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Sample records for cells gamma radiation

  1. Influence on cell proliferation of background radiation or exposure to very low, chronic gamma radiation. [Paramecium tetraurelia; Synechococcus lividus

    SciTech Connect

    Planel, H.; Soleilhavoup, J.P.; Tixador, R.; Richoilley, G.; Conter, A.; Croute, F.; Caratero, C.; Gaubin, Y.

    1987-05-01

    Investigations carried out on the protozoan Paramecium tetraurelia and the cyanobacteria Synechococcus lividus, which were shielded against background radiation or exposed to very low doses of gamma radiation, demonstrated that radiation can stimulate the proliferation of these two single-cell organisms. Radiation hormesis depends on internal factors (age of starting cells) and external factors (lighting conditions). The stimulatory effect occurred only in a limited range of doses and disappeared for dose rates higher than 50 mGy/y.

  2. Interactions between endothelial cells and T cells modulate responses to mixed neutron/gamma radiation.

    PubMed

    Cary, Lynnette H; Noutai, Daniel; Salber, Rudolph E; Williams, Margaret S; Ngudiankama, Barbara F; Whitnall, Mark H

    2014-06-01

    Detonation of an improvised nuclear device near a population center would cause significant casualties from the acute radiation syndrome (ARS) due to exposure to mixed neutron/gamma fields (MF). The pathophysiology of ARS involves inflammation, microvascular damage and alterations in immune function. Interactions between endothelial cells (EC) and hematopoietic cells are important not only for regulating immune cell traffic and function, but also for providing the microenvironment that controls survival, differentiation and migration of hematopoietic stem and progenitor cells in blood-forming tissues. Endothelial cells/leukocyte interactions also influence tumor progression and the results of anticancer therapies. In this study, we hypothesized that irradiation of endothelial cells would modulate their effects on hematopoietic cells and vice versa. Human umbilical vein endothelial cells (HUVEC) and immortalized T lymphocytes (Jurkat cells) were cultured individually and in co-culture after exposure to mixed fields. Effects of nonirradiated cells were compared to effects of irradiated cells and alterations in signaling pathways were determined. Mitogen-activated protein kinases (MAPKs) p38 and p44/42 (ERK1/2) in HUVEC exhibited higher levels of phosphorylated protein after exposure to mixed field radiation. IL-6, IL-8, G-CSF, platelet derived growth factor (PDGF) and angiopoietin 2 (ANG2) protein expression were upregulated in HUVEC by exposure to mixed field radiation. PCR arrays using HUVEC mRNA revealed alterations in gene expression after exposure to mixed fields and/or co-culture with Jurkat cells. The presence of HUVEC also influenced the function of Jurkat cells. Nonirradiated Jurkat cells showed an increase in proliferation when co-cultured with nonirradiated HUVEC, and a decrease in proliferation when co-cultured with irradiated HUVEC. Additionally, nonirradiated Jurkat cells incubated in media from irradiated HUVEC exhibited upregulation of activated caspase 3. Irradiation of Jurkat cells caused a G2/M arrest and increased adherence to HUVEC. When co-cultured with HUVEC, irradiated Jurkat cells exhibited G0/G1 arrest and increased apoptosis. The data indicate that gene expression and cell function of endothelial cells and hematopoietic cells are influenced by radiation and by interactions between the two cell types. These phenomena may affect the success of therapies for ARS and cancer. PMID:24828109

  3. Effect of gamma radiation on sodium channels in different conformations in neuroblastoma cells

    SciTech Connect

    Freschi, J.E.; Moran

    1986-01-01

    The dose-response relationship between gamma radiation and batrachotoxin-stimulated sodium influx in neuroblastoma cells in tissue culture was studied. Also tested was the hypothesis that changes in sodium-channel conformation may alter the radiosensitivity of the channel. It was found that gamma radiation inhibited toxin-stimulated /sup 22/Na uptake at doses beyond a threshold of 200-300 Gy. No effects were seen following doses below 100 Gy. This inhibition of sodium permeability was seen when the cells were irradiated with sodium channels in the closed or inactivated, nonconducting states. However, when the channels were in the toxin-opened, conducting state, gamma radiation had no effect at doses up to 2000 Gy. Results support earlier electrophysiological studies that showed that high doses of ionizing radiation are required to produce a measureable decrease in sodium permeability. In addition, the data suggest that by changing the sodium-channel conformation, batrachotoxin appears to alter radiosensitive chemical bonds in the gating or ion-conducting portion of the channel.

  4. Gamma radiation increases endonuclease-dependent L1 retrotransposition in a cultured cell assay

    PubMed Central

    Farkash, Evan A.; Kao, Gary D.; Horman, Shane R.; Prak, Eline T. Luning

    2006-01-01

    Long Interspersed Elements (LINE-1s, L1s) are the most active mobile elements in the human genome and account for a significant fraction of its mass. The propagation of L1 in the human genome requires disruption and repair of DNA at the site of integration. As Barbara McClintock first hypothesized, genotoxic stress may contribute to the mobilization of transposable elements, and conversely, element mobility may contribute to genotoxic stress. We tested the ability of genotoxic agents to increase L1 retrotransposition in a cultured cell assay. We observed that cells exposed to gamma radiation exhibited increased levels of L1 retrotransposition. The L1 retrotransposition frequency was proportional to the number of phosphorylated H2AX foci, an indicator of genotoxic stress. To explore the role of the L1 endonuclease in this context, endonuclease-deficient tagged L1 constructs were produced and tested for their activity in irradiated cells. The activity of the endonuclease-deficient L1 was very low in irradiated cells, suggesting that most L1 insertions in irradiated cells still use the L1 endonuclease. Consistent with this interpretation, DNA sequences that flank L1 insertions in irradiated cells harbored target site duplications. These results suggest that increased L1 retrotransposition in irradiated cells is endonuclease dependent. The mobilization of L1 in irradiated cells potentially contributes to genomic instability and could be a driving force for secondary mutations in patients undergoing radiation therapy. PMID:16507671

  5. Evaluation of genotoxicity of the acute gamma radiation on earthworm Eisenia fetida using single cell gel electrophoresis technique (Comet assay).

    PubMed

    Sowmithra, K; Shetty, N J; Jha, S K; Chaubey, R C

    2015-12-01

    Earthworms (Eisenia fetida) most suitable biological indicators of radioactive pollution. Radiation-induced lesions in DNA can be considered to be molecular markers for early effects of ionizing radiation. Gamma radiation produces a wide spectrum of DNA. Some of these lesions, i.e., DNA strand breaks and alkali labile sites can be detected by the single-cell gel electrophoresis (SCGE) or comet assay by measuring the migration of DNA from immobilized nuclear DNA. E. fetida were exposed to different doses of gamma radiation, i.e., 1, 5, 10, 20, 30, 40 and 50Gy, and comet assay was performed for all the doses along with control at 1, 3 and 5h post irradiation to evaluate the genotoxicity of gamma radiation in this organism. The DNA damage was measured as percentage of comet tail DNA. A significant increase in DNA damage was observed in samples exposed to 5Gy and above, and the increase in DNA damage was dose dependent i.e., DNA damage was increased with increased doses of radiation. The highest DNA damage was noticed at 1h post irradiation and gradually decreased with time, i.e., at 3 and 5h post irradiation. The present study reveals that gamma radiation induces DNA damage in E. fetida and the comet assay is a sensitive and rapid method for its detection to detect genotoxicity of gamma radiation. PMID:26653984

  6. Gamma radiation alters cell cycle and induces apoptosis in p53 mutant E6.1 Jurkat cells.

    PubMed

    Ahmadianpour, Mohammad Reza; Abdolmaleki, Parviz; Mowla, Seyed Javad; Hosseinkhani, Saman

    2013-01-01

    This study aimed at investigating the effect of gamma radiation with 1.5, 3.0 and 7.5 Gy doses on apoptosis induction, cell cycle alteration and increment of amount of p-ATM (phosphorylated ATM) and p-E2F1 (phosphorylated E2F1) proteins in Jurkat T-lymphoblastoid E6.1 cells. Exposure of human p53 mutant Jurkat cells to gamma radiation resulted in apoptosis, which was detected by luminometric and flow cytometric analysis. Also, phosphorylated ATM (ataxia telangiectasia mutated) and E2F1 (elongation factor) proteins were detected by western blot analysis. Based on luminescence detection data the lethal dose of 7.5 Gy induced cell death 12 h after exposure (p<0.05) while sub-lethal doses of 1.5 and 3.0 Gy induced apoptosis 18 h after exposure (p<0.05). Flow cytometric analysis revealed a G2 arrest 24h after exposure to 3.0 and 7.5 Gy. This arrest was accompanied by cell death with an increasing rate of occurrence up to 72 h after exposure. Western blot analysis showed that 1 h after cell irradiation by 1.5, 3.0 and 7.5 Gy, the amount of p-ATM increased to its maximum rate and remained constant up to 6 h, and then it decreased. Moreover, the amount of phosphorylated E2F1 (Ser-31) increased 2 h after exposure to the same doses and remained constant up to 12 h after irradiation. Survival and cell division of treated Jurkat cells showed a decrease compared to the control group. We believe that ionizing radiation-induced DNA damage activates a p53-independent apoptosis pathway via back-up systems in which the phosphorylation of ATM and E2F1 proteins was involved. Thus, gamma radiation can induce apoptosis and cell cycle alteration in Jurkat cells via a P53-independent pathway. PMID:23079488

  7. Mutant quantity and quality in mammalian cells (AL) exposed to cesium-137 gamma radiation: effect of caffeine

    NASA Technical Reports Server (NTRS)

    McGuinness, S. M.; Shibuya, M. L.; Ueno, A. M.; Vannais, D. B.; Waldren, C. A.; Chatterjee, A. (Principal Investigator)

    1995-01-01

    We examined the effect of caffeine (1,3,7-trimethylxanthine) on the quantity and quality of mutations in cultured mammalian AL human-hamster hybrid cells exposed to 137Cs gamma radiation. At a dose (1.5 mg/ml for 16 h) that reduced the plating efficiency (PE) by 20%, caffeine was not itself a significant mutagen, but it increased by approximately twofold the slope of the dose-response curve for induction of S1- mutants by 137Cs gamma radiation. Molecular analysis of 235 S1- mutants using a series of DNA probes mapped to the human chromosome 11 in the AL hybrid cells revealed that 73 to 85% of the mutations in unexposed cells and in cells treated with caffeine alone, 137Cs gamma rays alone or 137Cs gamma rays plus caffeine were large deletions involving millions of base pairs of DNA. Most of these deletions were contiguous with the region of the MIC1 gene at 11p13 that encodes the S1 cell surface antigen. In other mutants that had suffered multiple marker loss, the deletions were intermittent along chromosome 11. These "complex" mutations were rare for 137Cs gamma irradiation (1/63 = 1.5%) but relatively prevalent (23-50%) for other exposure conditions. Thus caffeine appears to alter both the quantity and quality of mutations induced by 137Cs gamma irradiation.

  8. AET reduces the frequency of micronuclei in bone marrow cells of mice exposed to. gamma. radiation

    SciTech Connect

    Garriott, M.L.; Crowe, D.T.

    1983-01-01

    The purpose of this paper was to determine whether or not a radioprotective agent which binds to DNA and inhibits DNA damage could also provide protection against radiation-induced micronuclei. Male mice were injected intraperitoneally with such an agent, 2-aminoethylisothiouronium bromide hydrobromide (AET), or its solvent 15 min prior to a single 10-min exposure to /sup 60/Co ..gamma.. rays delivered at various dose rates. Animals were killed 24 hr after irradiation and examined for the frequency of polychromatic erythrocytes containing micronuclei. The results showed a significant dose response to the irradiation for both treatments and a significant reduction in the frequency of micronucleated cells in the mice receiving the radioprotective agent.

  9. AET reduces the frequency of micronuclei in bone marrow cells of mice exposed to gamma radiation

    SciTech Connect

    Garriott, M.L.; Crowe, D.T.

    1983-01-01

    The purpose of this paper was to determine whether or not a radioprotective agent which binds to DNA and inhibits DNA damage could also provide protection against radiation-induced micronuclei. Male mice were injected intraperitoneally with such an agent, 2-aminoethylisothiouronium bromide hydrobromide (AET), or its solvent 15 min prior to a single 10-min exposure to /sup 60/Co gamma rays delivered at various dose rates. Animals were killed 24 hr after irradiation and examined for the frequency of polychromatic erythrocytes containing micronuclei. The results showed a significant dose response to the irradiation for both treatments and a significant reduction in the frequency of micronucleated cells in the mice receiving the radioprotective agent.

  10. Comparison of sister chromatid exchange induction in murine germinal and somatic cells by gamma radiation exposure in vivo

    SciTech Connect

    Morales-Ramirez, P.; Mendiola-Cruz, M.T.; Vallarino-Kelly, T.; Rodriguez-Reyes, R.

    1994-12-31

    Sister chromatid exchange (SCE) induction by gamma rays was determined in speratogonia irradiated before or after BrdU incorporation. Furthermore, the comparison of responses obtained in spermatogonia, bone marrow and salivary gland cells was carried out in the cells irradiated after BrdU incorporation, a condition which permits a higher SCE induction. Results indicate that gamma ray exposure of spermatogonia could induce a significant increase in SCE frequency with doses as low as 0.27 Gy, either before or after BrdU incorporation. However, the increase caused by radiation exposure after BrdU incorporation in spermatogonia was nearly three times lower than that obtained in both bone marrow and salivary gland cells. These data suggest that spermatogonia are either more efficient in repairing the gamma ray-induced lesions involved in SCE production or that these cells are less prone to the induction of such lesions. 53 refs., 2 figs., 3 tabs.

  11. CHO cell repair of single-strand and double-strand DNA breaks induced by gamma- and alpha-radiations.

    PubMed

    Cole, A; Shonka, F; Corry, P; Cooper, W G

    1975-01-01

    Neutral and alkaline sucrose gradient sedimentation analysis was used to measure double- and single-strand breaks in the DNA of Chinese hamster ovary (CHO) cells exposed to either gamma- or alpha-radiation. After irradiation, cells were incubated for 15-180 min to test the ability of the cell to rejoin the DNA breaks. Essentially complete rejoining was observed for single-strand breaks induced by gamma- or alpha-doses below 20 krad and for double-strand breaks induced by gamma doses below 60 krad. Approximately 80% rejoining was observed for double-strand breaks induced by alpha doses below 40 krad. At higher doses, the repair system appeared to saturate in such a way that essentially no additional breaks were rejoined. PMID:1191188

  12. Mutant quantity and quality in mammalian cells (A{sub L}) exposed to cesium-137 gamma radiation: Effect of caffeine

    SciTech Connect

    McGuinness, S.M.; Shibuya, M.L.; Ueno, A.M.

    1995-06-01

    We examined the effect of caffeine (1,3,7-trimethylxanthine) on the quantity and quality of mutations in cultured mammalian A{sub L} human-hamster hybrid cells exposed to {sup 137}Cs {gamma} radiation. At a dose (1.5 mg/ml for 16 h) that reduced the plating efficiency (PE) by 20%, caffeine was not itself a significant mutagen, but it increased by approximately twofold the slope of the dose-response curve for induction of S1{sup {minus}} mutants by {sup 137}Cs {gamma} radiation. Molecular analysis of 235 S1{sup {minus}} mutants using a series of DNA probes mapped to the human chromosome 11 in the A{sub L} hybrid cells revealed that 73 to 85% of the mutations in unexposed cells and in cells treated with caffeine alone, {sup 137}Cs {gamma} rays alone or {sup 137}Cs {gamma} rays plus caffeine were large deletions involving millions of base pairs of DNA. Most of these deletions were contiguous with the region of the MIC1 gene at 11p13 that encodes the S1 cell surface antigen. In other mutants that had suffered multiple marker loss, the deletions were intermittent along chromosome 11. These {open_quotes}complex{close_quotes} mutations were rare for {sup 137}Cs {gamma} irradiation (1/63 = 1.5%) but relatively prevalent (23-50%) for other exposure conditions. Thus caffeine appears to alter both the quantity and quality of mutations induced by {sup 137}Cs {gamma} irradiation. 62 refs., 3 figs., 3 tabs.

  13. Diffuse gamma radiation

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Simpson, G. A.; Thompson, D. J.

    1977-01-01

    An examination of the intensity, energy spectrum, and spatial distribution of the diffuse gamma-radiation observed by SAS-2 satellite away from the galactic plane in the energy range above 35 MeV has shown that it consists of two components. One component is generally correlated with galactic latitudes, the atomic hydrogen column density was deduced from 21 cm measurements, and the continuum radio emission, believed to be synchrotron emission. It has an energy spectrum similar to that in the plane and joins smoothly to the intense radiation from the plane. It is therefore presumed to be of galactic origin. The other component is apparently isotropic, at least on a coarse scale, and has a steep energy spectrum. No evidence is found for a cosmic ray halo surrounding the galaxy in the shape of a sphere or oblate spheroid with galactic dimensions. Constraints for a halo model with significantly larger dimensions are set on the basis of an upper limit to the gamma-ray anisotropy.

  14. Gamma radiation induced cell cycle perturbations and DNA damage in Catla Catla as measured by flow cytometry.

    PubMed

    Anbumani, S; Mohankumar, Mary N

    2015-03-01

    Gamma radiation induced cell cycle perturbations and DNA damage in Catla catla were analyzed in erythrocytes at different time points using flow cytometry (FCM). Protracted exposure to radiation induced damage between days 12 and 45. Disturbances in cell cycle machinery, i.e., proportional increase and decrease in Gap0 or quiescent/Gap1 (G0/G1), Synthesis (S) and Gap2/Mitotic (G2/M) phases were observed at both acute and protracted treatments. Both acute and protracted exposures induced apoptosis with a notable significance between days 3 and 6 at protracted and on day 45 at acute doses. Fish exposed protractedly avail some DNA repair mechanisms than acutely exposed. This is the first study to analyze radiation induced DNA damage under laboratory conditions and suggests that flow cytometry can also be an alternate tool to screen genotoxicity induced by ionizing radiation in fish. PMID:25483367

  15. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H.

    1994-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  16. Gamma radiation field intensity meter

    DOEpatents

    Thacker, Louis H.

    1995-01-01

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode.

  17. Gamma radiation field intensity meter

    DOEpatents

    Thacker, L.H.

    1994-08-16

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  18. Gamma radiation field intensity meter

    DOEpatents

    Thacker, L.H.

    1995-10-17

    A gamma radiation intensity meter measures dose rate of a radiation field. The gamma radiation intensity meter includes a tritium battery emitting beta rays generating a current which is essentially constant. Dose rate is correlated to an amount of movement of an electroscope element charged by the tritium battery. Ionizing radiation decreases the voltage at the element and causes movement. A bleed resistor is coupled between the electroscope support element or electrode and the ionization chamber wall electrode. 4 figs.

  19. Molecular signals in antigen presentation. II. Activation of cytolytic cells in vitro after ultraviolet radiation or combined gamma and ultraviolet radiation treatment of antigen-presenting cells

    SciTech Connect

    Granstein, R.D.; Tominaga, A.; Mizel, S.B.; Parrish, J.A.; Greene, M.I.

    1984-05-01

    Murine low-density spleen cells have potent antigen-presenting ability in a hapten-specific cytolytic T lymphocyte (CTL) system using the hapten azobenzenearsonate (ABA). Exposure of these cells to 0.33 KJ/m/sup 2/ of ultraviolet radiation (UVR) after coupling to hapten results in markedly inhibited antigen-presenting function that can be substantially corrected or bypassed by interleukin 1 (IL 1). These results have been interpreted to reflect an inhibition of Lyt-1/sup +/ T cell activation by UVR-treated APC. Treatment of these cells sequentially with 1500 rad of ..gamma..-radiation (GR) prior to hapten coupling, followed by 0.33 KJ/m/sup 2/ of UVR radiation after coupling, results in an antigen-resenting defect only minimally improved by IL 1. However, partially purified interleukin 2 (IL 2) can completely bypass or correct this defect. Thus, combined Cr and UVR induces a different or more profound defect in APC function when compared to UVR alone. However, these cells do provide a signal(s) other than hapten necessary for CTL activation because ABA-coupled high density spleen cells do not activate CTL cells, even with the addition of IL 2. Fluorescence-activated cell sorter analysis demonstrates that exposure of these low density spleen cells to GP or UVR results in decreased I-A antigen expression at 24 hr; exposure to both GR and UVR results in a greater decrease in I-A antigen expression at 24 hr than either alone. The addition of nonhapten-coupled low-density APC partially reconstitutes the ability of combined GR/UVR-treated LD-APC to present antigen, and this effect is enhanced by the administration of exogenous IL 1.

  20. Analysis of white blood cell counts in mice after gamma- or proton-radiation exposure.

    PubMed

    Maks, Casey J; Wan, X Steven; Ware, Jeffrey H; Romero-Weaver, Ana L; Sanzari, Jenine K; Wilson, Jolaine M; Rightnar, Steve; Wroe, Andrew J; Koss, Peter; Gridley, Daila S; Slater, James M; Kennedy, Ann R

    2011-08-01

    In the coming decades human space exploration is expected to move beyond low-Earth orbit. This transition involves increasing mission time and therefore an increased risk of radiation exposure from solar particle event (SPE) radiation. Acute radiation effects after exposure to SPE radiation are of prime importance due to potential mission-threatening consequences. The major objective of this study was to characterize the dose-response relationship for proton and γ radiation delivered at doses up to 2 Gy at high (0.5 Gy/min) and low (0.5 Gy/h) dose rates using white blood cell (WBC) counts as a biological end point. The results demonstrate a dose-dependent decrease in WBC counts in mice exposed to high- and low-dose-rate proton and γ radiation, suggesting that astronauts exposed to SPE-like radiation may experience a significant decrease in circulating leukocytes. PMID:21476859

  1. Analysis of White Blood Cell Counts in Mice after Gamma- or Proton-Radiation Exposure

    PubMed Central

    Maks, Casey J.; Wan, X. Steven; Ware, Jeffrey H.; Romero-Weaver, Ana L.; Sanzari, Jenine K.; Wilson, Jolaine M.; Rightnar, Steve; Wroe, Andrew J.; Koss, Peter; Gridley, Daila S.; Slater, James M.; Kennedy, Ann R.

    2013-01-01

    In the coming decades human space exploration is expected to move beyond low-Earth orbit. This transition involves increasing mission time and therefore an increased risk of radiation exposure from solar particle event (SPE) radiation. Acute radiation effects after exposure to SPE radiation are of prime importance due to potential mission-threatening consequences. The major objective of this study was to characterize the dose–response relationship for proton and γ radiation delivered at doses up to 2 Gy at high (0.5 Gy/min) and low (0.5 Gy/h) dose rates using white blood cell (WBC) counts as a biological end point. The results demonstrate a dose-dependent decrease in WBC counts in mice exposed to high- and low-dose-rate proton and γ radiation, suggesting that astronauts exposed to SPE-like radiation may experience a significant decrease in circulating leukocytes. PMID:21476859

  2. Antioxidant, anticlastogenic and radioprotective effect of Coleus aromaticus on Chinese hamster fibroblast cells (V79) exposed to gamma radiation.

    PubMed

    Rao, B S Satish; Shanbhoge, R; Upadhya, D; Jagetia, G C; Adiga, S K; Kumar, P; Guruprasad, K; Gayathri, P

    2006-07-01

    Coleus aromaticus (Benth, Family: Laminaceae), Indian Oregano native to India and Mediterranean, is well known for its medicinal properties. A preliminary study was undertaken to elucidate in vitro free radical scavenging potential and inhibition of lipid peroxidation by C.aromaticus hydroalcoholic extract (CAE). Anti-clastogenic and radioprotective potential of CAE were studied using micronucleus assay after irradiating Chinese hamster fibroblast (V79) cells. CAE at 10, 20, 40, 60, 80, 100 and 120 mug/ml resulted in a dose-dependent increase in radical scavenging ability against various free radicals viz., 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), superoxide anion (O(2)(*-)), hydroxyl (OH(*)) and nitric oxide (NO(*)) generated in vitro. A maximum scavenging potential was noticed at 100 mug/ml and a saturation point was reached thereafter with the increasing doses of CAE. The free radical scavenging potential of the extract was in the order of DPPH > ABTS > Superoxide > Hydroxyl > Nitric oxide. CAE also exhibited a moderate inhibition of lipid peroxidation in vitro, with a maximum inhibition at 60 mug/ml (33%), attaining saturation at higher doses. The extract also rendered protection against radiation induced DNA damage, as evidenced by the significant (P < 0.05) decrease in the percentage of radiation-induced micronucleated cells (MN) and frequency of micronuclei (total). A maximum anticlastogneic effect/ radioprotection was noticed at a very low concentration i.e., 5 mug/ml of CAE, treated 1 h prior to 2 Gy of gamma radiation. A significant (P < 0.0001) anticlastogenic/radioprotective effect was also observed when the cells were treated with an optimum dose of CAE (5 mug/ml) 1 h prior to 0.5, 1, 2 and 4 Gy of gamma radiation compared with the respective radiation control groups. Overall, our results established an efficient antioxidant, anticlastogenic and radioprotective potential of CAE, which may be of great pharmacological importance. PMID:16735450

  3. Gamma radiation from radio pulsars

    NASA Technical Reports Server (NTRS)

    Ruderman, Malvin

    1990-01-01

    The probable magnetospheric location and source of the gamma ray emission from some young radiopulsars is discussed. The suggested evolution of this emission as a function of pulsar period gives a diminished gamma-ray luminosity for a more rapidly spinning pre-Crab pulsar. A greatly enhanced one, similar to that of unidentified Cos B sources, is predicted for a slightly slower post-Vela pulsar, followed by a relatively rapid quenching of the gamma-ray luminosity at still longer periods. Possible anomalous exo-magnetospheric pulsed MeV and TeV-PeV radiation from the Crab pulsar is considered.

  4. Treatment by gamma or electron radiation decreases cell wall and gossypol content of cottonseed meal

    NASA Astrophysics Data System (ADS)

    Nayefi, M.; Salari, S.; Sari, M.; Behgar, M.

    2014-06-01

    The current study evaluated the effect of gamma and beam treatment (up to 40 kGy) on chemical composition and gossypol content of cottonseed meal. Irradiation decreased the crude fiber content. Gamma and electron treatment decreased total and free gossypol content.

  5. Abdominal {gamma}-Radiation Induces an Accumulation of Function-Impaired Regulatory T Cells in the Small Intestine

    SciTech Connect

    Billiard, Fabienne; Buard, Valerie; Benderitter, Marc; Linard, Christine

    2011-07-01

    Purpose: To assess the frequency and the functional characteristics of one major component of immune tolerance, the CD4{sup +}FoxP3{sup +} regulatory T cells (Tregs) in a mouse model of abdominal irradiation. Methods and Materials: Mice were exposed to a single abdominal dose of {gamma}-radiation (10 Gy). We evaluated small intestine Treg infiltration by Foxp3 immunostaining and the functional suppressive activity of Tregs isolated from mesenteric lymph nodes. Results: Foxp3 immunostaining showed that radiation induced a long-term infiltration of the intestine by Tregs (levels 5.5 times greater than in controls). Co-culture of Tregs from mesenteric lymph nodes with CD4{sup +} effector cells showed that the Tregs had lost their suppressive function. This loss was associated with a significant decrease in the levels of Foxp3, TGF-{beta}, and CTLA-4 mRNA, all required for optimal Treg function. At Day 90 after irradiation, Tregs regained their suppressive activity as forkhead box P3 (Foxp3), transforming growth factor beta (TGF-{beta}), and cytotoxic T-lymphocyte antigen 4 (CTLA-4) expression returned to normal. Analysis of the secretory function of mesenteric lymph node Tregs, activated in vitro with anti-CD3/anti-CD28 Abs, showed that this dysfunction was independent of a defect in interleukin-10 secretion. Conclusion: Radiation caused a long-term accumulation of function-impaired Foxp3{sup +}CD4{sup +} Tregs in the intestine. Our study provides new insights into how radiation affects the immune tolerance in peripheral tissues.

  6. Combination of PTEN and {gamma}-Ionizing Radiation Enhances Cell Death and G{sub 2}/M Arrest Through Regulation of AKT Activity and p21 Induction in Non-Small-Cell Lung Cancer Cells

    SciTech Connect

    Park, Jong Kuk; Jung, Hae-Yun; Park, Seon Ho; Kang, Seung Yi; Yi, Mi-Rang; Um, Hong Duck; Hong, Sung Hee

    2008-04-01

    Purpose: To identify the role of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) during {gamma}-ionizing radiation ({gamma}-IR) treatment for non-small-cell lung cancer cells. Methods and Materials: Wild-type PTEN or mutant forms of PTEN plasmids were transfected to construct stable transfectants of the NCI-H1299 non-small-cell lung cancer cell line. Combined effects of PTEN expression and IR treatment were tested using immunoblot, clonogenic, and cell-counting assays. Related signaling pathways were studied with immunoblot and kinase assays. Results: At steady state, stable transfectants showed almost the same proliferation rate but had different AKT phosphorylation patterns. When treated with {gamma}-IR, wild-type PTEN transfectants showed higher levels of cell death compared with mock vector or mutant transfectants, and showed increased G{sub 2}/M cell-cycle arrest accompanied by p21 induction and CDK1 inactivation. NCI-H1299 cells were treated with phosphosinositide-3 kinase (PI3K)/AKT pathway inhibitor (LY29002), resulting in reduced AKT phosphorylation levels. Treatment of NCI-H1299 cells with LY29002 and {gamma}-IR resulted in increased cell-cycle arrest and p21 induction. Endogenous wild-type PTEN-containing NCI-H460 cells were treated with PTEN-specific siRNA and then irradiated with {gamma}-IR: however reduced PTEN levels did not induce cell-cycle arrest or p21 expression. Conclusions: Taken together, these findings indicate that PTEN may modulate cell death or the cell cycle via AKT inactivation by PTEN and {gamma}-IR treatment. We also propose that a PTEN-PI3K/AKT-p21-CDK1 pathway could regulate cell death and the cell cycle by {gamma}-IR treatment.

  7. Gamma radiation-induced single strand breaks in DNA and their repair in spheroplasts and nuclei of light-grown and dark-grown Euglena cells.

    PubMed

    Netrawali, M S; Nair, K A

    1983-01-01

    Exposure of light-grown and dark-grown Euglena cells to gamma radiation causes single strand breaks in nuclear DNA as assessed by sedimentation analysis in alkaline sucrose density gradients. The number of radiation-induced single strand breaks in nuclear DNA of light-grown cells is found to be less than that in dark-grown cells. Post-irradiation incubation of both types of cells in 0 . 1 M phosphate buffer, pH 7 . 0 at 25 degrees C for 1 hour results in restitution of the strand breaks in DNA. Light-grown cells (cells with chloroplasts) are able to rejoin all the single strand breaks in DNA produced by gamma irradiation at D50 and D5 doses. On the other hand, dark-grown cells (cells devoid of chloroplasts) are unable to rejoin all the strand breaks caused by irradiation at either of the doses. The rate of DNA repair in dark-grown cells is also much slower than that in light-grown cells. Radiation-induced single strand breaks in DNA and their repair in nuclei from both types of cells is found to be similar to that observed in the spheroplasts. It is suggested that some factor(s) elaborated by chloroplasts may contribute towards the efficiency of nuclear DNA repair in Euglena cells. PMID:6403482

  8. Effects of low-dose radiation on gene expression in Syrian hamster embryo cells: Comparison of JANUS neutrons and gamma rays

    SciTech Connect

    Woloschak, G.E.; Chang-Liu, C.M.

    1992-07-01

    Past work by or group and others has shown the modulation of specific genes following exposure of cells to ionizing radiation. Many classes of genes have been found to be modulated in response to ionizing radiation, including those encoding cytoskeletal elements, cell growth arresting proteins, cytokines, and cellular oncogenes. The functions of this specific modulation of gene expression are currently being investigated by several groups: it has been suggested that gene modulation in response to radiation plays a role in the cellular repair of DNA damage, cell survival, or cellular transformation. Several groups have examined induction of nuclear proto-oncogenes following exposure to DNA-damaging agents. In all experiments, we examined modulation of gene expression by ionizing radiations in Syrian hamster embryo (SHE) fibroblasts, which are normal diploid cells that can be neoplastically transformed by low doses of ionizing radiations. Cells plated in 100-mm Petri plates containing 10 ml of medium were irradiated with {sup 60}C {gamma}-rays or fission-spectrum neutrons (0.85 MeV) from the JANUS reactor. All irradiations were performed at 37{degrees}C on cycling cells; equitoxic doses of neutrons and {gamma}-rays were selected on the basis of survival data.

  9. Effects of low-dose radiation on gene expression in Syrian hamster embryo cells: Comparison of JANUS neutrons and gamma rays

    SciTech Connect

    Woloschak, G.E.; Chang-Liu, C.M.

    1992-01-01

    Past work by or group and others has shown the modulation of specific genes following exposure of cells to ionizing radiation. Many classes of genes have been found to be modulated in response to ionizing radiation, including those encoding cytoskeletal elements, cell growth arresting proteins, cytokines, and cellular oncogenes. The functions of this specific modulation of gene expression are currently being investigated by several groups: it has been suggested that gene modulation in response to radiation plays a role in the cellular repair of DNA damage, cell survival, or cellular transformation. Several groups have examined induction of nuclear proto-oncogenes following exposure to DNA-damaging agents. In all experiments, we examined modulation of gene expression by ionizing radiations in Syrian hamster embryo (SHE) fibroblasts, which are normal diploid cells that can be neoplastically transformed by low doses of ionizing radiations. Cells plated in 100-mm Petri plates containing 10 ml of medium were irradiated with {sup 60}C {gamma}-rays or fission-spectrum neutrons (0.85 MeV) from the JANUS reactor. All irradiations were performed at 37{degrees}C on cycling cells; equitoxic doses of neutrons and {gamma}-rays were selected on the basis of survival data.

  10. Gamma radiation characteristics of plutonium dioxide fuel

    NASA Technical Reports Server (NTRS)

    Gingo, P. J.

    1969-01-01

    Investigation of plutonium dioxide as an isotopic fuel for Radioisotope Thermoelectric Generators yielded the isotopic composition of production-grade plutonium dioxide fuel, sources of gamma radiation produced by plutonium isotopes, and the gamma flux at the surface.

  11. Diffuse X and gamma radiation.

    NASA Technical Reports Server (NTRS)

    Silk, J.

    1973-01-01

    The most reliable measurements in the energy range from 0.1 MeV to 100 MeV are presented in graphs. Studies in the region from 1 keV to 100 keV are discussed, giving attention to nonthermal mechanisms, thermal emission from a uniform intergalactic medium, the contribution of discrete extragalactic sources to the isotropic X-ray background, discrete diffuse X-ray sources in galaxy clusters, the contribution of galaxy clusters to the isotropic X-ray background, and fluctuations in the X-ray background. Diffuse X rays below 1 keV are also considered together with diffuse galactic X and gamma rays above 1 keV and the significance of diffuse X and gamma radiation for astronomy.

  12. Virtual Gamma Ray Radiation Sources through Neutron Radiative Capture

    SciTech Connect

    Scott Wilde, Raymond Keegan

    2008-07-01

    The countrate response of a gamma spectrometry system from a neutron radiation source behind a plane of moderating material doped with a nuclide of a large radiative neutron capture cross-section exhibits a countrate response analogous to a gamma radiation source at the same position from the detector. Using a planar, surface area of the neutron moderating material exposed to the neutron radiation produces a larger area under the prompt gamma ray peak in the detector than a smaller area of dimensions relative to the active volume of the gamma detection system.

  13. Induction of macrophage antitumor activity by gamma radiation

    SciTech Connect

    Lambert, L.; Paulnock, D.M.

    1986-03-05

    The authors have developed a model system for examination of macrophage-mediated tumor cells lysis, using the murine macrophage tumor cell line RAW 264.7. These cells, like normal macrophages, exhibit a strict requirement for interaction with both interferon-..gamma.. (IFN-..gamma.., the priming signal) and bacterial lipopolysaccharide (LPS, the triggering signal) in the development of tumor cytolytic activity. In this system, the priming effects of IFN-..gamma.. decay rapidly following withdrawal of this mediator and the cells become unresponsive to LPS. They have recently observed that gamma radiation of the RAW 264.7 cells results in development of a primed state which is stable and responsive to LPS triggering for a least 48 hours. Irradiation-induced development of the primed phenotype is not solely the result of cytostatic effects as LPS treatment alone results in marked decreases in /sup 3/H-TdR incorporation in the absence of cytolytic potential. In addition to delivering the priming signal for tumor cytotoxicity, irradiation of this cell line results in changes in cell morphology that are typical of activation. Finally, treatment with irradiation results in increased cell surface expression of MHC-encoded Class I antigens; however, Class II antigen expression is not induced. Thus, the effects of gamma radiation on this cell line are strikingly similar to those resulting from incubation with IFN-..gamma...

  14. Protective Role of Hsp27 Protein Against Gamma Radiation-Induced Apoptosis and Radiosensitization Effects of Hsp27 Gene Silencing in Different Human Tumor Cells

    SciTech Connect

    Aloy, Marie-Therese Hadchity, Elie; Bionda, Clara; Diaz-Latoud, Chantal; Claude, Line; Rousson, Robert; Arrigo, Andre-Patrick; Rodriguez-Lafrasse, Claire

    2008-02-01

    Purpose: The ability of heat shock protein 27 (Hsp27) to protect cells from stressful stimuli and its increased levels in tumors resistant to anticancer therapeutics suggest that it may represent a target for sensitization to radiotherapy. In this study, we investigate the protective role of Hsp27 against radiation-induced apoptosis and the effect of its attenuation in highly expressing radioresistant cancer cell lines. Methods and Materials: We examined clonogenic death and the kinetics of apoptotic events in different tumor cell lines overexpressing or underexpressing Hsp27 protein irradiated with photons. The radiosensitive Jurkat cell line, which does not express Hsp27 constitutively or in response to {gamma}-rays, was stably transfected with Hsp27 complementary DNA. Attenuation of Hsp27 expression was accomplished by antisense or RNAi (interfering RNA) strategies in SQ20B head-and-neck squamous carcinoma, PC3 prostate cancer, and U87 glioblastoma radioresistant cells. Results: We measured concentration-dependent protection against the cytotoxic effects of radiation in Jurkat-Hsp27 cells, which led to a 50% decrease in apoptotic cells at 48 hours in the highest expressing cells. Underlying mechanisms leading to radiation resistance involved a significant increase in glutathione levels associated with detoxification of reactive oxygen species, a delay in mitochondrial collapse, and caspase activation. Conversely, attenuation of Hsp27 in SQ20B cells, characterized by their resistance to apoptosis, sensitizes cells to irradiation. This was emphasized by increased apoptosis, decreased glutathione basal level, and clonogenic cell death. Sensitization to irradiation was confirmed in PC3 and U87 radioresistant cells. Conclusion: Hsp27 gene therapy offers a potential adjuvant to radiation-based therapy of resistant tumors.

  15. Apparatus and method for detecting gamma radiation

    DOEpatents

    Sigg, Raymond A.

    1994-01-01

    A high efficiency radiation detector for measuring X-ray and gamma radiation from small-volume, low-activity liquid samples with an overall uncertainty better than 0.7% (one sigma SD). The radiation detector includes a hyperpure germanium well detector, a collimator, and a reference source. The well detector monitors gamma radiation emitted by the reference source and a radioactive isotope or isotopes in a sample source. The radiation from the reference source is collimated to avoid attenuation of reference source gamma radiation by the sample. Signals from the well detector are processed and stored, and the stored data is analyzed to determine the radioactive isotope(s) content of the sample. Minor self-attenuation corrections are calculated from chemical composition data.

  16. Apparatus and method for detecting gamma radiation

    DOEpatents

    Sigg, R.A.

    1994-12-13

    A high efficiency radiation detector is disclosed for measuring X-ray and gamma radiation from small-volume, low-activity liquid samples with an overall uncertainty better than 0.7% (one sigma SD). The radiation detector includes a hyperpure germanium well detector, a collimator, and a reference source. The well detector monitors gamma radiation emitted by the reference source and a radioactive isotope or isotopes in a sample source. The radiation from the reference source is collimated to avoid attenuation of reference source gamma radiation by the sample. Signals from the well detector are processed and stored, and the stored data is analyzed to determine the radioactive isotope(s) content of the sample. Minor self-attenuation corrections are calculated from chemical composition data. 4 figures.

  17. Dibasic calcium phosphate dihydrate, USP material compatibility with gamma radiation

    NASA Astrophysics Data System (ADS)

    Betancourt Quiles, Maritza

    Gamma radiation is a commonly used method to reduce the microbial bioburden in compatible materials when it is applied at appropriate dose levels. Gamma irradiation kills bacteria and mold by breaking down the organism’s DNA and inhibiting cell division. The purpose of this study is to determine the radiation dosage to be used to treat Dibasic Calcium Phosphate Dihydrate, USP (DCPD) and to evaluate its physicochemical effects if any, on this material. This material will be submitted to various doses of gamma radiation that were selected based on literature review and existing regulations that demonstrate that this method is effective to reduce or eliminate microbial bioburden in natural source and synthetic materials. Analytical testing was conducted to the DCPD exposed material in order to demonstrate that gamma radiation does not alter the physicochemical properties and material still acceptable for use in the manufacture of pharmaceutical products. The results obtained through this study were satisfactory and demonstrated that the gamma irradiation dosages from 5 to 30 kGy can be applied to DCPD without altering its physicochemical properties. These are supported by the Assay test data evaluation of lots tested before and after gamma irradiation implementation that show no significant statistical difference between irradiated and non irradiated assay results. The results of this study represent an achievement for the industry since they provide as an alternative the use of Gamma irradiation technology to control the microbial growth in DCPD.

  18. Relative Biological Effectiveness (RBE) of 131I Radiation Relative to 60Co Gamma Rays

    PubMed Central

    Neshasteh-Riz, Ali; Mahmoud Pashazadeh, Ali; Mahdavi, Seyed Rabie

    2013-01-01

    Objective: To assess relative biological effectiveness (RBE) of 131I radiation relative to 60Co gamma rays in glioblastoma spheroid cells. Materials and Methods: : In this experimental study, glioblastoma spheroid cells were exposed to 131I radiation and 60Co gamma rays. Radiation induced DNA damage was evaluated by alkaline comet assay. Samples of spheroid cells were treated by radiation from 131I for four different periods of time to find the dose-response equation. Spheroid cells were also exposed by 200 cGy of 60Co gamma rays as reference radiation to induce DNA damage as endpoint. Results: Resulted RBE of 131I radiation relative to 60Co gamma rays in 100 µm giloblastoma spheroid cells was equal to 1.16. Conclusion: The finding of this study suggests that 131I photons and electrons can be more effective than 60Co gamma rays to produce DNA damage in glioblastoma spheroid cells. PMID:24027663

  19. 30 CFR 57.5047 - Gamma radiation surveys.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Gamma radiation surveys. 57.5047 Section 57..., Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047 Gamma radiation surveys. (a) Gamma radiation surveys shall be conducted annually in all underground mines...

  20. 30 CFR 57.5047 - Gamma radiation surveys.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Gamma radiation surveys. 57.5047 Section 57..., Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047 Gamma radiation surveys. (a) Gamma radiation surveys shall be conducted annually in all underground mines...

  1. 30 CFR 57.5047 - Gamma radiation surveys.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Gamma radiation surveys. 57.5047 Section 57..., Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047 Gamma radiation surveys. (a) Gamma radiation surveys shall be conducted annually in all underground mines...

  2. 30 CFR 57.5047 - Gamma radiation surveys.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Gamma radiation surveys. 57.5047 Section 57..., Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047 Gamma radiation surveys. (a) Gamma radiation surveys shall be conducted annually in all underground mines...

  3. 30 CFR 57.5047 - Gamma radiation surveys.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Gamma radiation surveys. 57.5047 Section 57..., Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047 Gamma radiation surveys. (a) Gamma radiation surveys shall be conducted annually in all underground mines...

  4. Use of the comet assay to measure DNA damage in cells exposed to photosensitizers and gamma radiation

    NASA Astrophysics Data System (ADS)

    Pouget, J.-P.; Ravanat, J.-L.; Douki, T.; Richard, M.-J.; Cadet, J.

    1999-01-01

    We used the comet assay associated with DNA-glycosylases to estimate DNA damage in cells exposed to gamma irradiation or photosensitized either with methylene blue or orange acridine. A calibration performed using irradiation allowed the measurement of the steady-state level and the yield of 8-oxodGuo as well as strand breaks and alkali-labile sites. Nous avons utilisé la méthode des comètes associée à des ADN-glycosylases, pour estimer les dommages de l'ADN dans des cellules après l'exposition à un rayonnement gamma ou après photosensibilisation par le bleu de méthylène ou l'acridine orange. Une calibration de la méthode des comètes a permis de mesurer le niveau basal et les taux de formation de 8-oxodGuo ainsi que le nombre de cassures de brins et de sites alcali labiles.

  5. Low Dose Radiation Response Curves, Networks and Pathways in Human Lymphoblastoid Cells Exposed from 1 to 10 cGy of Acute Gamma Radiation

    SciTech Connect

    Wyrobek, A. J.; Manohar, C. F.; Nelson, D. O.; Furtado, M. R.; Bhattacharya, M. S.; Marchetti, F.; Coleman, M.A.

    2011-04-18

    We investigated the low dose dependency of the transcriptional response of human cells to characterize the shape and biological functions associated with the dose response curve and to identify common and conserved functions of low dose expressed genes across cells and tissues. Human lymphoblastoid (HL) cells from two unrelated individuals were exposed to graded doses of radiation spanning the range of 1-10 cGy were analyzed by transcriptome profiling, qPCR and bioinformatics, in comparison to sham irradiated samples. A set of {approx}80 genes showed consistent responses in both cell lines; these genes were associated with homeostasis mechanisms (e.g., membrane signaling, molecule transport), subcellular locations (e.g., Golgi, and endoplasmic reticulum), and involved diverse signal transduction pathways. The majority of radiation-modulated genes had plateau-like responses across 1-10 cGy, some with suggestive evidence that transcription was modulated at doses below 1 cGy. MYC, FOS and TP53 were the major network nodes of the low-dose response in HL cells. Comparison our low dose expression findings in HL cells with those of prior studies in mouse brain after whole body exposure, in human keratinocyte cultures, and in endothelial cells cultures, indicates that certain components of the low dose radiation response are broadly conserved across cell types and tissues, independent of proliferation status.

  6. Effects of gamma radiation on wastewater microbiota.

    PubMed

    Verde, Sandra Cabo; Silva, Telma; Matos, Paula

    2016-03-01

    Wastewater treatment by gamma radiation is a promising technology, with the capacity to reduce the impact of chemical and biological pollution of effluents in the environment. The aim of this study was to find out the effect of gamma radiation on the inactivation response of wastewater microorganisms. Wastewater samples were irradiated at a Co-60 facility, at different dose rates and at sublethal doses. The D10-values of total coliforms and mesophilic microbiota were determined for each sample and dose rate. Radio-resistant microorganisms in wastewater samples were isolated and their growth and inactivation kinetics in different composition substrates were determined, to find out the capacity of these bacteria to biodegrade the organic content of the wastewater. The results obtained suggest that irradiation substrate and dose rate influence the response of microorganisms to gamma radiation and could be also important factors for bioremediation. PMID:26370692

  7. Gamma ray emission from radiative supernova remnants

    NASA Astrophysics Data System (ADS)

    Asvarov, Abdul

    In this presentation we have considered Gamma-ray emission from supernova remnants (SNRs) evolving in high density environments, for which the radiative phase of evolution is more typical. Gamma-rays from such objects are believed to have hadronic origin, i.e. as a result of decay of neutral pi-mesons, created in the p-p collisions of relativistic hadrons (protons, etc.) with interstellar medium protons. DSA mechanism is considered as the main mechanism of acceleration of relativistic particles. We assume that SNR evolves in more or less homogeneous interstellar medium. This is contrary to two main models of origin of Gamma-rays from shell type SNRs, which are: 1) Runaway CR model which considers Gamma-ray emission from molecular clouds illuminated by runaway CRs that have escaped from the SNRs; 2) Crushed Cloud model, which considers the shocked interstellar clouds being responsible for the gamma-ray emission of the SNR. The considered model gives the largest conversion rate of SN energy to gamma-rays. It has been found that under certain (close to real) conditions considered here type of SNRs can easily provide the flux of gamma-rays with energies > 100 MeV, typical for the large number of unidentified sources listed in the recent Fermi LAT source catalog. We have obtained conditions under which SNRs are better observable in gamma-rays than in other bands of the electromagnetic spectrum.

  8. Gamma Radiation Doses In Sweden

    SciTech Connect

    Almgren, Sara; Isaksson, Mats; Barregaard, Lars

    2008-08-07

    Gamma dose rate measurements were performed in one urban and one rural area using thermoluminescence dosimeters (TLD) worn by 46 participants and placed in their dwellings. The personal effective dose rates were 0.096{+-}0.019(1 SD) and 0.092{+-}0.016(1 SD){mu}Sv/h in the urban and rural area, respectively. The corresponding dose rates in the dwellings were 0.11{+-}0.042(1 SD) and 0.091{+-}0.026(1 SD){mu}Sv/h. However, the differences between the areas were not significant. The values were higher in buildings made of concrete than of wood and higher in apartments than in detached houses. Also, {sup 222}Rn measurements were performed in each dwelling, which showed no correlation with the gamma dose rates in the dwellings.

  9. Gamma Radiation Doses In Sweden

    NASA Astrophysics Data System (ADS)

    Almgren, Sara; Barregârd, Lars; Isaksson, Mats

    2008-08-01

    Gamma dose rate measurements were performed in one urban and one rural area using thermoluminescence dosimeters (TLD) worn by 46 participants and placed in their dwellings. The personal effective dose rates were 0.096±0.019(1 SD) and 0.092±0.016(1 SD)μSv/h in the urban and rural area, respectively. The corresponding dose rates in the dwellings were 0.11±0.042(1 SD) and 0.091±0.026(1 SD)μSv/h. However, the differences between the areas were not significant. The values were higher in buildings made of concrete than of wood and higher in apartments than in detached houses. Also, 222Rn measurements were performed in each dwelling, which showed no correlation with the gamma dose rates in the dwellings.

  10. Gamma radiation effects on peanut skin antioxidants.

    PubMed

    de Camargo, Adriano Costa; de Souza Vieira, Thais Maria Ferreira; Regitano-D'Arce, Marisa Aparecida Bismara; Calori-Domingues, Maria Antonia; Canniatti-Brazaca, Solange Guidolin

    2012-01-01

    Peanut skin, which is removed in the peanut blanching process, is rich in bioactive compounds with antioxidant properties. The aims of this study were to measure bioactive compounds in peanut skins and evaluate the effect of gamma radiation on their antioxidant activity. Peanut skin samples were treated with 0.0, 5.0, 7.5, or 10.0 kGy gamma rays. Total phenolics, condensed tannins, total flavonoids, and antioxidant activity were evaluated. Extracts obtained from the peanut skins were added to refined-bleached-deodorized (RBD) soybean oil. The oxidative stability of the oil samples was determined using the Oil Stability Index method and compared to a control and synthetic antioxidants (100 mg/kg BHT and 200 mg/kg TBHQ). Gamma radiation changed total phenolic content, total condensed tannins, total flavonoid content, and the antioxidant activity. All extracts, gamma irradiated or not, presented increasing induction period (h), measured by the Oil Stability Index method, when compared with the control. Antioxidant activity of the peanut skins was higher than BHT. The present study confirmed that gamma radiation did not affect the peanut skin extracts' antioxidative properties when added to soybean oil. PMID:22489142

  11. Gamma Radiation Effects on Peanut Skin Antioxidants

    PubMed Central

    de Camargo, Adriano Costa; de Souza Vieira, Thais Maria Ferreira; Regitano-D’Arce, Marisa Aparecida Bismara; Calori-Domingues, Maria Antonia; Canniatti-Brazaca, Solange Guidolin

    2012-01-01

    Peanut skin, which is removed in the peanut blanching process, is rich in bioactive compounds with antioxidant properties. The aims of this study were to measure bioactive compounds in peanut skins and evaluate the effect of gamma radiation on their antioxidant activity. Peanut skin samples were treated with 0.0, 5.0, 7.5, or 10.0 kGy gamma rays. Total phenolics, condensed tannins, total flavonoids, and antioxidant activity were evaluated. Extracts obtained from the peanut skins were added to refined-bleached-deodorized (RBD) soybean oil. The oxidative stability of the oil samples was determined using the Oil Stability Index method and compared to a control and synthetic antioxidants (100 mg/kg BHT and 200 mg/kg TBHQ). Gamma radiation changed total phenolic content, total condensed tannins, total flavonoid content, and the antioxidant activity. All extracts, gamma irradiated or not, presented increasing induction period (h), measured by the Oil Stability Index method, when compared with the control. Antioxidant activity of the peanut skins was higher than BHT. The present study confirmed that gamma radiation did not affect the peanut skin extracts’ antioxidative properties when added to soybean oil. PMID:22489142

  12. Inspection of cargo containers using gamma radiation

    NASA Astrophysics Data System (ADS)

    Hussein, Esam M. A.; Gokhale, Prasad; Arendtsz, Nina V.; Lawrence, Andre H.

    1997-02-01

    This paper investigate, with the aid of Monte Carlo simulations and laboratory experiments, a technique for the detection of narcotics in large cargo containers using gamma-radiation. The transmission and back-scattering of photons, at different energies, is used to provide information useful for identifying the presence of bulk quantities of commonly encountered narcotics.

  13. Field Deployable Gamma Radiation Detectors for DHS Use

    SciTech Connect

    Sanjoy Mukhopadhyay

    2007-08-31

    Recently, the U.S. Department of Homeland Security (DHS) has integrated all nuclear detection research, development, testing, evaluation, acquisition, and operational support into a single office: the Domestic Nuclear Detection Office (DNDO). The DNDO has specific requirements set for all commercial and government off-the-shelf radiation detection equipment and data acquisition systems. This article would investigate several recent developments in field deployable gamma radiation detectors that are attempting to meet the DNDO specifications. Commercially available, transportable, handheld radio isotope identification devices (RIID) are inadequate for DHS’s requirements in terms of sensitivity, resolution, response time and reach back capability. The leading commercial vendor manufacturing handheld gamma spectrometer in the United States is Thermo Electron Corporation. Thermo Electron’s identiFINDER™, which primarily uses sodium iodide crystals (3.18-cm x 2.54-cm cylinders) as gamma detector, has a Full-Width-at-Half-Maximum energy resolution of 7 percent at 662 keV. Thermo Electron has just recently come up with a reach-back capability patented as RadReachBack™ that enables emergency personnel to obtain real-time technical analysis of radiation samples they find in the field. The current project has the goal to build a prototype handheld gamma spectrometer, equipped with a digital camera and an embedded cell phone to be used as an RIID with higher sensitivity (comparable to that of a 7.62-cm x 7.62-cm sodium iodide crystal at low gamma energy ranging from 30 keV to 3,000 keV), better resolution (< 3.0 percent at 662 keV), faster response time (able to detect the presence of gamma-emitting radio isotopes within 5 seconds of approach), which will make it useful as a field deployable tool. The handheld equipment continuously monitors the ambient gamma radiation and, if it comes across any radiation anomalies with higher than normal gamma gross counts, it sets an alarm condition. When a substantial alarm level is reached, the system auto triggers saving of relevant spectral data and software-triggers the digital camera to take a snapshot. The spectral data including in situ analysis and the imagery data will be packaged in a suitable format and sent to a command post using an imbedded cell phone.

  14. Composition and apparatus for detecting gamma radiation

    DOEpatents

    Hofstetter, K.J.

    1994-08-09

    A gamma radiation detector and a radioluminescent composition for use therein. The detector includes a radioluminescent composition that emits light in a characteristic wavelength region when exposed to gamma radiation, and means for detecting said radiation. The composition contains a scintillant such as anglesite (PbSO[sub 4]) or cerussite (PbCO[sub 3]) incorporated into an inert, porous glass matrix via a sol-gel process. Particles of radiation-sensitive scintillant are added to, a sol solution. The mixture is polymerized to form a gel, then dried under conditions that preserve the structural integrity and radiation sensitivity of the scintillant. The final product is a composition containing the uniformly-dispersed scintillant in an inert, optically transparent and highly porous matrix. The composition is chemically inert and substantially impervious to environmental conditions including changes in temperature, air pressure, and so forth. It can be fabricated in cylinders, blocks with holes therethrough for flow of fluid, sheets, surface coatings, pellets or other convenient shapes. 3 figs.

  15. Composition and apparatus for detecting gamma radiation

    DOEpatents

    Hofstetter, Kenneth J.

    1994-01-01

    A gamma radiation detector and a radioluminiscent composition for use therein. The detector includes a radioluminscent composition that emits light in a characteristic wavelength region when exposed to gamma radiation, and means for detecting said radiation. The composition contains a scintillant such as anglesite (PbSO.sub.4) or cerussite (PbCO.sub.3) incorporated into an inert, porous glass matrix via a sol-gel process. Particles of radiation-sensitive scintillant are added to, a sol solution. The mixture is polymerized to form a gel, then dried under conditions that preserve the structural integrity and radiation sensitivity of the scintillant. The final product is a composition containing the uniformly-dispersed scintillant in an inert, optically transparent and highly porous matrix. The composition is chemically inert and substantially impervious to environmental conditions including changes in temperature, air pressure, and so forth. It can be fabricated in cylinders, blocks with holes therethrough for flow of fluid, sheets, surface coatings, pellets or other convenient shapes.

  16. GammaCam{trademark} radiation imaging system

    SciTech Connect

    1998-02-01

    GammaCam{trademark}, a gamma-ray imaging system manufactured by AIL System, Inc., would benefit a site that needs to locate radiation sources. It is capable of producing a two-dimensional image of a radiation field superimposed on a black and white visual image. Because the system can be positioned outside the radiologically controlled area, the radiation exposure to personnel is significantly reduced and extensive shielding is not required. This report covers the following topics: technology description; performance; technology applicability and alternatives; cost; regulatory and policy issues; and lessons learned. The demonstration of GammaCam{trademark} in December 1996 was part of the Large-Scale Demonstration Project (LSDP) whose objective is to select and demonstrate potentially beneficial technologies at the Argonne National Laboratory-East (ANL) Chicago Pile-5 Research Reactor (CP-5). The purpose of the LSDP is to demonstrate that by using innovative and improved decontamination and decommissioning (D and D) technologies from various sources, significant benefits can be achieved when compared to baseline D and D technologies.

  17. Diverse delayed effects in human lymphoblastoid cells surviving exposure to high-LET (56)Fe particles or low-LET (137)Cs gamma radiation

    NASA Technical Reports Server (NTRS)

    Evans, H. H.; Horng, M. F.; Ricanati, M.; Diaz-Insua, M.; Jordan, R.; Schwartz, J. L.

    2001-01-01

    To obtain information on the origin of radiation-induced genomic instability, we characterized a total of 166 clones that survived exposure to (56)Fe particles or (137)Cs gamma radiation, isolated approximately 36 generations after exposure, along with their respective control clones. Cytogenetic aberrations, growth alterations, responses to a second irradiation, and mutant frequencies at the Na(+)/K(+) ATPase and thymidine kinase loci were determined. A greater percentage of clones that survived exposure to (56)Fe particles exhibited instability (defined as clones showing one or more outlying characteristics) than in the case of those that survived gamma irradiation. The phenotypes of the unstable clones that survived exposure to (56)Fe particles were also qualitatively different from those of the clones that survived gamma irradiation. A greater percentage (20%) of the unstable clones that survived gamma irradiation than those that survived exposure to (56)Fe particles (4%) showed an altered response to the second irradiation, while an increase in the percentage of clones that had an outlying frequency of ouabain-resistant and thymidine kinase mutants was more evident in the clones exposed to (56)Fe particles than in those exposed to gamma rays. Growth alterations and increases in dicentric chromosomes were found only in clones with more than one alteration. These results underscore the complex nature of genomic instability and the likelihood that radiation-induced genomic instability arises from different original events.

  18. Field Deployable Gamma Radiation Detectors for DHS Use

    SciTech Connect

    Sanjoy Mukhopadhyay

    2007-08-01

    Recently, the Department of Homeland Security (DHS) has integrated all nuclear detection research, development, testing, evaluation, acquisition, and operational support into a single office: the Domestic Nuclear Detection Office (DNDO). The DNDO has specific requirements set for all commercial off-the-shelf and government off-the-shelf radiation detection equipment and data acquisition systems. This article would investigate several recent developments in field deployable gamma radiation detectors that are attempting to meet the DNDO specifications. Commercially available, transportable, handheld radio isotope identification devices (RIID) are inadequate for DHS requirements in terms of sensitivity, resolution, response time, and reach-back capability. The leading commercial vendor manufacturing handheld gamma spectrometer in the United States is Thermo Electron Corporation. Thermo Electron's identiFINDER{trademark}, which primarily uses sodium iodide crystals (3.18 x 2.54cm cylinders) as gamma detectors, has a Full-Width-at-Half-Maximum energy resolution of 7 percent at 662 keV. Thermo Electron has just recently come up with a reach-back capability patented as RadReachBack{trademark} that enables emergency personnel to obtain real-time technical analysis of radiation samples they find in the field. The current project has the goal to build a prototype handheld gamma spectrometer, equipped with a digital camera and an embedded cell phone to be used as an RIID with higher sensitivity, better resolution, and faster response time (able to detect the presence of gamma-emitting radio isotopes within 5 seconds of approach), which will make it useful as a field deployable tool. The handheld equipment continuously monitors the ambient gamma radiation, and, if it comes across any radiation anomalies with higher than normal gamma gross counts, it sets an alarm condition. When a substantial alarm level is reached, the system automatically triggers the saving of relevant spectral data and software-triggers the digital camera to take a snapshot. The spectral data including in situ analysis and the imagery data will be packaged in a suitable format and sent to a command post using an imbedded cell phone.

  19. Afterglow Radiation from Gamma Ray Bursts

    SciTech Connect

    Desmond, Hugh; /Leuven U. /SLAC

    2006-08-28

    Gamma-ray bursts (GRB) are huge fluxes of gamma rays that appear randomly in the sky about once a day. It is now commonly accepted that GRBs are caused by a stellar object shooting off a powerful plasma jet along its rotation axis. After the initial outburst of gamma rays, a lower intensity radiation remains, called the afterglow. Using the data from a hydrodynamical numerical simulation that models the dynamics of the jet, we calculated the expected light curve of the afterglow radiation that would be observed on earth. We calculated the light curve and spectrum and compared them to the light curves and spectra predicted by two analytical models of the expansion of the jet (which are based on the Blandford and McKee solution of a relativistic isotropic expansion; see Sari's model [1] and Granot's model [2]). We found that the light curve did not decay as fast as predicted by Sari; the predictions by Granot were largely corroborated. Some results, however, did not match Granot's predictions, and more research is needed to explain these discrepancies.

  20. Satellite observation of atmospheric nuclear gamma radiation

    NASA Technical Reports Server (NTRS)

    Letaw, John R.; Share, G. H.; Kinzer, R. L.; Silberberg, R.; Chupp, E. L.

    1989-01-01

    Satellite observations of the spectrum of gamma radiation from the earth's atmosphere in the energy interval from 300 keV to 8.5 MeV were obtained with a gamma-ray spectrometer during 1980-1983. A total of 20 atmospheric line features are superimposed on a continuum background which is modeled using a power law with an index of -1.16. The line energies and intensities are consistent with production by secondary neutrons interacting with atmospheric N-14 and O-16. The intensity and spectrum of photons at energies below the 511-keV line, in excess of a power law continuum, are explained by Compton scattering of the annihilation line photons in traversing an average of 21 g/sq cm of atmosphere.

  1. Gamma radiation detectors for safeguards applications

    NASA Astrophysics Data System (ADS)

    Carchon, R.; Moeslinger, M.; Bourva, L.; Bass, C.; Zendel, M.

    2007-08-01

    The IAEA uses extensively a variety of gamma radiation detectors to verify nuclear material. These detectors are part of standardized spectrometry systems: germanium detectors for High-Resolution Gamma Spectrometry (HRGS); Cadmium Zinc Telluride (CZT) detectors for Room Temperature Gamma Spectrometry (RTGS); and NaI(Tl) detectors for Low Resolution Gamma Spectrometry (LRGS). HRGS with high-purity Germanium (HpGe) detectors cooled by liquid nitrogen is widely used in nuclear safeguards to verify the isotopic composition of plutonium or uranium in non-irradiated material. Alternative cooling systems have been evaluated and electrically cooled HpGe detectors show a potential added value, especially for unattended measurements. The spectrometric performance of CZT detectors, their robustness and simplicity are key to the successful verification of irradiated materials. Further development, such as limiting the charge trapping effects in CZT to provide improved sensitivity and energy resolution are discussed. NaI(Tl) detectors have many applications—specifically in hand-held radioisotope identification devices (RID) which are used to detect the presence of radioactive material where a lower resolution is sufficient, as they benefit from a generally higher sensitivity. The Agency is also continuously involved in the review and evaluation of new and emerging technologies in the field of radiation detection such as: Peltier-cooled CdTe detectors; semiconductor detectors operating at room temperature such as HgI 2 and GaAs; and, scintillator detectors using glass fibres or LaBr 3. A final conclusion, proposing recommendations for future action, is made.

  2. Radiation Sterilization and Food Irradiation Using Gamma Radiation

    NASA Astrophysics Data System (ADS)

    O'Hara, Kevin

    2003-03-01

    Since the introduction of MDS Nordion's first irradiator in the early 1960's, a variety of gamma-processing systems has been developed. Each design is suited to a particular set of requirements - from high-throughput operations of diverse product lots to full automation or batch processing, all using gamma radiation. Gamma irradiator designs include the Centurion irradiator for temperature-sensitive food products like hamburgers and poultry; the Brevion, a compact batch irradiator providing flexibility, timeliness and simplicity on a whole new scale; a JS-10000 irradiator that operates in either automatic or batch mode to enable multipurpose product scheduling and optimum throughput; and, an irradiator that processes full pallets and is ideal for processing high-density products requiring excellent dose uniformity. These innovative irradiator designs help facilities to be more efficient, maximize operating time, improve product turnaround and minimize inventory levels. MDS Nordion's development of improved Point Kernel and Monte Carlo techniques is discussed, including their application in radiation source optimization, production irradiator design and process control. Absorbed-dose calculations also provide insight into the critical areas for dose mapping and routine monitoring, allowing for the optimum placement of dosimeters. Calculations may also be used to determine the absorbed-dose distribution within product, especially in areas of complex geometry such as material interfaces. The use of easily accessible, accurate and validated dose-calculation programs can be used to optimize the irradiation process. Key Words: dosimetry, irradiator design, dose calculation, modelling, modeling, process control, radiation source optimization.

  3. 77 FR 62267 - Proposed Extension of Existing Information Collection; Gamma Radiation Surveys

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-12

    ... Safety and Health Administration Proposed Extension of Existing Information Collection; Gamma Radiation...: I. Background Gamma radiation occurs where radioactive materials are present. It has been associated..., and ground water. Gamma radiation hazards may be found near radiation sources at surface...

  4. Cell Radiation Experiment System

    NASA Technical Reports Server (NTRS)

    Morrison, Dennis R.

    2010-01-01

    The cell radiation experiment system (CRES) is a perfused-cell culture apparatus, within which cells from humans or other animals can (1) be maintained in homeostasis while (2) being exposed to ionizing radiation during controlled intervals and (3) being monitored to determine the effects of radiation and the repair of radiation damage. The CRES can be used, for example, to determine effects of drug, radiation, and combined drug and radiation treatments on both normal and tumor cells. The CRES can also be used to analyze the effects of radiosensitive or radioprotectant drugs on cells subjected to radiation. The knowledge gained by use of the CRES is expected to contribute to the development of better cancer treatments and of better protection for astronauts, medical-equipment operators, and nuclear-power-plant workers, and others exposed frequently to ionizing radiation.

  5. Upgrading of a gamma radiation facility

    NASA Astrophysics Data System (ADS)

    Andrade, M. E.; Coelho, N.; Oliveira, J. E.

    1995-02-01

    A gamma radiation facility installed with the support of the International Atomic Energy Agency (IAEA) is operating at Sacavém campus of the National Institute for Industrial Technology and Engineering (INETI) under the administration of the Institute of Technology and Innovation for Enterpreneurial Modernization (ITIME). In order to upgrade the safety of the plant and running operation, following national regulations as well as the CEN standards, several improvements have been introduced in the last couple of years. Hence, a new radiation monitoring system, a physical barrier at the entrance of the labyrinth and an electro-penumatic loading/unloading station were installed interlocked to the source. All the previous systems remaining and the new ones are controlled by a PC. The facility can work continuously in automatic mode.

  6. Near ground gamma radiation associated with lightning

    NASA Astrophysics Data System (ADS)

    Sakuma, K.; Greenfield, M. B.; Ikeda, Y.; Kubo, K.

    2004-03-01

    Increases in the atmospheric gamma radiation of 22 to 82above normal background have been observed after the onset of lightning fifteen times since March 2001[1]. Gamma rays have been observed with up to four 12.9 cm3 NaI detectors and recently with a high resolution Ge detector positioned 6-21 m and 15 m above ground, respectively. The tail of the observed background subtracted gamma ray rates GRR were fitted with exponential decay curves yielding typical correlation coefficients of 0.95 to 0.99 and half-lives of 52.7 +/-4.81 min and 52.8+/-10.95 min, without and with precipitation, respectively. The GRR above 300 KeV from radon progeny due to precipitation were subtracted [2]. The 3x3 Ge detector with 2 KeV resolution positioned about 2 m from one of the NaI detectors observed increases in GRR minutes after the onset of lightning with a delayed 50 min exponential decay which was concurrently observed in the NaI detector. [1] M. B. Greenfield et al., Journal of Applied Physics 93 no. 3 (2003) pp 1839-1844. [2] M. B. Greenfield et al., Journal of Applied Physics 93 no. 9 (2003) pp 5733-5741.

  7. Differentially Expressed Genes Associated with Low-Dose Gamma Radiation

    NASA Astrophysics Data System (ADS)

    Hegyesi, Hargita; Sándor, Nikolett; Schilling, Boglárka; Kis, Enikő; Lumniczky, Katalin; Sáfrány, Géza

    We have studied low dose radiation induced gene expression alterations in a primary human fibroblast cell line using Agilent's whole human genome microarray. Cells were irradiated with 60Co γ-rays (0; 0.1; 0.5 Gy) and 2 hours later total cellular RNA was isolated. We observed differential regulation of approximately 300-500 genes represented on the microarray. Of these, 126 were differentially expressed at both doses, among them significant elevation of GDF-15 and KITLG was confirmed by qRT-PCR. Based on the transcriptional studies we selected GDF-15 to assess its role in radiation response, since GDF-15 is one of the p53 gene targets and is believed to participate in mediating p53 activities. First we confirmed gamma-radiation induced dose-dependent changes in GDF-15 expression by qRT-PCR. Next we determined the effect of GDF-15 silencing on radiosensitivity. Four GDF-15 targeting shRNA expressing lentiviral vectors were transfected into immortalized human fibroblast cells. We obtained efficient GDF-15 silencing in one of the four constructs. RNA interference inhibited GDF-15 gene expression and enhanced the radiosensitivity of the cells. Our studies proved that GDF-15 plays an essential role in radiation response and may serve as a promising target in radiation therapy.

  8. Gamma radiation effects on nestling Tree Swallows

    SciTech Connect

    Zach, R.; Mayoh, K.R.

    1984-10-01

    The sensitivity of Tree Swallows (Tachycineta bicolor) to the stress of ionizing radiation was investigated with growth analysis. Freshly hatched nestlings were temporarily removed from nests, taken to the laboratory and acutely exposed to 0.9, 2.7, or 4.5 Gy gamma radiation. Some of the unirradiated control nestlings were also taken to the laboratory whereas others were left in the nests. Growth of all the nestlings was measured daily and analyzed by fitting growth models. There was no detectable radiation-induced mortality up to fledgling, approx. = 20 d after irradiation. Radiation exposure did not affect the basic growth pattern; the logistic growth model was most suitable for body mass and foot length, and the von Bertalanffy model for primary-feather length, irrespective of treatment. Parameter values from these models indicated pronounced growth depression in the 2.7-Gy and 4.5-Gy groups, particularly for body mass. Radiation also affected the timing of development. The growth depression of the 2.7-Gy group was similar to that caused by hatching asynchrony in unirradiated nestlings. The 4.5-Cy nestlings grew as well as unexposed nestlings that died from natural causes. Chronic irradiation at approx. = 1.0 Cy/d caused more severe growth effects than acute exposure to 4.5 Gy and may have caused permanent stunting. Growth analysis is a potent tool for assessing man-made environmental stresses. Observed body-mass statistics and model parameters seem to be most sensitive to environmental stresses, but coefficients of variation are not necessarily correlated with sensitivity. 34 references, 2 figures, 4 tables.

  9. Satellite observation of atmospheric nuclear gamma radiation.

    PubMed

    Letaw, J R; Share, G H; Kinzer, R L; Silberberg, R; Chupp, E L; Forrest, D J; Rieger, E

    1989-02-01

    We present a satellite observation of the spectrum of gamma radiation from the Earth's atmosphere in the energy interval from 300 keV to 8.5 MeV. The data were accumulated by the gamma ray spectrometer on the Solar Maximum Mission over 3 1/2 years, from 1980 to 1983. The excellent statistical accuracy of the data allows 20 atmospheric line features to be identified. The features are superimposed on a continuum background which is modeled using a power law with index -1.16. Many of these features contain a blend of more than one nuclear line. All of these lines (with the exception of the 511-keV annihilation line) are Doppler broadened. Line energies and intensities are consistent with production by secondary neutrons interacting with atmospheric 14N and 16O. Although we find no evidence for other production mechanisms, we cannot rule out significant contributions from direct excitation or spallation by primary cosmic ray protons. The relative intensities of the observed line features are in fair agreement with theoretical models; however, existing models are limited by the availability of neutron cross sections, especially at high energies. The intensity and spectrum of photons at energies below the 511-keV line, in excess of a power law continuum, can be explained by Compton scattering of the annihilation line photons in traversing an average of approximately 21 g cm-2 of atmosphere. PMID:11537397

  10. Solar cell radiation handbook

    NASA Technical Reports Server (NTRS)

    Carter, J. R., Jr.; Tada, H. Y.

    1973-01-01

    A method is presented for predicting the degradation of a solar array in a space radiation environment. Solar cell technology which emphasizes the cell parameters that degrade in a radiation environment, is discussed along with the experimental techniques used in the evaluation of radiation effects. Other topics discussed include: theoretical aspects of radiation damage, methods for developing relative damage coefficients, nature of the space radiation environment, method of calculating equivalent fluence from electron and proton energy spectrums and relative damage coefficients, and comparison of flight data with estimated degradation.

  11. Orchid flowers tolerance to gamma-radiation

    NASA Astrophysics Data System (ADS)

    Kikuchi, Olivia Kimiko

    2000-03-01

    Cut flowers are fresh goods that may be treated with fumigants such as methyl bromide to meet the needs of the quarantine requirements of importing countries. Irradiation is a non-chemical alternative to substitute the methyl bromide treatment of fresh products. In this research, different cut orchids were irradiated to examine their tolerance to gamma-rays. A 200 Gy dose did inhibit the Dendrobium palenopsis buds from opening, but did not cause visible damage to opened flowers. Doses of 800 and 1000 Gy were damaging because they provoked the flowers to drop from the stem. Cattleya irradiated with 750 Gy did not show any damage, and were therefore eligible for the radiation treatment. Cymbidium tolerated up to 300 Gy and above this dose dropped prematurely. On the other hand, Oncydium did not tolerate doses above 150 Gy.

