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Sample records for rate intra-cavitary irradiation

  1. Dosimetric comparison between intra-cavitary breast brachytherapy techniques for accelerated partial breast irradiation and a novel stereotactic radiotherapy device for breast cancer: GammaPod™

    NASA Astrophysics Data System (ADS)

    Ödén, Jakob; Toma-Dasu, Iuliana; Yu, Cedric X.; Feigenberg, Steven J.; Regine, William F.; Mutaf, Yildirim D.

    2013-07-01

    The GammaPod™ device, manufactured by Xcision Medical Systems, is a novel stereotactic breast irradiation device. It consists of a hemispherical source carrier containing 36 Cobalt-60 sources, a tungsten collimator with two built-in collimation sizes, a dynamically controlled patient support table and a breast immobilization cup also functioning as the stereotactic frame for the patient. The dosimetric output of the GammaPod™ was modelled using a Monte Carlo based treatment planning system. For the comparison, three-dimensional (3D) models of commonly used intra-cavitary breast brachytherapy techniques utilizing single lumen and multi-lumen balloon as well as peripheral catheter multi-lumen implant devices were created and corresponding 3D dose calculations were performed using the American Association of Physicists in Medicine Task Group-43 formalism. Dose distributions for clinically relevant target volumes were optimized using dosimetric goals set forth in the National Surgical Adjuvant Breast and Bowel Project Protocol B-39. For clinical scenarios assuming similar target sizes and proximity to critical organs, dose coverage, dose fall-off profiles beyond the target and skin doses at given distances beyond the target were calculated for GammaPod™ and compared with the doses achievable by the brachytherapy techniques. The dosimetric goals within the protocol guidelines were fulfilled for all target sizes and irradiation techniques. For central targets, at small distances from the target edge (up to approximately 1 cm) the brachytherapy techniques generally have a steeper dose fall-off gradient compared to GammaPod™ and at longer distances (more than about 1 cm) the relation is generally observed to be opposite. For targets close to the skin, the relative skin doses were considerably lower for GammaPod™ than for any of the brachytherapy techniques. In conclusion, GammaPod™ allows adequate and more uniform dose coverage to centrally and peripherally

  2. Dosimetric comparison between intra-cavitary breast brachytherapy techniques for accelerated partial breast irradiation and a novel stereotactic radiotherapy device for breast cancer: GammaPod™.

    PubMed

    Ödén, Jakob; Toma-Dasu, Iuliana; Yu, Cedric X; Feigenberg, Steven J; Regine, William F; Mutaf, Yildirim D

    2013-07-01

    The GammaPod™ device, manufactured by Xcision Medical Systems, is a novel stereotactic breast irradiation device. It consists of a hemispherical source carrier containing 36 Cobalt-60 sources, a tungsten collimator with two built-in collimation sizes, a dynamically controlled patient support table and a breast immobilization cup also functioning as the stereotactic frame for the patient. The dosimetric output of the GammaPod™ was modelled using a Monte Carlo based treatment planning system. For the comparison, three-dimensional (3D) models of commonly used intra-cavitary breast brachytherapy techniques utilizing single lumen and multi-lumen balloon as well as peripheral catheter multi-lumen implant devices were created and corresponding 3D dose calculations were performed using the American Association of Physicists in Medicine Task Group-43 formalism. Dose distributions for clinically relevant target volumes were optimized using dosimetric goals set forth in the National Surgical Adjuvant Breast and Bowel Project Protocol B-39. For clinical scenarios assuming similar target sizes and proximity to critical organs, dose coverage, dose fall-off profiles beyond the target and skin doses at given distances beyond the target were calculated for GammaPod™ and compared with the doses achievable by the brachytherapy techniques. The dosimetric goals within the protocol guidelines were fulfilled for all target sizes and irradiation techniques. For central targets, at small distances from the target edge (up to approximately 1 cm) the brachytherapy techniques generally have a steeper dose fall-off gradient compared to GammaPod™ and at longer distances (more than about 1 cm) the relation is generally observed to be opposite. For targets close to the skin, the relative skin doses were considerably lower for GammaPod™ than for any of the brachytherapy techniques. In conclusion, GammaPod™ allows adequate and more uniform dose coverage to centrally and peripherally

  3. Feasibility and Usefulness of Intra-Cavitary Contrast-Enhanced Ultrasound in Percutaneous Nephrostomy.

    PubMed

    Cui, Xin-Wu; Ignee, Andre; Maros, Tiberius; Straub, Bernd; Wen, Jian-Guo; Dietrich, Christoph F

    2016-09-01

    The aim of this study was to evaluate the feasibility and utility of intra-cavitary contrast enhanced ultrasound (ICCEUS) in guiding percutaneous nephrostomy (PCN) and assessing complications. Forty-five ultrasound-guided PCNs were performed in 35 patients with hydronephrosis resulting from urinary tract obstruction. Ultrasound contrast agent (0.1 mL diluted in 20-30 mL saline) was injected through the puncture needle and the drainage tube to precisely locate the device and obstruction, with the fluoroscopy results considered the gold standard. ICCEUS was performed again the next day to assess complications. All 45 PCNs were successfully performed under the guidance of ultrasound. With ICCEUS, we could confirm the correct insertion of needle and catheter and locate the obstruction in all 35 patients, with fluoroscopic results as the gold standard. Catheter dislodgement was diagnosed by administration of ultrasound contrast agent in 5 patients. Hematoma (1 patient) and urine leakage (1 patient) were also observed. With the advantages of lack of exposure to radiation, performance in real time and bedside availability, ICCEUS has the potential to become a new modality to guide PCN and assess catheter-related complications. PMID:27262520

  4. Measuring Degradation Rates Without Irradiance Data

    SciTech Connect

    Pulver, S.; Cormode, D.; Cronin, A.; Jordan, D.; Kurtz, S.; Smith, R.

    2011-02-01

    A method to report PV system degradation rates without using irradiance data is demonstrated. First, a set of relative degradation rates are determined by comparing daily AC final yields from a group of PV systems relative to the average final yield of all the PV systems. Then, the difference between relative and absolute degradation rates is found from a statistical analysis. This approach is verified by comparing to methods that utilize irradiance data. This approach is significant because PV systems are often deployed without irradiance sensors, so the analysis method described here may enable measurements of degradation using data that were previously thought to be unsuitable for degradation studies.

  5. Fission-gas-release rates from irradiated uranium nitride specimens

    NASA Technical Reports Server (NTRS)

    Weinstein, M. B.; Kirchgessner, T. A.; Tambling, T. N.

    1973-01-01

    Fission-gas-release rates from two 93 percent dense UN specimens were measured using a sweep gas facility. Specimen burnup rates averaged .0045 and .0032 percent/hr, and the specimen temperatures ranged from 425 to 1323 K and from 552 to 1502 K, respectively. Burnups up to 7.8 percent were achieved. Fission-gas-release rates first decreased then increased with burnup. Extensive interconnected intergranular porosity formed in the specimen operated at over 1500 K. Release rate variation with both burnup and temperature agreed with previous irradiation test results.

  6. Modeling irradiation creep of graphite using rate theory

    NASA Astrophysics Data System (ADS)

    Sarkar, Apu; Eapen, Jacob; Raj, Anant; Murty, K. L.; Burchell, T. D.

    2016-05-01

    We have examined irradiation induced creep of graphite in the framework of transition state rate theory. Experimental data for two grades of nuclear graphite (H-337 and AGOT) have been analyzed to determine the stress exponent (n) and activation energy (Q) for plastic flow under irradiation. We show that the mean activation energy lies between 0.14 and 0.32 eV with a mean stress-exponent of 1.0 ± 0.2. A stress exponent of unity and the unusually low activation energies strongly indicate a diffusive defect transport mechanism for neutron doses in the range of 3-4 × 1022 n/cm2.

  7. High Rate Proton Irradiation of 15mm Muon Drifttubes

    NASA Astrophysics Data System (ADS)

    Zibell, A.; Biebel, O.; Hertenberger, R.; Ruschke, A.; Schmitt, Ch.; Kroha, H.; Bittner, B.; Schwegler, P.; Dubbert, J.; Ott, S.

    2012-08-01

    Future LHC luminosity upgrades will significantly increase the amount of background hits from photons, neutrons 11.11d protons in the detectors of the ATLAS muon spectrometer. At the proposed LHC peak luminosity of 5\\cdot 1034(1)/(cm2s), background hit rates of more than 10(kHz)/(cm2) are expected in the innermost forward region, leading to a loss of performance of the current tracking chambers. Based on the ATLAS Monitored Drift Tube chambers, a new high rate capable drift tube detecor using tubes with a reduced diameter of 15mm was developed. To test the response to highly ionizing particles, a prototype chamber of 46 15mm drift tubes was irradiated with a 20 MeV proton beam at the tandem accelerator at the Maier-Leibnitz Laboratory, Munich. Three tubes in a planar layer were irradiated while all other tubes were used for reconstruction of cosmic muon tracks through irradiated and nonirradiated parts of the chamber. To determine the rate capability of the 15mm drifttubes we investigated the effect of the proton hit rate on pulse height, efficiency and spatial resolution of the cosmic muon signals.

  8. Modeling irradiation creep of graphite using rate theory

    DOE PAGESBeta

    Sarkar, Apu; Eapen, Jacob; Raj, Anant; Murty, K. L.; Burchell, T. D.

    2016-02-20

    In this work we examined irradiation induced creep of graphite in the framework of transition state rate theory. Experimental data for two grades of nuclear graphite (H-337 and AGOT) were analyzed to determine the stress exponent (n) and activation energy (Q) for plastic flow under irradiation. Here we show that the mean activation energy lies between 0.14 and 0.32 eV with a mean stress-exponent of 1.0 ± 0.2. A stress exponent of unity and the unusually low activation energies strongly indicate a diffusive defect transport mechanism for neutron doses in the range of 3-4 x 1022 n/cm2.

  9. Modeling irradiation creep of graphite using rate theory

    SciTech Connect

    Sarkar, Apu; Eapen, Dr. Jacob; Raj, Anant; Murty, Prof K.L.; Burchell, Timothy D

    2016-01-01

    We have examined irradiation induced creep of graphite in the framework of transition state rate theory. Experimental data for two grades of nuclear graphite (H-337 and AGOT) have been analyzed to determine the stress exponent (n) and activation energy (Q) for plastic flow under irradiation. We show that the mean activation energy lies between 0.14 and 0.32 eV with a mean stress-exponent of 1.0 +/- 0.2. A stress exponent of unity and the unusually low activation energies strongly indicate a diffusive defect transport mechanism for neutron doses in the range of 3-4 x 10(22) n/cm(2). (C) 2016 Elsevier B.V. All rights reserved.

  10. Long-term results of breast cancer irradiation treatment with low-dose-rate external irradiation

    SciTech Connect

    Pierquin, Bernard; Tubiana, Maurice . E-mail: maurice.tubiana@biomedicale.univ-paris5.fr; Pan, Camille; Lagrange, Jean-Leon; Calitchi, Elie; Otmezguine, Yves

    2007-01-01

    Purpose: The aim of this study was to assess beam therapy with low-dose-rate (LDR) external irradiation in a group of patients with breast cancer. Methods and Materials: This trial compared, from 1986 to 1989, patients with advanced breast cancer treated either by conventional fractionation or low-dose-rate (LDR) external radiotherapy (dose-rate 15 mGy/min, 5 sessions of 9 Gy delivered on 5 consecutive days). Results: A total of 21 patients were included in the fractionated therapy arm. At follow-up 15 years after treatment, 7 local recurrences had occurred, 3 patients had died of cancer, 18 patients were alive, 10 were without evidence of disease, and 6 had evidence of disease. A total of 22 patients had been included in the LDR arm of the study. Of these, 11 had received a dose of 45 Gy; thereafter, in view of severe local reactions, the dose was reduced to 35 Gy. There was no local recurrence in patients who had received 45 Gy, although there were 2 local recurrences among the 11 patients after 35 Gy. The sequelae were severe in patients who received 45 Gy but were comparable to those observed in patients treated by fractionated radiotherapy who received 35 Gy. The higher efficacy of tumor control in patients treated by LDR irradiation as well as the lower tolerance of normal tissue are probably related to the lack of repopulation. Conclusion: Although the patient numbers in this study are limited, based on our study results we conclude that the data for LDR irradiation are encouraging and that further investigation is warranted.

  11. High dose rate intraluminal irradiation in recurrent endobronchial carcinoma

    SciTech Connect

    Seagren, S.L.; Harrell, J.H.; Horn, R.A.

    1985-12-01

    Palliative therapy for previously irradiated patients with symptomatic recurrent endobronchial malignancy is a difficult problem. We have had the opportunity to treat 20 such patients with high dose rate (50-100 rad/min) endobronchial brachytherapy. Eligible patients had received previous high dose thoracic irradiation (TDF greater than or equal to 90), a performance status of greater than or equal to 50, and symptoms caused by a bronchoscopically defined and implantable lesion. The radiation is produced by a small cobalt-60 source (0.7 Ci) remotely afterloaded by cable control. The source is fed into a 4 mm diameter catheter which is placed with bronchoscopic guidance; it may oscillate if necessary to cover the lesion. A dose of 1,000 rad at 1 cm from the source is delivered. We have performed 22 procedures in 20 patients, four following YAG laser debulking. Most had cough, some with hemoptysis. Eight had dyspnea secondary to obstruction and three had obstructive pneumonitis. In 12, symptoms recurred with a mean time to recurrence of 4.3 months (range 1-9 months). Eighteen patients were followed-up and reexamined via bronchoscope 1-2.5 months following the procedure; two were lost to follow-up. All had at least 50 percent clearance of tumor, and six had complete clearance; most regressions were documented on film or videotape. In six, the palliation was durable. The procedure has been well tolerated with no toxicity. We conclude that palliative endobronchial high dose rate brachytherapy is a useful palliative modality in patients with recurrent endobronchial symptomatic carcinoma.

  12. Enhanced charge trapping in bipolar spacer oxides during low-dose-rate irradiation

    SciTech Connect

    Fleetwood, D.M.; Reber, R.A. Jr.; Winokur, P.S.; Kosier, S.L.; Schrimpf, R.D.; Nowlin, R.N.; Pease, R.L.; DeLaus, M.

    1994-03-01

    Thermally-stimulated-current and capacitance-voltage measurements reveal enhanced hole trapping in bipolar spacer-oxide capacitors irradiated at 0 V at low dose rates. Possible mechanisms and implications for bipolar low-rate response are discussed.

  13. An algorithm to evaluate solar irradiance and effective dose rates using spectral UV irradiance at four selected wavelengths.

    PubMed

    Anav, A; Rafanelli, C; Di Menno, I; Di Menno, M

    2004-01-01

    The paper shows a semi-analytical method for environmental and dosimetric applications to evaluate, in clear sky conditions, the solar irradiance and the effective dose rates for some action spectra using only four spectral irradiance values at selected wavelengths in the UV-B and UV-A regions (305, 320, 340 and 380 nm). The method, named WL4UV, is based on the reconstruction of an approximated spectral irradiance that can be integrated, to obtain the solar irradiance, or convoluted with an action spectrum to obtain an effective dose rate. The parameters required in the algorithm are deduced from archived solar spectral irradiance data. This database contains measurements carried out by some Brewer spectrophotometers located in various geographical positions, at similar altitudes, with very different environmental characteristics: Rome (Italy), Ny Alesund (Svalbard Islands, Norway) and Ushuaia (Tierra del Fuego, Argentina). To evaluate the precision of the method, a double test was performed with data not used in developing the model. Archived Brewer measurement data, in clear sky conditions, from Rome and from the National Science Foundation UV data set in San Diego (CA, USA) and Ushuaia, where SUV 100 spectroradiometers operate, were drawn randomly. The comparison of measured and computed irradiance has a relative deviation of about +/-2%. The effective dose rates for action spectra of Erythema, DNA and non-Melanoma skin cancer have a relative deviation of less than approximately 20% for solar zenith angles <50 degrees . PMID:15266087

  14. Analysis of bipolar linear circuit response mechanisms for high and low dose rate total dose irradiations

    SciTech Connect

    Barnaby, H.; Tausch, H.J.; Turfler, R.; Cole, P.; Baker, P.; Pease, R.L.

    1996-12-01

    A methodology is presented for the identification of circuit total dose response mechanisms in bipolar linear microcircuits irradiated at high and low dose rates. This methodology includes manual circuit analysis, circuit simulations with SPICE using extracted device parameters, and selective irradiations of portions of the circuit using a scanning electron microscope.

  15. Enhancement of cell growth rate by light irradiation in the cultivation of Rhodotorula glutinis.

    PubMed

    Yen, Hong-Wei; Zhang, Zhiyong

    2011-10-01

    A yeast, Rhodotorula glutinis, is regarded as a potential microbial oil producer, due to its high lipid content. The flask results of this study indicated that irradiation could increase the growth of R. glutinis compared to that of a batch without irradiation. Further 5-l fermenter results confirmed that irradiation could greatly enhance the cells' growth rate and total lipid productivity. The maximum lipid productivity obtained in the fed-batch operation with 3 LED (light emitting diode) lamps was 0.39 g/l h as compared to 0.34 g/l h in the batch with 3 LED lamps and 0.19 g/l h in the batch without irradiation. Conclusively, the irradiation could significantly increase the cells' growth rate, which, in turn, could be applied to the commercialized production of biodiesel from single cell oils. PMID:21757336

  16. Near-ultraviolet removal rates for subgingival dental calculus at different irradiation angles

    NASA Astrophysics Data System (ADS)

    Schoenly, Joshua E.; Seka, Wolf D.; Rechmann, Peter

    2011-07-01

    The laser ablation rate of subgingival dental calculus irradiated at a 400-nm-wavelength, 7.4-mJ pulse energy, and 85- and 20-deg irradiation angles is measured using laser triangulation. Three-dimensional images taken before and after irradiation create a removal map with 6-μm axial resolution. Fifteen human teeth with subgingival calculus are irradiated in vitro under a cooling water spray with an ~300-μm-diam, tenth-order super-Gaussian beam. The average subgingival calculus removal rates for irradiation at 85 and 20 deg are 11.1+/-3.6 and 11.5+/-5.9 μm/pulse, respectively, for depth removal and 4.5+/-1.7×105 and 4.8+/-2.3×105 μm3/pulse, respectively, for volume removal. The ablation rate is constant at each irradiation site but varies between sites because of the large differences in the physical and optical properties of calculus. Comparison of the average depth- and volume-removal rates does not reveal any dependence on the irradiation angle and is likely due to the surface topology of subgingival calculus samples that overshadows any expected angular dependence.

  17. The independence of irradiation creep in austenitic alloys of displacement rate and helium to dpa ratio

    SciTech Connect

    Garner, F.A.; Toloczko, M.B.; Grossbeck, M.L.

    1997-04-01

    The majority of high fluence data on the void swelling and irradiation creep of austenitic steels were generated at relatively high displacement rates and relatively low helium/dpa levels that are not characteristic of the conditions anticipated in ITER and other anticipated fusion environments. After reanalyzing the available data, this paper shows that irradiation creep is not directly sensitive to either the helium/dpa ratio or the displacement rate, other than through their possible influence on void swelling, since one component of the irradiation creep rate varies with no correlation to the instantaneous swelling rate. Until recently, however, the non-swelling-related creep component was also thought to exhibit its own strong dependence on displacement rate, increasing at lower fluxes. This perception originally arose from the work of Lewthwaite and Mosedale at temperatures in the 270-350{degrees}C range. More recently this perception was thought to extend to higher irradiation temperatures. It now appears, however, that this interpretation is incorrect, and in fact the steady-state value of the non-swelling component of irradiation creep is actually insensitive to displacement rate. The perceived flux dependence appears to arise from a failure to properly interpret the impact of the transient regime of irradiation creep.

  18. Effects of dose rate on microsturctural evolution and swelling in austenitic steels under irradiation

    NASA Astrophysics Data System (ADS)

    Okita, T.; Kamada, T.; Sekimura, N.

    2000-12-01

    Effects of dose rate on microstructural evolution in a simple model austenitic ternary alloy are examined. Annealed specimens are irradiated with fast neutrons at several positions in the core and above core in FFTF/MOTA between 390°C and 435°C in a wide range of doses and dose rates. In Fe-15Cr-16Ni, swelling seems to increase linearly with dose without incubation dose. Cavities are observed even in the specimens irradiated to 0.07 dpa at 1.9×10-9 dpa/s. Both cavity nucleation and growth are enhanced by low dose rates. These are mainly caused by accelerated formation of dislocation loops at lower dose rates. Low dose rates enhance swelling by shortening incubation dose for the onset of steady-state swelling. In the specimens irradiated at higher dose rates to higher doses, high density of dislocation increases average cavity diameter, however decreases cavity density.

  19. Facility for gamma irradiations of cultured cells at low dose rates: design, physical characteristics and functioning.

    PubMed

    Esposito, Giuseppe; Anello, Pasquale; Pecchia, Ilaria; Tabocchini, Maria Antonella; Campa, Alessandro

    2016-09-01

    We describe a low dose/dose rate gamma irradiation facility (called LIBIS) for in vitro biological systems, for the exposure, inside a CO2 cell culture incubator, of cells at a dose rate ranging from few μGy/h to some tens of mGy/h. Three different (137)Cs sources are used, depending on the desired dose rate. The sample is irradiated with a gamma ray beam with a dose rate uniformity of at least 92% and a percentage of primary 662keV photons greater than 80%. LIBIS complies with high safety standards. PMID:27423023

  20. Characterization of the neutron irradiation system for use in the Low-Dose-Rate Irradiation Facility at Sandia National Laboratories.

    SciTech Connect

    Franco, Manuel,

    2014-08-01

    The objective of this work was to characterize the neutron irradiation system consisting of americium-241 beryllium (241AmBe) neutron sources placed in a polyethylene shielding for use at Sandia National Laboratories (SNL) Low Dose Rate Irradiation Facility (LDRIF). With a total activity of 0.3 TBq (9 Ci), the source consisted of three recycled 241AmBe sources of different activities that had been combined into a single source. The source in its polyethylene shielding will be used in neutron irradiation testing of components. The characterization of the source-shielding system was necessary to evaluate the radiation environment for future experiments. Characterization of the source was also necessary because the documentation for the three component sources and their relative alignment within the Special Form Capsule (SFC) was inadequate. The system consisting of the source and shielding was modeled using Monte Carlo N-Particle transport code (MCNP). The model was validated by benchmarking it against measurements using multiple techniques. To characterize the radiation fields over the full spatial geometry of the irradiation system, it was necessary to use a number of instruments of varying sensitivities. First, the computed photon radiography assisted in determining orientation of the component sources. With the capsule properly oriented inside the shielding, the neutron spectra were measured using a variety of techniques. A N-probe Microspec and a neutron Bubble Dosimeter Spectrometer (BDS) set were used to characterize the neutron spectra/field in several locations. In the third technique, neutron foil activation was used to ascertain the neutron spectra. A high purity germanium (HPGe) detector was used to characterize the photon spectrum. The experimentally measured spectra and the MCNP results compared well. Once the MCNP model was validated to an adequate level of confidence, parametric analyses was performed on the model to optimize for potential

  1. Identification of neutron irradiation induced strain rate sensitivity change using inverse FEM analysis of Charpy test

    NASA Astrophysics Data System (ADS)

    Haušild, Petr; Materna, Aleš; Kytka, Miloš

    2015-04-01

    A simple methodology how to obtain additional information about the mechanical behaviour of neutron-irradiated WWER 440 reactor pressure vessel steel was developed. Using inverse identification, the instrumented Charpy test data records were compared with the finite element computations in order to estimate the strain rate sensitivity of 15Ch2MFA steel irradiated with different neutron fluences. The results are interpreted in terms of activation volume change.

  2. Dose Rate Calibration of a Commercial Beta-Particle Irradiator Used In Archeological and Geological Dating

    SciTech Connect

    Bernal, S.M.

    2004-10-31

    The 801E Multiple Sample Irradiator, manufactured by Daybreak Nuclear Systems, is capable of exposing up to 30 samples to beta radiation by placing each sample one by one directly beneath a heavily shielded ceramic Sr-90/Y-90 source and opening a specially designed shutter. Daybreak Nuclear Systems does not provide the {sup 90}Sr/{sup 90}Y dose rate to the sample because of variations of up to 20% in the nominal activity of the beta sources (separately manufactured by AEA Technology). Thus it is left to the end user to determine. Here aluminum oxide doped with carbon (Al{sub 2}O{sub 3}:C), in the form of Landauer's Luxel{trademark}, was irradiated to different known doses using a calibrated {sup 90}Sr/{sup 90}Y beta particle irradiator, and the OSL signal monitored after each irradiation to generate a calibration curve. Comparison of the OSL Signal from the unknown 801E Irradiator dose with the calibration curve enabled the dose and therefore dose rate to be determined. The timing accuracy of the 801E Irradiator was also evaluated and found to be +/- 0.5 seconds. The dose rate of the beta source was found to be 0.147 +/- 0.007 Gy/s.

  3. Chromosomal Aberrations in Normal and AT Cells Exposed to High Dose of Low Dose Rate Irradiation

    NASA Technical Reports Server (NTRS)

    Kawata, T.; Shigematsu, N.; Kawaguchi, O.; Liu, C.; Furusawa, Y.; Hirayama, R.; George, K.; Cucinotta, F.

    2011-01-01

    Ataxia telangiectasia (A-T) is a human autosomally recessive syndrome characterized by cerebellar ataxia, telangiectases, immune dysfunction, and genomic instability, and high rate of cancer incidence. A-T cell lines are abnormally sensitive to agents that induce DNA double strand breaks, including ionizing radiation. The diverse clinical features in individuals affected by A-T and the complex cellular phenotypes are all linked to the functional inactivation of a single gene (AT mutated). It is well known that cells deficient in ATM show increased yields of both simple and complex chromosomal aberrations after high-dose-rate irradiation, but, less is known on how cells respond to low-dose-rate irradiation. It has been shown that AT cells contain a large number of unrejoined breaks after both low-dose-rate irradiation and high-dose-rate irradiation, however sensitivity for chromosomal aberrations at low-dose-rate are less often studied. To study how AT cells respond to low-dose-rate irradiation, we exposed confluent normal and AT fibroblast cells to up to 3 Gy of gamma-irradiation at a dose rate of 0.5 Gy/day and analyzed chromosomal aberrations in G0 using fusion PCC (Premature Chromosomal Condensation) technique. Giemsa staining showed that 1 Gy induces around 0.36 unrejoined fragments per cell in normal cells and around 1.35 fragments in AT cells, whereas 3Gy induces around 0.65 fragments in normal cells and around 3.3 fragments in AT cells. This result indicates that AT cells can rejoin breaks less effectively in G0 phase of the cell cycle? compared to normal cells. We also analyzed chromosomal exchanges in normal and AT cells after exposure to 3 Gy of low-dose-rate rays using a combination of G0 PCC and FISH techniques. Misrejoining was detected in the AT cells only? When cells irradiated with 3 Gy were subcultured and G2 chromosomal aberrations were analyzed using calyculin-A induced PCC technique, the yield of unrejoined breaks decreased in both normal and AT

  4. Degradation and annealing studies on gamma rays irradiated COTS PPD CISs at different dose rates

    NASA Astrophysics Data System (ADS)

    Wang, Zujun; Ma, Yingwu; Liu, Jing; Xue, Yuan; He, Baoping; Yao, Zhibin; Huang, Shaoyan; Liu, Minbo; Sheng, Jiangkun

    2016-06-01

    The degradation and annealing studies on Colbalt-60 gamma-rays irradiated commercial-off-the-shelf (COTS) pinned photodiode (PPD) CMOS image sensors (CISs) at the various dose rates are presented. The irradiation experiments of COTS PPD CISs are carried out at 0.3, 3.0 and 30.0 rad(Si)/s. The COTS PPD CISs are manufactured using a standard 0.18-μm CMOS technology with four-transistor pixel PPD architecture. The behavior of the tested CISs shows a remarkable degradation after irradiation and differs in the dose rates. The dark current, dark signal non-uniformity (DSNU), random noise, saturation output, signal to noise ratio (SNR), and dynamic range (DR) versus the total ionizing dose (TID) at the various dose rates are investigated. The tendency of dark current, DSNU, and random noise increase and saturation output, SNR, and DR to decrease at 3.0 rad(Si)/s are far greater than those at 0.3 and 30.0 rad(Si)/s. The damage mechanisms caused by TID irradiation at the various dose rates are also analyzed. The annealing tests are carried out at room temperature with unbiased conditions after irradiation.

  5. Dose Rate Effects on Damage and Recovery of Radiation Hard Glass Under Gamma Irradiation

    NASA Astrophysics Data System (ADS)

    Menchini, Francesca; Baccaro, Stefania; Cemmi, Alessia; di Sarcina, Ilaria; Fiore, Salvatore; Piegari, Angela

    2014-06-01

    Optical systems employed in space missions are subjected to high fluxes of energetic particles. Their optical properties should be stable throughout the whole mission, to avoid a possible failure of the experiments. Radiation hard glasses are widely used as substrates or windows in high-energy applications, due to their resistance in hostile environments where energetic particles and γ rays are present. In this work we have irradiated radiation resistant glass windows by γ rays from a 60Co source at several doses, from 50 to 3×l05 Gy, and at two different dose rates. The optical properties of the samples have been monitored and the effects of radiations have been measured. Moreover, a partial recovery of the damage has been observed after the end of irradiation. The effects depend on the irradiation dose rate.

  6. Effect of UV irradiation on the evaporation rate of alcohols droplets

    NASA Astrophysics Data System (ADS)

    Korobko, O. V.; Britan, A. V.; Verbinskaya, G. H.; Gavryushenko, D. A.

    2015-06-01

    The effect of ultraviolet irradiation with a wavelength of 390 nm on the evaporation of droplets of the homologous series of alcohols ( n-propanol, n-butanol, n-pentanol, n-heptanol, n-octanol, and n-decanol) at 10, 30, 50, 100, and 200 mm Hg in an atmosphere of dry nitrogen is studied. The values of the evaporation rate of alcohols are calculated with and without irradiation. Starting from n-pentanol, the rate of evaporation grows strongly for droplets of higher alcohols under the effect of low-power irradiation not associated with the heating of the evaporating droplets of alcohols. The obtained results are analyzed by comparing them to experimental data on neutron scattering by alcohols. It is shown that free convection must be considered in order to describe the evaporation process. Expressions of different authors for describing this effect are analyzed.

  7. Allograft tissue irradiation and failure rate after anterior cruciate ligament reconstruction: A systematic review

    PubMed Central

    Dashe, Jesse; Parisien, Robert L; Cusano, Antonio; Curry, Emily J; Bedi, Asheesh; Li, Xinning

    2016-01-01

    AIM: To evaluate whether anterior cruciate ligament (ACL) allograft irradiation is effective for sterility without compromising graft integrity and increasing failure rate. METHODS: A literature search was conducted using PubMed, Cochrane, and Google. The following search terms were used: “Gamma irradiation AND anterior cruciate ligament AND allograft” with a return of 30 items. Filters used included: English language, years 1990-2015. There were 6 hits that were not reviewed, as there were only abstracts available. Another 5 hits were discarded, as they did not pertain to the topic of interest. There were 9 more articles that were excluded: Three studies were performed on animals and 6 studies were meta-analyses. Therefore, a total of 10 articles were applicable to review. RESULTS: There is a delicate dosing crossover where gamma irradiation is both effective for sterility without catastrophically compromising the structural integrity of the graft. Of note, low dose irradiation is considered less than 2.0 Mrad, moderate dose is between 2.1-2.4 Mrad, and high dose is greater than or equal to 2.5 Mrad. Based upon the results of the literature search, the optimal threshold for sterilization was found to be sterilization at less than 2.2 Mrad of gamma irradiation with the important caveat of being performed at low temperatures. The graft selection process also must include thorough donor screening and testing as well as harvesting the tissue in a sterile fashion. Utilization of higher dose (≥ 2.5 Mrad) of irradiation causes greater allograft tissue laxity that results in greater graft failure rate clinically in patients after ACL reconstruction. CONCLUSION: Allograft ACL graft gamma irradiated with less than 2.2 Mrad appears to be a reasonable alternative to autograft for patients above 25 years of age. PMID:27335815

  8. Displacement rate dependence of irradiation creep as predicted by the production bias model

    SciTech Connect

    Woo, C.H.

    1996-04-01

    Recently, it has been shown that the non-swelling component of irradiation creep of austenitic stainless steels is relatively independent of temperature but is sensitive to the displacement rate. An earlier model of Lewthwaite and Mosedale anticipated the sensitivity of displacement rate and attributed it to the flux sensitivity of point defect recombination. The point-defect recombination process does not yield the observed temperature dependence, however, although it does predict an inverse dependence of the creep rate on the square root of the displacement rate that was experimentally observed at relatively low temperatures.

  9. Response of mouse lung to irradiation at different dose-rates

    SciTech Connect

    Hill, R.P.

    1983-07-01

    Groups of LAF1 mice were given thoracic irradiation using /sup 60/Co ..gamma..-rays at dose-rates of 0.05 Gy/min (LDR) or 1.1 Gy/min (HDR) and the death of the animals was monitored as a function of time. It was found that the time pattern of animal deaths was similar for the two different dose-rates. Dose response curves for animals dying at various times up to 500 days after irradiation were calculated and the LD/sub 50/ values determined. The curves for the LD/sub 50/ values, plotted as a function of the time at analysis for treatment at HDR or LDR, were essentially parallel to each other but separated by a factor (LDR/HDR) of about 1.8. This indicates that the sparing effect of LDR treatment is the same for deaths occurring during the early pneumonitis phase or during the late fibrotic phase of lung damage. The available information on the response of patients to whole thoracic irradiation, given for either palliation or piror to bone marrow transplantation, suggests that for similar dose-rates to those studied here the ratio (LDR/HDR) is only 1.2 to 1.3. This difference between the animal and human data may reflect the modifying effect of the large doses of cytotoxic drugs used in combination with the irradiation of bone marrow transplant patients.

  10. Helium generation rates in isotopically tailored Fe-Cr-Ni alloys irradiated in FFTF/MOTA

    SciTech Connect

    Greenwood, L.R.; Garner, F.A. ); Oliver, B.M. . Rocketdyne Div.)

    1991-11-01

    Three Fe-Cr-Ni alloys have been doped with 0.4% {sup 59}Ni for side-by-side irradiations of doped and undoped materials in order to determine the effects of fusion-relevant levels of helium production on microstructural development and mechanical properties. The alloys were irradiated in three successive cycles of the Materials Open Test Assembly (MOTA) located in the Fast Flux Test Facility (FFTF). Following irradiation, helium levels were measured by isotope dilution mass spectrometry. The highest level of helium achieved in doped alloys was 172 appm at 9.1 dpa for a helium(appm)-to-dpa ratio of 18.9. The overall pattern of predicted helium generation rates in doped and undoped alloys is in good agreement with the helium measurements.

  11. Rate of F center formation in sapphire under low-energy low-fluence Ar+ irradiation

    NASA Astrophysics Data System (ADS)

    Epie, E. N.; Wijesundera, D. N.; Tilakaratne, B. P.; Chen, Q. Y.; Chu, W. K.

    2016-03-01

    Ionoluminescence, optical absorption spectroscopy and Rutherford backscattering spectrometry channelling (RBS-C) have been used to study the rate of F center formation with fluence in 170 keV Ar+ irradiated single crystals of α-Al2O3 (sapphire) at room temperature. Implantation fluences range between 1013 cm-2 and 5 ×1014 cm-2. F center density (NF) has been found to display an initial rapid linear increase with Ar+ fluence followed by saturation to a maximum value of 1.74 ×1015 cm-2. Experimental results show a 1-1 correlation between radiation damage in the oxygen sublattice and F center density. This suggest F center kinetics in sapphire under low-energy low-fluence Ar irradiation is a direct consequence of dynamic competition between oxygen defect creation and recombination. An attempt has also been made to extend this discussion to F center kinetics in sapphire under swift heavy ion irradiation.

  12. Stage I, grade III adenocarcinoma of the endometrium treated with surgery and irradiation. Sites of failure and correlation of failure rate with irradiation technique

    SciTech Connect

    Bedwinek, J.; Galakatos, A.; Camel, M.; Kao, M.S.; Stokes, S.; Perez, C.

    1984-07-01

    Eighty-three patients treated with total abdominal hysterectomy and bilateral salpingo-oophorectomy (TAH-BSO) and adjuvant irradiation for Stage I, grade III adenocarcinoma of the endometrium were reviewed. At 5 years, the overall survival was 71%, and the disease-free survival (excluding patients dying of intercurrent disease) was 79%. The failure rates for pelvis alone, pelvis plus distant, and distant alone were 4.8%, 4.8%, and 10.8%, respectively. The most common site of failure was the upper abdomen; 12% of all patients had a failure at this site, either alone or in conjunction with failure at another site. The 24% rate of failure in 50 patients receiving a preoperative implant and external irradiation was not significantly different from the 15% failure rate in 33 patients whose adjuvant irradiation consisted of a preoperative implant only. For the patients who had both an implant and external irradiation, the dose of external irradiation had no correlation with the rate of failure. In contrast, the number of milligram-hours delivered to the uterus by the preoperative implant had a strong inverse correlation with the rate of failure, both for patients receiving an implant only and for those receiving an implant plus external irradiation. The data suggest the following: (1) a high-intensity preoperative uterine implant may be an important adjunct to surgery; and (2) external pelvic irradiation in addition to the implant does not seem to be any more beneficial than an implant alone.

  13. Crack growth rates and fracture toughness of irradiated austenitic stainless steels in BWR environments.

    SciTech Connect

    Chopra, O. K.; Shack, W. J.

    2008-01-21

    In light water reactors, austenitic stainless steels (SSs) are used extensively as structural alloys in reactor core internal components because of their high strength, ductility, and fracture toughness. However, exposure to high levels of neutron irradiation for extended periods degrades the fracture properties of these steels by changing the material microstructure (e.g., radiation hardening) and microchemistry (e.g., radiation-induced segregation). Experimental data are presented on the fracture toughness and crack growth rates (CGRs) of wrought and cast austenitic SSs, including weld heat-affected-zone materials, that were irradiated to fluence levels as high as {approx} 2x 10{sup 21} n/cm{sup 2} (E > 1 MeV) ({approx} 3 dpa) in a light water reactor at 288-300 C. The results are compared with the data available in the literature. The effects of material composition, irradiation dose, and water chemistry on CGRs under cyclic and stress corrosion cracking conditions were determined. A superposition model was used to represent the cyclic CGRs of austenitic SSs. The effects of neutron irradiation on the fracture toughness of these steels, as well as the effects of material and irradiation conditions and test temperature, have been evaluated. A fracture toughness trend curve that bounds the existing data has been defined. The synergistic effects of thermal and radiation embrittlement of cast austenitic SS internal components have also been evaluated.

  14. A multi-millennial reconstruction of the total solar irradiance from the carbon radioisotope production rate

    NASA Astrophysics Data System (ADS)

    Vieira, L. A.; Krivova, N.; Solanki, S.; Balmaceda, L.

    2008-05-01

    The total solar irradiance (TSI) changes by about 0.1% between solar activity minimum and maximum. In addition to this cyclic variation, a secular variation in the irradiance is also plausible. Recent models suggest that the magnitude of the secular increase in the TSI since the Maunder Minimum was comparable to the solar cycle variation. Detailed reconstructions of irradiance since the Maunder minimum are common, but on longer timescales hardly any quantitative reconstructions are available, due to the lack of solar data. Here we present a reconstruction of solar irradiance on millennial time scales. The reconstruction involves two steps: (1) modelling of the evolution of the solar open magnetic flux from the production rate of 14C (as earlier carried out by Solanki et al. 2004 and Usoskin et al. 2007) and (2) evaluation of the solar irradiance from the calculated open magnetic flux. The model is tested by comparing to the TSI reconstruction from the sunspot number for the last 4 centuries. We also discuss limits and uncertainties of the model.

