimental to the fracture toughness of the 1900H specimens. Irradiation at 33 kGy increased fracture toughness for the GUR 1050 specimens, and substantial reductions were observed only at the highest irradiation level. Scanning electron microscopy of the fracture surface revealed diamond-like fracture patterns of the nonirradiated specimens indicative of ductile, multilevel fracture. Pronounced striations were apparent on these fracture surfaces, oriented perpendicular to the direction of crack growth. The striations appeared as folds in surface layers of the GUR 1050 specimens. At the highest irradiation levels, the striations were nearly eliminated on the fracture surfaces of the 1900H specimens, and were markedly less severe for the GUR 1050. These results demonstrated that at higher irradiation levels the materials became more brittle in fatigue, with less ductile folding and tearing of the fracture surfaces. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 559,566, 2002 [source] Reduction of Carcinogenic N-Nitrosamines and Residual Nitrite in Model System Sausage by IrradiationJOURNAL OF FOOD SCIENCE, Issue 4 2002H. J. Ahn ABSTRACT Gamma irradiation was used to reduce the N-nitrosamines and residual nitrite in model system sausage during storage. Aerobic or vacuum packaged sausage was irradiated at 0, 5,10, 20, and 30 kGy. The residual nitrite levels were significantly reduced by gamma irradiation, and, in vacuum packaging, the reduction was dose dependent. The N-nitrosodimethylamine of the sausage irradiated at 10 kGy or above reduced in aerobic packaging, while a dose of 20 kGy was needed in vacuum packaging. The N-nitrosopyrrolidine reduction was found at 20 and 30 kGy-irradiation. Results indicated that high dose irradiation (> 10 kGy) was needed to reduce the carcinogenic N-nitrosamine and nitrite levels in pork sausage during storage. [source] The lethal effects of gamma irradiation on larvae of the Huhu beetle, Prionoplus reticularis: a potential quarantine treatment for New Zealand export pine treesENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2000Philip J. Lester Abstract Gamma irradiation was investigated as a possible method for disinfestation of huhu beetle larvae, Prionoplus reticularis White, in Pinus radiata D. Don. Larvae of four representative size classes were irradiated at six doses, and the lethal dose (LD99) calculated from mortality data 3 days and 10 days post treatment. All larval size classes showed a similar sensitivity to gamma irradiation and required 3677 Gray (Gy) and 2476 Gy for a LD99 3 and 10 days post-treatment, respectively. The penetration of gamma irradiation into pine wood was found to be lowest in freshly cut logs, and decreased linearly at a rate of 0.698 Gy mm,1 of wood. The penetration was greatest in wood that had been stored for 2 years, and decreased 0.512 Gy mm,1 of wood. These results are likely to be correlated with wood moisture content. Gamma irradiation appears to be a potential alternative method to fumigation for quarantine treatment of P. reticularis. [source] Radioprotective effects of Daflon against genotoxicity induced by gamma irradiation in human cultured lymphocytesENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 9 2009Seyed Jalal Hosseinimehr Abstract The ability of Daflon to protect against genotoxicity induced by gamma irradiation has been investigated in vivo and in vitro in cultured lymphocytes from healthy human volunteers. Peripheral human blood samples were collected predose (10 min before) and 1, 2, and 3 hr after a single oral ingestion of 1000 mg of Daflon. At each time point, whole blood was exposed in vitro to 150 cGy of cobalt-60 gamma rays, and then the lymphocytes were cultured with mitogenic stimulation to determine the micronuclei in cytokinesis-blocked binucleated cells. For each volunteer, the results showed a significant increase in the incidence of micronuclei after exposure to gamma irradiation as compared to control unexposed samples. As early as 1 hr after Daflon administration, a significant decrease in the incidence of micronuclei was observed in comparison with similarly irradiated lymphocytes collected before administration. The maximum protection was reached 1 hr after administration of Daflon with a significant decrease in the frequency of micronuclei of 40%. These findings suggest the possible application of Daflon for the protection of human lymphocytes from the genetic damage and side effects induced by gamma irradiation. Environ. Mol. Mutagen. 