  12. Intrinsic radiation resistance in human chondrosarcoma cells

    SciTech Connect

    Moussavi-Harami, Farid; Mollano, Anthony; Martin, James A.; Ayoob, Andrew; Domann, Frederick E.; Gitelis, Steven; Buckwalter, Joseph A. . E-mail: joseph-buckwalter@uiowa.edu

    2006-07-28

    Human chondrosarcomas rarely respond to radiation treatment, limiting the options for eradication of these tumors. The basis of radiation resistance in chondrosarcomas remains obscure. In normal cells radiation induces DNA damage that leads to growth arrest or death. However, cells that lack cell cycle control mechanisms needed for these responses show intrinsic radiation resistance. In previous work, we identified immortalized human chondrosarcoma cell lines that lacked p16{sup ink4a}, one of the major tumor suppressor proteins that regulate the cell cycle. We hypothesized that the absence of p16{sup ink4a} contributes to the intrinsic radiation resistance of chondrosarcomas and that restoring p16{sup ink4a} expression would increase their radiation sensitivity. To test this we determined the effects of ectopic p16{sup ink4a} expression on chondrosarcoma cell resistance to low-dose {gamma}-irradiation (1-5 Gy). p16{sup ink4a} expression significantly increased radiation sensitivity in clonogenic assays. Apoptosis did not increase significantly with radiation and was unaffected by p16{sup ink4a} transduction of chondrosarcoma cells, indicating that mitotic catastrophe, rather than programmed cell death, was the predominant radiation effect. These results support the hypothesis that p16{sup ink4a} plays a role in the radiation resistance of chondrosarcoma cell lines and suggests that restoring p16 expression will improve the radiation sensitivity of human chondrosarcomas.

  13. Pulsar and diffuse contributions to the observed galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Harding, A. K.; Stecker, F. W.

    1980-01-01

    With the acquisition of satellite data on the energy spectrum of galactic gamma-radiation, it is clear that such radiation has a multicomponent nature. A calculation of the pulsar gamma ray emission spectrum is used together with a statistical analysis of recent data on 328 known pulsars to make a new determination of the pulsar contribution to galactic gamma ray emission. The contributions from diffuse interstellar cosmic ray induced production mechanisms to the total emission are then reexamined. It is concluded that pulsars may account for a significant fraction of galactic gamma ray emission.

  14. Petroleum and diesel sulfur degradation under gamma radiation

    NASA Astrophysics Data System (ADS)

    Andrade, Luana dos Santos; Calvo, Wilson Aparecido Parejo; Sato, Ivone Mulako; Duarte, Celina Lopes

    2015-10-01

    Hydrodesulfurization (HDS) is currently the most common method used by refineries to remove sulfur compounds from petroleum fractions. However, it is not highly effective for removing thiophene compounds such as benzothiophene. Additionally, this process generates high costs for the oil industry. In the present work, ionizing radiation was used in order to study the effect on the degradation of petroleum and diesel sulfur compounds. Crude oil and diesel fuel samples were studied, without any pretreatment, and irradiated using a cobalt-60 gamma cell in a batch system at absorbed doses of 30 kGy and 50 kGy. The sulfur compounds were extracted and then analyzed by gas chromatography associated with mass spectrometry (GCMS). A high efficiency of ionizing radiation was observed regarding the degradation of sulfur compounds such as benzothiophene and benzenethiol and the formation of fragments, for example 1.2-dimethylbenzene and toluene.

  15. Inhaled /sup 147/Pm and/or total-body gamma radiation: Early mortality and morbidity in rats

    SciTech Connect

    Filipy, R.E.; Lauhala, K.E.; McGee, D.R.; Cannon, W.C.; Buschbom, R.L.; Decker, J.R.; Kuffel, E.G.; Park, J.F.; Ragan, H.A.; Yaniv, S.S.; Scott, B.R.

    1989-05-01

    Rats were given doses of /sup 60/Co gamma radiation and/or lung burdens of /sup 147/Pm (in fused aluminosilicate particles) within lethal ranges in an experiment to determine and compare morbidity and mortality responses for the radiation insults within 1 year after exposure. Radiation-induced morbidity was assessed by measuring changes in body weights, hematologic parameters, and pulmonary-function parameters. Acute mortality and morbidity from inhaled promethium were caused primarily by radiation pneumonitis and pulmonary fibrosis that occurred more than 53 days after exposure. Acute mortality and morbidity from total-body gamma irradiation occurred within 30 days of exposure and resulted from the bone-marrow radiation syndrome. Gamma radiation caused transient morbidity, reflected by immediately depressed blood cell levels and by reduced body weight gain in animals that survived the acute gamma radiation syndrome. Inhaled promethium caused a loss of body weight and diminished pulmonary function, but its only effect on blood cell levels was lymphocytopenia. Combined gamma irradiation and promethium lung burdens were synergistic, in that animals receiving both radiation insults had higher morbidity and mortality rates than would be predicted based on the effect of either kind of radiation alone. Promethium lung burdens enhanced the effect of gamma radiation in rats within the first 30 days of exposure, and gamma radiation enhanced the later effect of promethium lung burdens. 70 refs., 68 figs., 21 tabs.

  16. Ionizing radiation potentiates the induction of nitric oxide synthase by interferon-gamma and/or lipopolysaccharide in murine macrophage cell lines. Role of tumor necrosis factor-alpha.

    PubMed

    McKinney, L C; Aquilla, E M; Coffin, D; Wink, D A; Vodovotz, Y

    2000-01-01

    Macrophages respond to infection or injury by changing from a "resting" cellular phenotype to an "activated" state defined by the expression of various cytotoxic effector functions. Regulation of the transition from a resting to an activated state is effected by cytokine and/or pathogenic signals. Some signals do not directly induce activation, but instead "prime" the macrophage to respond more vigorously to a second signal. One example of this priming phenomenon involves induction of nitric oxide (NO) synthesis by the enzyme nitric oxide synthase (NOS2). Our experiments indicate that low doses (1-5 Gy) of ionizing radiation can enhance the induction of enzymatically active NOS2 by IFN-gamma or LPS in J774.1 and RAW264.7 murine macrophage cell lines. Radiation alone did not produce this induction, rather, it was effective as a priming signal; cells exposed to radiation produced more NO when a second signal, either IFN-gamma or LPS, was applied 24 h later. PMID:10863529

  17. A Device for Search of Gamma-Radiation Intensive Sources at the Radiation Accident Condition

    SciTech Connect

    Batiy, Valeriy; Klyuchnykov, A; Kochnev, N; Rudko, Vladimir; shcherbin, vladimir; Yegorov, V; Schmieman, Eric A.

    2005-08-08

    The procedure designed for measuring angular distributions of gamma radiation and for search of gamma radiation intensive sources is described. It is based on application of the original multidetector device ShD-1, for measuring an angular distribution in a complete solid angle (4 pi). The calibration results and data on the angular distributions of intensity of gamma radiation at the roof of Chornobyl NPP ''Shelter'' are presented.

  18. Solar cell radiation handbook

    NASA Technical Reports Server (NTRS)

    Tada, H. Y.; Carter, J. R., Jr.

    1977-01-01

    Solar cell theory cells are manufactured, and how they are modeled mathematically is reviewed. The interaction of energetic charged particle radiation with solar cells is discussed in detail and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Finally, an extensive body of data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence is presented.

  19. Solar cell radiation handbook

    SciTech Connect

    Tada, H.Y.; Carter, J.R. Jr.; Anspaugh, B.E.

    1982-11-01

    The handbook to predict the degradation of solar cell electrical performance in any given space radiation environment is presented. Solar cell theory, cell manufacturing and how they are modeled mathematically are described. The interaction of energetic charged particles radiation with solar cells is discussed and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence are presented.

  20. Solar cell radiation handbook

    NASA Technical Reports Server (NTRS)

    Tada, H. Y.; Carter, J. R., Jr.; Anspaugh, B. E.; Downing, R. G.

    1982-01-01

    The handbook to predict the degradation of solar cell electrical performance in any given space radiation environment is presented. Solar cell theory, cell manufacturing and how they are modeled mathematically are described. The interaction of energetic charged particles radiation with solar cells is discussed and the concept of 1 MeV equivalent electron fluence is introduced. The space radiation environment is described and methods of calculating equivalent fluences for the space environment are developed. A computer program was written to perform the equivalent fluence calculations and a FORTRAN listing of the program is included. Data detailing the degradation of solar cell electrical parameters as a function of 1 MeV electron fluence are presented.

  1. Inactivation of rabies diagnostic reagents by gamma radiation

    SciTech Connect

    Gamble, W.C.; Chappell, W.A.; George, E.H.

    1980-11-01

    Treatment of CVS-11 rabies adsorbing suspensions and street rabies infected mouse brains with gamma radiation resulted in inactivated reagents that are safer to distribute and use. These irradiated reagents were as sensitive and reactive as the nonirradiated control reagents.

  2. {lambda}(1520) {yields} {lambda}{gamma} Radiative-Decay Width

    SciTech Connect

    Vavilov, D.V.; Antipov, Yu.M.; Artamonov, A.V.; Batarin, V.A.; Victorov, V.A.; Golovkin, S.V.; Gorin, Yu.P.; Eroshin, O.V.; Kozhevnikov, A.P.; Konstantinov, A.S.; Kubarovsky, V.P.; Kurshetsov, V.F.; Landsberg, L.G.; Leontiev, V.M.; Molchanov, V.V.; Mukhin, V.A.; Patalakha, D.I.; Petrenko, S.V.; Petrukhin, A.I.; Kolganov, V.Z.

    2005-03-01

    The radiative decay {lambda}(1520) {yields} {lambda}{gamma} was recorded in the exclusive reaction p + N {yields} {lambda}(1520)K{sup +} + N at the SPHINX facility. The branching ratio for this decay and the corresponding partial width were found to be, respectively, Br[{lambda}(1520) {yields} {lambda}{gamma}] = (1.02 {+-} 0.21) x 10{sup -2} and {gamma}[{lambda}(1520) {yields} {lambda}{gamma}] = 159 {+-} 35 keV (the quoted errors are purely statistical, the systematic errors being within 15%)

  3. RADIATION SENSITIVITY & PROCESSING OF DNA DAMAGE FOLLOWING LOW DOSES OF GAMMA-RAY ALPHA PARTICLES & HZE IRRADIATION OF NORMAL DSB REPAIR DEFICIENT CELLS

    SciTech Connect

    O'Neil, Peter

    2009-05-15

    Non-homologous end joining (NHEJ) predominates in the repair of DNA double strand breaks (DSB) over homologous recombination (HR). NHEJ occurs throughout the cell cycle whereas HR occurs in late S/G2 due to the requirement of a sister chromatid (Rothkamm et al, Mol Cell Biol 23 5706-15 [2003]). To date evidence obtained with DSB repair deficient cells using pulsed-field gel electrophoresis has revealed the major pathway throughout all phases of the cell cycle for processing high dose induced DSBs is NHEJ (Wang et al, Oncogene 20 2212-24 (2001); Pluth et al, Cancer Res. 61 2649-55 [2001]). These findings however were obtained at high doses when on average >> 20-30 DSBs are formed per cell. The contribution of the repair pathways (NHEJ and HR) induced in response to DNA damage during the various phases of the cell cycle may depend upon the dose (the level of initial DSBs) especially since low levels of DSBs are induced at low dose. To date, low dose studies using NHEJ and HR deficient mutants have not been carried out to address this important question with radiations of different quality. The work presented here leads us to suggest that HR plays a relatively minor role in the repair of radiation-induced prompt DSBs. SSBs lead to the induction of DSBs which are associated specifically with S-phase cells consistent with the idea that they are formed at stalled replication forks in which HR plays a major role in repair. That DNA-PKcs is in some way involved in the repair of the precursors to replication-induced DSB remains an open question. Persistent non-DSB oxidative damage also leads to an increase in RAD51 positive DSBs. Both simple and complex non-DSB DNA damage may therefore contribute to indirect DSBs induced by ionising radiation at replication forks.

  4. Development of a novel gamma probe for detecting radiation direction

    NASA Astrophysics Data System (ADS)

    Pani, R.; Pellegrini, R.; Cinti, M. N.; Longo, M.; Donnarumma, R.; D'Alessio, A.; Borrazzo, C.; Pergola, A.; Ridolfi, S.; De Vincentis, G.

    2016-01-01

    Spatial localization of radioactive sources is currently a main issue interesting different fields, including nuclear industry, homeland security as well as medical imaging. It is currently achieved using different systems, but the development of technologies for detecting and characterizing radiation is becoming important especially in medical imaging. In this latter field, radiation detection probes have long been used to guide surgery, thanks to their ability to localize and quantify radiopharmaceutical uptake even deep in tissue. Radiolabelled colloid is injected into, or near to, the tumor and the surgeon uses a hand-held radiation detector, the gamma probe, to identify lymph nodes with radiopharmaceutical uptkake. The present work refers to a novel scintigraphic goniometric probe to identify gamma radiation and its direction. The probe incorporates several scintillation crystals joined together in a particular configuration to provide data related to the position of a gamma source. The main technical characteristics of the gamma locator prototype, i.e. sensitivity, spatial resolution and detection efficiency, are investigated. Moreover, the development of a specific procedure applied to the images permits to retrieve the source position with high precision with respect to the currently used gamma probes. The presented device shows a high sensitivity and efficiency to identify gamma radiation taking a short time (from 30 to 60 s). Even though it was designed for applications in radio-guided surgery, it could be used for other purposes, as for example homeland security.

  5. Some Radiation Techniques Used in the GU-3 Gamma Irradiator

    SciTech Connect

    Dodbiba, Andon; Ylli, Ariana; Stamo, Iliriana; Kongjika, Efigjeni

    2007-04-23

    Different radiation techniques, measurement of dose and its distibution throughout the irradiated materials are the main problems treated in this paper. The oscillometry method combined with the ionization chamber, as an absolute dosimeter, is used for calibration of routine ECB dosimeters. The dose uniformity, for the used radiation techniques in our GU-3 Gamma Irradiator with Cs-137, is from 93% up to 99%.

  6. Observations of Galactic gamma-radiation with the SMM spectrometer

    NASA Technical Reports Server (NTRS)

    Share, G. H.; Kinzer, R. L.; Messina, D. C.; Purcell, W. R.; Chupp, E. L.

    1986-01-01

    Preliminary results from the SMM gamma-ray spectrometer are reported which indicate the detection of a constant source of 0.511-MeV annihilation radiation from the Galaxy. Year-to-year variability appears to be less than 30 percent. The radiation probably comes from a diffuse source and is not associated with the reported compact object at the Galactic center.

  7. Natural gamma radiation from long-lived actinide isotopes

    SciTech Connect

    Dupree, S.A.; Sanger, H.M.

    1987-06-01

    The purpose of this report is to describe a method, developed at Sandia National Laboratories, for calculating volumetric, unshielded, gamma radiation source spectra with arbitrary energy group structures from essentially arbitrary mixtures of actinide isotopes. The computer code and data base are combined as INRAD. These spectra can be used to describe the source for gamma radiation transport codes. Coupled with this source routine is a special version of the one-dimensional, discrete ordinates, radiation transport code XSDRN that uses the spectrum generating routine to define sources in an appropriate energy group structure. 15 refs., 34 figs., 10 tabs.

  8. Proton and gamma radiation tests on nonlinear crystals.

    PubMed

    Roth, Ulrich; Tröbs, Michael; Graf, Thomas; Balmer, Jürg E; Weber, Heinz P

    2002-01-20

    We report on the results of proton and gamma irradiation tests performed on nonlinear crystals for second- (SHG) and third-harmonic generation. Beta-barium borate (BBO), lithium triborate (LBO), and KTP crystals were exposed to three different energies of proton radiation (8, 70, and 300 MeV) and incremental doses of gamma radiation (up to 139 krad) in order to investigate the change in SHG performance and transmission spectra. BBO and LBO crystals turned out to be a suitable choice for SHG under radiative conditions. PMID:11905572

  9. A localized excess of diffuse gamma radiation

    NASA Technical Reports Server (NTRS)

    Chen, A.; Dwyer, J.; Kaaret, P.

    1995-01-01

    Using archival Energetic Gamma Ray Experiment Telescope (EGRET) gamma-ray data and atomic hydrogen (H I) column densities derived from 21 cm radio observations, we have found a large irregular region in the northern Galactic hemisphere extending from (l approximately 90 deg, b approximately 52 deg) to (l approximately 45 deg, b approximately 77 deg) with a significant enhancement in the gamma-ray emissivity compared to the surrounding sky. The region contains no previously identified gamma-ray point sources. The emission may arise from a localized enhancement in cosmic-ray density or from the presence of matter other than H I. If the emission is due to unseen matter, a column density enhancement equivalent to approximately 2 x 10(exp 20) H-atoms/sq cm is required.

  10. Designing Equipment for Use in Gamma Radiation Environments

    SciTech Connect

    Vandergriff, K.U.

    1990-01-01

    High levels of gamma radiation are known to cause degradation in a variety of materials and components. When designing systems to operate in a high radiation environment, special precautions and procedures should be followed. This report (1) outlines steps that should be followed in designing equipment and (2) explains the general effects of radiation on various engineering materials and components. Much information exists in the literature on radiation effects upon materials. However, very little information is available to give the designer a step-by-step process for designing systems that will be subject to high levels of gamma radiation, such as those found in a nuclear fuel reprocessing facility. In this report, many radiation effect references are relied upon to aid in the design of components and systems.

  11. Quantification of the 2-deoxyribonolactone and nucleoside 5'-aldehyde products of 2-deoxyribose oxidation in DNA and cells by isotope-dilution gas chromatography mass spectrometry: differential effects of gamma-radiation and Fe2+-EDTA.

    PubMed

    Chan, Wan; Chen, Bingzi; Wang, Lianrong; Taghizadeh, Koli; Demott, Michael S; Dedon, Peter C

    2010-05-01

    The oxidation of 2-deoxyribose in DNA has emerged as a critical determinant of the cellular toxicity of oxidative damage to DNA, with oxidation of each carbon producing a unique spectrum of electrophilic products. We have developed and validated an isotope-dilution gas chromatography-coupled mass spectrometry (GC-MS) method for the rigorous quantification of two major 2-deoxyribose oxidation products: the 2-deoxyribonolactone abasic site of 1'-oxidation and the nucleoside 5'-aldehyde of 5'-oxidation chemistry. The method entails elimination of these products as 5-methylene-2(5H)-furanone (5MF) and furfural, respectively, followed by derivatization with pentafluorophenylhydrazine (PFPH), addition of isotopically labeled PFPH derivatives as internal standards, extraction of the derivatives, and quantification by GC-MS analysis. The precision and accuracy of the method were validated with oligodeoxynucleotides containing the 2-deoxyribonolactone and nucleoside 5'-aldehyde lesions. Further, the well-defined 2-deoxyribose oxidation chemistry of the enediyne antibiotics, neocarzinostatin and calicheamicin gamma(1)(I), was exploited in control studies, with neocarzinostatin producing 10 2-deoxyribonolactone and 300 nucleoside 5'-aldehyde per 10(6) nt per microM in accord with its established minor 1'- and major 5'-oxidation chemistry. Calicheamicin unexpectedly caused 1'-oxidation at a low level of 10 2-deoxyribonolactone per 10(6) nt per microM in addition to the expected predominance of 5'-oxidation at 560 nucleoside 5'-aldehyde per 10(6) nt per microM. The two hydroxyl radical-mediated DNA oxidants, gamma-radiation and Fe(2+)-EDTA, produced nucleoside 5'-aldehyde at a frequency of 57 per 10(6) nt per Gy (G-value 74 nmol/J) and 3.5 per 10(6) nt per microM, respectively, which amounted to 40% and 35%, respectively, of total 2-deoxyribose oxidation as measured by a plasmid nicking assay. However, gamma-radiation and Fe(2+)-EDTA produced different proportions of 2-deoxyribonolactone at 7% and 24% of total 2-deoxyribose oxidation, respectively, with frequencies of 10 lesions per 10(6) nt per Gy (G-value, 13 nmol/J) and 2.4 lesions per 10(6) nt per microM. Studies in TK6 human lymphoblastoid cells, in which the analytical data were corrected for losses sustained during DNA isolation, revealed background levels of 2-deoxyribonolactone and nucleoside 5'-aldehyde of 9.7 and 73 lesions per 10(6) nt, respectively. Gamma-irradiation of the cells caused increases of 0.045 and 0.22 lesions per 10(6) nt per Gy, respectively, which represents a approximately 250-fold quenching effect of the cellular environment similar to that observed in previous studies. The proportions of the various 2-deoxyribose oxidation products generated by gamma-radiation are similar for purified DNA and cells. These results are consistent with solvent exposure as a major determinant of hydroxyl radical reactivity with 2-deoxyribose in DNA, but the large differences between gamma-radiation and Fe(2+)-EDTA suggest that factors other than hydroxyl radical reactivity govern DNA oxidation chemistry. PMID:20377226

  12. Toxic-dose warfarin-induced apoptosis and its enhancement by gamma ionizing radiation in leukemia K562 and HL-60 cells is not mediated by induction of oxidative stress.

    PubMed

    Onaran, Ilhan; Sencan, Sevide; Demirtaş, Halil; Aydemir, Birsen; Ulutin, Turgut; Okutan, Murat

    2008-11-01

    The purpose of this study was to test the hypothesis that warfarin may enhance free radical production and oxidative damage on cancer cells. We examined the possible concentration-dependent effect of warfarin on cytotoxicity with respect to oxidative stress on leukemia cell lines (K562 and HL-60) and normal human peripheral blood mononuclear cells (PBMC). Gamma radiation was used as a positive control agent for oxidative stress. At all concentrations of warfarin (5-200 muM), 5-amino-2,3-dihydro-1,4-phthalazinedione (luminol)- and bis-N-methylacridinium nitrate (lucigenin)-amplified chemiluminescence responses and lipid peroxidation and protein oxidation were stable after 72 h incubation at 37 degrees C. However, The 2',7'-dichlorofluorescein diacetate (DCFH-DA) oxidation was increased when cells were incubated with high concentrations (50-200 muM) of warfarin. In these concentration ranges, warfarin reduced cell growth in a dose-dependent manner, producing apoptosis. Our results also revealed that at concentrations above 5 muM, warfarin had a potentiating effect on radiation-mediated growth inhibition and apoptosis. Furthermore, marked effects were observed on leukemic cells compared with PBMC. We report here that the increase of DCFH oxidation might be due to the increase in the release of cytochrome C caused by warfarin, as cytosolic cytochrome C content was significantly elevated in the warfarin-treated cells compared with control cells, and because cotreatment with antioxidants N- acetylcysteine or 4,5-dihydroxy-1,3-benzene-disulfonic acid (Tiron) was unable to prevent cytochrome C release and DCFH oxidation induced by the drug. Taken together, these results suggest that high warfarin concentrations may be toxic to leukemic cells in vitro through apoptosis, although at the pharmacological concentrations (<50 muM), warfarin has no prooxidant or cytotoxic effect on PBMC, K562, and HL-60 cells. In addition, when the treatment of leukemic cells with warfarin at concentrations above 5 muM is combined with radiation, we observed an increase in radiation-induced cytotoxicity. The mechanism by which warfarin potentiates this cytotoxicity is unclear, but it may not be directly due to toxic damage induced by warfarin-generated free radicals. PMID:18568337

  13. SM22{alpha}-induced activation of p16{sup INK4a}/retinoblastoma pathway promotes cellular senescence caused by a subclinical dose of {gamma}-radiation and doxorubicin in HepG2 cells

    SciTech Connect

    Kim, Tae Rim; Lee, Hee Min; Lee, So Yong; Kim, Eun Jin; Kim, Kug Chan; Paik, Sang Gi; Cho, Eun Wie; Kim, In Gyu

    2010-09-10

    Research highlights: {yields} SM22{alpha} overexpression in HepG2 cells leads cells to a growth arrest state, and the treatment of a subclinical dose of {gamma}-radiation or doxorubicin promotes cellular senescence. {yields} SM22{alpha} overexpression elevates p16{sup INK4a} followed by pRB activation, but there are no effects on p53/p21{sup WAF1/Cip1} pathway. {yields} SM22{alpha}-induced MT-1G activates p16{sup INK4a}/pRB pathway, which promotes cellular senescence by damaging agents. -- Abstract: Smooth muscle protein 22-alpha (SM22{alpha}) is known as a transformation- and shape change-sensitive actin cross-linking protein found in smooth muscle tissue and fibroblasts; however, its functional role remains uncertain. We reported previously that SM22{alpha} overexpression confers resistance against anti-cancer drugs or radiation via induction of metallothionein (MT) isozymes in HepG2 cells. In this study, we demonstrate that SM22{alpha} overexpression leads cells to a growth arrest state and promotes cellular senescence caused by treatment with a subclinical dose of {gamma}-radiation (0.05 and 0.1 Gy) or doxorubicin (0.01 and 0.05 {mu}g/ml), compared to control cells. Senescence growth arrest is known to be controlled by p53 phosphorylation/p21{sup WAF1/Cip1} induction or p16{sup INK4a}/retinoblastoma protein (pRB) activation. SM22{alpha} overexpression in HepG2 cells elevated p16{sup INK4a} followed by pRB activation, but did not activate the p53/p21{sup WAF1/Cip1} pathway. Moreover, MT-1G, which is induced by SM22{alpha} overexpression, was involved in the activation of the p16{sup INK4a}/pRB pathway, which led to a growth arrest state and promoted cellular senescence caused by damaging agents. Our findings provide the first demonstration that SM22{alpha} modulates cellular senescence caused by damaging agents via regulation of the p16{sup INK4a}/pRB pathway in HepG2 cells and that these effects of SM22{alpha} are partially mediated by MT-1G.

  14. A study of the diffuse galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Kniffen, D. A.

    1982-01-01

    Assuming cosmic rays pervade the Galaxy, they necessarily produced high energy gamma-rays as they interact with the instellar matter and photons. The cosmic ray nucleon interactions five rise to gamma rays primarily through the decay of pi mesons, giving a unique spectrum with a maximum at approximately 68 MeV. Cosmic ray electrons produce gamma rays through bremsstrahlung, but with a markedly different energy spectral shape, one which decreases monotonically with energy. Cosmic ray electrons also interact with the interstellar starlight, optical and infrared photons, and the blackbody radiation through the Compton process. A model of galactic gamma ray production is discussed, and the predicted spatial distribution and energy spectra are presented. Considering the uncertainty in the point source contributions, the agreement between the theoretical predictions and the gamma ray data seems quite reasonable.

  15. Monitoring precipitation and lightning via changes in atmospheric gamma radiation

    SciTech Connect

    Greenfield, M.B.; Domondon, A.; Tsuchiya, S.; Tomiyama, G.

    2003-08-26

    Atmospheric {gamma}-radiation has been measured since 1999 and recently at three elevations 220m from the first site to ascertain position dependency and optimal elevation for observing {gamma}-rays from radon and radon-progeny found in precipitation. Radiation from time-independent and diurnal components was minimized in order to ascertain the reliability, accuracy and practicality of determining precipitation rates from correlated {gamma}-rates. Data taken with 4-12.9cm3 NaI detectors at elevations above ground of 9.91, 14.2, 15.7, and 21.4 m were fit with a model assuming a surface and/or volume deposition of radon progeny on/in water droplets during precipitation which predicts {gamma} -ray rates proportional to the 2/5 and/or 3/5 power of rain rates, respectively. With mostly surface deposition and age corrections for radon progeny, the correlation coefficients improved with elevation and reached a maximum at 0.95 around 20m. Atmospheric {gamma} radiation enables monitoring precipitation rates to 0.3 mm/h with time resolution limited only by counting statistics. High {gamma}-ray rates, decreasing with 40-minute half-life following lightning may be indirectly due to ions accelerated in electric field.

  16. Haemopoietic cell renewal in radiation fields

    NASA Astrophysics Data System (ADS)

    Fliedner, T. M.; Nothdurft, W.; Tibken, B.; Hofer, E.; Weiss, M.; Kindler, H.

    1994-10-01

    Space flight activities are inevitably associated with a chronic exposure of astronauts to a complex mixture of ionising radiation. Although no acute radiation consequences are to be expected as a rule, the possibility of Solar Particle Events (SPE) associated with relatively high doses of radiation (1 or more Gray) cannot be excluded. It is the responsibility of physicians in charge of the health of astronauts to evaluate before, during and after space flight activities the functional status of haemopoietic cell renewal. Chronic low level exposure of dogs indicate that daily gamma-exposure doses below about 2 cGy are tolerated for several years as far as blood cell concentrations are concerned. However, the stem cell pool may be severely affected. The maintenance of sufficient blood cell counts is possible only through increased cell production to compensate for the radiation inflicted excess cell loss. This behaviour of haemopoietic cell renewal during chronic low level exposure can be simulated by bioengineering models of granulocytopoiesis. It is possible to define a ``turbulence region'' for cell loss rates, below which an prolonged adaptation to increased radiation fields can be expected to be tolerated. On the basis of these experimental results, it is recommended to develop new biological indicators to monitor haemopoietic cell renewal at the level of the stem cell pool using blood stem cells in addition to the determination of cytokine concentrations in the serum (and other novel approaches). To prepare for unexpected haemopoietic effects during prolonged space missions, research should be increased to modify the radiation sensitivity of haemopoietic stem cells (for instance by the application of certain regulatory molecules). In addition, a ``blood stem cell bank'' might be established for the autologous storage of stem cells and for use in space activities keeping them in a radiation protected container.

  17. Reusable shielding material for neutron- and gamma-radiation

    NASA Astrophysics Data System (ADS)

    Calzada, Elbio; Grnauer, Florian; Schillinger, Burkhard; Trck, Harald

    2011-09-01

    At neutron research facilities all around the world radiation shieldings are applied to reduce the background of neutron and gamma radiation as far as possible in order to perform high quality measurements and to fulfill the radiation protection requirements. The current approach with cement-based compounds has a number of shortcomings: "Heavy concrete" contains a high amount of elements, which are not desired to obtain a high attenuation of neutron and/or gamma radiation (e.g. calcium, carbon, oxygen, silicon and aluminum). A shielding material with a high density of desired nuclei such as iron, hydrogen and boron was developed for the redesign of the neutron radiography facility ANTARES at beam tube 4 (located at a cold neutron source) of FRM-II. The composition of the material was optimized by help of the Monte Carlo code MCNP5. With this shielding material a considerable higher attenuation of background radiation can be obtained compared to usual heavy concretes.

  18. Effect of gamma radiation on honey quality control

    NASA Astrophysics Data System (ADS)

    Bera, A.; Almeida-Muradian, L. B.; Sabato, S. F.

    2009-07-01

    Honey is one of the most complex substances produced by bees, mainly from the nectar of flowers. Gamma radiation is a technique that can be used to decrease the number of microbiological problems associated with food and increase the shelf life of certain products. The objective of this study was to verify the effect of gamma radiation with source of cobalto-60 (10 kGy) on some parameters used in honey quality control. Seven samples of pure honey were obtained from local markets in Sao Paulo, Brazil, in 2007. The methods used are in accordance with Brazilian Regulations. The physicochemical parameters analyzed were: moisture, HMF, free acidity, pH, sugars and ash. The results showed that gamma radiation, in the dose mentioned above, did not cause significant physicochemical alterations.

  19. Measurements of background gamma radiation on Spacelab 2

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.; Paciesas, W. S.; Gregory, J. C.

    1987-01-01

    A nuclear radiation monitor (NRM) which was flown as part of the verification instrumentation on the Spacelab 2 mission (July 29 - August 6, 1985) recorded spectra every 20 seconds and counting rates in coarse energy bands on finer time scales. The gamma radiation environment on Spacelab is characterized by cosmic-ray and trapped proton secondary radiation in the Spacelab/Shuttle, earth albedo radiation, and delayed induced radioactivity in the detector and surrounding materials. It is found that passages through South Atlantic Anomaly protons produce a well-defined background enhancement.

  20. Curcumin Regulates Low-Linear Energy Transfer {gamma}-Radiation-Induced NF{kappa}B-Dependent Telomerase Activity in Human Neuroblastoma Cells

    SciTech Connect

    Aravindan, Natarajan; Veeraraghavan, Jamunarani; Madhusoodhanan, Rakhesh; Herman, Terence S.; Natarajan, Mohan

    2011-03-15

    Purpose: We recently reported that curcumin attenuates ionizing radiation (IR)-induced survival signaling and proliferation in human neuroblastoma cells. Also, in the endothelial system, we have demonstrated that NF{kappa}B regulates IR-induced telomerase activity (TA). Accordingly, we investigated the effect of curcumin in inhibiting IR-induced NF{kappa}B-dependent hTERT transcription, TA, and cell survival in neuroblastoma cells. Methods and Materials: SK-N-MC or SH-SY5Y cells exposed to IR and treated with curcumin (10-100 nM) with or without IR were harvested after 1 h through 24 h. NF{kappa}B-dependent regulation was investigated either by luciferase reporter assays using pNF{kappa}B-, pGL3-354-, pGL3-347-, or pUSE-I{kappa}B{alpha}-Luc, p50/p65, or RelA siRNA-transfected cells. NF{kappa}B activity was analyzed using an electrophoretic mobility shift assay and hTERT expression using the quantitative polymerase chain reaction. TA was determined using the telomerase repeat amplification protocol assay and cell survival using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltertrazolium bromide and clonogenic assay. Results: Curcumin profoundly inhibited IR-induced NF{kappa}B. Consequently, curcumin significantly inhibited IR-induced TA and hTERT mRNA at all points investigated. Furthermore, IR-induced TA is regulated at the transcriptional level by triggering telomerase reverse transcriptase (TERT) promoter activation. Moreover, NF{kappa}B becomes functionally activated after IR and mediates TA upregulation by binding to the {kappa}B-binding region in the promoter region of the TERT gene. Consistently, elimination of the NF{kappa}B-recognition site on the telomerase promoter or inhibition of NF{kappa}B by the I{kappa}B{alpha} mutant compromises IR-induced telomerase promoter activation. Significantly, curcumin inhibited IR-induced TERT transcription. Consequently, curcumin inhibited hTERT mRNA and TA in NF{kappa}B overexpressed cells. Furthermore, curcumin enhanced the IR-induced inhibition of cell survival. Conclusions: These results strongly suggest that curcumin inhibits IR-induced TA in an NF{kappa}B dependent manner in human neuroblastoma cells.

  1. Induction of a cytogenetic adaptive response in germ cells of irradiated mice with very low-dose rate of chronic gamma-irradiation and its biological influence on radiation-induced DNA or chromosomal damage and cell killing in their male offspring.

    PubMed

    Cai, L; Wang, P

    1995-03-01

    In earlier studies we have shown that either a single exposure or multiple exposures to a low dose of X-rays (0.05 Gy) induced a significant cytogenetic adaptive response in mouse germ cells. In this paper, a very low-dose rate (20 microGy/min) of chronic 60Co gamma-irradiation was used to pre-irradiate mice for 40 days. Then, another 40 days later, these mice were treated with a subsequent large dose of X-irradiation, followed 24 h later by cytogenetic analysis of their spermatocytes. Analysis for radiation-induced DNA and chromosomal damage was also carried out in splenocytes, bone marrow cells and spermatocytes of the offspring of mice adapted by the low-dose rate of chronic gamma-irradiation. Results demonstrated that (i) cumulative gamma-irradiation (1.10 Gy) at the dose rate 20 microGy/min induced a marked cytogenetic adaptive response in the mouse germ cells (stem spermatogonia); (ii) the sensitivity of offspring's bone marrow cells and spermatocytes to 1.5 Gy X-ray-induced chromosome aberrations was not influenced by the low-dose radiation delivered to paternal germ cells; (iii) either constitutive or post-irradiation DNA repair capacity (UV-induced unscheduled DNA synthesis, UDS) was not modified in the offspring's splenocytes; (iv) the sensitivity of the offspring's splenocytes to radiation-induced cell killing was also not altered. These results suggest that low-dose radiation delivered to the male parents with a significant induction of cytogenetic adaptive response in their germ cell does not likely cause any risk of damaging effects to the offspring of those irradiated male mice. PMID:7603336

  2. Gamma Radiation from PSR B1055-52

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Bailes, M.; Bertsch, D. L.; Cordes, J.; DAmico, N. D.; Esposito, J. A.; Finley, J.; Hartman, R. C.; Hermsen, W.; Kanbach, G.; Kaspi, V. M.; Kniffen, D. A.; Kuiper, L.; Lin, Y. C.; Lyne, A.; Manchester, R.; Matz, S. M.; Mayer-Hasselwander, H. A.; Michelson, P. F.; Nolan, P. L.

    1998-01-01

    The telescopes on the Compton Gamma Ray Observatory (CCRO) have observed PSR B1055-52 a number of times between 1991 and 1998. From these data, a more detailed picture of the gamma radiation from this source has been developed, showing several characteristics which distinguish this pulsar: the light curve is complex; there is no detectable unpulsed emission; the energy spectrum is flat, with no evidence of a sharp high-energy cutoff up to greater than 4 GeV. Comparisons of the gamma-ray data with observations at longer wavelengths show that no two of the known gamma-ray pulsars have quite the same characteristics; this diversity makes interpretation in terms of theoretical models difficult.

  3. Gamma Radiation from PSR B1055-52

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.; Bailes, M.; Bertsch, D. L.; Cordes, J.; DAmico, N.; Esposito, J. A.; Finley, J.; Hartman, R. C.; Hermsen, W.; Kanbach, G.; Kaspi, V. M.; Kniffen, D. A.; Kuiper, L.; Lin, Y. C.; Lyne, A.; Manchester, R.; Matz, S. M.; Mayer-Hasselwander, H. A.; Michelson, P. F.; Nolan, P. L.

    1999-01-01

    The telescopes on the Compton Gamma Ray Observatory (CGRO) have observed PSR B1055-52 a number of times between 1991 and 1998. From these data, a more detailed picture of the gamma radiation from this source has been developed, showing several characteristics which distinguish this pulsar: the light curve is complex; there is no detectable unpulsed emission; the energy spectrum is flat, with no evidence of a sharp high-energy cutoff up to greater than 4 GeV. Comparisons of the gamma-ray data with observations at longer wavelengths show that no two of the known gamma-ray pulsars have quite the same characteristics; this diversity makes interpretation in terms of theoretical models difficult.

  4. Primary stress responses in Arabidopsis thaliana exposed to gamma radiation.

    PubMed

    Vanhoudt, Nathalie; Horemans, Nele; Wannijn, Jean; Nauts, Robin; Van Hees, May; Vandenhove, Hildegarde

    2014-03-01

    As the environment is inevitably exposed to ionizing radiation from natural and anthropogenic sources, it is important to evaluate gamma radiation induced stress responses in plants. The objective of this research is therefore to investigate radiation effects in Arabidopsis thaliana on individual and subcellular level by exposing 2-weeks-old seedlings for 7 days to total doses of 3.9 Gy, 6.7 Gy, 14.8 Gy and 58.8 Gy and evaluating growth, photosynthesis, chlorophyll a, chlorophyll b and carotenoid concentrations and antioxidative enzyme capacities. While the capacity of photosystem II (PSII measured as Fv/Fm) remained intact, plants started optimizing their photosynthetic process at the lower radiation doses by increasing the PSII efficiency (φPSII) and the maximal electron transport rate (ETRmax) and by decreasing the non-photochemical quenching (NPQ). At the highest radiation dose, photosynthetic parameters resembled those of control conditions. On subcellular level, roots showed increased superoxide dismutase (SOD) and ascorbate peroxidase (APX) capacities under gamma irradiation but catalase (CAT), syringaldazine peroxidase (SPX) and guaiacol peroxidase (GPX) activities, on the other hand, decreased. In the leaves no alterations were observed in SOD, CAT and SPX capacities, but GPX was highly affected. Based on these results it seems that roots are more sensitive for oxidative stress under gamma radiation exposure than leaves. PMID:24333636

  5. Stability of a salicylate-based poly(anhydride-ester) to electron beam and gamma radiation

    PubMed Central

    Rosario-Meléndez, Roselin; Lavelle, Linda; Bodnar, Stanko; Halperin, Frederick; Harper, Ike; Griffin, Jeremy; Uhrich, Kathryn E.

    2011-01-01

    The effect of electron beam and gamma radiation on the physicochemical properties of a salicylate-based poly(anhydride-ester) was studied by exposing polymers to 0 (control), 25 and 50 kGy. After radiation exposure, salicylic acid release in vitro was monitored to assess any changes in drug release profiles. Molecular weight, glass transition temperature and decomposition temperature were evaluated for polymer chain scission and/or crosslinking as well as changes in thermal properties. Proton nuclear magnetic resonance and infrared spectroscopies were also used to determine polymer degradation and/or chain scission. In vitro cell studies were performed to identify cytocompatibility following radiation exposure. These studies demonstrate that the physicochemical properties of the polymer are not substantially affected by exposure to electron beam and gamma radiation. PMID:21909173

  6. Sewage sludge pasteurization by gamma radiation: Financial viability case studies

    NASA Astrophysics Data System (ADS)

    Swinwood, Jean F.; Kotler, Jiri

    This paper examines the financial viability of sewage sludge pasteurization by gamma radiation, by examining the following three North American scenarios: 1) Small volume sewage treatment plant experiencing high sludge disposal costs. 2) Large volume sewage treatment plant experiencing low sludge disposal costs. 3) Large volume sewage treatment plant experiencing high sludge disposal costs.

  7. GAMMA RADIATION TREATMENT OF WATERS FROM LIGNITE MINES

    EPA Science Inventory

    Discussed in this report are results of laboratory investigations carried out with the application of gamma radiation for the purification of waters drained from surface lignite mines. These waters are polluted to a considerable extent with suspended matter of various sizes, a la...

  8. Carbon Nanotubes Synthesis Through Gamma Radiation

    NASA Astrophysics Data System (ADS)

    Tirado, Pablo; Garcia, Rafael; Montes, Jorge; Melendrez, Rodrigo; Barboza, Marcelino; Contreras, Oscar

    2015-03-01

    Carbon nanotubes show a great potential of applications since there discovery by Iijima in 1991[1] due to their numerous physical-chemical properties such as their high weight to strength relationship, which make them ideal to use in high resistance compound materials, and in many other applications[2] In this work, a novel method for the synthesis of carbon nanotubes is presented, starting from an ultra-thin sheet of graphite synthesized by the chemical vapor decomposition technique (CVD), using ultra high purity methane and hydrogen at 1200°C in a horizontal quartz reactor. For the synthesis of carbon nanotubes, the graphite sheets were exposed to different doses of radiation, with the objective of breaking the graphite bonds and form carbon nanotubes; a Gammacell equipment model 220 Excel was used for the purpose, which counts with a radiation source of cobalt 60, and a current radiation rate of 0.9 Gy/seconds. The time of exposure to radiation was varied in each sample, according to the desired dose of radiation in each case, afterwards the samples were characterized using the Raman spectroscopy and TEM microscopy techniques with the objective of observing the kind of nanotubes formed, their morphology and their number of defects. Results will be shown during the poster session.

  9. Bioburden assessment and gamma radiation inactivation patterns in parchment documents

    NASA Astrophysics Data System (ADS)

    Nunes, Inês; Mesquita, Nuno; Cabo Verde, Sandra; Carolino, Maria Manuela; Portugal, António; Botelho, Maria Luísa

    2013-07-01

    Parchment documents are part of our cultural heritage and, as historical artifacts that they are, should be preserved. The aim of this study was to validate an appropriate methodology to characterize the bioburden of parchment documents, and to assess the growth and gamma radiation inactivation patterns of the microbiota present in that material. Another goal was to estimate the minimum gamma radiation dose (Dmin) to be applied for the decontamination of parchment as an alternative treatment to the current toxic chemical and non-chemical decontamination methods. Two bioburden assessment methodologies were evaluated: the Swab Method (SM) and the Destructive Method (DM). The recovery efficiency of each method was estimated by artificial contamination, using a Cladosporium cladosporioides spore suspension. The parchment samples' microbiota was typified using morphological methods and the fungal isolates were identified by ITS-DNA sequencing. The inactivation pattern was assessed using the DM after exposure to different gamma radiation doses, and using C. cladosporioides as reference. Based on the applied methodology, parchment samples presented bioburden values lower than 5×103 CFU/cm2 for total microbiota, and lower than 10 CFU/cm2 for fungal propagules. The results suggest no evident inactivation trend for the natural parchment microbiota, especially regarding the fungal community. A minimum gamma radiation dose (Dmin) of 5 kGy is proposed for the decontamination treatment of parchment. Determining the minimal decontamination dose in parchment is essential for a correct application of gamma radiation as an alternative decontamination treatment for this type of documents avoiding the toxicity and the degradation promoted by the traditional chemical and non-chemical treatments.

  10. Radiation effect on silicon transistors in mixed neutrons-gamma environment

    NASA Astrophysics Data System (ADS)

    Assaf, J.; Shweikani, R.; Ghazi, N.

    2014-10-01

    The effects of gamma and neutron irradiations on two different types of transistors, Junction Field Effect Transistor (JFET) and Bipolar Junction Transistor (BJT), were investigated. Irradiation was performed using a Syrian research reactor (RR) (Miniature Neutron Source Reactor (MNSR)) and a gamma source (Co-60 cell). For RR irradiation, MCNP code was used to calculate the absorbed dose received by the transistors. The experimental results showed an overall decrease in the gain factors of the transistors after irradiation, and the JFETs were more resistant to the effects of radiation than BJTs. The effect of RR irradiation was also greater than that of gamma source for the same dose, which could be because neutrons could cause more damage than gamma irradiation.

  11. Co-60 gamma radiation assisted diffusion of iodine in polypropylene

    NASA Astrophysics Data System (ADS)

    Mathakari, N. L.; Bhoraskar, V. N.; Dhole, S. D.

    2010-09-01

    Thin films of polypropylene having dimensions 50 mm × 15 mm × 350 μm were immersed in 1 N iodine solution and then irradiated with Co-60 gamma radiation for the periods of 48, 96 and 144 h at the doses varying from 14.4 to 43.2 kGy. The films were also kept immersed in iodine solution for similar periods but without irradiation. Furthermore, the films were also directly-irradiated with Co-60 gamma radiation for similar periods and doses. The radiation-iodinated, plain-iodinated and directly-irradiated samples were characterized by using various techniques such as weight gain EDS, SEM, FTIR, UV-visible spectroscopy, contact angle and XRD. Weight gain, EDS and SEM collectively reveal that gamma irradiation enhances iodine intake in polypropylene. FTIR, EDS and contact angle measurements indicate that presence of iodine during irradiation resists radiation induced carbonylation of polypropylene. FTIR also shows presence of HOI (Hypoiodous acid) species instead of expected C-I bonds. UV-visible analysis unambiguously shows that presence of iodine enhances radiation induced band gap reduction process of polypropylene. XRD indicates that iodine decreases the crystallinity of polypropylene.

  12. Rheology of Indian Honey: Effect of Temperature and Gamma Radiation

    PubMed Central

    Panicker, Lata; Gautam, Satyendra

    2014-01-01

    Honey brands commonly available in Indian market were characterized for their rheological and thermal properties. Viscosity of all the honey samples belonging to different commercial brands was found to decrease with increase in temperature (5–40°C) and their sensitivity towards temperature varied significantly as explained by calculating activation energy based on Arrhenius model and ranged from 54.0 to 89.0 kJ/mol. However, shear rate was not found to alter the viscosity of honey indicating their Newtonian character and the shear stress varied linearly with shear rate for all honey samples. Honey is known to contain pathogenic microbial spores and in our earlier study gamma radiation was found to be effective in achieving microbial decontamination of honey. The effect of gamma radiation (5–15 kGy) on rheological properties of honey was assessed, and it was found to remain unchanged upon radiation treatment. The glass transition temperatures (Tg) of these honey analyzed by differential scanning calorimetry varied from −44.1 to −54.1°C and remained unchanged upon gamma radiation treatment. The results provide information about some key physical properties of commercial Indian honey. Radiation treatment which is useful for ensuring microbial safety of honey does not alter these properties. PMID:26904655

  13. Design and development of a portable gamma radiation monitor

    NASA Astrophysics Data System (ADS)

    Munir, M.; Ahmad, N.; Sohail, S.; Naveed, R. A.; Rafiq, M. Q.; Khalid, M.

    2009-07-01

    A portable gamma radiation monitor has been designed and developed. The monitor can be used effectively in the dose range from 0.07 to 500 mGy/h due to gamma rays of energy greater than 65 keV. The monitor overestimated radiation doses and the uncertainty in the measured dose rate has been found to be ≤30%. The response of the monitor can be considered isotropic within an acceptable error of ±30%. Provision has also been added to use the monitor as an installed radiation monitor. In installed mode, it can be operated from a remote location up to 1 km and the timing history can be stored on a personal computer.

  14. Design and development of a portable gamma radiation monitor

    SciTech Connect

    Munir, M.; Khalid, M.; Ahmad, N.; Sohail, S.; Naveed, R. A.; Rafiq, M. Q.

    2009-07-15

    A portable gamma radiation monitor has been designed and developed. The monitor can be used effectively in the dose range from 0.07 to 500 mGy/h due to gamma rays of energy greater than 65 keV. The monitor overestimated radiation doses and the uncertainty in the measured dose rate has been found to be {<=}30%. The response of the monitor can be considered isotropic within an acceptable error of {+-}30%. Provision has also been added to use the monitor as an installed radiation monitor. In installed mode, it can be operated from a remote location up to 1 km and the timing history can be stored on a personal computer.

  15. A study of the diffuse galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Kniffen, D. A.

    1984-01-01

    The observed diffuse galactic gamma radiation is compared to that predicted from galactic cosmic ray interactions with galactic matter and photons, assuming that on a broad scale the galactic cosmic rays in the plane are correlated with matter density. Recent considerations of the galactic diffuse matter distribution, particularly the molecular hydrogen, the galactic photon density, and a revised cosmic ray galactic scale height, are included. The predictions are compared to the observational gamma ray longitude distributions, the latitude distribution, and energy spectrum, including the COS-B satellite results, and the COS-B background estimate. Considering the uncertainties, the agreement between the theoretical predictions and the gamma ray data seems generally reasonable, suggesting that the general concepts are likely to be correct. Both the results determined here alone and in conjunction with other work calculating source functions assuming only cosmic ray matter contributions indicate no necessity for a significant point source contribution to the diffuse gamma radiation in the energy range being considered (E(gamma)10 MeV).

  16. A study of the diffuse galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Kniffen, D. A.

    1984-01-01

    The observed diffuse galactic gamma radiation is compared to that predicted from galactic cosmic ray interactions with galactic matter and photons, assuming that on a broad scale the galactic cosmic rays in the plane are correlated with matter density. Recent considerations of the galactic diffuse matter distribution, particularly the molecular hydrogen, the galactic photon density, and a revised cosmic ray galactic scale height, are included. The predictions are compared to the observational gamma ray longitude distributions, the latitude distribution, and energy spectrum, including the COS-B satellite results, and the COS-B background estimate. Considering the uncertainties, the agreement between the theoretical predictions and the gamma ray data seems generally reasonable, suggesting that the general concepts are likely to be correct. Both the results determined here alone and in conjunction with other work calculating source functions assuming only cosmic ray matter contributions indicate no necessity for a significant point source contribution to the diffuse gamma radiation in the energy range being considered (E(gamma)10 MeV). Previously announced in STAR as N84-18151

  17. Effects of gamma radiation on spermatogenesis and fertility of male Amblyomma americanum (Acari: Ixodidae)

    SciTech Connect

    Oliver, J.H. Jr.; Stanley, M.A.

    1987-04-01

    Amblyomma americanum males were treated with 0.5, 1, 2, 3, 4, 8, and 16 krad of gamma radiation. Testes of ticks treated with 2, 3, 4, 8, and 16 krad were smaller than those of ticks irradiated at lower levels and controls. No recognizable alteration in timing of spermatogenesis was noted among the different radiation groups, but severe breakdown and depletion of germinal cells was noted at 4, 8, and 16 krad. Percent hatch of larvae from crosses of irradiated males and untreated females decreased with increasing radiation level. No hatch was observed from eggs of females mated to males treated at 2 krad or higher.

  18. [The effectiveness of fractionated exposure of sarcoma M-1 to gamma-radiation and fast neutrons].

    PubMed

    Iuzhakov, V V; Sevan'kaeva, L E; Ul'ianenko, S E; Iakovleva, N D; Kuznetsova, M N; Tsyganova, M G; Fomina, N K; Ingel', I E; Lychagin, A A

    2013-01-01

    The effectiveness of fractionated exposure to gamma- and neutron radiation in their separate and combined use on the growth and functional morphology of mutant p53 sarcoma M-1 in rats was studied. Investigation techniques included immunostaining of PCNA and mutant p53 expressing cells, determination of mitotic activity and apoptotic death of tumor cells, as well as computer analysis of microscopic images. The antitumor efficacy of different types of radiation is shown to be determined by different levels of apoptosis induction, reduced proliferation and cellularity. Neutron radiation of the impulse generator has a marked damaging effect on the vasculature and the development of tumor necrosis. Fractionated irradiation at equal daily doses led to the decrease in the relative effectiveness of radio-inactivation of tumor cells. After 9 fractions of irradiation, the calculated value of the RBE of fast neutrons normalized to the input dose of 1 Gy by the coefficient of tumor growth inhibition, a reduced proliferative activity of PCNA and induced apoptosis of tumor cells was 3.4, 3.7 and 3.1, respectively. In the mode of daily superfractionation with splitting the dose in two fractions, the effectiveness of the combined exposure corresponded to the additive effect of gamma- and neutron radiation with a tendency toward synergism. There are reasons to believe that high resistance of sarcoma M-1 to the ionizing radiation impact is due not only to a fraction of hypoxic cells, but also the mutant status of p53 gene. PMID:24450208

  19. Gamma radiation resistant Fabry-Perot fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Liu, Hanying; Miller, Don W.; Talnagi, Joseph

    2002-08-01

    The Nuclear Regulatory Commission (NRC) in 1998 completed a study of emerging technologies that could be applicable to measurement systems in nuclear power plants [H. M. Hashemian [et al.], "Advanced Instrumentation and Maintenance Technologies for Nuclear Power Plants," NUREG/CR-5501 (1998)]. This study concluded that advanced fiber optic sensing technology is an emerging technology that should be investigated. It also indicated that there had been very little research related to performance evaluation of fiber optic sensors in nuclear plant harsh environments, although substantial research has been performed on nuclear radiation effects on optical fibers in the last two decades. A type of Fabry-Perot fiber optic temperature sensor, which is manufactured by Fiso Technologies in Canada, is qualified to be a candidate for potential applications in nuclear radiation environment due to its unique signal processing technique and its resistance to power loss. The gamma irradiation effects on this type of sensors are investigated in this article. Two sensors were irradiated in a gamma irradiation field and one of them was irradiated up to a total gamma dose of 133 Mrad. The sensor on-line performance was monitored during each gamma irradiation test. Furthermore, the sensor static and dynamic performance before and after each irradiation test were evaluated according to the Standard ISA-dS67.06.01 ("Performance Monitoring for Nuclear Safety-Related Instrument Channels in Nuclear Power Plants", Standard ISA-dS67.06.01, Draft 7, Instrument Society of America, 1999). Although several abnormal phenomena were observed, analysis shows that gamma irradiation is not accredited to the abnormal behavior, which implies that this type of sensor is suitable to a gamma irradiation environment with a high gamma dose.

  20. Characterization of commercial proton exchange membrane materials after exposure to beta and gamma radiation

    SciTech Connect

    Thomson, S.N.; Carson, R.; Muirhead, C.; Li, H.; Castillo, I.; Boniface, H.; Suppiah, S.; Ratnayake, A.; Robinson, J.

    2015-03-15

    Proton Exchange Membrane (PEM) type electrolysis cells have a potential use for tritium removal and heavy water upgrading. AECL is currently exposing various commercial PEM materials to both gamma (Cobalt-60 source) and beta (tritiated water) radiation to study the effects of radiation on these materials. This paper summarizes the testing methods and results that have been collected to date. The PEM materials that are or have been exposed to radiation are: Nafion 112, 212, 117 and 1110. Membrane characterization pre- and post- exposure consists of non-destructive inspection (FTIR, SEM/XPS), mechanical (tensile strength, percentage elongation, and modulus), electrical (resistance), or chemical (ion-exchange capacity - IEC). It has appeared that the best characterization techniques to compare exposed versus unexposed membranes were IEC, ultimate tensile strength and percent elongation. These testing techniques are easy and cheap to perform. The non-destructive tests, such as SEM and FTIR did not provide particularly useful information on radiation-induced degradation. Where changes in material properties were measured after radiation exposure, they would be expected to result in poorer cell performance. However, for modest γ-radiation exposure, all membranes showed a slight decrease in cell voltage (better performance). In contrast, the one β-radiation exposed membrane did show the expected increase in cell voltage. The counterintuitive trend for γ-radiation exposed membranes is not yet understood. Based on these preliminary results, it appears that γ- and β-radiation exposures have different effects.

  1. Gamma radiation survey of the LDEF spacecraft

    NASA Technical Reports Server (NTRS)

    Phillips, G. W.; King, S. E.; August, R. A.; Ritter, J. C.; Cutchin, J. H.; Haskins, P. S.; Mckisson, J. E.; Ely, D. W.; Weisenberger, A. G.; Piercey, R. B.

    1992-01-01

    The retrieval of the Long Duration Exposure Facility spacecraft in January 1990 after nearly six years in orbit offered a unique opportunity to study the long term buildup of induced radioactivity in the variety of materials on board. We conducted the first complete gamma-ray survey of a large spacecraft on LDEF shortly after its return to earth. A surprising observation was the Be-7 activity which was seen primarily on the leading edge of the satellite, implying that it was picked up by LDEF in orbit. This is the first known evidence for accretion of a radioactive isotope onto an orbiting spacecraft. Other isotopes observed during the survey, the strongest being Na-22, are all attributed to activation of spacecraft components. Be-7 is a spallation product of cosmic rays on nitrogen and oxygen in the upper atmosphere. However, the observed density is much greater than expected due to cosmic-ray production in situ. This implies transport of Be-7 from much lower altitudes up to the LDEF orbit.

  2. Thermal stability of grafted fibers. [Gamma radiation

    SciTech Connect

    Sundardi, F.; Kadariah; Marlianti, I.

    1983-10-01

    Presented the experimental results on the study of thermal stability of grafted fibers, i.e., polypropylene-, polyester-, and rayon-grafted fibers. These fibers were obtained by radiation grafting processes using hydrophylic monomers such as 1-vinyl 2-pyrolidone, acrylic acid, N-methylol acrylamide, and acrylonitrile. The thermal stability of the fibers was studied using a Shimadzu Thermal Analyzer DT-30. The thermal stability of the fibers, which can be indicated by the value of the activation energy for thermal degradation, was not improved by radiation grafting. The degree of improvement depends on the thermal stability of the monomers used for grafting. The thermal stability of a polypropylene fiber, either a grafted or an ungrafted one, was found to be inferior compared to the polyester of a rayon fiber, which may be due to the lack of C=O and C=C bonds in the polypropylene molecules. The thermal stability of a fiber grafted with acrylonitrile monomer was found to be better than that of an ungrafted one. However, no improvement was detected in the fibers grafted with 1-vinyl 2-pyrrolidone monomer, which may be due to the lower thermal stability of poly(1-vinyl-2-pyrrolidone), compared to the polypropylene or polyester fibers. 17 figures, 3 tables.

  3. Characterization of gamma radiation inducible thioredoxin h from Spirogyra varians.

    PubMed

    Yoon, Minchul; Yang, Ho-Yeon; Lee, Seung-Sik; Kim, Dong-Ho; Kim, Gwang-Hoon; Choi, Jong-il

    2013-08-15

    In this study, thioredoxin h (Trxh) was isolated and characterized from the fresh water green alga Spirogyra varians, which was one amongst the pool of proteins induced upon gamma radiation treatment. cDNA clones encoding S. varians thioredoxin h were isolated from a pre-constructed S. varians cDNA library. Trxh had a molecular mass of 13.5kDa and contained the canonical WCGPC active site. Recombinant Trxh showed the disulfide reduction activity, and exhibited insulin reduction activity. Also, Trxh had higher 5,5'-dithiobis(2-nitrobenzoic acid) reduction activity with Arabidopsis thioredoxin reductase (TR) than with Escherichia coli TR. Specific expression of the Trxh gene was further analyzed at mRNA and protein levels and was found to increase by gamma irradiation upto the absorbed dose of 3kGy, suggesting that Trxh may have potential functions in protection of biomolecules from gamma irradiation. PMID:23830452

  4. Analytical modeling for gamma radiation damage on silicon photodiodes

    NASA Astrophysics Data System (ADS)

    Jafari, H.; Feghhi, S. A. H.

    2016-04-01

    Radiation-induced damage in PIN silicon photodiode induces degradation of the photodiode parameters. In this work, by presenting an analytical model, the effect of gamma dose on the dark current in a PIN photodiode array was investigated. Geant4 was used to obtain the damage constant as a result of primary incident particle fluence and NIEL distribution calculations. Experimental measurements as well as numerical simulation of the semiconductor with ATLAS were carried out to verify and parameterize the analytical model calculations. A reasonable agreement has been found between analytical results and experimental data for BPX65 silicon photodiodes irradiated by a Co-60 gamma source at total doses up to 500 krad under different reverse voltages. Moreover, the results showed that the dark current of each photodiode array pixel has considerably increased by gamma dose irradiation.

  5. Optical Sensors for Monitoring Gamma and Neutron Radiation

    NASA Technical Reports Server (NTRS)

    Boyd, Clark D.

    2011-01-01

    For safety and efficiency, nuclear reactors must be carefully monitored to provide feedback that enables the fission rate to be held at a constant target level via adjustments in the position of neutron-absorbing rods and moderating coolant flow rates. For automated reactor control, the monitoring system should provide calibrated analog or digital output. The sensors must survive and produce reliable output with minimal drift for at least one to two years, for replacement only during refueling. Small sensor size is preferred to enable more sensors to be placed in the core for more detailed characterization of the local fission rate and fuel consumption, since local deviations from the norm tend to amplify themselves. Currently, reactors are monitored by local power range meters (LPRMs) based on the neutron flux or gamma thermometers based on the gamma flux. LPRMs tend to be bulky, while gamma thermometers are subject to unwanted drift. Both electronic reactor sensors are plagued by electrical noise induced by ionizing radiation near the reactor core. A fiber optic sensor system was developed that is capable of tracking thermal neutron fluence and gamma flux in order to monitor nuclear reactor fission rates. The system provides near-real-time feedback from small- profile probes that are not sensitive to electromagnetic noise. The key novel feature is the practical design of fiber optic radiation sensors. The use of an actinoid element to monitor neutron flux in fiber optic EFPI (extrinsic Fabry-Perot interferometric) sensors is a new use of material. The materials and structure used in the sensor construction can be adjusted to result in a sensor that is sensitive to just thermal, gamma, or neutron stimulus, or any combination of the three. The tested design showed low sensitivity to thermal and gamma stimuli and high sensitivity to neutrons, with a fast response time.

  6. Self-occluding quad NaI directional gamma radiation detector for standoff radiation detection

    NASA Astrophysics Data System (ADS)

    Portnoy, David; Mattson, John

    2011-09-01

    Currently there is a significant amount of interest in standoff radiation detection. One of the biggest challenges is to separate small radiation signals from large varying background radiation. Many systems have been developed to address this problem that rely on coded-aperture and/or Compton imaging. These imaging systems tend to be large, heavy, complex, and therefore expensive. In this paper we report on the development of a self-occluding directional gamma radiation sensor that is relatively small (<40 kg), inexpensive, and simple in design. Laboratory and field measurements suggest that these sensors will work as well as the gamma imaging systems for many radiation detection applications at a fraction of the cost, weight, and complexity. An azimuth can be resolved with a standard deviation of 7 in 10 seconds for a source yielding 45 CPS at the detector in a 300 CPS background radiation field. This paper describes the self-occluding quad NaI directional gamma radiation detector, the impact of gamma energy and distance on angular precision and accuracy, and potential applications.

  7. The Gamma-ray galactic diffuse radiation and Cerenkov telescopes

    SciTech Connect

    Chardonnet, P.; Salati, P.; Silk, J.; Grenier, I.; Smoot, G.

    1995-12-01

    By using the PYTHIA version of the Lund Monte Carlo program, we study the photon yield of proton-proton collisions in the energy range between 10 GeV and 1 TeV. The resulting photon spectrum turns out to scale roughly with incident energy. Then, by folding the energy spectrum of cosmic-ray protons with the distribution of HI and CO, the Galactic diffuse emission of {gamma}-rays above 100 GeV is mapped. Prospects for observing that diffuse radiation with atmospheric Cerenkov telescopes are discussed. Present instruments are able to detect the {gamma}-ray glow of the Galactic center. The latter will be mapped by the next generation of telescopes if their energy threshold is decreased. However, a detailed survey of the Galactic ridge will be a real challenge, even in the long term. The MILAGRO project seems more appropriate. Finally, we investigate the {gamma}-ray emission from weakly interacting massive particles clustering at the Galactic center. It has been speculated that those species are a major component of the halo dark matter. We show that their {gamma}-ray signal is swamped in the Galactic diffuse radiation and cannot be observed at TeV energies. {copyright} {ital 1995 The American Astronomical Society.}

  8. Gamma radiation from the Crab and Vela pulsars

    NASA Technical Reports Server (NTRS)

    Kanbach, Gottfried

    1990-01-01

    The young pulsars in Crab and Vela were observed as very efficient emitters of high energy gamma radiation. While their radiation in the radio, optical, and x ray range was always known to differ considerably, the gamma ray emission on a superficial level appears quite similar: lightcurves with two narrow peaks, separated by 141 deg (Crab) and 153 deg (Vela) and photon energies in excess of 1 GeV with spectra that can be described by a power-law for Crab and a broken power-law for Vela. The detailed observations of these sources with the COS-B instrument, extending over nearly seven years, have revealed significant differences in the characteristics of the pulsars in the gamma-ray domain. Secular changes in the temporal (Crab) and spectral (Vela) properties above 50 MeV were found. These tantalizing signatures of the pulsar emission processes must now be explored in more detail and over a larger spectral range with the GRO (Gamma Ray Observatory) instruments in order to gain a deeper understanding of the physics of young neutron stars.

  9. Titanium-Water Thermosyphon Gamma Radiation Exposure and Results

    NASA Technical Reports Server (NTRS)

    Sanzi, James, L.A; Jaworske, Donald, A.; Goodenow, Debra, A.

    2012-01-01

    Titanium-water thermosyphons are being considered for use in heat rejection systems for fission power systems. Their proximity to the nuclear reactor will result in some gamma irradiation. Noncondensable gas formation from radiation-induced breakdown of water over time may render portions of the thermosyphon condenser inoperable. A series of developmental thermosyphons were operated at nominal operating temperature under accelerated gamma irradiation, with exposures on the same order of magnitude as that expected in 8 years of heat rejection system operation. Temperature data were obtained during exposure at three locations on each thermosyphon: evaporator, condenser, and condenser end cap. Some noncondensable gas was evident; however, thermosyphon performance was not affected because the noncondensable gas was compressed into the fill tube region at the top of the thermosyphon, away from the heat rejecting fin. The trend appeared to be an increasing amount of noncondensable gas formation with increasing gamma irradiation dose. Hydrogen is thought to be the most likely candidate for the noncondensable gas and hydrogen is known to diffuse through grain boundaries. Post-exposure evaluation of one thermosyphon in a vacuum chamber and at temperature revealed that the noncondensable gas diffused out of the thermosyphon over a relatively short period of time. Further research shows a number of experimental and theoretical examples of radiolysis occurring through gamma radiation alone in pure water.

  10. Titanium-Water Thermosyphon Gamma Radiation Effects and Results

    NASA Technical Reports Server (NTRS)

    Sanzi, James L.; Jaworske, Donald A.; Goodenow, Debra A.

    2012-01-01

    Titanium-water thermosyphons are being considered for use in heat rejection systems for fission power systems. Their proximity to the nuclear reactor will result in some exposure to gamma irradiation. Non-condensable gas formation from radiation may breakdown water over time and render a portion of the thermosyphon condenser inoperable. A series of developmental thermosyphons were operated at nominal operating temperature with accelerated gamma irradiation exposures on the same order of magnitude that is expected in eight years of heat rejection system operation. Temperature data were obtained during exposure at three locations on each thermosyphon; evaporator, condenser, and condenser end cap. Some non-condensable gas was evident, however thermosyphon performance was not affected because the non-condensable gas was compressed into the fill tube region at the top of the thermosyphon, away from the heat rejecting fin. The trend appeared to be an increasing amount of non-condensable gas formation with increasing gamma irradiation dose. Hydrogen is thought to be the most likely candidate for the non-condensable gas and hydrogen is known to diffuse through grain boundaries. Post-exposure evaluation of selected thermosyphons at temperature and in a vacuum chamber revealed that the non-condensable gas likely diffused out of the thermosyphons over a relatively short period of time. Further research shows a number of experimental and theoretical examples of radiolysis occurring through gamma radiation alone in pure water.

  11. Characterization of muon and gamma radiations at the PTOLEMY site

    NASA Astrophysics Data System (ADS)

    Betts, Susannah; Gentile, Charles; Tully, Chris; Zapata, Sandra; Chris Tully Collaboration

    2013-10-01

    PTOLEMY is an experimental project at Princeton Plasma Physics Laboratory designed to determine the present day number density of relic neutrinos through measurement of electrons produced from neutrino capture on tritium. The weak interaction cross section for relic neutrino interactions necessitates high sensitivity measurements that could be influenced by high energy particles, like muons and gamma ray photons, which induce nuclear transitions and secondary electrons. Muons produced from the collision of cosmic rays with atmospheric nuclei are a significant source of background radiation at and below Earth's surface. The muon flux is measured by the coincidence of minimum ionization radiation loss in two plastic scintillator paddles. The spectrum of gamma ray photons is measured using sodium iodide based scintillators. These measurements will provide a characterization of the background and rates at the PTOLEMY site.

  12. Airborne gamma radiation soil moisture measurements over short flight lines

    NASA Technical Reports Server (NTRS)

    Peck, Eugene L.; Carrol, Thomas R.; Lipinski, Daniel M.

    1990-01-01

    Results are presented on airborne gamma radiation measurements of soil moisture condition, carried out along short flight lines as part of the First International Satellite Land Surface Climatology Project Field Experiment (FIFE). Data were collected over an area in Kansas during the summers of 1987 and 1989. The airborne surveys, together with ground measurements, provide the most comprehensive set of airborne and ground truth data available in the U.S. for calibrating and evaluating airborne gamma flight lines. Analysis showed that, using standard National Weather Service weights for the K, Tl, and Gc radiation windows, the airborne soil moisture estimates for the FIFE lines had a root mean square error of no greater than 3.0 percent soil moisture. The soil moisture estimates for sections having acquisition time of at least 15 sec were found to be reliable.

  13. Modification of microcrystalline cellulose by gamma radiation-induced grafting

    NASA Astrophysics Data System (ADS)

    Madrid, Jordan F.; Abad, Lucille V.

    2015-10-01

    Modified microcrystalline cellulose (MCC) was prepared through gamma radiation-induced graft polymerization of glycidyl methacrylate (GMA). Simultaneous grafting was employed wherein MCC with GMA in methanol was irradiated with gamma radiation in nitrogen atmosphere. The effects of different experimental factors such as monomer concentration, type of solvent and absorbed dose on the degree of grafting, Dg, were studied. The amount of grafted GMA, expressed as Dg, was determined gravimetrically. Information from grafted samples subjected to Fourier transformed infrared spectroscopy (FTIR) in attenuated total reflectance (ATR) mode showed peaks corresponding to GMA which indicates successful grafting. The X-ray diffraction (XRD) analysis revealed that the crystalline region of MCC was not adversely affected after grafting with GMA. The thermogravimetric analysis (TGA) data showed that the decomposition of grafted MCC occurred at higher temperature compared to the base MCC polymer.

  14. A hemispherical high-pressure xenon gamma radiation spectrometer

    NASA Astrophysics Data System (ADS)

    Kessick, Royal; Tepper, Gary

    2002-09-01

    A prototype hemispherical high-pressure xenon gamma radiation spectrometer was designed, constructed and tested. The detector consists of a pair of concentric hemispherical electrodes contained inside a thin-walled stainless steel pressure dome. Detector performance parameters such as energy resolution, linearity and vibration sensitivity were determined and compared to previous cylindrical and planar designs. Without a Frisch grid, the hemispherical detector provides a total room temperature energy resolution of 6% @ 662 keV and is relatively insensitive to acoustic interference.

  15. Gamma radiation induced effects on slaughterhouse wastewater treatment

    NASA Astrophysics Data System (ADS)

    Melo, Rita; Cabo Verde, Sandra; Branco, Joaquim; Botelho, M. Luisa

    2008-01-01

    A preliminary study using gamma radiation on slaughterhouse wastewater samples was carried out. Chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total suspended solids (TSS) results were obtained at a dose rate of 0.9 kGy h -1. A decrease of COD, BOD and colour was observed after irradiation at high absorbed doses. The microbiological results, following irradiation in the same conditions, correlated with the BOD results. The results obtained highlight the potential of this technology for wastewater treatment.

  16. Influence of gamma radiation onto polymeric matrix with papain

    NASA Astrophysics Data System (ADS)

    Zulli, Gislaine; Lopes, Patrícia Santos; Velasco, Maria Valéria Robles; Alcântara, Mara Tânia Silva; Rogero, Sizue Ota; Lugao, Ademar Benévolo; Mathor, Monica Beatriz

    2010-03-01

    Papain is a proteolytic enzyme that has been widely used as debridement agent for scars and wound healing treatment. However, papain presents low stability, which limits its use to extemporaneous or short shelf-life formulations. The purpose of this study was to entrap papain into a polymeric matrix in order to obtain a drug delivery system that could be used as medical device. Since these systems must be sterile, gamma radiation is an interesting option and presents advantages in relation to conventional agents: no radioactive residues are formed; the product can be sterilized inside the final packaging and has an excellent reliability. The normative reference for the establishment of the sterilizing dose determines 25 kGy as the inactivation dose for viable microorganisms. A silicone dispersion was selected to prepare membranes containing 2% (w/w) papain. Irradiated and non-irradiated membranes were simultaneously assessed in order to verify whether gamma radiation interferes with the drug-releasing profile. Results showed that irradiation does not affect significantly papain release and its activity. Therefore papain shows radioresistance in the irradiation conditions applied. In conclusion, gamma radiation can be easily used as sterilizing agent without affecting the papain release profile and its activity onto the biocompatible device is studied.