  15. Survival of tumor cells after proton irradiation with ultra-high dose rates

    PubMed Central

    2011-01-01

    Background Laser acceleration of protons and heavy ions may in the future be used in radiation therapy. Laser-driven particle beams are pulsed and ultra high dose rates of >109 Gy s-1may be achieved. Here we compare the radiobiological effects of pulsed and continuous proton beams. Methods The ion microbeam SNAKE at the Munich tandem accelerator was used to directly compare a pulsed and a continuous 20 MeV proton beam, which delivered a dose of 3 Gy to a HeLa cell monolayer within < 1 ns or 100 ms, respectively. Investigated endpoints were G2 phase cell cycle arrest, apoptosis, and colony formation. Results At 10 h after pulsed irradiation, the fraction of G2 cells was significantly lower than after irradiation with the continuous beam, while all other endpoints including colony formation were not significantly different. We determined the relative biological effectiveness (RBE) for pulsed and continuous proton beams relative to x-irradiation as 0.91 ± 0.26 and 0.86 ± 0.33 (mean and SD), respectively. Conclusions At the dose rates investigated here, which are expected to correspond to those in radiation therapy using laser-driven particles, the RBE of the pulsed and the (conventional) continuous irradiation mode do not differ significantly. PMID:22008289

  16. Low-dose-rate, low-dose irradiation delays neurodegeneration in a model of retinitis pigmentosa.

    PubMed

    Otani, Atsushi; Kojima, Hiroshi; Guo, Congrong; Oishi, Akio; Yoshimura, Nagahisa

    2012-01-01

    The existence of radiation hormesis is controversial. Several stimulatory effects of low-dose (LD) radiation have been reported to date; however, the effects on neural tissue or neurodegeneration remain unknown. Here, we show that LD radiation has a neuroprotective effect in mouse models of retinitis pigmentosa, a hereditary, progressive neurodegenerative disease that leads to blindness. Various LD radiation doses were administered to the eyes in a retinal degeneration mouse model, and their pathological and physiological effects were analyzed. LD gamma radiation in a low-dose-rate (LDR) condition rescues photoreceptor cell apoptosis both morphologically and functionally. The greatest effect was observed in a condition using 650 mGy irradiation and a 26 mGy/minute dose rate. Multiple rounds of irradiation strengthened this neuroprotective effect. A characteristic up-regulation (563%) of antioxidative gene peroxiredoxin-2 (Prdx2) in the LDR-LD-irradiated retina was observed compared to the sham-treated control retina. Silencing the Prdx2 using small-interfering RNA administration reduced the LDR-LD rescue effect on the photoreceptors. Our results demonstrate for the first time that LDR-LD irradiation has a biological effect in neural cells of living animals. The results support that radiation exhibits hormesis, and this effect may be applied as a novel therapeutic concept for retinitis pigmentosa and for other progressive neurodegenerative diseases regardless of the mechanism of degeneration involved. PMID:22074737

  17. Strain-rate effects on microstructural deformation in irradiated 316 SS

    NASA Astrophysics Data System (ADS)

    Cole, James I.; Tsai, Hanchung; Allen, Todd R.; Yoshitake, Tsunemitsu; Akasaka, Naoaki; Yamagata, Ichiro; Nakamura, Yasuo

    2006-06-01

    A series of studies have been performed to investigate the post-irradiation deformation and failure behavior of 12% cold-worked 316 stainless steel following irradiation to variety of doses and temperatures in the outer rows of the experimental breeder reactor II (EBR-II). In the current phase of these studies, three sets of samples with different radiation-induced microstructures have been characterized with transmission electron microscopy (TEM) following tensile testing to failure at a 'fast' strain-rate (1 × 10 -3 s -1) and a 'slow' strain-rate (1 × 10 -7 s -1). The samples were irradiated to doses between 9 and 41 dpa at temperatures between 383 and 443 °C. Tensile tests were conducted at a temperature of 430 °C and only regions outside of the necked region were examined. Over the parameters tested, strain-rate had a negligible effect on the deformation microstructure. In addition, there was no clear evidence of localized deformation behavior and the deformation appeared relatively homogeneous, characterized by unfaulting and incorporation of faulted dislocation loops into the general dislocation network structure. The influence of the defect microstructures and strain-rate on deformation behavior is discussed.

  18. Dose rate estimates from irradiated light-water-reactor fuel assemblies in air

    SciTech Connect

    Lloyd, W.R.; Sheaffer, M.K.; Sutcliffe, W.G.

    1994-01-31

    It is generally considered that irradiated spent fuel is so radioactive (self-protecting) that it can only be moved and processed with specialized equipment and facilities. However, a small, possibly subnational, group acting in secret with no concern for the environment (other than the reduction of signatures) and willing to incur substantial but not lethal radiation doses, could obtain plutonium by stealing and processing irradiated spent fuel that has cooled for several years. In this paper, we estimate the dose rate at various distances and directions from typical pressurized-water reactor (PWR) and boiling-water reactor (BWR) spent-fuel assemblies as a function of cooling time. Our results show that the dose rate is reduced rapidly for the first ten years after exposure in the reactor, and that it is reduced by a factor of {approx}10 (from the one year dose rate) after 15 years. Even for fuel that has cooled for 15 years, a lethal dose (LD50) of 450 rem would be received at 1 m from the center of the fuel assembly after several minutes. However, moving from 1 to 5 m reduces the dose rate by over a factor of 10, and moving from 1 to 10 m reduces the dose rate by about a factor of 50. The dose rates 1 m from the top or bottom of the assembly are considerably less (about 10 and 22%, respectively) than 1 m from the center of the assembly, which is the direction of the maximum dose rate.

  19. Intra-cavitary dosimetry for IMRT head and neck treatment using thermoluminescent dosimeters in a naso-oesophageal tube

    NASA Astrophysics Data System (ADS)

    Gagliardi, F. M.; Roxby, K. J.; Engström, P. E.; Crosbie, J. C.

    2009-06-01

    Complex intensity-modulated radiation therapy (IMRT) treatment plans require rigorous quality assurance tests. The aim of this study was to independently verify the delivered dose inside the patient in the region of the treatment site. A flexible naso-gastric tube containing thermoluminescent dosimeters (TLDs) was inserted into the oesophagus via the sinus cavity before the patient's first treatment. Lead markers were also inserted into the tube in order that the TLD positions could be accurately determined from the lateral and anterior-posterior electronic portal images taken prior to treatment. The measured dose was corrected for both daily linac output variations and the estimated dose received from the portal images. The predicted dose for each TLD was determined from the treatment planning system and compared to the measured TLD doses. The results comprise 431 TLD measurements on 43 patients. The mean measured-to-predicted dose ratio was 0.988 ± 0.011 (95% confidence interval) for measured doses above 0.2 Gy. There was a variation in this ratio when the measurements were separated into low dose (0.2-1.0 Gy), medium dose (1.0-1.8 Gy) and high dose (>1.8 Gy) measurements. The TLD-loaded, naso-oesophageal tube for in vivo dose verification is straightforward to implement, and well tolerated by patients. It provides independent reassurance of the delivered dose for head and neck IMRT.

  20. Dose rate dependence of the speciation of neptunium in irradiated solutions of nitric acid

    SciTech Connect

    Precek, M.; Paulenova, A.; Mincher, B.J.; Mezyk, S.P.

    2013-07-01

    The effects of radiation on the redox speciation of neptunium are of interest due to their impact on the performance of separation of neptunium from highly radioactive solutions of dissolved used nuclear fuel. In this study, the influence of dose rate change from 0.4 kGy/h to 6 kGy/h was examined during irradiation of solutions of initially hexavalent 2.0-2.5 mM neptunium in nitric acid of two different concentrations (0.5 and 1 M). Results indicate that the immediate radiolytic steady-state concentration of neptunium(V) were depressed and its initial radiolytic yield was up to 2-times lower (in 1 M HNO{sub 3} solutions)during irradiations with the higher dose rate. The finding is explained on the basis of the enhancement of the role of oxidizing radicals during the radiolytic process. (authors)

  1. Lymphoid cell kinetics under continuous low dose-rate gamma irradiation: A comparison study

    NASA Technical Reports Server (NTRS)

    Foster, B. R.

    1975-01-01

    A comparison study was conducted of the effects of continuous low dose-rate gamma irradiation on cell population kinetics of lymphoid tissue (white pulp) of the mouse spleen with findings as they relate to the mouse thymus. Experimental techniques employed included autoradiography and specific labeling with tritiated thymidine (TdR-(h-3)). The problem studied involved the mechanism of cell proliferation of lymphoid tissue of the mouse spleen and thymus under the stress of continuous irradiation at a dose rate of 10 roentgens (R) per day for 105 days (15 weeks). The aim was to determine whether or not a steady state or near-steady state of cell population could be established for this period of time, and what compensatory mechanisms of cell population were involved.

  2. ADONIS, high count-rate HP-Ge {gamma} spectrometry algorithm: Irradiated fuel assembly measurement

    SciTech Connect

    Pin, P.; Barat, E.; Dautremer, T.; Montagu, T.; Normand, S.

    2011-07-01

    ADONIS is a digital system for gamma-ray spectrometry, developed by CEA. This system achieves high count-rate gamma-ray spectrometry with correct dynamic dead-time correction, up to, at least, more than an incoming count rate of 3.10{sup 6} events per second. An application of such a system at AREVA NC's La Hague plant is the irradiated fuel scanning facility before reprocessing. The ADONIS system is presented, then the measurement set-up and, last, the measurement results with reference measurements. (authors)

  3. Dose-rate and irradiation temperature dependence of BJT SPICE model rad-parameters

    SciTech Connect

    Montagner, X.; Briand, R.; Fouillat, P.; Touboul, A.; Schrimpf, R.D.; Galloway, K.F.; Calvet, M.C.; Calvel, P.

    1998-06-01

    A method to predict low dose rate degradation of bipolar transistors using high dose-rate, high temperature irradiation is evaluated, based on an analysis of four new rad-parameters that are introduced in the BJT SPICE model. This improved BJT model describes the radiation-induced excess base current with great accuracy. The low-level values of the rad-parameters are good tools for evaluating the proposed high-temperature test method because of their high sensitivity to radiation-induced degradation.

  4. Effect of irradiation temperature and strain rate on the mechanical properties of V-4Cr-4Ti irradiated to low doses in fission reactors

    SciTech Connect

    Zinkle, S.J.; Snead, L.L.; Rowcliffe, A.F.; Alexander, D.J.; Gibson, L.T.

    1998-09-01

    Tensile tests performed on irradiated V-(3-6%)Cr-(3-6%)Ti alloys indicate that pronounced hardening and loss of strain hardening capacity occurs for doses of 0.1--20 dpa at irradiation temperatures below {approximately}330 C. The amount of radiation hardening decreases rapidly for irradiation temperatures above 400 C, with a concomitant increase in strain hardening capacity. Low-dose (0.1--0.5 dpa) irradiation shifts the dynamic strain aging regime to higher temperatures and lower strain rates compared to unirradiated specimens. Very low fracture toughness values were observed in miniature disk compact specimens irradiated at 200--320 C to {approximately}1.5--15 dpa and tested at 200 C.

  5. Preliminary experience on the implementation of computed tomography (CT)-based image guided brachytherapy (IGBT) of cervical cancer using high-dose-rate (HDR) Cobalt-60 source in University of Malaya Medical Centre (UMMC)

    NASA Astrophysics Data System (ADS)

    Jamalludin, Z.; Min, U. N.; Ishak, W. Z. Wan; Malik, R. Abdul

    2016-03-01

    This study presents our preliminary work of the computed tomography (CT) image guided brachytherapy (IGBT) implementation on cervical cancer patients. We developed a protocol in which patients undergo two Magnetic Resonance Imaging (MRI) examinations; a) prior to external beam radiotherapy (EBRT) and b) prior to intra-cavitary brachytherapy for tumour identification and delineation during IGBT planning and dosimetry. For each fraction, patients were simulated using CT simulator and images were transferred to the treatment planning system. The HR-CTV, IR-CTV, bladder and rectum were delineated on CT-based contouring for cervical cancer. Plans were optimised to achieve HR-CTV and IR-CTV dose (D90) of total EQD2 80Gy and 60Gy respectively, while limiting the minimum dose to the most irradiated 2cm3 volume (D2cc) of bladder and rectum to total EQD2 90Gy and 75Gy respectively. Data from seven insertions were analysed by comparing the volume-based with traditional point- based doses. Based on our data, there were differences between volume and point doses of HR- CTV, bladder and rectum organs. As the number of patients having the CT-based IGBT increases from day to day in our centre, it is expected that the treatment and dosimetry accuracy will be improved with the implementation.

  6. Crack growth rates of irradiated austenitic stainless steel weld heat affected zone in BWR environments.

    SciTech Connect

    Chopra, O. K.; Alexandreanu, B.; Gruber, E. E.; Daum, R. S.; Shack, W. J.; Energy Technology

    2006-01-31

    Austenitic stainless steels (SSs) are used extensively as structural alloys in the internal components of reactor pressure vessels because of their superior fracture toughness. However, exposure to high levels of neutron irradiation for extended periods can exacerbate the corrosion fatigue and stress corrosion cracking (SCC) behavior of these steels by affecting the material microchemistry, material microstructure, and water chemistry. Experimental data are presented on crack growth rates of the heat affected zone (HAZ) in Types 304L and 304 SS weld specimens before and after they were irradiated to a fluence of 5.0 x 10{sup 20} n/cm{sup 2} (E > 1 MeV) ({approx} 0.75 dpa) at {approx}288 C. Crack growth tests were conducted under cycling loading and long hold time trapezoidal loading in simulated boiling water reactor environments on Type 304L SS HAZ of the H5 weld from the Grand Gulf reactor core shroud and on Type 304 SS HAZ of a laboratory-prepared weld. The effects of material composition, irradiation, and water chemistry on growth rates are discussed.

  7. Lymphoid cell kinetics under continuous low dose-rate gamma irradiation: A comparison study

    NASA Technical Reports Server (NTRS)

    Foster, B. R.

    1975-01-01

    The mechanism of cell proliferation is studied in the lymphoid tissue of the mouse spleen under the stress of continuous irradiation at a dose-rate of 10 roentgens per day for 105 days. Autoradiography and specific labeling with tritiated thymidine were utilized. It was found that at least four compensatory mechanisms maintained a near-steady state of cellular growth: (1) an increase in the proportion of PAS-positive cells which stimulate mitotic activity, (2) maturation arrest of proliferating and differentiating cells which tend to replenish the cells damaged or destroyed by irradiation, (3) an increase in the proportion of cells proliferating, and (4) an increase in the proportion of precursor cells. The results are compared to previous findings observed in the thymus.

  8. The dependence of irradiation creep in austenitic alloys on displacement rate and helium to dpa ratio

    SciTech Connect

    Garner, F.A.; Toloczko, M.B.; Grossbeck, M.L.

    1998-03-01

    Before the parametric dependencies of irradiation creep can be confidently determined, analysis of creep data requires that the various creep and non-creep strains be separated, as well as separating the transient, steady-state, and swelling-driven components of creep. When such separation is attained, it appears that the steady-state creep compliance, B{sub o}, is not a function of displacement rate, as has been previously assumed. It also appears that the formation and growth of helium bubbles under high helium generation conditions can lead to a significant enhancement of the irradiation creep coefficient. This is a transient influence that disappears as void swelling begins to dominate the total strain, but this transient can increase the apparent creep compliance by 100--200% at relatively low ({le}20) dpa levels.

  9. Irradiation swelling behavior and its dependence on temperature, dose rate and dislocation structure evolution

    SciTech Connect

    Surh, M P; Sturgeon, J B; Wolfer, W G

    2004-01-16

    The microstructural evolution of high purity steel under irradiation is modeled including a dislocation density that evolves simultaneously with void nucleation and growth. The predicted void swelling trends versus temperature, flux, and time are compared to experiment and to earlier calculations with a fixed dislocation density. The behavior is further analyzed within a simplified picture of segregation of irradiation defects to microstructural sinks. Agreement with experimental swelling behavior improves when dislocations co-evolve with the void content versus simulations with a fixed dislocation density. The time-dependent dislocation content dictates the rate of void nucleation and shapes the overall void size distribution so as to give steady swelling behavior over long times.

  10. Displacement damage rate dependence of defect cluster formation in α-Fe during irradiation

    NASA Astrophysics Data System (ADS)

    Watanabe, Y.; Morishita, K.; Yamamoto, Y.; Hamaguchi, D.; Tanigawa, H.

    2013-05-01

    Formation kinetics of defect clusters in pure iron during irradiation has been numerically investigated by reaction rate theory, with focusing on nucleation process of vacancy clusters (voids) and self-interstitial-atoms (SIA) clusters under a wide range of atomic displacement damage rate (dpa rate) and temperature conditions. In the rate theory model, the size dependence of thermal stability of a defect cluster is treated for a wide range of cluster size. The numerical analysis shows that the nucleation processes of voids and SIA-clusters are quite different from each other. As to the voids, the nucleation rate of voids depends much on temperature and dpa rate, and has the individual peak temperature for each dpa rate, during which the peak temperature increases with increasing dpa rate. This tendency for void nucleation is similar to that for void swelling observed in experiments. As to the SIA-clusters, the nucleation rate of SIA-clusters does not depend much on temperature and has no peak temperatures because of the relatively high thermal stability of an SIA-cluster, indicating that the conventional model (di-interstitial model) is applicable to describe the nucleation of SIA-clusters in a wide range of temperature.

  11. Growth Rates and Assimilate Partitioning in the Elongation Zone of Tall Fescue Leaf Blades at High and Low Irradiance 1

    PubMed Central

    Schnyder, Hans; Nelson, Curtis J.

    1989-01-01

    Tall fescue (Festuca arundinacea Schreb.) leaf blades elongated 33% faster at continuous low than at continuous high irradiance (60 versus 300 micromoles per second per square meter photosynthetic photon flux density) when temperature of the leaf elongation zone was held constant at 21°C. Increased rate of elongation was associated with a near proportional increase in length of the elongation zone (+38%). In contrast, growth in width and thickness was decreased at low irradiance, resulting in only a 12% increase in leaf area production and 5% less total growth-associated water deposition than at high irradiance. At low irradiance dry matter (DM) import into the elongation zone was 28% less, and 55% less DM was used per unit leaf area produced. DM use in synthesis of structural components (i.e. DM less water-soluble carbohydrates) was only 13% less at low irradiance, whereas water-soluble carbohydrates (WSC) deposition was 43% less. The lower rate of WSC deposition at low irradiance was associated with a higher net rate of monosaccharide deposition (+39%), whereas net deposition rates for sucrose (−27%) and fructan (−56%) were less than at high irradiance. Still, at low irradiance, net fructan accumulation accounted for 64% of WSC deposition, i.e. 25% of DM import, demonstrating the high sink strength of the leaf elongation zone. PMID:16666873

  12. Biological cell irradiation at ultrahigh dose rate employing laser driven protons

    SciTech Connect

    Doria, D.; Kakolee, K. F.; Kar, S.; and others

    2012-07-09

    The ultrashort duration of laser-driven multi-MeV ion bursts offers the possibility of radiobiological studies at extremely high dose rates. Employing the TARANIS Terawatt laser at Queen's University, the effect of proton irradiation at MeV-range energies on live cells has been investigated at dose rates exceeding 10{sup 9}Gy/s as a single exposure. A clonogenic assay showed consistent lethal effects on V-79 live cells, which, even at these dose rates, appear to be in line with previously published results employing conventional sources. A Relative Biological Effectiveness (RBE) of 1.4{+-}0.2 at 10% survival is estimated from a comparison with a 225 kVp X-ray source.

  13. A review of irradiation effects on LWR core internal materials - IASCC susceptibility and crack growth rates of austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Chopra, O. K.; Rao, A. S.

    2011-02-01

    Austenitic stainless steels (SSs) are used extensively as structural alloys in the internal components of light water reactor (LWR) pressure vessels because of their relatively high strength, ductility, and fracture toughness. However, exposure to neutron irradiation for extended periods changes the microstructure (radiation hardening) and microchemistry (radiation-induced segregation) of these steels, and degrades their fracture properties. Irradiation-assisted stress corrosion cracking (IASCC) is another degradation process that affects LWR internal components exposed to neutron radiation. The existing data on irradiated austenitic SSs were reviewed to evaluate the effects of key parameters such as material composition, irradiation dose, and water chemistry on IASCC susceptibility and crack growth rates of these materials in LWR environments. The significance of microstructural and microchemistry changes in the material on IASCC susceptibility is also discussed. The results are used to determine (a) the threshold fluence for IASCC and (b) the disposition curves for cyclic and IASCC growth rates for irradiated SSs in LWR environments.

  14. Evaluation of simulated photolysis rates and their response to solar irradiance variability

    NASA Astrophysics Data System (ADS)

    Sukhodolov, Timofei; Rozanov, Eugene; Ball, William T.; Bais, Alkiviadis; Tourpali, Kleareti; Shapiro, Alexander I.; Telford, Paul; Smyshlyaev, Sergey; Fomin, Boris; Sander, Rolf; Bossay, Sébastien; Bekki, Slimane; Marchand, Marion; Chipperfield, Martyn P.; Dhomse, Sandip; Haigh, Joanna D.; Peter, Thomas; Schmutz, Werner

    2016-05-01

    The state of the stratospheric ozone layer and the temperature structure of the atmosphere are largely controlled by the solar spectral irradiance (SSI) through its influence on heating and photolysis rates. This study focuses on the uncertainties in the photolysis rate response to solar irradiance variability related to the choice of SSI data set and to the performance of the photolysis codes used in global chemistry-climate models. To estimate the impact of SSI uncertainties, we compared several photolysis rates calculated with the radiative transfer model libRadtran, using SSI calculated with two models and observed during the Solar Radiation and Climate Experiment (SORCE) satellite mission. The importance of the calculated differences in the photolysis rate response for ozone and temperature changes has been estimated using 1-D a radiative-convective-photochemical model. We demonstrate that the main photolysis reactions, responsible for the solar signal in the stratosphere, are highly sensitive to the spectral distribution of SSI variations. Accordingly, the ozone changes and related ozone-temperature feedback are shown to depend substantially on the SSI data set being used, which highlights the necessity of obtaining accurate SSI variations. To evaluate the performance of photolysis codes, we compared the results of eight, widely used, photolysis codes against two reference schemes. We show that, in most cases, absolute values of the photolysis rates and their response to applied SSI changes agree within 30%. However, larger errors may appear in specific atmospheric regions because of differences, for instance, in the treatment of Rayleigh scattering, quantum yields, or absorption cross sections.

  15. Slow Ca2+ wave stimulation using low repetition rate femtosecond pulsed irradiation

    NASA Astrophysics Data System (ADS)

    Iwanaga, S.; Smith, N. I.; Fujita, K.; Kawata, S.

    2006-01-01

    We demonstrated stimulation of Ca2+ in living cells by near-infrared laser pulses operated at sub-MHz repetition rates. HeLa cells were exposed to focused 780 nm femtosecond pulses, generated by a titanium-sapphire laser and adjusted by an electro-optical modulator. We found that the laser-induced Ca2+ waves could be generated over three orders of magnitude in repetition rates, with required laser pulse energy varying by less than one order of magnitude. Ca2+ wave speed and gradients were reduced with repetition rate, which allows the technique to be used to modulate the strength and speed of laser-induced effects. By lowering the repetition rate, we found that the laser-induced Ca2+ release is partially mediated by reactive oxygen species (ROS). Inhibition of ROS was successful only at low repetition rates, with the implication that ROS scavengers may in general be depleted in experiments using high repetition rate laser irradiation.

  16. Effect of dose rate of gamma irradiation on biochemical quality and browning of mushrooms Agaricus bisporus

    NASA Astrophysics Data System (ADS)

    Beaulieu, M.; D'Aprano, G.; Lacroix, M.

    2002-03-01

    In order to enhance the shelf-life of edible mature mushrooms Agaricus bisporus, 2 kGy ionising treatments were applied at two different dose rates: 4.5 kGy/h ( I-) and 32 kGy/h ( I+). Both I+ and I- showed 2 and 4 days shelf-life enhancement compared to the control ( C). Before day 9, no significant difference ( p>0.05) in L* value was detected in irradiated mushrooms. However, after day 9, the highest observed L* value (whiteness) was obtained for the mushrooms irradiated in I-. Analyses of phenolic compounds revealed that mushrooms in I- contained more phenols than I+ and C, the latter containing the lower level of phenols. The polyphenol oxidase (PPO) activities of irradiated mushrooms, analysed via catechol oxidase and dopa oxidase substrates, resulted in being significantly lowered ( p⩽0.05) compared to C, with a further decrease in I+. Analyses of the enzymes indicated that PPO activity was lower in I+, contrasting with its lower phenol concentration. Ionising treatments also increased significantly ( p⩽0.05) the phenylalanine ammonia-lyase (PAL) activity. The observation of mushrooms cellular membranes, by electronic microscopy, revealed a better preserved integrity in I- than in I+. It is thus assumed that the browning effect observed in I+ was caused by both the decompartimentation of vacuolar phenol and by the entry of molecular oxygen into the cell cytoplasm. The synergetic effect of the residual active PPO and the molecular oxygen, in contact with the phenols, allowed an increased oxidation rate and, therefore, a more pronounced browning in I+ than in I-.

  17. Energy related germination and survival rates of water-imbibed Arabidopsis seeds irradiated with protons

    NASA Astrophysics Data System (ADS)

    Qin, H. L.; Xue, J. M.; Lai, J. N.; Wang, J. Y.; Zhang, W. M.; Miao, Q.; Yan, S.; Zhao, W. J.; He, F.; Gu, H. Y.; Wang, Y. G.

    2006-04-01

    In order to investigate the influence of ion energy on the germination and survival rates, water-imbibed Arabidopsis seeds were irradiated with protons in atmosphere. The ion fluence used in this experiment was in the range of 4 × 109-1 × 1014 ions/cm2. The ion energy is from 1.1 MeV to 6.5 MeV. According to the structure of the seed and TRIM simulation, the ions with the energy of 6.5 MeV can irradiate the shoot apical meristem directly whereas the ions with the energy of 1.1 MeV cannot. The results showed that both the germination and survival rates decrease while increasing the ion fluence, and the fluence-respond curve for each energy has different character. Besides the shoot apical meristem (SAM), which is generally considered as the main radiobiological target, the existence of a secondary target around SAM is proposed in this paper.

  18. Excess processing of oxidative damaged bases causes hypersensitivity to oxidative stress and low dose rate irradiation.

    PubMed

    Yoshikawa, Y; Yamasaki, A; Takatori, K; Suzuki, M; Kobayashi, J; Takao, M; Zhang-Akiyama, Q-M

    2015-10-01

    Ionizing radiations such as X-ray and γ-ray can directly or indirectly produce clustered or multiple damages in DNA. Previous studies have reported that overexpression of DNA glycosylases in Escherichia coli (E. coli) and human lymphoblast cells caused increased sensitivity to γ-ray and X-ray irradiation. However, the effects and the mechanisms of other radiation, such as low dose rate radiation, heavy-ion beams, or hydrogen peroxide (H2O2), are still poorly understood. In the present study, we constructed a stable HeLaS3 cell line overexpressing human 8-oxoguanine DNA N-glycosylase 1 (hOGG1) protein. We determined the survival of HeLaS3 and HeLaS3/hOGG1 cells exposed to UV, heavy-ion beams, γ-rays, and H2O2. The results showed that HeLaS3 cells overexpressing hOGG1 were more sensitive to γ-rays, OH(•), and H2O2, but not to UV or heavy-ion beams, than control HeLaS3. We further determined the levels of 8-oxoG foci and of chromosomal double-strand breaks (DSBs) by detecting γ-H2AX foci formation in DNA. The results demonstrated that both γ-rays and H2O2 induced 8-oxoguanine (8-oxoG) foci formation in HeLaS3 cells. hOGG1-overexpressing cells had increased amounts of γ-H2AX foci and decreased amounts of 8-oxoG foci compared with HeLaS3 control cells. These results suggest that excess hOGG1 removes the oxidatively damaged 8-oxoG in DNA more efficiently and therefore generates more DSBs. Micronucleus formation also supported this conclusion. Low dose-rate γ-ray effects were also investigated. We first found that overexpression of hOGG1 also caused increased sensitivity to low dose rate γ-ray irradiation. The rate of micronucleus formation supported the notion that low dose rate irradiation increased genome instability. PMID:26059740

  19. Sensitivity of the photolysis rate to the uncertainties in spectral solar irradiance variability

    NASA Astrophysics Data System (ADS)

    Sukhodolov, Timofei; Rozanov, Eugene; Bais, Alkiviadis; Tourpali, Kleareti; Shapiro, Alexander; Telford, Paul; Peter, Thomas; Schmutz, Werner

    2014-05-01

    The state of the stratospheric ozone layer and temperature structure are mostly maintained by the photolytical processes. Therefore, the uncertainties in the magnitude and spectral composition of the spectral solar irradiance (SSI) evolution during the declining phase of 23rd solar cycle have substantial implications for the modeling of the middle atmosphere evolution, leading not only to a pronounced differences in the heating rates but also affecting photolysis rates. To estimate the role of SSI uncertainties we have compared the most important photolysis rates (O2, O3, and NO2) calculated with the reference radiation code libRadtran using SSI for June 2004 and February 2009 obtained from two models (NRL, COSI) and one observation data set based on SORCE observations. We found that below 40 km changes in the ozone and oxygen photolysis can reach several tenths of % caused by the changes of the SSI in the Harley and Huggins bands for ozone and several % for oxygen caused by the changes of the SSI in the Herzberg continuum and Schumann-Runge bands. For the SORCE data set these changes are 2-4 times higher. We have also evaluated the ability of the several photolysis rates calculation methods widely used in atmospheric models to reproduce the absolute values of the photolysis rates and their response to the implied SSI changes. With some remarks all schemes show good results in the middle stratosphere compare to libRadtran. However, in the troposphere and mesosphere there are more noticeable differences.

  20. Interstitial pneumonitis following bone marrow transplantation after low dose rate total body irradiation

    SciTech Connect

    Barrett, A.; Depledge, M.H.; Powles, R.L.

    1983-07-01

    Idiopathic and infective interstitial pneumonitis (IPn) is a common complication after bone marrow transplantation (BMT) in many centers and carries a high mortality. We report here a series of 107 patients with acute leukemia grafted at the Royal Marsden Hospital in which only 11 (10.3%) developed IPn and only 5 died (5%). Only one case of idiopathic IPn was seen. Factors which may account for this low incidence are discussed. Sixty of 107 patients were transplanted in first remission of acute myeloid leukemia (AML) and were therefore in good general condition. Lung radiation doses were carefully monitored and doses of 10.5 Gy were not exceeded except in a group of 16 patients in whom a study of escalating doses of TBI (up to 13 Gy) was undertaken. The dose rate used for total body irradiation (TBI) was lower than that used in other centers and as demonstrated elsewhere by ourselves and others, reduction of dose rate to <0.05 Gy/min may be expected to lead to substantial reduction in lung damage. Threshold doses of approximately 8 Gy for IPn have been reported, but within the dose range of 8 to 10.5 Gy we suggest that dose rate may significantly affect the incidence. Data so far available suggest a true improvement in therapeutic ratio for low dose rate single fraction TBI compared with high dose rate.

  1. Total-body irradiation and cataract incidence: A randomized comparison of two instantaneous dose rates

    SciTech Connect

    Ozsahin, M.; Belkacemi, Y.; Pene, F.; Dominique, C.; Schwartz, L.H.; Uzal, C.; Lefkopoulos, D.; Gindrey-Vie, B.; Vitu-Loas, L.; Touboul, E. )

    1994-01-15

    To assess the influence of instantaneous total-body irradiation dose rate in hematological malignancies, the authors randomized 157 patients according to different instantaneous dose rates. Patients have undergone a total-body irradiation before bone-marrow transplantation according to two different techniques: Either in one fraction (1000 cGy given to the midplane at the level of L4, and 800 cGy to the lungs) or in six fractions (1200 cGy over 3 consecutive days to the midplane at the level of L4, and 900 cGy to the lungs). Patients were randomized according to two instantaneous dose rates, called LOW and HIGH, in single-dose (6 vs. 15 cGy/min) and fractionated (3 vs. 6 cGy/min) TBI groups; there were 77 cases for the LOW and 80 for the HIGH groups, with 57 patients receiving single-dose (28 LOW, 29 HIGH) and 100 patients receiving fractionated total-body irradiation (49 LOW, 51 HIGH). As of July 1992, 16 of 157 patients developed cataracts after 17 to 46 months, with an estimated incidence of 23% at 5 years. Four of 77 patients in the LOW group, 12 of 80 patients in the HIGH group developed cataracts, with 5-year estimated incidences of 12% and 34%, respectively. Ten of 57 patients in the single-dose group, and 6 of 100 patients in the fractionated group developed cataracts, with 5-year estimated incidences of 39% and 13%, respectively. When the subgroups were considered, in the single-dose group, 3 of 28 LOW patients, and 7 of 29 HIGH patients developed cataracts, with 5-year estimated incidences of 24% and 53%, respectively; in the fractionated group, 1 of 49 LOW patients, and 5 of 51 HIGH patients developed cataracts, with 5-year estimated incidences of 4% and 22%, respectively. There was no statistically significant difference in terms of 5-year estimated cataract incidence between the patients receiving steroids and those not. The instantaneous dose rate was the only independent factor influencing the cataractogenesis. 18 refs., 5 figs., 1 tab.

  2. Influence of gamma irradiation effects on the residual alteration rate of the French SON68 nuclear glass

    NASA Astrophysics Data System (ADS)

    Rolland, S.; Tribet, M.; Jollivet, P.; Jégou, C.; Broudic, V.; Marques, C.; Ooms, H.; Toulhoat, P.

    2013-02-01

    The residual rate regime of SON68 nuclear glass has been investigated here by static experiments under external irradiation. The experiments were carried out in a gamma irradiator with 60Co sources. Four dose rates were studied: two high dose rates (5 and 10 kGy h-1) to exacerbate electronic radiation effects, and two lower dose rates (0.8 and 0.05 kGy h-1). The objective of this work is not to assess potential LET effects but to assess more widely electronic effects on the residual rate regime which controls the long term stability of the glass under geological disposal. Fresh glasses were leached in argon atmosphere at 90 °C and at a high surface-area-to-volume ratio (SA/V = 10 000 m-1). Under these conditions the system quickly reaches the residual alteration rate regime. The alteration rate was monitored by solution analyses: the release of glass alteration tracer elements—in particular boron, sodium and lithium—was measured by ICP-AES. The hydrogen peroxide produced by water radiolysis was quantified by chemiluminescence. Radiation effects on the glass and its gel network were characterized by scanning electron microscopy (SEM) and Transmission Electron Microscopy (TEM). Higher H2O2 concentrations were measured on irradiated samples in the presence of glass, suggesting an irradiation effect on the glass and its alteration layer. However, the data obtained on glass alteration show that potential defects or changes induced by gamma irradiation do not modify the kinetics of alteration up to a gamma dose rate of 10 kGy h-1: the residual rates measured for the different dose rates studied are similar and comparable to experiments performed without irradiation. Moreover, these observations are consistent with SEM and TEM characterizations which show that the alteration layer formed under gamma irradiation is similar to the alteration layer formed without irradiation. This study demonstrates that species produced by pure water radiolysis and defects induced by

  3. Differential expression of thymic DNA repair genes in low-dose-rate irradiated AKR/J mice.

    PubMed

    Bong, Jin Jong; Kang, Yu Mi; Shin, Suk Chul; Choi, Seung Jin; Lee, Kyung Mi; Kim, Hee Sun

    2013-01-01

    We previously determined that AKR/J mice housed in a low-dose-rate (LDR) ((137)Cs, 0.7 mGy/h, 2.1 Gy) γ-irradiation facility developed less spontaneous thymic lymphoma and survived longer than those receiving sham or high-dose-rate (HDR) ((137)Cs, 0.8 Gy/min, 4.5 Gy) radiation. Interestingly, histopathological analysis showed a mild lymphomagenesis in the thymus of LDR-irradiated mice. Therefore, in this study, we investigated whether LDR irradiation could trigger the expression of thymic genes involved in the DNA repair process of AKR/J mice. The enrichment analysis of Gene Ontology terms and Kyoto Encyclopedia of Genes and Genomes pathways showed immune response, nucleosome organization, and the peroxisome proliferator-activated receptors signaling pathway in LDR-irradiated mice. Our microarray analysis and quantitative polymerase chain reaction data demonstrated that mRNA levels of Lig4 and RRM2 were specifically elevated in AKR/J mice at 130 days after the start of LDR irradiation. Furthermore, transcriptional levels of H2AX and ATM, proteins known to recruit DNA repair factors, were also shown to be upregulated. These data suggest that LDR irradiation could trigger specific induction of DNA repair-associated genes in an attempt to repair damaged DNA during tumor progression, which in turn contributed to the decreased incidence of lymphoma and increased survival. Overall, we identified specific DNA repair genes in LDR-irradiated AKR/J mice. PMID:23820165

  4. Postoperative vaginal irradiation with high dose rate afterloading technique in endometrial carcinoma stage I

    SciTech Connect

    Sorbe, B.G.; Smeds, A.C. )

    1990-02-01

    A high dose rate ({sup 60}Co) afterloading technique was used for postoperative prophylactic vaginal irradiation in a series of 404 women with endometrial carcinoma Stage I. The total recurrence rate was 3.7% with 0.7% vaginal deposits. The crude 5-year survival rate for the complete series was 91.8% compared to 13.3% for those with recurrences. Depth of myometrial infiltration (greater than 1/3 of the uterine wall) and nuclear grade were the most important prognostic factors. Clinically significant late radiation reactions (bladder and/or rectum) were recorded in 6.9%. Dose per fraction and the size of the target volume were highly significantly related to the occurrence of both early and late radiation reactions. Vaginal shortening is closely related to the dose per fraction, length of the reference isodose, and the applicator diameter. The shape of the vaginal applicator versus the isodoses and the importance of the source train geometry and relative activity for dose gradient inhomogeneities within the target volume are discussed. Cumulative radiation effect (CRE) and linear-quadratic (LQ) calculations have been performed and related to tissue reactions within the target volume and in the risk organs. An alpha-beta quotient of 8.8 for vaginal shrinkage effect and 2.0 for late rectal complications are suggested on the basis of calculations using a maximum likelihood method for quantal radiation data.

  5. Dose and dose rate effects of whole-body proton-irradiation on lymphocyte blastogenesis and hematological variables: part II

    NASA Technical Reports Server (NTRS)

    Pecaut, Michael J.; Gridley, Daila S.; Smith, Anna L.; Nelson, Gregory A.

    2002-01-01

    The goal of part II of this study was to evaluate functional characteristics of leukocytes and circulating blood cell parameters after whole-body proton irradiation at varying doses and at low- and high-dose-rates (LDR and HDR, respectively). C57BL/6 mice (n=51) were irradiated and euthanized at 4 days post-exposure for assay. Significant radiation dose- (but not dose-rate-) dependent decreases were observed in splenocyte responses to T and B cell mitogens when compared to sham-irradiated controls (P<0.001). Spontaneous blastogenesis, also significantly dose-dependent, was increased in both blood and spleen (P<0.001). Red blood cell counts, hemoglobin concentration, and hematocrit were decreased in a dose-dependent manner (P<0.05), whereas thrombocyte numbers were only slightly affected. Comparison of proton- and gamma-irradiated groups (both receiving 3 Gy at HDR) showed a higher level of spontaneous blastogenesis in blood leukocytes and a lower splenocyte response to concanavalin A following proton irradiation (P<0.05). There were no dose rate effects. Collectively, the data demonstrate that the measurements in blood and spleen were largely dependent upon the total dose of proton radiation and that an 80-fold difference in the dose rate was not a significant factor. A difference, however, was found between protons and gamma-rays in the degree of change induced in some of the measurements.