2009. © 2009 Wiley-Liss, Inc. [source] Effects of low dose gamma irradiation on microbial inactivation and physicochemical properties of fried shrimp (Penaeus vannamei)INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2010He Wang Summary Changes in microbiological, physicochemical and sensory properties of shrimp gamma irradiated with 60Co at doses of 0, 1, 3, 6, 9 kGy were investigated. Irradiation at 6 kGy eliminated most of the spoilage microorganisms and did not affect sensory quality. The L* value increased as irradiation dose increased, while a* value decreased as irradiation dose increased. Irradiation had no significant effect on the texture of shrimp samples; however, increasing the dose up to 9 kGy significantly increased the amount of volatile compounds, such as, alcohols, ketones, aldehydes, furans, and oxides. According to the total sensory points, the appearance and flavour of the shrimp product was considered as acceptable by sensory evaluation when irradiated at doses of 0,6 kGy. These results showed that gamma irradiation processing (<6 kGy) had the potential to extend the shelf life of fried shrimp. [source] Effect of gamma irradiation and sulphitation treatments on keeping quality of white button mushroom Agaricus bisporus (J. Lge)INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2009Ali M. Wani Summary Gamma irradiation, alone and in combination with sulphitation, was tested for preventing the browning and maintaining the quality attributes of the white button mushrooms. Mushrooms were subjected to treatment of gamma irradiation in the dose range of 0.5,2.0 kGy and to combination treatments of sulphitation at a concentration of 0.1% potassium metabisulphite (KMS) and gamma irradiation (dose range 0.5,2.0 kGy) followed by storage at 10 ± 2 °C (RH 85%). A dose of 2.0 kGy significantly reduced the weight loss, prevented browning and mould growth. Cap and veil opening of mushrooms was delayed by 9 days and shelf life was extended by 12 days at a dose level of 2.0 kGy. Sulphitation alone at a concentration of 0.1% KMS was effective in controlling browning only upto 3 days, beyond which both browning and cap opening increased significantly (P , 0.05) and the samples were unacceptable after 6 days of storage. No synergistic effect of sulphitation and irradiation was observed with respect to the shelf-life extension of mushroom. [source] Effect of gamma-ray irradiation on the physicochemical properties of flour and starch granule structure for wheatINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 4 2009Jun Wang Summary Effect of gamma irradiation on the physicochemical properties of flour and starch granule structure of wheat was compared to non-irradiated wheat. The moisture content of wet gluten and titratable acidity of wheat flour were significantly affected by gamma irradiation. This treatment also destroyed the starch granules of wheat grain and their breakage augmented as the dose of gamma irradiation increased, apparently resulting in the increase of small starch granules. Probably, these results were due to the disruption of large molecule, such as proteins, lipids and starch. The irradiated wheat flour for RVA pasting properties (flour viscosity) was also evaluated. Besides the difference in RVA profile, starch pasting curves showed a considerable decrease for six main parameters as gamma irradiation dose at different velocity increased. [source] Gamma irradiation alters fatigue-crack behavior and fracture toughness in 1900H and GUR 1050 UHMWPEJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 5 2002Jantzen C. Cole Abstract Pitting and delamination remain causative factors of polyethylene failure in total knee replacement. Gamma irradiation induces cross linking in ultra-high-molecular-weight polyethylene, which has been shown to improve wear resistance. Irradiation may reduce fracture toughness and fatigue strength, however, and the effects of irradiation are dependent upon the resin, processing technique, and radiation dose. The effects of varying levels of gamma irradiation (0, 33, 66, and 100 kGy) on the fracture