  17. Gamma radiation induced micronuclei and erythrocyte cellular abnormalities in the fish Catla catla.

    PubMed

    Anbumani, S; Mohankumar, Mary N

    2012-10-15

    Ionizing radiation induced DNA damage in fishes is a scarcely studied topic and very few studies are available in fishes exposed to ionizing radiation using the erythrocyte micronucleus assay under laboratory conditions. Since radionuclides released accidentally or during a nuclear disaster can contaminate inland water bodies, biomonitoring methods are required for assessing the impacts of high and low levels of radiation that may ultimately result in ionizing radiation exposure to both humans and non-human biota. Fresh water fish, Catla catla were subjected to protracted (0.002 Gy/min) and acute (3.2 Gy/min) gamma radiation to a total dose of 5 Gy. Peripheral blood samples were collected at different intervals (days 3, 6, 12, 18, 30, 45, 90, 135, 202) and analyzed by the erythrocyte micronucleus assay. Nuclear anomalies observed were micronuclei (MN), deformed nuclei (DN), nuclear bud (NBu), nuclear bridge (NBr), vacuolated nucleus (VN), binucleated cell (BNC), apoptotic cells (AC) while cytoplasmic abnormalities detected were vacuolated cytoplasm (VC), anisochromasia (AN), echinocytes (EC) and enucleus (EN). Both exposures caused a statistically significant increase in nuclear and cytoplasmic abnormalities that correlated with micronucleus and other nuclear anomalies. However, the extent of damage is higher after an acute exposure lasting for a longer period leading to apoptosis. Nuclear and cytoplasmic abnormalities are the resultants of gamma radiation induced genotoxicity and cytotoxicity. PMID:22771702

  18. Effect of gamma radiation on membrane fluidity of MOLT-4 nuclei

    SciTech Connect

    McClain, D.E.; Trypus, C.A.; May, L.

    1990-01-01

    These experiments measured the effect of gamma radiation on the nuclear envelope using doxyl-fatty acid spin-label probes. Nuclei were isolated from cultured MOLT-4 cells, a radiation-sensitive human T-cell lymphocyte. Membrane fluidity was measured from the electron paramagnetic resonance spectra of the probes. MOLT-4 cells were grown under standard conditions, and suspension were exposed to CO radiation at room temperature. The spectra of 5-doxylstearic acid in the nuclei were those of a strongly immobilized label. A difference in the membrane fluidity was detected in a series of experiments comparing labeled irradiated and nonirradiated nuclei. The change in fluidity was measured by comparing the changes in the order parameter, S, of the spin label in irradiated nuclei with those in control nuclei.

  19. Human gamma delta T-cell recognition of Yersinia enterocolitica.

    PubMed Central

    Young, J L; Goodall, J C; Beacock-Sharp, H; Gaston, J S

    1997-01-01

    We have studied the human gamma delta T-cell response to Yersinia enterocolitica, a facultative intracellular bacterium which causes gastroenteritis and, particularly in human leucocyte antigen (HLA)-B27+ individuals, reactive arthritis (ReA). A marked proliferation of that cytotoxic gamma delta T cells is seen when Yersinia-infected lymphoblastoid cell lines or fixed intact Yersinia are added to cultures of mononuclear cells derived from the synovial fluid of ReA patients or from the peripheral blood of healthy donors. In contrast, heat-inactivated Yersinia fail to stimulate the gamma delta T-cell response. The gamma delta T-cell lines generated killed both autologous and allogeneic infected cell lines. Interestingly, a T-cell line generated from synovial fluid mononuclear cells (SFMC) killed infected autologous cell lines and a cell line matched for HLA-B27 less well than infected allogeneic target cells. gamma delta T-cell clones isolated from this line were found to express V gamma 9V delta 2 T-cell receptor (TCR) and also killed infected mismatched cells more efficiently than autologous targets. Moreover, from experiments using major histocompatability complex (MHC)-deficient cell lines, it was apparent that target cell recognition was MHC independent. Our results suggest that gamma delta T cells can be involved in immunity to Yersinia enterocolitica and should be taken into account when considering immunopathological mechanisms leading to reactive arthritis. PMID:9378487

  20. Effects of proton and gamma radiation on lymphocyte populations and acute response to antigen

    NASA Technical Reports Server (NTRS)

    Kajioka, E. H.; Gheorghe, C.; Andres, M. L.; Abell, G. A.; Folz-Holbeck, J.; Slater, J. M.; Nelson, G. A.; Gridley, D. S.

    1999-01-01

    BACKGROUND: The clinical use of proton radiation in the management of cancer, as well as benign disorders, is rapidly increasing. The major goal of this study was to compare the effects of proton and gamma (60Co) radiation on cell-mediated and humoral immunological parameters. MATERIALS AND METHODS: C57BL/6 mice were exposed to a single dose of 3 Gray (Gy) protons or gamma-rays and intraperitoneally injected 1 day later with sheep red blood cells (sRBC). On 4, 10, 15, and 29 days after exposure, subsets from each group were euthanised; nonirradiated controls (with and without sRBC injection) were included. Body and relative spleen weights, leukocyte counts, spontaneous blastogenesis, lymphocyte populations, and anti-sRBC titers were evaluated. RESULTS: The data showed significant depression (p < 0.05) in nearly all assays on days 4 and 10 after irradiation. B lymphocytes (CD19+) were the most radiosensitive, although reconstitution back to normal levels was observed by day 15. T cell (CD3+) and T helper cell (CD4+) recovery was evident by day 29, whereas the T cytotoxic cell (CD8+) count remained significantly below normal. Natural killer cells (NK1.1+) were relatively radioresistant. Anti-sRBC antibody production was slow and low titers were obtained after irradiation. No significant differences were noted between the two types of radiation. CONCLUSIONS: Taken together, the data show that whole-body irradiation with protons or gamma-rays, at the dose employed, results in marked, but transient, immunosuppression. However, at the time points of testing and with the assays used, little or no differences were found between the two forms of radiation.

  1. Effects of gamma-Radiation on Select Lipids and Antioxidants

    NASA Technical Reports Server (NTRS)

    Gandolph, Jacob; Mauer, Lisa; Perchonok, Michele

    2006-01-01

    Radiation encountered on an extended duration space mission (estimates of 3 Sieverts for a mission to Mars) poses a threat not only to human health, but also to the quality, nutritional value, and palatability of the food system. Free radicals generated by radiation interaction with foods may initiate many unwanted reactions including: 1) autoxidation in lipids that alters flavor, odor, and concentrations of essential fatty acids, and 2) depletion of antioxidants food products and dietary supplements. Studies have shown that antioxidants may provide long term health protection from oxidative stress caused by radiation exposure; therefore, consumption of antioxidants will be important. Stability of essential fatty acids is also important for astronauts long-term health status. The objectives of this study were to characterize the effects of low dose gamma-radiation on lipids and antioxidants by monitoring oxidation and reducing power, respectively, in model systems. Select oils and antioxidants were exposed to levels of gamma-radiation ranging from 0 to 1000 Gy (1 Gy = 1 Sv) using a Gammacell 220 and stored at ambient or elevated temperatures (65 C) for up to 3 months prior to analysis. A Fricke dosimeter was used to verify differences between the radiation doses administered. Primary and secondary products of lipid oxidation in soybean and peanut oils were monitored using conjugated diene and 2-thiobarbituric acid (TBARs) assays. Changes in fatty acid composition and formation and vitamin E levels were also measured. The reducing power of antioxidant compounds, including vitamins C and E and beta-carotene, was determined using the ferric reducing antioxidant power (FRAP) assay. Significant differences (alpha =0.05) were present between all radiation doses tested using the Fricke dosimeter. Increasing radiation doses above 3 Sv resulted in significantly (alpha =0.05) elevated levels of oxidation and free fatty acids in soybean and peanut oils. Decreases in concentrations of essential fatty acids upon increasing radiation doses were also observed. Increasing radiation doses caused significant (alpha =0.05) decreases in reducing power and hence the effectiveness of vitamins C and E as well as beta-carotene. This work establishes a need for quantifying the effects of space relevant radiation doses in the development of a food system for an extended duration mission and for identifying threshold radiation levels that will impact the useful shelf-life of the variety of foods that will be sent. Eventual rancidity of lipids and the loss of antioxidant bioprotective effects are major concerns for the acceptability and nutritional profile of a food system.

  2. Coherent Synchrotron Radiation of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Gainullin, K. G.; Zlobin, A. M.

    By now there is no doubt that the gamma-ray bursts (GRB) have a cosmological origin. This allows to regard GRB as the most powerful known energy sources, ? 1054 erg (with a total number of gamma quanta N? 1060). A plausible mechanism of coherent synchrotron radiation (CSR) of relativistic electrons driven by a local magnetic field is studied in this paper. We consider relativistic electrons arising in the Compton scattering of a GRB in directions close to that of the ray from the source to a ground-based observer. The synchrotron pulses from Compton electrons located at different points on the line between the GRB source and the observer arrive at the observation point simultaneously. This simultaneity ensures the coherence of the detected radiation. Both molecular clouds in the host galaxy of the GRB and our own Galaxy, as well as the Earth atmosphere are assumed to be scatterers of the GRB radiation. Signals of each scatterer reach the Earth surface, and can be detected at radio wavelengths. We estimate the characteristics of this radiation. The comparison of GRB data with the corresponding information on CSR pulses offers a way to determine some global characteristics of the medium between the Earth and the GRB source.

  3. Coherent Synchrotron Radiation of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Gainullin, K. G.; Zlobin, A. M.

    2005-06-01

    By now there is no doubt that the gamma-ray bursts (GRB) have a cosmological origin. This allows to regard GRB as the most powerful known energy sources, ? 1054 erg (with a total number of gamma quanta N_? 1060). A plausible mechanism of coherent synchrotron radiation (CSR) of relativistic electrons driven by a local magnetic field is studied in this paper. We consider relativistic electrons arising in the Compton scattering of a GRB in directions close to that of the ray from the source to a ground-based observer. The synchrotron pulses from Compton electrons located at different points on the line between the GRB source and the observer arrive at the observation point simultaneously. This simultaneity ensures the coherence of the detected radiation. Both molecular clouds in the host galaxy of the GRB and our own Galaxy, as well as the Earth atmosphere are assumed to be scatterers of the GRB radiation. Signals of each scatterer reach the Earth surface, and can be detected at radio wavelengths. We estimate the characteristics of this radiation. The comparison of GRB data with the corresponding information on CSR pulses offers a way to determine some global characteristics of the medium between the Earth and the GRB source.

  4. On the omnipresent background gamma radiation of the continuous spectrum

    NASA Astrophysics Data System (ADS)

    Banjanac, R.; Maleti?, D.; Jokovi?, D.; Veselinovi?, N.; Dragi?, A.; Udovi?i?, V.; Ani?in, I.

    2014-05-01

    The background spectrum of a germanium detector, shielded from the radiations arriving from the lower and open for the radiations arriving from the upper hemisphere, is studied by means of absorption measurements, both in a ground level and in an underground laboratory. The low-energy continuous portion of this background spectrum that peaks at around 100 keV, which is its most intense component, is found to be of very similar shape at the two locations. It is established that it is mostly due to the radiations of the real continuous spectrum, which is quite similar to the instrumental one. The intensity of this radiation is in our cases estimated to about 8000 photons/(m2s2?srad) in the ground level laboratory, and to about 5000 photons/(m2s2?srad) in the underground laboratory, at the depth of 25 m.w.e. Simulations by GEANT4 and CORSIKA demonstrate that this radiation is predominantly of terrestrial origin, due to environmental gamma radiations scattered off the materials that surround the detector (the "skyshine radiation"), and to a far less extent to cosmic rays of degraded energy.

  5. IFN-{gamma}+ CD8+ T Lymphocytes: Possible Link Between Immune and Radiation Responses in Tumor-Relevant Hypoxia

    SciTech Connect

    De Ridder, Mark Jiang Heng; Esch, Gretel van; Law, Kalun; Monsaert, Christinne; Berge, Dirk L. van den; Verellen, Dirk; Verovski, Valeri N.; Storme, Guy A.

    2008-07-01

    Activated T lymphocytes are known to kill tumor cells by triggering cytolytic mechanisms; however, their ability to enhance radiation responses remains unclear. This study examined the radiosensitizing potential of mouse CD8+ T cells, obtained by T-cell-tailored expansion and immunomagnetic purification. Activated CD8+ T cells displayed an interferon (IFN)-{gamma}+ phenotype and enhanced by 1.8-fold the radiosensitivity of EMT-6 tumor cells in 1% oxygen, which modeled tumor-relevant hypoxia. Radiosensitization was counteracted by neutralizing IFN-{gamma} or by blocking the inducible isoform of nitric oxide synthase, thus delineating the immune-tumor cell interaction through the IFN-{gamma} secretion pathway. Reverse transcriptase-polymerase chain reaction, enzyme-linked immunosorbent assay, and fluorescence-activated cell sorter data in agreement detected downregulation of the IFN-{gamma} gene by hypoxia, which caused IFN-{gamma} deficiency next to radioresistance. Therefore, immune and radiation responses are likely to be allied in the hypoxic tumor microenvironment, and CD8+ T cells may bridge immunostimulatory and radiosensitizing strategies.

  6. Gamma radiation induced changes in nuclear waste glass containing Eu

    NASA Astrophysics Data System (ADS)

    Mohapatra, M.; Kadam, R. M.; Mishra, R. K.; Kaushik, C. P.; Tomar, B. S.; Godbole, S. V.

    2011-10-01

    Gamma radiation induced changes were investigated in sodium-barium borosilicate glasses containing Eu. The glass composition was similar to that of nuclear waste glasses used for vitrifying Trombay research reactor nuclear waste at Bhabha Atomic Research Centre, India. Photoluminescence (PL) and electron paramagnetic resonance (EPR) techniques were used to study the speciation of the rare earth (RE) ion in the matrix before and after gamma irradiation. Judd-Ofelt ( J- O) analyses of the emission spectra were done before and after irradiation. The spin counting technique was employed to quantify the number of defect centres formed in the glass at the highest gamma dose studied. PL data suggested the stabilisation of the trivalent RE ion in the borosilicate glass matrix both before and after irradiation. It was also observed that, the RE ion distributes itself in two different environments in the irradiated glass. From the EPR data it was observed that, boron oxygen hole centre based radicals are the predominant defect centres produced in the glass after irradiation along with small amount of E’ centres. From the spin counting studies the concentration of defect centres in the glass was calculated to be 350 ppm at 900 kGy. This indicated the fact that bulk of the glass remained unaffected after gamma irradiation up to 900 kGy.

  7. Gamma-ray pulsars: Radiation processes in the outer magnetosphere

    NASA Technical Reports Server (NTRS)

    Romani, Roger W.

    1996-01-01

    We describe an emission model for gamma ray pulsars based on curvature radiation-reaction limited charges in the outer magnetosphere. We show how pair production on thermal surface flux can limit the acceleration zones. Estimates for the efficiency of GeV photon production eta gamma and the gamma-ray beaming fraction are derived, including their dependence on pulsar parameters. In general eta gamma increases with pulsar age, but is decreased for low magnetic fields and for small magnetic inclinations. We argue that this produces GeV pulse profiles, curvature spectra and detection statistics consistent with the observations. We also describe the optical through X-ray pulsar synchrotron spectrum and the spectral variations with pulsar phase. A test computation for Vela-like parameters reproduces phase-resolved GeV spectra consistent with those observed by EGRET. Finally we comment on very high energy pulsed emission and particle production and note extensions needed to allow a more complete pulsar model.

  8. Biological wound dressings sterilized with gamma radiation: Mexican clinical experience

    NASA Astrophysics Data System (ADS)

    Martínez-Pardo, M. E.; Ley-Chávez, E.; Reyes-Frías, M. L.; Rodríguez-Ferreyra, P.; Vázquez-Maya, L.; Salazar, M. A.

    2007-11-01

    Biological wound dressings sterilized with gamma radiation, such as amnion and pig skin, are a reality in Mexico. These tissues are currently processed in the tissue bank and sterilized in the Gamma Industrial Irradiation Plant; both facilities belong to the Instituto Nacional de Investigaciones Nucleares (ININ) (National Institute of Nuclear Research). With the strong support of the International Atomic Energy Agency, the bank was established at the ININ and the Mexican Ministry of Health issued its sanitary license on July 7, 1999. The Quality Management System of the bank was certified by ISO 9001:2000 on August 1, 2003; the scope of the system is "Research, Development and Processing of Biological Tissues Sterilized with Gamma Radiation". At present, more than 150 patients from 16 hospitals have been successfully treated with these tissues. This paper presents a brief description of the tissue processing, as well as the present Mexican clinical experience with children and adult patients who underwent medical treatment with radiosterilized amnion and pig skin, used as biological wound dressings on burns and ocular surface disorders.

  9. Current Trends in Gamma Radiation Detection for Radiological Emergency Response

    SciTech Connect

    Mukhopadhyay, S., Guss, P., Maurer, R.

    2011-09-01

    Passive and active detection of gamma rays from shielded radioactive materials, including special nuclear materials, is an important task for any radiological emergency response organization. This article reports on the current trends and status of gamma radiation detection objectives and measurement techniques as applied to nonproliferation and radiological emergencies. In recent years, since the establishment of the Domestic Nuclear Detection Office by the Department of Homeland Security, a tremendous amount of progress has been made in detection materials (scintillators, semiconductors), imaging techniques (Compton imaging, use of active masking and hybrid imaging), data acquisition systems with digital signal processing, field programmable gate arrays and embedded isotopic analysis software (viz. gamma detector response and analysis software [GADRAS]1), fast template matching, and data fusion (merging radiological data with geo-referenced maps, digital imagery to provide better situational awareness). In this stride to progress, a significant amount of interdisciplinary research and development has taken place–techniques and spin-offs from medical science (such as x-ray radiography and tomography), materials engineering (systematic planned studies on scintillators to optimize several qualities of a good scintillator, nanoparticle applications, quantum dots, and photonic crystals, just to name a few). No trend analysis of radiation detection systems would be complete without mentioning the unprecedented strategic position taken by the National Nuclear Security Administration (NNSA) to deter, detect, and interdict illicit trafficking in nuclear and other radioactive materials across international borders and through the global maritime transportation–the so-called second line of defense.

  10. Current trends in gamma radiation detection for radiological emergency response

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Sanjoy; Guss, Paul; Maurer, Richard

    2011-09-01

    Passive and active detection of gamma rays from shielded radioactive materials, including special nuclear materials, is an important task for any radiological emergency response organization. This article reports on the current trends and status of gamma radiation detection objectives and measurement techniques as applied to nonproliferation and radiological emergencies. In recent years, since the establishment of the Domestic Nuclear Detection Office by the Department of Homeland Security, a tremendous amount of progress has been made in detection materials (scintillators, semiconductors), imaging techniques (Compton imaging, use of active masking and hybrid imaging), data acquisition systems with digital signal processing, field programmable gate arrays and embedded isotopic analysis software (viz. gamma detector response and analysis software [GADRAS]1), fast template matching, and data fusion (merging radiological data with geo-referenced maps, digital imagery to provide better situational awareness). In this stride to progress, a significant amount of inter-disciplinary research and development has taken place-techniques and spin-offs from medical science (such as x-ray radiography and tomography), materials engineering (systematic planned studies on scintillators to optimize several qualities of a good scintillator, nanoparticle applications, quantum dots, and photonic crystals, just to name a few). No trend analysis of radiation detection systems would be complete without mentioning the unprecedented strategic position taken by the National Nuclear Security Administration (NNSA) to deter, detect, and interdict illicit trafficking in nuclear and other radioactive materials across international borders and through the global maritime transportation-the so-called second line of defense.

  11. Gamma-ray lines from radiative dark matter decay

    SciTech Connect

    Garny, Mathias; Ibarra, Alejandro; Tran, David; Weniger, Christoph E-mail: alejandro.ibarra@ph.tum.de E-mail: weniger@mppmu.mpg.de

    2011-01-01

    The decay of dark matter particles which are coupled predominantly to charged leptons has been proposed as a possible origin of excess high-energy positrons and electrons observed by cosmic-ray telescopes PAMELA and Fermi LAT. Even though the dark matter itself is electrically neutral, the tree-level decay of dark matter into charged lepton pairs will generically induce radiative two-body decays of dark matter at the quantum level. Using an effective theory of leptophilic dark matter decay, we calculate the rates of radiative two-body decays for scalar and fermionic dark matter particles. Due to the absence of astrophysical sources of monochromatic gamma rays, the observation of a line in the diffuse gamma-ray spectrum would constitute a strong indication of a particle physics origin of these photons. We estimate the intensity of the gamma-ray line that may be present in the energy range of a few TeV if the dark matter decay interpretation of the leptonic cosmic-ray anomalies is correct and comment on observational prospects of present and future Imaging Cherenkov Telescopes, in particular the CTA.

  12. The origin of the diffuse background gamma-radiation

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Puget, J. L.

    1974-01-01

    Recent observations have now provided evidence for diffuse background gamma radiation extending to energies beyond 100 MeV. There is some evidence of isotropy and implied cosmological origin. Significant features in the spectrum of this background radiation have been observed which provide evidence for its origin in nuclear processes in the early stages of the big-band cosmology and tie in these processes with galaxy fromation theory. A crucial test of the theory may lie in future observations of the background radiation in the 100 MeV to 100 GeV energy range which may be made with large orbiting spark-chamber satellite detectors. A discussion of the theoretical interpretations of present data, their connection with baryon symmetric cosmology and galaxy formation theory, and the need for future observations are given.

  13. The origin of the diffuse background gamma radiation

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Puget, J. L.

    1974-01-01

    Recent observations provided evidence for diffuse background gamma radiation extending to energies beyond 100 MeV, and evidence of isotropy and implied cosmological origin. Significant features in the spectrum of this background radiation were observed which provide evidence for its origin in nuclear processes in the early stages of big-bang cosmology, and connect these processes with the galaxy formation theory. A test of the theory is in future observations of the background radiation in the 100 MeK to 100 GeV energy range which are made with large orbiting spark-chamber satellite detectors. The theoretical interpretations of present data, their connection with baryon-symmetric cosmology and galaxy formation theory, and the need for future observations are discussed.

  14. EFFECTS OF GAMMA RADIATION ON ELECTROCHEMICAL PROPERTIES OF IONIC LIQUIDS

    SciTech Connect

    Visser, A; Nicholas Bridges, N; Thad Adams, T; John Mickalonis, J; Mark02 Williamson, M

    2009-04-21

    The electrochemical properties of ionic liquids (ILs) make them attractive for possible replacement of inorganic salts in high temperature molten salt electrochemical processing of nuclear fuel. To be a feasible replacement solvent, ILs need to be stable in moderate and high doses of radiation without adverse chemical and physical effects. Here, we exposed seven different ILs to a 1.2 MGy dose of gamma radiation to investigate their physical and chemical properties as they related to radiological stability. The azolium-based ILs experienced the greatest change in appearance, but these ILs were chemically more stable to gamma radiation than some of the other classes of ILs tested, due to the presence of aromatic electrons in the azolium ring. All the ILs exhibited a decrease in their conductivity and electrochemical window (at least 1.1 V), both of which could affect the utility of ILs in electrochemical processing. The concentration of the irradiation decomposition products was less than 3 mole %, with no impurities detectable using NMR techniques.

  15. Gamma Radiation Reduced Toxicity of Azoxystrobin Tested on Artemia franciscana.

    PubMed

    Dvorak, P; Zdarsky, M; Benova, K; Falis, M; Tomko, M

    2016-06-01

    Fungicide azoxystrobin toxicity was monitored by means of a 96-h biotest with Artemia franciscana nauplius stages after exposure to solutions with concentrations of 0.2, 0.4, 0.6 and 0.8 mg L(-1) irradiated with (60)Co gamma radiation with doses of 1, 2.5, 5 and 10 kGy. The effects of ionization radiation on azoxystrobin toxicity were mainly manifested by a statistically significant reduction of lethality after 72- and 96-h exposure. A maximum reduction of lethality of 72 % was achieved using doses of 1-5 kGy for an azoxystrobin initial concentration of 0.4 mg L(-1) and after 72 h of exposure. At a 96-h exposure, a difference of lethal effects reached up to 70 % for a dose of 10 kGy. The observed effect of gamma ionizing radiation on azoxystrobin toxicity suggest that this approach can be applied as an alternative for a reduction of azoxystrobin residua in food. PMID:27107585

  16. Advanced multi-dimensional imaging of gamma-ray radiation

    NASA Astrophysics Data System (ADS)

    Woodring, Mitchell; Beddingfield, David; Souza, David; Entine, Gerald; Squillante, Michael; Christian, James; Kogan, Alex

    2003-06-01

    The tracking of radiation contamination and distribution has become a high-priority US DOE task. To support DOE needs, Radiation Monitoring Devices Inc. has been actively carrying out research and development on a gamma-radiation imager, RadCam 2000 TM. The imager is based upon a position-sensitive PMT coupled to a scintillator near a MURA coded aperture. The modulated gamma flux detected by the PSPMT is mathematically decoded to produce images that are computer displayed in near real time. Additionally, we have developed a data-manipulation scheme which allows a multi-dimensional data array, comprised of x position, y position, and energy, to be used in the imaging process. In the imager software a gate can be set on a specific isotope energy to reveal where in the field of view the gated data lies or, conversely, a gate can be set on an area in the field of view to examine what isotopes are present in that area. This process is complicated by the FFT decoding process used with the coded aperture; however, we have achieved excellent performance and results are presented here.

  17. Geraniin down regulates gamma radiation-induced apoptosis by suppressing DNA damage.

    PubMed

    Bing, So Jin; Ha, Danbee; Kim, Min Ju; Park, Eunjin; Ahn, Ginnae; Kim, Dae Seung; Ko, Ryeo Kyeong; Park, Jae Woo; Lee, Nam Ho; Jee, Youngheun

    2013-07-01

    Gamma ray irradiation triggers DNA damage and apoptosis of proliferating stem cells and peripheral immune cells, resulting in the destruction of intestinal crypts and lymphoid system. Geraniin is a natural compound extracts from an aquatic plant Nymphaea tetragona and possesses good antioxidant property. In this study, we demonstrate that geraniin rescues radiosensitive splenocytes and jejunal crypt cells from radiation-induced DNA damage and apoptosis. Isolated splenocytes from C57BL/6 mice treated with geraniin were protected against radiation injury of 2 Gy irradiation through the enhancement of the proliferation and attenuation of DNA damage. Also, geraniin inhibited apoptosis in radiosensitive splenocytes by reducing the expression level and immunoreactivity of proapoptotic p53 and Bax and increasing those of anti-apoptotic Bcl-2. In mice exposed to radiation, geraniin treatment protected splenocytes and intestinal crypt cells from radiation-induced cell death. Our results suggest that geraniin presents radioprotective effects by regulating DNA damage on splenocytes, exerting immunostimulatory capacities and inhibiting apoptosis of radiosensitive immune cells and jejunal crypt cells. Therefore, geraniin can be a radioprotective agent against γ-irradiation exposure. PMID:23541438

  18. LIDT test coupled with gamma radiation degraded optics

    NASA Astrophysics Data System (ADS)

    IOAN, M.-R.

    2016-06-01

    A laser can operate in regular but also in nuclear ionizing radiation environments. This paper presents the results of a real time measuring method used to detect the laser induced damage threshold (LIDT) in the optical surfaces/volumes of TEMPAX borosilicate glasses operating in high gamma rays fields. The laser damage quantification technique is applied by using of an automated station intended to measure the damage threshold of optical components, according to the International Standard ISO 21254. Single and multiple pulses laser damage thresholds were determined. For an optical material, life time when it is subjected to multiple pulses of high power laser radiation can be predicted. A few ns pulses shooting laser, operating in regular conditions, inflects damage to a target by its intense electrical component but also in a lower manner by local absorption of its transported thermal energy. When the beam is passing thru optical glass elements affected by ionizing radiation fields, the thermal component is starting to have a more important role, because of the increased thermal absorption in the material's volume caused by the radiation induced color centers. LIDT results on TEMPAX optical glass windows, with the contribution due to the gamma radiation effects (ionization mainly by Compton effect in this case), are presented. This contribution was highlighted and quantified. Energetic, temporal and spatial beam characterizations (according to ISO 11554 standards) and LIDT tests were performed using a high power Nd: YAG laser (1064 nm), before passing the beam through each irradiated glass sample (0 kGy, 1.3 kGy and 21.2 kGy).

  19. Gamma-Gamma Absorption in the Broad Line Region Radiation Fields of Gamma-Ray Blazars

    NASA Astrophysics Data System (ADS)

    Böttcher, Markus; Els, Paul

    2016-04-01

    The expected level of γγ absorption in the Broad Line Region (BLR) radiation field of γ-ray loud Flat Spectrum Radio Quasars (FSRQs) is evaluated as a function of the location of the γ-ray emission region. This is done self-consistently with parameters inferred from the shape of the spectral energy distribution (SED) in a single-zone leptonic EC-BLR model scenario. We take into account all geometrical effects both in the calculation of the γγ opacity and the normalization of the BLR radiation energy density. As specific examples, we study the FSRQs 3C279 and PKS 1510-089, keeping the BLR radiation energy density at the location of the emission region fixed at the values inferred from the SED. We confirm previous findings that the optical depth due to γγ absorption in the BLR radiation field exceeds unity for both 3C279 and PKS 1510-089 for locations of the γ-ray emission region inside the inner boundary of the BLR. It decreases monotonically, with distance from the central engine and drops below unity for locations within the BLR. For locations outside the BLR, the BLR radiation energy density required for the production of GeV γ-rays rapidly increases beyond observational constraints, thus making the EC-BLR mechanism implausible. Therefore, in order to avoid significant γγ absorption by the BLR radiation field, the γ-ray emission region must therefore be located near the outer boundary of the BLR.

  20. Oxidative stress modulates PPAR gamma in vascular endothelial cells.

    PubMed

    Blanquicett, Carmelo; Kang, Bum-Yong; Ritzenthaler, Jeffrey D; Jones, Dean P; Hart, C Michael

    2010-06-15

    The peroxisome proliferator-activated receptor gamma (PPAR gamma) plays an important role in vascular regulation. However, the impact of oxidative stress on PPAR gamma expression and activity has not been clearly defined. Human umbilical vein endothelial cells (HUVECs) were exposed to graded concentrations of H(2)O(2) for 0.5-72h, or bovine aortic endothelial cells (BAECs) were exposed to alterations in extracellular thiol/disulfide redox potential (E(h)) of the cysteine/cystine couple. Within 2h, H(2)O(2) reduced HUVEC PPAR gamma mRNA and activity and reduced the expression of two PPAR gamma-regulated genes without altering PPAR gamma protein levels. After 4h H(2)O(2) exposure, mRNA levels remained reduced, whereas PPAR gamma activity returned to control levels. PPAR gamma mRNA levels remained depressed for up to 72 h after exposure to H(2)O(2), without any change in PPAR gamma activity. Catalase prevented H(2)O(2)-induced reductions in PPAR gamma mRNA and activity. H(2)O(2) (1) reduced luciferase expression in HUVECs transiently transfected with a human PPAR gamma promoter reporter, (2) failed to alter PPAR gamma mRNA half-life, and (3) transiently increased expression and activity of c-Fos and phospho-c-Jun. Treatment with the AP1 inhibitor curcumin prevented H(2)O(2)-mediated reductions in PPAR gamma expression. In addition, medium having an oxidized E(h) reduced BAEC PPAR gamma mRNA and activity. These findings demonstrate that oxidative stress, potentially through activation of inhibitory redox-regulated transcription factors, attenuates PPAR gamma expression and activity in vascular endothelial cells through suppression of PPAR gamma transcription. PMID:20302927

  1. Ceramic Matrix Composites Performances Under High Gamma Radiation Doses

    NASA Astrophysics Data System (ADS)

    Cemmi, A.; Baccaro, S.; Fiore, S.; Gislon, P.; Serra, E.; Fassina, S.; Ferrari, E.; Ghisolfi, E.

    2014-06-01

    Ceramic matrix composites reinforced by continuous ceramic fibers (CMCs) represent a class of advanced materials developed for applications in automotive, aerospace, nuclear fusion reactors and in other specific systems for harsh environments. In the present work, the silicon carbide/silicon carbide (SiCf/SiC) composites, manufactured by Chemical Vapour Infiltration process at FN S.p.A. plant, have been evaluated in term of gamma radiation hardness at three different absorbed doses (up to around 3MGy). Samples behavior has been investigated before and after irradiation by means of mechanical tests (flexural strength) and by surface and structural analyses (X-ray diffraction, SEM, FTIR-ATR, EPR).

  2. Natural Radiation from Soil using Gamma-Ray Spectrometry

    NASA Astrophysics Data System (ADS)

    Silveira, M. A. G.; Moreira, R. H.; de Paula, A. L. C.; Medina, N. H.

    2009-06-01

    We have studied the distribution of natural radioactivity in the soil of Interlagos, in São Paulo city and Billings Reservoir, in São Bernardo do Campo, São Paulo, Brazil. The main contribution of the effective radiation dose is due to the elements of the 238Th decay series, with smaller contributions from 40K and the elements of the series of 238U. The results indicate the dose in all of the studied areas is around the average international dose due to external exposure to gamma rays (0.48 mSv/yr) proceeding from natural terrestrial elements.

  3. Mechanisms for Production of the Diffuse Gamma-ray Continuum Radiation

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1973-01-01

    The production of cosmic gamma radiation from Compton interactions with low energy photons, bremsstrahlung interactions, cosmic ray induced neutral pion production, and matter-antimatter annihilation is discussed.

  4. Human hematopoietic cell express two forms of the cytokine receptor common gamma-chain (gamma c).

    PubMed

    Shi, Y F; Hill, M; Novak, A; Chen, Z Q; Wang, R X; Liew, C C; Mills, G B

    1997-12-01

    Recent studies have revealed that the gamma-chain of the IL-2 receptor is shared by the receptors for IL-4, IL-7, IL-9, IL-13, and IL-15, and it is therefore also referred to as the common gamma-chain (gamma c). Mutations of gamma c result in X-linked severe combined immunodeficiency syndrome in humans, indicating that gamma c is essential for normal development and function of the immune system. We demonstrate that human hematopoietic cells express two gamma c transcripts differing in their carboxyl terminal coding region. One transcript is the previously reported sequence (gamma c-long), whereas the newly identified sequence exhibits a deletion of 72 nucleotides close to the 3'-end of the open reading frame (gamma c-short). This alteration predicts a loss of 24 amino acids including a conserved tyrosine residue which is shared by several members of the cytokine receptor family. The presence of these two distinct forms of gamma c transcripts was demonstrated by sequencing of reversely transcribed and polymerase chain reaction (RT-PCR) amplified mRNA, restriction digestion of the RT-PCR products, RNAse protection, and Northern blotting from human cell lines and human peripheral blood lymphocytes. Furthermore, the two variants were present in peripheral blood lymphocytes from both female and male donors, which rules out allelic variants since gamma c is a single copy gene located on the X chromosome. A truncation mutant at a site near the observed changes in gamma c-short has been reported by others to alter biochemical events activated by cytokines. This combined with the loss of a potential SH2 "docking" site in gamma c-short suggests that gamma c-long and gamma c-short may link to different signaling pathways and may play an important role in determining the cellular response to IL-2, IL-4, IL-7, IL-9, IL-13, IL-15. PMID:9444398

  5. Gamma radiation effects on commercial Mexican bread making wheat flour

    NASA Astrophysics Data System (ADS)

    Agúndez-Arvizu, Z.; Fernández-Ramírez, M. V.; Arce-Corrales, M. E.; Cruz-Zaragoza, E.; Meléndrez, R.; Chernov, V.; Barboza-Flores, M.

    2006-04-01

    Gamma irradiation is considered to be an alternative method for food preservation to prevent food spoilage, insect infestation and capable of reducing the microbial load. In the present investigation, commercial Mexican bread making wheat flour was irradiated at 1.0 kGy using a 60C Gammabeam 651 PT irradiator facility. No changes were detected in moisture, protein and ashes in gamma irradiated samples as compared to those of non-irradiated samples. Slight radiation effects were observed in the alveogram values and farinograph properties; the falling number decreased 11%, the absorption as well as the mixing tolerance were practically unchanged by irradiation. An increase of 15% in the stability value and a 29% in the dough development time were observed. Also the deformation energy decreased 7% with no change at all in the tenacity/extensibility factor. Total aerobic, yeast and mold counts were reduced 96%, 25% and 75%; respectively by the irradiation process. The obtained results confirm that gamma irradiation is effective in reducing the microbial load in bread making wheat flour without a significant change in the physicochemical and baking properties.

  6. An experimental search for gamma radiation associated with thunderstorm activity

    SciTech Connect

    Fryberger, D.

    1992-11-01

    This experiment is a repeat of an earlier experiment, but with more sensitive apparatus and in a location with a higher incidence of thunderstorm activity. The earlier experiment was undertaken by Ashby and Whitehead to investigate the theory that ball lightning might be associated with the annihilation of small amounts of antimatter, and it yielded some very interesting but inconclusive results. In the course of about 12 months of data taking, four high rate bursts of gamma radiation were detected. These events lasted a few seconds and had many thousands of counts (16500, 5000, 3700, and {gt} 7700. Unfortunately, the association of these gamma ray bursts with thunderstorms or ball lightning was not clearly established, although one of the bursts did occur during a local thunderstorm in rough coincidence with a lightning bolt striking a flagpole about 100 yards from the gamma ray detection crystals. A pulse height spectrum taken for this burst (no spectrum was taken for the other three) exhibited a significant peak, well above background, the energy of which appeared to be compatible with the 511 keV positron annihilation line. While the peak could not be unambiguously attributed to positron annihilation, this certainly appeared to be the most likely source.

  7. An experimental search for gamma radiation associated with thunderstorm activity

    SciTech Connect

    Fryberger, D.

    1992-11-01

    This experiment is a repeat of an earlier experiment, but with more sensitive apparatus and in a location with a higher incidence of thunderstorm activity. The earlier experiment was undertaken by Ashby and Whitehead to investigate the theory that ball lightning might be associated with the annihilation of small amounts of antimatter, and it yielded some very interesting but inconclusive results. In the course of about 12 months of data taking, four high rate bursts of gamma radiation were detected. These events lasted a few seconds and had many thousands of counts (16500, 5000, 3700, and [gt] 7700. Unfortunately, the association of these gamma ray bursts with thunderstorms or ball lightning was not clearly established, although one of the bursts did occur during a local thunderstorm in rough coincidence with a lightning bolt striking a flagpole about 100 yards from the gamma ray detection crystals. A pulse height spectrum taken for this burst (no spectrum was taken for the other three) exhibited a significant peak, well above background, the energy of which appeared to be compatible with the 511 keV positron annihilation line. While the peak could not be unambiguously attributed to positron annihilation, this certainly appeared to be the most likely source.

  8. Inhaled /sup 239/PuO/sub 2/ and/or total-body gamma radiation: Early mortality and morbidity in rats and dogs

    SciTech Connect

    Filipy, R.E.; Decker, J.R.; Lai, Y.L.; Lauhala, K.E.; Buschbom, R.L.; Hiastala, M.P.; McGee, D.R.; Park, J.F.; Kuffel, E.G.; Ragan, H.A.; Cannon, W.C.; Yaniv, S.S.; Scott, B.R.

    1988-08-01

    Rats and beagle dogs were given doses of /sup 60/Co gamma radiation and/or body burdens of /sup 239/PuO/sub 2/ within lethal ranges in an experiment to determine and compare morbidity and mortality responses of both species within 1 year after exposure. Radiation-induced morbidity was assessed by measuring changes in body weights, hematologic parameters, and pulmonary-function parameters. Gamma radiation caused transient morbidity, reflected by immediately depressed blood cell concentrations and by long-term loss of body weight and diminished pulmonary function in animals of both species that survived the acute gamma radiation syndrome. Inhaled plutonium caused a loss of body weight and diminished pulmonary function in both species, but its only effect on blood cell concentrations was lymphocytopenia in dogs. Combined gamma irradiation and plutonium lung burdens were synergistic, in that animals receiving both radiation insults had higher morbidity and mortality rates than would be predicted based on the effect of either kind of radiation alone. Plutonium lung burdens enhanced the effect of gamma radiation in rats within the first 30 days of exposure, and gamma radiation enhanced the long-term effect of plutonium lung burdens in both species. Rats were less sensitive to both kinds of radiation, whether administered alone or in combination. 71 refs., 105 figs., 48 tabs.

  9. An investigation of gamma background radiation in Hamadan province, Iran.

    PubMed

    Rostampour, Nima; Almasi, Tinoosh; Rostampour, Masoumeh; Mohammadi, Mohammad; Ghazikhanlou Sani, Karim; Khosravi, Hamid R; Pooya, S Mehdi Hosseini; Golzar, Bahman; Jabari Vesal, Naghi

    2012-12-01

    The general population, everywhere in the world is exposed to a small dose of ionising radiation from natural sources. Stochastic effects such as cancer and genetic disorders are caused when living creatures are exposed to low doses. In Iran, it is measured in some cities, especially in high-background areas such as Ramsar, but so far there is no measurement in the Hamadan province. Hamadan is located in the west of Iran. Measurements were performed using a RDS-110 survey meter, CaSO(4):Dy thermoluminecense dosimetries (TLDs) and a Harshaw 4000 TLD reader. To estimate the dose rate  outdoors, four stations along the main directions (north, south, west and east) and one in the town centre were selected. Mean annual X and gamma equivalent dose in Hamadan province are 1.12±0.22  and 1.66±0.07 mSv, which related to RDS-110 survey meter and TLDs measurements, respectively. The TLDs and RDS-110 results are representative of the external photon radiation doses for the selected monitoring locations and for those locations for the hours during which the measurements were taken, respectively. Maximum and minimum of external photon radiation doses are related to Hamadan and Kaboudar-Ahang towns, respectively. According to the results of the study, it seems that the annual X and gamma equivalent dose in Hamadan province exceeded the global mean external exposure amounts by the UNSCEAR, and further studies are needed to measure internal exposures to determine the total environmental radiation level in  Hamadan province. PMID:22570508

  10. Radiative Penguin Decays of B Mesons: Measurements of B to K* gamma, B to K2* gamma, and Search for B0 to phi gamma

    SciTech Connect

    Bauer, J.

    2005-01-03

    Electromagnetic radiative penguin decays of the B meson were studied with the BaBar detector at SLAC's PEP-II asymmetric-energy B Factory. Branching fractions and isospin asymmetry of the decay B {yields} K*{gamma}, branching fractions of B {yields} K*{sub 2}(1430){gamma}, and a search for B{sup 0} {yields} {phi}{gamma} are presented. The decay rates may be enhanced by contributions from non-standard model processes.

  11. Effect of Gamma radiation on microbial population of natural casings

    NASA Astrophysics Data System (ADS)

    Trigo, M. J.; Fraqueza, M. J.

    1998-06-01

    The high microbial load of fresh and dry natural casings increases the risk of meat product contamination with pathogenic microorganisms, agents of foodborn diseases. The aim of this work is to evaluate the killing effect of gamma radiation of the resident microbial population of pork and beef casings, to improve their hygiene and safety. Portions of fresh pork (small intestines and colon) and dry beef casings were irradiated in a Cobalt 60 source with with absorbed doses of 1,2,5 and 10 kGy. The D 10 values of total aerobic microorganisms in the pork casings were 1.65 kGy for colon and 1.54 kGy for small intestine. The D 10 value found in beef dry casings (small intestine) was 10.17 kGy. Radurization with 5 kGy was able to reduce, at least, 6 logs the coliform bacteria in pork casings. The killing effect over faecal Streptococci was 4 logs for pork fresh casings and 2 logs for beef dry casings. Gamma radiation with 5 kGy proved to be a convenient method to reduce substantially the microbial population of pork fresh casings. Otherwise, the microbial population of beef dry casings still resisted to 10 kGy.

  12. Removal of trihalomethane from chlorinated seawater using gamma radiation.

    PubMed

    Rajamohan, R; Natesan, Usha; Venugopalan, V P; Rajesh, Puspalata; Rangarajan, S

    2015-12-01

    Chlorine addition as a biocide in seawater results in the formation of chlorination by-products such as trihalomethanes (THMs). Removal of THMs is of importance as they are potential mutagenic and carcinogenic agents. In this context, a study was conducted that used ionizing radiation to remove THMs from chlorinated (1, 3, and 5mg/L) seawater by applying various dosages (0.4-5.0kGy) of gamma radiation. Bromoform (BF) showed a faster rate of degradation as compared to other halocarbons such as bromodichloromethane (BDCM) and dibromochloromethane (DBCM). In chlorine-dosed seawater, total irradiation dose of 0.4 to 5kGy caused percentage reduction in the range of 6.9 to 76.7%, 2.3 to 99.6%, and 45.7 to 98.3% for BDCM, DBCM, and BF, respectively. During the irradiation process, pH of the chlorinated seawater decreased with increase in the absorbed dose; however, no change in total organic carbon (TOC) was observed. The results show that gamma dose of 2.5kGy was adequate for maximum degradation of THM; but for complete mineralization, higher dose would be required. PMID:26199004

  13. Delayed gamma radiation from lightning induced nuclear reactions

    NASA Astrophysics Data System (ADS)

    Greenfield, M. B.; Sakuma, K.; Ikeda, Y.; Kubo, K.

    2004-03-01

    An increase in atmospheric gamma radiation observed with NaI and Ge detectors positioned about 15 m above ground was observed following natural lightning near Tokyo, Japan [1]. Background subtracted gamma ray rates GRR following numerous lightning strokes observed since 2001 persisted for a few hours and subsequently decayed with a half-life of about 50 minutes. Using a 3x3 Ge detector, with 2 KeV resolution, positioned about 2 m from one of the NaI detectors increases in GRR were observed minutes after the onset of lightning with a delayed 50 min exponential decay. Although most of the increase in activity occured at less than a few 100 KeV, on July 11, 2003 a 1267 +/-2 KeV line was observed. Although the statistics of this event were poor, the appearance of this line with an exponential decay of 50 min half-life suggests the possibility that it may be due to 39Cl (1267 MeV; half-life = 55.5 min) via the 40Ar(gamma,p)39Cl, 40Ar(p,2p)39Cl and/or 40Ar(n,d)39Cl reactions. Observations of > 10 MeV gamma rays observed in NaI detectors within 10s of meters from and coincident with rocket-triggered lightning at the International Center for Lightning Research and Testing suggest that charged particles accelerated in intense electric fields associated with lightning give rise to photons with sufficient energy to initiate nuclear reactions [2]. Further work to explain the cause of this anomalous activity is underway using natural and triggered lightning. 1. M. B. Greenfield et al., Journal of Applied Physics 93 no. 3 (2003) pp 1839-184. 2. J. R. Dwyer et al., Science 299, (2003), pp 694-697 and recent communications

  14. Mechanisms of radiation-induced neoplastic cell transformation

    SciTech Connect

    Yang, T.C.H.; Tobias, C.A.

    1984-04-01

    Studies with cultured mammalian cells demonstrated clearly that radiation can transform cells directly and can enhance the cell transformation by oncogenic DNA viruses. In general, high-LET heavy-ion radiation can be more effective than X and gamma rays in inducing neoplastic cell transformation. Various experimental results indicate that radiation-induced DNA damage, most likely double-strand breaks, is important for both the initiation of cell transformation and for the enhancement of viral transformation. Some of the transformation and enhancement lesions can be repaired properly in the cell, and the amount of irrepairable lesions produced by a given dose depends on the quality of radiation. An inhibition of repair processes with chemical agents can increase the transformation frequency of cells exposed to radiation and/or oncogenic viruses, suggesting that repair mechanisms may play an important role in the radiation transformation. The progression of radiation-transformed cells appears to be a long and complicated process that can be modulated by some nonmutagenic chemical agents, e.g., DMSO. Normal cells can inhibit the expression of transforming properties of tumorigenic cells through an as yet unknown mechanism. The progression and expression of transformation may involve some epigenetic changes in the irradiated cells. 38 references, 15 figures, 1 table.

  15. Radiomodifying and anticlastogenic effect of Zingerone on Swiss albino mice exposed to whole body gamma radiation.

    PubMed

    Rao, B Nageshwar; Rao, B S Satish; Aithal, B Kiran; Kumar, M R Sunil

    2009-01-01

    The radioprotective effect and antigenotoxic potential of phenolic alkanone, Zingerone (ZO) were investigated in Swiss albino mice exposed to gamma radiation. To study the optimum dose for radiation protection, mice were administered with ZO (10-100mg/kgb.wt.), once daily for five consecutive days. One hour after the last administration of ZO on the fifth day, animals were whole body exposed to 10 Gy gamma radiations. The radioprotective potential was assessed using animal survival at an optimal ZO dose of 20mg/kgb.wt., administered prior to 7-11 Gy. Further, the radioprotective potential of ZO was also analyzed by haemopoietic stem cell survival (CFU) assay, mouse bone marrow micronucleus test and histological observations of intestinal and bone marrow damage. Effect of ZO pretreatment on radiation-induced changes in glutathione (GSH), glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT) and lipid peroxidation (LPx) levels was also analyzed. ZO treatment resulted increase in the LD(50/30) by 1.8 Gy (dose reduction factor = 1.2). The number of spleen colonies after whole body irradiation of mice (4.5 or 7.5 Gy) was increased when ZO was administered 1h prior to irradiation. The histological observations indicated a decline in the villus height and crypt number with an increase in goblet and dead cell population in the irradiated group, which was normalized by pretreatment with ZO. A significant (p < 0.001) reduction in micronucleated polychromatic, normochromatic erythrocytes, increased PCE/NCE ratio, increase in the GSH, GST, SOD, CAT and decreased LPx levels were observed in ZO pretreated group when compared to the irradiated animals. Our findings demonstrate the potential of ZO in mitigating radiation-induced mortality and cytogenetic damage, which may be attributed to inhibition radiation-induced decline in the endogenous antioxidant levels and scavenging of radiation-induced free radicals. PMID:19463966

  16. Aberrant megakaryocytopoiesis preceding radiation-induced leukemia in the dog. [Gamma radiation

    SciTech Connect

    Tolle, D.V.; Seed, T.M.; Cullen, S.M.; Poole, C.M.; Fritz, T.E.

    1982-01-01

    Six of nine decedent beagles exposed continuously to 2.5 R/22 hour day of whole-body /sup 60/Co ..gamma..-radiation died with myeloproliferative diseases: three cases of myelogenous leukemia and one each of monocytic leukemia, erythroleukemia, and erythremic myelosis. The three dogs that died with myelogenous leukemia had micromegakaryocytes and megakaryoblasts in the peripheral blood during the preleukemic phase when myeloblasts were not observed in the peripheral blood or in increased numbers in the bone marrow. In this study we have examined the megakaryocytes during the preleukemic period by a combination of light, transmission, and scanning electron microscopy. Morphologic abnormalities seen by light microscopy included mononucleated and binucleated forms, many with cytoplasmic blebs. The small mononuclear forms in the bone marrow tended to form clusters. Ultrastructural features included a paucity of both specific ..cap alpha.. granules and dense granules. The micromegakaryocytes showed dysgenesis of the demarcation membrane system. This membrane system appeared disorganized with a few dilated round, oval, or rarely, elongated vesicles and showed no evidence of platelet formation. The cells also had a paucity of endoplasmic reticulum, few mitochrondria, and sparse glycogen accumulations. The scarcity of cytoplasmic organelles gave a pale immature appearance to the cytoplasm. By scanning electron microscopy, the sponge-like surface of large mature megakaryocytes from unirradiated marrow contrasted with the characteristically smooth, topographically featureless surfaces of the micromegakaryocytes from preleukemic dogs.

  17. Aberrant megakaryocytopoiesis preceding radiation-induced leukemia in the dog. [Gamma radiation

    SciTech Connect

    Tolle, D.V.; Seed, T.M.; Cullen, S.M.; Poole, C.M.; Fritz, T.E.

    1982-01-01

    Six of nine decedent beagles exposed continuously to 2.5 R*/22 hour day of whole-body 60Co gamma-radiation died with myeloproliferative diseases: three cases of myelogenous leukemia and one each of monocytic leukemia, erythroleukemia, and erythremic myelosis. The three dogs that died with myelogenous leukemia had micromegakaryocytes and megakaryoblasts in the peripheral blood during the preleukemic phase when myeloblasts were not observed in the peripheral blood or in increased numbers in the bone marrow. In this study we have examined the megakaryocytes during the preleukemic period by a combination of light, transmission, and scanning electron microscopy. Morphologic abnormalities seen by light microscopy included mononucleated and binucleated forms, many with cytoplasmic blebs. The small mononuclear forms in the bone marrow tended to form clusters. Ultrastructural features included a paucity of both specific alpha granules and dense granules. The micromegakaryocytes showed dysgenesis of the demarcation membrane system. This membrane system appeared disorganized with a few dilated round, oval, or rarely, elongated vesicles and showed no evidence of platelet formation. The cells also had a paucity of endoplasmic reticulum, few mitochrondria, and sparse glycogen accumulations. The scarcity of cytoplasmic organelles gave a pale immature appearance to the cytoplasm. By scanning electron microscopy, the sponge-like surface of large mature megakaryocytes from unirradiated marrow contrasted with the characteristically smooth, topographically featureless surfaces of the micromegakaryocytes from preleukemic dogs.

  18. [Protection of cadaver tissues exposed to high gamma radiation].

    PubMed

    Matus-Jiménez, J; Flores-Fletes, J R; Carrillo, A

    2013-01-01

    Bone tissue is the most widely used tissue for the treatment of various conditions. As a result of this, allografts are used at an increasing frequency and processes for their harvest, preservation and sterilization have improved. The sterilization method that grants the greatest sterilization is high-dose gamma radiation, which destroys prions and any microorganism thus assuring that patients will not experience any infection. But given that radiation use has proven to deteriorate bone and tendon tissue, efforts have been made to protect the latter. One way to do this is a commercially available substance called Clearant. Studies conducted elsewhere have found that it does protect bone and tendon tissue. This study was therefore conducted with allograft samples exposed to high-dose radiation. Its purpose was to assess, with photon microscopy using various dyes and electron microscopy, the presence of color changes as well as the destruction of the anatomical structure. The same tissue was followed-up throughout the process until it was placed in the patient. The review found no structural changes in bone and tendon tissues exposed to high radiation doses (60 kilograys) when the Clearant process was used, and concluded that the former may be used safely in orthopedic or traumatologic diseases. PMID:24707605

  19. Induction of p53 protein by gamma radiation in lymphocyte lines from breast cancer and ataxia telangiectasia patients.

    PubMed Central

    Birrell, G. W.; Ramsay, J. R.

    1995-01-01

    Exposure of human cells to gamma-radiation causes levels of the tumour-suppressor nuclear protein p53 to increase in temporal association with the decrease in replicative DNA synthesis. Cells from patients with the radiosensitive and cancer-prone disease ataxia telangiectasia (AT) exhibit radioresistant DNA synthesis and show a reduced or delayed gamma-radiation-induced increase in p53 protein levels. We have used Western immunoblotting with semiquantitative densitometry to examine the gamma-radiation-induced levels of p53 protein in 57 lymphoblastoid cell lines (LCLs) derived from patients with AT, carriers of the AT gene, breast cancer patients and normal donors. We confirm the previously reported reduced induction in AT homozygote LCLs (n = 8) compared with normal donor LCLs (n = 17, P = 0.01). We report that AT heterozygote LCLs (n = 5) also have a significantly reduced p53 induction when compared with LCLs from normal donors (n = 17, P = 0.02). The response of breast cancer patient cells was not significantly different from normal donor cells but 18% (5/27) had a p53 response in the AT heterozygote range (95% confidence interval) compared with only 6% (1/17) of the normal donor cells. We found no significant correlation between p53 induction and cellular radiosensitivity in LCLs from breast cancer patients. These methods may be useful in identifying individuals at greater risk of the DNA-damaging effects of ionising radiation. Images Figure 2 PMID:7577453

  20. DNA damage induced by gamma-radiation in combination with ethylene oxide or propylene oxide in human fibroblasts.

    PubMed

    Chovanec, M; Cedervall, B; Kolman, A

    2001-09-28

    To estimate the effects of interaction of gamma-rays and an epoxide, cell survival and induction of DNA double-strand breaks (DSBs) following combined exposure to ionizing radiation and ethylene oxide (EtO) or propylene oxide (PO) were studied in human fibroblasts. Two treatment protocols were applied: (a) the cells were pre-exposed to different doses of gamma-rays and then treated with epoxide, and (b) the cells were pretreated with epoxide and then exposed to different doses of gamma-rays. Here we show that order of the treatment did not play a role in cell survival and that the effect of combined exposure on cell killing was additive for both epoxides. As to DNA DSBs induction, however, a difference dependent upon the order of the treatment was observed. While EtO or PO treatment followed by gamma-rays exposure led to an increased number of DSBs at higher gamma-ray doses (2-3 Gy), no significant increase of DSBs was detected after the opposite order of the treatment (gamma-ray exposure followed by EtO or PO treatment). PMID:11566293

  1. Oxidative stress and gamma radiation-induced cancellous bone loss with musculoskeletal disuse

    PubMed Central

    Kondo, Hisataka; Yumoto, Kenji; Alwood, Joshua S.; Mojarrab, Rose; Wang, Angela; Almeida, Eduardo A. C.; Searby, Nancy D.; Limoli, Charles L.

    2010-01-01

    Exposure of astronauts in space to radiation during weightlessness may contribute to subsequent bone loss. Gamma irradiation of postpubertal mice rapidly increases the number of bone-resorbing osteoclasts and causes bone loss in cancellous tissue; similar changes occur in skeletal diseases associated with oxidative stress. Therefore, we hypothesized that increased oxidative stress mediates radiation-induced bone loss and that musculoskeletal disuse changes the sensitivity of cancellous tissue to radiation exposure. Musculoskeletal disuse by hindlimb unloading (1 or 2 wk) or total body gamma irradiation (1 or 2 Gy of 137Cs) of 4-mo-old, male C57BL/6 mice each decreased cancellous bone volume fraction in the proximal tibiae and lumbar vertebrae. The extent of radiation-induced acute cancellous bone loss in tibiae and lumbar vertebrae was similar in normally loaded and hindlimb-unloaded mice. Similarly, osteoclast surface in the tibiae increased 46% as a result of irradiation, 47% as a result of hindlimb unloading, and 64% as a result of irradiation + hindlimb unloading compared with normally loaded mice. Irradiation, but not hindlimb unloading, reduced viability and increased apoptosis of marrow cells and caused oxidative damage to lipids within mineralized tissue. Irradiation also stimulated generation of reactive oxygen species in marrow cells. Furthermore, injection of α-lipoic acid, an antioxidant, mitigated the acute bone loss caused by irradiation. Together, these results showed that disuse and gamma irradiation, alone or in combination, caused a similar degree of acute cancellous bone loss and shared a common cellular mechanism of increased bone resorption. Furthermore, irradiation, but not disuse, may increase the number of osteoclasts and the extent of acute bone loss via increased reactive oxygen species production and ensuing oxidative damage, implying different molecular mechanisms. The finding that α-lipoic acid protected cancellous tissue from the detrimental effects of irradiation has potential relevance to astronauts and radiotherapy patients. PMID:19875718

  2. Gamma radiation consequences on desert locust Schistocerca gregaria (Forsk.) digestive system.

    PubMed

    Dushimirimana, S; Muratori, F; Damiens, D; Hance, T

    2010-01-01

    Schistocera gregaria (Forsk.) (Orthoptera, Acrididae) remains a major insect pest in Africa, more particularly in the Sahelian zone. Present control methods are only partially efficient. In a previous study, we tested the potentiality of a sterile insect technique (SIT). Males of S. gregaria appeared to be much radiosensitive as already a dose of 3 Gy limited their survival. Gamma-radiations are known to damages the epithelial tissue of midgut, which affects the alimentation in insects. In this work, we show how digestive system of S. gregaria males is affected when submitted to a dose of 4 gamma rays. Nutrition is affected as males stop feeding soon after irradiation and progressively lose weight. Histological analyses on the midgut showed important epithelium damages. The regenerative cells by which the epithelial cells are replaced were damaged on the first days following irradiation. Consequently, regenerative cells are unable to divide and replace the normal loss of midgut cell. After nine days, the entire midgut epithelium was destroyed and only longitudinal muscles layer remained intact. This indicates that low radiation doses should be used if SIT will be applied. PMID:21539264

  3. Combination of {gamma}-radiation antagonizes the cytotoxic effects of vincristine and vinblastine on both mitotic arrest and apoptosis

    SciTech Connect

    Sui, Meihua; Fan Weimin . E-mail: fanw@musc.edu

    2005-03-15

    Purpose: Combination therapy with different modalities is a common practice in the treatment of cancer. The promising clinical profile of vincristine and vinblastine has promoted considerable interest in combining these vinca alkaloids with radiation therapy to treat a variety of solid tumors. However, the therapeutic efficacy and the interaction between the vinca alkaloids with radiation is not entirely clear. In this study, we assessed the potential interactions in the combination of vincristine or vinblastine with {gamma}-radiation against human tumor cells in vitro. Methods and materials: Vincristine or vinblastine and {gamma}-radiation were administrated at three different sequences designed as preradiated, coradiated, and postradiated combinations in human breast cancer cells and human epidermoid carcinoma cells. The cytotoxic interactions and mutual influences between these two modalities were analyzed by a series of assays including cytotoxic, morphologic, and biochemical examinations. Results: Our results showed that the combination of these two modalities did not produce any synergistic or additive effects. Instead, the clonogenic assays showed the survival rates of these combinations were increased up to 2.17-fold and 2.7-fold, respectively, of those treated with vincristine or vinblastine alone (p < 0.01). DNA fragmentation, T{alpha}T-mediated dUTP nick end labeling (TUNEL) assay, and flow cytometric assays also showed that the combination of {gamma}-radiation significantly interfered with the ability of these vinca alkaloids to induce apoptosis. Further analyses indicated that addition of {gamma}-radiation resulted in cell cycle arrest at the G{sub 2} phase, which subsequently prevented the mitotic arrest induced by vincristine or vinblastine. In addition, biochemical examinations revealed that {gamma}-radiation regulated p34{sup cdc2}/cyclin B1 and survivin, and inhibited I{kappa}B{alpha} degradation and bcl-2 phosphorylation. Conclusions: These results suggest that {gamma}-radiation might specifically block the cell cycle at the G{sub 2} phase, which in turn interferes with the cytotoxic effects of vincristine or vinblastine on mitotic arrest and apoptosis. Thereby, it eventually results in an antagonistic interaction between these two modalities. This finding may be implicated in the clinical application of combination therapy of vinca alkaloids and radiation.

  4. dl-. cap alpha. -tocopheryl succinate enhances the effect of. gamma. -irradiation on neuroblastoma cells in culture

    SciTech Connect

    Sarri, A.; Prasad, K.N.

    1984-01-01

    The effect of dl-..cap alpha..-tocopheryl (vitamin E) succinate in modifying the radiation response of mouse neuroblastoma (NBP/sub 2/) and mouse fibroblast (L-cells) cells in culture was studied on the criterion of growth inhibition (due to cell death and inhibition of cell division). Results show that vitamin E succinate markedly enhanced the effect of /sub 60/CO-..gamma..-irradiation on NB cells, but it did not significantly modify the effect of irradiation on mouse fibroblasts. Sodium succinate plus ethanol (0.25% final concentration) did not modify the radiation response of NB cells or fibroblasts. Butylated hydroxyanisole, a lipid soluble antioxidant, also enhanced the effect of irradiation on NB cells, indicating that the effect of vitamin E in modifying the radiation response may be mediated, in part, by antioxidation mechanisms.

  5. Networked gamma radiation detection system for tactical deployment

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ronald; Smith, Ethan; Guss, Paul; Mitchell, Stephen

    2015-08-01

    A networked gamma radiation detection system with directional sensitivity and energy spectral data acquisition capability is being developed by the National Security Technologies, LLC, Remote Sensing Laboratory to support the close and intense tactical engagement of law enforcement who carry out counterterrorism missions. In the proposed design, three clusters of 2″ × 4″ × 16″ sodium iodide crystals (4 each) with digiBASE-E (for list mode data collection) would be placed on the passenger side of a minivan. To enhance localization and facilitate rapid identification of isotopes, advanced smart real-time localization and radioisotope identification algorithms like WAVRAD (wavelet-assisted variance reduction for anomaly detection) and NSCRAD (nuisance-rejection spectral comparison ratio anomaly detection) will be incorporated. We will test a collection of algorithms and analysis that centers on the problem of radiation detection with a distributed sensor network. We will study the basic characteristics of a radiation sensor network and focus on the trade-offs between false positive alarm rates, true positive alarm rates, and time to detect multiple radiation sources in a large area. Empirical and simulation analyses of critical system parameters, such as number of sensors, sensor placement, and sensor response functions, will be examined. This networked system will provide an integrated radiation detection architecture and framework with (i) a large nationally recognized search database equivalent that would help generate a common operational picture in a major radiological crisis; (ii) a robust reach back connectivity for search data to be evaluated by home teams; and, finally, (iii) a possibility of integrating search data from multi-agency responders.

  6. The impact of gamma radiation on sediment microbial processes.

    PubMed

    Brown, Ashley R; Boothman, Christopher; Pimblott, Simon M; Lloyd, Jonathan R

    2015-06-15

    Microbial communities have the potential to control the biogeochemical fate of some radionuclides in contaminated land scenarios or in the vicinity of a geological repository for radioactive waste. However, there have been few studies of ionizing radiation effects on microbial communities in sediment systems. Here, acetate and lactate amended sediment microcosms irradiated with gamma radiation at 0.5 or 30 Gy h(-1) for 8 weeks all displayed NO3 (-) and Fe(III) reduction, although the rate of Fe(III) reduction was decreased in 30-Gy h(-1) treatments. These systems were dominated by fermentation processes. Pyrosequencing indicated that the 30-Gy h(-1) treatment resulted in a community dominated by two Clostridial species. In systems containing no added electron donor, irradiation at either dose rate did not restrict NO3 (-), Fe(III), or SO4 (2-) reduction. Rather, Fe(III) reduction was stimulated in the 0.5-Gy h(-1)-treated systems. In irradiated systems, there was a relative increase in the proportion of bacteria capable of Fe(III) reduction, with Geothrix fermentans and Geobacter sp. identified in the 0.5-Gy h(-1) and 30-Gy h(-1) treatments, respectively. These results indicate that biogeochemical processes will likely not be restricted by dose rates in such environments, and electron accepting processes may even be stimulated by radiation. PMID:25841009

  7. Gamma radiation influence on technological characteristics of wheat flour

    NASA Astrophysics Data System (ADS)

    Teixeira, Christian A. H. M.; Inamura, Patricia Y.; Uehara, Vanessa B.; Mastro, Nelida L. d.

    2012-08-01

    This study aimed at determining the influence of gamma radiation on technological characteristics of wheat (Triticum sativum) flour and physical properties of pan breads made with this flour. The bread formulation included wheat flour, water, milk, salt, sugar, yeast and butter. The α-amylase activity of wheat flour irradiated with 1, 3 and 9 kGy in a Gammacell 220 (AECL), one day, five days and one month after irradiation was evaluated. Deformation force, height and weight of breads prepared with the irradiated flour were also determined. The enzymatic activity increased—reduction of falling number time—as radiation dose increased, their values being 397 s (0 kGy), 388 s (1 kGy), 343 s (3 kGy) and 293 s (9 kGy) respectively, remaining almost constant over the period of one month. Pan breads prepared with irradiated wheat flour showed increased weight. Texture analysis showed that bread made of irradiated flour presented an increase in maximum deformation force. The results indicate that wheat flour ionizing radiation processing may confer increased enzymatic activity on bread making and depending on the irradiation dose, an increase in weight, height and deformation force parameters of pan breads made of it.

  8. The Impact of Gamma Radiation on Sediment Microbial Processes

    PubMed Central

    Brown, Ashley R.; Boothman, Christopher; Pimblott, Simon M.

    2015-01-01

    Microbial communities have the potential to control the biogeochemical fate of some radionuclides in contaminated land scenarios or in the vicinity of a geological repository for radioactive waste. However, there have been few studies of ionizing radiation effects on microbial communities in sediment systems. Here, acetate and lactate amended sediment microcosms irradiated with gamma radiation at 0.5 or 30 Gy h−1 for 8 weeks all displayed NO3− and Fe(III) reduction, although the rate of Fe(III) reduction was decreased in 30-Gy h−1 treatments. These systems were dominated by fermentation processes. Pyrosequencing indicated that the 30-Gy h−1 treatment resulted in a community dominated by two Clostridial species. In systems containing no added electron donor, irradiation at either dose rate did not restrict NO3−, Fe(III), or SO42− reduction. Rather, Fe(III) reduction was stimulated in the 0.5-Gy h−1-treated systems. In irradiated systems, there was a relative increase in the proportion of bacteria capable of Fe(III) reduction, with Geothrix fermentans and Geobacter sp. identified in the 0.5-Gy h−1 and 30-Gy h−1 treatments, respectively. These results indicate that biogeochemical processes will likely not be restricted by dose rates in such environments, and electron accepting processes may even be stimulated by radiation. PMID:25841009

  9. Neutron and gamma radiation shielding material, structure, and process of making structure

    DOEpatents

    Hondorp, Hugh L.

    1984-01-01

    The present invention is directed to a novel neutron and gamma radiation elding material consisting of 95 to 97 percent by weight SiO.sub.2 and 5 to 3 percent by weight sodium silicate. In addition, the method of using this composition to provide a continuous neutron and gamma radiation shielding structure is disclosed.

  10. [Interferon gamma as a regulator of immune cell function].

    PubMed

    Szuster-Ciesielska, A; Kandefer-Szerszeń, M

    1999-01-01

    The article reviews the literature with regard to identification of lymphocyte subsets that respond to specific inducers and produce IFN-gamma, the structure of IFN-gamma gene, the IFN signal transduction pathway that initiates biochemical changes at cellular level and influences the function of immunocompetent cells: mononuclear phagocytes, T and B lymphocytes. The interaction of IFN-gamma with other cytokines in regulation of immune response is also discussed. PMID:10352545

  11. Population doses from environmental gamma radiation in Iraq

    SciTech Connect

    Marouf, B.A.; Mohamad, A.S.; Taha, J.S.; al-Haddad, I.K. )

    1992-05-01

    The exposure rates due to external gamma radiation were measured in 11 Iraqi governerates. Measurements were performed with an Environmental Monitoring System (RSS-111) in open air 1 m above the ground. The average absorbed dose rate in each governerate was as follows (number x 10(-2) microGy h-1): Babylon (6.0), Kerbala (5.3), Al-Najaf (5.4), Al-Kadysia (6.5), Wasit (6.5), Diala (6.5), Al-Anbar (6.5), Al-Muthana (6.6), Maisan (6.8), Thee-Kar (6.6), and Al-Basrah (6.5). The collective doses to the population living in these governerates were 499, 187, 239, 269, 262, 458, 384, 153, 250, 450, and 419 person-Sv, respectively.

  12. Combined Treatment With Peroxisome Proliferator-Activated Receptor (PPAR) Gamma Ligands and Gamma Radiation Induces Apoptosis by PPARγ-Independent Up-Regulation of Reactive Oxygen Species-Induced Deoxyribonucleic Acid Damage Signals in Non-Small Cell Lung Cancer Cells

    SciTech Connect

    Han, Eun Jong; Im, Chang-Nim; Park, Seon Hwa; Moon, Eun-Yi; Hong, Sung Hee

    2013-04-01

    Purpose: To investigate possible radiosensitizing activities of the well-known peroxisome proliferator-activated receptor (PPAR)γ ligand ciglitazone and novel PPARγ ligands CAY10415 and CAY10506 in non-small cell lung cancer (NSCLC) cells. Methods and Materials: Radiosensitivity was assessed using a clonogenic cell survival assay. To investigate the mechanism underlying PPARγ ligand-induced radiosensitization, the subdiploid cellular DNA fraction was analyzed by flow cytometry. Activation of the caspase pathway by combined PPARγ ligands and γ-radiation treatment was detected by immunoblot analysis. Reactive oxygen species (ROS) were measured using 2,7-dichlorodihydrofluorescein diacetate and flow cytometry. Results: The 3 PPARγ ligands induced cell death and ROS generation in a PPARγ-independent manner, enhanced γ-radiation–induced apoptosis and caspase-3–mediated poly (ADP-ribose) polymerase (PARP) cleavage in vitro. The combined PPARγ ligand/γ-radiation treatment triggered caspase-8 activation, and this initiator caspase played an important role in the combination-induced apoptosis. Peroxisome proliferator-activated receptor-γ ligands may enhance the γ-radiation-induced DNA damage response, possibly by increasing γ-H2AX expression. Moreover, the combination treatment significantly increased ROS generation, and the ROS scavenger N-acetylcysteine inhibited the combined treatment-induced ROS generation and apoptotic cell death. Conclusions: Taken together, these results indicated that the combined treatment of PPARγ ligands and γ-radiation synergistically induced DNA damage and apoptosis, which was regulated by ROS.

  13. Survival of mouse testicular stem cells after. gamma. or neutron irradiation

    SciTech Connect

    Lu, C.C.; Meistrich, M.L.; Thames, H.D. Jr.

    1980-03-01

    The survival of mouse testicular stem cells after ..gamma.. or neutron irradiation was measured by counts of repopulated tubular cross sections and by the numbers of differentiated spermatogenic cells produced. The numbers of such cells were determined either by sperm head counts of the X-isozyme of lactate dehydrogenase enzyme levels. Qualitatively similar results were obtained with all three assays. The results have confirmed that, with C3H mice, stem-cell survival is higher when the ..gamma..-radiation dose is fractionated by a 24-h interval. Single-dose ..gamma..-radiaton survival curves for the stem cell had large shoulders and also showed the presence of a radioresistant subpopulation which predominated after doses greater than 600 rad. Part of the shoulder must have resulted from repair of sublethal damage since neutron irradiation produced survival curves with smaller shoulders. The relative biological effectiveness for stem-cell killing for these neutrons (mean energy, 22 MeV) varied from about 2.9 at 10 rad of ..gamma.. radiation to 2.2 at 600 rad.

  14. Cell Phone RF Radiation

    NASA Astrophysics Data System (ADS)

    Abdul-Razzaq, Wathiq

    2015-04-01

    In a recent article in Physics Today, Meredith and Redish emphasized the need to make introductory physics courses beneficial for life sciences majors.1 In this study, a lab activity is proposed to measure the intensity of electromagnetic waves emitted by cell phones and connect these measurements to various standards, biological topics, and personal health.

  15. Cell Phone RF Radiation

    ERIC Educational Resources Information Center

    Abdul-Razzaq, Wathiq

    2015-01-01

    In a recent article in "Physics Today," Meredith and Redish emphasized the need to make introductory physics courses beneficial for life sciences majors. In this study, a lab activity is proposed to measure the intensity of electromagnetic waves emitted by cell phones and connect these measurements to various standards, biological

  16. Cell Phone RF Radiation

    ERIC Educational Resources Information Center

    Abdul-Razzaq, Wathiq

    2015-01-01

    In a recent article in "Physics Today," Meredith and Redish emphasized the need to make introductory physics courses beneficial for life sciences majors. In this study, a lab activity is proposed to measure the intensity of electromagnetic waves emitted by cell phones and connect these measurements to various standards, biological…

  17. Cytoskeletal and functional changes in bioreactor assembled thyroid tissue organoids exposed to gamma radiation

    NASA Technical Reports Server (NTRS)

    Green, Lora M.; Patel, Zarana; Murray, Deborah K.; Rightnar, Steven; Burell, Cheryl G.; Gridley, Daila S.; Nelson, Gregory A.