  6. Helium effects on microstructural change in RAFM steel under irradiation: Reaction rate theory modeling

    NASA Astrophysics Data System (ADS)

    Watanabe, Y.; Morishita, K.; Nakasuji, T.; Ando, M.; Tanigawa, H.

    2015-06-01

    Reaction rate theory analysis has been conducted to investigate helium effects on the formation kinetics of interstitial type dislocation loops (I-loops) and helium bubbles in reduced-activation-ferritic/martensitic steel during irradiation, by focusing on the nucleation and growth processes of the defect clusters. The rate theory model employs the size and chemical composition dependence of thermal dissociation of point defects from defect clusters. In the calculations, the temperature and the production rate of Frenkel pairs are fixed to be T = 723 K and PV = 10-6 dpa/s, respectively. And then, only the production rate of helium atoms was changed into the following three cases: PHe = 0, 10-7 and 10-5 appm He/s. The calculation results show that helium effect on I-loop formation quite differs from that on bubble formation. As to I-loops, the loop formation hardly depends on the existence of helium, where the number density of I-loops is almost the same for the three cases of PHe. This is because helium atoms trapped in vacancies are easily emitted into the matrix due to the recombination between the vacancies and SIAs, which induces no pronounced increase or decrease of vacancies and SIAs in the matrix, leading to no remarkable impact on the I-loop nucleation. On the other hand, the bubble formation depends much on the existence of helium, in which the number density of bubbles for PHe = 10-7 and 10-5 appm He/s is much higher than that for PHe = 0. This is because helium atoms trapped in a bubble increase the vacancy binding energy, and suppress the vacancy dissociation from the bubble, resulting in a promotion of the bubble nucleation. And then, the helium effect on the promotion of bubble nucleation is very strong, even the number of helium atoms in a bubble is not so large.

  7. Planetary quarantine in the solar system. Survival rates of some terrestrial organisms under simulated space conditions by proton irradiation

    NASA Astrophysics Data System (ADS)

    Koike, J.; Oshima, T.

    We have been studying the survival rates of some species of terrestrial unicellular and multicellular organism (viruses, bacteria, yeasts, fungi, algae, etc.) under simulated interstellar conditions, in connection with planetary quarantine. The interstellar environment in the solar system has been simulated by low temperature, high vacuum (77 K, 4 × 10 -8 torr), and proton irradiation from a Van de Graaff generator. After exposure to a barrage of protons corresponding to about 250 years of irradiation in solar space, tobacco mosaic virus, Bacillus subtilis spores, Staphylococcus aureus, Micrococcus flavus, Aspergillus niger spores, and Clostridium mangenoti spores showed survival rates of 82, 45, 74, 13, 28, and 25%, respectively.

  8. Planetary quarantine in the solar system. Survival rates of some terrestrial organisms under simulated space conditions by proton irradiation.

    PubMed

    Koike, J; Oshima, T

    1993-08-01

    We have been studying the survival rates of some species of terrestrial unicellular and multicellular organism (viruses, bacteria, yeasts, fungi, algae, etc.) under simulated interstellar conditions, in connection with planetary quarantine. The interstellar environment in the solar system has been simulated by low temperature, high vacuum (77 K, 4 x 10(-8) torr), and proton irradiation from a Van de Graaff generator. After exposure to a barrage of protons corresponding to about 250 years of irradiation in solar space, tobacco mosaic virus, Bacillus subtilis spores, Staphylococcus aureus, Micrococcus flavus, Aspergillus niger spores, and Clostridium mangenoti spores showed survival rates of 82, 45, 74, 13, 28, and 25%, respectively. PMID:11541644

  9. Development and characterization of a novel variable low-dose rate irradiator for in vivo mouse studies

    PubMed Central

    Olipitz, Werner; Hembrador, Sheena; Davidson, Matthew; Yanch, Jacquelyn C.; Engelward, Bevin P.

    2011-01-01

    Radiation exposure of humans generally results in low doses delivered at low dose-rate. Our limited knowledge of the biological effects of low dose radiation is mainly based on data from the atomic bomb long-term survivor study (LSS) cohort. However, the total doses and dose-rates in the LSS cohort are still higher than most environmental and occupational exposures in humans. Importantly, the dose-rate is a critical determinant of health risks stemming from radiation exposure. Understanding the shape of the dose-rate response curve for different biological outcomes is thus crucial for projecting the biological hazard from radiation in different environmental and man-made conditions. A significant barrier to performing low dose-rate studies is the difficulty in creating radiation source configurations compatible with long-term cellular or animal experiments. In this study the design and characterization of a large area, 125I-based irradiator is described. The irradiator allows continuous long-term exposure of mice at variable dose-rates and can be sited in standard animal care facilities. The dose-rate is determined by the level of 125I activity added to a large NaOH filled, rectangular phantom. The desired dose rate is maintained at essentially constant levels by weekly additions of 125I to compensate for decay. Dosimetry results for long-term animal irradiation at targeted dose rates of 0.00021 and 0.0021 cGy min−1 are presented. PMID:20386202

  10. Effects of gamma irradiation on onion sprouting. I.--Influence of dose rate and post-harvest period of treatment.

    PubMed

    Farooqi, W A; Donini, B

    1976-01-01

    Onions of "Dorata di Parma" variety were exposed to 10 Krads of Co60 gamma irradiation in 5, 10, 20, 40, and 80 minutes in December, 1975 and then stored in the cold storage (10 +/- 1 degree C; R.H. 65-70%) and at the room temperature (15-20 degrees C; R.H. 40-70%) for 3 months, to study the influence of dose-rate and post-harvest period of treatment. Average number of buds sprouted in each onion bulb under cold storage condition ranged from 2-3, while this number was found to increase to 3-4 under ambient storage conditions. Although no effect of either irradiation or dose rate was observed when onions were irradiated after the break of their dormancy, however, a significant slowing down effect of irradiation could be observed as far as the rate of growth of sprouts was concerned. Weight loss was also reduced significantly in the irradiated onions as compared with controls. PMID:1037423

  11. Dose and dose rate effects of whole-body proton irradiation on leukocyte populations and lymphoid organs: part I

    NASA Technical Reports Server (NTRS)

    Gridley, Daila S.; Pecaut, Michael J.; Dutta-Roy, Radha; Nelson, Gregory A.

    2002-01-01

    The goal of part I of this study was to evaluate the effects of whole-body proton irradiation on lymphoid organs and specific leukocyte populations. C57BL/6 mice were exposed to the entry region of the proton Bragg curve to total doses of 0.5 gray (Gy), 1.5 Gy, and 3.0 Gy, each delivered at a low dose rate (LDR) of 1 cGy/min and high dose rate (HDR) of 80 cGy/min. Non-irradiated and 3 Gy HDR gamma-irradiated groups were included as controls. At 4 days post-irradiation, highly significant radiation dose-dependent reductions were observed in the mass of both lymphoid organs and the numbers of leukocytes and T (CD3(+)), T helper (CD3(+)/CD4(+)), T cytotoxic (CD3(+)/CD8(+)), and B (CD19(+)) cells in both blood and spleen. A less pronounced dose effect was noted for natural killer (NK1.1(+) NK) cells in spleen. Monocyte, but not granulocyte, counts in blood were highly dose-dependent. The numbers for each population generally tended to be lower with HDR than with LDR radiation; a significant dose rate effect was found in the percentages of T and B cells, monocytes, and granulocytes and in CD4(+):CD8(+) ratios. These data indicate that mononuclear cell response to the entry region of the proton Bragg curve is highly dependent upon the total dose and that dose rate effects are evident with some cell types. Results from gamma- and proton-irradiated groups (both at 3 Gy HDR) were similar, although proton-irradiation gave consistently lower values in some measurements.

  12. An ecologic study of cancer mortality rates in Spain with respect to indices of solar UVB irradiance and smoking.

    PubMed

    Grant, William B

    2007-03-01

    There is increasing evidence that vitamin D reduces the risk of many types of cancer. Geographic variations in cancer mortality rates in Spain are apparently linked to variations in solar ultraviolet (UV) irradiances and other factors. Cancer mortality rates for 48 continental Spanish provinces for 1978-1992 were used in linear regression analyses with respect to mortality rates for latitude (an index of solar UVB levels), skin cancer (an index of high cumulative UVB irradiance), melanoma (an index related to solar UV irradiance and several other factors) and lung cancer (an index of cumulative effects of smoking). The 9 cancers with mortality rates significantly correlated with latitude for 1 or both sexes were brain, gastric, melanoma, nonmelanoma skin cancer (NMSC), non-Hodgkin's lymphoma (NHL), pancreatic, pleural, rectal and thyroid cancer. Inverse correlations with latitude were found for laryngeal, lung and uterine corpus cancer. The 17 cancers inversely correlated with NMSC are bladder, brain, breast, colon, esophageal, gallbladder, Hodgkin's lymphoma, lung, melanoma, multiple myeloma, NHL, ovarian, pancreatic, pleural, rectal, thyroid and uterine corpus cancer. The 16 correlated with melanoma are bladder, brain, breast, colon, gallbladder, leukemia, lung, multiple myeloma, NHL, ovarian, pancreatic, pleural, prostate, rectal, renal and uterine corpus cancer. The results for lung cancer were in accordance with the literature. These results provide more support for the UVB/vitamin D/cancer hypothesis and indicate a new way to investigate the role of solar UV irradiance on cancer risk. They also provide more evidence that melanoma and NMSC have different etiologies. PMID:17149699

  13. The effect of continuous low dose-rate gamma irradiation on cell population kinetics of lymphoid tissue

    NASA Technical Reports Server (NTRS)

    Foster, B. R.

    1973-01-01

    The problem studied involved cell proliferation in mice thymus undergoing irradiation at a dose rate of 10 roetgens/day for 105 days. Specifically, the aim was to determine wheather or not a steady state of cell population can be established for the indicated period of time and what compensatory mechanisms of cell population are involved.

  14. Continuous Exposure to Low-Dose-Rate Gamma Irradiation Reduces Airway Inflammation in Ovalbumin-Induced Asthma.

    PubMed

    Kim, Joong Sun; Son, Yeonghoon; Bae, Min Ji; Lee, Seung Sook; Park, Sun Hoo; Lee, Hae June; Lee, Soong In; Lee, Chang Geun; Kim, Sung Dae; Jo, Wol Soon; Kim, Sung Ho; Shin, In Sik

    2015-01-01

    Although safe doses of radiation have been determined, concerns about the harmful effects of low-dose radiation persist. In particular, to date, few studies have investigated the correlation between low-dose radiation and disease development. Asthma is a common chronic inflammatory airway disease that is recognized as a major public health problem. In this study, we evaluated the effects of low-dose-rate chronic irradiation on allergic asthma in a murine model. Mice were sensitized and airway-challenged with ovalbumin (OVA) and were exposed to continuous low-dose-rate irradiation (0.554 or 1.818 mGy/h) for 24 days after initial sensitization. The effects of chronic radiation on proinflammatory cytokines and the activity of matrix metalloproteinase-9 (MMP-9) were investigated. Exposure to low-dose-rate chronic irradiation significantly decreased the number of inflammatory cells, methylcholine responsiveness (PenH value), and the levels of OVA-specific immunoglobulin E, interleukin (IL)-4, and IL-5. Furthermore, airway inflammation and the mucus production in lung tissue were attenuated and elevated MMP-9 expression and activity induced by OVA challenge were significantly suppressed. These results indicate that low-dose-rate chronic irradiation suppresses allergic asthma induced by OVA challenge and does not exert any adverse effects on asthma development. Our findings can potentially provide toxicological guidance for the safe use of radiation and relieve the general anxiety about exposure to low-dose radiation. PMID:26588845

  15. Continuous Exposure to Low-Dose-Rate Gamma Irradiation Reduces Airway Inflammation in Ovalbumin-Induced Asthma

    PubMed Central

    Kim, Joong Sun; Son, Yeonghoon; Bae, Min Ji; Lee, Seung Sook; Park, Sun Hoo; Lee, Hae June; Lee, Soong In; Lee, Chang Geun; Kim, Sung Dae; Jo, Wol Soon; Kim, Sung Ho; Shin, In Sik

    2015-01-01

    Although safe doses of radiation have been determined, concerns about the harmful effects of low-dose radiation persist. In particular, to date, few studies have investigated the correlation between low-dose radiation and disease development. Asthma is a common chronic inflammatory airway disease that is recognized as a major public health problem. In this study, we evaluated the effects of low-dose-rate chronic irradiation on allergic asthma in a murine model. Mice were sensitized and airway-challenged with ovalbumin (OVA) and were exposed to continuous low-dose-rate irradiation (0.554 or 1.818 mGy/h) for 24 days after initial sensitization. The effects of chronic radiation on proinflammatory cytokines and the activity of matrix metalloproteinase-9 (MMP-9) were investigated. Exposure to low-dose-rate chronic irradiation significantly decreased the number of inflammatory cells, methylcholine responsiveness (PenH value), and the levels of OVA-specific immunoglobulin E, interleukin (IL)-4, and IL-5. Furthermore, airway inflammation and the mucus production in lung tissue were attenuated and elevated MMP-9 expression and activity induced by OVA challenge were significantly suppressed. These results indicate that low-dose-rate chronic irradiation suppresses allergic asthma induced by OVA challenge and does not exert any adverse effects on asthma development. Our findings can potentially provide toxicological guidance for the safe use of radiation and relieve the general anxiety about exposure to low-dose radiation. PMID:26588845

  16. Electron-ion collision rates in noble gas clusters irradiated by femtosecond laser pulse

    NASA Astrophysics Data System (ADS)

    Dey, R.; Roy, A. C.

    2012-05-01

    We report a theoretical analysis of electron-ion collision rates in xenon gas clusters irradiated by femtosecond laser pulses. The present analysis is based on the eikonal approximation (EA), the first Born approximation (FBA) and the classical (CL) methods. The calculations are performed using the plasma-screened Rogers potential introduced by Moll et al. [J. Phys. B. 43, 135103 (2010)] as well as the Debye potential for a wide range of experimental parameters. We find that the magnitudes of electron-ion collision frequency obtained in the EA do not fall as rapidly with the kinetic energy of electrons as in the FBA and CL methods for higher charge states of xenon ion (Xe8+ and Xe14+). Furthermore, EA shows that the effect of the inner structure of ion is most dominant for the lowest charge state of xenon ion (Xe1+). In the case of the present effective potential, FBA overestimates the CL results for all three different charge states of xenon, whereas for the Debye potential, both the FBA and CL methods predict collision frequencies which are nearly close to each other.

  17. Growth rates of North Sea macroalgae in relation to temperature, irradiance and photoperiod

    NASA Astrophysics Data System (ADS)

    Fortes, M. D.; Lüning, K.

    1980-03-01

    Three eulittoral algae (Ulva lactuca, Porphyra umbilicalis, Chondrus crispus) and one sublittoral alga (Laminaria saccharina) from Helgoland (North Sea) were cultivated in a flow-through system at different temperatures, irradiances and daylengths. In regard to temperature there was a broad optimum at 10 15° C, except in P. umbilicalis, which grew fastest at 10 °C. A growth peak at this temperature was also found in four of 17 other North Sea macroalgae, for which the growth/temperature response was studied, whereas 13 of these species exhibited a growth optimum at 15 °C, or a broad optimum at 10 15 °C. Growth was light-saturated in U. lactuca, L. saccharina and C. crispus at photon flux densities above 70 µE m-2s-1, but in P. umbilicalis above 30 µE m-2s-1. Growth rate did not decrease notably in the eulittoral species after one week in relatively strong light (250 µE m-2s-1), but by about 50 % in the case of the sublittoral L. saccharina, as compared with growth under weak light conditions (30 µE m-2s-1). In contrast, chlorophyll content decreased in the sublittoral as well as in the eulittoral species, and the greatest change in pigment content occurred in the range 30 70 µE m-2s-1. Growth rate increased continuously up to photoperiods of 24 h light per day in L. saccharina and C. crispus, whereas daylength saturation occurred at photoperiods of more than 16 h light per day in U. lactuca and P. umbilicalis.

  18. Analysis of the dose rate produced by control rods discharged from a BWR into the irradiated fuel pool.

    PubMed

    Ródenas, J; Gallardo, S; Abarca, A; Juan, V

    2010-01-01

    BWR control rods become activated by neutron reactions into the reactor. Therefore, when they are withdrawn from the reactor, they must be stored into the storage pool for irradiated fuel at a certain depth under water. Dose rates on the pool surface and the area surrounding the pool should be lower than limits for workers. The MCNP code based on the Monte Carlo method has been applied to model this situation and to calculate dose rates at points of interest. PMID:19836252

  19. Soluble carbohydrate allocation to roots, photosynthetic rate of leaves, and nitrate assimilation as affected by nitrogen stress and irradiance

    NASA Technical Reports Server (NTRS)

    Henry, L. T.; Raper, C. D. Jr

    1991-01-01

    Upon resupply of exogenous nitrogen to nitrogen-stressed plants, uptake rate of nitrogen is enhanced relative to nonstressed plants. Absorption of nitrogen presumably is dependent on availability of carbohydrates in the roots. A buildup in soluble carbohydrates thus should occur in roots of nitrogen-stressed plants, and upon resupply of exogenous nitrogen the increased uptake rate should be accompanied by a rapid decline in carbohydrates to prestress levels. To evaluate this relationship, three sets of tobacco plants growing in a complete hydroponic solution containing 1.0 mM NO3- were either continued in the complete solution for 21 d, transferred to a minus-nitrogen solution for 21 d, or transferred to a minus-nitrogen solution for 8-9 d and then returned to the 1.0 mM NO3- solution. These nitrogen treatments were imposed upon plants growing at photosynthetic photon flux densities of 700 and 350 micromoles m-2 s-1. Soluble carbohydrate levels in roots increased during onset of nitrogen stress to levels that were fourfold greater than in roots of non-stressed plants. Following resupply of external nitrogen, a rapid resumption of nitrogen uptake was accompanied by a decline in soluble carbohydrates in roots to levels characteristic of nonstressed plants. This pattern of soluble carbohydrate levels in roots during onset of and recovery from nitrogen stress occurred at both irradiance levels. The response of net photosynthetic rate to nitrogen stress could be expressed as a nonlinear function of concentration of reduced nitrogen in leaves. The net photosynthetic rate at a given concentration of reduced nitrogen, however, averaged 10% less at the lower than at the higher irradiance. The decline in net photosynthetic rate per unit of reduced nitrogen in leaves at the lower irradiance was accompanied by an increase in the nitrate fraction of total nitrogen in leaves from 20% at the higher irradiance to 38% at the lower irradiance.

  20. Laser-based irradiation apparatus and methods for monitoring the dose-rate response of semiconductor devices

    DOEpatents

    Horn, Kevin M.

    2006-03-28

    A scanned, pulsed, focused laser irradiation apparatus can measure and image the photocurrent collection resulting from a dose-rate equivalent exposure to infrared laser light across an entire silicon die. Comparisons of dose-rate response images or time-delay images from before, during, and after accelerated aging of a device, or from periodic sampling of devices from fielded operational systems allows precise identification of those specific age-affected circuit structures within a device that merit further quantitative analysis with targeted materials or electrical testing techniques. Another embodiment of the invention comprises a broad-beam, dose rate-equivalent exposure apparatus. The broad-beam laser irradiation apparatus can determine if aging has affected the device's overall functionality. This embodiment can be combined with the synchronized introduction of external electrical transients into a device under test to simulate the electrical effects of the surrounding circuitry's response to a radiation exposure.

  1. Differential expression of immune-associated cancer regulatory genes in low- versus high-dose-rate irradiated AKR/J mice.

    PubMed

    Shin, Suk Chul; Lee, Kyung-Mi; Kang, Yu Mi; Kim, Kwanghee; Lim, Seon Ah; Yang, Kwang Hee; Kim, Ji Young; Nam, Seon Young; Kim, Hee Sun

    2011-06-01

    AKR/J mice carrying leukemia viral inserts develop thymic lymphoma. Recently, we demonstrated that the incidence of thymic lymphoma was decreased when these mice were raised in a low-dose-rate γ-irradiation facility. In contrast, mice irradiated at a high-dose rate developed severe thymic lymphoma and died much earlier. To understand the genetic changes occurred by low- versus high-dose-rate γ-irradiation whole genome microarray was performed. Both groups of mice demonstrated up-regulation of Ifng, Igbp1, and IL7 in their thymuses, however, mice exposed to high-dose-rate γ-irradiation exhibited marked down-regulation of Sp3, Il15, Traf6, IL2ra, Pik3r1, and Hells. In contrast, low-dose-rate irradiated mice demonstrated up-regulation of Il15 and Jag2. These gene expression profiles imply the impaired immune signaling pathways by high-dose-rate γ-irradiation while the facilitation of anti-tumor immune responses by low-dose-rate γ-irradiation. Therefore, our data delineate common and distinct immune-associated pathways downstream of low- versus high-dose-rate irradiation in the process of cancer progression in AKR/J mice. PMID:21266193

  2. Effects of dpa rate on swelling in neutron-irradiated Fe-Cr and Fe-Cr-Mo alloys

    NASA Astrophysics Data System (ADS)

    Okita, T.; Sekimura, N.; Garner, F. A.

    2011-10-01

    Data are presented on the void swelling of three model Fe-Cr ferritic alloys following irradiation in TEM packets in FFTF-MOTA over the range 373-600 °C and a wide range of dpa rates. It is shown that raising the chromium level decreases the steady-state swelling rate at ˜420 °C. Addition of Mo to the Fe-12Cr alloy does not change the swelling rate significantly but does lead to an apparent swelling of ˜3% that arises from the radiation-accelerated formation of Chi phase. Swelling tends to decrease with increasing irradiation temperature for all three alloys. It is shown that the sensitivity of swelling to dpa rate expresses itself not at the various packet positions in FFTF, each with their characteristic nominal dpa rates, but also in response to variations in dpa rate along the length of the packet containing the specimens. The latter introduces second-order uncertainties in determination of the dpa levels and dpa rates, but these are not sufficient to obscure the major conclusion concerning dpa rate and composition.

  3. Low Cloud Cover-Adjusted Ultraviolet B Irradiance Is Associated with High Incidence Rates of Leukemia: Study of 172 Countries

    PubMed Central

    2015-01-01

    There are 52,380 cases of leukemia and 24,090 deaths from it in the US annually. Its causes are unknown and no preventive strategies have been implemented. We hypothesized that leukemia is due mainly to vitamin D deficiency, which is due mainly to low solar ultraviolet B (UVB) irradiance. To test this hypothesis, we estimated age-standardized cloud-cover-adjusted winter UVB irradiance using cloud cover data from the International Satellite Cloud Climatology Project, latitudes of population centroids, and standard astronomical calculations. Incidence rates for 172 countries, available from the International Agency for Cancer Research, were plotted according to cloud-adjusted UVB irradiance. We used multiple regression to account for national differences in elevation and average life expectancy. Leukemia incidence rates were inversely associated with cloud-adjusted UVB irradiance in males (p ≤ 0.01) and females (p ≤ 0.01) in both hemispheres. There were few departures from the trend line, which was parabolic when plotted with the equator at the center of the display, northern hemisphere countries on the right side and southern hemisphere countries on the left. The bivariate association displayed by the polynomial trend line indicated that populations at higher latitudes had at least two times the risk of leukemia compared to equatorial populations. The association persisted in males (p ≤ 0.05) and females (p ≤ 0.01) after controlling for elevation and life expectancy. Incidence rates of leukemia were inversely associated with solar UVB irradiance. It is plausible that the association is due to vitamin D deficiency. This would be consistent with laboratory studies and a previous epidemiological study. Consideration should be given to prudent use of vitamin D for prevention of leukemia. PMID:26637119

  4. Low Cloud Cover-Adjusted Ultraviolet B Irradiance Is Associated with High Incidence Rates of Leukemia: Study of 172 Countries.

    PubMed

    Cuomo, Raphael E; Garland, Cedric F; Gorham, Edward D; Mohr, Sharif B

    2015-01-01

    There are 52,380 cases of leukemia and 24,090 deaths from it in the US annually. Its causes are unknown and no preventive strategies have been implemented. We hypothesized that leukemia is due mainly to vitamin D deficiency, which is due mainly to low solar ultraviolet B (UVB) irradiance. To test this hypothesis, we estimated age-standardized cloud-cover-adjusted winter UVB irradiance using cloud cover data from the International Satellite Cloud Climatology Project, latitudes of population centroids, and standard astronomical calculations. Incidence rates for 172 countries, available from the International Agency for Cancer Research, were plotted according to cloud-adjusted UVB irradiance. We used multiple regression to account for national differences in elevation and average life expectancy. Leukemia incidence rates were inversely associated with cloud-adjusted UVB irradiance in males (p ≤ 0.01) and females (p ≤ 0.01) in both hemispheres. There were few departures from the trend line, which was parabolic when plotted with the equator at the center of the display, northern hemisphere countries on the right side and southern hemisphere countries on the left. The bivariate association displayed by the polynomial trend line indicated that populations at higher latitudes had at least two times the risk of leukemia compared to equatorial populations. The association persisted in males (p ≤ 0.05) and females (p ≤ 0.01) after controlling for elevation and life expectancy. Incidence rates of leukemia were inversely associated with solar UVB irradiance. It is plausible that the association is due to vitamin D deficiency. This would be consistent with laboratory studies and a previous epidemiological study. Consideration should be given to prudent use of vitamin D for prevention of leukemia. PMID:26637119

  5. Formation rates of complex organics in UV irradiated CH_3OH-rich ices. I. Experiments

    NASA Astrophysics Data System (ADS)

    Öberg, K. I.; Garrod, R. T.; van Dishoeck, E. F.; Linnartz, H.

    2009-09-01

    Context: Gas-phase complex organic molecules are commonly detected in the warm inner regions of protostellar envelopes, so-called hot cores. Recent models show that photochemistry in ices followed by desorption may explain the observed abundances. There is, however, a general lack of quantitative data on UV-induced complex chemistry in ices. Aims: This study aims to experimentally quantify the UV-induced production rates of complex organics in CH3OH-rich ices under a variety of astrophysically relevant conditions. Methods: The ices are irradiated with a broad-band UV hydrogen microwave-discharge lamp under ultra-high vacuum conditions, at 20-70 K, and then heated to 200 K. The reaction products are identified by reflection-absorption infrared spectroscopy (RAIRS) and temperature programmed desorption (TPD), through comparison with RAIRS and TPD curves of pure complex species, and through the observed effects of isotopic substitution and enhancement of specific functional groups, such as CH3, in the ice. Results: Complex organics are readily formed in all experiments, both during irradiation and during the slow warm-up of the ices after the UV lamp is turned off. The relative abundances of photoproducts depend on the UV fluence, the ice temperature, and whether pure CH3OH ice or CH3OH:CH4/CO ice mixtures are used. C2H6, CH3CHO, CH3CH2OH, CH3OCH3, HCOOCH3, HOCH2CHO and (CH2OH)2 are all detected in at least one experiment. Varying the ice thickness and the UV flux does not affect the chemistry. The derived product-formation yields and their dependences on different experimental parameters, such as the initial ice composition, are used to estimate the CH3OH photodissociation branching ratios in ice and the relative diffusion barriers of the formed radicals. At 20 K, the pure CH3OH photodesorption yield is 2.1(±1.0)×10-3 per incident UV photon, the photo-destruction cross section 2.6(±0.9)×10-18 cm^2. Conclusions: Photochemistry in CH3OH ices is efficient enough to

  6. Radiation-induced failures and degradation of wireless real-time dosimeter under high-dose-rate irradiation

    NASA Astrophysics Data System (ADS)

    Tsuchiya, K.; Kuroki, K.; Akiba, N.; Kurosawa, K.; Matsumoto, T.; Nishiyama, J.; Harano, H.

    2010-04-01

    Radiation-induced malfunction and degradation of electronic modules in certain operating conditions are described in this report. The cumulative radiation effects on Atmel AVR microcontrollers, and 2.4 GHz and 303 MHz wireless network devices were evaluated under gamma ray irradiation with dose rates of 100, 10 and 3 Gy/h. The radiation-induced malfunctions occurred at doses of 510+/-22 Gy for AVR microcontrollers, and 484+/-111 and 429+/-14 Gy for 2.4 GHz and 303 MHz wireless network devices, respectively, under a 100 Gy/h equivalent dose rate. The degradation of microcontrollers occurred for total ionizing doses between 400 and 600 Gy under X-ray irradiation. In addition, we evaluated the reliability of neutron dosimeters using a standard neutron field. One of the neutron dosimeters gave a reading that was half of the standard field value.

  7. Radiobiological basis of total body irradiation with different dose rate and fractionation: repair capacity of hemopoietic cells

    SciTech Connect

    Song, C.W.; Kim, T.H.; Khan, F.M.; Kersey, J.H.; Levitt, S.H.

    1981-12-01

    Total body irradiation (TBI) followed by bone marrow transplantation is being used in the treatment of malignant or non-malignant hemopoietic disorders. It has been believed that the ability of hemopoietic cells to repair sublethal radiation damage is negligible. Therefore, several schools of investigators suggested that TBI in a single exposure at extremely low dose rate (5 rad/min) over several hours, or in several fractions in 2-3 days, should yield a higher therapeutic gain, as compared with a single exposure at a high dose rate (26 rad/min). We reviewed the existing data in the literature, in particular, the response of hemopoietic cells to fractionated doses of irradiation and found that the repair capacity of both malignant and non-malignant hemopoietic cells might be greater than has been thought. It is concluded that we should not underestimate the ability of hemopoietic cells to repair sublethal radiation damage in using TBI.

  8. Radiobiological basis of total body irradiation with different dose rate and fractionation: repair capacity of hemopoietic cells

    SciTech Connect

    Song, C.W.; Kim, T.H.; Khan, F.M.; Kersey, J.H.; Levitt, S.H.

    1981-12-01

    Total body irradiation (TBI) followed by bone marrow transplantation is being used in the treatment of malignant or non-malignant hemopoietic disorders. It has been believed that the ability of hemopoietic cells to repair sublethal radiation damage is negligible. Therefore, several schools of investigators suggested that TBI in a single exposure at extremely low dose rate (5 rad/min) over several hours, or in several fractions in 2-3 days, should yield a higher therapeutic gain, as compared with a single exposure at a high dose rate (25 rad/min). We reviewed the existing data in the literature, in particular, the response of hemopoietic cells to fractionated doses of irradiation and found that the repair capacity of both malignant and non-malignant hemopoietic cells might be greater than has been thought. It is concluded that we should not underestimate the ability of hemopoietic cells to repair sublethal radiation damage in using TBI.

  9. Effect of electron irradiation on carrier removal rate in silicon and silicon carbide with 4H modification

    SciTech Connect

    Kozlovskii, V. V.; Emtsev, V. V.; Emtsev, K. V.; Strokan, N. B.; Ivanov, A. M.; Lomasov, V. N.; Oganesyan, G. A.; Lebedev, A. A.

    2008-02-15

    Comparative study of the effect of successive (up to fluences of 3 Multiplication-Sign 10{sup 16} cm{sup -2}) irradiation with 900 keV electrons of samples made of FZ-Si and 4H-SiC (CVD) has been performed for the first time. Measurements on initial and irradiated samples were made using the van der Pauw method for silicon and the capacitance-voltage technique at a frequency of 1 kHz for silicon carbide. In addition, the spectrum of the defect levels introduced was monitored by the DLTS method for SiC. The carrier removal and defect introduction rates were determined for the two materials. It was found that the rates of defect introduction into FZ-Si and 4 H-SiC (CVD) are close to eachy other ({approx}0.1 cm{sup -1}), which is largely due to the almost identical threshold energies of defect generation.

  10. Effect of electron irradiation on carrier removal rate in silicon and silicon carbide with 4H modification

    SciTech Connect

    Kozlovskii, V. V.; Emtsev, V. V. Emtsev, K. V.; Strokan, N. B.; Ivanov, A. M.; Lomasov, V. N.; Oganesyan, G. A.; Lebedev, A. A.

    2008-02-15

    Comparative study of the effect of successive (up to fluences of 3 x 10{sup 16} cm{sup -2}) irradiation with 900 keV electrons of samples made of FZ-Si and 4H-SiC (CVD) has been performed for the first time. Measurements on initial and irradiated samples were made using the van der Pauw method for silicon and the capacitance-voltage technique at a frequency of 1 kHz for silicon carbide. In addition, the spectrum of the defect levels introduced was monitored by the DLTS method for SiC. The carrier removal and defect introduction rates were determined for the two materials. It was found that the rates of defect introduction into FZ-Si and 4 H-SiC (CVD) are close to eachy other ({approx}0.1 cm{sup -1}), which is largely due to the almost identical threshold energies of defect generation.

  11. Strain rate dependence of the tensile properties of V-(4--5%)Cr-(4--5%)Ti irradiated in EBR-II and HFBR

    SciTech Connect

    Zinkle, S.J.; Snead, L.L.; Robertson, J.P.; Rowcliffe, A.F.

    1998-03-01

    Elevated temperature tensile tests performed on V-(405)Cr-(4-5)Ti indicate that the yield stress increases with increasing strain rate for irradiation and test temperatures near 200 C, and decreases with increasing strain rate for irradiation and test temperatures near 400 C. This observation is in qualitative agreement with the temperature-dependent strain rate effects observed on unirradiated specimens, and implies that some interstitial solute remains free to migrate in irradiated specimens. Additional strain rate data at different temperatures are needed.

  12. Repair rates of DNA double-strand breaks under different doses of proton and γ-ray irradiation

    NASA Astrophysics Data System (ADS)

    Wu, Jingwen; Fu, Qibin; Quan, Yi; Wang, Weikang; Mei, Tao; Li, Jia; Yang, Gen; Ren, Xiaotang; Xue, Jianming; Wang, Yugang

    2012-04-01

    It is known that DNA double-strand breaks (DSBs), which can be induced by a variety of treatments including ionizing radiation (IR), can cause most deleterious consequences among all kinds of DNA lesions. However, it is still under debate about whether DSBs repair is equally efficient after low and high-LET radiation, especially the basic biological responses after exposure to high-LET particles. In present study, synchronous fibroblast normal Human lung fibroblast (NHLF) cells were irradiated with graded doses of proton and γ-ray. Then γ-H2AX foci assay was used to monitor DSBs induction and repair at 0.5, 1, 2, 4, and 18 h post irradiation. The results showed that the γ-ray irradiation could produce more γ-H2AX foci than proton irradiation at the same dose. However, compared to low LET radiation with γ-ray, the results also showed a much slower DSBs repair rate after high LET radiation with protons, suggesting that the cellular ability to eliminate DSBs after low and high-LET ionizing radiation is quite different.

  13. Dose and dose rate effects of whole-body gamma-irradiation: II. Hematological variables and cytokines.

    PubMed

    Gridley, D S; Pecaut, M J; Miller, G M; Moyers, M F; Nelson, G A

    2001-01-01

    The goal of part II of this study was to evaluate the effects of gamma-radiation on circulating blood cells, functional characteristics of splenocytes, and cytokine expression after whole-body irradiation at varying total doses and at low- and high-dose-rates (LDR, HDR). Young adult C57BL/6 mice (n = 75) were irradiated with either 1 cGy/min or 80 cGy/min photons from a 60Co source to cumulative doses of 0.5, 1.5, and 3.0 Gy. The animals were euthanized at 4 days post-exposure for in vitro assays. Significant dose- (but not dose-rate-) dependent decreases were observed in erythrocyte and blood leukocyte counts, hemoglobin, hematocrit, lipopolysaccharide (LPS)-induced 3H-thymidine incorporation, and interleukin-2 (IL-2) secretion by activated spleen cells when compared to sham-irradiated controls (p < 0.05). Basal proliferation of leukocytes in the blood and spleen increased significantly with increasing dose (p < 0.05). Significant dose rate effects were observed only in thrombocyte counts. Plasma levels of transforming growth factor-beta 1 (TGF-beta 1) and splenocyte secretion of tumor necrosis factor-alpha (TNF-alpha) were not affected by either the dose or dose rate of radiation. The data demonstrate that the responses of blood and spleen were largely dependent upon the total dose of radiation employed and that an 80-fold difference in the dose rate was not a significant factor in the great majority of measurements. PMID:11491015

  14. Dose and dose rate effects of whole-body gamma-irradiation: II. Hematological variables and cytokines

    NASA Technical Reports Server (NTRS)

    Gridley, D. S.; Pecaut, M. J.; Miller, G. M.; Moyers, M. F.; Nelson, G. A.

    2001-01-01

    The goal of part II of this study was to evaluate the effects of gamma-radiation on circulating blood cells, functional characteristics of splenocytes, and cytokine expression after whole-body irradiation at varying total doses and at low- and high-dose-rates (LDR, HDR). Young adult C57BL/6 mice (n = 75) were irradiated with either 1 cGy/min or 80 cGy/min photons from a 60Co source to cumulative doses of 0.5, 1.5, and 3.0 Gy. The animals were euthanized at 4 days post-exposure for in vitro assays. Significant dose- (but not dose-rate-) dependent decreases were observed in erythrocyte and blood leukocyte counts, hemoglobin, hematocrit, lipopolysaccharide (LPS)-induced 3H-thymidine incorporation, and interleukin-2 (IL-2) secretion by activated spleen cells when compared to sham-irradiated controls (p < 0.05). Basal proliferation of leukocytes in the blood and spleen increased significantly with increasing dose (p < 0.05). Significant dose rate effects were observed only in thrombocyte counts. Plasma levels of transforming growth factor-beta 1 (TGF-beta 1) and splenocyte secretion of tumor necrosis factor-alpha (TNF-alpha) were not affected by either the dose or dose rate of radiation. The data demonstrate that the responses of blood and spleen were largely dependent upon the total dose of radiation employed and that an 80-fold difference in the dose rate was not a significant factor in the great majority of measurements.

  15. Study of variations in structural, optical parameters and bulk etch rate of CR-39 polymer due to electron irradiation

    NASA Astrophysics Data System (ADS)

    Sahoo, G. S.; Tripathy, S. P.; Joshi, D. S.; Bandyopadhyay, T.

    2016-07-01

    In this work, electron induced modifications on the bulk etch rate, structural and optical parameters of CR-39 polymer were studied using gravimetric, FTIR (Fourier Transform Infrared) and UV-vis (Ultraviolet-Visible) techniques, respectively. CR-39 samples were irradiated with 10 MeV electron beam for different durations to have the absorbed doses of 1, 10, 550, 5500, 16 500, and 55 000 kGy. From the FTIR analysis, the peak intensities at different bands were found to be changing with electron dose. A few peaks were observed to shift at high electron doses. From the UV-vis analysis, the optical band gaps for both direct and indirect transitions were found to be decreasing with the increase in electron dose whereas the opacity, number of carbon atoms in conjugation length, and the number of carbon atoms per cluster were found to be increasing. The bulk etch rate was observed to be increasing with the electron dose. The primary objective of this investigation was to study the response of CR-39 to high electron doses and to determine a suitable pre-irradiation condition. The results indicated that, the CR-39 pre-irradiated with electrons can have better sensitivity and thus can be potentially applied for neutron dosimetry.

  16. Laser-based irradiation apparatus and method to measure the functional dose-rate response of semiconductor devices

    DOEpatents

    Horn, Kevin M.