toughness and fatigue-crack resistance of UHMWPE, isostatically molded from 1900H and GUR 1050 resins, were examined. Paris law regressions were performed to quantify fatigue-crack propagation rates as functions of change in stress intensity, and J -integral methods were used to quantify the elastic,plastic fracture toughness. The results indicated that gamma irradiation reduced the resistance of both materials to fatigue-crack growth, and that the reductions were radiation dosage and resin dependent. Irradiation at any level was detrimental to the fracture toughness of the 1900H specimens. Irradiation at 33 kGy increased fracture toughness for the GUR 1050 specimens, and substantial reductions were observed only at the highest irradiation level. Scanning electron microscopy of the fracture surface revealed diamond-like fracture patterns of the nonirradiated specimens indicative of ductile, multilevel fracture. Pronounced striations were apparent on these fracture surfaces, oriented perpendicular to the direction of crack growth. The striations appeared as folds in surface layers of the GUR 1050 specimens. At the highest irradiation levels, the striations were nearly eliminated on the fracture surfaces of the 1900H specimens, and were markedly less severe for the GUR 1050. These results demonstrated that at higher irradiation levels the materials became more brittle in fatigue, with less ductile folding and tearing of the fracture surfaces. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 559,566, 2002 [source] CONTAMINATION OF GRAINS BY MYCOTOXIN-PRODUCING MOLDS AND MYCOTOXINS AND CONTROL BY GAMMA IRRADIATIONJOURNAL OF FOOD SAFETY, Issue 3 2006NAGY H. AZIZ ABSTRACT Ninety random grain samples were collected and analyzed for mycotoxins, and the effect of gamma irradiation on the production of mycotoxins in grains was studied. Aspergillus, Penicillium, Mucor, Rhizopus, Fusarium, Alternaria, Scopulariopsis and Cladosporium were the most common fungal genera isolated from grains. Aspergillus flavus, Aspergillus niger, Aspergillus candidus, Aspergillus ochraceus, Penicillium citrinum, Penicillium expansum, Penicillium citreonigrum, Penicillium purpurogenum, Penicillium griseofulvum and Penicillium verrucosumwere the most common Aspergillus and Penicillium species in grains. Out of 120 Aspergillus and Penicillium isolates, 80 were mycotoxin producers. Analysis of grains revealed the occurrence of aflatoxin B1 ochratoxin A, cycolopiazonic acid and citrinin. Of the 90 samples, 67 were positive for one or more mycotoxin. Irradiation of grains at dose of 2.0 and 4.0 kGy decreased significantly the total fungal counts compared with unirradiated controls. After 100 days of storage at room temperature, the unirradiated grains were contaminated with high concentrations of mycotoxins as compared with irradiated 4.0-kGy samples. Mycotoxin production in grains decreased with increasing irradiation doses and was not detected at 6.0 kGy over 100 days of storage. [source] Aflatoxin Inactivation Using Aqueous Extract of Ajowan (Trachyspermum ammi) SeedsJOURNAL OF FOOD SCIENCE, Issue 1 2005Shruti S. Hajare ABSTRACT: Aqueous extract of ajowan seeds was found to contain an aflatoxin inactivation factor (IF). Thin layer chromatography analysis of the toxins after treatment with IF showed relative reduction of aflatoxin G1 > G2 > B1 > B2. Quantification of toxin using a fluorotoxin meter as well as the Enzyme Linked Immuno s orb ent Assay (ELISA) confirmed these findings. An approximate 80% reduction in total aflatoxin content over the controls was observed. This observed phenomenon of reduction in total toxin was referred to as toxin inactivation. Temperature was found to influence the rate of toxin inactivation. At 45 °C, it was found to be rapid during the initial 5 h and slowed later. The IF was found to retain considerable activity even after boiling and autoclaving, indicating partial heat stability. The activity was lost below pH 4.0. Above pH 4.0, it increased gradually, reaching the maximum at pH 10.0. IF was found to be stable to gamma irradiation. Toxin decontamination in spiked corn samples could be achieved using IF. This study emphasizes the potential of ajowan IF in aflatoxin removal from contaminated food commodities. However, the biological toxicity, if any, of the IF inactivated aflatoxins needs to be confirmed, and the work in this direction is in progress. [source] Irradiation Effects on Biogenic Amines in Korean Fermented Soybean Paste During FermentationJOURNAL OF FOOD SCIENCE, Issue 1 2003J.