    2002-01-01

    Fischer rat thyroid cells were grown under low-shear stress in a bioreactor to a stage of organization composed of integrated follicles resembling small thyroid glands prior to exposure to 3 Gray-gamma radiation. Bioreactor tissues and controls (both irradiated and non-irradiated) were harvested at 24, 48, 96 and 144 hours post-exposure. Tissue samples were fixed and fluorescently labeled for actin and microtubules. Tissues were assessed for changes in cytoskeletal components induced by radiation and quantified by laser scanning cytometry. ELISA's were used to quantify transforming growth factor-beta and thyroxin released from cells to the culture supernatant. Tissue architecture was disrupted by exposure to radiation with the structural organization of actin and loss of follicular content the most obviously affected. With time post-irradiation the actin appeared disordered and the levels of fluorescence associated with filamentous-actin and microtubules cycled in the tissue analogs, but not in the flask-grown cultures. Active transforming growth factor-beta was higher in supernatants from the irradiated bioreactor tissue. Thyroxin release paralleled cell survival in the bioreactors and control cultures. Thus, the engineered tissue responses to radiation differed from those of conventional tissue culture making it a potentially better mimic of the in vivo situation.

  18. Consequences of Lethal-Whole-Body Gamma Radiation and Possible Ameliorative Role of Melatonin

    PubMed Central

    Mihandoost, Ehsan; Shirazi, Alireza; Mahdavi, Seied Rabie; Aliasgharzadeh, Akbar

    2014-01-01

    Gamma radiation induces the generation of free radicals, leading to serious cellular damages in biological systems. Radioprotectors act as prophylactic agents that are administered to shield normal cells and tissues from the deleterious effects of radiation. Melatonin synergistically acts as an immune-stimulator and antioxidant. We investigated the possible radioprotective role of melatonin (100 mg/kg i.p.) against lethal-whole-body radiation- (10 Gy) induced sickness, body weight loss, and mortality in rats. Results of the present study suggest that exposure to lethal-whole-body radiation incurred mortality, body weight loss, and apoptosis and it also depleted the immunity and the antioxidant status of the rats. Our results show that melatonin pretreatment provides protection against radiation induced mortality, oxidative stress, and immune-suppression. The melatonin pretreated irradiated rats showed less change in body weight as compared to radiation only group. On the other hand, melatonin appeared to have another radioprotective role, suggesting that melatonin may reduce apoptosis through a caspase-3-mediated pathway by blocking caspase-3 activity. PMID:25431791

  19. Effect of gamma radiation on native endolithic microorganisms from a radioactive waste deposit site.

    PubMed

    Pitonzo, B J; Amy, P S; Rudin, M

    1999-07-01

    A time-course experiment was conducted to evaluate the effects of gamma radiation on the indigenous microbiota present in rock obtained from Yucca Mountain, Nevada Test Site. Microcosms were constructed by placing pulverized Yucca Mountain rock in polystyrene cylinders. Continuous exposure (96 h) at a dose rate of 1.63 Gy/min was used to mimic the near-field environment surrounding waste canisters. The expected maximum surface dose rate from one unbreached canister designed to contain spent nuclear fuels is 0.06 Gy/min. Considering the current repository packing design, multiple canisters within one vault, the cumulative dose rate may well approach that used in this experiment. The microbial communities were characterized after receiving cumulative doses of 0, 0.098, 0. 58, 2.33, 4.67, 7.01 and 9.34 kGy. Radiation-resistant microorganisms in the pulverized rock became viable but nonculturable (VBNC) after a cumulative dose of 2.33 kGy. VBNC microorganisms lose the ability to grow on media on which they have routinely been cultured in response to the environmental stress imposed (i.e. radiation) but can be detected throughout the time course using direct fluorescence microscopy techniques. Two representative exopolysaccharide-producing isolates from Yucca Mountain were exposed to the same radiation regimen in sand microcosms. One isolate was much more radiation-resistant than the other, but both had greater resistance than the general microbial community based on culturable counts. However, when respiring cell counts (VBNC) were compared after irradiation, the results would indicate much more radiation resistance of the individual isolates and the microbial community in general. These results have significant implications for underground storage of nuclear waste as they indicate that indigenous microorganisms are capable of surviving gamma irradiation in a VBNC state. PMID:10381842

  20. Radiation-Resistant Micrococcus luteus SC1204 and Its Proteomics Change Upon Gamma Irradiation.

    PubMed

    Deng, Wuyuan; Yang, Yang; Gao, Peng; Chen, Hao; Wen, Wenting; Sun, Qun

    2016-06-01

    To explore the radiation-resistance mechanisms in bacteria, a radiation-resistant strain SC1204 was isolated from the surrounding area of a (60)Co-γ radiation facility. SC1204 could survive up to 8 kGy dose of gamma irradiation and was identified as Micrococcus luteus by phylogenetic analysis of 16S rRNA gene sequences. Its proteomic changes under 2-kGy irradiation were examined by two-dimensional electrophoresis followed by MALDI-TOF-TOF/MS analysis. The results showed that at least 24 proteins displayed significant changes (p < 0.05) at expression level under the radiation stress, among which 22 were successfully identified and classified into the major functional categories of metabolism, energy production and conservation, translation, ribosomal structure, and biogenesis. Among these proteins, leucyl aminopeptidase involved in synthesis of glutathione was the most abundant induced protein during postirradiation recovery, indicating that anti-oxidation protection was the most important line of defense in SC1204 against radiation. The next abundant protein was phosphoribosyl aminoimidazole carboxamide formyltransferase/IMP cyclohydrolase (AICAR Tfase/IMPCH), the key enzyme in the biosynthetic pathway of purine that is anti-radiation compound. Other proteins changing significantly (p < 0.05) after radiation exposure included urocanate hydratase, dihydrolipoyl dehydrogenase, succinyl-CoA synthetase subunit alpha, phosphoglycerate kinase, cell division protein FtsZ, elongation factor Ts and Tu, translation elongation factor Tu and G, 30S ribosomal protein S1, histidyl-tRNA synthetase, and arginyl-tRNA synthetase, which were considered to be the key proteins in urocanate metabolism, tricarboxylic acid cycle, glycolysis, cell division process, and synthesis process of proteins. Therefore, these proteins may also play important roles in radiation resistance in M. luteus. PMID:26920868

  1. Mediate gamma radiation effects on some packaged food items

    NASA Astrophysics Data System (ADS)

    Inamura, Patricia Y.; Uehara, Vanessa B.; Teixeira, Christian A. H. M.; del Mastro, Nelida L.

    2012-08-01

    For most of prepackaged foods a 10 kGy radiation dose is considered the maximum dose needed; however, the commercially available and practically accepted packaging materials must be suitable for such application. This work describes the application of ionizing radiation on several packaged food items, using 5 dehydrated food items, 5 ready-to-eat meals and 5 ready-to-eat food items irradiated in a 60Co gamma source with a 3 kGy dose. The quality evaluation of the irradiated samples was performed 2 and 8 months after irradiation. Microbiological analysis (bacteria, fungus and yeast load) was performed. The sensory characteristics were established for appearance, aroma, texture and flavor attributes were also established. From these data, the acceptability of all irradiated items was obtained. All ready-to-eat food items assayed like manioc flour, some pâtés and blocks of raw brown sugar and most of ready-to-eat meals like sausages and chicken with legumes were considered acceptable for microbial and sensory characteristics. On the other hand, the dehydrated food items chosen for this study, such as dehydrated bacon potatoes or pea soups were not accepted by the sensory analysis. A careful dose choice and special irradiation conditions must be used in order to achieve sensory acceptability needed for the commercialization of specific irradiated food items.

  2. JITTER RADIATION MODEL OF THE CRAB GAMMA-RAY FLARES

    SciTech Connect

    Teraki, Yuto; Takahara, Fumio

    2013-02-15

    The gamma-ray flares of the Crab nebula detected by the Fermi and AGILE satellites challenge our understanding of the physics of pulsars and their nebulae. The central problem is that the peak energy of the flares exceeds the maximum energy E {sub c} determined by synchrotron radiation loss. However, when turbulent magnetic fields exist with scales {lambda}{sub B} smaller than 2{pi}mc {sup 2}/eB, jitter radiation can emit photons with energies higher than E {sub c}. The scale required for the Crab flares is about two orders of magnitude less than the wavelength of the striped wind. We discuss a model in which the flares are triggered by plunging the high-density blobs into the termination shock. The observed hard spectral shape may be explained by the jitter mechanism. We make three observational predictions: first, the polarization degree will become lower in flares; second, no counterpart will be seen in TeV-PeV range; and third, the flare spectrum will not be harder than {nu}F {sub {nu}}{proportional_to}{nu}{sup 1}.

  3. Cell death is induced by ciglitazone, a peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) agonist, independently of PPAR{gamma} in human glioma cells

    SciTech Connect

    Lee, Myoung Woo; Kim, Dae Seong; Kim, Hye Ryung; Kim, Hye Jin; Yang, Jin Mo; Ryu, Somi; Noh, Yoo Hun; Lee, Soo Hyun; Son, Meong Hi; Jung, Hye Lim; Yoo, Keon Hee; Koo, Hong Hoe; Sung, Ki Woong

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer Greater than 30 {mu}M ciglitazone induces cell death in glioma cells. Black-Right-Pointing-Pointer Cell death by ciglitazone is independent of PPAR{gamma} in glioma cells. Black-Right-Pointing-Pointer CGZ induces cell death by the loss of MMP via decreased Akt. -- Abstract: Peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) regulates multiple signaling pathways, and its agonists induce apoptosis in various cancer cells. However, their role in cell death is unclear. In this study, the relationship between ciglitazone (CGZ) and PPAR{gamma} in CGZ-induced cell death was examined. At concentrations of greater than 30 {mu}M, CGZ, a synthetic PPAR{gamma} agonist, activated caspase-3 and induced apoptosis in T98G cells. Treatment of T98G cells with less than 30 {mu}M CGZ effectively induced cell death after pretreatment with 30 {mu}M of the PPAR{gamma} antagonist GW9662, although GW9662 alone did not induce cell death. This cell death was also observed when cells were co-treated with CGZ and GW9662, but was not observed when cells were treated with CGZ prior to GW9662. In cells in which PPAR{gamma} was down-regulated cells by siRNA, lower concentrations of CGZ (<30 {mu}M) were sufficient to induce cell death, although higher concentrations of CGZ ( Greater-Than-Or-Slanted-Equal-To 30 {mu}M) were required to induce cell death in control T98G cells, indicating that CGZ effectively induces cell death in T98G cells independently of PPAR{gamma}. Treatment with GW9662 followed by CGZ resulted in a down-regulation of Akt activity and the loss of mitochondrial membrane potential (MMP), which was accompanied by a decrease in Bcl-2 expression and an increase in Bid cleavage. These data suggest that CGZ is capable of inducing apoptotic cell death independently of PPAR{gamma} in glioma cells, by down-regulating Akt activity and inducing MMP collapse.

  4. Response of radiation monitoring labels to gamma rays and electrons

    NASA Astrophysics Data System (ADS)

    Rahim, F. Abdel; Miller, A.; McLaughlin, W. L.

    Many kinds of coated or impregnated reflecting papers change color or become colored by large radiation doses. Such papers or "labels" do not generally supply dosimetry information, but may give useful inventory information, namely a visual indication of whether or not an industrial product or location has been irradiated to high doses. Among labels available worldwide, a few are suitable for indicating absorbed dose regions of slightly less than 10 4 Gy (< 1 Mrad), and some are intended for monitoring high dose ranges (i.e., sterilization dose levels of > 10 4 Gy or > 1 Mrad), and in some cases even up to very high dose regions (˜10 5 to 10 6 Gy or ˜10 to 100 Mrad). Only one labels which is expected to be commercially available, was studied for lower dose levels, 10 1-10 3 Gy (1-100 krad), namely one based on polymerization of diacetylene. Tests of stability, sensitivity of ambient light, and differences in dose rate and radiation type (gamma rays and electron beams) were made on 15 kinds of labels. The results show that, for many types of indicators, diverse effects may give misleading conclusions unless countermeasures are taken. For example, some of the most commonly used labels, which contain dyes that indicate changes of pH due to release of halogen from halogenated substrates, have limited shelf life and must be protected from extreme environmental conditions. Some also show a marked rate dependence of response. Readings of color reflection optical densities on labels or long paper strips permit somewhat more precise discrimination of dose levels, and may sometimes be useful for monitoring differences in local dose distributions or area monitoring of radiation damage probabilities around particle accelerators or large radionuclide sources.

  5. Rapid and transient activation of gamma/delta T cells to interferon gamma production, NK cell-like killing and antigen processing during acute virus infection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gamma/delta T cells are the majority peripheral blood T cells in young cattle. The role of gamma/delta T cells in innate responses against infection with foot-and-mouth disease virus (FMDV) was analyzed on 5 consecutive days following infection. Before infection, bovine gamma/delta T cells expressed...

  6. Progenitors Mobilized by Gamma-Tocotrienol as an Effective Radiation Countermeasure

    PubMed Central

    Singh, Vijay K.; Wise, Stephen Y.; Fatanmi, Oluseyi O.; Scott, Jessica; Romaine, Patricia L. P.; Newman, Victoria L.; Verma, Amit; Elliott, Thomas B.; Seed, Thomas M.

    2014-01-01

    The purpose of this study was to elucidate the role of gamma-tocotrienol (GT3)-mobilized progenitors in mitigating damage to mice exposed to a supralethal dose of cobalt-60 gamma-radiation. CD2F1 mice were transfused 24 h post-irradiation with whole blood or isolated peripheral blood mononuclear cells (PBMC) from donors that had received GT3 72 h prior to blood collection and recipient mice were monitored for 30 days. To understand the role of GT3-induced granulocyte colony-stimulating factor (G-CSF) in mobilizing progenitors, donor mice were administered a neutralizing antibody specific to G-CSF or its isotype before blood collection. Bacterial translocation from gut to heart, spleen and liver of irradiated recipient mice was evaluated by bacterial culture on enriched and selective agar media. Endotoxin in serum samples also was measured. We also analyzed the colony-forming units in the spleens of irradiated mice. Our results demonstrate that whole blood or PBMC from GT3-administered mice mitigated radiation injury when administered 24 h post-irradiation. Furthermore, administration of a G-CSF antibody to GT3-injected mice abrogated the efficacy of blood or PBMC obtained from such donors. Additionally, GT3-mobilized PBMC inhibited the translocation of intestinal bacteria to the heart, spleen, and liver, and increased colony forming unit-spleen (CFU-S) numbers in irradiated mice. Our data suggests that GT3 induces G-CSF, which mobilizes progenitors and these progenitors mitigate radiation injury in recipient mice. This approach using mobilized progenitor cells from GT3-injected donors could be a potential treatment for humans exposed to high doses of radiation. PMID:25423021

  7. The effect of gamma radiation on the ultrastructure of sweet potatoes (Ipomoea batatas)

    SciTech Connect

    Brown, A.

    1986-12-01

    Radiation is being used to increase the storage life of fresh foods. Various doses of gamma radiation were administered to Jewel cultivar sweet potatoes and the effects were monitored by direct observation and by scanning and transmission electron microscopy. Potatoes were divided into two groups: those irradiated immediately after harvest (doses = 0 kGy - 0.4 KGy) and those irradiated one week after harvest (doses = 0 kGy - 0.4 kGy). Potatoes were examined and viewed each month for 7 months. Gross observations included weight, color and texture of the sweet potatoes. Those potatoes irradiated immediately after harvest spoiled faster than those irradiated one week after harvest. Scanning electron microscopy demonstrated several cellular modifications accompanying spoilage. Cell collapse was greatest at the higher radiation doses during the periods of 1 to 5 months post-irradiation. The shape and size of starch granules varied with storage time and radiation levels. The mitochondria, cell walls and plasma membranes appeared normal as seen by transmission electron microscopy until 6 months post-irradiation for potatoes irradiated both immediately after harvest and one week after harvest. Thereafter, degradative changes were observed.

  8. Radiation sensitivity of Merkel cell carcinoma cell lines

    SciTech Connect

    Leonard, J.H.; Ramsay, J.R.; Birrell, G.W.

    1995-07-30

    Merkel cell carcinoma (MCC), being a small cell carcinoma, would be expected to be sensitive to radiation. Clinical analysis of patients at our center, especially those with macroscopic disease, would suggest the response is quite variable. We have recently established a number of MCC cell lines from patients prior to radiotherapy, and for the first time are in a position to determine their sensitivity under controlled conditions. Some of the MCC lines grew as suspension cultures and could not be single cell cloned; therefore, it was not possible to use clonogenic survival for all cell lines. A tetrazolium based (MTT) assay was used for these lines, to estimate cell growth after {gamma} irradiation. Control experiments were conducted on lymphoblastoid cell lines (LCL) and the adherent MCC line, MCC13, to demonstrate that the two assays were comparable under the conditions used. We have examined cell lines from MCC, small cell lung cancer (SCLC), malignant melanomas, Epstein Barr virus (EBV) transformed lymphocytes (LCL), and skin fibroblasts for their sensitivity to {gamma} irradiation using both clonogenic cell survival and MTT assays. The results show that the tumor cell lines have a range of sensitivities, with melanoma being more resistant (surviving fraction at 2 Gy (SF2) 0.57 and 0.56) than the small cell carcinoma lines, MCC (SF2 range 0.21-0.45, mean SF2 0.30, n = 8) and SCLC (SF2 0.31). Fibroblasts were the most sensitive (SF2 0.13-0.20, mean 0.16, n = 5). The MTT assay, when compared to clonogenic assay for the MCC13 adherent line and the LCL, gave comparable results under the conditions used. Both assays gave a range of SF2 values for the MCC cell lines, suggesting that these cancers would give a heterogeneous response in vivo. The results with the two derivative clones of MCC14 (SF2 for MCC14/1 0.38, MCC14/2 0.45) would further suggest that some of them may develop resistance during clonogenic evolution. 25 refs., 3 figs., 1 tab.

  9. Gamma-ray radiation response at 1550 nm of fluorine-doped radiation hard single-mode optical fiber.

    PubMed

    Kim, Youngwoong; Ju, Seongmin; Jeong, Seongmook; Lee, Seung Ho; Han, Won-Taek

    2016-02-22

    We have investigated gamma-ray radiation response at 1550 nm of fluorine-doped radiation hard single-mode optical fiber. Radiation-induced attenuation (RIA) of the optical fiber was measured under intermittent gamma-ray irradiations with dose rate of ~10 kGy/h. No radiation hardening effect on the RIA by the gamma-ray pre-dose was found when the exposed fiber was bleached for long periods of time (27~47 days) at room-temperature. Photo-bleaching scheme upon 980 nm LD pumping has proven to be an effective deterrent to the RIA, particularly by suppressing the incipient RIA due to room-temperature unstable self-trapped hole defects (STHs). Large temperature dependence of the RIA of the optical fiber together with the photo-bleaching effect are worthy of note for reinforcing its radiation hard characteristics. PMID:26907044

  10. Prompt gamma radiation as a new tool to measure reactor power

    NASA Astrophysics Data System (ADS)

    jalali, Majid; Abdi, Mohammad Reza; davati, Mojtaba Mostajabod

    2013-10-01

    A new method, based on reactor prompt gamma radiation detection, for reactor power measurement is introduced and validated. To verify, the ex-core gamma radiation spectrum from the Iranian Heavy Water Zero Power Reactor (HWZPR) were measured by HPGe and NaI detectors each suitably positioned. The collective prompt gamma count rates for all or for a portion of each of 2″×2″ NaI detector spectra were obtained for seven power level readings from calibrated reactor power monitors. A good linear behavior was found between gamma count rate and reactor power. The method of calibrated prompt gamma reactor power determination is a stable and reliable tool, on-line, sensitive to sudden variation of power, working in pulse mode, increasing redundancy and diversity and so improving the reactor safety. The prompt gamma counting system can be adopted and installed in other nuclear reactors to measure power.

  11. Radiation Metabolomics: Identification of Minimally Invasive Urine Biomarkers for Gamma-Radiation Exposure in Mice

    PubMed Central

    Tyburski, John B.; Patterson, Andrew D.; Krausz, Kristopher W.; Slavík, Josef; Fornace, Albert J.; Gonzalez, Frank J.; Idle, Jeffrey R.

    2008-01-01

    Gamma-radiation exposure has both short- and long-term adverse health effects. The threat of modern terrorism places human populations at risk for radiological exposures, yet current medical countermeasures to radiation exposure are limited. Here we describe metabolomics for γ-radiation biodosimetry in a mouse model. Mice were γ-irradiated at doses of 0, 3 and 8 Gy (2.57 Gy/min), and urine samples collected over the first 24 h after exposure were analyzed by ultra-performance liquid chromatography–time-of-flight mass spectrometry (UPLC–TOFMS). Multivariate data were analyzed by orthogonal partial least squares (OPLS). Both 3- and 8-Gy exposures yielded distinct urine metabolomic phenotypes. The top 22 ions for 3 and 8 Gy were analyzed further, including tandem mass spectrometric comparison with authentic standards, revealing that N-hexanoylglycine and β-thymidine are urinary biomarkers of exposure to 3 and 8 Gy, 3-hydroxy-2-methylbenzoic acid 3-O-sulfate is elevated in urine of mice exposed to 3 but not 8 Gy, and taurine is elevated after 8 but not 3 Gy. Gene Expression Dynamics Inspector (GEDI) self-organizing maps showed clear dose–response relationships for subsets of the urine metabolome. This approach is useful for identifying mice exposed to γ radiation and for developing metabolomic strategies for noninvasive radiation biodosimetry in humans. PMID:18582157

  12. Hydrogel membranes of PVAl/ clay by gamma radiation

    NASA Astrophysics Data System (ADS)

    de Oliveira, M. J. A.; Parra, D. F.; Amato, V. S.; Lugão, A. B.

    2013-03-01

    In the last decades several studies concerning the new methods for drug delivery system have been investigated. A new field known as "smart therapy" involves devices and drug delivery systems to detect, identify and treat the site affected by the disease, not interfering with the biological system. Cutaneous Leishmaniasis is an endemic disease that is characterized by the development of single or multiple localized lesions on exposed areas of skin and one coetaneous treatment could be a potential solution. The aim of this study was to obtain polymeric hydrogel matrices of poly(vinylalcohol)(PVAl) and chitosan with inorganic nanoparticles, which can release a drug according to the need of the treatment of injury caused by leishmania on the skin. The hydrogels matrices were obtained with PVAl/ chitosan and PVAl/ chitosan 0.5; 1.0 and 1.5% laponite RD clay, crosslinked by ionizing gamma radiation with dose of 25 kGy. The techniques used for characterization were swelling, gel fraction, Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TGA). After synthesis, the samples were immersed in distilled water and weighed in periods of time until 60 h for the swelling determination. The obtained results have indicated that the swelling of the membranes increases with clay concentration, in consequence of ionic groups present in the clay.

  13. APPLICATION OF JITTER RADIATION: GAMMA-RAY BURST PROMPT POLARIZATION

    SciTech Connect

    Mao, Jirong; Wang, Jiancheng

    2013-10-10

    A high degree of polarization of gamma-ray burst (GRB) prompt emission has been confirmed in recent years. In this paper, we apply jitter radiation to study the polarization feature of GRB prompt emission. In our framework, relativistic electrons are accelerated by turbulent acceleration. Random and small-scale magnetic fields are generated by turbulence. We further determine that the polarization property of GRB prompt emission is governed by the configuration of the random and small-scale magnetic fields. A two-dimensional compressed slab, which contains a stochastic magnetic field, is applied in our model. If the jitter condition is satisfied, the electron deflection angle in the magnetic field is very small and the electron trajectory can be treated as a straight line. A high degree of polarization can be achieved when the angle between the line of sight and the slab plane is small. Moreover, micro-emitters with mini-jet structures are considered to be within a bulk GRB jet. The jet 'off-axis' effect is intensely sensitive to the observed polarization degree. We discuss the depolarization effect on GRB prompt emission and afterglow. We also speculate that the rapid variability of GRB prompt polarization may be correlated with the stochastic variability of the turbulent dynamo or the magnetic reconnection of plasmas.

  14. Natural gamma-radiation in the Aeolian volcanic arc.

    PubMed

    Chiozzi, P; Pasquale, V; Verdoya, M; Minato, S

    2001-11-01

    Pulse-height distributions of gamma-rays, obtained with a field NaI(Tl) scintillation spectrometer in numerous sites of the Lipari and Vulcano islands (Aeolian volcanic arc, Italy), were measured to determine the U, Th and K concentrations of the bedrock and the relative values of the air absorbed dose rate. U is spatially related to both Th and K and the Th/U ratio is on average 3.1-3.5. The magmatic evolution is reflected by the concentration of the three radioelements, as they are more abundant within the more felsic units of the volcanic series. The higher values of U (15.7-20.0 ppm) coincide with higher Th (48.3-65.9 ppm) and K (4.9-6.1%) concentrations associated with rhyolitic rocks of the third cycle (< 50 ky). The air absorbed dose rate varies from 20 to 470 nGy h(-1). The highest values (> 350 nGy h(-1)) are observed on outcrops of rhyolitic obsidian lava flows. The cosmic-ray contribution is also evaluated to estimate the total background radiation dose rate. PMID:11573810

  15. Effect of gamma radiation on Aspergillus flavus and Aspergillus ochraceus ultrastructure and mycotoxin production

    NASA Astrophysics Data System (ADS)

    Ribeiro, J.; Cavaglieri, L.; Vital, H.; Cristofolini, A.; Merkis, C.; Astoreca, A.; Orlando, J.; Carú, M.; Dalcero, A.; Rosa, C. A. R.

    2011-05-01

    The aim of this work was to study the effect of gamma radiation (2 kGy) on Aspergillus flavus and Aspergillus ochraceus ultrastructure. Moreover, the influence on aflatoxin B 1 and ochratoxin A production was also observed. Irradiated A. flavus strain showed a dull orangish colony while control strain showed the typical green color. Minor differences were observed on stipes, metulae and conidia size between control and irradiated A. flavus and A. ochraceus strains. Irradiated fungi showed ultrastructural changes on cell wall, plasmalema and cytoplasm levels. The levels of mycotoxins produced by irradiated strains were two times greater than those produced by control strains. Successive transferences of irradiated strains on malt extract agar allowed the fungus to recuperate morphological characteristics. Although minor changes in the fungal morphology were observed, ultrastructural changes at cell wall level and the increase of mycotoxin production ability were observed. Inappropriate storage of irradiated food and feed would allow the development of potentially more toxicogenic fungal propagules.

  16. Effects of Dietary Iron and Gamma Radiation on the Rat Retina

    NASA Technical Reports Server (NTRS)

    Morgan, Jennifer; Marshall, Grace; Theriot, Corey A.; Chacon, Natalia; Zwart, Sara; Zanello, Susana B.

    2012-01-01

    A health risk of concern for NASA relates to radiation exposure and its synergistic effects with other space environmental factors, includi ng nutritional status of the crew. Astronauts consume almost three times the recommended daily allowance of iron due to the use of fortifie d foods aboard the International Space Station, with iron intake occa sionally exceeding six times the recommended values. Recently, NASA has become concerned with visual changes associated with spaceflight, a nd research is being conducted to elucidate the etiology of eye structure alterations in the spaceflight environment. Terrestrially, iron o verload is also associated with certain optic neuropathies. In additi on, due to its role in Fenton reactions, iron can potentiate oxidative stress, which is a recognized cause of cataract formation. As part o f a study investigating the combined effects of radiation exposure an d iron overload on multiple physiological systems, we focused on defining the effects of both treatments on eye biology. In this study, 12- week-old Sprague-Dawley rats were assigned to one of four experimental groups: normal iron/no radiation (Control/Sham), high iron/no radiat ion (Fe/Sham), normal iron/gamma radiation (3 Gy cumulative dose, fra ctionated at 0.375 Gy/d every other day for 16 d) (Control/Rad), and high iron/gamma radiation (Fe/Rad). Oxidative stress-induced DNA damag e, measured as concentration of the marker 8-hydroxy-2'-deoxyguanosine (8OHdG) in eye retinal tissue by enzyme-immunoanalysis did not show significant changes among treatments. However, there was an overall i ncrease in 8OHdG immunostaining density in retina sections due to radiation exposure (P = 0.05). Increased dietary iron and radiation expos ure had an interactive effect (P = 0.02) on 8OHdG immunostaining of t he retinal ganglion cell layer with iron diet increasing the signal in the group not exposed to radiation (P = 0.05). qPCR gene expression profiling of relevant target genes indicated upregulation of ferritin light chain (P = 0.09) as a result of dietary iron but no change in e xpression of the gene for ferritin heavy chain. Immunolocalization of light chain and heavy chain of the iron storage protein ferritin showed the expected distribution in the choroid, photoreceptor layer, inn er nuclear layer and in the inner plexiform layer that corresponded t o the synaptic terminals of bipolar cells. Evidence of stress and damage in the retina was also suggested by a decrease in expression of th e survival marker Bcl2 (P = 0.01) and the protective proteins clusterin (P = 0.04) and heat shock factor 1 (Hsf1, P < 0.001), as a result o f increased dietary iron. The effect of increased iron on expression of the antioxidant enzyme heme oxygenase 1 (Hmox1) had a significant interaction with the effect of radiation (P < 0.001). In summary, the results of this study indicate that both gamma radiation exposure and a moderate increase in dietary iron can contribute to deleterious cha nges in retinal health and physiology.

  17. Some neutron and gamma radiation characteristics of plutonium cermet fuel for isotopic power sources

    NASA Technical Reports Server (NTRS)

    Neff, R. A.; Anderson, M. E.; Campbell, A. R.; Haas, F. X.

    1972-01-01

    Gamma and neutron measurements on various types of plutonium sources are presented in order to show the effects of O-17, O-18 F-19, Pu-236, age of the fuel, and size of the source on the gamma and neutron spectra. Analysis of the radiation measurements shows that fluorine is the main contributor to the neutron yields from present plutonium-molybdenum cermet fuel, while both fluorine and Pu-236 daughters contribute significantly to the gamma ray intensities.

  18. [Survival of clonogenic cells of Lewis lung carcinoma cells forming colonies in agar cultures in diffusion chambers during gamma-irradiation and exposure to gamma-neutron californium-252 irradiation].

    PubMed

    Konopliannikov, A G; Lepekhina, L A; Kolesnikova, A I; Ermakov, V I

    1986-01-01

    Clonogenic cells forming colonies in agar cultures in diffusion chambers and those isolated from subcutaneously transplanted Lewis lung carcinoma do not differ in their sensitivity to 60Co gamma-rays with respect to tumor growth stages. The dose-survival curves for all studied cells are S-shaped with a small shoulder. A cumulative dose-survival curve for malignant clonogenic cells is characterized by the average value of mean lethal dose D0 = 2.24 Gy and extrapolation number n = 2.0. When exposed to gamma-neutron-radiation (252Cf) malignant clonogenic cells exhibit a nearly exponential dose-survival curve with D0 = 0.56 Gy (with respect to a neutron component). The RBE of gamma-neutron radiation (252Cf) is 2.5. PMID:3749472

  19. Development of an alpha/beta/gamma detector for radiation monitoring

    SciTech Connect

    Yamamoto, Seiichi; Hatazawa, Jun

    2011-11-15

    For radiation monitoring at the site of nuclear power plant accidents such as Fukushima Daiichi, radiation detectors not only for gamma photons but also for alpha and beta particles are needed because some nuclear fission products emit beta particles and gamma photons and some nuclear fuels contain plutonium that emits alpha particles. We developed a radiation detector that can simultaneously monitor alpha and beta particles and gamma photons for radiation monitoring. The detector consists of three-layered scintillators optically coupled to each other and coupled to a photomultiplier tube. The first layer, which is made of a thin plastic scintillator (decay time: 2.4 ns), detects alpha particles. The second layer, which is made of a thin Gd{sub 2}SiO{sub 5} (GSO) scintillator with 1.5 mol.% Ce (decay time: 35 ns), detects beta particles. The third layer made of a thin GSO scintillator with 0.4 mol.% Ce (decay time: 70 ns) detects gamma photons. By using pulse shape discrimination, the count rates of these layers can be separated. With individual irradiation of alpha and beta particles and gamma photons, the count rate of the first layer represented the alpha particles, the second layer represented the beta particles, and the third layer represented the gamma photons. Even with simultaneous irradiation of the alpha and beta particles and the gamma photons, these three types of radiation can be individually monitored using correction for the gamma detection efficiency of the second and third layers. Our developed alpha, beta, and gamma detector is simple and will be useful for radiation monitoring, especially at nuclear power plant accident sites or other applications where the simultaneous measurements of alpha and beta particles and gamma photons are required.

  20. Dosimetry of mixed neutron and gamma radiation with paired Fricke solutions in light and heavy water.

    PubMed

    Himit, M; Itoh, T; Endo, S; Fujikawa, K; Hoshi, M

    1996-06-01

    Paired Fricke solutions, made up from light water or heavy water and 0.8N in H2SO4 and 1 mM in Fe(NH4)2(SO4)2 and NaCl, were calibrated with 60Co gamma rays and with mixed neutron and gamma radiation from a 252Cf source. Absorbance increases, AL and AH, in light- and heavy-water Fricke dosimeters, respectively, increased with fast-neutron and gamma-ray tissue doses, Dn (GY) and D gamma (GY), of the mixed radiation as follows: AL = 0.00178Dn + 0.00371D gamma; AH = 0.00121Dn + 0.00442 D gamma. G-values of 7.2 and 5.5 were obtained for 252Cf neutrons in light- and heavy-water Fricke dosimeters, respectively. When we applied the pair of equations to AL and AH values observed after exposure to mixed radiation in a nuclear reactor, resulting Dn and D gamma values agreed within 10% to doses measured with paired ionization chambers. Doses required for Fricke dosimeters were 5 Gy or more. In contrast, we found that micronuclear yields in onion roots can measure the neutron component of mixed radiation fields at the order of 10 cGy with reasonable accuracy even if the neutron to gamma-ray dose ratio is unknown. PMID:8840720

  1. A gamma-ray testing technique for spacecraft. [considering cosmic radiation effects

    NASA Technical Reports Server (NTRS)

    Gribov, B. S.; Repin, N. N.; Sakovich, V. A.; Sakharov, V. M.

    1977-01-01

    The simulated cosmic radiation effect on a spacecraft structure is evaluated by gamma ray testing in relation to structural thickness. A drawing of the test set-up is provided and measurement errors are discussed.

  2. Effect of Gamma Radiation on Zinc Tolerance Efficiency of Aspergillus terreus Thorn.

    PubMed

    Das, Dipanwita; Chakraborty, A; Santra, S C

    2016-03-01

    The present study emphasizes the potential of gamma radiation in enhancing zinc tolerance of Aspergillus terreus. Gamma-exposed A. terreus could tolerate 1.13 times more Zn, reflecting higher growth (in terms of CFU) under Zn stress and enhanced Zn removal efficacies than their unirradiated counterparts. Radiation-induced upregulation of antioxidative system (SOD, CAT, GSH and MT) of A. terreus is responsible for radiation-induced enhancement of Zn tolerance. FTIR spectra reveals the involvement of functional groups in Zn biosorption; SEM study divulges the structural changes due to metal and gamma exposure and SEM-EDX depicts the Zn uptake by A. terreus (both in gamma-exposed and unexposed conditions). This work sheds light toward utilizing low doses of ionizing radiation for making more metal-tolerant fungi and the possible mechanisms adopted by A. terreus for being more metallo-resistant. PMID:26612034

  3. Detection system for high-resolution gamma radiation spectroscopy with neutron time-of-flight filtering

    DOEpatents

    Dioszegi, Istvan; Salwen, Cynthia; Vanier, Peter

    2014-12-30

    A .gamma.-radiation detection system that includes at least one semiconductor detector such as HPGe-Detector, a position-sensitive .alpha.-Detector, a TOF Controller, and a Digitizer/Integrator. The Digitizer/Integrator starts to process the energy signals of a .gamma.-radiation sent from the HPGe-Detector instantly when the HPGe-Detector detects the .gamma.-radiation. Subsequently, it is determined whether a coincidence exists between the .alpha.-particles and .gamma.-radiation signal, based on a determination of the time-of-flight of neutrons obtained from the .alpha.-Detector and the HPGe-Detector. If it is determined that the time-of-flight falls within a predetermined coincidence window, the Digitizer/Integrator is allowed to continue and complete the energy signal processing. If, however, there is no coincidence, the Digitizer/Integrator is instructed to be clear and reset its operation instantly.

  4. Deinococcus puniceus sp. nov., a bacterium isolated from soil-irradiated gamma radiation.

    PubMed

    Lee, Jae-Jin; Srinivasan, Sathiyaraj; Lim, Sangyong; Joe, Minho; Im, Seonghun; Kim, Myung Kyum

    2015-04-01

    A Gram-positive, coccus-shaped, crimson-color-pigmented bacterium was isolated from soil irradiated with 5 kGy gamma radiation and was designated strain DY1(T). Cells showed growth at 10-30 °C and pH 7-11 and were oxidase-negative and catalase-positive. Phylogenetic analyses of the 16S rRNA gene showed that the strain DY1(T) belonged to the genus Deinococcus with sequence similarities to Deinococcus aquatilis CCUG 53370(T) (96.2 %) and Deinococcus navajonensis KR-114(T) (94.1 %). Strain DY1(T) showed low level of DNA relatedness with D. aquatilis CCUG 53370(T) (41.3 ± 3.9 %). The DNA G + C content of DY1(T) was 58.7 mol%. Predominant fatty acids were summed feature 3 (C16:1 ω7c/ω6c), C16:0, and C17:0. The major amino acids were D-alanine, L-glutamic acid, glycine, and L-ornithine in the peptidoglycan. The major polar lipids were unknown phosphoglycolipids (PGL). Strain DY1(T) has resistance to gamma radiation and was found to be a novel species. Therefore, the strain was designated as DY1(T) (=KCTC 33027(T) = JCM 18576(T)), and the name Deinococcus puniceus sp. nov. is herein proposed. PMID:25477066

  5. Occurrence in vivo of sister chromatid exchanges at the same locus in successive cell divisions caused by nonrepairable lesions induced by gamma rays

    SciTech Connect

    Morales-Ramirez, P.; Vallarino-Kelly, T.; Rodriguez-Reyes, R.

    1988-01-01

    The capacity of lesions induced by gamma radiation to produce sister chromatid exchanges (SCE) in successive divisions in mouse bone marrow cells in vivo was evaluated using a protocol for the three-way differentiation of sister chromatids. Evidence was obtained that exposure to gamma radiation induces DNA lesions that result in the formation of SCE at the same locus in two successive cell divisions. The relevance of this observation with respect to DNA repair and mutagenesis is discussed.

  6. Influence of gamma radiation on microbiological parameters of the ethanolic fermentation of sugar-cane must

    NASA Astrophysics Data System (ADS)

    Alcarde, A. R.; Walder, J. M. M.; Horii, J.

    2003-04-01

    The influence of gamma radiation on reducing the population of some bacteria Bacillus and Lactobacillus that usually contaminate the sugar-cane must and its effects on acidity of the medium and viability of the yeast during fermentation were evaluated. The treatment with gamma radiation reduced the bacterial load of the sugar-cane must. Consequently, the volatile acidity produced during the fermentation of the must decreased and the viability of the yeast afterwards added increased.

  7. Pulsar and diffuse contributions to observed galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Harding, A. K.; Stecker, F. W.

    1981-01-01

    The first calculation of a gamma-ray production spectrum from pulsars in the Galaxy, along with a statistical analysis of data on 328 known radio pulsars, are presented. The implications of this point source contribution to the general interpretation of the observed galactic gamma-ray spectrum are indicated. The contributions from diffuse interstellar cosmic-ray induced production mechanisms are then re-examined, concluding that pulsars may be contributing significantly to the galactic gamma-ray emission.

  8. Angular distribution of gamma-ray radiation from magnetic polar caps of fast pulsars.

    NASA Astrophysics Data System (ADS)

    Shuyuan, An

    1991-08-01

    A numerical investigation on the angular distribution of the gamma-ray radiation emitted by relativistic primary particles flying from the magnetic polar caps of a fast pulsar with an inclination of χ ≠ 0 between its rotating axis and magnetic axis is presented on the basis of the classical theory of radiation. It is indicated that the major factors which intensely influence the orientation characteristics of the gamma-ray radiation are the curvature of the magnetic line and the energy dissipation of the primary particles. The considerable distortion of the magnetic line will lead to a certain amount of the directivity dispersion of the radiation.

  9. Latexin sensitizes leukemogenic cells to gamma-irradiation-induced cell-cycle arrest and cell death through Rps3 pathway.

    PubMed

    You, Y; Wen, R; Pathak, R; Li, A; Li, W; St Clair, D; Hauer-Jensen, M; Zhou, D; Liang, Y

    2014-01-01

    Leukemia is a leading cause of cancer death. Recently, the latexin (Lxn) gene was identified as a potential tumor suppressor in several types of solid tumors and lymphoma, and Lxn expression was found to be absent or downregulated in leukemic cells. Whether Lxn functions as a tumor suppressor in leukemia and what molecular and cellular mechanisms are involved are unknown. In this study, the myeloid leukemogenic FDC-P1 cell line was used as a model system and Lxn was ectopically expressed in these cells. Using the protein pull-down assay and mass spectrometry, ribosomal protein subunit 3 (Rps3) was identified as a novel Lxn binding protein. Ectopic expression of Lxn inhibited FDC-P1 growth in vitro. More surprisingly, Lxn enhanced gamma irradiation-induced DNA damages and induced cell-cycle arrest and massive necrosis, leading to depletion of FDC-P1 cells. Mechanistically, Lxn inhibited the nuclear translocation of Rps3 upon radiation, resulting in abnormal mitotic spindle formation and chromosome instability. Rps3 knockdown increased the radiation sensitivity of FDC-P1, confirming that the mechanism of action of Lxn is mediated by Rps3 pathway. Moreover, Lxn enhanced the cytotoxicity of chemotherapeutic agent, VP-16, on FDC-P1 cells. Our study suggests that Lxn itself not only suppresses leukemic cell growth but also potentiates the cytotoxic effect of radio- and chemotherapy on cancer cells. Lxn could be a novel molecular target that improves the efficacy of anti-cancer therapy. PMID:25341047

  10. Latexin sensitizes leukemogenic cells to gamma-irradiation-induced cell-cycle arrest and cell death through Rps3 pathway

    PubMed Central

    You, Y; Wen, R; Pathak, R; Li, A; Li, W; St Clair, D; Hauer-Jensen, M; Zhou, D; Liang, Y

    2014-01-01

    Leukemia is a leading cause of cancer death. Recently, the latexin (Lxn) gene was identified as a potential tumor suppressor in several types of solid tumors and lymphoma, and Lxn expression was found to be absent or downregulated in leukemic cells. Whether Lxn functions as a tumor suppressor in leukemia and what molecular and cellular mechanisms are involved are unknown. In this study, the myeloid leukemogenic FDC-P1 cell line was used as a model system and Lxn was ectopically expressed in these cells. Using the protein pull-down assay and mass spectrometry, ribosomal protein subunit 3 (Rps3) was identified as a novel Lxn binding protein. Ectopic expression of Lxn inhibited FDC-P1 growth in vitro. More surprisingly, Lxn enhanced gamma irradiation-induced DNA damages and induced cell-cycle arrest and massive necrosis, leading to depletion of FDC-P1 cells. Mechanistically, Lxn inhibited the nuclear translocation of Rps3 upon radiation, resulting in abnormal mitotic spindle formation and chromosome instability. Rps3 knockdown increased the radiation sensitivity of FDC-P1, confirming that the mechanism of action of Lxn is mediated by Rps3 pathway. Moreover, Lxn enhanced the cytotoxicity of chemotherapeutic agent, VP-16, on FDC-P1 cells. Our study suggests that Lxn itself not only suppresses leukemic cell growth but also potentiates the cytotoxic effect of radio- and chemotherapy on cancer cells. Lxn could be a novel molecular target that improves the efficacy of anti-cancer therapy. PMID:25341047

  11. GaAs Solar Cell Radiation Handbook

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.

    1996-01-01

    History of GaAs solar cell development is provided. Photovoltaic equations are described along with instrumentation techniques for measuring solar cells. Radiation effects in solar cells, electrical performance, and spacecraft flight data for solar cells are discussed. The space radiation environment and solar array degradation calculations are addressed.

  12. Shelf life extension of fresh turmeric ( Curcuma longa L.) using gamma radiation

    NASA Astrophysics Data System (ADS)

    Dhanya, R.; Mishra, B. B.; Khaleel, K. M.; Cheruth, Abdul Jaleel

    2009-09-01

    Gamma radiation processing was found to extend shelf life of fresh turmeric. A 5 kGy radiation dose and 10 °C storage temperature was found to keep peeled turmeric samples microbe free and acceptable until 60 days of storage. The control sample without radiation treatment spoiled within a week of storage. The changes in color, texture and moisture content of fresh turmeric due to radiation treatment were found to be statistically insignificant.

  13. Paracoccidioides brasiliensis-stimulated human gamma/delta T cells support antibody production by B cells.

    PubMed Central

    Munk, M E; Fazioli, R A; Calich, V L; Kaufmann, S H

    1995-01-01

    Paracoccidioidomycosis patients show hyperactive humoral immune responses. Consequently, we investigated whether cytokines in supernatants from Paracoccidioides brasiliensis-stimulated gamma/delta T cells support B-cell activation. We detected proliferation of B cells and increased immunoglobulin M (IgM) and IgG production. Thus, gamma/delta T cells may participate in polyclonal B-cell activation during paracoccidioidomycosis. PMID:7890430

  14. Nature of gamma rays background radiation in new and old buildings of Qatar University

    SciTech Connect

    Al-Houty, L.; Abou-Leila, H.; El-Kameesy, S. )

    1987-01-01

    Measurements and analysis of gamma-background radiation spectrum in four different places of Qatar University campus were performed at the energy range 10 keV-3 MeV using hyper pure Ge-detector. The dependence of the detector absolute photopeak efficiency on gamma-ray energies was determined and correction of the data for that was also done. The absorbed dose for each gamma line was calculated and an estimation of the total absorbed dose for the detected gamma lines in the four different places was obtained. Comparison with other results was also performed.

  15. EGRET Observations of High-Energy Gamma Radiation from PSR B1706-44

    NASA Astrophysics Data System (ADS)

    Thompson, D. J.; Bailes, M.; Bertsch, D. L.; Esposito, J. A.; Fichtel, C. E.; Harding, A. K.; Hartman, R. C.; Hunter, S. D.; Manchester, R. N.; Mattox, J. R.; von Montigny, C.; Mukherjee, R.; Ramanamurthy, P. V.; Sreekumar, P.; Fierro, J. M.; Lin, Y. C.; Michelson, P. F.; Nolan, P. L.; Kanbach, G.; Mayer-Hasselwander, H. A.; Merck, M.; Kniffen, D. A.; Schneid, E. J.; Kaspi, V. M.; Johnston, S.; Daugherty, J.; Ruderman, M.

    1996-07-01

    The Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory has observed PSR B1706-44 a number of times between 1991 and 1995. From these data, a more detailed picture of the gamma radiation from this source has been developed, showing several characteristics that distinguish this pulsar from others: the light curve is complex, with evidence of three pulses; there is no detectable unpulsed emission; and the energy spectrum changes slope at 1 GeV. No two of the known gamma-ray pulsars have quite the same characteristics; this diversity makes interpretation in terms of theoretical models difficult.

  16. Effects of gamma radiation on raspberries: safety and quality issues.

    PubMed

    Verde, S Cabo; Trigo, M J; Sousa, M B; Ferreira, A; Ramos, A C; Nunes, I; Junqueira, C; Melo, R; Santos, P M P; Botelho, M L

    2013-01-01

    There is an ever-increasing global demand from consumers for high-quality foods with major emphasis placed on quality and safety attributes. One of the main demands that consumers display is for minimally processed, high-nutrition/low-energy natural foods with no or minimal chemical preservatives. The nutritional value of raspberry fruit is widely recognized. In particular, red raspberries are known to demonstrate a strong antioxidant capacity that might prove beneficial to human health by preventing free radical-induced oxidative stress. However, food products that are consumed raw, are increasingly being recognized as important vehicles for transmission of human pathogens. Food irradiation is one of the few technologies that address both food quality and safety by virtue of its ability to control spoilage and foodborne pathogenic microorganisms without significantly affecting sensory or other organoleptic attributes of the food. Food irradiation is well established as a physical, nonthermal treatment (cold pasteurization) that processes foods at or nearly at ambient temperature in the final packaging, reducing the possibility of cross contamination until the food is actually used by the consumer. The aim of this study was to evaluate effects of gamma radiation on raspberries in order to assess consequences of irradiation. Freshly packed raspberries (Rubus idaeus L.) were irradiated in a (60)Co source at several doses (0.5, 1, or 1.5 kGy). Bioburden, total phenolic content, antioxidant activity, physicochemical properties such as texture, color, pH, soluble solids content, and acidity, and sensorial parameters were assessed before and after irradiation and during storage time up to 14 d at 4°C. Characterization of raspberries microbiota showed an average bioburden value of 10(4) colony-forming units (CFU)/g and a diverse microbial population predominantly composed of two morphological types (gram-negative, oxidase-negative rods, 35%, and filamentous fungi, 41%). The inactivation studies on the raspberries mesophilic population indicated a one log reduction of microbial load (95% inactivation efficiency for 1.5 kGy), in the surviving population mainly constituted by filamentous fungi (79-98%). The total phenolic content of raspberries indicated an increase with radiation doses and a decrease with storage time. The same trend was found for raspberries' antioxidant capacity with storage time. Regarding raspberries physicochemical properties, irradiation induced a significant decrease in firmness compared with nonirradiated fruit. However, nonirradiated and irradiated fruit presented similar physicochemical and sensory properties during storage time. Further studies are needed to elucidate the benefits of irradiation as a raspberries treatment process. PMID:23514071

  17. X-ray and gamma-ray astronomy. [origins of extraterrestrial radiation sources

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Accomplishments in the fields of X-ray and gamma ray astronomy are discussed. Data obtained from IMP and OGO satellites are analyzed to determine the sources of interplanetary radiation bursts. The energy spectrum of cosmic gamma ray bursts as observed by IMP-6 is described. The application of cooling blackbody techniques as a method for examining cosmic gamma ray bursts is reported. The experimental results and theoretical interpretation of high energy diffuse gamma rays are investigated. The structure of the SAS-2 satellite is depicted and the accomplishments are examined. Other sources of gamma radiation to include galactic fermi, Cygnus X-1, supernovae, and the planet Jupiter are proposed. Data obtained from the Pioneer 10 space probe are presented in graph form.

  18. RBE (relative biological effectiveness) of tritium beta radiation to gamma radiation and x-rays analyzed by both molecular and genetic methods

    SciTech Connect

    Lee, W.R.

    1988-01-01

    The relative biological effectiveness (RBE) of tritium beta radiation to /sup 60/Co gamma radiation was determined using sex-linked recessive lethals (SLRL) induced in Drosophila melanogaster spermatozoa as the biological effect. The SLRL test, a measure of mutations induced in germ cells transmitted through successive generations, yields a linear dose-response curve in the range used in these experiments. From these ratios of the slopes of the /sup 3/H beta and the /sup 60/ Co gamma radiation linear dose response curves, an RBE of 2.7 is observed. When sources of error are considered, this observation suggests that the tritium beta particle is 2.7 /plus minus/ 0.3 times more effective per unit of energy absorbed in inducing gene mutations transmitted to successive generation than /sup 60/Co gamma radiation. Ion tracks with a high density of ions (high LET) are more efficient than tracks with a low ion density (low LET) in inducing transmissible mutations, suggesting interaction among products of ionization. Molecular analysis of x-ray induced mutations shows that most mutations are deletions ranging from a few base pairs as determined from sequence data to multi locus deletions as determined from complementation tests and Southern blots. 14 refs., 1 fig.

  19. Attosecond Gamma-Ray Pulses via Nonlinear Compton Scattering in the Radiation-Dominated Regime.

    PubMed

    Li, Jian-Xing; Hatsagortsyan, Karen Z; Galow, Benjamin J; Keitel, Christoph H

    2015-11-13

    The feasibility of the generation of bright ultrashort gamma-ray pulses is demonstrated in the interaction of a relativistic electron bunch with a counterpropagating tightly focused superstrong laser beam in the radiation-dominated regime. The Compton scattering spectra of gamma radiation are investigated using a semiclassical description for the electron dynamics in the laser field and a quantum electrodynamical description for the photon emission. We demonstrate the feasibility of ultrashort gamma-ray bursts of hundreds of attoseconds and of dozens of megaelectronvolt photon energies in the near-backwards direction of the initial electron motion. The tightly focused laser field structure and the radiation reaction are shown to be responsible for such short gamma-ray bursts, which are independent of the durations of the electron bunch and of the laser pulse. The results are measurable with the laser technology available in the near future. PMID:26613446

  20. Isodose mapping of terrestrial gamma radiation dose rate of Selangor state, Kuala Lumpur and Putrajaya, Malaysia.

    PubMed

    Sanusi, M S M; Ramli, A T; Gabdo, H T; Garba, N N; Heryanshah, A; Wagiran, H; Said, M N

    2014-09-01

    A terrestrial gamma radiation survey for the state of Selangor, Kuala Lumpur and Putrajaya was conducted to obtain baseline data for environmental radiological health practices. Based on soil type, geological background and information from airborne survey maps, 95 survey points statistically representing the study area were determined. The measured doses varied according to geological background and soil types. They ranged from 17 nGy h(-1) to 500 nGy h(-1). The mean terrestrial gamma dose rate in air above the ground was 182 ± 81 nGy h(-1). This is two times higher than the average dose rate of terrestrial gamma radiation in Malaysia which is 92 nGy h(-1) (UNSCEAR 2000). An isodose map was produced to represent exposure rate from natural sources of terrestrial gamma radiation. PMID:24787672

  1. Attosecond Gamma-Ray Pulses via Nonlinear Compton Scattering in the Radiation-Dominated Regime

    NASA Astrophysics Data System (ADS)

    Li, Jian-Xing; Hatsagortsyan, Karen Z.; Galow, Benjamin J.; Keitel, Christoph H.

    2015-11-01

    The feasibility of the generation of bright ultrashort gamma-ray pulses is demonstrated in the interaction of a relativistic electron bunch with a counterpropagating tightly focused superstrong laser beam in the radiation-dominated regime. The Compton scattering spectra of gamma radiation are investigated using a semiclassical description for the electron dynamics in the laser field and a quantum electrodynamical description for the photon emission. We demonstrate the feasibility of ultrashort gamma-ray bursts of hundreds of attoseconds and of dozens of megaelectronvolt photon energies in the near-backwards direction of the initial electron motion. The tightly focused laser field structure and the radiation reaction are shown to be responsible for such short gamma-ray bursts, which are independent of the durations of the electron bunch and of the laser pulse. The results are measurable with the laser technology available in the near future.

  2. Interferon-gamma reduces melanosomal antigen expression and recognition of melanoma cells by cytotoxic T cells.

    PubMed

    Le Poole, I Caroline; Riker, Adam I; Quevedo, M Eugenia; Stennett, Lawrence S; Wang, Ena; Marincola, Francesco M; Kast, W Martin; Robinson, June K; Nickoloff, Brian J

    2002-02-01

    In malignant melanoma, tumor-infiltrating lymphocytes are frequently reactive with melanosomal antigens. Achieving complete remissions by peptide therapy is frequently hampered by metastases evading immune recognition. The tumor microenvironment seems to favor reduced expression of target antigens by melanoma cells. Among candidate factors, interferon-gamma (IFN-gamma) (10(2) to 10(3) U/ml) suppressed expression of antigens MART-1, TRP-1, and gp100 by M14 melanoma cells as shown by immunohistology and fluorescence-activated cell sorting analysis, reducing MART-1 expression by >65%. Northern blot analysis revealed that reduced expression was regulated at the transcriptional level, demonstrating a 79% reduction in MART-1 transcript abundance after 32 hours of IFN-gamma treatment. To evaluate consequences of IFN-gamma exposure for immune recognition, MART-1-responsive T cells were reacted with pretreated HLA-matched melanoma cells. Cytotoxicity was reduced up to 78% by IFN-gamma pretreatment, and was restored by addition of MART-1 peptide AAGIGILTV for 2 hours. Examination of melanoma lesions by quantitative reverse transcriptase-polymerase chain reaction revealed up to 188-fold more abundant IFN-gamma transcripts when compared to control skin. Laser capture microdissection and immunohistology localized most IFN-gamma-producing T cells to the tumor stroma. Reduced MART-1 expression was frequently observed in adjacent tumor cells. Consequently, IFN-gamma may enhance inflammatory responses yet hamper effective recognition of melanoma cells. PMID:11839572

  3. Mutation measurement in mammalian cells. IV: Comparison of gamma-ray and chemical mutagenesis.

    PubMed

    Puck, T T; Johnson, R; Webb, P; Yohrling, G

    1998-01-01

    The interaction of chemical mutagens with mammalian cells is much more complex than that of gamma-irradiation because of the different ways in which chemical agents react with cell and medium components. Nevertheless, the system previously described for analysis of mutagenesis by gamma-radiation appears applicable to chemical mutagenesis. The approach involves measurement of cell survival, use of caffeine to inhibit repair, analysis of mitotic index changes, and quantitation of microscopically visible structural changes in mitotic chromosomes. The behavior of a variety of chemical mutagens and nonmutagens in this system is described and compared with that of gamma-irradiation. The procedure is simple and the results reasonably quantitative though less so than those of gamma-irradiation. The procedure can be used for environmental monitoring, analysis of mutational events, and individual and epidemiological testing. Mutational events should be classified as primary or secondary depending on whether they represent initial genomic insult, or genomic changes resulting from primary mutation followed by structural changes due to metabolic actions. While caffeine has multiple effects on the mammalian genome, when used under the conditions specified here it appears to act principally as an inhibitor of mutation repair, and so affords a measure of the role of repair in the action of different mutagens on cells in the G2 phase of the life cycle. PMID:9776977

  4. Low dose radiation-induced endothelial cell retraction.

    PubMed

    Kantak, S S; Diglio, C A; Onoda, J M

    1993-09-01

    We characterized in vitro the effects of gamma-radiation (12.5-100 cGy) on pulmonary microvascular endothelial cell (PMEC) morphology and F-actin organization. Cellular retraction was documented by phase-contrast microscopy and the organization of actin microfilaments was determined by immunofluorescence. Characterization included radiation dose effects, their temporal duration and reversibility of the effects. A dose-dependent relationship between the level of exposure (12.5-100 cGy) and the rate and extent of endothelial retraction was observed. Moreover, analysis of radiation-induced depolymerization of F-actin microfilament stress fibres correlated positively with the changes in PMEC morphology. The depolymerization of the stress fibre bundles was dependent on radiation dose and time. Cells recovered from exposure to reform contact inhibited monolayers > or = 24 h post-irradiation. Concomitantly, the depolymerized microfilaments reorganized to their preirradiated state as microfilament stress fibres arrayed parallel to the boundaries of adjacent contact-inhibited cells. The data presented here are representative of a series of studies designed to characterize low-dose radiation effects on pulmonary microvascular endothelium. Our data suggest that post-irradiation lung injuries (e.g. oedema) may be induced with only a single fraction of therapeutic radiation, and thus microscopic oedema may initiate prior to the lethal effects of radiation on the microvascular endothelium, and much earlier than would be suggested by the time course for clinically-detectable oedema. PMID:8105010

  5. Indoor and outdoor in situ high-resolution gamma radiation measurements in urban areas of Cyprus.

    PubMed

    Svoukis, E; Tsertos, H

    2007-01-01

    In situ, high-resolution, gamma-ray spectrometry of a total number of 70 outdoor and 20 indoor representative measurements were performed in preselected, common locations of the main urban areas of Cyprus. Specific activities and gamma absorbed dose rates in air due to the naturally occurring radionuclides of (232)Th and (238)U series, and (40)K are determined and discussed. Effective dose rate to the Cyprus population due to terrestrial gamma radiation is derived directly from this work. The results obtained outdoors match very well with those derived previously by high-resolution gamma spectrometry of soil samples, which were collected from the main island bedrock surface. This implies that the construction and building materials in urban areas do not affect the external gamma dose rate; thus they are mostly of local origin. Finally, the indoor/outdoor gamma dose ratio was found to be 1.4 +/- 0.5. PMID:17065195

  6. Protection effects of condensed bromoacenaphthylene on radiation deterioration of ethylene-propylene-diene rubber. [Gamma radiation

    SciTech Connect

    Morita, Y.; Hagiwara, M.; Kasai, N.

    1982-09-01

    As a continuation of a series of the studies on the flame and ..gamma..-radiation resistant modification of ethylene-propylene-diene rubber (EPDM), condensed bromoacenaphthylene (con-BACN) as a newly developed flame retardant was synthesized and its effects on the radiation resistance of EPDM were investigated. The radiation resistance evaluated by measuring tensile properties of irradiated sheets of 2 mm thick was found improved greatly by adding con-BACN together with ordinary rubber ingredients but decreased by decabromodiphenylether (DBDPE) that has bromins in aromatic rings as con-BACN. When EPDM sheets of 1 mm thick were irradiated in oxygen at a dose rate of 1 X 10/sup 5/ rad/h, the weight swelling ratio increased with increasing dose, indicating that oxidative main chain scission is predominant under the irradiation conditions. On the other hand, crosslinking was shown to be predominant in nitrogen. From the results of the swelling experiments with different additives, it was concluded that DBDPE accelerates both the main chain scission in oxygen and the crosslinking in nitrogen. In contrast to this, con-BACN reduced the chain scission in oxygen. This observation was accounted by the assumption that the influence of the oxidative chain scission is partly compensated by the concurrent crosslinking which takes place through additions of con-BACN to substrate polymers even in the presence of oxygen.

  7. Study of a number of biochemical indices of the blood and tissue of dogs after prolonged gamma-radiation

    NASA Technical Reports Server (NTRS)

    Alers, I.; Alersova, E.; Praslichka, T.; Mishurova, E.; Sedlakova, A.; Malatova, Z.; Akhunov, A. A.; Markelov, B. A.

    1974-01-01

    The glucose content in blood and the lipid content in serum and tissues of dogs exposed to chronic radiation for 3 and 5 years were studied. In tissues of these animals, the concentration of soluble DNA and DNA contained in DNP was studied in the spleen, lymph node (deep cervical node) and bone marrow of thigh bones. Results indicate that chronic gamma irradiation significantly changes concentrations of glucose in the blood, and that of several lipids in serum and tissues. A reduction in the concentration of DNP in tested organs reflects changes in the relative number of cells with various nuclear cytoplasmic ratios; most pronounced changes in biochemical indices occur in dogs exposed to chronic gamma radiation in doses of 125 rad per year.

  8. Roles of ionizing radiation in cell transformation

    SciTech Connect

    Tobias, C.A.; Albright, N.W.; Yang, T.C.

    1983-07-01

    Earlier the authors described a repair misrepair model (RMR-I) which is applicable for radiations of low LET, e.g., x rays and gamma rays. RMR-II was described later. Here is introduced a mathematical modification of the RMR model, RMR-III, which is intended to describe lethal effects caused by heavily ionizing tracks. 31 references, 4 figures.

  9. Comptonization of diffuse ambient radiation by a relativistic jet: The source of gamma rays from blazars?

    NASA Technical Reports Server (NTRS)

    Sikora, Marek; Begelman, Mitchell C.; Rees, Martin J.

    1994-01-01

    Recent Energy Gamma Ray Experiment Telescope (EGRET) observations of blazars have revealed strong, variable gamma-ray fluxes with no signatures of gamma-ray absorption by pair production. This radiation probably originates from the inner parts of relativistic jets which are aimed nearly toward us. On sub-parsec scales, the jet will be pervaded by radiation from the broad-line region, as well as by photons from the central continuum source (some of which will be scattered by thermal plasma). In a frame moving with the relativistic outflow, the energy of this ambient radiation would be enhanced. This radiation would be Comptonized by both cold and relativistic electrons in the jet, yielding (in the observer's frame) a collimated beam of X-rays and gamma rays. On the assumption that this process dominates self-Comptonization of synchrotron radiation, we develop a self-consistent model for variable gamma-ray emission, involving a single population of relativistic electrons accelerated by a disturbance in the jet. The spectral break between the X-ray and gamma-ray band, observed in 3C 279 and deduced for other blazars, results from inefficient radiative cooling of lower energy electrons. The existence of such a break strongly favors a model involving Comptonization of an external radiation field over a synchrotron self-Compton model. We derive constraints on such model parameters as the location and speed of the source, its dimensions and internal physical parameters, the maximum photon energies produced in the source, and the density and distribution of ambient radiation. Finally, we discuss how observations might discriminate between our model and alternative ones invoking Comptonization of ambient radiation.

  10. Mechanisms for production of the diffuse gamma-ray continuum radiation

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1973-01-01

    Basic mechanisms involved in the production of cosmic gamma radiation are outlined. They include Compton interactions with low energy protons, bremsstrahlung interactions, cosmic ray induced neutral pion production, and matter-antimatter annihilation. Detailed data are given on diffuse continuum radiation. Comparative data results are given in tables and graphs.

  11. Comments on radiation sterilization in the UK and on the efficient operation of a gamma plant

    NASA Astrophysics Data System (ADS)

    Frohnsdorff, R. S. M.

    Some general comments are made on the use of gamma radiation for the sterilisation of medical products in the UK. The radiation process is deceptively simple but successful operation requires careful study of detail. A computer has been programmed to study the arrangement of radio-active source rods. Optimisation of the source can improve dose uniformity and process efficiency.

  12. Reliability studies on Si PIN photodiodes under Co-60 gamma radiation

    SciTech Connect

    Prabhakara Rao, Y. P.; Praveen, K. C.; Gnana Prakash, A. P.; Rani, Y. Rejeena

    2013-02-05

    Silicon PIN photodiodes were fabricated with 250 nm SiO{sub 2} antireflective coating (ARC). The changes in the electrical characteristics, capacitance-voltage characteristics and spectral response after gamma irradiation are systematically studied to estimate the radiation tolerance up to 10 Mrad. The different characteristics studied in this investigation demonstrate that Si PIN photodiodes are suitable for high radiation environment.

  13. AGM1+ spleen cells contain gamma interferon (IFN-gamma) gene transcripts in the early, sex-dependent production of IFN-gamma after picornavirus infection.

    PubMed Central

    McFarland, H I; Bigley, N J

    1990-01-01

    Encephalomyocarditis D variant (EMCV-D)-infected spleen cell cultures prepared from diabetes-resistant ICR Swiss female mice produce more gamma interferon (IFN-gamma) activity over a 24-h period than do spleen cell cultures from diabetes-susceptible male mice of this strain. Pretreatment of mice with anti-asialo GM1 eliminates early in vitro IFN-gamma production from 4 to 16 h postinfection (p.i.) and reduces IFN-gamma production from 16 to 24 h p.i. In this study, depletion of spleen cells with anti-Thy-1 by panning greatly reduced IFN-gamma activity in EMCV-D-infected spleen cell cultures throughout a 24-h period. Populations of asialo GM1 (AGM1), L3T4, and Lyt-2-positive cells were isolated from cells harvested at 9 h p.i. from EMCV-D-infected spleen cell cultures by a modified panning technique on polystyrene microscope slides. By in situ hybridization with a [35S]dATP-labeled IFN-gamma cDNA probe, only the AGM1-bearing cells were found to contain detectable IFN-gamma gene transcripts. An AGM1+, Thy-1+ natural killer-like cell is the probable producer of the early, sex-dependent IFN-gamma activity in this system. Images PMID:1974653

  14. Interaction of deep impurities with radiation defects in n-Si at gamma-irradiation

    NASA Astrophysics Data System (ADS)

    Makhkamov, S.; Karimov, M.; Khakimov, Z. M.; Odilova, N. D.; Makhmudov, S. A.; Kurbanov, A. O.; Begmatov, K. A.

    2005-08-01

    This work presents the results of research on peculiarities of radiation defect formation in single crystal n-Si, doped by deep level impurities (Cu, Ni, Ir, Rh, Pt and Au), at irradiation by gamma-quanta of 60 Co. A property of gamma-irradiation to create only vacancies and self-interstitial atoms is used to understand the nature of deep levels with participation of these impurities and primary elemental radiation defects. The role of covalence radii and diffusion coefficients in efficiency of radiation defect formation is discussed.

  15. Reflectivity of linear and nonlinear gamma radiated apodized chirped Bragg grating under ocean

    SciTech Connect

    Hamdalla, Taymour A.

    2012-09-06

    In this paper, the effect Co{sup 60} gamma radiation is investigated on the effective refractive index of apodized chirped Bragg grating. Nine apodization profiles are considered. Comparison between the reflectivity of the gamma radiated and non radiated fiber Bragg grating has been carried out. The electric field of signals propagating through the apodized chirped fiber Bragg grating (ACFBG) is first calculated from which, new values for the refractive index are determined. The nonlinear effects appear on the ACFBG reflectivity. The effect of nonlinearity and undersea temperature and pressure on the grating is also studied.

  16. Recent results on celestial gamma radiation from SMM

    NASA Technical Reports Server (NTRS)

    Share, Gerald H.

    1991-01-01

    Observations made by the Gamma Ray Spectrometer on board the SMM are described. Recent results reported include observations and analyses of gamma-ray lines from Co-56 produced in supernovae, observations of the temporal variation of the 511 keV line observed during Galactic center transits, and measurements of the diffuse Galactic spectrum from 0.3 to 8.5 MeV. The work in progress includes measurements of the distribution of Galactic Al-26, observations to place limits on Galactic Ti-44 and Fe-60 and on Be-7 produced in novae, and searches for a characteristic gamma-ray emission from pair plasmas, a 2.223 MeV line emission, limits on deexcitation lines from interstellar C and O, and gamma-ray bursts.

  17. Evaluation of the Combined Effects of Gamma Radiation and High Dietary Iron on Peripheral Leukocyte Distribution and Function

    NASA Technical Reports Server (NTRS)

    Crucian, Brian E.; Morgan, Jennifer L. L.; Quiriarte, Heather A.; Sams, Clarence F.; Smith, Scott M.; Zwart, Sara R.

    2011-01-01

    NASA is concerned with the health risks to astronauts, particularly those risks related to radiation exposure. Both radiation and increased iron stores can independently increase oxidative damage, resulting in protein, lipid and DNA oxidation. Oxidative stress increases the risk of many health problems including cancer, cataracts, and heart disease. This study, a subset of a larger interdisciplinary investigation of the combined effect of iron overload on sensitivity to radiation injury, monitored immune parameters in the peripheral blood of rats subjected to gamma radiation, high dietary iron or both. Specific immune measures consisted of (A) peripheral leukocyte distribution; (B) plasma cytokine levels; (C) cytokine production profiles following whole blood stimulation of either T cells or monocytes.

  18. SMM detection of interstellar Al-26 gamma radiation

    NASA Technical Reports Server (NTRS)

    Share, G. H.; Kinzer, R. L.; Chupp, E. L.; Forrest, D. J.; Rieger, E.

    1985-01-01

    The gamma ray spectrometer on the Solar Maximum Mission Satellite has detected the interstellar Al-26 line when the Galactic center traversed its aperture. The center of the emission is consistent with the location of the Galactic center, but the spatial distribution is presently not well defined. The total flux in the direction of the Galactic center is 4.3 + or - 0.4) x .0001 gamma/sq cm-s-rad for an assumed population I distribution.

  19. Different patterns of allelic imbalance in sporadic tumors and tumors associated with long-term exposure to gamma-radiation.

    PubMed

    Litviakov, Nikolai V; Freidin, Maxim B; Sazonov, Aleksey E; Khalyuzova, Maria V; Buldakov, Mikhail A; Karbyshev, Mikhail S; Albakh, Еlena N; Isubakova, Daria S; Gagarin, Аleksey A; Nekrasov, Gennadiy B; Mironova, Elena B; Izosimov, Аndrey S; Takhauov, Ravil M; Karpov, Аndrei B

    2015-12-01

    The study aimed to reveal cancer related mutations in DNA repair and cell cycle genes associated with chronic occupational exposure to gamma-radiation in personnel of the Siberian Group of Chemical Enterprises (SGCE). Mutations were analyzed by comparing genotypes of malignant tumors and matched normal tissues of 255 cancer patients including 98 exposed to external gamma-radiation (mean dose 128.1±150.5mSv). Also a genetic association analysis was carried out in a sample of 149 cancer patients and 908 healthy controls occupationally exposed to gamma-radiation (153.2±204.6mSv and 150.5±211.2mSv, respectively). Eight SNPs of genes of DNA excision repair were genotyped (rs13181, rs1052133, rs1042522, rs2305427, rs4244285, rs1045642, rs1805419 and rs1801133). The mutation profiles in heterozygous loci for selected SNP were different between sporadic tumors and tumors in patients exposed to radiation. In sporadic tumors, heterozygous genotype Arg/Pro of the rs1042522 SNP mutated into Arg/0 in 15 cases (9.6%) and 0/Pro in 14 cases (8.9%). The genotype Lys/Gln of the rs13181 SNP mutated into Lys/0 and 0/Gln in 9 and 4 cases, respectively. In tumors of patients exposed to low-level radiation, the rs1042522 Arg/0 mutated genotype was found in 12 cases (12.1%), while in 2 cases (2%) 0/Pro mutation was observed. Finally, the rs13181 0/Gln mutated genotype was observed in 15 cases (16,5%) . Thus, our study showed the difference in patterns of allelic imbalance in tumors appeared under low-level radiation exposure and spontaneous tumors for selected SNPs. This suggests different mechanisms of inactivation of heterozygous genotypes in sporadic and radiation-induced tumors. PMID:26653978

  20. Snowpack snow water equivalent measurement using the attenuation of cosmic gamma radiation

    SciTech Connect

    Osterhuber, R.; Fehrke, F.; Condreva, K.

    1998-05-01

    Incoming, background cosmic radiation constantly fluxes through the earth`s atmosphere. The high energy gamma portion of this radiation penetrates many terrestrial objects, including the winter snowpack. The attenuation of this radiation is exponentially related to the mass of the medium through which it penetrates. For the past three winters, a device measuring cosmic gamma radiation--and its attenuation through snow--has been installed at the Central Sierra Snow Laboratory, near Donner Pass, California. This gamma sensor, measuring energy levels between 5 and 15 MeV, has proved to be an accurate, reliable, non-invasive, non-mechanical instrument with which to measure the total snow water equivalent of a snowpack. This paper analyzes three winters` worth of data and discusses the physics and practical application of the sensor for the collection of snow water equivalent data from a remote location.

  1. Galactic plane gamma radiation. [SAS-2 and COS-b observations

    NASA Technical Reports Server (NTRS)

    Hartman, R. C.; Kniffen, D. A.; Thompson, D. J.; Fichtel, C. E.; Ogelman, H. B.; Tuner, T.; Ozel, M. E.

    1978-01-01

    Analysis of the complete data from SAS-2 accentuates the fact that the distribution of galactic gamma radiation has several similarities to that of other large-scale tracers of galactic structure. The gamma radiation shows no statistically significant variation with direction, and the spectrum seen along the plane is the same as that derived for the galactic component of the gamma radiation at high latitude. This uniformity of the energy spectrum, the smooth decrease in intensity as a function of galactic latitude, and the absence of any galactic gamma ray sources at high latitudes argue in favor of a diffuse origin for most of the galactic gamma radiation, rather than a collection of localized sources. All the localized sources identified in the SAS 2 data are associated with known compact objects on the basis of observed periodicities, except gamma195+5 Excluding those SAS 2 sources observed by COS-B and two other excesses (CG 312-1 and CG333+0) visible in the SAS 2 data associated with tangential directions of spiral arms, thera are eight remaining new sources in the COS-B catalog.