    2008-05-20

    A broad-beam laser irradiation apparatus can measure the parametric or functional response of a semiconductor device to exposure to dose-rate equivalent infrared laser light. Comparisons of dose-rate response from before, during, and after accelerated aging of a device, or from periodic sampling of devices from fielded operational systems can determine if aging has affected the device's overall functionality. The dependence of these changes on equivalent dose-rate pulse intensity and/or duration can be measured with the apparatus. The synchronized introduction of external electrical transients into the device under test can be used to simulate the electrical effects of the surrounding circuitry's response to a radiation exposure while exposing the device to dose-rate equivalent infrared laser light.

  17. The effect of heating rate on thermoluminescence of anion-defective alumina after high-dose irradiation

    NASA Astrophysics Data System (ADS)

    Nikiforov, S. V.; Kortov, V. S.; Makkambaev, B. A.; Aminov, T. A.

    2016-05-01

    The dependences of the light sum of peaks of thermoluminescence (TL) at 180 and 300°C on the rate of heating of single crystals of anion-defective alumina after high-dose irradiation are investigated. It is found that these dependences for the peak at 180°C are the same for all studied samples and match the known dependence measured after low-dose irradiation. The curves for the TL peak at 300°C vary significantly from one sample to another. The parameters of thermal TL quenching are calculated for both peaks using the Monte Carlo method. Practical suggestions regarding the use of the obtained results in high-dose dosimetry are provided.

  18. The effect of continuous low dose-rate gamma irradiation on cell population kinetics of lymphoid tissue

    NASA Technical Reports Server (NTRS)

    Foster, B. R.

    1974-01-01

    Cellular response and cell population kinetics were studied during lymphopoiesis in the thymus of the mouse under continuous gamma irradiation using autoradiographic techniques and specific labeling with tritiated thymidine. On the basis of tissue weights, it is concluded that the response of both the thymus and spleen to continuous low dose-rate irradiation is multiphasic. That is, alternating periods of steady state growth, followed by collapse, which in turn is followed by another period of homeostasis. Since there are two populations of lymphocytes - short lived and long-lived, it may be that different phases of steady state growth are mediated by different lymphocytes. The spleen is affected to a greater extent with shorter periods of steady-state growth than exhibited by the thymus.

  19. Proposal of an energy rating method fair to countries of lower irradiance resources

    NASA Astrophysics Data System (ADS)

    Araki, Kenji

    2012-10-01

    International standard must be fair among nations. Fairness means fair among manufactures, testers and users. Present typical approaches, based on linear approximation and sampling only "good climate", may be improved by assuring fairness among spectrum and irradiance conditions among nations. In unwanted area, low efficiency days are usually humid and white-sky days. The energy anticipation will be underestimated based on the measurement by manufacturers in unwanted countries. This is not fair among manufactures. If we only filter "good climate data", it may be helpful to users in good irradiance area. This filtering may be blind to the realistic conditions. This is not fair to users. The robust approach will be parabolic representation of "daily energy" based on more than 10 days data.

  20. Elevated mutation rates in the germ line of first- and second-generation offspring of irradiated male mice

    PubMed Central

    Barber, Ruth; Plumb, Mark A.; Boulton, Emma; Roux, Isabelle; Dubrova, Yuri E.

    2002-01-01

    Mutation rates at two expanded simple tandem repeat loci were studied in the germ line of first- and second-generation offspring of inbred male CBA/H, C57BL/6, and BALB/c mice exposed to either high linear energy transfer fission neutrons or low linear energy transfer x-rays. Paternal CBA/H exposure to either x-rays or fission neutrons resulted in increased mutation rates in the germ line of two subsequent generations. Comparable transgenerational effects were observed also in neutron-irradiated C57BL/6 and x-irradiated BALB/c mice. The levels of spontaneous mutation rates and radiation-induced transgenerational instability varied between strains (BALB/c>CBA/H>C57BL/6). Pre- and postmeiotic paternal exposure resulted in similar increases in mutation rate in the germ line of both generations of CBA/H mice, which together with our previous results suggests that radiation-induced expanded simple tandem repeat instability is manifested in diploid cells after fertilization. The remarkable finding that radiation-induced germ-line instability persists for at least two generations raises important issues of risk evaluation in humans. PMID:11997464

  1. Naphthalene degradation in seawater by UV irradiation: the effects of fluence rate, salinity, temperature and initial concentration.

    PubMed

    Jing, Liang; Chen, Bing; Zhang, Baiyu; Zheng, Jisi; Liu, Bo

    2014-04-15

    A large amount of oil pollution at sea is produced by the operational discharge of oily wastewater. The removal of polycyclic aromatic hydrocarbons (PAHs) from such sources using UV irradiation has become attractive, yet the photolysis mechanism in seawater has remained unclear. This study examines the photodegradation kinetics of naphthalene in natural seawater through a full factorial design of experiments (DOE). The effects of fluence rate, salinity, temperature and initial concentration are investigated. Results show that fluence rate, temperature and the interaction between temperature and initial concentration are the most influential factors. An increase in fluence rate can linearly promote the photodegradation process. Salinity increasingly impedes the removal of naphthalene because of the existence of free-radical scavengers and photon competitors. The results will help understand the photolysis mechanism of PAHs and develop more effective methods for treating oily seawater generated from offshore industries. PMID:24576392

  2. Enhancing the growth rate and astaxanthin yield of Haematococcus pluvialis by nuclear irradiation and high concentration of carbon dioxide stress.

    PubMed

    Cheng, Jun; Li, Ke; Yang, Zongbo; Zhou, Junhu; Cen, Kefa

    2016-03-01

    Unicellular green microalgae Haematococcus pluvialis was mutated with (60)Co-γ irradiation to promote growth rate and increase astaxanthin yield under high concentration of CO2 stress. The average specific growth rate of H. pluvialis mutated with 4000 Gy γ-ray irradiation was increased by 15% compared with the original strain with air aeration. The mutant grew best with 6% CO2 (the maximum specific growth rate was 0.60/d) when it was cultured with high concentrations of CO2 (2-10%). The peak biomass productivity (0.16 g/L/d) of the mutant cultured with 6% CO2 was 82% higher than that of the mutant with air. The astaxanthin yield and lipid content of the mutant induced with 6% CO2 and high light (108 μmol photons m(-2) s(-1)) increased to 46.0mg/L and 45.9%, which were 2.4 and 1.3 times higher than those of the wild-type strain, respectively. PMID:26773378

  3. Predicting Radiosensitivity with Gamma-H2AX Foci Assay after Single High-Dose-Rate and Pulsed Dose-Rate Ionizing Irradiation.

    PubMed

    van Oorschot, Bregje; Hovingh, Suzanne; Dekker, Annelot; Stalpers, Lukas J; Franken, Nicolaas A P

    2016-02-01

    Gamma-H2AX foci detection is the standard method to quantify DNA double-strand break (DSB) induction and repair. In this study, we investigated the induction and decay of γ-H2AX foci of different tumor cell lines and fibroblasts with known mutations in DNA damage repair genes, including ATM, LigIV, DNA-PKcs, Rad51 and Rad54. A radiation dose of 2.4 Gy was used for either an acute single high-dose-rate (sHDR) exposure or a pulsed dose-rate (pDR) exposure over 24 h. The number of γ-H2AX foci was determined at 30 min and 24 h after sHDR irradiation and directly after pDR irradiation. In a similar manner, γ-H2AX foci were also examined in lymphocytes of patients with differences in normal tissue toxicity after a total radiation dose of 1 Gy. In an initial count of the number of foci 30 min after sHDR irradiation, repair-proficient cell types could not be distinguished from repair-deficient cell types. However at 24 h postirradiation, while we observed a large decrease in foci numbers in NHEJ-proficient cells, the amount of γ-H2AX foci in cell types with mutated NHEJ repair remained at high levels. Except for IRS-1SF cells, HR-deficient cell types eventually did show a moderate decrease in foci number over time, albeit to a lesser extent than their corresponding parentals or repair-proficient control cells. In addition, analysis of γ-H2AX foci after sHDR exposure of patients with different sensitivity status clearly showed individual differences in radiation response. Radiosensitive patients could be distinguished from the more radioresistant patients with γ-H2AX foci decay ratios (initial number of foci divided by residual number of foci). Significantly higher decay ratios were observed in patients without toxicities, indicating more proficient repair compared to patients with radiation-induced side effects. After pDR irradiation, no consistent correlation could be found between foci number and radiosensitivity. In conclusion, γ-H2AX formation is a rapid and

  4. Modeling Low-Dose-Rate Effects in Irradiated Bipolar-Base Oxides

    SciTech Connect

    Cirba, C.R.; Fleetwood, D.M.; Graves, R.J.; Michez, A.; Milanowski, R.J.; Saigne, F.; Schrimpf, R.D.; Witczak, S.C.

    1998-10-26

    A physical model is developed to quantify the contribution of oxide-trapped charge to enhanced low-dose-rate gain degradation in bipolar junction transistors. Multiple-trapping simulations show that space charge limited transport is partially responsible for low-dose-rate enhancement. At low dose rates, more holes are trapped near the silicon-oxide interface than at high dose rates, resulting in larger midgap voltage shifts at lower dose rates. The additional trapped charge near the interface may cause an exponential increase in excess base current, and a resultant decrease in current gain for some NPN bipolar technologies.

  5. Recovery capacity of glial progenitors after in vivo fission-neutron or X irradiation: age dependence, fractionation and low-dose-rate irradiations.

    PubMed

    Philippo, H; Winter, E A M; van der Kogel, A J; Huiskamp, R

    2005-06-01

    Previous experiments on the radiosensitivity of O-2A glial progenitors determined for single-dose fission-neutron and X irradiation showed log-linear survival curves, suggesting a lack of accumulation of recovery of sublethal damage. In the present study, we addressed this question and further characterized the radiobiological properties of these glial stem cells by investigating the recovery capacity of glial stem cells using either fractionated or protracted whole-body irradiation. Irradiations were performed on newborn, 2-week-old or 12-week-old rats. Fractionated irradiations (four fractions) were performed with 24-h intervals, followed by cell isolations 16- 24 h after the last irradiation. Single-dose irradiations were followed by cell isolation 16-24 h after irradiation or delayed cell isolation (4 days after irradiation) of the O-2A progenitor cells from either spinal cord (newborns) or optic nerve (2- and 12-week-old rats). Results for neonatal progenitor cell survival show effect ratios for both fractionated fission-neutron and X irradiation of the order of 1.8 when compared with single-dose irradiation. A similar ratio was found after single-dose irradiation combined with delayed plating. Comparable results were observed for juvenile and adult optic nerve progenitors, with effect ratios of the order of 1.2. The present investigation clearly shows that fractionated irradiation regimens using X rays or fission neutrons and CNS tissue from rats of various ages results in an increase in O-2A progenitor cell survival while repair is virtually absent. This recovery of the progenitor pool after irradiation can be observed at all ages but is greatest in the neonatal spinal cord and can probably be attributed to repopulation. PMID:15913395

  6. Corrosion product identification and relative rates of corrosion of candidate metals in an irradiated air-steam environment

    SciTech Connect

    Reed, D.T.; Swayambunathan, V.; Tani, B.S. ); Van Konynenburg, R.A. )

    1989-11-03

    Previously reported work by others indicates that dicopper trihydroxide nitrate, Cu{sub 2}NO{sub 3}(OH){sub 3}, forms on copper and copper alloys subjected to irradiated moist air near room temperature. We have performed experiments over a range of temperature and humidity, and have found that this species is formed at temperatures up to at least 150{degree}C if low to intermediate relative humidities are present. At 150{degree}C and 100% relative humidity, only Cu{sub 2}O and CuO were observed. The relative general corrosion rates of the copper materials tested in 1-month experiments at dose rates of 0.7 and 2.0 kGy/h were Cu > 70/30 Cu--Ni > Al-bronze. High-nickel alloy 825 showed no observable corrosion. 29 refs., 4 tabs.

  7. Dose and dose rate effects of whole-body gamma-irradiation: I. Lymphocytes and lymphoid organs

    NASA Technical Reports Server (NTRS)

    Pecaut, M. J.; Nelson, G. A.; Gridley, D. S.

    2001-01-01

    The major goal of part I of this study was to compare varying doses and dose rates of whole-body gamma-radiation on lymphoid cells and organs. C57BL/6 mice (n = 75) were exposed to 0, 0.5, 1.5, and 3.0 Gy gamma-rays (60Co) at 1 cGy/min (low-dose rate, LDR) and 80 cGy/min (high-dose rate, HDR) and euthanized 4 days later. A significant dose-dependent loss of spleen mass was observed with both LDR and HDR irradiation; for the thymus this was true only with HDR. Decreasing leukocyte and lymphocyte numbers occurred with increasing dose in blood and spleen at both dose rates. The numbers (not percentages) of CD3+ T lymphocytes decreased in the blood in a dose-dependent manner at both HDR and LDR. Splenic T cell counts decreased with dose only in HDR groups; percentages increased with dose at both dose rates. Dose-dependent decreases occurred in CD4+ T helper and CD8+ T cytotoxic cell counts at HDR and LDR. In the blood the percentages of CD4+ cells increased with increasing dose at both dose rates, whereas in the spleen the counts decreased only in the HDR groups. The percentages of the CD8+ population remained stable in both blood and spleen. CD19+ B cell counts and percentages in both compartments declined markedly with increasing HDR and LDR radiation. NK1.1+ natural killer cell numbers and proportions remained relatively stable. Overall, these data indicate that the observed changes were highly dependent on the dose, but not dose rate, and that cells in the spleen are more affected by dose rate than those in blood. The results also suggest that the response of lymphocytes in different body compartments may be variable.

  8. Radiation bronchitis and stenosis secondary to high dose rate endobronchial irradiation

    SciTech Connect

    Speiser, B.L. ); Spratling, L.

    1993-03-15

    The purpose of the study was to describe a new clinical entity observed in follow-up bronchoscopies in patients who were treated with high dose rate and medium dose rate remote afterloading brachytherapy of the tracheobronchial tree. Patients were treated by protocol with medium dose rate, 47 patients receiving 1000 cGy at a 5 mm depth times three fractions, high dose rate 144 patients receiving 1000 cGy at a 10 mm depth for three fractions and high dose rate 151 patients receiving cGy at a 10 mm depth for three fractions followed by bronchoscopy. Incidence of this entity was 9% for the first group, 12% for the second, and 13% for the third group. Reactions were grade 1 consisting of mild inflammatory response with a partial whitish circumferential membrane in an asymptomatic patient; grade 2, thicker complete white circumferential membrane with cough and/or obstructive problems requiring intervention; grade 3, severe inflammatory response with marked membranous exudate and mild fibrotic reaction; and grade 4 a predominant fibrotic reaction with progressive stenosis. Variables associated with a slightly increased incidence of radiation bronchitis and stenosis included: large cell carcinoma histology, curative intent, prior laser photoresection, and/or concurrent external radiation. Survival was the strongest predictor of the reaction. Radiation bronchitis and stenosis is a new clinical entity that must be identified in bronchial brachytherapy patients and treated appropriately. 23 refs., 3 figs., 7 tabs.

  9. Kinetics of the current response in TlBr detectors under a high dose rate of {gamma}-ray irradiation

    SciTech Connect

    Gazizov, I. M.; Zaletin, V. M.; Kukushkin, V. M.; Kuznetsov, M. S.; Lisitsky, I. S.

    2012-03-15

    The kinetics of the photocurrent response in doped and undoped TlBr samples subjected to irradiation with {gamma}-ray photons from a {sup 137}Cs source with the dose rate 0.033 to 3.84 Gy/min are studied. The crystals were grown by the directional crystallization of the melt method using the Bridgman-Stockbarger technique. The Pb impurity mass fraction introduced into the doped TlBr crystals was 1-10 ppm and amounted to 150 ppm for the Ca impurity. The crystals were grown in a vacuum, in bromine vapors, in a hydrogen atmosphere, and in air. Decay of the photocurrent is observed for extrinsic semiconductor crystals doped with bivalent cations (irrespective of the growth atmosphere), and also for crystals grown in hydrogen and crystals grown in an excess of thallium. The time constant of photocurrent decay {tau} amounted to 30-1400 s and was proportional to resistivity. It is shown that the current response can be related to photolysis in the TlBr crystals during irradiation with {gamma}-ray photons. The energy of hole traps responsible for a slow increase in the photo-current has been estimated and found to be equal to 0.6-0.85 eV.

  10. Determining the americium transmutation rate and fission rate by post-irradiation examination within the scope of the ECRIX-H experiment

    NASA Astrophysics Data System (ADS)

    Lamontagne, J.; Pontillon, Y.; Esbelin, E.; Béjaoui, S.; Pasquet, B.; Bourdot, P.; Bonnerot, J. M.

    2013-09-01

    The ECRIX-H experiment aims to assess the feasibility of transmuting americium micro-dispersed in an inert magnesia matrix under a locally moderated neutron flux in the Phénix reactor. A first set of examinations demonstrated that pellet behaviour was satisfactory with moderate swelling at the end of the irradiation. Additional post-irradiation examinations needed to be conducted to confirm the high transmutation rate so as to definitively conclude on the success of the ECRIX-H experiment. This article presents and discusses the results of these new examinations. They confirm the satisfactory behaviour of the MgO matrix not only during the basic irradiation but also during post-irradiation thermal transients. These examinations also provide additional information on the behaviour of fission products both in the americium-based particles and in the MgO matrix. These results particularly validate the transmutation rate predicted by the calculation codes using several different analytical techniques. The fission rate is also determined. Moderate pellet swelling under irradiation (6.7 vol.%), while only 23% of the produced He and 4% of the fission gases were released from the fuel. No interaction between the pellets and the cladding. Formation of bubbles due to the precipitation of fission gases and He mainly in bubbles located inside the americium-based particles. These bubbles are the main cause of macroscopic swelling in the pellets. Well-crystallised structure of the MgO matrix which shows no amorphisation after irradiation despite the presence of fission products. The absence of any reaction of MgO with the americium-based phase, Formation of a PuO2-type crystalline phase from AmO1.62 particles following the Am transmutation process. A shielded electron probe micro-analyser (EPMA) 'CAMECA' Camebax equipped to collect and exploit the measurements using the 'SAMx' system. A Philips XL30 scanning electron microscope (SEM). Field acquisitions were performed thanks to

  11. Theory of absorption rate of carriers in fused silica under intense laser irradiation

    SciTech Connect

    Deng, Hongxiang; Xiang, Xia; Zheng, WG; Yuan, XD; Wu, SY; Jiang, XD; Gao, Fei; Zu, Xiaotao T.; Sun, Kai

    2010-11-15

    A quantum non-perturbation theory for phonon-assisted photon absorption of conduction band electron in intense laser was developed. By carrying out the calculation in fused silica at wavelengths from ultraviolet to infrared in terawatt intensity laser, we show that the Non-perturbation approach can make a uniform description of energy absorption rate at both short wavelengths and long wavelengths on TW / cm2 intensity laser.

  12. Elevated temperature tensile properties of irradiated 20/25/Nb stainless steel fuel pin cladding at low and high strain rates

    NASA Astrophysics Data System (ADS)

    Gravenor, J. G.; Douglas, J.

    1988-09-01

    Tensile specimens were prepared from 20/25/Nb stainless steel fuel pin cladding irradiated in a Commercial Advanced Gas-cooled Reactor (CAGR) at temperatures in the range 622-866 K and integrated fast neutron doses up to 16 × 10 24n/ m2. The tests were performed in air at temperatures in the range 298-873 K at strain rates from 2 × 10 -5s-1 to 7.2 s -1. The tensile properties varied with irradiation temperature, test temperature and strain rate. At lower irradiation temperature, strengthening produced by fast neutron damage was accompanied by reduced elongation. Strengthening was also observed at higher irradiation temperatures, possibly due to precipitation phenomena. The maximum irradiation embrittlement was observed in tests at 873 K at low strain rates between 2 × 10 -4s-1 and 2 × 10 -5s-1. The failure mode of embrittled specimens irradiated at higher temperatures was characterized by prematurely ruptured ductile fibres, rather than by intergranular cracking.

  13. Effect of strain rate on the tensile properties of unirradiated and irradiated V-4Cr-4Ti

    NASA Astrophysics Data System (ADS)

    Rowcliffe, A. F.; Zinkle, S. J.; Hoelzer, D. T.

    2000-12-01

    Tensile tests were carried out on an annealed, unirradiated V-4Cr-4Ti alloy from RT to 850°C at strain rates ranging from 10-1 to 10-5 s-1. Below 300°C, where interstitial solutes are relatively immobile, deformation is homogeneous, and the strain rate sensitivity (SRS) of the yield and flow stress is positive. Between 300°C and 700°C, the formation of solute atmospheres at locked dislocations results in dynamic strain-aging (DSA), deformation becomes heterogeneous, and the SRS of the flow stress is negative; in this regime the lower yield stress is independent of strain rate. Above 700°C, substitutional solutes are also mobile, DSA declines, and the material enters a power law creep regime in which the SRS becomes positive again. Following neutron irradiation to 0.5 dpa at temperatures ⩽400°C, severe flow localization occurs due to the high number density of <1 1 0> and <1 1 1> loops. However, above 400°C, strain hardening capacity returns but without the Lüders extension. At 500°C, after several percent plastic deformation, DSA occurs as interstitial solutes are released from the defect structure.

  14. Differential expression of cancer pathway-related genes in low-versus high-dose-rate-irradiated AKR/J mice

    NASA Astrophysics Data System (ADS)

    Jong Bong, Jin; Kang, Yu Mi; Shin, Suk Chul; Choi, Moo Hyun; Choi, Seung Jin; Kim, Hee Sun

    2012-11-01

    To understand the biological effects of ionizing radiation on lymphomagenesis, we reared AKR/J mice for 130 days with exposure to either high-dose-rate (HDR, 0.8 Gy/min, a single dose of 4.5 Gy) or low-dose-rate (LDR, 0.7 mGy/h, a cumulative dose of 2.1 Gy) irradiation. After 130 days, we compared the mean thymus weight, analyzed the histological changes, and measured apoptotic cell numbers using the terminal deoxynucleotidyl transferase-mediated dUTP-end labeling (TUNEL) assay. We also used microarrays and quantitative polymerase chain reaction analysis (qPCR) to analyze the expression profiles of cancer pathway-related genes in the thymuses of the mice. The mean thymus weight of the LDR-irradiated mice decreased relative to Sham- and HDR-irradiated mice. Histopathological examination revealed that the neoplastic cells in the thymuses of the Sham- and HDR-irradiated mice were pleomorphic, with marked anisocytosis and anisokaryosis, whereas the cells and their nuclei were relatively small and uniform in size in the LDR-irradiated mice. Furthermore, TUNEL assays showed that the number of apoptotic cells was higher in the LDR-irradiated mice than in the Sham- and HDR-irradiated mice. Microarray analysis showed differentially expressed genes according to carcinogenic stage (DNA repair/genomic instability, DNA damage signaling pathway, cell cycle, cancer pathway, p53 signaling pathway, apoptosis, and T- and B-cell activation). qPCR data for cancer pathway-related genes showed that Cds1 gene expression was upregulated in the LDR-irradiated mice, whereas expression of the Itga4, Myc, and Itgb1 genes was upregulated in the irradiated mice. However, the functions of cancer pathway-related genes require further study and validation.

  15. TGF-B3 Dependent Modification of Radiosensitivity in Reporter Cells Exposed to Serum From Whole-Body Low Dose-Rate Irradiated Mice.

    PubMed

    Edin, Nina Jeppesen; Altaner, Čestmír; Altanerova, Veronica; Ebbesen, Peter

    2015-01-01

    Prior findings in vitro of a TGF-β3 dependent mechanism induced by low dose-rate irradiation and resulting in increased radioresistance and removal of low dose hyper-radiosensitivity (HRS) was tested in an in vivo model. DBA/2 mice were given whole-body irradiation for 1 h at low dose-rates (LDR) of 0.3 or 0.03 Gy/h. Serum was harvested and added to RPMI (4% mouse serum and 6% bovine serum).This medium was transferred to reporter cells (T-47D breast cancer cells or T98G glioblastoma cells). The response to subsequent challenge irradiation of the reporter cells was measured by the colony assay. While serum from unirradiated control mice had no effect on the radiosensitivity in the reporter cells, serum from mice given 0.3 Gy/h or 0.03 Gy/h for 1 h removed HRS and also increased survival in response to doses up to 5 Gy. The effect lasted for at least 15 months after irradiation. TGF-β3 neutralizer added to the medium containing mouse serum inhibited the effect. Serum from mice given irradiation of 0.3 Gy/h for 1 h and subsequently treated with iNOS inhibitor 1400W did not affect radiosensitivity in reporter cells; neither did serum from the unirradiated progeny of mice given 1h LDR whole-body irradiation. PMID:26673923

  16. Analysis of Chromosomal Aberrations after Low and High Dose Rate Gamma Irradiation in ATM or NBS Suppressed Human Fibroblast Cells

    NASA Technical Reports Server (NTRS)

    Hada, M.; Huff, J. L.; Patel, Z.; Pluth, J. M.; George, K. A.; Cucinotta, F. A.

    2009-01-01

    condensation (PCC) technique at the first mitosis post-irradiation. Chromosomes were analyzed using a multicolor fluorescence in-situ hybridization (mFISH) chromosome painting method. Preliminary analysis showed that chromosomal exchanges were increased in the cells treated with the specific ATM inhibitor. Possible cytogenetic signatures of acute and low dose-rate gamma irradiation in ATM or Nibrin deficient and suppressed cells will be discussed.

  17. Determining the americium transmutation rate and fission rate by post-irradiation examination within the scope of the ECRIX-H experiment

    NASA Astrophysics Data System (ADS)

    Lamontagne, J.; Pontillon, Y.; Esbelin, E.; Béjaoui, S.; Pasquet, B.; Bourdot, P.; Bonnerot, J. M.

    2013-09-01

    The ECRIX-H experiment aims to assess the feasibility of transmuting americium micro-dispersed in an inert magnesia matrix under a locally moderated neutron flux in the Phénix reactor. A first set of examinations demonstrated that pellet behaviour was satisfactory with moderate swelling at the end of the irradiation. Additional post-irradiation examinations needed to be conducted to confirm the high transmutation rate so as to definitively conclude on the success of the ECRIX-H experiment. This article presents and discusses the results of these new examinations. They confirm the satisfactory behaviour of the MgO matrix not only during the basic irradiation but also during post-irradiation thermal transients. These examinations also provide additional information on the behaviour of fission products both in the americium-based particles and in the MgO matrix. These results particularly validate the transmutation rate predicted by the calculation codes using several different analytical techniques. The fission rate is also determined. Moderate pellet swelling under irradiation (6.7 vol.%), while only 23% of the produced He and 4% of the fission gases were released from the fuel. No interaction between the pellets and the cladding. Formation of bubbles due to the precipitation of fission gases and He mainly in bubbles located inside the americium-based particles. These bubbles are the main cause of macroscopic swelling in the pellets. Well-crystallised structure of the MgO matrix which shows no amorphisation after irradiation despite the presence of fission products. The absence of any reaction of MgO with the americium-based phase, Formation of a PuO2-type crystalline phase from AmO1.62 particles following the Am transmutation process. A shielded electron probe micro-analyser (EPMA) 'CAMECA' Camebax equipped to collect and exploit the measurements using the 'SAMx' system. A Philips XL30 scanning electron microscope (SEM). Field acquisitions were performed thanks to

  18. Effects of irradiation temperature and dose rate on the mechanical properties of self-ion implanted Fe and Fe-Cr alloys

    NASA Astrophysics Data System (ADS)

    Hardie, Christopher D.; Williams, Ceri A.; Xu, Shuo; Roberts, Steve G.

    2013-08-01

    Pure Fe and model Fe-Cr alloys containing 5, 10 and 14%Cr were irradiated with Fe+ ions at a maximum energy of 2 MeV to the same dose of 0.6 dpa at temperatures of 300 °C, 400 °C and 500 °C, and at dose rates corresponding to 6 × 10-4 dpa/s and 3 × 10-5 dpa/s. All materials exhibited an increase in hardness after irradiation at 300 °C. After irradiation at 400 °C, hardening was observed only in Fe-Cr alloys, and not in the pure Fe. After irradiation at 500 °C, no hardening was observed in any of the materials tested. For irradiations at both 300 °C and 400 °C, greater hardening was found in the Fe-Cr alloys irradiated at the lower dose rate. Transmission electron microscopy and atom probe tomography of Fe 5%Cr identified larger dislocation loop densities and sizes in the alloy irradiated with the high dose rate and Cr precipitation in the alloy irradiated with the low dose rate. Loss of defects at extended sinks such as dislocations and grain boundaries. Growth or shrinkage of defect clusters by the capture of point defects. Mutual annihilation by the recombination of a vacancy and interstitial. At low dose rates and/or high irradiation temperatures, reaction path (i) (sinks) dominates and at a high dose rates and/or low irradiation temperature reaction path (iii) (recombination) dominates [2]. The evolution of radiation damage such as dislocation loops and voids and phenomena such as radiation induced segregation, swelling and creep, depend on the fraction of point defects which migrate to sinks, recombine or cluster within the lattice and will be influenced by the reaction path that dominates the microstructural evolution of the material under irradiation.The relative proportions of these reaction types are directly dependent on the density and mobility of the defects, and hence dependent on dose rate and temperature. In iron, vacancy type defects are generally found to have significantly higher activation energy for migration compared to interstitial

  19. Bystander Effects Induced by Continuous Low-Dose-Rate {sup 125}I Seeds Potentiate the Killing Action of Irradiation on Human Lung Cancer Cells In Vitro

    SciTech Connect

    Chen, H.H. Jia, R.F.; Yu, L.; Zhao, M.J.; Shao, C.L.; Cheng, W.Y.

    2008-12-01

    Purpose: To investigate bystander effects of low-dose-rate (LDR) {sup 125}I seed irradiation on human lung cancer cells in vitro. Methods and Materials: A549 and NCI-H446 cell lines of differing radiosensitivity were directly exposed to LDR {sup 125}I seeds irradiation for 2 or 4 Gy and then cocultured with nonirradiated cells for 24 hours. Induction of micronucleus (MN), {gamma}H2AX foci, and apoptosis were assayed. Results: After 2 and 4 Gy irradiation, micronucleus formation rate (MFR) and apoptotic rate of A549 and NCI-H446 cells were increased, and the MFR and apoptotic rate of NCI-H446 cells was 2.1-2.8 times higher than that of A549 cells. After coculturing nonirradiated bystander cells with {sup 125}I seed irradiated cells for 24 hours, MFR and the mean number of {gamma}H2AX foci/cells of bystander A549 and NCI-H446 cells were similar and significantly higher than those of control (p <0.05), although they did not increase with irradiation dose. However, the proportion of bystander NCI-H446 cells with MN numbers {>=}3 and {gamma}H2AX foci numbers 15-19 and 20-24 was higher than that of bystander A549 cells. In addition, dimethyl sulfoxide (DMSO) treatment could completely suppress the bystander MN of NCI-H446 cells, but it suppressed only partly the bystander MN of A549 cells, indicating that reactive oxygen species are involved in the bystander response to NCI-H446 cells, but other signaling factors may contribute to the bystander response of A549 cells. Conclusions: Continuous LDR irradiation of {sup 125}I seeds could induce bystander effects, which potentiate the killing action on tumor cells and compensate for the influence of nonuniform distribution of radiation dosage on therapeutic outcomes.

  20. Effects of irradiation temperature and dose rate on the mechanical properties of self-ion implanted Fe and Fe-Cr alloys

    NASA Astrophysics Data System (ADS)

    Hardie, Christopher D.; Williams, Ceri A.; Xu, Shuo; Roberts, Steve G.

    2013-08-01

    Pure Fe and model Fe-Cr alloys containing 5, 10 and 14%Cr were irradiated with Fe+ ions at a maximum energy of 2 MeV to the same dose of 0.6 dpa at temperatures of 300 °C, 400 °C and 500 °C, and at dose rates corresponding to 6 × 10-4 dpa/s and 3 × 10-5 dpa/s. All materials exhibited an increase in hardness after irradiation at 300 °C. After irradiation at 400 °C, hardening was observed only in Fe-Cr alloys, and not in the pure Fe. After irradiation at 500 °C, no hardening was observed in any of the materials tested. For irradiations at both 300 °C and 400 °C, greater hardening was found in the Fe-Cr alloys irradiated at the lower dose rate. Transmission electron microscopy and atom probe tomography of Fe 5%Cr identified larger dislocation loop densities and sizes in the alloy irradiated with the high dose rate and Cr precipitation in the alloy irradiated with the low dose rate. Loss of defects at extended sinks such as dislocations and grain boundaries. Growth or shrinkage of defect clusters by the capture of point defects. Mutual annihilation by the recombination of a vacancy and interstitial. At low dose rates and/or high irradiation temperatures, reaction path (i) (sinks) dominates and at a high dose rates and/or low irradiation temperature reaction path (iii) (recombination) dominates [2]. The evolution of radiation damage such as dislocation loops and voids and phenomena such as radiation induced segregation, swelling and creep, depend on the fraction of point defects which migrate to sinks, recombine or cluster within the lattice and will be influenced by the reaction path that dominates the microstructural evolution of the material under irradiation.The relative proportions of these reaction types are directly dependent on the density and mobility of the defects, and hence dependent on dose rate and temperature. In iron, vacancy type defects are generally found to have significantly higher activation energy for migration compared to interstitial

  1. Evaluation of two intracavitary high-dose-rate brachytherapy devices for irradiating additional and irregularly shaped volumes of breast tissue.

    PubMed

    Lu, Sharon M; Scanderbeg, Daniel J; Barna, Patrick; Yashar, William; Yashar, Catheryn

    2012-01-01

    The SAVI and Contura breast brachytherapy applicators represent 2 recent advancements in brachytherapy technology that have expanded the number of women eligible for accelerated partial breast irradiation in the treatment of early-stage breast cancer. Early clinical experience with these 2 single-entry, multichannel high-dose-rate brachytherapy devices confirms their ease of use and dosimetric versatility. However, current clinical guidelines for SAVI and Contura brachytherapy may result in a smaller or less optimal volume of treated tissue compared with traditional interstitial brachytherapy. This study evaluates the feasibility of using the SAVI and Contura to irradiate larger and irregularly shaped target volumes, approaching what is treatable with the interstitial technique. To investigate whether additional tissue can be treated, 17 patients treated with the SAVI and 3 with the Contura were selected. For each patient, the planning target volume (PTV) was modified to extend 1.1 cm, 1.3 cm, and 1.5 cm beyond the tumor bed cavity. To evaluate dose conformance to an irregularly shaped target volume, 9 patients treated with the SAVI and 3 with the Contura were selected from the original 20 patients. The following asymmetric PTV margin combinations were assessed for each patient: 1.5/0.3, 1.3/0.3, and 1.1/0.3 cm. For all patients, treatment planning was performed, adopting the National Surgical Adjuvant Breast and Bowel Project guidelines, and dosimetric comparisons were made. The 6-1 and 8-1 SAVI devices can theoretically treat a maximal tissue margin of 1.5 cm and an asymmetric PTV with margins ranging from 0.3 to 1.5 cm. The 10-1 SAVI and Contura can treat a maximal margin of 1.3 cm and 1.1 cm, respectively, and asymmetric PTV with margins ranging from 0.3-1.3 cm. Compared with the Contura, the SAVI demonstrated greater dosimetric flexibility. Risk of developing excessive hot spots increased with the size of the SAVI device. Both the SAVI and Contura appear

  2. [Molecular-genetic and epidemiologic examination of personnel subjected to occupational irradiation in Russian Federal Nuclear Center (Sarov). Report 1. Genome structural damage rate and radiosensitivity].

    PubMed

    Korzeneva, I B; Zaichkina, S I; Malinina, T V; Afanas'ev, K I; Dubrova, Iu E; Skorodumova, E N; Samsonova, V F; Volkova, I V; Shishova, R T; Shcherbakova, I L

    2008-01-01

    A comparative evaluation of the cytological and dosimetric examination of the cohort comprised by VNIEF personnel subjected chronically to gamma-neutron ionizing radiation, as well as non-irradiated cohort is given. The obtained data on the influence of the occupational and on X-ray irradiation, age and smoking on the rate of structural genome damage, as well as the activity of the human repair system activity are presented. The influence of the individual heterozygosis by 9 polymorphous loci: Hp, Tf, Gc; 6-PGD, EsD, ACP, PGM1, microsatellite lici SCF1PO and F13AO1 is shown. PMID:19004324

  3. Materials corrosion and mitigation strategies for APT, end of FY `97 report: Inconel 718 in-beam corrosion rates from the `97 A6 irradiation

    SciTech Connect

    Lillard, R.S.; Pile, D.L.; Butt, D.P.

    1998-08-01

    This report summarizes the results from the 1997 irradiation of the corrosion insert at the LANSCE A6 Target Station. It addresses the corrosion measurements made on the in-beam Inconel 718 probe only. To simulate the environment that materials may be exposed to in a spallation neutron target/blanket cooling loops, samples were irradiated by the proton beam at the A6 Target Station of the Los Alamos Neutron Scattering Center (LANSCE). EIS measurements have demonstrated that the polarization resistance of IN718 decreases from approximately 3 x 10{sup 5} ohms prior to irradiation to approximately 1,000 ohms during irradiation at a proton beam current of 400 {micro}A. From the polarization resistance measurements, corrosion rate as a function of beam current was calculated for several different scenarios of beam/sample interaction. As the beam spot was small relative to the size of the IN718 corrosion probe (2{sigma} = 3 cm vs. 1.3 cm diam. x 15.9 cm length respectively), The first method for calculating corrosion rate used beam profile as a criterion for the area of highest damage. The beam spot intensity profile at LANSCE has been characterized and found to be a Gaussian distribution rotated about a central axis. From this relationship, and R{sub p} as a function of beam current, corrosion rate as a function of radial distance from the center of the beam was calculated for each beam current. Physical evidence from change in thickness measurements made on tungsten rods irradiated at 1 mA during the FY 96 irradiation period suggest that this Gaussian damage profile is an accurate depiction of beam/sample interaction. From this method the corrosion rate of IN718 during irradiation at a beam current of 1.0 mA is calculated to be approximately 0.002 inches per yr (2 mpy). The second method assumed that the predominant contributor to the corrosion current comes from an area defined by 2{sigma}. Further, the method assumed that the corrosion rate was uniform over this area

  4. Using the quantum yields of photosystem II and the rate of net photosynthesis to monitor high irradiance and temperature stress in chrysanthemum (Dendranthema grandiflora).