-H. Kim ABSTRACT: Irradiation effects on biogenic amines (BAs) and microbiological populations of Korean fermented soybean paste were investigated during fermentation. Soybean paste was prepared and irradiated with doses of 5,10, and 15 kGy, and then fermented at 25 °C for 12 wk. Bacillus spp. and lactic-acid bacteria decreased by irradiation but increased during fermentation. Biogenic amines detected were putrescine, cadaverine, ,-phenylethylamine, spermidine, spermine, tryptamine, histamine, tyramine, and agmatine. A significant difference was not observed in BA content between control and irradiated samples immediately after gamma irradiation. However, 4 kinds of BAs, putrescine, tryptamine, spermidine, and histamine, showed significant reduction by irradiation during fermentation (P < 0.05). [source] Reduction of Carcinogenic N-Nitrosamines and Residual Nitrite in Model System Sausage by IrradiationJOURNAL OF FOOD SCIENCE, Issue 4 2002H. J. Ahn ABSTRACT Gamma irradiation was used to reduce the N-nitrosamines and residual nitrite in model system sausage during storage. Aerobic or vacuum packaged sausage was irradiated at 0, 5,10, 20, and 30 kGy. The residual nitrite levels were significantly reduced by gamma irradiation, and, in vacuum packaging, the reduction was dose dependent. The N-nitrosodimethylamine of the sausage irradiated at 10 kGy or above reduced in aerobic packaging, while a dose of 20 kGy was needed in vacuum packaging. The N-nitrosopyrrolidine reduction was found at 20 and 30 kGy-irradiation. Results indicated that high dose irradiation (> 10 kGy) was needed to reduce the carcinogenic N-nitrosamine and nitrite levels in pork sausage during storage. [source] Effects of Low-dose Gamma Irradiation and Conventional Treatments on Shelf Life and Quality Characteristics of Diced CeleryJOURNAL OF FOOD SCIENCE, Issue 6 2000A. Prakash ABSTRACT: The effects of 0.5 and 1.0 kGy gamma irradiation on microbial and sensory characteristics of diced celery were compared to conventional treatments such as acidification, blanching, and chlorination. Aerobic plate counts for the irradiated celery did not exceed 107 CFU/g, in contrast, the acidified, blanched, chlorinated, and control samples surpassed aerobic microbial counts of 108 CFU/g in 22, 19, 12, and 8 d, respectively. Importantly, the 1.0-kGy treatment eliminated inoculated Listeria monocytogenes and E. coli. While the acidified and blanched samples had significantly different sensory profiles compared to the other treatments, the irradiated samples maintained their color, texture, and aroma longer and were preferred in the sensory tests. The sensory shelf life of the 1.0-kGy-treated celery was 29 d compared to 22 d for the control, chlorinated, and 0.5 kGy, and 15 d for the acidified and blanched celery. [source] Polyethylene cross-linking by two different methods reduces acetabular liner wear in a hip joint wear simulatorJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2003Darryl D. D'Lima Advances in cross-linking have led to the development of wear resistant ultrahigh molecular weight polyethylene for total joint replacement. This study compared wear reduction by two different cross-linking methods as measured in a hip wear simulator. One highly cross-linked polyethylene was treated with 7.5 Mrad gamma irradiation with post-irradiation annealing and a sterilization dose of 2.5 Mrad (10 Gamma), while the other used 9.5 Mrad warm irradiation with 10 MeV electron-beam (9.5 EB). Liners of the same design, made from nominally cross-linked (gamma sterilized) polyethylene were also tested. Gravimetric wear analysis was performed every 500,000 cycles for 5,000,000 cycles. After correcting for weight gain due to water absorption, the nominally cross-linked liners demonstrated mean wear rates of 15.7 (±1.7) and 12.5 (±1.0) mg/million cycles. Both highly cross-linked polyethylene liners demonstrated significantly less wear than their respective controls (with mean wear rates of 1.5 (±1.2) and ,1.4 (±1.5) mg/million cycles). The 9.5 EB liners gained weight presumably due to increased fluid absorption, in addition to that measured in loaded,soaked control implants. Any wear occurring was therefore assumed to have been more than offset by weight gain. Highly cross-linked polyethylene was significantly more wear resistant than non- or nominally cross-linked polyethylene. The differences in wear rates between the two highly cross-linked polyethylene designs (9.5 EB or 10 Gamma) are probably too small to be clinically significant. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Effect of freeze-drying and gamma irradiation on the mechanical properties of human cancellous boneJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2000O. Cornu Freeze-drying and gamma irradiation are commonly used for preservation and sterilization in bone banking. The cumulative effects of preparation and sterilization of cancellous graft material have not been adequately studied, despite the clinical importance of graft material in orthopaedic surgery. Taking benefit from the symmetry of the left and right femoral heads, the influence of lipid extraction followed by freeze-drying of a femoral head and a final 25-kGy gamma irradiation was determined, with the nonirradiated, nonprocessed counterpart as the control. Five hundred and fifty-six compression tests were performed (137 pairs for the first treatment and 141 pairs for the second). Mechanical tests were performed after 30 minutes of rehydration in saline solution. Freeze-dried femoral heads that had undergone lipid extraction experienced reductions of 18.9 and 20.2% in ultimate strength and stiffness, respectively. Unexpectedly, the work to failure did not decrease after this treatment. The addition of gamma irradiation resulted in a mean drop of 42.5% in ultimate strength. Stiffness of the processed bone was not modified by the final irradiation, with an insignificant drop of 24%, whereas work to failure was reduced by a mean of 71.8%. Freeze-dried bone was a bit less strong and stiff than its frozen control. Its work to failure was not reduced, due to more deformation in the nonlinear domain, and it was not brittle after 30 minutes of rehydration. Final irradiation of the freeze-dried bone weakened its mechanical resistance, namely by the loss of its capacity to absorb the energy (in a plastic way) and a subsequent greater brittleness. [source] Long-lived intermediates in reversible addition,fragmentation chain-transfer (RAFT) polymerization generated by , radiationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2002Christopher Barner-Kowollik Abstract A novel experimental procedure is presented that allowed probing of reversible addition,fragmentation chain-transfer (RAFT) free-radical polymerizations for long-lived species. The new experimental sequence consisted of gamma irradiation of a mixture of initial RAFT agent (cumyl dithiobenzoate) and monomer at ambient temperature, a subsequent predetermined waiting period without initiation source also at ambient temperature, and then heating of the reaction mixture to a significantly higher temperature. After each sequence step, the monomer conversion and molecular weight distribution were determined, indicating that controlled polymer formation occurs only during the heating period. The results indicated that stable intermediates (either radical or nonradical in nature) are present in such experiments because thermal self-initiation of the monomer can be excluded as the reason for polymer formation. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1058,1063, 2002 [source] Is growth hormone a radioprotective agent?JOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 3 2006SB Tekin Abstract There is currently substantial clinical interest in growth hormone (GH) as a protective agent against radiation-related normal tissue injury. To further assess the potential radiation injury-preventive effects of GH, these effects were studied in rats by using a radiation-induced skin injury model. Group 1 received neither GH nor irradiation (control group). Group 2 received 30 Gy of gamma irradiation as a single dose to the right hind legs of the rats (radiation group). Group 3 and 4 received the same irradiation plus either 0.01 U/kg/day GH (RT + 0.01 GH group) or 0.02 U/kg/day GH (RT + 0.02 GH group) subcutaneously. Clinically and