  2. Radiation chemistry of salt-mine brines and hydrates. [Gamma radiation

    SciTech Connect

    Jenks, G.H.; Walton, J.R.; Bronstein, H.R.; Baes, C.F. Jr.

    1981-07-01

    Certain aspects of the radiation chemistry of NaCl-saturated MgCl/sub 2/ solutions and MgCl/sub 2/ hydrates at temperatures in the range of 30 to 180/sup 0/C were investigated through experiments. A principal objective was to establish the values for the yields of H/sub 2/ (G(H/sub 2/)) and accompanying oxidants in the gamma-ray radiolysis of concentrated brines that might occur in waste repositories in salt. We concluded that G(H/sub 2/) from gamma-irradiated brine solution into a simultaneously irradiated, deaerated atmosphere above the solution is between 0.48 and 0.49 over most of the range 30 to 143/sup 0/C. The yield is probably somewhat lower at the lower end of this range, averaging 0.44 at 30 to 45/sup 0/C. Changes in the relative amounts of MgCl/sub 2/ and NaCl in the NaCl-saturated solutions have negligible effects on the yield. The yield of O/sub 2/ into the same atmosphere averages 0.13, independent of the temperature and brine composition, showing that only about 50% of the radiolytic oxidant that was formed along with the H/sub 2/ was present as O/sub 2/. We did not identify the species that compose the remainder of the oxidant. We concluded that the yield of H/sub 2/ from a gamma-irradiated brine solution into a simultaneously irradiated atmosphere containing 5 to 8% air in He may be greater than the yield in deaerated systems by amounts ranging from 0% for temperatures of 73 to 85/sup 0/C, to about 30 and 40% for temperatures in the ranges 100 to 143/sup 0/C and 30 to 45/sup 0/C, respectively. We did not establish the mechanism whereby the air affected the yields of H/sub 2/ and O/sub 2/. The values found in this work for G(H/sub 2/) in deaerated systems are in approximate agreement with the value of 0.44 for the gamma-irradiation yield of H/sub 2/ in pure H/sub 2/O at room temperature. They are also in agreement with the values predicted by extrapolation from the findings of previous researchers for the value for G(H/sub 2/) in 2 M NaCl solutions at room temperature.

  3. Changes in the biological properties of an ordinary chernozem exposed to gamma radiation

    NASA Astrophysics Data System (ADS)

    Denisova, T. V.; Kazeev, K. Sh.; Kolesnikov, S. I.; Val'Kov, V. F.

    2007-09-01

    The dynamics of changes in the number of microorganisms and biochemical properties of an ordinary chernozem were studied in model experiments 3, 30, and 90 days after the soil was subjected to gamma radiation at doses of 0.12-2.0 Mrad. The microscopic fungi are the most radiosensitive soil microorganisms. In 90 days of incubation after the gamma radiation, the number of microorganisms remained lower than that in the control variant by 31-96% in accordance with the dose. The enzyme activity of the ordinary chernozem, as compared to that of the microorganisms, was more resistant to the gamma radiation. The integral index of the soil biological state (ISBSI) decreased by 20-63% upon the radiation depending on the dose applied. After 90 days, the ISBSI value was close to the control variant (doses of 0.1-0.5 Mrad), whereas, in the variants with high doses of radiation (1.0 and 2.0 Mrad), its values were 46 and 59% lower, respectively, than in the control. The rate of restoring of the biological properties was related to the dose of radiation: the less the dose, the quicker the rate of restoration of the biological properties of the ordinary chernozem. However, at the high levels of gamma radiation, some biological properties were not restored even after 90 days.

  4. Mutation inhibition by beta-estradiol after low doses of gamma-irradiation of mammalian cells.

    PubMed

    Puck, T T; Johnson, R; Webb, P

    1999-03-01

    The methodology previously described for measuring mutagenesis has been applied to the study of mutation prevention in immortalized G2 phase human lymphocytes exposed to 25 and 50 cGy of gamma-radiation. Caffeine prevents repair of mutations. Two times 10(-4) M beta-estradiol applied for 2.5 h markedly decreases induced mutations and affects male and female cells similarly. Quantitative measurement of mutagenesis in cells of different individuals and the effect of various agents on mutation yield should be important in prevention of cancer and other mutational disease. PMID:11225056

  5. Effect of proton and gamma irradiation on human lung carcinoma cells: Gene expression, cell cycle, cell death, epithelial-mesenchymal transition and cancer-stem cell trait as biological end points.

    PubMed

    Narang, Himanshi; Kumar, Amit; Bhat, Nagesh; Pandey, Badri N; Ghosh, Anu

    2015-10-01

    Proton beam therapy is a cutting edge modality over conventional gamma radiotherapy because of its physical dose deposition advantage. However, not much is known about its biological effects vis-a-vis gamma irradiation. Here we investigated the effect of proton- and gamma- irradiation on cell cycle, death, epithelial-mesenchymal transition (EMT) and "stemness" in human non-small cell lung carcinoma cells (A549). Proton beam (3MeV) was two times more cytotoxic than gamma radiation and induced higher and longer cell cycle arrest. At equivalent doses, numbers of genes responsive to proton irradiation were ten times higher than those responsive to gamma irradiation. At equitoxic doses, the proton-irradiated cells had reduced cell adhesion and migration ability as compared to the gamma-irradiated cells. It was also more effective in reducing population of Cancer Stem Cell (CSC) like cells as revealed by aldehyde dehydrogenase activity and surface phenotyping by CD44(+), a CSC marker. These results can have significant implications for proton therapy in the context of suppression of molecular and cellular processes that are fundamental to tumor expansion. PMID:26278043

  6. Evaluation of the sensitivity of the gas-discharge gamma-counters to the concomitant neutron radiation

    NASA Astrophysics Data System (ADS)

    Pikalov, G. L.; Kiseev, S. V.

    2015-11-01

    In the fields of gamma-neutron radiation the accuracy measurement of gamma- ray doses depends on their sensitivity to concomitant neutron radiation. In this connection, verification results of gamma-dosimetry on the installation with isotope cobalt or cesium sources are not always adequate to measurement results in real gamma-neutron fields. The data prove, that the sensitivity coefficients of gas-discharge gamma-dosimeters at PRIZ-M reactor is 1.23 larger as compared to Co60 source, due to the effect of the concomitant neutrons on their indications. The error due to the neutrons effect can be significantly reduced or eliminated completely, if gamma-dosimeters calibrated in the field of gamma-neutron radiation, adequate spectral and dose characteristics to radiation fields in which they are used.

  7. Lower Bound on the Cosmic TeV Gamma-Ray Background Radiation

    NASA Astrophysics Data System (ADS)

    Inoue, Yoshiyuki; Tanaka, Yasuyuki T.

    2016-02-01

    The Fermi gamma-ray space telescope has revolutionized our understanding of the cosmic gamma-ray background radiation in the GeV band. However, investigation on the cosmic TeV gamma-ray background radiation still remains sparse. Here, we report the lower bound on the cosmic TeV gamma-ray background spectrum placed by the cumulative flux of individual detected extragalactic TeV sources including blazars, radio galaxies, and starburst galaxies. The current limit on the cosmic TeV gamma-ray background above 0.1 TeV is obtained as 2.8 × 10-8(E/100 GeV)-0.55 exp(-E/2100GeV)[GeV cm-2 s-1 sr-1] < E2dN/dE < 1.1 × 10-7(E/100 GeV)-0.49 [GeV cm-2 s-1 sr-1], where the upper bound is set by requirement that the cascade flux from the cosmic TeV gamma-ray background radiation can not exceed the measured cosmic GeV gamma-ray background spectrum. Two nearby blazars, Mrk 421 and Mrk 501, explain ˜70% of the cumulative background flux at 0.8-4 TeV, while extreme blazars start to dominate at higher energies. We also provide the cumulative background flux from each population, i.e., blazars, radio galaxies, and starburst galaxies which will be the minimum requirement for their contribution to the cosmic TeV gamma-ray background radiation.

  8. Gamma radiation induced degradation in PE-PP block copolymer

    SciTech Connect

    Ravi, H. R.; Sreepad, H. R.; Ahmed, Khaleel; Govindaiah, T. N.

    2012-06-05

    In the present investigation, effect of gamma irradiation on the PP-PE block copolymer has been studied. The polymer has been subjected to gamma irradiation from 100 to 500 Mrad dosages. Characterization of the polymer using XRD and FTIR was done both before irradiation and after irradiation in each step. Effect of irradiation on the electrical properties of the material has also been studied. FTIR study shows that the sample loses C - C stretching mode of vibration but gains C=C stretching mode of vibration after irradiation. Present investigation clearly indicates that though the electrical conductivity increases in the material, it undergoes degradation and shows brittleness due to irradiation.

  9. Mutagenesis and repair by low doses of alpha radiation in mammalian cells.

    PubMed

    Puck, Theodore T; Johnson, Robert; Webb, Patricia; Cui, Helen; Valdez, Joseph G; Crissman, Harry

    2002-09-17

    Low doses of alpha radiation in basements have been causally implicated in lung cancer. Previous studies have concentrated on high dose effects, for which no significant repair was found. In the present study, the methodology for measuring mutation by quantitating mitotic breaks and gaps was found to be applicable to G2-phase Chinese hamster ovary cells irradiated with 10-50 cGy of alpha radiation. The mutation yield in such cells closely resembles that of gamma irradiation. Caffeine, which inhibits repair, produces the same straight line increase of alpha and gamma mutation yields plotted against the dose. In the absence of caffeine, the repair of alpha radiation lesions is almost twice as great as for gamma radiation. Mitotic index changes substantiate these interpretations. It is proposed that the higher ion density associated with alpha radiation may result in fewer lesions being missed by the repair processes. The quantitation of chromosomal lesions for G2 cells exposed to low doses of alpha radiation, gamma radiation, or chemical mutagens in the presence and absence of caffeine is a rapid and reproducible methodology. Protection from mutational disease in a fashion similar to the use of sanitation for infectious disease appears practical. PMID:12198179

  10. Slow elimination of phosphorylated histone {gamma}-H2AX from DNA of terminally differentiated mouse heart cells in situ

    SciTech Connect

    Gavrilov, Boris; Vezhenkova, Irina; Firsanov, Denis; Solovjeva, Liudmila; Svetlova, Maria; Mikhailov, Vyacheslav; Tomilin, Nikolai . E-mail: nvtom@hotmail.com

    2006-09-08

    Phosphorylation of replacement histone H2AX occurs in megabase chromatin domains around double-strand DNA breaks (DSBs) and this modification (called {gamma}-H2AX) may serve as a useful marker of genome damage and repair in terminally differentiated cells. Here using immunohistochemistry we studied kinetics of {gamma}-H2AX formation and elimination in the X-irradiated mouse heart and renal epithelial tissues in situ. Unirradiated tissues have 3-5% {gamma}-H2AX-positive cells and in tissues fixed 1 h after X-irradiation {gamma}-H2AX-positive nuclei are induced in a dose-dependent manner approaching 20-30% after 3 Gy of IR. Analysis of mouse tissues at different times after 3 Gy of IR showed that maximal induction of {gamma}-H2AX in heart is observed 20 min after IR and then is decreased slowly with about half remaining 23 h later. In renal epithelium maximum of the {gamma}-H2AX-positive cells is observed 40 min after IR and then decreases to control values in 23 h. This indicates that there are significant variations between non-proliferating mammalian tissues in the initial H2AX phosphorylation rate as well as in the rate of {gamma}-H2AX elimination after X-irradiation, which should be taken into account in the analysis of radiation responses.

  11. Peroxisome proliferator-activated receptor gamma overexpression suppresses proliferation of human colon cancer cells

    SciTech Connect

    Tsukahara, Tamotsu; Haniu, Hisao

    2012-08-03

    Highlights: Black-Right-Pointing-Pointer We examined the correlation between PPAR{gamma} expression and cell proliferation. Black-Right-Pointing-Pointer PPAR{gamma} overexpression reduces cell viability. Black-Right-Pointing-Pointer We show the synergistic effect of cell growth inhibition by a PPAR{gamma} agonist. -- Abstract: Peroxisome proliferator-activated receptor gamma (PPAR{gamma}) plays an important role in the differentiation of intestinal cells and tissues. Our previous reports indicate that PPAR{gamma} is expressed at considerable levels in human colon cancer cells. This suggests that PPAR{gamma} expression may be an important factor for cell growth regulation in colon cancer. In this study, we investigated PPAR{gamma} expression in 4 human colon cancer cell lines, HT-29, LOVO, DLD-1, and Caco-2. Real-time polymerase chain reaction (PCR) and Western blot analysis revealed that the relative levels of PPAR{gamma} mRNA and protein in these cells were in the order HT-29 > LOVO > Caco-2 > DLD-1. We also found that PPAR{gamma} overexpression promoted cell growth inhibition in PPAR{gamma} lower-expressing cell lines (Caco-2 and DLD-1), but not in higher-expressing cells (HT-29 and LOVO). We observed a correlation between the level of PPAR{gamma} expression and the cells' sensitivity for proliferation.

  12. Gamma radiation exposure of accompanying persons due to Lu-177 patients

    NASA Astrophysics Data System (ADS)

    Kovan, Bilal; Demir, Bayram; Tuncman, Duygu; Capali, Veli; Turkmen, Cuneyt

    2015-07-01

    Neuroendocrine tumours (NET) are cancers usually observed and arisen in the stomach, intestine, pancreas and breathing system. Recently, radionuclide therapy applications with Lu-177 peptide compound are rapidly growing; especially effective clinical results are obtained in the treatment of well-differentiated and metastatic NET. In this treatment, Lu-177-DOTA, a beta emitter radioisotope in the radiopharmaceutical form, is given to the patient by intravenous way. Lu-177 has also gamma rays apart from beta rays. Gamma rays have 175 keV average energy and these gamma rays should be under the control in terms of radiation protection. In this study, we measured the exposure dose from the Lu-177 patient.

  13. Gamma-radiation induced changes in the physical and chemical properties of lignocellulose.

    PubMed

    Khan, Ferdous; Ahmad, S R; Kronfli, E

    2006-08-01

    gamma-radiation induced effects on the physical and chemical properties of natural lignocellulose (jute) polymer were investigated. Samples were irradiated to required total doses at a particular dose rate. The changes in the parameters such as the tensile strength, elongation at break, and work done at rupture for the lignocellulose samples on irradiation with the gamma-rays from a cobalt-60 source were measured. The mechanical properties were found to have nonlinear relations with the radiation doses. The chemical stability of irradiated fibers was found to degrade progressively with the increase of radiation dose. Additionally, other chemical changes of the samples due to exposure to high-energy radiation were also investigated using fluorescence and infrared spectroscopic analysis. Differential scanning calorimetry and thermogravimetric studies showed a significant reduction in thermal stability. The wide-angle X-ray diffraction study showed that structural changes of cellulose appeared due to the radiation-induced chemical reaction of lignocellulose. PMID:16903675

  14. Secondary production of neutral pi-mesons and the diffuse galactic gamma radiation

    NASA Technical Reports Server (NTRS)

    Dermer, C. D.

    1986-01-01

    Isobaric and scaling model predictions of the secondary spectra of neutral pi-mesons produced in proton-proton collisions, at energies between threshold and a few GeV, are compared on the basis of accelerator data and found to show the isobaric model to be superior. This model is accordingly used, in conjuction with a scaling model representation at high energies, in a recalculation of the pi exp (0) gamma-radiation's contribution to the diffuse galactic gamma background; the cosmic ray-induced production of photons (whose energy exceeds 100 MeV) by such radiation occurs at a rate of 1.53 x 10 to the -25 photons/(s-H atom). These results are compared with previous calculations of this process as well as with COS-B observations of the diffuse galactic gamma-radiation.

  15. Multiple fractions of gamma rays induced resistance to cis-dichloro-diammineplatinum (II) and methotrexate in human HeLa cells

    SciTech Connect

    Osmak, M.; Perovic, S. )

    1989-06-01

    Previous irradiation could induce changes in the cell-sensitivity to additional cytotoxic agents. In this study we examined whether the sensitivity to additional cytotoxic agents was affected in cells irradiated with multiple fractions of gamma rays if these agents were given at the time when the lesions induced in DNA by radiation have already been repaired. Human cervix carcinoma HeLa cells were irradiated daily with 0.5 Gy of gamma rays five times a week for 6 weeks. When the fractionation regimen was completed, that is when the cells had accumulated the total dose of 15 Gy of gamma rays, the sensitivity of these cells to gamma rays, UV light, cis-dichlorodiammineplatinum (II) (cis-DDP), methotrexate (MTX), and hydroxyurea (HU) was examined and compared to control cells. Results revealed that preirradiated cells did not change sensitivity to gamma rays and UV light, but that they increased the resistance to cis-DDP, and MTX (especially for higher concentrations of MTX), and increased sensitivity to HU (for lower concentrations of HU). The increased resistance to cis-DDP was also measurable up to 30 days after the last dose of gamma rays. The results indicate that preirradiation of HeLa cells with multiple fractions of gamma rays could change their sensitivity to additional cytotoxic agents, and that this is a relatively long-lasting effect. Our results suggest that caution is needed in medical application of radiation combined with chemical treatment.

  16. (Gamma scattering in condensed matter with high intensity Moessbauer radiation)

    SciTech Connect

    Not Available

    1992-01-01

    This report discusses: quasielastic scattering studies on glycerol; gamma-ray scattering from alkali halides; lattice dynamics in metals; Moessbauer neutron scattering, x-ray diffraction, and macroscopic studies of high {Tc} superconductors containing tungsten; NiAl scattering studies; and atomic interference factors and nuclear Casimir effect.

  17. Interferon-gamma inhibits cell cycle exit in differentiating oligodendrocyte progenitor cells.

    PubMed

    Chew, Li-Jin; King, William C; Kennedy, Ann; Gallo, Vittorio

    2005-11-01

    The developmental processes of the oligodendrocyte progenitor cell (OPC) lineage that are targeted by interferon-gamma (IFN-gamma) were studied in primary rat OPC cultures. Under conditions of thyroid hormone-mediated oligodendrocyte differentiation, IFN-gamma produced a dose-dependent apoptotic response in OPCs. The lowest dose tested (15 ng/ml or 75 U/ml) was nonapoptotic, but activated detectable STAT1 DNA-binding. At this dose, IFN-gamma reduced the percentage of mature O1+ cells and increased the percentage of immature A2B5+ OPCs. This was observed without significant change in total cell number and cytotoxicity, and was accompanied by an increase in BrdU-labeled A2B5+ and O4+ cells. FACS analysis confirmed a lack of apoptotic sub-G1 cells and revealed a greater percentage of S- and G2/M-phase OPCs with IFN-gamma treatment. Dual immunostaining with Ki-67 and Olig2 showed a smaller percentage of Olig2+ cells in G0 phase in IFN-gamma-treated OPCs, indicating loss of G1 control. Instead, increased levels and phosphorylation of the checkpoint protein p34cdc2 by IFN- suggested increased partial arrest in G2. IFN-gamma not only sustained expression of PCNA and the G1-S regulators retinoblastoma protein, cyclin D1, cyclin E, and cdk2, but also decreased p27 levels. In addition to changes in cell proliferation and differentiation, IFN-gamma attenuated myelin basic protein (MBP) expression significantly, which was associated with decreased expression of both MBP and Sox10 RNAs. These findings indicate that IFN-gamma not only maintains cell cycle activity that could predispose OPCs to apoptosis, but also overrides G1-G0 signals leading to thyroid hormone-mediated terminal differentiation and myelin gene expression. PMID:15920731

  18. Response of thyroid follicular cells to gamma irradiation compared to proton irradiation. I. Initial characterization of DNA damage, micronucleus formation, apoptosis, cell survival, and cell cycle phase redistribution

    NASA Technical Reports Server (NTRS)

    Green, L. M.; Murray, D. K.; Bant, A. M.; Kazarians, G.; Moyers, M. F.; Nelson, G. A.; Tran, D. T.

    2001-01-01

    The RBE of protons has been assumed to be equivalent to that of photons. The objective of this study was to determine whether radiation-induced DNA and chromosome damage, apoptosis, cell killing and cell cycling in organized epithelial cells was influenced by radiation quality. Thyroid-stimulating hormone-dependent Fischer rat thyroid cells, established as follicles, were exposed to gamma rays or proton beams delivered acutely over a range of physical doses. Gamma-irradiated cells were able to repair DNA damage relatively rapidly so that by 1 h postirradiation they had approximately 20% fewer exposed 3' ends than their counterparts that had been irradiated with proton beams. The persistence of free ends of DNA in the samples irradiated with the proton beam implies that either more initial breaks or a quantitatively different type of damage had occurred. These results were further supported by an increased frequency of chromosomal damage as measured by the presence of micronuclei. Proton-beam irradiation induced micronuclei at a rate of 2.4% per gray, which at 12 Gy translated to 40% more micronuclei than in comparable gamma-irradiated cultures. The higher rate of micronucleus formation and the presence of larger micronuclei in proton-irradiated cells was further evidence that a qualitatively more severe class of damage had been induced than was induced by gamma rays. Differences in the type of damage produced were detected in the apoptosis assay, wherein a significant lag in the induction of apoptosis occurred after gamma irradiation that did not occur with protons. The more immediate expression of apoptotic cells in the cultures irradiated with the proton beam suggests that the damage inflicted was more severe. Alternatively, the cell cycle checkpoint mechanisms required for recovery from such damage might not have been invoked. Differences based on radiation quality were also evident in the alpha components of cell survival curves (0.05 Gy(-1) for gamma rays, 0.12 Gy(-1) for protons), which suggests that the higher level of survival of gamma-irradiated cells could be attributed to the persistence of nonlethally irradiated thyrocytes and/or the capacity to repair damage more effectively than cells exposed to equal physical doses of protons. The final assessment in this study was radiation-induced cell cycle phase redistribution. Gamma rays and protons produced a similar dose-dependent redistribution toward a predominantly G(2)-phase population. From our cumulative results, it seems likely that a majority of the proton-irradiated cells would not continue to divide. In conclusion, these findings suggest that there are quantitative and qualitative differences in the biological effects of proton beams and gamma rays. These differences could be due to structured energy deposition from the tracks of primary protons and the associated high-LET secondary particles produced in the targets. The results suggest that a simple dose-equivalent approach to dosimetry may be inadequate to compare the biological responses of cells to photons and protons.

  19. Observed Gamma Ray Radiation Variations Associated with Tropical Zone Rainfall Events

    NASA Astrophysics Data System (ADS)

    Spjeldvik, W. N.; Martin, I. M.; Gusev, A. A.

    2014-12-01

    Major liquid precipitation events are associated with changes in measurable natural nuclear radiation at ground level. We have observed that gamma radiation from airborne constituents varies with weather conditions, especially rainfall events, as observed with ground level instrumentation at near tropical zone low latitudes. Simultaneous observations of natural gamma ray emissions at the ground level and tropical zone rainfall variation observations have been performed in Sao Jose dos Campos, Sao Paulo, Brazil with temporal resolution accuracy of the order of one minute. This has allowed a detailed comparison of rainfall amounts and monitored gamma ray emission time profiles to estimate the actual radionuclide concentration in the rainwater. The radionuclide fallout time profiles were numerically simulated from the observed gamma rate through a numerical minimization procedure. The radionuclide concentration was calculated as a ratio of the simulated fallout to that of the observed rainfall amounts. Our result shows an anti-correlation between the average values of these parameters at times. The effect is especially pronounced at rapid rainfall onsets. The results obtained are compared with the current models and data, and the causes are discussed. Future research will study gamma ray radiation versus weather events at ground level in the temporal zone (North America) where the natural background radiation is thought to be generally somewhat lower than at ground level on the South American continent.

  20. Unraveling low-level gamma radiation--responsive changes in expression of early and late genes in leaves of rice seedlings at Iitate Village, Fukushima.

    PubMed

    Hayashi, Gohei; Shibato, Junko; Imanaka, Tetsuji; Cho, Kyoungwon; Kubo, Akihiro; Kikuchi, Shoshi; Satoh, Kouji; Kimura, Shinzo; Ozawa, Shoji; Fukutani, Satoshi; Endo, Satoru; Ichikawa, Katsuki; Agrawal, Ganesh Kumar; Shioda, Seiji; Fukumoto, Manabu; Rakwal, Randeep

    2014-01-01

    In the summer of 2012, 1 year after the nuclear accident in March 2011 at the Fukushima Daiichi nuclear power plant, we examined the effects of gamma radiation on rice at a highly contaminated field of Iitate village in Fukushima, Japan. We investigated the morphological and molecular changes on healthy rice seedlings exposed to continuous low-dose gamma radiation up to 4 µSv h(-1), about 80 times higher than natural background level. After exposure to gamma rays, expression profiles of selected genes involved in DNA replication/repair, oxidative stress, photosynthesis, and defense/stress functions were examined by RT-PCR, which revealed their differential expression in leaves in a time-dependent manner over 3 days (6, 12, 24, 48, and 72 h). For example, OsPCNA mRNA rapidly increased at 6, 12, and 24 h, suggesting that rice cells responded to radiation stress by activating a gene involved in DNA repair mechanisms. At 72 h, genes related to the phenylpropanoid pathway (OsPAL2) and cell death (OsPR1oa) were strongly induced, indicating activation of defense/stress responses. We next profiled the transcriptome using a customized rice whole-genome 4×44K DNA microarray at early (6h) and late (72 h) time periods. Low-level gamma radiation differentially regulated rice leaf gene expression (induced 4481 and suppressed 3740 at 6 h and induced 2291 and suppressed 1474 genes at 72 h) by at least 2-fold. Using the highly upregulated and downregulated gene list, MapMan bioinformatics tool generated diagrams of early and late pathways operating in cells responding to gamma ray exposure. An inventory of a large number of gamma radiation-responsive genes provides new information on novel regulatory processes in rice. PMID:25124817

  1. Effective gamma-ray doses due to natural radiation from soils of southeastern Brazil

    SciTech Connect

    Silveira, M. A. G.; Moreira, R. H.; Bellini, B. S.; Medina, N. H.; Aguiar, V. A. P.

    2010-08-04

    We have used gamma-ray spectrometry to study the distribution of natural radiation from soils of southeastern Brazil: Billings reservoir, Sao Bernardo do Campo Parks, Diadema Parks, Interlagos region, Sao Paulo, and soil from Sao Paulo and Rio de Janeiro beaches. In most of the regions studied we have found that the dose due the external exposure to gamma-rays, proceeding from natural terrestrial elements, are between the values 0.3 and 0.6 mSv/year, established by the United Nations Scientific Committee on the Effects of Atomic Radiation.

  2. Gadolinium-doped water cerenkov-based neutron and high energy gamma-ray detector and radiation portal monitoring system

    DOEpatents

    Dazeley, Steven A; Svoboda, Robert C; Bernstein, Adam; Bowden, Nathaniel

    2013-02-12

    A water Cerenkov-based neutron and high energy gamma ray detector and radiation portal monitoring system using water doped with a Gadolinium (Gd)-based compound as the Cerenkov radiator. An optically opaque enclosure is provided surrounding a detection chamber filled with the Cerenkov radiator, and photomultipliers are optically connected to the detect Cerenkov radiation generated by the Cerenkov radiator from incident high energy gamma rays or gamma rays induced by neutron capture on the Gd of incident neutrons from a fission source. The PMT signals are then used to determine time correlations indicative of neutron multiplicity events characteristic of a fission source.

  3. Gamma evaluation combined with isocenter optimal matching in intensity modulated radiation therapy quality assurance

    NASA Astrophysics Data System (ADS)

    Bak, Jino; Choi, Jin Hwa; Park, Suk Won; Park, Kwangwoo; Park, Sungho

    2015-12-01

    Two-dimensional (2D) dose comparisons are widely performed by using a gamma evaluation with patient-specific intensity modulated radiation therapy quality assurance (IMRT QA) or dose delivery quality assurance (DQA). In this way, a pass/fail determination is made for a particular treatment plan. When gamma evaluation results are close to the failure criterion, the pass/fail decision may change applying a small shift to the center of the 2D dose distribution. In this study, we quantitatively evaluated the meaning of such a small relative shift in a 2D dose distribution comparison. In addition, we propose the use of a small shift for a pass/fail criterion in gamma analysis, where the concept of isocenter optimal matching (IOM) is applied to IMRT QA of 20 patients. Gamma evaluations were performed to compare two dose distributions, one with and the other without IOM. In-house software was developed in C++ in order to find IOM values including both translational and rotational shifts. Upon gamma evaluation failure, further investigation was initiated using IOM. In this way, three groups were categorized: group 1 for `pass' on gamma evaluation, group 21 for `fail' on the gamma evaluation and `pass' on the gamma the evaluation with IOM, and group 22 for `fail' on the both gamma evaluations and the IOM calculation. IOM results revealed that some failures could be considered as a `pass'. In group 21, 88.98% (fail) of the averaged gamma pass rate changed to 90.45% (pass) when IOM was applied. On average, a ratio of γ ≥ 1 was reduced by 11.06% in 20 patients. We propose that gamma evaluations that do not pass with a rate of 85% to 90% may be augmented with IOM to reveal a potential pass result.

  4. Measurement of gamma and neutron radiations inside spent fuel assemblies with passive detectors

    NASA Astrophysics Data System (ADS)

    Viererbl, L.; Lahodová, Z.; Voljanskij, A.; Klupák, V.; Koleška, M.; Cabalka, M.; Turek, K.

    2011-10-01

    During operation of a fission nuclear reactor, many radionuclides are generated in fuel by fission and activation of 235U, 238U and other nuclides present in the assembly. After removal of a fuel assembly from the core, these radionuclides are sources of different types of radiation. Gamma and neutron radiation emitted from an assembly can be non-destructively detected with different types of detectors. In this paper, a new method of measurement of radiation from a spent fuel assembly is presented. It is based on usage of passive detectors, such as alanine dosimeters for gamma radiation and track detectors for neutron radiation. Measurements are made on the IRT-2M spent fuel assemblies used in the LVR-15 research reactor. During irradiation of detectors, the fuel assembly is located in a water storage pool at a depth of 6 m. Detectors are inserted into central hole of the assembly, irradiated for a defined time interval, and after the detectors removed from the assembly, gamma dose or neutron fluence are evaluated. Measured profiles of gamma dose rate and neutron fluence rate inside of the spent fuel assembly are presented. This measurement can be used to evaluate relative fuel burn-up.

  5. A biotechnological project with a gamma radiation source of 100,000 Ci

    NASA Astrophysics Data System (ADS)

    Lombardo, J. H.; Smolko, E. E.

    A project for the production of radiovaccines and other bio-medical products is presented which includes a radiation facility provided with a gamma ray source equivalent to 100,000 Ci of Co-60. The whole process incorporates novel basic features in virus production and inactivation steps. The former is carried out in animals previously subjected to immunodepression through electromagnetic radiation. The later is obtained at low temperatures by using either electromagnetic or particle radiations. A vaccine manufacture process is shown to illustrate the utilization of ionizing radiations to obtain a foot and mouth disease virus (FMDV) vaccine with good antigenic quality and low cost.

  6. Gamma radiation and photospheric white-light flare continuum

    NASA Technical Reports Server (NTRS)

    Hudson, H. S.; Dwivedi, B. N.

    1982-01-01

    It is noted that recent gamma-ray observations of solar flares have provided a better means for estimating the heating of the solar atmosphere by energetic protons. This type of heating has been suggested as the explanation of the continuum emission of the white-light flare. The effects on the photosphere of high-energy particles capable of producing the intense gamma-ray emission observed in the flare of July 11, 1978, are analyzed. A simple energy-balance argument is used, and hydrogen ionization is taken into account. It is found that energy deposition increases with height for the inferred proton spectra and is not strongly dependent upon the assumed angle of incidence. At the top of the photosphere, the computed energy inputs fall in the range 10-100 ergs/cu cm-s.

  7. Microwave and gamma radiation observations of soil moisture

    NASA Technical Reports Server (NTRS)

    Schmugge, T. J.; Njoku, E. G.; Peck, E.; Ulaby, F. T.

    1979-01-01

    The unique dielectric properties of water at microwave wavelengths afford the possibility for remotely sensing the moisture content in the surface layer of the soil. The surface emissivity and reflectivity for the soils at these wavelengths are strong functions of its moisture content. The changes in emissivity can be observed by passive microwave techniques (radiometry) and the change in reflectivity can be observed by active microwave techniques (radar). The difference in the natural terrestrial gamma ray flux measured for wet and dry soil may be used to determine soil moisture. The presence of water moisture in the soil causes an effective increase in soil density, resulting in an increased attenuation of the gamma flux for wet soil and a corresponding lower flux above the ground surface.

  8. Radiation detection system for portable gamma-ray spectroscopy

    DOEpatents

    Rowland, Mark S.; Howard, Douglas E.; Wong, James L.; Jessup, James L.; Bianchini, Greg M.; Miller, Wayne O.

    2006-06-20

    A portable gamma ray detection apparatus having a gamma ray detector encapsulated by a compact isolation structure having at least two volumetrically-nested enclosures where at least one is a thermal shield. The enclosures are suspension-mounted to each other to successively encapsulate the detector without structural penetrations through the thermal shields. A low power cooler is also provided capable of cooling the detector to cryogenic temperatures without consuming cryogens, due to the heat load reduction by the isolation structure and the reduction in the power requirements of the cooler. The apparatus also includes a lightweight portable power source for supplying power to the apparatus, including to the cooler and the processing means, and reducing the weight of the apparatus to enable handheld operation or toting on a user's person.

  9. High-energy gamma radiation from extragalactic radio sources

    NASA Technical Reports Server (NTRS)

    Dermer, C. D.; Schlickeiser, R.; Mastichiadis, A.

    1992-01-01

    We propose that the important relationship between 3C 273 and 3C 279, the first two extragalactic sources detected at over 100 MeV energies, is their superluminal nature. In support of this conjecture, we propose a kinematic focusing mechanism, based on Compton scattering of accretion-disk photons by relativistic nonthermal electrons in the jet, that preferentially emits gamma rays in the superluminal direction.

  10. Energetic Gamma Radiation from Rapidly Rotating Black Holes

    NASA Astrophysics Data System (ADS)

    Hirotani, Kouichi; Pu, Hung-Yi

    2016-02-01

    Supermassive black holes (BHs) are believed to be the central powerhouse of active galactic nuclei. Applying the pulsar outer-magnetospheric particle accelerator theory to BH magnetospheres, we demonstrate that an electric field is exerted along the magnetic field lines near the event horizon of a rotating BH. In this particle accelerator (or a gap), electrons and positrons are created by photon-photon collisions and accelerated in the opposite directions by this electric field, efficiently emitting gamma-rays via curvature and inverse-Compton processes. It is shown that a gap arises around the null-charge surface formed by the frame-dragging effect, provided that there is no current injection across the gap boundaries. The gap is dissipating a part of the hole’s rotational energy, and the resultant gamma-ray luminosity increases with decreasing plasma accretion from the surroundings. Considering an extremely rotating supermassive BH, we show that such a gap reproduces the significant very-high-energy (VHE) gamma-ray flux observed from the radio galaxy IC 310, provided that the accretion rate becomes much less than the Eddington rate particularly during its flare phase. It is found that the curvature process dominates the inverse-Compton process in the magnetosphere of IC 310, and that the observed power-law-like spectrum in VHE gamma-rays can be explained to some extent by a superposition of the curvature emissions with varying curvature radius. It is predicted that the VHE spectrum extends into higher energies with increasing VHE photon flux.

  11. Heterogeneity in the radiation survival curves and biochemical properties of human lung cancer cell lines

    SciTech Connect

    Morstyn, G.; Russo, A.; Carney, D.N.; Karawya, E.; Wilson, S.H.; Mitchell, J.B.

    1984-10-01

    Human lung cancers of distinct histology exhibit different responses to radiation therapy in vivo. For examination of the basis of this phenomenon, the radiation survival curves and levels of relevant enzymes were determined in 16 lung cancer cell lines derived from tumors of different histology. These included lines from 5 adenocarcinomas, 7 small cell tumors, 3 variant small cell tumors, and 1 large cell tumor. These findings were compared to those obtained with the use of a normal skin fibroblast cell line. Whether cloned in liquid culture or soft agarose, cell lines had similar radiation survival curves. These curves were consistent with the apparent in vivo radiation responsiveness of the tumors. Although considerable heterogeneity in radiation survival curves was observed among the cell lines, cells from large cell lines and small variant lines had pronounced shoulders and extrapolation numbers (n) from 5.6 to 14. In contrast, cells from small cell lines and adenocarcinoma cell lines were more sensitive (-n values of 1-3.3). In these cell lines, levels of DNA polymerase beta, glutathione (GSH), GSH transferase, GSH reductase (NAD(P)H), gamma-glutamyltransferase did not correlate with radiation parameters of sensitivity. DNA polymerase beta and GSH levels were, however, higher than those in a line of normal skin fibroblasts. These cell lines may be useful in identifying the basis of the variable responsiveness of human lung cancer cells to ionizing radiation.

  12. GaAs Solar Cell Radiation Handbook

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.

    1996-01-01

    The handbook discusses the history of GaAs solar cell development, presents equations useful for working with GaAs solar cells, describes commonly used instrumentation techniques for assessing radiation effects in solar cells and fundamental processes occurring in solar cells exposed to ionizing radiation, and explains why radiation decreases the electrical performance of solar cells. Three basic elements required to perform solar array degradation calculations: degradation data for GaAs solar cells after irradiation with 1 MeV electrons at normal incidence; relative damage coefficients for omnidirectional electron and proton exposure; and the definition of the space radiation environment for the orbit of interest, are developed and used to perform a solar array degradation calculation.

  13. Enrichment of magnetic alignment stimulated by {gamma}-radiation in core-shell type nanoparticle Mn-Zn ferrite

    SciTech Connect

    Naik, P. P.; Tangsali, R. B.; Sonaye, B.; Sugur, S.

    2013-02-05

    Core shell type nanoparticle Mn{sub x}Zn{sub 1-x}Fe{sub 2}O{sub 4} systems with x=0.55, 0.65 and 0.75 were prepared using autocombustion method. The systems were characterized using tools like XRD and IR for structure confirmation. Magnetic parameter measurements like Saturation magnetization and coercivity were obtained from hysteresis loop which exhibited a symmetry shift due to core shell nature of the nanoparticles. Nanoparticles of particle size between 21.2nm to 25.7nm were found to show 20 percent shrinkage after being radiated by the {gamma}-radiation. This is due to variation in the cation distribution which also affects the cell volume of the cubic cell. Lattice constant reduction observed is reflected in the magnetic properties of the samples. A considerable hike in the saturation magnetization of the samples was observed due to enrichment of magnetic alignment in the magnetic core of the particles. Samples under investigation were irradiated with gamma radiation from Co{sup 60} source for different time intervals.

  14. Chromosomal aberrations in peripheral blood lymphocytes exposed to a mixed beam of low energy neutrons and gamma radiation.

    PubMed

    Wojcik, A; Obe, G; Lisowska, H; Czub, J; Nievaart, V; Moss, R; Huiskamp, R; Sauerwein, W

    2012-09-01

    Cells exposed to thermal neutrons are simultaneously damaged by radiations with high and low linear energy transfer (LET). A question relevant for the assessment of risk of exposure to a mixed beam is whether the biological effect of both radiation types is additive or synergistic. The aim of the present investigation was to calculate whether the high and low LET components of a thermal neutron field interact when damaging cells. Human peripheral blood lymphocytes were exposed to neutrons from the HB11 beam at the Institute for Energy and Transport, Petten, Netherlands, in a 37 °C water phantom at varying depths, where the mix of high and low LET beam components differs. Chromosomal aberrations were analysed and the relative biological effectiveness (RBE) values as well as the expected contributions of protons and photons to the aberration yield were calculated based on a dose response of aberrations in lymphocytes exposed to (60)Co gamma radiation. The RBE for 10 dicentrics per 100 cells was 3 for mixed beam and 7.2 for protons. For 20 dicentrics per 100 cells the respective values were 2.4 and 5.8. Within the limitations of the experimental setup the results indicate that for this endpoint there is no synergism between the high and low LET radiations. PMID:22809710

  15. Immunotherapy of acute radiation syndromes with antiradiation gamma G globulin.

    NASA Astrophysics Data System (ADS)

    Popov, Dmitri; Maliev, Vecheslav; Casey, Rachael; Jones, Jeffrey; Kedar, Prasad

    Introduction: If an immunotherapy treatment approach to treatment of acute radiation syndromes (ARS) were to be developed; consideration could be given to neutralization of radiation toxins (Specific Radiation Determinants- SRD) by specific antiradiation antibodies. To accomplish this objective, irradiated animals were injected with a preparation of antiradiation immunoglobulin G (IgG) obtained from hyperimmune donors. Radiation-indeced toxins that we call Specific Radiation Determinants (SRD) possess toxic (neurotoxic, haemotoxic and enterotoxic) characteristics as well as specific antigenic properties that combined with the direct physiochemical direct radiation damage, induce the development of many of the pathological processes associated with ARS. We tested several specific hyperimmune IgG preparations against these radiation toxins and observed that their toxic properties were neutralized by specific antiradiation IgGs. Material and Methods: Rabbits were inoculated with SRD radiation toxins to induce hyperimmune serum. The hyperimmune serum was pooled from several animals, purified, and concentrated. Enzyme-linked immunosorbent assays of the hyperimmune serum revealed high titers of IgG with specific binding to radiation toxins. The antiradiation IgG preparation was injected into laboratory animals one hour before and three hours after irradiation, and was evaluated for its ability to protect inoculated animals against the development of acute radiation syndromes. Results: Animals that were inoculated with specific antiradiation antibodies before receiving lethal irradiation at LD 100/30 exhibited 60-75% survival rate at 30 days, whereas all control animals expired by 30 days following exposure. These inoculated animals also exhibited markedly reduced clinical symptoms of ARS, even those that did not survive irradiation. Discussion: The results of our experiments demonstrate that rabbit hyperimmune serum directed against SRD toxins afford significant, albeit incomplete, protection against high doses of radiation. In comparison, the mortality rate of irradiated control animals was 100% in the same time period. The mortality rates of hyperimmune serum-treated animals varied in different groups of animals and different forms of ARS; however, significant radioprotection was observed in each group treated with IgGs activated against specific radiation toxins.

  16. Repair of radiation damage in mammalian cells

    SciTech Connect

    Setlow, R.B.

    1981-01-01

    The responses, such as survival, mutation, and carcinogenesis, of mammalian cells and tissues to radiation are dependent not only on the magnitude of the damage to macromolecular structures - DNA, RNA, protein, and membranes - but on the rates of macromolecular syntheses of cells relative to the half-lives of the damages. Cells possess a number of mechanisms for repairing damage to DNA. If the repair systems are rapid and error free, cells can tolerate much larger doses than if repair is slow or error prone. It is important to understand the effects of radiation and the repair of radiation damage because there exist reasonable amounts of epidemiological data that permits the construction of dose-response curves for humans. The shapes of such curves or the magnitude of the response will depend on repair. Radiation damage is emphasized because: (a) radiation dosimetry, with all its uncertainties for populations, is excellent compared to chemical dosimetry; (b) a number of cancer-prone diseases are known in which there are defects in DNA repair and radiation results in more chromosomal damage in cells from such individuals than in cells from normal individuals; (c) in some cases, specific radiation products in DNA have been correlated with biological effects, and (d) many chemical effects seem to mimic radiation effects. A further reason for emphasizing damage to DNA is the wealth of experimental evidence indicating that damages to DNA can be initiating events in carcinogenesis.

  17. Papain incorporated chitin dressings for wound debridement sterilized by gamma radiation

    NASA Astrophysics Data System (ADS)

    Singh, Durgeshwer; Singh, Rita

    2012-11-01

    Wound debridement is essential for the removal of necrotic or nonviable tissue from the wound surface to create an environment conducive to healing. Nonsurgical enzymatic debridement is an attractive method due to its effectiveness and ease of use. Papain is a proteolytic enzyme derived from the fruit of Carica papaya and is capable of breaking down a variety of necrotic tissue substrates. The present study was focused on the use of gamma radiation for sterilization of papain dressing with wound debriding activity. Membranes with papain were prepared using 0.5% chitin in lithium chloride/dimethylacetamide solvent and sterilized by gamma radiation. Fluid absorption capacity of chitin-papain membranes without glycerol was 14.30±6.57% in 6 h. Incorporation of glycerol resulted in significant (p<0.001) increase in the absorption capacity. Moisture vapour transmission rate of the membranes was 4285.77±455.61 g/m2/24 h at 24 h. Gamma irradiation at 25 kGy was found suitable for sterilization of the dressings. Infrared (IR) spectral scanning has shown that papain was stable on gamma irradiation at 25-35 kGy. The irradiated chitin-papain membranes were impermeable to different bacterial strains and also exhibited strong bactericidal action against both Gram-positive and Gram-negative bacteria. The fluid handling characteristics and the antimicrobial properties of chitin-papain membranes sterilized by gamma radiation were found suitable for use as wound dressing with debriding activity.

  18. CDDO-Me Protects Normal Lung and Breast Epithelial Cells but Not Cancer Cells from Radiation

    PubMed Central

    El-Ashmawy, Mariam; Delgado, Oliver; Cardentey, Agnelio; Wright, Woodring E.; Shay, Jerry W.

    2014-01-01

    Although radiation therapy is commonly used for treatment for many human diseases including cancer, ionizing radiation produces reactive oxygen species that can damage both cancer and healthy cells. Synthetic triterpenoids, including CDDO-Me, act as anti-inflammatory and antioxidant modulators primarily by inducing the transcription factor Nrf2 to activate downstream genes containing antioxidant response elements (AREs). In the present series of experiments, we determined if CDDO-Me can be used as a radioprotector in normal non-cancerous human lung and breast epithelial cells, in comparison to lung and breast cancer cell lines. A panel of normal non-cancerous, partially cancer progressed, and cancer cell lines from both lung and breast tissue was exposed to gamma radiation with and without pre-treatment with CDDO-Me. CDDO-Me was an effective radioprotector when given ∼18 hours before radiation in epithelial cells (average dose modifying factor (DMF) = 1.3), and Nrf2 function was necessary for CDDO-Me to exert these radioprotective effects. CDDO-Me did not protect cancer lines tested from radiation-induced cytotoxicity, nor did it protect experimentally transformed human bronchial epithelial cells (HBECs) with progressive oncogenic manipulations. CDDO-Me also protected human lymphocytes against radiation-induced DNA damage. A therapeutic window exists in which CDDO-Me protects normal cells from radiation by activating the Nrf2 pathway, but does not protect experimentally transformed or cancer cell lines. This suggests that use of this oral available, non-toxic class of drug can protect non-cancerous healthy cells during radiotherapy, resulting in better outcomes and less toxicity for patients. PMID:25536195

  19. Effects of gamma irradiation on the radiation-resistant bacteria and polyphenol oxidase activity in fresh kale juice

    NASA Astrophysics Data System (ADS)

    Kim, Dongho; Song, Hyunpa; Lim, Sangyong; Yun, Hyejeong; Chung, Jinwoo

    2007-07-01

    Gamma radiation was performed to prolong the shelf life of natural kale juice. The total aerobic bacteria in fresh kale juice, prepared by a general kitchen process, was detected in the range of 10 6 cfu/ml, and about 10 2 cfu/ml of the bacteria survived in the juice in spite of gamma irradiation treatment with a dose of 5 kGy. Two typical radiation-resistant bacteria, Bacillus megaterium and Exiguobacterium acetylicum were isolated and identified from the 5 kGy-irradiated kale juices. The D10 values of the vegetative cell and endospore of the B. megaterium in peptone water were 0.63±0.05 and 1.52±0.05 kGy, respectively. The D10 value of the E. acetylicum was calculated as 0.65±0.06 kGy. In the inoculation test, the growth of the surviving B. megaterium and E. acetylicum in the 3-5 kGy-irradiated kale juice retarded and/or decreased significantly during a 3 d post-irradiation storage period. However, there were no significant differences in the residual polyphenol oxidase activity and browning index between the nonirradiated control and the gamma irradiated kale juice during a post-irradiation period.

  20. Orbital Observatory GLAST - New Step in the Study of Cosmic Gamma Radiation: Mission Overview

    NASA Technical Reports Server (NTRS)

    Moiseev, Alexander

    2008-01-01

    This viewgraph presentation is a overview of the Gamma-ray Large Area Space Telescope (GLAST), now named Fermi Space Telescope. The new telescope is scheduled for launch in the middle of 2008. It contains the high energy gamma-ray telescope LAT (Large Area Telescope) and the GMB (GLAST Burst Monitor). The science objectives of GLAST cover almost every area of high energy astrophysics, including Active Galactic Nuclei (AGN), including Extragalactic background light (EBL), Gamma-ray bursts (GRB), Pulsars, Diffuse gamma-radiation, EGRET unidentified sources, Solar physics, Origin of Cosmic Rays and, Dark Matter and New Physics. Also included in this overview is a discussion of the preparation to the analysis of the science data.

  1. Radiation Enhances Regulatory T Cell Representation

    SciTech Connect

    Kachikwu, Evelyn L.; Iwamoto, Keisuke S.; Liao, Yu-Pei; DeMarco, John J.; Agazaryan, Nzhde; Economou, James S.; McBride, William H.; Schaue, Doerthe

    2011-11-15

    Purpose: Immunotherapy could be a useful adjunct to standard cytotoxic therapies such as radiation in patients with micrometastatic disease, although successful integration of immunotherapy into treatment protocols will require further understanding of how standard therapies affect the generation of antitumor immune responses. This study was undertaken to evaluate the impact of radiation therapy (RT) on immunosuppressive T regulatory (Treg) cells. Methods and Materials: Treg cells were identified as a CD4{sup +}CD25{sup hi}Foxp3{sup +} lymphocyte subset, and their fate was followed in a murine TRAMP C1 model of prostate cancer in mice with and without RT. Results: CD4{sup +}CD25{sup hi}Foxp3{sup +} Treg cells increased in immune organs after local leg or whole-body radiation. A large part, but not all, of this increase after leg-only irradiation could be ascribed to radiation scatter and Treg cells being intrinsically more radiation resistant than other lymphocyte subpopulations, resulting in their selection. Their functional activity on a per-cell basis was not affected by radiation exposure. Similar findings were made with mice receiving local RT to murine prostate tumors growing in the leg. The importance of the Treg cell population in the response to RT was shown by systemic elimination of Treg cells, which greatly enhanced radiation-induced tumor regression. Conclusions: We conclude that Treg cells are more resistant to radiation than other lymphocytes, resulting in their preferential increase. Treg cells may form an important homeostatic mechanism for tissues injured by radiation, and in a tumor context, they may assist in immune evasion during therapy. Targeting this population may allow enhancement of radiotherapeutic benefit through immune modulation.

  2. Response of organic liquid scintillators to fast neutrons and gamma radiation

    NASA Astrophysics Data System (ADS)

    Hoertz, Paul G.; Mills, Karmann; Davis, Lynn; Baldasaro, Nicholas; Gupta, Vijay

    2013-03-01

    Liquid organic scintillators are cocktails of aromatic fluorophores in an aromatic solvent. They find widespread use in Liquid Scintillation Counters with applications in medical diagnostics as well as fundamental nuclear and particle physics. Ultima Gold™ XR, a commercially available organic liquid scintillator from Perkin Elmer, can be used in both aqueous and non-aqueous systems and is typically used for beta detection in medical diagnostics. Its performance under gamma radiation and neutron radiation is less well-characterized. Special and normal Ultima Gold™ XR liquid scintillators were exposed in separate experiments to fast neutrons and high energy photons from a nuclear reactor and to gamma rays from a Co-60 source. To perform the measurements in the radiation chamber, a custom light collection system consisting of a fiber optic cable, spectrometer and a diffuse reflecting optical cavity was fabricated. Advanced calibration procedures, traceable to NIST standards, were developed to determine photon fluxes and flux densities of the scintillators under ionizing radiation conditions. The scintillator emission spectra under gamma radiation from a Co-60 source and neutron radiation from a pool-type nuclear reactor were recorded and compared. Results on the spectrometer design and comparison of the spectra under different exposure are presented.

  3. Thermal analysis evaluation of mechanical properties changes promoted by gamma radiation on surgical polymeric textiles

    NASA Astrophysics Data System (ADS)

    Ferreira, L. M.; Casimiro, M. H.; Oliveira, C.; Cabeço Silva, M. E.; Marques Abreu, M. J.; Coelho, A.

    2002-05-01

    The large number of surgical operations with post-operative infection problems and the appearing of new infectious diseases, contribute to the development of new materials in order to answer the needs of health care services. This development must take into account the modifications promoted by sterilisation methods in materials, namely by gamma radiation. The differential scanning calorimetry (DSC) and thermogravimetry (TGA) techniques show that a nonwoven and a laminate textiles maintain a good molecular cohesion, do not showing high levels of degradation, for gamma radiation dose values lower than 100 kGy in nonwoven and 200 kGy in laminate materials. The tensile strength and the elongation decrease slowly for the nonwoven textile and decrease faster for the laminate textile for 25 and 80 kGy absorbed dose. This paper shows that the DSC and TGA techniques can be helpful for the prevision of mechanical changes occurred in the materials as a consequence of the gamma irradiation.

  4. Production of hydrogel wound dressings using gamma radiation

    NASA Astrophysics Data System (ADS)

    Ajji, Z.; Othman, I.; Rosiak, J. M.

    2005-04-01

    Hydrogel wound dressings have been prepared using the gamma rays irradiation technique. The dressings are composed of poly(vinyl pyrrolidone) (PVP), poly(ethylene glycol) (PEG) and agar. The influence of some process parameters on the properties of the dressings has been investigated as: the gel fraction, maximum swelling, swelling kinetics, and mechanical properties. The gel fraction increases with increasing PVP concentration due to increased crosslink density, and decreases with increasing the PEG concentration. PEG seems to act not only as plasticizer but also to modify the gel properties as gelation% and maximum swelling. The prepared hydrogels dressings could be considered as a good barrier against microbes.

  5. Inactivation of foodborne pathogens on crawfish tail meat using cryogenic freezing and gamma radiation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Foodborne illness outbreaks occasionally occur as a result of microbiologically contaminated crustaceans, including crawfish. Cryogenic freezing and gamma radiation are two technologies which can be used to improve the microbiological safety and shelf-life of foods. In the U.S. the majority of non-c...

  6. Short-lived variations in the background gamma-radiation dose.

    PubMed

    Burnett, J L; Croudace, I W; Warwick, P E

    2010-09-01

    Sudden increases in the background gamma-radiation dose may occur due to the removal of (222)Rn and (220)Rn progeny from the atmosphere by wet deposition mechanisms. This contribution has been measured using a Geiger-Muller detector at the Atomic Weapons Establishment (Aldermaston, UK) during July 2005-April 2006. The results are approximated by a log-normal distribution and there were nine separate occurrences of the gamma-radiation dose exceeding 125% of the geometric mean value. The increases were associated with periods of heavy rainfall, although no correlation was evident between the dose rate and the amount of rainfall, as increased rainfall dilutes the activity further rather than increasing its atmospheric removal. The events were preceded by periods of fine weather and atmospheric stability that allow for the build-up of (222)Rn and (220)Rn progeny. Similar increases in gamma-radiation dose have been measured at a nearby monitoring station situated approximately 11 miles from Aldermaston. Increases in gamma-radiation dose during heavy rainfall have also been observed throughout the UK, that followed the trajectory of an air mass. All events decreased to typical values within 1-2 h as the water permeated into the ground below and the radioactivity decayed away. PMID:20826890

  7. Comparison of antibodies raised against heat-and gamma radiation-killed bacteria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For antibody generation, pathogenic bacteria are often heat-treated prior to inoculation into host animals in order to prevent infection and subsequently, premature death of the host. Inoculation of host rabbits with gamma radiation-killed pathogenic bacteria was employed with the hopes of generati...

  8. Use of gamma radiation as a form of preservation of sweet potatoes

    NASA Astrophysics Data System (ADS)

    The effects of (GAMMA) radiation on the sweet potato weevil, organoleptic properties of sweet potatoes, protein content of same, and sweet potato quality (vitamins, color, texture, and carbohydrates) are discussed. Evaluation of preliminary results indicate that changes should be made in irradiation procedures/conditions and analyses.

  9. Use of gamma radiation as a form of preservation of sweet potatoes. Quarterly progress report

    SciTech Connect

    Not Available

    1985-01-01

    This progress report covers: harvest and conditioning following harvest; effects of ..gamma.. radiation on the sweet potato weevil, organoleptic properties of sweet potatoes, protein content of same, and sweet potato quality (vitamins, color, texture, and carbohydrates). Evaluation of preliminary results indicate that changes should be made in irradiation procedures/conditions and analyses. (DLC)

  10. Gamma radiation inactivation of non-0157:H7 shiga-toxin producing Escherichia coli in foods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Non-O157:H7 serovars of shiga-toxin producing Escherichia coli are emerging foodborne pathogens that have been associated with illness outbreaks and food product recalls on a global basis. Ionizing (gamma) radiation is a nonthermal food safety intervention technology that has been approved for use i...

  11. MICRONUCLEI IN BINUCLEATED LYMPHOCYTES OF MICE FOLLOWING EXPOSURE TO GAMMA RADIATION

    EPA Science Inventory

    Experiments were designed to investigate the induction of micronuclei (MN) in mouse peripheral blood lymphocytes (PBLs) after in vitro or in vivo exposure to 60Co gamma radiation. or the in vitro experiments, 4 ml of blood from male C57BL/6J mice were either irradiated in 6 ml Fa...

  12. Gamma Radiation Induced Oxidation and Tocopherols Decrease in In-Shell, Peeled and Blanched Peanuts

    PubMed Central

    de Camargo, Adriano Costa; de Souza Vieira, Thais Maria Ferreira; Regitano-D’Arce, Marisa Aparecida Bismara; de Alencar, Severino Matias; Calori-Domingues, Maria Antonia; Canniatti-Brazaca, Solange Guidolin

    2012-01-01

    In-shell, peeled and blanched peanut samples were characterized in relation to proximate composition and fatty acid profile. No difference was found in relation to its proximate composition. The three major fatty acids were palmitic acid, oleic acid, and linoleic acid. In order to investigate irradiation and storage effects, peanut samples were submitted to doses of 0.0, 5.0, 7.5 or 10.0 kGy, stored for six months at room temperature and monitored every three months. Peanuts responded differently to irradiation, particularly with regards to tocopherol contents, primary and secondary oxidation products and oil stability index. Induction periods and tocopherol contents were negatively correlated with irradiation doses and decreased moderately during storage. α-Tocopherol was the most gamma radiation sensitive and peeled samples were the most affected. A positive correlation was found among tocopherol contents and the induction period of the oils extracted from irradiated samples. Gamma radiation and storage time increased oxidation compounds production. If gamma radiation is considered an alternative for industrial scale peanut conservation, in-shell samples are the best feedstock. For the best of our knowledge this is the first article with such results; this way it may be helpful as basis for future studies on gamma radiation of in-shell crops. PMID:22489128

  13. Radiation measurement above the lunar surface by Kaguya gamma-ray spectrometer

    NASA Astrophysics Data System (ADS)

    Hasebe, Nobuyuki; Nagaoka, Hiroshi; Kusano, Hiroki; Hareyama, Matoko; Ideguchi, Yusuke; Shimizu, Sota; Shibamura, Eido

    The lunar surface is filled with various ionizing radiations such as high energy galactic particles, albedo particles and secondary radiations of neutrons, gamma rays and other elementary particles. A high-resolution Kaguya Gamma-Ray Spectrometer (KGRS) was carried on the Japan’s lunar explorer SELENE (Kaguya), the largest lunar orbiter since the Apollo missions. The KGRS instrument employed, for the first time in lunar exploration, a high-purity Ge crystal to increase the identification capability of elemental gamma-ray lines. The Ge detector is surrounded by BGO and plastic counters as for anticoincidence shields. The KGRS measured gamma rays in the energy range from 200 keV to 13 MeV with high precision to determine the chemical composition of the lunar surface. It provided data on the abundance of major elements over the entire lunar surface. In addition to the gamma-ray observation by the KGRS, it successfully measured the global distribution of fast neutrons. In the energy spectra of gamma-rays observed by the KGRS, several saw-tooth- peaks of Ge are included, which are formed by the collision interaction of lunar fast neutrons with Ge atoms in the Ge crystal. With these saw-tooth-peaks analysis, global distribution of neutrons emitted from the lunara surface was successfully created, which was compared with the previous results obtained by Lunar Prospector neutron maps. Another anticoincidence counter, the plastic counter with 5 mm thickness, was used to veto radiation events mostly generated by charged particles. A single photomultiplier serves to count scintillation light from the plastic scintillation counter. The global map of counting rates observed by the plastic counter was also created, implying that the radiation counting rate implies the geological distribution, in spite that the plastic counter mostly measures high energy charged particles and energetic neutrons. These results are presented and discussed.

  14. Naturally induced secondary radiation in interplanetary space: Preliminary analyses for gamma radiation and radioisotope production from thermal neutron activation

    NASA Astrophysics Data System (ADS)

    Plaza-Rosado, Heriberto

    1991-09-01

    Thermal neutron activation analyses were carried out for various space systems components to determine gamma radiation dose rates and food radiation contamination levels. The space systems components selected were those for which previous radiation studies existed. These include manned space vehicle radiation shielding, liquid hydrogen propellant tanks for a Mars mission, and a food supply used as space vehicle radiation shielding. The computational method used is based on the fast neutron distribution generated by the BRYNTRN and HZETRN transport codes for Galactic Cosmic Rays (GCR) at solar minimum conditions and intense solar flares in space systems components. The gamma dose rates for soft tissue are calculated for water and aluminum space vehicle slab shields considering volumetric source self-attenuation and exponential buildup factors. In the case of the lunar habitat with regolith shielding, a completely exposed spherical habitat was assumed for mathematical convenience and conservative calculations. Activation analysis of the food supply used as radiation shielding is presented for four selected nutrients: potassium, calcium, sodium, and phosphorus. Radioactive isotopes that could represent a health hazard if ingested are identified and their concentrations are identified. For nutrients soluble in water, it was found that all induced radioactivity was below the accepted maximum permissible concentrations.

  15. Naturally induced secondary radiation in interplanetary space: Preliminary analyses for gamma radiation and radioisotope production from thermal neutron activation

    NASA Technical Reports Server (NTRS)

    Plaza-Rosado, Heriberto

    1991-01-01

    Thermal neutron activation analyses were carried out for various space systems components to determine gamma radiation dose rates and food radiation contamination levels. The space systems components selected were those for which previous radiation studies existed. These include manned space vehicle radiation shielding, liquid hydrogen propellant tanks for a Mars mission, and a food supply used as space vehicle radiation shielding. The computational method used is based on the fast neutron distribution generated by the BRYNTRN and HZETRN transport codes for Galactic Cosmic Rays (GCR) at solar minimum conditions and intense solar flares in space systems components. The gamma dose rates for soft tissue are calculated for water and aluminum space vehicle slab shields considering volumetric source self-attenuation and exponential buildup factors. In the case of the lunar habitat with regolith shielding, a completely exposed spherical habitat was assumed for mathematical convenience and conservative calculations. Activation analysis of the food supply used as radiation shielding is presented for four selected nutrients: potassium, calcium, sodium, and phosphorus. Radioactive isotopes that could represent a health hazard if ingested are identified and their concentrations are identified. For nutrients soluble in water, it was found that all induced radioactivity was below the accepted maximum permissible concentrations.

  16. The effect of gamma radiation on the Common carp (Cyprinus carpio): In vivo genotoxicity assessment with the micronucleus and comet assays.

    PubMed

    M K, Praveen Kumar; Soorambail K, Shyama; Bhagatsingh Harisingh, Sonaye; D'costa, Avelyno; Ramesh Chandra, Chaubey

    2015-10-01

    Radioactive wastes may be leached into freshwater, either accidentally or in industrial effluents. We have studied gamma radiation-induced DNA damage in the freshwater fish Cyprinus carpio. Fish were irradiated with 2-10Gy gamma radiation and genotoxic effects in blood cells were studied with the micronucleus (MN) and comet assays. Micronuclei and a dose-dependent increase in comet-tail DNA were seen in dose- and time-dependent studies. The highest % tail DNA was observed at 24h, declining until 72h, which may indicate the repair of radiation-induced DNA single-strand breaks after gamma radiation. However, double-stranded DNA damage may not have been repaired, as indicated by increased micronuclei at later periods. A positive correlation was observed between the comet and micronucleus assay results. This study confirms the mutagenic/genotoxic potential of gamma radiation in the Common carp, as well as the possible combined use of the micronucleus and comet assays for in vivo laboratory studies with fresh-water fish for screening the genotoxic potential of radioactive pollution. PMID:26433258

  17. Low-Dose Gamma Radiation Does Not Induce an Adaptive Response for Micronucleus Induction in Mouse Splenocytes.

    PubMed

    Bannister, L A; Serran, M L; Mantha, R R

    2015-11-01

    Low-dose ionizing radiation is known to induce radioadaptive responses in cells in vitro as well as in mice in vivo. Low-dose radiation decreases the incidence and increases latency for spontaneous and radiation-induced tumors in mice, potentially as a result of enhanced cellular DNA repair efficiency or a reduction in genomic instability. In this study, the cytokinesis-block micronucleus (CBMN) assay was used to examine dose response and potential radioadaptive response for cytogenetic damage and cell survival in C57BL/6 and BALB/c spleen cells exposed in vitro or in vivo to low-dose 60Co gamma radiation. The effects of genetic background, radiation dose and dose rate, sampling time and cell cycle were investigated with respect to dose response and radioadaptive response. In C57BL/6 mice, a linear-quadratic dose-response relationship for the induction of micronuclei (MN) was observed for doses between 100 mGy and 2 Gy. BALB/c mice exhibited increased radiosensitivity for MN induction compared to C57BL/6 mice. A 20 mGy dose had no effect on MN frequencies in splenocytes of either mouse strain, however, increased spleen weight and a reduced number of dead cells were noted in the C57BL/6 strain only. Multiple experimental parameters were investigated in radioadaptive response studies, including dose and dose rate of the priming dose (20 mGy at 0.5 mGy/min and 100 mGy at 10 mGy/min), time interval (4 and 24 h) between priming and challenge doses, cell cycle stage (resting or proliferating) at exposure and kinetics after the challenge dose. Radioadaptive responses were not observed for MN induction for either mouse strain under any of the experimental conditions investigated. In contrast, a synergistic response for radiation-induced micronuclei in C57BL/6 spleen was detected after in vivo 20 mGy irradiation. This increase in the percentage of cells with cytogenetic damage was associated with a reduction in the number of nonviable spleen cells, suggesting that low-dose irradiation led to a reduction in the turnover of damaged cells within the spleen of C57BL/6 mice. Overall, these results indicate that long-term protective effects against tumor latency and other beneficial health outcomes observed after low-dose irradiation are not mediated by a reduction of the proportion of cells harboring radiation-induced cytogenetic damage. PMID:26495871

  18. Low Doses of Gamma-Irradiation Induce an Early Bystander Effect in Zebrafish Cells Which Is Sufficient to Radioprotect Cells

    PubMed Central

    Pereira, Sandrine; Malard, Véronique; Ravanat, Jean-Luc; Davin, Anne-Hélène; Armengaud, Jean; Foray, Nicolas; Adam-Guillermin, Christelle

    2014-01-01

    The term “bystander effect” is used to describe an effect in which cells that have not been exposed to radiation are affected by irradiated cells though various intracellular signaling mechanisms. In this study we analyzed the kinetics and mechanisms of bystander effect and radioadaptation in embryonic zebrafish cells (ZF4) exposed to chronic low dose of gamma rays. ZF4 cells were irradiated for 4 hours with total doses of gamma irradiation ranging from 0.01–0.1 Gy. In two experimental conditions, the transfer of irradiated cells or culture medium from irradiated cells results in the occurrence of DNA double strand breaks in non-irradiated cells (assessed by the number of γ-H2AX foci) that are repaired at 24 hours post-irradiation whatever the dose. At low total irradiation doses the bystander effect observed does not affect DNA repair mechanisms in targeted and bystander cells. An increase in global methylation of ZF4 cells was observed in irradiated cells and bystander cells compared to control cells. We observed that pre-irradiated cells which are then irradiated for a second time with the same doses contained significantly less γ-H2AX foci than in 24 h gamma-irradiated control cells. We also showed that bystander cells that have been in contact with the pre-irradiated cells and then irradiated alone present less γ-H2AX foci compared to the control cells. This radioadaptation effect is significantly more pronounced at the highest doses. To determine the factors involved in the early events of the bystander effect, we performed an extensive comparative proteomic study of the ZF4 secretomes upon irradiation. In the experimental conditions assayed here, we showed that the early events of bystander effect are probably not due to the secretion of specific proteins neither the oxidation of these secreted proteins. These results suggest that early bystander effect may be due probably to a combination of multiple factors. PMID:24667817

  19. Persistence of gamma-H2AX and 53BP1 foci in proliferating and nonproliferating human mammary epithelial cells after exposure to gamma-rays or iron ions

    SciTech Connect

    Groesser, Torsten; Chang, Hang; Fontenay, Gerald; Chen, James; Costes, Sylvain V.; Barcellos-Hoff, Mary Helen; Parvin, Bahram; Rydberg, Bjorn

    2010-12-22

    To investigate {gamma}-H2AX (phosphorylated histone H2AX) and 53BP1 (tumour protein 53 binding protein No. 1) foci formation and removal in proliferating and non-proliferating human mammary epithelial cells (HMEC) after exposure to sparsely and densely ionizing radiation under different cell culture conditions. HMEC cells were grown either as monolayers (2D) or in extracellular matrix to allow the formation of acinar structures in vitro (3D). Foci numbers were quantified by image analysis at various time points after exposure. Our results reveal that in non-proliferating cells under 2D and 3D cell culture conditions, iron-ion induced {gamma}-H2AX foci were still present at 72 h after exposure, although 53BP1 foci returned to control levels at 48 h. In contrast in proliferating HMEC, both {gamma}-H2AX and 53BP1 foci decreased to control levels during the 24-48 h time interval after irradiation under 2D conditions. Foci numbers decreased faster after {gamma}-ray irradiation and returned to control levels by 12 h regardless of marker, cell proliferation status, and cell culture condition. Conclusions: The disappearance of radiation induced {gamma}-H2AX and 53BP1 foci in HMEC have different dynamics that depend on radiation quality and proliferation status. Notably, the general patterns do not depend on the cell culture condition (2D versus 3D). We speculate that the persistent {gamma}-H2AX foci in iron-ion irradiated non-proliferating cells could be due to limited availability of double strand break (DSB) repair pathways in G0/G1-phase, or that repair of complex DSB requires replication or chromatin remodeling.

  20. THE PHOTOSPHERIC RADIATION MODEL FOR THE PROMPT EMISSION OF GAMMA-RAY BURSTS: INTERPRETING FOUR OBSERVED CORRELATIONS

    SciTech Connect

    Fan Yizhong; Wei Daming; Zhang Fuwen; Zhang Binbin E-mail: dmwei@pmo.ac.cn E-mail: bbzhang@psu.edu

    2012-08-10

    We show that the empirical E{sub p}-L, {Gamma}-L, E{sub p}-{Gamma}, and {eta}-bar{sub {gamma}}-E{sub p} correlations (where L is the time-averaged luminosity of the prompt emission, E{sub p} is the spectral peak energy, {Gamma} is the bulk Lorentz factor, and {eta}-bar{sub {gamma}} is the emission efficiency of gamma-ray bursts, GRBs) are well consistent with the relations between the analogous parameters predicted in the photospheric radiation model of the prompt emission of GRBs. The time-resolved thermal radiation of GRB 090902B does follow the E{sub p}-L and {Gamma}-L correlations. A reliable interpretation of the four correlations in alternative models is still lacking. These may point toward a photospheric origin of prompt emission of some GRBs.

  1. Gamma radiation sensitivity of foodborne pathogens on meat and poultry

    SciTech Connect

    Thayer, D.W.; Boyd, G.

    1994-12-31

    Several factors have been identified that may affect the responses of foodborne pathogens to ionizing radiation. Among these are the temperature and atmosphere during the process of irradiation; the medium in which the pathogen is suspended; and the genus, species, serovar, and physiological state of the organism. In addition to these factors, variations in {open_quotes}apparent{close_quotes} radiation sensitivity of bacteria may occur because of the incubation conditions and media used to estimate the number of surviving colony-forming units. Both incubation temperature and culture media frequently affect the ability of injured bacteria to recover. Because there are so many possible variables, it is often difficult to compare data on the radiation sensitivity of foodborne pathogens from different studies. The objectives of the studies reported here were to compare the radiation sensitivities of Bacillus cereus on beef, beef gravy, chicken, pork, and turkey; and of Escherichia coli 0157:H7, Listeria monocytogenes, Salmonella, and Staphylococcus aureus on beef, pork, lamb, turkey breast, and turkey leg meats. Examples of the effects of serovar, irradiation temperature, growth phase, and atmosphere during irradiation were also examined.

  2. Inactivation of foodborne pathogens on seafood by gamma radiation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ionizing radiation is used on a global basis to improve the phytosanitary and microbial safety and shelf-life of foods. In recent years progress has been made in the commercial application of irradiation to sterilize destructive invasive insects and to irradiate produce to improve its microbiologica...

  3. Gamma radiation induces hydrogen absorption by copper in water.

    PubMed

    Lousada, Cláudio M; Soroka, Inna L; Yagodzinskyy, Yuriy; Tarakina, Nadezda V; Todoshchenko, Olga; Hänninen, Hannu; Korzhavyi, Pavel A; Jonsson, Mats

    2016-01-01

    One of the most intricate issues of nuclear power is the long-term safety of repositories for radioactive waste. These repositories can have an impact on future generations for a period of time orders of magnitude longer than any known civilization. Several countries have considered copper as an outer corrosion barrier for canisters containing spent nuclear fuel. Among the many processes that must be considered in the safety assessments, radiation induced processes constitute a key-component. Here we show that copper metal immersed in water uptakes considerable amounts of hydrogen when exposed to γ-radiation. Additionally we show that the amount of hydrogen absorbed by copper depends on the total dose of radiation. At a dose of 69 kGy the uptake of hydrogen by metallic copper is 7 orders of magnitude higher than when the absorption is driven by H2(g) at a pressure of 1 atm in a non-irradiated dry system. Moreover, irradiation of copper in water causes corrosion of the metal and the formation of a variety of surface cavities, nanoparticle deposits, and islands of needle-shaped crystals. Hence, radiation enhanced uptake of hydrogen by spent nuclear fuel encapsulating materials should be taken into account in the safety assessments of nuclear waste repositories. PMID:27086752

  4. Gamma radiation induces hydrogen absorption by copper in water

    PubMed Central

    Lousada, Cláudio M.; Soroka, Inna L.; Yagodzinskyy, Yuriy; Tarakina, Nadezda V.; Todoshchenko, Olga; Hänninen, Hannu; Korzhavyi, Pavel A.; Jonsson, Mats

    2016-01-01

    One of the most intricate issues of nuclear power is the long-term safety of repositories for radioactive waste. These repositories can have an impact on future generations for a period of time orders of magnitude longer than any known civilization. Several countries have considered copper as an outer corrosion barrier for canisters containing spent nuclear fuel. Among the many processes that must be considered in the safety assessments, radiation induced processes constitute a key-component. Here we show that copper metal immersed in water uptakes considerable amounts of hydrogen when exposed to γ-radiation. Additionally we show that the amount of hydrogen absorbed by copper depends on the total dose of radiation. At a dose of 69 kGy the uptake of hydrogen by metallic copper is 7 orders of magnitude higher than when the absorption is driven by H2(g) at a pressure of 1 atm in a non-irradiated dry system. Moreover, irradiation of copper in water causes corrosion of the metal and the formation of a variety of surface cavities, nanoparticle deposits, and islands of needle-shaped crystals. Hence, radiation enhanced uptake of hydrogen by spent nuclear fuel encapsulating materials should be taken into account in the safety assessments of nuclear waste repositories. PMID:27086752

  5. Gamma radiation induces hydrogen absorption by copper in water

    NASA Astrophysics Data System (ADS)

    Lousada, Cláudio M.; Soroka, Inna L.; Yagodzinskyy, Yuriy; Tarakina, Nadezda V.; Todoshchenko, Olga; Hänninen, Hannu; Korzhavyi, Pavel A.; Jonsson, Mats

    2016-04-01

    One of the most intricate issues of nuclear power is the long-term safety of repositories for radioactive waste. These repositories can have an impact on future generations for a period of time orders of magnitude longer than any known civilization. Several countries have considered copper as an outer corrosion barrier for canisters containing spent nuclear fuel. Among the many processes that must be considered in the safety assessments, radiation induced processes constitute a key-component. Here we show that copper metal immersed in water uptakes considerable amounts of hydrogen when exposed to γ-radiation. Additionally we show that the amount of hydrogen absorbed by copper depends on the total dose of radiation. At a dose of 69 kGy the uptake of hydrogen by metallic copper is 7 orders of magnitude higher than when the absorption is driven by H2(g) at a pressure of 1 atm in a non-irradiated dry system. Moreover, irradiation of copper in water causes corrosion of the metal and the formation of a variety of surface cavities, nanoparticle deposits, and islands of needle-shaped crystals. Hence, radiation enhanced uptake of hydrogen by spent nuclear fuel encapsulating materials should be taken into account in the safety assessments of nuclear waste repositories.