    PubMed

    Janka, Eshetu; Körner, Oliver; Rosenqvist, Eva; Ottosen, Carl-Otto

    2015-05-01

    Under a dynamic greenhouse climate control regime, temperature is adjusted to optimise plant physiological responses to prevailing irradiance levels; thus, both temperature and irradiance are used by the plant to maximise the rate of photosynthesis, assuming other factors are not limiting. The control regime may be optimised by monitoring plant responses, and may be promptly adjusted when plant performance is affected by extreme microclimatic conditions, such as high irradiance or temperature. To determine the stress indicators of plants based on their physiological responses, net photosynthesis (Pn) and four chlorophyll-a fluorescence parameters: maximum photochemical efficiency of PSII [Fv/Fm], electron transport rate [ETR], PSII operating efficiency [F'q/F'm], and non-photochemical quenching [NPQ] were assessed for potted chrysanthemum (Dendranthema grandiflora Tzvelev) 'Coral Charm' under different temperature (20, 24, 28, 32, 36 °C) and daily light integrals (DLI; 11, 20, 31, and 43 mol m(-2) created by a PAR of 171, 311, 485 and 667 μmol m(-2) s(-1) for 16 h). High irradiance (667 μmol m(-2) s(-1)) combined with high temperature (>32 °C) significantly (p < 0.05) decreased Fv/Fm. Under high irradiance, the maximum Pn and ETR were reached at 24 °C. Increased irradiance decreased the PSII operating efficiency and increased NPQ, while both high irradiance and temperature had a significant effect on the PSII operating efficiency at temperatures >28 °C. Under high irradiance and temperature, changes in the NPQ determined the PSII operating efficiency, with no major change in the fraction of open PSII centres (qL) (indicating a QA redox state). We conclude that 1) chrysanthemum plants cope with excess irradiance by non-radiative dissipation or a reversible stress response, with the effect on the Pn and quantum yield of PSII remaining low until the temperature reaches 28 °C and 2) the integration of online measurements to monitor photosynthesis and PSII

  5. Dependence of steady-state radiation swelling rate of l 0.1C-16Cr-15Ni-2Mo-2Mn-Ti-Si austenitic steel on dpa rate and irradiation temperature

    NASA Astrophysics Data System (ADS)

    Kozlov, А. V.; Portnykh, I. А.

    2009-04-01

    A large number of swelling measurement data on the 0.1C-16Cr-15Ni-2Mo-2Mn-Ti-Si austenitic steel used as a fuel cladding at temperatures 640-870 К in the BN-600 fast reactor were analyzed. It was found that within irradiation temperatures 690-830 К a steady-state swelling dose rate was from 0.45%/dpa to 1.1%/dpa. By the statistical model of point defect migration for the 0.1C-16Cr-15Ni-2Mo-2Mn-Ti-S steel the dependence of the steady-state swelling rate on the irradiation temperature and displacement rate was calculated. The calculation data were consistent with the experimental data.

  6. Limitations of current dosimetry for intracavitary accelerated partial breast irradiation with high dose rate iridium-192 and electronic brachytherapy sources

    NASA Astrophysics Data System (ADS)

    Raffi, Julie A.

    Intracavitary accelerated partial breast irradiation (APBI) is a method of treating early stage breast cancer using a high dose rate (HDR) brachytherapy source positioned within the lumpectomy cavity. An expandable applicator stretches the surrounding tissue into a roughly spherical or elliptical shape and the dose is prescribed to 1 cm beyond the edge of the cavity. Currently, dosimetry for these treatments is most often performed using the American Association of Physicists in Medicine Task Group No. 43 (TG-43) formalism. The TG-43 dose-rate equation determines the dose delivered to a homogeneous water medium by scaling the measured source strength with standardized parameters that describe the radial and angular features of the dose distribution. Since TG-43 parameters for each source model are measured or calculated in a homogeneous water medium, the dosimetric effects of the patient's dimensions and composition are not accounted for. Therefore, the accuracy of TG-43 calculations for intracavitary APBI is limited by the presence of inhomogeneities in and around the target volume. Specifically, the breast is smaller than the phantoms used to determine TG-43 parameters and is surrounded by air, ribs, and lung tissue. Also, the composition of the breast tissue itself can affect the dose distribution. This dissertation is focused on investigating the limitations of TG-43 dosimetry for intracavitary APBI for two HDR brachytherapy sources: the VariSource TM VS2000 192Ir source and the AxxentRTM miniature x-ray source. The dose for various conditions was determined using thermoluminescent dosimeters (TLDs) and Monte Carlo (MC) calculations. Accurate measurements and calculations were achieved through the implementation of new measurement and simulation techniques and a novel breast phantom was developed to enable anthropomorphic phantom measurements. Measured and calculated doses for phantom and patient geometries were compared with TG-43 calculated doses to

  7. Microbial Survival Rates of Escherichia coli and Deinococcus radiodurans Under Low Temperature, Low Pressure, and UV-Irradiation Conditions, and Their Relevance to Possible Martian Life

    NASA Astrophysics Data System (ADS)

    Diaz, Benjamin; Schulze-Makuch, Dirk

    2006-04-01

    Viability rates were determined for microbial populations of Escherichia coli and Deinococcus radiodurans under the environmental stresses of low temperature (-35°C), low-pressure conditions (83.3 kPa), and ultraviolet (UV) irradiation (37 W/m2). During the stress tests the organisms were suspended in saltwater soil and freshwater soil media, at variable burial depths, and in seawater. Microbial populations of both organisms were most susceptible to dehydration stress associated with low-pressure conditions, and to UV irradiation. However, suspension in a liquid water medium and burial at larger depths (5 cm) improved survival rates markedly. Our results indicate that planetary surfaces that possess little to no atmosphere and have low water availability do not constitute a favorable environment for terrestrial microorganisms.

  8. Freshly induced short-lived gamma-ray activity as a measure of fission rates in lightly re-irradiated spent fuel

    NASA Astrophysics Data System (ADS)

    Kröhnert, H.; Perret, G.; Murphy, M. F.; Chawla, R.

    2010-12-01

    A new measurement technique has been developed to determine fission rates in burnt fuel, following re-irradiation in a zero-power research reactor. The development has been made in the frame of the LIFE@PROTEUS program at the Paul Scherrer Institute, which aims at characterizing the interfaces between fresh and highly burnt fuel assemblies in modern LWRs. To discriminate against the high intrinsic gamma-ray activity of the burnt fuel, the proposed measurement technique uses high-energy gamma-rays, above 2000 keV, emitted by short-lived fission products freshly produced in the fuel. To demonstrate the feasibility of this technique, a fresh UO 2 sample and a 36 GWd/t burnt UO 2 sample were irradiated in the PROTEUS reactor and their gamma-ray activities were recorded directly after irradiation. For both fresh and the burnt fuel samples, relative fission rates were derived for different core positions, based on the short-lived 142La (2542 keV), 89Rb (2570 keV), 138Cs (2640 keV) and 95Y (3576 keV) gamma-ray lines. Uncertainties on the inter-position fission rate ratios were mainly due to the uncertainties on the net-area of the gamma-ray peaks and were about 1-3% for the fresh sample, and 3-6% for the burnt one. Thus, for the first time, it has been shown that the short-lived gamma-ray activity, induced in burnt fuel by irradiation in a zero-power reactor, can be used as a quantitative measure of the fission rate. For both fresh and burnt fuel, the measured results agreed, within the uncertainties, with Monte Carlo (MCNPX) predictions.

  9. The dependence of helium generation rate on nickel content of Fe-Cr-Ni alloys irradiated at high dpa levels in fast reactors

    SciTech Connect

    Garner, F.A.; Oliver, B.M.; Greenwood, L.R.

    1997-04-01

    With a few exceptions in the literature, it is generally accepted that it is nickel in Fe-Cr-Ni alloys that produces most of the transmutant helium and that the helium generation rate should scale linearly with the nickel content. Surprisingly, this assumption is based only on irradiations of pure nickel and has never been tested in an alloy series. There have also been no extensive tests of the predictions for helium production in alloys in various fast reactors spectra.

  10. SU-E-T-501: Normal Tissue Toxicities of Pulsed Low Dose Rate Radiotherapy and Conventional Radiotherapy: An in Vivo Total Body Irradiation Study

    SciTech Connect

    Cvetkovic, D; Zhang, P; Wang, B; Chen, L; Ma, C

    2014-06-01

    Purpose: Pulsed low dose rate radiotherapy (PLDR) is a re-irradiation technique for therapy of recurrent cancers. We have previously shown a significant difference in the weight and survival time between the mice treated with conventional radiotherapy (CRT) and PLDR using total body irradiation (TBI). The purpose of this study was to investigate the in vivo effects of PLDR on normal mouse tissues.Materials and Methods: Twenty two male BALB/c nude mice, 4 months of age, were randomly assigned into a PLDR group (n=10), a CRT group (n=10), and a non-irradiated control group (n=2). The Siemens Artiste accelerator with 6 MV photon beams was used. The mice received a total of 18Gy in 3 fractions with a 20day interval. The CRT group received the 6Gy dose continuously at a dose rate of 300 MU/min. The PLDR group was irradiated with 0.2Gyx20 pulses with a 3min interval between the pulses. The mice were weighed thrice weekly and sacrificed 2 weeks after the last treatment. Brain, heart, lung, liver, spleen, gastrointestinal, urinary and reproductive organs, and sternal bone marrow were removed, formalin-fixed, paraffin-embedded and stained with H and E. Morphological changes were observed under a microscope. Results: Histopathological examination revealed atrophy in several irradiated organs. The degree of atrophy was mild to moderate in the PLDR group, but severe in the CRT group. The most pronounced morphological abnormalities were in the immune and hematopoietic systems, namely spleen and bone marrow. Brain hemorrhage was seen in the CRT group, but not in the PLDR group. Conclusions: Our results showed that PLDR induced less toxicity in the normal mouse tissues than conventional radiotherapy for the same dose and regimen. Considering that PLDR produces equivalent tumor control as conventional radiotherapy, it would be a good modality for treatment of recurrent cancers.

  11. Unexpected behaviour of polystyrene-based scintillating fibers during irradiation at low doses and low dose rates

    NASA Astrophysics Data System (ADS)

    Wick, K.; Zoufal, T.

    2001-12-01

    The time dependence of the optical radiation damage process was studied for different fibers with polystyrene (PS) core. The fibers were irradiated with X-rays. In the present experiment the light guide BCF-98 (Bicron, clear polystyrene) was compared with the two scintillating fibers SCSF-38 and SCSF-81 (Kuraray). The light transmission through the fiber was investigated before, during and after irradiation. All investigated fibers showed unexpected effects depending on the fiber type: (1) at low doses the scintillating fibers are more sensitive to radiation than at high doses, i.e. the optical absorption rises nonlinearly with dose; (2) shortlived optical absorption centers decaying within several hours were detected in all fibers with PS core investigated up to now. Especially for SCSF-81, the annealing part is large and it totally overlaps the emission spectrum of the fiber.

  12. Analysis of dose rates received around the storage pool for irradiated control rods in a BWR nuclear power plant.

    PubMed

    Ródenas, J; Abarca, A; Gallardo, S

    2011-08-01

    BWR control rods are activated by neutron reactions in the reactor. The dose produced by this activity can affect workers in the area surrounding the storage pool, where activated rods are stored. Monte Carlo (MC) models for neutron activation and dose assessment around the storage pool have been developed and validated. In this work, the MC models are applied to verify the expected reduction of dose when the irradiated control rod is hanged in an inverted position into the pool. PMID:21093278

  13. Gamma-ray spectrometric measurements of fission rate ratios between fresh and burnt fuel following irradiation in a zero-power reactor

    NASA Astrophysics Data System (ADS)

    Kröhnert, H.; Perret, G.; Murphy, M. F.; Chawla, R.

    2013-01-01

    The gamma-ray activity from short-lived fission products has been measured in fresh and burnt UO2 fuel samples after irradiation in a zero-power reactor. For the first time, short-lived gamma-ray activity from fresh and burnt fuel has been compared and fresh-to-burnt fuel fission rate ratios have been derived. For the measurements, well characterized fresh and burnt fuel samples, with burn-ups up to 46 GWd/t, were irradiated in the zero-power research reactor PROTEUS. Fission rate ratios were derived based on the counting of high-energy gamma-rays above 2200 keV, in order to discriminate against the high intrinsic activity of the burnt fuel. This paper presents the measured fresh-to-burnt fuel fission rate ratios based on the 142La (2542 keV), 89Rb (2570 keV), 138Cs (2640 keV) and 95Y (3576 keV) high-energy gamma-ray lines. Comparisons are made with the results of Monte Carlo modeling of the experimental configuration, carried out using the MCNPX code. The measured fission rate ratios have 1σ uncertainties of 1.7-3.4%. The comparisons with calculated predictions show an agreement within 1-3σ, although there appears to be a slight bias (∼3%).

  14. Factors Associated With Chest Wall Toxicity After Accelerated Partial Breast Irradiation Using High-Dose-Rate Brachytherapy

    SciTech Connect

    Brown, Sheree; Vicini, Frank; Vanapalli, Jyotsna R.; Whitaker, Thomas J.; Pope, D. Keith; Lyden, Maureen; Bruggeman, Lisa; Haile, Kenneth L.; McLaughlin, Mark P.

    2012-07-01

    Purpose: The purpose of this analysis was to evaluate dose-volume relationships associated with a higher probability for developing chest wall toxicity (pain) after accelerated partial breast irradiation (APBI) by using both single-lumen and multilumen brachytherapy. Methods and Materials: Rib dose data were available for 89 patients treated with APBI and were correlated with the development of chest wall/rib pain at any point after treatment. Ribs were contoured on computed tomography planning scans, and rib dose-volume histograms (DVH) along with histograms for other structures were constructed. Rib DVH data for all patients were sampled at all volumes {>=}0.008 cubic centimeter (cc) (for maximum dose related to pain) and at volumes of 0.5, 1, 2, and 3 cc for analysis. Rib pain was evaluated at each follow-up visit. Patient responses were marked as yes or no. No attempt was made to grade responses. Eighty-nine responses were available for this analysis. Results: Nineteen patients (21.3%) complained of transient chest wall/rib pain at any point in follow-up. Analysis showed a direct correlation between total dose received and volume of rib irradiated with the probability of developing rib/chest wall pain at any point after follow-up. The median maximum dose at volumes {>=}0.008 cc of rib in patients who experienced chest wall pain was 132% of the prescribed dose versus 95% of the prescribed dose in those patients who did not experience pain (p = 0.0035). Conclusions: Although the incidence of chest wall/rib pain is quite low with APBI brachytherapy, attempts should be made to keep the volume of rib irradiated at a minimum and the maximum dose received by the chest wall as low as reasonably achievable.

  15. Intravenous Laser Blood Irradiation, Interstitial Laser Acupuncture, and Electroacupuncture in an Animal Experimental Setting: Preliminary Results from Heart Rate Variability and Electrocorticographic Recordings

    PubMed Central

    He, Wei; Wang, Xiaoyu; Jing, Xianghong; Shi, Hong; Shang, Hongyan; Zhu, Bing

    2013-01-01

    This is the first study to investigate intravenous (i.v.) laser blood irradiation, interstitial (i.st.) laser acupuncture, and electroacupuncture (EA) in combination with heart rate variability (HRV) and electrocorticogram. We investigated 10 male anesthetized Sprague-Dawley rats under the three conditions mentioned previously in Beijing, China, and data analysis was performed in Graz, Europe. For i.v. laser stimulation in the femoral vein and i.st. laser acupuncture at Neiguan (PC6), we used a European system (Modulas needle, Schwa-Medico, Germany; 658 nm, 50 mW, continuous wave mode), and for EA at Neiguan, a Chinese system (Hanshi-100A; Nanjing Jisheng Medical Technology Company, China; 15 Hz, 1 mA). HR, HRV, and electrocorticogram were recorded using a biophysical amplifier AVB-10 (Nihon-Kohden, Japan). HR changed significantly during i.st. laser acupuncture stimulation of Neiguan in anesthetized rats. Total HRV increased insignificantly during i.v. and i.st. laser stimulation. The LF/HF ratio showed significant changes only during i.v. laser blood irradiation. Integrated cortical EEG (electrocorticogram) decreased insignificantly during EA and i.v. laser blood irradiation. Further studies concerning dosage-dependent alterations are in progress. PMID:23476681

  16. Role of solar UVB irradiance and smoking in cancer as inferred from cancer incidence rates by occupation in Nordic countries

    PubMed Central

    2012-01-01

    A large body of evidence indicates that solar ultraviolet-B (UVB) irradiance and vitamin D reduce the risk of incidence and death for many types of cancer. However, most of that evidence comes from midlatitude regions, where solar UVB doses are generally high in summer. Data on cancer standardized incidence ratios (SIRs) by sex and 54 occupation categories based on 1.4 million male and 1.36 million female cancer cases for 1961–2005 in the five Nordic countries provide the basis for an ecological study of the role of solar UVB in the risk of many types of cancer at high latitudes. Lip cancer SIRs less lung cancer SIRs for men was the best index of solar UVB dose, which was weakly inversely correlated with both melanoma and nonmelanoma skin cancer (NMSC) SIRs. Lung cancer SIRs were used as the index of the effects of smoking. For men, the UVB index was significantly inversely correlated with 14 types of internal cancer—bladder, breast, colon, gallbladder, kidney, laryngeal, liver, lung, oral, pancreatic, pharyngeal, prostate, rectal and small intestine cancer. For women, the same UVB index was inversely correlated with bladder, breast and colon cancer. These results generally agree with findings from other studies. These results provide more support for the UVB-vitamin D-cancer hypothesis and suggest that widespread fear of chronic solar ultraviolet (UV) irradiance may be misplaced. PMID:22928078

  17. Microchemical and microstructural evolution of AISI 304 stainless steel irradiated in EBR-II at PWR-relevant dpa rates

    NASA Astrophysics Data System (ADS)

    Dong, Y.; Sencer, B. H.; Garner, F. A.; Marquis, E. A.

    2015-12-01

    AISI 304 stainless steel was irradiated at 416 °C and 450 °C at a 4.4 × 10-9 and 3.05 × 10-7 dpa/s to ∼0.4 and ∼28 dpa, respectively, in the reflector of the EBR-II fast reactor. Both unirradiated and irradiated conditions were examined using standard and scanning transmission electron microscopy, energy dispersive spectroscopy, and atom probe tomography on very small specimens produced by focused ion beam milling. These results are compared with previous electron microscopy examination of 3 mm disks from essentially the same material. By comparing a very low dose specimen with a much higher dose specimen, both derived from a single reactor assembly, it has been demonstrated that the coupled microstructural and microchemical evolution of dislocation loops and other sinks begins very early, with elemental segregation producing at these sinks what appears to be measurable precursors to fully formed precipitates found at higher doses. The nature of these sinks and their possible precursors are examined in detail.

  18. Washout rate in rat brain irradiated by a 11C beam after acetazolamide loading using a small single-ring OpenPET prototype

    NASA Astrophysics Data System (ADS)

    Hirano, Yoshiyuki; Takuwa, Hiroyuki; Yoshida, Eiji; Nishikido, Fumihiko; Nakajima, Yasunori; Wakizaka, Hidekatsu; Yamaya, Taiga

    2016-03-01

    In dose verification techniques of particle therapies based on in-beam positron emission tomography (PET), the causes of washout of positron emitters by physiological effects should be clarified to correct washout for accurate verification. As well, the quantitative washout rate has a potential usefulness as a diagnostic index which should be explored. Therefore, we measured washout rates of rat brain after vasodilator acetazolamide loading to investigate the possible effects of blood flow on washout. Six rat brains were irradiated by a radioisotope 11C beam and time activity curves on the whole brains were obtained with a small single-ring OpenPET prototype. Then, washout rates were calculated with the Mizuno model, where two washout rates (k 2m and k 2s ) were assumed, and a two-compartment model including efflux from tissue to blood (k 2) and influx (k 3) and efflux (k 4) between the two tissue compartments. Before the irradiations, we used laser-Doppler flowmetry to confirm that acetazolamide increased cerebral blood flow (CBF) of a rat. We compared means of k 2m , k 2s and k 2, k 3 and k 4 without acetazolamide loading (Rest) and with acetazolamide loading (ACZ). For all k values, ACZ values were lower than Rest values. In other words, though CBF increased, washout rates were decreased. This may be attributed to the implanted 11C reacting to form 11CO2. Because acetazolamide increased the concentration of CO2 in brain, suppressed diffusion of 11CO2 and decomposition of 11CO2 into ions were prevented.

  19. Net carbon dioxide exchange rates and predicted growth patterns in Alstroemeria Jacqueline' at varying irradiances, carbon dioxide concentrations, and air temperatures

    SciTech Connect

    Leonardos, E.D.; Tsujita, M.J.; Grodzinski, B. . Dept. of Horticultural Science)

    1994-11-01

    The influence of irradiance, CO[sub 2] concentration, and air temperature on leaf and whole-plant net C exchange rate (NCER) of Alstroemeria Jacqueline' was studied. At ambient CO[sub 2], leaf net photosynthesis was maximum at irradiances above 600 [mu]mol[center dot]m[sup [minus]2][center dot]s[sup [minus]1] photosynthetically active radiation (PAR), while whole-plant NCER required 1,200 [mu]mol[center dot]m[sup [minus]2][center dot]s[sup [minus]1] PAR to be saturated. Leaf and whole-plant NCERs were doubled under CO[sub 2] enrichment of 1,500 to 2,000 [mu]l CO[sub 2]/liter. Leaf and whole-plant NCERs declined as temperature increased from 20 to 35 C. Whereas the optimum temperature range for leaf net photosynthesis was 17 to 23 C, whole-plant NCER, even at high light and high CO[sub 2], declined above 12 C. Dark respiration of leaves and whole plants increased with a Q[sub 10] of [approx] 2 at 15 to 35 C. In an analysis of day effects, irradiance, CO[sub 2] concentration, and temperature contributed 58%, 23%, and 14%, respectively, to the total variation in NCER explained by a second-order polynomial model (R[sup 2] = 0.85). Interactions among the factors accounted for 4% of the variation in day C assimilation. The potential whole-plant growth rates during varying greenhouse day and night temperature regimes were predicted for short- and long-day scenarios. The data are discussed with the view of designing experiments to test the importance of C gain in supporting flowering and high yield during routine harvest of Alstroemeria plants under commercial greenhouse conditions.

  20. Enhancing growth rate and lipid yield of Chlorella with nuclear irradiation under high salt and CO2 stress.

    PubMed

    Cheng, Jun; Lu, Hongxiang; Huang, Yun; Li, Ke; Huang, Rui; Zhou, Junhu; Cen, Kefa

    2016-03-01

    In order to produce biodiesel from microalgae cultured with abundant seawater, Chlorella sp. was mutated with (137)Se-γ ray irradiation and domesticated with f/2 seawater culture medium (salinity=3 wt.%) under 15 vol.% CO2 stress. Biomass yield of the mutant increased by 25% compared with wild species and lipid content increased to 54.9%. When nitrogen and phosphorus concentrations in the initial substrate increased, the increased propagation speed of the mutant resulted in decreased cell diameter by 26.6% and decreased cell wall thickness by 69.7%. The dramatically increased biomass yield of the mutant with sufficient initial substrate and relative nitrogen starvation in the later growth period with continuous 15 vol.% CO2 led to an increased lipid yield of 1.0 g/L. The long-chain unsaturated fatty acids increased, whereas short-chain saturated fatty acids decreased. PMID:26724554

  1. Adaptive response in embryogenesis: V. Existence of two efficient dose-rate ranges for 0.3 Gy of priming irradiation to adapt mouse fetuses.

    PubMed

    Wang, Bing; Ohyama, Harumi; Shang, Yi; Tanaka, Kaoru; Aizawa, Shiro; Yukawa, Osami; Hayata, Isamu

    2004-03-01

    The adaptive response is an important phenomenon in radiobiology. A study of the conditions essential for the induction of an adaptive response is of critical importance to understanding the novel biological defense mechanisms against the hazardous effects of radiation. In our previous studies, the specific dose and timing of radiation for induction of an adaptive response were studied in ICR mouse fetuses. We found that exposure of the fetuses on embryonic day 11 to a priming dose of 0.3 Gy significantly suppressed prenatal death and malformation induced by a challenging dose of radiation on embryonic day 12. Since a significant dose-rate effect has been observed in a variety of radiobiological phenomena, the effect of dose rate on the effectiveness of induction of an adaptive response by a priming dose of 0.3 Gy administered to fetuses on embryonic day 11 was investigated over the range from 0.06 to 5.0 Gy/min. The occurrence of apoptosis in limb buds, incidences of prenatal death and digital defects, and postnatal mortality induced by a challenging dose of 3.5 Gy given at 1.8 Gy/min to the fetuses on embryonic day 12 were the biological end points examined. Unexpectedly, effective induction of an adaptive response was observed within two dose-rate ranges for the same dose of priming radiation, from 0.18 to 0.98 Gy/ min and from 3.5 to 4.6 Gy/min, for reduction of the detrimental effect induced by a challenging dose of 3.5 Gy. In contrast, when the priming irradiation was delivered at a dose rate outside these two ranges, no protective effect was observed, and at some dose rates elevation of detrimental effects was observed. In general, neither a normal nor a reverse dose- rate effect was found in the dose-rate range tested. These results clearly indicated that the dose rate at which the priming irradiation was delivered played a crucial role in the induction of an adaptive response. This paper provides the first evidence for the existence of two dose-rate ranges

  2. Chromosome Damage and Cell Proliferation Rates in In Vitro Irradiated Whole Blood as Markers of Late Radiation Toxicity After Radiation Therapy to the Prostate

    SciTech Connect

    Beaton, Lindsay A.; Ferrarotto, Catherine; Marro, Leonora; Samiee, Sara; Malone, Shawn; Grimes, Scott; Malone, Kyle; Wilkins, Ruth C.

    2013-04-01

    Purpose: In vitro irradiated blood samples from prostate cancer patients showing late normal tissue damage were examined for lymphocyte response by measuring chromosomal aberrations and proliferation rate. Methods and Materials: Patients were selected from a randomized trial evaluating the optimal timing of dose-escalated radiation and short-course androgen deprivation therapy. Of 438 patients, 3% experienced grade 3 late radiation proctitis and were considered to be radiosensitive. Blood samples were taken from 10 of these patients along with 20 matched samples from patients with grade 0 proctitis. The samples were irradiated at 6 Gy and, along with control samples, were analyzed for dicentric chromosomes and excess fragments per cell. Cells in first and second metaphase were also enumerated to determine the lymphocyte proliferation rate. Results: At 6 Gy, there were statistically significant differences between the radiosensitive and control cohorts for 3 endpoints: the mean number of dicentric chromosomes per cell (3.26 ± 0.31, 2.91 ± 0.32; P=.0258), the mean number of excess fragments per cell (2.27 ± 0.23, 1.43 ± 0.37; P<.0001), and the proportion of cells in second metaphase (0.27 ± 0.10, 0.46 ± 0.09; P=.0007). Conclusions: These results may be a valuable indicator for identifying radiosensitive patients and for tailoring radiation therapy.

  3. Accelerated Partial Breast Irradiation With Low-Dose-Rate Interstitial Implant Brachytherapy After Wide Local Excision: 12-Year Outcomes From a Prospective Trial

    SciTech Connect

    Hattangadi, Jona A.; Powell, Simon N.; MacDonald, Shannon M.; Mauceri, Thomas; Ancukiewicz, Marek; Freer, Phoebe; Lawenda, Brian; Alm El-Din, Mohamed A.; Gadd, Michele A.; Smith, Barbara L.; Taghian, Alphonse G.

    2012-07-01

    Purpose: To evaluate the long-term toxicity, cosmesis, and local control of accelerated partial breast irradiation with implant brachytherapy after wide local excision for Stage T1N0 breast cancer (BCa). Materials and Methods: Between 1997 and 2001, 50 patients with Stage T1N0M0 BCa were treated in a Phase I-II protocol using low-dose-rate accelerated partial breast irradiation with implant brachytherapy after wide local excision and lymph node surgery. The total dose was escalated in three groups: 50 Gy (n = 20), 55 Gy (n = 17), and 60 Gy (n = 13). Patient- and physician-assessed breast cosmesis, patient satisfaction, toxicity, mammographic abnormalities, repeat biopsies, and disease status were prospectively evaluated at each visit. Kendall's tau ({tau}{sub {beta}}) and logistic regression analyses were used to correlate outcomes with dose, implant volume, patient age, and systemic therapy. Results: The median follow-up period was 11.2 years (range, 4-14). The patient satisfaction rate was 67%, 67% reported good-excellent cosmesis, and 54% had moderate-severe fibrosis. Higher dose was correlated with worse cosmetic outcome ({tau}{sub {beta}} 0.6, p < .0001), lower patient satisfaction ({tau}{sub {beta}} 0.5, p < .001), and worse fibrosis ({tau}{sub {beta}} 0.4, p = .0024). Of the 50 patients, 35% had fat necrosis and 34% developed telangiectasias {>=}1 cm{sup 2}. Grade 3-4 late skin and subcutaneous toxicities were seen in 4 patients (9%) and 6 patients (13%), respectively, and both correlated with higher dose ({tau}{sub {beta}} 0.3-0.5, p {<=} .01). One patient had Grade 4 skin ulceration and fat necrosis requiring surgery. Mammographic abnormalities were seen in 32% of the patients, and 30% underwent repeat biopsy, of which 73% were benign. Six patients had ipsilateral breast recurrence: five elsewhere in the breast, and one at the implant site. One patient died of metastatic BCa after recurrence. The 12-year actuarial local control, recurrence-free survival

  4. Degradation rates of benzotriazoles and benzothiazoles under UV-C irradiation and the advanced oxidation process UV/H2O2.

    PubMed

    Bahnmüller, Sabrina; Loi, Clara H; Linge, Kathryn L; Gunten, Urs von; Canonica, Silvio

    2015-05-01

    Benzotriazoles (BTs) and benzothiazoles (BTHs) are extensively used chemicals found in a wide range of household and industrial products. They are chemically stable and are therefore ubiquitous in the aquatic environment. The present study focuses on the potential of ultraviolet (UV) irradiation, alone or in combination with hydrogen peroxide (H2O2), to remove BTs and BTHs from contaminated waters. Six compounds, three out of each chemical class, were investigated using a low-pressure mercury lamp (main emission at 254 nm) as the radiation source. Initially, the direct phototransformation kinetics and quantum yield in dilute aqueous solution was studied over the pH range of 4-12. All BTs and BTHs, except for benzothiazole, exhibited pH-dependent direct phototransformation rate constants and quantum yields in accordance to their acid-base speciation (7.1 < pKa < 8.9). The direct phototransformation quantum yields (9.0 × 10(-4)-3.0 × 10(-2) mol einstein(-1)), as well as the photon fluence-based rate constants (1.2-48 m(2) einstein(-1)) were quite low. This suggests that UV irradiation alone is not an efficient method to remove BTs and BTHs from impacted waters. The second-order rate constants for the reaction of selected BTs and BTHs with the hydroxyl radical were also determined, and found to fall in the range of 5.1-10.8 × 10(9) M(-1) s(-1), which is typical for aromatic contaminants. Finally, the removal of BTs and BTHs was measured in wastewater and river water during application of UV irradiation or the advanced oxidation process UV/H2O2. The latter process provided an efficient removal, mostly due to the effect of the hydroxyl radical, that was comparable to other aromatic aquatic contaminants, in terms of energy requirement or treatment costs. PMID:25725202

  5. Effect of Dose Rate on Residual γ-H2AX Levels and Frequency of Micronuclei in X-Irradiated Mouse Lymphocytes

    PubMed Central

    Turner, H. C.; Shuryak, I.; Taveras, M.; Bertucci, A.; Perrier, J. R.; Chen, C.; Elliston, C. D.; Johnson, G. W.; Smilenov, L. B.; Amundson, S. A.; Brenner, D. J.

    2015-01-01

    The biological risks associated with low-dose-rate (LDR) radiation exposures are not yet well defined. To assess the risk related to DNA damage, we compared the yields of two established biodosimetry end points, γ-H2AX and micronuclei (MNi), in peripheral mouse blood lymphocytes after prolonged in vivo exposure to LDR X rays (0.31 cGy/min) vs. acute high-dose-rate (HDR) exposure (1.03 Gy/min). C57BL/6 mice were total-body irradiated with 320 kVP X rays with doses of 0, 1.1, 2.2 and 4.45 Gy. Residual levels of total γ-H2AX fluorescence in lymphocytes isolated 24 h after the start of irradiation were assessed using indirect immunofluorescence methods. The terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was used to determine apoptotic cell frequency in lymphocytes sampled at 24 h. Curve fitting analysis suggested that the dose response for γ-H2AX yields after acute exposures could be described by a linear dependence. In contrast, a linear-quadratic dose-response shape was more appropriate for LDR exposure (perhaps reflecting differences in repair time after different LDR doses). Dose-rate sparing effects (P < 0.05) were observed at doses ≤2.2 Gy, such that the acute dose γ-H2AX and TUNEL-positive cell yields were significantly larger than the equivalent LDR yields. At the 4.45 Gy dose there was no difference in γ-H2AX expression between the two dose rates, whereas there was a two- to threefold increase in apoptosis in the LDR samples compared to the equivalent 4.45 Gy acute dose. Micronuclei yields were measured at 24 h and 7 days using the in vitro cytokinesis-blocked micronucleus (CBMN) assay. The results showed that MNi yields increased up to 2.2 Gy with no further increase at 4.45 Gy and with no detectable dose-rate effect across the dose range 24 h or 7 days post exposure. In conclusion, the γ-H2AX biomarker showed higher sensitivity to measure dose-rate effects after low-dose LDR X rays compared to MNi formation; however

  6. High-dose total-body irradiation and autologous marrow reconstitution in dogs: dose-rate-related acute toxicity and fractionation-dependent long-term survival

    SciTech Connect

    Deeg, H.J.; Storb, R.; Weiden, P.L.; Schumacher, D.; Shulman, H.; Graham, T.; Thomas, E.D.

    1981-11-01

    Beagle dogs treated by total-body irradiation (TBI) were given autologous marrow grafts in order to avoid death from marrow toxicity. Acute and delayed non-marrow toxicities of high single-dose (27 dogs) and fractionated TBI (20 dogs) delivered at 0.05 or 0.1 Gy/min were compared. Fractionated TBI was given in increments of 2 Gy every 6 hr for three increments per day. Acute toxicity and early mortality (<1 month) at identical total irradiation doses were comparable for dogs given fractionated or single-dose TBI. With single-dose TBI, 14, 16, and 18 Gy, respectively, given at 0.05 Gy/min, 0/5, 5/5, and 2/2 dogs died from acute toxicity; with 10, 12, and 14 Gy, respectively, given at 0.1 Gy/min, 1/5, 4/5, and 5/5 dogs died acutely. With fractionated TBI, 14 and 16 Gy, respectively, given at 0.1 Gy/min, 1/5, 4/5, and 2/2 dogs died auctely. Early deaths were due to radiation enteritis with or without associated septicemia (29 dogs; less than or equal to Day 10). Three dogs given 10 Gy of TBI at 0.1 Gy/min died from bacterial pneumonia; one (Day 18) had been given fractionated and two (Days 14, 22) single-dose TBI. Fifteen dogs survived beyond 1 month; eight of these had single-dose TBI (10-14 Gy) and all died within 7 months of irradiation from a syndrome consisting of hepatic damage, pancreatic fibrosis, malnutrition, wasting, and anemia. Seven of the 15 had fractionated TBI, and only one (14 Gy) died on Day 33 from hepatic failure, whereas 6 (10-14 Gy) are alive and well 250 to 500 days after irradiation. In conclusion, fractionated TBI did not offer advantages over single-dose TBI with regard to acute toxicity and early mortality; rather, these were dependent upon the total dose of TBI. The total acutely tolerated dose was dependent upon the exposure rate; however, only dogs given fractionated TBI became healthy long-term survivors.

  7. Screening of lipases for the synthesis of xylitol monoesters by chemoenzymatic esterification and the potential of microwave and ultrasound irradiations to enhance the reaction rate.

    PubMed

    Rufino, Alessandra R; Biaggio, Francisco C; Santos, Julio C; de Castro, Heizir F

    2010-07-01

    Lipases from different sources, Pseudomonas fluorescens (AK lipase), Burkholderia cepacia (PS lipase), Penicillium camembertii (lipase G) and Porcine pancreas lipase (PPL), previously immobilized on epoxy SiO(2)-PVA, were screened for the synthesis of xylitol monoesters by esterification of the protected xylitol using oleic acid as acyl donor group. Among all immobilized derivatives, the highest esterification yield was achieved by P. camembertii lipase, showing to be attractive alternative to bulk chemical routes to satisfy increasing commercial demands. Further experiments were performed to determine the influence of fatty acids chain size on the reaction yield and the feasibility of using non-conventional heating systems (microwave and ultrasound irradiations) to enhance the reaction rate. PMID:20420851

  8. The Contribution of Tissue Level Organization to Genomic Stability Following Low Dose/Low Dose Rate Gamma and Proton Irradiation

    SciTech Connect

    Cheryl G. Burrell, Ph.D.

    2012-05-14

    The formation of functional tissue units is necessary in maintaining homeostasis within living systems, with individual cells contributing to these functional units through their three-dimensional organization with integrin and adhesion proteins to form a complex extra-cellular matrix (ECM). This is of particular importance in those tissues susceptible to radiation-induced tumor formation, such as epithelial glands. The assembly of epithelial cells of the thyroid is critical to their normal receipt of, and response to, incoming signals. Traditional tissue culture and live animals present significant challenges to radiation exposure and continuous sampling, however, the production of bioreactor-engineered tissues aims to bridge this gap by improve capabilities in continuous sampling from the same functional tissue, thereby increasing the ability to extrapolate changes induced by radiation to animals and humans in vivo. Our study proposes that the level of tissue organization will affect the induction and persistence of low dose radiation-induced genomic instability. Rat thyroid cells, grown in vitro as 3D tissue analogs in bioreactors and as 2D flask grown cultures were exposed to acute low dose (1, 5, 10 and 200 cGy) gamma rays. To assess immediate (6 hours) and delayed (up to 30 days) responses post-irradiation, various biological endpoints were studied including cytogenetic analyses, apoptosis analysis and cell viability/cytotoxicity analyses. Data assessing caspase 3/7 activity levels show that, this activity varies with time post radiation and that, overall, 3D cultures display more genomic instability (as shown by the lower levels of apoptosis over time) when compared to the 2D cultures. Variation in cell viability levels were only observed at the intermediate and late time points post radiation. Extensive analysis of chromosomal aberrations will give further insight on the whether the level of tissue organization influences genomic instability patterns after

  9. Proteomic analysis of Spirogyra varians mutant with high starch content and growth rate induced by gamma irradiation.

    PubMed

    Yoon, Minchul; Choi, Jong-il; Kim, Gwang Hoon; Kim, Dong-Ho; Park, Don-Hee

    2013-06-01

    This study was conducted to develop a high-efficiency strain of Spirogyra varians for the production of biomass by radiation breeding. The characteristics of wild-type and mutant S. varians were analyzed through phenomenological and proteomic observations. The results of our phenomenological observations of the S. varians mutant demonstrated increases in growth rate and content of chlorophyll a, b, and a + b; in particular, a significant threefold increase was observed in starch accumulation. Proteomic analysis to investigate the differences in expression between wild-type and mutant proteins identified 18 proteins with significantly different expressions. From the literature review, it was confirmed that the up-regulated proteins were mainly involved in photosynthesis, carbohydrate biosynthesis, and energy metabolism. These results suggest the possibility of algae development by radiation breeding for the production of biofuel. PMID:23370702

  10. Efficient rotational echo double resonance recoupling of a spin-1/2 and a quadrupolar spin at high spinning rates and weak irradiation fields

    NASA Astrophysics Data System (ADS)

    Nimerovsky, Evgeny; Goldbourt, Amir

    2010-09-01

    A modification of the rotational echo (adiabatic passage) double resonance experiments, which allows recoupling of the dipolar interaction between a spin-1/2 and a half integer quadrupolar spin is proposed. We demonstrate efficient and uniform recoupling at high spinning rates ( ν r), low radio-frequency (RF) irradiation fields ( ν1), and high values of the quadrupolar interaction ( ν q) that correspond to values of α=ν12/νqνr, the adiabaticity parameter, which are down to less than 10% of the traditional adiabaticity limit for a spin-5/2 (α = 0.55). The low-alpha rotational echo double resonance curve is obtained when the pulse on the quadrupolar nucleus is extended to full two rotor periods and beyond. For protons (spin-1/2) and aluminum (spin-5/2) species in the zeolite SAPO-42, a dephasing curve, which is significantly better than the regular REAPDOR experiment (pulse length of one-third of the rotor period) is obtained for a spinning rate of 13 kHz and RF fields down to 10 and even 6 kHz. Under these conditions, α is estimated to be approximately 0.05 based on an average quadrupolar coupling in zeolites. Extensive simulations support our observations suggesting the method to be robust under a large range of experimental values.