histopathologically, acute skin reactions were assessed by two independent experts in radiation oncology and pathology, respectively. Irradiation increased dermatitis in rats when compared with the control group. The severity of radiodermatitis in the rats in the RT + 0.01 GH and RT + 0.02 GH groups was significantly lower than that in the RT group; radiodermatitis developed earlier in the RT group than in the other groups. GH was efficacious in preventing epidermal atrophy, dermal degeneration such as oedema and collagen fibre loss, and hair follicle atrophy, but not better than in the control group. These results are preliminary to studies that will be performed with higher doses of GH in radiation-treated cancer patients, with the aim of reducing radiation-induced toxicity. [source] The effect of gamma irradiation on the microbial load, mineral concentration and sensory characteristics of liquorice (Glycyrrhiza glabra L)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 1 2003Mahfouz Al-Bachir Abstract Ground liquorice roots were exposed to various doses (0, 5, 10, 15 and 20,kGy) of gamma radiation from a 60Co source. Irradiated and non-irradiated samples were stored at room temperature. Microbial population, viscosity, concentrations of some minerals and the sensory properties of the extracts were evaluated after 0 and 12 months of storage. Tests carried out immediately after irradiation showed that the microbial count had been reduced and that the dose required to reduce the count by 1 log cycle (D10) was about 2,kGy. No effect was observed on the total dissolved solids in extracts of liquorice roots. Glycyrrhizinic acid concentration in the extracts and the viscosities of suspensions produced from irradiated roots were lower than those from non-irradiated ones. Sensory evaluation indicated that there were no significant differences (P,<,0.05) in colour, taste or flavour between extracts produced from irradiated and non-irradiated roots. However, after 12 months of storage, some mineral ion (Na+, Ca2+ and K+) concentrations in extracts produced from irradiated roots were lower than in those from non-irradiated ones; no significant differences (P,<,0.05) in viscosity were found between suspensions of irradiated and non-irradiated roots. © 2002 Society of Chemical Industry [source] Effects of gamma irradiation on physical and chemical properties of chickpeas (Cicer arietinum)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2002John A Graham Abstract Changes in the physical and chemical properties of chickpeas gamma irradiated with 60Co at doses of 0,50,kGy were investigated. Irradiation between 0 and 20,kGy had no significant effect on the hydration capacity of the chickpeas; however, increasing the dose from 20 to 50,kGy significantly decreased the hydration capacity owing to leaching of soluble compounds from the cotyledon to the water. There was an improvement in cooking quality (defined as degree of softness) with increased irradiation. Gelatinisation properties of the starch (measured with a Rapid Visco-Analyser) exhibited a deterioration with increasing irradiation dose, while reversed phase HPLC identified a sequential decrease in low-molecular-weight protein composition with increasing irradiation dose. © 2002 Society of Chemical Industry [source] Color centers in Yb:YAG crystals grown by temperature-gradient techniquesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2006Yongjun Dong Abstract Yb:YAG (Yb:Y3Al5O12) crystals have been grown by temperature-gradient techniques (TGT) and their color centers and impurity defects were investigated by means of gamma irradiations and thermal treatment. Two color centers located at 255 and 290 nm were observed in the as-grown TGT-Yb:YAG. Analysis shows that the 255 nm band may be associated with Fe3+ ions. Absorption intensity changes of the 290 nm band after gamma irradiation and thermal treatment indicate that this band may be associated with oxygen-vacancy defects. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optical absorption, paramagnetic resonance and depolarisation currents in MgAl2O4 spinelPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2007Roberto Paiva Abstract Optical Absorption (OA), Electron Paramagnetic Resonance (EPR) and Thermally Stimulated Depolarisation Currents (TSDC) techniques were applied to study the effects of irradiation and thermal treatments in the formation, aggregation and destruction processes of dipole defects in MgAl2O4 spinel. Irradiated MgAl2O4 crystals present two OA bands centred at 3.4 eV and 5.1 eV. The 3.4 eV band increases with the irradiation-dose, stabilizes its maximum height for doses near 10 kGy and is completely destroyed for thermal treatments above 500 K. This same band decays when the sample is maintained at room temperature reaching a constant value after a few weeks. The EPR spectrum is composed by two superimposed bands at g = 2.011. The gamma dose dependence, the thermal treatments between 370 K and 500 K and the thermal decay of the two bands at room temperature, show that each band behaves in a different way thus indicating that they are associated with two different defects. Gamma dose of 10 kGy produces a TSDC band at 245 K. When the sample is maintained at room temperature, after the gamma irradiation, for several weeks, a displacement in the peak position to 290 K, is observed. Thermal treatments above 500 K destroy the 290 K band. This band is associated to at least two V-type centres. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Protection of DNA and microsomal membranes in vitro by Glycyrrhiza glabra L. against gamma irradiationPHYTOTHERAPY RESEARCH, Issue 6 2002T. K. Shetty Abstract The radioprotective effect of the root extract of Glycyrrhiza glabra L on lipid peroxidation in rat liver microsomes and plasmid pBR322 DNA was investigated. The extract was found to protect microsomal membranes, as evident from reduction in lipid peroxidation, and could also protect plasmid DNA from radiation-induced strand breaks. Copyright © 2002 John Wiley & Sons, Ltd. [source] Methacryloxyethyl phosphate-grafted expanded polytetrafluoroethylene membranes for biomedical applicationsPOLYMER INTERNATIONAL, Issue 12 2005Edeline Wentrup-Byrne Abstract Expanded polytetrafluoroethylene (ePTFE) membranes were modified by graft copolymerization with methacryloxyethyl phosphate (MOEP) in methanol and 2-butanone (methyl ethyl ketone (MEK)) at ambient temperature using gamma irradiation. The effect of dose rate (0.46 and 4.6 kGy h,1), monomer concentration (1,40 %) and solvent were studied and the modified membranes were characterized by weight increase, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). XPS was used to determine the % degree of surface coverage using the CF (ePTFE membrane) and the CC (MOEP graft copolymer) peaks. Grafting yield, as well as surface coverage, were found to increase with increasing monomer concentration and were significantly higher for samples grafted in MEK than in methanol solution. SEM images showed distinctly different surface morphologies for the membranes grafted in methanol (smooth) and MEK (globular), hence indicating phase separation of the homopolymer in MEK. We propose that in our system, the non-solvent properties of MEK for the homopolymer play a more important role than solvent chain transfer reactions in determining grafting outcomes. Copyright © 2005 Society of Chemical Industry [source] Yielding behaviour of thermoplastic/elastomer blends cured by gamma irradiationPOLYMER INTERNATIONAL, Issue 3 2001A Shaltout Abstract Mechanical blends of thermoplastic medium density polyethylene (MDPE) and elastomeric ethylene propylene diene monomer (EPDM) have been prepared with a fixed composition of 60/40,wt%. They have been used either in their gum form or loaded with two different reinforcing fillers, high abrasion furnace (HAF) carbon black or precipitated SiO2 (Hi Sil) of concentration 25,100,phr (parts per hundred parts of resin) with respect to the blend. Curing was achieved by gamma irradiation. Yielding properties (yield stress, yield strain and cold drawing) have been followed as a function of irradiation dose for different blend compositions. Yield stress values increased with irradiation dose and with the content of the reinforcing filler, but yield strain and cold drawing values decreased with irradiation dose and also with the filler content. The data obtained reveal that Hi Sil is more effective as a reinforcing filler, and the prepared blends are suitable for load-bearing applications. © 2001 Society of Chemical Industry [source] | ||||||||||||||||||||||