  6. Response of oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), eggs to gamma radiation

    NASA Astrophysics Data System (ADS)

    Silva, W. D.; Arthur, V.; Mastrangelo, T.

    2010-10-01

    As insects increase in radiotolerance as they develop and usually several developmental stages of the pest may be present in the fresh shipped commodity, it is important to know the radiation susceptibility of the stages of the target insect before the establishment of ionizing radiation quarantine treatments. This study was performed to determine the radiotolerance of eggs of the oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), to gamma radiation. This species is considered as one of the most serious worldwide pests for temperate fruits, especially peaches. Eggs (12 h old) were exposed to 0 (control), 25, 35, 50, 75, 100, 125 and 150 Gy of gamma radiation. Surviving larvae were allowed to feed on an artificial diet. Three days after irradiation, it was verified that larvae's cephalic capsules were significantly affected by gamma radiation, and the estimated mean LD 90 and LD 99 were 66.3 Gy and 125.8 Gy, respectively. Oriental fruit moth eggs revealed to be quite radiosensitive and very low doses as 50 Gy were sufficient to disrupt G. molesta embryogenesis. At 25 Gy, only male adults originated from the surviving larvae and, after mating with untreated fertile females, shown to be sterile.

  7. CARBON FIBRE COMPOSITE MATERIALS PRODUCED BY GAMMA RADIATION INDUCED CURING OF EPOXY RESINS

    SciTech Connect

    Dispenza, C.; Spadaro, G.; Alessi, S.

    2008-08-28

    It is well known that ionizing radiation can initiate polymerization of suitable monomers for many applications. In this work an epoxy difunctional monomer has been used as matrix of a carbon fibre composite in order to produce materials through gamma radiation, for aerospace and advanced automotive applications. Radiation curing has been performed at different absorbed doses and, as comparison, also thermal curing of the same monomer formulations has been done. Furthermore some irradiated samples have been also subjected to a post irradiation thermal curing in order to complete the polymerization reactions. The properties of the cured materials have been studied by moisture absorption isotherms, dynamic mechanical thermal analysis and mechanical flexural tests.

  8. Combined Effects of Gamma Radiation and High Dietary Iron on Peripheral Leukocyte Distribution and Function

    NASA Technical Reports Server (NTRS)

    Crucian, Brian E.; Morgan, Jennifer L. L.; Quiriarte, Heather A.; Sams, Clarence F.; Smith, Scott M.; Zwart, Sara R.

    2012-01-01

    Both radiation and increased iron stores can independently increase oxidative damage, resulting in protein, lipid and DNA oxidation. Oxidative stress increases the risk of many health problems including cancer, cataracts, and heart disease. This study, a subset of a larger interdisciplinary investigation of the combined effect of iron overload on sensitivity to radiation injury, monitored immune parameters in the peripheral blood of rats subjected to gamma radiation, high dietary iron or both. Specific immune measures consisted of: (1) peripheral leukocyte distribution, (2) plasma cytokine levels and (3) cytokine production profiles following whole blood mitogenic stimulation

  9. Effect of 60Co-gamma radiation on the binding properties in furs

    NASA Astrophysics Data System (ADS)

    Raina, R. K.

    New Zealand white rabbit pelts were pickled by the usual procedure and were tanned with basic aluminium sulphate, basic chromium sulphate and their combinations. Tanned furs were irradiated with 60Co-gamma radiations in the dose range of 5.0-114.0 kGy. The effect of radiation on the binding properties of various added substances like mineral tannins, fats, moisture and shrinkage temperature has been assessed by their comparison with the control samples. The results of these investigations show that radiation on furs causes detannage, increases the moisture and bound fat content and decreases the shrinkage temperature of the furs.

  10. Modification of silicone sealant to improve gamma radiation resistance, by addition of protective agents

    NASA Astrophysics Data System (ADS)

    González-Pérez, Giovanni; Burillo, Guillermina

    2013-09-01

    Poly (dimethylsiloxane) (PDMS) sealant (SS) was modified with the addition of different protective compounds to conserve its physical-chemical properties during gamma irradiation. 2-Vinyl naphthalene (2-VN), bisphenol-A (BPA) and poly (vinyl carbazole) (PVK) were used to evaluate radiation protection through the crosslinking effect of radiation. The samples were irradiated with doses from 100 kGy to 500 kGy at room temperature in air, with a 60Co gamma source, and the changes in molecular weight, thermal behavior, elastic properties and infrared spectra (FTIR-ATR) absorbance analysis were determined. The molecular weight of unmodified silicone sealant increases with the absorbed dose because of crosslinking as predominant effect. However, the crosslinking effect was inhibited with the addition of protective agent due to the aromatic compounds present. Modified silicone sealant films present better radiation resistance than unmodified system.

  11. Identification of three FcR-positive T cell subsets (T gamma, T mu and T gamma mu) in the cerebrospinal fluid of multiple sclerosis patients.

    PubMed Central

    Merrill, J E; Biberfeld, G; Landin, S; Sidén, A; Norrby, E

    1980-01-01

    Proportions of T cells and T cell subsets, as identified by their Fc receptors (FcR) for IgM and IgG (Tmu and T gamma), were determined in the peripheral blood lymphocyte (PBL) and cerebrospinal fluid (CSF) lymphocyte populations in patients with multiple sclerosis (MS). On average, MS patients had 79% total T cells (62% of which were T gamma, 66% Tmu) in CSF lymphocytes compared to 66% total T cells (30% T gamma, 63% Tmu) in PBL. Normal age- and sex-matched controls PBL had 74% total T cells (20% T gamma, 54% Tmu). By direct observation using an indirect immunofluorescence assay, 41% of the CSF T gamma cells in MS patients bore receptors for IgM; these cells were designated T gamma mu and, according to the double-marker analysis, did not seem to correlate with disease stage. In MS PBL, 20% of T gamma cells were T gamma mu compared to 9% in the control PBL T gamma population. Thus, MS patients had a higher proportion of total T cells, T gamma cells and T gamma mu cells in their CSF than in their peripheral blood and than those populations found in normal control blood. The significance of this T gamma mu population for the continuing disease state in MS is discussed. PMID:6970641

  12. Non-pulsed gamma radiation from a binary system with a pulsar

    NASA Astrophysics Data System (ADS)

    Chernyakova, M. A.; Illarionov, A. F.

    1999-04-01

    We consider a binary system with a millisecond pulsar ejecting relativistic particles and an optical star emitting soft photons with energy omega ~= 1-10 eV. These low-energy photons are scattered by the relativistic electrons and positrons of the pulsar wind. The scattered photons form a wide spectrum from the hard X-ray band up to gamma band epsilon ~= 1-1000 GeV. When the pulsar wind is isotropic, the luminosity of gamma radiation L_gamma=L_gamma(psi) depends strongly on the angle psi between the directions to the optical star and the observer from the pulsar. During the orbital motion this angle varies periodically, giving rise to a periodic change of the observed intensity of the gamma radiation and its spectrum. We calculate the spectral shape of the scattered hard photons. Under the assumption that the energy losses of the relativistic particles are small, we derive analytic formulae for the spectra of the photons. We apply our results to the binary system PSR B1259-63 and show that if the wind from the Be star is accounted for then it is possible to reproduce the observed spectrum.

  13. Predictions of induced background radiations at gamma/X-ray experiment envelopes in NASA spacecraft

    NASA Technical Reports Server (NTRS)

    Fischbein, W. L.; Debiak, T.; Rossi, M.; Stauber, M.; Suh, P.

    1979-01-01

    This work seeks to predict secondary radiation levels induced in spacecraft structures by space protons. The radiations analyzed are secondary neutrons from spallation and evaporation reactions and gamma and beta rays from the decay of induced radioactivity, as sources of interfering background to spaceborne measurements of galactic and planetary gamma rays below 10 MeV. The spacecraft considered are the Multi-Mission Spacecraft (MMS) and the Space Shuttle, modeled as spherical shells. The proton environment is that of the South Atlantic Anomaly, as well as cosmic ray protons. The induced radioactivity is analyzed in terms of its interference with various gamma-ray lines of astrophysical interest, as well as its contribution to several spectral regions of the gamma-ray continuum. The buildup of the line and continuum radioactivity background is predicted for a period of nearly 9 months in orbit (approximately 4100 orbits). In addition, background contributions from cosmic ray electron bremsstrahlung and earth gamma-ray albedo are estimated.

  14. Clinical Applications of Gamma Delta T Cells with Multivalent Immunity

    PubMed Central

    Deniger, Drew C.; Moyes, Judy S.; Cooper, Laurence J. N.

    2014-01-01

    γδ T cells hold promise for adoptive immunotherapy because of their reactivity to bacteria, viruses, and tumors. However, these cells represent a small fraction (1–5%) of the peripheral T-cell pool and require activation and propagation to achieve clinical benefit. Aminobisphosphonates specifically expand the Vγ9Vδ2 subset of γδ T cells and have been used in clinical trials of cancer where objective responses were detected. The Vγ9Vδ2 T cell receptor (TCR) heterodimer binds multiple ligands and results in a multivalent attack by a monoclonal T cell population. Alternatively, populations of γδ T cells with oligoclonal or polyclonal TCR repertoire could be infused for broad-range specificity. However, this goal has been restricted by a lack of applicable expansion protocols for non-Vγ9Vδ2 cells. Recent advances using immobilized antigens, agonistic monoclonal antibodies (mAbs), tumor-derived artificial antigen presenting cells (aAPC), or combinations of activating mAbs and aAPC have been successful in expanding gamma delta T cells with oligoclonal or polyclonal TCR repertoires. Immobilized major histocompatibility complex Class-I chain-related A was a stimulus for γδ T cells expressing TCRδ1 isotypes, and plate-bound activating antibodies have expanded Vδ1 and Vδ2 cells ex vivo. Clinically sufficient quantities of TCRδ1, TCRδ2, and TCRδ1negTCRδ2neg have been produced following co-culture on aAPC, and these subsets displayed differences in memory phenotype and reactivity to tumors in vitro and in vivo. Gamma delta T cells are also amenable to genetic modification as evidenced by introduction of αβ TCRs, chimeric antigen receptors, and drug-resistance genes. This represents a promising future for the clinical application of oligoclonal or polyclonal γδ T cells in autologous and allogeneic settings that builds on current trials testing the safety and efficacy of Vγ9Vδ2 T cells. PMID:25566249

  15. High-total-dose gamma and neutron radiation tolerance of VCSEL assemblies

    NASA Astrophysics Data System (ADS)

    Berghmans, Francis; Van Uffelen, Marco; Decréton, Marc C.

    2002-09-01

    Optical fiber technology is seriously considered for communication and monitoring applications during the operation and maintenance of future thermonuclear fusion reactors. Their environment is characterized, in particular, by possibly high gamma dose-rates and total doses in excess of 10 MGy. In addition, the maintenance equipment might be stored in close vicinity of the reactor during its operation and therefore the communication devices might also be exposed to a substantial neutron fluence. The feasibility of applying photonic technology in these radiation fields therefore needs to be assessed. Whereas many reports deal with the radiation behavior of a variety of fiber-optic devices, only little information is available on the radiation tolerance at high total dose (e.g. > 1 MGy). We describe our recent results obtained on vertical-cavity surface-emitting laser (VCSEL) assemblies. We have conducted high total dose (up to 20 MGy) irradiation experiments on such devices, which confirmed their excellent gamma radiation hardness. The optical power loss at nominal forward current was less than 2 dB and the threshold current remained unaltered. We have also irradiated these devices with neutrons inside the BR1 reactor (SCK•CEN, Mol, Belgium) up to a total fluence on the order of 1015 n×cm-2. The response of VCSELs to neutrons is, as expected, different from that to gamma radiation. VCSELs previously exposed to gamma rays exhibited an accelerated degradation under neutron radiation compared to not pre-irradiated devices. The beneficial effect of applying a continuous forward bias to the VCSELs is also evidenced.

  16. Evaluation of fungal burden and aflatoxin presence in packed medicinal plants treated by gamma radiation.

    PubMed

    Aquino, Simone; Gonçalez, Edlayne; Rossi, Maria Helena; Nogueira, Juliana Hellmeister de Campos; Reis, Tatiana Alves Dos; Corrêa, Benedito

    2010-05-01

    This study was developed to evaluate the fungal burden, toxigenic molds, and mycotoxin contamination and to verify the effects of gamma radiation in four kinds of medicinal plants stored before and after 30 days of irradiation treatment. Eighty samples of medicinal plants (Peumus boldus, Camellia sinensis, Maytenus ilicifolia, and Cassia angustifolia) purchased from drugstores, wholesale, and open-air markets in São Paulo city, Brazil, were analyzed. The samples were treated using a (60)Co gamma ray source (Gammacell) with doses of 5 and 10 kGy. Nonirradiated samples were used as controls of fungal isolates. For enumeration of fungi on medicinal plants, serial dilutions of the samples were plated in duplicate onto dichloran 18% glycerol agar. The control samples revealed a high burden of molds, including toxigenic fungi. The process of gamma radiation was effective in reducing the number of CFU per gram in all irradiated samples of medicinal plants after 30 days of storage, using a dose of 10 kGy and maintaining samples in a protective package. No aflatoxins were detected. Gamma radiation treatment can be used as an effective method for preventing fungal deterioration of medicinal plants subject to long-term storage. PMID:20501045

  17. Sublethal effects in Atlantic salmon (Salmo salar) exposed to mixtures of copper, aluminium and gamma radiation.

    PubMed

    Heier, Lene Sørlie; Teien, Hans Christian; Oughton, Deborah; Tollefsen, Knut-Erik; Olsvik, Pål A; Rosseland, Bjørn Olav; Lind, Ole Christian; Farmen, Eivind; Skipperud, Lindis; Salbu, Brit

    2013-07-01

    The present study was designed to investigate the effects in presmolt of Atlantic salmon (Salmo salar) exposed to copper (Cu), aluminium (Al) and gamma radiation, individually or in combination. Fish were exposed for 48 h to metals added to lake water; 10, 40 and 80 μg Cu/L, 250 μg Al/L and a combination of 40 μg Cu/L and 250 μg Al/L. In addition, gamma radiation (4-70 mGy delivered over 48 h) was added as an additional exposure stressor. Selected endpoints were chosen to reveal different toxic mechanisms and included Cu and Al accumulation on gills, blood chemistry and haematological variables (plasma sodium and chloride, haematocrit, glucose), hepatic levels of reduced and oxidised glutathione (GSH and GSSG) and hepatic transcriptional response of glutathione peroxidase (GPx), gamma-glutamylcysteine synthetase (GCS), metallothionein (MT) and ubiquitin. Exposure to Cu alone resulted in gill accumulation of Cu, reduction of plasma ions and increased transcriptional response of GPx, MT and ubiquitin. Exposure to Al alone reduced plasma ion levels but did not affect any of the hepatic biomarkers except for ubiquitin. The combined metal exposure (Cu + Al) altered the GSH levels, however GPx and MT were not affected suggesting a different mode of detoxification in the combined exposure. Gamma radiation appeared to influence GSH and ubiquitin levels. The observed effects seemed to be both stressor and concentration dependent. PMID:22583837

  18. Inactivation of Thirty Viruses by Gamma Radiation 1

    PubMed Central

    Sullivan, Robert; Fassolitis, Alexander C.; Larkin, Edward P.; Read, Ralston B.; Peeler, James T.

    1971-01-01

    Decimal reduction values (D value) for 30 viruses were determined. The weighted D values of the viruses suspended in Eagle's minimum essential medium ranged from 0.39 to 0.53 Mrads. It was necessary to increase the radiation dose by a factor of >3 to inactivate virus suspended in Eagle's minimum essential medium as compared to the same virus suspended in distilled water. The destruction rate curves were of a first-order reaction. PMID:4999976

  19. Radiation anomaly detection algorithms for field-acquired gamma energy spectra

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Sanjoy; Maurer, Richard; Wolff, Ron; Guss, Paul; Mitchell, Stephen

    2015-08-01

    The Remote Sensing Laboratory (RSL) is developing a tactical, networked radiation detection system that will be agile, reconfigurable, and capable of rapid threat assessment with high degree of fidelity and certainty. Our design is driven by the needs of users such as law enforcement personnel who must make decisions by evaluating threat signatures in urban settings. The most efficient tool available to identify the nature of the threat object is real-time gamma spectroscopic analysis, as it is fast and has a very low probability of producing false positive alarm conditions. Urban radiological searches are inherently challenged by the rapid and large spatial variation of background gamma radiation, the presence of benign radioactive materials in terms of the normally occurring radioactive materials (NORM), and shielded and/or masked threat sources. Multiple spectral anomaly detection algorithms have been developed by national laboratories and commercial vendors. For example, the Gamma Detector Response and Analysis Software (GADRAS) a one-dimensional deterministic radiation transport software capable of calculating gamma ray spectra using physics-based detector response functions was developed at Sandia National Laboratories. The nuisance-rejection spectral comparison ratio anomaly detection algorithm (or NSCRAD), developed at Pacific Northwest National Laboratory, uses spectral comparison ratios to detect deviation from benign medical and NORM radiation source and can work in spite of strong presence of NORM and or medical sources. RSL has developed its own wavelet-based gamma energy spectral anomaly detection algorithm called WAVRAD. Test results and relative merits of these different algorithms will be discussed and demonstrated.

  20. High Radiation Resistance IMM Solar Cell

    NASA Technical Reports Server (NTRS)

    Pan, Noren

    2015-01-01

    Due to high launch costs, weight reduction is a key driver for the development of new solar cell technologies suitable for space applications. This project is developing a unique triple-junction inverted metamorphic multijunction (IMM) technology that enables the manufacture of very lightweight, low-cost InGaAsP-based multijunction solar cells. This IMM technology consists of indium (In) and phosphorous (P) solar cell active materials, which are designed to improve the radiation-resistant properties of the triple-junction solar cell while maintaining high efficiency. The intrinsic radiation hardness of InP materials makes them of great interest for building solar cells suitable for deployment in harsh radiation environments, such as medium Earth orbit and missions to the outer planets. NASA Glenn's recently developed epitaxial lift-off (ELO) process also will be applied to this new structure, which will enable the fabrication of the IMM structure without the substrate.

  1. Mammalian stem cells reprogramming in response to terahertz radiation.

    PubMed

    Bock, Jonathan; Fukuyo, Yayoi; Kang, Sona; Phipps, M Lisa; Alexandrov, Ludmil B; Rasmussen, Kim Ø; Bishop, Alan R; Rosen, Evan D; Martinez, Jennifer S; Chen, Hou-Tong; Rodriguez, George; Alexandrov, Boian S; Usheva, Anny

    2010-01-01

    We report that extended exposure to broad-spectrum terahertz radiation results in specific changes in cellular functions that are closely related to DNA-directed gene transcription. Our gene chip survey of gene expression shows that whereas 89% of the protein coding genes in mouse stem cells do not respond to the applied terahertz radiation, certain genes are activated, while other are repressed. RT-PCR experiments with selected gene probes corresponding to transcripts in the three groups of genes detail the gene specific effect. The response was not only gene specific but also irradiation conditions dependent. Our findings suggest that the applied terahertz irradiation accelerates cell differentiation toward adipose phenotype by activating the transcription factor peroxisome proliferator-activated receptor gamma (PPARG). Finally, our molecular dynamics computer simulations indicate that the local breathing dynamics of the PPARG promoter DNA coincides with the gene specific response to the THz radiation. We propose that THz radiation is a potential tool for cellular reprogramming. PMID:21209821

  2. Accumulation of Mn(II) in Deinococcus radiodurans Facilitates Gamma-Radiation Resistance

    SciTech Connect

    Daly, Michael J.; Gaidamakova, E; Matrosova, V; Vasilenko, A; Zhai, M; Venkateswaran, Amudhan; Hess, M; Omelchenko, M V.; Kostandarithes, Heather M.; Makarova, S; Wackett, L. P.; Fredrickson, Jim K.; Ghosal, D

    2004-11-05

    Deinococcus radiodurans is extremely resistant to ionizing radiation. How this bacterium can grow under chronic gamma-radiation (50 Gy/hour) or recover from acute doses greater than 10 kGy is unknown. We show that D. radiodurans accumulates very high intracellular manganese and low iron levels compared to radiation sensitive bacteria, and resistance exhibits a concentration-dependent response to Mn(II). Among the most radiation-resistant bacterial groups reported, Deinococcus, Enterococcus, Lactobacillus and cyanobacteria spp. accumulate Mn(II). In contrast, Shewanella oneidensis and Pseudomonas putida have high Fe but low intracellular Mn concentrations and are very sensitive. We propose that Mn(II) accumulation facilitates recovery from radiation injury.

  3. Radiation Enhances Regulatory T Cell Representation

    PubMed Central

    Kachikwu, Evelyn L.; Iwamoto, Keisuke S.; Liao, Yu-Pei; DeMarco, John J.; Agazaryan, Nzhde; Economou, James S.; McBride, William H.; Schaue, Dörthe

    2010-01-01

    PURPOSE Immunotherapy (IT) could be a useful adjunct to standard cytotoxic therapies such as radiation in patients with micrometastatic disease although successful integration of IT into treatment protocols will require further understanding of how standard therapies affect the generation of anti-tumor immune responses. This study was undertaken to evaluate the impact of radiation therapy on immunosuppressive T regulatory (Treg) cells. MATERIALS and METHODS Tregs were identified as a CD4+CD25hiFoxp3+ lymphocyte subset and their fate followed in a murine TRAMP-C1 model of prostate cancer in mice with and without radiation therapy. RESULTS CD4+CD25hiFoxp3+ Treg cells increased in immune organs following local leg or whole body radiation. A large part, but not all, of this increase following leg-only irradiation could be ascribed to radiation scatter and Tregs being intrinsically more radiation resistant than other lymphocyte subpopulations resulting in their selection. Their functional activity on a per cell basis was not affected by radiation exposure. Similar findings were made with mice receiving local RT to murine prostate tumors growing in the leg. The importance of the Treg population in the response to RT was shown by systemic elimination of Tregs, which greatly enhanced radiation-induced tumor regression. CONCLUSIONS We conclude that Tregs are more resistant to radiation than other lymphocytes resulting in their preferential increase. Treg cells may form an important homeostatic mechanism for tissues injured by radiation, and in a tumor context may assist in immune evasion during therapy. Targeting this population may allow enhancement of radiotherapeutic benefit through immune modulation. PMID:21093169

  4. Enhanced Beta-Gamma Coincidence Counting Gas Cell

    SciTech Connect

    McIntyre, Justin I.; Carman, April J.; Aalseth, Craig E.; Hayes, James C.; Heimbigner, Tom R.; Hossbach, Todd W.; Hubbard, Charles W.; Litke, Kevin E.; Miley, Harry S.; Morris, Scott J.; Ripplinger, Michael D.; Suarez, Reynold

    2005-10-01

    The Automated Radioxenon Sampler/Analyzer (ARSA) uses a highly compact, high efficiency beta-gamma coincidence detector to detect 133Xe, 131mXe, 133mXe and 135Xe for treaty monitoring and environmental sampling. This system has shown itself to be reliable and robust in several field exercises [1, 2]. However, from a maintenance and quality assurance/quality control (QA/QC) standpoint it suffers from a very detailed photo-multiplier-tube gain matching regime. In an effort to upgrade and simplify the current beta-gamma coincident detector, PNNL has developed a simplified but equally effective well-type detector. Initial comparison between three different well detectors has been performed. Along with the well gamma-ray detectors, a new plastic scintillation gas cell was constructed. The spectral resolution and efficiency obtained from this new design has been demonstrated to be as good as or better than the original ARSA design with greatly improved calibration and maintenance characteristics. The ARSA detector and the well-detector design and effectiveness for xenon detection will be discussed.

  5. Tolerance to Gamma Radiation in the Tardigrade Hypsibius dujardini from Embryo to Adult Correlate Inversely with Cellular Proliferation

    PubMed Central

    Beltrán-Pardo, Eliana; Jönsson, K. Ingemar; Harms-Ringdahl, Mats; Haghdoost, Siamak; Wojcik, Andrzej

    2015-01-01

    Tardigrades are highly tolerant to desiccation and ionizing radiation but the mechanisms of this tolerance are not well understood. In this paper, we report studies on dose responses of adults and eggs of the tardigrade Hypsibius dujardini exposed to gamma radiation. In adults the LD50/48h for survival was estimated at ~ 4200 Gy, and doses higher than 100 Gy reduced both fertility and hatchability of laid eggs drastically. We also evaluated the effect of radiation (doses 50 Gy, 200 Gy, 500 Gy) on eggs in the early and late embryonic stage of development, and observed a reduced hatchability in the early stage, while no effect was found in the late stage of development. Survival of juveniles from irradiated eggs was highly affected by a 500 Gy dose, both in the early and the late stage. Juveniles hatched from eggs irradiated at 50 Gy and 200 Gy developed into adults and produced offspring, but their fertility was reduced compared to the controls. Finally we measured the effect of low temperature during irradiation at 4000 Gy and 4500 Gy on survival in adult tardigrades, and observed a slight delay in the expressed mortality when tardigrades were irradiated on ice. Since H. dujardini is a freshwater tardigrade with lower tolerance to desiccation compared to limno-terrestrial tardigrades, the high radiation tolerance in adults, similar to limno-terrestrial tardigrades, is unexpected and seems to challenge the idea that desiccation and radiation tolerance rely on the same molecular mechanisms. We suggest that the higher radiation tolerance in adults and late stage embryos of H. dujardini (and in other studied tardigrades) compared to early stage embryos may partly be due to limited mitotic activity, since tardigrades have a low degree of somatic cell division (eutely), and dividing cells are known to be more sensitive to radiation. PMID:26208275

  6. Modern Methods of Real-Time Gamma Radiation Monitoring for General Personal Protection

    NASA Astrophysics Data System (ADS)

    Korostynska, O.; Arshak, K.; Arshak, A.; Vaseashta, Ashok

    Real-time radiation detectors become an essential part of emergency personnel who may have to respond to unknown accidents, incidents or terrorist attacks, which could involve radioactive material. More and more ordinary citizens are interested in personal radiation protection as well. Reasons include lost sources, nuclear industrial accidents, nuclear or radiological terrorism and the possibility of nuclear weapons being used in a war. People want to have the ability to measure it for themselves and they want to be notified when the radiation levels are increased. To meet this demand, considerable research into new sensors is underway, including efforts to enhance the sensor performance through both the material properties and manufacturing technologies. Deep understanding of physical properties of the materials under the influence of radiation exposure is vital for the effective design of dosimeter devices. Detection of radiation is based on the fact that both the electrical and the optical properties of the materials undergo changes upon the exposure to ionizing radiation. It is believed that radiation causes structural defects. The influence of radiation depends on both the dose and the parameters of the films including their thickness: the degradation is more severe for the higher dose and the thinner films. This paper presents overview of modern methods of real-time gamma radiation monitoring for personal protection of radiation workers and general public and suggests further developments in this area.

  7. Effect of sublethal gamma radiation on host defenses in experimental scrub typhus

    SciTech Connect

    Kelly, D.J.; Rees, J.C.

    1986-06-01

    The effect of sublethal gamma radiation on inbred mice chronically infected with scrub typhus rickettsiae was examined. Inbred mice which were inoculated with the Gilliam or Karp strain of Rickettsia tsutsugamushi by the subcutaneous route harbored the infection for at least 1 year. Irradiation of these animals at 12 or 52 weeks postinoculation with normally sublethal levels induced a significantly higher percentage of rickettsemic mice (recrudescence) than was seen in the unirradiated, similarly infected control animals. In addition, sublethal irradiation at 12 weeks induced a quantitative increase in total rickettsiae. Homologous antibody titers to the rickettsiae were examined for 5 weeks after irradiation to determine the role of the humoral response in radiation-induced recrudescence. Unirradiated, infected mice showed consistent titers of about 320 throughout the 5-week observation period, and the titer was not affected by exposure of up to 500 rads of gamma radiation. Drug dose-dependent radioprotection and modification of recrudescence was noted in infected, irradiated mice treated with the antiradiation compound S-2-(3-aminopropylamino)ethyl phosphorothioic acid. The results of this investigation supported the conclusion that the recrudescence of a chronic rickettsial infection in the appropriate host after immunological impairment due to gamma radiation can result in an acute, possibly lethal rickettsemia.

  8. Foods for a Mission to Mars: Investigations of Low-Dose Gamma Radiation Effects

    NASA Technical Reports Server (NTRS)

    Gandolph, J.; Shand, A.; Stoklosa, A.; Ma, A.; Weiss, I.; Alexander, D.; Perchonok, M.; Mauer, L. J.

    2007-01-01

    Food must be safe, nutritious, and acceptable throughout a long duration mission to maintain the health, well-being, and productivity of the astronauts. In addition to a developing a stable pre-packaged food supply, research is required to better understand the ability to convert edible biomass into safe, nutritious, and acceptable food products in a closed system with many restrictions (mass, volume, power, crew time, etc.). An understanding of how storage conditions encountered in a long-term space mission, such as elevated radiation, will impact food quality is also needed. The focus of this project was to contribute to the development of the highest quality food system possible for the duration of a mission, considering shelf-stable extended shelf-life foods, bulk ingredients, and crops to be grown in space. The impacts of space-relevant radiation doses on food, bulk ingredient, and select candidate crop quality and antioxidant capacity were determined. Interestingly, increasing gamma-radiation doses (0 to 1000 Gy) did not always increase dose-related effects in foods. Intermediate radiation doses (10 to 800Gy) often had significantly larger impact on the stability of bulk ingredient oils than higher (1000Gy) radiation doses. Overall, most food, ingredient, and crop systems investigated showed no significant differences between control samples and those treated with 3 Gy of gamma radiation (the upper limit estimated for a mission to Mars). However, this does not mean that all foods will be stable for 3-5 years, nor does it mean that foods are stable to space radiation comprising more than gamma rays.

  9. Sensitometry of the response of a new radiochromic film dosimeter to gamma radiation and electron beams

    NASA Astrophysics Data System (ADS)

    McLaughlin, W. L.; Yun-Dong, Chen; Soares, C. G.; Miller, A.; Van Dyk, G.; Lewis, D. F.

    1991-04-01

    A new radiation-sensitive imaging material, called GafChromic™ Dosimetry Media, offers advances in high-dose radiation dosimetry and high-resolution radiography for gamma radiation and electrons. The potential uses in radiation processing, radiation sterilization of medical devices, population control of insects by irradiation, food irradiation, blood irradiation for organ-transplant immuno-suppression, clinical radiography, and industrial radiography have led to the present sensitometric study over the breadth of the wide dynamic range of this new routine detector and imaging material, namely, absorbed doses from 10 Gy to 5 × 10 4 Gy. The thin-coated film is colorless before irradiation, and registers a deep-blue image upon irradiation, with two absorption bands at about 650 nm (major band) and 600 nm (minor band). The response to electrons, in terms of increase in absorbance per unit absorbed dose, is the same as that to gamma radiation within the estimated uncertainty of the measurements (± 5%, 95% confidence level). The spatial resolving power is > 1200 lines/mm. After the first 24 hours, the image is stable over many months (within ± 5% in absorbance), however, the system should be irradiated and analyzed at approximately the temperatures used during calibration, because of temperature dependence during irradiation and readout, and temperatures greater than 55°C should be avoided.

  10. High-efficiency scintillation detector for combined of thermal and fast neutrons and gamma radiation

    DOEpatents

    Chiles, Marion M.; Mihalczo, John T.; Blakeman, Edward D.

    1989-01-01

    A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation even count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.

  11. High-efficiency scintillation detector for combined detection of thermal and fast neutrons and gamma radiation

    DOEpatents

    Chiles, M.M.; Mihalczo, J.T.; Blakeman, E.D.

    1987-02-27

    A scintillation based radiation detector for the combined detection of thermal neutrons, high-energy neutrons and gamma rays in a single detecting unit. The detector consists of a pair of scintillators sandwiched together and optically coupled to the light sensitive face of a photomultiplier tube. A light tight radiation pervious housing is disposed about the scintillators and a portion of the photomultiplier tube to hold the arrangement in assembly and provides a radiation window adjacent the outer scintillator through which the radiation to be detected enters the detector. The outer scintillator is formed of a material in which scintillations are produced by thermal-neutrons and the inner scintillator is formed of a material in which scintillations are produced by high-energy neutrons and gamma rays. The light pulses produced by events detected in both scintillators are coupled to the photomultiplier tube which produces a current pulse in response to each detected event. These current pulses may be processed in a conventional manner to produce a count rate output indicative of the total detected radiation event count rate. Pulse discrimination techniques may be used to distinguish the different radiations and their energy distribution.

  12. Assessment of Gamma Radiation Resistance of Spores Isolated from the Spacecraft Assembly Facility During MSL Assembly

    NASA Technical Reports Server (NTRS)

    Chopra, Arsh; Ramirez, Gustavo A.; Vaishampayan, Parag A.; Venkateswaran, Kasthuri J.

    2011-01-01

    Spore forming bacteria, a common inhabitant of spacecraft assembly facilities, are known to tolerate extreme environmental conditions such as radiation, desiccation, and high temperatures. Since the Viking era (early 1970's), spores have been utilized to assess the degree and level of microbiological contamination on spacecraft and their associated spacecraft assembly facilities. There is a growing concern that desiccation and extreme radiation resistant spore forming microorganisms associated with spacecraft surfaces can withstand space environmental conditions and subsequently proliferate on another solar body. Such forward contamination would certainly jeopardize future life detection or sample return technologies. It is important to recognize that different classes of organisms are critical while calculating the probability of contamination, and methods must be devised to estimate their abundances. Microorganisms can be categorized based on radiation sensitivity as Type A, B, C, and D. Type C represents spores resistant to radiation (10% or greater survival above 0.8 Mrad gamma radiation). To address these questions we have purified 96 spore formers, isolated during planetary protection efforts of Mars Science Laboratory assembly for gamma radiation resistance. The spores purified and stored will be used to generate data that can be used further to model and predict the probability of forward contamination.

  13. Assessment of Gamma Radiation Resistance of Spores Isolated from the Spacecraft Assembly Facility During MSL Assembly

    NASA Technical Reports Server (NTRS)

    Chopra, Arsh; Ramirez, Gustavo A.; Venkateswaran, Kasthuri J.; Vaishampayan, Parag A.

    2011-01-01

    Spore forming bacteria, a common inhabitant of spacecraft assembly facilities, are known to tolerate extreme environmental conditions such as radiation, desiccation, and high temperatures. Since the Viking era (early 1970's), spores have been utilized to assess the degree and level of microbiological contamination on spacecraft and their associated spacecraft assembly facilities. There is a growing concern that desiccation and extreme radiation resistant spore forming microorganisms associated with spacecraft surfaces can withstand space environmental conditions and subsequently proliferate on another solar body. Such forward contamination would certainly jeopardize future life detection or sample return technologies. It is important to recognize that different classes of organisms are critical while calculating the probability of contamination, and methods must be devised to estimate their abundances. Microorganisms can be categorized based on radiation sensitivity as Type A, B, C, and D. Type C represents spores resistant to radiation (10% or greater survival above 0.8 mRad gamma radiation). To address these questions we have purified 96 spore formers, isolated during planetary protection efforts of Mars Science Laboratory assembly for gamma radiation resistance. The spores purified and stored will be used to generate data that can be used further to model and predict the probability of forward contamination.

  14. Radiation tolerance of vertical junction solar cells

    NASA Technical Reports Server (NTRS)

    Schelnine, A.; Wohlgemuth, J.

    1980-01-01

    Extensive radiation testing of vertical junction (VJ) solar cells demonstrated a radiation tolerance better than both planar silicon cells and at least one type of (AlGa)As-GaAs cell. Due to tradeoffs between short circuit current and open circuit voltage, the end of life (10 to the 16th power 1 MeV electrons/sq cm) maximum power point is nearly independent of bulk resistivity between 2 and 10 ohm cm, increases slightly with increasing wafer thickness between 3 and 11 mils, and increases slightly with increasing groove depth between 1 and 3 mils.

  15. Search for ultra-high-energy radiation from [gamma]-ray bursts

    SciTech Connect

    Schnee, R.W.

    1993-01-01

    Using data from the CYGNUS extensive air shower array, we have searched for evidence of emission of ultra-high-energy radiation coincident with [gamma]-ray bursts observed by the BATSE instrument on the Compton Gamma-Ray Observatory. No statistically significant excess was found for any point in the sky within 4[sigma] of BATSE's best location coordinates for any of the 56 bursts examined. Furthermore, no events were seen in the 2.2[degree] radius circular bin surrounding [gamma]-ray burst GRB 920720, whose location was determined accurately by the Compton/Ulysses/PVO Interplanetary Network of satellites. Flux upper limits depend greatly on the actual zenith angle of the burst. Typical fluence upper limits above 100 TeV are [approximately]10[sup [minus]6] erg cm[sup [minus]2]. The fluence upper limits for GRB 920720 is 2 [times] 10[sup [minus]6] erg cm[sup [minus]2].

  16. Detection of galactic Al-26 gamma radiation by the SMM spectrometer

    NASA Technical Reports Server (NTRS)

    Share, G. H.; Kinzer, R. L.; Kurfess, J. D.; Forrest, D. J.; Chupp, E. L.; Rieger, E.

    1985-01-01

    The Solar Maximum Mission satellite's gamma-ray spectrometer has detected a line near 1.81 MeV in each of the three years (1980-1982) over which the Galactic center traversed the broad aperture of that instrument. No significant intensity variation is noted over this period. The Galactic center/anticenter intensity ratio is greater than 2.5, and the center of the emission is noted to be consistent with the location of the Galactic center. For an assumed source distribution which follows the more than 100 MeV Galactic gamma radiation, the total flux in the direction of the Galactic center and the measured energy of the line are consistent with the detection of a narrow gamma-ray line from interstellar Al-26 by HEAO 3 in 1979-1980.

  17. Gamma radiation effects on phenolics, antioxidants activity and in vitro digestion of pistachio ( Pistachia vera) hull

    NASA Astrophysics Data System (ADS)

    Behgar, M.; Ghasemi, S.; Naserian, A.; Borzoie, A.; Fatollahi, H.

    2011-09-01

    The effect of gamma radiation (10, 20, 30, 40, 50 and 60 kGy) on tannin, total phenolics, antioxidants activity and in vitro digestion of pistachio hulls has been investigated in this study. The possibility of using the radial diffusion method based on software measurement of the rings area has also been investigated in this study. The software based method in radial diffusion method showed a higher r2 (0.995) value when compared to the traditional method. Irradiation reduced the tannin content ( P<0.01) and activity of antioxidants ( P<0.05) of pistachio hull extracts but increased the total phenolic content ( P<0.05). There was no effect of gamma irradiation on the in vitro digestion of the pistachio hull. Irradiation decreased the digestion rate of the pistachio hull at the dose of 40 kGy when compared to the control. This study showed that gamma irradiation decreased tannin and antioxidants activity of pistachio hull.

  18. Des-Aspartate-Angiotensin I Attenuates Mortality of Mice Exposed to Gamma Radiation via a Novel Mechanism of Action

    PubMed Central

    Wang, Hong; Sethi, Gautam; Loke, Weng-Keong; Sim, Meng-Kwoon

    2015-01-01

    ACE inhibitors and ARBs (angiotensin receptor blockers) have been shown to attenuate radiation injuries in animal models of lethal gamma irradiation. These two classes of drug act by curtailing the actions of angiotensin II-linked inflammatory pathways that are up-regulated during gamma radiation in organ systems such as the brain, lung, kidney, and bone marrow. ACE inhibitors inhibit ACE and attenuate the formation of angiotensin II from angiotensin I; ARBs block the angiotensin AT1 receptor and attenuate the actions of angiotensin II that are elicited through the receptor. DAA-I (des-aspartate-angiotensin I), an orally active angiotensin peptide, also attenuates the deleterious actions of angiotensin II. It acts as an agonist on the angiotensin AT1 receptor and elicits responses that oppose those of angiotensn II. Thus, DAA-I was investigated for its anticipated radioprotection in gamma irradiated mice. DAA-I administered orally at 800 nmole/kg/day for 30 days post exposure (6.4 Gy) attenuated the death of mice during the 30-day period. The attenuation was blocked by losartan (50 nmole/kg/day, i.p.) that was administered sequential to DAA-I administration. This shows that the radioprotection was mediated via the angiotensin AT1 receptor. Furthermore, the radioprotection correlated to an increase in circulating PGE2 of surviving animals, and this suggests that PGE2 is involved in the radioprotection in DAA-I-treated mice. At the hematopoietic level, DAA-I significantly improved two syndromes of myelosuppression (leucopenia and lymphocytopenia), and mice pre-treated with DAA-I prior to gamma irradiation showed significant improvement in the four myelodysplastic syndromes that were investigated, namely leucopenia, lymphocytopenia, monocytopenia and thrombocytopenia. Based on the known ability of PGE2 to attenuate the loss of functional hematopoietic stem and progenitor cells in radiation injury, we hypothesize that PGE2 mediated the action of DAA-I. DAA-I completely attenuated the increase in circulating level of two inflammatory cytokines, TNFα and IL-6, in irradiated mice; and this shows that DAA-I exerted additional anti-inflammatory actions, which could also have contributed to its radioprotection. These findings show that DAA-I acts via a novel mechanism of action on the angiotensin AT1 receptor to specifically release PGE2, which mediates radioprotection in the gamma irradiated mice. PMID:26378927

  19. Breast cancer stem cells and radiation

    NASA Astrophysics Data System (ADS)

    Phillips, Tiffany Marie

    2007-12-01

    The present studies explore the response of breast cancer stem cells (BCSC's) to radiation and the implications for clinical cancer treatment. Current cancer therapy eliminates bulky tumor mass but may fail to eradicate a critical tumor initiating cell population termed "cancer stem cells". These cells are potentially responsible for tumor formation, metastasis, and recurrence. Recently cancer stem cells have been prospectively identified in various malignancies, including breast cancer. The breast cancer stem cell has been identified by the surface markers CD44+/CD24 -(low). In vitro mammosphere cultures allow for the enrichment of the cancer stem cell population and were utilized in order to study differential characteristics of BCSC's. Initial studies found that BCSC's display increased radiation resistance as compared to other non-stem tumor cells. This resistance was accompanied by decreased H2AX phosphorylation, decreased reactive oxygen species formation, and increased phosphorylation of the checkpoint protein Chk1. These studies suggest differential DNA damage and repair within the BCSC population. Studies then examined the consequences of fractionated radiation on the BCSC population and found a two-fold increase in BCSC's following 5 x 3Gy. This observation begins to tie cancer stem cell self-renewal to the clinical stem cell phenomenon of accelerated repopulation. Accelerated repopulation is observed when treatment gaps increase between sequential fractions of radiotherapy and may be due to cancer stem cell symmetric self-renewal. The balance between asymmetric and symmetric stem cell division is vital for proper maintenance; deregulation is likely linked to cancer initiation and progression. The developmental Notch-1 pathway was found to regulate BCSC division. Over-expressing the constitutively active Notch-1-ICD in MCF7 cells produced an increase in the BCSC population. Additionally, radiation was observed to increase the expression of the Notch-1 ligand, Jagged-1, and this was complemented by radiation induced Notch-1 activation. Studies also linked hypoxia and BCSC renewal through Epo signaling. Treatment with rhEpo induced an increase in BCSC's, which again was due to rhEpo induced Jagged-1 expression and subsequent Notch-1 activation. This thesis suggests that radiation and rhEpo induce Jagged-1 expression in non-stem cells, which then induce Notch-1 activation in adjacent stem cells, and results in symmetric cancer stem cell self-renewal.

  20. A new, passive dosemeter for gamma, beta and neutron radiations.

    PubMed

    Jones, L A; Stokes, R P

    2011-03-01

    The Defence Science and Technology Laboratory (Dstl) provides personal radiation dosimetry to the UK Ministry of Defence. Dstl has recently developed a dosemeter that is based on a combination of thermoluminescent and etched-track detectors. The Dstl Combined Dosemeter is capable of assessing doses due to photons, beta particles and neutrons. This paper presents the laboratory type testing results for the Combined Dosemeter, and also describes the procedure for calibrating the dosemeter for use in workplace neutron fields. The Combined Dosemeter meets the type test requirements that are relevant to its intended applications, and gives neutron doses that are within 50% of the true dose in the workplaces in which it is used, even when the wearer has the potential to be exposed to a variety of neutron spectra (e.g. on board nuclear-powered submarines). PMID:21346288

  1. LDEF solar cell radiation effects analysis

    NASA Technical Reports Server (NTRS)

    Rives, Carol J.; Azarewicz, Joseph L.; Massengill, Lloyd

    1993-01-01

    Because of the extended time that the Long Duration Exposure Facility (LDEF) mission stayed in space, the solar cells on the satellite experienced greater environments than originally planned. The cells showed an overall degradation in performance that is due to the combined effects of the various space environments. The purpose of this analysis is to calculate the effect of the accumulated radiation on the solar cells, thereby helping Marshall Space Flight Center (MSFC) to unravel the relative power degradation from the different environments.

  2. Lignocellulolytic mutants of Pleurotus ostreatus induced by gamma-ray radiation and their genetic similarities

    NASA Astrophysics Data System (ADS)

    Lee, Y.-K.; Chang, H.-H.; Kim, J.-S.; Kim, J. K.; Lee, K.-S.

    2000-02-01

    To induce the lignocellulolytic mutants of Pleurotus ostreatus, the mycelia were irradiated by gamma-ray radiation to doses of 1-2 kGy. Five strains were isolated by the criteria of clamp connection, fruiting body formation, growth rate and activities of extracellular enzymes. All isolated strains were able to form the fruiting bodies and grew similarly to the control. The extracellular enzymes activities in liquid media of isolated strains were up to 10 times higher than the control. Genetic similarities of the isolated strains ranged from 64.4% to 93.3% of the control. From these results, it seems that the genetic diversity of P. ostreatus could be changed and useful strains be induced by gamma-ray radiation to recycle or reuse biowastes.

  3. Three-dimensional radiation dosimetry for gamma knife using a gel dosimeter

    NASA Astrophysics Data System (ADS)

    Hussain, Kazi Muazzam

    The use of three-dimensional radiation dosimetry has been limited. With the use of water phantoms and ionization chambers, it has been possible to determine three dimensional dose distributions on a gross scale for cobalt 60 and linear accelerator sources. This method has been somewhat useful for traditional radiotherapy. There is, however, a need for more precise dosimetry, particularly with stereotactic radiosurgery. Most gamma knife facilities use either thermoluminescant dosimetry or film, neither of which provides three dimensional dose distributions. To overcome this limitation, we have developed a gel dosimetry system that relies on the production of a ferric ion-xylenol orange colored complex. This work demonstrates the use of laser light and a detector to quantify radiation-induced colorimetric changes in absorbance for the gel dosimeter. The absorbance has been reconstructed by the back projection technique to demonstrate the applicability of the gel dosimeter to gamma knife 3D-dose distributions.

  4. In situ gamma-ray spectrometry: A tutorial for environmental radiation scientists

    SciTech Connect

    Miller, K.M.; Shebell, P.

    1993-10-01

    This tutorial is intended for those in the environmental field who perform assessments in areas where there is radioactive contamination in the surface soil. Techniques will be introduced for performing on-site quantitative measurements of gamma radiation in the environment using high resolution germanium detectors. A basic understanding of ionizing radiation principles is assumed; however, a detailed knowledge of gamma spectrometry systems is not required. Emphasized is the practical end of operations in the field and the conversion of measured full absorption peak count rates in a collected spectrum to meaningful radiological quantities, such as the concentration of a radionuclide in the soil, activity per unit area, and dose rate in the air. The theory of operation and calibration procedures will be covered in detail to provide the necessary knowledge to adapt the technique to site-specific problems. Example calculations for detector calibration are also provided.

  5. A new natural gamma radiation measurement system for marine sediment and rock analysis

    NASA Astrophysics Data System (ADS)

    Vasiliev, M. A.; Blum, P.; Chubarian, G.; Olsen, R.; Bennight, C.; Cobine, T.; Fackler, D.; Hastedt, M.; Houpt, D.; Mateo, Z.; Vasilieva, Y. B.

    2011-11-01

    A new high-efficiency and low-background system for the measurement of natural gamma radioactivity in marine sediment and rock cores retrieved from beneath the seabed was designed, built, and installed on the JOIDES Resolution research vessel. The system includes eight large NaI(Tl) detectors that measure adjacent intervals of the core simultaneously, maximizing counting times and minimizing statistical error for the limited measurement times available during drilling expeditions. Effect to background ratio is maximized with passive lead shielding, including both ordinary and low-activity lead. Large-area plastic scintillator active shielding filters background associated with the high-energy part of cosmic radiation. The new system has at least an order of magnitude higher statistical reliability and significantly enhances data quality compared to other offshore natural gamma radiation (NGR) systems designed to measure geological core samples. Reliable correlations and interpretations of cored intervals are possible at rates of a few counts per second.

  6. Public exposure due to external gamma background radiation in boundary areas of Iran.

    PubMed

    Pooya, S M Hosseini; Dashtipour, M R; Enferadi, A; Orouji, T

    2015-09-01

    A monitoring program in boundary areas of a country is an appropriate way to indicate the level of public exposure. In this research, gamma background radiation was measured using TL dosimeters at 12 boundary areas as well as in the capital city of Iran during the period 2010 to 2011. The measurements were carried out in semi-annual time intervals from January to June and July to December in each year. The maximum average dose equivalent value measured was approximately 70 μSv/month for Tehran city. Also, the average dose values obtained were less than 40 μSv/month for all the cities located at the sea level except that of high level natural radiation area of Ramsar, and more than 55 μSv/month for the higher elevation cities. The public exposure due to ambient gamma dose equivalent in Iran is within the levels reported by UNSCEAR. PMID:26057985

  7. Development and characterization of starch nanoparticles by gamma radiation: potential application as starch matrix filler.

    PubMed

    Lamanna, Melisa; Morales, No J; Garca, Nancy Lis; Goyanes, Silvia

    2013-08-14

    Gamma radiation arises as an advantageous alternative to obtain starch nanoparticles given its low cost, simple methodology and scalability. Starch nanoparticles (SNP) with sizes around 20 and 30 nm were obtained applying a dose of 20 kGy from cassava (CNP-?) and waxy maize (WNP-?) starch, respectively. They showed the same thermal degradation behavior and their maximum mass loss zone was similar to those nanoparticles obtained from acid hydrolysis (WNP-h). Additionally, CNP-? and WNP-? were used as nanofillers in a cassava matrix. Increments of 102% in storage modulus were obtained with the addition of only 2.5 wt.% of WNP-?, showing that gamma radiation is a successful methodology to obtain SNP able to be used as starch reinforcement. PMID:23769521

  8. The priming effect of glucose in soil sterilized by gamma-radiation and reinoculated with Cellulomonas sp.

    PubMed

    Kunc, F

    1980-01-01

    Mineralization of native organic matter and U-14C-glucose was followed by measuring the formation of CO2 and its radioactivity in chernozem soil presterilized by gamma-radiation and inoculated with a washed suspension of Cellulomonas sp. cells. The introduced bacteria mineralized the soil organic component to a higher extent in variants enriched with glucose. This so-called priming effect of glucose was observed also in the presence of chloramphenicol, inhibiting the growth of the bacteria. The increased mineralization of the native soil organic fraction was also detected in samples that were not enriched with glucose when the bacterial suspension was first disintegrated ultrasonically and the material then used for the inoculation. Possible participation of phenomena of the type of cometabolism and activation of cell membrane transport mechanisms on the occurrence of the priming effect of glucose in the soil is discussed. PMID:6247255

  9. Young gamma-ray pulsar: from modeling the gamma-ray emission to the particle-in-cell simulations of the global magnetosphere

    NASA Astrophysics Data System (ADS)

    Brambilla, Gabriele; Kalapotharakos, Constantions; Timokhin, Andrey; Kust Harding, Alice; Kazanas, Demosthenes

    2016-04-01

    Accelerated charged particles flowing in the magnetosphere produce pulsar gamma-ray emission. Pair creation processes produce an electron-positron plasma that populates the magnetosphere, in which the plasma is very close to force-free. However, it is unknown how and where the plasma departs from the ideal force-free condition, which consequently inhibits the understanding of the emission generation. We found that a dissipative magnetosphere outside the light cylinder effectively reproduces many aspects of the young gamma-ray pulsar emission as seen by the Fermi Gamma-ray Space Telescope, and through particle-in-cell simulations (PIC), we started explaining this configuration self-consistently. These findings show that, together, a magnetic field structure close to force-free and the assumption of gamma-ray curvature radiation as the emission mechanism are strongly compatible with the observations. Two main issues from the previously used models that our work addresses are the inability to explain luminosity, spectra, and light curve features at the same time and the inconsistency of the electrodynamics. Moreover, using the PIC simulations, we explore the effects of different pair multiplicities on the magnetosphere configurations and the locations of the accelerating regions. Our work aims for a self-consistent modeling of the magnetosphere, connecting the microphysics of the pair-plasma to the global magnetosphere macroscopic quantities. This direction will lead to a greater understanding of pulsar emission at all wavelengths, as well as to concrete insights into the physics of the magnetosphere.

  10. New decay branches of the radiative capture reaction {sup 12}C({sup 16}O,{gamma}){sup 28}Si

    SciTech Connect

    Lebhertz, D.; Courtin, S.; Haas, F.; Salsac, M.-D.; Beck, C.; Michalon, A.; Rousseau, M.; Marley, P. L.; Glover, R. G.; Kent, P. E.; Hutcheon, D. A.; Davis, C.; Pearson, J. E.

    2009-01-28

    Resonances in the {sup 12}C({sup 16}O,{gamma}){sup 28}Si radiative capture process at energies around the Coulomb barrier have been probed using the very selective 0 deg. Dragon spectrometer at Triumf and its associated BGO {gamma}-array. For the first time the full level scheme involved in this process has been measured and shows previously unobserved {gamma}-decay to doorway states around 11 MeV in {sup 28}Si.

  11. The high-energy diffuse cosmic gamma-ray background radiation from blazars

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.; Salamon, M. H.; Malkan, M. A.

    1993-01-01

    We predict the spectrum and flux of the high-energy diffuse cosmic gamma-ray background radiation produced by blazars. Our calculations are based on the Compton Observatory EGRET observations of high-energy gamma-rays from these objects, the Whipple observation of TeV gamma-rays from Mrk 421, and radio population studies of flat-spectrum radio sources. Our statistical analysis gives a result consistent with a linear correlation. We then use the radio luminosity function and redshift evolution to calculate the gamma-ray background. We find that blazars cannot account for the flux level or steep spectrum of the background observed by SAS 2 in the sub-GeV range, but could likely provide the dominant background component in the multi-GeV energy range and above. We predict a differential photon spectral index for this component of about 2 up to about 10 GeV. Above that energy, the spectrum should gradually steepen owing to pair production by interactions of the gamma-rays with intergalactic infrared photons. Using the calculations of this effect by Stecker et al. (1992), we estimate a spectral index of about 3.5 for energies above a TeV.

  12. Celestial diffuse gamma radiation above 30 MeV observed by SAS-2

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Kniffen, D. A.; Hartman, R. C.

    1973-01-01

    The Small Astronomy Satellite (SAS)-2, launched on November 15, 1972, carried into orbit a 32-deck magnetic-core digitized spark chamber gamma ray telescope to study celestial gamma radiation in the energy range above 30 MeV. In the study of several regions with b sub 2 15 deg, a finite, diffuse flux of gamma rays with a steep energy spectrum in the energy region from 35 to 200 MeV is observed. Representing the energy spectrum by a power law of the form dJ/dE = AE to - alpha power over this energy range, alpha is found along with the integral flux above 100 MeV. Combining this result with existing low energy gamma ray data yields an energy spectrum which is not a simple power law in energy, as in the X-ray region, but which demonstrates first an increase and then a decrease in slope, consistent within uncertainties with that predicted by cosmological theories, including the continuous production of high energy gamma rays primarily from neutral pi mesons throughout the history of the universe.

  13. Evaluation of the in vivo genotoxic effects of gamma radiation on the peripheral blood leukocytes of head and neck cancer patients undergoing radiotherapy.

    PubMed

    Kadam, Samit B; Shyama, Soorambail K; Almeida, Valentine G

    2013-04-15

    The present study aimed to evaluate the genotoxic effects of ionizing radiation on non-target cells of Head and Neck Squamous Cell Carcinoma (HNSCC) patients exposed to various cumulative doses of gamma rays during radiotherapy. The ten patients (P1-P10) were treated with cobalt 60 gamma radiation (External Beam Radiotherapy) for a period of five to six weeks with a daily fraction of 2Gy for 5 days each week. The genotoxic effects of radiation (single strand breaks - SSBs) in these patients were analyzed using the alkaline single cell gel electrophoresis (SCGE) technique, with the Olive Tail Moment (OTM) as the critical parameter. A sample of each patient's peripheral blood before starting with radiotherapy (pre-therapy) served as the control, and blood collected at weekly time intervals during the course of the radiotherapy served as treated (10, 20, 30, 40, 50 and 60Gy) samples. In vivo radiosensitivity of these patients, as indicated by SSB's after the cumulative radiation doses at the various times, was assessed using Student's t-test. Significant DNA damage relative to the individual patient's pre-therapy baseline data was observed in all patients. Inter-individual variation of the genotoxic effects was analyzed using two-way ANOVA. The correlation between doses for the means of smoker and non-smoker patients was calculated using the Pearson test. The results of this study may indicate the need to reduce the daily radiotherapy dose further to prevent genotoxic effects on non-target cells, thus improving safety. Furthermore, these results may indicate that the estimation of DNA damage following exposure to a gamma radiation, as measured by the comet assay in whole blood leukocytes, can be used to screen human populations for radiation-induced genetic damage at the molecular level. PMID:23370449

  14. Activation of PPAR{gamma} is not involved in butyrate-induced epithelial cell differentiation

    SciTech Connect

    Ulrich, S.; Waechtershaeuser, A.; Loitsch, S.; Knethen, A. von; Bruene, B.; Stein, J. . E-mail: j.stein@em.uni-frankfurt.de

    2005-10-15

    Histone deacetylase-inhibitors affect growth and differentiation of intestinal epithelial cells by inducing expression of several transcription factors, e.g. Peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) or vitamin D receptor (VDR). While activation of VDR by butyrate mainly seems to be responsible for cellular differentiation, the activation of PPAR{gamma} in intestinal cells remains to be elucidated. The aim of this study was to determine the role of PPAR{gamma} in butyrate-induced cell growth inhibition and differentiation induction in Caco-2 cells. Treatment with PPAR{gamma} ligands ciglitazone and BADGE (bisphenol A diglycidyl) enhanced butyrate-induced cell growth inhibition in a dose- and time-dependent manner, whereas cell differentiation was unaffected after treatment with PPAR{gamma} ligands rosiglitazone and MCC-555. Experiments were further performed in dominant-negative PPAR{gamma} mutant cells leading to an increase in cell growth whereas butyrate-induced cell differentiation was again unaffected. The present study clearly demonstrated that PPAR{gamma} is involved in butyrate-induced inhibition of cell growth, but seems not to play an essential role in butyrate-induced cell differentiation.

  15. Sewage sludge pasteurization by gamma radiation: A Canadian demonstration project — 1988-91

    NASA Astrophysics Data System (ADS)

    Swinwood, Jean F.; Wilson, Bruce K.

    Nordion International Inc. and a Canadian city, in cooperation with the Federal & Provincial Ministries of the Environment, began a project in 1988 to construct and operate a commercial-scale sewage sludge pasteurization facility using gamma radiation technology. The facility is scheduled to begin operations in 1991. This paper discusses the objectives and scope of the project, the design of the irradiation system, and the plans to market the pasteurized sludge as a high-value, organic soil conditioner and fertilizer.

  16. Observation of the radiative decay J/psi. -->. gamma. eta. pi pi

    SciTech Connect

    Newman-Holmes, C.

    1982-09-01

    The radiative decay J/psi ..-->.. ..gamma.. eta ..pi pi.. has been observed in data taken with the Crystal Ball detector at the SPEAR e/sup +/e/sup -/ storage ring. In addition to the well-known eta', the eta ..pi pi.. mass spectrum shows a broad enhancement centered at approx. 1700 MeV. There is no explicit evidence for the l(1440) in the eta ..pi pi.. mass spectrum.

  17. A cylindrical xenon ionization chamber detector for high resolution, room temperature gamma radiation spectroscopy

    NASA Astrophysics Data System (ADS)

    Tepper, Gary; Losee, Jon; Palmer, Robert

    A 0.75 l gridded cylindrical ionization chamber gamma radiation detector using highly purified xenon near the critical point as the detection medium is described. The detector operates at room temperature with a noise subtracted intrinsic energy resolution of 1.8% at 662 keV. The detector design and performance variables are discussed in comparison to previous planar and cylindrical xenon detectors.

  18. Radiation and taxol effects on synchronized human cervical carcinoma cells

    SciTech Connect

    Geard, C.R.; Jones, J.M. )

    1994-06-15

    The purpose was to evaluate the effectiveness of the plant derived chemotherapeutic agent taxol alone and in combination with ionizing radiation on synchronous and asynchronous human cervical carcinoma cells and to define the mechanistic basis for this cytotoxic response. Asynchronous and synchronous cells (obtained by modified mitotic shake-off) derived from carcinomas of the human uterine cervix were treated with a range of concentrations of taxol (0, 1.0, 2.5, 5.0, 10.0, and 20.0 nM) for either 8, 24, or 48 h. Synchronized cell cycling was evaluated by counting mitotic indices and by uptake of bromodeoxyuridine (BrdUrd). Cells were irradiated ([sup 137]Cs [gamma] rays at 1.12 Gy/min) alone and after taxol treatment and plating efficiencies and radiosensitivity determined. Taxol treatment resulted in a dose time dependent loss of colony forming ability with 10 nM for 24 h producing about 10% cell survival. Irradiating taxol treated cells resulted in a strictly additive response in contrast to previous supra-additive results with astrocytoma and melanoma cells. Mitotically synchronized cells rapidly moved into G[sub 1] phase with a second mitotic peak at 28 h (total cycle time). Taxol treatment resulted in a continued accumulation of mitoses, and a failure and/or delay of entry of a fraction of cells into S phase after a G[sub 1] phase of at least 10 h. That is, taxol effects cell cycling at a stage other than G[sub 2]/M. Irradiating (3 Gy) synchronized cells showed a 10-fold variation in sensitivity, with mitosis as the most sensitive phase with taxol alone resulting in some cytotoxicity and combined effects additive or less than additive. This may explain the failure to obtain taxol radiosensitization with these cells and it may indicate that taxol has a multiplicity of actions with differences in effectiveness likely between cells of different origins. 24 refs., 5 figs.

  19. Gamma-radiation-induced wood-plastic composites from Syrian tree species

    NASA Astrophysics Data System (ADS)

    Bakraji, Elias Hanna; Salman, Numan; Al-kassiri, Haroun

    2001-05-01

    Wood-plastic composites (WPC) have been prepared with five low-grade woods, native to Syria, using three monomer systems; acrylamide, butylmethacrylate, and styrene, with methanol as the swelling solvent. Polymerization was induced at various radiation doses (10, 20, and 30 kGy) at a dose rate of 3.5 kGy/h using a 60Co gamma radiation source. Some physical properties of WPC, namely polymer loading and compression strength have been measured. The polymer loading decreases approximately with increasing density of the wood species used.

  20. Radiosensitivity of nall human melanoma transplanted into nude mice: repair, reoxygenation and dose fractionation. [Gamma radiation

    SciTech Connect

    Guichard, M.; Malaise, E.P.

    1982-06-01

    Split dose and fractionated ..gamma..-rays experiments have been performed on a human melanoma transplanted into nude mice using an in vitro colony assay. Repair of potentially lethal damage observed after a single dose of 20 Gy was found to no longer occur when 7 daily doses of 2.5 Gy were administered. In split-dose experiments, the increase in survival level probably can not be explained by repair of sublethal damage. When a single high dose of radiation is administered a certain reoxygenation is observed; however, there is no reoxygenation when low radiation doses are delivered daily.

  1. Method for detecting water equivalent of snow using secondary cosmic gamma radiation

    DOEpatents

    Condreva, Kenneth J.

    1997-01-01

    Water equivalent of accumulated snow determination by measurement of secondary background cosmic radiation attenuation by the snowpack. By measuring the attentuation of 3-10 MeV secondary gamma radiation it is possible to determine the water equivalent of snowpack. The apparatus is designed to operate remotely to determine the water equivalent of snow in areas which are difficult or hazardous to access during winter, accumulate the data as a function of time and transmit, by means of an associated telemetry system, the accumulated data back to a central data collection point for analysis. The electronic circuitry is designed so that a battery pack can be used to supply power.

  2. Degradation of Biochemical Activity in Soil Sterilized by Dry Heat and Gamma Radiation

    NASA Technical Reports Server (NTRS)

    Shih, K. L.; Souza, K. A.

    1978-01-01

    The effect of soil sterilization by dry heat (0.08% relative humidity), gamma radiation, or both on soil phosphatase, urease, and decarboxylase activity was studied. Soil sterilized by a long exposure to dry heat at relatively low temperatures (eight weeks at 100.5 C) retained higher activities than did soil exposed to a higher temperature (two weeks at 124.5 C), while all activity was destroyed by four days at 148.5 C. Sterilization with 7.5 Mrads destroyed less activity than did heat sterilization. The effect of several individually nonsterizing doses of heat radiation is described.

  3. Gamma radiation-induced blue shift of resonance peaks of Bragg gratings in pure silica fibres

    NASA Astrophysics Data System (ADS)

    Faustov, A. V.; Gusarov, A. I.; Mégret, P.; Wuilpart, M.; Kinet, D.; Zhukov, A. V.; Novikov, S. G.; Svetukhin, V. V.; Fotiadi, A. A.

    2016-02-01

    We report the first observation of a significant gamma radiation-induced blue shift of the reflection/transmission peak of fibre Bragg gratings inscribed into pure-silica core fibres via multiphoton absorption of femtosecond pulses. At a total dose of ~100 kGy, the shift is ~20 pm. The observed effect is attributable to the ionising radiation-induced decrease in the density of the silica glass when the rate of colour centre formation is slow. We present results of experimental measurements that provide the key parameters of the dynamics of the gratings for remote dosimetry and temperature sensing.

  4. Method for detecting water equivalent of snow using secondary cosmic gamma radiation

    DOEpatents

    Condreva, K.J.

    1997-01-14

    Water equivalent of accumulated snow determination by measurement of secondary background cosmic radiation attenuation by the snowpack. By measuring the attenuation of 3-10 MeV secondary gamma radiation it is possible to determine the water equivalent of snowpack. The apparatus is designed to operate remotely to determine the water equivalent of snow in areas which are difficult or hazardous to access during winter, accumulate the data as a function of time and transmit, by means of an associated telemetry system, the accumulated data back to a central data collection point for analysis. The electronic circuitry is designed so that a battery pack can be used to supply power. 4 figs.

  5. Gamma radiation grafted polymers for immobilization of Brucella antigen in diagnostic test studies

    NASA Astrophysics Data System (ADS)

    Docters, E. H.; Smolko, E. E.; Suarez, C. E.

    The radiation grafting process has a wide field of industrial applications, and in the recent years the immobilization of biocomponents in grafted polymeric materials obtained by means of ionizing radiations is a new and important contribution to biotechnology. In the present work, gamma preirradiation grafting method was employed to produce acrylics hydrogels onto polyethylene (PE), polyvinyl chloride (PVC) and polystyrene (PS). Two monomers were used to graft the previously mentioned polymers: methacrylic acid (MAAc) and acrylamide (AAm), and several working conditions were considered as influencing the degree of grafting. All this grafted polymers were used to study the possibility of a subsequent immobilization of Brucella antigen (BAg) in diagnostic test studies (ELISA).

  6. High linear-energy-transfer radiation can overcome radioresistance of glioma stem-like cells to low linear-energy-transfer radiation

    PubMed Central

    Hirota, Yuki; Masunaga, Shin-Ichiro; Kondo, Natsuko; Kawabata, Shinji; Hirakawa, Hirokazu; Yajima, Hirohiko; Fujimori, Akira; Ono, Koji; Kuroiwa, Toshihiko; Miyatake, Shin-Ichi

    2014-01-01

    Ionizing radiation is applied as the standard treatment for glioblastoma multiforme (GBM). However, radiotherapy remains merely palliative, not curative, because of the existence of glioma stem cells (GSCs), which are regarded as highly radioresistant to low linear-energy-transfer (LET) photons. Here we analyzed whether or not high-LET particles can overcome the radioresistance of GSCs. Glioma stem-like cells (GSLCs) were induced from the GBM cell line A172 in stem cell culture medium. The phenotypes of GSLCs and wild-type cells were confirmed using stem cell markers. These cells were irradiated with 60Co gamma rays or reactor neutron beams. Under neutron-beam irradiation, high-LET proton particles can be produced through elastic scattering or nitrogen capture reaction. Radiosensitivity was assessed by a colony-forming assay, and the DNA double-strand breaks (DSBs) were assessed by a histone gamma-H2AX focus detection assay. In stem cell culture medium, GSLCs could form neurosphere-like cells and express neural stem cell markers (Sox2 and Musashi) abundantly in comparison with their parental cells. GSLCs were significantly more radioresistant to gamma rays than their parental cells, but neutron beams overcame this resistance. There were significantly fewer gamma-H2AX foci in the A172 GSLCs 24 h after irradiation with gamma rays than in their parental cultured cells, while there was no apparent difference following neutron-beam irradiation. High-LET radiation can overcome the radioresistance of GSLCs by producing unrepairable DNA DSBs. High-LET radiation therapy might have the potential to overcome GBM's resistance to X-rays in a clinical setting. PMID:23955054

  7. Secondary metabolite perturbations in Phaseolus vulgaris leaves due to gamma radiation.

    PubMed

    Ramabulana, T; Mavunda, R D; Steenkamp, P A; Piater, L A; Dubery, I A; Madala, N E

    2015-12-01

    Oxidative stress is a condition in which the balance between the production and elimination of reactive oxygen species (ROS) is disturbed. However, plants have developed a very sophisticated mechanism to mitigate the effect of ROS by constantly adjusting the concentration thereof to acceptable levels. Electromagnetic radiation is one of the factors which results in oxidative stress. In the current study, ionizing gamma radiation generated from a Cobalt-60 source was used to induce oxidative stress in Phaseolus vulgaris seedlings. Plants were irradiated with several radiation doses, with 2 kGy found to be the optimal, non-lethal dose. Metabolite distribution patterns from irradiated and non-irradiated plants were analyzed using UHPLC-qTOF-MS and multivariate data models such as principal component analysis (PCA) and orthogonal projection to latent structures discriminate analysis (OPLS-DA). Metabolites such as hydroxycinnamic phenolic acids, flavonoids, terpenes, and a novel chalcone were found to be perturbed in P. vulgaris seedlings treated with the aforementioned conditions. The results suggest that there is a compensatory link between constitutive protectants and inducible responses to injury as well as defense against oxidative stress induced by ionizing radiation. The current study is also the first to illustrate the power of a metabolomics approach to decipher the effect of gamma radiation on crop plants. PMID:26512968

  8. Diffuse gamma radiation. [intensity, energy spectrum and spatial distribution from SAS 2 observations

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Simpson, G. A.; Thompson, D. J.

    1978-01-01

    Results are reported for an investigation of the intensity, energy spectrum, and spatial distribution of the diffuse gamma radiation detected by SAS 2 away from the galactic plane in the energy range above 35 MeV. The gamma-ray data are compared with relevant data obtained at other wavelengths, including 21-cm emission, radio continuum radiation, and the limited UV and radio information on local molecular hydrogen. It is found that there are two quite distinct components to the diffuse radiation, one of which shows a good correlation with the galactic matter distribution and continuum radiation, while the other has a much steeper energy spectrum and appears to be isotropic at least on a coarse scale. The galactic component is interpreted in terms of its implications for both local and more distant regions of the Galaxy. The apparently isotropic radiation is discussed partly with regard to the constraints placed on possible models by the steep energy spectrum, the observed intensity, and an upper limit on the anisotropy.

  9. Durability and shielding performance of borated Ceramicrete coatings in beta and gamma radiation fields

    NASA Astrophysics Data System (ADS)

    Wagh, Arun S.; Sayenko, S. Yu.; Dovbnya, A. N.; Shkuropatenko, V. A.; Tarasov, R. V.; Rybka, A. V.; Zakharchenko, A. A.

    2015-07-01

    Ceramicrete™, a chemically bonded phosphate ceramic, was developed for nuclear waste immobilization and nuclear radiation shielding. Ceramicrete products are fabricated by an acid-base reaction between magnesium oxide and mono potassium phosphate. Fillers are used to impart desired properties to the product. Ceramicrete's tailored compositions have resulted in several commercial structural products, including corrosion- and fire-protection coatings. Their borated version, called Borobond™, has been studied for its neutron shielding capabilities and is being used in structures built for storage of nuclear materials. This investigation assesses the durability and shielding performance of borated Ceramicrete coatings when exposed to gamma and beta radiations to predict the composition needed for optimal shielding performance in a realistic nuclear radiation field. Investigations were conducted using experimental data coupled with predictive Monte Carlo computer model. The results show that it is possible to produce products for simultaneous shielding of all three types of nuclear radiations, viz., neutrons, gamma-, and beta-rays. Additionally, because sprayable Ceramicrete coatings exhibit excellent corrosion- and fire-protection characteristics on steel, this research also establishes an opportunity to produce thick coatings to enhance the shielding performance of corrosion and fire protection coatings for use in high radiation environment in nuclear industry.