  11. Systematic Study Related to the Role of Initial Impurities and Irradiation Rates in the Formation and Evolution of Complex Defects in Silicon for Detectors in HEP Experiments

    NASA Astrophysics Data System (ADS)

    Lazanu, S.; Lazanu, I.

    The influence of oxygen and carbon impurities on the concentrations of defects in silicon for detector uses, in complex fields of radiation, characteristic to high energy physics experiments, is investigated in the frame of the quantitative phenomenological model developed previously by the authors and extended in the present paper. Continuous irradiation conditions are considered, simulating realistically the environments for these experiments. The generation rate of primary defects is calculated starting from the projectile-silicon interaction and from the recoil energy redistribution in the lattice. The mechanisms of formation of complex defects are explicitly analysed. Vacancy-interstitial annihilation, interstitial and vacancy migration to sinks, divacancy, vacancy- and interstitial-impurity complex formation and decomposition are considered. Oxygen and carbon impurities present in silicon could monitor the concentration of all stable defects, due to their interaction with vacancies and interstitials. Their role in the mechanisms of formation and decomposition of the following stable defects: V2, VO, V2O, Ci, CiOi, CiCs and VP, is studied. The model predictions cover a generation rate of primary defects between 102 pairs/cm3/s and 1011 pairs/cm3/s, and could be a useful clue in obtaining harder materials for detectors for space missions, at the new generation of accelerators, as, e.g. LHC, Super-LHC and Eloisatron, or for industrial applications.

  12. Accelerated partial breast irradiation: An analysis of variables associated with late toxicity and long-term cosmetic outcome after high-dose-rate interstitial brachytherapy

    SciTech Connect

    Wazer, David E. . E-mail: dwazer@tufts-nemc.org; Kaufman, Seth; Cuttino, Laurie; Di Petrillo, Thomas; Arthur, Douglas W.

    2006-02-01

    Purpose: To perform a detailed analysis of variables associated with late tissue effects of high-dose-rate (HDR) interstitial brachytherapy accelerated partial breast irradiation (APBI) in a large cohort of patients with prolonged follow-up. Methods and Materials: Beginning in 1995, 75 women with Stage I/II breast cancer were enrolled in identical institutional trials evaluating APBI as monotherapy after lumpectomy. Patients eligible included those with T1-2, N0-1 ({<=}3 nodes positive), M0 tumors of nonlobular histology with negative surgical margins, no extracapsular nodal extension, and negative results on postexcision mammogram. All patients underwent surgical excision and postoperative irradiation with HDR interstitial brachytherapy. The planning target volume was defined as the excision cavity plus a 2-cm margin. Treatment was delivered with a high-activity Ir-192 source at 3.4 Gy per fraction twice daily for 5 days to a total dose of 34 Gy. Dosimetric analyses were performed with three-dimensional postimplant dose and volume reconstructions. All patients were evaluated at 3-6-month intervals and assessed with a standardized cosmetic rating scale and according to Radiation Therapy Oncology Group late normal tissue toxicity scoring criteria. Clinical and therapy-related features were analyzed for their relationship to cosmetic outcome and toxicity rating. Clinical features analyzed included age, volume of resection, history of diabetes or hypertension, extent of axillary surgery, and systemic therapies. Therapy-related features analyzed included volume of tissue encompassed by the 100%, 150%, and 200% isodose lines (V100, V150, and V200, respectively), the dose homogeneity index (DHI), number of source dwell positions, and planar separation. Results: The median follow-up of all patients was 73 months (range, 43-118 months). The cosmetic outcome at last follow-up was rated as excellent, good, and fair/poor in 67%, 24%, and 9% of patients, respectively

  13. Quality of platelet concentrates irradiated with UVB light: effect of UV dose and dose rate on glycocalicin release and correlation with other markers of the platelet storage lesion.

    PubMed

    Bessos, H; Murphy, W G; Robertson, A; Vickers, M; Seghatchian, M J; Tandy, N P; Cutts, M; Pamphilon, D H

    1993-06-01

    The amount of membrane-associated glycoprotein Ib in platelet concentrates (PCs) irradiated with a high dose of UVB light has been shown to be significantly reduced after 48 h storage. We recently corroborated this finding when we noted an increase in the supernatant levels of glycocalicin (GC, a major segment of glycoprotein Ib) in UVB-treated PCs during storage. The aim of the present study was to determine whether GC release was related to both the UV dose and the rate of dose delivery. Plateletpheresis concentrates obtained from five donors were pooled and split into five equal parts. Four of these were treated with 7500 and 15,000 mJ/cm2 UVB using two prototype UV sources with differing rates of dose delivery; namely, Baxter (BAT) and British Aerospace (BAC) cabinets, with the latter having the slower rate of delivery. On days 1 and 5 of storage, GC levels in the supernatants of PCs were determined by ELISA. Moreover, the following parameters were also assessed: platelet and WBC count; hypotonic shock response (HSR) and platelet aggregation response to ADP, ADP+collagen, ADP+arachidonic acid and ristocetin; pH; supernatant levels of lactate, glucose, von Willebrand factor (vWf) and beta-thromboglobulin (beta TG). The results revealed an association of GC release with UVB dose using both UV sources, although this was more apparent in the BAC system, in which glycocalicin release at day 5 of storage was as follows (microgram/ml, mean +/- SD): 4.8 +/- 0.3 and 9.5 +/- 3.6 at 7500 and 15,000 mJ/cm2 respectively.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8374699

  14. Microstructure and mechanical properties of austenitic stainless steel 12X18H9T after neutron irradiation in the pressure vessel of BR-10 fast reactor at very low dose rates

    NASA Astrophysics Data System (ADS)

    Porollo, S. I.; Dvoriashin, A. M.; Konobeev, Yu. V.; Ivanov, A. A.; Shulepin, S. V.; Garner, F. A.

    2006-12-01

    Results are presented for void swelling, microstructure and mechanical properties of Russian 12X18H9T (0.12C-18Cr-9Ni-Ti) austenitic stainless steel irradiated as a pressure vessel structural material of the BR-10 fast reactor at ˜350 °C to only 0.64 dpa, produced by many years of exposure at the very low displacement rate of only 1.9 × 10 -9 dpa/s. In agreement with a number of other recent studies it appears that lower dpa rates have a pronounced effect on the microstructure and resultant mechanical properties. In general, lower dpa rates lead to the onset of swelling at much lower doses compared to comparable irradiations conducted at higher dpa rates.

  15. Microstructure and mechanical properties of austenitic stainless steel 12X18H9T after neutron irradiation in the pressure vessel of BR-10 fast reactor at very low dose rates

    SciTech Connect

    Porollo, S. I.; Dvoriashin, Alexander M.; Konobeev, Yury V.; Ivanov, A. A.; Shulepin, S. V.; Garner, Francis A.

    2006-12-01

    Results are presented for void swelling, microstructure andmechanical properties of Russian 12X18H9T (0.12C-18Cr-9Ni-Ti) austenitic stainless steel irradiated as a pressure vessel structure material of the BR-10 fast reactor at ~350C to only 0.64 dpa, produced by many years of exposure at the very low displacement rate of only 1.9x10-9 dpa/s. In agreement with a number of other recent studies it appears that lower dpa rates have a pronounced effect on the microstructure and resultant mechanical properties. In general, loweer dpa rates lead to the onset of swelling at much lower doses compared to comparable irradiations conducted at higher dpa rates.

  16. [Searching Radiation Countermeasures using the Model of Prolonged Irradiation of Mice with Low Dose Rate and Evaluation of Their Influence on Heat Shock Protein Genes Expression].

    PubMed

    Rozhdestvensky, L M; Mikhailov, V F; Schlyakova, T G; Shagirova, J M; Shchegoleva, R A; Raeva, N F; Lisina, N I; Shulenina, L V; Zorin, V V; Pchelka, A V; Trubitsina, K Y

    2015-01-01

    Different radiomodificators (cytokine betaleukine, antioxidant phenoxan, antigipoksant limontar and nucleoside riboxin) were investigated on mice for evaluating their radiation protective capacity against prolonged (21 h) exposure at a dose of 12.6 Gy at a low dose rate of 10 mGy/min. Bone marrow cellularity and endogenic CFUs were used as evaluation criteria 9 days after exposure. Simultaneously, expression of the heat shock proteins of 25, 70 and 90 kDa in unexposed mice bone marrow was studied 2, 24 and 48 h after injections. Betaleukine only had a positive significant effect in both tests in the variants of 50 mcg/kg and 3 mcg/kg when administered 2 h and 22 h before exposure, correspondingly. Effects of betaleukine HSPs on expression were both stimulating and inhibiting, that was in contradiction with a constant positive effect in 5 experiments on exposed mice for each betaleukine variant. It argues against the vital role of HSPs in the betaleukine antiradiation effect. In 2 experiments with high temperatures betaleukine administered at a dose of 50 mcg/kg evoked a very high HSP-70 gene expression after 24 h, and mice exposed to irradiation at that time in a parallel experiment showed an increased radiation effect. It corresponds to the idea that HSPs serve a stress indicator. PMID:26601542

  17. Release of K+ and H+ from poly U in aqueous solution upon gamma and electron irradiation. Rate of strand break formation in poly U.

    PubMed

    Bothe, E; Schulte-Frohlinde, D

    1982-01-01

    Conductivity changes were found which followed the reaction of radiolytically generated OH radicals with the potassium salt of polyuridylic acid (poly U) in aqueous solution. After 60Co-gamma-irradiation the observed increase of conductivity at pH = 6.8 was shown to consist of the liberation of K+ ions from the stock of K+ ions electrostatically bound to the polyanion. The initial G(K+) is 36 and hence 6 times higher than the G value of OH radicals in N2O saturated solutions. At a poly U concentration of 60 mg l-1 half of the ion release occurred at 12 J kg-1 and nearly all ions are released at 40 J kg-1. The liberation of K+ is explained to be a consequence of the formation of chain breaks leading to an increase of the degree of dissociation. The rate of the ion release was studied under pulse radiolysis conditions. Because of the high G-value of counterion liberation and the use of conductivity as analytical quantity the method is very sensitive. With 6 mg l-1 poly U the rate could be measured even at a dose per pulse of 0.25 J kg-1. The kinetics of the ion release can be described in terms of two parallel first order reactions of comparable contribution with an average rate constant of 0.8 s-1 at 20 degrees C, 60 mg l-1 poly U and pH = 6.8 with a small contribution of slower components. In more acidic solutions, besides K+ ions H+ are also liberated since at low pH values bound K+ is replaced by H+. The rate of the ion release was found to increase with increasing replacement of K+ by H+ (kobs = 100 s-1 at pH = 3.4, 60 mg l-1 poly U and T = 18 degrees C). With potassium ion free polyuridylic acid the corresponding rate constant amounted to 220 s-1, nearly independent of pH. From the temperature dependence activation parameters for the ion release were derived (Ea = 57 kJ mol-1, A = 1.0 X 10(10) s-1 at pH = 6.8). Addition of p-benzoquinone at pH = 3.7 and dithiothreitol (DTT) at pH 6.8 were found to decrease the size of the conductivity changes and to increase

  18. Impact of Prophylactic Cranial Irradiation Timing on Brain Relapse Rates in Patients With Stage IIIB Non-Small-Cell Lung Carcinoma Treated With Two Different Chemoradiotherapy Regimens

    SciTech Connect

    Topkan, Erkan; Parlak, Cem; Kotek, Ayse; Yuksel, Oznur; Cengiz, Mustafa; Ozsahin, Mahmut; Pehlivan, Berrin

    2012-07-15

    Purpose: To retrospectively assess the influence of prophylactic cranial irradiation (PCI) timing on brain relapse rates in patients treated with two different chemoradiotherapy (CRT) regimens for Stage IIIB non-small-cell lung cancer (NSCLC). Methods and Materials: A cohort of 134 patients, with Stage IIIB NSCLC in recursive partitioning analysis Group 1, was treated with PCI (30 Gy at 2 Gy/fr) following one of two CRT regimens. Regimen 1 (n = 58) consisted of three cycles of induction chemotherapy (ICT) followed by concurrent CRT (C-CRT). Regimen 2 (n = 76) consisted of immediate C-CRT during thoracic radiotherapy. Results: At a median follow-up of 27.6 months (range, 7.2-40.4), 65 patients were alive. Median, progression-free, and brain metastasis-free survival (BMFS) times for the whole study cohort were 23.4, 15.4, and 23.0 months, respectively. Median survival time and the 3-year survival rate for regimens 1 and 2 were 19.3 vs. 26.1 months (p = 0.001) and 14.4% vs. 34.4% (p < .001), respectively. Median time from the initiation of primary treatment to PCI was 123.2 (range, 97-161) and 63.4 (range, 55-74) days for regimens 1 and 2, respectively (p < 0.001). Overall, 11 (8.2%) patients developed brain metastasis (BM) during the follow-up period: 8 (13.8%) in regimen 1 and 3 (3.9%) in regimen 2 (p = 0.03). Only 3 (2.2%) patients developed BM at the site of first failure, and for 2 of them, it was also the sole site of recurrence. Median BMFS for regimens 1 and 2 were 17.4 (13.5-21.3) vs. 26.0 (22.9-29.1 months), respectively (p < 0.001). Conclusion: These results suggest that in Stage IIIB NSCLC patients treated with PCI, lower BM incidence and longer survival rates result from immediate C-CRT rather than ITC-first regimens. This indicates the benefit of earlier PCI use without delay because of induction protocols.

  19. Factors for Predicting Rectal Dose of High-Dose-Rate Intracavitary Brachytherapy After Pelvic Irradiation in Patients With Cervical Cancer: A Retrospective Study With Radiography-Based Dosimetry

    SciTech Connect

    Huang Engyen; Wang Chongjong; Lan Jenhong; Chen Huichun; Fang Fumin; Hsu, H.-C.; Huang Yujie; Wang Changyu; Wang Yuming

    2010-02-01

    Purpose: To evaluate the predictive factors for rectal dose of the first fraction of high-dose-rate intracavitary brachytherapy (HDR-ICBT) in patients with cervical cancer. Methods and Materials: From March 1993 through February 2008, 946 patients undergoing pelvic irradiation and HDR-ICBT were analyzed. Examination under anesthesia (EUA) at the first implantation of the applicator was usually performed in the early period. Rectal point was determined radiographically according to the 38th Report of the International Commission of Radiation Units and Measurements (ICRU). The ICRU rectal dose (PRD) as a percentage of point A dose was calculated; multiple linear regression models were used to predict PRD. Results: Factors influencing successful rectal dose calculation were EUA (p < 0.001) and absence of diabetes (p = 0.047). Age (p < 0.001), body weight (p = 0.002), diabetes (p = 0.020), and EUA (p < 0.001) were independent factors for the PRD. The predictive equation derived from the regression model was PRD (%) = 57.002 + 0.443 x age (years) - 0.257 x body weight (kg) + 6.028 x diabetes (no: 0; yes: 1) - 8.325 x EUA (no: 0; yes: 1) Conclusion: Rectal dose at the first fraction of HDR-ICBT is positively influenced by age and diabetes, and negatively correlated with EUA and body weight. A small fraction size at point A may be considered in patients with a potentially high rectal dose to reduce the biologically effective dose if the ICRU rectal dose has not been immediately obtained in the first fraction of HDR-ICBT.

  20. A master curve-mechanism based approach to modeling the effects of constraint, loading rate and irradiation on the toughness-temperature behavior of a V-4Cr-4Ti alloy

    SciTech Connect

    Odette, G.R.; Donahue, E.; Lucas, G.E.; Sheckherd, J.W.

    1996-10-01

    The influence of loading rate and constraint on the effective fracture toughness as a function of temperature [K{sub e}(T)] of the fusion program heat of V-4Cr-4Ti was measured using subsized, three point bend specimens. The constitutive behavior was characterized as a function of temperature and strain rate using small tensile specimens. Data in the literature on this alloy was also analysed to determine the effect of irradiation on K{sub e}(T) and the energy temperature (E-T) curves measured in subsized Charpy V-notch tests. It was found that V-4Cr-4Ti undergoes {open_quotes}normal{close_quotes} stress-controlled cleavage fracture below a temperature marking a sharp ductile-to-brittle transition. The transition temperature is increased by higher loading rates, irradiation hardening and triaxial constraint. Shifts in a reference transition temperature due to higher loading rates and irradiation can be reasonably predicted by a simple equivalent yield stress model. These results also suggest that size and geometry effects, which mediate constraint, can be modeled by combining local critical stressed area {sigma}*/A* fracture criteria with finite element method simulations of crack tip stress fields. The fundamental understanding reflected in these models will be needed to develop K{sub e}(T) curves for a range of loading rates, irradiation conditions, structural size scales and geometries relying (in large part) on small specimen tests. Indeed, it may be possible to develop a master K{sub e}(T) curve-shift method to account for these variables. Such reliable and flexible failure assessment methods are critical to the design and safe operation of defect tolerant vanadium structures.

  1. Far-UV Spectroscopy of the Planet-hosting Star WASP-13: High-energy Irradiance, Distance, Age, Planetary Mass-loss Rate, and Circumstellar Environment

    NASA Astrophysics Data System (ADS)

    Fossati, L.; France, K.; Koskinen, T.; Juvan, I. G.; Haswell, C. A.; Lendl, M.

    2015-12-01

    Several transiting hot Jupiters orbit relatively inactive main-sequence stars. For some of those, the {log}{R}{HK}\\prime activity parameter lies below the basal level (-5.1). Two explanations have been proposed so far: (i) the planet affects the stellar dynamo, (ii) the {log}{R}{HK}\\prime measurements are biased by extrinsic absorption, either by the interstellar medium (ISM) or by material local to the system. We present here Hubble Space Telescope/COS far-UV spectra of WASP-13, which hosts an inflated hot Jupiter and has a measured {log}{R}{HK}\\prime value (-5.26), well below the basal level. From the star's spectral energy distribution we obtain an extinction E(B - V) = 0.045 ± 0.025 mag and a distance d = 232 ± 8 pc. We detect at ≳4σ lines belonging to three different ionization states of carbon (C i, C ii, and C iv) and the Si iv doublet at ˜3σ. Using far-UV spectra of nearby early G-type stars of known age, we derive a C iv/C i flux ratio-age relation, from which we estimate WASP-13's age to be 5.1 ± 2.0 Gyr. We rescale the solar irradiance reference spectrum to match the flux of the C iv 1548 doublet. By integrating the rescaled solar spectrum, we obtain an XUV flux at 1 AU of 5.4 erg s-1 cm-2. We use a detailed model of the planet's upper atmosphere, deriving a mass-loss rate of 1.5 × 1011 g s-1. Despite the low {log}{R}{HK}\\prime value, the star shows a far-UV spectrum typical of middle-aged solar-type stars, pointing toward the presence of significant extrinsic absorption. The analysis of a high-resolution spectrum of the Ca ii H&K lines indicates that the ISM absorption could be the origin of the low {log}{R}{HK}\\prime value. Nevertheless, the large uncertainty in the Ca ii ISM abundance does not allow us to firmly exclude the presence of circumstellar gas. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from MAST at the Space Telescope Science Institute, which is operated by the Association of Universities for

  2. SEU measurements using /sup 252/CF fission particles, on CMOS static RAMS, subjected to a continuous period of low dose rate /sup 60/CO irradiation

    SciTech Connect

    Sanderson, T.K.; Mapper, D.; Stephen, J.H.; Farren, J.; Adams, L.; Harboe-Sorensen, R.

    1987-12-01

    SEU measurements have been made on a number of CMOS static RAMs over a period of eight months while they were being continuously irradiated with /sup 60/Co gamma rays. The results are discussed and compared with those of other workers using different methods.

  3. Simplified quantification of labile proton concentration-weighted chemical exchange rate (kws) with RF saturation time dependent ratiometric analysis (QUESTRA) - Normalization of relaxation and RF irradiation spillover effects for improved quantitative chemical exchange saturation transfer (CEST) MRI

    PubMed Central

    Sun, Phillip Zhe

    2012-01-01

    Chemical exchange saturation transfer (CEST) MRI is an emerging imaging technique capable of detecting dilute proteins/peptides and microenvironmental properties, with promising in vivo applications. However, CEST MRI contrast is complex, varying not only with the labile proton concentration and exchange rate, but also with experimental conditions such as field strength and RF irradiation scheme. Furthermore, the optimal RF irradiation power depends on the exchange rate, which must be estimated in order to optimize the CEST MRI experiments. Although methods including numerical fitting with modified Bloch-McConnell equations, quantification of exchange rate with RF saturation time and power (QUEST and QUESP), have been proposed to address this relationship, they require multiple-parameter non-linear fitting and accurate relaxation measurement. Our work here extended the QUEST algorithm with ratiometric analysis (QUESTRA) that normalizes the magnetization transfer ratio (MTR) at labile and reference frequencies, which effectively eliminates the confounding relaxation and RF spillover effects. Specifically, the QUESTRA contrast approaches its steady state mono-exponentially at a rate determined by the reverse exchange rate (kws), with little dependence on bulk water T1, T2, RF power and chemical shift. The proposed algorithm was confirmed numerically, and validated experimentally using a tissue-like phantom of serially titrated pH compartments. PMID:21842497

  4. Influence of random point defects introduced by proton irradiation on the flux creep rates and magnetic field dependence of the critical current density J c of co-evaporated GdBa2Cu3O7-δ coated conductors

    NASA Astrophysics Data System (ADS)

    Haberkorn, N.; Kim, Jeehoon; Suárez, S.; Lee, Jae-Hun; Moon, S. H.

    2015-12-01

    We report the influence of random point defects introduced by 3 MeV proton irradiation (doses of 0.5 × 1016, 1 × 1016, 2 × 1016 and 6 × 1016 cm-2) on the vortex dynamics of co-evaporated 1.3 μm thick, GdBa2Cu3O7-δ coated conductors. Our results indicate that the inclusion of additional random point defects reduces the low field and enhances the in-field critical current densities J c. The main in-field J c enhancement takes place below 40 K, which is in agreement with the expectations for pinning by random point defects. In addition, our data show a slight though clear increase in flux creep rates as a function of irradiation fluence. Maley analysis indicates that this increment can be associated with a reduction in the exponent μ characterizing the glassy behavior.

  5. Photoionization of isooctane and n-octane in intense laser fields: The effect of irradiance on ionization rates and electron dynamics

    NASA Astrophysics Data System (ADS)

    Healy, Andrew T.

    Thin path length jets (60 mum) of liquid isooctane and n-octane have been photoionized with 36-70 fs pulses of 3.1 eV photons. The population of electrons ejected post ionization is investigated over a large range of ionizing irradiance, Iex, though transient absorption (TA) measurements at wavelengths in the range 570 nm (2.17 eV) to 1315 nm (0.94 eV). As Iex is varied over a range from 3 TW/cm2 to 410 TW/cm2, the dependence of the TA intensity on Iex at time delays 0.7 ps and 2.5 ps exhibits the periodic structure theoretically predicted to develop as a result of multiphoton channel closings. At low Iex (< 9 TW/cm2), TA intensity in isooctane is proportional to Inex where n = 3, consistent with non-resonant, near threshold ionization (liquid phase ionization potential = 8.6 eV). At I ex > 9 TW/cm2, n declines with increasing Iex up to Iex = 13 TW/cm2, at which point n abruptly increases to 4. The pattern is repeated at Iex > 13 TW/cm 2, albeit with n declining from 4 and then abruptly increasing to 5 as Iex becomes greater than 100 TW/cm2. A similar trend is observed in n-octane. The decay of the TA intensity in both liquids has been measured from 0.50 ps to 180 ps over the same range of irradiance. Via comparison of the two liquids, and electron quenching studies, the TA at wavelengths longer than 800 nm has been assigned to be predominantly due to absorption by the electron. At the lowest irradiances, where n = 3 photons are required for photoionization, the TA decay in isooctane is characteristic of a geminate ion pair decaying via diffusive recombination in a Coulomb field. As the irradiance is increased, an early time, rapid, exponential decay of the TA begins to develop until an irradiance is reached (≅ 13 TW/cm2) at which our studies indicate that the n = 3 channel closes. At this irradiance, the TA decay returns to purely diffusive-like. As the irradiance is further increased, there is a reappearance of the early time exponential decay until the n = 4

  6. Optimal moderator materials at various proton energies considering photon dose rate after irradiation for an accelerator-driven ⁹Be(p, n) boron neutron capture therapy neutron source.

    PubMed

    Hashimoto, Y; Hiraga, F; Kiyanagi, Y

    2015-12-01

    We evaluated the accelerator beam power and the neutron-induced radioactivity of (9)Be(p, n) boron neutron capture therapy (BNCT) neutron sources having a MgF2, CaF2, or AlF3 moderator and driven by protons with energy from 8 MeV to 30 MeV. The optimal moderator materials were found to be MgF2 for proton energies less than 10 MeV because of lower required accelerator beam power and CaF2 for higher proton energies because of lower photon dose rate at the treatment position after neutron irradiation. PMID:26272165

  7. Laser stand for irradiation of targets by laser pulses from the Iskra-5 facility at a repetition rate of 100 MHz

    SciTech Connect

    Annenkov, V I; Garanin, Sergey G; Eroshenko, V A; Zhidkov, N V; Zubkov, A V; Kalipanov, S V; Kalmykov, N A; Kovalenko, V P; Krotov, V A; Lapin, S G; Martynenko, S P; Pankratov, V I; Faizullin, V S; Khrustalev, V A; Khudikov, N M; Chebotar, V S

    2009-08-31

    A train of a few tens of high-power subnanosecond laser pulses with a repetition period of 10 ns is generated in the Iskra-5 facility. The laser pulse train has an energy of up to 300 J and contains up to 40 pulses (by the 0.15 intensity level), the single pulse duration in the train being {approx}0.5 ns. The results of experiments on conversion of a train of laser pulses to a train of X-ray pulses are presented. Upon irradiation of a tungsten target, a train of X-ray pulses is generated with the shape of an envelope in the spectral band from 0.18 to 0.28 keV similar to that of the envelope of the laser pulse train. The duration of a single X-ray pulse in the train is equal to that of a single laser pulse. (lasers)

  8. Ageing of organic electrical insulating materials due to radiation—III. Dielectric properties of a cycloaliphatic epoxy resin: Effect of irradiation environmental conditions and dose rate

    NASA Astrophysics Data System (ADS)

    Spadaro, G.; Calderaro, E.; Schifani, R.; Rizzo, G.

    The effect of dose rate under different environmental conditions on a cycloaliphatic epoxy resin is considered. In particular dielectric measurements were performed. The dose rate is an interesting parameter on evaluating the behaviour of insulating materials in real operating conditions by means of accelerated ageing laboratory tests.

  9. The non-contact monitoring of heart and respiratory rates using laser irradiation: an experimental simultaneous monitoring with and without clothes during biochemical hazards.

    PubMed

    Matsui, T; Ishizuka, T; Ishihara, M; Ishihara, M; Matsumura, K; Kikuchi, M; Kurita, A

    2003-01-01

    The purpose of this study is to develop a non-contact method to evaluate the heart and respiratory rates simultaneously using a single optical sensor which can be used without the removal of clothes before a decontamination procedure in biochemical hazards. We measured the heart and respiratory rates with and without clothes to assess the vital sign monitoring before decontamination. In order to monitor the heart and respiratory rates of rabbits simultaneously, the respiratory and cardiac peaks were separated using fast Fourier transform from a 5 mW helium-neon laser (wavelength 632.8 nm) reflected off the chest walls of rabbits. A cloth (50 mm x 50 mm, 2 mm thick) was placed on the chest of the rabbits to simulate the vital sign monitoring with clothes. The heart rate measured using this method agreed with the rate derived from an electrocardiogram (r = 0.82, p<0.05). The respiratory rate correlated with the manually measured respirator rate (r = 0.93, p<0.05). This method appears promising as a non-contact method for monitoring the heart and respiratory rates of patients under biochemically hazardous conditions. PMID:12775459

  10. Feasibilty of exterior vascular laser irradiation therapy

    NASA Astrophysics Data System (ADS)

    Chen, Rong; Xie, Shusen; Li, Hui; Li, Buhong; Chen, Yanjiao; Zhang, Xiaodong; Chen, Huifang; Xia, Xiangnan; Lin, Aizhen

    1998-08-01

    In order to study the exterior vascular laser irradiation therapy for replacing the intravascular laser irradiation therapy, we measure the distribution of radiant fluence rate in exterior vascular laser irradiation in vivo and imitative intravascular laser irradiation. The result shows that the average radiant fluence rate of exterior vascular and intravascular is 1.11 and 10.81 respectively, which is ten times between them. In order to get the radiant fluence rate corresponding to the intravascular laser irradiation, we suggest that about 20 mW HeNe laser could be used in exterior vascular laser irradiation therapy, and the laser must irradiate on the vascular perpendicularly. The suitable patient with exposed vascular must be chosen, and the diameter of the irradiated vascular is about 6 mm. Our experiment result, especially the data measured in vivo, will be useful for the research of light transport in human tissue.

  11. Total lymphoid irradiation

    SciTech Connect

    Sutherland, D.E.; Ferguson, R.M.; Simmons, R.L.; Kim, T.H.; Slavin, S.; Najarian, J.S.

    1983-05-01

    Total lymphoid irradiation by itself can produce sufficient immunosuppression to prolong the survival of a variety of organ allografts in experimental animals. The degree of prolongation is dose-dependent and is limited by the toxicity that occurs with higher doses. Total lymphoid irradiation is more effective before transplantation than after, but when used after transplantation can be combined with pharmacologic immunosuppression to achieve a positive effect. In some animal models, total lymphoid irradiation induces an environment in which fully allogeneic bone marrow will engraft and induce permanent chimerism in the recipients who are then tolerant to organ allografts from the donor strain. If total lymphoid irradiation is ever to have clinical applicability on a large scale, it would seem that it would have to be under circumstances in which tolerance can be induced. However, in some animal models graft-versus-host disease occurs following bone marrow transplantation, and methods to obviate its occurrence probably will be needed if this approach is to be applied clinically. In recent years, patient and graft survival rates in renal allograft recipients treated with conventional immunosuppression have improved considerably, and thus the impetus to utilize total lymphoid irradiation for its immunosuppressive effect alone is less compelling. The future of total lymphoid irradiation probably lies in devising protocols in which maintenance immunosuppression can be eliminated, or nearly eliminated, altogether. Such protocols are effective in rodents. Whether they can be applied to clinical transplantation remains to be seen.

  12. The dependence of helium generation rate on nickel content of Fe Cr Ni alloys irradiated to high dpa levels in EBR-II

    NASA Astrophysics Data System (ADS)

    Garner, F. A.; Oliver, B. M.; Greenwood, L. R.

    1998-10-01

    Fusion-relevant helium-effects experiments conducted on austenitic steels in the Materials Open Test Assembly (MOTA) of the Fast Flux Test Facility (FFTF) fast reactor had to recognize the contributions of both the high neutron energy (n,α) reactions and that of the 58Ni(n,γ) 59Ni(n,α) reaction sequence with low energy neutrons. An experiment conducted in the harder neutron spectra found within the core of Experimental Breeder Reactor-II (EBR-II) has shown that the helium in this reactor was generated almost exclusively from the interaction of high energy neutrons with the natural isotopes of nickel. There was very little contribution from 59Ni. The helium production was found to scale directly with the nickel content over the range 25-75% Ni. Even at very high neutron exposures, the helium production in such reactors can be predicted within 5% accuracy on the basis of high energy reactions, as demonstrated by an experiment conducted on three Fe-15Cr-Ni ternary alloys irradiated to doses of 75-131 dpa in EBR-II.

  13. Extracorporeal irradiation of the blood in a rate model for human acute myelocytic leukemia: increased efficacy after combination with cell mobilization by low-molecular-weight dextran sulfate

    SciTech Connect

    Hagenbeek, A.; Martens, A.C.M.

    1981-10-01

    The efficacy of extracorporeal irradiation of the blood (ECIB) in combination with cell mobilization by dextran sulfate (DS; MW 17,000) was investigated in a rat model for human acute myelocytic leukemia. Repeated injections with DS (q* 3 hr) induced a significant increase in the number of peripheral leukemic cells, i.e., up to 4.5 times the original number 6 hr after the first injection. Cell mobilization in combination with ECIB (2 x 8 hr) caused a depletion of the blood compartments and the rapidly exchangeable tissue pool down to 10 to 25% of their original sizes, as determined by measuring the distribution of infused /sup 51/Cr-labeled leukemic cells and organ weights. These size reductions are about two times as great as those in rats treated with ECIB alone. In addition, the slowly exchangeable tissue pools are significantly depleted when DS is added to ECIB treatment. The reduction the total tumor load was about 50%. This, however, is too small to result in a significant different in survival time between treated and nontreated leukemic rats.

  14. Simultaneous determination of labile proton fraction ratio and exchange rate with irradiation radio frequency (RF) power dependent quantitative CEST MRI analysis

    PubMed Central

    Sun, Phillip Zhe; Wang, Yu; Xiao, Gang; Wu, Renhua

    2014-01-01

    Chemical exchange saturation transfer (CEST) imaging is sensitive to dilute proteins/peptides and microenvironmental properties, and has been increasingly evaluated for molecular imaging and in vivo applications. However, the experimentally measured CEST effect depends on the CEST agent concentration, exchange rate and relaxation time. In addition, there may be non-negligible direct radio-frequency (RF) saturation effects, particularly severe for diamagnetic CEST (DIACEST) agents due to their relatively small chemical shift difference from that of the bulk water resonance. As such, the commonly used asymmetry analysis only provides CEST-weighted information. Recently, it has been shown with numerical simulation that both labile proton concentration and exchange rate can be determined by evaluating the RF power dependence of DIACEST effect. To validate the simulation results, we prepared and imaged two CEST phantoms: a pH phantom of serially titrated pH at a fixed creatine concentration and a concentration phantom of serially varied creatine concentration titrated to the same pH, and solved the labile proton fraction ratio and exchange rate per-pixel. For the concentration phantom, we showed that the labile proton fraction ratio is proportional to the CEST agent concentration with negligible change in the exchange rate. Additionally, we found the exchange rate of the pH phantom is dominantly base-catalyzed with little difference in the labile proton fraction ratio. In summary, our study demonstrated quantitative DIACEST MRI, which remains promising to augment the conventional CEST-weighted MRI analysis. PMID:23606428

  15. Simultaneous experimental determination of labile proton fraction ratio and exchange rate with irradiation radio frequency power-dependent quantitative CEST MRI analysis.

    PubMed

    Sun, Phillip Zhe; Wang, Yu; Xiao, Gang; Wu, Renhua

    2013-01-01

    Chemical exchange saturation transfer (CEST) imaging is sensitive to dilute proteins/peptides and microenvironmental properties, and has been increasingly evaluated for molecular imaging and in vivo applications. However, the experimentally measured CEST effect depends on the CEST agent concentration, exchange rate and relaxation time. In addition, there may be non-negligible direct radio-frequency (RF) saturation effects, particularly severe for diamagnetic CEST (DIACEST) agents owing to their relatively small chemical shift difference from that of the bulk water resonance. As such, the commonly used asymmetry analysis only provides CEST-weighted information. Recently, it has been shown with numerical simulation that both labile proton concentration and exchange rate can be determined by evaluating the RF power dependence of DIACEST effect. To validate the simulation results, we prepared and imaged two CEST phantoms: a pH phantom of serially titrated pH at a fixed creatine concentration and a concentration phantom of serially varied creatine concentration titrated to the same pH, and solved the labile proton fraction ratio and exchange rate per-pixel. For the concentration phantom, we showed that the labile proton fraction ratio is proportional to the CEST agent concentration with negligible change in the exchange rate. Additionally, we found the exchange rate of the pH phantom is dominantly base-catalyzed with little difference in the labile proton fraction ratio. In summary, our study demonstrated quantitative DIACEST MRI, which remains promising to augment the conventional CEST-weighted MRI analysis. PMID:23606428

  16. Chronic Gamma-Irradiation Induces a Dose-Rate-Dependent Pro-inflammatory Response and Associated Loss of Function in Human Umbilical Vein Endothelial Cells.

    PubMed

    Ebrahimian, T; Le Gallic, C; Stefani, J; Dublineau, I; Yentrapalli, R; Harms-Ringdahl, M; Haghdoost, S

    2015-04-01

    A central question in radiation protection research is dose and dose-rate relationship for radiation-induced cardiovascular diseases. The response of endothelial cells to different low dose rates may contribute to help estimate risks for cardiovascular diseases by providing mechanistic understanding. In this study we investigated whether chronic low-dose-rate radiation exposure had an effect on the inflammatory response of endothelial cells and their function. Human umbilical vein endothelial cells (HUVECs) were chronically exposed to radiation at a dose of 1.4 mGy/h or 4.1 mGy/h for 1, 3, 6 or 10 weeks. We determined the pro-inflammatory profile of HUVECs before and during radiation exposure, and investigated the functional consequences of this radiation exposure by measuring their capacity to form vascular networks in matrigel. Expression levels of adhesion molecules such as E-selectin, ICAM-1 and VCAM-1, and the release of pro-inflammatory cytokines such as MCP-1, IL-6 and TNF-α were analyzed. When a total dose of 2 Gy was given at a rate of 4.1 mGy/h, we observed an increase in IL-6 and MCP-1 release into the cell culture media, but this was not observed at 1.4 mGy/h. The increase in the inflammatory profile induced at the dose rate of 4.1 mGy/h was also correlated with a decrease in the capacity of the HUVECs to form a vascular network in matrigel. Our results suggest that dose rate is an important parameter in the alteration of HUVEC inflammatory profile and function. PMID:25807321

  17. [Food irradiation].

    PubMed

    Migdał, W

    1995-01-01

    A worldwide standard on food irradiation was adopted in 1983 by Codex Alimentarius Commission of the Joint Food Standard Programme of the Food and Agriculture Organization (FAO) of the United Nations and the World Health Organization (WHO). As a result, 41 countries have approved the use of irradiation for treating one or more food items and the number is increasing. Generally, irradiation is used to: food loses, food spoilage, disinfestation, safety and hygiene. The number of countries which use irradiation for processing food for commercial purposes has been increasing steadily from 19 in 1987 to 33 today. In the frames of the national programme on the application of irradiation for food preservation and hygienization an experimental plant for electron beam processing has been established in Institute of Nuclear Chemistry and Technology. The plant is equipped with a small research accelerator Pilot (19MeV, 1 kW) and an industrial unit Elektronika (10MeV, 10 kW). On the basis of the research there were performed at different scientific institutions in Poland, health authorities have issued permission for irradiation for: spices, garlic, onions, mushrooms, potatoes, dry mushrooms and vegetables. PMID:8619113

  18. Tissue irradiator

    DOEpatents

    Hungate, F.P.; Riemath, W.F.; Bunnell, L.R.

    1975-12-16

    A tissue irradiator is provided for the in-vivo irradiation of body tissue. The irradiator comprises a radiation source material contained and completely encapsulated within vitreous carbon. An embodiment for use as an in- vivo blood irradiator comprises a cylindrical body having an axial bore therethrough. A radioisotope is contained within a first portion of vitreous carbon cylindrically surrounding the axial bore, and a containment portion of vitreous carbon surrounds the radioisotope containing portion, the two portions of vitreous carbon being integrally formed as a single unit. Connecting means are provided at each end of the cylindrical body to permit connections to blood- carrying vessels and to provide for passage of blood through the bore. In a preferred embodiment, the radioisotope is thulium-170 which is present in the irradiator in the form of thulium oxide. A method of producing the preferred blood irradiator is also provided, whereby nonradioactive thulium-169 is dispersed within a polyfurfuryl alcohol resin which is carbonized and fired to form the integral vitreous carbon body and the device is activated by neutron bombardment of the thulium-169 to produce the beta-emitting thulium-170.