  10. Cell death (apoptosis) in mouse intestine after continuous irradiation with gamma rays and with beta rays from tritiated water

    SciTech Connect

    Ijiri, K.

    1989-04-01

    Apoptosis is a pattern of cell death involving nuclear pycnosis, cytoplasmic condensation, and karyorrhexis. Apoptosis induced by continuous irradiation with gamma rays (externally given by a 137Cs source) or with beta rays (from tritiated water injected ip) was quantified in the crypts of two portions of mouse bowel, the small intestine and descending colon. The time-course change in the incidence of apoptosis after each type of radiation could be explained on the basis of the innate circadian rhythm of the cells susceptible to apoptotic death and of the excretion of tritiated water (HTO) from the body. For 6-h continuous gamma irradiation at various dose rates (0.6-480 mGy/h) and for 6 h after injection of HTO of various radioactivities (0.15-150 GBq per kg body wt), the relationships between dose and incidence of apoptosis were obtained. Survival curves were then constructed from the curves for dose vs incidence of apoptosis. For the calculation of the absorbed dose from HTO, the water content both of the mouse body and of the cells was assumed to be 70%. One megabecquerel of HTO per mouse (i.e., 40 MBq/kg body wt) gave a dose rate of 0.131 mGy/h. The mean lethal doses (D0) were calculated for gamma rays and HTO, and relative biological effectiveness values of HTO relative to gamma rays were obtained. The D0 values for continuous irradiation with gamma rays were 210 mGy for small intestine and 380 mGy for descending colon, and the respective values for HTO were 130 and 280 mGy, indicating the high radiosensitivity of target cells for apoptotic death. The relative biological effectiveness of HTO relative to 137Cs gamma rays for cell killing in both the small intestine and the descending colon in the mouse was 1.4-2.1.

  11. Resistance of a cultured fish cell line (CAF-MM1) to. gamma. irradiation

    SciTech Connect

    Mitani, H.; Etoh, H.; Egami, N.

    1982-02-01

    Fish are generally more resistant to whole-body ionizing radiation than mammals. To study the radiosensitivity of fish in vitro, CAF-MM1 cells derived from the fin of the goldfish, Carassius auratus, were used. The survival parameters of CAF-MM1 obtained after ..gamma.. irradiation at 26/sup 0/C were 325 rad for D/sub o/, 975 rad for Dq, and 15 for n. No mammalian cell line with such a low sensitivity in the presence of O/sub 2/ has been reported. It was found that the large initial shoulder of the survival curve was paralleled by substantial repair of sublethal damage as evidenced by split-dose experiments. This low sensitivity to ..gamma.. irradiation did not change upon the administration of caffeine or postirradiation illumination, although these treatments were effective after uv irradiation. The decrease in the mitotic index in CAF-MM1 occurred immediately after irradiation, and it recovered within a very short time. This indicated that the duration of G2 arrest was shorter than that observed in mammalian cells. The data also suggest that the resistance of fish to whole-body irradiation is attributable to resistance at the cellular level.

  12. Radiation Therapy

    MedlinePlus

    ... Radiation (also called x-rays, gamma rays, or photons) either kills tumor cells directly or interferes with ... treatment per day, five days a week, for two to seven weeks. Potiential Side Effects Most people ...

  13. [Radiation-induced, irreparable, hereditary changes in cells promoting their neoplastic transformation].

    PubMed

    Kuzin, A M; Vagabova, M E; Iurov, S S

    1988-01-01

    In experiments with model plant tumors (Kalanchoe-ti plasmid Agrobact. tumefaciens C-58D) it was shown that exposure of the recipient plant to low-level gamma-radiation of 2 Gy induced changes in cells that were not repaired over two months promoting tumoral transformations in them. Those changes were shown to persist in the offspring of the exposed somatic cells. PMID:3363091

  14. Atypical radiation response of SCID cells

    NASA Astrophysics Data System (ADS)

    Chawapun, Nisa

    Murine SCID (severe combined immune deficiency) cells are well known for their defect in DNA double-strand break repair and in variable(diversity)joining [V(D)J] recombination due to a mutation in a catalytic subunit of DNA-dependent protein kinase (DNA-PKcs). As a consequence, scid cells are hypersensitive to ionizing radiation. The present study showed that asynchronous populations of scid cells were about two-fold more sensitive than Balb/c with respect to cell killing and the defect in scid cells was corrected by complementation with human chromosome 8. Analysis of the survival of synchronized populations as a function of the cell cycle revealed that while scid cells were hypersensitive in all cell cycle phases compared to wild-type cells, this hypersensitivity is even more pronounced in G1 phase. The hypersensitivity reduced as the cells progressed into S phase suggested that homologous recombination repair plays a role. The results imply that there are at least two pathways for the repair of DSB DNA, consistent with a model previously proposed by others. The scid cells were also more sensitive to UVC light (254 nm) killing as compared to wild type cells by clonogenic survival. Using a host cell reactivation (HCR) assay to study the nucleotide excision repair (NER) which is the major repair pathway for UV-photoproducts, the results showed that NER in scid cells was not as efficient as CB- 17. This suggests that DNA-PK is involved in NER as well as non-homologous end-joining (NHEJ) DSB repair which is responsible for ionizing radiation sensitivity in scid cells. Repair in scid cells was not totally absent as shown by low dose rate sparing of cell killing after exposure to 137Cs γ-rays at dose rate of 0.6 cGy/h, 1.36 cGy/h, 6 cGy/h as compared to high dose rate at 171 cGy/min, although this phenomenon could be explained partly by proliferation. However, for radiation induced transformation, no significant dose rate effect was seen. A plot of transformation versus survival revealed that the transformation induction was inversely proportional to radiation dose rate. Lower dose rates were more effective in inducing transformation in scid cells. This finding could lead to the influence of cancer risk estimation in an irradiated population consisting of a subpopulation(s) with genetic disorders predisposing those individuals to cancer.

  15. Age and radiation sensitivity of rat mammary clonogenic cells.

    PubMed

    Shimada, Y; Yasukawa-Barnes, J; Kim, R Y; Gould, M N; Clifton, K H

    1994-01-01

    The relative risk of breast cancer is very high among women who were exposed to ionizing radiation during or before puberty. In the current studies, the surviving fractions of clonogenic mammary cells of groups of virgin rats were estimated after single exposures to 137Cs gamma rays at intervals from 1 to 12 weeks after birth. The radiosensitivity of clonogens from prepubertal rats was high and changed with the onset of puberty at between 4 and 6 weeks of age. By this time, the increase in the size of the clonogenic cell subpopulation was slowing and differentiation of terminal mammary end buds and alveolar structures was occurring. Analysis of the relationship of clonogen survival and radiation dose according to the alpha/beta model showed that the exponential alpha D term predominated at the second and fourth weeks of age. By the eighth week of age, the beta D2 term had come to predominate and the survival curve had a pronounced initial convex shoulder. Further experiments are required to determine whether there is an association between the high sensitivity of the prepubertal and pubertal mammary clonogens to radiation killing and a high susceptibility to radiogenic initiation of cancer. PMID:8265781

  16. The TP53 dependence of radiation-induced chromosome instability in human lymphoblastoid cells

    NASA Technical Reports Server (NTRS)

    Schwartz, Jeffrey L.; Jordan, Robert; Evans, Helen H.; Lenarczyk, Marek; Liber, Howard

    2003-01-01

    The dose and TP53 dependence for the induction of chromosome instability were examined in cells of three human lymphoblastoid cell lines derived from WIL2 cells: TK6, a TP53-normal cell line, NH32, a TP53-knockout created from TK6, and WTK1, a WIL2-derived cell line that spontaneously developed a TP53 mutation. Cells of each cell line were exposed to (137)Cs gamma rays, and then surviving clones were isolated and expanded in culture for approximately 35 generations before the frequency and characteristics of the instability were analyzed. The presence of dicentric chromosomes, formed by end-to-end fusions, served as a marker of chromosomal instability. Unexposed TK6 cells had low levels of chromosomal instability (0.002 +/- 0.001 dicentrics/cell). Exposure of TK6 cells to doses as low as 5 cGy gamma rays increased chromosome instability levels nearly 10-fold to 0.019 +/- 0.008 dicentrics/cell. There was no further increase in instability levels beyond 5 cGy. In contrast to TK6 cells, unexposed cultures of WTK1 and NH32 cells had much higher levels of chromosome instability of 0.034 +/- 0.007 and 0.041 +/- 0.009, respectively, but showed little if any effect of radiation on levels of chromosome instability. The results suggest that radiation exposure alters the normal TP53-dependent cell cycle checkpoint controls that recognize alterations in telomere structure and activate apoptosis.

  17. Empowering gamma delta T cells with antitumor immunity by dendritic cell-based immunotherapy

    PubMed Central

    Van Acker, Heleen H; Anguille, Sébastien; Van Tendeloo, Viggo F; Lion, Eva

    2015-01-01

    Gamma delta (γδ) T cells are the all-rounders of our immune-system with their major histocompatibility complex-unrestricted cytotoxicity, capacity to secrete immunosti-mulatory cytokines and ability to promote the generation of tumor antigen-specific CD8+ and CD4+ T cell responses. Dendritic cell (DC)-based vaccine therapy has the prospective to harness these unique features of the γδ T cells in the fight against cancer. In this review, we will discuss our current knowledge on DC-mediated γδ T cell activation and related opportunities for tumor immunologists. PMID:26405575

  18. Levels of naturally occurring gamma radiation measured in British homes and their prediction in particular residences.

    PubMed

    Kendall, G M; Wakeford, R; Athanson, M; Vincent, T J; Carter, E J; McColl, N P; Little, M P

    2016-03-01

    Gamma radiation from natural sources (including directly ionising cosmic rays) is an important component of background radiation. In the present paper, indoor measurements of naturally occurring gamma rays that were undertaken as part of the UK Childhood Cancer Study are summarised, and it is shown that these are broadly compatible with an earlier UK National Survey. The distribution of indoor gamma-ray dose rates in Great Britain is approximately normal with mean 96 nGy/h and standard deviation 23 nGy/h. Directly ionising cosmic rays contribute about one-third of the total. The expanded dataset allows a more detailed description than previously of indoor gamma-ray exposures and in particular their geographical variation. Various strategies for predicting indoor natural background gamma-ray dose rates were explored. In the first of these, a geostatistical model was fitted, which assumes an underlying geologically determined spatial variation, superimposed on which is a Gaussian stochastic process with Matérn correlation structure that models the observed tendency of dose rates in neighbouring houses to correlate. In the second approach, a number of dose-rate interpolation measures were first derived, based on averages over geologically or administratively defined areas or using distance-weighted averages of measurements at nearest-neighbour points. Linear regression was then used to derive an optimal linear combination of these interpolation measures. The predictive performances of the two models were compared via cross-validation, using a randomly selected 70 % of the data to fit the models and the remaining 30 % to test them. The mean square error (MSE) of the linear-regression model was lower than that of the Gaussian-Matérn model (MSE 378 and 411, respectively). The predictive performance of the two candidate models was also evaluated via simulation; the OLS model performs significantly better than the Gaussian-Matérn model. PMID:26880257

  19. Investigation of the fluorescence emitted from polyallyl diglycol carbonate modified by gamma-ray radiation excited by UV radiation

    NASA Astrophysics Data System (ADS)

    Elmaghraby, Elsayed K.; Salama, Talat A.

    The fluorescence emitted from the gamma-ray-irradiated polyallyl diglycol carbonate upon illumination by the 346 nm UV radiation is studied. The fluorescence spectra show two distinct phenomena, the variation of fluorescence wavelength and intensity with received irradiation dose. These variations are found to be correlated to the change in the dielectric constant and the change in absorption. The dielectric constant is measured at three guiding frequencies, while the absorption is predicted with the reflected first and second diffractions of the excitation monochromator. The results support the donor-bridge-acceptor molecular origin of the fluorescence.

  20. Biological radiation dose from secondary particles in a Milky Way gamma-ray burst

    NASA Astrophysics Data System (ADS)

    Atri, Dimitra; Melott, Adrian L.; Karam, Andrew

    2014-07-01

    Gamma-ray bursts (GRBs) are a class of highly energetic explosions emitting radiation in a very short timescale of a few seconds and with a very narrow opening angle. Although, all GRBs observed so far are extragalactic in origin, there is a high probability of a GRB of galactic origin beaming towards the Earth in the past ~0.5 Gyr. We define the level of catastrophic damage to the biosphere as approximation 100 kJ m-2, based on Thomas et al. (2005a, b). Using results in Melott & Thomas (2011), we estimate the probability of the Earth receiving this fluence from a GRB of any type, as 87% during the last 500 Myr. Such an intense burst of gamma rays would ionize the atmosphere and deplete the ozone (O3) layer. With depleted O3, there will be an increased flux of Solar UVB on the Earth's surface with potentially harmful biological effects. In addition to the atmospheric damage, secondary particles produced by gamma ray-induced showers will reach the surface. Among all secondary particles, muons dominate the ground-level secondary particle flux (99% of the total number of particles) and are potentially of biological significance. Using the Monte Carlo simulation code CORSIKA, we modelled the air showers produced by gamma-ray primaries up to 100 GeV. We found that the number of muons produced by the electromagnetic component of hypothetical galactic GRBs significantly increases the total muon flux. However, since the muon production efficiency is extremely low for photon energies below 100 GeV, and because GRBs radiate strongly for only a very short time, we find that the biological radiation dose from secondary muons is negligible. The main mechanism of biological damage from GRBs is through Solar UVB irradiation from the loss of O3 in the upper atmosphere.

  1. Terrestrial gamma radiation baseline mapping using ultra low density sampling methods.

    PubMed

    Kleinschmidt, R; Watson, D

    2016-01-01

    Baseline terrestrial gamma radiation maps are indispensable for providing basic reference information that may be used in assessing the impact of a radiation related incident, performing epidemiological studies, remediating land contaminated with radioactive materials, assessment of land use applications and resource prospectivity. For a large land mass, such as Queensland, Australia (over 1.7 million km(2)), it is prohibitively expensive and practically difficult to undertake detailed in-situ radiometric surveys of this scale. It is proposed that an existing, ultra-low density sampling program already undertaken for the purpose of a nationwide soil survey project be utilised to develop a baseline terrestrial gamma radiation map. Geoelement data derived from the National Geochemistry Survey of Australia (NGSA) was used to construct a baseline terrestrial gamma air kerma rate map, delineated by major drainage catchments, for Queensland. Three drainage catchments (sampled at the catchment outlet) spanning low, medium and high radioelement concentrations were selected for validation of the methodology using radiometric techniques including in-situ measurements and soil sampling for high resolution gamma spectrometry, and comparative non-radiometric analysis. A Queensland mean terrestrial air kerma rate, as calculated from the NGSA outlet sediment uranium, thorium and potassium concentrations, of 49 ± 69 nGy h(-1) (n = 311, 3σ 99% confidence level) is proposed as being suitable for use as a generic terrestrial air kerma rate background range. Validation results indicate that catchment outlet measurements are representative of the range of results obtained across the catchment and that the NGSA geoelement data is suitable for calculation and mapping of terrestrial air kerma rate. PMID:26063584

  2. Comparative studies on PADC polymeric detector treated by gamma radiation and Ar ion beam

    NASA Astrophysics Data System (ADS)

    El-Saftawy, A. A.; Abdel Reheem, A. M.; Kandil, S. A.; Abd El Aal, S. A.; Salama, S.

    2016-05-01

    In the present study, a comparative analysis and evaluation of the induced defects in polyallyl diglycol carbonate (PADC) polymeric detector exposed to Ar+ and gamma radiation were made. To get insight into the structure defects due to irradiation, X-ray diffraction (XRD) technique was employed. The PADC surface structure changed after irradiation due to the reduction in the surface crystalline structure and the formation of disordered systems. Also, surface morphology changes were traced using scanning electron microscopy (SEM) and showed minor surface irregularities after gamma irradiation and large changes upon Ar+ irradiation. Additionally, micro-hardness and friction coefficient of the irradiated samples were investigated and found to increase after irradiation. UV-vis spectroscopy was used to estimate the optical band gap energy which considered as the basis for calculating the number of conjugated carbon atoms responsible for the blackening effect and color changes took place over the PADC surface. It was found that as the applied dose increased, the band gap decreased and the number of carbon clusters get larger. The refractive index and the dispersion parameters for the studied polymer were calculated and discussed. Also, the induced defects on the polymer surface which serve as a non-radiative centers resulting in reduced photoluminescence (PL) intensity. For nearly all the measured parameters, gamma irradiated samples showed a significant changes compared to that induced by ions. But, low energy Ar+ prove efficiency in controlling surface properties of PADC polymer without affecting its sensitive bulk properties, besides that the obtained results are reasonable and comparable to that induced by gamma radiation.

  3. M-BAND Study of Radiation-Induced Chromosome Aberrations in Human Epithelial Cells: Radiation Quality and Dose Rate Effects

    NASA Technical Reports Server (NTRS)

    Hada, Megumi; Cucinotta, Francis; Wu, Honglu

    2009-01-01

    The advantage of the multicolor banding in situ hybridization (mBAND) technique is its ability to identify both inter- (translocation to unpainted chromosomes) and intra- (inversions and deletions within a single painted chromosome) chromosome aberrations simultaneously. To study the detailed rearrangement of low- and high-LET radiation induced chromosome aberrations in human epithelial cells (CH184B5F5/M10) in vitro, we performed a series of experiments with Cs-137 gamma rays of both low and high dose rates, neutrons of low dose rate and 600 MeV/u Fe ions of high dose rate, with chromosome 3 painted with multi-binding colors. We also compared the chromosome aberrations in both 2- and 3-dimensional cell cultures. Results of these experiments revealed the highest chromosome aberration frequencies after low dose rate neutron exposures. However, detailed analysis of the radiation induced inversions revealed that all three radiation types induced a low incidence of simple inversions. Most of the inversions in gamma-ray irradiated samples were accompanied by other types of intra-chromosomal aberrations but few inversions were accompanied by inter-chromosomal aberrations. In contrast, neutrons and Fe ions induced a significant fraction of inversions that involved complex rearrangements of both inter- and intrachromosomal exchanges. The location of the breaks involved in chromosome exchanges was analyzed along the painted chromosome. The breakpoint distribution was found to be randomly localized on chromosome 3 after neutron or Fe ion exposure, whereas non-random distribution with clustering breakpoints was observed after -ray exposure. Our comparison of chromosome aberration yields between 2- and 3-dimensional cell cultures indicated a significant difference for gamma exposures, but not for Fe ion exposures. These experimental results indicated that the track structure of the radiation and the cellular/chromosome structure can both affect radiation-induced chromosome aberrations.

  4. 1989 neutron and gamma personnel dosimetry intercomparison study using RADCAL (Radiation Calibration Laboratory) sources

    SciTech Connect

    Sims, C.S.; Casson, W.H.; Patterson, G.R. ); Murakami, H. . Dept. of Health Physics); Liu, J.C. )

    1990-10-01

    The fourteenth Personnel Dosimetry Intercomparison Study (i.e., PDIS 14) was conducted during May 1-5, 1989. A total of 48 organizations (33 from the US and 15 from abroad) participated in PDIS 14. Participants submitted by mail a total of 1,302 neutron and gamma dosimeters for this mixed field study. The type of neutron dosimeter and the percentage of participants submitting that type are as follows: TLD-albedo (40%), direct interaction TLD (22%), track (20%), film (7%), combination (7%), and bubble detectors (4%). The type of gamma dosimeter and the percentage of participants submitting that type are as follows: TLD (84%) and film (16%). Radiation sources used in the six PDIS 14 exposures included {sup 252}Cf moderated by 15-cm D{sub 2}O, {sup 252}Cf moderated by 15-cm polyethylene (gamma-enhanced with {sup 137}Cs), and {sup 238}PuBe. Neutron dose equivalents ranged from 0.44--2.63 mSv and gamma doses ranged from 0. 01-1.85 mSv. One {sup 252}Cf(D{sub 2}O) exposure was performed at a 60{degree} angle of incidence (most performance tests are at perpendicular incidence). The average neutron dosimeter response for this exposure was 70% of that at normal incidence. The average gamma dosimeter response was 96% of that at normal incidence. A total of 70% of individual reported neutron dosimeter measurements were within {plus minus}50% of reference values. If the 0.01 mSv data are omitted, approximately 90% of the individual reported gamma measurements were within {plus minus}50% of reference values. 33 refs., 9 figs., 27 tabs.

  5. Induced ICER I{gamma} down-regulates cyclin A expression and cell proliferation in insulin-producing {beta} cells

    SciTech Connect

    Inada, Akari; Weir, Gordon C.; Bonner-Weir, Susan . E-mail: susan.bonner-weir@joslin.harvard.edu

    2005-04-15

    We have previously found that cyclin A expression is markedly reduced in pancreatic {beta}-cells by cell-specific overexpression of repressor inducible cyclic AMP early repressor (ICER I{gamma}) in transgenic mice. Here we further examined regulatory effects of ICER I{gamma} on cyclin A gene expression using Min6 cells, an insulin-producing cell line. The cyclin A promoter luciferase assay showed that ICER I{gamma} directly repressed cyclin A gene transcription. In addition, upon ICER I{gamma} overexpression, cyclin A mRNA levels markedly decreased, thereby confirming an inhibitory effect of ICER I{gamma} on cyclin A expression. Suppression of cyclin A results in inhibition of BrdU incorporation. Under normal culture conditions endogenous cyclin A is abundant in these cells, whereas ICER is hardly detectable. However, serum starvation of Min6 cells induces ICER I{gamma} expression with a concomitant very low expression level of cyclin A. Cyclin A protein is not expressed unless the cells are in active DNA replication. These results indicate a potentially important anti-proliferative effect of ICER I{gamma} in pancreatic {beta} cells. Since ICER I{gamma} is greatly increased in diabetes as well as in FFA- or high glucose-treated islets, this effect may in part exacerbate diabetes by limiting {beta}-cell proliferation.

  6. Cell inactivation, mutation and DNA strand-break induction by gamma-rays at very low temperatures.

    PubMed

    Kozubek, S; Rýznar, L; Vítová, H; Mlejnek, P; Slotová, J

    1994-01-01

    Cell inactivation, mutation and DNA strand-break induction by gamma-radiation have been investigated at very low temperatures (-78 degrees C, -196 degrees C, and -268 degrees C). In Escherichia coli Ymel, lacI+-->lacI- and Salmonella typhimurium TA102, his--->his+ dose-modifying factors determined for low radiation doses are similar for both mutation induction and cell inactivation. The sensitivity of repair-deficient strains E. coli polA- and E. coli recA- was also reduced at low temperature to a comparable extent. This suggests that the lesions which are responsible for cell inactivation and mutagenesis could be strongly mutually related and/or that different types of lesions which are responsible for cell inactivation and mutation induction in bacteria are reduced at low temperature to the same or similar extent. Likewise, a lower yield of DNA strand breaks in plasmids irradiated at low temperature was observed. PMID:7708903

  7. Effect of Gender on the Radiation Sensitivity of Murine Blood Cells.

    PubMed

    Billings, Paul C; Romero-Weaver, Ana L; Kennedy, Ann R

    2014-08-01

    Space travel beyond the Earth's protective magnetosphere risks exposing astronauts to ionizing radiation, such as that generated during a solar particle event (SPE). Ionizing radiation has well documented effects on blood cells and it is generally assumed that these effects contribute to the hematopoietic syndrome (HS), observed in animals and humans, following exposure to total body irradiation (TBI). The purpose of the current study was to assess the role of gender on the effects of gamma radiation on blood cells. C3H/HeN mice were irradiated with a (137)Cs gamma source. Radiation had similar effects on white blood cells (WBCs), lymphocytes, and granulocytes in male and female C3H/HeN mice, while red blood cell (RBC) counts and hematocrit values remained stable following radiation exposure. Non-irradiated male mice had 13% higher platelet counts, compared with their female counterparts, and showed enhanced recovery of platelets on day 16 following radiation exposure. Hence, gender differences influence the response of platelets to TBI exposure. PMID:25221782

  8. Effect of Gender on the Radiation Sensitivity of Murine Blood Cells

    PubMed Central

    Billings, Paul C; Romero-Weaver, Ana L; Kennedy, Ann R

    2014-01-01

    Space travel beyond the Earth’s protective magnetosphere risks exposing astronauts to ionizing radiation, such as that generated during a solar particle event (SPE). Ionizing radiation has well documented effects on blood cells and it is generally assumed that these effects contribute to the hematopoietic syndrome (HS), observed in animals and humans, following exposure to total body irradiation (TBI). The purpose of the current study was to assess the role of gender on the effects of gamma radiation on blood cells. C3H/HeN mice were irradiated with a 137Cs gamma source. Radiation had similar effects on white blood cells (WBCs), lymphocytes, and granulocytes in male and female C3H/HeN mice, while red blood cell (RBC) counts and hematocrit values remained stable following radiation exposure. Non-irradiated male mice had 13% higher platelet counts, compared with their female counterparts, and showed enhanced recovery of platelets on day 16 following radiation exposure. Hence, gender differences influence the response of platelets to TBI exposure. PMID:25221782

  9. Gamma radiation impact on performance of OOK, DPSK and homodyne BPSK based optical inter-satellite communication system

    NASA Astrophysics Data System (ADS)

    Liu, Yun; Zhao, Shanghong; Gong, Zizheng; Hou, Rui; Qiang, Ruoxin

    2015-09-01

    Performance of optical inter-satellite communication system is influenced by the harsh space radiation environment. Gamma radiation effects on main devices of communication system are analyzed and on the basis of existing experimental data, performance degradation of on off keying (OOK), differential phase shift keying (DPSK) and homodyne binary phase shift keying (BPSK) based system under 1 kGy gamma irradiation is simulated. Variation of Q factors and bit error ratio of these systems with different radiation position are achieved and discussed. The result shows that it is more urgent to improve the radiation hardness of transmitter, and the introduction of local laser is a considerable method to reduce gamma radiation impact on system performance.

  10. CCL20, (gamma)(delta) T cells, and IL-22 in corneal epithelial healing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    After corneal epithelial abrasion, leukocytes and platelets rapidly enter the corneal stroma, and CCR6 (+) IL-17(+) gamma delta T cells migrate into the epithelium. Gamma delta T-cell-deficient (TCRd(-/-)) mice have significantly reduced inflammation and epithelial wound healing. Epithelial CCL20 mR...

  11. Inhibition of radiation-enhanced expression of integrin and metastatic potential in B16 melanoma cells by a lipoxygenase inhibitor

    SciTech Connect

    Onoda, J.M.; Honn, K.V. |; Kantak, S.S.; Piechocki, M.P.; Awad, W.; Chea, R.; Liu, B.

    1994-12-01

    Low-dose {gamma} radiation stimulates expression of phenotypic characteristics in B16 melanoma cells which regulate metastatic potential. A transient increase in the expression of an integrin receptor ({alpha}{sub IIb}{beta}{sub 3}) was observed after exposure of B16 melanoma cells to 0.25 to 2.0 Gy of {gamma} radiation. This increased receptor expression resulted in enhanced adhesion of tumor cells to fibronectin in vitro and increased experimentally induced metastasis in vivo. In this report, we determined a role for the 12-lipoxygenase metabolite, 12-HETE, in radiation-enhanced metastasis. A significant increase in biosynthesis of 12-HETE in B16 melanoma cells was detected <5 min after exposure to 0.5 Gy {gamma} radiation. We then determined that radiation-enhanced expression of {alpha}{sub IIb}{beta}{sub 3} integrin and adhesion of B16 melanoma cells to fibronectin in vitro and metastasis in vivo were reduced by treatment of the cells with the lipoxygenase inhibitor NDGA prior to irradiation. These findings suggest that low-dose radiation, at levels comparable to those used in fractionated or hyperfractionated radiotherapy, increases the metastatic potential of surviving tumor cells via a rapid and transient alteration in lipoxygenase metabolism of arachidonic acid and surface expression of an integrin receptor. 30 refs., 5 figs., 1 tab.

  12. Ionizing radiation damage to cells: effects of cell cycle redistribution.

    PubMed

    Chen, P L; Brenner, D J; Sachs, R K

    1995-04-01

    If a population of cycling cells is exposed to a fixed dose of ionizing radiation delivered over time T, it is sometimes observed that increasing T increases the amount of cell killing. This is essentially because at first the radiation preferentially kills cells in a sensitive portion of the cycle and the surviving, more resistant cells then have time to reach more sensitive stages. We refer to this effect as population resensitization, caused by redistribution within the cell cycle. We investigate the effect theoretically by employing the McKendrick-von Foerster equation for age-structured proliferating cell populations, generalized by introducing a radiation damage term. Within our formalism, we show that population resensitization occurs whenever: (a) prior to irradiation the cell population has the stable age-distribution approached asymptotically by an unirradiated population, and (b) T is sufficiently small. Examples and other cases are outlined. The methods of Volterra integral equations, renewal theory, and positive semigroup theory are applied. The effect of varying T is evaluated by considering the ultimate amplitude of the stable age-distribution population at times much greater than both the irradiation duration and the average cell-cycle time. The main biological limitations of the formalism are the following: considering only radiation damage which is not subject to enzymatic repair or quadratic misrepair, using an overly naive method of ensuring loss of cell cycle synchrony, neglecting nonlinear effects such as density inhibition of growth, and neglecting radiatively induced perturbations of the cell cycle. Possible methods for removing these limitations are briefly discussed. PMID:7703592

  13. Decreased production of interferon-gamma by human neonatal cells. Intrinsic and regulatory deficiencies.

    PubMed Central

    Wilson, C B; Westall, J; Johnston, L; Lewis, D B; Dower, S K; Alpert, A R

    1986-01-01

    Human neonatal lymphocytes produced little macrophage activation factor in response to mitogens. This correlated with decreased production of interferon-gamma (IFN gamma): adult lymphokines contained 894.2 +/- 177.1 U/ml, whereas neonatal cord and peripheral lymphokines contained 66.9 +/- 17.0 and 116.7 +/- 29.6 U/ml by bioassay. Results by radioimmunoassay (RIA) for IFN gamma were similar. In contrast, the interleukin 2 content of cord lymphokines was greater (P less than 0.01) and that of neonatal peripheral blood lymphokines similar to that of adults. Interleukin 1 production and interleukin 2 receptor expression and affinity were similar for adult and neonatal cells. Interleukins 1 and 2 in amounts comparable to those in adult lymphokines did not increase production of macrophage activation factor or IFN gamma by neonatal cells. Neonatal cells did not contain intracellular IFN or degrade exogenous IFN. Excess suppressor activity was not found in neonatal cultures. Addition of IFN alpha, 10,000-50,000 U/ml of interleukin 2 or phorbol myristate acetate (PMA) to cord mononuclear cells or of adult monocytes or PMA to cord T cells increased IFN gamma production compared to cells stimulated with concanavalin A (ConA) alone. Nevertheless, under optimal conditions (T cells + PMA + Con A), adult cells produced much more IFN gamma (1,360 +/- 261 U/ml by RIA) than cord cells (122 +/- 37 U/ml). Staphylococcal enterotoxin A (SEA) stimulated cord cell IFN gamma production at low cell densities; nevertheless, adult cells produced more IFN in response to SEA 1,341 +/- 350 U/ml) than cord cells (350 +/- 33 U/ml). Decreased production of IFN gamma by neonatal cells appears to be due both to differences in their intrinsic capacity to produce IFN gamma and to differences in regulatory mechanisms. PMID:3081575

  14. Caffeine sensitization of cultured mammalian cells and human lymphocytes irradiated with gamma rays and fast neutrons: a study of relative biological effectiveness in relation to cellular repair

    SciTech Connect

    Hannan, M.A.; Gibson, D.P.

    1985-10-01

    The sensitizing effects of caffeine were studied in baby hamster kidney (BHK-21) cells and human lymphocytes following irradiation with gamma rays and fast neutrons. Caffeine sensitization occurred only when log-phase BHK cells and mitogen-stimulated lymphocytes were exposed to the two radiations. Noncycling (confluent) cells of BHK resulted in a shouldered survival curve following gamma irradiation while a biphasic curve was obtained with the log-phase cells. Survival in the case of lymphocytes was estimated by measurement of (TH)thymidine uptake. The relative biological effectiveness (RBE) of fast neutrons was found to be greater at survival levels corresponding to the resistant portions of the survival curves (shoulder or resistant tail). In both cell types, no reduction in RBE was observed when caffeine was present, because caffeine affected both gamma and neutron survival by the same proportion.

  15. Radiation-induced degradation of cyclohexanebutyric acid in aqueous solutions by gamma ray irradiation

    NASA Astrophysics Data System (ADS)

    Jia, Wenbao; He, Yanquan; Ling, Yongsheng; Hei, Daqian; Shan, Qing; Zhang, Yan; Li, Jiatong

    2015-04-01

    The radiation-induced degradation of cyclohexanebutyric acid under gamma ray irradiation was investigated. Degradation experiments were performed with 100 mL sealed Pyrex glass vessels loaded with 80 mL of cyclohexanebutyric acid solutions at various initial concentrations of 10, 20, and 40 mg L-1. The absorbed doses were controlled at 0, 0.65, 1.95, 3.25, 6.5, 9.75, and 13 kGy. The results showed that gamma ray irradiation could effectively degrade cyclohexanebutyric acid in aqueous solutions. The removal rate of cyclohexanebutyric acid increased significantly with the increase of absorbed dose and the decrease of its initial concentration. At the same time, the removal of chemical oxygen demand (COD) was as effective as that of cyclohexanebutyric acid. The kinetic studies showed that the degradation of cyclohexanebutyric acid followed pseudo first-order reaction. Above all, the proposed mechanism obtained when NaNO2, NaNO3 and tert-butanol were added showed that the OH radical played a major role in the gamma degradation process of cyclohexanebutyric acid, while H and eaq- played a minor role in the gamma degradation process. The degradation products were identified by Fourier transform infrared spectroscopy (FTIR) and gas chromatography/mass spectrometry (GC/MS) during cyclohexanebutyric acid degradation.

  16. a Study of the Characteristics of High-Energy Gamma Radiation Following the Fusion of CHLORINE-35 + Iron -54.

    NASA Astrophysics Data System (ADS)

    Herman, Michael Gordon

    The characteristics of high energy gamma radiation from the decay of heavy-ion fusion induced compound nucleus formation are investigated. The compound nucleus of ('89)Tc was formed with a ('35)Cl projectile and an ('54)Fe target. Laboratory energies ranged from the Coulomb barrier to the fission limit. The highest energy photons are believed to result from the decay of giant resonances built on lower lying excited nuclear states. The origin of these transitions and their relationship to the structure of the excited nucleus are discussed. Measurements using a 4(pi) NaI sum spectrometer, two small solid-angle NaI gamma detectors and a recoil mass spectrometer yielded gamma strength, average gamma multiplicity, total gamma cascade energy, multiplicity as a function of gamma ray energy, fusion cross sections and the above stated gamma quantities gated by residual mass. Evidence for statistical emission of high energy gamma rays following equilibrated compound nucleus fusion is presented. The dependence of the Giant Dipole resonance characteristics on angular momentum and excitation energy is deduced. Competition between high energy gamma decay and particle evaporation is observed. The statistical model treatment of compound nucleus formation and decay is compared to the data using the computer code CASCADE. Significantly higher than average multiplicities for the highest energy photons can not be reproduced by the statistical model. The possibility of spin dependent radiative capture or GDR coupling to a non-Yrast band is discussed.

  17. Verification by the FISH translocation assay of historic doses to Mayak workers from external gamma radiation.

    PubMed

    Sotnik, Natalia V; Azizova, Tamara V; Darroudi, Firouz; Ainsbury, Elizabeth A; Moquet, Jayne E; Fomina, Janna; Lloyd, David C; Hone, Pat A; Edwards, Alan A

    2015-11-01

    The aim of this study was to apply the fluorescence in situ hybridization (FISH) translocation assay in combination with chromosome painting of peripheral blood lymphocytes for retrospective biological dosimetry of Mayak nuclear power plant workers exposed chronically to external gamma radiation. These data were compared with physical dose estimates based on monitoring with badge dosimeters throughout each person's working life. Chromosome translocation yields for 94 workers of the Mayak production association were measured in three laboratories: Southern Urals Biophysics Institute, Leiden University Medical Center and the former Health Protection Agency of the UK (hereinafter Public Health England). The results of the study demonstrated that the FISH-based translocation assay in workers with prolonged (chronic) occupational gamma-ray exposure was a reliable biological dosimeter even many years after radiation exposure. Cytogenetic estimates of red bone marrow doses from external gamma rays were reasonably consistent with dose measurements based on film badge readings successfully validated in dosimetry system "Doses-2005" by FISH, within the bounds of the associated uncertainties. PMID:26319788

  18. Attenuation of X and Gamma Rays in Personal Radiation Shielding Protective Clothing.

    PubMed

    Kozlovska, Michaela; Cerny, Radek; Otahal, Petr

    2015-11-01

    A collection of personal radiation shielding protective clothing, suitable for use in case of accidents in nuclear facilities or radiological emergency situations involving radioactive agents, was gathered and tested at the Nuclear Protection Department of the National Institute for Nuclear, Chemical and Biological Protection, Czech Republic. Attenuating qualities of shielding layers in individual protective clothing were tested via spectra measurement of x and gamma rays, penetrating them. The rays originated from different radionuclide point sources, the gamma ray energies of which cover a broad energy range. The spectra were measured by handheld spectrometers, both scintillation and High Purity Germanium. Different narrow beam geometries were adjusted using a special testing bench and a set of various collimators. The main experimentally determined quantity for individual samples of personal radiation shielding protective clothing was x and gamma rays attenuation for significant energies of the spectra. The attenuation was assessed comparing net peak areas (after background subtraction) in spectra, where a tested sample was placed between the source and the detector, and corresponding net peak areas in spectra, measured without the sample. Mass attenuation coefficients, which describe attenuating qualities of shielding layers materials in individual samples, together with corresponding lead equivalents, were determined as well. Experimentally assessed mass attenuation coefficients of the samples were compared to the referred ones for individual heavy metals. PMID:26425983

  19. Effect of gamma radiation on growth and survival of common seed-borne fungi in India

    NASA Astrophysics Data System (ADS)

    Maity, J. P.; Chakraborty, A.; Chanda, S.; Santra, S. C.

    2008-07-01

    The present work describes radiation-induced effects of major seeds like Oryza sativa Cv-2233, Oryza sativa Cv-Shankar, Cicer arietinum Cv-local and seed-borne fungi like Alternaria sp., Aspergillus sp., Trichoderma sp. and Curvularia sp. 60Co gamma source at 25 °C emitting gamma ray at 1173 and 1332 keV energy was used for irradiation. Dose of gamma irradiation up to 3 kGy (0.12 kGy/h) was applied for exposing the seed and fungal spores. Significant depletion of the fungal population was noted with irradiation at 1-2 kGy, whereas germinating potential of the treated grain did not alter significantly. However, significant differential radiation response in delayed seed germination, colony formation of the fungal spores and their depletion of growth were noticed in a dose-dependent manner. The depletion of the fungal viability (germination) was noted within the irradiation dose range of 1-2 kGy for Alternaria sp. and Aspergillus sp., while 0.5-1 kGy for Trichoderma sp. and Curvularia sp. However, complete inhibition of all the selected fungi was observed above 2.5 kGy.

  20. Measurements of gamma radiation levels and spectra in the San Francisco Bay Area

    NASA Astrophysics Data System (ADS)

    Lo, B. T.; Brozek, K. P.; Angell, C. T.; Norman, E. B.

    2011-10-01

    Much of the radiation received by an average person is emitted by naturally-occurring radioactive isotopes from the thorium, actinium, and uranium decay series, or potassium. In this study, we have measured gamma radiation levels at various locations in the San Francisco Bay Area and the UC Berkeley campus from spectra taken using an ORTEC NOMAD portable data acquisition system and a large-volume coaxial HPGe detector. We have identified a large number of gamma rays originating from natural sources. The most noticeable isotopes are 214Bi, 40K, and 208Tl. We have observed variations in counting rates by factors of two to five between different locations due to differences in local conditions - such as building, concrete, grass, and soil compositions. In addition, in a number of outdoor locations, we have observed 604-, 662-, and 795-keV gamma rays from 134,137Cs, which we attribute to fallout from the recent Fukushima reactor accident. The implications of these results will be discussed. This work was supported in part by a grant from the U. S. Dept. of Homeland Security.

  1. Kinetics of the radiation-induced radicals in gamma irradiated solid cefazolin sodium

    NASA Astrophysics Data System (ADS)

    Yurus, S.; Korkmaz, M.

    2005-01-01

    Room and high temperature kinetic and spectroscopic features of the radical species produced in gamma irradiated cefazolin sodium (here after CS) were investigated in detail using electron spin resonance (ESR) spectroscopy to determine the feasibility of its sterilization by radiation and to explore the dosimetric properties of this semi-synthetic representative of cephalosporins. Irradiated CS exhibits an unresolved ESR doublet as other cephalosporins reported up to date. Signal intensity data derived from microwave saturation, dose-response, decays at room and at high temperature studies were analysed assuming a model of two radical species giving rise to doublet and singlet ESR signals. Spectroscopic parameters of these species were determined through spectrum simulation calculations. Decay parameters calculated from annealing studies at seven different temperatures were used to calculate the activation energies of the contributing species. Radiosensitivity of CS to gamma rays was found to be relatively low in the dose range of 0-25 kGy. This conclusion was considered as an indication of the feasibility of radiosterilization of CS by gamma radiation. Five different functions were tried to explore dose-response data of CS in the dose range of 0-25 kGy and it was concluded that a function comprising a linear and a quadratic terms of applied dose describes best experimental results.

  2. In situ determination of radon concentration and total gamma radiation in Kastel Gomilica, Croatia

    NASA Astrophysics Data System (ADS)

    Lovrencic, Ivanka; Barisic, Delko; Orescanin, Visnja; Lulic, Stipe

    2007-10-01

    To determine current radiation background of the environment at the "Giricic" location in Kastel Gomilica, Croatia, in situ measurement of radon concentration (222Rn and 220Rn) in an open atmosphere on a ground level and at the height of 1.5 m has been made as well as total gamma radiation at the height of 1 m in an energy range of 15 keV to 2 MeV. The researched location was divided in three specific parts: (i) regulated area with the bottom ash and flying ash in the basis ("old" depot), (ii) unregulated area with waste materials, including bottom ash and flying ash, in the basis ("new" depot), (iii) uncontaminated area with no waste materials deposited on. Average radon concentration on a ground level was 213 Bq/m3 for the "old" depot, 214 Bq/m3 for the "new" depot and 59 Bq/m3 for the uncontaminated area and at the height of 1.5 m 20 Bq/m3 for the "old" depot, 34 Bq/m3 for the "new" depot and 26 Bq/m3 for the uncontaminated area. Average total gamma radiation values in selected energy range were 109.92 cps (counts per second) for the "old" depot, 357.76 cps for the "new" depot and 65.97 cps for the uncontaminated area. For selected radionuclides (214Pb, 137Cs, 228Ac, 234mPa, 40K and 214Bi) average gamma radiation values at characteristic energies have been determined as well.

  3. [gamma]-radiation-induced changes in the chemical and physical structure of poly(ethylene terephthalate)

    SciTech Connect

    Jin, Ho-Seon.

    1992-01-01

    Poly(ethylene terephthalate) (PET) film was irradiated with [gamma]-rays in air at doses from 0 to 620 Mrad, and at the rate of 0l8 to 1.0 Mrad/hr. Radiation-induced physical structure changes were studied by DMA and DSC measurements. Tensile properties were measured to find interrelationships with chemical and physical structure changes. Below 100 Mrad, PET shows little change in NMR and IR spectra. Fluorescence emission spectra, however, show the presence and increase of monohydroxy-substituted phenylene groups. This hydroxylation appears to stabilize the polymer. The phenylene group in PET also contributes to radiation-resistance. The amorphous-crystalline interfaces impede the penetration of oxygen and slow the oxidative chain scission. Between 100 and 215 Mrad, UV studies reveal that the rates of reaction begin to change rapidly. Chain scission appears to take place first in the interspherulitic amorphous regions and then in the intraspherulitic (interlamella) regions. [gamma]-Radiation-induced oxidative degradation shows aspects of both photolysis and of thermooxidative degradation (proton and carbon-13 NMR, and IR studies). It was concluded that the crystalline phase breaks down in to smaller crystallites, and these smaller crystallites grow in size by acting as nucleating sites. Tensile measurements show that throughout the range of irradiation studied the tensile strength at break and the percent elongation decrease. The tensile strength decreases uniformly and the percent elongation exhibits a more rapid decrease above 100 Mrad. The results of this study lead to the conclusion that [gamma]-radiation-induced oxidative degradation of PET involves products that are seen in both photolysis and thermooxidation.

  4. Programmable Zone Dosimeter for Operational Monitoring and Measurement of External Gamma Radiation

    NASA Astrophysics Data System (ADS)

    Toledo, René; Osorio, Juan Fco.; López, Ernesto; Claro, Leodibel Pablo; Galván, José

    2002-08-01

    The ZONE DOSIMETER is a high technology portable device, designed on the base of strict quality requirements. It uses real-time digital techniques in order to enhance the quality of monitoring. The dosimeter measures the dose rate of external γ (gamma) radiation, which allows determining the dose of radiation to which the personal is exposed. In this manner, the accomplishment of the regulations of radiological protection and security in institutions where ionizing radiations are used is assured. The dosimeter is commercialized with a fixed pre-calibration; nevertheless, it is up to the user to obtain all the certifications required by the national legislations for its operation within the system of radiological security. It may also be used in Laboratories of Nuclear Medicine.

  5. Terrestrial gamma radiation dose rate in Ryukyu Islands, subtropical region of Japan.

    PubMed

    Furukawa, M; Kina, S; Shiroma, M; Shiroma, Y; Masuda, N; Motomura, D; Hiraoka, H; Fujioka, S; Kawakami, T; Yasuda, Y; Arakawa, K; Fukahori, K; Jyunicho, M; Ishikawa, S; Ohomoto, T; Shingaki, R; Akata, N; Zhuo, W; Tokonami, S

    2015-11-01

    In order to explain the distribution of natural radiation level in the Asia, in situ measurements of dose rate in air due to terrestrial gamma radiation have been conducted in a total of 21 islands that belong to Ryukyu Islands (Ryukyu Archipelago), subtropical rejoin of southwest Japan. Car-borne surveys have also been carried out in Okinawa-jima, the biggest island of the archipelago. Based on the results for these measurements, arithmetic mean, the maximum and the minimum of the dose rates at 1 m in height from the unpaved soil ground in the archipelago were estimated to be 47, 165 and 8 nGy h(-1), respectively. A comparative study of car-borne data obtained prior to and subsequent to the 2011 Fukushima nuclear accident, as for Okinawa-jima, indicated that the nuclear accident has no impact on the environmental radiation at the present time. PMID:26065703

  6. Effect of dexamethasone on the cytotoxic and enzymatic response of cultured endothelial cells to radiation

    SciTech Connect

    Lam, T.T.; Rubin, D.B.; Drab, E.A.

    1985-08-01

    Experiments were conducted to determine (1) whether glucocorticoids directly protected endothelial cells (EC) from radiation and (2) if angiotensin converting enzyme (ACE) activity, known to be increased by glucocorticoid, played a role in the EC response to radiation. Confluent monolayers of EC cultured from bovine aorta EC were treated with dexamethasone (10/sup -6/ M); after irradiation (5.0 Gy, /sup 60/Co ..gamma..) ACE and lactate dehydrogenase (LDH) activities, DNA and protein contents, and nuclei number were measured. Combined dexamethasone treatment and radiation increased cellular ACE activity at a time when neither agent alone had an effect (24-hr dexamethasone exposure before 5 Gy and assayed 24 hr after 5 Gy). This interaction between radiation and dexamethasone treatment suggests that the glucocorticoid modifies the cell's response to injury. Although this interaction does not ameliorate radiation cytotoxicity, maintenance of ACE levels in injured vessels by hormones may have physiological significance in the hemodynamics of irradiated tissues.

  7. Complete suppression of reverse annealing of neutron radiation damage during active gamma irradiation in MCZ Si detectors

    NASA Astrophysics Data System (ADS)

    Li, Z.; Verbitskaya, E.; Chen, W.; Eremin, V.; Gul, R.; Hrknen, J.; Hoeferkamp, M.; Kierstead, J.; Metcalfe, J.; Seidel, S.

    2013-01-01

    For the development of radiation-hard Si detectors for the SiD BeamCal (Si Detector Beam Calorimeter) program for International Linear Collider (ILC), n-type Magnetic Czochralski Si detectors have been irradiated first by fast neutrons to fluences of 1.51014 and 31014 neq/cm2, and then by gamma up to 500 Mrad. The motivation of this mixed radiation project is to test the radiation hardness of MCZ detectors that may utilize the gamma/electron radiation to compensate the negative effects caused by neutron irradiation, all of which exists in the ILC radiation environment. By using the positive space charge created by gamma radiation in MCZ Si detectors, one can cancel the negative space charge created by neutrons, thus reducing the overall net space charge density and therefore the full depletion voltage of the detector. It has been found that gamma radiation has suppressed the room temperature reverse annealing in neutron-irradiated detectors during the 5.5 month of time needed to reach a radiation dose of 500 Mrad. The room temperature annealing (RTA) was verified in control samples (irradiated to the same neutron fluences, but going through this 5.5 month RTA without gamma radiation). This suppression is in agreement with our previous predictions, since negative space charge generated during the reverse annealing was suppressed by positive space charge induced by gamma radiation. The effect is that regardless of the received neutron fluence the reverse annealing is totally suppressed by the same dose of gamma rays (500 Mrad). It has been found that the full depletion voltage for the two detectors irradiated to two different neutron fluences stays the same before and after gamma radiation. Meanwhile, for the control samples also irradiated to two different neutron fluences, full depletion voltages have gone up during this period. The increase in full depletion voltage in the control samples corresponds to the generation of negative space charge, and this increase in concentration of negative space charge goes up with the neutron fluence. If we assume the reverse annealing is also taking place for the two gamma-irradiated samples with similarly different concentrations of negative space charge generated, the observed effect of no changes in space charge (no changes in Vfd) in these two gamma-irradiated samples would imply that concentrations of positive space charge created in these two control samples are different at the same gamma dose, and gamma irradiation effectively "switched off", the RT (room temperature) reverse annealing of neutron irradiation. It has also been found that as soon as the gamma irradiation stops, the RT reverse annealing of neutron irradiation-induced defects resumes with same rate as that of the control detectors. This behavior in mixed radiation samples (neutron plus gamma) would suggest some nonlinear effect (defects induced by mixed-radiations are not additive of those by individual radiation alone), or interaction of radiation induced acceptor-type and donor-type defects.

  8. Detection of DNA Damage by Space Radiation in Human Fibroblast Cells Flown on the International Space Station

    NASA Technical Reports Server (NTRS)

    Wu, Honglu; Lu, Tao; Wong, Michael; Beno, Jonathan; Countryman, Stefanie; Stodieck, Louis; Karouia, Fathi; Zhang, Ye

    2015-01-01

    Although charged particles in space have been detected with radiation detectors on board spacecraft since the early discovery of the Van Allen Belt, reports on effects of direct exposure to space radiation in biological systems have been limited. Measurement of biological effects of space radiation has been difficult due to the low dose and low dose rate nature of the radiation environment, and the difficulty in separating the radiation effects from microgravity and other space environmental factors. In astronauts, only a small number of changes, such as increased chromosome aberrations in lymphocytes and early onset of cataracts, attributed primarily to the exposure to space radiation. In a recent experiment, human fibroblast cells were flown on the International Space Station (ISS). Cells fixed on Days 3 and 14 after reaching orbit were analyzed for phosphorylation of a histone protein H2AX by immunofluorescent staining of cells, which is a widely used marker for DNA double strand breaks. The 3-dimensional gamma-H2AX foci were captured with a laser confocal microscope. Quantitative analysis revealed a small fraction of foci that were larger and displayed a track pattern in the flight samples in comparison to the ground control. Human fibroblast cells were also exposed to low dose rate gamma rays, as well as to protons and Fe ions. Comparison of the pattern and distribution of the foci after gamma ray and charged particle exposure to our flight results confirmed that the foci found in the flown cells were indeed induced by space radiation.

  9. Gallium Arsenide solar cell radiation damage experiment

    NASA Technical Reports Server (NTRS)

    Maurer, R. H.; Kinnison, J. D.; Herbert, G. A.; Meulenberg, A.

    1991-01-01

    Gallium arsenide (GaAs) solar cells for space applications from three different manufactures were irradiated with 10 MeV protons or 1 MeV electrons. The electrical performance of the cells was measured at several fluence levels and compared. Silicon cells were included for reference and comparison. All the GaAs cell types performed similarly throughout the testing and showed a 36 to 56 percent power areal density advantage over the silicon cells. Thinner (8-mil versus 12-mil) GaAs cells provide a significant weight reduction. The use of germanium (Ge) substrates to improve mechanical integrity can be implemented with little impact on end of life performance in a radiation environment.

  10. Comparison of radiation sensitivity for three cell lines as measured by the cloning assay and the micro-nucleus test.

    PubMed

    Stap, J; Aten, J A

    1990-11-01

    The correlation between cell killing and the induction of micro-nuclei was studied for three cell lines after treatment with gamma radiation to investigate whether the frequency of micro-nucleated cells can be used to determine the radiation sensitivity of a cell type. R1 rat rhabdomyosarcoma cells showed a higher sensitivity for the induction of proliferative death than RUC rat ureter carcinoma cells and V79 Chinese hamster cells which had a similar radiation sensitivity. The frequencies of micro-nucleated cells were measured at 48 hours after the treatment. It was determined by time-lapse cinematography that almost all the cells in the treated cultures had divided at that time. Our results indicate that for these cell lines the correlation between the effectiveness for cell killing and the induction of micro-nuclei was the same, within the experimental errors. PMID:2260014

  11. Antizyme suppression leads to an increment of the cellular redox potential and an induction of HIF-1alpha: its involvement in resistance to gamma-radiation.

    PubMed

    Kim, Jin Sik; Kim, Tae Lim; Cho, Eun Wie; Paik, Sang Gi; Chung, Hai Won; Kim, In Gyu

    2008-06-01

    The mammalian antizyme (AZ) promotes ubiqutin-independent degradation of ornithine decarboxylase, a key enzyme in polyamine biosynthesis. This study shows that AZ suppression in human lung carcinoma A549 cells caused growth defects and death, but made the cells resistant to DNA damaging agents such as gamma-radiation and cisplatin. In these cells, the cellular redox potential (glutathione/glutathione disulfide [GSH/GSSG] ratio) was increased and thus intracellular reactive oxygen species were severely diminished, which might cause growth defects and cell death. The increase of cellular redox potential was mainly caused by dramatic increase of the cytoplasmic nicotinamide adenine dinucleotide phosphate (NADP)(+)-dependent isocitrate dehydrogenase, which generates the reducing equivalents NADPH. In the AZ-suppressed cells, the hypoxia inducible factor 1alpha (HIF-1alpha) was also increased. As in other cases which showed an increment of HIF-1alpha and the cellular redox potential, the AZ-suppressed cells showed resistance to gamma-radiation and anticancer drugs. Therefore, these facts might be considered as important for the use of radio- and chemotherapy on tumor cells which show an unbalance in their polyamine levels. PMID:18484090

  12. Radiative-neutron-capture gamma-ray analysis by a linear combination technique

    USGS Publications Warehouse

    Tanner, A.B.; Bhargava, R.C.; Senftle, F.E.; Brinkerhoff, J.M.

    1972-01-01

    The linear combination technique, when applied to a gamma-ray spectrum, gives a single number indicative of the extent to which the spectral lines of a sought element are present in a complex spectrum. Spectra are taken of the sought element and of various other substances whose spectra interfere with that of the sought element. A weighting function is then computed for application to spectra of unknown materials. The technique was used to determine calcium by radiative-neutron-capture gamma-ray analysis in the presence of interfering elements, notably titanium, and the results were compared with those for two popular methods of peak area integration. Although linearity of response was similar for the methods, the linear combination technique was much better at rejecting interferences. For analyses involving mixtures of unknown composition the technique consequently offers improved sensitivity. ?? 1972.

  13. Thermoluminescence behavior of KClXBr1-X: In mixed crystals exposed to gamma radiation

    NASA Astrophysics Data System (ADS)

    Rezaee Ebrahim Saraee, Kh.; Hosseini, S. A.; Faripour, H.; Faiez, M. R.; Abdi, M. R.; Soltani, N.; Aghay Khareiky, A.

    2014-09-01

    In-doped KClXBr1-X (X=1, 0.75, 0.5, 0.25 and 0) mixed crystal has been grown by the Czochralski method. The segregation coefficient of In was studied by the inductively coupled plasma atomic emission spectrometry (ICP-OES). The crystal structure has been determined using X-ray diffraction (XRD) analysis. The thermoluminescence (TL) characterization of KClXBr1-X mixed crystals, exposed to gamma radiation has been performed. The results show the introduction of the dopants ions induced changes in the TL glow curve structure. The TL results suggest that doped KClXBr1-X mixed crystal has good potential active dosimeter applications for gamma ray irradiation.

  14. Gamma-ray escape peak characteristics of radiation-damaged reverse-electrode germanium coaxial detectors

    NASA Astrophysics Data System (ADS)

    Pehl, Richard H.; Hull, Ethan L.; Madden, Norman W.; Xing, Jingshu; Friesel, Dennis L.

    1996-02-01

    A comparison of the characteristics of full-energy gamma-ray peaks and their corresponding escape peaks when high energy photons interact in radiation damaged reverse-electrode (n-type) germanium coaxial detectors is presented. Coaxial detector geometry is the dominant factor, causing charge collection to be dramatically better for interactions occurring near the outer periphery of the detector as well as increasing of the probability of escape events occurring in this region. It follows that the resolution of escape peaks is better than that of ordinary gamma-ray peaks. This is experimentally verified. A nearly identical but undamaged detector exhibited significant Doppler broadening of single escape peaks. Because double escape events preferentially occur at outer radii, energy shifts of double escape reflect extremely small amounts of charge trapping in undamaged detectors.

  15. Gamma-Ray Escape Peak Characteristics of Radiation Damaged Reverse-Electrode Germanium Detectors

    NASA Astrophysics Data System (ADS)

    Hull, E. L.; Xing, J. S.; Friesel, D. L.; Pehl, R. H.; Madden, N. M.

    1996-05-01

    A comparison between the characteristics of escape peaks and ordinary, multiple Compton and photoelectrically interacting, full-energy gamma-ray peaks from radiation damaged reverse-electrode (n-type) germanium coaxial detectors is presented. Coaxial detector geometry is the dominant factor, causing charge collection to be dramatically better near the outer periphery of the detector as well as increasing the probability of escape events occurring in this region. It follows that the resolution of escape peaks is better than that of ordinary gamma-ray peaks. This is experimentally verified. However, a nearly identical but undamaged detector exhibited significant Doppler broadening of single escape peaks. Because double escape events preferentially occur at outer radii, energy shifts in double escape peaks reflect extremely small amounts of charge trapping.

  16. The Effects of Ionizing Radiation on Mammalian Cells.

    ERIC Educational Resources Information Center

    Biaglow, John E.

    1981-01-01

    Discusses the effects of radiation on dividing cells and factors influencing these effects; also briefly reviews the radical mechanism for radiation damage. Emphasizes the importance of oxygen in radiation effects. (CS)

  17. Gamma radiation and magnetic field mediated delay in effect of accelerated ageing of soybean.

    PubMed

    Kumar, Mahesh; Singh, Bhupinder; Ahuja, Sumedha; Dahuja, Anil; Anand, Anjali

    2015-08-01

    Soybean seeds were exposed to gamma radiation (0.5, 1, 3 and 5 kGy), static magnetic field (50, 100 and 200 mT) and a combination of gamma radiation and magnetic energy (0.5 kGy + 200 mT and 5 kGy + 50 mT) and stored at room temperature for six months. These seeds were later subjected to accelerated ageing treatment at 42 °C temperature and 95-100 % relative humidity and were compared for various physical and biochemical characteristics between the untreated and the energized treatments. Energy treatment protected the quality of stored seeds in terms of its protein and oil content . Accelerated aging conditions, however, affected the oil and protein quantity and quality of seed negatively. Antioxidant enzymes exhibited a decline in their activity during aging while the LOX activity, which reflects the rate of lipid peroxidation, in general, increased during the aging. Gamma irradiated (3 and 5 kGy) and magnetic field treated seeds (100 and 200 mT) maintained a higher catalase and ascorbate peroxidase activity which may help in efficient scavenging of deleterious free radical produced during the aging. Aging caused peroxidative changes to lipids, which could be contributed to the loss of oil quality. Among the electromagnetic energy treatments, a dose of 1-5 kGy of gamma and 100 mT, 200 mT magnetic field effectively slowed the rate of biochemical degradation and loss of cellular integrity in seeds stored under conditions of accelerated aging and thus, protected the deterioration of seed quality. Energy combination treatments did not yield any additional protection advantage. PMID:26243899

  18. Interaction of ultraviolet and X-ray radiation with gamma rays produced by a jet in active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Zbyszewska, Magda

    1994-01-01

    Recent observations by the Compton Gamma-Ray Observatory give evidence for the existence of a type of blazar with strong gamma-ray emission. Data obtained by EGRET for the quasar 3C 279 show a spectrum between 100 MeV and 10 GeV. Photons of such energies should interact with the X-rays and produce positron/electron pairs. If the optical depth against pair production for the gamma rays is large (tau(gamma gamma) greater than 1), the gamma-ray spectrum should be affected. The importance of this process has been pointed out by, e.g., Maraschi, Ghisellini, & Celotti (1992). Several works (e.g., Dermer 1993; Zbyszewska 1993; Sikora, Begelman, & Rees 1993) concerning gamma-ray radiation from quasar 3C 279 have proposed a model in which the gamma rays are produced via interaction between a moving cloud of relativistic electrons and external soft photons. The presence of gamma rays in active galactic nuclei spectra gives constraints on the localization and the luminosity of the medium which produces ultraviolet/X-ray photons. We investigate what conditions should be fulfilled in the above model to avoid the absorption of the gamma rays due to pair production.

  19. Induction of transpositions of MGE Dm412 by {gamma}-radiation in an isogenic line of Drosophila melanogaster

    SciTech Connect

    Zabanov, S.A.; Vasil`eva, L.A.; Ratner, V.A. |

    1995-06-01

    In an isogenic line of Drosophila, transpositions of mobile genetic elements (MGE) Dm412 were induced by {gamma}-radiation at doses of 300, 800, and 1300 R. The rates of induced transpositions were (for each dose, respectively) 3.9 x 10{sup {minus}3}, 1.0 x 10{sup {minus}2}, and 1.87 x 10{sup {minus}2} events per occupied site per haploid genome of the isogenic line per generation. Thus, the transposition rate increased linearly with the radiation dose. The specific rate of {gamma}-radiation-induced transpositions was (1.3 {+-} 0.6) x 10{sup {minus}5} per occupied site per haploid genome of the isogenic line per Roentgen per generation. {gamma}-Radiation-induced hot transposition sites and haplotypes, very similar to those induced by heat shock, were found. It was suggested that the mechanism of induction by {gamma}-radiation involves the heat shock system. Thus, it is more similar to the mechanism of temperature induction than to the direct mutational effect of {gamma}-radiation. Estimates of induced transposition rates per genome for each dose were calculated as 1.1, 3.0, and 5.6 events, respectively, per genome per generation. This level probably corresponds to the subthreshold level of genomes near the {open_quotes}catastrophic border of transpositional losses.{close_quotes} 21 refs., 1 fig., 4 tabs.

  20. gamma-Glutamyl transpeptidase expression in Ewing's sarcoma cells: up-regulation by interferons.

    PubMed Central

    Bouman, Lena; Sancau, Josiane; Rouillard, Dany; Bauvois, Brigitte

    2002-01-01

    The genetic hallmark of Ewing's sarcoma family of tumours (ET) is the presence of the translocation t(11;22)(q24;q12), which creates the ET fusion gene, leading to cellular transformation. Five human gamma-glutamyl transpeptidase (gamma-GT) genes are located near the chromosomal translocation in ET. gamma-GT is a major enzyme involved in glutathione homoeostasis. Five human cell lines representative of primary or metastatic tumours were investigated to study whether gamma-GT alterations could occur at the chromosomal breaks and rearrangements in ET. As shown by enzymic assays and FACS analyses, all ET cell lines consistently expressed a functional gamma-GT which however did not discriminate steps of ET progression. As shown previously [Sancau, Hiscott, Delattre and Wietzerbin (2000) Oncogene 19, 3372-3383], ET cells respond to the antiproliferative effects of interferons (IFNs) type I (alpha and beta) and to a much less degree to IFN type II (gamma). IFN-alpha and -beta arrested cells in the S-phase of the cell cycle. We found an enhancement of gamma-GT mRNA species with IFN-alpha and -beta by reverse transcriptase-PCR analyses. This is reflected by up-regulation of gamma-GT protein, which coincides with the increase in gamma-GT-specific enzymic activity. Similarly, IFNs up-regulate the levels of gamma-GT in another IFN-responsive B cell line. Whether this up-regulation of gamma-GT by IFNs is of physiological relevance to cell behaviour remains to be studied. PMID:12049636

  1. Amorphous and crystalline optical materials used as instruments for high gamma radiation doses estimations

    NASA Astrophysics Data System (ADS)

    Ioan, M.-R.

    2016-06-01

    Nuclear radiation induce some changes to the structure of exposed materials. The main effect of ionizing radiation when interacting with optical materials is the occurrence of color centers, which are quantitatively proportional to the up-taken doses. In this paper, a relation between browning effect magnitude and dose values was found. Using this relation, the estimation of a gamma radiation dose can be done. By using two types of laser wavelengths (532 nm and 633 nm), the optical powers transmitted thru glass samples irradiated to different doses between 0 and 59.1 kGy, were measured and the associated optical browning densities were determined. The use of laser light gives the opportunity of using its particularities: monochromaticity, directionality and coherence. Polarized light was also used for enhancing measurements quality. These preliminary results bring the opportunity of using glasses as detectors for the estimation of the dose in a certain point in space and for certain energy, especially in particles accelerators experiments, where the occurred nuclear reactions are involving the presence of high gamma rays fields.

  2. Airborne gamma radiation measurements of soil moisture during FIFE: Activities and results

    NASA Technical Reports Server (NTRS)

    Peck, Eugene L.

    1992-01-01

    Soil moisture measurements were obtained during the summer of 1987 and 1989 near Manhattan, Kansas, using the National Weather Service (NWS) airborne gamma radiation system. A network of 24 flight lines were established over the research area. Airborne surveys were flown daily during two intensive field campaigns. The data collected was sufficient to modify the NWS standard operational method for estimating soil moisture for the Field Experiment (FIFE) flight lines. The average root mean square error of the soil moisture estimates for shorter FIFE flight lines was found to be 2.5 percent, compared with a reported value of 3.9 percent for NWS flight lines. Techniques were developed to compute soil moisture estimates for portions of the flight lines. Results of comparisons of the airborne gamma radiation soil moisture estimates with those obtained using the NASA Pushbroom Microwave Radiation (PBMR) system and hydrological model are presented. The airborne soil moisture measurements, and real averages computed using all remotely sensed and ground data, have been in support of the research of the many FIFE investigators whose overall goal was the upscale integration of models and the application of satellite remote sensing.

  3. Evaluation of phenolic compounds in maté ( Ilex paraguariensis) processed by gamma radiation

    NASA Astrophysics Data System (ADS)

    Furgeri, C.; Nunes, T. C. F.; Fanaro, G. B.; Souza, M. F. F.; Bastos, D. H. M.; Villavicencio, A. L. C. H.

    2009-07-01

    The radiation food processing has been demonstrating great effectiveness in the attack of pathogenic agents, while little compromising nutritional value and sensorial properties of foods. The maté ( Ilex paraguariensis), widely consumed product in South America, generally in the form of infusions with hot or cold water, calls of chimarrão or tererê, it is cited in literature as one of the best sources phenolic compounds. The antioxidants action of these constituent has been related to the protection of the organism against the free radicals, generated in alive, currently responsible for the sprouting of some degenerative illness as cancer, arteriosclerosis, rheumatic arthritis and cardiovascular clutters among others. The objective of that work was to evaluate the action of the processing for gamma radiation in phenolic compounds of tererê beverage in the doses of 0, 3, 5, 7 and 10 kGy. The observed results do not demonstrate significant alterations in phenolic compounds of tererê beverage processed by gamma radiation.

  4. Host defenses in experimental scrub typhus: effect of sublethal gamma radiation

    SciTech Connect

    Kelly, D.J.

    1983-01-01

    The effect of sublethal gamma radiation on inbred mice chronically infected with scrub typhus rickettsiae was examined. Inbred mice which have been inoculated with Gilliam or Karp strain of Rickettsia tsutsugamushi by the subcutaneous route harbored the infection for at least one year. Irradiation of these animals at 12 or 52 weeks post inoculation at normally sublethal levels induced a significantly higher percentage of rickettsemic mice (recrudescence) than in the unirradiated similarly infected control animals. In addition, sublethal irradiation at 12 weeks also induced a quantitative increase in total rickettsiae. Homologous antibody titers to the rickettsiae were examined for five weeks following irradiation to determine the role of the humoral response in radiation induced recrudescence. Modification of recrudescence was investigated using radioprotective drugs. The expected results of this investigation supported the conclusion that the recrudescence of a chronic rickettsial infection in the appropriate host following immunological impairment due to battlefield or clinical exposure to gamma radiation can result in an acute, possibly lethal rickettsemia.

  5. Size Effects on Gamma Radiation Response of Magnetic Properties of Barium Hexaferrite Powders

    SciTech Connect

    McCloy, John S.; Kukkadapu, Ravi K.; Crum, Jarrod V.; Johnson, Bradley R.; Droubay, Timothy C.

    2011-12-08

    Little is currently known about the effects of gamma-ray irradiation on oxide magnet materials. In particular, the effect of particle size on radiation susceptibility was investigated. Two commercial powders of BaFe12O19 were thoroughly characterized, then exposed to 1 MGy of gamma radiation from a 60Co source. AC susceptibility and DC magnetometry and Mössbauer spectroscopy were performed after irradiation and compared to pre-irradiated measurements. DC magnetization and AC susceptibility decreased for both samples with the relative change of DC magnetization being larger for the micrometer-sized particles and the relative change of the AC susceptibility being larger for the nanometer-sized particles. Mössbauer spectroscopy indicated a decrease in both the hyperfine fieldsand in the distribution of hyperfine fields for each Fe site, particularly in the larger particle sample. Decreases in susceptibility are believed to be due to recrystallization of the particles and redistribution of an amorphous component, in the bulk or on the surface, and consequent reduction in the particle magnetic moment. This radiation damage mechanism is different than that seen in previous studies of neutron and heavy ion irradiation of BaFe12O19.

  6. Effect of gamma radiation on chlorobutyl rubber vulcanized by three different crosslinking systems

    NASA Astrophysics Data System (ADS)

    Scagliusi, Sandra R.; Cardoso, Elisabeth L. C.; Lugao, Ademar B.

    2012-09-01

    The development of halogenated butyl rubber (chlorobutyl) in the 1950s and 1960s greatly extended the usefulness of butyl. Their properties allowed the development of more durable tubeless tires with the air retaining innerliner, chemically bonded to the body of the tire. Tire innerliners are by far the largest application for halobutyl. When polymers are subjected to high energy radiation, a number of chemical reactions may occur following the initial ionization and excitation events. These reactions lead to changes in the molecular weight of the polymer through scission (S) and crosslinking (X) of the molecules and affect the physical and mechanical properties. In the halobutyl rubbers the chain scission may predominate. This work aims to show effects of gamma radiation in properties of chlorobutyl rubbers vulcanized with sulfur, sulfur donor and phenolic resin. The butyl rubber has been already studied by us previously. The samples were characterized before and after irradiation. Gamma radiation doses used were: 25 kGy, 50 kGy, 100 kGy, 150 kGy and 200 kGy, in order to identify which cure system is the most stable under irradiation. In this study we observed that the properties of all samples were affected irrespective of the vulcanization system.

  7. Dysregulation of IRP1-Mediated Iron Metabolism Causes Gamma Ray-specific Radioresistance in Leukemia Cells

    PubMed Central

    Haro, Kurtis J.; Sheth, Aneesh; Scheinberg, David A.

    2012-01-01

    Iron is required for nearly all organisms, playing important roles in oxygen transport and many enzymatic reactions. Excess iron, however, can be cytotoxic. Emerging evidence suggests that radioresistance can be achieved in lower organisms by the protection of proteins, but not DNA, immediately following ionizing radiation (IR) exposure, allowing for improved DNA repair. One potential mechanism for protein protection is controlling and limiting the amount of free iron in cells, as has been demonstrated in the extremophile Deinococcus Radiodurans, reducing the potential for oxidative damage to proteins during exposure to IR. We found that iron regulatory protein 1 (IRP1) expression was markedly reduced in human myeloid leukemia HL60 cells resistant to low linear energy transfer (LET) gamma rays, but not to high LET alpha particles. Stable knockdown of IRP1 by short-hairpin RNA (shRNA) interference in radiosensitive parental cells led to radioresistance to low LET IR, reduced intracellular Fenton chemistry, reduced protein oxidation, and more rapid DNA double-strand break (DSB) repair. The mechanism of radioresistance appeared to be related to attenuated free radical-mediated cell death. Control of intracellular iron by IRPs may be a novel radioresistance mechanism in mammalian cells. PMID:23155415

  8. Gamma-H2AX as a biomarker of DNA damage induced by ionizing radiation in targeted and bystander human artificial skin models and peripheral blood lymphocytes

    NASA Astrophysics Data System (ADS)

    Redon, Christophe; Dickey, Jennifer; Bonner, William; Sedelnikova, Olga

    Ionizing radiation (IR) exposure is inevitable. In addition to exposure from cosmic rays, the sun and radioactive substances, modern society has created new sources of radiation exposure such as space and high altitude journeys, X-ray diagnostics, radiological treatments and the increasing threat of radiobiological terrorism. For these reasons, a reliable, reproducible and sensitive assessment of dose and time exposure to IR is essential. We developed a minimally invasive diagnostic test for IR exposure based on detection of a phosphorylated variant of histone H2AX (gamma-H2AX), which occurs specifically at sites of DNA double-strand breaks (DSBs). The phosphorylation of thousands of H2AX molecules forms a gamma-H2AX focus in the chromatin flanking the DSB site that can be detected in situ. We analyzed gamma- H2AX focus formation in both directly irradiated cells as well as in un-irradiated "bystanders" in close contact with irradiated cells. In order to insure minimal invasiveness, we examined commercially available artificial skin models as a surrogate for human skin biopsies as well as peripheral blood lymphocytes. In human skin models, cells in a thin plane were microbeamirradiated and gamma-H2AX formation was measured both in irradiated and in distal bystander cells over time. In irradiated cells DSB formation reached a maximum at 15-30 minutes post- IR and then declined within several hours; all cells were affected. In marked contrast, the incidence of DSBs in bystander cells reached a maximum by 12-48 hours post-irradiation, gradually decreasing over the 7 day time course. At the maxima, 40-60% of bystander cells were affected. Similarly, we analyzed blood samples exposed to IR ex vivo at doses ranging from 0.02 to 3 Gy. The amount of DNA damage was linear in respect to radiation dose and independent of the age or sex of the blood donor. The method is highly reproducible and highly sensitive. In directly irradiated cells, the number of gamma-H2AX foci peaked 30 min after irradiation and then declined at a relatively steady pace as the cell repaired the DNA damage. Radiation effects were still detectable after 48 hrs for doses greater than 1 Gy and remained linear to initial dose. Activated bystander lymphocytes cultured with media from irradiated lymphocytes exhibited a two-fold increased damage response as seen by gamma- H2AX formation. The effect reached a maximum 3 hrs post-exposure and was retained for over 24 hrs. Thus, detection of gamma-H2AX formation to determine DNA damage in a minimally invasive skin test and a non-invasive blood test could be useful and promising tools to analyze direct and indirect effects of radiation exposure.