  19. High-dose Extended-Field Irradiation and High-Dose-Rate Brachytherapy With Concurrent Chemotherapy for Cervical Cancer With Positive Para-Aortic Lymph Nodes

    SciTech Connect

    Kim, Young Seok; Kim, Jong Hoon; Ahn, Seung Do; Lee, Sang-wook; Shin, Seong Soo; Nam, Joo-Hyun; Kim, Young-Tak; Kim, Yong-Man; Kim, Jong-Hyeok; Choi, Eun Kyung

    2009-08-01

    Purpose: To determine the efficacy and toxicity of extended-field radiotherapy (RT) with concurrent platinum-based chemotherapy in patients with uterine cervical carcinoma and positive para-aortic nodes. Methods and Materials: We retrospectively reviewed the results for 33 women with Stage IB-IVB cervical cancer. Each patient had received 59.4 Gy, including a three-dimensional conformal boost to the para-aortic lymph nodes and 41.4-50.4 Gy of external beam radiotherapy to the pelvis. Each patient also underwent six or seven applications of high-dose-rate brachytherapy (median, 5 Gy to point A at each session). Results: The median follow-up period of surviving patients was 39 months. The most common acute toxicity was hematologic, observed in 23 women. Severe acute and late gastrointestinal toxicity was observed in 3 and 4 patients, respectively. More than three-quarters of patients showed a complete response, encompassing the primary mass, metastatic pelvic, and para-aortic lymph nodes. Of the 33 women, 15 had no evidence of disease, 6 had persistent disease, 4 developed in-field failures, and 6 developed distant failures. The 5-year overall and disease-free survival rate was 47% and 42%, respectively. Conclusion: Concurrent chemoradiotherapy with extended-field radiotherapy is feasible in women with uterine cervical carcinoma and positive para-aortic lymph nodes, with acceptable late morbidity and a high survival rate, although it was accompanied by substantial acute toxicity.

  20. The role of growth rate, redox-state of the plastoquinone pool and the trans-thylakoid deltapH in photoacclimation of Chlorella vulgaris to growth irradiance and temperature.

    PubMed

    Wilson, K E; Huner, N P

    2000-12-01

    The long-term photoacclimation of Chlorella vulgaris Beijer (UTEX 265) to growth irradiance and growth temperature under ambient CO2 conditions was examined. While cultures grew at a faster rate at 27 than at 5 degrees C, growth rates appeared to be independent of irradiance. Decreases in light-harvesting polypeptide accumulation, increases in xanthophyll pool size and changes in the epoxidation state of the xanthophyll cycle pigments were correlated linearly with increases in the relative reduction state of QA, the primary quinone receptor of photosystem II, when estimated as 1-qP under steady-state growth conditions. However, we show that there is also a specific temperature-dependent component, in addition to the redox-state of the QA, involved in regulating the content and composition of light-harvesting complex II of C. vulgaris. In contrast, modulation of the epoxidation state of the xanthophyll pool in response to increased 1-qP in cells grown at 5 degrees C was indistinguishable from that of cells grown at 27 degrees C, indicating that light and temperature interact in a similar way to regulate xanthophyll cycle activity in C. vulgaris. Because C. vulgaris exhibited a low-light phenotype in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), but a high-light phenotype upon addition of 2,5-dibromo-6-isopropyl-3-methyl-1,4-benzoquinone, we conclude that the plastoquinone pool acts as a sensor regulating the accumulation of light-harvesting polypeptides in C. vulgaris. However, concomitant measurements of non-photochemical fluorescence quenching (qN) and the epoxidation state of the xanthophyll pool appear to indicate that, in addition to the redox-state of the plastoquinone pool, the trans-thylakoid deltapH may also contribute to sensing changes in irradiance and temperature that would lead to over-excitation of the photosynthetic apparatus. We suggest that sink capacity as reflected in photosynthate utilization and cell growth ultimately regulate

  1. Irradiation subassembly

    DOEpatents

    Seim, O.S.; Filewicz, E.C.; Hutter, E.

    1973-10-23

    An irradiation subassembly for use in a nuclear reactor is described which includes a bundle of slender elongated irradiation -capsules or fuel elements enclosed by a coolant tube and having yieldable retaining liner between the irradiation capsules and the coolant tube. For a hexagonal bundle surrounded by a hexagonal tube the yieldable retaining liner may consist either of six segments corresponding to the six sides of the tube or three angular segments each corresponding in two adjacent sides of the tube. The sides of adjacent segments abut and are so cut that metal-tometal contact is retained when the volume enclosed by the retaining liner is varied and Springs are provided for urging the segments toward the center of the tube to hold the capsules in a closely packed configuration. (Official Gazette)

  2. Irradiance gradients

    SciTech Connect

    Ward, G.J. Ecole Polytechnique Federale, Lausanne ); Heckbert, P.S. . School of Computer Science Technische Hogeschool Delft . Dept. of Technical Mathematics and Informatics)

    1992-04-01

    A new method for improving the accuracy of a diffuse interreflection calculation is introduced in a ray tracing context. The information from a hemispherical sampling of the luminous environment is interpreted in a new way to predict the change in irradiance as a function of position and surface orientation. The additional computation involved is modest and the benefit is substantial. An improved interpolation of irradiance resulting from the gradient calculation produces smoother, more accurate renderings. This result is achieved through better utilization of ray samples rather than additional samples or alternate sampling strategies. Thus, the technique is applicable to a variety of global illumination algorithms that use hemicubes or Monte Carlo sampling techniques.

  3. Role of heat accumulation in the multi-shot damage of silicon irradiated with femtosecond XUV pulses at a 1 MHz repetition rate.

    PubMed

    Sobierajski, Ryszard; Jacyna, Iwanna; Dłużewski, Piotr; Klepka, Marcin T; Klinger, Dorota; Pełka, Jerzy B; Burian, Tomáš; Hájková, Věra; Juha, Libor; Saksl, Karel; Vozda, Vojtěch; Makhotkin, Igor; Louis, Eric; Faatz, Bart; Tiedtke, Kai; Toleikis, Sven; Enkisch, Hartmut; Hermann, Martin; Strobel, Sebastian; Loch, Rolf A; Chalupsky, Jaromir

    2016-07-11

    The role played by heat accumulation in multi-shot damage of silicon was studied. Bulk silicon samples were exposed to intense XUV monochromatic radiation of a 13.5 nm wavelength in a series of 400 femtosecond pulses, repeated with a 1 MHz rate (pulse trains) at the FLASH facility in Hamburg. The observed surface morphological and structural modifications are formed as a result of sample surface melting. Modifications are threshold dependent on the mean fluence of the incident pulse train, with all threshold values in the range of approximately 36-40 mJ/cm2. Experimental data is supported by a theoretical model described by the heat diffusion equation. The threshold for reaching the melting temperature (45 mJ/cm2) and liquid state (54 mJ/cm2), estimated from this model, is in accordance with experimental values within measurement error. The model indicates a significant role of heat accumulation in surface modification processes. PMID:27410821

  4. Irradiated foods

    MedlinePlus

    ... it reduces the risk of food poisoning . Food irradiation is used in many countries. It was first approved in the U.S. to prevent sprouts on white potatoes, and to control insects on wheat and in certain spices and seasonings.

  5. Simultaneous Integrated Boost Irradiation After Breast-Conserving Surgery: Physician-Rated Toxicity and Cosmetic Outcome at 30 Months' Follow-Up

    SciTech Connect

    Bantema-Joppe, Enja J.; Schilstra, Cornelis; Bock, Geertruida H. de; Dolsma, Wil V.; Busz, Dianne M.; Langendijk, Johannes A.; Maduro, John H.

    2012-07-15

    Purpose: To evaluate toxicity and cosmetic outcome (CO) in breast cancer survivors treated with three-dimensional conformal radiotherapy with a hypofractionated, simultaneous integrated boost (3D-CRT-SIB) and to identify risk factors for toxicity, with special focus on the impact of age. Methods and Materials: Included were 940 consecutive disease-free patients treated for breast cancer (Stage 0-III) with 3D-CRT-SIB, after breast-conserving surgery, from 2005 to 2010. Physician-rated toxicity (Common Terminology Criteria for Adverse Events version 3.0) and CO were prospectively assessed during yearly follow-up, up to 5 years after radiotherapy. Multivariate logistic regression analyses using a bootstrapping method were performed. Results: At 3 years, toxicity scores of 436 patients were available. Grade {>=}2 fibrosis in the boost area was observed in 8.5%, non-boost fibrosis in 49.4%, pain to the chest wall in 6.7%, and fair/poor CO in 39.7% of cases. Radiotherapy before chemotherapy was significantly associated with grade {>=}2 boost fibrosis at 3 years (odds ratio [OR] 2.8, 95% confidence interval [CI] 1.3-6.0). Non-boost fibrosis was associated with re-resection (OR 2.2, 95% CI 1.2-4.0) and larger tumors (OR 1.1, 95% CI 1.0-1.1). At 1 year, chest wall pain was significantly associated with high boost dosage (OR 2.1, 95% CI 1.2-3.7) and younger age (OR 0.4, 95% CI 0.2-0.7). A fair/poor CO was observed more often after re-resection (OR 4.5, 95% CI 2.4-8.5), after regional radiotherapy (OR 2.9, 95% CI 1.2-7.1), and in larger tumors (OR 1.1, 95% CI 1.0-1.1). Conclusions: Toxicity and CO are not impaired after 3D-CRT-SIB. Fibrosis was not significantly associated with radiotherapy parameters. Independent risk factors for fibrosis were chemotherapy after radiotherapy, re-resection, and larger tumor size. Re-resection was most predictive for worse CO. Age had an impact on chest wall pain occurrence.

  6. Consumer acceptance of irradiated poultry.

    PubMed

    Hashim, I B; Resurreccion, A V; McWatters, K H

    1995-08-01

    A simulated supermarket setting (SSS) test was conducted to determine whether consumers (n = 126) would purchase irradiated poultry products, and the effects of marketing strategies on consumer purchase of irradiated poultry products. Consumer preference for irradiated poultry was likewise determined using a home-use test. A slide program was the most effective educational strategy in changing consumers' purchase behavior. The number of participants who purchased irradiated boneless, skinless breasts and irradiated thighs after the educational program increased significantly from 59.5 and 61.9% to 83.3 and 85.7% for the breasts and thighs, respectively. Using a label or poster did not increase the number of participants who bought irradiated poultry products. About 84% of the participants consider it either "somewhat necessary" or "very necessary" to irradiate raw chicken and would like all chicken that was served in restaurants or fast food places to be irradiated. Fifty-eight percent of the participants would always buy irradiated chicken if available, and an additional 27% would buy it sometimes. About 44% of the participants were willing to pay the same price for irradiated chicken as for nonirradiated. About 42% of participants were willing to pay 5% or more than what they were currently paying for nonirradiated chicken. Seventy-three percent or more of consumers who participated in the home-use test (n = 74) gave the color, appearance, and aroma of the raw poultry products a minimum rating of 7 (= like moderately). After consumers participated in a home-use test, 84 and 88% selected irradiated thighs and breasts, respectively, over nonirradiated in a second SSS test. PMID:7479506

  7. Design of YCF-1 mobile γ irradiator

    NASA Astrophysics Data System (ADS)

    Hehu, Zhang; Chuanzhen, Wang

    1993-07-01

    YCF-1 Mobile irradiator is designed by BINE of China. It has been put into running in YanJi city of Jilin province. It is able to be moved to border and distance places and area lumped and spreading out of agricultural products to service. It can play a important role in demonstration and extending irradiation technology in food irradiation, disinfestation, sterilization and quarantine, etc. This paper describes the features and design considerations of mobile irradiator. This irradiator adopted Cesium-137 source. The design capacity of loading source is 9.25PBq (250kCi), A half-time of Cs- 137 is 30.2 years long, exchanging source is not needed utilization rate of energy is higher, and the shielding is thinner, The Weight is lighter, The dose rate on the surface of it is 0.0025mSv/h in accordance with national standard. The internal size of irradiation room is 1800×1800×900mm (L×W×H), The sheilding of irradiation room is a steel shell filled with lead. The thickness of lead is 18cm. The irradiator is installed on a special flat truck. The size of the truck is 7000×3400×4200mm (L×W×H). The weight of irradiator is more than 80 150kw. The main components and parts of irradiator are: source, source racks and hoist, irradiation chamber, storage source chamber, the product's transport system, dose monitoring system, ventilation system and safety interlock system, etc.

  8. Objective and Longitudinal Assessment of Dermatitis After Postoperative Accelerated Partial Breast Irradiation Using High-Dose-Rate Interstitial Brachytherapy in Patients With Breast Cancer Treated With Breast Conserving Therapy: Reduction of Moisture Deterioration by APBI

    SciTech Connect

    Tanaka, Eiichi; Yamazaki, Hideya; Yoshida, Ken; Takenaka, Tadashi; Masuda, Norikazu; Kotsuma, Tadayuki; Yoshioka, Yasuo; Inoue, Takehiro

    2011-11-15

    Purpose: To objectively evaluate the radiation dermatitis caused by accelerated partial breast irradiation (APBI) using high-dose-rate interstitial brachytherapy. Patients and Methods: The skin color and moisture changes were examined using a newly installed spectrophotometer and corneometer in 22 patients who had undergone APBI using open cavity implant high-dose-rate interstitial brachytherapy (36 Gy in six fractions) and compared with the corresponding values for 44 patients in an external beam radiotherapy (EBRT) control group (50-60 Gy in 25-30 fractions within 5-6 weeks) after breast conserving surgery. Results: All values changed significantly as a result of APBI. The extent of elevation in a Asterisk-Operator (reddish) and reduction in L Asterisk-Operator (black) values caused by APBI were similar to those for EBRT, with slightly delayed recovery for 6-12 months after treatment owing to the surgical procedure. In contrast, only APBI caused a change in the b Asterisk-Operator values, and EBRT did not, demonstrating that the reduction in b Asterisk-Operator values (yellowish) depends largely on the surgical procedure. The changes in moisture were less severe after APBI than after EBRT, and the recovery was more rapid. The toxicity assessment using the Common Toxicity Criteria, version 3, showed that all dermatitis caused by APBI was Grade 2 or less. Conclusion: An objective analysis can quantify the effects of APBI procedures on color and moisture cosmesis. The radiation dermatitis caused by APBI using the present schedule showed an equivalent effect on skin color and a less severe effect on moisture than the effects caused by standard EBRT.

  9. HRB-22 irradiation phase test data report

    SciTech Connect

    Montgomery, F.C.; Acharya, R.T.; Baldwin, C.A.; Rittenhouse, P.L.; Thoms, K.R.; Wallace, R.L.

    1995-03-01

    Irradiation capsule HRB-22 was a test capsule containing advanced Japanese fuel for the High Temperature Test Reactor (HTTR). Its function was to obtain fuel performance data at HTTR operating temperatures in an accelerated irradiation environment. The irradiation was performed in the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL). The capsule was irradiated for 88.8 effective full power days in position RB-3B of the removable beryllium (RB) facility. The maximum fuel compact temperature was maintained at or below the allowable limit of 1300{degrees}C for a majority of the irradiation. This report presents the data collected during the irradiation test. Included are test thermocouple and gas flow data, the calculated maximum and volume average temperatures based on the measured graphite temperatures, measured gaseous fission product activity in the purge gas, and associated release rate-to-birth rate (R/B) results. Also included are quality assurance data obtained during the test.

  10. Prone Whole-Breast Irradiation Using Three-Dimensional Conformal Radiotherapy in Women Undergoing Breast Conservation for Early Disease Yields High Rates of Excellent to Good Cosmetic Outcomes in Patients With Large and/or Pendulous Breasts

    SciTech Connect

    Bergom, Carmen; Kelly, Tracy; Morrow, Natalya; Wilson, J. Frank; Walker, Alonzo; Xiang Qun; Ahn, Kwang Woo; White, Julia

    2012-07-01

    Purpose: To report our institution's experience using prone positioning for three-dimensional conformal radiotherapy (3D-CRT) to deliver post-lumpectomy whole breast irradiation (WBI) in a cohort of women with large and/or pendulous breasts, to determine the rate of acute and late toxicities and, more specifically, cosmetic outcomes. We hypothesized that using 3D-CRT for WBI in the prone position would reduce or eliminate patient and breast size as negative prognostic indicators for toxicities associated with WBI. Methods and Materials: From 1998 to 2006, 110 cases were treated with prone WBI using 3D-CRT. The lumpectomy, breast target volumes, heart, and lung were contoured on all computed tomography scans. A dose of 45-50 Gy was prescribed to the breast volume using standard fractionation schemes. The planning goals were {>=}95% of prescription to 95% of the breast volume, and 100% of boost dose to 95% of lumpectomy planning target volume. Toxicities and cosmesis were prospectively scored using the Common Terminology Criteria for Adverse Effects Version 3.0 and the Harvard Scale. The median follow-up was 40 months. Results: The median body mass index (BMI) was 33.6 kg/m{sup 2}, and median breast volume was 1396 cm{sup 3}. The worst toxicity encountered during radiation was Grade 3 dermatitis in 5% of our patient population. Moist desquamation occurred in 16% of patients, with only 2% of patients with moist desquamation outside the inframammary/axillary folds. Eleven percent of patients had Grade {>=}2 late toxicities, including Grade 3 induration/fibrosis in 2%. Excellent to good cosmesis was achieved in 89%. Higher BMI was associated with moist desquamation and breast pain, but BMI and breast volume did not impact fibrosis or excellent to good cosmesis. Conclusion: In patients with higher BMI and/or large-pendulous breasts, delivering prone WBI using 3D-CRT results in favorable toxicity profiles and high excellent to good cosmesis rates. Higher BMI was

  11. Prone Whole-Breast Irradiation Using Three-Dimensional Conformal Radiotherapy in Women Undergoing Breast Conservation for Early Disease Yields High Rates of Excellent to Good Cosmetic Outcomes in Patients With Large and/or Pendulous Breasts

    PubMed Central

    Bergom, Carmen; Kelly, Tracy; Morrow, Natalya; Wilson, J. Frank; Walker, Alonzo; Xiang, Qun; Ahn, Kwang Woo; White, Julia

    2013-01-01

    Purpose To report our institution’s experience using prone positioning for three-dimensional conformal radiotherapy (3D-CRT) to deliver post-lumpectomy whole breast irradiation (WBI) in a cohort of women with large and/or pendulous breasts, to determine the rate of acute and late toxicities and, more specifically, cosmetic outcomes. We hypothesized that using 3D-CRT for WBI in the prone position would reduce or eliminate patient and breast size as negative prognostic indicators for toxicities associated with WBI. Methods and Materials From 1998 to 2006, 110 cases were treated with prone WBI using 3D-CRT. The lumpectomy, breast target volumes, heart, and lung were contoured on all computed tomography scans. A dose of 45–50 Gy was prescribed to the breast volume using standard fractionation schemes. The planning goals were ≥95% of prescription to 95% of the breast volume, and 100% of boost dose to 95% of lumpectomy planning target volume. Toxicities and cosmesis were prospectively scored using the Common Terminology Criteria for Adverse Effects Version 3.0 and the Harvard Scale. The median follow-up was 40 months. Results The median body mass index (BMI) was 33.6 kg/m2, and median breast volume was 1396 cm3. The worst toxicity encountered during radiation was Grade 3 dermatitis in 5% of our patient population. Moist desquamation occurred in 16% of patients, with only 2% of patients with moist desquamation outside the inframammary/axillary folds. Eleven percent of patients had Grade ≥2 late toxicities, including Grade 3 induration/fibrosis in 2%. Excellent to good cosmesis was achieved in 89%. Higher BMI was associated with moist desquamation and breast pain, but BMI and breast volume did not impact fibrosis or excellent to good cosmesis. Conclusion In patients with higher BMI and/or large–pendulous breasts, delivering prone WBI using 3D-CRT results in favorable toxicity profiles and high excellent to good cosmesis rates. Higher BMI was associated with moist

  12. Free radical kinetics on irradiated fennel

    NASA Astrophysics Data System (ADS)

    Yamaoki, Rumi; Kimura, Shojiro; Ohta, Masatoshi

    2008-09-01

    Herein, an electron spin resonance study on the behavior of organic radicals in fennel before and after irradiation is reported. The spectrum of irradiated fennel composed of the spectrum component derived from the un-irradiated sample (near g=2.005) and the spectra components derived from carbohydrates. The time decay of intensity spectral components was well explained by first-order kinetics with a variety of rate constants. Especially, the signal at near g=2.02 ascribed to stable cellulose-derivative components is expected to be a good indicator in the identification of irradiated plant samples.

  13. Use of Irradiated Foods

    NASA Technical Reports Server (NTRS)

    Brynjolfsson, A.

    1985-01-01

    The safety of irradiated foods is reviewed. Guidelines and regulations for processing irradiated foods are considered. The radiolytic products formed in food when it is irradiated and its wholesomeness is discussed. It is concluded that food irradiation processing is not a panacea for all problems in food processing but when properly used will serve the space station well.

  14. Detection of irradiated liquor

    NASA Astrophysics Data System (ADS)

    Shengchu, Qi; Jilan, Wu; Rongyao, Yuan

    D-2,3-butanediol is formed by irradiation processes in irradiated liquors. This radiolytic product is not formed in unirradiated liquors and its presence can therefore be used to identify whether a liquor has been irradiated or not. The relation meso/dl≈1 for 2,3-butanediol and the amount present in irradiated liquors may therefore be used as an indication of the dose used in the irradiation.

  15. Growth-irradiance relationships in phytoplankton

    SciTech Connect

    Falkowski, P.G.; Dubinsky, Z.; Wyman, K.

    1985-03-01

    The steady state growth rates of three species of marine phytoplankton, Thalassiosira weisflogii, Isochrysis galbana, and Prorocentrum micans, were followed in turbidostat culture. At each growth irradiance, photosynthesis and respiration were measured by following changes in oxygen. Together with measurements of optical absorption cross sections, cellular chlorophyll, carbon and nitrogen, and excretion rates as well as knowledge of the quantum flux, the quantum requirement for growth and photosynthesis were calculated. Our results suggest that variations in growth rate caused by changes in irradiance may be related to changes in respiration rates relative to growth as well as changes in optical absorption cross sections for a given species. Interspecific differences in growth rate at a given irradiance are not related to changes in respiration however, but are primarily attributable to differences in optical absorption cross sections normalized to chlorophyll and differences in chlorophyll:carbon ratios.

  16. Pretransfusion blood irradiation: Clinical rationale and dosimetric considerations

    SciTech Connect

    Masterson, M.E.; Febo, R. )

    1992-05-01

    The irradiation of blood before transfusion into immunosuppressed patients is an increasingly common technique used to prevent graft-versus-host disease. A technical procedure is described for the calibration of blood irradiators, including the determination of absolute dose rate and relative dose distribution over the blood volume. Results of dose rate measurements on commercially available irradiators indicate differences of +5% to {minus}13% with manufacturer-supplied calibrations and variations in the relative dose rate over the irradiation volume from 70% to 180%. The clinical implications of these findings and the need for accurate dosimetry are discussed.

  17. Significance of primary irradiation creep in graphite

    NASA Astrophysics Data System (ADS)

    Erasmus, Christiaan; Kok, Schalk; Hindley, Michael P.

    2013-05-01

    Traditionally primary irradiation creep is introduced into graphite analysis by applying the appropriate amount of creep strain to the model at the initial time-step. This is valid for graphite components that are subjected to high fast neutron flux fields and constant stress fields, but it does not allow for the effect of movement of stress locations around a graphite component during life, nor does it allow primary creep to be applied rate-dependently to graphite components subject to lower fast neutron flux. This paper shows that a differential form of primary irradiation creep in graphite combined with the secondary creep formulation proposed by Kennedy et al. performs well when predicting creep behaviour in experimental samples. The significance of primary irradiation creep in particular in regions with lower flux is investigated. It is shown that in low flux regions with a realistic operating lifetime primary irradiation creep is significant and is larger than secondary irradiation creep.

  18. Modeling precipitate evolution in zirconium alloys during irradiation

    NASA Astrophysics Data System (ADS)

    Robson, J. D.

    2016-08-01

    The second phase precipitates (SPPs) in zirconium alloys are critical in controlling their performance. During service, SPPs are subject to both thermal and irradiation effects that influence volume fraction, number, and size. In this paper, a model has been developed to capture the combined effect of thermal and irradiation exposure on the Zr(Fe,Cr)2 precipitates in Zircaloy. The model includes irradiation induced precipitate destabilization integrated into a classical size class model for nucleation, growth and coarsening. The model has been applied to predict the effect of temperature and irradiation on SPP evolution. Increasing irradiation displacement rate is predicted to strongly enhance the loss of particles that arises from coarsening alone. The effect of temperature is complex due to competition between coarsening and irradiation damage. As temperature increases, coarsening is predicted to become increasingly important compared to irradiation induced dissolution and may increase resistance to irradiation induced dissolution by increasing particle size.

  19. Dental Implants Installed in Irradiated Jaws

    PubMed Central

    Chambrone, L.; Mandia, J.; Shibli, J.A.; Romito, G.A.; Abrahao, M.

    2013-01-01

    The aim of this study was to assess the survival rate of titanium implants placed in irradiated jaws. MEDLINE, EMBASE, and CENTRAL were searched for studies assessing implants that had been placed in nongrafted sites of irradiated patients. Random effects meta-analyses assessed implant loss in irradiated versus nonirradiated patients and in irradiated patients treated with hyperbaric oxygen (HBO) therapy. Of 1,051 potentially eligible publications, 15 were included. A total of 10,150 implants were assessed in the included studies, and of these, 1,689 (14.3%) had been placed in irradiated jaws. The mean survival rate in the studies ranged from 46.3% to 98.0%. The pooled estimates indicated a significant increase in the risk of implant failure in irradiated patients (risk ratio: 2.74; 95% confidence interval: 1.86, 4.05; p < .00001) and in maxillary sites (risk ratio: 5.96; 95% confidence interval: 2.71, 13.12; p < .00001). Conversely, HBO therapy did not reduce the risk of implant failure (risk ratio: 1.28; 95% confidence interval: 0.19, 8.82; p = .80). Radiotherapy was linked to higher implant failure in the maxilla, and HBO therapy did not improve implant survival. Most included publications reported data on machined implants, and only 3 studies on HBO therapy were included. Overall, implant therapy appears to be a viable treatment option for reestablishing adequate occlusion and masticatory conditions in irradiated patients. PMID:24158336

  20. Influence of microwave irradiation on enzyme kinetics

    NASA Astrophysics Data System (ADS)

    Pavelkić, V. M.; Stanisavljev, D. R.; Gopčević, K. R.; Beljanski, M. V.

    2009-09-01

    The in vitro effect of 2.45 GHz microwave irradiation on porcine pepsin activity under controlled temperature and absorbed microwave power via kinetic parameters was evaluated. Kinetic study with respect of time of irradiation demonstrated the existence of an inactivation effect of microwaves at pH 2 on pepsin molecule. Bovine serum albumin (BSA)-bromphenol blue (BPB) complex was used as substrate for the assay of pepsin by kinetic method. Depending on absorbed microwave dose, the degree of caused inactivation varies from 39.11 to 45.91% for 5 and 20 min of pepsin MW irradiation, respectively. The V maxapp and K mapp were calculated for low (5 min of MW irradiation) and higher specific absorbed dose (20 min of MW irradiation), as well as for untreated enzyme, from double reciprocal Lineweaver-Burk plot. The effect of microwaves on substrate (BSA-BPB complex) was also investigated. For reaction performed with MW irradiated substrate for 5 min the reaction rate was decreased for 15.15%, while for 20 min of substrate irradiation reaction rate was decreased for 25.52% compared to the control reaction.

  1. Total body calcium analysis. [neutron irradiation

    NASA Technical Reports Server (NTRS)

    Lewellen, T. K.; Nelp, W. B.

    1974-01-01

    A technique to quantitate total body calcium in humans is developed. Total body neutron irradiation is utilized to produce argon 37. The radio argon, which diffuses into the blood stream and is excreted through the lungs, is recovered from the exhaled breath and counted inside a proportional detector. Emphasis is placed on: (1) measurement of the rate of excretion of radio argon following total body neutron irradiation; (2) the development of the radio argon collection, purification, and counting systems; and (3) development of a patient irradiation facility using a 14 MeV neutron generator. Results and applications are discussed in detail.

  2. Vanadium irradiation at ATR - neutronics aspects

    SciTech Connect

    Gomes, I.C.; Smith, D.L.

    1995-04-01

    Calculations were performed to estimate damage and transmutation rates in vanadium irradiated in the ATR (Advanced Test Reactor) located in Idaho. The main focuses of the study are to evaluate the transmutation of vanadium to chromium and to explore ways to design the irradiation experiment to avoid excessive transmutation. It was found that the A-hole of ATR produces damage rate of {approximately} 0.2%/dpa of vanadium to chromium. A thermal neutron filter can be incorporated into the design to reduce the vanadium-to-chromium transmutation rate to low levels. A filter 1-2 mm thick of gadolinium or hafnium can be used.

  3. Irradiation autogenous mandibular grafts in primary reconstructions

    SciTech Connect

    Hamaker, R.C.

    1981-07-01

    The procedure, irradiated mandibular autografts, for primary reconstruction, is presented with an immediate success rate of 88%. Eight cases have undergone primary mandibular reconstruction with the tumorous mandible irradiated to 10,000 rads in a single dose. The longest follow-up is 2 3/4 years. The autograft has proven to be an ideal implant. Major resections of the mandible in conjunction with large myocutaneous flaps have been reconstructed utilizing this implant.

  4. Investigation of irradiated soil byproducts.

    PubMed

    Brey, R R; Rodriguez, R; Harmon, J F; Winston, P

    2001-01-01

    The high dose irradiation of windblown soil deposited onto the surface of spent nuclear fuel is of concern to long-term fuel storage stability. Such soils could be exposed to radiation fields as great as 1.08 x 10(-3) C/kg-s (15,000 R/hr) during the 40-year anticipated period of interim dry storage prior to placement at the proposed national repository. The total absorbed dose in these cases could be as high as 5 x 10(7) Gy (5 x 10(9) rads). This investigation evaluated the potential generation of explosive or combustible irradiation byproducts during this irradiation. It focuses on the production of radiolytic byproducts generated within the pore water of surrogate clays that are consistent with those found on the Idaho National Engineering and Environmental Laboratory. Synthesized surrogates of localized soils containing combinations of clay, water, and aluminum samples, enclosed within a stainless steel vessel were irradiated and the quantities of the byproducts generated measured. Two types of clays, varying primarily in the presence of iron oxide, were investigated. Two treatment levels of irradiation and a control were investigated. An 18-Mev linear accelerator was used to irradiate samples. The first irradiation level provided an absorbed dose of 3.9 x 10(5)+/-1.4 x 10(5)Gy (3.9 x 10(7)+/-1.4 x 10(7) rads) in a 3-h period. At the second irradiation level, 4.8 x 10(5)+/-2.0 x 10(5)Gy (4.8 x 10(7)+/-2.0 x 10(7) rads) were delivered in a 6-h period. When averaged over all treatment parameters, irradiated clay samples with and without iron (III) oxide (moisture content = 40%) had a production rate of hydrogen gas that was a strong function of radiation-dose. A g-value of 5.61 x 10(-9)+/-1.56 x 10(-9) mol/J (0.054+/-0.015 molecules/100-eV) per mass of pore water was observed in the clay samples without iron (III) oxide for hydrogen gas production. A g-value of 1.07 x 10(-8)+/-2.91 x 10(-9) mol/J (0.103+0.028 molecules/100-eV) per mass of pore water was observed

  5. Influences of Microwave Irradiation on Environment

    NASA Astrophysics Data System (ADS)

    Murakami, H.; Abe, Y.; Iwata, T.; Kudo, I.; Saito, K.; Okuda, T.

    2004-12-01

    An experimental facility to evaluate the long-duration influence of microwave to environment, a so-called long duration microwave exposure facility (LDMEF), was constructed in Tsukuba in 1994, and so far irradiation tests on plants accumulated over 40,000 hours have been conducted with the aid of 2.45 GHz magnetron. The LDMEF consists of a pair of outdoor electromagnetically isolated areas, one under the influence of microwave irradiation with a 500 W magnetron and one without microwave irradiation. The growth rates of plants in both areas were compared and evaluated with the experimental data for the temperature distribution in the soil and power distribution of microwave. Although any appreciable influence of microwave was not noticed in the power density less than 10 mW/cm2 , the experimental results showed a significant growth rate enhancement when the power density became over 10 mW/cm2 . However, the growth was rather depressed when the power density increased over 15 mW/cm2 . These effects are well explained by the temperature and moisture in the soil which are also under an appreciable influence of microwave irradiation [1,2]. In this context, we newly constructed an indoor irradiation facility, in which the growth conditions of plants under a constant soil temperature can be maintained. In addition, irradiation with a 5.8 GHz magnetron will be conducted in the new facility. In parallel to a series of indoor and outdoor irradiation tests on plants, the influence of microwave irradiation on the growth pattern of albino mouse will be conducted. This experiment will be the first experimental evaluation for the influence of microwave irradiation on animals.

  6. Irradiation creep of dispersion strengthened copper alloy

    SciTech Connect

    Pokrovsky, A.S.; Barabash, V.R.; Fabritsiev, S.A.

    1997-04-01

    Dispersion strengthened copper alloys are under consideration as reference materials for the ITER plasma facing components. Irradiation creep is one of the parameters which must be assessed because of its importance for the lifetime prediction of these components. In this study the irradiation creep of a dispersion strengthened copper (DS) alloy has been investigated. The alloy selected for evaluation, MAGT-0.2, which contains 0.2 wt.% Al{sub 2}O{sub 3}, is very similar to the GlidCop{trademark} alloy referred to as Al20. Irradiation creep was investigated using HE pressurized tubes. The tubes were machined from rod stock, then stainless steel caps were brazed onto the end of each tube. The creep specimens were pressurized by use of ultra-pure He and the stainless steel caps subsequently sealed by laser welding. These specimens were irradiated in reactor water in the core position of the SM-2 reactors to a fluence level of 4.5-7.1 x 10{sup 21} n/cm{sup 2} (E>0.1 MeV), which corresponds to {approx}3-5 dpa. The irradiation temperature ranged from 60-90{degrees}C, which yielded calculated hoop stresses from 39-117 MPa. A mechanical micrometer system was used to measure the outer diameter of the specimens before and after irradiation, with an accuracy of {+-}0.001 mm. The irradiation creep was calculated based on the change in the diameter. Comparison of pre- and post-irradiation diameter measurements indicates that irradiation induced creep is indeed observed in this alloy at low temperatures, with a creep rate as high as {approx}2 x 10{sup {minus}9}s{sup {minus}1}. These results are compared with available data for irradiation creep for stainless steels, pure copper, and for thermal creep of copper alloys.

  7. Irradiation creep due to SIPA under cascade damage conditions

    SciTech Connect

    Woo, C.H.; Garner, F.A.; Holt, R.A.

    1992-12-31

    This paper derives the relationships between void swelling and irradiation creep due to Stress-Induced Preferred Absorption (SIPA) and SIPA-Induced Growth (SIG) under cascade damage conditions in an irradiated pressurized tube. It is found that at low swelling rates irradiation creep is a major contribution to the total diametral strain rate of the tube, whereas at high swelling rates the creep becomes a minor contribution. The anisotropy of the corresponding dislocation structure is also predicted to decline as the swelling rate increases. The theoretical predictions are found to agree very well with experimental results.

  8. Irradiation creep of vanadium-base alloys

    SciTech Connect

    Tsai, H.; Billone, M.C.; Strain, R.V.; Smith, D.L.; Matsui, H.

    1998-03-01

    A study of irradiation creep in vanadium-base alloys is underway with experiments in the Advanced Test Reactor (ATR) and the High Flux Isotope Reactor (HFIR) in the United States. Test specimens are thin-wall sealed tubes with internal pressure loading. The results from the initial ATR irradiation at low temperature (200--300 C) to a neutron damage level of 4.7 dpa show creep rates ranging from {approx}0 to 1.2 {times} 10{sup {minus}5}/dpa/MPa for a 500-kg heat of V-4Cr-4Ti alloy. These rates were generally lower than reported from a previous experiment in BR-10. Because both the attained neutron damage levels and the creep strains were low in the present study, however, these creep rates should be regarded as only preliminary. Substantially more testing is required before a data base on irradiation creep of vanadium alloys can be developed and used with confidence.

  9. Influence of the reactive atmosphere on the formation of nanoparticles in the plasma plume induced by nanosecond pulsed laser irradiation of metallic targets at atmospheric pressure and high repetition rate

    NASA Astrophysics Data System (ADS)

    Girault, M.; Le Garrec, J.-L.; Mitchell, J. B. A.; Jouvard, J.-M.; Carvou, E.; Menneveux, J.; Yu, J.; Ouf, F.-X.; Carles, S.; Potin, V.; Pillon, G.; Bourgeois, S.; Perez, J.; Marco de Lucas, M. C.; Lavisse, L.

    2016-06-01

    The influence of a reactive atmosphere on the formation of nanoparticles (NPs) in the plasma plume generated by nanosecond pulsed laser irradiation of metal targets (Ti, Al, Ag) was probed in situ using Small Angle X-ray Scattering (SAXS). Air and different O2-N2 gas mixtures were used as reactive gas within atmospheric pressure. SAXS results showed the formation of NPs in the plasma-plume with a mean radius varying in the 2-5 nm range. A decrease of the NPs size with increasing the O2 percentage in the O2-N2 gas mixture was also showed. Ex situ observations by transmission electron microscopy and structural characterizations by X-ray diffraction and Raman spectroscopy were also performed for powders collected in experiments done using air as ambient gas. The stability of the different metal oxides is discussed as being a key parameter influencing the formation of NPs in the plasma-plume.

  10. Applicability of the Sunna dosimeter for food irradiation control

    NASA Astrophysics Data System (ADS)

    Kovács, A.; Baranyai, M.; Wojnárovits, L.; Miller, S.; Murphy, M.; McLaughlin, W. L.; Slezsák, I.; Kovács, A. I.

    2002-03-01

    The quick development concerning the commercial application of food irradiation in the USA recently resulted in growing marketing of irradiated red meat as well as irradiated fresh and dried fruits. These gamma and electron irradiation technologies require specific dosimetry systems for process control. The new version of the Sunna dosimeter has been characterized in gamma, electron and bremsstrahlung radiation fields by measuring the optically stimulated luminescence (osl) at 530 nm both below and above 1 kGy, i.e. for disinfestation and for meat irradiation purposes. No humidity and no significant dose rate effect on the green osl signal was observed. The temperature coefficient was determined from 0°C up to about 40°C and to stabilize the osl signal after irradiation a heat treatment method was introduced. Based on these investigations the Sunna 'gamma' film is a suitable candidate for dose control below and above 1 kGy for food irradiation technologies.

  11. Mobile gamma-irradiation robot

    NASA Astrophysics Data System (ADS)

    Teply, J.; Franek, C.; Vocilka, J.; Stetka, R.; Vins, J.; Krotil, J.; Garba, A.