  9. Study of radiation dose induced by cosmic-ray origin low-energy gamma rays and electrons near sea level

    NASA Astrophysics Data System (ADS)

    Mrdja, D.; Bikit, I.; Bikit, K.; Slivka, J.; Anicin, I.

    2015-02-01

    For a long time, it has been known that low-energy continuous gamma radiation is present in open air at the Earth's surface. In previous investigations it was assumed that this radiation is produced almost exclusively by gamma photons emitted due to the natural radioactivity, which are backscattered by air above ground. We show that significant amount of this radiation (related to energy region 30-300 keV) that peaks at about 90 keV, is produced by cosmic-rays, with the photon flux of about 3000 m-2 s-1. We find that the contribution of this omnipresent low-energy gamma radiation of cosmic-ray origin, including the corresponding low-energy electron flux, to the doses of general population are non-negligible components of overall doses induced by cosmic rays near sea level.

  10. Gallium arsenide solar cell radiation damage study

    NASA Technical Reports Server (NTRS)

    Maurer, R. H.; Herbert, G. A.; Kinnison, J. D.; Meulenberg, A.

    1989-01-01

    A thorough analysis has been made of electron- and proton- damaged GaAs solar cells suitable for use in space. It is found that, although some electrical parametric data and spectral response data are quite similar, the type of damage due to the two types of radiation is different. An I-V analysis model shows that electrons damage the bulk of the cell and its currents relatively more, while protons damage the junction of the cell and its voltages more. It is suggested that multiple defects due to protons in a strong field region such as a p/n junction cause the greater degradation in cell voltage, whereas the individual point defects in the quasi-neutral minority-carrier-diffusion regions due to electrons cause the greater degradation in cell current and spectral response.

  11. A broadband gamma-ray spectrometry using novel unfolding algorithms for characterization of laser wakefield-generated betatron radiation.

    PubMed

    Jeon, Jong Ho; Nakajima, Kazuhisa; Kim, Hyung Taek; Rhee, Yong Joo; Pathak, Vishwa Bandhu; Cho, Myung Hoon; Shin, Jung Hun; Yoo, Byung Ju; Hojbota, Calin; Jo, Sung Ha; Shin, Kang Woo; Sung, Jae Hee; Lee, Seung Ku; Cho, Byeoung Ick; Choi, Il Woo; Nam, Chang Hee

    2015-12-01

    We present a high-flux, broadband gamma-ray spectrometry capable of characterizing the betatron radiation spectrum over the photon energy range from 10 keV to 20 MeV with respect to the peak photon energy, spectral bandwidth, and unique discrimination from background radiations, using a differential filtering spectrometer and the unfolding procedure based on the Monte Carlo code GEANT4. These properties are experimentally verified by measuring betatron radiation from a cm-scale laser wakefield accelerator (LWFA) driven by a 1-PW laser, using a differential filtering spectrometer consisting of a 15-filter and image plate stack. The gamma-ray spectra were derived by unfolding the photostimulated luminescence (PSL) values recorded on the image plates, using the spectrometer response matrix modeled with the Monte Carlo code GEANT4. The accuracy of unfolded betatron radiation spectra was assessed by unfolding the test PSL data simulated with GEANT4, showing an ambiguity of less than 20% and clear discrimination from the background radiation with less than 10%. The spectral analysis of betatron radiation from laser wakefield-accelerated electron beams with energies up to 3 GeV revealed radiation spectra characterized by synchrotron radiation with the critical photon energy up to 7 MeV. The gamma-ray spectrometer and unfolding method presented here facilitate an in-depth understanding of betatron radiation from LWFA process and a novel radiation source of high-quality photon beams in the MeV regime. PMID:26724015

  12. A broadband gamma-ray spectrometry using novel unfolding algorithms for characterization of laser wakefield-generated betatron radiation

    NASA Astrophysics Data System (ADS)

    Jeon, Jong Ho; Nakajima, Kazuhisa; Kim, Hyung Taek; Rhee, Yong Joo; Pathak, Vishwa Bandhu; Cho, Myung Hoon; Shin, Jung Hun; Yoo, Byung Ju; Hojbota, Calin; Jo, Sung Ha; Shin, Kang Woo; Sung, Jae Hee; Lee, Seung Ku; Cho, Byeoung Ick; Choi, Il Woo; Nam, Chang Hee

    2015-12-01

    We present a high-flux, broadband gamma-ray spectrometry capable of characterizing the betatron radiation spectrum over the photon energy range from 10 keV to 20 MeV with respect to the peak photon energy, spectral bandwidth, and unique discrimination from background radiations, using a differential filtering spectrometer and the unfolding procedure based on the Monte Carlo code GEANT4. These properties are experimentally verified by measuring betatron radiation from a cm-scale laser wakefield accelerator (LWFA) driven by a 1-PW laser, using a differential filtering spectrometer consisting of a 15-filter and image plate stack. The gamma-ray spectra were derived by unfolding the photostimulated luminescence (PSL) values recorded on the image plates, using the spectrometer response matrix modeled with the Monte Carlo code GEANT4. The accuracy of unfolded betatron radiation spectra was assessed by unfolding the test PSL data simulated with GEANT4, showing an ambiguity of less than 20% and clear discrimination from the background radiation with less than 10%. The spectral analysis of betatron radiation from laser wakefield-accelerated electron beams with energies up to 3 GeV revealed radiation spectra characterized by synchrotron radiation with the critical photon energy up to 7 MeV. The gamma-ray spectrometer and unfolding method presented here facilitate an in-depth understanding of betatron radiation from LWFA process and a novel radiation source of high-quality photon beams in the MeV regime.

  13. Estrogens decrease {gamma}-ray-induced senescence and maintain cell cycle progression in breast cancer cells independently of p53

    SciTech Connect

    Toillon, Robert-Alain . E-mail: robert.toillon@univ-lille1.fr; Magne, Nicolas; Laios, Ioanna; Castadot, Pierre; Kinnaert, Eric; Van Houtte, Paul; Desmedt, Christine B.Sc.; Leclercq, Guy; Lacroix, Marc

    2007-03-15

    Purpose: Sequential administration of radiotherapy and endocrine therapy is considered to be a standard adjuvant treatment of breast cancer. Recent clinical reports suggest that radiotherapy could be more efficient in association with endocrine therapy. The aim of this study was to evaluate the estrogen effects on irradiated breast cancer cells (IR-cells). Methods and Materials: Using functional genomic analysis, we examined the effects of 17-{beta}-estradiol (E{sub 2}, a natural estrogen) on MCF-7 breast cancer cells. Results: Our results showed that E{sub 2} sustained the growth of IR-cells. Specifically, estrogens prevented cell cycle blockade induced by {gamma}-rays, and no modification of apoptotic rate was detected. In IR-cells we observed the induction of genes involved in premature senescence and cell cycle progression and investigated the effects of E{sub 2} on the p53/p21{sup waf1/cip1}/Rb pathways. We found that E{sub 2} did not affect p53 activation but it decreased cyclin E binding to p21{sup waf1/cip1} and sustained downstream Rb hyperphosphorylation by functional inactivation of p21{sup waf1/cip1}. We suggest that Rb inactivation could decrease senescence and allow cell cycle progression in IR-cells. Conclusion: These results may help to elucidate the molecular mechanism underlying the maintenance of breast cancer cell growth by E{sub 2} after irradiation-induced damage. They also offer clinicians a rational basis for the sequential administration of ionizing radiation and endocrine therapies.

  14. Modulation of radiation-induced apoptosis and G{sub 2}/M block in murine T-lymphoma cells

    SciTech Connect

    Palayoor, S.T.; Macklis, R.M.; Bump, E.A.; Coleman, C.N.

    1995-03-01

    Radiation-induced apoptosis in lymphocyte-derived cell lines is characterized by endonucleolytic cleavage of cellular DNA within hours after radiation exposure. We have studied this phenomenon qualitatively (DNA gel electrophoresis) and quantitatively (diphenylamine reagent assay) in murine EL4 T-lymphoma cells exposed to {sup 137}Cs {gamma} irradiation. Fragmentation was discernible within 18-24 h after exposure. It increased with time and dose and reached a plateau after 8 Gy of {gamma} radiation. We studied the effect of several pharmacological agents on the radiation-induced G{sub 2}/M block and DNA fragmentation. The agents which reduced the radiation-induced G{sub 2}/M-phase arrest (caffeine, theobromine, theophylline and 2-aminopurine) enhanced the degree of DNA fragmentation at 24 h. In contrast, the agents which sustained the radiation-induced G{sub 2}/M-phase arrest (TPA, DBcAMP, IBMX and 3-aminobenzamide) inhibited the DNA fragmentation at 24 h. These studies on EL4 lymphoma cells are consistent with the hypothesis that cells with radiation-induced genetic damage are eliminated by apoptosis subsequent to a G{sub 2}/M block. Furthermore, it may be possible to modulate the process of radiation-induced apoptosis in lymphoma cells with pharmacological agents that modify the radiation-induced G{sub 2}/M block, and to use this effect in the treatment of patients with malignant disease. 59 refs., 7 figs.

  15. Determination of canine dose conversion factors in mixed neutron and gamma radiation fields. Technical report

    SciTech Connect

    Torres, B.A.; Bhatt, R.C.; Myska, J.C.; Holland, B.K.

    1996-07-01

    The primary objective of mixed-field neutron/gamma radiation dosimetry in canine irradiation experiments conducted at the Armed Forces Radiobiology Research Institute (AFRRI) is to determine the absorbed midline tissue dose (MLT) at the region of interest in the canine. A dose conversion factor (DCF) can be applied to free-in-air (FIA) dose measurements to estimate the MLT doses to canines. This report is a summary of the measured DCFs that were used to determine the MLT doses in canines at AFRRI from 1979 to 1992.

  16. Use of gamma ray radiation to parallel the plates of a Fabry-Perot interferometer

    NASA Technical Reports Server (NTRS)

    Skinner, Wilbert R.; Hays, Paul B.; Anderson, Sally M.

    1987-01-01

    The use of gamma radiation to parallel the plates of a Fabry-Perot etalon is examined. The method for determining the etalon parallelism, and the procedure for irradiating the posts are described. Changes in effective gap for the etalon over the surface are utilized to measure the parallelism of the Fabry-Perot etalon. An example in which this technique is applied to an etalon of fused silica plates, which are 132 mm in diameter and coded with zinc sulfide and cryolite, with Zerodur spaces 2 cm in length. The effect of the irradiation of the posts on the thermal performance of the etalon is investigated.

  17. Use of gamma ray radiation to parallel the plates of a Fabry-Perot interferometer

    NASA Astrophysics Data System (ADS)

    Skinner, Wilbert R.; Hays, Paul B.; Anderson, Sally M.

    1987-03-01

    The use of gamma radiation to parallel the plates of a Fabry-Perot etalon is examined. The method for determining the etalon parallelism, and the procedure for irradiating the posts are described. Changes in effective gap for the etalon over the surface are utilized to measure the parallelism of the Fabry-Perot etalon. An example in which this technique is applied to an etalon of fused silica plates, which are 132 mm in diameter and coded with zinc sulfide and cryolite, with Zerodur spaces 2 cm in length. The effect of the irradiation of the posts on the thermal performance of the etalon is investigated.

  18. Gamma radiation effects on the dynamic fatigue measurements of glass discs

    NASA Technical Reports Server (NTRS)

    Ananaba, T. O. J.; Kinser, D. L.

    1985-01-01

    Circular specimens of low iron soda lime silicate glass were blasted with grit after having a circular notch etched into their centers. After separation into two groups, one group was exposed to gamma radiation. The fracture strengths of all samples were then tested by the biaxial technique, i.e., specimens were balanced on three balls and loaded in the center by a piston. The irradiated samples had received a 140,000 Gy dose from a Co-60 source. An enhanced interaction between the ambient moisture and the grit-blasted central notch was observed in the irradiated samples, which displayed accelerated corrosion.

  19. Effective Atomic Numbers of Lanthanides with Gamma Radiation for Photon Energy Absorption

    NASA Astrophysics Data System (ADS)

    Shantappa, Anil; Hanagodimath, S. M.

    Effective atomic numbers for photon energy absorption, ZPEA,eff have been calculated for photon from 1 keV to 20 MeV for selected oxides of lanthanides, such as Lanthanum oxide, Cerium oxide, Samarium oxide, Europium oxide, Dysprosium oxide, Thulium oxide, Ytterbium oxide. The ZPEA,eff values then compared with ZPI,eff for photon interaction. The ZPEA,eff values have been found to change with energy and composition of selected lanthanides. Oxides of lanthanides are considered as better shielding materials to the exposure of gamma radiation. The values of effective atomic number for photon energy absorption help in the calculation of absorbed dose.

  20. Experimental investigation of gamma ray radiation effects on 1550nm single mode fiber

    NASA Astrophysics Data System (ADS)

    Liu, Qingfeng; Ma, Jing; Tan, Liying; Zhou, Yanping; Che, Chi; Yang, Qingbo

    2015-03-01

    We compared the degradation of two kinds of 1550nm single-mode optical fibers following the irradiation by gamma ray (60Co). Over a total dose of 9.06104 rad, the absorption coefficient increased while the rates were different between samples. The influence of ionizing radiation is theoretically analyzed. In room temperature annealing experiment, the absorption coefficient of Corning sample was recovered visibly, but Alcatel sample continues to deteriorate. It is suggested that different producing technology and doping are clearly influence the generation and recombination process of color center.

  1. Response of human HTB140 melanoma cells to conventional radiation and hadrons.

    PubMed

    Ristić-Fira, A; Todorović, D; Zakula, J; Keta, O; Cirrone, P; Cuttone, G; Petrović, I

    2011-01-01

    Conventional radiotherapy with X- and gamma-rays is one of the common and effective treatments of cancer. High energy hadrons, i.e., charged particles like protons and (12)C ions, due to their specific physics and radiobiological advantages are increasingly used. In this study, effectiveness of different radiation types is evaluated on the radio-resistant human HTB140 melanoma cells. The cells were irradiated with gamma-rays, the 62 MeV protons at the Bragg peak and in the middle of the spread-out Bragg peak (SOBP), as well as with the 62 MeV/u (12)C ions. The doses ranged from 2 to 24 Gy. Cell survival and proliferation were assessed 7 days after irradiation, whereas apoptosis was evaluated after 48 h. The acquired results confirmed the high radio-resistance of cells, showing better effectiveness of protons than gamma-rays. The best efficiency was obtained with (12)C ions due to higher linear energy transfer. All analyzed radiation qualities reduced cell proliferation. The highest proliferation was detected for (12)C ions because of their large killing capacity followed by small induction of reparable lesions. This enabled unharmed cells to preserve proliferative activity. Irradiations with protons and (12)C ions revealed similar moderate pro-apoptotic ability that is in agreement with the level of cellular radio-resistance. PMID:21777021

  2. The use of gamma radiation for the elimination of Salmonella from frozen meat.

    PubMed

    Ley, F J; Kennedy, T S; Kawashima, K; Roberts, D; Hobbs, B C

    1970-06-01

    The use of a gamma radiation process for the elimination of Salmonella from frozen meat is considered with particular reference to the treatment of boned-out horsemeat and kangaroo meat imported into the UK and intended for use as pet meat.Examination of dose/survival curves produced for several serotypes of Salmonella in frozen meat shows that a radiation dose of 0.6 Mrad. will reduce a population by at least a factor of 10(5). The influence on the radiation resistance of salmonellas of such factors as preirradiation growth in the meat and temperature during irradiation have been examined and considered. It is also demonstrated with both preinoculated and naturally contaminated meat that postirradiation storage in the frozen state does not lead to the revival of irradiated salmonellas.The properties of Salmonella survivors deliberately produced in meat using conditions of irradiation designed to simulate a commercial process are studied after six recycling treatments through the process. There were no important changes in characteristics normally used for identification of Salmonella but radiation resistance was lowered. Survivors grown in situ in meat after irradiation showed an abnormally long lag phase, and removal of competitive microflora in meat by the radiation treatment can influence the growth of salmonellas. PMID:4914090

  3. Spectral analysis of paramagnetic centers induced in human tooth enamel by x-rays and gamma radiation

    NASA Astrophysics Data System (ADS)

    Kirillov, V. A.; Kuchuro, I. I.

    2010-03-01

    Based on study of spectral and relaxation characteristics, we have established that paramagnetic centers induced in tooth enamel by x-rays and gamma radiation are identical in nature. We show that for the same exposure dose, the intensity of the electron paramagnetic resonance (EPR) signal induced by x-radiation with effective energy 34 keV is about an order of magnitude higher than the amplitude of the signal induced by gamma radiation. We have identified a three-fold attenuation of the EPR signal along the path of the x-radiation from the buccal to the lingual side of a tooth, which is evidence that the individual had undergone diagnostic x-ray examination of the dentition or skull. We have shown that the x-ray exposure doses reconstructed from the EPR spectra are an order of magnitude higher than the applied doses, while the dose loads due to gamma radiation are equal to the applied doses. The data obtained indicate that for adequate reconstruction of individual absorbed doses from EPR spectra of tooth enamel in the population subjected to the combined effect of x-radiation and accidental external gamma radiation as a result of the disaster at the Chernobyl nuclear power plant, we need to take into account the contribution to the dose load from diagnostic x-rays in examination of the teeth, jaw, or skull.

  4. Cell to Cell Variability of Radiation-Induced Foci: Relation between Observed Damage and Energy Deposition

    PubMed Central

    Voisin, Pascale; Clairand, Isabelle; Benderitter, Marc; Bottollier-Depois, Jean-François; Barquinero, Joan Francesc

    2016-01-01

    Most studies that aim to understand the interactions between different types of photon radiation and cellular DNA assume homogeneous cell irradiation, with all cells receiving the same amount of energy. The level of DNA damage is therefore generally determined by averaging it over the entire population of exposed cells. However, evaluating the molecular consequences of a stochastic phenomenon such as energy deposition of ionizing radiation by measuring only an average effect may not be sufficient for understanding some aspects of the cellular response to this radiation. The variance among the cells associated with this average effect may also be important for the behaviour of irradiated tissue. In this study, we accurately estimated the distribution of the number of radiation-induced γH2AX foci (RIF) per cell nucleus in a large population of endothelial cells exposed to 3 macroscopic doses of gamma rays from 60Co. The number of RIF varied significantly and reproducibly from cell to cell, with its relative standard deviation ranging from 36% to 18% depending on the macroscopic dose delivered. Interestingly, this relative cell-to-cell variability increased as the dose decreased, contrary to the mean RIF count per cell. This result shows that the dose effect, in terms of the number of DNA lesions indicated by RIF is not as simple as a purely proportional relation in which relative SD is constant with dose. To analyse the origins of this observed variability, we calculated the spread of the specific energy distribution for the different target volumes and subvolumes in which RIF can be generated. Variances, standard deviations and relative standard deviations all changed similarly from dose to dose for biological and calculated microdosimetric values. This similarity is an important argument that supports the hypothesis of the conservation of the association between the number of RIF per nucleus and the specific energy per DNA molecule. This comparison allowed us to calculate a volume of 1.6 μm3 for which the spread of the specific energy distribution could explain the entire variability of RIF counts per cell in an exposed cell population. The definition of this volume may allow to use a microdosimetric quantity to predict heterogeneity in DNA damage. Moreover, this value is consistent with the order of magnitude of the volume occupied by the hydrated sugar-phosphate backbone of the DNA molecule, which is the part of the DNA molecule responsible for strand breaks. PMID:26727594

  5. Preliminary results on soil-emitted gamma radiation and its relation with the local atmospheric electric field at Amieira (Portugal)

    NASA Astrophysics Data System (ADS)

    Lopes, F.; Silva, H. G.; Bárias, S.; Barbosa, S. M.

    2015-10-01

    The atmospheric electric field near the Earth's surface is dominated by atmospheric pollutants and natural radioactivity, with the latter directly linked to radon (222Rn) gas. For a better comprehension on the temporal variability of both the atmospheric electric field and the radon concentration and its relation with local atmospheric variables, simultaneous measurements of soil-emitted gamma radiation and potential gradient (defined from the vertical component of the atmospheric electric field) were taken every minute, along with local meteorological parameters (e.g., temperature, atmospheric pressure, relative humidity and daily solar radiation). The study region is Amieira, part of the Alqueva lake in Alentejo Portugal, where an interdisciplinary meteorological campaign, ALEX2014, took place from June to August 2014. Soil gamma radiation is more sensitive to small concentrations of radon as compared with alpha particles measurements, for that reason it is more suited for sites with low radon levels, as expected in this case. Preliminary results are presented here: statistical and spectral analysis show that i) the potential gradient has a stronger daily cycle as compared with the gamma radiation, ii) most of the energy of the gamma signal is concentrated in the low frequencies (close to 0), contrary to the potential gradient that has most of the energy in frequency 1 (daily cycle) and iii) a short-term relation between gamma radiation and the potential gradient has not been found. Future work and plans are also discussed.

  6. Effect of SPE-like Proton or Photon Radiation on the Kinetics of Mouse Peripheral Blood Cells and Radiation Biological Effectiveness Determinations

    PubMed Central

    Romero-Weaver, A.L.; Wan, X.S.; Diffenderfer, E.S.; Lin, L.

    2013-01-01

    Abstract Exploration missions outside low-Earth orbit are being planned; therefore, it is critical to understand the risk astronauts would be exposed to in the space environment, especially during extravehicular activities (EVAs). Reductions in white blood cell (WBC) numbers can occur as a result of exposure to solar particle event (SPE) radiation. The aim of the present study was to determine the duration of the effects on blood cell numbers from exposure to a single whole-body dose of SPE-like proton radiation or photon radiation as well as to determine the radiation biological effectiveness (RBE) values at those times when radiation exposure causes blood cell numbers to experience the most critical effects when using mice as a model. Our results indicate that both types of radiation cause significant reductions in the numbers of all blood cell types at different times post-irradiation. The RBE values were not significantly different from 1.0. These results indicate that the risk estimations for astronauts from exposure of mice to SPE-like proton radiation are comparable to those previously made for doses of standard reference radiations, suggesting that countermeasures should be developed for the decreases in blood cell counts observed following the exposure of mice to SPE radiation. Key Words: Proton radiation—Gamma radiation—Blood cell counts—Solar particle event. Astrobiology 13, 570–577. PMID:23980767

  7. Solar cell radiation handbook. Addendum 1: 1982-1988

    NASA Technical Reports Server (NTRS)

    Anspaugh, Bruce E.

    1989-01-01

    The Solar Cell Radiation Handbook (JPL Publication 82-69) is updated. In order to maintain currency of solar cell radiation data, recent solar cell designs have been acquired, irradiated with 1 MeV electrons, and measured. The results of these radiation experiments are reported.

  8. Response of a. gamma. -ray ''telescope'' dosimeter to the (n +. gamma. ) radiation from a /sup 239/Pu-Be source

    SciTech Connect

    Attix, F.H.; Pearson, D.W.; DeLuca, P.M. Jr.

    1985-01-01

    The design, construction, and investigation of a gamma-ray telescope that can tell the direction of incident photons is reported. The dosimeter is based on LiF thermoluminescence. The gamma-ray telescope dosimeter was tested with a /sup 239/Pu-Be source and found to perform satisfactorily. For a high-energy neutron field the gamma-ray telescope dosimeter contributes very little to the total dose equivalent. (LEW)

  9. Death of a classified worker probably caused by overexposure to gamma radiation.

    PubMed Central

    Lloyd, D C; Edwards, A A; Fitzsimons, E J; Evans, C D; Railton, R; Jeffrey, P; Williams, T G; White, A D; Ikeya, M; Sumitomo, H

    1994-01-01

    This paper describes the case of an industrial radiographer who was seriously overexposed to gamma radiation. The exact circumstances of this exposure were not established but it was concluded that he was repeatedly irradiated probably to a total average whole body dose of at least 10 Gy over several years. Also, a much larger dose to a hand required its partial amputation. He developed myelodysplasia, which progressed to acute myeloid leukaemia from which he died. Karyotypic examination of the leukaemic blasts showed changes very similar to those associated with secondary leukaemia that may develop after radio or chemotherapy. The paper describes his medical case history, the investigation of his workplace, and the attempts to estimate his radiation dose by chromosomal analysis of blood lymphocytes and electron spin resonance of dental enamel and bone. Images Figure 1 Figure 2 PMID:8000499

  10. SIMILAR RADIATION MECHANISM IN GAMMA-RAY BURSTS AND BLAZARS: EVIDENCE FROM TWO LUMINOSITY CORRELATIONS

    SciTech Connect

    Wang, F. Y.; Yi, S. X.; Dai, Z. G.

    2014-05-01

    Active galactic nuclei and gamma-ray bursts (GRBs) are powerful astrophysical events with relativistic jets. In this Letter, the broadband spectral properties of GRBs and well-observed blazars are compared. The distribution of GRBs is consistent with the well-known blazar sequence including the νL {sub ν}(5 GHz) – α{sub RX} and νL {sub ν}(5 GHz) – ν{sub peak} correlations, where α{sub RX} is defined as the broadband spectral slope in radio-to-X-ray bands, and ν{sub peak} is defined as the spectral peak frequency. Moreover, GRBs occupy the low radio luminosity end of these sequences. These two correlations suggest that GRBs could have a radiation process, i.e., synchrotron radiation, similar to blazars both in the prompt emission and afterglow phases.

  11. Aflatoxins and ochratoxin a reduction in black and white pepper by gamma radiation

    NASA Astrophysics Data System (ADS)

    Jalili, M.; Jinap, S.; Noranizan, M. A.

    2012-11-01

    Irradiation is an important means of decontamination of food commodities, especially spices. The aim of the current study was to investigate the efficacy of gamma radiation (60Co) for decontaminating ochratoxin A (OTA) and aflatoxins B1 (AFB1), B2 (AFB2), G1 (AFG1) and G2 (AFG2) residues in artificially contaminated black and white pepper samples. The moisture content of the pepper samples was set at 12% or 18%, and the applied gamma dose ranged from 5 to 30 kGy. Mycotoxin levels were determined by high-performance liquid chromatography (HPLC) after immunoaffinity column (IAC) chromatography. Both the gamma irradiation dose and moisture content showed significant effects (P<0.05) on mycotoxin reduction. The maximum toxin reductions, found at 18% moisture content and 30 kGy, were 55.2%, 50.6%, 39.2%, 47.7% and 42.9% for OTA, AFB1, AFB2, AFG1 and AFG2, respectively.

  12. Spectroscopic evaluation of painted layer structural changes induced by gamma radiation in experimental models

    NASA Astrophysics Data System (ADS)

    Manea, Mihaela M.; Moise, Ioan V.; Virgolici, Marian; Negut, Constantin D.; Barbu, Olimpia-Hinamatsuri; Cutrubinis, Mihalis; Fugaru, Viorel; Stanculescu, Ioana R.; Ponta, Corneliu C.

    2012-02-01

    The degradation of cultural heritage objects by insects and microorganisms is an important issue for conservators, art specialists and humankind in general. Gamma irradiation is an efficient method of polychrome wooden artifacts disinfestation. Color changes and other modifications in the physical chemical properties of materials induced by gamma irradiation are feared by cultural heritage responsible committees and they have to be evaluated objectively and precisely. In this paper FTIR and FT-Raman spectroscopy methods were used to investigate the structural changes in some experimental models of tempera paint layers on wood following 11 kGy gamma irradiation at two dose rates. Radiation chemistry depends on the particular pigment, matrix formed by protein, resin (in case of varnished samples) and water presence. For the majority of painted layer in experimental models very small spectral variations were observed. Small changes in the FTIR spectra were observed for the raw sienna experimental model: for the higher dose rate the egg yolk protein oxidation peaks and the CH stretching bands due to lipids degradation products increased.

  13. A meta-analysis of leukaemia risk from protracted exposure to low-dose gamma radiation

    PubMed Central

    Schubauer-Berigan, M K

    2010-01-01

    Context More than 400 000 workers annually receive a measurable radiation dose and may be at increased risk of radiation-induced leukaemia. It is unclear whether leukaemia risk is elevated with protracted, low-dose exposure. Objective We conducted a meta-analysis examining the relationship between protracted low-dose ionising radiation exposure and leukaemia. Data sources Reviews by the National Academies and United Nations provided a summary of informative studies published before 2005. PubMed and Embase databases were searched for additional occupational and environmental studies published between 2005 and 2009. Study selection We selected 23 studies that: (1) examined the association between protracted exposures to ionising radiation and leukaemia excluding chronic lymphocytic subtype; (2) were a cohort or nested case–control design without major bias; (3) reported quantitative estimates of exposure; and (4) conducted exposure–response analyses using relative or excess RR per unit exposure. Methods Studies were further screened to reduce information overlap. Random effects models were developed to summarise between-study variance and obtain an aggregate estimate of the excess RR at 100 mGy. Publication bias was assessed by trim and fill and Rosenthal's file drawer methods. Results We found an ERR at 100 mGy of 0.19 (95% CI 0.07 to 0.32) by modelling results from 10 studies and adjusting for publication bias. Between-study variance was not evident (p=0.99). Conclusions Protracted exposure to low-dose gamma radiation is significantly associated with leukaemia. Our estimate agreed well with the leukaemia risk observed among exposed adults in the Life Span Study (LSS) of atomic bomb survivors, providing increased confidence in the current understanding of leukaemia risk from ionising radiation. However, unlike the estimates obtained from the LSS, our model provides a precise, quantitative summary of the direct estimates of excess risk from studies of protracted radiation exposures. PMID:20935290

  14. Breeding biology of Tree Swallows and House Wrens in a gradient of gamma radiation

    SciTech Connect

    Zach, R.; Mayoh, K.R.

    1982-12-01

    In a gradient of gamma radiation from 38.7 mC kg/sup -1/.d/sup -1/ to background levels of 0.05 ..mu..C. kg/sup -1/ . d/sup -1/ to background levels of 0.05 ..mu..C . kg/sup -1/ . d/sup -1/, Tree Swallows (Iridoprocne bicolor) and House Wrens (Troglodytes aedon) avoided nesting in areas of high radiation. Nest boxes selected by swallows and wrens had a mean exposure rate of only 9.3 and 6.6 ..mu..C . kg/sup -1/ . d/sup -1/, respectively. Lateral and canopy vegetation indices and nest hole height and direction could not explain the observed pattern of box selection. Of the boxes with low exposure rates, swallows selected those with little vegetation cover, whereas wrens chose boxes and heavy cover. It appears that the birds responded to radiation levels as low as 100 times background, but it is not clear whether they actually detected radiation or simply responded to secondary clues. The number of swallows and wrens fledged per box was unrelated to radiation exposure. The same was true for number of eggs, hatching success, fledging success, incubation time, and nestling time. Breeding success was reduced because of infertile eggs, eggs with dead embryos, cracked eggs, predation, adverse weather, abandonment, and parasites. The logistic model was ideally suited for describing gains in mass in nestling swallows and wrens. Growth of nestlings was not related to radiation exposure as indicated by the growth rate constant, asymptotic mass, and the proportion of variation explained by the logistic model. Breeding and growth performance were similar in studies not involving experimental radiation.

  15. Breeding biology of tree swallows and house wrens in a gradient of gamma radiation

    SciTech Connect

    Zach, R.; Mayoh, K.R.

    1982-12-01

    In a gradient of gamma radiation ranging from 38.7 mC.kg/sup -1/.d/sup -1/ to background levels of 0.05 ..mu..C.kg/sup -1/.d/sup -1/, Tree Swallows (Iridoprocne bicolor) and House Wrens (Troglodytes aedon) avoided nesting in areas of high radiation. Nest boxes selected by swallows and wrens had a mean exposure rate of only 9.3 and 6.6 ..mu..C.kg/sup -1/.d/sup -1/, respectively. Lateral and canopy vegetation indices and nest hole height and direction could not explain the observed pattern of box selection. Of the boxes with low exposure rates, swallows selected those with little vegetation cover, whereas wrens chose boxes with heavy cover. It appears that the birds responded to radiaton levels as low as 100 times background but it is not clear whether they actually detected radiation or simply responded to secondary clues. The number of swallows and wrens fledged per box was unrelated to radiation exposure. The same was true for number of eggs, hatching success, fledging success, incubation time, and nestling time. Breeding success was reduced because of infertile eggs, eggs with dead embryos, cracked eggs, predation, adverse weather, abandonment, and parasites. The logistic model was ideally suited for describing gains in mass in nestling swallows and wrens. Growth of nestlings was not related to radiation exposure as indicated by the growth rate constant, asymptotic mass, and the proportion of variation explained by the logistic model. The data show that birds avoided adverse effects of radiation by judicious box selection. However, there were indications that at higher breeding densities birds may use high-exposure boxes, where breeding success or growth of nestlings may become reduced due to radiation.

  16. Modification of fecundity and fertility during oogenesis by. gamma. radiation and/or ozone with a cytological analysis in the ectoparasitic wasp, Habrobracon juglandis (Ashmead)

    SciTech Connect

    Ofuoku, E.E.

    1984-01-01

    In Experiment I, adult female wasps were exposed to ozone for 0, 2, 4, 6, 8, 10, 12, 16, 24, and 27 h. The results indicated that the 27 h of ozone exposure produced 100% lethality on the first day. Exposures below 27 h progressively decreased life span with increasing length of exposure. In Experiment II A, adult virgin Habrobracon females were exposed to ozone for 0, 2, 4, 6, 8, 10, 12, 16, and 24 h to determine the effects of ozone on fecundity (egg laying ability) and fertility (egg hatching ability). The results showed that ozone significantly decreased fecundity and fertility in all meiotic stages except metaphase I. In Experiment II B, adult virgin Habrobracon females were exposed to Co-60 ..gamma.. radiation. All treated wasps showed significant progressive decreases in fecundity and fertility with increases in radiation dose. In Experiment II C, adult virgin Habrobracon females were exposed to Co-60 ..gamma.. radiation, to ozone, or to combinations thereof to determine the effects of these insults on fecundity and fertility. Together or singly ozone and radiation reduced fecundity and fertility. In Experiment III, adult virgin Habrobracon females were exposed to the conditions of Experiment II C to correlate by cytological examination of the ovarioles the effects of ionizing radiation and/or ozone on the germ cells at specific meiotic stages. Results obtained from the cytological study explain the fecundity and fertility observations.

  17. Isolation and characterization of mold fungi and insects infecting sawmill wood, and their inhibition by gamma radiation

    NASA Astrophysics Data System (ADS)

    Kalawate, Aparna; Mehetre, Sayaji

    2015-12-01

    This article describes the isolation, identification, and characterization of wood-rotting fungi and insects, and their inhibition was studied using gamma radiation. Products manufactured from plantation timber species are deteriorated by wood-rotting fungi such as Hypocrea lixii, Fusarium proliferatum, and Aspergillus flavus, and insects such as powderpost beetles. Proper preservation methods are necessary for ensuring a long service life of wood products. In this study, wood samples were treated with 2.5% copper ethanolamine boron (CEB) (10% w/v) and subsequently irradiated with gamma rays (10 kGy). It was observed that CEB-treated and gamma-irradiated samples controlled fungi and powderpost beetles significantly. As wood is a dead organic material, penetration of chemicals into it is very difficult. Gamma rays easily pass through wooden objects with hidden eggs and dormant spores of insects and fungi, respectively. Gamma irradiation was proved very effective in reducing damage caused by both fungi and insects.

  18. Evaluation of The Combined Effects of Hyperthermia, Cobalt-60 Gamma Rays and IUdR on Cultured Glioblastoma Spheroid Cells and Dosimetry Using TLD-100

    PubMed Central

    Neshasteh-Riz, Ali; Rahdani, Rozhin; Mostaar, Ahmad

    2014-01-01

    Objective In radiation treatment, the irradiation which is effective enough to control the tumors far exceeds normal-tissues tolerance. Thus to avoid such unfavourable outcomes, some methods sensitizing the tumor cells to radiation are used. Iododeoxyuridine (IUdR) is a halogenated thymidine analogue that known to be effective as a radiosensitizer in human cancer therapy. Improving the potential efficacy of radiation therapy after combining to hyperthermia depends on the magnitude of the differential sensitization of the hyperthermic effects or on the differential cytotoxicity of the radiation effects on the tumor cells. In this study, we evaluated the combined effects of IUdR, hyperthermia and gamma rays of 60Co on human glioblastoma spheroids culture. Materials and Methods In this experimental study,the cultured spheroids with 100µm diameter were treated by 1 µM IUdR, 43°C hyperthermia for an hour and 2 Gy gamma rays, respectively. The DNA damages induced in cells were compared using alkaline comet assay method, and dosimetry was then performed by TLD-100. Comet scores were calculated as mean ± standard error of mean (SEM) using one-way ANOVA. Results Comparison of DNA damages induced by IUdR and hyperthermia + gamma treatment showed 2.67- and 1.92-fold enhancement, respectively, as compared to the damages induced by radiation alone or radiation combined IUdR. Dosimetry results showed the accurate dose delivered to cells. Conclusion Analysis of the comet tail moments of spheroids showed that the radiation treatments combined with hyperthermia and IUdR caused significant radiosensitization when compared to related results of irradiation alone or of irradiation with IUdR. These results suggest a potential clinical advantage of combining radiation with hyperthermia and indicate effectiveness of hyperthermia treatment in inducing cytotoxicity of tumor cells. PMID:24611138

  19. A human esophageal epithelial cell model for study of radiation induced cancer and DNA repair

    NASA Astrophysics Data System (ADS)

    Huff, Janice; Patel, Zarana; Hada, Megumi; Cucinotta, Francis A.

    For cancer risk assessment in astronauts and for countermeasure development, it is essential to understand the molecular mechanisms of radiation carcinogenesis and how these mechanisms are influenced by exposure to the types of radiation found in space. We are developing an in vitro model system for the study of radiation-induced initiation and progression of esophageal carcinoma. Development of squamous cell carcinoma of the esophagus is associated with radiation exposure, as revealed by the significant enhanced in incidence rates for this type of cancer in the survivors of the atomic bomb detonations in Japan. It is also associated with poor nutritional status and micronutrient deficiencies, which are also important issues for long duration spaceflight. The possible synergies between nutritional issues and radiation exposure are unknown. Here we present the results of preliminary characterization of both normal and hTERT-immortalized esophageal epithelial cells grown in 2-dimensional culture. We analyzed DNA repair capacity by measuring the kinetics of formation and loss of gamma-H2AX foci following radiation exposure. Additionally, we analyzed induction of chromosomal aberrations using 3-color fluorescence in situ hybridization (FISH). Data were generated using both low LET (gamma rays) and high LET ions (1000 MeV/nucleon iron.

  20. Deinococcus deserti sp. nov., a gamma-radiation-tolerant bacterium isolated from the Sahara Desert.

    PubMed

    de Groot, Arjan; Chapon, Virginie; Servant, Pascale; Christen, Richard; Saux, Marion Fischer-Le; Sommer, Suzanne; Heulin, Thierry

    2005-11-01

    Two gamma- and UV-radiation-tolerant, Gram-negative, rod-shaped bacterial strains, VCD115T and VCD117, were isolated from a mixture of sand samples collected in the Sahara Desert in Morocco and Tunisia, after exposure of the sand to 15 kGy gamma radiation. Phylogenetic analysis based on 16S rRNA gene sequences and DNA-DNA hybridizations showed that VCD115T and VCD117 are members of a novel species belonging to the genus Deinococcus, with Deinococcus grandis as its closest relative. The DNA G+C contents of VCD115T and VCD117 are 59.8 and 60.6 mol%, respectively. The major fatty acids (straight-chain 15 : 1, 16 : 1, 17 : 1 and 16 : 0), polar lipids (dominated by phosphoglycolipids and glycolipids) and quinone type (MK-8) support the affiliation to the genus Deinococcus. The strains did not grow on rich medium such as trypticase soy broth (TSB), but did grow as whitish colonies on tenfold-diluted TSB. The genotypic and phenotypic properties allowed differentiation of VCD115T and VCD117 from recognized Deinococcus species. Strains VCD115T and VCD117 are therefore identified as representing a novel species, for which the name Deinococcus deserti sp. nov. is proposed, with the type strain VCD115T (=DSM 17065T=LMG 22923T). PMID:16280508

  1. Gamma spectroscopic analysis and associated radiation hazards of building materials used in Egypt.

    PubMed

    El-Taher, A

    2010-02-01

    Radiation exposure of the population can be increased appreciably by the use of building materials containing above-normal levels of naturally occurring radionuclides of terrestrial origin. Using gamma-ray spectrometry, the natural radioactivity levels of 55 samples of natural and manufactured Egyptian building materials have been investigated. The samples were collected from local market and construction sites. From the measured gamma-ray spectra, activity concentrations were determined. The activities were in the ranges 11.7-35.6, 12.4-55.2 and 60-350 Bq kg(-1) for (226)Ra, (232)Th and (40)K, respectively. The activities are compared with available reported data from other countries and with the world average value for soils. The radium equivalent activity Ra(eq), the external hazard index H(ex) and the absorbed dose rate in air D in each sample was evaluated to assess the radiation hazard for people living in dwellings made of the materials studied. All building materials have shown Ra(eq) (range from 37.76 to 116.87 Bq kg(-1)) lower than the limit of 370 Bq kg(-1) adopted by the Organization for Economic Cooperation and Development (OECD). The absorbed dose rate in indoor air is lower than the international recommended value of 55 nGy h(-1) for all test samples. All the materials examined are acceptable for use as building materials as defined by the OECD criterion. PMID:19841012

  2. Influence of gamma radiation on the gel rigidity index and binding capability of gelatin

    SciTech Connect

    Fassihi, A.R.; Parker, M.S.

    1988-10-01

    Changes in the rigidity indices of gelatin gel before and after gamma irradiation were characterized by dynamic mechanical testing, and the significance of these changes on the strength of granules was evaluated. Results illustrate the difficulty of obtaining reproducible values for gels containing less than 20% gelatin. However, rigidity indices for gels with a gelatin content of 20% and higher are consistent and may provide a useful controlling factor for preparation of gelatins of more precise specifications. The data indicate that rigidity degradation kinetics of several concentrations of gelatin gel at different radiation doses are complex, showing both increasing and decreasing rates. These findings strongly suggest that doses of less than 2.0 Mrad of gamma radiation should be used in order to obtain gelatins of acceptable quality for pharmaceutical applications. The crushing strength of granules of lactose powder granulated with irradiated gelatin reveals that the binding capability of such gelatin is significantly reduced. The results obtained for various size fractions and granule hardnesses containing different binder concentrations also suggest that particle size influences the granule strength to a lesser extent than does binder concentration and its consistency.

  3. Advances in commercial application of gamma radiation in tropical fruits at Brazil

    NASA Astrophysics Data System (ADS)

    Sabato, S. F.; Silva, J. M.; Cruz, J. N.; Broisler, P. O.; Rela, P. R.; Salmieri, S.; Lacroix, M.

    2009-07-01

    All regions of Brazil are potential areas for growing tropical fruits. As this country is already a great producer and exporter of tropical fruits, ionizing radiation has been the subject of studies in many commodities. An important project has been carried out to increase the commercial use of gamma radiation in our country. Instituto de Pesquisas Energeticas e Nucleares (IPEN)-CNEN/SP together with field producers in northeast region and partners like International Atomic Energy Agency (IAEA), CIC, Empresa Brasileira Pesquisa na Agricultura (EMBRAPA) joined to demonstrate this technology, its application and commercial feasibility. The objective of this study is to show advances in feasibility demonstrate the quality of the irradiated fruits in an international consignment from Brazil to Canada. In this work, Tommy Atkins mangoes harvested in northeast region of Brazil were sent to Canada. The fruits were treated in a gamma irradiation facility at doses 0.4 and 1.0 kGy. The control group was submitted to hydrothermal treatment (46 °C for 110 min). The fruits were stored at 11 °C for 10 days until the international transportation and kept at an environmental condition (22 °C) for 12 days, where their physical-chemical and sensorial properties were evaluated. The financial part of the feasibility study covers the scope of the investment, including the net working capital and production costs.

  4. Low doses of gamma radiation in the management of postharvest Lasiodiplodia theobromae in mangos

    PubMed Central

    Santos, Alice Maria Gonçalves; Lins, Severina Rodrigues Oliveira; da Silva, Josenilda Maria; de Oliveira, Sônia Maria Alves

    2015-01-01

    The postharvest life of mango is limited by the development of pathogens, especially fungi that cause rot, among which stands out the Lasiodiplodia theobromae. Several control methods have been employed to minimize the damages caused by this fungus, chemical control can leave residues to man and nature; physical control by the use of gamma radiation in combination with modified atmosphere and cold storage. The use of gamma radiation helps to reduce the severity of the pathogen assist in the ripening process of fruits, even at low doses (0.25, 0.35 and 0.45 kGy) chemical properties such as pH, soluble solids, acid ascorbic, titratable acidity and also the quality parameters of the pulp showed no damage that are ideal for trade and consumption of mangoes. This treatment can be extended for use in the management of diseases such as natural infections for penducular rot complex that has as one of L. theobroma pathogens involved. PMID:26413068

  5. Decay strength distributions in {sup 12}C({sup 12}C,{gamma}) radiative capture

    SciTech Connect

    Jenkins, D. G.; Fulton, B. R.; Marley, P.; Fox, S. P.; Glover, R.; Wadsworth, R.; Watson, D. L.; Courtin, S.; Haas, F.; Lebhertz, D.; Beck, C.; Papka, P.; Rousseau, M.; Sanchez i Zafra, A.; Hutcheon, D. A.; Davis, C.; Ottewell, D.; Pavan, M. M.; Pearson, J.; Ruiz, C.

    2007-10-15

    The heavy-ion radiative capture reaction, {sup 12}C({sup 12}C,{gamma}), has been investigated at energies both on- and off-resonance, with a particular focus on known resonances at E{sub c.m.}=6.0, 6.8, 7.5, and 8.0 MeV. Gamma rays detected in a BGO scintillator array were recorded in coincidence with {sup 24}Mg residues at the focal plane of the DRAGON recoil separator at TRIUMF. In this manner, the relative strength of all decay pathways through excited states up to the particle threshold could be examined for the first time. Isovector M1 transitions are found to be a important component of the radiative capture from the E{sub c.m.}=6.0 and 6.8 MeV resonances. Comparison with Monte Carlo simulations suggests that these resonances may have either J=0 or 2, with a preference for J=2. The higher energy resonances at E{sub c.m.}=7.5 and 8.0 MeV have a rather different decay pattern. The former is a clear candidate for a J=4 resonance, whereas the latter has a dominant J=4 character superposed on a J=2 resonant component underneath. The relationship between these resonances and the well-known quasimolecular resonances as well as resonances in breakup and electrofission of {sup 24}Mg into two {sup 12}C nuclei are discussed.

  6. Single-source gamma radiation procedures for improved calibration and measurements in porous media

    SciTech Connect

    Oostrom, M.; Hofstee, C.; Dane, H.; Lenhard, R.J.

    1998-08-01

    When dual-energy gamma radiation systems are employed for measurements in porous media, count rates from both sources are often used to compute parameter values. However, for several applications, the count rates of just one source are insufficient. These applications include the determination of volumetric liquid content values in two-liquid systems and salt concentration values in water-saturated porous media. Single-energy gamma radiation procedures for three applications are described in this paper. Through an error analysis, single-source procedures are shown to reduce the probable error in the determinations considerably. Example calculations and simple column experiments were conducted for each application to compare the performance of the new single-source and standard dual-source methods. In all cases, the single-source methods provided more reliable data than the traditional dual-source methods. In addition, a single-source calibration procedure is proposed to determine incident count rates indirectly. This procedure, which requires packing under saturated conditions, can be used in all single- and dual-source applications and yields accurate porosity and dry bulk density values.

  7. Radiation damage and charge collection effects in Si(Li) gamma-ray detectors

    NASA Astrophysics Data System (ADS)

    Hull, Ethan L.; Pehl, Richard H.; Tindall, Craig; Luke, Paul N.; Kurfess, James D.

    2003-01-01

    The spectroscopy performance of 6-mm thick Si(Li) planar detectors was studied as a function of operating temperature and electric field. The energy resolution of the 662-keV gamma-ray peak from a 137Cs source was used to monitor the spectroscopy performance of the detectors. The efficiency, depletion voltage, leakage current, and noise were also monitored. The effects of radiation damage caused by 200-MeV protons were studied to determine the viability of operation in space. Four detectors, two maintained at 88 K and two maintained at 212 K, were irradiated to a fluence of 8.710 8 p/cm 2. No effects were observed. The two detectors irradiated at 212 K were subsequently irradiated with an additional 8.710 9 p/cm 2, again at 212 K. These detectors then exhibited slight energy resolution degradation. No other radiation damage effects were observed. The resolution degradation increased at higher operating temperature and decreased with higher electric field. Cycling the detectors to room temperature for 14 h eliminated the resolution degradation. The resolution of these detectors is limited by the combination of ballistic deficit and parallel noise in the 220 K range. A significant decrease in the gamma-ray peak count rate, almost certainly caused by surface channel effects, was the most dramatic temperature-dependent effect observed.

  8. Low doses of gamma radiation in the management of postharvest Lasiodiplodia theobromae in mangos.

    PubMed

    Santos, Alice Maria Gonçalves; Lins, Severina Rodrigues Oliveira; Silva, Josenilda Maria da; Oliveira, Sônia Maria Alves de

    2015-01-01

    The postharvest life of mango is limited by the development of pathogens, especially fungi that cause rot, among which stands out the Lasiodiplodia theobromae. Several control methods have been employed to minimize the damages caused by this fungus, chemical control can leave residues to man and nature; physical control by the use of gamma radiation in combination with modified atmosphere and cold storage. The use of gamma radiation helps to reduce the severity of the pathogen assist in the ripening process of fruits, even at low doses (0.25, 0.35 and 0.45 kGy) chemical properties such as pH, soluble solids, acid ascorbic, titratable acidity and also the quality parameters of the pulp showed no damage that are ideal for trade and consumption of mangoes. This treatment can be extended for use in the management of diseases such as natural infections for penducular rot complex that has as one of L. theobroma pathogens involved. PMID:26413068

  9. Pilot scale-up and shelf stability of hydrogel wound dressings obtained by gamma radiation

    NASA Astrophysics Data System (ADS)

    Soler, Dulce Mara; Rodrguez, Yanet; Correa, Hector; Moreno, Ailed; Carrizales, Lila

    2012-08-01

    This study is aimed of producing pilot batches of hydrogel wound dressings by gamma radiation and evaluating their shelf stability. Six batches of 3L capacity were prepared based on poly(vinyl pyrrolidone), agar and polyethylene glycol and they were dispensed in polyester trays, covered with polyester films and sealed in two types of materials: polyethylene bags and vacuum polyethylene bags. Dressings were formed in a single step process for the hydrogel formation and sterilization at 25-30 kGy gamma radiation dose in a JS-9500 Gamma Irradiator (Nordion, Canada). The six batches were initially physicochemical characterized in terms of dimensions and appearance, gel fraction, morphology analysis, hydrogel strength, moisture retention capability and swelling capacity. They were kept under two storage conditions: room temperature (T: 302 C/RH: 70 5%) and refrigerated temperature (T: 53 C) during 24 months and sterility test was performed. The appearance of membranes was transparent, clear, uncut and flexible; the gel fraction of batches was higher than 75% and the hydrogel surface showed a porous structure. There was a slow decrease of the compression rate 20% until 7 h and about 70% at 24 h. Moisture retention capability in 5 h was similar for all the batches, about 40% and 60% at 37 C and at room temperature respectively. The swelling of hydrogels in acidic media was strong and in alkaline media the weight variation remains almost stable until 24 h and then there is a loss of weight. The six batches remained sterile during the stability study in the conditions tested. The pilot batches were consistent from batch to batch and remained stable during 24 months.

  10. Effect of gamma radiation on the inactivation of aflatoxin B1 in food and feed crops

    PubMed Central

    Ghanem, I.; Orfi, M.; Shamma, M.

    2008-01-01

    Samples of food crops (peanut, peeled pistachio, unpeeled pistachio, rice, and corn) and feed (barley, bran, corn) were autoclave-sterilized, and inoculated with 106 of spore suspension of an isolate of Aspergillus flavus fungus known to produce aflatoxin B1 (AFB1) . Following a 10-day period of incubation at 27 C to allow for fungal growth, food and feed samples were irradiated with gamma radiation at the doses 4, 6, and 10 kGy. Results indicated that degradation of AFB1 was positively correlated with the increase in the applied dose of gamma ray for each tested sample. At a dose of 10 kGy percentages of AFB1 degradation reached highest values at 58.6, 68.8, 84.6, 81.1 and 87.8% for peanuts, peeled pistachios, unpeeled pistachios, corn and rice samples, respectively. In feed samples percentages of AFB1 degradation were 45, 66, and 90% in barley, 47, 75, and 86% in bran, and 31, 72, and 84% in corn for the doses of 4, 6, and 10 kGy, respectively. AFB1 degradation in food samples correlated negatively with oil content in irradiated samples. Thus, in peanuts, which contained the highest oil content, percentage of AFB1 degradation at 10 kGy was not more than 56.6%, whereas, the corresponding value in corn, which contained the lowest oil content, reached as high as 80%. The above results indicate the possibility of using gamma radiation as a means of degradation of AFB1 in food and feed crops to levels lower than the maximum allowed levels. PMID:24031308

  11. Radiation grafting of methyl methacrylate monomer on natural rubber latex. [Gamma radiation

    SciTech Connect

    Sundardi, F.; Kadariah, S.

    1984-05-01

    A method of radiation grafting of methyl methacrylate (MMA) monomer on natural rubber (NR) latex has been studied. The irradiation dose in radiation emulsion polymerization of MMA monomer was lower compared to the irradiation dose for grafting of MMA monomer on NR latex, in order to obtain the same degree of conversion. This is due to the size of the rubber particles which are quite large and, hence, not sufficient to ensure an ideal emulsion polymerization. The irradiation dose for radiation grafting of MMA monomer on latex was around 300 krad to obtain a 75% degree of conversion. However, this irradiation dose was lower compared to the irradiation dose for bulk polymerization of MMA momomer, in order to obtain the same degree of conversion. This is due to the gel effect in the viscous media. Radiation grafting of MMA monomer on NR latex does not influence the pH of the latex, but influences the viscosity significantly. The viscosity of the NR latex increased with an increase in irradiation dose, due to the increase of the total solid content in the latex. The MMA monomer converted to P-MMA in NR latex was largely grafted on the NR, or at least insoluble in a solvent for P-MMA, such as acetone or toluene. The hardness of the pure gum vulcanizate increased with an increase in the degree of grafting or P-MMA content, but the other physical properties, such as tensile strength, modulus, elongation at break, and thermal stability, were not greatly influenced by the degree of grafting. 9 references, 3 figures, 5 tables.

  12. The diffuse galactic gamma radiation - The Compton contribution and component separation by energy interval and galactic coordinates

    NASA Technical Reports Server (NTRS)

    Kniffen, D. A.; Fichtel, C. E.

    1981-01-01

    The diffuse high-energy galactic gamma radiation to be expected from cosmic ray interactions with matter and photons is considered with particular emphasis on the contribution of Compton radiation from cosmic ray electrons. The intensity, spectrum and spatial distribution of the expected galactic gamma radiation are estimated based on models of the matter, cosmic ray and photon distributions to take into account the contributions of bremsstrahlung, high-energy cosmic-ray nucleon and interstellar matter interactions as well as Compton interactions between cosmic ray electrons and background photons. Results suggest that the Compton gamma ray contribution from cosmic ray electron interactions with galactic visible and infrared photons is substantially larger than previously believed. Analysis of the energy spectra and latitude dependence of the various sources reveals that the Compton radiation, bremsstrahlung and nuclear cosmic ray-matter interaction radiation should be separable, with Compton radiation dominating at energies from 10 to 100 MeV at galactic latitudes greater than several degrees. Results demonstrate the potential of gamma ray observations in studies of galactic structure, cosmic ray electrons and galactic photon density.

  13. Interferon-alpha and interferon-gamma differentially affect pancreatic beta-cell phenotype and function.

    PubMed

    Baldeón, M E; Chun, T; Gaskins, H R

    1998-07-01

    To better clarify individual roles of interferon (IFN)-alpha and IFN-gamma in beta-cell pathology during the onset of type 1 diabetes mellitus, we compared the effects of these cytokines on insulin production and major histocompatibility complex (MHC) gene expression in pancreatic beta-cell lines. IFN-gamma but not IFN-alpha decreased secreted and intracellular insulin concentrations in betaTC6-F7 and betaTC3 cells. Likewise, IFN-gamma but not IFN-alpha treatment of beta-cells upregulated mRNA expression of MHC class IA antigen-processing genes and surface expression of class IA molecules. Alternatively, class IA MHC expression was upregulated by IFN-gamma and IFN-alpha in the P388D1 macrophage cell line. The observation of constitutive Ifn-alpha6 mRNA expression by a differentiated beta-cell line substantiates previous indications that local expression of IFN-alpha in islets may trigger insulitis. Evidence that IFN-gamma, a product of infiltrating leukocytes, directly decreases beta-cell glucose sensitivity and increases MHC class IA cell surface expression supports the postulate that IFN-gamma magnifies the insulitic process. PMID:9688831

  14. Measurement of Branching Fractions in Radiative BDecays to eta K gamma and Search for B Decays to eta' K gamma

    SciTech Connect

    Aubert, B.

    2006-03-31

    The authors present measurements of the B {yields} {eta}K{gamma} branching fractions and upper limits for the B {yields} {eta}'K{gamma} branching fractions. For B{sup +} {yields} {eta}K{sup +}{gamma} they also measure the time-integrated charge asymmetry. The data sample, collected with the BABAR detector at the Stanford Linear Accelerator Center, represents 232 x 10{sup 6} produced B{bar B} pairs. The results for branching fractions and upper limits at 90% C.L. in units of 10{sup -6} are: {Beta}(B{sup 0} {yields} {eta}K{sup 0}{gamma}) = 11.3{sub -2.6}{sup +2.8} {+-} 0.6, {Beta}(B{sup +} {yields} {eta}K{sup +}{gamma}) = 10.0 {+-} 1.3 {+-} 0.5, {Beta}(B{sup 0} {yields} {eta}'K{sup 0}{gamma}) < 6.6, {Beta}(B{sup +} {yields} {eta}'K{sup +}{gamma}) < 4.2. The charge asymmetry in the decay B{sup +} {yields} {eta}K{sup +}{gamma} is {Alpha}{sub ch} = -0.09 {+-} 0.12 {+-} 0.01. The first errors are statistical and the second systematic.

  15. A new analytical formula for neutron capture gamma dose calculations in double-bend mazes in radiation therapy

    PubMed Central

    Ghiasi, Hosein; Mesbahi, Asghar

    2012-01-01

    Background Photoneutrons are produced in radiation therapy with high energy photons. Also, capture gamma rays are the byproduct of neutrons interactions with wall material of radiotherapy rooms. Aim In the current study an analytical formula was proposed for capture gamma dose calculations in double bend mazes in radiation therapy rooms. Materials and methods A total of 40 different layouts with double-bend mazes and a 18MeV photon beam of Varian 2100 Clinac were simulated using MCNPX Monte Carlo (MC) code. Neutron capture gamma ray dose equivalent was calculated by the MC method along the maze and at the maze entrance door of all the simulated rooms. Then, all MC resulted data were fitted to an empirical formula for capture gamma dose calculations. WuMcGinley analytical formula for capture gamma dose equivalent at the maze entrance door in single-bend mazes was also used for comparison purposes. Results For capture gamma dose equivalents at the maze entrance door, the difference of 211% was seen between MC and the derived equation, while the difference of 3687% was found between MC and the WuMcGinley methods. Conclusion Our results showed that the derived formula results were consistent with the MC results for all of 40 different geometries. However, as a new formula, further evaluations are required to validate its use in practical situations. Finally, its application is recommend for capture gamma dose calculations in double-bend mazes to improve shielding calculations. PMID:24377027

  16. SOLIDIFICATION TESTING FOR A HIGH ACTIVITY WASTESTREAM FROM THE SAVANNAH RIVER SITE USING GROUT AND GAMMA RADIATION SHEILDING MATERIALS - 10017

    SciTech Connect

    Burns, H.

    2009-11-10

    The U.S. Department of Energy (DOE) tasked MSE Technology Applications, Inc. (MSE) with evaluating grouts that include gamma radiation shielding materials to solidify surrogates of liquid aqueous radioactive wastes from across the DOE Complex. The Savannah River Site (SRS) identified a High Activity Waste (HAW) that will be treated and solidified at the Waste Solidification Building (WSB) for surrogate grout testing. The HAW, which is produced at the Mixed Oxide Fuel Fabrication Facility (MFFF), is an acidic aqueous wastestream generated by the alkaline treatment process and the aqueous purification process. The HAW surrogate was solidified using Portland cement with and without the inclusion of different gamma radiation shielding materials to determine the shielding material that is the most effective to attenuate gamma radiation for this application.

  17. Synergistic effects in the short-term preservation of hides with antiseptics and gamma radiation

    NASA Astrophysics Data System (ADS)

    Du Plessis, TA; Russell, AE; Stevens, RCB; Galloway, AC

    The normal time lapse between the skinning and tanning processes of green hides necessitates the need for a short-term preservation technique to be employed. The most common method of bringing about such preservation is the coarse salting of the flesh side of hides. More recently the antiseptic treatment of hides was introduced to overcome the serious environmental pollution brought about by the salting process. The antiseptic treatment, however, must also be carefully controlled to avoid upsetting the biological breakdown processes in effluent plants. The gamma sterilization of such hides presents a non-polluting alternative to these methods. As the nature of this product demands excessively high radiation doses to be effective, which negatively influences the economics of the process and the physical properties of the resultant leather, a combination process employing radiation and antiseptics was investigated. It was observed that the radiation dose could be lowered from 50 kGy to 8 kGy in combination with certain antiseptics, whilst the required antiseptic concentration could be substantially lowered in the presence of radiation. The resultant leather was of an excellent quality whilst minimizing the environmental pollution problem.

  18. The effect of perinatal sup 60 Co gamma radiation on brain weight in beagles

    SciTech Connect

    Hamilton, B.F.; Benjamin, S.A.; Angleton, G.M.; Lee, A.C. )

    1989-08-01

    Beagle dogs were given single, whole-body {sup 60}Co gamma-radiation exposures at one of three prenatal (8, 28, or 55 days postcoitus) or three postnatal (2, 70, or 365 days postpartum) ages to evaluate the relative radiosensitivity of various stages of brain development. A total of 387 dogs received mean doses ranging from 0.16 to 3.83 Gy, and 120 dogs were sham-irradiated. Groups of dogs were sacrificed at preselected times from 70 days to 11 years of age. Brain weight decreased significantly with increasing dose in dogs irradiated at 28 or 55 days postcoitus or at 2 days postpartum. Irradiations at 28 days postcoitus were dramatically more effective in causing a reduction in brain weight than those at 55 days postcoitus or 2 days postpartum. Among dogs given 1.0 Gy or more and followed for up to 4 years, there was a radiation effect evident at all three sensitive exposure ages. Among dogs given lower doses and followed for up to 11 years, there was a significant decrease in brain weight in dogs given 0.80-0.88 Gy at 28 days postcoitus. All decreases in brain weight were present after normalization for radiation-induced reductions in skeletal (body) size. No specific morphologic changes were noted in the brains which showed the radiation-related reductions in size.

  19. Search for radiative penguin decays B(+)-->rho(+)gamma, B(0)-->rho(0)gamma, and B(0)-->omegagamma.

    PubMed

    Aubert, B; Barate, R; Boutigny, D; Couderc, F; Gaillard, J-M; Hicheur, A; Karyotakis, Y; Lees, J P; Tisserand, V; Zghiche, A; Palano, A; Pompili, A; Chen, J C; Qi, N D; Rong, G; Wang, P; Zhu, Y S; Eigen, G; Ofte, I; Stugu, B; Abrams, G S; Borgland, A W; Breon, A B; Brown, D N; Button-Shafer, J; Cahn, R N; Charles, E; Day, C T; Gill, M S; Gritsan, A V; Groysman, Y; Jacobsen, R G; Kadel, R W; Kadyk, J; Kerth, L T; Kolomensky, Yu G; Kukartsev, G; Lynch, G; Mir, L M; Oddone, P J; Orimoto, T J; Pripstein, M; Roe, N A; Ronan, M T; Shelkov, V G; Wenzel, W A; Barrett, M; Ford, K E; Harrison, T J; Hart, A J; Hawkes, C M; Morgan, S E; Watson, A T; Fritsch, M; Goetzen, K; Held, T; Koch, H; Lewandowski, B; Pelizaeus, M; Steinke, M; Boyd, J T; Chevalier, N; Cottingham, W N; Kelly, M P; Latham, T E; Wilson, F F; Cuhadar-Donszelmann, T; Hearty, C; Knecht, N S; Mattison, T S; McKenna, J A; Thiessen, D; Khan, A; Kyberd, P; Teodorescu, L; Blinov, A E; Blinov, V E; Druzhinin, V P; Golubev, V B; Ivanchenko, V N; Kravchenko, E A; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Yushkov, A N; Best, D; Bruinsma, M; Chao, M; Eschrich, I; Kirkby, D; Lankford, A J; Mandelkern, M; Mommsen, R K; Roethel, W; Stoker, D P; Buchanan, C; Hartfiel, B L; Foulkes, S D; Gary, J W; Shen, B C; Wang, K; Del Re, D; Hadavand, H K; Hill, E J; Macfarlane, D B; Paar, H P; Rahatlou, Sh; Sharma, V; Berryhill, J W; Campagnari, C; Dahmes, B; Long, O; Lu, A; Mazur, M A; Richman, J D; Verkerke, W; Beck, T W; Eisner, A M; Heusch, C A; Kroseberg, J; Lockman, W S; Nesom, G; Schalk, T; Schumm, B A; Seiden, A; Spradlin, P; Williams, D C; Wilson, M G; Albert, J; Chen, E; Dubois-Felsmann, G P; Dvoretskii, A; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Ryd, A; Samuel, A; Yang, S; Jayatilleke, S; Mancinelli, G; Meadows, B T; Sokoloff, M D; Abe, T; Blanc, F; Bloom, P; Chen, S; Ford, W T; Nauenberg, U; Olivas, A; Rankin, P; Smith, J G; Zhang, J; Zhang, L; Chen, A; Harton, J L; Soffer, A; Toki, W H; Wilson, R J; Zeng, Q L; Altenburg, D; Brandt, T; Brose, J; Dickopp, M; Feltresi, E; Hauke, A; Lacker, H M; Müller-Pfefferkorn, R; Nogowski, R; Otto, S; Petzold, A; Schubert, J; Schubert, K R; Schwierz, R; Spaan, B; Sundermann, J E; Bernard, D; Bonneaud, G R; Brochard, F; Grenier, P; Schrenk, S; Thiebaux, Ch; Vasileiadis, G; Verderi, M; Bard, D J; Clark, P J; Lavin, D; Muheim, F; Playfer, S; Xie, Y; Andreotti, M; Azzolini, V; Bettoni, D; Bozzi, C; Calabrese, R; Cibinetto, G; Luppi, E; Negrini, M; Piemontese, L; Sarti, A; Treadwell, E; Anulli, F; Baldini-Ferroli, R; Calcaterra, A; de Sangro, R; Finocchiaro, G; Patteri, P; Peruzzi, I M; Piccolo, M; Zallo, A; Buzzo, A; Capra, R; Contri, R; Crosetti, G; Vetere, M Lo; Macri, M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Bailey, S; Brandenburg, G; Chaisanguanthum, K S; Morii, M; Won, E; Dubitzky, R S; Langenegger, U; Bhimji, W; Bowerman, D A; Dauncey, P D; Egede, U; Gaillard, J R; Morton, G W; Nash, J A; Nikolich, M B; Taylor, G P; Charles, M J; Grenier, G J; Mallik, U; Cochran, J; Crawley, H B; Lamsa, J; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Yi, J; Biasini, M; Covarelli, R; Pioppi, M; Davier, M; Giroux, X; Grosdidier, G; Höcker, A; Laplace, S; Diberder, F Le; Lepeltier, V; Lutz, A M; Petersen, T C; Plaszczynski, S; Schune, M H; Tantot, L; Wormser, G; Cheng, C H; Lange, D J; Simani, M C; Wright, D M; Bevan, A J; Chavez, C A; Coleman, J P; Forster, I J; Fry, J R; Gabathuler, E; Gamet, R; Hutchcroft, D E; Parry, R J; Payne, D J; Sloane, R J; Touramanis, C; Back, J J; Cormack, C M; Harrison, P F; Lodovico, F Di; Mohanty, G B; Brown, C L; Cowan, G; Flack, R L; Flaecher, H U; Green, M G; Jackson, P S; McMahon, T R; Ricciardi, S; Salvatore, F; Winter, M A; Brown, D; Davis, C L; Allison, J; Barlow, N R; Barlow, R J; Hart, P A; Hodgkinson, M C; Lafferty, G D; Lyon, A J; Williams, J C; Farbin, A; Hulsbergen, W D; Jawahery, A; Kovalskyi, D; Lae, C K; Lillard, V; Roberts, D A; Blaylock, G; Dallapiccola, C; Flood, K T; Hertzbach, S S; Kofler, R; Koptchev, V B; Moore, T B; Saremi, S; Staengle, H; Willocq, S; Cowan, R; Sciolla, G; Sekula, S J; Taylor, F; Yamamoto, R K; Mangeol, D J J; Patel, P M; Robertson, S H; Lazzaro, A; Lombardo, V; Palombo, F; Bauer, J M; Cremaldi, L; Eschenburg, V; Godang, R; Kroeger, R; Reidy, J; Sanders, D A; Summers, D J; Zhao, H W; Brunet, S; Côté, D; Taras, P; Nicholson, H; Cavallo, N; Fabozzi, F; Gatto, C; Lista, L; Monorchio, D; Paolucci, P; Piccolo, D; Sciacca, C; Baak, M; Bulten, H; Raven, G; Snoek, H L; Wilden, L; Jessop, C P; Losecco, J M; Allmendinger, T; Gan, K K; Honscheid, K; Hufnagel, D; Kagan, H; Kass, R; Pulliam, T; Rahimi, A M; Ter-Antonyan, R; Wong, Q K; Brau, J; Frey, R; Igonkina, O; Potter, C T; Sinev, N B; Strom, D; Torrence, E; Colecchia, F; Dorigo, A; Galeazzi, F; Margoni, M; Morandin, M; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Tiozzo, G; Voci, C; Benayoun, M; Briand, H; Chauveau, J; David, P; de la Vaissière, Ch; Buono, L Del; Hamon, O; John, M J J; Leruste, Ph; 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Aston, D; Bartoldus, R; Berger, N; Boyarski, A M; Buchmueller, O L; Claus, R; Convery, M R; Cristinziani, M; Nardo, G De; Dong, D; Dorfan, J; Dujmic, D; Dunwoodie, W; Elsen, E E; Fan, S; Field, R C; Glanzman, T; Gowdy, S J; Hadig, T; Halyo, V; Hast, C; Hryn'ova, T; Innes, W R; Kelsey, M H; Kim, P; Kocian, M L; Leith, D W G S; Libby, J; Luitz, S; Luth, V; Lynch, H L; Marsiske, H; Messner, R; Muller, D R; O'grady, C P; Ozcan, V E; Perazzo, A; Perl, M; Petrak, S; Ratcliff, B N; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Simi, G; Snyder, A; Soha, A; Stelzer, J; Su, D; Sullivan, M K; Va'vra, J; Wagner, S R; Weaver, M; Weinstein, A J R; Wisniewski, W J; Wittgen, M; Wright, D H; Yarritu, A K; Young, C C; Burchat, P R; Edwards, A J; Meyer, T I; Petersen, B A; Roat, C; Ahmed, S; Alam, M S; Ernst, J A; Saeed, M A; Saleem, M; Wappler, F R; Bugg, W; Krishnamurthy, M; Spanier, S M; Eckmann, R; Kim, H; Ritchie, J L; Satpathy, A; Schwitters, R F; Izen, J M; Kitayama, I; Lou, X C; Ye, S; Bianchi, F; Bona, M; Gallo, F; Gamba, D; Bosisio, L; Cartaro, C; Cossutti, F; Ricca, G Della; Dittongo, S; Grancagnolo, S; Lanceri, L; Poropat, P; Vitale, L; Vuagnin, G; Panvini, R S; Banerjee, Sw; Brown, C M; Fortin, D; Jackson, P D; Kowalewski, R; Roney, J M; Sobie, R J; Band, H R; Cheng, B; Dasu, S; Datta, M; Eichenbaum, A M; Graham, M; Hollar, J J; Johnson, J R; Kutter, P E; Li, H; Liu, R; Mihalyi, A; Mohapatra, A K; Pan, Y; Prepost, R; Tan, P; von Wimmersperg-Toeller, J H; Wu, J; Wu, S L; Yu, Z; Greene, M G; Neal, H

    2005-01-14

    A search for the decays B-->rho(770)gamma and B0-->omega(782)gamma is performed on a sample of 211 x 10(6) Upsilon(4S)-->BB events collected by the BABAR detector at the SLAC PEP-II asymmetric-energy e(+)e(-) storage ring. No evidence for the decays is seen. We set the following limits on the individual branching fractions: B(B+-->rho(+)gamma)<1.8 x 10(-6), B(B0-->rho(0)gamma)<0.4 x 10(-6), and B(B0-->omegagamma)<1.0 x 10(-6) at the 90% confidence level. We use the quark model to limit the combined branching fraction B [B-->(rho/omega)gamma]<1.2 x 10(-6), from which we determine a constraint on the ratio of Cabibbo-Kobayashi-Maskawa matrix elements |V(td)|/|V(ts)|. PMID:15698065

  20. A specific proteomic response of Sulfolobus solfataricus P2 to gamma radiations.

    PubMed

    Larmony, Sharon; Garnier, Florence; Hoste, Astrid; Nadal, Marc

    2015-11-01

    Sulfolobus solfataricus is an acidophilic hyperthermophilic crenarchaeon living at 80 °C in aerobic conditions. As other thermophilic organisms, S. solfataricus is resistant to gamma irradiation and we studied the response of this microorganism to this ionizing irradiation by monitoring cell growth, DNA integrity and proteome variations. In aerobic conditions, the S. solfataricus genome was fragmented due to the multiple DNA double strand breakages induced by γ-rays and was fully restored within a couple of hours. Comparison of irradiated and unirradiated cell proteomes indicated that only few proteins changed. The proteins identified by mass spectrometry are involved in different cellular pathways including DNA replication, recombination and repair. Interestingly, we observed that some proteins are irradiation dose-specific while others are common to the cell response regardless of the irradiation dose. Most of the proteins highlighted in these conditions seem to act together to allow an efficient cell response to γ-irradiation. PMID:26116887