    1993-07-01

    The source container with 98 TBq of 137Cs and shielding made from depleted uranium has the total weight of 264 kg, height of 0.370 and diameter 0.272 m. The container is joined to accessories allowing movment of the radiation beam. The dose rate at a distance of 0.4 m in the beam axis is 50 Gy/h. Various technical means are available for manipulation and transport. The irradiation process proceeds according to a precalculated program. The safety measures have been taken to secure the possible application in historical buildings and similar objects. The licence from health physics authorities has been obtained. The first irradiation process performed is described.

  12. Therapeutic postprostatectomy irradiation.

    PubMed

    Youssef, Emad; Forman, Jeffrey D; Tekyi-Mensah, Samuel; Bolton, Susan; Hart, Kim

    2002-06-01

    The purpose of this study was to determine the outcome of patients receiving external beam radiation for an elevated postprostatectomy prostate-specific antigen (PSA) level. Between December 1991 and September 1998, 108 patients received definitive radiation therapy for elevated postprostatectomy PSA levels. The median dose of irradiation was 68 Gy (range, 48-74 Gy). During treatment, the PSA levels were checked an average of 5 times (range, 3-7 times). Prostate-specific antigen values were judged to decline or increase during treatment if they changed by more than 0.2 ng/mL. After treatment, biochemical failure was defined as a measurable or rising PSA > 0.2 ng/mL. Median follow-up was 51 months (range, 3-112 months). Fifty-eight patients (54%) had evidence of biochemical failure. The 3- and 5-year actuarial biochemical relapse-free (bNED) survivals for all patients were 55% and 39%, respectively. Upon univariate analysis, intratreatment PSA and preradiation PSA were significant predictors of bNED survival. Patients with a PSA level that decreased during treatment had a 5-year bNED survival of 43% compared to 10% in patients with an increasing PSA level (P = 0.0002). Using the preradiation therapy PSA value as a continuous variable, higher preradiation therapy PSA levels were associated with an increased risk of failure (P = 0.004). Cut points of pretreatment PSA were derived at 0.9 ng/mL and 4.2 ng/mL using the Michael Leblanc recursive partitioning algorithm. The 5-year bNED rate for patients with a preradiation therapy PSA < 0.9 ng/mL was 45% versus 42% for patients with preradiation therapy PSA between 0.9 and 4.2 ng/mL and 21% for patients > or = 4.2 ng/mL (P = 0.0003). Patients with a Gleason score of < or = 7 had a 5-year bNED rate of 38% compared to 37% for patients with a Gleason score > 7 (P = 0.27). Other factors examined individually that did not reach statistical significance included time from surgery to radiation therapy, race, seminal vesicle

  13. Hardness Evolution of Gamma-Irradiated Polyoxymethylene

    NASA Astrophysics Data System (ADS)

    Hung, Chuan-Hao; Harmon, Julie P.; Lee, Sanboh

    2016-04-01

    This study focuses on analyzing hardness evolution in gamma-irradiated polyoxymethylene (POM) exposed to elevated temperatures after irradiation. Hardness increases with increasing annealing temperature and time, but decreases with increasing gamma ray dose. Hardness changes are attributed to defects generated in the microstructure and molecular structure. Gamma irradiation causes a decrease in the glass transition temperature, melting point, and extent of crystallinity. The kinetics of defects resulting in hardness changes follow a first-order structure relaxation. The rate constant adheres to an Arrhenius equation, and the corresponding activation energy decreases with increasing dose due to chain scission during gamma irradiation. The structure relaxation of POM has a lower energy barrier in crystalline regions than in amorphous ones. The hardness evolution in POM is an endothermic process due to the semi-crystalline nature of this polymer.

  14. IRRADIATION METHOD OF CONVERTING ORGANIC COMPOUNDS

    DOEpatents

    Allen, A.O.; Caffrey, J.M. Jr.

    1960-10-11

    A method is given for changing the distribution of organic compounds from that produced by the irradiation of bulk alkane hydrocarbons. This method consists of depositing an alkane hydrocarbon on the surface of a substrate material and irradiating with gamma radiation at a dose rate of more than 100,000 rads. The substrate material may be a metal, metal salts, metal oxides, or carbons having a surface area in excess of 1 m/sup 2//g. The hydrocarbons are deposited in layers of from 0.1 to 10 monolayers on the surfaces of these substrates and irradiated. The product yields are found to vary from those which result from the irradiation of bulk hydrocarbons in that there is an increase in the quantity of branched hydrocarbons.

  15. Wear-resistant polytetrafluoroethylene via electron irradiation

    SciTech Connect

    Blanchet, T.A.; Peng, Y.L.

    1996-06-01

    The sliding wear and friction behavior of irradiation-modified PTFE (by 10 MeV electrons in ambient air) against polished stainless steel is studied. Steady-state wear rate is shown to decrease monotonically by more than three orders of magnitude as the dose of the irradiation is increased from 0 to 30 Mrad. Friction initially increases with increasing dose, reaching a miximum value at 5 Mrad, then decreases with subsequent increases in dose, attaining a value similar to that of unirradiated PTFE at 30 Mrad. Hardness monotonically increases with increasing dose; however, irradiated PTFE was not found to abrasively damage the steel countersurface as many wear-resistant particle-filled PTFE composites do. Wear reduction is accomplished as debris production transforms from that of numerous large plate-like debris for unirradiated PTFE to that of very fine debris for irradiated PTFE. 26 refs., 6 figs.

  16. Interstitial irradiation of brain tumors: a review

    SciTech Connect

    Bernstein, M.; Gutin, P.H.

    1981-12-01

    As an adjuvant to surgery, radiation therapy has consistently proven to be the most successful form of treatment for primary and secondary malignant brain tumors and possibly for inoperable benign tumors. Because the risk of radiation necrosis of normal brain limits the amount of radiation that can be given by external beam therapy at conventional dose rates, interstitial radiation of brain tumors is a logical alternative treatment approach. We discuss the radiobiological advantages of low dose rate irradiation and intratumoral placement of sources that make interstitial irradiation an attractive treatment for brain tumors and review the history of clinical brachytherapy for intracranial neoplasia.

  17. Comparison of Deuterium Retention for Ion-irradiated and Neutron-irradiated Tungsten

    SciTech Connect

    Yasuhisa Oya; Masashi Shimada; Makoto Kobayashi; Takuji Oda; Masanori Hara; Hideo Watanabe; Yuji Hatano; Pattrick Calderoni; Kenji Okuno

    2011-12-01

    The behavior of D retention for Fe{sup 2+}-irradiated tungsten with a damage of 0.025-3 dpa was compared with that for neutron-irradiated tungsten with 0.025 dpa. The D{sub 2} thermal desorption spectroscopy (TDS) spectra for Fe{sup 2+}-irradiated tungsten consisted of two desorption stages at 450 and 550 K, while that for neutron-irradiated tungsten was composed of three stages and an addition desorption stage was found at 750 K. The desorption rate of the major desorption stage at 550K increased as the displacement damage increased due to Fe{sup 2+} irradiation increasing. In addition, the first desorption stage at 450K was found only for damaged samples. Therefore, the second stage would be based on intrinsic defects or vacancy produced by Fe{sup 2+} irradiation, and the first stage should be the accumulation of D in mono-vacancy and the activation energy would be relatively reduced, where the dislocation loop and vacancy is produced. The third one was found only for neutron irradiation, showing the D trapping by a void or vacancy cluster, and the diffusion effect is also contributed to by the high full-width at half-maximum of the TDS spectrum. Therefore, it can be said that the D{sub 2} TDS spectra for Fe{sup 2+}-irradiated tungsten cannot represent that for the neutron-irradiated one, indicating that the deuterium trapping and desorption mechanism for neutron-irradiated tungsten is different from that for the ion-irradiated one.

  18. Neutron irradiation creep in stainless steel alloys

    NASA Astrophysics Data System (ADS)

    Schüle, Wolfgang; Hausen, Hermann

    1994-09-01

    Irradiation creep elongations were measured in the HFR at Petten on AMCR steels, on 316 CE-reference steels, and on US-316 and US-PCA steels varying the irradiation temperature between 300°C and 500°C and the stress between 25 and 300 MPa. At the beginning of an irradiation a type of "primary" creep stage is observed for doses up to 3-5 dpa after which dose the "secondary" creep stage begins. The "primary" creep strain decreases in cold-worked steel materials with decreasing stress and decreasing irradiation temperature achieving also negative creep strains depending also on the pre-treatment of the materials. These "primary" creep strains are mainly attributed to volume changes due to the formation of radiation-induced phases, e.g. to the formation of α-ferrite below about 400°C and of carbides below about 700°C, and not to irradiation creep. The "secondary" creep stage is found for doses larger than 3 to 5 dpa and is attributed mainly to irradiation creep. The irradiation creep rate is almost independent of the irradiation temperature ( Qirr = 0.132 eV) and linearly dependent on the stress. The total creep elongations normalized to about 8 dpa are equal for almost every type of steel irradiated in the HFR at Petten or in ORR or in EBR II. The negative creep elongations are more pronounced in PCA- and in AMCR-steels and for this reason the total creep elongation is slightly smaller at 8 dpa for these two steels than for the other steels.

  19. Modeling of microstructure evolution in austenitic stainless steels irradiated under light water reactor condition

    NASA Astrophysics Data System (ADS)

    Gan, J.; Was, G. S.; Stoller, R. E.

    2001-10-01

    A model for microstructure development in austenitic alloys under light water reactor irradiation conditions is described. The model is derived from the model developed by Stoller and Odette to describe microstructural evolution under fast neutron or fusion reactor irradiation conditions. The model is benchmarked against microstructure measurements in 304 and 316 SS irradiated in a boiling water reactor core using one material-dependent and three irradiation-based parameters. The model is also adapted for proton irradiation at higher dose rate and higher temperature and is calibrated against microstructure measurements for proton irradiation. The model calculations show that for both neutron and proton irradiations, in-cascade interstitial clustering is the driving mechanism for loop nucleation. The loss of interstitial clusters to sinks by interstitial cluster diffusion was found to be an important factor in determining the loop density. The model also explains how proton irradiation can produce an irradiated dislocation microstructure similar to that in neutron irradiation.

  20. Comminuting irradiated ferritic steel

    DOEpatents

    Bauer, Roger E.; Straalsund, Jerry L.; Chin, Bryan A.

    1985-01-01

    Disclosed is a method of comminuting irradiated ferritic steel by placing the steel in a solution of a compound selected from the group consisting of sulfamic acid, bisulfate, and mixtures thereof. The ferritic steel is used as cladding on nuclear fuel rods or other irradiated components.

  1. Irradiated homologous costal cartilage for augmentation rhinoplasty

    SciTech Connect

    Lefkovits, G. )

    1990-10-01

    Although the ideal reconstructive material for augmentation rhinoplasty continues to challenge plastic surgeons, there exists no report in the literature that confines the use of irradiated homologous costal cartilage, first reported by Dingman and Grabb in 1961, to dorsal nasal augmentation. The purpose of this paper is to present a retrospective analysis of the author's experience using irradiated homologous costal cartilage in augmentation rhinoplasty. Twenty-seven dorsal nasal augmentations were performed in 24 patients between 16 and 49 years of age with a follow-up ranging from 1 to 27 months. Good-to-excellent results were achieved in 83.3% (20 of 24). Poor results requiring revision were found in 16.7% (4 of 24). Complication rates included 7.4% infection (2 of 27) and 14.8% warping (4 of 27). The resorption rate was zero. These results compare favorably with other forms of nasal augmentation. Advantages and disadvantages of irradiated homologous costal cartilage are discussed.

  2. Irradiation Creep in Graphite

    SciTech Connect

    Ubic, Rick; Butt, Darryl; Windes, William

    2014-03-13

    An understanding of the underlying mechanisms of irradiation creep in graphite material is required to correctly interpret experimental data, explain micromechanical modeling results, and predict whole-core behavior. This project will focus on experimental microscopic data to demonstrate the mechanism of irradiation creep. High-resolution transmission electron microscopy should be able to image both the dislocations in graphite and the irradiation-induced interstitial clusters that pin those dislocations. The team will first prepare and characterize nanoscale samples of virgin nuclear graphite in a transmission electron microscope. Additional samples will be irradiated to varying degrees at the Advanced Test Reactor (ATR) facility and similarly characterized. Researchers will record microstructures and crystal defects and suggest a mechanism for irradiation creep based on the results. In addition, the purchase of a tensile holder for a transmission electron microscope will allow, for the first time, in situ observation of creep behavior on the microstructure and crystallographic defects.

  3. Stage III and localized stage IV breast cancer: irradiation alone vs irradiation plus surgery

    SciTech Connect

    Bedwinek, J.; Rao, V.; Perez, C.; Lee, J.; Fineberg, B.

    1981-01-01

    One hundred forty-seven patients with non-inflammatory, Stage III and IV breast cancer were treated with irradiation alone (54 patients) or with a combination of irradiation and mastectomy (93 patients). In the T/sub 3/ category, the local failure rate was 45% (5/11) for the irradiation alone patients vs 12% (3/25) for the irradiation plus surgery patients; in the T/sub 4/ category these figures were 65% (28/43) vs 13% (9/68), respectively. Corresponding local failure rates by size of primary tumor were 50% (2/4) vs 15% (5/29) for tumors 0-5 cm, 43% (0/21) vs 14% (6/45) for 5-8 cm tumors, and 75% (22/29) vs 5% (1/20) for tumors greater than or equal to8 cm. The rates of regional failure for the two treatment methods were compared according to N stage; they were 9% (2/23) for irradiation alone vs 11% (8/76) for irradiation plus surgery in the N/sub 0//sub -//sub 1/ category, and 58% (18/31) vs 18% (3/17), respectively, for the N/sub 2//sub -//sub 3/ category. A dose response analysis for patients with tumors greater than 5 cm treated with irradiation alone did not show a decrease in local failure rate with increasing total tumor dose over a range of 4000 to 7000 rad, suggesting that doses in this range are too low for these large tumors. Since a significant late complication rate has been reported with doses higher than this, patients with non-inflammatory, but large (>5 cm) tumors, should be treated with a combination of surgery and irradiation whenever possible to achieve maximum local-regional control with a minimum probability of complications. In 36 patients with inflammatory carcinoma, the rates of local and regional failure were 52% (15/29) and 38% (11/29), respectively, for patients treated with irradiation alone, and 14% (1/7) and 29% (2/7), respectively, for patients receiving irradiation plus surgery.

  4. Control of fouling formation in membrane ultrafiltration by ultrasound irradiation.

    PubMed

    Naddeo, Vincenzo; Belgiorno, Vincenzo; Borea, Laura; Secondes, Mona Freda N; Ballesteros, Florencio

    2015-01-01

    The increasing application of membrane filtration in water and wastewater treatment necessitates techniques to improve performance, especially in fouling control. Ultrasound is one promising technology for this purpose as cavitational effects facilitate continuous cleaning of the membrane. This research studied the ultrafiltration of lake water in systems with constant permeate flux under medium frequency (45 kHz) ultrasound irradiation. Fouling was investigated by monitoring transmembrane pressure (TMP) using continuous or intermittent ultrasound irradiation and dead-end or crossflow operation. Best performance was observed with continuous ultrasound irradiation in crossflow mode. Intermittent irradiation reduced the rate of TMP build-up but nevertheless allowed irreversible fouling to develop. PMID:25384626

  5. Dose rate effects in WLS fibers

    NASA Astrophysics Data System (ADS)

    Maio, A.; David, M.; Gomes, A.

    1997-03-01

    The radiation hardness of different types of WLS fibers produced by BICRON, KURARAY and POL.HI.TECH has been systematically studied. Low dose rate irradiations (from 0.55 krad/h up to 4 krad/h and total dose of about 140 krad) were performed with a 60Co γ source. The results are compared with high dose rate irradiations (1.5 Mrad/h and total dose of 1 Mrad) in a mixed field of 20% of neutrons and 80% of γ's in a nuclear reactor. The degradation of the optical properties of fibers with different composition, namely different Ultraviolet absorber (UVA) concentration and different type of cladding are studied. Dose rate effects are investigated as well as the effect of irradiation with different type of particles. The UVA can help on the radiation hardness, but no permanent dose rate effects, or special effects due to the neutron component of the irradiation field were observed.

  6. Building X-ray tube based irradiators

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The construction of economical x-ray tube based irradiators in a variety of configurations is described using 1000 Watt x-ray tubes. Single tube, double tube, and four tube designs are described, as well as various cabinet construction techniques. Relatively high dose rates were achieved for small s...

  7. Irradiation-Induced Nanostructures

    SciTech Connect

    Birtcher, R.C.; Ewing, R.C.; Matzke, Hj.; Meldrum, A.; Newcomer, P.P.; Wang, L.M.; Wang, S.X.; Weber, W.J.

    1999-08-09

    This paper summarizes the results of the studies of the irradiation-induced formation of nanostructures, where the injected interstitials from the source of irradiation are not major components of the nanophase. This phenomena has been observed by in situ transmission electron microscopy (TEM) in a number of intermetallic compounds and ceramics during high-energy electron or ion irradiations when the ions completely penetrate through the specimen. Beginning with single crystals, electron or ion irradiation in a certain temperature range may result in nanostructures composed of amorphous domains and nanocrystals with either the original composition and crystal structure or new nanophases formed by decomposition of the target material. The phenomenon has also been observed in natural materials which have suffered irradiation from the decay of constituent radioactive elements and in nuclear reactor fuels which have been irradiated by fission neutrons and other fission products. The mechanisms involved in the process of this nanophase formation are discussed in terms of the evolution of displacement cascades, radiation-induced defect accumulation, radiation-induced segregation and phase decomposition, as well as the competition between irradiation-induced amorphization and recrystallization.

  8. Physicochemical and structural characteristics of rice starch modified by irradiation.

    PubMed

    Polesi, Luís Fernando; Sarmento, Silene Bruder Silveira; Moraes, Jaqueline de; Franco, Célia Maria Landi; Canniatti-Brazaca, Solange Guidolin

    2016-01-15

    This work evaluated the physicochemical and structural properties of rice starch of the cultivars IAC 202 and IRGA 417 modified by irradiation. Starch samples were irradiated by (60)Co in doses 1, 2 and 5kGy, on a rate of 0.4kGy/h. A control not irradiated was used for comparison. The granule morphology and A-type X-ray diffraction pattern were not altered by irradiation. There was an increase in amylose content, carboxyl content and acidity with irradiation. Gamma radiation did not affect the thermal properties of IAC202, but increased gelatinization temperature of IRGA417, in the higher dose (5kGy). The number of long chains of amylopectin was reduced and short chains were increased for IAC202, whereas for IRGA 417, the opposite was observed, probably due to cross-linking of starch chains. Starches had their physicochemical and structural properties modified by irradiation differently. PMID:26258702

  9. Esophageal fistula associated with intracavitary irradiation for esophageal carcinoma

    SciTech Connect

    Hishikawa, Y.; Tanaka, S.; Miura, T.

    1986-05-01

    Fifty-three patients with esophageal carcinoma were treated with high-dose-rate intracavitary irradiation following external irradiation. Ten patients developed esophageal fistula. Perforations were found in the bronchus (four), major vessels (four), pericardium (one), and mediastinum (one). The frequency of fistula occurrence in these patients was not remarkably different from that in 30 other patients treated only with greater than or equal to 50 Gy external irradiation. From the time of the development of esophageal fistula, intracavitary irradiation did not seem to accelerate the development of fistula. The fistulas in our ten patients proved to be associated with tumor, deep ulcer (created before intracavitary irradiation), chemotherapy, infection, and trauma rather than the direct effect of intracavitary irradiation.

  10. Alaskan Commodities Irradiation Project

    SciTech Connect

    Zarling, J.P.; Swanson, R.B.; Logan, R.R.; Das, D.K.; Lewis, C.E.; Workman, W.G.; Tumeo, M.A.; Hok, C.I.; Birklid, C.A.; Bennett, F.L.

    1988-12-01

    The ninety-ninth US Congress commissioned a six-state food irradiation research and development program to evaluate the commercial potential of this technology. Hawaii, Washington, Iowa, Oklahoma and Florida as well as Alaska have participated in the national program; various food products including fishery products, red meats, tropical and citrus fruits and vegetables have been studied. The purpose of the Alaskan study was to review and evaluate those factors related to the technical and economic feasibility of an irradiator in Alaska. This options analysis study will serve as a basis for determining the state's further involvement in the development of food irradiation technology. 40 refs., 50 figs., 53 tabs.

  11. The Total Irradiance Monitors

    NASA Astrophysics Data System (ADS)

    Kopp, Greg

    2015-08-01

    The first Total Irradiance Monitor (TIM) launched on NASA’s Solar Radiation and Climate Experiment in 2003 and quickly proved to be the most accurate and stable instrument on orbit for measuring the total solar irradiance (TSI). The TIM’s design improvements over the older classical radiometers helped its selection on many subsequent missions, including NASA’s Glory, NOAA’s TSI Calibration Transfer Experiment, and the series of NASA’s Total and Spectral Solar Irradiance Sensor instruments currently underway. I will summarize the status of and differences between each of the TIMs currently on-orbit or in production.

  12. Test reactor irradiation coordination

    SciTech Connect

    Heartherly, D.W.; Siman Tov, I.I.; Sparks, D.W.

    1995-10-01

    This task was established to supply and coordinate irradiation services needed by NRC contractors other than ORNL. These services include the design and assembly of irradiation capsules as well as arranging for their exposure, disassembly, and return of specimens. During this period, the final design of the facility and specimen baskets was determined through an iterative process involving the designers and thermal analysts. The resulting design should permit the irradiation of all test specimens to within 5{degrees}C of their desired temperature. Detailing of all parts is ongoing and should be completed during the next reporting period. Procurement of the facility will also be initiated during the next review period.

  13. Economics of food irradiation.

    PubMed

    Deitch, J

    1982-01-01

    This article examines the cost competitiveness of the food irradiation process. An analysis of the principal factors--the product, physical plant, irradiation source, and financing--that impact on cost is made. Equations are developed and used to calculate the size of the source for planned product throughput, efficiency factors, power requirements, and operating costs of sources, radionuclides, and accelerators. Methods of financing and capital investment are discussed. A series of tables show cost breakdowns of sources, buildings, equipment, and essential support facilities for both a cobalt-60 and a 10-MeV electron accelerator facility. Additional tables present irradiation costs as functions of a number of parameters--power input, source size, dose, and hours of annual operation. The use of the numbers in the tables are explained by examples of calculations of the irradiation costs for disinfestation of grains and radicidation of feed. PMID:6759046

  14. Food irradiation in perspective

    NASA Astrophysics Data System (ADS)

    Henon, Y. M.

    1995-02-01

    Food irradiation already has a long history of hopes and disappointments. Nowhere in the world it plays the role that it should have, including in the much needed prevention of foodborne diseases. Irradiated food sold well wherever consumers were given a chance to buy them. Differences between national regulations do not allow the international trade of irradiated foods. While in many countries food irradiation is still illegal, in most others it is regulated as a food additive and based on the knowledge of the sixties. Until 1980, wholesomeness was the big issue. Then the "prerequisite" became detection methods. Large amounts of money have been spent to design and validate tests which, in fact, aim at enforcing unjustified restrictions on the use of the process. In spite of all the difficulties, it is believed that the efforts of various UN organizations and a growing legitimate demand for food safety should in the end lead to recognition and acceptance.

  15. Irradiation of biliary carcinoma

    SciTech Connect

    Herskovic, A.; Heaston, D.; Engler, M.J.; Fishburn, R.I.; Jones, R.S.; Noell, K.T.

    1981-04-01

    External and interstitial irradiation have effected the disappearance of biliary lesions. The use of indwelling catheters in the biliary tract makes the technique more appealing. Iridium 192 implants were used.

  16. Improvement of colour strength and colourfastness properties of gamma irradiated cotton using reactive black-5

    NASA Astrophysics Data System (ADS)

    Ahmad Bhatti, Ijaz; Adeel, Shahid; Nadeem, Raziya; Asghar, Toheed

    2012-03-01

    The dyeing behaviour of gamma irradiated cotton fabric using Reactive Black-5 dye powder has been investigated. The mercerized, bleached and plain weaved cotton fabric was irradiated to different absorbed doses of 100, 200, 300, 400, 500 and 600 Gy using Co-60 gamma irradiator. Dyeing was performed using irradiated and un-irradiated cotton with dye solutions. The dyeing parameters such as temperature of dyeing, time of dyeing and pH of dyeing solutions were optimised. The colour strength values of dyed fabrics were evaluated by comparing irradiated and un-irradiated cotton in CIE Lab system using Spectra flash SF650. Methods suggested by International Standard Organisation (ISO) were employed to study the effect of gamma irradiation on the colourfastness properties of dyed fabric. It is found that gamma irradiated cotton dyed with Reactive Black-5 has not only improved the colour strength but also enhanced the rating of fastness properties.

  17. Precompaction irradiation of meteorites

    SciTech Connect

    Caffee, M.W.

    1986-01-01

    In the four meteorites studied, the nonirradiated grains show the nominal amount of spallogenic Ne and Ar expected from recent galactic cosmic ray exposure. Two conclusions follow from these observations: (1) the quality of spallogenic Ne and Ar in the irradiated grains is far more than can be explained by reasonable precompaction exposures to galactic cosmic rays. If the pre-compaction irradiation occurred in a regolith, the exposure to galactic cosmic rays would have to last several hundred m.y. for some of the grains. Similarly long ages would result if the source of the protons were solar flares with a particle flux similar to modern-day solar flares. These exposure durations are incompatible with current models for the pre-compaction irradiation of gas rich meteorites. (2) There is always a correlation between solar flare tracks and precompaction spallogenic Ne and Ar. This correlation is surprising, considering the difference in range of these two effects. Galactic cosmic rays have a range of meters whereas solar flare heavy ions have a range of less than a millimeter. This difference should largely decouple these two effects, as was shown in studies on lunar soil 60009, where both irradiated and non-irradiated grains contain large quantities of spallogenic Ne. If galactic cosmic rays are responsible for the spallogenic Ne and Ar in the irradiated grains, the authors would similarly expect the nonirradiated grains to contain large amounts of spallogenic Ne and Ar.

  18. Blood irradiation: Rationale and technique

    SciTech Connect

    Lewis, M.C. )

    1990-01-01

    Upon request by the local American Red Cross, the Savannah Regional Center for Cancer Care irradiates whole blood or blood components to prevent post-transfusion graft-versus-host reaction in patients who have severely depressed immune systems. The rationale for blood irradiation, the total absorbed dose, the type of patients who require irradiated blood, and the regulations that apply to irradiated blood are presented. A method of irradiating blood using a linear accelerator is described.

  19. Nanoimprint lithography using IR laser irradiation

    NASA Astrophysics Data System (ADS)

    Grigaliūnas, V.; Tamulevičius, S.; Muehlberger, M.; Jucius, D.; Guobienė, A.; Kopustinskas, V.; Gudonytė, A.

    2006-11-01

    A new technique called "infrared laser-assisted nanoimprint lithography" was utilised to soften the thermoplastic polymer material mR-I 8020 during nanoimprint lithography. A laser setup and a sample holder with pressure and temperature control were designed for the imprint experiments. The polymer was spin coated onto crystalline Si <1 1 1> substrates. A prepatterned Si <1 1 1> substrate, which is transparent for the CO 2 laser irradiation, was used as an imprint stamp as well. It was shown, that the thermoplastic resist mR-I 8020 could be successfully imprinted using the infrared CW CO 2 laser irradiation ( λ = 10.6 μm). The etching rate of the CO 2 laser beam irradiated mR-I 8020 resist film under O 2 RF (13.56 MHz) plasma treatment and during O 2 reactive ion beam etching was investigated as well.

  20. Effects Of Dose Rates On Radiation Damage In CMOS Parts

    NASA Technical Reports Server (NTRS)

    Goben, Charles A.; Coss, James R.; Price, William E.

    1990-01-01

    Report describes measurements of effects of ionizing-radiation dose rate on consequent damage to complementary metal oxide/semiconductor (CMOS) electronic devices. Depending on irradiation time and degree of annealing, survivability of devices in outer space, or after explosion of nuclear weapons, enhanced. Annealing involving recovery beyond pre-irradiation conditions (rebound) detrimental. Damage more severe at lower dose rates.

  1. Physiologic consequences of local heart irradiation in rats

    SciTech Connect

    Geist, B.J.; Lauk, S.; Bornhausen, M.; Trott, K.R. )

    1990-05-01

    Noninvasive methods have been used to study the long-term cardiovascular and pulmonary functional changes at rest and after exercise in adult rats following local heart irradiation with single x-ray doses of 15, 17.5 or 20 Gy, and in non-irradiated control animals. Rats that had undergone a chronic exercise program were compared with untrained cohorts. The earliest dysfunction detected was an increased respiratory rate (f) at 10 weeks after irradiation in the highest dose group. In contrast, both telemetric heart-rate (HR) and rhythm and indirect systolic blood pressure measurements performed at rest only revealed changes starting at 43 weeks after irradiation with 20 Gy, up to which point the rats showed no clinical signs of heart failure. However, the number of minutes required for the recovery of the HR to pre-exercise levels following the implementation of a standardized exercise challenge was elevated in untrained rats compared with their trained cohorts at 18 weeks after irradiation with 20 Gy. Increases in recovery times were required in the two lowest dose groups, starting at 26 weeks after irradiation. It was concluded that the reserve capacity of the cardiopulmonary system masks functional decrements at rest for many months following local heart irradiation, necessitating the use of techniques which reveal reductions in reserve capacities. Further, the influence of local irradiation to the heart and lungs deserves closer scrutiny due to mutual interactions.

  2. Disinfestation of different cereal products by irradiation

    NASA Astrophysics Data System (ADS)

    Kovács, E.; Kiss, I.; Boros, A.; Horváth, Ny.; Tóth, J.; Gyulai, P.; Szalma, Á.

    The sensitivity of overlineTribolium confusum - small flour beetle - to radiation was studied in a dose range of 0-0.8 kGy. We found that the insect egg was the most sensitive to radiation, then larvae and pupae followed it. 0.2 kGy dose of irradiation kills these forms or their further development is inhibited. Imagoes do not immediately die after 0.8 kGy dose of irradiation; the young imagoes are more sensitive to radiation than the aged ones. 0.4 kGy average dose of irradiation is a suitable protection against overlineTribolium confusum. Disinfestation experiments were performed with wheat-germ and wheat-bran and parallelly the most important ingredients of the two products were analysed. The vitamin E content and the rate of lipid-oxidation of wheat germ were determined. The vitamin E content decreased after radiation treatment, however, during storage of at least 6 months, it remained at a level specified by food quality standards (higher than 10 mg%). Carbohydrate content of wheat-bran (water soluble carbohydrate content, crude-fibre and dietary fibre content) did not change at all. Storability of radiation disinfested wheat-germ was 8 months, wheat-bran 3-4 months. On the base of the results 2-2 tons of wheat-germ and wheat-bran were irradiated and trial marked in 1985. In 1986 the irradiation of 10 tons of wheat-germ is planned.

  3. Deformation in metals after low temperature irradiation: Part II - Irradiation hardening, strain hardening, and stress ratios

    SciTech Connect

    Byun, Thak Sang; Li, Meimei

    2008-03-01

    Effects of irradiation at temperatures 200oC on tensile stress parameters are analyzed for dozens of bcc, fcc, and hcp pure metals and alloys, focusing on irradiation hardening, strain hardening, and relationships between the true stress parameters. Similar irradiation-hardening rates are observed for all the metals irrespective of crystal type; typically, the irradiation-hardening rates are large, in the range 100 - 1000 GPa/dpa, at the lowest dose of <0.0001 dpa and decrease with dose to a few tens of MPa/dpa or less at about 10 dpa. However, average irradiation-hardening rates over the dose range of 0 dpa − (the dose to plastic instability at yield) are considerably lower for stainless steels due to their high uniform ductility. It is shown that whereas low temperature irradiation increases the yield stress, it does not significantly change the strain-hardening rate of metallic materials; it decreases the fracture stress only when non-ductile failure occurs. Such dose independence in strain hardening behavior results in strong linear relationships between the true stress parameters. Average ratios of plastic instability stress to unirradiated yield stress are about 1.4, 3.9, and 1.3 for bcc metals (and precipitation hardened IN718 alloy), annealed fcc metals (and pure Zr), and Zr-4 alloy, respectively. Ratios of fracture stress to plastic instability stress are calculated to be 2.2, 1.7, and 2.1, respectively. Comparison of these values confirms that the annealed fcc metals and other soft metals have larger uniform ductility but smaller necking ductility when compared to other materials.

  4. Degradation of poly(carbonate urethane) by gamma irradiation

    NASA Astrophysics Data System (ADS)

    Özdemir, T.; Usanmaz, A.

    2007-06-01

    Poly(carbonate urethane) (PCU), is a valuable commercial engineering polymer. In order to understand the possible use of PCU in radioactive waste management as a solidifying agent or as a disposal container, radiation stability of the PCU is studied by Co-60 gamma irradiations at two different dose rates of 1540 and 82.8 Gy/h. The total dose of irradiation was up to 6.24 MGy. Degradation nature was tested by studying the changes in mechanical and thermal properties with rate and total dose of irradiation. Ultimate tensile strength and toughness first increased and then decreased with the irradiation dose. Half value dose (HVD) for elongation was 4010 kGy and for tensile strength 6010 kGy at the dose rate of 1540 Gy/h. The non-irradiated PCU transparent color changed to yellow and then brown with increased irradiation dose. The FTIR spectral analysis showed a random scission of polymer with irradiation. From the experimental observation, it was shown that PCU can be used for embedding radioactive waste for about 300 years.

  5. Microstructure evolution in austenitic Fe-Cr-Ni alloys irradiated with rotons: comparison with neutron-irradiated microstructures

    NASA Astrophysics Data System (ADS)

    Gan, J.; Was, G. S.

    2001-08-01

    Irradiation-induced microstructures of high purity and commercial purity austenitic stainless steels were investigated using proton-irradiation. For high purity alloys, Fe-20Cr-9Ni (HP 304 SS), Fe-20Cr-24Ni and Ni-18Cr-9Fe were irradiated using 3.2 MeV protons between 300°C and 600°C at a dose rate of 7×10 -6 dpa/ s to doses up to 3.0 dpa. The commercial purity alloys, CP 304 SS and CP 316 SS were irradiated at 360°C to doses between 0.3 and 5.0 dpa. The dose, temperature and composition dependence of the number density and size of dislocation loops and voids were characterized. The changes in yield strength due to irradiation were estimated from Vickers hardness measurements and compared to calculations using a dispersed-barrier-hardening (DBH) model. The dose and temperature dependence of proton-irradiated microstructure (loops, voids) and the irradiation hardening are consistent with the neutron-data trend. Results indicate that proton-irradiation can accurately reproduce the microstructure of austenitic alloys irradiated in LWR cores.

  6. Irradiation creep of various ferritic alloys irradiated {approximately}400 C in the PFR and FFTF reactors

    SciTech Connect

    Toloczko, M.B.; Garner, F.A.; Eiholzer, C.R.

    1998-03-01

    Three ferritic alloys were irradiated in two fast reactors to doses of 50 dpa or more at temperatures near 400 C. One martensitic alloy, HT9, was irradiated in both the FFTF and PFR reactors. PFR is the Prototype Fast Reactor in Dourneay, Scotland, and FFTF is the Fast Flux Test Facility in Richland, WA. D57 is a developmental alloy that was irradiated in PFR only, and MA957 is a Y{sub 2}O{sub 3} dispersion-hardened ferritic alloy that was irradiated only in FFTF. These alloys exhibited little or no void swelling at {approximately}400 C. Depending on the alloy starting condition, these steels develop a variety of non-creep strains early in the irradiation that are associated with phase changes. Each of these alloys creeps at a rate that is significantly lower than that of austenitic steels irradiated in the same experiments. The creep compliance for ferritic alloys in general appears to be {approximately}0.5 {times} 10{sup {minus}6} MPa{sup {minus}1} dpa{sup {minus}1}, independent of both composition and starting state. The addition of Y{sub 2}O{sub 3} as a dispersoid does not appear to change the creep behavior.

  7. Radioisotope tracer study in a sludge hygienization research irradiator (SHRI).

    PubMed

    Pant, H J; Thýn, J; Zitný, R; Bhatt, B C

    2001-01-01

    A radioisotope tracer study has been carried out in a batch type sludge hygienization research irradiator with flow from top to bottom, the objective being to measure flow rate, circulation and mixing times and to investigate the hydrodynamic behaviour of the irradiator for identifying the cause(s) of malfunction. A stimulus-response technique with NH4(82)Br as a tracer was used to measure the above parameters. Experiments were carried out at three different flow rates, i.e 1.0, 0.64 and 0.33 m3/min. Three combined models based on a set of differential equations are proposed and used to simulate the measured tracer concentration curves. The obtained parameters were used to estimate dead volume and analyse hydrodynamic behaviour of the irradiator. The nonlinear regression problem of model parameter estimation was solved using the Marquardt-Levenberg method. The measured flow rate was found to be in good agreement with the values shown by the flow meter. The circulation times were found to be half of the mixing times. A simple approach for estimation of dose based on a known vertical dose-rate profile inside the irradiator is presented. About one-fourth of the volume of the irradiator was found to be dead at lower flow rates and this decreased with increase in flow rate. At higher flow rates, a semi stagnant volume was found with slow exchange of flow between the active and dead volumes. PMID:11144238

  8. Irradiation creep in austenitic and ferritic steels irradiated in a tailored neutron spectrum to induce fusion reactor levels of helium

    SciTech Connect

    Grossbeck, M.L.; Gibson, L.T.; Jitsukawa, S.

    1996-04-01

    Six austenitic stainless steels and two ferritic alloys were irradiated sequentially in two research reactors where the neutron spectrum was tailored to produce a He production rate typical of a fusion device. Irradiation began in the Oak Ridge Research Reactor where an atomic displacement level of 7.4 dpa was achieved and was then transferred to the High Flux Isotope Reactor for the remainder of the irradiation to a total displacement level of 19 dpa. Temperatures of 60 and 330{degree}C are reported on. At 330{degree}C irradiation creep was found to be linear in stress and fluence with rates in the range of 1.7 - 5.5 x 10{sup -4}% MPa{sup -1} dpa{sup -1}. Annealed and cold-worked materials exhibited similar creep rates. There is some indication that austenitic alloys with TiC or TiO precipitates had a slightly higher irradiation creep rate than those without. The ferritic alloys HT-9 and Fe-16Cr had irradiatoin creep rates about 0.5 x 10{sup -4}% MPa{sup -1} dpa{sup -1}. No meaningful data could be obtained from the tubes irradiated at 60{degree}C because of damage to the tubes.

  9. FOOD IRRADIATION REACTOR

    DOEpatents

    Leyse, C.F.; Putnam, G.E.

    1961-05-01

    An irradiation apparatus is described. It comprises a pressure vessel, a neutronic reactor active portion having a substantially greater height than diameter in the pressure vessel, an annular tank surrounding and spaced from the pressure vessel containing an aqueous indium/sup 1//sup 1//sup 5/ sulfate solution of approximately 600 grams per liter concentration, means for circulating separate coolants through the active portion and the space between the annular tank and the pressure vessel, radiator means adapted to receive the materials to be irradiated, and means for flowing the indium/sup 1//sup 1//sup 5/ sulfate solution through the radiator means.

  10. Fuel or irradiation subassembly

    DOEpatents

    Seim, O.S.; Hutter, E.

    1975-12-23

    A subassembly for use in a nuclear reactor is described which incorporates a loose bundle of fuel or irradiation pins enclosed within an inner tube which in turn is enclosed within an outer coolant tube and includes a locking comb consisting of a head extending through one side of the inner sleeve and a plurality of teeth which extend through the other side of the inner sleeve while engaging annular undercut portions in the bottom portion of the fuel or irradiation pins to prevent movement of the pins.